Chemical mechanical polishing of tungsten using a method and composition containing quaternary phosphonium compounds
View Patent ↗A process and composition are disclosed for polishing tungsten containing select quaternary phosphonium compounds at low concentrations to at least reduce corrosion rate of tungsten. The process and composition include providing a substrate containing tungsten; providing a stable polishing composition, containing, as initial components: water; an oxidizing agent; select quaternary phosphonium compounds at low concentrations to at least reduce corrosion rate; a dicarboxylic acid, a source of iron ions; a colloidal silica abrasive; and, optionally a pH adjusting agent; providing a chemical mechanical polishing pad, having a polishing surface; creating dynamic contact at an interface between the polishing pad and the substrate; and dispensing the polishing composition onto the polishing surface at or near the interface between the polishing pad and the substrate; wherein some of the tungsten is polished away from the substrate, and corrosion rate of tungsten is reduced.
1. A composition for chemical mechanical polishing tungsten comprising:
water;
an oxidizing agent;
a colloidal silica abrasive having a permanent negative zeta potential;
a dicarboxylic acid,
a source of iron (III) ions; and,
optionally, a pH adjusting agent;
a quaternary phosphonium compound in amounts of less than 1000 ppm but greater than 0 ppm, wherein the quaternary phosphonium compound has a formula:
wherein R 1 , R 2 , R 3 and R 4 independently comprise hydrogen; linear or branched alkyl; linear or branched hydroxyalkyl; linear or branched alkoxy; linear or branched, aminoalkyl; linear or branched haloalkyl; linear or branched carboxyalkyl; acetonyl; substituted or unsubstituted aryl; substituted or unsubstituted arylalkyl; substituted or unsubstituted phenylalkoxy; allyl; phosphoniumalkyl moiety; or a heterocyclic alkyl moiety; with the proviso that R 1 , R 2 , R 3 , R 4 are not all hydrogen at the same instance and are not all butyl at the same instance; and X − is a halide ion or hydroxide ion.
2. The composition of claim 1 , wherein the chemical mechanical polishing composition for tungsten comprises, as initial components:
the water;
0.01 to 10 wt% of the oxidizing agent, wherein the oxidizing agent is hydrogen peroxide;
0.01 to 10 wt% of the colloidal silica abrasive having the permanent negative zeta potential;
100 to 1,400 ppm of the dicarboxylic acid, salt thereof or mixtures thereof, wherein the dicarboxylic acid, salt thereof or mixtures thereof is malonic acid, salt thereof or mixtures thereof;
100 to 1,000 ppm of the source of iron (III) ions, wherein the source of iron (III) ions is ferric nitrate nonahydrate;
optionally the pH adjusting agent, and
wherein the chemical mechanical polishing composition has a pH from 1 to 7; and
wherein the quaternary phosphonium compound is in amounts of 5 to 500 ppm,
wherein R 1 , R 2, R 3 and R 4 independently comprise hydrogen; linear or branched (C 1 -C 16 )alkyl; linear or branched hydroxy(C 1 -C 4 )alkyl; linear or branched (C 1 -C 4 )alkoxy; linear or branched, amino(C 1 -C 4 )alkyl; linear or branched halo(C 1 -C 4 )alkyl; linear or branched carboxy(C 1 -C 4 )alkyl; substituted or unsubstituted phenyl; substituted or unsubstituted phenyl(C 1 -C 4 )alkyl; substituted or unsubstituted phenyl(C 1 -C 4 )alkoxy; (C 2 -C 4 )alkylphosphonium moiety; or a heterocyclic(C 1 -C 3 )alkyl moiety; with the proviso that R 1 , R 2, R 3 and R 4 are not all hydrogen at the same instance and all are not butyl at the same instance; and X − is bromide, chloride or fluoride.
3. The composition of claim 1 , wherein the chemical mechanical polishing composition for tungsten comprises, as initial components:
the water;
1 to 3 wt% of the oxidizing agent, wherein the oxidizing agent is hydrogen peroxide;
2 to 4 wt% of the colloidal silica abrasive having the permanent negative zeta potential;
120 to 1,350 ppm of the dicarboxylic acid, salt thereof or mixtures thereof, wherein the dicarboxylic acid, salt thereof or mixtures thereof is malonic acid, salt thereof or mixtures thereof;
250 to 400 ppm of the source of iron (III) ions, wherein the source of iron (III) ions is ferric nitrate nonahydrate;
optionally the pH adjusting agent, and
wherein the chemical mechanical polishing composition has a pH from 2 to 3; and
wherein the quaternary phosphonium compound is in amounts of 10 to 100 ppm, wherein the quaternary phosphonium compound is in amounts of 10 ppm to 100 ppm, wherein R 1 , R 2, R 3 and R4 independently comprise hydrogen; linear or branched (C 4 -C 16 )alkyl; linear or branched hydroxy(C 1 -C 4 )alkyl; linear or branched, amino(C 1 -C 4 )alkyl; linear or branched halo(C 1 -C 4 )alkyl; substituted or unsubstituted phenyl; or substituted or unsubstituted phenyl(C 1 -C 4 )alkyl; with the proviso that R 1 , R 2, R 3, R 4 are not all hydrogen at the same instance and not all are butyl at the same instance; and X − is bromide or chloride.