| 摘要 |
PURPOSE: To remove a stepped part from the upside of a substrate by a method, wherein all oxide films which grow in a vertical direction on the substrate is removed off in a drive-in process after N-type impurities and P-type impurities have been injected into a substrate. CONSTITUTION: A photoresist 11 is applied to an oxide film 10 on a substrate 1, the photoresist 11 is removed from an alignment key region 15 and an N-well region 13 by the use of an N-well mask, and N-type impurities are injected into the substrate 1. Then, the photoresist 11 is removed, a photoresist 12 is again applied to the substrate 1, the photoresist 12 is removed from a P-well region 14 by the use of a P-well mask, the exposed oxide film 10 is etched, and P-type impurities are injected into the substrate 1. Then, the photoresist 12 is removed, and a drive-in process is carried out. At this point, a lower part is oxidized at the thin part of the oxide film 10, and an oxide film 10A grows at the thick part conforming to its upper part. By this setup, the surface of the substrate 1 can be made flat.
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