Method of manufacturing a semiconductor device having trenches for isolation and capacitor formation trenches

Abstract

At least not less than one capacitor formation trench providing an uneven surface is formed on the surface of a capacitor formation region. Thus, the surface area of a capacitor is increased, which enables improvement of the capacitance of the capacitor per unit area. Further, by forming the capacitor formation trench and an element formation trench that are formed in the surface of the semiconductor substrate by the same step, it is possible to simplify the manufacturing process. Whereas, a dielectric film of the capacitor in the capacitor formation region and a high-voltage gate insulating film in a MISFET formation region are formed by the same step; alternatively, the dielectric film of the capacitor in the capacitor formation region and a memory gate interlayer film between a polysilicon layer and a polysilicon layer in the memory cell formation region are formed by the same step.