SEMICONDUCTOR INTEGRATED CIRCUIT

摘要

PROBLEM TO BE SOLVED: To reduce the rough surface on a side wall of a trench of a trench capacitor by forming the trench capacitor in the shape of a bottle with the lower part of the treanch being larger than the upper part and covering a collar and an epitaxial buried plate from inside with a node dielectric. SOLUTION: A trench capacitor 310 included in a DRAM cell 300 is formed in a silicon wafer substrate 301. A lower part of a trench has a larger diameter or width WL than the diameter or width WU of an upper part. The trench of such a shape is called a bottle trench. And, an epitaxial silicon (epi) layer 365 covers the lower part of the trench below a collar 368 from inside. The epi is doped with an n-type dopant such as As or P and is used as a buried plate of a capacitor. By covering the lower part of the trench by the epi layer from inside, the rough surface to be formed with a node dielectric can be reduced.