CMP composition including an anionic abrasive
A chemical mechanical polishing composition comprises, consists of, or consists essentially of a liquid carrier, anionic particles dispersed in the liquid carrier, an anionic polymer or surfactant, and a cationic polymer.
1. A chemical mechanical polishing composition comprising:
a liquid carrier;
anionic particles dispersed in the liquid carrier;
a cationic polymer; and
an anionic polymer, further comprising:
an iron-containing accelerator; and
a stabilizer bound to the iron-containing accelerator.
2. The composition of claim 1 , wherein the anionic particles comprise anionic silica, anionic alumina, or a mixture thereof.
3. The composition of claim 1 , further comprising hydrogen peroxide.
4. The composition of claim 1 , wherein a ratio of a total number of negative charges on the anionic polymer to a total number of positive charges on the cationic polymer at a pH of the composition is greater than about 1:1.
5. The composition of claim 1 , wherein a ratio of a total number of negative charges on the anionic polymer to a total number of positive charges on the cationic polymer is in a range from about 1:1 to about 10:1.
6. The composition of claim 1 , wherein:
the anionic particles comprise anionic colloidal silica particles; and
a ratio of a total number of negative charges on the anionic polymer to a total number of positive charges on the cationic polymer at a pH of the composition is greater than about 1:1.
7. The composition of claim 1 , wherein:
the anionic particles comprise anionic alpha alumina particles; and
a ratio of a total number of negative charges on the anionic polymer to a total number of positive charges on the cationic polymer at a pH of the composition is greater than about 3.5.
8. The composition of claim 1 , wherein the anionic polymer comprises a polysulfonic acid polymer.
9. The composition of claim 1 , wherein the anionic polymer is a polysulfonic acid polymer comprising sulfonic acid monomer units, the polysulfonic acid polymer selected from the group consisting of polyvinylsulfonic acid, polystyrenesulfonic acid, poly (2-acrylamido-2-methylpropane sulfonic acid), poly (styrenesulfonic acid-co-maleic acid), and mixtures thereof.
10. The composition of claim 1 , wherein the anionic polymer comprises polyvinylsulfonic acid, polystyrenesulfonic acid, or a mixture thereof.
11. The composition of claim 1 , wherein the cationic polymer comprises a polyamino acid.
12. The composition of claim 1 , wherein the cationic polymer comprises polylysine.
13. The composition of claim 1 , wherein the cationic polymer comprises a monomer including a quaternary amine group.
14. The composition of claim 1 , wherein the cationic polymer comprises poly(diallyldimethylammonium).
15. The composition of claim 1 , wherein the anionic particles comprises anionic silica; the anionic polymer comprises of a polysulfonic acid polymer; and the cationic polymer comprises a polyamino acid.
16. The composition of claim 15 , wherein the cationic polymer comprises polylysine; and a ratio of a total number of negative charges on the anionic polymer to a total number of positive charges on the cationic polymer is in a range from about 1:1 to about 20:1.
17. The composition of claim 16 , wherein:
the composition comprises from about 20 to about 2000 ppm by weight of polystyrenesulfonic acid at point of use; and
the composition comprises from about 2 to about 50 ppm by weight of the polylysine at point of use.
18. The composition of claim 1 , wherein the anionic particles comprise anionic alpha alumina; the anionic polymer comprises a polysulfonic acid polymer; and the cationic polymer comprises a monomer including a quaternary amine group.
19. The composition of claim 18 , wherein the cationic polymer comprises poly(diallyldimethylammonium); and a ratio of a total number of negative charges on the anionic polymer to a total number of positive charges on the cationic polymer is in a range from about 3.5:1 to about 20:1.
20. The composition of claim 19 , wherein:
the composition comprises from about 20 to about 2000 ppm by weight of polystyrenesulfonic acid at point of use; and
the composition comprises from about 20 to about 200 ppm by weight of the poly(diallyldimethylammonium) at point of use.
21. The composition of claim 1 , wherein the anionic particles have a negative charge of at least 10 mV in the polishing composition.
22. The composition of claim 1 , comprising less than about 1 weight percent of the anionic particles at point of use.
23. The composition of claim 1 , having a pH in a range from about 2 to about 5.
24. A method of chemical mechanical polishing a substrate having a tungsten layer or a molybdenum layer, the method comprising:
(a) contacting the substrate with a polishing composition of claim 1 ;
(b) moving the polishing composition relative to the substrate; and
(c) abrading the substrate to remove a portion of the tungsten layer or the molybdenum layer from the substrate and thereby polish the substrate.
25. The method of claim 24 , wherein:
the anionic particles comprise anionic silica;
the anionic polymer comprises a polysulfonic acid polymer; and
the cationic polymer comprises a polyamino acid.
26. The method of claim 25 , wherein
the polishing composition further comprises an iron-containing accelerator and a stabilizer bound to the iron-containing accelerator;
the cationic polymer comprises polylysine and
a ratio of a total number of negative charges on the anionic polymer to a total number of positive charges on the cationic polymer is in a range from about 1:1 to about 20:1.
27. The method of claim 24 , wherein:
the anionic particles comprise anionic alpha alumina;
the anionic polymer comprises a polysulfonic acid polymer; and
the cationic polymer comprises a monomer including a quaternary amine group.
28. The method of claim 27 , wherein
the polishing composition further comprises an iron-containing accelerator and a stabilizer bound to the iron-containing accelerator;
the cationic polymer comprises poly(diallyldimethylammonium); and
a ratio of a total number of negative charges on the anionic polymer to a total number of positive charges on the cationic polymer is in a range from about 3.5:1 to about 20:1.