| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method of a semiconductor device with low price and high reliability, having at least two types of semiconductor devices, for example, a nonvolatile memory of one layer polysilicon type and a high speed logic circuit, on the same substrate, by means of controlling the contamination caused by photoresist and the like to the minimum, and forming the oxide films with different thicknesses by restraining the increase of the number of manufacturing processes. SOLUTION: This method is provided for manufacturing a semiconductor device in which the first and second semiconductor devices are installed on the same substrate 21 and moreover the thicknesses of the gate oxide films are different among the semiconductor devices. The method includes a process of forming the gate oxide films 23B on the forming region 21B of the second semiconductor device, and at the same time, forming the gate oxide films 23C, which are thicker than the gate oxide films 23B, on the forming region 21C of the first semiconductor device, after forming an impurity diffusion layer 22C whose surface impurity concentration is controlled on the forming area 21C of the first semiconductor device.
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