METHOD OF POLISHING A LOW-K SUBSTRATE
Disclosed is a method of chemically-mechanically polishing a substrate. The method comprises, consists of, or consists essentially of (a) contacting a substrate containing a low-k dielectric composition, which includes less than about 80% by weight of carbon, with a polishing pad and a chemical-mechanical polishing composition comprising water and abrasive particles having a positive surface charge, wherein the polishing composition has a pH of from about 3 to about 6; (b) moving the polishing pad and the chemical-mechanical polishing composition relative to the substrate; and (c) abrading at least a portion of the substrate to polish the substrate. In some embodiments, the low-k dielectric composition is carbon-doped silicon oxide.
1 . A method of chemically-mechanically polishing a substrate, the method comprising:
(a) contacting a substrate containing a low-k dielectric composition, which includes less than about 80% by weight of carbon, with a polishing pad and a chemical-mechanical polishing composition comprising water and abrasive particles having a positive surface charge, wherein the polishing composition has a pH of from about 3 to about 6;
(b) moving the polishing pad and the chemical-mechanical polishing composition relative to the substrate; and
(c) abrading at least a portion of the substrate to polish the substrate.
2 . The method of claim 1 , wherein the low-k dielectric composition includes less than about 50% by weight of carbon.
3 . The method of claim 1 , wherein the low-k dielectric composition includes less than about 30% by weight of carbon.
4 . The method of claim 1 , wherein the low-k dielectric composition is carbon-doped silicon oxide.
5 . The method of claim 4 , wherein the carbon-doped silicon oxide includes at least 35% by weight silicon.
6 . The method of claim 4 , wherein the carbon-doped silicon oxide includes at least 45% by weight oxygen.
7 . The method of claim 1 , wherein the abrasive particles have a zeta potential of at least about +10 mV.
8 . The method of claim 1 , wherein the abrasive particles include wet process ceria.
9 . The method of claim 1 , wherein the abrasive particles are present in an amount of about 0.05 wt. % to about 2 wt. % of the polishing composition.
10 . The method of claim 1 , wherein the pH of the composition is from about 3 to about 5.6.
11 . The method of claim 10 , wherein the pH of the composition is from about 5 to about 5.6.
12 . The method of claim 1 , wherein the polishing composition further comprises an ionic polymer of formula (I):
wherein X 1 and X 2 are independently selected from hydrogen, —OH, and —COOH, and wherein at least one of X 1 and X 2 is —COOH,
Z 1 and Z 2 are independently O or S,
R 1 , R 2 , R 3 , and R 4 are independently selected from hydrogen, C 1 -C 6 alkyl, and C 7 -C 10 aryl, and
n is an integer of about 3 to about 500.
13 . The method of any claim 12 , wherein X 1 and X 2 are both —COOH.
14 . The method of claim 12 , wherein Z 1 and Z 2 are both O, and R 1 , R 2 , R 3 , and R 4 are hydrogen.
15 . The method of claim 12 , wherein the ionic polymer has a molecular weight of about 500 g/mol to about 10,000 g/mol, and wherein n is an integer with a value of 8 or greater.
16 . The method of claim 12 , wherein the ionic polymer is a polyethylene glycol diacid.
17 . The method of claim 12 , wherein the ionic polymer is present in an amount of about 0.01 wt. % to about 0.5 wt. % of the polishing composition.
18 . The method of claim 1 , wherein the polishing composition further comprises a polyhydroxy aromatic compound.
19 . The method of claim 18 , wherein the polyhydroxy aromatic compound is selected from 1,3-dihydroxybenzene and 1,3,5-trihydroxybenzene.
20 . The method of claim 18 , wherein the polyhydroxy aromatic compound is 1,3,5-trihydroxybenzene.
21 . The method of claim 18 , wherein the polyhydroxy aromatic compound is present in an amount of about 0 wt. % to about 0.5 wt. % of the polishing composition.
22 . The method of claim 1 , wherein the polishing composition further comprises polyvinyl alcohol.
23 . The method of claim 22 , wherein the polyvinyl alcohol has a molecular weight of about 20,000 g/mol to about 200,000 g/mol.
24 . The method of claim 22 , wherein the polyvinyl alcohol is a branched polyvinyl alcohol.
25 . The method of claim 22 , wherein the polyvinyl alcohol is present in an amount of about 0.05 wt. % to about 0.5 wt. % of the polishing composition.
26 . The method of claim 1 , wherein abrading at least a portion of the surface of the substrate removes about 100-500 Å/min of silicon oxide depending on the pH from the surface of the substrate.
27 . The method of claim 1 , wherein the substrate further contains silicon nitride, and wherein abrading at least a portion of the surface of the substrate removes less than about 20 Å/min of silicon nitride from the surface of the substrate.