TW201521958A - Holding pad - Google Patents

Abstract

The holding pad according to the invention is a holding pad comprising a polyurethane resin sheet for holding a holding surface of an object to be polished, wherein the polyurethane resin sheet has a storage elastic modulus E' of 0.3 to 2.0 MPa at 40 DEG C, and the polyurethane resin sheet has a water absorbing capacity of 95 to 200 mg/50.3 cm2.

Description

Hold pad

The present invention relates to a retaining pad.

Conventionally, when a semiconductor wafer, a wafer for a semiconductor device, a substrate for various recording disks, a glass substrate for a liquid crystal display, or the like, in particular, a glass substrate is subjected to precision planar polishing, it is attached to the polishing head by water. The holding mat absorbs the object to be held by the object to be polished, and then grinds it using a polishing pad. The holding mat has a sheet made of an elastic material such as a polyurethane resin having continuous cells, and the fine bubbles on the surface (holding surface) of the sheet can function as a suction cup to hold the object to be polished. That is, the sheet can function as a holding layer.

Incidentally, during the polishing process, the holding mat is exposed to the polishing liquid (grinding mud), and thus the polishing liquid may permeate into the continuous air bubbles existing inside the holding layer having the holding mat. When the polishing liquid penetrates, the elastic material constituting the holding layer loses elasticity or the holding layer swells and is difficult to be stably held, and as a result, the polishing workability is lowered. Regarding countermeasures against this phenomenon, for example, Patent Document 1 discloses a protection containing a fluorine-based water repellent. Hold the pad.

Prior technical literature Patent literature

Patent Document 1: Japanese Laid-Open Patent Publication No. Hei 9-254027

When the water repellent described in Patent Document 1 is used, it is possible to suppress penetration of the polishing liquid into the inside of the holding layer. However, in order to adsorb the object to be adhered to the holding mat, water is used to make the holding surface of the holding layer wet. At this time, since the water repellent is present, the affinity with water is lowered, and adsorption is likely to occur when water is removed. bad. On the other hand, if the amount of the water-repellent agent is reduced in order to prevent such adsorption failure, the water-repellent agent may be dispersed unevenly in the holding layer, and the water may be infiltrated by the water-repellent portion, and as a result, it is maintained during the grinding process. The skin wear occurs locally in the layer, and it is difficult to stably maintain the object to be polished. Here, "skin abrasion" means that the holding layer is swollen by water seepage or the like, and as a result, the holding surface of the holding layer is directly contacted with the polishing surface of the polishing pad to be removed, or the holding surface contacting the corner of the object to be polished is The corners are removed and the holes are opened. This is because the holding layer is swollen and peeled off by the polishing head to partially bend.

The present invention has been made in view of the above problems, and an object thereof is to provide a holding mat which can suppress both adsorption failure of an object to be polished and skin abrasion.

The inventors of the present invention have repeatedly conducted painstaking research in order to achieve the above object, It has been found that the above object can be attained if the storage elastic modulus E' of the holding mat at 40 ° C is appropriately lowered and the sheet having the water absorption amount measured by the specific water absorption amount is in a proper range as the holding layer, and the present invention is completed. .

That is, the present invention is as follows.

[1] A holding mat provided with a holding mat having a polyurethane resin sheet for holding a holding surface of an object to be polished, and a storage elastic modulus E' of the above polyurethane resin sheet at 40 ° C It is 0.3 to 2.0 MPa, and the water absorption amount of the above polyurethane resin sheet is 95 to 200 mg/50.3 cm ² .

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

[3] The above-mentioned holding mat, wherein the resin constituting the above-mentioned polyurethane resin sheet has a 100% modulus at 25 ° C of 4.0 to 10.0 MPa.

[4] The above holding mat, wherein the above-mentioned polyurethane resin sheet contains a water repellent.

[5] The holding mat according to the above aspect, wherein the water repellent contains a fluorine-based water repellent having a perfluoroalkyl group having 6 to 8 carbon atoms.

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

According to the present invention, it is possible to provide a holding mat which can suppress both adsorption failure of the workpiece and skin abrasion.

110‧‧‧ Keep pad

112‧‧‧ Polyurethane resin sheet

114‧‧‧Substrate

116‧‧‧Next layer

P‧‧‧ Keep face

Fig. 1 is a schematic cross-sectional view showing an example of a holding mat to which the present invention is attached.

Fig. 2 is a perspective schematic view showing an apparatus used for measuring the amount of adsorption associated with the present invention.

Hereinafter, an embodiment of the present invention (hereinafter simply referred to as "this embodiment") will be described in detail with reference to the drawings, but the present invention is not limited to the following embodiment. The invention can be variously modified without departing from the spirit and scope of the invention. In the drawings, the same elements are denoted by the same reference numerals, and the repeated description is omitted. In addition, the positional relationship of up, down, left, and the like is based on the positional relationship shown in the drawing unless otherwise specified. Moreover, the dimensional ratios of the drawings are not limited by the ratios illustrated.

The holding mat of the present embodiment is provided with a holding mat having a polyurethane resin sheet for holding the holding surface of the workpiece, and the storage modulus E' of the polyurethane resin sheet at 40 ° C is 0.3~ 2.0 MPa, and the water absorption of the polyurethane resin sheet is 95 to 200 mg/50.3 cm ² .

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

The resin sheet 112 contained in the holding mat 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 modulus E' of the resin sheet 112 is 0.3 to 2.0 MPa at 40 °C. By setting the storage modulus E' at 40 °C to 0.3 MPa or more, the resin sheet 112 is less likely to cause skin abrasion during the polishing process. On the other hand, when the storage modulus E' at 40 °C is set to 2.0 MPa or less, the adsorption force of the resin sheet 112 on the object to be polished is increased, and 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 ° C, preferably 0.5 to 1.0 MPa, more preferably 0.5 to 0.7 MPa.

(Method for measuring storage modulus E')

In the present specification, the storage elastic modulus E' of the resin sheet is measured by using a dynamic viscoelasticity measuring device (for example, "TAA III" manufactured by TA Instruments Japan Co., Ltd.) under the following conditions, and is added and averaged. value.

[Measurement conditions]

. Sample size: 10mm × 10mm × thickness 0.8mm × 3 overlap

. Test direction: compression mode

. Load: 100g/cm ²

. Deformation: 0.10%

. Frequency: 1Hz

. Temperature range: 20~80°C, heating rate: 5°C/min

. Sample thickness: measured by thickness

. In the case where the thicknesses of the samples are different, the measurement is carried out by overlapping the range of 2 mm to 3 mm.

The water absorption amount of the resin sheet 112 is 95 to 200 mg/50.3 cm ² . By setting the water absorption amount to 95 mg/50.3 cm ² or more, the adsorption force of the resin sheet 112 on the workpiece is increased, and the adsorption failure is less likely to occur. On the other hand, when the adsorption amount is set to 200 mg/50.3 cm ² or less, the resin sheet 112 is less likely to cause skin abrasion during the polishing process. From the same viewpoint, the water absorption amount of the resin sheet 112 is preferably 100 to 160 mg/50.3 cm ^{2 ,} preferably 107 to 150 mg/50.3 cm ^{2 , more} preferably 110 to 130 mg/50.3 cm ² .

(Method for measuring water absorption)

The water absorption amount of the resin sheet 112 was measured as follows. Fig. 2 is a perspective schematic view showing an apparatus used for measuring the water absorption amount of the resin sheet. First prepare the diameter The 125 mm holding pad 110 has a sample 10 to be measured, a butt-welded flange 20 made of vinyl chloride, and a flange plate 30 made of vinyl chloride (any of which is JIS 10K-80A). Inner diameter of flanges 20, 30 It is 80 mm (the sectional area is 50.3 cm ² ). Next, the sample 10 was dried in a dryer at 40 ° C for 10 hours or more. The work was then carried out in an atmospheric environment at room temperature of 20 ° C and a relative humidity of 50%. Next, the sample 10 was naturally cooled to room temperature in an atmospheric environment, and its mass was measured by an electronic balance. Next, as shown in Fig. 2, the holding surface P of the sample 10 is sandwiched between the butt-welded flange 20 and the flange plate 30 on the butt-welded flange 20 side, and is fixed by being clamped up and down. Next, 300 mL of 20 ° C ion-exchanged water W was injected into the tube of the butt-welded flange 20 (at this time, the height of the holding surface P of the sample 10 to the water surface was about 60 mm). After the injection, the cells were allowed to stand for 8 hours, and then the fixed sample 10 was unwound and taken out, and the surface water was absorbed by the filter paper. At this time, the water is sucked by the filter paper so as not to be pressed against the sample 10 and wiped only on the surface of the sample 10. The mass of the sample 10 was then quickly determined. The ion-exchanged water W was injected and allowed to stand, and the mass difference of the sample 10 before and after standing was determined as the water absorption amount of the resin sheet 112.

The method of controlling the storage elastic modulus E' and the water absorption amount of the resin sheet 112 in the above-described embodiment in the above range is, for example, adjusting the 100% modulus of the resin constituting the resin sheet 112 at 25 ° C and the KEL at 40 ° C. The type of the resin, the addition of the water repellent, the type and amount of the water repellent, the thickness and density of the resin sheet 112, and the method of polishing the back surface of the resin sheet 112 on the opposite side of the skin layer.

The resin constituting the resin sheet 112 preferably has a 100% modulus at 25 ° C of 4.0 to 10.0 MPa, preferably 5.0 to 9.0 MPa, more preferably 5.0 to 7.0 MPa. By setting the 100% modulus to 4.0 MPa or more, the storage elastic modulus E' of the resin sheet 112 is easily 0.3 MPa or more, and by setting it at 10.0 MPa or less, the storage elastic modulus E' of the resin sheet 112 is easily 2.0. Below MPa. Further, in the present specification, the 100% modulus is a non-foamed resin sheet (test piece) of the same material as that of the resin sheet 112 in an environment of room temperature of 23 ± 2 ° C, and when extending 100%, That is, when the elongation is twice the original length, the tensile force is divided by the initial sectional area of the test piece.

The KEL of the resin sheet 112 at 40 ° C is preferably 1.0 × 10 ⁵ to 5.0 × 10 ⁵ Pa ^{-1 , more} preferably 1.5 × 10 ⁵ to 4.0 × 10 ⁵ Pa ^-1 , and 2.0 × 10 ⁵ to 3.0 × 10 ⁵ Pa ^-1 is better. By setting the KEL to 1.0 × 10 ⁵ Pa ^-1 or more, the resin sheet 112 is easily deformed, and the retainability and the adsorptivity of the object to be polished can be improved. In addition, it is difficult to deviate from the in-plane direction of the object to be polished during the polishing process. On the other hand, when the KEL is set to 5.0 × 10 ⁵ Pa ^-1 or less, the amount of deformation of the resin sheet 112 can be reduced (that is, the amount of the resin sheet 112 at the time of polishing processing can be reduced), and the occurrence of skin abrasion can be suppressed. The life of the pad 110 can be further increased.

(KEL calculation method)

In the present specification, KEL (energy loss factor) is a storage elastic modulus E' and a loss elastic modulus E" measured at 40 ° C according to the same conditions as the "measurement method of storage elastic modulus E'". It is calculated by the following formulas (1a) and (1b).

KEL=tanδ×10 ¹² /(E'×(1+tanδ ² )) (1a)

Tanδ=E”/E’ (1b)

The density (total density) of the resin sheet 112 associated with this embodiment is preferably 0.15 to 0.30 g/cm ² at 25 °C. When the density is set to 0.15 g/cm ² or more, the permanent deformation of the resin sheet 112 is less likely to occur, and by setting it at 0.30 g/cm ² or less, the entire resin sheet 112 can easily and more uniformly retain the object to be polished. . As a result, by setting the density of the resin sheet 112 to the above range, it is possible to further suppress the occurrence of unevenness in the polishing in the in-plane direction of the holding mat 110 during the polishing process or in the polishing process.

The thickness of the resin sheet 112 is not particularly limited, and may be, for example, 0.2 to 1.5 mm, or 0.6 to 1.2 mm. Further, the thickness of the resin sheet 112 can be measured in accordance with the measurement method described in JIS K 6550 (1994). In other words, in the thickness direction of the resin sheet 112, a load (load) of 100 g per 1 cm ^{2 is} applied as the thickness at the initial load.

In the resin sheet 112, the constituent material of the precursor of the resin (hereinafter referred to as "base material") has a plurality of bubbles (not shown), which can be formed by a so-called wet film formation method or by a dry molding method. From the standpoint of more effective and indeed achieving the object of the present invention, it is preferred to form by a wet film formation method. When the resin sheet 112 is formed by a wet film formation method, the surface of the holding surface P may have a dense microporous skin layer (not shown). The surface of the skin layer has fine flatness. On the other hand, on the inner side of the skin layer (inside of the resin sheet 112), a microporous hole having a larger pore diameter than the skin layer and a triangular shape with rounded corners along the thickness direction of the resin sheet 112 may be formed (continuous air bubbles; Not shown). This hole can also be formed such that the hole diameter on the holding surface P side is smaller than the opposite side of the holding surface P. A hole (not shown) having a pore diameter larger than that of the skin layer and smaller than the pores may be formed in the resin sheet 112. The microporous, porous, and small-pore pores of the cortex may also be connected to each other in a mesh shape by communicating holes.

The base material constituting the resin sheet 112 is not particularly limited as long as it contains a composition of the most polyurethane resin. For example, the resin sheet 112 may contain a polyurethane resin 80 with respect to the total amount of the base material. ~100% by mass. The resin sheet 112 preferably contains a polyamine relative to the total amount thereof. The ethyl formate resin is 85 to 100% by mass, more preferably 90 to 100% by mass, and particularly preferably 90 to 95% by mass.

Examples of the polyurethane resin include a polyester-based polyurethane resin, a polyether-based polyurethane resin, and a polycarbonate-based polyurethane resin, and these may be used alone or in combination of two. More than one kind to use. From the viewpoint of more effectively and surely exerting the object of the present invention, a polyester-based polyurethane resin is preferred among these.

The polyurethane resin can be synthesized by a usual method or can be obtained from a commercially available product. The commercially available product is, for example, Crisvon (trade name, manufactured by DIC Corporation), Sanprene (trade name, manufactured by Sanyo Chemical Industries Co., Ltd.), and Resamine (trade name, manufactured by Dainippon Seika Co., Ltd.). The polyurethane resin may be used alone or in combination of two or more.

The resin sheet 112 may contain, in addition to the polyurethane resin, other resins such as polyfluorene resin and/or polyimide resin. The polyanthracene resin can be synthesized by a conventional method or can be obtained from a commercially available product. Commercially available products include, for example, Udel (trade name, manufactured by Solvay Advanced Polymers Co., Ltd.). Polyimine resins can be synthesized by a conventional method or can be obtained from commercially available products. As a commercial item, for example, Aurum (trade name, manufactured by Mitsui Chemicals, Inc.) can be cited.

The resin sheet 112 preferably contains a water repellent agent in addition to the base material. Examples of the water repellent include a fluorine water repellent, a rhodium water repellent, and a hydrocarbon water repellent. From the viewpoint of more effective and indeed achieving the object of the present invention, it is preferred that the fluorine-based water repellent is used among the above. Water repellent can be used alone or in combination Use above.

The fluorine-based water repellent is, for example, a compound having a perfluoroalkyl group (fluorine-based water repellent), and is preferably a fluorotelomer represented by the following formula (2).

Rf-R-X (2)

Here, Rf represents a perfluoroalkyl group having a carbon number of 3 to 8, preferably 4 to 8, preferably 6 to 8, and particularly preferably 6. Further, R represents an alkylene group having a carbon number of 2 to 6, preferably 2 to 4, and particularly preferably 2. 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 the like is preferably a hydroxyl group. Further, examples of the compound having a perfluoroalkyl group include a compound obtained by denaturation of a resin with a perfluoroalkyl group. The resin which can form the resin sheet which retains a pad is a resin, and a polyurethane resin is mentioned, for example, as a resin, and the denaturation method is mentioned, for example, at the end of resin. And/or a method of introducing a perfluoroalkyl group into a side chain. The compound having a perfluoroalkyl group may be used alone or in combination of two or more.

From the viewpoint of more effectively and surely achieving the object of the present invention, it is preferred that the fluorine telomer has a carbon number of Rf of 6 and a carbon number of R of 2 is more preferable. In addition, in consideration of dispersibility and time-dependent stability of the resin sheet, a compound obtained by denaturation of a resin with a perfluoroalkyl group is a compound obtained by introducing a fluorotelomer into the resin, for example, having the above formula ( 2) A resin having a group represented by Rf-R- is preferable, and a polyurethane resin having a group represented by Rf-R- in the above formula (2) is preferred. As such a resin, for example, a polyurethane resin described in International Publication No. 2012/172936 can be mentioned.

The fluorotelomer can be synthesized by a conventional method or can be obtained from a commercially available product. For example, the Crisvon Assistor SD series (trade name, manufactured by DIC Corporation), the Asahiguard E series (trade name, manufactured by AGC Seimi Chemical Co., Ltd.), and the NK Guard S series (product name manufactured by Rihua Chemical Co., Ltd.) , Unidyne Multi series (trade name by Daikin Industrial Co., Ltd.), etc. The fluorotelomer may be used singly or in combination of two or more.

The water repellent content in the resin sheet 112 is preferably 2 to 14 parts by mass, and preferably 3 to 13 parts by mass, based on 30 parts by mass of the resin constituting the resin sheet 112. When the content of the water repellent is 2 parts by mass or more based on 30 parts by mass of the resin, the water absorption amount is easily 200 mg/50.3 cm ² or less, and the water repellent can be prevented from being locally present, so that the skin portion can also be suppressed. Wear. In addition, by setting the content of the water repellent to 14 parts by mass or less based on 30 parts by mass of the resin, the water absorption amount is easily 95 mg/50.3 cm ² or more. In the method of manufacturing the holding mat 110 described later, when the resin sheet 112 is produced by the coagulation and regeneration step and the water repellent is contained in the resin solution at the stage before the coagulation and regeneration step, the coagulation unevenness is less likely to occur. As a result, film formation unevenness of the resin sheet 112 can be suppressed more.

In addition, a fluorine-based water repellent agent such as a fluorine telomer is used as the water repellent, and when the fluorine water repellent contains a fluorine water repellent having Rf of carbon number 6, the resin sheet 112 contains In the fluorine-based water repellent, 60 to 100 mol% is preferably a fluorine-based water repellent having a carbon number of 6 Rf. This means that a large amount of fluorocarbon is contained as a fluorine telomer having a carbon number of more than 6 A compound having a small amount of a fluorine atom as in the case of a fluorotelomer having Rf having a carbon number of less than 6. Thereby, the content of the compound containing a large amount of fluorine atoms can be reduced, and the decrease in the amount of water absorption and the poor adsorption can be more effectively suppressed, and the content of the compound containing a small amount of fluorine atoms can be reduced, and the appropriate water repellency can be more effectively ensured.

In addition to the resin and any water repellent, the resin sheet 112 may contain a material which is usually used for a resin sheet of a holding mat, such as a pigment such as carbon black, a hydrophilic additive, and hydrophobicity. One or two or more kinds of additives. In addition, various materials such as a solvent used in the production process of the resin sheet 112 may remain in the resin sheet 112 without hindering the solution of the problem of the present invention.

Fine pores may also be present on the holding surface P of the resin sheet 112. The fine pores can be formed, for example, by adding an additive which forms a fine pore on the holding surface (cortex) when the resin sheet 112 is formed into a film.

The base material 114 provided in the holding mat 110 is not particularly limited as long as it can support the resin sheet 112, and may be included in the conventional holding mat as a base material. Specifically, polyethylene terephthalate may be mentioned. A resin film such as an ester (hereinafter referred to as "PET") film.

Additionally, the adhesive layer 116 may also contain an adhesive or adhesive known to be used to hold the mat. Examples of the material of the adhesive layer 116 include various thermoplastic adhesives such as an acrylic, a nitrile, a nitrile rubber, a polyamine, a polyurethane, and a polyester.

Further, the base material 114 and the adhesive layer 116 of the holding mat 110 may also come from a double-sided tape provided with these. The double-sided tape has both sides of the substrate 114 There is an adhesive layer containing an adhesive or an adhesive, wherein one of the subsequent layers corresponds to the above-mentioned adhesive layer 116. The other adhesive layer is a holding plate for attaching the holding mat 110 to the holding machine. The double-sided tape may be included in the conventional holding mat, and may have a release paper (not shown) on the opposite side of the base material 114.

Next, an example of a method of manufacturing the holding mat of the present embodiment will be described. Here, the case where the resin sheet 112 is produced by the wet film formation method will be described. However, the method of producing the resin sheet 112 is not limited thereto. In this manufacturing method, the step of preparing the resin sheet 112 and the step of joining the substrate 114 to the resin sheet 112 to obtain the holding mat 110 are included.

The step of preparing the resin sheet 112 further includes a step of preparing a resin solution containing a resin and a solvent, if necessary, a water repellent (resin solution preparation step); and a step of coating the resin solution on the surface of the film formation substrate ( a coating step); a step of solidifying and regenerating the resin in the resin solution to form a precursor sheet (coagulation regeneration step); a step of removing the solvent from the precursor sheet to obtain a resin sheet 112 (solvent removal step); and polishing treatment Or a chipping process of grinding and/or removing a part of the resin sheet 112 (grinding. removal step). The following describes each step.

First, in the resin solution preparation step, a resin such as the above-mentioned polyurethane resin, a solvent which can dissolve the resin and be mixed into a coagulating liquid described later, and a water repellent and other materials contained in the resin sheet 112 are necessary. (for example, pigments, hydrophilic additives and hydrophobic additives), Further, the resin solution was prepared by defoaming under reduced pressure as necessary. 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 relative to the total amount of the resin solution is not particularly limited, and may be, for example, in the range of 10 to 50% by mass or 15 to 35% by mass.

Next, in the coating step, it is preferred to apply a resin solution to the surface of the tape-form film-forming substrate at a normal temperature using a coating device such as a knife coater to form a coating film. The thickness of the resin solution applied at this time may be appropriately adjusted so that the thickness of the finally obtained resin sheet 112 becomes a desired thickness. The material of the substrate for film formation may, for example, be a resin film such as a PET film, a cloth or a non-woven fabric. Among these, a resin film such as a PET film which is difficult to penetrate liquid is preferable.

Next, in the solidification regeneration step, the coating film of the resin solution applied to the substrate for film formation is continuously guided to a poor solvent (for example, water in the case of polyurethane resin) corresponding to the resin. In the coagulation solution of the ingredients. In order to adjust the regeneration rate of the resin, an organic solvent such as a polar solvent different from the solvent in the resin solution may be added to the coagulation liquid. Further, the temperature of the coagulation liquid is not particularly limited as long as it is a temperature at which the resin can be solidified, and may be, for example, 15 to 65 °C. In the coagulation liquid, a film (skin layer) is first formed at the interface between the resin solution coating film and the coagulating liquid, and numerous dense micropores are formed in the resin beside the film. Then, the resin is regenerated by the diffusion of the solvent contained in the resin solution into the coagulating solution and the infiltration of the poor solvent into the resin, and is preferably a resin having an open cell structure. At this time, if the liquid is difficult to penetrate into the substrate for film formation (for example, PET thin) In the film), the coagulating liquid does not permeate the substrate, so that the solvent and the poor solvent in the resin solution are preferentially displaced in the vicinity of the skin layer, and a large void is formed in the inner side of the skin layer. In this manner, a precursor sheet is formed on the film forming substrate.

When the water repellent is contained in the resin solution, if the content of the water repellent is 14 parts by mass or less based on 30 parts by mass of the resin, it is possible to suppress uneven coagulation which may be caused by interference between the water repellent and the coagulating liquid. Therefore, as a result, the film formation unevenness of the obtained resin sheet 112 can be prevented more.

Next, in the solvent removal step, the solvent remaining in the formed precursor sheet is removed to obtain a resin sheet 112. The solvent can be removed by using a known cleaning solution. Further, after the solvent is removed, the resin sheet 112 may be dried as necessary. The drying of the resin sheet 112 may be, for example, a cylindrical dryer having a cylinder having a heat source therein, but the drying method is not limited thereto. In the case of using a cylindrical dryer, the precursor sheet is dried along the circumferential surface of the cylinder. Further, the obtained resin sheet 112 may be wound into a roll shape.

Next, in the polishing removal step, at least one of the main surface on the skin side of the resin sheet 112 and the back surface on the opposite side thereof is preferably ground and/or removed by a buffing treatment or a chipping treatment. By the polishing treatment or the chipping treatment, the thickness of the resin sheet 112 can be made uniform, so that the pressing force applied to the workpiece can be more uniform, and the damage of the object to be polished can be further suppressed, and the flatness of the object to be polished can be improved. . Further, since the main surface of the resin sheet 112 on the skin side is the holding surface P, it is preferable to perform a polishing treatment on the back surface to improve the polishing uniformity of the workpiece.

Next, the substrate 114 is bonded to the resin sheet 112 to obtain a holding mat 110. In this step, the substrate 114 is bonded to the opposite surface of the holding surface P of the resin sheet 112 by the adhesive layer 116, for example, using the substrate 114 and the double-sided tape having the adhesive layer 116. Further, on the opposite side of the adhesive layer 116 of the substrate 114, another double-sided tape adhesive layer and a release paper may be provided. The holding mat 110 can be obtained in this manner.

Next, a method of polishing processing using the holding mat 110 of the present embodiment will be described. The object to be polished is not particularly limited, and examples thereof include a semiconductor, a wafer for a semiconductor device, a substrate for various recording disks, and a material for a glass substrate for a liquid crystal display. From the viewpoint of more effectively and surely exerting the effects produced by the present invention, the object to be polished is preferably a glass substrate among the above.

In the polishing process, first, the holding mat 110 is attached to the workpiece holder of the grinder to hold the mat 110 to hold the object to be polished. In order to attach the holding mat 110 to the workpiece holder, the release paper of the double-sided tape is removed as necessary, and the exposed adhesive layer is then fixed to the workpiece holder, and the holding surface P is directed downward (or upward). Alternatively, in a case where the holding mat 110 does not have a double-sided tape, the holding mat 110 is subsequently fixed to the object holder by a separately prepared adhesive or adhesive. Next, the holding surface P of the resin sheet 112 contains an appropriate amount of water, and the object to be polished is pressed, and the object to be polished is held by the holding object by the holding pad 110 by the surface tension of the water and the adhesiveness of the resin sheet 112. seat. At this time, the surface to be polished (machined surface) of the object to be polished is directed downward (or upward). On the other hand, under the (or above) the object to be polished and ground The polishing pad (abrasive cloth) is attached to the surface of the polishing plate disposed opposite to the object holder so that the polishing surface faces upward (or below).

Next, the object to be polished is moved to the polishing platen to convey the object to be polished, and the surface to be polished of the object to be polished is brought into contact with the polishing surface of the polishing pad. Then, a polishing slurry containing chemical components such as abrasive grains (abrasive particles; for example, SiO ₂ or CeO ₂ ) and an oxidizing agent typified by hydrogen peroxide is circulated and supplied between the object to be polished and the polishing pad. In this manner, the object to be polished is pressed against the polishing pad by the object to be polished, and the object to be polished and the polishing platen are rotated, and the surface of the object to be polished is polished by the polishing pad by CMP. machining.

In the present embodiment, the storage elastic modulus E' of the resin sheet 112 at 40 ° C is set to 0.3 to 2.0 MPa, and the water absorption amount of the resin sheet 112 is set to 95 to 200 mg / 50.3 cm ² , thereby suppressing the polishing. Both the adsorption of the substance and the abrasion of the skin. By setting the storage modulus E' at 40 ° C to 0.3 MPa or more, the resin sheet 112 is less likely to cause skin abrasion during the polishing process. On the other hand, when the storage elastic modulus E' at 40 ° C is set to 2.0 MPa or less, the adsorption force of the resin sheet 112 on the workpiece is increased, and adsorption failure is less likely to occur. In addition, by setting the water absorption amount to 95 mg/50.3 cm ² or more, the adsorption force of the resin sheet 112 on the workpiece is increased, and the adsorption failure is less likely to occur. On the other hand, when the adsorption amount is set to 200 mg/50.3 cm ² or less, the resin sheet 112 is less likely to cause skin abrasion during the polishing process. Inhibition of the occurrence of epidermal abrasion prevents the holding surface P from being damaged, and as a result, the life of the holding mat 110 is prolonged.

Although the present embodiment has been described in detail above, the present invention is not limited to the above embodiment. For example, in the above-described embodiment, the bonding of the resin sheet 112 and the substrate 114 is performed using the adhesive layer 116, and the bonding is not limited to the use of the adhesive layer 116. Further, the holding mat of the present invention may not have a base material, and it is preferable to provide a base material from the viewpoint of maintaining the operability of the mat. In addition, in the method of manufacturing the holding mat, the grinding may be omitted. Remove the steps. Further, in the method of manufacturing the holding mat, the water repellent may be added to the resin solution to be applied to the obtained resin sheet, or the water repellent may be applied together, and then the resin may be dried as necessary. The flakes contain a water repellent. Examples of the method of applying the water repellent include a dipping method and a spraying method.

[Examples]

The invention is further illustrated by the following examples, but the invention is not limited by the examples.

(Example 1)

100 parts by mass of the polyester resin polyurethane resin of 6.0 MPa, 100 parts by mass of the raw material resin (the same as the value at 25 ° C, the same applies hereinafter), 50 parts by mass of DMF, and 8 mass of water. In a portion, 3 parts by mass of "Crisvon Assistor SD-38" (trade name) manufactured by DIC Corporation, which is a water-repellent agent and containing a perfluorohexyl compound, was mixed and stirred to prepare a resin solution. Next, a PET film as a substrate for film formation is prepared, and the resin solution is applied to the resin solution using a knife coater. On top of this, a coating film having a thickness of 1.0 mm was obtained. The polyester-based polyurethane resin is a polyester polyol obtained by dehydrating and condensing ethylene glycol, propylene glycol and adipic acid, and methylene bis(4,1-phenylene)=diisocyanate ( MDI) is obtained by condensation with a low molecular weight diol (the same applies to the following examples and comparative examples).

Next, the obtained coating film was immersed in a 18° C. coagulation bath containing water as a coagulation liquid together with the substrate for film formation, and the resin was solidified and regenerated to obtain a precursor sheet. The precursor sheet is taken out from the coagulation bath, the film-forming substrate is peeled off from the precursor sheet, and then the precursor sheet is immersed in a washing liquid (desolvent bath) composed of water and at room temperature, and removed as a solvent. DMF, while getting a resin sheet. Then, the resin sheet is dried while being entangled. Next, the back surface of the resin sheet (the side on which the film formation substrate was peeled off and the surface in contact with the film formation substrate) was subjected to a buffing treatment to have a thickness of 0.8 mm.

Next, a double-sided tape having a backing layer (material: acrylic resin) on both sides of the PET substrate and further having a release paper on one side is attached to the resin sheet in an adhesive layer on the opposite side to the release paper. The polished side was then cut into a circle having an outer diameter of 33.5 cm to obtain a holding mat.

The storage elastic modulus E' at 40 ° C of the resin sheet provided in the holding mat is measured by the above-mentioned "measurement method of storage elastic modulus E'", and the water absorption amount is measured by the "measurement method of water absorption amount". The KEL at 40 ° C was measured by the above "calculation method of KEL". Further, in the method for measuring the storage modulus E' and KEL, the dynamic viscoelasticity measuring device The product name "RSA III" manufactured by TA Instruments Japan was used.

(Measurement of adsorption force)

The holding mat was cut into squares of about 100 mm x 100 mm. In addition, prepare the diameter A glass substrate having a thickness of 60 mm and a thickness of about 1 mm is used as an object to be adsorbed. Install the cut retaining pad on the fixed plate. Next, an appropriate amount of water is sprayed on the holding surface of the resin sheet provided on the holding mat to appropriately remove the moisture, and then the glass substrate is surely pressed to be adsorbed on the holding mat. Next, the jig for stretching was pressed against the surface of the glass substrate on the opposite side of the holding mat by a double-sided tape having the same size and a buffer layer as the glass substrate. Then, the jig for stretching was stretched to the opposite side to the glass substrate, and the maximum value of the tensile load was read when the glass substrate was pulled apart by the holding mat. The tensile testing machine was a universal tensile testing machine TENSILON (manufactured by ORIENTEC Co., Ltd.). The above-described operation is repeated three times without replacing the holding mat attached to the object to be polished, (but after the second time, the glass substrate is attached to the holding mat in a state in which the jig for stretching is attached to the glass substrate). The maximum values of the three tensile loads were added and averaged to determine the adsorption force.

(maintaining the life of the pad)

The holding mat was attached to a predetermined position of a grinder (manufactured by SpeedFam Co., Ltd., trade name "SP-1200"). Next, an appropriate amount of water is sprayed on the holding surface of the resin sheet provided in the holding mat to appropriately remove the moisture, and then the glass substrate for the liquid crystal display as the object to be polished is used. (470 mm × 370 mm × 0.5 mm) was adsorbed on the holding mat. The polishing pad was polished using Polypas FX-7M (trade name, manufactured by Fujifilm Ehime Co., Ltd.) under the following conditions. The time point at which the object to be polished is detached from the holding mat and the time at which the pad is worn is determined as the end point of the life, and the polishing process is performed until the polishing is impossible. After the polishing is completed, the number of objects to be polished is evaluated as the life of the pad. . In addition, the number of objects to be polished is up to 50.

Grinding machine: Oscar grinder SP-1200 (trade name, manufactured by SpeedFam Co., Ltd.)

Grinding speed (speed): 61rpm

Processing pressure: 76gf/cm ²

Grinding mud: 10% grinding mud from Shorex A-10 (trade name of Showa Denko Co., Ltd.)

Grinding time: 10 minutes / piece

The results of the above respective measurements are disclosed in Table 1.

(Example 2)

Change the amount of water repellent added to polyester-based polyurethane A holding mat was prepared in the same manner as in Example 1 except that 100 parts by mass of the resin was used in an amount of 7 parts by mass, and each measurement was carried out. The results of each measurement are disclosed in Table 1.

(Example 3)

A holding mat was produced in the same manner as in Example 1 except that the amount of the water-repellent agent was changed to 10 parts by mass based on 100 parts by mass of the 30% DMF solution of the polyester-based polyurethane resin. Determination. The results of each measurement are disclosed in Table 1.

(Example 4)

A holding mat was prepared in the same manner as in Example 1 except that the amount of the water-repellent agent was changed to 13 parts by mass based on 100 parts by mass of the 30% DMF solution of the polyester-based polyurethane resin. Determination. The results of each measurement are disclosed in Table 1.

(Example 5)

A holding mat was produced in the same manner as in Example 3 except that the raw material resin 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 disclosed in Table 1.

(Comparative Example 1)

In the same manner as in Example 3 except that the raw material resin was changed to a polyester-based polyurethane resin having a 100% modulus of 3.0 MPa. Pads were taken for each measurement. The results of each measurement are disclosed in Table 1.

(Comparative Example 2)

A holding mat was prepared in the same manner as in Example 3 except that the water-repellent was changed to "Crisvon Assistor SD-27" (trade name) manufactured by DIC Co., Ltd. containing a perfluorooctyl compound, and each measurement was performed. The results of each measurement are disclosed in Table 1.

(Comparative Example 3)

A holding mat was prepared in the same manner as in Example 1 except that the amount of the water-repellent agent was changed to 1 part by mass based on 100 parts by mass of the 30% DMF solution of the polyester-based polyurethane resin. Determination. The results of each measurement are disclosed in Table 1.

(Comparative Example 4)

A holding mat was prepared in the same manner as in Example 1 except that the amount of the water-repellent agent was changed to 15 parts by mass based on 100 parts by mass of the 30% DMF solution of the polyester-based polyurethane resin. Determination. The results of each measurement are disclosed in Table 1.

(Comparative Example 5)

A holding mat was produced in the same manner as in Example 3 except that the raw material resin was changed to a polyester-based polyurethane resin having a 100% modulus of 20 MPa, and each measurement was performed. The results of each measurement are disclosed in Table 1.

In the measurement of the life of the holding mat, in the case of Comparative Examples 1 and 3, the resin sheet was subjected to skin abrasion, and the object to be polished was deviated from the in-plane direction of the holding mat, and as a result, polishing was difficult. Further, in the case of Comparative Examples 2, 4, and 5, the object to be polished was released from the holding mat, and as a result, it was difficult to perform polishing.

Industrial availability

The holding mat of the present invention is suitably used for polishing a semiconductor, a substrate for a semiconductor device, a substrate for various recording discs, a glass substrate for a liquid crystal display, or the like as an object to be polished, and therefore is industrially usable for these uses. Sex.

Claims (6)

A holding mat provided with a holding mat having a polyurethane resin sheet for holding a holding surface of an object to be polished, and the storage elastic modulus E' of the polyurethane resin sheet at 40 ° C is 0.3~ 2.0 MPa, and the water absorption amount of the aforementioned polyurethane resin sheet is 95 to 200 mg/50.3 cm ² . The holding mat of claim 1, wherein the polyurethane resin sheet has a KEL of from 1.0 × 10 ⁵ to 5.0 × 10 ⁵ Pa ^-1 at 40 °C. The holding mat according to claim 1 or 2, wherein the resin constituting the polyurethane resin sheet has a 100% modulus at 25 ° C of 4.0 to 10.0 MPa. The holding mat of claim 1 or 2, wherein the polyurethane resin sheet contains a water repellent. The retaining pad of claim 4, wherein the water repellent comprises a fluorine-based water repellent having a perfluoroalkyl group having a carbon number of 6-8. The holding mat of the fifth aspect of the invention, wherein 60 to 100 mol% of the fluorine-based water repellent agent contained in the polyurethane resin sheet is a fluorine-based dial having a carbon number of 6 perfluoroalkyl group Aqueous agent.