Semiconductor device esp. MISFET prodn. - using silicon nitride film obtd. by direct nitriding to prevent ion implanted impurity migration during heat treatment

摘要

Semiconductor device, esp. MISFET prodn. involves implantation of an impurity in a semiconducting Si substrate and heating. The novel feature is that a Si3N4 film, esp a gate insulating film of the MISFET, is produced on the substrate by direct thermal nitriding, so that the total amt of ion implanted impurity is retained at the surface of the substrate after heating. Specifically, the Si3N4 film prevents redistribution of the implanted impurity from the substrate into the Si3N4 film when the substrate is heated to activate the impurity and correct damage to the substrate caused by ion implantation.