Semiconductor device i.e. dynamic random access memory device, producing method, involves forming recess by isotropic etching of base area of another recess, where former recess includes larger width than width of latter recess

摘要

The method involves forming a recess (55) in a substrate (51A), and forming a plasma oxide layer (56) over the substrate. The layer is etched, so that a part of the layer remains on side walls of the recess. Another recess is formed by isotropic etching of a base area of the former recess, where the latter recess includes a larger width than a width of the former recess. A gas mixture of carbon fluoride (CF4) and oxygen gases (CO2) with a flow ratio of CF4-gas to CO2 gas is from 1 to 2, is utilized. A gas mixture of oxygen and nitrogen gas is utilized in a photoresist removing chamber.