Wafer and method of producing the same
First Claim
1. A method of producing a wafer which comprises a step of polishing a predetermined face of a wafer to flatten the predetermined face while supplying a polishing liquid onto a bonded abrasive cloth, wherein the bonded abrasive cloth comprises a urethane bonding material consisting of a soft segment having a polyfunctional isocyanate and a hard segment having a polyfunctional polyol and having an expansion ratio of 1.1-4 times and silica having an average particle size of 0.2-10 μ
- m and a hydroxy group, and a ratio of the hard segment occupied in the urethane bonding material is 40-55% as a molecular weight ratio, and a volume ratio of silica in the whole of the bonded abrasive cloth is within a range of 20-60%, and a Shore D hardness of the bonded abrasive cloth is 40-80.
1 Assignment
0 Petitions
Accused Products
Abstract
A wafer is produced at a step of polishing a predetermined face of a wafer to flatten the predetermined face while supplying a polishing liquid onto a bonded abrasive cloth, wherein the bonded abrasive cloth comprises a urethane bonding material consisting of a soft segment having a polyfunctional isocyanate and a hard segment having a polyfunctional polyol and having an expansion ratio of 1.1-4 times and silica having an average particle size of 0.2-10 μm and a hydroxy group, and has a given ratio of the hard segment occupied in the urethane bonding material, a given volume ratio of silica and a given Shore D hardness.
13 Citations
12 Claims
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1. A method of producing a wafer which comprises a step of polishing a predetermined face of a wafer to flatten the predetermined face while supplying a polishing liquid onto a bonded abrasive cloth, wherein the bonded abrasive cloth comprises a urethane bonding material consisting of a soft segment having a polyfunctional isocyanate and a hard segment having a polyfunctional polyol and having an expansion ratio of 1.1-4 times and silica having an average particle size of 0.2-10 μ
- m and a hydroxy group, and a ratio of the hard segment occupied in the urethane bonding material is 40-55% as a molecular weight ratio, and a volume ratio of silica in the whole of the bonded abrasive cloth is within a range of 20-60%, and a Shore D hardness of the bonded abrasive cloth is 40-80.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A wafer heat-treated above 1100°
- C. and having a diameter of not less than 300 mm, wherein a micro-projection(s) having a height of not less than 10 nm is not existent on a rear surface of the wafer and a flatness (GBIR) of the wafer is not more than 0.35 μ
m.
- C. and having a diameter of not less than 300 mm, wherein a micro-projection(s) having a height of not less than 10 nm is not existent on a rear surface of the wafer and a flatness (GBIR) of the wafer is not more than 0.35 μ
Specification