Method for polishing silicon wafer and polishing liquid therefor
First Claim
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1. A method for polishing silicon wafers comprising the steps of:
- eliminating a native oxide film formed on a silicon wafer by using an alkaline aqueous solution containing free abrasive grains as a primary polishing liquid;
simultaneously rough polishing a surface and a rear surface of the silicon wafer with a double-sided polisher having a carrier plate in which the silicon wafer is housed, an upper surface plate in which a hard abrasive cloth is pasted on a lower surface, and a lower surface plate in which the hard abrasive cloth is pasted on a top surface, wherein the upper surface plate and the lower surface plate hold the carrier plate respectively from above and below therebetween, so as to relatively rotate the silicon wafer and the hard abrasive cloth while supplying a secondary polishing liquid in which hydroxyethyl cellulose is added to an alkaline aqueous solution with no free abrasive grains, to the hard abrasive cloth; and
applying final polishing on at least the rough polished surface of the silicon wafer, wherein;
the hard abrasive cloth has Shore-D hardness of 70 to 90 and a compressibility of 1 to 5%,a polishing rate of the silicon wafer in the rough polishing is 0.05 to 1 μ
m per minute, andthe final polishing is carried out with a soft abrasive cloth and is performed with a third polishing liquid containing free abrasive grains.
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Abstract
Disclosed is a method for polishing a silicon wafer, wherein a surface to be polished of a silicon wafer is rough polished, while supplying a polishing liquid, which is obtained by adding a water-soluble polymer to an aqueous alkaline solution that contains no free abrasive grains, to a polishing cloth. Consequently, the surface to be polished can be polished at high polishing rate and the flatness of the edge portion including roll-off and roll-up can be controlled.
19 Citations
9 Claims
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1. A method for polishing silicon wafers comprising the steps of:
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eliminating a native oxide film formed on a silicon wafer by using an alkaline aqueous solution containing free abrasive grains as a primary polishing liquid; simultaneously rough polishing a surface and a rear surface of the silicon wafer with a double-sided polisher having a carrier plate in which the silicon wafer is housed, an upper surface plate in which a hard abrasive cloth is pasted on a lower surface, and a lower surface plate in which the hard abrasive cloth is pasted on a top surface, wherein the upper surface plate and the lower surface plate hold the carrier plate respectively from above and below therebetween, so as to relatively rotate the silicon wafer and the hard abrasive cloth while supplying a secondary polishing liquid in which hydroxyethyl cellulose is added to an alkaline aqueous solution with no free abrasive grains, to the hard abrasive cloth; and applying final polishing on at least the rough polished surface of the silicon wafer, wherein; the hard abrasive cloth has Shore-D hardness of 70 to 90 and a compressibility of 1 to 5%, a polishing rate of the silicon wafer in the rough polishing is 0.05 to 1 μ
m per minute, andthe final polishing is carried out with a soft abrasive cloth and is performed with a third polishing liquid containing free abrasive grains. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for polishing silicon wafers comprising the steps of:
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rough polishing at least the surface serving as a surface to be polished between a surface and a rear surface of the silicon wafer so as to relatively rotate a silicon wafer and an abrasive cloth; and applying final polishing on at least the rough polished surface of the silicon wafer after the rough polishing, the method wherein the rough polishing is split into a first-step polishing which is carried out while supplying a first-step polishing liquid in which a water-soluble polymer is added to an alkaline aqueous solution with no free abrasive grains to the abrasive cloth, and a second-step polishing which is carried out while supplying a second-step polishing liquid in which a water-soluble polymer is added to an alkaline aqueous solution with no free abrasive grains to the abrasive cloth after the first-step polishing, and concentration of the water-soluble polymer in the second-step polishing liquid is made higher than the concentration of the water-soluble polymer in the first-step polishing liquid.
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Specification