Method of forming semiconductor memory device by selectively forming an insulating film on the drain region
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorsShunpei Yamazaki, Yasuhiko Takemura
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Abstract
A semiconductor memory device capable of being electrically written and erased comprising a floating gate, wherein, a silicon nitride film is incorporated between the drain region and the floating gate. Also claimed is a method for forming the same, which comprises forming a drain region on selected portions of a semiconductor substrate; forming a silicon nitride film or a silicon oxinitride film or a silicon carbide film or an aluminum oxide film selectively on the drain region; coating the substrate with a gate oxide film; and establishing a floating gate and thereafter a control gate.
Claims10
A method for forming a semiconductor memory device comprising the steps of:
- selectively forming a drain region within a semiconductor substrate having a protrusion;
- selectively forming an insulating film comprising a material selected from the group consisting of silicon nitride, silicon oxinitride, silicon carbide and aluminum oxide on said drain region;
- forming a gate oxide film on a channel region of said substrate adjacent to said drain region;
- forming a floating gate over to said drain region with said insulating film interposed therebetween;
- and
- forming a control gate over at least said channel region with said gate oxide film interposed therebetween;
- wherein said drain region is formed in an upper portion of the protrusion of said semiconductor substrate.
A method for manufacturing a semiconductor memory device comprising the steps of:
- forming source and drain regions within a semiconductor layer comprising silicon, thereby defining a channel region therebetween, said semiconductor layer having a protrusion;
- forming a first insulating film comprising silicon nitride selectively on said drain region by a thermal nitriding process;
- oxidizing a surface of said semiconductor layer by a thermal oxidation so that a second insulating film comprising silicon oxide is formed on said semiconductor layer,
- wherein said drain region is formed within said protrusion of the semiconductor layer and said first insulating film is located on a side surface of said protrusion.
A method for manufacturing a semiconductor memory device comprising the steps of:
- forming a drain region within a protrusion of a semiconductor layer comprising silicon;
- forming a first insulating film on a side surface of said protrusion, said first insulating film comprising a material selected from the group consisting of silicon nitride, aluminum oxide, silicon oxinitride and silicon carbide;
- and
- oxidizing a surface of said semiconductor layer except for said side surface by a thermal oxidation so that a second insulating film comprising silicon oxide is formed on said semiconductor layer.
A method for manufacturing a semiconductor memory device comprising the steps of:
- forming a semiconductor layer comprising silicon and having a protrusion wherein an upper portion of said protrusion is added with an impurity of one conductivity type;
- forming a first insulating film comprising a material selected from the group consisting of silicon nitride, aluminum oxide, silicon oxinitride and silicon carbide on a side surface of said upper portion of said protrusion;
- thermally oxidizing a surface of said semiconductor layer to form a second insulating film comprising silicon on a portion of said semiconductor layer;
- and
- forming a floating gate electrode adjacent to said protrusion with said first and second insulating films interposed therebetween.
Dependencies are inferred from the claim text.