| 摘要 |
PURPOSE:To diffuse a plurality of dopants simultaneously through a high- temperature heat treatment by forming, as a diffusion source, a silicon oxide film, in which the dopants are nonuniformly distributed in the direction of film thickness, on the surface of a semiconductor. CONSTITUTION:A trench groove is formed in a p-type single crystal silicon substrate. 3nm of BSG:B concentration = 6X10<19>atoms/cm<3> are formed on the surface of the groove by LPCVD and annealed for 10 minutes at 900 deg.C. 100nm of BAsSG:B concentration=6X10<19>atoms/cm<3> and As concentration = 5X10<20>atoms/cm<3> are accumulated by LPCVD method again. After the oxidation for 4 hours at 1000 deg.C and then for 1 hour at 800 deg.C in a hydrogenated inert gas, diffusion is conducted for 10 minutes at 1000 deg.C in nitrogen so that n<+> (As) layer and p<-> (B) layer are made in the substrate. AsSG and BSG are peeled off by hydrofluoric acid, etc., a silicon oxide/silicon nitride/silicon oxide film is formed on the surface of the trench and an electrode is embedded in the trench so that a capacitor is completed. |
