| 摘要 |
PURPOSE:To enable to raise the withstand voltage between the first polycrystalline Si layer and the second polycrystalline Si layer and to enable to favorably form the configuration of a semiconductor memory device by a method wherein the phosphorus concentration of the lower polycrystalline Si film of the upper and lower polycrystalline Si films constituting the first polycrystalline Si layer is made to be higher than that of the upper polycrystalline Si film. CONSTITUTION:An SiO2 film 12 and an Si3N4 film 13 are formed on a silicon substrate 11 and both of the SiO2 film 12 and the Si3N4 film 13 are used as the insulating film of the capacitor part. Firstly, a polycrystalline Si film 14 is made to grow in 2,000Angstrom , and after that, a diffusion is performed for 30min in a phosphorus atmosphere of 950 deg.C and phosphorus is doped. Then, after a polycrystalline Si film 15 is made to further grow in 2,000Angstrom , a diffusion is performed for 20min in a phosphorus atmosphere of 900 deg.C and low-concentration phosphorus is doped. Both of the polycrystalline Si films 4 and 15 are used as the first polycrystalline Si layer. Then, after a patterning is performed on the polycrystalline Si films 14 and 15 according to etching, a heat treatment is performed in an oxidizing atmosphere of 1,000 deg.C, an oxide film 16 is formed and the oxide film 16 is used as the insulating film between the first polycrystalline Si layer and a second polycrystalline Si layer 18. As the oxidizing velocity of the lower polycrystalline Si film having a phosphorus concentration higher than that of the upper polycrystalline Si film of the first polycrystalline Si layer is faster, the oxide film 16 is thickly formed. By this way, the configuration of this semiconductor memory device is favorably formed. |
