Method of manufacturing semiconductor memory device having trench memory

Abstract

A method of manufacturing a semiconductor memory device having a trench memory capacitor. First masks are formed on an element forming region of a semiconductor substrate formed of the element forming region and an element isolation region. A film formed of a different material from that of the first masks is deposited and is etched by anisotropic dry etching to leave second masks around the first mask. The semiconductor substrate is selectively etched using the first and second masks as an etching mask so as to form a first groove in the element isolation region. An insulation film is buried in the first groove. A portion of the first mask, formed at least above memory capacitor forming regions in the element forming region, is removed by etching, thereby forming a third mask on a portion excluding the memory capacitor forming region. The semiconductor substrate is selectively etched by using the second and third masks and the insulation film buried in the first groove as an etching mask so as to form second grooves in the respective memory capacitor forming regions. A distance between the first and second grooves is defined by the second masks in a self-alignment manner. A capacitor electrode is formed in the second grooves through a gate insulation film.