| 摘要 |
PURPOSE:To make an inter-element isolation breakdown voltage big enough and to realize high integration density and large capacity by a method wherein one end of the third impurity diffusion layer of the second conductivity type which is formed on the surface of side walls near the bottom of a groove at a silicon substrate of the first conductivity type separates the space in relation to the first impurity diffusion layer of the first conductivity type which is formed at the bottom of the groove. CONSTITUTION:After a thick silicon oxide film 8 and a p<+> type impurity diffusion layer 6 have been formed, a p<+> type impurity 15 is doped by ion implantation into the surface region at side walls of a groove 5 and the p<+> type impurity is diffused by heat treatment so that a p<+> type impurity diffusion layer 100 can be formed. Then, after an n<+> type impurity 16 has been doped by ion implantation into the surface region of side walls of the groove 5 by making use of an oxide film 4 as a mask, this n<+> type impurity is diffused by heat treatment so that an n<+> type impurity diffusion layer 120 can be formed. During this process, an ion is implanted from the oblique direction and is heat-treated so that, at the side walls near the bottom of the groove 5, one end of the n<+> type impurity diffusion layer 120 can separate the space in relation to the p<+> type impurity diffusion layer 6. Through this constitution, it is possible to increase an inter-element isolation breakdown strength and to obtain a big electric charge storage capacity. |
