Semiconductor device and manufacturing method thereof
AssigneeRenesas Electronics Corporation
InventorsYoshiyuki Kawashima, Koichi Toba
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Abstract
An improvement is achieved in the performance of semiconductor device including a nonvolatile memory. In a split-gate nonvolatile memory, between a memory gate electrode and a p-type well and between a control gate electrode and the memory gate electrode, an insulating film is formed. Of the insulating film, the portion between the lower surface of the memory gate electrode and the upper surface of a semiconductor substrate has silicon oxide films, and a silicon nitride film interposed between the silicon oxide films. Of the insulating film, the portion between a side surface of the control gate electrode and a side surface of the memory gate electrode is formed of a silicon oxide film, and does not have the silicon nitride film.
Claims25
A semiconductor device including a memory cell of a nonvolatile memory, the semiconductor device comprising:
- a semiconductor substrate;
- a first gate electrode formed over the semiconductor substrate to form the memory cell;
- a second gate electrode formed over the semiconductor substrate to adjoin the first gate electrode, and form the memory cell;
- a first gate insulating film formed between the first gate electrode and the semiconductor substrate;
- and
- an insulating film formed between the second gate electrode and the semiconductor substrate and between the first gate electrode and the second gate electrode,
- wherein, of the insulating film, a first portion between a lower surface of the second gate electrode and an upper surface of the semiconductor substrate has a first silicon oxide film, a second silicon oxide film, and a first silicon nitride film interposed between the first and second silicon oxide films,
- wherein the first silicon nitride film functions as a charge storage portion of the memory cell, and
- wherein, of the insulating film, a second portion between a side surface of the first gate electrode and a side surface of the second gate electrode is formed of a silicon oxide, and does not have the first silicon nitride film.
A method of manufacturing a semiconductor device including a memory cell of a nonvolatile memory, the method comprising the steps of:
- (a) preparing a semiconductor substrate;
- (b) forming a first gate electrode forming the memory cell over a main surface of the semiconductor substrate via a first gate insulating film;
- (c) forming a silicon oxide film over the main surface of the semiconductor substrate and a side surface of the first gate electrode;
- (d) forming, over the silicon oxide film, a second gate electrode adjoining the first gate electrode via the silicon oxide film, and forming the memory cell;
- (e) removing the silicon oxide film from a portion uncovered with the second gate electrode;
- (f) after the step (e), removing at least a part of a portion of the silicon oxide film located between a lower surface of the second gate electrode and the semiconductor substrate to form a cavity;
- (g) forming a first silicon oxide film over a surface of the semiconductor substrate exposed in the cavity, while forming a second silicon oxide film over the lower surface of the second gate electrode exposed in the cavity;
- and
- (h) forming a silicon nitride film between the first silicon oxide film over the surface of the semiconductor substrate and the second silicon oxide film under the lower surface of the second gate electrode.
Dependencies are inferred from the claim text.