Tungsten processing slurry with catalyst
Described are compositions (e.g., slurries) useful in methods for chemical-mechanical processing (e.g. polishing or planarizing) a surface of a substrate that contains tungsten, the slurries containing abrasive particles, metal cation catalyst, phosphorus-containing zwitterionic compound, and optional ingredients such as oxidizer; also described are methods and substrates used or processed on combination with the compositions.
1. A chemical mechanical processing composition comprising:
liquid carrier,
abrasive particles,
catalyst comprising:
metal cation, wherein the metal cation is an iron cation present from about 10 to about 50 ppm based on the total weight of the composition, and
zwitterionic compound capable of forming a complex in the composition with the metal cation, the zwitterionic compound comprising a phosphorus-containing group having a negative charge in the composition, and a cationic group having a positive charge in the composition, wherein the zwitterionic compound has a structure according to Formula 1:
wherein:
R 1 and R 2 are independently selected from
a negatively-charged oxygen (—O − ), and
hydroxy (—OH), or
an organic radical connected to the phosphorus atom through a divalent oxygen,
such that at least one of R 1 and R 2 is a negatively-charged oxygen providing the negative charge;
n is one;
L is a linking group; and
R 3 is an organic group that exhibits the positive charge.
2. A composition of claim 1 wherein the composition has a pH below 7 and the negative charge is at a phosphate, phosphinate, or phosphonate group.
3. A composition of claim 1 wherein the positive charge is at a nitrogen atom.
4. A composition of claim 1 wherein one of R 1 and R 2 is a negatively-charged oxygen providing the negative charge, and the other of R 1 and R 2 is —OH.
5. A composition of claim 1 wherein one of R 1 and R 2 is a negatively-charged oxygen providing the negative charge, and the other of R 1 and R 2 is an organic radical R 4 connected to the phosphorus atom through a divalent oxygen:
wherein R 4 is a substituted or unsubstituted, saturated, branched, or straight alkyl radical.
6. A composition of claim 1 wherein the zwitterionic compound is selected from: o-phosphoryl-ethanolamine, choline glycerophosphate, inosine monophosphate, phosphocholine.
7. A composition of claim 1 wherein the iron cation is derived from iron nitrate nonahydrate.
8. A composition of claim 1 comprising from about 0.5 to about 4 weight percent silica abrasive particles.
9. A composition of claim 1 wherein R 3 is an amine-functional organic group comprising a nitrogen atom that provides the positive charge.
10. A composition of claim 9 wherein the amine-functional organic group is selected from —NH 3 + , a quaternary ammonium, and an aromatic heterocyclic amine.
11. A composition of claim 10 wherein the amine-functional organic group is —NH 3 + , and L is a substituted or unsubstituted divalent alkylene.
12. A composition of claim 11 wherein L is a substituted divalent alkylene, comprising substituents selected from a hydroxy group, a phosphate group, a phosphonate group, and combinations thereof.
13. A composition of claim 1 wherein L and R 3 together form an organic radical that includes one or multiple saturated or aromatic ring structures.
14. A composition of claim 13 wherein the one or multiple saturated or aromatic ring structures contain a heteroatom, and wherein the heteroatom is selected from oxygen and nitrogen.
15. A composition of claim 14 wherein the organic radical includes an aromatic nitrogen-containing ring, and the nitrogen of the aromatic ring provides the positive charge.
16. A composition of claim 1 wherein the abrasive particles are colloidal silica particles.
17. A composition of claim 16 wherein the abrasive particles exhibit a positive charge of at least 6 millivolts, in the composition.
18. A composition of claim 16 wherein the abrasive particles exhibit a permanent positive charge of at least 10 millivolts, in the composition.