Patent ID: 7795155
Filing Date: 2010-09-14
Classification: C09K

Abstract:
1. A method for forming an indium cap layer on a metallic surface which comprises: providing a surface having metallic interconnects separated by interlayer dielectric wherein the metallic interconnects are capable of forming an intermetallic with indium; blanket depositing indium onto the surface; and then selectively chemically etching the indium located on the interlayer dielectric leaving an indium cap layer; wherein the etching comprises contacting with an etchant composition that comprises about 0.05 Molar to about 5 Molar of a strong acid having a pKa of about 3.5 or less; and wherein the etchant composition further comprises an oxidant; wherein the concentration of the strong acid is about 0.25 to about 2 Molar; and wherein oxidant is present in a concentration of about 0.01 Molar to about 0.5 Molar and is selected from the group consisting of vanadyl sulfate and 3-nitrobenzenesulfonic acid, sodium salt and mixtures thereof.