CMP slurry/method for polishing ruthenium and other films
View Patent ↗A method and associated composition for CMP processing of noble metal-containing substrates (such as ruthenium-containing substrates) afford both high removal rates of the noble metal and are tunable with respect to rate of noble metal removal in relation to removal of other films. Low levels of an oxidizing agent containing one or more peroxy-functional group(s) can be used along with a novel ligand to effectively polish noble metal substrates.
1. A method for chemical mechanical planarization of a surface having at least one feature thereon comprising a noble metal, said method comprising the steps of:
A) placing a substrate having the surface having the at least one feature thereon comprising the noble metal in contact with a polishing pad;
B) delivering a polishing composition having a pH which is basic, comprising:
a) an abrasive;
b) a cyanate salt; and
c) an oxidizing agent containing at least one peroxy-functional group; and
C) polishing the substrate with the composition.
2. The method of claim 1 wherein the cyanate salt is selected from sodium cyanate, potassium cyanate, and ammonium cyanate.
3. The method of claim 1 wherein the oxidizing agent is selected from periodic acid and a salt of periodic acid.
4. The method of claim 3 wherein the salt of periodic acid is potassium periodate.
5. The method of claim 1 wherein the noble metal is selected from the group consisting of ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), platinum (Pt), silver (Ag), gold (Au), alloys thereof, oxides thereof, and combinations thereof.
6. The method of claim 5 wherein the noble metal is ruthenium.
7. The method of claim 1 wherein the pH ranges from 9 to 12.
8. The method of claim 1 wherein the level of the cyanate salt ranges from 0.2 weight % to 4 weight %.
9. The method of claim 1 wherein the level of the oxidizing agent containing at least one peroxy-functional group ranges from 0.01 weight % to 2.0 weight %.
10. The method of claim 1 wherein the polishing composition further comprises d) alkyl or aryl sulfonate ions.