JP2022155532A - Abrasive pad and polished product manufacturing method - Google Patents

Abstract

To provide an abrasive pad with excellent surface smoothness, and a polished product manufacturing method with use of the same.SOLUTION: An abrasive pad has a polyurethane sheet as a polishing layer, and an end point detection window provided at an opening of the polyurethane sheet. In dynamic viscoelasticity measurement performed under the conditions of a tension mode, a frequency of 1.0 Hz, 10 to 100°C, a storage elastic modulus E'W90 at 90°C is 1.0×107 Pa or more, a D hardness (DW80) of the end point detection window at 80°C is 40 or more, and a D hardness (DW20) of the end point detection window at 20°C is 40 to 90.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a polishing pad and a method for manufacturing a polishing workpiece using the same.

In semiconductor manufacturing processes, chemical mechanical polishing (CMP) is used in the process of flattening after insulating film deposition and in the process of forming metal wiring. One of the important techniques required for chemical mechanical polishing is polishing endpoint detection for detecting whether the polishing process has been completed. For example, over-polishing or under-polishing to the target polishing end point directly leads to product defects. Therefore, in chemical mechanical polishing, it is necessary to strictly control the polishing amount by detecting the polishing end point.

Chemical mechanical polishing is a complicated process, and the polishing speed (polishing rate) varies 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. Change. Furthermore, in recent years, the precision and in-plane uniformity of the residual film thickness required in the semiconductor manufacturing process have become more and more severe. Under these circumstances, it is becoming more difficult to detect the polishing end point with sufficient accuracy.

Known major polishing end point detection methods include the optical end point detection method, the torque end point detection method, and the eddy current end point detection method. The end point is detected by irradiating the wafer with light through the member and monitoring the reflected light.

As a polishing pad using such an optical end point detection system, for example, Patent Document 1 discloses a polishing pad that can suppress slurry from accumulating in grooves of a window member and increase the accuracy of polishing rate detection. A polishing pad having a pad body and a transparent window member formed integrally with a part of the pad body, wherein the surface of the window member is recessed from the surface of the pad body. It is disclosed to

JP-A-2002-001647

By the way, as one method for producing a polishing pad having a window as described above, a resin composition is filled and cured in a state where a window member is fixed in a mold, and then the obtained cured product is sliced. and then perform a dressing process. Here, since the window member and the cured product of the resin composition are made of different materials, their physical properties are not a little different. . Also, when performing the dressing process, the window may be recessed due to the difference in the amount of wear between the window and the polishing layer.

When such dents are formed, slurry and polishing dust tend to accumulate there, which may cause scratches and the like, degrading the surface quality of the object to be polished. Further, when the amount of wear of the window portion is smaller than that of the polishing layer, the window portion is more likely to remain than the polishing layer as the polishing progresses, and as a result, the window portion may become convex. Such convex windows may also cause scratches and the like, degrading the surface quality of the object to be polished.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a polishing pad with excellent flatness during slicing and dressing, and a method for manufacturing a polished product using the same.

The present inventors have made extensive studies to solve the above problems. As a result, the inventors have found that the above problems can be solved by providing the endpoint detection window with predetermined viscoelasticity and hardness, and have completed the present invention.

That is, the present invention is as follows.
[1]
having a polyurethane sheet serving as a polishing layer and an endpoint detection window provided in an opening of the polyurethane sheet,
In the dynamic viscoelasticity measurement of the endpoint detection window performed under the conditions of tensile mode, frequency of 1.0 Hz, and 10 to 100 ° C., the storage elastic modulus E′ _W90 at 90 ° C. is 1.0 × ¹⁰ Pa or more,
The D hardness (D _W80 ) of the endpoint detection window at 80° C. is 40 or more,
The endpoint detection window has a D hardness (D _W20 ) at 20° C. of 40 to 90.
polishing pad.
[2]
wherein the endpoint detection window contains a polyurethane resin W,
The polishing pad according to [1].
[3]
The polyurethane resin W contains structural units derived from an alicyclic isocyanate and/or an aliphatic isocyanate,
The polishing pad according to [2].
[4]
The polyurethane resin W contains structural units derived from a compound having 3 or more hydroxyl groups,
The polishing pad according to [2] or [3].
[5]
In the dynamic viscoelasticity measurement of the endpoint detection window, the storage elastic modulus E′ _W30 at 30° C. is 60×107 to 100× ¹⁰⁷ Pa.
[1] The polishing pad according to any one of [4].
[6]
In the dynamic viscoelasticity measurement of the endpoint detection window, the peak temperature of tan δ is 70 to 100 ° C.
[1] The polishing pad according to any one of [5].
[7]
The polyurethane sheet contains a polyurethane resin P and hollow fine particles dispersed in the polyurethane resin P.
[1] The polishing pad according to any one of [6].
[8]
a polishing step of polishing an object to be polished using the polishing pad according to any one of [1] to [7] in the presence of a polishing slurry to obtain a polished object;
an endpoint detection step of performing endpoint detection by an optical endpoint detection method during the polishing;
A method for producing an abrasive article.

ADVANTAGE OF THE INVENTION According to this invention, the polishing pad which is excellent in the flatness at the time of a slicing process and a dressing process, and the manufacturing method of the polished workpiece using the same can be provided.

1 is a schematic perspective view of a polishing pad of this embodiment; FIG. FIG. 3 is a schematic cross-sectional view of the end point detection window portion of the polishing pad of the present embodiment; 4 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. 1 is a schematic diagram showing a film thickness control system installed in CMP; FIG. FIG. 4 is a diagram showing the surface state of the end point detection window portion of the polishing pad of Example 1 after slicing and before dressing; FIG. 10 is a diagram showing the surface state of the end point detection window portion of the polishing pad of Comparative Example 1 after slicing and before dressing; FIG. 10 is a diagram showing the surface state of the end point detection window portion of the polishing pad of Comparative Example 2 after slicing and before dressing; FIG. 10 is a diagram showing the surface state of the end point detection window portion of the polishing pad of Example 2 after slicing and before dressing; FIG. 4 is a diagram showing the surface state of the end point detection window portion of the polishing pad of Example 1 after dressing. FIG. 10 is a diagram showing the surface state of the end point detection window portion of the polishing pad of Comparative Example 1 after dressing; FIG. 10 is a diagram showing the surface state of the end point detection window portion of the polishing pad of Comparative Example 2 after dressing. FIG. 10 is a diagram showing the surface state of the end point detection window portion of the polishing pad of Example 2 after dressing.

Hereinafter, embodiments of the present invention (hereinafter referred to as "present embodiments") will be described in detail with reference to the drawings as necessary, but the present invention is not limited thereto and the gist thereof. Various modifications are possible without departing from the above. In the drawings, the same elements are denoted by the same reference numerals, and overlapping descriptions are omitted. Moreover, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios of the drawings are not limited to the illustrated ratios.

1. Polishing Pad The polishing pad of the present embodiment has a polyurethane sheet serving as a polishing layer and an end point detection window provided in the opening of the polyurethane sheet, and is subjected to tensile mode, frequency of 1.0 Hz, and conditions of 10 to 100°C. In the dynamic viscoelasticity measurement of the endpoint detection window performed at , the storage elastic modulus _E'W90 at 90°C is 1.0 × ¹⁰ Pa or more, and the D hardness ( _DW80 ) at 80°C of the endpoint detection window is It is 40 or more, and the D hardness (D _W20 ) at 20° C. of the endpoint detection window is 40-70.

As a result, the flatness can be improved from the viewpoint that convex portions are less likely to occur in the slicing process, and the flatness can be improved from the viewpoint that the end point detection window is less likely to be over-polished than the polishing layer during the dressing process. can be done. In this embodiment, these two types of flatness are collectively referred to simply as "flatness".

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

2 and 3 show sectional views around the endpoint detection window 12 in FIG. As shown in FIGS. 2 and 3, an adhesive layer 14 may be provided between the polishing layer 11 and the cushion layer 13, and the surface of the cushion layer 13 is attached to the table 22 shown in FIG. An adhesive layer 15 may be provided for the purpose. The polishing surface 11a of the polishing pad of the present embodiment may be flat as shown in FIG. 2, or may be uneven with grooves 16 formed therein as shown in FIG. The grooves 16 may be formed with a plurality of grooves having various shapes such as concentric circles, grids, and radial grooves singly or in combination.

1.1. Endpoint Detection Window The endpoint detection window is a transparent member provided in the opening of the polyurethane sheet, and serves as a transmission path for light from the film thickness detection sensor in optical endpoint detection. In this embodiment, the end-point detection window is circular, but it may be square, rectangular, polygonal, elliptical, or the like, if desired.

In the present embodiment, in the process of manufacturing the polishing pad, when slicing, the endpoint detection window becomes recessed from the polishing layer or cracks. The storage elastic modulus E′ and D hardness of the end-point detection window are defined from the viewpoint of suppressing the detection window from becoming recessed or protruding from the polishing layer and improving flatness.

1.1.1. Dynamic Viscoelasticity The storage elastic modulus E′ of the endpoint detection window in this embodiment can be obtained by dynamic viscoelasticity measurement performed under the conditions of tensile mode, frequency of 1.0 Hz, and 10 to 100°C. As will be described later, slicing is performed while the object is heated, so the storage elastic modulus E′ _W90 at 90° C. is defined as the storage elastic modulus E′ of the endpoint detection window in this embodiment. In addition, in the present embodiment, the peak temperature of the loss tangent tan δ is set at The position may be further adjusted, and the storage elastic modulus E′ _W30 at 30° C. may be specified from the viewpoint of representing the characteristics of the endpoint detection window during dressing.

The storage elastic modulus E′ _W90 of the endpoint detection window at 90° C. is 1.0×10 ⁷ Pa or more, preferably 1.25×10 ⁷ to 20×10 ⁷ Pa, more preferably 1.5×10 7 Pa or more. It is 10 ⁷ to 10×10 ⁷ Pa. The storage elastic modulus E′ _W90 of 1.0×10 ⁷ Pa or more prevents the end-point detection window from becoming recessed or protruding from the polishing layer, or from cracking when slicing. can be suppressed, and flatness can be further improved.

In addition, the peak temperature of tan δ is preferably 70 to 100° C., more preferably 70 to 95, and even more preferably 75 to 90 in the dynamic viscoelasticity measurement in the endpoint detection window. When the peak temperature of tan δ is within the above range, when slicing, it is possible to suppress the end-point detection window from becoming recessed or protruding from the polishing layer, or from being cracked, thereby improving flatness. can be improved.

Furthermore, the storage elastic modulus E′ _W30 at 30° C. is preferably 10×10 ⁷ to 80×10 ⁷ Pa, more preferably 20×10 ⁷ to 70×10 ⁷ Pa, still more preferably 30×10 ⁷ to 70×10 ⁷ Pa. When the storage elastic modulus _E′W30 is within the above range, it is possible to suppress the end-point detection window from being recessed from the polishing layer when performing the dressing process, and to improve the flatness. can be improved.

The measurement conditions for the dynamic viscoelasticity measurement are not particularly limited, but the measurement can be performed under the conditions described in Examples.

1.1.2. D Hardness The D hardness (D _W80 ) of the endpoint detection window at 80° C. is 40 or more, preferably 40-60, more preferably 40-50. When the D hardness (D _W80 ) is 40 or more, when slicing, it is possible to suppress the end point detection window from being recessed or protruding from the polishing layer, or from being cracked, thereby improving flatness. can be improved.

The D hardness (D _W20 ) of the endpoint detection window at 20° C. is 40-90, preferably 50-85, more preferably 55-80. When the D hardness (D _W20 ) is within the above range, it is possible to suppress the end-point detection window from becoming recessed or protruding from the polishing layer when the dressing process is performed. Flatness can be further improved.

The measurement conditions for the D hardness are not particularly limited, but can be measured according to the conditions described in Examples.

1.1.3. Constituent material The material constituting the endpoint detection window is not particularly limited as long as it is a transparent member that can function as a window. Examples include polyurethane resin W, polyvinyl chloride resin, polyvinylidene fluoride resin, polyether sulfone resin, and polystyrene. resin, polyethylene resin, polytetrafluoroethylene resin, and the like. Among these, polyurethane resin W is preferable. By using such a resin, the dynamic viscoelastic properties, D hardness, and transparency can be more easily adjusted, and the flatness can be further improved.

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. Structural Units Derived from Polyisocyanates Structural units derived from polyisocyanates are not particularly limited, but for example, structural units derived from alicyclic isocyanates, structural units derived from aliphatic isocyanates, and structures derived from aromatic isocyanates units. Among these, the polyurethane resin W preferably contains structural units derived from an alicyclic isocyanate and/or an aliphatic isocyanate. This makes it easier to adjust the dynamic viscoelastic properties, D hardness (D _W20 ), and D hardness (D _W80 ) within the above ranges, further improving the transparency and further improving the yellowing resistance of the window. It is in. Moreover, the flatness can be further improved.

The alicyclic isocyanate is 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.

Examples of aliphatic isocyanates include, but are not limited to, hexamethylene diisocyanate (HDI), pentamethylene diisocyanate (PDI), tetramethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, and trimethylene diisocyanate. , trimethylhexamethylene diisocyanate, and the like.

Examples of 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.

Examples of low-molecular-weight polyols include, but are not limited to, 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, tricyclode low-molecular-weight polyols having two hydroxyl groups such as candimethanol and 1,4-cyclohexanedimethanol; and low-molecular-weight polyols having three or more hydroxyl groups such as glycerin, hexanetriol, trimethylolpropane, isocyanuric acid and erythritol. Low-molecular-weight polyols may be used singly or in combination of two or more.

Among these, low-molecular-weight polyols having 3 or more hydroxyl groups are preferred, and glycerin is more preferred. By using such a low-molecular-weight polyol, the dynamic viscoelastic properties and D hardness can be easily adjusted within the above range, the wear amount can be adjusted, the flatness can be further improved, and the transparency can be further improved. In addition, the yellowing resistance of windows tends to be further improved.

The content of the structural unit derived from the low-molecular-weight polyol having 3 or more hydroxyl groups is preferably 8.0 to 30 parts, more preferably 10 to 25 parts, per 100 parts of the structural unit derived from the polyisocyanate. and more preferably 12.5 to 20 parts. When the content of the structural unit derived from the low-molecular-weight polyol having three or more hydroxyl groups is within the above range, the dynamic viscoelastic properties and D hardness can be easily adjusted within the above range, and the flatness can be further improved. , the transparency tends to be further improved, and the yellowing resistance of the window tends to be further improved.

In addition, the polymer polyol is not particularly limited, but for example, polyether polyol, polyester polyol, polycarbonate polyol, polyether polycarbonate polyol, polyurethane polyol, epoxy polyol, vegetable oil polyol, polyolefin polyol, acrylic polyol, and vinyl monomer-modified A polyol is mentioned. Polymer polyols may be used singly or in combination of two or more.

The number average molecular weight of the polymer polyol is preferably 300-1200, more preferably 400-950, still more preferably 500-800. By using such a polymer polyol, it tends to be easy to adjust the dynamic viscoelastic properties and the D hardness within the above ranges.

Among these, polyether polyol is preferred, and polytetramethylene ether glycol is more preferred. By using such a polymer polyol, the dynamic viscoelastic properties and D hardness can be easily adjusted within the above ranges, the hardness at low temperatures can be easily adjusted, and the decrease in hardness due to temperature rise can be suppressed. . Further, the flatness can be further improved, the transparency is further improved, and the yellowing resistance of the window tends to be further improved.

The content of structural units derived from polyether polyol is preferably 40 to 100 parts, preferably 50 to 90 parts, more preferably 60 to 84 parts, per 100 parts of structural units derived from polyisocyanate. Department. When the content of the structural unit derived from the polyether polyol is within the above range, the dynamic viscoelastic properties and D hardness can be easily adjusted within the above range, the flatness can be further improved, and the transparency can be improved. In addition to further improvement, there is a tendency for the yellowing resistance of the window to be further improved.

Moreover, as a polyol, it is preferable to use a low-molecular-weight polyol and a high-molecular-weight polyol together, and it is more preferable to use a low-molecular-weight polyol having three or more hydroxyl groups and a polyether polyol together. As a result, the dynamic viscoelastic properties and D hardness can be easily adjusted within the above ranges, the hardness at low temperatures can be easily adjusted, and a decrease in hardness due to temperature rise can be suppressed. Further, the flatness can be further improved, the transparency is further improved, and the yellowing resistance of the window tends to be further improved.

From the above viewpoint, the content of the polyether polyol is preferably 1.0 to 9.0 parts, more preferably 2.0 to 8.0 parts, per 1 part of the low-molecular-weight polyol having 3 or more hydroxyl groups. parts, more preferably 3.0 to 7.0 parts.

1.2. Polishing Layer A polyurethane sheet is used as the polishing layer of the present embodiment. This polyurethane sheet has an opening in which the endpoint detection window is embedded. Although the position of the opening is not particularly limited, it is preferably provided at a position in the radial direction corresponding to the film thickness detection sensor 23 installed on the table 22 . Although the number of openings is not particularly limited, the openings are arranged at similar radial positions so that the windows pass over the film thickness detection sensor 23 multiple times when the polishing pad 10 attached to the table 22 rotates once. It is preferable to have a plurality of them.

Examples of the form of the polyurethane sheet include, but are not particularly limited to, a foamed polyurethane sheet, a resin non-foamed polyurethane sheet, and a sheet in which a fiber base material is impregnated with polyurethane.

Here, the term "resin foam molding" refers to a foam that does not have a fiber base material and is made of a predetermined resin. The foam shape is not particularly limited, but examples thereof include spherical cells, substantially spherical cells, tear-shaped cells, and open cells in which each cell is partially connected.

A non-foamed molded article of resin refers to a non-foamed article that does not have a fiber base material and is composed of a predetermined resin. A non-foamed body refers to a body that does not have air bubbles as described above. In the first embodiment, non-foamed molded articles of resin include those obtained by applying a curable composition to a base material such as a film and then curing the same. More specifically, the resin cured product formed by a labia 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, etc. Included in non-foamed molded articles.

Furthermore, the resin-impregnated base material refers to a material obtained by impregnating a fiber base material with a resin. Here, the fiber base material is not particularly limited, and examples thereof include woven fabrics, nonwoven fabrics, and knitted fabrics.

1.2.1. Dynamic viscoelasticity In addition to the polishing rate and the surface quality of the object to be polished, the polyurethane sheet is subject to cracks and the end point detection window in the polishing pad obtained by slicing or dressing. From the viewpoint of suppressing this, it is preferable to have predetermined dynamic viscoelastic properties.

Specifically, in the dynamic viscoelasticity measurement performed under the conditions of tension mode, frequency of 1.0 Hz, and temperature of 10 to 100°C, the storage elastic modulus E' _P90 of the polyurethane sheet at 90°C is preferably 1.0 × 10 ⁷ . Pa or more, preferably 2.0×10 ⁷ Pa to 20×10 ⁷ Pa, more preferably 3.0×10 ⁷ Pa to 15×10 ⁷ Pa. When the storage elastic modulus E′ _P90 is 1.0×10 ⁷ Pa or more, in addition to improving the polishing rate and the surface quality of the object to be polished, the polishing pad obtained by slicing or dressing has an endpoint detection window. It tends to be more inhibited from becoming recessed or protruding from the polishing layer, or from being cracked, thereby further improving the flatness.

From the same point of view, the difference (E' _P90 -E' _W90 ) between the storage elastic modulus E' _W90 and the storage elastic modulus E' _P90 is 9.5×10 ⁷ Pa or less, preferably 1.0. ×10 ⁷ Pa to 9.0×10 ⁷ Pa, more preferably 2.0×10 ⁷ Pa to 9.0×10 ⁷ Pa. When the difference (E' _P90 -E' _W90 ) is 9.5×10 ⁷ Pa or less, the difference in physical properties between the polishing layer and the endpoint detection window is reduced under the slicing conditions, so that the polishing layer and the endpoint detection window are uniform. , and the shape of the window tends to be flat. Therefore, in the polishing pad obtained by slicing or dressing, the end-point detection window is further suppressed from becoming recessed or protruding from the polishing layer, or from being cracked, thereby further improving flatness. tend to be able.

1.2.2. Polyurethane Sheet The polyurethane resin P that constitutes the polyurethane sheet is not particularly limited, but examples thereof include polyester-based polyurethane resins, polyether-based polyurethane resins, and polycarbonate-based polyurethane resins. You may use these individually by 1 type or in combination of 2 or more types.

Such a polyurethane resin P can be synthesized from a polyisocyanate and a polyol, and a reaction product of a urethane prepolymer and a curing agent is particularly preferred. Here, the urethane prepolymer can be synthesized from polyisocyanate and polyol. The polyisocyanate, polyol, and curing agent that constitute the polyurethane resin P are described below.

1.2.2.1. Structural Units Derived from Polyisocyanates Structural units derived from polyisocyanates are not particularly limited, but for example, structural units derived from alicyclic isocyanates, structural units derived from aliphatic isocyanates, and structures derived from aromatic isocyanates units. Among these, aromatic isocyanates are preferred, and 2,4-tolylene diisocyanate (2,4-TDI) is more preferred.

Examples of the alicyclic isocyanate, aliphatic isocyanate, and aromatic isocyanate are the same as those exemplified in the endpoint detection window.

1.2.2.2. Structural Units Derived from Polyols Structural units derived from polyols are not particularly limited. Among these, it is preferable to use at least a low-molecular-weight polyol, and it is preferable to use a combination of a low-molecular-weight polyol and a high-molecular-weight polyol.

Examples of low-molecular-weight polyols and high-molecular-weight polyols are the same as those exemplified in the endpoint detection window. Among these, as the low-molecular-weight polyol, a low-molecular-weight polyol having two hydroxyl groups is preferable, and diethylene glycol is more preferable. Moreover, as a polymer polyol, polyether polyol is preferable, and polytetramethylene ether glycol is more preferable.

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

Examples of polyamines include, but are not limited to, aliphatic polyamines such as ethylenediamine, propylenediamine and hexamethylenediamine; alicyclic polyamines such as isophoronediamine and dicyclohexylmethane-4,4'-diamine; Dichloro-4,4'-diaminodiphenylmethane (MOCA), 4-methyl-2,6-bis(methylthio)-1,3-benzenediamine, 2-methyl-4,6-bis(methylthio)-1,3- aromatic polyamines such as benzenediamine and 2,2-bis(3-amino-4-hydroxyphenyl)propane;

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

As the polyol, the same polyols as exemplified in the endpoint detection window can be exemplified. Among these, polymer polyols are preferred, polyether polyols are more preferred, and polypropylene glycol is even more preferred.

1.2.2.4. Hollow Fine Particles 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 hollow fine particles, and tends to easily adjust the dynamic viscoelasticity and D hardness within the above ranges.

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

The shape of the hollow fine particles is not particularly limited, and may be spherical or substantially spherical, for example. Further, when the hollow fine particles are expandable balloons, they may be used in an unexpanded state or in an expanded state.

The average particle diameter of the hollow fine particles contained in the polyurethane sheet is preferably 5-200 μm, more preferably 5-80 μm, even more preferably 5-50 μm, and particularly preferably 5-35 μm. When the average particle size is within the above range, it tends to be easy to adjust the dynamic viscoelastic properties and D hardness within the above range. The average particle diameter can be measured by a laser diffraction particle size distribution analyzer (eg, Mastersizer-2000 manufactured by Spectris Co., Ltd.) or the like.

1.3. Others The polishing pad of the present embodiment may have a cushion layer on the side opposite to the polishing surface of the polishing layer. The surface to be attached to the machine) may have an adhesive layer. In this case, the cushion layer and the adhesive layer have openings at locations similar to where the endpoint detection windows of the polishing layer are located.

2. Method for producing polishing pad The method for producing the polishing pad of the present embodiment is not particularly limited. obtaining a resin block in which the window member is embedded by curing; and slicing the obtained resin block to obtain a polyurethane sheet having an endpoint detection window in the opening. Then, the polishing surface of the obtained polyurethane sheet may be dressed.

The temperature for slicing is preferably 70.degree. C. to 100.degree. Also, the temperature in the dressing treatment is preferably 20°C to 30°C. This tends to further improve flatness.

3. Method for producing a polished object The method for producing a polished object according to the present embodiment includes a polishing step of polishing an object to be polished using the above-described polishing pad in the presence of a polishing slurry to obtain a polished object; and an endpoint detection step of performing endpoint detection by an optical endpoint detection method.

3.1. Polishing process The polishing process may be primary lapping polishing (rough lapping), secondary lapping (finish lapping), primary polishing (rough polishing), or secondary polishing (finish polishing). ), or may also serve as polishing. Here, "lapping" refers to polishing at a relatively high rate using coarse abrasive grains, and "polishing" refers to increasing the surface quality at a relatively low rate using fine abrasive grains. Say to polish for.

Among these, the polishing pad of the present embodiment is preferably used for chemical mechanical polishing (CMP). The method for producing a polished object of this embodiment will be described below using chemical mechanical polishing as an example, but the method for producing a polished object of this embodiment is not limited to the following.

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

A conventionally known method can be used as the polishing method, and is not particularly limited. For example, first, an object to be polished held on a holding surface plate arranged to face the polishing pad is pressed against the polishing surface, and the polishing pad and/or the holding surface plate are rotated while slurry is supplied from the outside. Let The polishing pad and the holding platen may rotate in the same direction or in opposite directions at different rotational speeds. Further, the object to be polished may be polished while moving (rotating) inside the frame during the polishing process.

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

3.2. End Point Detection Step The method for manufacturing a polished workpiece according to the present embodiment has an end point detection step of detecting the end point by an optical end point detection method in the polishing step. Specifically, a conventionally known method can be used as the end point detection method by the optical end point detection method.

FIG. 4 shows a schematic diagram of the endpoint detection method of the optical endpoint detection system. This schematic diagram shows a chemical mechanical polishing process in which a wafer W held by a top ring 21 is pressed onto a polishing pad 10 attached on a table 22 while flowing a slurry 24 thereon, and the uneven film on the surface of the wafer W is scraped and flattened. . The polishing apparatus 20 mounts a film thickness detection sensor 23 for monitoring the film thickness on the table 22 in order to detect the end point of the predetermined film thickness at the same time as flattening and terminate the process with high accuracy. 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 causes light to enter the surface of the wafer W through the end point detection window 12, and the light reflected by the film on the wafer W (wafer surface) and the film on the wafer W are detected. A film thickness change can be detected by detecting the strength of the reflection intensity caused by the phase difference with respect to the light reflected at the interface between the wafer and the substrate.

Hereinafter, the present invention will be described more specifically using examples and comparative examples. The present invention is by no means limited by the following examples. In addition, "part" shall mean a mass part.

[Production Example 1: Endpoint Detection Window 1]
100 parts of 4,4′methylenebis(cyclohexyl isocyanate), 78.6 parts of poly(oxytetramethylene)glycol (PTMG) having a number average molecular weight of 650, and 14.8 parts of glycerin are reacted to detect the end point. A transparent member to be the window 1 was obtained.

[Manufacturing Example 2: End Point Detection Window 2]
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, 7.5 parts of glycerin, and 7.5 parts of ethylene glycol , to obtain a transparent member that will serve as the endpoint detection window 2 .

[Production Example 3: End Point Detection Window 3]
100 parts of 4,4′methylenebis(cyclohexyl isocyanate), 78.6 parts of poly(oxytetramethylene)glycol (PTMG) having a number average molecular weight of 650, 4.5 parts of glycerin, and 10.5 parts of ethylene glycol , to obtain a transparent member that will serve as the endpoint detection window 3 .

[Manufacturing Example 4: End Point Detection Window 4]
100 parts of 4,4'methylenebis(cyclohexyl isocyanate), 103.6 parts of poly(oxytetramethylene)glycol (PTMG) having a number average molecular weight of 1000, and 15.9 parts of glycerin are reacted to detect the end point. A transparent member to be the window 4 was obtained.

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

Next, the liquids in the first liquid tank and the liquid in the second liquid tank were injected from respective inlets of a mixer provided with two inlets, and stirred and mixed to obtain a mixed liquid.

Then, the obtained mixed liquid was cast into a mold in which the endpoint detection window 1 obtained as described above was installed in advance, and was primarily cured at 80° C. for 30 minutes. The formed block-shaped molding was extracted from the mold and subjected to secondary curing in an oven at 120° C. for 4 hours to obtain a urethane resin block. The resulting urethane resin block was allowed to cool to 25°C.

Then, after heating again at 120° C. for 5 hours in an oven, slicing was performed, and the sliced surface was subjected to grinding (buffing) as necessary to obtain a foamed polyurethane sheet. A double-faced tape was attached to the rear surface of the obtained polyurethane sheet, a cushion layer was attached thereto, and a double-sided tape was attached to the surface of the cushion layer to obtain a polishing pad.

When evaluating the cross section around the end point detection window after the dressing process, the polishing pad obtained as described above was subjected to the dressing process under the following conditions.
(dress condition)
Polishing machine used: Speedfam, trade name “FAM-12BS”
Surface plate rotation speed (polishing pad rotation speed): 50 rpm
Flow rate: 100 ml/min (Pure water at 20° C. was dropped from the rotation center of the polishing pad.)
Dresser: 3M diamond dresser, model number "A188"
Dresser rotation speed: 100 rpm
Dressing pressure: 0.115 kg/cm2
Direction of dresser rotation: Rotates in the same direction as the polishing pad Test time: 60 minutes

[Comparative Example 1]
A polishing pad was obtained in the same manner as in Example 1, except that the endpoint detection window 2 of Production Example 2 was used.

[Comparative Example 2]
A polishing pad was obtained in the same manner as in Example 1, except that the endpoint detection window 3 of Production Example 3 was used.

[Example 2]
A polishing pad was obtained in the same manner as in Example 1, except that the endpoint detection window 4 of Production Example 4 was used.

[Dynamic viscoelasticity measurement]
Based on the following conditions, a dry polyurethane sheet was held for 40 hours in a constant temperature and humidity chamber at a temperature of 23 ° C (± 2 ° C) and a relative humidity of 50% (± 5%). A dynamic viscoelasticity measurement was performed in an atmosphere (dry state). The sample size of the endpoint detection window was 5 cm long×0.5 cm wide×0.125 cm thick, and the sample size of the polishing layer was 5 cm long×0.5 cm wide×0.13 cm thick.
(Measurement condition)
Measuring device: RSA III (manufactured by TA Instruments)
Test length: 1cm
Test mode: Tensile Frequency: 1.0Hz
Temperature range: 10-100°C
Heating rate: 3.0°C/min
Strain range: 0.10%
Initial load: 300g
Measurement interval: 1.5 points/°C

[D hardness]
The D hardness was measured according to JIS K6253. At the time of measurement, a D hardness tester manufactured by Teclock Co., Ltd. was used, and the sample was a stack of four endpoint detection windows (thickness of about 0.125 cm (1.25 mm)) described in Comparative Examples and Examples, and the total thickness was at least 0 .45 cm (4.5 mm) or more. In addition, the sample used was one which was allowed to stand for 30 minutes in a constant temperature and humidity chamber at 20°C or 80°C.

[Cross-section evaluation]
For each pad obtained as described above, the periphery of the end point detection window after slicing and before dressing (the portion surrounded by the dashed line S in FIG. 2) (evaluation 1), and the end point detection after dressing A cross section (evaluation 2) around the window (the portion surrounded by the dashed line S in FIG. 2) is measured with a laser microscope (VK-X1000, manufactured by KEYENCE) at a size of about 14 mm x 1 mm with respect to the surface of the diameter portion of the endpoint detection window. The range was magnified 200 times and observed in the coupled mode, and profile measurement of height information was performed based on the obtained laser image.

The results are shown in FIGS. 5A-D and 6A-D. 5A to 5D and 6A to 6D show the cross-sectional measurement results of two endpoint detection windows, and the cross-sectional measurement results of each endpoint detection window in the slicing direction and the direction perpendicular to the slicing direction. is shown.

In evaluation 1, if the end point detection window was within ±50 μm from the polished surface, it was evaluated as ◯, and otherwise it was evaluated as x. In addition, in evaluation 2, if the cross-sectional image is flat (the height is the same from the edge to the center), it is rated as ◯, and if it is convex (the height increases from the edge to the center), it is rated as x. .

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

DESCRIPTION OF SYMBOLS 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 (8)

having a polyurethane sheet serving as a polishing layer and an endpoint detection window provided in an opening of the polyurethane sheet,
In the dynamic viscoelasticity measurement of the endpoint detection window performed under the conditions of tensile mode, frequency of 1.0 Hz, and 10 to 100 ° C., the storage elastic modulus E′ _W90 at 90 ° C. is 1.0 × ¹⁰ Pa or more,
The D hardness (D _W80 ) of the endpoint detection window at 80° C. is 40 or more,
The endpoint detection window has a D hardness (D _W20 ) at 20° C. of 40 to 90.
polishing pad. wherein the endpoint detection window contains a polyurethane resin W,
The polishing pad according to claim 1. The polyurethane resin W contains structural units derived from an alicyclic isocyanate and/or an aliphatic isocyanate,
The polishing pad according to claim 2. The polyurethane resin W contains structural units derived from a compound having 3 or more hydroxyl groups,
The polishing pad according to claim 2 or 3. In the dynamic viscoelasticity measurement of the endpoint detection window, the storage elastic modulus E′ _W30 at 30° C. is 60×10 ⁷ to 100×10 ⁷ Pa.
The polishing pad according to any one of claims 1-4. In the dynamic viscoelasticity measurement of the endpoint detection window, the peak temperature of tan δ is 70 to 100 ° C.
The polishing pad according to any one of claims 1-5. 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 claims 1-6. a polishing step of polishing an object to be polished using the polishing pad according to any one of claims 1 to 7 in the presence of a polishing slurry to obtain a polished object;
an endpoint detection step of performing endpoint detection by an optical endpoint detection method during the polishing;
A method for producing an abrasive article.

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