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US 2002/0153558 A1Published application
Semiconductor device and method for manufacturing the same
AssigneeShindengen Electric Manufacturing Co., Ltd.
InventorsToshiyuki Takemori, Masato Itoi, Yuji Watanabe
Life of this patent
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Abstract
The capacitance between the gate electrode film and the drain layer of semiconductor device is reduced while keeping the resistance low, with the withstand voltage of the gate insulating film also being maintained at a sufficient level. A trench 10 is formed with the bottom of the trench at a comparatively shallow position in an N-epitaxial layer 18. The thickness of a bottom surface part 16 of a gate electrode film 11 is formed so as to be thicker than other parts of the gate electrode film 11. Also, when a P type body layer 19 is formed, an interface between the P type body layer 19 and an N-epitaxial layer 18 is located at a deeper position than a bottom end of the gate electrode film 11.
Claims6
A semiconductor device, comprising:
- a semiconductor substrate, in which a drain layer of a first conductivity type and a conductive region of an opposite conductivity-type to the first conductivity type are formed with the conductive region over the drain layer;
- a trench formed as an opening in the conductive region that reaches the drain layer;
- a source region of the first conductivity type that is positioned inside the conductive region, with at least part of the source region being exposed to inner surfaces of the trench;
- a gate insulating film that is formed on the inner surfaces of the trench so that an upper surface of the gate insulating film at a bottom of the trench is deeper than the source region but is shallower than an interface between the drain layer and the conductive region;
- a gate electrode film that is formed on inner surfaces of the gate insulating film;
- and
- a source electrode film that is insulated from the gate electrode film and is connected to the source region.
4 more elements
A semiconductor device, comprising:
- a semiconductor substrate, in which a drain layer of a first conductivity type and a conductive region of an opposite conductivity-type to the first conductivity type are formed with the conductive region over the drain layer;
- a trench formed as an opening in the conductive region that reaches the drain layer;
- a source region of the first conductivity type that is positioned inside the conductive region, with at least part of the source region being exposed to inner surfaces of the trench;
- a gate insulating film that is formed on the inner surfaces of the trench so that parts of the gate insulating film that are located beyond a predetermined depth are thicker than other parts of the gate insulating film;
- a gate electrode film that is formed on inner surfaces of the gate insulating film;
- and
- a source electrode film that is insulated from the gate electrode film and is connected to the source region.
4 more elements
A semiconductor device, comprising:
- a semiconductor substrate, in which a drain layer of a first conductivity type, and a conductive region of an opposite conductivity-type to the first conductivity type are formed with the conductive region over the drain layer;
- a trench formed as an opening in the conductive region that reaches the drain layer;
- a source region of the first conductivity type that is positioned inside the conductive region, with at least part of the source region being exposed to inner surfaces of the trench;
- a gate insulating film that is formed on the inner surfaces of the trench, the gate insulating film being formed so that a thickness of the gate insulating film decreases towards the opening in the conductive region;
- a gate electrode film that is formed on inner surfaces of the gate insulating film;
- and
- a source electrode film that is insulated from the gate electrode film and is connected to the source region.
4 more elements
A method of manufacturing a semiconductor device, comprising the steps of:
- forming a first silicon oxide film on a surface of a semiconductor substrate on which a drain layer of a first conductivity-type has been formed;
- forming an opening at a predetermined position in the silicon oxide film to expose the drain layer;
- forming an opening in the exposed drain layer to form a trench in the drain layer;
- forming a second silicon oxide film on the surface of the semiconductor substrate and inner surfaces of the trench;
- removing the second silicon oxide film from the surface of the semiconductor substrate and inner surfaces of the trench, so as to let the second silicon oxide film remain up to a predetermined depth in the bottom part of the trench;
- forming a third silicon oxide film on inner surfaces of the trench by oxidizing the surface of the semiconductor substrate in the area of the trench;
- depositing a polysilicon film on the surface of the semiconductor substrate and the inner surfaces of the trench, so as to fill up the trench;
- removing the polysilicon film from the surface of the semiconductor substrate and part of the trench;
- removing the third silicon oxide film from the surface of the semiconductor substrate and part of the inner surfaces of the trench;
- and
- forming a fourth silicon oxide on the surface of the semiconductor substrate and the inner surfaces of the trench.
8 more elements
A method of manufacturing a semiconductor device, comprising the steps of:
- forming a first silicon oxide film on a surface of a semiconductor substrate on which a drain layer of a first conductivity-type has been formed;
- forming an opening at a predetermined position in the silicon oxide film to expose the drain layer;
- forming an opening in the exposed drain layer to form a first trench in the drain layer;
- forming a second silicon oxide film on the surface of the semiconductor substrate and inner surfaces of the first trench;
- forming a silicon nitride film that covers the surface of the semiconductor substrate and the inner surfaces of the first trench;
- removing the silicon nitride film from the surface of the semiconductor substrate and a bottom surface of the first trench, so as to expose the second silicon oxide film at the surface of the semiconductor substrate and at the bottom surface of the first trench;
- removing at least part of the first silicon oxide layer and the second silicon oxide layer, as well as the silicon oxide layer exposed at the bottom surface of the first trench, so as to expose the drain layer at the bottom surface of the first trench;
- forming a second trench by forming an opening in the drain layer exposed at the bottom surface of the first trench;
- oxidizing the drain layer in a periphery of the second trench;
- removing a second silicon oxide film and the silicon nitride film from inner side surfaces of the first trench;
- forming a third silicon oxide film on inner surfaces of the first trench and the second trench and on the surface of the semiconductor substrate;
- depositing a polysilicon film on the inner surfaces of the first trench and the second trench and the surface of the semiconductor substrate, so as to fill up the first trench and the second trench;
- removing the polysilicon film from the surface of the semiconductor substrate and part of the first trench;
- removing the third silicon oxide film from the surface of the semiconductor substrate and part of the inner surfaces of the first trench;
- and
- forming a fourth silicon oxide on the surface of the semiconductor substrate and the inner surfaces of the first trench.
13 more elements
Dependencies are inferred from the claim text.