KR20160065082A - Holding pad - Google Patents

Abstract

The present invention relates to a holding pad comprising a polyurethane resin sheet having a holding surface for holding an object to be polished, wherein the polyurethane resin sheet has a storage elastic modulus E 'at 40 DEG C of 0.3 to 2.0 MPa, And the absorption amount of the resin sheet is 95 to 200 mg / 50.3 cm < 2 >.

Description

Holding pad {HOLDING PAD}

The present invention relates to a holding pad.

Conventionally, in the case of performing precision surface polishing of a semiconductor wafer, a silicon wafer for a semiconductor device, a substrate for various recording disks, a glass substrate for a liquid crystal display, and particularly a glass substrate, So that the object to be polished is polished by using a polishing pad. The holding pad has a sheet made of an elastic material such as a polyurethane resin having open cells, and fine bubbles on the surface (holding surface) of the sheet serve as a sucker, so that the object to be polished can be held. That is, the sheet functions as a holding layer.

However, since the holding pad is exposed to the polishing liquid (polishing slurry) at the time of polishing, the polishing liquid sometimes penetrates into the open cells existing in the holding layer of the holding pad. Once the polishing liquid enters, the elasticity of the elastic material constituting the holding layer disappears or the holding layer swells, making it difficult to maintain the stable state, and as a result, the polishing performance is deteriorated. As a countermeasure for preventing this, for example, Patent Document 1 discloses a holding pad including a fluorine-based water repellent agent.

Patent Document 1: JP-A-9-254027

When a water repellent agent as described in Patent Document 1 is used, invasion of the polishing liquid into the interior of the holding layer can be suppressed. However, when the holding surface of the holding layer is made wet by using water to adsorb the holding pad to the object to be polished, the affinity with water is lowered due to the presence of the water repellent agent, so that defective adsorption occurs at the water- It gets easier. On the other hand, if the addition amount of the water repellent agent is reduced in order to prevent such poor adhesion, dispersion of the water repellent agent in the oil retention layer occurs, and water invades from the water repellent part. As a result, It is difficult to stably maintain the object to be polished because the skin is worn. Here, the " epidermal wear " is a phenomenon in which the holding surface of the holding layer swells by direct contact with the polishing surface of the polishing pad as a result of the swelling of the holding layer by immersion or the like, or the holding surface contacting with the edge of the polishing subject It means that the edge is cut or formed by the edge portion. This is caused by the swelling of the holding layer, peeling from the polishing head, and partial bending.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a holding pad capable of suppressing both adhesion failure of a polished object and skin abrasion.

The inventors of the present invention have conducted diligent studies in order to achieve the above object, and as a result, they have found that a sheet having a storage elastic modulus E 'at 40 ° C is suitably low and an absorption amount by a specific absorption amount measurement is in a suitable range, The present inventors have found that the above object can be achieved and have completed the present invention.

That is, the present invention is as follows.

[1] A holding pad comprising a polyurethane resin sheet having a holding surface for holding an object to be polished, wherein the polyurethane resin sheet has a storage elastic modulus E 'at a temperature of 40 ° C of 0.3 to 2.0 MPa, And the absorption amount of the resin sheet is 95 to 200 mg / 50.3 cm < 2 >.

[2] The holding pad according to [1], wherein the polyurethane resin sheet has a KEL at 40 ° C of 1.0 × 10 ^{5 to} 5.0 × 10 ⁵ Pa ^-1 .

[3] The holding pad according to [3], wherein the 100% modulus of the resin constituting the polyurethane resin sheet at 25 ° C is 4.0 to 10.0 MPa.

[4] The holding pad, wherein the polyurethane resin sheet contains a water repellent agent.

[5] The holding pad according to any one of [1] to [5], wherein the water repellent agent comprises a fluorinated water repellent having a perfluoroalkyl group having 6 to 8 carbon atoms.

[6] The holding pad, wherein 60 to 100 mol% of the fluorine-based water repellent agent contained in the polyurethane resin sheet is a fluorine-based water repellent agent having a perfluoroalkyl group having 6 carbon atoms.

According to the present invention, it is possible to provide a holding pad capable of suppressing both adhesion failure of a polished object and skin abrasion.

1 is a cross-sectional view schematically showing an example of a holding pad according to the present invention.
Fig. 2 is a perspective view schematically showing a mechanism used for measurement of adsorption amount according to the present invention. Fig.

Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as " present embodiment ") will be described in detail with reference to the drawings as necessary, but the present invention is not limited to the following embodiment. The present invention can be modified in various ways without departing from the gist of the invention. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. In addition, the positional relationships of the up, down, left, and right are based on the positional relationships shown in the drawings unless otherwise specified. In addition, the dimensional ratio in the drawings is not limited to the illustrated ratio.

The holding pad of the present embodiment is a holding pad comprising a polyurethane resin sheet having a holding surface for holding an object to be polished, wherein the polyurethane resin sheet has a storage elastic modulus E 'at 40 캜 of 0.3 to 2.0 MPa, , And the absorption amount of the polyurethane resin sheet is 95 to 200 mg / 50.3 cm < 2 >.

1 is a schematic cross-sectional view showing an example of a holding pad according to the present embodiment. The holding pad 110 includes a polyurethane resin sheet (hereinafter simply referred to as a " resin sheet ") 112 and a substrate 114 laminated in this order. The resin sheet 112 and the base material 114 are bonded to each other. In this example, the resin sheet 112 and the base material 114 are bonded to each other through the adhesive layer 116.

The resin sheet 112 contained in the holding pad 110 contains a polyurethane resin and functions as a holding layer having a holding surface P for holding the object to be polished. The storage elastic modulus E 'of the resin sheet 112 is 0.3 to 2.0 MPa at 40 占 폚. When the storage elastic modulus E 'at 40 캜 is 0.3 MPa or more, it is difficult for the epidermis wear to occur in the resin sheet 112 in the polishing process. On the other hand, when the storage elastic modulus E 'at 40 ° C is 2.0 MPa or less, the adsorption force of the resin sheet 112 to the object to be polished is increased, and the adsorption failure is less likely to occur. From the same viewpoint, the storage elastic modulus E 'of the resin sheet 112 is preferably 0.4 to 1.5 MPa at 40 캜, more preferably 0.5 to 1.0 MPa, and even more preferably 0.5 to 0.7 MPa.

(Method of measuring storage elastic modulus E ') [

In the present specification, the storage elastic modulus E 'of the resin sheet is measured by using a dynamic viscoelasticity measuring apparatus (for example, "RSA III" manufactured by T.A. Instrument Co., Ltd., Japan) under the following conditions, .

[Measuring conditions]

Sample size: 10 mm × 10 mm × thickness 0.8 mm × 3 sheets

ㆍ Test direction: Compression mode

Load: 100 g / cm < 2 >

ㆍ Distortion: 0.10%

ㆍ Frequency: 1 Hz

ㆍ Temperature range: 20 ~ 80 ℃, Temperature rise rate: 5 ℃ / min

ㆍ Sample thickness: Measured by thickness meter

• For samples with different thicknesses, measure them in a stack of 2 mm to 3 mm.

The amount of absorption of the resin sheet 112 is 95 to 200 mg / 50.3 cm2. When the absorption amount is 95 mg / 50.3 cm 2 or more, the adsorption force of the resin sheet 112 to the object to be smoked becomes high, and the adsorption failure is hardly caused. On the other hand, when the adsorption amount is 200 mg / 50.3 cm 2 or less, the skin sheet 112 is hardly worn by the epidermis in the polishing process. From the same viewpoint, the amount of absorption of the resin sheet 112 is preferably 100 to 160 mg / 50.3 cm 2, more preferably 107 to 150 mg / 50.3 cm 2, and even more preferably 110 to 130 mg / 50.3 cm 2.

(Method of measuring absorption amount)

The amount of absorption of the resin sheet 112 is measured as follows. 2 is a perspective view schematically showing a mechanism used for measuring the amount of absorption of a resin sheet. First, a holding pad 110 having a diameter of 125 mm and serving as a sample 10 to be measured and a butt welded flange 20 made of vinyl chloride and a plate flange 30 made of vinyl chloride (both of which are JIS 10K-80A ). The flanges 20 and 30 have an inner diameter? Of 80 mm (cross-sectional area of 50.3 cm2). Next, the sample 10 is dried in a drier at 40 DEG C for 10 hours or more. Thereafter, the operation is performed in an atmospheric environment at a room temperature of 20 DEG C and a relative humidity of 50%. Subsequently, the sample 10 is naturally cooled to room temperature in an atmospheric atmosphere, and its mass is measured by an electronic balance. Next, as shown in Fig. 2, the sample 10 is placed between the butt weld flange 20 and the plate flange 30 with its holding surface P as the butt welded flange 20 side And fastened from above and below. Subsequently, 300 mL of ion-exchanged water (W) at 20 캜 is injected into the tube of the butt welded flange 20 (the height of the water surface from the holding surface P of the sample 10 at this time is about 60 mm .). After the injection, they are allowed to stand for 8 hours, then the sample 10 is opened from the fixation, and the surface moisture is absorbed by the filter paper. At this time, water is absorbed by pressing the surface of the sample 10 without pressing the filter paper 10 against the sample 10. Then, the mass of the sample 10 is measured quickly. The mass difference of the sample 10 before and after the ion exchange water W is injected and set is taken as the absorption amount of the resin sheet 112.

As a method for controlling the resin sheet 112 according to the present embodiment to have the storage elastic modulus E 'and the absorption amount in the above-mentioned range, for example, a method of controlling the resin constituting the resin sheet 112 at 100% modulus at 25 DEG C, The kind of the water repellent agent, the type and amount of the water repellent agent, the thickness and the density of the resin sheet 112, and the amount of the back side of the resin sheet 112 opposite to the skin layer .

The 100% modulus of the resin constituting the resin sheet 112 at 25 캜 is preferably 4.0 to 10.0 MPa, more preferably 5.0 to 9.0 MPa, and even more preferably 5.0 to 7.0 MPa. When the 100% modulus is 4.0 MPa or more, the storage elastic modulus E 'of the resin sheet 112 tends to be 0.3 MPa or more, and the storage elastic modulus E' of the resin sheet 112 is 2.0 MPa or less . In the present specification, the 100% modulus is a value obtained when the non-foamed resin sheet (test piece) using the same material as the resin sheet 112 is increased by 100% under the environment of room temperature 23 ± 2 ° C, The tensile strength at doubling is divided by the initial cross-sectional area of the specimen.

KEL at 40 ℃ of resin sheets ^{112, 1.0 × 10 5 ~5.0 × 10} 5 Pa -1 , and ^{is, 1.5 × 10 5 ~4.0 × 10} 5 Pa -1 , and more preferred is, 2.0 × 10 ⁵ preferably To 3.0 x 10 < ⁵ > Pa < ^{-1 &} gt ;. When the KEL is 1.0 x 10 < ⁵ > Pa < ^-1 > or more, the resin sheet 112 is easily deformed, and the retention and adsorption of the polished product can be enhanced. In addition, deviation in the in-plane direction of the object to be polished hardly occurs at the time of polishing. On the other hand, when the KEL is 5.0 × 10 ⁵ Pa ^-1 or less, the amount of deformation of the resin sheet 112 is reduced (ie, the amount of resin sheet 112 lost during polishing is reduced) And the life of the holding pad 110 can be made longer.

(Calculation method of KEL)

In the present specification, the KEL (energy loss factor) is calculated from the storage elastic modulus E 'and the loss elastic modulus E "at 40 ° C measured under the same conditions as the" method of measuring the storage elastic modulus E' 1b.

KEL = tan? 10 ¹² / (E '(1 + tan? ² )) (1a)

tan? = E "/ E ' (1b)

The density (bulk density) of the resin sheet 112 according to the present embodiment is preferably 0.15 to 0.30 g / cm < 2 > at 25 deg. When the density is 0.15 g / cm 2 or more, permanent distortion of the resin sheet 112 hardly occurs, and when the density is 0.30 g / cm 2 or less, it is easy to keep the object to be smoothed more uniformly throughout the resin sheet 112 Loses. As a result, when the density of the resin sheet 112 is in the above-mentioned range, it is more preferable that the object to be polished is shifted in the in-plane direction with respect to the holding pad 110 at the time of polishing or unevenness in polishing occurs during polishing .

The thickness of the resin sheet 112 is not particularly limited, but may be, for example, 0.2 to 1.5 mm or 0.6 to 1.2 mm. The thickness of the resin sheet 112 is measured in accordance with the measuring method described in JIS K 6550 (1994). That is, it is the thickness when a load of 100 g per 1 cm 2 is applied (loaded) as the initial load in the thickness direction of the resin sheet 112.

The resin sheet 112 has a plurality of bubbles (not shown) in a material constituting a matrix such as a resin (hereinafter referred to as " matrix material ") and may be formed by a wet film- May be formed by a molding method, but it is preferably formed by a wet film forming method from the viewpoint of achieving the object of the present invention more effectively and reliably. When the resin sheet 112 is formed by the wet film forming method, it may have a skin layer on the side of the holding surface P where fine micropores not shown are formed. The surface of the skin layer has a fine flatness. On the other hand, on the inner side of the skin layer (the inside of the resin sheet 112), a void having a triangular cross-section with a hole diameter larger than the micropores of the skin layer and rounded along the thickness direction of the resin sheet 112 (open cell; (Not shown) may be formed. The void may be formed so that the size on the holding surface (P) side is smaller than the size on the side opposite to the holding surface (P). The resin sheet 112 may have holes (not shown) having a size larger than the micropores of the skin layer and smaller than the voids. The micropores, voids and small-size holes of the skin layer may be connected to each other through a communication hole and mesh-like.

The matrix material constituting the resin sheet 112 is not particularly limited as long as it is a composition containing most of the polyurethane resin. For example, the resin sheet 112 may have a polyurethane resin in an amount of 80 to 100 % By mass. More preferably, the resin sheet 112 contains 85 to 100 mass%, more preferably 90 to 100 mass%, and particularly preferably 90 to 95 mass% of a polyurethane resin based on the total amount thereof do.

As the polyurethane resin, for example, a polyester-based polyurethane resin, a polyether-based polyurethane resin and a polycarbonate-based polyurethane resin can be cited. These resins are used singly or in combination of two or more. Of these, polyester-based polyurethane resins are preferable from the viewpoint of more effectively and reliably showing the object of the present invention.

The polyurethane resin may be synthesized by a conventional method, or a commercially available product may be obtained. Commercially available products include, for example, Chrisborn (trade name by DIC Corporation), Sanfren (trade name by Sanyo Chemical Industries, Ltd.), and Rezamin (trade name by Dainichi Chemical Industry Co., Ltd.). The polyurethane resin may be used singly or in combination of two or more.

The resin sheet 112 may contain other resins such as a polysulfone resin and / or a polyimide resin in addition to the polyurethane resin. The polysulfone resin may be synthesized by a usual method or a commercially available product may be obtained. Commercially available products include, for example, Yudel (trade name, manufactured by Solvay Advanced Polymers Co., Ltd.). The polyimide resin may be synthesized by a conventional method, or a commercially available product may be obtained. Commercially available products include, for example, olam (trade name, manufactured by Mitsui Chemicals).

The resin sheet 112 preferably contains a water repellent agent in addition to the matrix material. Examples of the water repellent agent include a fluorine-based water repellent agent, a silicone-based water repellent agent, and a hydrocarbon-based water repellent agent. Among these, a fluorine-based water repellent agent is preferable from the viewpoint of achieving the object of the present invention more effectively and reliably. The water repellent agent may be used alone or in combination of two or more.

Examples of the fluorine-based water repellent agent include a compound having a perfluoroalkyl group (a fluorine-based water repellent agent), and a fluorine telomer represented by the following formula (2) is preferably used.

Rf-R-X (2)

Here, Rf represents a perfluoroalkyl group, and the number of carbon atoms thereof is 3 to 8, preferably 4 to 8, more preferably 6 to 8, and particularly preferably 6. R represents an alkylene group having 2 to 6 carbon atoms, preferably 2 to 4 carbon atoms, and particularly preferably 2 carbon atoms. X represents a functional group, and examples thereof include a hydroxyl group, CH ₂ ═CHC (═O) CO-, H (OCH ₂ CH ₂ ) _x O-, YSO ₃ - [Y represents a hydrogen atom or NH ₄ ] And is preferably a hydroxyl group. As the compound having a perfluoroalkyl group, a compound obtained by modifying a resin with a perfluoroalkyl group is also exemplified. As the resin, a resin capable of forming a resin sheet of the holding pad, for example, a polyurethane resin can be mentioned from the viewpoint of improving the dispersibility and the time-lapse stability of the resin sheet. As a modification method, for example, And / or introducing a perfluoroalkyl group into the side chain. The compounds having a perfluoroalkyl group may be used singly or in combination of two or more.

Of the fluoroteromers, the number of carbon atoms of Rf is preferably 6, and the number of carbon atoms of R is preferably 2 from the viewpoint of achieving the object of the present invention more effectively and securely. In consideration of the dispersibility and the time-course stability of the resin sheet, it is also possible to use a compound obtained by modifying the resin with a perfluoroalkyl group and introducing a fluoroteromer into the resin, for example, a compound having Rf-R- Is preferable, and a polyurethane resin having a group represented by Rf-R- in the above formula (2) is more preferable. Examples of such resins include the polyurethane resins described in International Publication No. 2012/172936.

The fluoroteromer may be synthesized by a conventional method, or a commercially available product may be obtained. As commercially available products, there are commercially available products such as, for example, Chrisborn Sister SD series (manufactured by DIC Corporation), Asahi Guard E series (trade name, manufactured by AGC Seiyaku Chemical Co., Ltd.), NK Guard S series Trade name, manufactured by Kin Kogyo Co., Ltd.). The fluoroteromers may be used singly or in combination of two or more.

The content of the water repellent agent in the resin sheet 112 is preferably 2 to 14 parts by mass, more preferably 3 to 13 parts by mass, relative to 30 parts by mass of the resin constituting the resin sheet 112. When the content of the water repellent agent is 2 parts by mass or more based on 30 parts by mass of the resin, the amount of water absorption tends to be 200 mg / 50.3 cm 2 or less, and localization of the water repellent agent can be prevented, It becomes. Further, when the content of the water repellent agent is 14 parts by mass or less based on 30 parts by mass of the resin, the amount of water absorption tends to be 95 mg / 50.3 cm 2 or more. In the case of producing the resin sheet 112 through the coagulation regeneration step in the manufacturing method of the holding pad 110, which will be described later, and when a water repellent agent is contained in the resin solution in the former stage prior to the coagulation regeneration step, And as a result, the unevenness of the film formation of the resin sheet 112 can be further suppressed.

When the fluorine-based water repellent agent such as fluorine-based water repellent is used as the water repellent agent and the fluorine-based water repellent agent having the Rf carbon number of 6 is contained, 60 to 100 mol% of the fluorine-based water repellent agent contained in the resin sheet 112, Based water repellent having Rf of carbon number 6 is preferable. This limits a compound containing a small amount of fluorine atoms, such as a compound containing a large amount of fluorine atoms such as a fluorine telomer having Rf having a carbon number of more than 6, or a fluorine telomer having an Rf having a carbon number of less than 6. As a result, the content of the compound containing a large amount of fluorine atoms can be reduced, whereby the decrease in the amount of water absorption and the defective adsorption can be suppressed more effectively, the content of the compound containing less fluorine atoms can be reduced, .

In addition to the resin and optional water repellent agent, the resin sheet 112 may be formed of a material commonly used for a resin sheet of a holding pad such as a pigment such as carbon black, a hydrophilic additive and a hydrophobic additive One or two or more of them may be included. Further, various materials such as a solvent used in the manufacturing process of the resin sheet 112 may remain in the resin sheet 112 within a range that does not hinder the problem of the present invention.

Fine pores may be present on the holding surface P of the resin sheet 112. [ The fine pores can be formed, for example, by adding an additive for forming micropores to the holding surface (skin layer) at the time of forming the resin sheet 112.

The base material 114 provided on the holding pad 110 is for supporting the resin sheet 112 and is not particularly limited and may be included as a base material on a conventional holding pad and specifically includes polyethylene terephthalate (Hereinafter referred to as " PET ") film.

Further, the adhesive layer 116 may include an adhesive or a pressure-sensitive adhesive that is used in a conventionally known holding pad. Examples of the material of the adhesive layer 116 include various thermoplastic adhesives such as acrylic, nitrile, nitrile rubber, polyamide, polyurethane, and polyester.

The base material 114 and the adhesive layer 116 in the holding pad 110 may be derived from a double-sided tape having them. The double-sided tape has an adhesive layer containing an adhesive or a pressure-sensitive adhesive on both sides of the base material 114, and one of the adhesive layers corresponds to the adhesive layer 116. And the other adhesive layer is for bonding the holding pads 110 to the holding base plate of the polishing machine. The double-sided tape may be included in a conventional holding pad or may have a release paper not shown on the opposite side of the base material 114. [

Next, an example of a manufacturing method of the holding pad according to the present embodiment will be described. Here, the case of manufacturing the resin sheet 112 by the wet film forming method will be described, but the manufacturing method of the resin sheet 112 is not limited to this. This manufacturing method has a step of preparing a resin sheet 112 and a step of bonding the base material 114 to the resin sheet 112 to obtain the holding pad 110. [

The step of preparing the resin sheet 112 may further include a step of preparing a resin solution containing a resin, a solvent and, if necessary, a water repellent agent (a resin solution preparation step), a step of applying the resin solution to the surface of the substrate for film formation A step of removing the solvent from the precursor sheet to obtain a resin sheet 112 (a solvent removing step); and a step of removing the solvent from the precursor sheet (solvent removing step) (Grinding / removing step) of grinding and / or removing part of the grinding wheel 112 by a buffing process or a slicing process. Hereinafter, each process will be described.

First, in the resin solution preparing step, a resin such as the above-mentioned polyurethane resin, a solvent capable of dissolving the resin and capable of being mixed with a coagulating liquid to be described later, and a water repellent agent included in the resin sheet 112, (For example, a pigment, a hydrophilic additive and a hydrophobic additive) are mixed, and if necessary, the resin solution is prepared by defoaming under reduced pressure. The solvent is not particularly limited, and examples thereof include N, N-dimethylformamide (hereinafter referred to as "DMF") and N, N-dimethylacetamide. The content of the resin with respect to the total amount of the resin solution is not particularly limited, but may be, for example, in the range of 10 to 50 mass%, or 15 to 35 mass%.

Next, in the coating step, the resin solution is coated on the surface of the band-shaped film-forming base material, preferably at room temperature, using a coating device such as a knife coater to form a coating film. The thickness of the resin solution applied may be appropriately adjusted so that the thickness of the resin sheet 112 finally obtained becomes a desired thickness. As a material of the substrate for film formation, for example, a resin film such as a PET film, a fabric, and a nonwoven fabric. Among these, a resin film such as a PET film which is difficult to infiltrate the liquid is preferable.

Subsequently, in the coagulating and regenerating step, the coating film of the resin solution applied to the substrate for film formation is continuously guided into a coagulating solution mainly composed of a poor solvent for the resin (for example, water in the case of a polyurethane resin). In the coagulating solution, an organic solvent such as a polar solvent other than the solvent in the resin solution may be added to adjust the regeneration speed of the resin. The temperature of the coagulating liquid is not particularly limited as long as it can coagulate the resin, and may be, for example, 15 to 65 캜. In the coagulating solution, first, a film (skin layer) is formed at the interface between the coating film of the resin solution and the coagulating solution, and innumerable dense micropores are formed in the resin closest to the coating film. Thereafter, the regeneration of the resin having an open-cell structure is preferably proceeded by the phenomenon of coalescence of the diffusion of the solvent contained in the resin solution into the coagulating solution and the penetration of the poor solvent into the resin. At this time, if the substrate for film formation is difficult to penetrate the liquid (for example, a PET film), since the coagulating solution does not penetrate the substrate, substitution of the solvent and the poor solvent in the resin solution occurs preferentially in the vicinity of the skin layer, There is a tendency that a larger void is formed on the inner side of the layer than in the vicinity of the layer. Thus, a precursor sheet is formed on the substrate for film formation.

When the resin solution contains a water repellent agent, if the content of the water repellent agent is 14 parts by mass or less based on 30 parts by mass of the resin, it is possible to further suppress the solidification unevenness that may be caused by interference between the water repellent and the coagulating solution. It is possible to further prevent film unevenness of the sheet 112.

Next, in the solvent removal step, the solvent remaining in the formed precursor sheet is removed to obtain a resin sheet 112. For the removal of the solvent, conventionally known cleaning liquids can be used. Further, the resin sheet 112 after removal of the solvent may be dried if necessary. For drying the resin sheet 112, for example, a cylinder dryer provided with a cylinder having a heat source inside can be used, but the drying method is not limited thereto. When a cylinder dryer is used, the precursor sheet is dried by passing along the circumferential surface of the cylinder. The obtained resin sheet 112 may be rolled up.

Then, in the grinding / removing step, at least one of the main surface of the resin sheet 112 on the side of the skin layer and the reverse side of the resin sheet 112 is ground and / or partially removed by a buffing treatment or a slicing treatment. Since the thickness of the resin sheet 112 can be uniformized by the buffing treatment or the slicing treatment, the pressing force against the object to be polished is further equalized, the damage of the object to be polished is further suppressed and the flatness of the object to be polished is improved . Since the main surface on the skin layer side is the surface which becomes the holding surface P in the resin sheet 112, it is preferable to grind the back surface to improve the polishing uniformity of the object to be polished.

Next, the base material 114 is bonded to the resin sheet 112 to obtain the holding pad 110. In this step, a base material 114 is bonded to a surface of the resin sheet 112 opposite to the holding surface P via the adhesive layer 116, for example, using a double-faced tape having the base material 114 and the adhesive layer 116 . The other adhesive layer and peeling paper of the double-faced tape may be provided on the side of the base material 114 opposite to the adhesive layer 116. [ Thus, the holding pad 110 can be obtained.

Next, a method of polishing using the holding pad 110 of the present embodiment will be described. Examples of the object to be polished in the polishing process include, but are not limited to, semiconductors, silicon wafers for semiconductor devices, substrates for various recording disks, and glass substrates for liquid crystal displays. Among these, from the viewpoint of more effectively and reliably showing the effect of the present invention, the object to be polished is preferably a glass substrate.

In the polishing process, first, the holding pad 110 is attached to the object to be polished of the polishing machine, and the object to be polished is held by the holding pad 110. To attach the holding pad 110 to the object to be polished, the release paper of the double-faced tape is removed as necessary, and the object P is adhered and fixed to the object to be polished so that the holding surface P faces downward (or upward) . Alternatively, when the holding pad 110 does not have a double-sided tape, the holding pad 110 is adhered and fixed to the object to be polished with an adhesive or a pressure sensitive adhesive separately prepared. Next, an appropriate amount of water is contained on the holding surface P of the resin sheet 112 to press the object to be polished, so that the object to be polished is pushed through the holding pad 110 by the surface tension of the water and the tackiness of the resin sheet 112 And held in the object holder. At this time, the surface to be polished (processed surface) of the object to be polished faces downward (or upward). On the other hand, a polishing pad (polishing cloth) is mounted on the surface of the polishing platen disposed on the lower side (or the upper side) of the object to be polished so as to face the object to be polished, with the polishing surface facing the upper side (or lower side).

Next, the object to be polished is moved toward the polishing platen so that the polished surface of the object to be polished comes into contact with the polishing surface of the polishing pad, and the object to be polished is returned. And, between the operand evil and the polishing pad, abrasive grains; and supplies (the abrasive particles for example SiO _2, CeO ₂₎ and hydrogen peroxide circulating the abrasive slurry including the chemical composition of the oxidizing agent and so on, represented by. At the same time, the object to be polished is polished by CMP on the polishing pad by rotating the object to be polished and the polishing platen while pressing the object to be polished to the polishing pad side with the object holder.

In the present embodiment, by setting the storage elastic modulus E 'of the resin sheet 112 at 40 ° C to 0.3 to 2.0 MPa and the absorption amount of the resin sheet 112 to 95 to 200 mg / 50.3 cm 2, Both adsorption failure of water and skin abrasion can be suppressed. When the storage elastic modulus E 'at 40 캜 is 0.3 MPa or more, it is difficult for the epidermis wear to occur in the resin sheet 112 in the polishing process. On the other hand, when the storage elastic modulus E 'at 40 ° C is 2.0 MPa or less, the adsorption force of the resin sheet 112 to the object to be polished is increased, and the adsorption failure is less likely to occur. Further, when the amount of absorption is 95 mg / 50.3 cm 2 or more, the adsorption force of the resin sheet 112 to the object to be smoked becomes high, and the adsorption failure becomes difficult to occur. On the other hand, when the adsorption amount is 200 mg / 50.3 cm 2 or less, the skin sheet 112 is hardly worn by the epidermis in the polishing process. The occurrence of skin abrasion is prevented to prevent damage to the holding surface P, and consequently, the life of the holding pad 110 is extended.

Although the present embodiment has been described in detail above, the present invention is not limited to the above embodiment. For example, in the present embodiment, the adhesive layer 116 is used for bonding the resin sheet 112 and the base material 114, but the bonding is not limited to the use of the adhesive layer 116. Furthermore, the holding pad of the present invention does not need to have a base material, but it is preferable to provide the base material from the viewpoint of handling property of the holding pad. The grinding / removing step may be omitted in the manufacturing method of the holding pad. In addition, in the manufacturing method of the holding pad, a water repellent agent may be contained in the resin sheet, instead of or in addition to the resin solution, by applying a water repellent agent to the resin sheet thus obtained and then drying the resin sheet if necessary. Examples of the method of applying the water repellent agent include a dip method and a spray method.

Example

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

(Example 1)

To 100 parts by mass of a 30% DMF solution of a polyester-based polyurethane resin having 6.0 MPa of a 100% modulus of a raw material resin (at 25 캜), 50 parts by mass of DMF, 8 parts by mass of water, And 3 parts by mass of " Crisbon ASSISTER SD-38 " (trade name) manufactured by DIC Co., Ltd., containing perfluorohexyl compound were added and mixed and stirred to prepare a resin solution. Next, a PET film was prepared as a film-forming substrate, and the resin solution was coated thereon using a knife coater to obtain a coating film having a thickness of 1.0 mm. Examples of the polyester-based polyurethane resin include a polyester polyol obtained by dehydrating condensation of ethylene glycol and propylene glycol with adipic acid, methylene bis (4,1-phenylene) = diisocyanate (MDI) and a low- (The same also in the following Examples and Comparative Examples).

Subsequently, the obtained coating film was immersed in a coagulating bath of 18 DEG C comprising water as a coagulating liquid together with the substrate for film formation, and the resin was coagulated and regenerated to obtain a precursor sheet. After removing the precursor sheet from the coagulating bath and peeling the substrate for film formation from the precursor sheet, the precursor sheet was immersed in a cleaning liquid (desolvating bath) made of water at room temperature to remove the solvent DMF to obtain a resin sheet. Thereafter, the resin sheet was wound while being dried. Next, the back surface of the resin sheet (the surface on the side where the film forming base material was peeled off and which was in contact with the film base material) was buffed to a thickness of 0.8 mm.

Next, a double-sided tape having an adhesive layer (material: acrylic resin) on both surfaces of the PET substrate and having a release paper on one surface is bonded to the surface of the resin sheet subjected to the buffing treatment with an adhesive layer on the opposite side of the release paper , And cut into a circle having an outer diameter of 33.5 cm to obtain a holding pad.

The storage elastic modulus E 'of the resin sheet provided at the holding pad at 40 ° C is referred to as the "method of measuring the storage elastic modulus E'", the absorption amount is referred to as the "method of measuring the absorption amount", the KEL at 40 ° C is calculated by the " Quot ;, respectively. In the measuring method of the storage elastic moduli E 'and KEL, the product name "RSA III" manufactured by T.A. Instrument Co., Ltd. was used as the dynamic viscoelasticity measuring device.

(Measurement of adsorption force)

The holding pad was cut out into a square of about 100 mm x 100 mm. A glass substrate having a diameter of 60 mm and a thickness of about 1 mm was prepared as an object to be adsorbed. A retention pad was attached to the fixed platen. Subsequently, an appropriate amount of water was sprayed onto the holding surface of the resin sheet provided on the holding pad, and the water was appropriately removed, and then the glass substrate was firmly pressed on the holding pad to be adsorbed. Next, the tensile jig was tightly pressed and adhered to the surface of the glass substrate opposite to the holding pad side through the double-faced tape having the cushion layer of the same size as the glass substrate. Thereafter, the tensile jig was pulled to the side opposite to the glass substrate, and the maximum value of the tensile load when the glass substrate was separated from the holding pad was read. Tensilon (manufactured by ORIENTEC) was used as a tensile tester. The above operation was repeated three times without replacing the holding pad mounted on the object holder (the second and subsequent times, the glass substrate was adsorbed on the holding pad with the tensile jig adhered to the glass substrate) The maximum value of the tensile load of the meeting was averaged to determine the attraction force.

(Measurement of the life of the holding pad)

A holding pad was attached to a predetermined position of a polishing machine (product name: SP-1200, manufactured by Speed Farm Co., Ltd.). Subsequently, an appropriate amount of water was sprayed onto the holding surface of the resin sheet provided on the holding pad, and water was appropriately removed, and then the glass substrate for liquid crystal display (470 mm x 370 mm x 0.5 mm) . Using Polipass FX-7M (trade name, manufactured by Fujibo Ehime Co., Ltd.) as a polishing pad, polishing was carried out under the following conditions. Polishing is performed until the time when the object to be polished is broken from the holding pad or when the time when the skin of the holding pad is worn is damaged as a life end and polishing becomes impossible and the number of polished objects to be polished is increased, The life span was evaluated. In addition, the number of the objects to be polished was maximum 50 pieces.

Grinding machine used: Oscar grinder SP-1200 (manufactured by Speed Farm Co., Ltd.)

Polishing speed (revolutions): 61 rpm

Working pressure: 76 gf / ㎠

Slurry: Shorox A-10 (trade name, manufactured by Showa Denko K.K.) 10% slurry

Polishing time: 10 minutes / every

The results of the above measurements are shown in Table 1.

(Example 2)

A holding pad was prepared in the same manner as in Example 1 except that the amount of the water repellent agent added was changed to 7 parts by mass with respect to 100 parts by mass of the 30% DMF solution of the polyester-based polyurethane resin, and measurements were made. The results of each measurement are shown in Table 1.

(Example 3)

A holding pad was prepared in the same manner as in Example 1 except that the addition amount of the water repellent agent was changed to 10 parts by mass with respect to 100 parts by mass of the 30% DMF solution of the polyester-based polyurethane resin, and each measurement was carried out. The results of each measurement are shown in Table 1.

(Example 4)

A holding pad was prepared in the same manner as in Example 1 except that the amount of the water repellent agent added was changed to 13 parts by mass with respect to 100 parts by mass of the 30% DMF solution of the polyester-based polyurethane resin, and each measurement was carried out. The results of each measurement are shown in Table 1.

(Example 5)

A holding pad was prepared in the same manner as in Example 3 except that the resin of the raw material was changed to a polyester-based polyurethane resin having a 100% modulus of 8.4 MPa, and each measurement was carried out. The results of each measurement are shown in Table 1.

(Comparative Example 1)

A holding pad was prepared in the same manner as in Example 3, except that the resin of the raw material was changed to a polyester-based polyurethane resin having a 100% modulus of 3.0 MPa, and measurements were made. The results of each measurement are shown in Table 1.

(Comparative Example 2)

A retentive pad was prepared in the same manner as in Example 3 except that the water repellent agent was changed to "CHRISON ASSISTER SD-27" (trade name) manufactured by DIC Corporation, which contains a perfluorooctyl compound, and each measurement was carried out. The results of each measurement are shown in Table 1.

(Comparative Example 3)

A holding pad was prepared in the same manner as in Example 1 except that the amount of the water repellent agent added was changed to 1 part by mass with respect to 100 parts by mass of the 30% DMF solution of the polyester-based polyurethane resin, and measurements were made. The results of each measurement are shown in Table 1.

(Comparative Example 4)

A holding pad was prepared in the same manner as in Example 1 except that the addition amount of the water repellent agent was changed to 15 parts by mass with respect to 100 parts by mass of the 30% DMF solution of the polyester-based polyurethane resin, and each measurement was carried out. The results of each measurement are shown in Table 1.

(Comparative Example 5)

A holding pad was prepared in the same manner as in Example 3 except that the resin of the raw material was changed to a polyester-based polyurethane resin having a modulus of 100 MPa of 20 MPa, and each measurement was carried out. The results of each measurement are shown in Table 1.

In the lifetime measurement of the holding pad, in Comparative Examples 1 and 3, skin abrasion occurred in the resin sheet, and the object to be polished shifted in the in-plane direction of the holding pad, so that polishing became difficult. In Comparative Examples 2, 4, and 5, polishing was difficult as a result of peeling of the object to be polished from the holding pad.

INDUSTRIAL APPLICABILITY Since the holding pad of the present invention is suitably used for a semiconductor, a silicon wafer for a semiconductor device, a substrate for various recording disks, a glass substrate for a liquid crystal display, and the like as an object to be polished, have.

110: Retention pad
112: polyurethane resin sheet
114: substrate
116: Adhesive layer
P: Holding face.

Claims (6)

A holding pad comprising a polyurethane resin sheet having a holding surface for holding an object to be polished, characterized in that the polyurethane resin sheet has a storage elastic modulus E 'at a temperature of 40 DEG C of 0.3 to 2.0 MPa, And the absorption amount is 95 to 200 mg / 50.3 cm 2. The holding pad according to claim 1, wherein the polyurethane resin sheet has a KEL at 40 캜 of 1.0 × 10 ^{5 to} 5.0 × 10 ⁵ Pa ^-1 . The holding pad according to claim 1 or 2, wherein the resin constituting the polyurethane resin sheet has a 100% modulus at 25 DEG C of 4.0 to 10.0 MPa. The holding pad according to any one of claims 1 to 3, wherein the polyurethane resin sheet contains a water repellent agent. The holding pad according to claim 4, wherein the water repellent agent comprises a fluorinated water repellent having a perfluoroalkyl group having 6 to 8 carbon atoms. The holding pad according to claim 5, wherein 60 to 100 mol% of the fluorine-based water repellent contained in the polyurethane resin sheet is a fluorine-based water repellent having a perfluoroalkyl group having 6 carbon atoms.

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