Semiconductor memory device and manufacturing method thereof

Abstract

A manufacturing method of a semiconductor memory device comprising the steps of: forming plural trenches in stripes in a semiconductor substrate and filling each of the trenches with an element isolation insulating film to form element isolation regions; sequentially forming a tunnel insulating film and a charge-storable film so as to cover active regions between the element isolation regions; forming an interlayer insulating film on the charge-storable film; forming plural control gates on the interlayer insulating film in a direction orthogonal to a longitudinal direction of the trenches; among source formation regions and drain formation regions alternately provided between the plural control gates, etching the element isolation insulating film in the source formation regions, using as a mask a resist film having openings in the source formation regions, to expose surfaces of the trenches; and carrying out isotropic plasma ion implantation on the source formation regions to form source diffusion layers in the surfaces of the trenches and in the active regions.

Dependencies are inferred from the claim text.