SILICON WAFER POLISHING COMPOSITION AND METHOD
A chemical mechanical polishing composition for polishing a silicon wafer comprises, consists essentially of, or consists of a water based liquid carrier, colloidal silica particles dispersed in the liquid carrier, about 0.01 weight percent to about 2 weight percent of a dipolar aprotic solvent at point of use, and a pH in a range from about 8 to about 12. A method for polishing a silicon wafer may include contacting the wafer with the above described polishing composition, moving the polishing composition relative to the wafer, and abrading the wafer to remove silicon from the wafer and thereby polish the wafer.
1 . A chemical mechanical polishing composition comprising:
an aqueous based liquid carrier;
abrasive particles dispersed in the liquid carrier;
about 0.01 weight percent to about 2 weight percent of a dipolar aprotic solvent; and
a pH in a range from about 8 to about 12.
2 . The composition of claim 1 , wherein the dipolar aprotic solvent is a member of the group consisting of acetonitrile, dimethyl sulfoxide, dimethylformamide, hexamethylphosphoramide, ethyl acetate, pyridine, and mixtures thereof.
3 . The composition of claim 1 , wherein the dipolar aprotic solvent is dimethyl sulfoxide.
4 . The composition of claim 1 , comprising from about 0.05 weight percent to about 0.5 weight percent of the dipolar aprotic solvent.
5 . The composition of claim 1 , further comprising one or more organic carboxylic acids.
6 . The composition of claim 1 , further comprising one or more polyaminocarboxylic acids.
7 . The composition of claim 1 , further comprising one or more tetraalkylammonium salts.
8 . The composition of claim 1 , further comprising one or more aminophosphonic acids.
9 . The composition of claim 1 , further comprising one or more nitrogen containing heterocyclic compounds.
10 . The composition of claim 1 , wherein the abrasive particles comprise colloidal silica abrasive particles.
11 . The composition of claim 10 , further comprising:
one or more tetraalkylammonium salts;
one or more polyaminocarboxylic acids; and
one or more nitrogen containing heterocyclic compounds.
12 . The composition of claim 11 , further comprising at least one of potassium hydroxide and potassium bicarbonate.
13 . The composition of claim 11 , wherein the dipolar aprotic solvent is dimethyl sulfoxide.
14 . A method of chemical mechanical polishing a wafer, the method comprising:
(a) contacting the wafer with a polishing composition comprising
(i) an aqueous based liquid carrier;
(ii) abrasive particles dispersed in the liquid carrier;
(iii) about 0.01 weight percent to about 2 weight percent of a dipolar aprotic solvent;
and (iv) a pH in a range from about 8 to about 12;
(b) moving the polishing composition relative to the wafer; and
(c) abrading the wafer to remove silicon from the wafer and thereby polish the wafer.
15 . The method of claim 14 ; wherein
the method uses a polishing apparatus having (i) an upper platen and a lower platen, each of said platens having a polishing pad adhered thereto, and (ii) a carrier plate having at least one holding hole for holding the wafer; and
said abrading in (c) removes silicon from opposing first and second sides of the wafer, thereby polishing the wafer.
16 . The method of claim 14 , wherein:
the wafer includes a hard laser mark; and
said abrading in (c) improves a flatness of the wafer in a peripheral region of the wafer.
17 . A method of polishing a silicon wafer, the method comprising:
(a) providing a polishing apparatus having at least one polishing pad mounted on a corresponding platen;
(b) contacting the polishing pad with a dipolar aprotic solvent to wet the polishing pad;
(c) contacting said wetted polishing pad with a polishing composition;
(d) moving the polishing composition relative to the wafer; and
(e) abrading the wafer to remove silicon from the wafer and thereby polish the wafer.
18 . The method of claim 17 , wherein the polishing composition is free of dipolar aprotic solvent.
19 . The method of claim 17 , wherein the dipolar aprotic solvent is dimethyl sulfoxide.
20 . The method of claim 17 , wherein the polishing composition comprises:
colloidal silica particles dispersed in an aqueous liquid carrier;
one or more tetraalkylammonium salts;
one or more polyaminocarboxylic acids;
one or more nitrogen containing heterocyclic compounds; and
a pH in a range from about 8 to about 12.
21 . The method of claim 17 , wherein:
the polishing apparatus comprises (i) an upper platen and lower platen, each of said platens having a polishing pad adhered thereto, and (ii) a carrier plate having at least one holding hole for holding the wafer; and
said abrading in (e) removes silicon from opposing first and second sides of the wafer, thereby polishing the wafer.
22 . The method of claim 17 , wherein:
the wafer includes a hard laser mark; and
contacting the polishing pad with the dipolar aprotic solvent in (c) and said abrading in (e) improves a flatness of the wafer in a peripheral region of the wafer.