| 摘要 |
PURPOSE:To prevent the oxidation and exfoliation of a gate electrode by a method wherein, after the gate electrode composed of W has been patterned, it is heat-treated in an atmosphere of NH3 and the surface (the top and side faces) of the gate electrode is nitrified. CONSTITUTION:W for gate electrode use is deposited by a sputtering method. After a resist coated on this W has been patterned, a resist mask 21 is formed; a reactive ion etching operation is executed by using SF6 as an etching gas and by making use of this mask as a mask; a gate electrode 13 composed of W is formed. Then, this assembly is heated in an atmosphere of NH3 at 800 deg.C; a WN film 14 is grown on the surface (the top and side faces) of the gate electrode. Then, if an Si substrate 11 is heat-treated in an atmosphere of O2 at 800 deg.C and an SiO2 film 15 is grown, the surface of the gate electrode is covered with a WO3 film 13a; because WO3 is formed uniformly, it is not exfoliated. In succession, if this assembly is treated with hydrogen at 900 deg.C, WO3 is reduced to W. During this process, because SiO2 is stable, it is possible to execute a stable process by using W.
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