SEMICONDUCTOR DEVICE AND METHOD FOR MANUFACTURING THE SAME

PROBLEM TO BE SOLVED: To provide a semiconductor device, by which the degrading or yield caused by misfit shifting in an epitaxial silicon film is reduced though the epitaxial silicon film and a polycrystal silicon film on a monocrystal silicon film lie in a row with each other. SOLUTION: An SiON film 38 is an insulation film below a silicon film. Thus, by controlling the ratio of silicon, oxygen and nitride, it is possible to make the thermal expansion coefficient of the insulating film close to the thermal expansion coefficient of silicon. Consequently, during the manufacturing process of the semiconductor, after forming the silicon film, stress caused by the difference between the insulation film and the thermal expansion coefficient will not occur easily in the polycrystal silicon film on the insulating film. Thus, the epitaxial silicon film is not easily given stress from the polycrystal silicon film.