Semiconductor device

Abstract

Abstract PURPOSE:To suppress the redistribution of impurities due to oxidation after the formation of a gate electrode and heat treatment in a diffusing step and the like by forming an impurity-diffusion blocking film on a polycrystalline silicon film wherein different impurities are added. CONSTITUTION:P-type impurity ions (e.g. boron ions) are implanted in a polycrystalline silicon film 6b on an N well 3 which is to become a PMOS region. N-type impurity ions (e.g. arsenic ions) are implanted in a polycrystalline silicon film 6a on a P well 2 which is to become an NMOS region. A tungsten silicide film 8a which is a metal silicide film is formed on the polycrystalline silicon films 6a and 6b. A gate electrode is formed. Silicon(Si) ions are implanted in the tungsten silicide film 8a, and the perfect amorphous state is obtained. Since there is no grain boundary in the amorphous tungsten silicide film, the impurity diffusion is the same as the ordinary diffusion in bulk. Therefore, very quick diffusion is not generated at a part which is a path for the grain boundary. In this way, the redistribution of the P-type and N-type impurities contained in the polycrystalline silicon films 6a and 6b is suppressed, and the fluctuation of threshold voltage value in a transistor is prevented.

Inventors

• 👤 Hiroyuki Hayashida
• 👤 林田　弘之

Bibliographic Details