| 摘要 |
PURPOSE:To enable the formation of flat element-isolating regions by a method wherein a groove is formed in the element-isolating region of a semiconductor substrate, and an oxide film is formed in this groove. CONSTITUTION:After a protection oxide film 8 and an Si nitride film 9 are formed on the surface of a semiconductor substrate 7, the film 9 of a region serving as the element-isolating region is selectively removed. Next, an impurity layer 10 is formed by selective ion implantation with the film 9 as a mask. Then, an oxide film 11 is formed by selectively oxidizing the layer 10. The groove is formed on the substrate 7 by removing the film 11. After a protection oxide film 12 is formed by oxidizing the inclined section and the bottom section of the groove, an Si nitride film 13 is formed over the entire surface of the substrate 7. Only the film 13 coating the bottom of the groove is removed, thus leaving the Si nitride film 13' at the inclined section of the groove. The Si nitride film left on the substrate 7 is used as a mask, and an impurity of the same conductivity type as that of the substrate 7 is diffused to the bottom of the groove. With the films 9 and 13' as a mask, oxide films 16 are selectively formed on the bottom and the inclined surfaces of the groove. Thereby, a structure without a stepwise difference between the element-isolating region and the element-forming region can be obtained. |
