| 摘要 |
PURPOSE:To perform impurity ion implantations to predetermined regions on a semiconductor substrate, groove sides and groove bottom in separate steps by forming a mask used in case of forming an impurity layer in the groove formed on the substrate and on its periphery in multilayers. CONSTITUTION:After a thin thermal oxide film 2 is first formed on a whole single crystalline silicon substrate 1, a thin silicon nitride film 3 is formed by a CVD method, and patterned through a photocomposing step as a mask for an interelement isolating oxide film of its flat part. Then, after a thin silicon oxide film 6 is formed, the film 3 is formed, and then a thick silicon oxide film 4 is formed. These films become a 5-layer structure film as an etching mask in case of forming the substrate. In the final step of essential section, an interelement isolating oxide film 9 is formed on the flat surface of the substrate, the side faces and the bottom of the groove, a channel cut P-type impurity diffused layer 8 is formed thereunder, an N-type impurity diffused layer 10 is formed on the side face of the groove, and a P-type impurity diffused layer 11 is formed on the flat surface. |
