| 摘要 |
PURPOSE:To perform annealing.diffusing and realize high density integration, by depositing polysilicon on the inner surface of a trench, implanting dopant in a polysilicon substrate via this polysilicon film, and oxidizing the polysilicon film only. CONSTITUTION:On a single crystal silicon substrate 1 a trench 2 with 1mum square caliber is formed to a depth of 4-5mum, by dry etching in which a silicon oxide film 3 formed by CVD method is used as a mask. A polysilicon film 4 of 10-30nm thick is deposited by CVD method, on the whole surface of the silicon substrate containing the inner surface of the trench. After AS ion 5 is implanted in the trench by implanting method under a condition where the depth of mean range is as long as the polysilicon film thickness, the polysilicon layer is oxidized at a temperature in a range of 800-1000 deg.C in an oxygen atmosphere, and turned into a second silicon oxide film 6. After the silicon oxide film 6 is eliminated in a mixed solution of hydrofluoric acid and ammonium fluoride, a gate insulating film 7 and a gate electrode 8 are formed. |
