Compositions for oxide CMP
View Patent ↗A chemical mechanical polishing composition comprising a soluble cerium compound at a pH above 3 and a method to selectively polish a silicon oxide overfill in preference to a silicon nitride film layer in a single step during the manufacture of integrated circuits and semiconductors.
1. A method for removing at least a portion of a silicon dioxide layer from a substrate comprising:
(a) admixing a salt, a soluble cerium compound including Ce 4+ ions; an oxidizing agent having a oxidation potential greater than Ce 4+ , and de-ionized water to give a chemical mechanical polishing composition having a pH of from about 3.0 to about 11.0;
(b) applying the chemical mechanical polishing composition to the substrate; and
(c) removing at least a portion of the silicon oxide layer from the substrate by bringing a pad into contact with the substrate and moving the pad in relation to the substrate.
2. The method of claim 1 , wherein the substrate is a layered substrate comprising at least one layer of silicon dioxide and at least one layer of silicon nitride.
3. The method of claim 1 , wherein the silicon oxide is removed from the substrate at a rate at least five-fold greater than the removal rate of silicon nitride.
4. The method of claim 1 , wherein the oxidizing agent is ammonium persulfate.
5. The method of claim 1 , wherein the salt and soluble cerium compound is ammonium cerium nitrate.
6. The method of claim 1 , including at least one metal oxide abrasive selected from the group including alumina, titania, zirconia, germania, silica, ceria and mixtures thereof.
7. The method of claim 1 , wherein the metal oxide abrasive is silica.
8. A method for removing at least a portion of a silicon dioxide layer deposited on a silicon wafer including a silicon nitride layer comprising:
(a) mixing from about 2 to about 15 wt. % silica, from about 0.05 to about 10 wt. % ammonium cerium nitrate, from about 0.05 to about 5.0 wt. % ammonium persulfate, at least one chelating agent and de-ionized water to give a chemical mechanical polishing slurry having a pH of between about 3.8 to about 5.5;
(b) applying the chemical mechanical polishing slurry to a pad;
(c) rotating the pad; and
(d) removing at least a portion of the silicon dioxide layer by bringing the rotating pad into contact with the wafer and rotating the wafer in relation to the rotating pad.