Chemical mechanical polishing (CMP) composition for shallow trench isolation (STI) applications and methods of making thereof

1. A method of reducing trace metal contaminants and smaller sized cerium oxide particles in a cerium oxide slurry, comprising steps of:

(i) adding a chemical chelator to the cerium oxide slurry to obtain treated cerium oxide slurry; wherein the chemical chelator reacts with trace metal ions in trace metal contaminants to form metal ion-chelator complexes; and

(ii) centrifuging cerium oxide slurry obtained from step (i) to remove metal ion-chelator complexes and to remove smaller sized cerium oxide particles; wherein

the chemical chelator having chemical structure selected from the group consisting of:

and combinations thereof;

wherein R is selected from the group consisting of alkyl, alkoxy, organic group with one or more hydroxyl groups, substituted organic sulfonic acid, substituted organic sulfonic acid salt, substituted organic carboxylic acid, substituted organic carboxylic acid salt, organic carboxylic ester, organic amine groups, and combinations thereof; one of R′ and R″ is selected from the group consisting of hydrogen, alkyl, alkoxy, organic group with one or more hydroxyl groups, substituted organic sulfonic acid, substituted organic sulfonic acid salt, substituted organic carboxylic acid, substituted organic carboxylic acid salt, organic carboxylic ester, organic amine, and combinations thereof; and the other of R′ and R″ is selected from the group consisting of alkyl, alkoxy, organic group with one or more hydroxyl groups, substituted organic sulfonic acid, substituted organic sulfonic acid salt, substituted organic carboxylic acid, substituted organic carboxylic acid salt, organic carboxylic ester, organic amine, and combinations thereof.

2. The method of claim 1 , wherein the method further comprises the steps of

(a) adding an ion exchange resin to the cerium oxide slurry; and (b) removing the ion exchange resin through filtration to obtain treated cerium oxide slurry; wherein the ion exchange resin is a cationic ion exchange resin or an anionic ion exchange resin;

wherein the ion exchange resin is selected from the group consisting of the cationic ion exchange resin having proton or potassium ions; and the anionic ion exchange resin having hydroxyl group.

3. The method of claim 2 , wherein the ion exchange resin is the cationic ion exchange resin having potassium ions; and the method further comprising

(c) adding anionic ion exchange resin having hydroxyl group to the treated cerium oxide slurry after step (b);

(d) removing the anionic ion exchange resin from the cerium oxide slurry in (c) through filtration; and

repeating steps (a) to (d) at least twice.

4. The method of claim 1 , wherein the method further comprises the steps of

(a) adding a chemical additive to the cerium oxide slurry to form a mixture; wherein the chemical additive reacts with trace metal ions in the trace metal contaminants to form water soluble chemical additive-metal ion complexes in the mixture; (b) centrifuging the mixture; (c) collecting cerium oxide particles from the precipitate of the centrifugation; and (d) mixing deionized water with the collected cerium oxide particles to obtain treated cerium oxide slurry;

wherein the chemical additive is selected from the group consisting of (a) organic acid selected from the group consisting of oxalic acid, citric acid, malic acid, tartaric acid, maleic acid, itaconic acid, gluconic acid, lactic acid, ETDA, and combinations thereof; (b) amino acids selected from the group consisting of glycine, alanine, serine, proline, and combinations thereof; (c) organic compound containing at least one carboxylic acid group; (d) amino acid derivatives containing at least one amine acid moieties or iminodiacetic acid; (e) organic amine compound selected from the group consisting of ethylene diamine, propylene diamine, ethylenimine, organic compound containing primary or secondary amino groups; and combinations thereof; (f) organic sulfuric acids containing at least one sulfuric acid group; (g) organic phosphoric acids containing at least one phosphoric acid group; (h) pyridine and its derivatives selected from the group consisting of pyridine, 2-methylpyridine, substituted pyridine at position 2, 3, 4, 5 or 6 respectively, and combinations thereof; (i) bipyridine and its derivatives selected from the group consisting of 2,2′-bipyrine, 4,4′-dimethyl bipyridine, 4,4′-bipyridine, and all other substituted 2,2′-bipyrine or 4,4′-bipyridine derivatives, and combinations thereof; (j) terpyridine and its derivatives; (k) quinoline and its derivatives; (l) hydroxylquinoline and its derivatives; and (m) ammonium hydroxide; and (n) combinations thereof.

5. The method of claim 4 , wherein the chemical additive is oxalic acid having concentration ranging from 0.01M to 0.1M.

6. The method of claim 1 , wherein the chemical chelator is selected from the group consisting of 8-hydroxylquinoline, 8-hydroxylquinoline-5-sulfonic acid, and combinations thereof.

7. The method of claim 1 , wherein the method further comprises the step of running deionized water through the cerium oxide slurry using at least one ultra filtration membrane to obtain a treated cerium oxide slurry as retentate.

8. The method of claim 7 , wherein the method further comprising (a) inducing agglomeration of cerium oxide particles before the step of running deionized water; and (b) sonicating the treated cerium oxide slurry after the step of running deionized water.

9. The method of claim 1 , wherein the method further comprises the steps of (a) centrifuging the cerium oxide slurry; (b) collecting cerium oxide particles from the precipitate of centrifugation; (c) mixing deionized water with the collected cerium oxide particles to form a new cerium oxide slurry; and (d) repeating steps (a) to (c) at least twice to obtain a treated cerium oxide slurry comprising cerium oxide particles from the precipitate of the last centrifugation.