Dual gate oxide process for uniform oxide thickness

摘要

A process for forming dual gate oxides of improved oxide thickness uniformity for use in high performance DRAM systems or logic circuits, comprising:a) growing a sacrificial oxide layer on a substrate;b) implanting a dopant through the sacrificial oxide layer;c) implanting a first dosage of nitrogen ions in the absence of a photoresist to form a nitrided silicon layer;d) subjecting the substrate to a rapid thermal anneal for a sufficient time and at a sufficient temperature to allow nitrogen to diffuse to the silicon/oxide interface;e) masking the substrate with a photoresist to define the locations of the thin oxides of the dual gate oxide;f) implanting a second dosage of nitrogen ions through the photoresist;g) stripping the photoresist and the sacrificial oxide layers; andh) growing by oxidation gate oxide layers characterized by improved oxide thickness uniformity in the nitrogen ion implanted areas in the thin and thick oxides.