Method and composition for reducing gate oxide damage during RF sputter clean

Abstract

Provided is a method and composition for RF sputter cleaning of contact and via holes which provides substantially uniform charge distribution in the holes and minimizes electron shadowing. This is accomplished by isotropically depositing, such as by PVD, a layer of conductive material at the wafer surface surrounding a hole and down the sides of the hole. Isotropic deposition is such that in high aspect ratio trenches and holes deposition is heaviest at the top and minimal at the bottom (due to the deposition shadowing effect). The deposited conductive material is preferably a metal that is also used as a liner in the holes prior to depositing the plug material. The conductive material provides path for negative charge otherwise accumulating at the top of a hole during RF sputter cleaning to reach the bottom of the hole and thereby prevents accumulations of charge of one polarity in and around the hole. Thus, the stress on the gate oxide caused by conventional RF sputtering, described above, is relieved.

Dependencies are inferred from the claim text.