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Semiconductor devices and methods of manufacturing the same

  • US 6,531,356 B1
  • Filed: 01/27/2000
  • Issued: 03/11/2003
  • Est. Priority Date: 01/27/1999
  • Status: Active Grant
First Claim
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1. A method of manufacturing a semiconductor device, comprising:

  • selectively forming, on a semiconductor substrate, an oxidation-resistant layer having a masking action against oxidation;

    introducing an impurity of second conductivity type to said semiconductor substrate with said oxidation-resistant layer used as a mask, thereby forming a second well in said semiconductor substrate;

    selectively oxidizing a surface area of said second well with said oxidation-resistant layer used as a mask, thereby forming a LOCOS layer in said second well;

    removing said oxidation-resistant layer;

    introducing an impurity of first conductivity type to said semiconductor substrate with said LOCOS layer used as a mask, thereby forming a first well in said semiconductor substrate in adjacent relation to said second well;

    removing said LOCOS layer;

    introducing an impurity of the first conductivity type to part of said second well, thereby forming a third well in said second well; and

    forming a field effect transistor in each of said first, second and third wells, by a process comprising;

    after introducing a first conductivity type impurity and a second conductivity type impurity in areas of said semiconductor substrate, forming a LOCOS layer in a pattern on said semiconductor substrate to form first conductivity type and second conductivity type low-density impurity layers in said areas under the LOCOS layer, part of said LOCOS layer being formed at least around a gate insulating layer of said field effect transistor;

    forming a gate electrode; and

    forming a high-density impurity layer comprising a source/drain area.

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