Fluoride-modified silica sols for chemical mechanical planarization
View Patent ↗A chemical-mechanical planarization composition containing surface-modified abrasive particles such as silica where at least a portion of the surface of the particles has bound thereto a surface-modifying aluminum-containing stabilizer and fluoride that is used to polish semiconductor substrates. The use of a CMP slurry containing surface-modifying aluminum-containing stabilizer and fluoride bound to a silica abrasive provides high metal polishing rates relative to the removal rate of a dielectric.
1. A chemical-mechanical planarization composition comprising: surface-modified abrasive particles having at least a portion of the surface thereof modified with aluminum-containing stabilizer and with fluoride, wherein the moles of surface-modifying fluoride present is between 0.01 and 3 times the moles of surface-modifying aluminum-containing stabilizer disposed on the surface of abrasive particles.
2. The composition of claim 1 wherein the amount of aluminum-containing stabilizer is between 0.1 times 10 −4 moles and 25 times 10 −4 moles per gram of surface-modified abrasive.
3. The composition of claim 2 wherein the composition comprises the abrasive having the surface-modifying fluoride, and further comprises soluble fluoride, wherein the total amount of surface-modifying fluoride and soluble fluoride in the composition is such that at least one tenth of the fluoride is surface-modifying fluoride associated with abrasive particles having aluminum-containing stabilizer thereon.
4. The composition of claim 2 wherein the total moles of surface-modifying fluoride present in the composition is equal to or less than 8 times the moles of aluminum-containing stabilizer disposed on the surface of abrasive particles.
5. The composition of claim 2 wherein the total moles of surface-modifying fluoride present in the composition is equal to or less than 5 times the moles of aluminum-containing stabilizer disposed on the surface of abrasive particles.
6. The composition of claim 2 wherein the total moles of surface-modifying fluoride present in the composition is equal to or less than 4 times the moles of aluminum-containing stabilizer disposed on the surface of abrasive particles.
7. The composition of claim 1 wherein the surface-modified abrasive particles are colloidal silica.
8. The composition of claim 7 wherein the amount of aluminum-containing stabilizer is between 0.1 times 10 −4 moles and 25 times 10 −4 moles per gram of surface-modified abrasive.
9. The composition of claim 7 wherein the composition comprises the abrasive having the surface-modifying fluoride, and further comprises soluble fluoride, wherein the total amount of surface-modifying fluoride and soluble fluoride in the composition is such that at least one tenth of the fluoride is surface-modifying fluoride associated with abrasive particles having aluminum-containing stabilizer thereon.
10. The composition of claim 8 wherein the total moles of surface-modifying fluoride present in the composition is equal to or less than 8 times the moles of aluminum-containing stabilizer disposed on the surface of abrasive particles.
11. The composition of claim 8 wherein the total moles of surface-modifying fluoride present in the composition is equal to or less than 4 times the moles of aluminum-containing stabilizer disposed on the surface of abrasive particles.
12. The composition of claim 1 wherein the surface-modified abrasive is silica, wherein amount of aluminum-containing stabilizer is between 2 times 10.4 and 15 times 10.4 moles per gram of silica.
13. The composition of claim 1 wherein the surface-modified abrasive further comprises a second stabilizer selected from boric acid, borate, or mixture thereof.
14. A method of chemical mechanical polishing a substrate comprising tungsten, said method comprising: movably contacting a substrate having tungsten on a surface thereof with an aqueous composition comprising the composition of claim 1 .
15. The composition of claim 1 wherein the moles of fluoride is between about 0.5 to about 2 times the moles of aluminum-containing stabilizer added to the abrasive particles.
16. The composition of claim 8 wherein the moles of fluoride is between about 0.5 to about 2 times the moles of aluminum-containing stabilizer added to the abrasive particles.
17. The method of claim 14 wherein the amount of aluminum-containing stabilizer is between 0.1 times 10 −4 moles and 25 times 10 −4 moles per gram of surface-modified abrasive.
18. The method of claim 17 wherein the composition comprises the abrasive having the surface-modifying fluoride, and further comprises soluble fluoride, wherein the total amount of surface-modifying fluoride and soluble fluoride in the composition is such that at least one tenth of the fluoride is surface-modifying fluoride associated with abrasive particles having aluminum-containing stabilizer thereon.
19. The method of claim 17 wherein the total moles of surface-modifying fluoride present in the composition is equal to or less than 5 times the moles of aluminum-containing stabilizer disposed on the surface of abrasive particles.