| 摘要 |
PURPOSE:To obtain a gate insulating film of excellent quality by providing a phosphorus diffusion layer of high density on the back surface of a substrate so as to getter heavy metal prior to the formation of a gate insulating film after selective oxidation. CONSTITUTION:Poly Si 3 and Si3N4 4 are superposed on SiO2 2 on a P type Si substrate 1, masked by a resist 5 and etched, and then B ions are implanted 6 therein. The resist 5 being removed, high-temperature wet oxidation is applied to form oxide films 7 and 9 and a P<+> layer 8. Then, masked by a resist 10, the layer 9 is removed, and thereby a phosphorus diffusion layer 11 of high density is formed. Next, the resist being removed, the layers 4 and 3 are removed by plasma of CF4+O2, and a gate oxide film 12 and a phosphorus-added poly Si gate electrode 13 are formed. Heavy metal is gettered by the layer 11 on the occasion, and thereby the SiO2 film 12 is turned to be a film of excellent quality and without any defects. Then, windows are made in the film 12, N<+> layers 14a and 14b are provided, SiO2 15 and PSG16 are superposed thereon, holes are made therein, and Al electrodes 17 are fitted. By this constitution, the characteristics of the device can be improved and, in addition, the device can be made to be small-sized and highly-integrated. |
