TRENCH CAPACITOR HAVING AN EPITAXIAL BURIED LAYER

摘要

PURPOSE: A trench capacitor is provided to improve a surface roughness of a trench sidewall. CONSTITUTION: The trench capacitor(310) has a lower side which is extended and has an epitaxial silicon layer(365). The trench capacitor is formed so as to have a bottle shape. The epitaxial layer lines the sidewall of the lower side of the extended trench. The epitaxial layer serves as a buried plate of the trench capacitor. A diffusion region(367) surrounds the lower side of the extended trench to improve an impurity concentration of the epitaxial layer. The diffusion region(367) is formed by an atmosphere doping, a plasma doping, or a plasma immersion implantation.