JP2021049608A - Polishing pad, method for manufacturing the same and method for manufacturing polished product - Google Patents

Abstract

To provide a polishing pad that can suppress generation of roll-off and scratches, and to provide a method for manufacturing the polishing pad and a method for manufacturing a polished product using the polishing pad.SOLUTION: A polishing pad includes a polishing layer including air bubbles inside thereof, where a resin constituting the polishing layer has a 100% modulus of 5-20 MPa at 23±2°C and the resin has a wall ratio W100 of 20-40% at a depth of 100 μm from a polishing surface of the polishing layer.SELECTED DRAWING: None

Description

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

Conventionally, polishing using a polishing pad has been performed in order to flatten an object to be polished such as a semiconductor wafer, glass, or a magnetic disk. Polishing is divided into primary polishing (rough polishing), which tends to emphasize the polishing rate, and secondary polishing (final finishing), which tends to emphasize surface quality such as less scratches. Can be categorized.

From the viewpoint of improving surface quality, a polishing pad provided with a soft polishing layer is used in order to disperse local stresses during polishing and reduce scratches. As such a soft polishing layer, for example, a soft plastic sheet in which foam is formed by a wet film forming method is known.

Generally, a soft plastic sheet is manufactured by applying a resin solution prepared by dissolving soft plastic in a water-miscible organic solvent to a sheet-like base material and then coagulating and regenerating the resin in an aqueous coagulating liquid (wet film formation). Will be done. Therefore, the wet-formed soft plastic sheet (polishing layer 1) has a foamed structure 2 that accompanies solidification and regeneration of the resin, and the polishing process can be performed while storing the polishing liquid (see FIG. 1). ).

Such a soft plastic sheet usually has a cushion layer 4 on the side opposite to the polishing surface 3, but the soft plastic sheet (polishing layer 1) itself is flexible and easily deformed, and the object to be polished W is pressed against it. At this time, of the surface layer of the polishing layer 1, the vicinity 1'in contact with the peripheral edge of the object to be polished is particularly stretched. The stress received by the object to be polished from this stretched portion is higher than the stress received by the object to be polished from the unstretched portion. Therefore, an excessive stress F is applied to the peripheral portion W1 of the object to be polished W, roll-off W2 is likely to occur, and the flatness of the object to be polished W is lowered (see FIGS. 1 and 2). The roll-off may be edge sagging or edge sagging.

Patent Document 1 discloses a technique for adjusting the compressive deformation amount value of a pad from a pad modulus value to 70 to 100, with an object of achieving both such low surface roughness and a high-quality end shape. , A polishing pad having basically a high pad modulus value and a low compression deformation amount value is disclosed.

Japanese Unexamined Patent Publication No. 2010-086597

However, when such a hard polishing pad is used, it is difficult to achieve high-quality surface quality with few minute scratches, which is required in recent years.

The present invention has been made in view of the above problems, and describes a polishing pad capable of suppressing roll-off and scratch generation, a method for manufacturing the polishing pad, and a method for manufacturing a polished product using the polishing pad. The purpose is to provide.

The present inventors have diligently studied to solve the above problems. As a result, while maintaining the polishing layer as soft, the wall thickness between the bubbles near the surface layer of the polishing layer is kept within a certain range, so that the stress received from the object to be polished is suppressed and the roll-off during polishing is suppressed. We have found that the occurrence can be suppressed, and have completed the present invention.

That is, the present invention is as follows.
[1]
It has a polishing layer with air bubbles inside,
The 100% modulus of the resin constituting the polishing layer at 23 ± 2 ° C. is 5 to 20 MPa, and the wall ratio W ₁₀₀ of the resin at a depth of 100 μm from the polished surface of the polishing layer is 20 to 40%.
Polishing pad.
[2]
The reduction rate ((W _50- W ₁₀₀ ) / W _{50 ) of the resin wall ratio W 100 at} a depth of 100 μm from the polished surface is 30 to 60 with _{respect to the resin wall ratio W 50 at} a depth of 50 μm from the polished surface. %,
The polishing pad according to [1].
[3]
A cushion layer is further provided on the side of the polishing layer opposite to the polishing surface.
The polishing pad according to [1] or [2].
[4]
The amount of compression deformation of the laminate of the polishing layer and the cushion layer is 40 to 70 μm.
The polishing pad according to [3].
[5]
A step of applying a resin solution containing a resin dissolved in an organic solvent onto a film-forming substrate and coagulating the resin solution in an aqueous coagulation liquid to obtain a resin sheet.
It has a step of stretching the obtained resin sheet.
Manufacturing method of polishing pad.
[6]
It has a polishing step of polishing an object to be polished using the polishing pad according to any one of [1] to [4].
Manufacturing method of polished products.

According to the present invention, it is possible to provide a polishing pad capable of suppressing the occurrence of roll-off and scratches, a method for manufacturing the polishing pad, and a method for manufacturing a polished product using the polishing pad.

It is the schematic which shows the polishing process which used the conventional soft plastic sheet as a polishing layer. It is the schematic which shows the roll-off which occurred in the peripheral part of the object to be polished. It is the schematic which shows the polishing process using the polishing pad of this embodiment.

Hereinafter, embodiments of the present invention (hereinafter referred to as “the present embodiment”) will be described in detail, but the present invention is not limited thereto, and various modifications can be made without departing from the gist thereof. Is.

[Polishing pad]
The polishing pad of the present embodiment has a polishing layer having bubbles inside. The 100% modulus of the resin constituting this polishing layer at 23 ± 2 ° C. is 5 to 20 MPa, and the wall ratio W ₁₀₀ of the resin at a depth of 100 μm from the polished surface of the polishing layer is 20 to 40%. ..

As described above, the conventional polishing pad using soft plastic is flexible and easily deformed, and is suitable for finish polishing and the like. However, due to its flexibility, there is a problem that excessive stress is applied to the peripheral portion of the object to be polished when the object to be polished is pressed, and roll-off is likely to occur.

It is considered that one of the reasons why the stress received by the object to be polished from the stretched portion increases is that the flexibility of the stretched portion decreases due to the foamed structure being crushed by the stretching. On the other hand, the polishing pad 30 of the present embodiment has a bubble structure 32 that relieves the stress applied to the peripheral portion W1 of the object to be polished W when the object to be polished W is pressed against the object W. More specifically, in order to ensure flexibility even when stretched and to keep the stress received by the object to be polished from the stretched portion low, the relationship between the resin and bubbles at a predetermined depth from the polished surface is set within a predetermined range. (See Fig. 3).

Further, in addition to the above, the polishing pad 30 of the present embodiment may have a cushion layer 34 on the opposite side of the polishing layer 31 from the polishing surface 33 via an adhesive layer such as double-sided tape. Further, the polishing pad 30 of the present embodiment may have an adhesive layer such as double-sided tape for fixing the polishing pad to the polishing surface plate on the surface of the cushion layer 34 opposite to the polishing layer side. Each configuration will be described in detail below.

[Abrasive layer]
The polishing layer has a polishing surface that comes into direct contact with the object to be polished when the object to be polished is polished by the polishing pad.

The 100% modulus of the resin constituting the polishing layer at 23 ± 2 ° C. is 5 to 20 MPa, preferably 5 to 10 MPa, and more preferably 6 to 9 MPa. When the 100% modulus is 5 MPa or more, the deformation of the polishing layer when the object to be polished is pressed is suppressed, and the roll-off is further suppressed. Further, when the 100% modulus is 20 MPa or less, the flexibility of the polishing layer is further improved and the generation of scratches is further suppressed. The 100% modulus is obtained when a non-foamed sheet (test piece) using the same material as the layer to be measured is stretched 100% in an environment of room temperature 23 ± 2 ° C., that is, 2 of the original length. It is a value obtained by dividing the tensile force when stretched twice by the initial cross-sectional area of the test piece.

Further, as described above, the polishing layer of the present embodiment has a bubble structure that relieves stress applied to the peripheral portion of the object to be polished. _{In the present embodiment, as an index of such a bubble structure, a wall ratio W 100} indicating the ratio of resin and bubbles at a depth of 100 μm from the polished surface of the polishing layer is used. The wall ratio W ₁₀₀ is 20 to 40%, preferably 22 to 37%, and more preferably 25 to 35%. When the wall ratio W ₁₀₀ is 20% or more, the ratio of air bubbles becomes small, so that when the polishing layer is repeatedly pressed, partial sinking occurs and it is difficult for it to return to its original state. Become. If the settling occurs, the polishing rate may vary when the polishing pad is used repeatedly. However, when the wall ratio W ₁₀₀ is 20% or more, such variation can be suppressed. On the other hand, when the wall ratio W ₁₀₀ is 40% or less, the stress applied to the peripheral portion of the object to be polished can be suppressed to be smaller, and roll-off can be suppressed.

Further, as a bubble structure that relieves stress applied to the peripheral portion of the object to be polished, it is preferable that the wall ratio W becomes lower as the distance from the polished surface increases, that is, the proportion of the bubbles increases. From this point of view, as an index of the bubble structure, the reduction rate _{of the resin wall ratio W 100 at} a depth of 100 μm from the polished surface with respect to the _{resin wall ratio W 50 at a depth of 50 μm from the polished surface ((W 50} − W _100). ) / W ₅₀ ) can be used.

The reduction rate ((W ₅₀ − W ₁₀₀ ) / W ₅₀ ) in the present embodiment is preferably 30 to 60%, more preferably 33 to 57%, and even more preferably 35 to 55%. The larger the rate of decrease ((W _50- W ₁₀₀ ) / W ₅₀ ), the more rapidly the proportion of air bubbles occupies from the polished surface toward the depth of 100 μm, and the rate of decrease ((W _50- W ₁₀₀ ) / W ₅₀ ). The larger the value, the more gradually the proportion of air bubbles occupies from the polished surface toward a depth of 100 μm. Therefore, when the reduction rate ((W ₅₀ − W ₁₀₀ ) / W ₅₀ ) is 30% or more, the stress applied to the peripheral portion of the object to be polished tends to be further relaxed. Further, when the reduction rate ((W ₅₀ − W ₁₀₀ ) / W ₅₀ ) is 60% or less, the decrease in the polishing rate due to the excessive increase in the flexibility of the polishing layer tends to be suppressed.

Examples of the wall ratios W ₁₀₀ and W ₅₀ include a method of adjusting the amount of the organic solvent used in the resin solution, a method of stretching the resin sheet, and a method of adjusting the stretching ratio in the manufacturing method described later. The larger the amount of the organic solvent used in the resin solution, the larger the bubbles formed and the smaller the wall ratio, and the smaller the amount of the organic solvent used, the larger the wall ratio tends to be. Further, by stretching the resin sheet, the wall ratio becomes smaller than that of the resin sheet before stretching, and the wall ratio can be adjusted by the stretching ratio. Further, the wall ratios W ₁₀₀ and W ₅₀ can be measured by the method described in the examples.

The three-dimensional shape of the bubbles contained in the polishing layer is not particularly limited, and examples thereof include a substantially spherical shape, a cone shape, and a spindle shape. In the case of a cone shape or a spindle shape, a cone shape or a spindle shape long in the thickness direction of the polishing layer is preferable. Since the polishing layer contains air bubbles having such a shape, the polishing pad tends to easily hold the slurry and also tends to contain the polishing debris. Further, since the polishing layer has cone-shaped or spindle-shaped bubbles long in the thickness direction of the polishing layer, it tends to be easy to form a polishing layer satisfying the wall ratio W.

The resin constituting the polishing layer is not particularly limited, and examples thereof include polyurethane resin, polysulfone resin, polyimide resin, and other resins used for the resin sheet portion of the conventional polishing pad. Of these, polyurethane resin is preferred. By using such a resin, the occurrence of roll-off and scratch tends to be further suppressed. Further, the 100% modulus tends to be set in the above range, and a desired bubble structure tends to be easily formed. The resin constituting the polishing layer may be used alone or in combination of two or more.

The polyurethane resin is not particularly limited, and examples thereof include polyester-based polyurethane resins, polyether-based polyurethane resins, polyester-ether-based polyurethane resins, and polycarbonate-based polyurethane resins. One type of polyurethane resin may be used alone, or two or more types may be used in combination.

The polishing layer may contain other additives. The other additives are not particularly limited as long as they can be used for the polishing layer in the polishing pad, and are, for example, pigments such as carbon black, film forming stabilizers such as nonionic surfactants, and anionic surfactants. Foaming modifiers such as.

[Cushion layer]
The polishing pad of the present embodiment may have a cushion layer on a surface of the polishing layer opposite to the surface (polishing surface) for polishing the object to be polished. By providing the cushion layer, the influence of the hardness and flatness of the surface plate is further mitigated, and uneven contact between the work and the polished surface tends to be further prevented. As a result, the service life of the polishing pad can be extended, and the occurrence of chipping such as chipping of the peripheral portion of the work tends to be more effectively prevented.

The material of the cushion layer is not particularly limited, and examples thereof include resin-impregnated non-woven fabric, synthetic rubber, polyethylene foam, and polyurethane foam. Of these, polyurethane foam is more preferred.

The thickness of the cushion layer is preferably 0.1 to 10 mm, more preferably 0.4 to 3 mm. When the thickness of the cushion layer is within the above range, it is less likely to be subject to mechanical restrictions when the polishing pad is installed in the polishing machine, and the influence of the polishing surface plate tends to be sufficiently reduced.

In the polishing pad of the present embodiment, it is preferable that the laminated body of the polishing layer and the cushion layer has desired characteristics. From such a viewpoint, the amount of compressive deformation of the laminated body of the polishing layer and the cushion layer is preferably 40 to 70 μm, more preferably 45 to 68 μm, and further preferably 50 to 65 μm. When the amount of compression deformation is within the above range, roll-off and scratch tend to be further suppressed.

[Adhesive layer]
The polishing pad of the present embodiment may have an adhesive layer between the polishing layer and the cushion layer or on the surface of the cushion layer opposite to the polishing layer side. Here, the adhesive layer arranged between the polishing layer and the cushion layer adheres the polishing layer and the cushion layer, and the adhesive layer arranged on the surface of the cushion layer opposite to the polishing layer side is polished. It is used to attach a polishing pad to the polishing surface plate of the machine.

The adhesive layer is not particularly limited, and examples thereof include double-sided tape and an adhesive. In the case of double-sided tape, a release paper may be attached to the adhesive surface.

[Manufacturing method of polishing pad]
The polishing pad manufacturing method of the present embodiment includes a step of applying a resin solution containing a resin dissolved in an organic solvent on a film-forming substrate and coagulating the resin solution in an aqueous coagulation liquid to obtain a resin sheet. It has a step of stretching the obtained resin sheet.

Generally, as a method for forming a resin sheet, a wet film forming method and a dry molding method (also referred to as a molding method) are known, but in the present embodiment, the wet film forming method is adopted. In the wet film formation method, a resin solution in which a resin is dissolved in a water-miscible organic solvent is continuously applied to a film-forming substrate, and the resin is coagulated and regenerated into a sheet by immersing the resin in an aqueous coagulation liquid. Let me. The inside of the sheet thus obtained contains a large number of foams generated by the solidification and regeneration of the resin. Then, this can be washed and then dried to obtain a long resin sheet. Hereinafter, each step of the wet film forming method will be described in detail.

Generally, the wet film forming method includes a preparation step, a coating step, a solidification regeneration step, and a washing and drying step. Further, if necessary, a grinding / removing step for flattening the surface of the sheet may be included.

In the preparatory step, the resin is dissolved in a soluble and water-miscible organic solvent, and if desired, an additive is added and mixed so as to be uniform to prepare a resin solution. The resin solution is preferably defoamed under vacuum after removing agglomerates and the like by filtration.

For example, examples of a water-soluble organic solvent in which polyurethane can be dissolved include N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), and N-methyl. Polar solvents such as pyrrolidone (NMP) and methyl ethyl ketone (MEK) can be mentioned.

The resin concentration in the resin solution is not limited, but can be, for example, 10 to 50% by mass.

Further, for example, a foaming regulator for controlling foaming, a film forming stabilizer for stabilizing the solidification and regeneration of polyurethane, and an additive such as carbon black for stabilizing foaming are added to the resin solution. Can be done.

The film-forming stabilizer is not particularly limited, and examples thereof include nonionic surfactants. Specifically, for example, polyoxyethylene alkyl ether, polyoxypropylene alkyl ether, polyoxyethylene polyoxypropylene alkyl ether, perfluoroalkylethylene oxide adduct, glycerin fatty acid ester, propylene glycol fatty acid ester, and the like having 3 carbon atoms. Examples thereof include compounds to which the above alkyl chains are added.

The foaming regulator is not particularly limited, and examples thereof include anionic surfactants. Specifically, for example, sodium lauryl sulfate, carboxylate, sulfonate, sulfate ester salt, phosphoric acid ester salt and the like can be mentioned.

In the coating step, the resin solution prepared in the preparatory step is applied substantially uniformly to the strip-shaped film-forming substrate using a knife coater or the like at room temperature to form a coating film. At this time, the coating thickness (coating amount) of the resin solution can be adjusted by adjusting the gap (clearance) between the knife coater and the film-forming substrate.

As the film-forming base material, a flexible film, a non-woven fabric, a woven fabric or the like can be used. When a non-woven fabric or woven fabric is used as the film-forming base material, the base material is previously prepared with water or an aqueous organic solvent solution (DMF and water) in order to prevent the polyurethane solution from penetrating into the film-forming base material when the polyurethane solution is applied. It is preferable to perform pretreatment (sealing) by immersing in a mixed solution of

In the solidification / regeneration step, the coating film (the film-forming base material coated with the resin solution) obtained in the coating step is subjected to a coagulation solution (for example, water or a solvent containing water as a main component) which is a poor solvent for the resin. The coating film of the resin solution is solidified and regenerated into a sheet having a large number of foams inside.

In the coagulation liquid, generally, first, a skin layer having a thickness of about several μm in which microporous formation is formed is formed on the surface of the applied resin solution, and then the organic solvent in the polyurethane solution is replaced with the coagulation liquid. As the process progresses, the resin solidifies and regenerates in the form of a sheet on one side of the film-forming base material. At this time, typically, the organic solvent is desolved from the resin solution, and the organic solvent and the coagulating liquid are replaced, so that the fine particles formed on the skin layer under the skin layer (the film-forming substrate side) are typically formed. A foam layer having a larger pore diameter than the porous surface and having a rounded shape in the thickness direction of the sheet and having a substantially triangular cross section is formed in a state of being substantially evenly dispersed, but the bubble structure is not limited to this.

In the washing / drying step, the resin sheet solidified and regenerated in the solidification / regeneration step is peeled off from the film-forming substrate, washed in a cleaning liquid such as water, and the organic solvent remaining in the resin is removed. After cleaning, the obtained resin sheet is dried with a cylinder dryer or the like, if necessary.

A cylinder dryer is a dryer provided with a cylinder having a heat source inside, and the resin sheet is dried by passing along the peripheral surface of the cylinder. The dried resin sheet is wound into a roll.

In order to obtain a polishing layer having a predetermined wall ratio near the surface layer, a method of adjusting the amount of organic solvent used in the resin solution, a method of stretching the resin sheet, a method of adjusting the amount of buffing on the surface of the resin sheet, and a resin. Examples thereof include a method of adding a foaming aid to the solution.

The resin sheet wound as described above is stretched at a predetermined stretching ratio by a stretching step. As a result, the resin sheet is stretched and the wall ratio changes. The stretch ratio of the resin sheet is 105 to 300% (meaning a length of 1.05 to 3 times the original length), and more preferably 110 to 250%. Although it depends on the type of resin constituting the resin sheet, when the draw ratio is 105% or more, it becomes easy to form a polishing layer having a predetermined wall ratio, and when the draw ratio is 300% or less, it becomes easy to form. There is a tendency to avoid breakage of the resin sheet and excessive thinning.

In the grinding / removing step, at least one of both sides of the sheet is ground and / or partially removed by buffing or slicing. The thickness of the sheet can be made uniform by buffing or slicing, and the surface of the sheet can be made flatter. Therefore, the pressing force on the object to be polished is further equalized and the flatness of the object to be polished is improved. Can be made to.

The polishing layer in the present embodiment is not limited to the above-mentioned wet film forming method, but two types having different 100% modulus by other methods, for example, a supercritical gas foaming method as disclosed in Japanese Patent No. 4624781. It can also be manufactured from thermoplastic polyurethane.

[Manufacturing method of polished products]
The method for producing a polished product of the present embodiment includes a polishing step of polishing an object to be polished using the above-mentioned polishing pad. The polishing step may be primary polishing (coarse polishing), finish polishing, or both of them.

First, a polishing pad is attached to the polishing surface plate of the polishing machine and fixed. Then, the object to be polished held by the holding surface plate arranged so as to face the polishing surface plate is pressed against the polishing surface side of the polishing pad, and the polishing surface plate is supplied with slurry between the work and the polishing pad. And / or by rotating the holding surface plate relatively, the machined surface of the object to be polished is polished.

The slurry may contain a strong oxidizing agent, a solvent, and polishing particles used in chemical mechanical polishing. The strong oxidizing agent is not particularly limited, and examples thereof include potassium permanganate and sodium permanganate. Examples of the solvent include water and organic solvents. As the organic solvent, hydrocarbons are preferable, and hydrocarbons having a high boiling point are more preferable. The hydrocarbon is not particularly limited, and examples thereof include paraffinic hydrocarbons, olefin hydrocarbons, aromatic hydrocarbons, and alicyclic hydrocarbons. Examples of hydrocarbons having a high boiling point include petroleum-based hydrocarbons having an initial distillation point of 220 ° C. or higher. The solvent may be used alone or in combination of two or more.

In addition, the slurry may contain other additives, if necessary. Examples of such additives include nonionic surfactants, anionic surfactants, carboxylic acid esters, carboxylic acid amides and carboxylic acids.

The material to be polished is not particularly limited, but for example, materials such as semiconductor devices and electronic components, particularly Si substrate (silicon wafer), SiC (silicon carbide) substrate, GaAs (gallium arsenide) substrate, glass, hard disk and LCD. Examples thereof include a thin substrate (object to be polished) such as a substrate for (liquid crystal display). Among these, the method for producing a polished product of the present embodiment is a method for producing a difficult-to-polish material such as sapphire, SiC, GaN, and diamond, which can be applied to power devices, LEDs, and the like. It can be preferably used.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited to the following examples.

(Example 1)
[Abrasive layer manufacturing process]
100 parts by mass of a solution of 30% polyester polyurethane resin having a 100% modulus of 9 MPa at 25 ° C. in dimethylformamide (DMF), 7.9 parts by mass of carbon black, a film-forming stabilizer (nonionic surfactant) A resin solution was obtained by adding 2.7 parts by mass, 1.2 parts by mass of a foaming conditioner (anionic surfactant), 8 parts by mass of water, and 55 parts by mass of DMF, and mixing and stirring.

Next, a PET film was prepared as a base material for film formation, and the above resin solution was applied thereto using a knife coater to obtain a coating film.

Next, the obtained coating film was immersed in water as a coagulation liquid together with a film-forming base material, and the resin was coagulated and regenerated to obtain a resin sheet. The resin sheet was taken out from the coagulation bath, the base material for film formation was peeled off from the resin sheet, and then the resin sheet was immersed in a cleaning liquid consisting of water to remove DMF as a solvent. Then, the resin sheet was wound while being dried.

The obtained resin sheet 0.6 mm was stretched by 140% in the width direction, and the surface of the resin sheet was buffed to obtain a resin sheet having a thickness of 0.4 mm, which was used as a polishing layer.

[Cushion layer manufacturing process]
100 parts by mass of a solution prepared by dissolving 30% of polyester polyurethane resin having a 100% modulus of 24 MPa at 25 ° C. with DMF, 5.4 parts by mass of carbon black, and 2.7 parts by mass of a film-forming stabilizer (nonionic surfactant). A resin solution was obtained by adding 1.2 parts by mass of a foam adjusting agent (anionic surfactant), 8 parts by mass of water, and 55 parts by mass of DMF for adjusting the viscosity, and mixing and stirring.

Next, a PET film was prepared as a base material for film formation, and the above resin solution was applied thereto using a knife coater to obtain a coating film.

Next, the obtained coating film was immersed in water as a coagulation liquid together with a film-forming base material, and the resin was coagulated and regenerated to obtain a resin sheet. The resin sheet was taken out from the coagulation bath, the base material for film formation was peeled off from the resin sheet, and then the resin sheet was immersed in a cleaning liquid consisting of water to remove DMF as a solvent. Then, the resin sheet was dried to obtain a cushion layer having a thickness of 0.4 mm.

[Abrasion pad manufacturing process]
The cushion layer also obtained above was bonded to the unbuffed surface side of the polishing layer obtained above using an adhesive made of polyurethane resin. Then, a double-sided tape made of a PET base material provided with a release paper was attached to the surface of the cushion layer that was not attached to the polishing layer to form a polishing pad.

(Example 2)
In the polishing layer manufacturing step, all the same as in Example 1 except that a polyester polyurethane resin having a 100% modulus at 25 ° C. of 6.3 MPa was used and the obtained resin sheet was further stretched by 110% in the width direction. A polishing pad was prepared according to the formulation.

(Comparative Example 1)
In the polishing layer preparation step, polishing pads were prepared in the same manner as in Example 1 except that the obtained resin sheet was not stretched.

(Comparative Example 2)
In the polishing layer preparation step, polishing pads were produced by the same formulation as in Example 1 except that the amount of DMF added was changed from 55 parts by mass to 30 parts by mass.

[Wall ratio]
Tomographic images at depths of 100 μm and 50 μm from the polished surface of the polishing layer were obtained using a three-dimensional measurement X-ray CT apparatus (TDM1000H-II (2K) manufactured by Yamato Scientific Co., Ltd.). Next, the area of the bubble portion and the resin portion was calculated for the obtained tomographic image using image processing software (VG Studio MAX 3.0 manufactured by Volume Graphics), and the ratio of the resin portion area to the total area was calculated as the wall ratio. It was calculated as.

[Compression deformation amount]
Using a shopper type thickness measuring device (pressurized surface: circular with a diameter of 1 cm), the amount of compression deformation of the polishing pad was measured in accordance with Japanese Industrial Standards (JIS L 1021). Specifically, the thickness t0 after being pressurized with the initial load for 30 seconds was measured, and then the thickness t1 after being left for 5 minutes under the final load was measured. At this time, the initial load was 100 g / cm ² and the final load was 1120 g / cm ² . The amount of compression deformation was calculated by the following mathematical formula (1).
Formula (1): Compressive deformation amount (mm) = t0-t1

[Polishing test]
The polishing pads obtained in Examples and Comparative Examples were attached to the surface plate of the polishing machine. Then, the silicon wafer (diameter 12 inches × thickness 780 μm) to be polished was polished under the polishing conditions shown below.
(Polishing conditions)
Rotation speed: (Surface plate) 40 rpm / (Top ring) 41 rpm
Polishing pressure: 100 g / cm ²
Swing: 20 mm
Abrasive: GLANZOX 1306 manufactured by Fujimi Incorporated (stock solution: water = 1:20)

[Evaluation of roll-off]
The SFQRmax (sight squares range) of the outer peripheral portion of the silicon wafer after the polishing test was evaluated. SFQR is a numerical value indicating the degree of roll-off of the wafer.

Regarding the results of Examples and Comparative Examples, those in which improvement of 10% or more was observed from Example 1 based on the results of Example 1 were ◎, and those in which improvement was observed in the range of less than 10% from Example 1. Was evaluated as ◯, those deteriorated in the range of less than 10% from Example 1 were evaluated as Δ, and those deteriorated by 10% or more from Example 1 were evaluated as × by relative comparison.

[Presence / absence of scratch]
The surface of 6 objects to be polished after the polishing test was measured in the high-sensitivity measurement mode of a wafer surface inspection device (manufactured by KLA Corporation, trade name "Surfscan SP1DLS"), and the presence or absence of scratches on the surface of the object to be polished. Was counted and evaluated according to the following evaluation criteria.
(Evaluation criteria)
◯: When there is no polished object with scratches ×: When there is one or more polished objects with scratches

The polishing pad of the present invention has industrial applicability as a polishing pad for polishing a silicon wafer or the like.

Claims (6)

It has a polishing layer with air bubbles inside,
The 100% modulus of the resin constituting the polishing layer at 23 ± 2 ° C. is 5 to 20 MPa.
_{The resin wall ratio W 100 at} a depth of 100 μm from the polished surface of the polishing layer is 20 to 40%.
Polishing pad. The reduction rate ((W _50- W ₁₀₀ ) / W _{50 ) of the resin wall ratio W 100 at} a depth of 100 μm from the polished surface is 30 to 60 with _{respect to the resin wall ratio W 50 at} a depth of 50 μm from the polished surface. %,
The polishing pad according to claim 1. A cushion layer is further provided on the side of the polishing layer opposite to the polishing surface.
The polishing pad according to claim 1 or 2. The amount of compression deformation of the laminate of the polishing layer and the cushion layer is 40 to 70 μm.
The polishing pad according to claim 3. A step of applying a resin solution containing a resin dissolved in an organic solvent onto a film-forming substrate and coagulating the resin solution in an aqueous coagulation liquid to obtain a resin sheet.
It has a step of stretching the obtained resin sheet.
Manufacturing method of polishing pad. A polishing step of polishing an object to be polished using the polishing pad according to any one of claims 1 to 4.
Manufacturing method of polished products.

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