JP4823142B2 - Manufacturing method of semiconductor device - Google Patents

Description

  The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device in which a buried wiring such as a DRAM or a high-speed logic LSI is formed using a chemical mechanical polishing slurry.

  In recent years, in the field of semiconductor devices, devices have been miniaturized and densified, and various fine processing techniques have been researched and developed. Among these, the chemical mechanical polishing (hereinafter referred to as CMP) technique is an indispensable technique for forming fine and high-density embedded wiring (damascene wiring).

  As the CMP technique, for example, there is a metal CMP technique that can be used to form a buried wiring of a metal such as copper or aluminum. In this metal CMP technique, as will be described below, polishing rate, flatness, and scratch are important parameters for evaluating the CMP performance. That is, in order to improve the productivity of the semiconductor device, it is necessary to increase the polishing process speed (or throughput) of metal CMP. Further, in order to suppress an increase in the resistance value of the embedded wiring, it is necessary to reduce the excessive polishing amount (metal loss) of the embedded wiring called dishing or thinning (or erosion) as much as possible. Furthermore, in order to obtain a semiconductor device that operates as designed with sufficient current flowing through the embedded wiring, it is necessary to reduce the density of scratches generated in the embedded wiring as much as possible.

  These are highly dependent on the properties of the slurry and polishing pad used in CMP. For example, the CMP performance correlates with the hardness of the polishing pad and the like. Generally, a hard pad with good flatness is used as a pad in a main polish that polishes metal to form an embedded wiring.

  On the other hand, the influence of the CMP slurry on the CMP performance is derived from characteristics such as abrasive particles, oxidant, or additive contained in the slurry. Among them, the influence of the characteristics of the abrasive particles on the CMP performance is extremely large. For example, generally, the larger the size of the abrasive particles in the slurry, the higher the polishing rate.

Hereinafter, the relationship between the characteristics of the CMP slurry and the CMP performance will be described with reference to FIGS. 38 (a) and (b) and FIGS. 39 (a) and (b).
In general, the CMP slurry 7 contains a solvent 25 such as water, abrasive particles 18 such as alumina (Al ₂ O ₃ ) particles or silica (SiO ₂ ) particles, and an oxidizing agent 22. Normally, the abrasive particles 18 are aggregated in the solvent 25 of the slurry 7 to form aggregates (or secondary particles) 20 as shown in FIG. The larger the diameter of the aggregate 20, that is, the secondary particle diameter, the faster the polishing rate.

  However, when the secondary particle diameter increases, deep dishing 108 is likely to occur in the metal wiring 26 as shown in FIG. Further, when the agglomeration of the abrasive particles 18 is intense and the secondary particles 20 become excessively large, the abrasive particles 18 form coarse particles. When such coarse particles are generated, a scratch 109 is likely to occur during CMP on a metal made of a relatively soft material such as aluminum.

  On the contrary, when the degree of dispersion of the abrasive particles 18 is high as shown in FIG. 38B, it is possible to suppress the occurrence of dishing 108 in the metal wiring 26 as shown in FIG. 109 is also less likely to occur. However, when the degree of dispersion of the abrasive particles 18 is increased, the polishing rate is significantly reduced. That is, there is a trade-off between suppressing the occurrence of dishing 108 and scratch 109 and increasing the polishing rate.

  This can be explained as follows. Generally, the size (or roughness) of the unevenness of the polishing surface of the polishing pad used when performing the above-described main polishing is about 20 μm. Compared to the roughness of the polished surface, the size of the abrasive particles 18 is sufficiently small. Therefore, when the degree of dispersion of the aggregate 20 is high and the distance between the abrasive particles 18 is excessively long, the abrasive particles 18 are buried in the recesses on the surface of the polishing pad. Then, each abrasive particle 18 cannot sufficiently interact with the metal wiring 26. For this reason, when the degree of dispersion of the aggregate 20 becomes excessively high, the polishing ability of the slurry 7 is reduced, and therefore the polishing rate is significantly reduced.

  As described above, since the degree of dispersion of the abrasive particles 18 greatly affects the CMP performance, it is important to control the degree of dispersion of the abrasive particles 18 to a desired value. However, the aggregated state of the abrasive particles 18 is likely to change with time. For example, if the CMP slurry 7 is stored without being used, the number of coarse particles increases with time. That is, when the slurry 7 left for a long time is used, dishing 108 and scratch 109 are more likely to occur. Further, when the number of coarse particles increases, the coarse particles are aggregated to produce larger coarse particles. Aggregated coarse particles cannot float in the solvent 25 and settle. It is almost impossible to disperse the coarse particles once precipitated in the solvent. That is, such a slurry becomes substantially unusable.

  Further, the oxidizer 22 contained in the CMP slurry 7 is also likely to be decomposed. When the oxidizing agent 22 is decomposed, its oxidizing power is significantly reduced. The oxidizing agent 22 having a reduced oxidizing power is one of the main factors that cause deterioration in CMP performance such as a reduction in polishing rate. As described above, the deterioration of the oxidizing agent 22 with time also leads to a shortened life of the slurry 7.

  Further, the waste liquid of the CMP slurry 7 after use contains a large amount of organic substances that are difficult to decompose in the natural environment. For this reason, if the used slurry 7 is discarded without being subjected to predetermined chemical treatment (purification treatment), the natural environment may be contaminated.

  The present invention has been made in view of the above-described problems, and provides a method for manufacturing a semiconductor device using a slurry for CMP that can perform high-precision polishing at a high polishing rate and is easy to store and discard. The purpose is to do.

According to one aspect of the present invention, forming an insulating film provided with a recess on a semiconductor substrate, forming a barrier layer on the insulating film to cover a bottom surface and a side wall of the recess, and the barrier Forming a copper-containing metal layer on the layer and embedding the recess, and chemically and mechanically polishing the metal layer, the chemical mechanical polishing comprising a dispersion medium, and the dispersion medium Abrasive particles dispersed therein and exhibiting a photocatalytic action by light irradiation, dispersed in the dispersion medium, methacrylic resin, phenol resin, urea resin, melamine resin, polystyrene resin, polyacetal resin, polycarbonate resin, and at least one of them and resin particles containing a material selected from the group consisting of mixture containing species, a chemical mechanical polishing slurry containing a nonionic surface active agent onto the polishing member Supplying the light to the slurry supplied onto the polishing member, and the polishing member and the semiconductor while the slurry irradiated with the light is interposed between the polishing member and the metal layer. A method of manufacturing a semiconductor device, comprising: moving the substrate relative to the substrate, wherein the abrasive particles have a positive charge, and the resin particles have a negatively charged functional group in the molecule or are surface-treated with silica. Is provided.

In the present invention, a slurry containing abrasive particles that exhibit photocatalytic action when irradiated with light is used as the slurry for CMP. Such abrasive particles can change their oxidizing power or reducing power and / or hydrophilicity by light irradiation. Therefore, highly accurate polishing can be performed at a high polishing rate, and storage and disposal are facilitated.
That is, according to the present invention, there is provided a method for manufacturing a semiconductor device using a slurry for CMP that allows high-precision polishing at a high polishing rate and is easy to store and discard.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same referential mark is attached | subjected to the component which exhibits the same or similar function, and the overlapping description is abbreviate | omitted.

(First reference example )
FIGS. 1A and 1B are diagrams schematically showing a CMP slurry according to a first reference example . A slurry 7 for CMP shown in FIGS. 1A and 1B contains a dispersion medium 25, abrasive particles 18 dispersed in the dispersion medium 25, and an additive 22 dissolved or dispersed in the dispersion medium 25. ing. In this reference example , the additive 22 is an optional component.

  The dispersion medium 25 is a polar solvent such as water. The abrasive particles 18 exhibit a photocatalytic action when irradiated with light having a predetermined wavelength. Here, to exhibit “photocatalytic action” implies that the oxidizing power and / or reducing power of the abrasive particles 18 are changed by light irradiation, and the hydrophilicity of the abrasive particles 18 is changed by light irradiation. Suppose you are. For example, when the hydrophilicity of the abrasive particles 18 is increased by light irradiation, the slurry 7 in which the abrasive particles 18 aggregate to form the secondary particles 20 as shown in FIG. In such a dispersion medium 25, the degree of dispersion of the abrasive particles 18 is improved as shown in FIG.

  2A and 2B are cross-sectional views schematically showing an example of CMP using the slurry shown in FIGS. 1A and 1B. Here, a buried metal wiring is formed. 2A and 2B, the polishing pad, the dispersion medium 25, and the additive 22 are omitted.

  The embedded metal wiring can be formed by the following method, for example. First, an interlayer insulating film 24 such as a silicon oxide film is formed on a semiconductor substrate (or semiconductor wafer) 23 such as a silicon substrate, and then a groove is formed in the interlayer insulating film 24. Next, a conductive film (metal film) 26 containing a metal such as copper as a main component is formed on the interlayer insulating film 24 so as to fill a groove provided in the interlayer insulating film 24. As described above, as shown in FIG. 2A, the substrate 2 to be polished provided with the metal film 26 as the portion to be polished is obtained. Thereafter, the metal film 26 is subjected to CMP using the slurry 7 shown in FIGS. This CMP process is performed so that only the portion of the metal film 26 located in the groove provided in the interlayer insulating film 24 remains and the other portion is removed. Thereby, as shown in FIG. 2B, the buried metal wiring 26 is obtained. Note that it is also possible to embed and form a plug or to embed and form a wiring and a plug at the same time by a method similar to this.

  The CMP process described above includes a chemical reaction between components in the slurry 7 and the surface of the metal layer 26, and physical removal of reaction products and the like from the surface of the metal layer 26 by the abrasive particles 18 in the slurry 7. Is used. Therefore, by appropriately irradiating the slurry 7 with light during the polishing, it is possible to control the reactivity such as the polishing power of the abrasive particles 18 and / or the oxidizing power of the slurry 7, and thus the desired CMP performance. Can be realized.

  For example, in the case where the abrasive particles 18 of the slurry 7 used in the CMP process are those whose degree of dispersion is changed by light irradiation, the intensity of light applied to the slurry 7 on the metal film 26 during the CMP process is increased. Accordingly, the particle diameter of the secondary particles 20 formed by the abrasive particles 18 can be controlled. That is, a desired polishing accuracy and a desired polishing rate can be realized in accordance with the intensity of light applied to the slurry 7 on the metal film 26 during the CMP process. Further, in the case where the abrasive particles 18 of the slurry 7 used in the above CMP treatment are those whose oxidative power is changed by light irradiation, the oxidant capable of controlling the oxidative power of the abrasive particles 18 according to the intensity of irradiated light. Can also be used. Therefore, also in this case, a desired polishing accuracy and a desired polishing rate can be realized according to the intensity of light applied to the slurry 7 on the metal film 26 during the CMP process.

In the present reference example , the metal layer 26 that is a portion to be polished contains a metal as a main component as described above. Examples of such metals include metals such as aluminum, copper, tungsten, titanium, molybdenum, niobium, tantalum, and vanadium; alloys containing at least one of these metals as a main component; at least one of these metals Nitride containing seed as a main component; Boride containing as a main component at least one of these metals; Oxide containing as a main component at least one of these metals; A metal compound containing one kind as a main component and further containing at least two kinds of nitrogen, boron, and oxygen can be given. The metal layer 26 may have a single layer structure or may have a laminated structure.

In this reference example , when the abrasive particles 18 of the slurry 7 are those whose degree of dispersion is changed by light irradiation, the abrasive particles 18 may be those whose degree of dispersion is increased by light irradiation. Further, when the abrasive particles 18 of the slurry 7 are those that change their oxidizing power by light irradiation, the abrasive particles 18 may increase their oxidizing power by light irradiation. Further, when the abrasive particles 18 of the slurry 7 change both the degree of dispersion and the oxidizing power by light irradiation, the abrasive particles 18 can increase both the degree of dispersion and the oxidizing power by light irradiation. Good.

  Examples of the abrasive particles 18 exhibiting the photocatalytic action described above include particles containing any of titanium oxide, tin oxide, niobium oxide, cadmium selenide, and cadmium sulfide.

  The slurry 7 can contain an oxidizing agent as the additive 22. Examples of such an oxidizing agent include those having a standard electrode potential of −3.0 V to +3.0 V, such as hydrogen peroxide, ammonium peroxodisulfate, phosphoric acid, nitric acid, and ammonium cerium nitrate. . Moreover, when the slurry 7 contains an oxidizing agent, the content is usually 0.1 wt% to 5.0 wt%.

  Further, when the abrasive particles 18 exhibit an oxidizing power by light irradiation, the slurry 7 may not contain an oxidizing agent as the additive 22. However, in order to use the oxidizing power of the abrasive particles 18 more effectively, the slurry 7 is used with a pH adjuster such as an inorganic acid such as nitric acid, phosphoric acid, hydrochloric acid or sulfuric acid, depending on the type of the abrasive particles 18 used. It is desirable to adjust the pH of the solution appropriately.

  The primary particle diameter A of the abrasive particles 18 is preferably distributed within a range of 5 nm to 1000 nm, and more preferably within a range of 5 nm to 20 nm. The secondary particle diameter B of the abrasive particles 18 is preferably distributed within a range of 100 nm to 1000 nm. This will be described with reference to FIG.

  FIG. 3 is a graph showing the relationship between the particle size of the abrasive particles and the sedimentation speed. In the figure, the horizontal axis indicates the primary particle diameter A and the secondary particle diameter B of the abrasive particles 18, and the vertical axis indicates the sedimentation rate of the abrasive particles 18 as primary particles and the secondary particles 20 that are aggregates of the abrasive particles 18. The sedimentation rate is shown.

  As shown in FIG. 3, when the particle diameters of the abrasive particles 18 made of titanium oxide or the like and the secondary particles 20 thereof exceed about 1000 nm, the sedimentation speed is remarkably increased. When the settling speed of the abrasive particles 18 or the secondary particles 20 is high, it becomes difficult to maintain them in a dispersed state. That is, there is a possibility that the abrasive particles 18 or the secondary particles 20 thereof are settled to form a precipitate. Since the abrasive particles 18 constituting the precipitate interact strongly with each other, it is almost impossible to disperse them in the dispersion medium 25 again. Generation of such a precipitate can be suppressed by setting the particle size of the abrasive particles 18 and the secondary particles 20 to 1000 nm or less.

  As shown in FIG. 3, when the primary particle diameter A of the abrasive particles 18 is less than about 5 nm, the sedimentation speed is remarkably increased. This is because when the primary particle diameter A of the abrasive particles 18 is less than about 5 nm, the Brownian motion of the particles 18 becomes intense. That is, when the Brownian motion of the abrasive particles 18 becomes intense, the probability that they collide with each other increases, and the probability that they bond with each other also increases. For these reasons, when the primary particle diameter A of the abrasive particles 18 is less than about 5 nm, the sedimentation speed thereof is remarkably increased, and therefore precipitates are easily generated.

  In many cases, in the slurry 7, some of the abrasive particles 18 are present as primary particles, and the rest are aggregated and exist as secondary particles 20. Therefore, in such a case, in order to make both the primary particle diameter and the secondary particle diameter of the abrasive particles 18 within the above range, the primary particle diameter of the abrasive particles 18 must be distributed within a range of 5 nm to 100 nm. Is preferable, and it is more preferable that the distribution is within a range of 5 nm to 20 nm. When the primary particle diameter of the abrasive particles 18 is distributed within such a range, the secondary particle diameter of the abrasive particles 18 can be distributed within a range of, for example, 100 nm to 1000 nm.

  The distribution of the primary particle diameter of the abrasive particles 18 described above can be examined, for example, by observing a TEM image of the abrasive particles 18. Similarly, the secondary particle size distribution of the abrasive particles 18 can also be examined, for example, by observing a TEM image of the abrasive particles 18 or by a particle size measurement method using a principle such as the Stokes method. .

As described above, in this reference example , the oxidizing power and / or reducing power of the abrasive particles 18 are changed by light irradiation, and / or the hydrophilicity of the abrasive particles 18 is changed by light irradiation. The photocatalytic action of the abrasive particles 18 is used. While not wishing to be bound by theory, it is believed that such photocatalysis is based on the following principle. An example in which the abrasive particles 18 are titanium oxide particles and pure water is used as the dispersion medium 25 will be described.

  The change in the hydrophilicity of the abrasive particles 18 due to light irradiation is considered to occur on the following principle. That is, when the titanium oxide particles 18 are irradiated with ultraviolet rays, holes are generated at the positions of titanium atoms constituting the titanium oxide particles 18. The holes generated at the position of the titanium atoms take electrons from the oxygen atoms constituting the titanium oxide particles 18. Thereby, oxygen atoms are oxidized. While the titanium oxide particles 18 are irradiated with ultraviolet rays, at least some of the oxygen atoms located on the surface of the titanium oxide particles 18 are deprived of electrons, and water molecules constituting the dispersion medium 25 are adsorbed thereto. . The surface of the titanium oxide particles 18 on which water molecules are adsorbed functions as a hydrophilic domain. Based on such a principle, it is considered that the hydrophilicity of the titanium oxide particles 18 is increased by ultraviolet irradiation.

On the other hand, the change in the oxidizing power of the abrasive particles 18 due to light irradiation is considered to occur on the following principle. A part of the holes generated on the surface of the titanium oxide particles 18 by the ultraviolet irradiation constitutes the metal layer 26 when the titanium oxide particles 18 are in contact with the metal layer 26 or located in the very vicinity. Takes electrons from the metal atoms. Further, another part of the holes generated on the surface of the titanium oxide particles 18 by the ultraviolet irradiation takes electrons from the hydroxy ions contained in the water constituting the dispersion medium 25, and the generated hydroxy radical is a metal The electrons are taken from the metal atoms constituting the layer 26. Note that a metal atom such as a copper atom from which electrons have been removed quickly forms an oxide such as CuO _x . Thus, since the oxidizing power of the abrasive particles 18 is brought about by the holes generated by the ultraviolet irradiation, the oxidizing power of the abrasive particles 18 can be changed by changing the intensity of the ultraviolet light irradiated to the titanium oxide particles 18. it can.

  When such photocatalytic action of the abrasive particles 18 is used, CMP can be performed by various methods. For example, the intensity of light applied to the slurry 7 may be constant during CMP. Alternatively, the intensity of light applied to the slurry 7 may be changed during CMP. In the latter case, for example, the slurry 7 is not irradiated with light at the initial stage of CMP, but light is applied to the slurry 7 just before the CMP is completed, or the slurry 7 is irradiated with weak light at the initial stage of CMP. The intensity of light applied to the slurry 7 may be increased just before ending. According to such a method, polishing can be performed at a high polishing rate at the initial stage of CMP, and high-precision polishing can be performed immediately before the completion of CMP. Therefore, the polishing rate can be further increased, and the occurrence of dishing, erosion, and scratches can be more effectively suppressed.

  When particles containing titanium oxide are used as the abrasive particles 18, titanium oxide having any crystal structure of anatase type, rutile type, or brookite type may be used as the titanium oxide. However, among them, it is preferable to use anatase type titanium oxide. This will be described with reference to FIGS. 4A to 4C and FIG.

  FIGS. 4A to 4C are diagrams showing the crystal structures of anatase type, rutile type, and brookite type titanium oxide, respectively. FIG. 5 is a diagram showing an energy band of titanium oxide. 4A to 4C, reference numeral 27 indicates a titanium atom, and reference numeral 28 indicates an oxygen atom.

  As the crystal structure of natural titanium oxide, anatase type, rutile type and brookite type shown in FIGS. 4 (a) to (c) are known. Among these, those utilized for industrial use are mainly anatase-type titanium oxide shown in FIG. 4 (a) and rutile-type titanium oxide shown in FIG. 4 (b). With respect to the brookite-type titanium oxide shown in FIG. 4C, research for practical use is currently underway.

  The ability of the above-described titanium oxide as a photocatalyst is different among anatase type, rutile type and brookite type. For example, anatase-type titanium oxide exhibits higher photocatalytic activity than rutile-type titanium oxide. This is because the energy bands are different between them as shown in FIG.

  The titanium oxide 18 generates light in the conduction band and holes in the valence band by absorbing light having energy equal to or higher than the band gap, which is the energy difference between the valence band and the conduction band. As shown in FIG. 3, the band gap of anatase type titanium oxide is about 3.2 eV, and the band gap of rutile type titanium oxide is about 3.0 eV. Both anatase type titanium oxide and rutile type titanium oxide absorb almost only ultraviolet rays, as is apparent from the respective band gap values. However, rutile titanium oxide can also absorb light in a wavelength range slightly closer to visible light than ultraviolet light.

  Thus, the rutile type titanium oxide that can absorb light in a wider wavelength range seems to have a higher ability as a photocatalyst than the anatase type titanium oxide. However, in fact, anatase-type titanium oxide exhibits higher photocatalytic activity than rutile-type titanium oxide. This is due to the following reason.

  As shown in FIG. 5, the energy levels of the valence band of anatase-type titanium oxide and rutile-type titanium oxide are both very deep. Therefore, all of the holes generated when these titanium oxides absorb light have sufficient oxidizing power. Specifically, as shown in FIG. 5, the oxidizing power of holes of these titanium oxides is much stronger than the oxidizing power of hydrogen peroxide which is general as an oxidizing agent.

On the other hand, the energy levels of the conduction bands of anatase type and rutile type titanium oxide are both close to the redox potential of hydrogen (H ⁺ , H ₂ ), as shown in FIG. Therefore, any of these titanium oxides has a relatively weak reducing power. However, the energy level of the conduction band of anatase-type titanium oxide is in a more negative position than the energy level of the conduction band of rutile-type titanium oxide. Therefore, the reducing power of anatase type titanium oxide is stronger than the reducing power of rutile type titanium oxide. For these reasons, anatase-type titanium oxide is considered to exhibit higher photocatalytic activity than rutile-type titanium oxide.

  In addition, it has been found that the brookite-type titanium oxide shown in FIG. 4C has a considerably high photocatalytic activity. It has also been found that the band gap is about 3.2 eV. Therefore, even when the abrasive particles 18 containing brookite-type titanium oxide are used, there is a possibility that a photocatalytic action equivalent to that when using an anatase-type titanium oxide-containing material is obtained.

  The abrasive particles 18 containing titanium oxide exhibit a photocatalytic action by absorbing ultraviolet light having a wavelength of about 380 nm or less among ultraviolet light having a wavelength range of 200 nm to 400 nm. Further, the photocatalytic action of the abrasive particles 18 containing titanium oxide becomes stronger as the wavelength of the irradiated ultraviolet rays becomes shorter.

Next, a CMP apparatus that can use the above-described slurry 7 will be described.
FIG. 6 is a diagram schematically showing an example of a CMP apparatus that can use the slurry shown in FIGS. 1 (a) and 1 (b). The CMP apparatus 1 includes a housing 19 that houses a head (or carrier) 3 that is a substrate holder, a turntable 6 that is a polishing jig, and a slurry supply device 8. Yes.

  The head 3 is rotatably attached to the head driving device 11, and holds the substrate 2 to be polished from the back side of the surface to be polished. The turntable 6 is rotatably attached to a table driving device 15 so as to face the head 3, and a polishing pad (or polishing cloth) 5 as a polishing member is detachably held on the surface facing the head 3. is doing. The slurry supply device 8 is configured to supply the slurry 7 onto the polishing pad 5 from the supply nozzle 8a. The head driving device 11 and the table driving device 15 constitute a driving mechanism.

  The head driving device 11 and the table driving device 15 each have a built-in head sensor 12 and a table sensor 16. The head sensor 12 detects the driving state of the head 3 such as a load applied to the head 3 (rotational shaft torque and / or axial load of the head 3), a rotational speed of the head 3, and the like. Further, the table sensor 16 detects the driving state of the turntable 6 such as a load applied to the table 6 due to frictional force during polishing (rotating shaft torque of the table 6), a rotational speed of the table 6, and the like. To do. The sensors 12 and 16 are electrically connected to the control device 14 via A / D converters 13 and 17, respectively.

  The control device 14 is electrically connected to the slurry supply device 8, the head driving device 11, and the table driving device 15. The control device 14, for example, based on signals from the sensors 12 and 16 and a preset program, the load applied to the head 3, the rotational speed of the head 3, the rotational speed of the table 6, and the supply amount of the slurry 7. And supply frequency are appropriately controlled.

  The CMP apparatus 1 further includes a light irradiation device 10 such as an ultraviolet lamp. The light irradiation device 10 irradiates the slurry 7 on the polishing pad 5 with light that can induce the photocatalytic action of the abrasive particles 18, for example, ultraviolet rays. The light irradiation device 10 is electrically connected to the control device 14, and controls ON / OFF of the light irradiation device 10, intensity of light emitted from the light irradiation device 10, a spectrum of light emitted from the light irradiation device 10, and the like. It can be controlled by the device 14. For example, the control device 14 may be configured to switch the irradiation / non-irradiation of the light according to the rotational shaft torque of the head 3 or the turntable 6.

  In this CMP apparatus 1, the casing 19 plays a role of preventing the slurry 7 from scattering to the outside during polishing and the dust 7 and dust in the atmosphere from being mixed into the slurry 7. In addition, it is preferable that the housing 19 is configured to prevent a light beam outside the CMP apparatus 1 from inducing an undesired photocatalytic action on the slurry 7 and the alteration of the slurry 7. That is, the housing 19 is preferably light-shielding against light that induces the photocatalytic action of the slurry 7.

When this CMP apparatus 1 is used, for example, CMP can be performed by the method described below.
FIG. 7 is a graph showing an example of the relationship between the polishing time and the load applied to the table 6 that can be observed during CMP using the CMP apparatus 1 shown in FIG. In the figure, the horizontal axis represents the polishing time, and the vertical axis represents the torque detected by the table sensor 16 as the output current value from the sensor 16.

  The polishing state of the substrate 2 to be polished can be estimated from a deviation between the set value of the rotational speed of the turntable 6 and the measured value and / or the rotational shaft torque of the turntable 6. Similarly, the polishing state of the substrate to be polished 2 can be estimated from the deviation between the set value of the rotational speed of the head 3 and the actual measurement value and / or the rotational shaft torque of the head 3 and the like. For example, when the control is performed so that the actual rotation speed of the head 3 or the turntable 6 is equal to the set value, the motor current value (or table current value) of the table driving device 15 is as shown in FIG. It changes according to the progress of polishing. Therefore, when the metal layer 26 shown in FIG. 2A is planarized, the table current value is monitored to detect when the upper surface of the insulating film 24 is exposed as shown in FIG. You can know polish, etc. Whether the polishing is completed can be estimated by monitoring the table current value.

  In this way, the progress of polishing can be estimated by monitoring the table current value. Therefore, for example, light irradiation by the light irradiation device 10 is not performed until reaching the just polish, and light irradiation by the light irradiation device 10 to the slurry 7 on the polishing pad 5 can be started at the time of just polishing. When the degree of dispersion of the abrasive particles 18 in the slurry 7 is increased by light irradiation using the light irradiation device 10, the polishing rate is higher in non-irradiation than in irradiation, and the polishing accuracy is higher in irradiation than in non-irradiation. high. Therefore, if the irradiation / non-irradiation of light is switched as described above, it is possible to achieve both high levels of suppressing the occurrence of dishing, erosion, scratches, etc. and shortening the polishing time.

  FIG. 8 is a diagram showing an example of CMP performance that can be realized when such a method is adopted. In the figure, circles indicate data obtained when titania particles are used as abrasive particles and light irradiation / non-irradiation is switched during CMP as described above. Further, square marks and triangle marks indicate data obtained when only alumina particles or silica particles are used as the abrasive particles, and more specifically, the former formed secondary particles with coarse abrasive particles. The latter shows the data when the abrasive particles did not substantially form secondary particles. In FIG. 8, the polishing rate is given a larger number when the polishing time is shorter. In FIG. 8, the scratch density is given a larger number when the scratch is generated at a lower density. Further, in FIG. 8, a larger number is given to the flatness when the degree of dishing or erosion is smaller.

  As shown in FIG. 8, when the abrasive particles are alumina particles or silica particles, the degree of dispersion of the abrasive particles cannot be changed during CMP. For this reason, when the abrasive particles form coarse secondary particles, the polishing rate is extremely high, but scratches are extremely generated and the flatness is extremely low. In addition, when the degree of dispersion of the abrasive particles is high, the frequency of occurrence of scratches is extremely low and the flatness is extremely high, but the polishing rate is extremely low.

  On the other hand, when titania particles are used as the abrasive particles, the degree of dispersion and the oxidizing power of the abrasive particles can be changed by switching light irradiation / non-irradiation during CMP. Therefore, when light irradiation / non-irradiation is switched during CMP as described above, the polishing rate is extremely high, the frequency of occurrence of scratches is extremely low, and the flatness can be extremely high. Accordingly, it is possible to simultaneously realize a high polishing rate, high flatness, low erosion, and low defect density (scratch-free).

(Second reference example )
The second reference example is the same as the first reference example except that the light irradiation method during CMP is different.

FIGS. 9A and 9B are cross-sectional views schematically showing an example of CMP according to the second reference example . Here, the embedded metal wiring is formed using the CMP slurry 7 described with reference to FIGS. 1A and 1B in the first reference example . 9A and 9B, the polishing pad, the dispersion medium 25, and the additive 22 are omitted.

In this reference example , for example, a buried metal wiring is formed by the following method. First, the substrate to be polished 2 shown in FIG. 9A is obtained by the same method as described in the first reference example . Next, the metal film 26 is subjected to a CMP process using the same slurry 7 used in the first reference example . During this CMP process, the substrate to be polished 2 is continuously irradiated with light such as ultraviolet rays that can induce the photocatalytic action of the slurry 7 from the back side of the surface to be polished.

  At the initial stage of CMP, as shown in FIG. 9A, the light irradiated on the back surface of the surface to be polished is reflected by the metal layer 26 and therefore reaches the slurry 7 interposed between the polishing pad and the substrate 2. do not do. Therefore, when the abrasive particles 18 are those whose degree of dispersion is increased by light irradiation, polishing proceeds at a relatively high speed.

  When the polishing proceeds to almost just polish, as shown in FIG. 9B, most of the light irradiated to the back surface of the surface to be polished can reach the slurry 7 interposed between the polishing pad and the substrate 2. Become. Therefore, the degree of dispersion of the abrasive particles 18 is increased. As a result, the polishing rate is reduced and more accurate polishing is performed.

As described above, in the second reference example , the metal layer 26 serves as a shutter or a switch for controlling irradiation / non-irradiation of light. Therefore, there is no need to electrically control irradiation / non-irradiation. Note that light irradiation may be started at any time during under-polishing based on the elapsed time from the start of polishing, the table current value, or the like without irradiating light at the initial stage of polishing.

In the second reference example , as described above, the slurry 7 interposed between the polishing pad and the substrate 2 is irradiated with light. Therefore, the degree of dispersion and oxidizing power of the abrasive particles 18 in the plane of the substrate 2 can be made more uniform and / or higher.

For the above-described CMP, for example, a CMP apparatus 1 shown in FIG. 6 partially modified can be used.
FIG. 10 is a cross-sectional view schematically showing a head of a CMP apparatus that can be used in the second reference example . A suction chamber 32 is provided inside the head 31. The suction chamber 32 is connected to a suction device and a pressure adjustment valve (not shown) through a ventilation path 34. In addition, a wafer chuck film (backing film) 35 made of an elastic body provided with suction holes 36 is attached to the head 31 so as to close the opening of the suction chamber 32. In the head 31 shown in FIG. 10, the substrate 2 can be sucked and held by such a configuration.

  The head 31 further includes a light irradiation device 33 such as an ultraviolet lamp inside the suction chamber 32. The light irradiation device 33 can emit light toward the substrate 2 through a suction hole 36 provided in the film 35 as indicated by a solid arrow.

  By using the above-described head 31 instead of the head 3 in the CMP apparatus 1 shown in FIG. 6, the CMP described with reference to FIGS. 9A and 9B can be performed. In addition, when using the head 31 mentioned above instead of the head 3, the CMP apparatus 1 does not need to be equipped with the light irradiation apparatus 10. FIG. Further, the light irradiation device 33 of the head 31 may be electrically connected to the control device 14 or may not be connected.

(Third reference example )
In the first and second reference examples, it is mainly explained that the change in the degree of photocatalytic action of the abrasive particles 18 is changed during CMP by mainly using the change in dispersion degree due to light irradiation as the photocatalytic action of the abrasive particles 18. did. On the other hand, in the third reference example , CMP is performed mainly using the oxidizing power that is generated by light irradiation as the photocatalytic action of the abrasive particles 18.

FIGS. 11A and 11B are cross-sectional views schematically showing an example of CMP according to the third reference example . Here, the embedded metal wiring is formed using the CMP slurry 7 described with reference to FIGS. 1A and 1B in the first reference example . In FIGS. 11A and 11B, the polishing pad, the dispersion medium 25, and the additive 22 are omitted.

In this reference example , for example, a buried metal wiring is formed by the following method. First, the substrate 2 to be polished is obtained by the same method as described in the first reference example . Next, using the same slurry 7 used in the first reference example , the metal film 26 is subjected to a CMP process as shown in FIGS. During this CMP, the slurry 7 supplied onto the polishing pad is continuously irradiated with light such as ultraviolet rays that can induce its photocatalytic action.

When the abrasive particles 18 increase their dispersity and oxidizing power by light irradiation, the abrasive particles 18 continue to maintain a high dispersity while irradiating light. Therefore, the abrasive particles 18 do not form large secondary particles. Therefore, the polishing power of the abrasive particles 18 remains relatively low during light irradiation. In this case, as described in the first and second reference examples, it is considered that the polishing rate is significantly reduced.

  However, if the intensity of light applied to the slurry 7 is sufficiently strong and the abrasive particles 18 and the surface to be polished can be brought into sufficient contact, the abrasive particles 18 can be used as an oxidizing agent. Therefore, the ability of the slurry 7 to oxidize the surface of the metal layer 26 is significantly improved. This means that the formation of a fragile oxide 43 that is easier to polish than metal is promoted. Therefore, even if the mechanical polishing power of the abrasive particles 18 is low, a sufficient polishing rate can be realized.

  Further, since the abrasive particles 18 do not form large secondary particles during CMP, dishing and erosion can be suppressed, and generation of scratches can be suppressed.

  Moreover, the oxidation of the surface of the metal layer 26 by the abrasive particles 18 mainly occurs when the abrasive particles 18 and the metal layer 26 are in contact with each other, and almost occurs when the abrasive particles 18 and the metal layer 26 are separated from each other. Absent. Therefore, high flatness can be realized. This will be described with reference to FIGS.

  12 is a cross-sectional view showing a state between the state shown in FIG. 11A and the state shown in FIG. In FIG. 12, the dispersion medium 25 and the additive 22 are omitted as in FIGS. 11A and 11B, but the polishing pad 5 is drawn.

  As shown in FIG. 12, during CMP, the polishing pad 5 is deformed along a groove on the surface to be polished. Therefore, the inner wall and bottom surface of the groove are also polished. However, as described above, oxidation of the surface of the metal layer 26 by the abrasive particles 18 hardly occurs when the abrasive particles 18 and the metal layer 26 are separated from each other. Since the polishing pad 5 is not deformed as the abrasive particles 18 are strongly pressed against the inner wall and bottom surface of the groove, the oxide film 43 is less likely to be formed on the inner wall and bottom surface of the groove than the upper surface of the metal layer 26. That is, the inner wall and bottom surface of the groove are maintained in a state that is difficult to be polished. Therefore, polishing of the inner wall and bottom surface of the groove can be suppressed, and the upper surface of the metal layer 26 can be selectively polished. Therefore, high flatness can be realized.

FIG. 13 is a graph showing the relationship between the width of the embedded wiring and the flatness. In the figure, the horizontal axis indicates the width of the wiring 26 and the vertical axis indicates the depth of the groove on the surface to be polished of the substrate 2 to be polished. Note that the data shown in FIG. 13 was obtained under the following conditions. That is, as the CMP slurry 7, a slurry containing anatase-type titanium oxide particles 18 having a primary particle diameter of about 20 nm at a concentration of about 3% by weight was used. Further, IC1000 / Suba400 was used as the polishing cloth (polishing pad). During CMP, a 500 W mercury lamp is kept on, the load is about 2.9 N / m ² (300 gf / cm ² ), the rotation speed of the head 3 is about 100 rpm, the rotation speed of the turntable is about 100 rpm, and the slurry flow rate is 200 cc. / Min. Under such conditions, a copper embedded wiring (Cu damascene wiring) 26 was formed.

As shown in FIG. 13, according to the method according to this reference example , high flatness can be realized at the time of just polishing. In addition, high flatness is maintained even at the time of over-polishing after 60% polishing from the just-polished. As described above, according to the present reference example , it is not necessary to control the polishing stop timing with high accuracy in order to achieve high flatness.

  When the abrasive particles 18 and the metal layer 26 are separated from each other, the fact that the surface oxidation of the metal layer 26 by the abrasive particles 18 hardly occurs is useful in various steps of the semiconductor device manufacturing process.

FIG. 14A is a cross-sectional view schematically showing another example of CMP according to the third reference example . FIG. 14B is a cross-sectional view schematically showing an example of CMP according to the prior art. Note that the structure shown in FIGS. 14A and 14B includes multilayer wiring. That is, an interlayer insulating film 24a is formed on a semiconductor substrate 23 such as a Si substrate, and a groove is provided in the insulating film 24a. This groove is filled with a metal layer 26a mainly composed of a metal such as Cu, and this metal layer 26a constitutes a lower layer wiring. A barrier layer 30a such as a TaN layer is provided on the bottom surface, side wall, and top surface of the metal layer 26a. An interlayer insulating film 24b is formed on the insulating film 24a, and via holes and grooves are provided in the interlayer insulating film 24b. These via holes and grooves are filled with a metal layer 26b containing a metal such as Cu as a main component, and the metal layer 26b constitutes an upper layer wiring and a via plug. A barrier layer 30b such as a WN layer formed by a CVD method, for example, is provided on the side surface of the portion constituting the plug of the metal layer 26b and the bottom and side walls of the portion constituting the upper layer wiring. Here, the WN layer means a layer mainly composed of tungsten nitride.

  By the way, in the above-described upper layer wiring and via plug, a barrier layer 30b such as a WN layer is formed on the surface of the insulating film 24b provided with a via hole and a trench by a CVD method or the like, and then the via hole and trench are formed as a metal such as a Cu layer. It is obtained by embedding with the layer 26b and further polishing by CMP until the upper surface of the insulating film 24b is exposed. A material used for the barrier layer 30b such as WN is more easily etched with an oxidizing agent such as an organic acid than a material used for the metal layer 26b such as Cu. Therefore, at the time of the CMP, in the prior art, as shown in FIG. 14B, the portion interposed between the metal layer 26b and the insulating film 24b of the barrier layer 30b is etched, and the metal layer 26b is peeled off. It becomes easy.

In the method according to this reference example , as described above, when the abrasive particles 18 and the metal layer 26b are separated from each other, the surface oxidation of the metal layer 26b by the abrasive particles 18 hardly occurs. Since the abrasive particles 18 are much larger than the oxidizing agent, it is difficult to penetrate between the metal layer 26b and the insulating film 24b. Therefore, if the method according to this reference example is used in the CMP for forming the upper layer wiring and the via plug, as shown in FIG. 14A, the gap between the metal layer 26b of the barrier layer 30b and the insulating film 24b is obtained. It is possible to suppress etching of the portion interposed in the film. Accordingly, it is possible to make it difficult for the metal layer 26b to be peeled off.

As described above, in this reference example , the high oxidizing power obtained by irradiating the abrasive particles 18 with light is used. The principle of changing the oxidizing power of the abrasive particles 18 by light irradiation has been briefly described in the first reference example , but here, the case where the abrasive particles 18 are titanium oxide particles will be described in more detail as an example.

FIG. 15 is a diagram showing an energy band of titanium oxide.
Titanium oxide is a kind of n-type semiconductor. Therefore, in the slurry 7, electrons move from the surface of the titanium oxide particles 18 to the electrolytic solution containing the water 25 and the acid 22. As a result, as shown in FIG. 15, the energy band of the surface of the titanium oxide particles 18 increases by ΔV. That is, in the vicinity of the surface of the titanium oxide particles 18 in the slurry 7 in the equilibrium state, the following equation:
ΔV = 2πn ₀ / κ · L ²
A band bend (Schottoky barrier) having a magnitude of ΔV shown in FIG. In the above equation, n ₀ represents the donor level concentration, κ represents the dielectric constant, and L represents the barrier height.

As described in the first reference example , when anatase-type titanium oxide is irradiated with ultraviolet rays having energy of about 3.2 eV or more, the valence band is directed to the conduction band as shown by the white arrow in the figure. Electrons are excited. Then, the same number of holes as the excited electrons are generated in the valence band of titanium oxide. Holes drift towards the lower potential side along the band bend. Further, the excited electrons drift toward the higher potential side along the band bend. At this time, on the surface of the titanium oxide particles 18, the following reaction formula:
OH ^{- +} h + → · OH
The chemical reaction indicated by

As shown in this reaction formula, hydroxy ions (OH ⁻ ) are oxidized by holes, and hydroxy radicals (.OH) having extremely strong oxidizing power are generated. The increase in the oxidizing power of titanium oxide by light irradiation is generally considered to be based on the above principle.

The oxidizing power of the titanium oxide particles 18 described above correlates with the primary particle diameter, as will be described below. As described above, the holes generated by irradiating the titanium oxide particles 18 with light move toward the particle surface. However, since ΔV is proportional to L ² , ΔV becomes very small when the primary particle diameter of the titanium oxide particles 18 is less than about 5 nm. For this reason, a driving force sufficient to move holes to the particle surface cannot be obtained. Moreover, when the primary particle diameter of the titanium oxide particles 18 exceeds about 100 nm, the time until the holes reach the particle surface becomes long and the probability of recombination with electrons increases. Therefore, in this case, fewer holes can reach the surface of the titanium oxide particles 18. Therefore, when the titanium oxide particles 18 are used as an oxidizing agent, the primary particle diameter of the titanium oxide particles 18 is preferably distributed within a range of about 5 nm to about 100 nm.

  Further, as described above, in order to use the abrasive particles 18 as an oxidant, it is necessary that the intensity of light applied to the slurry 7 is sufficiently strong. This will be described with reference to FIG.

  FIG. 16 is a graph showing the relationship between the intensity of light applied to the slurry and the polishing rate. In the figure, the horizontal axis indicates the irradiation light intensity, and the vertical axis indicates the polishing rate. The data shown in FIG. 16 is obtained when the copper embedded wiring (Cu damascene wiring) 26 is formed by the CMP method under substantially the same conditions as described with reference to FIG.

  As shown in FIG. 16, the higher the irradiation light intensity of ultraviolet rays, the higher the polishing rate. Further, when the slurry 7 was not irradiated with ultraviolet rays during Cu-CMP, the polishing rate of the Cu layer 26 was about 45 nm / min. On the other hand, when the slurry 7 was continuously irradiated with ultraviolet rays using a 30 W fluorescent lamp during Cu-CMP, the polishing rate of the Cu layer 26 was about 450 nm / min. That is, the polishing rate could be improved up to about 10 times. Further, when the slurry 7 was continuously irradiated with ultraviolet rays using a 500 W mercury lamp containing more ultraviolet rays during the Cu-CMP, the polishing rate of the Cu layer 26 was about 750 nm / min.

FIG. 16 also shows data related to CMP of the Al layer and data related to the SiO ₂ layer in addition to data related to CMP of the Cu layer. As is clear from these data, the highest polishing rate could be achieved when the layer to be polished was a Cu layer compared to when the layer to be polished was an Al layer or a SiO ₂ layer.

  FIGS. 17A and 17B are graphs showing the relationship between the intensity of light applied to the slurry and the polishing rate, respectively, obtained when alumina particles and silica particles are used as the abrasive particles. In the figure, the horizontal axis indicates the irradiation light intensity, and the vertical axis indicates the polishing rate. Note that the data shown in FIGS. 17A and 17B are obtained when CMP is performed under the same conditions as those described with reference to FIG. 16 except that alumina particles and silica particles are used as the abrasive particles. It is obtained.

  As shown in FIG. 17A, when alumina particles were used as the abrasive particles 18, the effect of increasing the polishing rate by ultraviolet irradiation was hardly obtained. Also, as shown in FIG. 17B, when silica particles were used as the abrasive particles 18, the effect of increasing the polishing rate by ultraviolet irradiation was hardly obtained. This is because both alumina and silica are insulators and their band gap is larger than the energy of ultraviolet rays.

  As described above, when the abrasive particles 18 are used as an oxidizing agent, the polishing rate correlates with the intensity of light applied to the slurry 7. However, when the abrasive particles 18 are used as an oxidizing agent, it is not only the intensity of light applied to the slurry 7 that affects the polishing rate. For example, the concentration of the abrasive particles 18 in the slurry 7 and the pH of the slurry 7 also affect the polishing rate.

  FIG. 18 is a graph showing the relationship between the concentration of the abrasive particles 18 in the slurry 7 and the polishing rate. In the figure, the horizontal axis indicates the concentration of the abrasive particles 18 in the slurry 7, and the vertical axis indicates the polishing rate. Further, the data shown in FIG. 18 is obtained under substantially the same conditions as described with reference to FIG. 13 except for the concentration of the abrasive particles 18 in the slurry 7.

  As shown in FIG. 18, when the concentration of the abrasive particles 18 in the slurry 7 is in the range of about 0.1 wt% to about 10 wt%, a higher polishing rate is obtained as the concentration of the abrasive particles 18 is increased. Yes. In particular, when the concentration of the abrasive particles 18 in the slurry 7 was about 1% by weight or more, a polishing rate of about 300 nm / min or more could be realized.

  FIG. 19 is a graph showing the relationship between the pH of the slurry 7 and the polishing rate. In the figure, the horizontal axis indicates the pH of the slurry 7 and the vertical axis indicates the polishing rate. Further, the data shown in FIG. 19 is obtained under substantially the same conditions as described with reference to FIG. 13 except for the pH of the slurry 7.

As shown in FIG. 19, when the pH of the slurry 7 is about 8 or less, the lower the pH, the higher the polishing rate is obtained. In particular, when the pH of the slurry 7 was about 5 or less, which is the isoelectric point of the titanium oxide particles 18, a polishing rate of about 600 nm / min or more could be realized. Note that when the pH of the slurry 7 is higher than about 7, the polishing rate is remarkably low. This is because a Cu (OH) _x film that is difficult to be polished is formed on the surface of the Cu layer 26 under such a pH.

The polishing speed also depends on the number of rotations of the turntable 6. The rotational speed of the turntable 6 affects the polishing rate even in general CMP, but the method according to this reference example has a very large influence on the polishing rate. This is because in this reference example , the abrasive particles 18 are used as an oxidizing agent. In other words, if the light-irradiated abrasive particles 18 are not quickly supplied to the surface to be polished, the holes generated by the light irradiation will not be used for metal oxidation and will recombine with electrons.

  FIG. 40 is a graph showing the relationship between the rotation speed of the turntable and the polishing rate. In the figure, the horizontal axis indicates the rotational speed of the turntable 6, and the vertical axis indicates the polishing rate. The data shown in FIG. 40 is obtained under substantially the same conditions as those described with reference to FIG. 13 except for the rotation speed of the turntable 6.

  As shown in FIG. 40, when the rotational speed of the turntable 6 is in the range of 60 rpm to 140 rpm, a high polishing rate of 300 nm / min or higher was obtained. Moreover, when the rotation speed of the turntable 6 was in the range of 80 rpm to 120 rpm, a high polishing rate of 600 nm / min or higher was obtained. As described above, the high polishing rate was obtained by setting the rotation speed of the turntable 6 to be equal to or higher than the lower limit as described above, and more holes were used for metal oxidation without recombining with electrons. It was because I was able to do it. The reason why the polishing rate is low when the rotation speed of the turntable 6 is higher than the above upper limit value is that the amount of the slurry 7 supplied to the surface to be polished is reduced by excessive centrifugal force.

The polishing rate greatly depends on the type of polishing pad 5 used.
FIG. 41 is a graph showing the relationship between the type of polishing pad and the polishing rate. In the figure, “No C” uses IC1000 / Suba400 which does not contain a conductive component as the polishing pad 5 and forms a copper embedded wiring under the same conditions as described with reference to FIG. The data obtained in this case is shown. In the figure, “C” indicates that a copper embedded wiring is formed under substantially the same conditions as those described with reference to FIG. 13 except that a Politex containing carbon is used as the polishing pad 5. The data obtained in this case is shown.

  As shown in FIG. 41, when the polishing pad 5 containing no conductive component was used, a polishing rate of about 1 μm / min could be realized. On the other hand, when the polishing pad 5 containing a conductive component was used, the polishing rate was about 50 nm / min. The reason why the polishing rate is remarkably different depending on the type of the polishing pad 5 used in this way is generated by irradiating the polishing particles 18 with light when the polishing pad contains a conductive component such as carbon. This is because the generated holes can recombine with the free electrons in the conductive component. The decrease in the polishing rate due to such recombination can be sufficiently suppressed by using a polishing pad 5 having a concentration of a conductive component such as carbon of 3% by weight or less. By using a material that does not contain such a conductive component, it can be almost completely prevented.

(Fourth reference example )
As described in the third reference example , when the abrasive particles 18 are used as an oxidizing agent, a metal residue may be generated. This will be described with reference to FIGS. 20 (a) and 20 (b).

20A and 20B are cross-sectional views schematically showing a metal residue that can be generated when CMP is performed by the method according to the third reference example . Although not shown in FIGS. 20A and 20B, the bottom and side surfaces of the Cu layer 26 have the same WN as described with reference to FIGS. 14A and 14B. A barrier layer such as a layer is formed.

As described above, the titanium oxide particles 18 improve the degree of dispersion and the oxidizing power by light irradiation. Therefore, it is considered that the dispersion degree of the titanium oxide particles 18 is high in the slurry 7 supplied onto the polishing pad. However, in the method described in the third reference example , as shown in FIG. 20A, the titanium oxide particles 18 are not necessarily uniformly distributed in the slurry 7 interposed between the polishing pad and the substrate to be polished. I don't mean. Therefore, the polishing of the Cu layer 26 may proceed nonuniformly.

When the polishing of the Cu layer 26 proceeds non-uniformly, concave portions and convex portions are generated on the surface of the Cu layer 26. When the area of the upper surface of the convex portion is small, the titanium oxide particles 18 are unlikely to intervene between the upper surface of the convex portion and the polishing pad, and therefore the upper surface of the convex portion is difficult to be oxidized. That is, it is difficult for the CuO _x film 43 to be formed on the upper surface of the convex portion compared to the bottom surface of the concave portion. Therefore, as shown in FIG. 20B, the Cu layer 26 may remain in an island shape on the upper surface of the insulating film 24.

  The height and diameter of the Cu layer 26 remaining in such an island shape may be about 500 nm at the maximum. Therefore, when such an island-like residual portion is generated, there is a risk of causing an electrical short circuit between adjacent wirings.

In this reference example , polishing is performed by the same method as described in the third reference example except that a nonionic surfactant is further added to the slurry 7. When the slurry 7 contains a nonionic surfactant, the abrasive particles 18 can be more uniformly dispersed. Therefore, in addition to the effects described in the third reference example , the polishing of the metal layer 26 can be progressed uniformly, and the generation of island-like residual portions can be suppressed.

FIG. 21 is a graph showing an example of the effect of the addition of a nonionic surfactant to the slurry suppressing the generation of island-like residues. Note that the data shown in FIG. 21 was obtained under the following conditions. That is, as the CMP slurry 7, a slurry containing anatase-type titanium oxide particles 18 having a primary particle diameter of about 20 nm at a concentration of about 3% by weight was used. Further, IC1000 / Suba400 was used as the polishing cloth (polishing pad). During CMP, a 500 W mercury lamp was kept on, the load was about 300 gf / cm ² , the head 3 was rotated about 100 rpm, the turntable was rotated about 100 rpm, and the slurry flow rate was 200 cc / min. Under such conditions, Cu wirings 26 having a width of 40 μm were formed at intervals of 10 μm.

  In FIG. 21, data obtained when no nonionic surfactant was added to the slurry 7 (“No NS”), and acetylenic diol (hydrophilic / hydrophobic balance HLB = 18) as nonionic surfactant were added to the slurry 7 as 0. The data obtained when added at a concentration of 1 wt% (“with NS”) are shown. Further, in the figure, the vertical axis indicates the number of island-like residual portions recognized when a predetermined area is observed.

  As shown in FIG. 21, when no nonionic surfactant was added to the slurry 7, 60 island-like residual portions were generated. On the other hand, when a nonionic surfactant was added to the slurry 7, the number of island-like residual portions was reduced to 7.

  Thus, by adding a nonionic surfactant to the slurry 7, the generation of island-like residual portions can be suppressed. Therefore, it is possible to suppress the occurrence of an electrical short circuit between the wirings and greatly improve the manufacturing yield.

  FIG. 22 is a graph showing an example of the effect of adding the nonionic surfactant to the slurry to improve the production yield. In FIG. 22, the wiring yield (“short”) related to the electrical short circuit caused by the island-like residual portion and the wiring yield (“open”) related to the peeling of the wiring described with reference to FIGS. 14 (a) and 14 (b). It shows. In FIG. 22, “without NS” and “with NS” use the slurry 7 described in relation to FIG. 21, and form the Cu wiring 26 under substantially the same conditions as described in relation to FIG. 21. The data obtained when formed is shown. Further, in FIG. 22, “Prior Art” uses a slurry containing alumina or silica particles as an abrasive particle and containing an oxidizing agent, and Cu under the same conditions as described with reference to FIG. 21. Data obtained when the wiring 26 is formed is shown. As shown in FIG. 22, when the titanium oxide particles 18 and the nonionic surfactant are combined, both the electrical short circuit between the wirings and the peeling of the wirings can be suppressed.

  As described above, when the titanium oxide particles 18 and the nonionic surfactant are combined, the yield can be improved. In addition, in this case, a high polishing rate can be realized. Such an effect is unique when a nonionic surfactant is added. That is, even if an anionic surfactant or a cationic surfactant is added to the slurry 7, the effect as much as when a nonionic surfactant is added cannot be obtained.

  FIG. 23 is a graph showing the relationship between the slurry composition and the polishing rate. The data shown in FIG. 23 is almost the same as described with reference to FIG. 21 using a slurry containing anatase-type titanium oxide particles 18 having a primary particle diameter of about 20 nm at a concentration of about 3% by weight. Data obtained when the Cu wiring 26 is formed under the conditions is shown. Specifically, “No S” indicates data obtained when no surfactant was added to the slurry. “AS1” and “AS2” indicate data obtained when dodecylbenzenesulfonic acid-based and polycarboxylic acid-based anionic surfactants were added to the slurry, respectively. “CS” represents data obtained when an ammonium chloride cationic surfactant was added to the slurry. “NS1” indicates data obtained when acetylene diol was added as a nonionic surfactant to the slurry. “NS2” indicates data obtained when a fluorine-based nonionic surfactant was added to the slurry.

  As shown in FIG. 23, when an anionic surfactant was added to the slurry 7, the polishing rate was lower than when no surfactant was added. In addition, when an anionic surfactant was added to the slurry 7, the titanium oxide particles 18 were agglomerated and their dispersibility was significantly reduced. This is presumably because the negatively charged anionic surfactant was adsorbed on the positively charged titanium oxide particles 18 and the oxidizing power of titanium oxide was reduced.

  Further, as shown in FIG. 23, when a cationic surfactant was added to the slurry 7, the polishing rate was lower than when no surfactant was added, and a practical polishing rate could not be obtained. This is presumably because the cationic surfactant was adsorbed on the copper oxide layer and the copper oxide was transformed into a material that was difficult to polish.

In this reference example , examples of the nonionic surfactant include acetylene diol, polyoxyethylene lauryl ether, sugar ester, sorbitan ester, glycerin ester, polyoxyethylene alkyl ether, fatty acid salt, alkyl sulfate, polyoxyethylene alkylamine. , Alkyltrimethylammonium salt, alkylamine salt, and a mixture containing at least one of them can be used. In this reference example , a fluorine-based nonionic surfactant containing a fluoroalkyl group in the molecule may be used as the nonionic surfactant.

In this reference example , the concentration of the nonionic surfactant in the slurry 7 is preferably in the range of 0.001 wt% to 0.5 wt%. When the concentration of the nonionic surfactant in the slurry 7 is less than 0.001% by weight, the effect of uniformly dispersing the abrasive particles 18 does not appear remarkably. On the other hand, when the concentration of the nonionic surfactant in the slurry 7 exceeds 0.5% by weight, the photocatalytic action of the abrasive particles 18 may be reduced to lower the polishing rate.

In this reference example , the slurry 7 does not contain an oxidizing agent. However, in order to use the abrasive particles 18 as an oxidizing agent, the pH of the slurry 7 is preferably 7 or less as described with reference to FIG. The pH of the slurry 7 can be adjusted, for example, by adding an inorganic acid such as nitric acid, phosphoric acid, hydrochloric acid, or sulfuric acid as a pH adjuster.

(Fifth reference example )
As described in the third reference example , when the abrasive particles 18 are used as an oxidizing agent, the pattern density affects the polishing rate. This will be described with reference to FIG.

FIG. 24 is a cross-sectional view for explaining the pattern density dependence of the polishing rate that can occur when CMP is performed by the method according to the third reference example . In FIG. 24, reference numeral 30 indicates a barrier layer such as a WN layer.

  In the portion 51 where the pattern density is low, the abrasive particles 18 can move relatively freely between the polishing pad 5 and the Cu layer 26. Therefore, the abrasive particles 18 can always exist at a sufficient density in the portion 51 where the pattern density is low. However, in the portion 52 where the pattern density is high, there is a high probability that the abrasive particles 18 enter the concave portion from the convex portion of the Cu layer 26. Since it is difficult for the abrasive particles 18 that have entered the recesses to return to the projections, the density of the abrasive particles 18 is reduced on the projections. Therefore, the polishing rate is extremely slow in the portion 52 having a high pattern density compared to the portion 51 having a low pattern density.

FIG. 25 is a cross-sectional view schematically showing CMP according to the fifth reference example . In this reference example , polishing is performed by the same method as described in the third reference example except that the resin particles 41 are further added to the slurry 7. When the resin particles 41 are likely to adhere to both the abrasive particles 18 and the polishing pad 5, it is possible to suppress the abrasive particles 18 from entering the recesses of the Cu layer 26 as shown in FIG. 25. Therefore, according to the fifth reference example , in addition to obtaining the effects described in the third reference example , the polishing rate of the portion 52 having a high pattern density can be increased.

  As a material of the resin particles 41, for example, a methacrylic resin, a phenol resin, a urea resin, a melamine resin, a polystyrene resin, a polyacetal resin, a polycarbonate resin, and a mixture containing at least one of them can be used.

As the resin particles 41 that easily adhere to the abrasive particles 18, for example, those charged to a polarity opposite to the charged polarity of the abrasive particles 18 can be used. For example, when using the titanium oxide particles positively charged as the abrasive particles 18, a functional group bearing a negative charge in the molecule (e.g., COO ^- group, etc.), resin particles containing, surface-treated with silica Resin particles and the like can be used. Further, as the resin particles 41 that easily adhere to the abrasive particles 18, resin particles that can adhere to the abrasive particles 18 and the polishing pad 5 due to a mechano-fusion phenomenon may be used. Since the polishing pad 5 is usually made of an organic material, the resin particles 41 can adhere strongly.

  The primary particle diameter of the resin particles 41 is preferably distributed within a range of 5 nm to 1000 nm. When the primary particle diameter of the resin particles 41 is less than 5 nm, the effect of the resin particles 41 fixing the abrasive particles 18 to the polishing pad 5 is small. Moreover, when the primary particle diameter of the resin particle 41 exceeds 1000 nm, it becomes difficult to disperse the resin particle 41 uniformly.

  The concentration of the resin particles 41 in the slurry 7 is preferably in the range of 0.1 wt% to 3.0 wt%. When the concentration of the resin particles 41 in the slurry 7 is less than 0.1% by weight, the effect of the resin particles 41 fixing the abrasive particles 18 to the polishing pad 5 is small. In addition, when the concentration of the resin particles 41 in the slurry 7 exceeds 3.0% by weight, the resin particles 41 may reduce the polishing power and the oxidizing power of the polishing particles 18.

FIG. 26 is a graph showing an example of the effect of adding the resin particles to the slurry to increase the polishing rate. Note that the data shown in FIG. 26 is obtained under the following conditions. That is, the CMP slurry 7 includes PMMA (polymethyl) containing anatase-type titanium oxide particles 18 having a primary particle diameter of about 20 nm at a concentration of about 3% by weight and having a COO ⁻ group on the surface and a primary particle diameter of about 200 nm. (Methacrylate) particles 41 at a concentration of about 0.5% by weight and a pH adjusted to about 3 was used. Further, IC1000 / Suba400 was used as the polishing cloth (polishing pad). During CMP, a 500 W mercury lamp was kept on, the load was about 300 gf / cm ² , the head 3 was rotated about 100 rpm, the turntable was rotated about 100 rpm, and the slurry flow rate was 200 cc / min. Under such conditions, the Cu wiring 26 was formed.

  FIG. 26 shows polishing rate data (“blanket”) in a portion where the pattern density is low and polishing rate data (“pattern”) in a portion where the pattern density is high. Further, in FIG. 26, “without resin” indicates data obtained when a slurry containing no resin particles 41 is used, and “with resin” is obtained when a slurry containing resin particles 41 is used. The obtained data is shown. As shown in FIG. 26, by adding the resin particles 41 to the slurry 7, it was possible to increase both the polishing rate in the portion where the pattern density was low and the polishing rate in the portion where the pattern density was high. In particular, when the resin particles 41 were added to the slurry 7, the polishing rate in the portion where the pattern density was high could be significantly increased.

(Sixth reference example )
In the fifth reference example , the polishing rate was increased by adding resin particles 41 to the slurry 7. In the sixth reference example , inorganic particles charged to the same polarity as the charged polarity of the abrasive particles 18 are added to the slurry 7 to increase the polishing rate.

FIG. 27 is a cross-sectional view schematically showing CMP according to the sixth reference example . In this reference example , polishing is performed by the same method as described in the third reference example except that the inorganic particles 42 are further added to the slurry 7. When the inorganic particles 42 charged with the same polarity as the charged polarity of the abrasive particles 18 are added to the slurry 7, the mechanical polishing power of the slurry 7 is improved. Therefore, according to the sixth reference example , in addition to obtaining the effects described in the third reference example , the polishing rate can be increased.

  When the charged polarity of the abrasive particles 18 and the charged polarity of the inorganic particles 42 are different, it is difficult to increase the polishing rate. For example, the titanium oxide particles 18 are positively charged, and the alumina particles 42 are also positively charged. Therefore, aggregation due to electrostatic force between the titanium oxide particles 18 and the alumina particles 42 hardly occurs. Therefore, the mechanical polishing power of the slurry 7 can be increased without reducing the oxidizing power of the titanium oxide particles 18. On the other hand, when the titanium oxide particles 18 and inorganic particles having a negative charge such as silica particles are combined, the particles aggregate together. Therefore, the oxidizing power of the titanium oxide particles 18 decreases, and the polishing rate decreases conversely.

In this reference example , when titanium oxide particles are used as the abrasive particles 18 and alumina particles are used as the inorganic particles 42, when preparing the slurry 7, the titanium oxide particles 18 and the alumina particles 42 are mixed in a powder state. It is desirable not to. That is, it is desirable to mix the dispersion liquid of the titanium oxide particles 18 and the dispersion liquid of the alumina particles 42, or add the other to one dispersion liquid of the titanium oxide particles 18 and the alumina particles 42. When the titanium oxide particles 18 and the alumina particles 42 are mixed in a powder state, the titanium oxide particles 18 and the alumina particles 42 may be integrated to produce composite particles. When such composite particles are produced, the surface area of titanium oxide is reduced and its oxidizing power is significantly reduced.

  The primary particle diameter of the alumina particles 42 is preferably distributed within a range of 5 nm to 100 nm. When the primary particle diameter of the alumina particles 42 is less than 5 nm, the effect of increasing the mechanical polishing force is small. Further, when the primary particle diameter of the alumina particles 42 exceeds 100 nm, scratches are likely to occur.

  The concentration of the alumina particles 42 in the slurry 7 is preferably in the range of 0.1 wt% to 3.0 wt%. When the concentration of the alumina particles 42 in the slurry 7 is less than 0.1% by weight, the effect of increasing the mechanical polishing power does not appear. Further, when the concentration of the alumina particles 42 in the slurry 7 exceeds 3.0% by weight, the alumina particles 42 may reduce the polishing power and the oxidizing power of the polishing particles 18.

FIG. 28 is a graph showing an example of the effect of adding inorganic particles to the slurry to increase the polishing rate. Note that the data shown in FIG. 28 is obtained under the following conditions. That is, the CMP slurry 7 contains anatase-type titanium oxide particles 18 having a primary particle diameter of about 20 nm at a concentration of about 3% by weight, and γ alumina particles 42 having a primary particle diameter of about 50 nm are about 0.5% by weight. And a slurry 7 having a pH of about 3 was used. Further, IC1000 / Suba400 was used as the polishing cloth (polishing pad). During CMP, a 500 W mercury lamp was kept on, the load was about 300 gf / cm ² , the head 3 was rotated about 100 rpm, the turntable was rotated about 100 rpm, and the slurry flow rate was 200 cc / min. Under such conditions, the Cu wiring 26 was formed.

  In FIG. 28, “without alumina” indicates data obtained when a slurry not containing alumina particles 21 is used, and “with alumina” is obtained when a slurry containing alumina particles 42 is used. Data are shown. Further, “with silica” indicates data obtained when a slurry containing silica particles is used instead of the alumina particles 42.

  As shown in FIG. 28, when silica particles are added to the slurry 7, both the polishing rate in the portion where the pattern density is low and the polishing rate in the portion where the pattern density is high are greatly reduced, and a practical polishing rate is obtained. There wasn't. On the other hand, when the alumina particles 42 were added to the slurry 7, it was possible to increase both the polishing rate in the portion where the pattern density was low and the polishing rate in the portion where the pattern density was high. In particular, when the alumina particles 42 were added to the slurry 7, the polishing rate in the portion where the pattern density was high could be significantly increased.

(Seventh reference example )
In the first to sixth reference examples described above, the case where titanium oxide particles are mainly used as the abrasive particles 18 has been described. In the seventh reference example , titanium oxide particles doped with nitrogen and / or sulfur are used as the abrasive particles 18.

  As described above, the photocatalytic action of titanium oxide is manifested mainly by irradiation with light in the ultraviolet region having a wavelength of 380 nm or less. Therefore, it is necessary to provide the CMP apparatus with an ultraviolet irradiation device such as a mercury lamp or a black light. In addition, ultraviolet rays may adversely affect the human body.

  However, when visible light is used for the titanium oxide particles 18 instead of ultraviolet rays, the photocatalytic action cannot be sufficiently exhibited. Therefore, in this case, a practical polishing rate cannot be obtained. Therefore, it is desirable that the abrasive particles 18 can sufficiently exhibit the photocatalytic action even when irradiated with light having a longer wavelength.

  FIG. 29 (a) is a diagram showing an energy band of titanium oxide, FIG. 29 (b) is a diagram showing an energy band of titanium oxide doped with nitrogen, and FIG. 29 (c) is an energy band of alumina or silica. FIG. As shown in FIG. 29 (a), titanium oxide has a band gap of 3.2 eV, and exhibits photocatalytic action by absorbing light in the ultraviolet region. On the other hand, when titanium oxide is doped with nitrogen, a new energy level is formed between the valence band and the conduction band of titanium oxide, as shown in FIG. Therefore, the effective band gap can be further reduced. Therefore, it is possible to develop a photocatalytic action even with visible light having a lower energy than ultraviolet light. In addition, as shown in FIG.29 (c), the band gap of an alumina or a silica is larger than 8 eV. Therefore, even if they are irradiated with light in the ultraviolet region, no photocatalytic action is exhibited.

  FIG. 30 is a graph showing the relationship between the wavelength of light applied to the abrasive particles 18 and the number of holes generated by photoexcitation. In the figure, the horizontal axis indicates the wavelength of light irradiated on the abrasive particles 18, and the vertical axis indicates the number of holes generated in the abrasive particles 18 due to light irradiation. The oxidizing power of the abrasive particles 18 is substantially proportional to the number of holes generated.

As shown in FIG. 30, when the material of the abrasive particles 18 is titanium oxide, a sufficient number of positive holes can be generated if irradiated with ultraviolet rays, but a sufficient number of positive particles can be generated even when irradiated with visible light. It is not possible to create holes. On the other hand, when titanium oxide doped with nitrogen is used as the material of the abrasive particles 18, it is possible to generate a sufficient number of holes not only when irradiated with ultraviolet rays but also when irradiated with visible rays. Become. Therefore, according to this reference example , sufficient oxidizing power can be obtained even when visible light is irradiated. Therefore, according to the present reference example , when CMP is performed by the same method as described in the first to sixth reference examples except that titanium oxide doped with nitrogen is used as the material of the abrasive particles 18, irradiation is performed. The effects described in the reference examples can be obtained not only when ultraviolet light is used as light but also when visible light is used.

In this reference example , as a material for the abrasive particles 18, titanium oxide doped with sulfur may be used instead of titanium oxide doped with nitrogen. Alternatively, titanium oxide doped with both nitrogen and sulfur may be used as the material of the abrasive particles 18 instead of titanium oxide doped with nitrogen. In these cases as well, the same effects as when titanium oxide doped with nitrogen is used as the material of the abrasive particles 18 can be obtained.

In this reference example , the concentration of nitrogen and / or sulfur in titanium oxide is preferably 10 atomic percent or less, and more preferably 2 atomic percent or less. If the concentration of nitrogen and / or sulfur is excessively high, the ability of the abrasive particles 18 as a photocatalyst may be reduced. In this reference example , the concentration of nitrogen and / or sulfur in titanium oxide is preferably 0.05 atomic% or more, and more preferably 0.1 atomic% or more. When the concentration of nitrogen and / or sulfur is low, it may be difficult to develop a sufficient photocatalytic action by irradiation with visible light.

In this reference example , the pH of the slurry 7 is preferably in the range of about 3 to about 5. When the pH of the slurry 7 is about 7, the zeta potential of the abrasive particles 18 approaches zero (isoelectric point), so that the slurry 7 easily aggregates. In addition, when the slurry 7 is alkaline, a metal hydroxide that is difficult to polish may be formed on the metal surface to be polished, and the polishing rate may decrease. Further, if the pH is less than about 3, the metal surface to be polished may be wet etched to cause unwanted dissolution.

In this reference example , the titanium oxide particles 18 doped with nitrogen, the titanium oxide particles 18 doped with sulfur, and the titanium oxide particles 18 doped with both nitrogen and sulfur can be obtained by various methods. For example, it can be obtained using a sol-gel method or a chemical reaction method.

(Eighth reference example )
Electrons and holes generated by irradiating titanium oxide with ultraviolet rays are easily recombined. Usually, their lifetime is about 100 nsec. Such a short lifetime of holes may limit the oxidizing power of the titanium oxide particles 18 and limit the polishing rate.

In the eighth reference example , titanium oxide particles carrying a charge separation material are used as the abrasive particles 18. When such abrasive particles 18 are used, recombination of electrons and holes caused by irradiating titanium oxide with light can be suppressed. For example, when titanium oxide particles carrying nickel as a charge separation substance are used as the abrasive particles 18, electrons generated by light irradiation are represented by the following reaction formula on nickel:
2H ^{+ +} 2e ^- → H ₂
The reduction reaction shown in FIG.
Therefore, electrons generated by light irradiation move toward nickel, and the probability that holes and electrons are recombined is reduced.

  FIG. 31 is a graph showing the relationship between the wavelength of light applied to the abrasive particles 18 and the number of holes in the abrasive particles 18. In the figure, the horizontal axis indicates the wavelength of light irradiated on the abrasive particles 18, and the vertical axis indicates the number of holes in the abrasive particles 18 at the time of light irradiation.

As shown in FIG. 31, when the titanium oxide particles 18 supporting a charge separation material such as nickel are used, the number of holes in the abrasive particles 18 at the time of ultraviolet irradiation is larger than when the titanium oxide particles 18 are used. The number can be increased. Therefore, a higher oxidizing power can be obtained. Therefore, according to this reference example , when CMP is performed by the same method as described in the first to sixth reference examples except that the titanium oxide particles 18 supporting the charge separation material are used, those reference examples are used. In addition to the effects described in (1) above, it is possible to achieve a higher polishing rate.

In this reference example , any of nickel, copper, silver, gold, niobium, and a mixture thereof is used as the charge separation material. Lead, vanadium, chromium and the like are dangerous because they are highly toxic and cause environmental problems. In particular, vanadium oxide is extremely toxic and is dangerous when used. In contrast, nickel, copper, silver, gold, and niobium have low toxicity and are easy to handle.

In this reference example , the coverage, which is the area covered with the charge separation substance on the titanium oxide surface, is preferably 90% or less, and more preferably 60% or less. If this coverage is excessively high, the ability of the abrasive particles 18 as a photocatalyst may be reduced. In this reference example , the coverage is preferably 5% or more, and more preferably 10% or more. When the said coverage is low, the probability that a hole and an electron will recombine cannot be reduced notably.

In the ninth reference example , the combination of the techniques described in the seventh and eighth reference examples is used. That is, titanium oxide particles carrying a charge separation material and doped with nitrogen and / or sulfur are used as the abrasive particles 18.

  FIG. 32 is a graph showing the relationship between the wavelength of light applied to the abrasive particles 18 and the number of holes in the abrasive particles 18. In the figure, the horizontal axis indicates the wavelength of light irradiated on the abrasive particles 18, and the vertical axis indicates the number of holes in the abrasive particles 18 at the time of light irradiation.

As shown in FIG. 32, for example, when titanium oxide particles 18 carrying a charge separation material such as nickel and doped with nitrogen are used, compared with the case where titanium oxide particles 18 are used, only when irradiated with ultraviolet rays. In addition, the number of holes in the abrasive particles 18 can be increased even during visible light irradiation. Therefore, a higher oxidizing power can be obtained even during visible light irradiation, and a higher polishing rate can be realized. That is, both of the effects described in the seventh and eighth reference examples can be obtained. In this reference example , for example, any of nickel, copper, silver, gold, platinum, niobium, and a mixture thereof can be used as the charge separation substance.

FIG. 33 is a graph showing the relationship between the type of abrasive particles 18 and the polishing rate. The data shown in FIG. 33 is obtained when the structure shown in FIG. 14A is formed under the following conditions. That is, as the CMP slurry 7, a slurry containing abrasive particles 18 at a concentration of about 3% by weight and having a pH of about 3 was used. Further, IC1000 / Suba400 was used as the polishing cloth (polishing pad). During CMP, a 500 W mercury lamp was kept on, the load was about 300 gf / cm ² , the head 3 was rotated about 100 rpm, the turntable was rotated about 100 rpm, and the slurry flow rate was 200 cc / min. Under such conditions, Cu wirings 26 having a width of 42.50 μm were formed at intervals of 7.5 μm.

In FIG. 33, “Al ₂ O ₃ ”, “SiO ₂ ”, and “TiO ₂ ” are data obtained when aluminum oxide particles, silicon oxide particles, and titanium oxide particles are used as the abrasive particles 18, respectively. Is shown. “TiON” indicates data obtained when titanium oxide particles doped with nitrogen are used as the abrasive particles 18. “Ni / TiO ₂ ” indicates data obtained when titanium oxide particles supporting Ni are used as the abrasive particles 18. “Ni / TiON” indicates data obtained when titanium oxide particles doped with nitrogen and supporting Ni are used as the abrasive particles 18.

  As shown in FIG. 33, when titanium oxide particles are used as the abrasive particles 18, when a CMP is performed while continuing irradiation with a mercury lamp (500W), a practical polishing rate can be obtained, but irradiation with a fluorescent lamp (30W) is possible. When CMP was performed while continuing, a practical polishing rate could not be obtained. On the other hand, when the titanium oxide particles doped with nitrogen were used as the abrasive particles 18, a higher polishing rate was obtained when CMP was performed while continuing to irradiate the mercury lamp, and CMP was performed while continuing to irradiate the fluorescent lamp. Sometimes a practical polishing rate could be obtained. When titanium oxide particles supporting Ni were used as the polishing particles 18, a higher polishing rate could be obtained when CMP was performed while continuing irradiation with a mercury lamp. Furthermore, when titanium oxide particles doped with nitrogen and carrying Ni are used as the abrasive particles 18, when CMP is performed while continuing to irradiate a mercury lamp, an extremely high polishing rate is obtained, and CMP continues while irradiating with a fluorescent lamp. A very high polishing rate could be obtained even when performing.

  In addition, the Cu film | membrane was immersed in the slurry 7 which used the titanium oxide particle as the abrasive particle 18, and the wet etching was performed. As a result, the etching rate was 1 nm / min or less both during light irradiation and during light shielding. As shown in FIG. 33, when titanium oxide particles are used as the abrasive particles 18, the polishing rate at the time of light shielding is remarkably lower than the polishing rate at the time of light irradiation. From these results, in the above CMP using titanium oxide particles as the abrasive particles 18, wet etching with a pH adjuster or the like dissolved in the dispersion medium 25 hardly contributes to the removal of copper. It was confirmed that the process proceeds mainly by the oxidation of copper by the titanium oxide particles 18 and the mechanical polishing of the resulting copper oxide particles 18 of copper.

  In addition, when titanium oxide particles are used as the abrasive particles 18, titanium oxide particles doped with nitrogen are used, titanium oxide particles carrying Ni are used as the abrasive particles 18, nitrogen is doped as the abrasive particles 18. In addition, in any of the cases where titanium oxide particles supporting Ni were used, dishing and erosion were 60 nm or less at the time of overpolishing after further polishing by 60% from just polishing. That is, good flatness could be realized.

(10th reference example )
Next, a tenth reference example will be described. In the first to ninth reference examples , the photocatalytic action of the abrasive particles 18 was used during CMP. On the other hand, in the tenth reference example , the photocatalytic action of the abrasive particles 18 is used when the CMP slurry 7 is stored.

As described above, if the slurry for CMP is stored without using it, the abrasive particles aggregate to form huge coarse particles, which eventually precipitate. In this reference example , the abrasive particles 18 whose dispersity is improved by light irradiation, such as titanium oxide particles, are used, and the slurry 7 is continuously irradiated with the light while the slurry 7 is stored. Thereby, the favorable dispersion state of the abrasive particles 18 can be maintained. If it is possible to maintain a good dispersion state of the abrasive particles 18 (for example, a dispersion state that does not cause precipitation of the abrasive particles 18), instead of continuously irradiating the slurry 7 with the light, the light is irradiated. You may irradiate intermittently. In addition, the intensity of light applied to the slurry 7 is not particularly limited as long as it can maintain a good dispersion state of the abrasive particles 18.

  FIG. 34 is a graph showing the relationship between the storage days of the CMP slurry and the number of coarse particles in the slurry. In the figure, the horizontal axis indicates the number of storage days, and the vertical axis indicates the number of coarse particles. In the figure, the solid line shows data obtained when titanium oxide particles are used as the abrasive particles 18 and the slurry 7 is continuously irradiated with ultraviolet rays during storage, and the broken line does not irradiate the slurry 7 with light during storage. The data obtained in the case of

  As shown in FIG. 34, when the slurry 7 was not irradiated with light, the number of coarse particles in the slurry increased with time. On the other hand, when the slurry 7 was continuously irradiated with ultraviolet rays, the number of coarse particles was almost constant regardless of the elapsed time.

  Further, if the abrasive particles 18 are stored without using the CMP slurry 7 using a material in which oxidizing power or reducing power is induced by light irradiation such as titanium oxide particles, oxidation induced by light irradiation is performed. Power and reducing power may be reduced. Against this, it is effective to irradiate the slurry 7 with light continuously or intermittently while the slurry 7 is being stored.

  FIG. 35 is a graph showing the relationship between the storage days of the CMP slurry and the polishing rate. In the figure, the horizontal axis indicates the number of storage days, and the vertical axis indicates the polishing rate. In the figure, the solid line shows data obtained when titanium oxide particles are used as the abrasive particles 18 and the slurry 7 is continuously irradiated with ultraviolet rays during storage, and the broken line does not irradiate the slurry 7 with light during storage. The data obtained in the case of

  As shown in FIG. 35, when the slurry 7 was not irradiated with light, the polishing rate decreased according to the number of days elapsed from the start of storage. On the other hand, when the slurry 7 was continuously irradiated with ultraviolet rays, the polishing rate was almost constant regardless of the number of days elapsed.

Thus, according to this reference example , it is possible to suppress the deterioration of the slurry 7 due to the aggregation of the abrasive particles 18 and the like. In addition, even if the slurry 7 is stored for a long period of time while being continuously irradiated with ultraviolet rays, a photochemical reaction other than maintaining the state of high dispersity and oxidizing power hardly occurs. Moreover, even if a photochemical reaction other than those occurs, the influence of such a photochemical reaction on the slurry 7 is extremely small. Therefore, according to this reference example , the life of the slurry for CMP can be significantly extended.

(Eleventh reference example )
Next, an eleventh reference example will be described. In the eleventh reference example , the photocatalytic action of the abrasive particles 18 is used after the CMP slurry 7 is used for CMP.

As described above, the waste liquid of the CMP slurry 7 after use may contain a large amount of organic substances that are difficult to decompose in the natural environment. In this reference example , the slurry 7 after use is irradiated with light capable of inducing the oxidizing power or reducing power of the abrasive particles 18 to decompose organic substances and the like in the slurry 7. By performing such a decomposition treatment, even if the used slurry 7 is discarded into the natural environment, there is no load on the environment. That is, chemical treatment using a chemical solution or the like is not necessary.

In addition, since sunlight contains light of various wavelengths, the oxidizing power or reducing power of the abrasive particles 18 can be induced. Therefore, sunlight may be used to decompose organic substances in the slurry 7. For example, even if the used slurry 7 is discarded in the natural environment where sunlight can reach without being subjected to the above-described decomposition treatment, organic substances contained in the used slurry 7 can be decomposed. In addition, when the slurry 7 is discarded into a natural environment where sunlight can reach, the natural environment can be purified. For example, tetrachloroethylene, which is a typical environmental pollutant, has the following reaction formula due to the photocatalytic action of titanium oxide:
C ₂ H ₂ Cl ₄ + 4H ₂ O → 2CO ₂ + 4HCl + 6H ⁺
Can be disassembled as shown in

Thus, according to the eleventh reference example , in addition to making the CMP slurry 7 after use almost harmless to the natural environment, the CMP slurry 7 after use is used for purification of the natural environment. It becomes possible.

( Twelfth reference example )
In the eleventh reference example , the used slurry 7 was used for purification of the natural environment. On the other hand, in the twelfth reference example , the used slurry 7 is reused for CMP.

FIG. 36 is a diagram schematically illustrating a CMP slurry reuse system according to a twelfth reference example . A reuse system 61 shown in FIG. 36 includes a slurry supply device 62 that supplies the slurry 7 to the CMP device 1, a slurry recovery device 63 that recovers the slurry 7 used in the CMP device 1, and a slurry that is recovered by the slurry recovery device 63. 7 includes a filter 64 that removes the shaving residue 70 from the filter 7, a regenerated slurry supply device 65 that supplies the slurry 7 from which the scrap residue 70 has been removed by the filter 64 to the slurry supply device 62, and light irradiation devices 66a to 66c. . Note that the CMP apparatus 1 used here may include the light irradiation apparatus 10 and / or 33 as in the CMP apparatus 1 described with reference to FIGS.

  Most of the running cost of the CMP apparatus is occupied by the cost of the polishing pad and the cost of the slurry. Therefore, from the viewpoint of cost, a technique for reusing the used slurry is important. However, conventional slurries are difficult to reuse. This is because ammonium persulfate, iron nitrate, organic acids, and the like used as oxidizing agents in conventional slurries form compounds with metals, and scraps and abrasive particles generated with CMP form coarse particles. This is due to the fact that there are fewer recyclable abrasive particles.

In this reference example , abrasive particles 18 whose dispersity and oxidizing power are increased by light irradiation, such as titanium oxide particles, are used as an oxidizing agent, and no oxidizing agent is added separately. Therefore, it is possible to suppress the formation of an undesired metal compound. In addition, the ability of the titanium oxide particles 18 as an oxidant is one of the ability as a photocatalyst, and can be used repeatedly. In addition, even if the shavings and the abrasive particles 18 form coarse particles, they can be separated by light irradiation, so that the abrasive particles 18 and the shavings can be easily separated. Therefore, according to this reference example , more abrasive particles can be collected more easily.

(13th reference example )
FIG. 37 is a diagram schematically showing a CMP slurry reuse system according to a thirteenth reference example . The reuse system 61 shown in FIG. 37 includes a slurry supply device 62 that supplies the slurry 7 to the CMP device 1, a slurry recovery device 63 that recovers the slurry 7 used in the CMP device 1, and a slurry that is recovered by the slurry recovery device 63. 7, a melting treatment device 67 for dissolving the shaving residue 70, a flocculating device 68 for agglomerating the abrasive particles 18 in the slurry 7 processed by the dissolution processing device 67 by shading, and a slurry 7 processed by the aggregating device 68. A filter 64 for separating the aggregated abrasive particles 18 from the dispersion medium 25 and the like, and the abrasive particles 18 collected by the filter 64 and the new dispersion medium 25 and the like are mixed to regenerate the slurry 7 and regenerate the slurry 7 A regenerated slurry supply device 65 for supplying to the slurry supply device 62 and light irradiation devices 66a to 66d are included. Note that the CMP apparatus 1 used here may include the light irradiation apparatus 10 and / or 33 as in the CMP apparatus 1 described with reference to FIGS.

In the present reference example , unlike the twelfth reference example , the shaving residue 70 in the slurry 7 is removed not by filtering but by dissolution treatment. Therefore, in this reference example , in addition to the effects described in the twelfth reference example , the scrap 70 is mixed into the regenerated slurry 7, and not only the scrap 70 but also the abrasive particles 18 are removed. It is possible to prevent the recovery efficiency of the abrasive particles 18 from being reduced by filtering. Further, in this reference example , since the abrasive particles 18 other than the abrasive particles 18 are not reused, the regenerated slurry 7 has a polishing ability equivalent to that of the new slurry 7. Furthermore, in this reference example , since the abrasive particles 18 are aggregated and separated from the dispersion medium 25 or the like (for example , secondary particles having a particle diameter of about 100 μm are generated), the abrasive particles 18 can be recovered with high efficiency. .

In this reference example , the dissolution treatment of the shaving residue 70 in the dissolution treatment device 67 is performed by, for example, mixing the slurry 7 supplied from the slurry recovery device 63 and a nitric acid aqueous solution having a concentration of about 6 mol / L. Can do. In this case, the shaving residue 70, for example, copper oxide, is represented by the following reaction formula:
CuO + 2HNO ₃ → Cu (NO) ₃ + H ₂ O
Dissolve as shown.

In addition, the dissolution treatment of the shavings 70 in the dissolution treatment device 67 can be performed, for example, by mixing the slurry 7 supplied from the slurry recovery device 63 and an aqueous hydrochloric acid solution having a concentration of about 6 mol / L. In this case, the shaving residue 70, for example, copper oxide, is represented by the following reaction formula:
CuO + 2HCl → CuCl ₂ + H ₂ O
Dissolve as shown.

In the twelfth and thirteenth reference examples , the slurry 7 can contain an organic component other than an organic acid such as a surfactant. However, in the twelfth and thirteenth reference examples , the light irradiation devices 66a to 66c and the light irradiation devices 10 and / or 33 are kept on even when the slurry 7 does not contain a surfactant. By turning on intermittently, the abrasive particles 18 can be maintained in a good dispersed state. In addition, when the slurry 7 does not contain an organic substance, the organic component is not deteriorated, so that it is not necessary to add a new organic component to the regenerated slurry. Therefore, from the viewpoint of reducing running costs, the slurry 7 preferably does not contain an organic component. In addition, when not adding organic components, such as an organic acid, to the slurry 7, the pH of the slurry 7 can be adjusted by using an inorganic acid as a pH adjuster. Therefore, the slurry 7 can be composed of, for example, only the dispersion medium 25 such as water, the abrasive particles 18 such as titanium oxide particles, and the inorganic acid.

In the twelfth and thirteenth reference examples , the slurry 7 described in the first to ninth reference examples can be used. However, since the slurry 7 described in the fourth and fifth reference examples contains an organic component, it is preferable to use the slurry 7 described in the first to third and sixth to ninth reference examples. .

The technologies according to the reference examples described above can be combined with each other. For example, the abrasive particles 18 described in any of the seventh to ninth reference examples can be used in the slurry 7 described in the fifth or sixth reference example . In addition, at least one of the resin particles described in the fifth reference example and the inorganic particles described in the sixth reference example can be added to the slurry 7 described in the fourth reference example . In the fourth reference example, an example in which the resin particles described in the fifth reference example are added to the slurry 7 corresponds to an embodiment of the present invention. Furthermore, the abrasive particles 18 described in the first to third reference example, the abrasive particles described in the seventh reference example, by mixing together at least two kinds of abrasive particles 18 described in Reference example 8 Can also be used.

  Thus, for example, the following technique is provided here.

  That is, according to the first aspect, a chemical mechanical material containing a dispersion medium, abrasive particles dispersed in the dispersion medium and exhibiting a photocatalytic action by light irradiation, and a nonionic surfactant dissolved in the dispersion medium. A polishing slurry is provided.

  According to the second aspect, there is provided a slurry for chemical mechanical polishing containing a dispersion medium, abrasive particles dispersed in the dispersion medium and exhibiting a photocatalytic action by light irradiation, and resin particles dispersed in the dispersion medium. Provided.

  According to the third aspect, there is provided a chemical mechanical polishing slurry containing a dispersion medium, abrasive particles dispersed in the dispersion medium and exhibiting a photocatalytic action by light irradiation, and alumina particles dispersed in the dispersion medium. Provided.

  According to the fourth aspect, it contains a dispersion medium and abrasive particles dispersed in the dispersion medium and exhibiting a photocatalytic action by light irradiation, and the abrasive particles are titanium, oxygen, nickel, copper, silver, gold And at least one element selected from the group consisting of niobium and a slurry for chemical mechanical polishing.

  According to the fifth aspect, it contains a dispersion medium and abrasive particles dispersed in the dispersion medium and exhibiting a photocatalytic action by light irradiation. The abrasive particles are at least one of titanium, oxygen, nitrogen, and sulfur. Chemical mechanical polishing slurries containing the elements are provided.

  According to a sixth aspect, the abrasive particles include any one of the first to third aspects containing at least one compound selected from the group consisting of titanium oxide, tin oxide, niobium oxide, cadmium selenide, and cadmium sulfide. A slurry is provided.

  According to the seventh aspect, there is provided the slurry according to the fifth aspect, wherein the abrasive particles exhibit the photocatalytic action when irradiated with visible light.

  According to the eighth aspect, there is provided the slurry according to any one of the first to seventh aspects, wherein the abrasive particles exhibit the photocatalytic action when irradiated with ultraviolet rays.

  According to the ninth aspect, there is provided the slurry according to any one of the first to eighth aspects, wherein the oxidizing power of the abrasive particles is increased by the light irradiation.

  According to the tenth aspect, there is provided the slurry according to any one of the first to ninth aspects, wherein the hydrophilicity of the abrasive particles is increased by the light irradiation.

  According to an eleventh aspect, there is provided the slurry according to any one of the first to tenth aspects, wherein the abrasive particles contain titanium oxide having an anatase type crystal structure.

  According to the twelfth aspect, the primary particle size of the abrasive particles is distributed within a range of 5 nm to 1000 nm, and the secondary particle size of the abrasive particles is distributed within a range of 100 nm to 1000 nm. A slurry according to any of the 11 aspects is provided.

  According to the thirteenth aspect, there is provided the slurry according to the twelfth aspect, wherein the primary particle diameter of the abrasive particles is distributed within a range of 5 nm to 20 nm.

  According to the fourteenth aspect, when the chemical mechanical polishing process is performed on the portion to be polished of the substrate to be polished using the slurry according to any of the first to thirteenth aspects, the slurry is irradiated with light. A method for manufacturing a semiconductor device including the semiconductor device is provided.

  According to a fifteenth aspect, there is provided a method of manufacturing a semiconductor device for chemically and mechanically polishing a portion to be polished of a substrate to be polished by relatively moving a polishing member and a substrate to be polished, the polishing member and the substrate to be polished Supplying a slurry for chemical mechanical polishing containing a dispersion medium and abrasive particles dispersed in the dispersion medium and exhibiting a photocatalytic action by light irradiation between the substrate and the polishing member and the object to be polished There is provided a method of manufacturing a semiconductor device including irradiating light to the slurry interposed between the substrate and the substrate.

  According to a sixteenth aspect, there is provided a method according to the fourteenth or fifteenth aspect, wherein at least one of the light intensity and the light spectrum is changed during the chemical mechanical polishing process.

  According to the seventeenth aspect, the light intensity and the light spectrum according to at least one of a load applied to the substrate holder holding the substrate to be polished and a load applied to the polishing jig holding the polishing member. A method according to the sixteenth aspect for changing at least one of the above is provided.

  According to an eighteenth aspect, there is provided a method according to any one of the fourteenth to seventeenth aspects, wherein the light is irradiated from a side opposite to the portion to be polished of the substrate to be polished.

  According to a nineteenth aspect, there is provided the method according to any one of the fourteenth to eighteenth aspects, wherein the portion to be polished includes a layer containing a metal as a main component.

  According to the twentieth aspect, the metal-based layer is composed of a metal, an alloy, a metal nitride, a metal boride, a metal oxide, and a metal compound containing at least two of nitrogen, boron, and oxygen. A material selected from the group consisting of: a metal element selected from the group consisting of aluminum, copper, tungsten, titanium, molybdenum, niobium, tantalum, and vanadium as a constituent element. Such a method is provided.

  According to the twenty-first aspect, forming an insulating film provided with a recess on a semiconductor substrate, forming a barrier layer containing tungsten nitride on the insulating film, and covering the bottom surface and side walls of the recess Forming a metal layer containing copper on the barrier layer and embedding the recess, and chemically and mechanically polishing the metal layer, wherein the chemical and mechanical polishing includes a dispersion medium and the A slurry for chemical mechanical polishing containing abrasive particles dispersed in a dispersion medium and exhibiting a photocatalytic action by light irradiation is supplied onto the polishing member, and the slurry supplied onto the polishing member is irradiated with the light. And a method of manufacturing a semiconductor device, comprising: moving the polishing member and the semiconductor substrate relative to each other while the slurry irradiated with the light is interposed between the polishing member and the metal surface. It is provided.

  According to a twenty-second aspect, according to any one of the fourteenth to twenty-first aspects, the chemical mechanical polishing is performed while rotating a polishing member used for the chemical mechanical polishing at a rotation speed within a range of 60 rpm to 140 rpm. A method is provided.

  According to a twenty-third aspect, there is provided the method according to any one of the fourteenth to twenty-second aspects, wherein the polishing member used for the chemical mechanical polishing has a conductive component concentration of 3% by weight or less.

  According to a twenty-fourth aspect, there is provided a method according to any one of the seventeenth to twenty-third aspects, further comprising irradiating light to the slurry used for the chemical mechanical polishing after the chemical mechanical polishing. The

  According to the twenty-fifth aspect, a chemical mechanical polishing treatment is applied to a substrate to be polished using a slurry for chemical mechanical polishing containing a dispersion medium and abrasive particles dispersed in the dispersion medium and exhibiting a photocatalytic action by light irradiation. After that, a method for manufacturing a semiconductor device is provided in which light is irradiated toward the slurry used in the chemical mechanical polishing treatment.

  According to the twenty-sixth aspect, the portion to be polished of the substrate to be polished is chemically treated using a slurry for chemical mechanical polishing containing a dispersion medium and abrasive particles dispersed in the dispersion medium and exhibiting a photocatalytic action by light irradiation. Mechanically polishing, and removing scraps generated by the chemical mechanical polishing from the slurry used for the chemical mechanical polishing to generate a regenerated slurry usable for the chemical mechanical polishing. The manufacturing method of the semiconductor device including this is provided.

  According to the twenty-seventh aspect, the portion to be polished of the substrate to be polished is chemically treated using a slurry for chemical mechanical polishing containing a dispersion medium and abrasive particles dispersed in the dispersion medium and exhibiting a photocatalytic action by light irradiation. From mechanical polishing, dissolving the scraps generated in the slurry used in the chemical mechanical polishing and generated by the chemical mechanical polishing, and from the slurry dissolving the scraps There is provided a method for manufacturing a semiconductor device, comprising: recovering the abrasive particles; and generating a regenerated slurry that can be used for the chemical mechanical polishing using the recovered abrasive particles.

  According to the twenty-eighth aspect, the substrate holder that can hold the substrate to be polished, the polishing jig that can hold the polishing member, the substrate to be polished held by the substrate holder, and held by the polishing jig A drive mechanism for moving the substrate holder relative to the polishing jig while facing the polishing member, and the object to be polished held by the substrate holder of the polishing member held by the polishing jig A slurry supply device capable of supplying a chemical mechanical polishing slurry to a surface facing the substrate; and a light irradiation device for irradiating the slurry supplied to the surface of the polishing member facing the substrate to be polished. An apparatus for manufacturing a semiconductor device is provided.

  According to a twenty-ninth aspect, the light irradiation device emits the light to the back surface of the surface of the substrate to be polished facing the polishing member, and at least a part of the light emitted to the back surface of the substrate to be polished is An apparatus according to a twenty-eighth aspect is provided, configured to irradiate the slurry interposed between the substrate to be polished and the polishing member through the substrate to be polished.

  According to a thirtieth aspect, there is provided the apparatus according to the twenty-ninth or thirtieth aspect, wherein the intensity and / or spectrum of the light emitted by the light irradiation device is variable.

  According to a thirty-first aspect, there is provided the apparatus according to any one of the twenty-eighth to thirtieth aspects, wherein the light irradiation device can irradiate ultraviolet rays as the light.

  According to the thirty-second aspect, while storing a slurry for chemical mechanical polishing containing a dispersion medium and abrasive particles dispersed in the dispersion medium and exhibiting photocatalytic action by light irradiation, the light is applied to the slurry. A method is provided for handling chemical mechanical polishing slurries that are irradiated continuously or intermittently.

  According to a thirty-third aspect, the slurry for chemical mechanical polishing contains a dispersion medium and abrasive particles dispersed in the dispersion medium and exhibiting a photocatalytic action by light irradiation, and the oxidizing power of the abrasive particles is increased by the light irradiation. Is released into the natural environment, and a chemical mechanical polishing slurry handling method is provided that purifies at least one of the natural environment and the slurry by irradiating the slurry with light emitted into the natural environment.

  According to a thirty-fourth aspect, there is provided the method according to the thirty-second or thirty-third aspect, wherein the light is ultraviolet light.

  According to a thirty-fifth aspect, there is provided the method according to the thirty-fourth aspect, wherein the light is solar rays including ultraviolet rays.

(A), (b) is a figure which shows schematically the slurry for CMP which concerns on a 1st reference example . (A), (b) is sectional drawing which shows roughly an example of CMP using the slurry shown to Fig.1 (a), (b). The graph which shows the relationship between the particle size of an abrasive particle, and its sedimentation speed. (A) thru | or (c) is a figure which shows the crystal structure of anatase type, a rutile type, and a brookite type titanium oxide, respectively. The figure which shows the energy band of a titanium oxide. The figure which shows roughly an example of the CMP apparatus which can use the slurry shown to Fig.1 (a), (b). The graph which shows an example of the relationship between the polishing time and the load added to a table which can be observed in the case of CMP using the CMP apparatus shown in FIG. The figure which shows an example of the CMP performance which can be implement | achieved when the method shown in FIG. 7 is employ | adopted. (A), (b) is sectional drawing which shows roughly an example of CMP which concerns on a 2nd reference example . Sectional drawing which shows schematically the head of the CMP apparatus which can be utilized in the 2nd reference example . (A), (b) is sectional drawing which shows roughly an example of CMP which concerns on a 3rd reference example . Sectional drawing which shows the state between the state shown to Fig.11 (a), and the state shown to FIG.11 (b). The graph which shows the relationship between the width | variety of a buried wiring, and flatness. (A) is sectional drawing which shows schematically the other example of CMP which concerns on a 3rd reference example , (b) is sectional drawing which shows schematically the example of CMP which concerns on a prior art. The figure which shows the energy band of a titanium oxide. The graph which shows the relationship between the intensity | strength of the light irradiated to a slurry, and polishing rate. (A), (b) is a graph which shows the relationship between the intensity | strength of the light irradiated to a slurry, and a grinding | polishing speed | velocity obtained when an alumina particle and a silica particle are used as an abrasive particle, respectively. The graph which shows the relationship between the density | concentration of the abrasive particle in the slurry 7, and polishing rate. The graph which shows the relationship between pH of the slurry 7, and polishing rate. (A), (b) is sectional drawing which shows roughly the metal remainder which may arise when CMP is performed by the method which concerns on a 4th reference example . The graph which shows an example of the effect which addition of nonionic surfactant in a slurry suppresses generation | occurrence | production of an island-like residue part. The graph which shows an example of the effect which the addition of nonionic surfactant in a slurry improves a manufacturing yield. The graph which shows the relationship between the composition of a slurry, and polishing rate. Sectional drawing explaining the pattern density dependence of the grinding | polishing speed which may arise when CMP is performed by the method which concerns on a 3rd reference example . Sectional drawing which shows schematically CMP concerning the 5th reference example . The graph which shows an example of the effect which the addition of the resin particle in a slurry raises a grinding | polishing rate. Sectional drawing which shows schematically CMP concerning the 6th reference example . The graph which shows an example of the effect which the addition of the inorganic particle in a slurry raises a grinding | polishing rate. (A) is a figure which shows the energy band of a titanium oxide, (b) is a figure which shows the energy band of the titanium oxide which doped nitrogen, (c) is a figure which shows the energy band of an alumina or a silica. The graph which shows the relationship between the wavelength of the light irradiated to the abrasive particle, and the number of holes generated by photoexcitation. The graph which shows the relationship between the wavelength of the light irradiated to the abrasive particle, and the number of holes in the abrasive particle. The graph which shows the relationship between the wavelength of the light irradiated to the abrasive particle, and the number of holes in the abrasive particle. The graph which shows the relationship between the kind of abrasive particle, and polishing rate. The graph which shows the relationship between the storage days of the slurry for CMP, and the number of coarse particles in a slurry. The graph which shows the relationship between the storage days of CMP slurry, and polishing rate. The figure which shows schematically the reuse system of the slurry for CMP concerning a 12th reference example . The figure which shows schematically the reuse system of the slurry for CMP concerning a 13th reference example . (A), (b) is a figure which shows the conventional slurry for CMP roughly. (A), (b) is sectional drawing which shows roughly the example of CMP using the slurry for conventional CMP. The graph which shows the relationship between the rotation speed of a turntable, and polishing speed. The graph which shows the relationship between the kind of polishing pad, and polishing speed.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... CMP apparatus, 2 ... Polishing substrate, 3 ... Head, 5 ... Polishing pad, 6 ... Turntable, 7 ... Slurry for CMP, 8 ... Slurry supply apparatus, 8a ... Supply nozzle, 10 ... Light irradiation apparatus, 11 ... Head drive device, 12 ... Head sensor, 13 ... A / D converter, 14 ... Control device, 15 ... Table drive device, 16 ... Table sensor, 17 ... A / D converter, 18 ... Abrasive particles, 19 ... Housing , 20 ... secondary particles, 22 ... additive, 23 ... semiconductor substrate, 24, 24a, 24b ... insulating film, 25 ... dispersion medium, 26, 26a, 26b ... metal film, 27 ... titanium atom, 28 ... oxygen atom, 30, 30a, 30b ... barrier layer, 31 ... head, 32 ... suction chamber, 33 ... light irradiation device, 34 ... air passage, 35 ... backing film, 36 ... suction hole, 41 ... resin particle, 42 ... inorganic particle, 4 DESCRIPTION OF SYMBOLS ... Oxide film, 61 ... Reuse system, 62 ... Slurry supply apparatus, 63 ... Slurry collection apparatus, 64 ... Filter, 65 ... Regenerated slurry supply apparatus, 66a thru | or 66d ... Light irradiation apparatus, 67 ... Dissolution treatment apparatus, 68 ... Aggregation Equipment: 70 ... Shaving residue, 108 ... Dishing, 109 ... Scratch.

Claims (14)

Forming an insulating film provided with a recess on a semiconductor substrate;
Forming a barrier layer on the insulating film to cover the bottom and side walls of the recess;
Forming a metal layer containing copper on the barrier layer and embedding the recess;
Chemical mechanical polishing the metal layer,
The chemical mechanical polishing includes a dispersion medium, abrasive particles dispersed in the dispersion medium and exhibiting a photocatalytic action when irradiated with light, and dispersed in the dispersion medium, such as a methacrylic resin, a phenol resin, a urea resin, and a melamine resin. Chemical mechanical polishing slurry containing resin particles containing a material selected from the group consisting of polystyrene resin, polyacetal resin, polycarbonate resin, and a mixture containing at least one of them, and a nonionic surfactant On the polishing member, irradiating the slurry supplied onto the polishing member with light, and interposing the slurry irradiated with light between the polishing member and the metal layer And moving the polishing member and the semiconductor substrate relative to each other, the polishing particles are positively charged, and the resin particles are negatively charged in the molecule. The method of manufacturing a semiconductor device has been surface treated with include functional groups or silica tinged.   The method of manufacturing a semiconductor device according to claim 1, wherein the barrier layer includes tungsten nitride.   The method for manufacturing a semiconductor device according to claim 1, wherein the abrasive particles contain titanium, oxygen, and at least one element selected from the group consisting of nickel, copper, silver, gold, and niobium. .   The method for manufacturing a semiconductor device according to claim 1, wherein the abrasive particles contain titanium, oxygen, and at least one element of nitrogen and sulfur.   The method for manufacturing a semiconductor device according to claim 1, wherein the abrasive particles contain at least one compound selected from the group consisting of titanium oxide, tin oxide, niobium oxide, cadmium selenide, and cadmium sulfide.   The method for manufacturing a semiconductor device according to claim 4, wherein the abrasive particles exhibit the photocatalytic action when irradiated with visible light.   The method for manufacturing a semiconductor device according to claim 1, wherein the abrasive particles exhibit the photocatalytic action when irradiated with ultraviolet rays.   The method for manufacturing a semiconductor device according to claim 1, wherein the oxidizing power of the abrasive particles is increased by the light irradiation.   The method for manufacturing a semiconductor device according to claim 1, wherein the hydrophilicity of the abrasive particles is increased by the light irradiation.   The method for manufacturing a semiconductor device according to claim 1, wherein the abrasive particles contain titanium oxide having an anatase type crystal structure.   The primary particle diameter of the abrasive particles is distributed within a range of 5 nm to 1000 nm, and the secondary particle diameter of the abrasive particles is distributed within a range of 100 nm to 1000 nm. The manufacturing method of the semiconductor device as described in any one of.   The method for manufacturing a semiconductor device according to claim 11, wherein the primary particle diameter of the abrasive particles is distributed within a range of 5 nm to 20 nm.   13. The semiconductor device manufacturing according to claim 1, wherein the chemical mechanical polishing is performed while rotating a polishing member used for the chemical mechanical polishing at a rotation speed within a range of 60 rpm to 140 rpm. Method.   The method for manufacturing a semiconductor device according to claim 1, wherein a polishing member used for the chemical mechanical polishing has a conductive component concentration of 3 wt% or less.

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