| 摘要 |
A method of manufacturing an input circuit of a semiconductor device comprises the steps of forming an N well on the main surface of a P type semiconductor substrate, forming a P well by injecting P type ions upwardly from the N well, and forming an N type region by injecting ions onto the main surface of the P well. An input voltage is applied to the N type region, and the input voltage is applied to the internal circuit formed on the main surface of the semiconductor substrate. A P-N junction is formed between the P well and an N type diffusion layer. When the P-N junction conducts due to the application of an excess voltage into the input voltage, current caused by the excess voltage is absorbed through the N type region formed on the main surface of the N well.
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