Semiconductor device having reduced surface leakage and methods of

Abstract

Surface leakage paths on bipolar and FET transistors may be significantly reduced by the presence of a fixed charge in an insulating layer adhered to a semiconductor wafer. The fixed charge consists of ions which are introduced into the insulating layer after all high-temperature process treatments have been performed on the wafer. The ions are introduced into the insulating layer by (1) immersing the wafer in a solution of a suitable metal salt; (2) sandwiching the wafers between carefully cleaned non-immersed wafers and (3) driving the ions to the insulating layer-wafer interface by heating the wafer stacks in a furnace at a preselected temperature. The effective charge level embedded in the insulating layer is sufficient to protect against inversion of the wafer surface due to conductors on the insulating layer having negative potentials exceeding 10 volts and overlying the stored-charge area.