Signetics

Ching W Lai

Warren C Rosvold

Hans J Sigg

A metal contact system for an IGFET having shallow source and drain includes a refractory metal silicide layer forming low resistance ohmic contact to a silicon surface, a layer on the silicide layer of another refractory metal to serve as a barrier against diffusion of the interconnect metal, and a layer of interconnect metal over the diffusion barrier layer. The refractory metal layers are deposited by sputtering platinum or platinel for the first layer and titanium-tungsten for the second layer. In metal gate construction an additional layer of chromium is used as an etch resistant mask to protect the refractory metal layers from chemical attack when removing silicon nitride after it has been used initially as an oxidation mask and later as a sputtering mask.

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San Jose, CA, United States of America

Ching W Lai