Semiconductor device and method of manufacturing semiconductor device
AssigneeRohm Co., Ltd.
InventorsRyotaro YAGI, Isamu Nishimura, Takahisa Yamaha
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Abstract
The semiconductor device according to the present invention includes a semiconductor layer, a trench formed by digging the semiconductor layer from the surface thereof, a gate insulating film formed on the inner surface of the trench, and a gate electrode made of silicon embedded in the trench through the gate insulating film. The gate electrode has a high-conductivity portion formed to cover the gate insulating film with a relatively high conductivity and a low-conductivity portion formed on a region inside the high-conductivity portion with a relatively low conductivity.
Claims5
A semiconductor device comprising:
- a semiconductor layer;
- a trench formed by digging the semiconductor layer from a surface thereof;
- a gate insulating film formed on an inner surface of the trench;
- and
- a gate electrode made of silicon embedded in the trench through the gate insulating film, wherein
- the gate electrode has a high-conductivity portion formed to cover the gate insulating film with a relatively high conductivity and a low-conductivity portion formed on a region inside the high-conductivity portion with a relatively low conductivity.
A method of manufacturing a semiconductor device, comprising the steps of:
- forming a first trench and a second trench smaller in width than the first trench in a semiconductor layer;
- forming an oxide film on a surface of the semiconductor layer including inner surfaces of the first trench and the second trench;
- forming a doped polysilicon layer made of doped polysilicon doped with an impurity on the oxide film with a thickness for leaving a space in the first trench while filling up the second trench;
- forming a non-doped polysilicon layer made of non-doped polysilicon doped with no impurity on the doped polysilicon layer with a thickness for filling up the space in the first trench;
- and
- removing the doped polysilicon layer and the non-doped polysilicon layer from on portions of the oxide layer located outside the first trench and the second trench by etch-back, for leaving the doped polysilicon layer and the non-doped polysilicon layer in the first trench while leaving the doped polysilicon layer in the second trench.
A method of manufacturing a semiconductor device, comprising the steps of:
- forming a first trench and a second trench smaller in width than the first trench in a semiconductor layer;
- forming an oxide film on a surface of the semiconductor layer including inner surfaces of the first trench and the second trench;
- forming a first non-doped polysilicon layer made of non-doped polysilicon doped with no impurity on the oxide film with a thickness for leaving spaces in the first trench and the second trench respectively;
- converting the first non-doped polysilicon layer to a doped polysilicon layer by implanting an impurity into the first non-doped polysilicon layer;
- forming a second non-doped polysilicon layer made of non-doped polysilicon doped with no impurity on the doped polysilicon layer with a thickness for filling up the spaces in the first trench and the second trench respectively;
- and
- removing the doped polysilicon layer and the second non-doped polysilicon layer from on portions of the oxide film located outside the first trench and the second trench by etch-back, for leaving the doped polysilicon layer and the second non-doped polysilicon layer in the first trench and the second trench.
Dependencies are inferred from the claim text.