Composition and method for metal CMP
A chemical mechanical polishing composition for polishing a substrate includes a liquid carrier and cationic metal oxide abrasive particles dispersed in the liquid carrier. The cationic metal oxide abrasive particles have a surface modified with at least one compound consisting of a silyl group having at least one quaternary ammonium group. A method for chemical mechanical polishing a substrate including a metal layer includes contacting the substrate with the above described polishing composition, moving the polishing composition relative to the substrate, and abrading the substrate to remove a portion of the metal layer from the substrate and thereby polish the substrate.
1. A chemical mechanical polishing composition comprising:
a liquid carrier;
cationic metal oxide abrasive particles dispersed in the liquid carrier, the cationic metal oxide abrasive particles having a surface modified with at least one compound comprising a silyl group represented by general formula (2) or general formula (3):
—Si(X) n -[L-CR 1 (OH)—C(R 2 ) 2 -A] 3-n (2)
wherein X is the same or different and each represents a hydroxyl group, a hydrolyzable substituent, a non-hydrolyzable substituent, or a bond with an O—Si of another silyl group or the particle;
n is 0, 1, or 2;
L is a linkage group;
R 1 is a hydrogen atom or an alkyl group that contains an amino group, a hydroxyl group, or an unsaturated bond;
R 2 is the same or different, and each represents a hydrogen atom or an alkyl group that contains an amino group, a hydroxyl group, or an unsaturated bond; and
A is a quaternary ammonium group;
wherein X is the same or different and each represents a hydroxyl group, a hydrolyzable substituent, a non-hydrolyzable substituent, or a bond with an O—Si of another silyl group or the particle;
n′ is 0, 1, or 2;
L′ is a linkage group; and
A′ is a quaternary ammonium group;
wherein the metal oxide abrasive particles have an aggregation ratio in a range from about 1.5 to about 5.0, and wherein the cationic metal oxide abrasive particles have an isoelectric point greater than about 9.
2. The composition of claim 1 , wherein
the silyl group is represented by the general formula (2); and
L is —CH 2 CH 2 CH 2 OCH 2 —, R 1 and R 2 are H, and A is —N′R′R″R′″ wherein R′, R″, and R′″ are the same or different and include substantially any carbon containing compound.
3. The composition of claim 1 , wherein
the silyl group is represented by the general formula (3); and
L is —CH 2 CH 2 — and A′ is —N′R′R″R′″ wherein R′, R″, and R′″ are the same or different and include substantially any carbon containing compound.
4. The composition of claim 1 , wherein the liquid carrier is water.
5. The composition of claim 1 , wherein the metal oxide abrasive particles are silica particles.
6. The composition of claim 1 , wherein the metal oxide abrasive particles have a mean particle size in a range from about 30 to about 90 nm.
7. The composition of claim 1 , having a pH from about 6 to about 8.
8. The composition of claim 1 , wherein the cationic metal oxide abrasive particles comprise colloidal silica particles having a zeta potential of at least 20 mV at a pH of greater than 6.
9. The composition of claim 1 , comprising less than about 2 weight percent of the cationic metal oxide abrasive particles.
10. The composition of claim 1 , wherein the liquid carrier has a total dissolved silicon concentration of less than about 150 ppm.
11. The composition of claim 1 , wherein the liquid carrier has a residual silane concentration of less than about 100 ppm.
12. The composition of claim 1 , further comprising a hydrogen peroxide oxidizer and a metal corrosion inhibitor.
13. A chemical mechanical polishing composition comprising:
a liquid carrier;
cationic metal oxide abrasive particles dispersed in the liquid carrier, the cationic metal oxide abrasive particles having a surface modified with at least one compound comprising a silyl group represented by general formula (2) or general formula (3):
—Si(X) n -[L-CR 1 (OH)—C(R 2 ) 2 -A] 3-n (2)
wherein X is the same or different and each represents a hydroxyl group, a hydrolyzable substituent, a non-hydrolyzable substituent, or a bond with an O—Si of another silyl group or the particle;
n is 0, 1, or 2;
L is a linkage group;
R 1 is a hydrogen atom or an alkyl group that contains an amino group, a hydroxyl group, or an unsaturated bond;
R 2 is the same or different, and each represents a hydrogen atom or an alkyl group that contains an amino group, a hydroxyl group, or an unsaturated bond; and
A is a quaternary ammonium group;
wherein X′ is the same or different and each represents a hydroxyl group, a hydrolyzable substituent, a non-hydrolyzable substituent, or a bond with an O—Si of another silyl group or the particle;
n′ is 0, 1, or 2;
L′ is a linkage group; and
A′ is a quaternary ammonium group;
wherein the metal oxide abrasive particles have an aggregation ratio in a range from about 1.5 to about 5.0, further comprising a triazole pyridine compound and having a pH in a range from about 6 to about 8.
14. A chemical mechanical polishing composition comprising:
a liquid carrier;
cationic metal oxide abrasive particles dispersed in the liquid carrier, the cationic metal oxide abrasive particles having a surface modified with at least one compound comprising a silyl group represented by the general formula:
—Si(X) n -[L-O—R-A] 3-n (1)
wherein X is the same or different and each represents a hydroxyl group, a hydrolyzable substituent, a non-hydrolyzable substituent, or a bond with an O—Si of another silyl group or the particle;
n is 0, 1, or 2;
L is a linkage group;
O is an oxygen heteroatom;
R is an alkyl group that contains an amino group, a hydroxyl group, or an unsaturated bond; and
A is a quaternary ammonium group;
wherein the liquid carrier is water and the metal oxide abrasive particles have a mean particle size in a range from about 30 to about 90 nm.
15. The composition of claim 14 , wherein L is —CH 2 CH 2 CH 2 —, R is —CH 2 CH(OH)CH 2 —, and A is —N + R′R″R′″ wherein R′, R″, and R′″ are the same or different and include substantially any carbon containing compound.
16. The composition of claim 14 , having a pH from about 6 to about 8 and wherein the wherein the cationic metal oxide abrasive particles comprise colloidal silica particles having a zeta potential of at least 20 mV.
17. The composition of claim 14 , comprising less than about 2 weight percent of the metal oxide abrasive particles.
18. The composition of claim 14 , wherein the liquid carrier has a total dissolved silicon concentration of less than about 150 ppm.
19. The composition of claim 14 , wherein the liquid carrier has a residual silane concentration of less than about 100 ppm.
20. The composition of claim 14 , further comprising a hydrogen peroxide oxidizer and a metal corrosion inhibitor.
21. The composition of claim 14 , further comprising a triazole pyridine compound and having a pH in a range from about 6 to about 8.