| 摘要 |
PURPOSE:To prevent punch through between neighboring small hole type capacitor elements, by providing a first small hole, and providing a second small hole, whose diameter of the opening is smaller than the size of a mask, in which the first small hole is formed. CONSTITUTION:With a silicon nitride film 4B as a thermal oxidation resisting mask, a silicon oxide film 7 is formed on the inner wall of a small hole 6. The oxidation of the inner wall of the small hole 6 isotropically progresses into a semiconductor substrate 1. Therefore, a boundary surface between the silicon oxide film 7 at the corner part of the small hole 6 and the semiconductor substrate 1 can be made to be an arc shape. With the silicon nitride film 4B and the silicon oxide film 7 as masks, the silicon oxide film 7 is etched, and the surface of the semiconductor substrate 1 is exposed. The thin bottom part of the silicon oxide film 7 is etched faster than the side part, and a second small hole 8 is formed. The diameter of the opening of the small hole 8 is specified by the silicon oxide film 7 at the side part of the small hole 6. Said diameter becomes smaller than the diameter of the opening in the mask 4 where the small hole 6 is formed. The distance between the neighboring small holes 8 is not contracted, and the punch through can be prevented. |
