Method of polishing silicon wafer
AssigneeSumco Corporation
InventorShuhei Matsuda
Life of this patent
Estimating the term…
Abstract
In a method of polishing a silicon wafer, a final polishing step includes an upstream polishing step and a subsequent finish polishing step. In the upstream polishing step, as a polishing agent, a first alkaline aqueous solution containing abrasive grains with a density of 1×1014/cm3 or more is first supplied, 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/cm3 or less. In the finish polishing step, as a polishing agent, a third alkaline aqueous solution containing a water-soluble polymer and abrasive grains with a density of 5×10′13/cm3 or less is supplied. Thus, the formation of not only PIDs but also scratches with small depth can be suppressed.
Claims9
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.
Dependencies are inferred from the claim text.