Semiconductor device and manufacturing method thereof
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorsKosei NODA, Nanae SATO
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Abstract
A charge retention characteristic of a nonvolatile memory transistor is improved. A first insulating film that functions as a tunnel insulating film, a charge storage layer, and a second insulating film are sandwiched between a semiconductor substrate and a conductive film. The charge storage layer is formed of two silicon nitride films. A silicon nitride film which is a lower layer is formed using NH3 as a nitrogen source gas by a CVD method and contains a larger number of N—H bonds than the upper layer. A second silicon nitride film which is an upper layer is formed using N2 as a nitrogen source gas by a CVD method and contains a larger number of Si—H bonds than the lower layer.
Claims22
A semiconductor device comprising a nonvolatile semiconductor memory element, the nonvolatile semiconductor memory element comprising:
- a semiconductor region comprising a semiconductor material, the semiconductor region including a source region, a drain region, and a channel formation region;
- a first insulating film formed over the semiconductor region;
- a first silicon nitride film formed over the first insulating film;
- a second silicon nitride film formed over the first silicon nitride film;
- and
- a conductive film formed over the second silicon nitride film,
- wherein the first silicon nitride film contains a larger number of N—H bonds than the second silicon nitride film.
A semiconductor device comprising a nonvolatile semiconductor memory element, the nonvolatile semiconductor memory element comprising:
- a semiconductor region comprising a semiconductor material, the semiconductor region including a source region, a drain region, and a channel formation region;
- a first insulating film formed over the semiconductor region;
- a first silicon nitride film formed over the first insulating film;
- a second silicon nitride film formed over the first silicon nitride film;
- and
- a conductive film formed over the second silicon nitride film,
- wherein the second silicon nitride film has a higher ratio of a concentration of bonds between silicon and at least one of hydrogen and halogen elements to a concentration of nitrogen-hydrogen (N—H) bonds than the first silicon nitride film.
Dependencies are inferred from the claim text.