Abstract: A field effect transistor includes a substrate, an epitaxial layer, a remnant-oxide layer, an electrode, a surrounding-oxide layer, a surrounding-nitride layer, a gate oxide layer, a gate, a P-body region, a source region, an interlayer dielectric and a source electrode. The epitaxial layer on the substrate has a trench having a sidewall and a bottom. The electrode inside the trench is coated subsequently by the surrounding-oxide layer, the surrounding-nitride layer and the remnant-oxide layer. The gate formed on the gate oxide layer is separated from the electrode sequentially by the gate oxide layer, the surrounding-nitride layer and the surrounding-oxide layer. The P-body region and the source region, formed at the epitaxial layer, are separated from the gate by the gate oxide layer. The interlayer dielectric covers the source region and the gate. The source electrode covers the P-body region and the interlayer dielectric, and contacts the source region.

Abstract: A field effect transistor includes a substrate, an epitaxial layer, a remnant-oxide layer, an electrode, a surrounding-oxide layer, a surrounding-nitride layer, a gate oxide layer, a gate, a P-body region, a source region, an interlayer dielectric and a source electrode. The epitaxial layer on the substrate has a trench having a sidewall and a bottom. The electrode inside the trench is coated subsequently by the surrounding-oxide layer, the surrounding-nitride layer and the remnant-oxide layer. The gate formed on the gate oxide layer is separated from the electrode sequentially by the gate oxide layer, the surrounding-nitride layer and the surrounding-oxide layer. The P-body region and the source region, formed at the epitaxial layer, are separated from the gate by the gate oxide layer. The interlayer dielectric covers the source region and the gate. The source electrode covers the P-body region and the interlayer dielectric, and contacts the source region.

Abstract: A field effect transistor is manufactured by firstly forming an epitaxial layer on a substrate. Then, a trench having an oxide layer is formed on the epitaxial layer. The oxide layer has a first electrode portion having a first width and a first height and a second electrode portion having a second width and a second height. A gate oxide layer covering the oxide layer and the second electrode portion has a gate portion having a third width. The epitaxial layer has a body region and a source region, where these two regions are adjacent to the gate portion and covered by an interlayer dielectric. A source electrode covering the body region and the interlayer dielectric contacts the source region. The first height is no less than the second height, the first width is smaller than the second width, and the second width is smaller than the third width.

Abstract: A field effect transistor is manufactured by firstly forming an epitaxial layer on a substrate. Then, a trench having an oxide layer is formed on the epitaxial layer. The oxide layer has a first electrode portion having a first width and a first height and a second electrode portion having a second width and a second height. A gate oxide layer covering the oxide layer and the second electrode portion has a gate portion having a third width. The epitaxial layer has a body region and a source region, where these two regions are adjacent to the gate portion and covered by an interlayer dielectric. A source electrode covering the body region and the interlayer dielectric contacts the source region. The first height is no less than the second height, the first width is smaller than the second width, and the second width is smaller than the third width.

Abstract: A field effect transistor includes a substrate, an epitaxial layer, a remnant-oxide layer, an electrode, a surrounding-oxide layer, a surrounding-nitride layer, a gate oxide layer, a gate, a P-body region, a source region, an interlayer dielectric and a source electrode. The epitaxial layer on the substrate has a trench having a sidewall and a bottom. The electrode inside the trench is coated subsequently by the surrounding-oxide layer, the surrounding-nitride layer and the remnant-oxide layer. The gate formed on the gate oxide layer is separated from the electrode sequentially by the gate oxide layer, the surrounding-nitride layer and the surrounding-oxide layer. The P-body region and the source region, formed at the epitaxial layer, are separated from the gate by the gate oxide layer. The interlayer dielectric covers the source region and the gate. The source electrode covers the P-body region and the interlayer dielectric, and contacts the source region.

Abstract: A method for manufacturing a field effect transistor having a widened trench forms sequentially an epitaxial layer, a trench, an oxidation layer, a trench-oxidation layer, a polysilicon layer, a residual oxidation layer, an electrode portion, a lower trench, a widened trench, a gate portion, a body region, a source region, an interlayer dielectric layer and a source electrode. The trench is formed at the epitaxial layer. The oxidation layer, the trench-oxidation layer and a polysilicon layer are then formed. The residual oxidation layer and the electrode portion are formed in the trench by etching the polysilicon layer and the trench-oxidation layer. The lower trench is formed by etching the epitaxial layer. The widened trench is formed by widening a portion of the trench away from a trench bottom so as to have the electrode portion and the residual oxidation layer disposed at the lower trench.