| 摘要 |
PURPOSE: A method for manufacturing an SRAM(Static Random Access Memory) is provided to be capable of improving the degree of integration. CONSTITUTION: A trench is formed at the inner portion of a semiconductor substrate(31). At this time, the semiconductor substrate includes a P well(33), an N well(35), and an isolation layer(37). An oxide layer(41) is formed at the trench by sequentially carrying out a selective oxygen ion implantation and a heat treatment. A vertical N type source/drain region(43) is formed at the inner portion of the P well by carrying out the first two-step ion implantation process. A vertical P type source/drain region(45) is formed at the inner portion of the N well by carrying out the second two-step ion implantation process. After a gate isolating layer(47) is formed at the inner wall of the trench, a gate electrode having a hard mask layer is formed at the upper portion of the gate isolating layer.
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