Production of integrated-circuit devices incorporating a diffusion stop for oxygen.

摘要

High quality silicon oxide is grown for integrated circuits by oxidizing poly-crystalline silicon under an oxygen gas flow. A diffusion stop layer of thermal silicon nitride is formed on the underlying substrate priorto the deposition of the poly layer to be oxidized. The nitride layer isolates the substrate from diffused oxygen within the poly layer during oxidation, permitting a non-critical, extended oxidation time. Extension of the oxidation period eliminates imperfect or "loose" chemical bonds throughout the oxide layer formed. Corner stress common in trench applications is minimized because the nitride prevents oxidation in the substrate. The oxidation of undoped poly over doped poly proceeds conformally because the nitride layer therebetween inhibits the enhanced oxidation effect of impurities in the doped poly.