| 摘要 |
A gate oxide film 18 and a gate electrode 20 are formed on a surface of a P-type substrate 14. A concave portion 42 is provided in a region of the P-type substrate 14, the region being contiguous to the gate electrode 20. On the P-type substrate 14, an N-type drain region 30 is disposed on the opposite side of the gate electrode 20 from the concave portion 42. N-type impurities are implanted into the P-type substrate 14 at a predetermined angle relative to the latter, thereby forming an N-type region 44 which includes a region underneath the concave portion 42 and which is partially submerged beneath the gate oxide film 18. P-type impurities are then implanted into the P-type substrate 14 at right angles to the latter, thus forming a P-type region 46 which includes a region underneath the concave portion 42 while covering the N-type region 44 and which forms a PN junction diode in combination with the N-type region 44.
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