US 11,890,719 B2
Method of polishing silicon wafer
Shuhei Matsuda, Tokyo (JP)
Assigned to SUMCO CORPORATION, Tokyo (JP)
Appl. No. 16/607,941
Filed by SUMCO CORPORATION, Tokyo (JP)
PCT Filed Oct. 17, 2017, PCT No. PCT/JP2017/037596
§ 371(c)(1), (2) Date Oct. 24, 2019,
PCT Pub. No. WO2019/077687, PCT Pub. Date Apr. 25, 2019.
Prior Publication US 2020/0306922 A1, Oct. 1, 2020
Int. Cl. B24B 37/005 (2012.01); B24B 37/04 (2012.01); B24B 37/10 (2012.01); B24B 37/24 (2012.01); B24B 37/34 (2012.01); B24B 37/015 (2012.01)
CPC B24B 37/245 (2013.01) [B24B 37/005 (2013.01); B24B 37/0056 (2013.01); B24B 37/044 (2013.01); B24B 37/34 (2013.01); B24B 37/015 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A method of polishing a silicon wafer, comprising a final polishing including:
an upstream polishing, using an upstream polishing unit including a first plate provided with a first polishing pad on its surface and a first polishing head, of polishing a surface of a silicon wafer by rotating the first plate and the silicon wafer held by the first polishing head while making the silicon wafer in contact with the first polishing pad and supplying a first polishing agent to the first polishing pad; and
a subsequent finish polishing, using a finish polishing unit including a second plate provided with a second polishing pad on its surface and a second polishing head, of further polishing the surface of the silicon wafer by rotating the second plate and the silicon wafer held by the second polishing head while making the silicon wafer in contact with the second polishing pad and supplying a second polishing agent to the second polishing pad,
wherein in the upstream polishing, as the first polishing agent, a first alkaline aqueous solution containing abrasive grains with a density of 1×1014 grains/cm3 or more is first supplied to perform the polishing at a polishing rate of 100 nm/min to 300 nm/min, and the supply is then switched to a supply of a second alkaline aqueous solution containing a water-soluble polymer and abrasive grains with a density of 5×1013 grains/cm3 or less to perform the polishing at a polishing rate of 5 nm/min to 20 nm/min,
after the upstream polishing, the silicon wafer is detached from the first polishing head and is transferred to the finish polishing unit while supplying water to the surface of the silicon wafer, and the silicon wafer is attached to the second polishing head, and
in the finish polishing, as the second polishing agent, a third alkaline aqueous solution containing a water-soluble polymer and abrasive grains with a density of 5×1013 grains/cm3 or less is supplied to perform the polishing at a polishing rate of 5 nm/min to 20 nm/min.