CORROSION INHIBITION IN COPPER CMP
Publication Date: 2009-May-29
The IP.com Prior Art Database
Disclosed herein are non-limiting embodiments of compositions and processes for inhibiting corrosion of copper during a chemical mechanical planarization (CMP) process.
Embodiments of the current invention include a composition comprising an inhibitor, a surfactant, and a base.
In some embodiments the inhibitor may be a non-triazole based inhibitor that is either a thiazoline, thiazole, pyrazole, thiadiazole, tetrazole or imidazole containing a single ring. Preferably 2-Mercapto-2-thiazoline, 2-aminothiazole, or 1,3,4-Thiadiazole-2,5-dithiol.
In some embodiments the surfactant may be a surfactant (non-ionic, anionic or zwitterionic), preferably an anionic surfactant and preferably one that is carboxylate, phosphate, sulfate, phosphonate, sulfonate functional. Preferred surfactants include glycolic acid ethoxylate lauryl ether, Glycolic acid ethoxylate 4-nonylphenyl ether, Poly(ethylene glycol) 4-nonylphenyl 3-sulfopropyl ether potassium salt, Polyether phosphate ester, or dodecylbenzenesulfonic acid.
In some embodiments, the base may be a metal ion free base to adjust the pH to above pH 7 (preferably 8-11). Bases could include organic amines, ammonium hydroxide, choline hydroxide, or tetraalkylammonium hydroxides. Most preferred is an organic amine, an example of which is isopropanolamine.
Corrosion inhibitors are necessary during the copper CMP process to prevent recess of copper lines during the removal of copper overburden. Benzotriazole is commonly used, and is an effective inhibitor for copper corrosion, but is difficult to remove during the post CMP cleaning processes and thus leads to a high level of organic residue on the copper surface. This residue can promote delamination of subsequent films that are deposited on top of the copper. Other inhibitors such as triazole, tetrazole, imidazole and their derivatives as well as some surfactant based inhibitors have been used as replacements for for BTA.
Disclosed is a composition and process for inhibiting corrosion of copper during a chemical mechanical planarization (CMP) process wherein an inhibitor solution is applied to the wafer surface during and/or after the copper and barrier polishing steps. The composition contains a thiazoline or thiazole based inhibitor, a surfactant, and a base. The corrosion inhibitor is preferably mercaptothiazoline or aminothiazole, and the surfactant is preferably an anionic surfactant with carboxylate, phosphate or sulfonate functionality. The solution of the present invention is an effective inhibitor against copper corrosion, thus preventing the recess of copper lines during buffing, handling and cleaning of wafers to remove residue from the planarization process. The chemistry is also effective at displacing BTA from the copper surfa...