JP7328838B2 - Polishing pad, method for producing same, and method for producing abrasive product - Google Patents

Description

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

A wafer such as a silicon single crystal is formed with a small notch (notch portion) formed at the edge portion of the outermost periphery of the wafer in order to indicate its direction. The surface of the wafer is subjected to chemical mechanical polishing or the like using a polishing slurry and a polishing pad, and the notch portion is also subjected to polishing for the purpose of preventing chipping and entrainment of dust.

As a polishing pad used for polishing such a notch portion, for example, a polishing pad formed by impregnating a base material with a resin has a porosity that increases from the outside in the thickness direction of the base material toward the center in the thickness direction. A polishing pad or the like configured to have a gradient distribution is known (see, for example, Patent Document 1).

JP 2011-009584 A

However, since the polishing pad disclosed in Patent Document 1 has different densities and hardness depending on the location, it takes time to start up, and the amount of slurry held and the contact with a work (workpiece) such as a wafer are uniform. Instead, there is a risk that the polishing state will vary and scratches will occur. In addition, the polishing pad for polishing the notch portion of the work contacts the work in the polishing process so that the main surface of the work and the main surface of the polishing pad are substantially perpendicular to each other, so the wear of the polishing pad shortens its life. There is

SUMMARY OF THE INVENTION It is an object of the present invention to provide a polishing pad for notch polishing with excellent wear resistance, a method for producing the same, and a method for producing a polished product using the polishing pad. With the goal.

The present inventors have made intensive studies to solve the above problems. As a result, by adjusting the orientation of the fibers on the plane parallel to the surface of the polishing pad, the ends of the fibers become the polishing surface, thereby suppressing the falling off of the fibers and resin, thereby solving the above problems. The inventors have found that it is possible and have completed the present invention.

That is, the present invention is as follows.
[1]
A circular or ring-shaped polishing pad made of a resin-impregnated nonwoven fabric containing a nonwoven fabric and a resin impregnated in the nonwoven fabric,
having a polishing section on the outer periphery for polishing the notch formed on the outer peripheral edge of the work;
In a cross section obtained by cutting the polishing pad in the thickness direction, the ratio of fibers oriented within ±30° with respect to a direction horizontal to the surface of the polishing pad is 50% or more.
polishing pad.
[2]
wherein the resin comprises a water-based polyurethane resin;
The polishing pad according to [1].
[3]
the resin does not have microporosity;
The polishing pad according to [1] or [2].
[4]
100% modulus of the resin is 0.5 to 5.0 MPa,
[1] The polishing pad according to any one of [3].
[5]
The surface of the resin-impregnated nonwoven fabric has a Shore A hardness of 60 to 90°.
[1] The polishing pad according to any one of [4].
[6]
The resin-impregnated nonwoven fabric has a density of 0.48 to 0.70 g/cm ³ ,
[1] The polishing pad according to any one of [5].
[7]
The mass ratio of the resin to the nonwoven fabric of the resin-impregnated nonwoven fabric is 1.35 or more.
[1] The polishing pad according to any one of [6].
[8]
A method for manufacturing a polishing pad according to any one of [1] to [7],
a nonwoven fabric production step of laminating a plurality of sheets of fleece in which fibers are oriented in the horizontal direction and entangling the fibers to produce a nonwoven fabric in which the fibers are oriented in the in-plane direction of the main surface of the nonwoven fabric;
an impregnation step of impregnating the nonwoven fabric with an aqueous resin dispersion;
a drying step of drying the impregnated water-based resin dispersion to obtain a resin-impregnated nonwoven fabric;
A cutting step of cutting the obtained resin-impregnated nonwoven fabric into a circular shape or an annular shape;
a polishing portion forming step of forming a polishing portion for polishing a notch portion formed on the outer peripheral edge of the work on the outer periphery of the cut resin-impregnated nonwoven fabric;
A method for manufacturing a polishing pad.
[9]
Using the polishing pad according to any one of [1] to [7], a polishing step of polishing the notch formed in the outer peripheral edge of the work,
A method for producing an abrasive product.

According to the present invention, it is possible to provide a polishing pad for notch polishing with excellent wear resistance, a method for producing the same, and a method for producing a polished product using the polishing pad.

It is the schematic which shows an example of the usage method of the polishing pad of this embodiment. It is a schematic diagram showing an example of a section of a polishing pad. 1 shows one cross-sectional photograph of the polishing pad of Example 1. FIG. 1 shows one cross-sectional photograph of the polishing pad of Comparative Example 1. FIG.

Hereinafter, an embodiment of the present invention (hereinafter referred to as "this embodiment") will be described in detail, but the present invention is not limited to this, and various modifications are possible without departing from the gist thereof. is. In addition, unless otherwise specified, positional relationships such as top, bottom, left, and right in the drawings are based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios of the drawings are not limited to the illustrated ratios.

[Polishing pad]
The polishing pad of the present embodiment is a circular or ring-shaped polishing pad made of resin-impregnated nonwoven fabric containing nonwoven fabric and resin impregnated in the nonwoven fabric, and a notch formed in the outer peripheral edge of a work (workpiece). The fibers are oriented within ±30° with respect to the direction horizontal to the surface of the polishing pad in a cross section obtained by cutting the polishing pad in the thickness direction. is 50% or more. The term “annular shape” means a shape having a hole penetrating in the thickness direction of the disk near the center of the substantially disk-like shape.

FIG. 1 shows an example of how to use the polishing pad of this embodiment. The polishing pad of this embodiment is a circular or ring-shaped polishing pad, and polishes a notch formed on the outer peripheral edge of the workpiece by the polishing section. Specifically, the notch portion is polished by the polishing portion by rotating the polishing pad while bringing the polishing portion into contact with the notch portion of the workpiece.

The polishing pad for polishing the notch portion of the work is brought into contact with the main surface of the work so that the main surface of the polishing pad is substantially perpendicular to the main surface of the polishing pad in the polishing process, so the polishing portion of the polishing pad is easily worn and has a short life. There is Abrasion of the polishing portion is mainly caused by scraping or dropping of fibers or resin from the contact surface between the polishing portion and the workpiece (hereinafter also referred to as "polishing surface") due to polishing. In particular, it has been found that the more the fibers are not buried deep in the polishing pad and the easier it is to detach from the polishing surface, the easier it is to wear.

In contrast, in this embodiment, the orientation of the fibers is adjusted in the direction parallel to the surface of the polishing pad. As a result, one end of the fiber is exposed to the polishing surface and the other end of the fiber is buried in the polishing pad, thereby preventing the fiber from coming off. In addition, by suppressing the shedding of the fiber that is the base material, it is possible to suppress the shedding of the resin adhering thereto.

From the above point of view, the polishing pad of the present embodiment defines the fiber orientation ratio in the cross section in the thickness direction. Specifically, in the cross section of the polishing pad in the thickness direction, the ratio of fibers oriented within ±30° with respect to the direction horizontal to the surface of the polishing pad is 50% or more based on the number of fibers. , preferably 60% or more, more preferably 70% or more. As described above, when the proportion of fibers oriented within ±30° with respect to the direction horizontal to the surface of the polishing pad is 50% or more, abrasion resistance is further improved.

The proportion of fibers oriented nearly parallel to the horizontal direction to the surface of the polishing pad can be measured by the method described in Examples. For example, a cross section is obtained by cutting the polishing pad along a plane parallel to the thickness direction of the polishing pad. Then, by examining the orientation of the fibers reflected in the photograph of the cross section obtained in this way, the ratio of the fibers oriented within ±30° with respect to the direction horizontal to the surface of the polishing pad can be calculated. can be done.

1 and 2, the polishing portion in this embodiment is the peripheral portion of the polishing pad and has a shape that fits the notch portion of the workpiece.

When increasing the proportion of fibers oriented parallel to and parallel to the surface of the polishing pad, the thickness of the fleece must be adjusted, the number of layers and entanglement density must be adjusted, and the composition/viscosity of the resin for the non-woven fabric must be adjusted. It can be controlled by adjusting the impregnation ratio (restriction).

[Resin impregnated nonwoven fabric]
The polishing pad of this embodiment is made of a resin-impregnated nonwoven fabric containing a nonwoven fabric and a resin impregnated in the nonwoven fabric. Hereinafter, aspects of the resin-impregnated nonwoven fabric constituting the polishing pad will be described in detail.

(non-woven fabric)
The fibers constituting the nonwoven fabric are not particularly limited, but examples include polyamide fibers, polyester fibers such as polyethylene terephthalate, polyolefin fibers such as polypropylene and polyethylene, and synthetic fibers such as acrylic fibers such as (meth)acrylate. include natural fibers such as cotton and linen; The fibers constituting the nonwoven fabric may be used singly or in combination of two or more. Also, nonwoven fabrics made of different fibers may be layered and used. The method for entangling fibers when obtaining a nonwoven fabric is not particularly limited, and may be, for example, needle punching or hydroentangling.

The fineness of fibers constituting the nonwoven fabric is preferably 0.1 to 10 dtex, more preferably 1.1 to 7.8 dtex, still more preferably 2.2 to 5.6 dtex. When the fineness is within the above range, the occurrence of scratches is reduced, and the proportion of fibers having an orientation nearly parallel to the direction horizontal to the surface of the polishing pad tends to be easily adjusted to the above range.

The average fiber length of fibers constituting the nonwoven fabric is preferably 20 to 80 mm, more preferably 30 to 70 mm, still more preferably 35 to 60 mm. When the average fiber length is within the above range, the occurrence of scratches is reduced, and the proportion of fibers having an orientation nearly parallel to the direction horizontal to the surface of the polishing pad tends to be easily adjusted within the above range.

The thickness of the nonwoven fabric is preferably 2-7 mm, more preferably 3-6 mm, and even more preferably 4-5 mm. The thickness of the nonwoven fabric can be appropriately adjusted to suit the notches to be polished.

(resin)
The resin with which the nonwoven fabric is impregnated is not particularly limited, but examples thereof include water-based resins and solvent-based resins, polyurethane resins such as polyurethane and polyurethane polyurea; vinyl-based resins such as vinyl acetate and polyvinylidene fluoride; polysulfone-based resins such as polysulfone and polyethersulfone; acylated cellulose-based resins such as acetylated cellulose and butyrylated cellulose; polyamide-based resins; .

Among these, water-based resins are preferred, and water-based polyurethane resins are more preferred. Examples of polyurethane resins include, but are not limited to, polyester-based polyurethane resins, polyether-based polyurethane resins, and polycarbonate-based polyurethane resins. Use of such a resin tends to further improve wear resistance. Although the reason for this is not particularly limited, it is considered that the cross-sectional shape of the polishing pad differs depending on the resin adhesion method.

For example, the cross-sectional shape of a polishing pad differs between a polishing pad obtained by impregnating a non-woven fabric with a water-based resin and drying it and a polishing pad obtained by wet coagulation. When a polishing pad is obtained by wet coagulation, microporosity generated during coagulation regeneration is usually generated in the resin portion of the polishing pad as shown in FIG. On the other hand, when a polishing pad is obtained by impregnating a non-woven fabric with a water-based resin (water-based resin dispersion) and drying it as shown in FIG. Since the resin portion tends to become more brittle with voids such as microporous, from the viewpoint of improving wear resistance, it is preferable to use a water-based resin. From this point of view, it is preferable that the resin of the polishing pad of the present embodiment does not have microporous. The microporous means, for example, the black holes in the resin part that can be seen in the photograph of FIG. means about 1 to 20 μm. Microporous is different from voids between amorphous fibers.

Note that the wet coagulation is a method of solidifying and regenerating the resin by immersing the resin solution in a coagulating liquid which is a poor solvent for the resin. When a nonwoven fabric is impregnated with a resin solution and then wet coagulation is used, in the coagulation liquid, the solvent of the resin solution and the coagulation liquid progress on the surface of the resin solution adhering to the fibers of the nonwoven fabric, and as a result, The resin is coagulated and reproduced on the surface of the fiber.

The 100% modulus of the resin is preferably 0.5-5.0 MPa, more preferably 0.5-4.0 MPa, and still more preferably 1.0-3.0 MPa. When the 100% modulus of the resin is within the above range, the occurrence of scratches tends to be suppressed and the quality of the resulting polished object tends to be further improved. The 100% modulus is the value obtained by dividing the load applied to a sheet made of the resin when it is stretched 100%, that is, when it is stretched twice its original length, by the unit area.

The mass ratio of the resin to the nonwoven fabric of the resin-impregnated nonwoven fabric is preferably 1.35 or more, more preferably 1.40 to 3.00, still more preferably 1.60 to 2.70. When the mass ratio of the resin with which the non-woven fabric is impregnated is within the above range, the hardness of the polishing pad is further improved, which tends to further improve the life of the polishing pad. Also, physical properties such as hardness of the polishing pad can be adjusted by adjusting the proportion of the nonwoven fabric and the resin.

The Shore A hardness of the resin-impregnated nonwoven fabric is preferably 60 to 90°, more preferably 65 to 90°, still more preferably 75 to 85°. When the Shore A hardness is 60° or more, the life of the polishing pad tends to be further improved. Moreover, since the Shore A hardness is 90° or less, the occurrence of scratches tends to be suppressed, and the quality of the resulting polished object tends to be further improved. The Shore A hardness can be measured by the method described in Examples. Also, the Shore A hardness can be adjusted by, for example, the type and amount of resin used.

The density of the resin-impregnated nonwoven fabric is preferably 0.48-0.70 g/cm ³ , more preferably 0.48-0.62 g/cm ³ , still more preferably 0.52-0.62 g/cm 3 is ³ . A density of 0.48 g/cm ³ or more tends to further improve the life of the polishing pad. Further, when the density is 0.70 g/cm ³ or less, the occurrence of scratches is suppressed, and the quality of the resulting polished object tends to be further improved. The density can be measured by the method described in Examples. Also, the density can be adjusted by, for example, the impregnation amount of the resin.

The compressibility of the resin-impregnated nonwoven fabric is preferably 1.0 to 5.0%, more preferably 1.0 to 4.0%, still more preferably 1.2 to 3.0%. When the compressibility is within the above range, the adhesion to the notch portion is improved, and deformation of the polishing pad is minimized during the polishing process in which the main surface of the workpiece and the main surface of the polishing pad are brought into contact so as to be substantially perpendicular to each other. tend to be more restrained. The compressibility can be measured by the method described in Examples. Also, the compressibility can be adjusted by adjusting the density.

The compression elastic modulus of the resin-impregnated nonwoven fabric is preferably 75-98%, more preferably 80-95%, still more preferably 85-92%. When the compression elastic modulus is within the above range, the adhesion to the notch portion is improved, and deformation of the polishing pad is prevented in the polishing process in which the main surface of the workpiece and the main surface of the polishing pad are brought into contact so as to be substantially perpendicular to each other. tend to be more suppressed. The compression modulus can be measured by the method described in Examples. Also, the compression modulus can be adjusted depending on the type of resin used.

The thickness of the polishing pad of this embodiment is preferably 2 to 7 mm, more preferably 3 to 6 mm, still more preferably 4 to 5 mm. The thickness of the polishing pad can be appropriately adjusted to suit the notches to be polished.

Unless otherwise specified, the above physical properties were measured after leaving the sample in an environment of 20±2° C. temperature and 65±5% relative humidity for 24 hours. In addition, since the polishing pad has a uniform structure of the polishing portion and other portions, and the polishing portion gradually becomes the polishing portion due to wear, instead of the polishing portion, the portion closer to the center than the polishing portion is used for various measurements. can be adopted.

[Method for producing polishing pad]
In the method for producing the polishing pad of the present embodiment, a plurality of fleece sheets having fibers oriented in the in-plane direction of the fleece are laminated and the fibers are entangled to form a non-woven fabric in which the fibers are oriented in the in-plane direction of the main surface of the non-woven fabric. An impregnation step of impregnating the nonwoven fabric with a water-based resin dispersion, a drying step of drying the impregnated water-based resin dispersion to obtain a resin-impregnated nonwoven fabric, and a resin-impregnated nonwoven fabric obtained in a circular or circular shape. A cutting step of cutting into a ring shape, and a polishing portion forming step of forming a polishing portion for polishing a notch portion formed on the outer peripheral edge of the work on the outer circumference of the cut resin-impregnated nonwoven fabric.

[Nonwoven fabric manufacturing process]
The nonwoven fabric manufacturing process is a process of laminating a plurality of fleece sheets with fibers oriented in the horizontal direction and entangling the fibers to fabricate a nonwoven fabric in which the fibers are oriented in the in-plane direction of the main surface of the nonwoven fabric. Here, the horizontal direction and the in-plane direction are parallel.

The production of nonwoven fabrics can be divided into fleece formation and the bonding of fleece fibers. The method of forming the fleece is not particularly limited, and examples thereof include dry methods, wet methods, spunbond methods, meltblown methods, and airlaid methods. The method for bonding the fleece fibers is not particularly limited, but examples thereof include a chemical bond method (immersion method, spray method), a thermal bond method, a needle punch method, a hydroentanglement method (water jet method), and the like. Each of these methods can be arbitrarily combined. For example, a fleece having aligned fiber directions is formed by a dry method, a plurality of sheets of the obtained fleece are laminated, and the fibers are entangled by needle punching to form a nonwoven fabric. can be made.

In the non-woven fabric manufacturing process, it is preferable that the length direction of the fibers is aligned horizontally and that the fiber orientation is maintained even during entangling. As a method for aligning the length direction of the fibers in the horizontal direction, there is a method in which the basis weight of the fleece is lightened and the number of laminated sheets is increased. As an example, when a dry method is used, raw cotton chips or lumpy cotton are pre-spreaded into small lumps by a cotton blender. Next, the pre-opened fibers are supplied to a carding machine, and the fibers are opened by the carding machine to form a fleece having a desired basis weight. By laminating many layers of the fleece obtained in this way, there tends to be more fibers oriented in the horizontal direction.

Moreover, as a method for maintaining the fiber orientation after entangling, there is a method of adjusting the entangling conditions. As an example, when forming a nonwoven fabric by entangling it with a needle punch, the smaller the number of punches (density), the less the entangled streaks (the part where the fibers are oriented in the thickness direction of the nonwoven fabric) generated in the part where the needles pass. be. On the other hand, the higher the punching number (density), the less likely the fiber orientation will be disturbed when impregnated with a resin, and the more the fiber orientation can be adjusted within a predetermined range when used as a polishing pad.

[Impregnation process]
The impregnation step is a step of impregnating the nonwoven fabric obtained as described above with a water-based resin dispersion (emulsion). As a specific method, for example, after the nonwoven fabric is fully immersed in the water-based resin dispersion, excess water-based resin dispersion is squeezed off from the nonwoven fabric using a mangle roller or the like to adjust the amount of resin adhered. The water-based resin dispersion contains a resin and water, and if necessary, may contain other additives. As the resin, those mentioned above can be used. The term "aqueous resin dispersion" means that the dispersion medium is water. The water-based resin dispersion may contain a water-soluble organic solvent, if necessary.

The water-based resin dispersion is not particularly limited as long as it contains the resin described above. Among these, a resin emulsion is preferable, and an emulsion of a water-based polyurethane resin is more preferable. Such a water-based resin dispersion tends to have a lower viscosity than a solvent-based resin even at a high concentration. Therefore, even when the nonwoven fabric is impregnated with a large amount of resin, the resin can be impregnated without disturbing the direction of the fibers.

The content of the resin in the aqueous resin dispersion is preferably 10 to 50% by mass, more preferably 15 to 45% by mass, and still more preferably 20 to 40% by mass, relative to the total amount of the aqueous resin dispersion. is. By using an aqueous resin dispersion having a resin content within the above range, there is a tendency to obtain a resin-impregnated nonwoven fabric impregnated with a relatively large amount of resin.

[Drying process]
The drying step is a step of drying the impregnated water-based resin dispersion to obtain a resin-impregnated nonwoven fabric. Thereby, a resin-impregnated nonwoven fabric can be obtained without generating microporous.

[Cutting process]
The cutting step is a step of cutting the resin-impregnated nonwoven fabric that has undergone the drying step into a circular shape or an annular shape (doughnut-shaped disk shape).

[Polishing part forming process]
The polishing portion forming step is a step of forming a polishing portion for polishing a notch portion formed on the outer peripheral edge of the work. A polishing section for polishing a notch formed on the outer peripheral edge of a workpiece is formed on the outer circumference of the resin-impregnated nonwoven fabric cut into a circular or annular shape (doughnut-shaped disc). Examples of the method for forming the polished portion include cutting.

[Method for producing polished product]
The method for manufacturing a polished product according to the present embodiment includes a polishing step of polishing the notch formed in the outer peripheral edge of the workpiece using the polishing pad. The work is not particularly limited as long as it has a notch. Further, as a polishing method, as shown in FIG. 1, there is a method in which the main surface of the workpiece and the main surface of the polishing pad are brought into contact so as to be substantially perpendicular to each other. In addition to the above-described polishing process, the method for manufacturing a polished product according to the present embodiment includes the above-described polishing pad or another polishing pad having the main surface thereof as a contact surface, and using the polishing pad to polish the main surface of the workpiece. It may have another polishing step for polishing.

A slurry may be used in the polishing step. Components contained in the slurry include, for example, polishing particles (abrasive grains) used in chemical mechanical polishing, pure water, and additives. Examples of additives include, but are not limited to, acids, alkalis, surfactants, oxidizing agents, and reaction inhibitors.

Surfactants include, but are not limited to, nonionic surfactants and anionic surfactants.

Examples of the oxidizing agent include, but are not particularly limited to, hydrogen peroxide.

Moreover, the slurry may contain other additives as needed. Examples of such additives include carboxylic acid esters, carboxylic acid amides and carboxylic acids.

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.

[Shore A hardness]
Measure the Shore A hardness of the polishing pad from the depth of indentation after 30 seconds of pressing the indentor (probe) against the test piece surface (main surface) of a polishing pad with a thickness of 4.5 mm or more via a spring. did. A durometer type A was used as a measuring device. This was repeated three times, and the Shore A hardness was obtained from the arithmetic mean. When the test piece had a thickness of less than 4.5 mm, a plurality of test pieces were stacked so as to have a thickness of 4.5 mm or more.

[Compression ratio]
The compressibility of the polishing pad was measured according to Japanese Industrial Standards (JIS L 1021) using a Shopper-type thickness gauge (pressure surface: circular with a diameter of 1 cm). Specifically, the thickness t ₀ was measured after pressing for 30 seconds with the initial load, and then the thickness t ₁ after standing under the final pressure for 5 minutes was measured. From these, the compressibility was calculated by the following formula. At this time, the initial load was 100 g/cm ² and the final load was 1120 g/cm ² .
Compression ratio (%)=(t ₀ -t ₁ )/t ₀ ×100

[Compression modulus]
The compression elastic modulus of the polishing pad was measured in accordance with Japanese Industrial Standards (JIS L 1021) using a Shopper-type thickness gauge (pressure surface: circular with a diameter of 1 cm). Specifically, the thickness t ₀ after pressing for 30 seconds under the initial load was measured, and then the thickness t ₁ after standing for 5 minutes under the final load was measured. After removing all the load and leaving it for 5 minutes, the thickness t ₀ ' was measured after pressing again with the initial load for 30 seconds. From these, the compression elastic modulus was calculated by the following formula. At this time, the initial load was 100 g/cm ² and the final load was 1120 g/cm ² .
Compressive modulus (%) = (t ₀ '-t ₁ )/(t ₀ -t ₁ ) x 100

〔thickness〕
The thickness of the polishing pad was measured according to Japanese Industrial Standards (JIS K 6505) using a Shopper-type thickness gauge (pressure surface: circular with a diameter of 1 cm). Specifically, three sample pieces of 10 cm × 10 cm were prepared by cutting out a polishing pad, and after each sample piece was set at a predetermined position of a thickness measuring instrument, a pressure surface was applied with a load of 480 g/cm ² . It was placed on the surface of the sample piece, and the thickness was measured after 5 seconds. The thickness of each sample piece was measured at 5 points, the arithmetic average was calculated, and the arithmetic average of the 3 sample pieces was calculated. If it is difficult to obtain a 10 cm x 10 cm sample piece due to the size of the polishing pad, the thickness of the polishing pad may be determined by measuring the thickness at 15 points in the polishing pad and calculating the arithmetic average.

〔density〕
The density of the polishing pad was measured according to Japanese Industrial Standards (JIS K 6505). Specifically, prepare a sample piece similar to that used in the thickness measurement, measure the mass with an automatic balance, calculate the density by the following formula, and obtain the arithmetic mean of the three sample pieces. was taken as the density of the polishing pad. If it is difficult to obtain a sample piece of 10 cm x 10 cm due to the size of the polishing pad, prepare three sample pieces of a size that can be collected, calculate the density from the mass and volume of the sample, and calculate the phase of the three pieces. An arithmetic mean may be obtained as the density of the polishing pad.
Density (g/cm ³ )=mass (g)/(10 (cm)×10 (cm)×thickness of sample piece (cm))

[Confirmation of fiber orientation ratio]
A sample was prepared by cutting the polishing pad obtained in the example or the comparative example to expose the cross section of the polishing pad. A cross section of the obtained polishing pad was photographed with a scanning electron microscope (product name “JCM-5700”, manufactured by JEOL Ltd.), and based on the obtained image data, the surface of the polishing pad and the horizontal direction The ratio of fibers oriented within ±30° was confirmed. Specifically, the total number of fibers that can be seen in a 100x SEM cross-sectional photograph (excluding those whose cut surface is only the cross section of the fiber and the direction of the fiber cannot be seen) and the direction horizontal to the surface of the polishing pad The number of fibers oriented within ±30° was counted, and the ratio of the number of fibers oriented within ±30° with respect to the direction horizontal to the surface of the polishing pad to the total number was calculated. This calculation operation was measured at three points, and the fiber orientation was represented by the arithmetic mean.

[Friction wear test]
Using a friction and wear tester (product name: "Friction and Wear Tester 154D", manufactured by Imoto Seisakusho Co., Ltd.), a friction and wear test was performed under the following conditions. As test pieces, the polishing pads obtained in Examples or Comparative Examples were cut in a plane parallel to the central axis of the circle, and three samples were prepared by exposing the cross sections. I used the one that was pasted together so that the A test piece was placed in a friction wear tester so that the exposed cross section and the sandpaper were in contact with each other, and the test was performed. In the evaluation of the friction and wear test, the scraping amount of the cross section of the test piece was weighed under the following conditions, and the wear resistance was evaluated based thereon. In this case, the smaller the scraped amount, the better the wear resistance. In addition, the evaluation of the example was represented by a relative value when the scraping amount of the comparative example was set to 100.
Flow rate: 50mL/min
Sandpaper count: #240
Pressure: 296g/ ^cm2
Time: 10min
Rotation speed: 60rpm

[Example 1]
A non-woven fabric made of polyethylene terephthalate fibers (fineness 3.3 dtex, average fiber length 51 mm) is passed through a cotton blending machine with polyethylene terephthalate raw cotton, and then carded (carded) to form a fleece to adjust the direction of the fibers. It was produced by laminating and entangling fibers with a needle punch. In the obtained nonwoven fabric, the ratio of fibers oriented within ±30° with respect to the in-plane direction of the main surface was 50% or more.

The obtained nonwoven fabric was immersed in a water-based polyurethane resin dispersion (100% modulus 2.0 Mps, product name "Bondic", manufactured by DIC). After the immersion, excess resin dispersion was squeezed out using a pair of mangle rollers capable of applying pressure, and the nonwoven fabric was substantially uniformly impregnated with the resin dispersion. Then, the resin dispersion was dried to obtain a resin-impregnated nonwoven fabric. In addition, in the obtained resin-impregnated nonwoven fabric, the amount of resin per 1 part by mass of the nonwoven fabric was 1.9 parts by mass.

After that, the obtained resin-impregnated nonwoven fabric was cut into a donut-shaped disk shape, and a polishing part was formed on the outer periphery for polishing the notch formed on the outer peripheral edge of the work.

The polishing pad obtained as described above is cut in the thickness direction to form a cross section, and the ratio of fibers oriented within ±30° with respect to the direction horizontal to the surface of the polishing pad. was confirmed to be 73%.

FIG. 3 shows one cross-sectional photograph of the polishing pad of Example 1. As shown in FIG. The horizontal direction of the cross-sectional photograph is the direction parallel to the surface of the polishing pad, and the vertical direction is the thickness direction of the polishing pad. As shown in FIG. 3, when the water-based resin is used, the orientation of the fibers is maintained and the orientation of the fibers becomes anisotropic.

[Example 2]
A polishing pad was obtained in the same manner as in Example 1, except that the amount of resin per 1 part by mass of the nonwoven fabric was 1.5 parts by mass. The obtained polishing pad was cut in the thickness direction to form a cross section, and the ratio of fibers oriented within ±30° with respect to the direction horizontal to the surface of the polishing pad was confirmed. %Met.

[Comparative Example 1]
The nonwoven fabric obtained in Example 1 was immersed in a resin solution containing a wet polyurethane resin (100% modulus 12 Mps, product name "Crisbon", manufactured by DIC) and N,N-dimethylformamide. After the immersion, excess resin solution was squeezed out using a mangle roller capable of applying pressure between a pair of rollers, and the nonwoven fabric was substantially uniformly impregnated with the resin solution. Then, the resin was coagulated and regenerated by immersing it in a coagulating liquid consisting of water at room temperature to obtain a resin-impregnated nonwoven fabric. In addition, in the obtained resin-impregnated nonwoven fabric, the resin amount was 1.3 parts by mass with respect to 1 part by mass of the nonwoven fabric.

After that, the obtained resin-impregnated nonwoven fabric was cut into a donut-shaped disk shape, and a polishing part was formed on the outer periphery for polishing the notch formed on the outer peripheral edge of the work.

The polishing pad obtained as described above is cut in the thickness direction to form a cross section, and the ratio of fibers oriented within ±30° with respect to the direction horizontal to the surface of the polishing pad. was confirmed to be 45%.

FIG. 4 shows one cross-sectional photograph of the polishing pad of Comparative Example 1. As shown in FIG. The horizontal direction of the cross-sectional photograph is the direction parallel to the surface of the polishing pad, and the vertical direction is the thickness direction of the polishing pad. As shown in FIG. 4, when a wet resin is used, it is necessary to increase the resin concentration in order to increase the adhesion amount of the resin. It can be seen that the orientation of the fibers is lost during impregnation, and the orientation of the fibers is further disturbed due to migration, etc., resulting in an isotropic one. The black pores in the resin portion that can be seen in the photograph of FIG. 4 are called microporous, and are pores formed when the wet resin is immersed in the coagulating liquid. The size of this microporous is about 1 to 20 μm, which is different from the voids between fibers.

In Comparative Example 1, a nonwoven fabric having fibers oriented in the in-plane direction of the main surface was used. No fiber was obtained in which the fibers were oriented in a direction parallel to the surface.

*Fiber orientation: The ratio of fibers that are oriented within ±30° with respect to the surface of the polishing pad and the plane in the horizontal direction.

When the polishing rate of the polishing pads was confirmed, all pads had similar polishing rates. In addition, the polishing pads of the examples using water-based polyurethane do not use solvents, so they can be manufactured by a method with less environmental load.

INDUSTRIAL APPLICABILITY The polishing pad of the present invention has industrial applicability as a polishing pad for polishing a notch formed in the outer peripheral edge of a work such as a silicon wafer.

Claims (9)

A circular or ring-shaped polishing pad made of a resin-impregnated nonwoven fabric containing a nonwoven fabric and a resin impregnated in the nonwoven fabric,
having a polishing section on the outer periphery for polishing the notch formed on the outer peripheral edge of the work;
In a cross section obtained by cutting the polishing pad in the thickness direction, the ratio of fibers oriented within ±30° with respect to a direction horizontal to the surface of the polishing pad is 50% or more.
polishing pad. wherein the resin comprises a water-based polyurethane resin;
The polishing pad according to claim 1. the resin does not have microporosity;
The polishing pad according to claim 1 or 2. 100% modulus of the resin is 0.5 to 5.0 MPa,
The polishing pad according to any one of claims 1-3. The surface of the resin-impregnated nonwoven fabric has a Shore A hardness of 60 to 90°.
The polishing pad according to any one of claims 1-4. The resin-impregnated nonwoven fabric has a density of 0.48 to 0.70 g/cm ³ ,
The polishing pad according to any one of claims 1-5. The mass ratio of the resin to the nonwoven fabric of the resin-impregnated nonwoven fabric is 1.35 or more.
The polishing pad according to any one of claims 1-6. A method for producing a polishing pad according to any one of claims 1 to 7,
a nonwoven fabric production step of laminating a plurality of sheets of fleece in which fibers are oriented in the horizontal direction and entangling the fibers to produce a nonwoven fabric in which the fibers are oriented in the in-plane direction of the main surface of the nonwoven fabric;
an impregnation step of impregnating the nonwoven fabric with an aqueous resin dispersion;
a drying step of drying the impregnated water-based resin dispersion to obtain a resin-impregnated nonwoven fabric;
a cutting step of cutting the obtained resin-impregnated nonwoven fabric into a circular shape or an annular shape; and forming a polishing part on the outer periphery of the cut resin-impregnated nonwoven fabric for polishing the notch formed on the outer peripheral edge of the work. a polishing portion forming step;
A method for manufacturing a polishing pad. Using the polishing pad according to any one of claims 1 to 7, a polishing step of polishing a notch formed in the outer peripheral edge of the work,
A method for producing an abrasive product.