| 摘要 |
PURPOSE:To contrive to improve the capacity of charge accumulation by enabling capacitors to be formed at the same time along two regions of different impurity concentration, by a method wherein a trench region is formed by removing a film which does not allow single crystal growth and a polycrystalline semiconductor layer, and an electrode is formed over the insulation film so as to cover the trench region. CONSTITUTION:An Si oxide film 10 is formed on an Si semiconductor substrate 1. An underlayer Si oxide film 3 is formed on an Si single crystal epitaxial layer 2 and on a polycrystalline Si layer 12, and an Si nitride film 4 is formed thereon. The Si oxide film 3 and the epitaxial layer 2 are partly selective- oxided, thus forming a field oxide film 6 at the element-isolating region, and the nitride film 4 and the oxide film 3 are removed. A part of the substrate 1 surface is exposed by removing also the Si oxide film 10, resulting in the formation of a trench 21. An Si oxide film 8 is formed over the exposed surfaces of the epitaxial layer 2 and the substrate 1, and a polycrystalline Si film 9 over the oxide film 8. |
