| 摘要 |
A semiconductor processing method of forming field oxide regions on a semiconductor substrate includes, i) providing an oxidation resistant mask over a layer of oxide over a desired active area region on a semiconductor substrate, the mask having a central region and opposed sidewall edges, the oxide layer being thinner in the central region than at the sidewall edges; and ii) oxidizing portions of the substrate unmasked by the mask to form field oxide regions on the substrate. The oxidation resistant mask can be provided by depositing and patterning a nitride layer atop a pad oxide layer. Substrate area not covered the mask is oxidized to produce an oxide layer outside of the mask which is thicker than the pad oxide layer. A thin layer of nitride can then be deposited, and anisotropically etched to produce masking spacers which cover the thicker oxide adjacent the original mask. Mask lifting during subsequent oxidation is restricted, thus minimizing bird's beak encroachment and substrate defects.
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