SEMICONDUCTOR DEVICE AND MANUFACTURE THEREOF

PURPOSE:To micronize an element restraining a buried contact layer from diffusing below an element isolating selection oxide film by a method wherein a diffusion layer loaded with conductive impurities is formed under the buried contact layer. CONSTITUTION:A buried contact layer and a MOS-type transistor formed adjacent to it are composed of a P-type silicon substrate 101, an element isolating selective oxide film 102, a first stopper layer 103, a silicon oxide film 104, an opening 105, a second stopper layer 106, a polycrystalline silicon wiring layer 107, and a buried contact layer 108. As the buried contact layer 108 is restrained from diffusing below the element isolating selective oxide film 102, the two buried contact layers 108 adjacent to the element isolating selective oxide film 102 can be electrically insulated from each other even when the element isolating selective oxide film 102 is shortened in space, and thus a semiconductor device can be micronized. As a stopper can be dispensed with at selective oxidation, a process can be shortened and the semiconductor device can be lessened in manufacturing cost.