There is disclosed a MIS field effect transistor, comprising a silicon
substrate, an insulating film formed over the silicon substrate and
containing silicon and at least one of nitrogen and oxygen, a metal
oxynitride film formed on the insulating film and containing at least one
kind of metal atom selected from the group consisting of zirconium,
hafnium and a lanthanoide series metal, the metal oxynitride film
containing nitrogen atom not bonding with the metal atom without
metal-nitrogen bond at the density of higher than 10.sup.19 /cm.sup.3, and
a gate electrode formed on the metal oxynitride film.
