| 摘要 |
PURPOSE:To enable a semiconductor device to be remarkably enhanced in capacitance without increasing it in size and a groove provided to it in depeth by a method wherein another mask pattern is formed inside an opening pattern provided to an etching mask in a self-aligned manner before a semiconductor substrate is etched for the formation of a trench. CONSTITUTION:A silicon substrate 11 is directionally etched through an RIE method using a silicon oxide film 12 and a silicon nitride film 15 as masks for the formation of a trench 3 to 5mum in depth. In this case, the formed trench has such a structure that a silicon pillar is left unremoved nearly at the center of the trench due to the presence of the silicon nitride film 15. At this point, the silicon oxide film 12 and the silicon nitride film 15 serving as masks become thinner or disappear by etching. Thereafter, a capacitor insulating film of high dielectric or the like and a capacitor electrode are formed inside the trench to form a capacitor. |
