| 摘要 |
PURPOSE:To form a uniform diffusion layer on the internal walls of a groove having vertical sidewalls by forming a first thin film and doping an impurity into a second thin film whose diffusion coefficient is greater than that of the first thin film and thereby using the impurity as a diffuser. CONSTITUTION:A groove 13 is formed by etching a p-type silicon substrate 11 on which an SiO2 film 12 has been deposited. After removing the SiO2 film 12 with diluted hydrofluoric acid, an SiO2 film 14 containing no impurity is deposited, e.g., 100nm thick over the entire surface and thereafter, a polycrystalline silicon film 15 is deposited, e.g., 100nm thereon. Then, an As ion is implanted at an angle of incidence 7 deg. inclined in the vertical direction with respect to the substrate surface with a doping amount of 10<15>/cm<2> or greater at an accelerating voltage of 50kev. The substrate is subjected to a thermal treatment in an oxygen atmosphere to cause As within the polycrystalline silicon film 15 to diffuse over the substrate surface and to thereby form an n-type layer 16 on the internal walls of the groove 13. Accordingly, a desired n-type layer can be formed on the internal walls of a thin, deep capacitor groove without damaging the substrate. |
