| 摘要 |
Polycrystalline silicon with high resistance for a semiconductor memory element is prepared by (A) doping a semiconductor substrate (10) with polycrystalline silicon (40), (B) selectively etching the doped silicon to give desirably patterned silicon (41), (C) doping the substrate (10) with a first oxide film (50), (D) removing the rest of the film (50) except the oxide film on the silicon (41) and doping the substrate with nitride film (60), (E) etching part of nitride film to expose partially the surface of the oxide film (50), (F) thermally oxidizing the patterned silicon (41) to form a second oxide film (80), and (G) removing the nitride film (60) and the second oxide film (80).
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