Isolation process induced wafer warpage

Abstract

Wafer warpage behavior during a local oxidation of silicon isolation process was investigated. Anisotropic etching of the front side nitride produced unbalanced stress states between front and back side nitride films, and caused a large wafer warpage. The maximum warpage was observed after field oxidation due to a wedge-effect of field oxide on the front side. Plastic deformation was shown to occur when the maximum warpage after field oxidation exceeded a critical value, although the warpage dramatically decreased after nitride stripping. (C) 1998 The Electrochemical Society, Inc. S1099-0062(98)01-008-6.