Self-aligning contact and interconnect structure

Abstract From the Canadian patent

An MOS transistor for use in an integrated circuit particularly CMOS integrated circuits, is fabricated with a self-aligning contact and interconnect structure which allows for higher packing density. Self-aligning source and drain contacts overlap the gate but are prevented from short circuiting to the gate by oxide insulation between the source/drain contacts and the gate, and a layer of silicon nitride above the gate. Contacts to the gate are made on top of the gate over the active region of the transistor because the source and drain regions are protected by a hardened layer of photoresist during etching of insulation to expose the gate contact. Source drain and gate contacts are …