MOS TRANSISTOR METHOD FOR MANUFACTURING IT

摘要

PROBLEM TO BE SOLVED: To solve a problem that the reliability of a gate insulating film is impaired by the stress of silicon-germanium crystal grains when using a polycrystal silicon-germanium film as an MOSFET. SOLUTION: After forming silicon grains of a diameter <=10 nm on an oxide film, the polycrystal silicon-germanium film is formed. Thus, the Ge density of the oxide film interface of the polycrystal silicon-germanium film becomes uniform to reduce lattice distortion and film stress and the reliability of the gate electrode is improved. Thus, a fast MOSFET using an ultrathin oxide film of a film thickness <=1.5 nm is realized.