Wet-process ceria compositions for polishing substrates, and methods related thereto
Disclosed are a chemical-mechanical polishing composition and a method of polishing a substrate. The polishing composition comprises low average particle size (e.g., 30 nm or less) wet-process ceria abrasive particles, at least one alcohol amine, and water, wherein said polishing composition has a pH of about 6. The polishing composition can be used, e.g., to polish any suitable substrate, such as a polysilicon wafer used in the semiconductor industry.
1. A chemical-mechanical polishing composition comprising:
(a) wet-process ceria abrasive particles having an average particle size of about 30 nm or less, wherein the ceria abrasive particles are substantially free of agglomeration in the polishing composition;
(b) at least one alcohol amine in an amount from about 0.001 wt. % to about 1 wt. % of the composition;
(c) at least one nonionic surfactant; and
(d) water;
wherein the composition has a pH of about 6 or more.
2. The polishing composition of claim 1 , wherein the abrasive particles have an average primary particle size of about 12 nm or less.
3. The polishing composition of claim 1 , wherein the abrasive particles are present in an amount from about 0.001 wt. % to about 2 wt. % of the composition.
4. The polishing composition of claim 1 , wherein the alcohol amine has a pKi of from about 6 to about 10.
5. The polishing composition of claim 1 , wherein the alcohol amine bears a functional group having a pKa of from about 7 to about 11.
6. The polishing composition of claim 1 , wherein the alcohol amine comprises 2-dimethylamino-2-methylpropanol, triethanolamine, diethanolamine, ethanolamine, 2-amino-2-methyl-1,3-propanediol, Bis-Tris, Tris or any combination thereof.
7. The polishing composition of claim 1 , wherein the nonionic surfactant has an hydrophobic lipophilic balance of from about 7 to about 18.
8. The polishing composition of claim 1 , wherein the nonionic surfactant comprises a polysorbate, sorbitan, polyoxyethylene ether, ethoxylate, acrylic, polyether polyol, or any combination thereof.
9. The polishing composition of claim 1 , wherein the nonionic surfactant comprises a polysorbate 20, polysorbate 60, polysorbate 65, polysorbate 80, sorbitan monolaurate, polyoxyethylene (40) nonylphenyl ether, pentaerythritol ethoxylate, glycerol propoxylate-block-ethoxylate, acrylic copolymer, polypropylene oxide-based triol, or any combination thereof.
10. The polishing composition of claim 1 , wherein the nonionic surfactant is present in an amount from about 0.001 wt. % to about 1 wt. % of the composition.
11. The polishing composition of claim 1 , further comprising a thickener.
12. The polishing composition of claim 11 , wherein the thickener comprises a cellulosic compound, dextran, polyvinyl alcohol, carrageenan, chitosan, or any combination thereof.
13. The polishing composition of claim 11 , wherein the thickener comprises hydroxyethylcellulose, carboxyethylcellulose, hydroxymethylcellulose, methylcellulose, hydroxypropylcellulose, or any combination thereof.
14. The polishing composition of claim 11 , wherein the thickener is present in an amount from about 0.001 wt. % to about 1 wt. % of the composition.
15. The polishing composition of claim 1 , further comprising a cationic polymer.
16. The polishing composition claim 15 , further comprising thickener.
17. The polishing composition of claim 15 , wherein the cationic polymer comprises poly(methacryloxyethyltrimethylammonium) chloride (polyMADQUAT), poly(diallyldimethylammonium) chloride (polyDADMAC), poly(acrylamide), poly(allylamine), poly(vinylimmidazolium), poly(vinylpyridinium), or any combination thereof.
18. The polishing composition of claim 15 , wherein the cationic polymer is present in an amount from about 0.001 wt. % to about 1 wt. % of the composition.