Self-aligned double-diffused MOS devices

摘要

A self-aligning masking technique for making double-diffused MOS devices. First and second openings are formed in a first masking layer, and a thin second oxide layer is formed therein. A silicon nitride layer is formed on the first and second masking layers, a third opening defining the source region is formed in the silicon nitride layer adjacent to the first opening, and the exposed first oxide layer is removed. A first region is diffused through the third opening and extends under the thin second oxide layer, and a second, shallower, opposite conductivity region is diffused through the third opening, the channel region being the region between the boundaries of the first and second diffused regions. The thin second masking layer and the overlying silicon nitride layer form a gate insulator for the MOS device, which gate insulator is automatically aligned to the first and second diffused regions.