Method of manufacturing non-volatile memory cell with simplified step of forming floating gate

摘要

A semiconductor device of the present invention includes a semiconductor substrate, stripe-shaped trenches for separating the semiconductor substrate into a plurality of active regions, a buried film having a projecting portion that projects from the semiconductor substrate, buried into the trenches, a source region and drain region of a second conductivity type, which are a pair of regions formed in the active region, for providing a channel region of a first conductivity type for a region therebetween, and a floating gate consisting of a single layer striding across the source region and the drain region, projecting beyond the projecting portion in a manner not overlapping the projecting portion, in which an aspect ratio of the buried film is 2.3 to 3.67.

主权项

1. A method for manufacturing a semiconductor device comprising:
a step of forming, on a semiconductor substrate, an etching mask selectively having a plurality of stripe-shaped openings without an electrode material interposed between the same and the semiconductor substrate; a step of forming trenches for separating the semiconductor substrate into a plurality of active regions, by etching the semiconductor substrate via the openings in the etching mask; a step of burying into the trench a buried film having a projecting portion that projects by a thickness of the etching mask from the semiconductor substrate, by supplying a film material in a filling-back manner from a bottom portion of the trench to an upper face of the etching mask; a step of exposing the active region surrounded by the projecting portions by removing the etching mask, burying an electrode material into the active region, and depositing an electrode material to cover the remaining buried film; a step of forming a floating gate made of the electrode material in the active region, by polishing the electrode material, from a state in which the electrode material is exposed, until an uppermost face of the electrode material reaches the same height as that of a top face of the projecting portion of the buried film; a step of forming a recess between the adjacent floating gates, by selectively removing the projecting portion of the buried film; a step of exposing a pair of a first region and a second region made of a part of the semiconductor substrate at an interval from each other, by selectively removing the floating gate along a longitudinal direction of the trench, and forming a channel region of a first conductivity type in a region between the first and second regions; and a step of forming a source region in the first region and forming a drain region in the second region, by supplying a second conductivity-type impurity into the first region and the second region.