JP7186340B2 - polishing sheet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polishing sheet suitable for finishing which is used to form a good mirror surface on bare silicon wafers, glass, compound semiconductor substrates, hard disk substrates, and the like.

BACKGROUND ART Conventionally, a polishing method using a polishing sheet has been employed as a means for mirror-finishing bare silicon wafers, glass, compound semiconductor substrates, hard disk substrates, and the like. The polishing sheet is made of non-woven fabric or woven fabric made of synthetic fiber, synthetic rubber, etc. as a base material, and a polyurethane-based solution is applied to the upper surface of the base material. It has a structure having a plurality of openings on the surface and a soft porous layer on the surface layer having a plurality of teardrop-shaped pores inside from the openings. A method of forming the openings by grinding and removing the surface of the skin layer of the soft porous layer having a plurality of teardrop-shaped pores inside is disclosed. (See Patent Document 1.).

In recent years, the quality requirements for the surface of the substrate to be polished have become more stringent. , there are problems that the surface to be polished of the substrate has many fine defects and that the edges of the substrate are greatly sagging. On the other hand, Patent Document 2 also discloses a finished polishing sheet in which a soft porous layer is formed on a polyester film. A polishing sheet that is integrated with a film by bonding is known. Although the sag at the edge of the substrate is small, as a manufacturing method, a soft porous layer is formed on the substrate, then peeled off and bonded. Since it is integrated, there is a problem that there are many fine defects on the polished surface of the substrate, probably due to slight residual strain of the soft porous layer at the time of peeling or adhesion. Furthermore, as a known technique for increasing the adhesive force at the interface between the polyester film and the soft porous layer, as shown in Patent Document 3, after forming a thermoplastic resin layer of a polyurethane-polyester copolymer on the polyester film, A technique for forming a soft porous layer by directly applying it is known, but the polishing sheet obtained by using this technique has a weak interface between the soft porous layer and the polyurethane-polyester copolymer resin layer, making it practically useless. There was a problem that the necessary adhesive strength could not be obtained.

JP-A-11-335979 JP-A-12-101339 JP-A-2000-42909

In view of the background of the prior art described above, the object of the present invention is to provide a surface to be polished of higher quality with less edge sagging and fewer fine defects in bare silicon wafers, glass, compound semiconductor substrates, hard disk substrates, and the like. To provide a polishing sheet suitable for mirror polishing, which can obtain a

In order to solve the above problems, the present invention discloses the following abrasive sheet.

Abrasive sheets laminated adjacently in order from the first layer to the fifth layer,
The first layer is a soft porous layer of a polyurethane resin having a plurality of pores with an open surface and a teardrop-shaped interior,
The second layer contains a polyurethane resin and a polyurethane urea resin having a ratio of the number of urea bonds to the number of urethane bonds of 5 to 18%. The proportion is 16 to 36%,
The third layer is a polyester film,
the fourth layer is an adhesive layer,
The fifth layer is a cushion layer having a compression modulus of 0.10 to 0.50 MPa.
polishing sheet.

Further, in order to solve the above problems, the present invention discloses the following method for producing an abrasive sheet.

A method for producing an abrasive sheet in which the first layer to the fifth layer are adjacently laminated in order, comprising:
Adhesive is applied to the polyester film that will be the third layer and dried to form the adhesive layer that is the fourth layer, and the third layer and the cushion layer of the fifth layer are formed through the fourth layer. pasted together,
On the side of the third layer opposite the fourth layer,
A. polyurethane resin,
B. Polyol compound, polyvalent amine compound and polyurethane bond-containing polyvalent isocyanate compound (where B component is 16 to 36% by mass with respect to the sum of A component and B component)
and C.I. applying a coating liquid containing a solvent, evaporating the solvent, chemically reacting the polyol compound, the amine compound and the polyurethane bond-containing polyvalent isocyanate compound to form a second layer;
applying a coating liquid containing a polyurethane resin and a solvent as a first layer on the surface of the second layer;
A polishing sheet characterized by being wet-coagulated in a coagulation bath to form a plurality of pores inside, washed and dried, and then subjected to buffing to open the surface portions of the pores in the first layer. Production method.

The abrasive sheet of the present invention has any one of the following preferred embodiments.
The fifth layer is nonwoven.
The thickness of the third layer is 75-250 μm.
The thickness of the second layer is 10-30 μm.
The fifth layer is a microfiber nonwoven fabric.
Any one of the above polishing sheets, wherein the polyurethane resin contained in the second layer is the same as the polyurethane resin contained in the first layer.

The method for producing a polishing sheet of the present invention has the following preferred embodiments.
In the second layer, the ratio of urea bonds to urethane bonds in the polyurethane urea resin obtained from the chemical reaction of the polyol compound, amine compound and polyurethane bond-containing polyvalent isocyanate compound is 5 to 18%.

According to the present invention, in a reconveyor wafer, glass, a compound semiconductor substrate, a hard disk substrate, or the like, it is possible to obtain a higher-quality polished surface with less edge sagging at the edge portion and fewer fine defects, for mirror polishing. A suitable polishing sheet can be obtained.

A polishing sheet and a method for producing the same according to the present invention will be described.

In the present invention, the first layer, which is a polyurethane resin porous layer having an open surface and a plurality of teardrop-like pores therein, can be formed into a soft porous layer by wet coagulation of polyurethane resin. It can be produced by applying a polyurethane resin solution in which polyurethane is dissolved in an organic solvent to the surface of the second layer, and solidifying and regenerating the polyurethane resin in the aqueous coagulating liquid. By grinding the surface of the polyurethane resin porous layer produced by this production method with sandpaper or the like, the pores can form openings on the surface of the layer. The porous layer produced by the wet coagulation method has teardrop-shaped pores extending inward from the opening. A range of ~900 μm is preferred. The opening diameter of the opening is similarly set according to the substrate to be polished and the polishing process, but is preferably in the range of 10 to 150 μm.

The polyurethane resin that can be used for the porous layer of the present invention is a polymer having a urethane bond obtained by polyaddition of a prepolymer having a plurality of terminal active hydrogens, particularly hydroxyl groups, and a compound having a plurality of isocyanate groups. is.

Examples of prepolymers having a plurality of active hydrogens at their terminals include polyester-based, polyether-based, polycarbonate-based and polycaprolactane-based main chain skeletons.

Solvents for the polyurethane solution for forming the first layer include N,N-dimethylformamide (hereinafter "DMF"), N,N-dimethylacetamide, dimethylsulfoxide, tetrahydrofuran, dioxane and N-methylpyrrolidone. is used. DMF is suitable as a solvent for dissolving the polyurethane resin.

The polyurethane solution may suitably contain other resins such as polymers such as polyvinyl chloride, polyester resins, polyethersulfones and polysulfones. The polyurethane solution may also contain, if necessary, carbon, organic pigments, surface active agents that reduce surface tension, and water repellent agents capable of imparting water repellency.

The second layer includes polyurethane resin and polyurethane urea resin.

Examples of the polyurethane contained in the second layer include polyurethanes similar to those described for the first layer. For enhancing the adhesion between the first layer and the second layer, it is preferable to use a polyurethane resin containing the same repeating structural units of the polymer as the polyurethane resin of the first layer. Furthermore, it is preferable to use the same polyurethane resin.

The polyurethane urea resin contained in the second layer has a ratio of urea bonds to urethane bonds of 5% to 18%. In this polyurethane urea resin, a polyol compound, a polyvalent amine compound, and a urethane bond-containing polyisocyanate compound react, and the isocyanate group of the urethane bond-containing polyvalent isocyanate compound reacts with the hydroxyl group of the polyol compound and the amino group of the amine compound. Then, it becomes a polymer and becomes a polyurethane urea resin having a urethane bond and a urea bond.
A polyol compound as a raw material of a polyurethane urea resin is a compound having two or more alcoholic hydroxyl groups in its molecule. Specifically, the following are exemplified.
diol compounds such as ethylene glycol and butylene glycol;
a triol compound,
polyether polyol compounds such as polytetramethylene glycol, polyester polyol compounds such as reaction products of ethylene glycol and adipic acid and butylene glycol and adipic acid,
Polycarbonate polyol compounds, polycaprolactone polyol compounds.

Among these, polytetramethylene glycol is preferable in that mechanical toughness can be obtained, and polytetramethylene glycol having a number average molecular weight of about 500 to 5,000 is more preferable, and polytetramethylene glycol of about 1,000 is more preferable.

A polyvalent amine compound used as a raw material for a polyurethane urea resin is a compound having two or more amino groups in its molecule. The polyamine compound acts as a cross-linking agent, partly reacts with the polyisocyanate compound to form a hard segment, the hard segment acts as a pseudo-cross-linking part, and partly contains a polyurethane bond, which will be described later. A hard segment is formed in the polymer chain by combining with the main chain terminal group of the isocyanate compound (soft segment portion) to produce a polyurethane urea resin having a block copolymer of the hard segment and the soft segment. This hard segment acts like a pseudo cross-linking agent.

Specific examples of polyamine compounds include aliphatic and aromatic polyamine compounds, particularly diamine compounds. The following are exemplified. ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane (methylenebis-o-chloroaniline), methylene-o-chloro Aniline. Also polyamine compounds having structures similar to these.

In addition, the polyamine compound may have a hydroxyl group, and examples of such amine compounds include 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxy Diethylpropylenediamine, 2-hydroxydipropylethylenediamine, di-2-hydroxypropylethylenediamine and the like can be mentioned. As the polyamine compound, diamine compounds are preferable in terms of high toughness, methylenebis-o-chloroaniline and methylene-o-chloroaniline analogous structural compounds, diaminodiphenylsulfone are more preferable, methylenebis-o-chloroaniline and methylene-o - analogous structural compounds of chloroanilines are particularly preferred.

The urethane bond-containing polyvalent isocyanate compound is a compound obtained by reacting the above polyol compound and polyisocyanate compound, and has a polyurethane structure and a plurality of isocyanate groups. As the polyurethane bond-containing isocyanate compound, a commercially available one may be used, or a compound synthesized by reacting a polyisocyanate compound and a polyol compound may be used. The reaction is not particularly limited, and an addition polymerization reaction may be performed using a method and conditions known in the production of polyurethane. For example, to a polyol compound heated to 45°C, add a polyvalent isocyanate compound heated to 55°C while stirring in a nitrogen atmosphere, raise the temperature to 85°C after 40 minutes, and further react at 85°C for 60 minutes. It can be manufactured by a method such as The weight average molecular weight of the polyurethane bond-containing isocyanate compound is not particularly limited, but is preferably 500 to 2,000, more preferably 1,000 to 1,500 from the viewpoint of toughness.

A polyvalent isocyanate compound is used as a raw material for the polyurethane-bonded polyisocyanate, and is a compound having two or more isocyanate groups in the molecule. The following compounds are exemplified.
m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6-tolylene diisocyanate, p-phenylene diisocyanate, 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, naphthalene-1,4-diisocyanate, diphenylmethane-4 ,4'-diisocyanate, 4,4'-methylene-(cyclohexyl isocyanate), 3,3'-dimethoxy-4,4'-biphenyl diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, xylylene- 1,4-diisocyanate, 4,4'-diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene xylene-1,4-diisocyanate, p-phenylene diisocyanate, xylylene-1,4-diisocyanate, ethylidine diisothiocyanate.

The polyurethane urea resin contained in the second layer has a ratio of the number of urea bonds to the number of urethane bonds of 5% to 18%. This ratio can be obtained by adjusting the charged amounts of the polyol compound, the amine compound and the urethane bond-containing polyisocyanate compound.
In a preferred embodiment, the mass ratio of the polyurethane urea resin is in the range of 16 to 36% with respect to the sum of the polyurethane resin and the polyurethane urea resin contained in the second layer.

If the ratio of urea bonds to urethane bonds in the polyurethane urea resin contained in the second layer of the present invention is too small, peeling will easily occur at the interface between the second layer and the polyester film that is the third layer. If the ratio of urea bonds to urethane bonds is too large, peeling is likely to occur at the interface between the first layer and the second layer.

A preferred method for forming the second layer in the present invention is to apply A.P. a polyurethane resin component of the first layer;B. "Polyol compound, polyvalent amine compound and polyurethane bond-containing polyvalent isocyanate compound" and C.I. In this method, a solvent-containing coating liquid is applied, the solvent is evaporated, and a polyol compound, an amine compound, and a polyurethane bond-containing polyvalent isocyanate compound are chemically reacted. Here, the B component is preferably 16 to 36% by mass, more preferably 20 to 33% by mass, based on the sum of the A component and the B component.

When this ratio is small, peeling is likely to occur at the interface between the second layer and the polyester film of the third layer. Moreover, when this ratio is large, the second layer and the first layer are likely to separate. A more preferable mass ratio of the polyurethane urea resin component of the second layer is in the range of 20 to 33%. In the preferred method of forming the second layer, each raw material of the B component forms a polyurethane urea resin by chemical reaction, and the composition of each raw material is such that the ratio of the number of urea bonds to the number of urethane bonds is 5 to 18%. is preferred.
The polyester film of the third layer is in the form of a film of polyester resin. There are three types of polyester film: the type with no surface treatment, the type with easy adhesion treatment, and the type with release treatment. The peel strength at the interface tended to be small. Even if a type in which a polyester film is treated for easy adhesion is used, or a type in which the first layer is directly formed, further peel strength at the interface is required. By interposing the second layer of the present invention between the polyester film of the first layer and the third layer, the peel strength of the interface between the polyester film and the second layer increases, and the second layer The peel strength at the interface between the layer and the first layer is also increased.
The thickness of the polyester film of the third layer is preferably 75 µm or more and 250 µm or less. If the thickness is less than 75 μm, the edge sag of the substrate to be polished becomes large, which is not preferable. If the thickness exceeds 250 μm, fine defects increase and it is difficult to obtain the quality of the substrate to be polished, probably reflecting the influence of deterioration of the conformability of the fifth cushion layer.

The fourth layer is a layer of adhesive that bonds the polyester film of the third layer and the fifth layer. Examples of this adhesive include acrylic resin adhesives, α-olefin adhesives, urethane resin adhesives, and hot melt adhesives made of thermoplastic resins. Urethane resin adhesives and hot melt adhesives are preferred. It is preferably used in that it can be adhered in a short time. As for the urethane resin-based adhesive, a method of dissolving the adhesive in various organic solvents and dry-coating with a laminator can be given as a suitable example.

As hot melt adhesives, Hitachi Kasei Polymer Co., Ltd.'s "Hibon" (registered trademark) series, Mitsui Takeda Chemicals Co., Ltd.'s "Takemelt" (registered trademark) MA series, Toa Gosei Co., Ltd.'s "Aron Melt" ( R series, Nitta Gelatin Co., Ltd. "Nittite" (registered trademark) ARX series, and Konishi Co., Ltd. "Bond" (registered trademark) KUM series.

The thickness of the adhesive is preferably 30 to 150 μm, more preferably 40 to 100 μm, in terms of maintaining a high adhesive strength.

For joining the third layer polyester film and the fifth layer cushion used in the present invention, a fourth layer adhesive is provided on the third layer, and then the fifth layer is pasted. be done. be.

The cushion layer, which is the fifth layer of the present invention, preferably has a compression modulus of 0.10 to 0.50 MPa. Furthermore, 0.2 to 0.45 MPa is preferable. Examples of the cushion layer include nonwoven fabrics and soft rubber foam sheets. Nonwoven fabrics are preferred because of their low volume modulus and good followability. Furthermore, ultrafine fiber nonwoven fabrics with a fiber diameter of about several μm are more preferable as a cushion layer in that they have a low volume modulus and uniform in-plane followability. A preferred range of fiber diameter is 1 to 6 μm. If the compressive elastic modulus is less than 0.10 MPa, the edge sag of the substrate to be polished increases, which is not preferable. If the compression elastic modulus of the cushion layer is large, the surface of the first layer tends to be difficult to uniformly contact the entire surface of the substrate to be polished, or fine defects tend to occur in the polishing result, which is not preferable.

As a preferred method for manufacturing the abrasive sheet of the present invention, the adhesive is applied to the third layer, polyester film, and dried to form the fourth layer, the adhesive layer. Then, the third layer and the fifth layer are laminated with the cushion layer, and the surface of the polyester film of the third layer opposite to the adhesive layer is coated with a liquid containing the compound shown later, and the solvent to form a second layer by chemically reacting the polyol compound, the amine compound, and the polyurethane bond-containing polyisocyanate compound, and applying the polyurethane resin and the solvent as the first layer on the surface of the second layer. A method in which a plurality of pores are formed in the interior by coating the containing material, wet-coagulating in a coagulating bath, and after washing and drying, the surface is buffed to open the surface portion of the first layer of the pores. be. Here, the coating liquid for the second layer preferably contains the following A to B.
A. polyurethane resin,
B. Polyol compound, polyvalent amine compound and polyurethane bond-containing polyvalent isocyanate compound (where B component is 16 to 36% by mass with respect to the sum of A component and B component)
and C.I. After applying the solvent second layer coating solution and drying it, it is better to wait for a while before coating the first layer to increase the peel strength between the first layer and the second layer, resulting in better adhesion. This is preferable because it stabilizes the force. In addition, the third layer is formed after the cushion layer, which is the fifth layer, is attached to the polyester film, which is the third layer, via the adhesive layer, which is the fourth layer. When the laminate of the fifth layer is wound up from the outer layer, the cushion layer and the third layer come into contact with each other, which is preferable because blocking does not occur.

Examples of means for applying the coating liquid containing the resin of the first layer to the surface of the second layer adjacent to the polyester film of the third layer include a roll coater, a knife coater, a knife over roll coater and a die coater. etc. After the coating liquid containing the resin of the first layer is applied, a solvent that has affinity with DMF but does not dissolve the resin of the first layer is used in the coagulation bath for forming the soft porous layer. . Generally, water or a mixed solution of water and DMF is used.

As a method for buffing the surface of the first layer, sandpaper may be wound around a rotating roll, and the surface of the first layer may be ground by bringing the surface of the rotating sandpaper into contact with the surface. As a method for managing an appropriate amount of grinding, it is possible to appropriately perform by monitoring the resistance value of the shaft of the rotating roll around which the sandpaper is wound. Then, a substrate having a glossy surface can be completed by polishing a substrate to be polished with the polishing sheet of the present invention or with the polishing sheet obtained by the manufacturing method of the polishing sheet of the present invention.

The following examples further illustrate details of the present invention. However, the present invention should not be construed as being limited by this example. Polishing evaluation and each measurement were performed as follows.

[Measurement of compression modulus]
Measurement was performed under the following conditions using an automated compression tester (KESFB3-AUTO-A) manufactured by Kato Tech. Calculated from the strain rate of 16 gf/cm ² (0.00157 MPa) and 40 gf/cm ² (0.00392 ^MPa ) when pressurized from 0 gf/cm ² to 50 gf/cm 2 using this machine (measured 5 times average value).

・ Strain rate: (initial thickness - thickness at predetermined pressure) / initial thickness ・ Compressive modulus: (0.00392 - 0.00157) / (strain rate at 40 gf / cm ² - strain rate at 16 gf / cm ² )
[MPa]
・Indenter area: 1.0 cm ²
・Indenter speed: 0.02mm/sec
・Upper limit load: 50 gf/cm.

[Polishing evaluation]
Using a polishing machine (model: SPP600) manufactured by Okamoto Machine Tool Works, an edged wafer was first polished with SUBA800, and an 8-inch silicon bare wafer was used. were prepared and evaluated under the following conditions.
・Platen rotation: 46 rpm
・Wafer head rotation: 49 rpm
・Head load: 200 g/cm ²
・ Slurry volume: 700 ml / min (slurry: colloidal silica slurry abrasive grain concentration 1%)
- Polishing time: 15 minutes.

- After polishing 100 dummy wafers, the 8-inch silicon bare wafer was polished.

[Defects on Silicon Wafer]
The surface of the silicon wafer polished under the above polishing conditions was analyzed with SURFSCAN SP-3 manufactured by KLA-Tencor to determine the number of defects of 0.026 μm.

[Edge sagging of silicon wafer edges]
Under the above polishing conditions, edge sagging of 2 mm perimeter of the edge portion was measured with ZYGO NewView7300.
[Synthesis of urethane bond-containing polyisocyanate compound]
279 parts by mass of 2,4-tolylene diisocyanate, 284 parts by mass of polytetramethylene ether glycol having a number average molecular weight of about 1000, and 64 parts by mass of diethylene glycol are reacted to obtain an isocyanate group content of 9.6% by mass. A urethane bond-containing polyisocyanate compound (1) was synthesized.

[Preparation of mixture of polyol compound and amine compound]
Mixture of polyol compound and amine compound (1):
100 parts by mass of polytetramethylene ether glycol having a number average molecular weight of about 1000 is heated to 120 ° C., methylene bis-o-chloroaniline is heated to 120 ° C. to liquefy, 1.40 parts by mass is mixed, and polyol A mixture (1) of a compound and an amine compound was prepared.

Mixture of polyol compound and amine compound (2):
100 parts by mass of polytetramethylene ether glycol having a number average molecular weight of about 1000 is heated to 120°C, and methylene bis-o-chloroaniline is heated to 120°C to liquefy. .96 parts by mass were added to prepare a mixture (2) of a polyol compound and an amine compound.

Mixture of polyol compound and amine compound (3):
100 parts by mass of polytetramethylene ether glycol having a number average molecular weight of about 1000 is heated to 120 ° C., methylene bis-o-chloroaniline is heated to 120 ° C. to make it liquid, and 4.71 parts by mass are mixed to obtain a polyol. A mixture (3) of compound and amine compound was prepared.

Mixture of polyol compound and amine compound (4):
100 parts by mass of polytetramethylene ether glycol having a number average molecular weight of about 1000 is heated to 120 ° C., and 0.82 parts by mass of methylene bis-o-chloroaniline liquefied by heating to 120 ° C. is mixed to obtain a polyol. A mixture (4) of compound and amine compound was prepared.

Mixture of polyol compound and amine compound (5):
100 parts by mass of polytetramethylene ether glycol having a number average molecular weight of about 1000 is heated to 120 ° C., and 6.26 parts by mass of methylene bis-o-chloroaniline liquefied by heating to 120 ° C. is mixed to obtain a polyol. A mixture (5) of compound and amine compound was prepared.

Examples and comparative examples are described below. Table 1 shows the composition of the polishing sheet, and Table 2 shows the polishing properties of the resulting polishing sheet.

[Example 1]
An acrylic adhesive for the fourth layer was applied to a 75 μm polyester film for the third layer so that the layer thickness was 50 μm, and fiber cotton with a fiber diameter of 14 μm for the fifth layer was used. A nonwoven fabric (thickness: 0.9 mm) having a compression modulus of 0.25 MPa was adhered.

100 parts by mass of a dimethylformamide solution of a polyester-based polyurethane having a solid content concentration of 30%, 60 parts by mass of a dimethylformamide solvent, 1.5 parts by mass of a foaming aid, and 10 parts by mass of a dimethylformamide solution containing 20% carbon black as a pigment. A coating liquid for forming a soft porous layer, which is the first layer, was prepared in advance by dispersing each part.

20.60 parts by mass of the same polyester polyurethane as the first layer, 3.78 parts by mass of a urethane bond-containing polyisocyanate compound (1), and 4.16 parts by mass of a mixture of a polyol compound and an amine compound (1) And 257 parts by mass of dimethylformamide are mixed to prepare a coating solution, which is applied to the surface of the polyester film which is the third layer of the laminate of the third layer to the fifth layer and dried, A second layer was formed with a thickness of 45 μm. The ratio of the number of urea bonds of the polyurethane urea resin to the number of urethane bonds in the second layer was 5.26%, and the mass ratio of the polyurethane urea resin in the entire resin was 27.82%.

The coating liquid for forming the first layer is applied to the surface of the second layer, immersed in a coagulation bath of a 10% aqueous solution of dimethylformamide for wet coagulation, and washed with water to remove dimethylformamide. and dried to form a soft porous layer with a thickness of 550 μm as the first layer. The surface of the first layer was ground with sandpaper to obtain an abrasive sheet.

Observation of the cross section of the polishing sheet obtained revealed that a large number of teardrop-like pores were formed in the first layer, and pores having an average diameter of 40 μm were formed in the surface layer of the pores. The obtained polishing sheet was used to polish a silicon wafer using a polishing machine. There was no delamination with the polishing sheet, and the polishing was completed without problems. As shown in Table 2, the number of defects and edge sagging of the edge portion were good.

[Example 2]
An acrylic adhesive as the fourth layer was applied to a 100 μm polyester film as the third layer at 60 μm, and a fiber cotton with a fiber diameter of 14 μm as the fifth layer was used. A nonwoven fabric (thickness: 1.2 mm) was adhered.

The same coating liquid as the first layer as in Example 1 was prepared in advance.

23.01 parts by mass of the same polyester polyurethane as the first layer, 2.24 parts by mass of a urethane bond-containing polyisocyanate compound (1), and 2.37 parts by mass of a mixture of a polyol compound and an amine compound (2) and 249 parts by mass of dimethylformamide to prepare a coating solution, which is the third layer of the laminate of the third to fifth layers, and is applied to the surface of the polyester film and dried. , a second layer was formed with a thickness of 35 μm. In the second layer, the ratio of the number of urea bonds in the polyurethane urea resin to the number of urethane bonds was 11.11%, and the weight ratio of the polyurethane urea resin in the entire resin was 16.67%. The surface of the second layer is coated with a coating liquid for forming the porous layer as the first layer, immersed in a coagulation bath of a 10% aqueous solution of dimethylformamide for wet coagulation, and washed with water. The dimethylformamide was removed by using a knife and dried to form a soft porous layer having a thickness of 450 μm as the first layer. The surface of the first layer was ground with sandpaper to obtain an abrasive sheet.

Observation of the cross section of the polishing sheet obtained revealed that a large number of teardrop-like pores were formed in the first layer, and pores having an average diameter of 50 μm were formed in the surface layer of the pores. The obtained polishing sheet was used to polish a silicon wafer using a polishing machine. In particular, there was no delamination on the polishing sheet, and the polishing was completed without problems. As shown in Table 2, the number of defects and edge sagging of the edge portion were good.

[Example 3]
A polyester film of 245 μm as the third layer is coated with an acrylic adhesive as the fourth layer with a thickness of 40 μm, and a fiber cotton with a fiber diameter of 14 μm as the fifth layer is used. A nonwoven fabric (thickness: 0.7 mm) was adhered.

100 parts by mass of a dimethylformamide solution of a polyester polyurethane with a solid content concentration of 30%, 60 parts by mass of a dimethylformamide solvent, 1.5 parts by mass of a foaming aid, and 10 parts by mass of a dimethylformamide solution containing 20% carbon black as a pigment. Each part was dispersed to prepare a coating liquid for forming a soft porous layer as a first layer.

23.73 parts by mass of the same polyester polyurethane as the first layer, 6.33 parts by mass of the urethane bond-containing polyisocyanate compound (3), and 6.44 parts by mass of the mixture (3) of the polyol compound and the amine compound and 328.5 parts by mass of dimethylformamide to prepare a coating solution, which is applied to the surface of the polyester film, which is the third layer of the laminate of the third to fifth layers, and dried. Then, a second layer was formed with a thickness of 60 μm. In the second layer, the ratio of the number of urea bonds in the polyurethane urea resin to the number of urethane bonds was 17.65%, and the weight ratio of the polyurethane urea resin in the entire resin was 34.98%.

The coating liquid for forming the first layer is applied to the surface of the second layer, immersed in a coagulation bath of a 10% aqueous solution of dimethylformamide for wet coagulation, and washed with water to remove dimethylformamide. and dried to form a soft porous layer with a thickness of 600 μm as the first layer. The surface of the first layer was ground with sandpaper to form an abrasive sheet. The surface opening diameter was 60 μm on average.

Observation of the cross section of the obtained polishing sheet revealed that a large number of teardrop-like pores were formed in the first layer, and pores having an average diameter of 60 μm were formed in the surface layer portion of the pores. The obtained polishing sheet was used to polish a silicon wafer using a polishing apparatus. The polishing sheet had no delamination and could be polished without problems. As shown in Table 2, the number of defects and edge sagging of the edge portion were good.

[Comparative Example 1]
All the same conditions except that the fiber diameter was the same instead of the nonwoven fabric used in Example 1, the density was changed as shown in Table 1, and the compression modulus was changed to 0.09 MPa (thickness: 0.9 mm). to prepare a polishing sheet.

The obtained polishing sheet was used to polish a silicon wafer using a polishing machine. The polishing sheet did not cause delamination and could be polished without any particular problems. However, as shown in Table 2, the number of defects and edge sagging of the edge portion were poor.

[Comparative Example 2]
All the same conditions except that the fiber diameter was the same instead of the nonwoven fabric used in Example 1, the density was changed as shown in Table 1, and the compression elastic modulus was changed to 0.57 MPa (thickness: 0.8 mm). to prepare a polishing sheet.

The obtained polishing sheet was used to polish a silicon wafer using a polishing apparatus. The polishing sheet did not peel off, and polishing was completed without any particular problem. As for the number of defects and the sagging of the edge portion, as shown in Table 2, the number of defects was large and the film was unsatisfactory.
[Comparative Example 3]
20.61 parts by mass of the polyester-based polyurethane used in the first layer of Example 1, and the polyurethane bond-containing isocyanate compound (1), 1 .77 parts by mass, a mixture (1) of a polyol compound and an amine compound, 1.95 parts by mass, and dimethylformamide, and 219 parts by mass are mixed to prepare a coating liquid, and the third layer to the fifth layer was applied to the surface of the polyester film, which was the third layer of the laminate of the layers, and dried to form a second layer having a thickness of 45 μm. In the second layer, the ratio of the number of urea bonds in the polyurethane urea resin to the number of urethane bonds was 5.26%, and the mass ratio of the polyurethane urea resin in the entire resin was 15.29%. A polishing sheet was produced under the same conditions as in Example 1 except for the above.

The obtained polishing sheet was used to polish a silicon wafer using a polishing machine. During the polishing of 100 dummy wafers, the polishing sheet was peeled off from the second layer of the polyester film, which was the third layer, and could not be properly polished.
[Comparative Example 4]
6. 20.55 parts by mass of the polyester-based polyurethane used in the first layer of the example, and the polyurethane bond-containing isocyanate compound (1); 05 parts by mass, 6.66 parts by mass of the mixture (1) of a polyol compound and an amine compound, dimethylformamide, and 299 parts by mass are mixed to prepare a coating liquid, and the third layer to the fifth layer. A second layer having a thickness of 45 μm was formed by coating and drying on the surface of the polyester film, which was the third layer of the laminate of layers. In the second layer, the ratio of the number of urea bonds in the polyurethane urea resin to the number of urethane bonds was 5.26%, and the mass ratio of the polyurethane urea resin in the entire resin was 38.21%. A polishing sheet was produced under the same conditions as in Example 1 except for the above.

The obtained polishing sheet was used to polish a silicon wafer using a polishing apparatus. As for the polishing sheet, during the polishing of 100 dummy wafers, the porous layer peeled off at the interface between the first layer and the second layer in some parts, and the polishing could not be properly polished. .

[Example 4]
Instead of the nonwoven fabric in Example 2, as shown in Table 1, a nonwoven fabric made of ultrafine fibers with a fiber diameter of 4 μm and a compressive elastic modulus of 0.30 MPa (thickness: 0.95 mm) was used, and the other conditions were the same as in Example 2. A polishing sheet was prepared in the same manner.

The obtained polishing sheet was used to polish a silicon wafer using a polishing machine. The polishing sheet did not cause delamination, and polishing was possible without any particular problems. As shown in Table 2, the number of defects and edge sagging of the edge portion were good.

[Example 5]
A polishing sheet was produced under the same conditions as in Example 1, except that the polyester film used in Example 1 had a thickness of 60 μm. The obtained polishing sheet was used to polish a silicon wafer using a polishing machine. The polishing sheet did not peel off, and polishing was completed without any particular problems. Table 2 shows the results of the number of defects and edge sagging of the edge portion.

[Example 6]
A polishing sheet was produced under the same conditions as in Example 1, except that the polyester film used in Example 1 had a thickness of 300 μm. The obtained polishing sheet was used to polish a silicon wafer using a polishing apparatus. The polishing sheet did not peel off, and polishing was completed without any particular problem. Table 2 shows the results of the number of defects and edge sagging of the edge portion.

[Example 7]
A polishing sheet was produced under the same conditions as in Example 1, except that a flexible foamed polyurethane sheet (thickness: 0.95 mm) having a compressibility of 0.3 MPa was used instead of the nonwoven fabric used in Example 1. The obtained polishing sheet was used to polish a silicon wafer using a polishing machine. The polishing sheet did not peel off, and polishing was completed without any particular problem. Table 2 shows the results of the number of defects and edge sagging of the edge portion.

[Comparative Example 5]
24.01 parts by mass of the polyester polyurethane used for the first layer in Example 1, 3.78 parts by mass of the polyurethane bond-containing isocyanate compound (1), and the mixture of the polyol compound and the amine compound (4), 4 .22 parts by mass and 288 parts by mass of dimethylformamide are mixed to prepare a coating liquid, which is the third layer of the laminate of the third to fifth layers, which is the polyester film surface. Then, a second layer was formed with a thickness of 50 μm. In the second layer, the ratio of the number of urea bonds in the polyurethane urea resin to the number of urethane bonds was 3.09%, and the mass ratio of the polyurethane urea resin to the entire resin was 25.00%. A polishing sheet was produced under the same conditions as in Example 1 except for the above conditions.

The obtained polishing sheet was used to polish a silicon wafer using a polishing apparatus. As for the polishing sheet, during the polishing of 100 dummy wafers, peeling occurred in part between the third layer, the polyester film, and the second layer, and polishing could not be performed.

[Comparative Example 6]
In Example 1, 26.80 parts by mass of polyester polyurethane as the resin of the first layer, 3.78 parts by mass of isocyanate compound containing polyurethane bond (1), mixture of polyol compound and amine compound (5), 3.78 parts by mass and 309 parts by mass of dimethylformamide are mixed to prepare a coating solution, which is the third layer of the laminate of the third to fifth layers, which is the polyester film surface. After drying, a second layer was formed with a thickness of 50 μm. In the second layer, the ratio of the number of urea bonds to the number of urethane bonds in the polyurethane urea resin was 20.48%, and the mass ratio of the polyurethane urea resin in the entire resin was 22.00%. A polishing sheet was produced under the same conditions as in Example 1 except for the above conditions.

The obtained polishing sheet was used to polish a silicon wafer using a polishing machine. During the polishing of 100 dummy wafers, the first layer of the polishing sheet was peeled off at a portion of the interface with the second layer, and polishing could not be performed.

Claims (9)

Abrasive sheets laminated adjacently in order from the first layer to the fifth layer,
The first layer is a polyurethane resin porous layer having a plurality of pores with an open surface and a teardrop-shaped interior,
The second layer contains a polyurethane resin and a polyurethane urea resin having a ratio of the number of urea bonds to the number of urethane bonds of 5 to 18%. The mass ratio is 16 to 36%,
The third layer is a polyester film,
the fourth layer is an adhesive layer,
The fifth layer is a cushion layer having a compression modulus of 0.10 to 0.50 MPa.
polishing sheet. 2. The abrasive sheet of claim 1, wherein the fifth layer is nonwoven. 3. The abrasive sheet according to claim 1, wherein the third layer has a thickness of 75-250 μm. 4. The abrasive sheet according to any one of claims 1 to 3, wherein the second layer has a thickness of 10 to 30 µm. 5. The abrasive sheet according to any one of claims 1 to 4, wherein the fifth layer is a microfiber nonwoven fabric. 6. The polishing sheet according to any one of claims 1 to 5, wherein the polyurethane resin contained in the second layer is the same as the polyurethane resin contained in the first layer. A method for producing an abrasive sheet in which the first layer to the fifth layer are adjacently laminated in order, comprising:
Adhesive is applied to the polyester film that will be the third layer and dried to form the adhesive layer that is the fourth layer, and the third layer and the cushion layer of the fifth layer are formed through the fourth layer. pasted together,
On the side of the third layer opposite the fourth layer,
A. polyurethane resin,
B. Polyol compound, polyvalent amine compound and polyurethane bond-containing polyvalent isocyanate compound (where B component is 16 to 36% by mass with respect to the sum of A component and B component)
and C.I. applying a coating liquid containing a solvent, evaporating the solvent, chemically reacting the polyol compound, the amine compound and the polyurethane bond-containing polyvalent isocyanate compound to form a second layer;
applying a coating liquid containing a polyurethane resin and a solvent as a first layer on the surface of the second layer;
A polishing sheet characterized by being wet-coagulated in a coagulation bath to form a plurality of pores inside, washed and dried, and then subjected to buffing to open the surface portions of the pores in the first layer. Production method. Claim 7, wherein the ratio of urea bonds to urethane bonds in the polyurethane urea resin obtained from the chemical reaction of the polyol compound, amine compound and polyurethane bond-containing polyvalent isocyanate compound contained in the second layer is 5 to 18%. manufacturing method of the polishing sheet. A method for manufacturing a substrate, comprising polishing a substrate to be polished with the polishing sheet according to any one of claims 1 to 6 or the polishing sheet obtained by the manufacturing method according to claim 7 or 8.