摘要 |
A semiconductor is made on a silicon substrate containing an impurity of a predetermined polarity having formed therein a well containing an impurity of an opposite polarity to a region in the silicon is provided. The method comprises forming a first masking layer on the surface of the substrate, providing openings in the masking layer and implanting dopant ions of a first polarity into the surface of the substrate in a set of first implant regions in the well on either side of a first central region in the well and in a set of second implant regions adjacent to the well on either side of a second central region adjacent to the well, formation of insulating structures over the first and second regions, forming gate oxide layers above the first and second central regions, forming a second masking layer on the surface of the substrate, providing openings in the masking layer and implanting dopant ions of a second polarity into the surface of the substrate in a set of second implant regions in the well on either side of a first central region in the well and in a set of fourth implant regions adjacent to the well on either side of a second central region adjacent to the well, and formation of conductive gate structures over the gate oxide layers.
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