| 摘要 |
A portion of a cell plate 91 extending upon a field oxide film 107a and a silicon oxide film 123 is referred to as a lower layer interconnection film 109. The lower layer interconnection film 109 has a concave shape. A through hole 95a is formed in a silicon oxide film 93 reaching the bottom of the concave shape lower layer interconnection film 109. The depth of the through hole 95a is greater in comparison with the case where a through hole is formed on an upper face portion 123a of the silicon oxide film 123. Because the depth of through hole 95a is great, the thickness of the tungsten film 101a formed in through hole 95a becomes thicker. This eliminates the problem that all the tungsten film 101a in the through hole 95a, and then a portion of the lower layer interconnection film 109 are overetched. Therefore, electrical connection between the upper layer interconnection layer 103a and the lower layer interconnection layer 109 can be ensured. |
