JP3120513B2 - Dry etching method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry etching method applied in the field of manufacturing semiconductor devices and the like, and more particularly to a method of etching back a refractory metal layer formed by a so-called blanket CVD method, which has a highly smooth surface. To reduce particle contamination and suppress the loading effect.

[0002]

2. Description of the Related Art As the integration and performance of semiconductor devices have increased as seen in recent VLSIs and ULSIs, the proportion of wiring portions on a device chip tends to increase. In order to prevent a large increase in chip area due to this, multilayer wiring is now an essential technology. Conventionally, as a wiring forming method, a metal thin film made of aluminum or the like has been widely formed by a sputtering method. However, as described above, in a situation in which the wiring is multi-layered, and as a result, the surface step of the base and the aspect ratio of the connection hole are increasing, the upper layer wiring and the semiconductor substrate are insufficient due to insufficient step coverage in the sputtering method. A poor connection between them and a poor connection between wires have already become serious problems.

[0003] In recent years, a high melting point metal such as tungsten (W), molybdenum (Mo) or tantalum (Ta), or a metal such as aluminum (Al) or copper (Cu) has been selectively grown in a connection hole. There is proposed a technique for filling a connection hole having a high aspect ratio. A typical example of such a selective growth method is a selective CVD method in which a gas such as a metal fluoride or an organometallic compound is reduced by a lower wiring material to deposit a metal.

[0004] However, although the selective CVD method has obtained quite good results at the research level, the selectivity gradually deteriorates, or the controllability at the time of removing the etch back of the overgrown portion commonly called a nail head is poor. At present, there is no prospect of introduction to mass production, contrary to the initial expectations. A blanket CVD method has recently attracted attention in place of the selective CVD method. This is a technique of depositing a metal or an alloy on the entire surface of a base. For example, a process of forming a high melting point metal layer such as W as covering the entire surface of an insulating film having a connection hole and filling the connection hole is used. This is a typical example.

[0005]

When the high melting point metal layer is buried in the connection hole and used as a so-called plug material, it is necessary to etch back the high melting point metal layer. In this etch-back step, overetching of about 5 to 10% is usually performed in consideration of the uniformity of processing in the wafer surface. However, even in the same wafer surface, the etching rate is higher in a portion close to a region where the plasma density is relatively high in the etching apparatus as compared with the other portions,
An abrupt decrease in the area to be etched occurs early. Then, there is a problem that radicals which have lost the bonding partner (that is, the high melting point metal) and become relatively excessive concentrate in the connection holes, and largely erode the barrier metal and the high melting point metal layer embedded therein. This problem will be described with reference to FIG.

For example, as shown in FIG.
On a semiconductor substrate 31 on which an impurity diffusion region 32 has been formed in advance, an interlayer insulating film 33 having a connection hole 33a opened facing the impurity diffusion region 32 is formed. Is formed, and a blanket C is further formed.
Consider a case where the Blk-W layer 35 is formed by the VD method.

[0007] Here, the above Blk
When the −W layer 35 is etched back, F ^* becomes excessive early in the vicinity of the high plasma density region when the surface of the barrier metal 34 is exposed. This concentrates on the surface of the Blk-W layer 35 buried in the connection hole 33a, and a large eroded portion 36 as shown in FIG. 11B is formed during overetching.

Further, when the barrier metal 34 is etched back under different conditions, radicals become excessive at the time when the surface of the interlayer insulating film 33 is exposed.
Concentrate on a slight cross section of the barrier metal 34 embedded therein. As a result, a large erosion portion 37 is formed as shown in FIG.

The phenomenon in which radicals become relatively excessive with the decrease in the area of the material layer to be etched and the etching rate rapidly increases is called the loading effect. It is the cause that is actually preventing the conversion. In the field of semiconductor device manufacturing in the future, single-wafer plasma etching will be used to perform high-speed etching using high-density plasma so that the wafer diameter will increase as device chips become larger and the throughput will not decrease. It is expected that the loading effect will be even more pronounced since the device is expected to be mainstream. Therefore, an urgent solution is desired.

[0010] The blanket CVD method still has another important problem of improving smoothness. For example, as schematically shown in FIG.
The surface morphology of the lk-W layer 35 is rough. Therefore, B
When the lk-W layer 35 is etched back, its surface morphology becomes a barrier metal 34 as shown in FIG.
Then, the barrier metal 34 is etched back, and as shown in FIG.
Is also transcribed. Therefore, even if the loading effect is well suppressed, as shown in FIG.
Even if a is buried flat, the rough surface morphology remains on the surface of the wafer to the end. Such surface roughness is likely to adversely affect the adhesion and reliability of wiring formed in a later step, and thus needs to be eliminated.

As a means for eliminating such a loading effect and a rough surface morphology, the present applicant has previously filed Japanese Patent Application No. Hei.
In the specification of JP-60906, a Blk-W layer is etched using sulfur fluoride such as S ₂ F _2, and H ₂ , H ₂ S, a silane compound or the like is added to the sulfur fluoride during over-etching. Propose technology. The free S released by the sulfur fluoride into the plasma has an effect of depositing on the wafer and smoothing fine irregularities on the surface of the Blk-W layer. The additional gas is used at the time of over-etching in order to capture the excess F ^* by H ^* or Si ^* and increase the apparent S / F ratio of the etching reaction system. As a result, the etch back near the interface with the base is performed under the condition that the radical property is weakened, and the loading effect can be suppressed. Moreover, since the deposited S can be easily removed by heating the wafer, there is a great merit in that it does not cause any particle contamination.

As described above, the process utilizing the deposition of S is a promising technique for performing the etch back of the Blk-W layer, but in order to promote its practical use, there are as many options as possible. Research needs to be pursued with a policy of searching for the optimal process according to the content of etching. Under such circumstances, it is also significant to provide an approach different from the conventional one as the S / F ratio control technique.

Therefore, the present invention provides a method of controlling the S / X ratio, which is different from the change of the etching gas composition, when performing etching back of the refractory metal layer utilizing the deposition of S, thereby achieving a high level of surface smoothing. And a dry etching method capable of preventing a loading effect.

[0014]

The dry etching method of the present invention is proposed to achieve the above-mentioned object. That is, the dry etching method according to the first invention of the present application is a method for performing etch-back of the high melting point metal layer, wherein at least a part of the inner wall of the processing chamber is covered with the S-based material layer, and An etching gas containing a halogen-based compound is introduced into a plasma apparatus having a shutter member capable of making a contact area of the S-based material layer with plasma variable, and supplied from the sulfur-based material layer according to the contact area. And depositing S and / or S-based material to smooth the surface of the refractory metal layer.

A dry etching method according to a second aspect of the present invention is characterized in that the smoothing is performed prior to the etch-back of the refractory metal layer.

A dry etching method according to a third aspect of the present invention is characterized in that the smoothing is performed prior to over-etching.

Further, the dry etching method according to the fourth invention of the present application is characterized in that the smoothing is performed as a competitive reaction with the etch-back of the refractory metal layer.

[0018]

The present inventor has recognized that in order to control the S / X ratio without changing the composition of the etching gas, it is indispensable to devise the structure and use of the plasma apparatus. Examination proceeded. The configuration of the plasma apparatus according to the present invention includes a shutter member for arranging an S-based material layer on at least a part of the inner wall surface of the processing chamber and changing a contact area between the S-based material layer and the plasma. Is provided. In addition, the idea of the method of use is to set an S / X ratio optimal for a desired process by operating the shutter member, and to change the S / X ratio during the process as needed. is there.

That is, when the contact area between the S-based material layer and the plasma is increased by operating the shutter member, the supply amount of S from the S-based material layer is increased and the apparent appearance of the etching reaction system is increased. When the S / X ratio increases and becomes small, the opposite is true. This contact area may be optimized in advance according to the contents of the process. Strictly speaking, S
Depending on the type of the system material layer, a compound containing S as a constituent element may be sputtered as it is or in the form of a fragment in addition to simple S, but the description will be simplified in the following description. Therefore, only a single S is handled.

According to this method, the S / X ratio can be easily changed during the process only by mechanical operation of the shutter member. For example, in the present invention, S
The step where the / X ratio needs to be changed is a step of depositing S on the surface of the refractory metal layer and smoothing it. In this step, the contact area between the S-based material layer and the plasma may be increased by operating the shutter member. At this time, it is not necessary to change other parameters such as the wafer temperature and the composition ratio of the etching gas. Therefore, the time required for stabilizing the discharge state can be shortened, the throughput can be improved, and the reproducibility of the process can be improved.

This smoothing may be performed at any stage before the etch back or the over etching.
The former corresponds to the second invention of the present application, and the latter corresponds to the third invention of the present application. Further alternatively, the above-described smoothing may be performed as a competitive reaction with etch-back. this is,
This corresponds to the fourth invention of the present application.

In any case, the surface morphology of the refractory metal layer is smoothed before being transferred to the base such as a barrier metal or an interlayer insulating film, so that the base is roughened even at the end point of the etch back. There is no.

Further, in the present invention, since S to be deposited on the wafer is supplied from the S-based material layer in order to achieve high anisotropy and high selectivity, the compound which is a main component of the etching gas is not necessarily used. It is not necessary to have a releasable S atom as a constituent element in the molecule. Therefore, the halogen-based compound constituting the etching gas is SF
_6, NF ₃ or the like stable and versatile, and is a great merit that it can be used an inexpensive compound.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described.

Embodiment 1 This embodiment is an example in which the second invention of the present application is applied and etchback is performed after smoothing the surface of the Blk-W layer.

Before starting the description of the actual etching process, FIG. 7 shows an example of the configuration of an RF bias applying type magnetic field microwave plasma etching apparatus used in carrying out the present invention. I will explain while. The basic components are a magnetron 11 that generates a microwave of 2.45 GHz, a rectangular waveguide 12 and a circular waveguide 13 that guide the microwave, and an ECR (Electron Cyclotron Resonance) discharge using the microwave. A quartz bell jar 14 for generating ECR plasma P therein, the circular waveguide 13 and the bell jar 1
4.75 x 10 ^-2 T (87
5 Gauss), a sample coil 16 connected to the bell jar 14 and evacuated to a high vacuum in the direction of arrow A, and a gas required for processing is supplied to the sample chamber 16 and the bell jar 14 by arrows. Gas introduction pipe 17 supplied from B ₁ and B ₂ directions, wafer 1
A wafer mounting electrode 19 for mounting the wafer 8, a coolant buried in the wafer mounting electrode 19 and supplied from a cooling facility such as a chiller is circulated in the directions of arrows C ₁ and C ₂ , and the wafer 18 is cooled.
And a RF power supply 22 connected through a blocking capacitor 21 for applying an RF bias to the wafer mounting electrode 19.

Here, an S-based material layer 23 is provided on the inner wall surface of the bell jar 14 near the wafer 18. The S-based material layer 23 does not necessarily have to continuously circumnavigate the inner wall surface of the bell jar 14; for example, even if a block-shaped or plate-shaped solid is discontinuously arranged on the inner wall surface. good. Specific constituent materials of the S-based material layer 23 include sulfur (S), silicon sulfide (SiS or SiS ₂ ), polythiazyl [(SN) _x ], and the like. As the method for forming the S-based material layer 23, a plate-like body cut out from a film or a block formed by an appropriate method is adhered, or the S-based material layer 23 is formed by plasma CVD, electron beam evaporation, ECR sputtering, or the like. A method of forming a film directly on a wall surface or the like can be considered. In this example and Example 2 described later, the (SN) _x layer formed by the plasma CVD method was used.

Further, on the inner peripheral side of the S-based material layer 23, a cylindrical elevating shutter 24 which can be moved up and down in the direction of arrow D by a driving means (not shown) is provided. Here, FIG. 7A shows a state in which the S-based material layer 23 is almost completely shielded from the ECR plasma P by the elevating shutter 24 (shutter opening 0%), and FIG. This shows a state where the entire surface of the S-based material layer 23 is exposed by lowering the shutter 14 (shutter opening degree 100%).

FIG. 8 is a perspective view showing the inside of the bell jar 14 partially cut away to more clearly show the arrangement of the elevating shutter 24. As shown in FIG. The side wall surface of the bell jar 14, the elevating shutter 24, and the wafer mounting electrode 19 are all arranged concentrically. The contact area between the S-based material layer 23 and the ECR plasma P can be arbitrarily adjusted by changing the vertical distance of the vertical shutter 24 in the direction of arrow D.

The elevating shutter 24 can be formed by appropriately selecting a material that does not consume radicals and does not cause unnecessary contamination in the etching reaction system. Examples of such a material include stainless steel and alumina. Can be used. In this example and Example 2 described later, the elevating shutter 24 made of stainless steel was employed.

Next, the above-mentioned magnetic field-induced microwave plasma
The etch back of the Blk-W layer was actually performed using an etching apparatus. This process will be described with reference to FIGS. As shown in FIG. 1 as an example, a wafer 18 used as an etching sample in this embodiment has a connection hole 3a facing the impurity diffusion region 2 on a silicon substrate 1 on which the impurity diffusion region 2 has been previously formed. blanket CVD as but is formed SiO ₂ interlayer insulating film 3 having an opening, the connection degree thin TiN barrier metal 4 on the entire surface of the substrate to which no embedded hole 3a is formed to further cover the connection hole 3a embedded and entirely The Blk-W layer 5 is formed by the method. Here, in the blanket CVD method, for example, a WF ₆ flow rate of 25 SCCM, a SiH ₄ flow rate of 10 SCCM, a gas pressure of 1.06 × 10 ⁴ Pa (80 Torr), and a wafer temperature of 4
After nucleus growth for 20 seconds at 75 ° C., the gas supply conditions were WF ₆ flow rate 60 SCCM, H ₂ flow rate 360 SCC.
W was deposited by changing to M. The Blk-W layer 5 thus formed had a rough surface morphology as schematically illustrated.

Next, the wafer 18 is placed on the wafer mounting electrode 19 of the above-mentioned magnetic field microwave plasma etching apparatus.
, And an ethanol refrigerant was supplied to the cooling pipe 20. In this state, the surface of the Blk-W layer 5 was smoothed by performing plasma processing under the following conditions as an example. NF ₃ flow rate 20 SCCM Gas pressure 1.3 Pa (10 mTorr) Microwave power 850 W RF bias power 5 W (2 MHz) Wafer temperature −30 ° C. Shutter opening 100% In this process, the entire surface of the S-based material layer 23 comes into contact with plasma. As a result, S was released into the gas phase, and this S was deposited on the surface of the wafer cooled at a low temperature to form the S deposition layer 6. The S-based deposited layer 6 is mainly composed of a single S, but in the present embodiment, the S-based material layer 23 is formed of (S
Since it is composed of N) _x , it is possible that sputter products of the S-based material layer 23 contain (SN) _x formed by recombination in the gas phase. The S-based deposited layer 6 smoothed the surface of the wafer 18 by absorbing fine surface irregularities of the Blk-W layer 5.

Next, B is etched by a two-stage etch-back process.
The lk-W layer 5 was etched back. First, as a first etch-back step, for example, Blk-
The W layer 5 was etched back by about 90% of the layer thickness. NF ₃ flow rate 50 SCCM Gas pressure 1.3 Pa (10 mTorr) Microwave power 850 W RF bias power 30 W (2 MHz) Wafer temperature −10 ° C. Shutter opening 30% In this process, the radical reaction due to F ^* generated by dissociation from NF ₃ is generated. Etchback progressed by a mechanism assisted by the incident energy of ions such as NF _x ⁺ , and the Blk-W layer 5 and the S-based deposited layer 6 were removed in the form of WF _x , SF _{x and the} like, respectively. This etch back was stopped immediately before the TiN barrier metal 4 was exposed, as shown in FIG. As a result, the surface of the Blk-W layer 5 became smooth, and the concern that the surface morphology at the time of film formation was transferred to the base disappeared at this point.

The above-mentioned wafer temperature is set from the viewpoint of preventing the excessive deposition of an etching reaction product having a low vapor pressure while obtaining the advantage of low-temperature etching. When the wafer temperature drops to -20 ° C, WS
_x (tungsten sulfide) is excessively deposited, and there is a possibility that a drastic reduction in the etching rate or a dimensional conversion difference may occur.

Next, as a second etch-back step, only the shutter opening is set to 100% of the above etching conditions.
And the remaining part of the Blk-W layer 5 was etched back. In such a case, according to the conventional process, as shown in FIG. 4, excess F ^* at the time of exposing the surface of the TiN barrier metal 4 is concentrated in the connection hole 3a,
The Blk-W layer 5 is easily eroded significantly by the so-called loading effect. However, in this embodiment, the shutter opening is increased at this point, and the supply of S to the etching reaction system is promoted. Therefore, the etching rate was reduced due to the deposition of S or the capture of F ^* by S, and the loading effect could be effectively suppressed.

Finally, the wafer 18 was transferred to another chamber, and as an example, the TiN barrier metal 4 was etched back under the following conditions. Cl ₂ flow rate 40 SCCM O ₂ flow rate 10 SCCM Gas pressure 1.3 Pa (10 mTorr) Microwave power 850 W RF bias power 100 W (2 MHz) Wafer temperature 20 ° C. This etch back was stopped when the SiO ₂ interlayer insulating film 3 was exposed. . As a result, as shown in FIG. 5, the inside of the connection hole 3a was buried flat and smoothly by the plug composed of the TiN barrier metal 4 and the Blk-W layer 5.

The S remaining on the surface of the wafer 18 after the completion of the etching was easily sublimated and removed by heating the wafer 18 to about 90 ° C. or higher, and did not cause any particle contamination.

Embodiment 2 In this embodiment, the third invention of the present application is applied. After etching back the Blk-W layer substantially by the thickness of the Blk-W layer, the surface is smoothed and then overetched. This is an example. This process will be described with reference to FIGS. First, the same wafer 18 as that shown in FIG. 1 is set in the magnetic field microwave plasma etching apparatus described in the first embodiment, and the first wafer 18 described in the first embodiment is used.
The Blk-W layer 5 was etched back by almost the same layer thickness under the same conditions as in the etch-back step.

At this time, the etching rate becomes non-uniform on the surface of the wafer 18 due to the distribution of temperature, plasma density, and the like.
As shown in (a), Bl on TiN barrier metal 4
The kW layer 5 remains. The surface of the Blk-W layer 5 still has a rough morphology.

Therefore, the S-based deposition layer 6 was formed on the surface of the wafer 18 under the same conditions as in the plasma processing described in the first embodiment. As a result, as shown in FIG.
-The surface of the W layer 5 was smoothed. Thereafter, over-etching was performed under the same conditions as in the second etch-back step described in the first embodiment. As shown in FIG. 4 described above, this over-etching
The process was completed when the surface of the N barrier metal 4 was exposed.

Further, under the same conditions as in Example 1, Ti
The N barrier metal 4 was etched back. Finally, as shown in FIG. 5, the connection hole could be buried flat and smooth with a plug made of the Blk-W layer 5 while preventing the loading effect.

Embodiment 3 In this embodiment, an example in which the fourth invention of the present application is applied, the Blk-W layer is etched back substantially by the thickness of the Blk-W layer, and then overetching which also serves as smoothing is performed. It is. In this embodiment, unlike the above-described embodiments, a magnetic field microwave plasma etching apparatus equipped with a rotary shutter was used.

This device is similar to FIG. 7 in a schematic sectional view, but FIG. 9 is a perspective view in which the inside of the bell jar 14 is partially cut away. That is, the apparatus of the present embodiment includes the cylindrical rotary shutter 25 having the slit-shaped opening 25a, and the S-based material layer 23a is also formed in a band shape following the opening pattern of the opening 25a. ing. In this embodiment, as the S-based material layer 23a,
An SiS ₂ layer formed by electron beam evaporation was employed. The rotary shutter 25 is rotatable in a direction indicated by an arrow E by driving means (not shown). The rotary shutter 25 is made of, for example, stainless steel.

Here, the positional relationship between the rotary shutter 25 and the S-based material layer 23a will be described with reference to FIG. 9A is a cross-sectional view taken along the line FF of FIG. 9, wherein FIG. 9A is a state in which the S-based material layer 23 a is shielded by the rotary shutter 25 (shutter opening degree: 0%), and FIG. The state where the entire surface of the layer 23a is exposed through the opening 25a (the shutter opening is 100%) is shown. S-based material layer 23a and EC
The contact area with the R plasma P can be arbitrarily adjusted by changing the rotation angle of the rotary shutter 25.

The Blk-W layer was actually etched back using the above-mentioned magnetic field microwave plasma etching apparatus. First, the same wafer 18 as that shown in FIG. 1 is set in the magnetic field microwave plasma etching apparatus described in the first embodiment, and as an example, the Blk-W layer 5 is substantially removed under the following conditions. Etchback was performed by the layer thickness.

SF ₆ flow rate 50 SCCM Gas pressure 1.3 Pa (10 mTorr) Microwave power 850 W RF bias power 100 W (2 MHz) Wafer temperature 30 ° C. Shutter opening 0% In this process, a large amount of F ^* generated by dissociation from SF ₆ , The etch back progressed at high speed, but the Blk-W layer 5
Had a rough surface morphology.

Next, as an example, overetching which also serves as smoothing was performed under the following conditions. SF ₆ flow rate 20 SCCM Gas pressure 1.3 Pa (10 mTorr) Microwave power 850 W RF bias power 30 W (2 MHz) Wafer temperature −10 ° C. Shutter opening 100% In this process, the RF bias power is reduced and the wafer is Effects such as a decrease in the temperature and an increase in the shutter opening are synergistically exhibited, the etching rate is significantly reduced, and the loading effect is suppressed.

Further, under the same conditions as in Example 1, Ti
The N barrier metal 4 was etched back. Finally, as shown in FIG. 5, the connection hole could be buried flat and smooth with a plug made of the Blk-W layer 5 while preventing the loading effect.

Although the present invention has been described based on three embodiments, the present invention is not limited to these embodiments. For example, as the halogen-based compound contained in the etching gas, a compound that can provide a reaction product having a low vapor pressure may be appropriately selected according to the type of the high-melting point metal layer, and other than NF ₃ and SF ₆ described above. Cl ₂ , HCl,
BCl ₃ , Br ₂ , HBr, BBr ₃ , CBr ₄ , Si
Br ₄ , CH ₃ Br, CH ₂ Br ₂ , CHBr _{3 and the} like can be used. In addition, He,
A rare gas such as Ar may be added to obtain a cooling effect, a sputtering effect, a dilution effect, and the like.

The refractory metal layer is made of Mo, in addition to the above-described W layer.
Layer, a Ti layer, a Ta layer, or the like. Also, a barrier metal having a commonly used composition can be appropriately selected and used. At the time of over-etching, it is also possible to achieve better selectivity to the underlayer and lower damage by lowering the power of the RF bias or increasing the RF frequency.

The S deposited on the surface of the elevating shutter 24 or the rotating shutter 25 is provided with a heating mechanism in advance to these shutter members, and is operated each time one etching is completed to remove sublimation. Alternatively, it can be removed by performing plasma cleaning between sheet processing. These measures are effective in preventing an excessive increase in the S / X ratio of the etching reaction system.

[0052]

As is clear from the above description, according to the dry etching method of the present invention, the blanket CV
Etching back of the refractory metal layer formed by the method D can be performed while smoothing and suppressing the loading effect extremely well. Thereby, a highly reliable plug can be formed in the connection hole opened in the interlayer insulating film, and the adhesion and reliability of the wiring material layer laminated thereon can be improved.

Further, the S / X ratio of the etching reaction system during the process is controlled by mechanically controlling the contact area between the plasma and the S-based material layer provided on the inner wall of the processing chamber of the plasma apparatus by using a shutter member. It can be done quickly and easily by the clever technique of changing
Further, by supplying S for protecting the side wall from the S-based material layer, a stable and inexpensive general-purpose halogen compound can be used as an etching gas, and the economical advantage is great. Since S can be easily sublimated and removed by heating the wafer, it does not cause particle contamination.

Therefore, the present invention is designed based on a fine design rule, and is extremely useful for manufacturing a semiconductor device having high integration and high performance.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a state in which a Blk-W layer is formed in a process example in which a dry etching method of the present invention is applied to etchback of a Blk-W layer laminated with a TiN barrier metal.

FIG. 2 is a schematic cross-sectional view showing a state in which the surface of the Blk-W layer is smoothed by an S-based deposition layer.

FIG. 3 is a schematic sectional view showing a state in which the S-based deposited layer and a part of the Blk-W layer are etched back.

FIG. 4 is a schematic cross-sectional view showing a state where a remaining portion of the Blk-W layer is etched back.

FIG. 5 is a schematic sectional view showing a state where the TiN barrier metal is etched back.

FIG. 6 is a schematic cross-sectional view showing a part of the dry etching method according to the present invention in another process example in which the dry etching method is applied to the etch back of a Blk-W layer laminated with a TiN barrier metal in the order of steps; Shows a state where a part of the Blk-W layer is etched back, and (b) shows a state where the surface of the Blk-W layer is smoothed by the S-based deposition layer.

FIG. 7 is a schematic cross-sectional view showing an example of the configuration of an RF bias application type magnetic field microwave plasma etching apparatus used in carrying out the dry etching method of the present invention, and FIG. 0% shutter opening
(B) represents the case where the shutter opening is 100%.

FIG. 8 is a schematic perspective view showing a vertically movable shutter and its peripheral members of the magnetic field microwave plasma etching apparatus shown in FIG. 7, partially cut away;

FIG. 9 is a partial cutaway view of a rotary shutter and its peripheral members in another configuration example of an RF bias application type magnetic field microwave plasma etching apparatus used in carrying out the dry etching method of the present invention. It is a schematic perspective view shown.

10A and 10B are cross-sectional views taken along the line FF of FIG. 9; FIG. 10A shows a case where the shutter opening of the rotary shutter is 0%, and FIG. 10B shows a case where the shutter opening is 100%.

FIG. 11 is a schematic cross-sectional view for explaining a problem in the conventional etch back of a Blk-W layer, and FIG.
In the state where the lk-W layer is formed, (b) the surface morphology of the barrier metal is deteriorated and the Blk-W layer is eroded, and (c) the surface morphology of the interlayer insulating film is deteriorated and B
The lk-W layer and the barrier metal are eroded, respectively.

FIG. 12 is a schematic cross-sectional view for explaining another problem in the conventional etch back of the Blk-W layer, and shows a state where the surface morphology of the wafer is deteriorated.

[Explanation of symbols]

1 ... silicon substrate 2 ... impurity diffusion regions 3 ... SiO ₂ interlayer insulating film 3a ... connection hole 4 ... TiN barrier metal 5 ... Blk-W layer 6 ... S system sediments 14 ... bell jar 16 ... sample chamber 18 ... wafer 19 ... wafer mounting electrode 23, 23a ... S-based material layer 24 ... elevating shutter 25 ... rotary shutter 25a ··Aperture

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 21/3065 H01L 21/28 301 H01L 21/3205

Claims (4)

(57) [Claims] In a dry etching method for etching back a refractory metal layer, at least a part of an inner wall of a processing chamber is covered with a sulfur-based material layer, and the sulfur-based material layer is brought into contact with plasma. Etching and etching containing a halogen-based compound in a plasma apparatus having a shutter member capable of changing the area.
A step of introducing a gas, depositing sulfur and / or a sulfur-based material supplied from the sulfur-based material layer in accordance with the contact area, and smoothing the surface of the refractory metal layer. Dry etching method. 2. The dry etching method according to claim 1, wherein the smoothing is performed prior to the etch-back of the refractory metal layer. 3. The dry etching method according to claim 1, wherein said smoothing is performed prior to over-etching. 4. The dry etching method according to claim 1, wherein the smoothing is performed as a competitive reaction with etch back of the high melting point metal layer.