SEMICONDUCTOR DEVICE
First Claim
1. A semiconductor device comprising:
- a semiconductor layer of a first general conductivity type;
a body layer of a second general conductivity type formed in the semiconductor layer and comprising a channel region;
a source layer formed in the body layer;
a gate electrode disposed on the body layer;
a first well layer of the first general conductivity type formed in the semiconductor layer;
a drain layer of the first general conductivity type formed in the first well layer;
a first withstand voltage boosting layer of the second general conductivity type configured to improve a withstand voltage of the semiconductor device, the first boosting layer being formed in a portion of the semiconductor layer operating as a drift region extending from the drain layer to the body layer;
a second well layer of the first general conductivity type configured to lower an on-resistance and formed in the semiconductor layer under the gate electrode; and
a third well layer of the first general conductivity type configured to lower the on-resistance and formed in the drift region so that the second and third well layers are physically separated from each other.
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Accused Products
Abstract
This invention is directed to offer a MOS transistor that has a high source-drain breakdown BVds, a low on resistance and a high electric current driving capacity. On resistance is lowered by forming an N well layer for lowering on resistance in the drift region. The N well layer is disposed beneath the gate electrode and away from the N well layer with a certain space between them. This space ensures the withstand voltage at the edge of the gate electrode of the drain layer side. Also, the N well layer is formed on the surface of an epitaxial layer in the region that includes a P+L layer. The edge of the N well layer of the drain layer side is located near the edge of the P+L layer of the drain layer side and away from the N well layer. This space makes the expansion of depletion layer from the P+L layer easier, further improving the withstand voltage.
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Citations
8 Claims
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1. A semiconductor device comprising:
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a semiconductor layer of a first general conductivity type; a body layer of a second general conductivity type formed in the semiconductor layer and comprising a channel region; a source layer formed in the body layer; a gate electrode disposed on the body layer; a first well layer of the first general conductivity type formed in the semiconductor layer; a drain layer of the first general conductivity type formed in the first well layer; a first withstand voltage boosting layer of the second general conductivity type configured to improve a withstand voltage of the semiconductor device, the first boosting layer being formed in a portion of the semiconductor layer operating as a drift region extending from the drain layer to the body layer; a second well layer of the first general conductivity type configured to lower an on-resistance and formed in the semiconductor layer under the gate electrode; and a third well layer of the first general conductivity type configured to lower the on-resistance and formed in the drift region so that the second and third well layers are physically separated from each other. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification