JP7650698B2 - Method for manufacturing polishing pad and polished product - Google Patents

Description

The present invention relates to a polishing pad and a method for manufacturing a polished product using the same.

In the semiconductor manufacturing process, chemical mechanical polishing (CMP) is used for planarization after insulating film deposition and for forming metal wiring. One of the important technologies required for chemical mechanical polishing is polishing end point detection, which detects whether the polishing process is complete. For example, over-polishing or under-polishing relative to the target polishing end point directly leads to product defects. Therefore, in chemical mechanical polishing, the amount of polishing must be strictly controlled by polishing end point detection.

Chemical mechanical polishing is a complex process, and the polishing speed (polishing rate) changes depending on the operating conditions of the polishing equipment, the quality of consumables (slurry, polishing pads, dressers, etc.), and variations in conditions over time during the polishing process. Furthermore, in recent years, the precision of remaining film thickness and in-plane uniformity required in semiconductor manufacturing processes have become increasingly strict. For these reasons, it has become more difficult to detect the polishing end point with sufficient precision.

The main methods for detecting the polishing end point are known to be optical end point detection, torque end point detection, and eddy current end point detection. In the optical end point detection method, the end point is detected by irradiating the wafer with light through a transparent window member installed on the polishing pad and monitoring the reflected light.

For example, Patent Document 1 discloses a polishing pad that uses such an optical end point detection method. The purpose of the polishing pad is to provide a polishing pad that can prevent slurry from accumulating in the grooves of the window member and increase the accuracy of polishing rate detection. The polishing pad has a pad body and a transparent window member that is integrally formed with a part of the pad body. The surface of the window member has a higher abrasiveness than the material of the pad body.

JP 2002-001647 A

However, if the polishing layer and the end point detection window have different characteristics as in Patent Document 1, for example, the end point detection window portion may be polished faster than the polishing layer, resulting in a recess, where slurry and polishing debris may easily accumulate, causing defects (surface defects). Also, if the end point detection window portion is polished slower than the polishing layer, the end point detection window may become a convex portion as polishing progresses, causing defects and potentially reducing the surface quality of the workpiece.

The present invention was made in consideration of the above problems, and aims to provide a polishing pad that has an end point detection window but is less likely to cause defects and can produce polished objects with excellent surface quality, as well as a method for manufacturing polished objects using the same.

The inventors conducted extensive research to solve the above problems. As a result, they discovered that the above problems could be solved by ensuring that the end point detection window and the viscoelasticity of the polishing layer have a specific relationship, and thus completed the present invention.

That is, the present invention is as follows.
[1]
The polishing method includes the steps of: (a) polishing a polishing layer formed in a polyurethane sheet; and (b) detecting an end point of the polishing layer by an end point detection window provided in an opening of the polyurethane sheet.
In dynamic viscoelasticity measurement performed under conditions of a tensile mode, a frequency of 1.0 Hz, and a temperature range of 10 to 100° C., the ratio (E' _P30 /E' _W30 ) of the storage modulus E' _W30 at 30° C. of the end point detection window to the storage modulus E' _P30 of the polyurethane sheet at 30° C. is 0.60 to 1.50.
Polishing pad.
[2]
The end point detection window contains polyurethane resin W.
The polishing pad according to [1].
[3]
The polyurethane resin W contains a structural unit derived from an alicyclic isocyanate and/or an aliphatic isocyanate.
The polishing pad according to [2].
[4]
The polyurethane resin W contains a structural unit derived from a compound having three or more hydroxyl groups.
The polishing pad according to [2] or [3].
[5]
In the dynamic viscoelasticity measurement, the ratio ( _E'P50 / _E'W50 ) of the storage modulus _E'W50 at 50°C of the end point detection window to the storage modulus _E'P50 of the polyurethane sheet at 50°C is 0.70 to 2.00.
The polishing pad according to any one of [1] to [4].
[6]
In the dynamic viscoelasticity measurement in the end point detection window, the storage modulus E' _W30 at 30°C is 10 x 10 ⁷ to 60 x 10 ⁷ Pa.
The polishing pad according to any one of [1] to [5].
[7]
The D hardness (D _W20 ) at 20° C. of the end point detection window is 40 to 70;
The polishing pad according to any one of [1] to [6].
[8]
The polyurethane sheet contains a polyurethane resin P and hollow fine particles dispersed in the polyurethane resin P.
The polishing pad according to any one of [1] to [7].
[9]
A polishing step of polishing an object to be polished using the polishing pad according to any one of [1] to [8] in the presence of a polishing slurry;
and an end point detection step of detecting an end point during the polishing by an optical end point detection method.
A method for manufacturing polished workpieces.

The present invention provides a polishing pad that has an end point detection window, yet is less prone to defects and can produce polished objects with excellent surface quality, as well as a method for manufacturing polished objects using the same.

1 is a schematic perspective view of a polishing pad according to an embodiment of the present invention. 3 is a schematic cross-sectional view of an end point detection window portion of the polishing pad of the present embodiment. FIG. 10 is a schematic cross-sectional view of another aspect of the end point detection window portion of the polishing pad of the present embodiment. FIG. FIG. 1 is a schematic diagram showing a film thickness control system installed in CMP.

Below, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail with reference to the drawings as necessary, but the present invention is not limited to this, and various modifications are possible without departing from the gist of the invention. In the drawings, the same elements are given the same reference numerals, and duplicated explanations will be omitted. Furthermore, unless otherwise specified, positional relationships such as up, down, left, and right will be based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios of the drawings are not limited to those shown in the drawings.

1. Polishing Pad The polishing pad of this embodiment has a polyurethane sheet that serves as a polishing layer, and an end point detection window provided at an opening of the polyurethane sheet, and in dynamic viscoelasticity measurement performed under conditions of a tensile mode, a frequency of 1.0 Hz, and a temperature of 10 to 100°C _, the ratio (E'P30/ _E'W30 ) of the storage modulus _E'W30 at 30°C of the end point detection window to the storage modulus _E'P30 of the polyurethane sheet at 30°C is 0.60 to 1.50.

As a result, the dynamic viscoelastic properties of the polishing layer and the end point detection window become closer during polishing, so that even if the end point detection window, which is a different material, is embedded in the polishing layer, the occurrence of defects (surface imperfections) on the surface of the workpiece is further suppressed. This makes it possible to obtain a polished workpiece with excellent surface quality.

Figure 1 shows a schematic perspective view of the polishing pad of this embodiment. As shown in Figure 1, the polishing pad 10 of this embodiment has a polishing layer 11, which is a polyurethane sheet, and an end point detection window 12, and may have a cushion layer 13 on the side opposite the polishing surface 11a, if necessary.

Figures 2 and 3 show cross-sectional views of the periphery of the end point detection window 12 in Figure 1. As shown in Figures 2 and 3, an adhesive layer 14 may be provided between the polishing layer 11 and the cushion layer 13, and an adhesive layer 15 may be provided on the surface of the cushion layer 13 for bonding to the table 22 in Figure 4. The polishing surface 11a of the polishing pad of this embodiment may be flat as shown in Figure 2, or may be uneven with grooves 16 formed therein as shown in Figure 3. The grooves 16 may be formed by using a variety of groove shapes, such as multiple concentric circles, lattice patterns, and radial patterns, either alone or in combination.

1.1 End point detection window The end point detection window is a transparent member provided in an opening of the polyurethane sheet, and serves as a transmission path for light from the film thickness detection sensor in optical end point detection. In this embodiment, the end point detection window is circular, but may be square, rectangular, polygonal, elliptical, or other shapes as necessary.

In this embodiment, the ratio of the storage modulus E' between the end point detection window and the polyurethane sheet is specified from the viewpoint of adjusting the degree of wear of the end point detection window and the polishing layer during polishing and preventing the occurrence of defects (surface defects) in the non-polished object due to excessive polishing of either the end point detection window or the polishing layer.

The storage modulus E' of the endpoint detection window and the polyurethane sheet in this embodiment can be determined by dynamic viscoelasticity measurement in a tensile mode at a frequency of 1.0 Hz and at 10 to 100° C. In this embodiment, the ratio of the storage modulus E' at 30° C. is specified from the viewpoint of expressing the characteristics of the endpoint detection window and the polyurethane sheet during polishing.

The ratio ( _E'P30 / _E'W30 ) of the storage modulus _E'W30 of the endpoint detection window at 30°C to the storage modulus _E'P30 of the polyurethane sheet at 30°C is 0.60 to 1.50, preferably 0.60 to 1.35, and more preferably 0.60 to 1.20. When the ratio ( _E'P30 / _E'W30 ) is within the above range, the properties of the endpoint detection window and the polyurethane sheet during polishing are similar, and the surface quality of the resulting polished object is further improved.

From the same viewpoint, in dynamic viscoelasticity measurement, the ratio ( _E'P50 / _E'W50 ) of the storage modulus _E'W50 of the endpoint detection window at 50°C to the storage modulus _E'P50 of the polyurethane sheet at 50°C is preferably 0.70 to 2.00, more preferably 0.70 to 1.85, and even more preferably 0.70 to 1.70. When the ratio ( _E'P50 / _E'W50 ) is within the above range, the properties of the endpoint detection window and the polyurethane sheet during polishing are similar, and the surface quality of the obtained polished object tends to be further improved.

In the dynamic viscoelasticity measurement of the endpoint detection window, the storage modulus E' _W30 at 30° C. is preferably 10×10 ⁷ to 60×10 ⁷ Pa, more preferably 15×10 ⁷ to 55×10 ⁷ Pa, and even more preferably 20×10 ⁷ to 50×10 ⁷ Pa. When the storage modulus E' _W30 is within the above range, the surface quality of the obtained polished object tends to be further improved.

There are no particular limitations on the conditions for measuring dynamic viscoelasticity, but measurements can be performed under the conditions described in the examples.

1.1.2 D Hardness The D hardness (D _W20 ) at 20° C. in the endpoint detection window is 40 to 70, preferably 45 to 70, and more preferably 50 to 65. When the D hardness (D _W20 ) is within the above range, the occurrence of defects (surface defects) tends to be further suppressed.

There are no particular limitations on the conditions for measuring D hardness, but it can be measured under the conditions described in the examples.

1.1.3. Constituent material The material constituting the end point detection window is not particularly limited as long as it is a transparent member capable of functioning as a window, and examples thereof include polyurethane resin W, polyvinyl chloride resin, polyvinylidene fluoride resin, polyethersulfone resin, polystyrene resin, polyethylene resin, polytetrafluoroethylene resin, etc. Among these, polyurethane resin W is preferable. By using such a resin, it is easier to adjust the dynamic viscoelastic properties, D hardness, and transparency.

Polyurethane resin W can be synthesized from polyisocyanate and polyol, and contains structural units derived from polyisocyanate and structural units derived from polyol.

1.1.3.1. Polyisocyanate-derived structural units The polyisocyanate-derived structural units are not particularly limited, and examples thereof include alicyclic isocyanate-derived structural units, aliphatic isocyanate-derived structural units, and aromatic isocyanate-derived structural units. Among these, it is preferable that the polyurethane resin W contains alicyclic isocyanate and/or aliphatic isocyanate-derived structural units. This makes it easier to adjust the dynamic viscoelasticity and D hardness to within the above ranges, and the transparency is improved, and the yellowing resistance of the window tends to be improved.

Alicyclic isocyanates are not particularly limited, but examples include 4,4'-methylene-bis(cyclohexyl isocyanate) (hydrogenated MDI), cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4-diisocyanate, and isophorone diisocyanate.

Aliphatic isocyanates include, but are not limited to, hexamethylene diisocyanate (HDI), pentamethylene diisocyanate (PDI), tetramethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, trimethylene diisocyanate, trimethylhexamethylene diisocyanate, etc.

Aromatic isocyanates include, but are not limited to, phenylene diisocyanate, 2,6-tolylene diisocyanate (2,6-TDI), 2,4-tolylene diisocyanate (2,4-TDI), xylylene diisocyanate, naphthalene diisocyanate, and diphenylmethane-4,4'-diisocyanate (MDI).

1.1.3.2. Structural Units Derived from Polyols Structural units derived from polyols are not particularly limited, but examples include low molecular weight polyols having a molecular weight of less than 300 and high molecular weight polyols having a molecular weight of 300 or more.

The low molecular weight polyol is not particularly limited, but examples thereof include low molecular weight polyols having two hydroxyl groups such as ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 1,4-butylene glycol, 1,5-pentanediol, neopentyl glycol, 1,6-hexane glycol, 2,5-hexanediol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol, tricyclodecane dimethanol, and 1,4-cyclohexane dimethanol; and low molecular weight polyols having three or more hydroxyl groups such as glycerin, hexanetriol, trimethylolpropane, isocyanuric acid, and erythritol. The low molecular weight polyols may be used alone or in combination of two or more.

Among these, low molecular weight polyols having three or more hydroxyl groups are preferred, and glycerin is more preferred. By using such low molecular weight polyols, it becomes easier to adjust the dynamic viscoelastic properties and D hardness to within the above ranges, the amount of wear can be adjusted, transparency is improved, and the yellowing resistance of the window tends to be improved.

The content of the structural units derived from a low molecular weight polyol having three or more hydroxyl groups is preferably 7.5 to 30 parts, more preferably 10 to 25 parts, and even more preferably 12.5 to 20 parts, per 100 parts of the structural units derived from the polyisocyanate. When the content of the structural units derived from a low molecular weight polyol having three or more hydroxyl groups is within the above range, it becomes easier to adjust the dynamic viscoelastic properties and D hardness within the above range, transparency is further improved, and the yellowing resistance of the window tends to be further improved.

The polymer polyol is not particularly limited, but examples thereof include polyether polyol, polyester polyol, polycarbonate polyol, polyether polycarbonate polyol, polyurethane polyol, epoxy polyol, vegetable oil polyol, polyolefin polyol, acrylic polyol, and vinyl monomer modified polyol. The polymer polyol may be used alone or in combination of two or more kinds.

The number average molecular weight of the polymer polyol is preferably 300 to 3000, more preferably 500 to 2500, and even more preferably 850 to 2000. By using such a polymer polyol, it tends to be easier to adjust the dynamic viscoelastic properties and D hardness to within the above ranges.

Among these, polyether polyols are preferred, and polytetramethylene ether glycol is more preferred. By using such polymer polyols, it is easy to adjust the dynamic viscoelastic properties and D hardness within the above ranges, it is easy to adjust the hardness at low temperatures, and it is possible to suppress the decrease in hardness that accompanies an increase in temperature. In addition to further improving transparency, there is a tendency for the window's yellowing resistance to be further improved.

The content of the structural units derived from polyether polyol is preferably 80 to 200 parts, more preferably 85 to 160 parts, and even more preferably 90 to 140 parts, per 100 parts of the structural units derived from polyisocyanate. When the content of the structural units derived from polyether polyol is within the above range, it becomes easier to adjust the dynamic viscoelastic properties and D hardness to within the above range, and transparency is further improved, and the yellowing resistance of the window tends to be further improved.

As the polyol, it is preferable to use a combination of a low molecular weight polyol and a high molecular weight polyol, and it is more preferable to use a combination of a low molecular weight polyol having three or more hydroxyl groups and a polyether polyol. This makes it easier to adjust the dynamic viscoelastic properties and D hardness to within the above ranges, further improving transparency and tending to further improve the yellowing resistance of the window.

From the above viewpoints, the content of polyether polyol is preferably 2.0 to 15.0 parts, more preferably 3.0 to 12.5 parts, and even more preferably 4.0 to 9.0 parts per part of low molecular weight polyol having three or more hydroxyl groups.

1.2. Polishing Layer A polyurethane sheet is used as the polishing layer in this embodiment. This polyurethane sheet has an opening in which an end point detection window is embedded. The position of the opening is not particularly limited, but it is preferable to provide it at a radial position corresponding to the film thickness detection sensor 23 installed on the table 22. In addition, the number of openings is not particularly limited, but it is preferable to have multiple openings at similar radial positions so that the window passes over the film thickness detection sensor 23 multiple times when the polishing pad 10 attached to the table 22 rotates once.

The form of the polyurethane sheet is not particularly limited, but examples include foamed polyurethane sheets, non-foamed polyurethane sheets made of resin, and sheets made of a fiber substrate impregnated with polyurethane.

Here, a resin foamed molded body refers to a foamed body that does not have a fiber base material and is composed of a specific resin. There are no particular limitations on the foam shape, but examples include spherical bubbles, nearly spherical bubbles, teardrop-shaped bubbles, and open bubbles in which each bubble is partially connected.

In addition, the term "non-foamed resin molded body" refers to a non-foamed body that does not have a fiber substrate and is composed of a specific resin. A non-foamed body refers to a body that does not have bubbles as described above. In the first embodiment, the non-foamed resin molded body also includes a body in which a curable composition is attached to a substrate such as a film and cured. More specifically, the non-foamed resin molded body also includes a cured resin product formed by a ravia coater method, a small-diameter gravure coater method, a reverse roll coater method, a transfer roll coater method, a kiss coater method, a die coater method, a screen printing method, a spray coating method, or the like.

Furthermore, a resin-impregnated substrate is one obtained by impregnating a fiber substrate with a resin. Here, the fiber substrate is not particularly limited, but examples thereof include woven fabric, nonwoven fabric, and knitted fabric.

In dynamic viscoelasticity measurement of the polishing layer, the storage modulus E' _P30 at 30° C. is preferably 15×10 ⁷ to 65×10 ⁷ Pa, more preferably 20×10 ⁷ to 60×10 ⁷ Pa, and even more preferably 25×10 ⁷ to 55×10 ⁷ Pa. When the storage modulus E' _P30 is within the above range, the surface quality of the obtained polished object tends to be further improved.

In dynamic viscoelasticity measurement of the polishing layer, the storage modulus E' _P50 at 50° C. is preferably 10×10 ⁷ to 40×10 ⁷ Pa, more preferably 15×10 ⁷ to 35×10 ⁷ Pa, and even more preferably 20×10 ⁷ to 30×10 ⁷ Pa. When the storage modulus E' _P50 is within the above range, the surface quality of the obtained polished object tends to be further improved.

1.2.2 Polyurethane Sheet The polyurethane resin P constituting the polyurethane sheet is not particularly limited, but examples thereof include polyester-based polyurethane resins, polyether-based polyurethane resins, and polycarbonate-based polyurethane resins. These may be used alone or in combination of two or more.

Such polyurethane resin P can be synthesized from polyisocyanate and polyol, and in particular, a reaction product of a urethane prepolymer and a curing agent is preferable. Here, the urethane prepolymer can be synthesized from polyisocyanate and polyol. The polyisocyanate, polyol, and curing agent that make up the polyurethane resin P are described below.

1.2.2.1. Structural units derived from polyisocyanates The structural units derived from polyisocyanates are not particularly limited, and examples thereof include structural units derived from alicyclic isocyanates, structural units derived from aliphatic isocyanates, and structural units derived from aromatic isocyanates. Among these, aromatic isocyanates are preferred, and 2,4-tolylene diisocyanate (2,4-TDI) is more preferred.

Examples of alicyclic isocyanates, aliphatic isocyanates, and aromatic isocyanates include those exemplified in the endpoint detection window above.

1.2.2.2. Structural units derived from polyols The structural units derived from polyols are not particularly limited, and examples thereof include low molecular weight polyols having a molecular weight of less than 300 and high molecular weight polyols having a molecular weight of at least 300. Among these, it is preferable to use at least a low molecular weight polyol, and it is preferable to use a low molecular weight polyol and a high molecular weight polyol in combination.

Examples of low molecular weight polyols and high molecular weight polyols include those exemplified in the endpoint detection window above. Among these, low molecular weight polyols are preferably low molecular weight polyols having two hydroxyl groups, and diethylene glycol is more preferred. Furthermore, high molecular weight polyols are preferably polyether polyols, and polytetramethylene ether glycol is more preferred.

1.2.2.3. Curing agent The curing agent is not particularly limited, but examples thereof include polyamines and polyols. The curing agents may be used alone or in combination of two or more.

The polyamines are not particularly limited, but examples thereof include aliphatic polyamines such as ethylenediamine, propylenediamine, and hexamethylenediamine; alicyclic polyamines such as isophoronediamine and dicyclohexylmethane-4,4'-diamine; and aromatic polyamines such as 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA), 4-methyl-2,6-bis(methylthio)-1,3-benzenediamine, 2-methyl-4,6-bis(methylthio)-1,3-benzenediamine, and 2,2-bis(3-amino-4-hydroxyphenyl)propane.

Among these, aromatic polyamines are preferred, and it is more preferable to use 3'-dichloro-4,4'-diaminodiphenylmethane (MOCA).

Examples of polyols include the same polyols as those exemplified in the endpoint detection window above. Among these, polymer polyols are preferred, polyether polyols are more preferred, and polypropylene glycol is even more preferred.

The polyurethane sheet is preferably a foamed polyurethane sheet containing a polyurethane resin P and hollow fine particles dispersed in the polyurethane resin P. Such a polyurethane sheet has closed cells derived from the hollow fine particles, and tends to have the dynamic viscoelastic properties and D hardness easily adjusted to within the above ranges.

The hollow microparticles may be commercially available or may be synthesized by a conventional method. The material of the shell of the hollow microparticles is not particularly limited, but examples include polyvinyl alcohol, polyvinylpyrrolidone, poly(meth)acrylic acid, polyacrylamide, polyethylene glycol, polyhydroxyether acrylate, maleic acid copolymer, polyethylene oxide, polyurethane, acrylonitrile-vinylidene chloride copolymer, acrylonitrile-methyl methacrylate copolymer, vinyl chloride-ethylene copolymer, etc.

The shape of the hollow microparticles is not particularly limited, and may be, for example, spherical or nearly spherical. In addition, when the hollow microparticles are expandable balloons, they may be used in an unexpanded state or in an expanded state.

The average particle size of the hollow microparticles contained in the polyurethane sheet is preferably 5 to 200 μm, more preferably 5 to 80 μm, even more preferably 5 to 50 μm, and particularly preferably 5 to 35 μm. By having the average particle size within the above range, it tends to be easier to adjust the dynamic viscoelastic properties and D hardness to within the above range. The average particle size can be measured using a laser diffraction particle size distribution measuring device (for example, Mastersizer 2000, manufactured by Spectris Co., Ltd.).

1.3. Others The polishing pad of this embodiment may have a cushion layer on the side opposite to the polishing surface of the polishing layer, or may have an adhesive layer between the polishing layer and the cushion layer, or on the surface of the cushion layer that is not on the polishing layer side (the surface that is attached to the polishing machine). In this case, the cushion layer and the adhesive layer have an opening in the same location as the end point detection window of the polishing layer.

2. Manufacturing Method of Polishing Pad The manufacturing method of the polishing pad of this embodiment is not particularly limited, but may include, for example, a step of filling a resin composition constituting the polishing layer into a mold to which a window member serving as an end point detection window is fixed, and curing the resin composition to obtain a resin block in which the window member is embedded, and a step of slicing the obtained resin block to obtain a polyurethane sheet having an end point detection window in an opening thereof, and the polishing surface of the obtained polyurethane sheet may be dressed as necessary.

The temperature during slicing is preferably 70 to 100°C. The temperature during dressing is preferably 20 to 30°C.

3. Manufacturing method of polished product The manufacturing method of the polished product of this embodiment includes a polishing step of polishing a workpiece using the polishing pad in the presence of a polishing slurry to obtain a polished product, and an end point detection step of detecting the end point during the polishing by an optical end point detection method.

3.1 Polishing process The polishing process may be a primary lapping process (rough lapping), a secondary lapping process (finish lapping), a primary polishing process (rough polishing), a secondary polishing process (finish polishing), or a process that combines these processes. Here, "lapping" refers to polishing at a relatively high rate using coarse abrasive grains, and "polishing" refers to polishing at a relatively low rate using fine abrasive grains to improve the surface quality.

Among these, the polishing pad of this embodiment is preferably used for chemical mechanical polishing (CMP). Below, the method for manufacturing the polished product of this embodiment will be explained using chemical mechanical polishing as an example, but the method for manufacturing the polished product of this embodiment is not limited to the following.

The object to be polished is not particularly limited, but examples thereof include materials such as semiconductor devices and electronic components, particularly thin substrates (objects to be polished) such as Si substrates (silicon wafers), SiC (silicon carbide) substrates, GaAs (gallium arsenide) substrates, glass, and substrates for hard disks and LCDs (liquid crystal displays). In particular, semiconductor devices having metal wiring such as W (tungsten) and Cu (copper) are included.

The polishing method may be a conventionally known method, and is not particularly limited. For example, first, the object to be polished held on a holding platen arranged opposite the polishing pad is pressed against the polishing surface, and the polishing pad and/or holding platen are rotated while supplying slurry from the outside. The polishing pad and holding platen may rotate in the same direction at different rotation speeds, or in different directions. In addition, the object to be polished may be polished while moving (rotating) inside the frame during the polishing process.

The slurry may contain water, chemical components such as an oxidizing agent represented by hydrogen peroxide, additives, abrasive grains (abrasive particles; for example, SiC, SiO ₂ , Al ₂ O ₃ , CeO ₂ ), etc. depending on the object to be polished and the polishing conditions.

3.2 End point detection process The method for manufacturing a polished workpiece according to the present embodiment includes an end point detection process for detecting the end point by an optical end point detection method in the polishing process. As the end point detection method by the optical end point detection method, a conventionally known method can be used.

Figure 4 shows a schematic diagram of an optical end point detection method. This schematic diagram shows a chemical mechanical polishing process in which a wafer W held by a top ring 21 is pressed against a polishing pad 10 attached to a table 22 while a slurry 24 is flowing thereon to remove the uneven film on the surface of the wafer W and flatten it. The polishing device 20 is equipped with a film thickness detection sensor 23 on the table 22 to monitor the film thickness in order to end the process accurately by detecting a predetermined film thickness at the same time as flattening. The film thickness detection sensor 23 can detect the polishing end point by, for example, irradiating the polishing surface of the wafer W with light and measuring and analyzing the spectral intensity characteristics of the reflected light.

More specifically, the film thickness detection sensor 23 can detect changes in film thickness by irradiating light onto the surface of the wafer W through the end point detection window 12 and detecting the strength of the reflection intensity caused by the phase difference between the light reflected by the film on the wafer W (wafer surface) and the light reflected at the interface between the film on the wafer W and the wafer substrate.

The present invention will be described in more detail below using examples and comparative examples. The present invention is not limited to the following examples. Note that "parts" refers to parts by mass.

[Production Example 1: End Point Detection Window 1]
A transparent member to become the end point detection window 1 was obtained by reacting 100 parts of 4,4' methylene bis (cyclohexyl isocyanate), 120.9 parts of poly (oxytetramethylene) glycol (PTMG) having a number average molecular weight of 1000, and 14.8 parts of glycerin.

[Production Example 2: End Point Detection Window 2]
A transparent member to become the end point detection window 2 was obtained by reacting 100 parts of 4,4' methylene bis (cyclohexyl isocyanate), 103.6 parts of poly (oxytetramethylene) glycol (PTMG) having a number average molecular weight of 1000, and 15.9 parts of glycerin.

[Production Example 3: End Point Detection Window 3]
A transparent member for the end point detection window 3 was obtained by reacting 100 parts of 4,4' methylene bis (cyclohexyl isocyanate), 96.7 parts of poly (oxytetramethylene) glycol (PTMG) having a number average molecular weight of 1000, and 16.3 parts of glycerin.

[Production Example 4: End Point Detection Window 4]
A transparent member for the end point detection window 4 was obtained by reacting 100 parts of 4,4' methylene bis (cyclohexyl isocyanate), 90.6 parts of poly (oxytetramethylene) glycol (PTMG) having a number average molecular weight of 1000, and 16.7 parts of glycerin.

[Production Example 5: End Point Detection Window 5]
A transparent member for the end point detection window 5 was obtained by reacting 100 parts of 4,4' methylene bis (cyclohexyl isocyanate), 78.6 parts of poly (oxytetramethylene) glycol (PTMG) having a number average molecular weight of 650, and 14.8 parts of glycerin.

[Production Example 6: End Point Detection Window 6]
A transparent member for use as the end point detection window 6 was obtained by reacting 100 parts of 4,4' methylene bis (cyclohexyl isocyanate), 78.6 parts of poly (oxytetramethylene) glycol (PTMG) having a number average molecular weight of 650, 10.5 parts of ethylene glycol, and 4.5 parts of glycerin.

Example 1
2,4-tolylene diisocyanate (2,4-TDI), poly(oxytetramethylene) glycol (PTMG) having an average molecular weight of 650, poly(oxytetramethylene) glycol (PTMG) having a number average molecular weight of 1000, and diethylene glycol (DEG) were reacted to obtain 100 parts of a urethane prepolymer having an NCO equivalent of 455. The shell portion was made of an acrylonitrile-vinylidene chloride copolymer, and 2.7 parts of unexpanded hollow fine particles (average particle size: 8.5 μm) were added and mixed to obtain a urethane prepolymer mixed liquid. The obtained urethane prepolymer mixed liquid was charged into a first liquid tank and kept warm at 60 ° C. In addition, 25.8 parts of 3,3'-dichloro-4,4'-diaminodiphenylmethane (methylene bis-o-chloroaniline) (MOCA) was charged into a second liquid tank as a curing agent, and the mixture was heated and melted at 120 ° C. and mixed, and further degassed under reduced pressure to obtain a curing agent melt liquid.

Next, the liquids in the first liquid tank and the second liquid tank were poured into a mixer equipped with two injection ports, and mixed by stirring to obtain a mixed liquid.

The resulting mixture was then poured into a mold in which the end point detection window 1 obtained as described above had been previously installed, and subjected to primary curing at 80°C for 30 minutes. The resulting block-shaped molded product was removed from the mold and subjected to secondary curing at 120°C for 4 hours in an oven, yielding a urethane resin block. The resulting urethane resin block was allowed to cool to 25°C.

Then, it was heated again in an oven at 120°C for 5 hours, and then sliced. The sliced surfaces were then ground (buffed) to obtain a foamed polyurethane sheet. Double-sided tape was attached to the back of the obtained polyurethane sheet, a cushion layer was attached, and further double-sided tape was attached to the surface of the cushion layer to obtain a polishing pad.

Example 2
A urethane prepolymer mixture was obtained by adding and mixing 2.9 parts of unexpanded hollow fine particles (average particle size: 8.5 μm) whose shell portion is made of an acrylonitrile-vinylidene chloride copolymer to 100 parts of a urethane prepolymer having an NCO equivalent of 420, which was obtained by reacting 2,4-tolylene diisocyanate (2,4-TDI), poly(oxytetramethylene) glycol (PTMG) having an average molecular weight of 650, poly(oxytetramethylene) glycol (PTMG) having a number average molecular weight of 1000, and diethylene glycol (DEG). The obtained urethane prepolymer mixture was charged into a first liquid tank and kept at 60° C. In addition to the first liquid tank, 28.0 parts of 3,3'-dichloro-4,4'-diaminodiphenylmethane (methylene bis-o-chloroaniline) (MOCA) was placed in a second liquid tank as a hardener, which was then heated to melt and mixed at 120°C, and further degassed under reduced pressure to obtain a hardener melt. A polishing pad was obtained in the same manner as in Example 1, except that the end point detection window 2 was used.

Example 3
A urethane prepolymer mixture was obtained by adding and mixing 2.8 parts of expanded hollow fine particles (average particle size: 20 μm) whose shell portion is made of an acrylonitrile-vinylidene chloride copolymer to 100 parts of a urethane prepolymer having an NCO equivalent of 460, which was obtained by reacting 2,4-tolylene diisocyanate (2,4-TDI), poly(oxytetramethylene) glycol (PTMG) having an average molecular weight of 650, and diethylene glycol (DEG). The obtained urethane prepolymer mixture was charged into a first liquid tank and kept at 60°C. In addition to the first liquid tank, 25.5 parts of 3,3'-dichloro-4,4'-diaminodiphenylmethane (methylene bis-o-chloroaniline) (MOCA) and 8.5 parts of polypropylene glycol were placed in a second liquid tank as a hardening agent, which was then heated to melt and mixed at 120°C, and further degassed under reduced pressure to obtain a hardening agent molten liquid. A polishing pad was obtained in the same manner as in Example 1, except that an end point detection window 3 was used.

Example 4
A polishing pad was obtained in the same manner as in Example 1, except that the end point detection window 2 was used.

Example 5
A polishing pad was obtained in the same manner as in Example 1, except that the end point detection window 3 was used.

Example 6
A polishing pad was obtained in the same manner as in Example 1, except that the end point detection window 4 was used.

Example 7
A polishing pad was obtained in the same manner as in Example 2, except that the end point detection window 4 was used.

Comparative Example 1
A polishing pad was obtained in the same manner as in Example 1, except that the end point detection window 5 was used.

Comparative Example 2
A polishing pad was obtained in the same manner as in Example 1, except that the end point detection window 6 was used.

[Dynamic viscoelasticity measurement]
Under the following conditions, a polyurethane sheet was kept in a thermohygrostat at a temperature of 23°C (±2°C) and a relative humidity of 50% (±5%) for 40 hours, and the resulting dry polyurethane sheet was used as a sample to perform dynamic viscoelasticity measurement under normal atmospheric conditions (dry state). The sample size of the end point detection window was 5 cm long x 0.5 cm wide x 0.125 cm thick, and the sample size of the polishing layer was 5 cm long x 0.5 cm wide x 0.13 cm thick.
(Measurement conditions)
Measuring device: RSA III (manufactured by TA Instruments)
Test length: 1 cm
Test mode: Tensile Frequency: 1.0 Hz
Temperature range: 10 to 100°C
Temperature increase rate: 3.0 ° C. / min
Distortion range: 0.10%
Initial load: 300g
Measurement interval: 1.5 points/℃

[D hardness]
The D hardness was measured according to JIS K6253. A D hardness tester manufactured by Tecrock Corporation was used for the measurement, and the sample was set so that the end point detection window (thickness: about 0.125 cm (1.25 mm)) described in the Comparative Examples and Examples was stacked four sheets, and the total thickness was at least 0.45 cm (4.5 mm).

[Surface quality verification test]
The polishing pad was placed at a predetermined position in the polishing device via a double-sided tape having an acrylic adhesive, and the Cu film substrate was polished under the following conditions.
(Polishing conditions)
Grinding machine: F-REX300X (manufactured by Ebara Corporation)
Disk: A188 (manufactured by 3M)
Rotation speed: (platen) 85 rpm, (top ring) 86 rpm
Polishing pressure: 3.5 psi
Polishing agent temperature: 20°C
Abrasive discharge amount: 200 ml/min
Abrasive: CSL-9044C (manufactured by Fujimi Corporation) (A mixture of CSL-9044C stock solution and pure water at a weight ratio of 1:9 was used)
Polishing object: Cu film substrate Polishing time: 60 seconds Pad break: 35N 10 minutes Conditioning: Ex-situ, 35N, 4 scans

After the above polishing process, the 10th to 50th polished pieces were evaluated using the high sensitivity measurement mode of a surface inspection device (KLA Tencor Corporation, Surfscan SP2XP) to detect and evaluate defects (surface defects) with a size of 155 nm or more. The surface quality was evaluated based on the results of defect (surface defect) confirmation.

The polishing pad of the present invention has industrial applicability as a pad suitable for polishing semiconductor wafers and the like.

10...polishing pad, 11...polishing layer, 11a...polishing surface, 12...end point detection window, 13...cushion layer, 14, 15...adhesive layer, 16...groove, 20...polishing device, 21...top ring, 22...table, 23...film thickness detection sensor, 24...slurry, W...wafer

Claims (5)

The polishing method includes the steps of: (a) polishing a polishing layer formed in a polyurethane sheet; and (b) detecting an end point of the polishing layer by an end point detection window provided in an opening of the polyurethane sheet.
The polyurethane sheet contains a polyurethane resin P and hollow fine particles dispersed in the polyurethane resin P,
the end point detection window contains polyurethane resin W,
the polyurethane resin W comprises a structural unit derived from an alicyclic isocyanate, a structural unit derived from a compound having three or more hydroxyl groups, and a structural unit derived from a polyether polyol,
In dynamic viscoelasticity measurement performed under conditions of a tensile mode, a frequency of 1.0 Hz, and a temperature range of 10 to 100° C., the ratio (E' _P30 /E' _W30 ) of the storage modulus E' _W30 at 30° C. of the end point detection window to the storage modulus E' _P30 of the polyurethane sheet at 30° C. is 0.60 to 1.50.
Polishing pad. In the dynamic viscoelasticity measurement, the ratio ( _E'P50 / _E'W50 ) of the storage modulus _E'W50 at 50°C of the end point detection window to the storage modulus _E'P50 of the polyurethane sheet at 50°C is 0.70 to 2.00.
2. The polishing pad of claim 1 . In the dynamic viscoelasticity measurement in the end point detection window, the storage modulus E' _W30 at 30°C is 10 x 10 ⁷ to 60 x 10 ⁷ Pa.
3. The polishing pad according to claim 1 or 2 . The D hardness (D _W20 ) at 20° C. of the end point detection window is 40 to 70;
The polishing pad according to any one of claims 1 to 3 . A polishing step of polishing an object to be polished using the polishing pad according to any one of claims 1 to 4 in the presence of a polishing slurry;
and an end point detection step of detecting an end point during the polishing by an optical end point detection method.
A method for manufacturing polished workpieces.

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