Insulated gate semiconductor device and method of manufacturing the same
First Claim
1. An insulated gate semiconductor device comprising a semiconductor base defining a top major surface and a bottom major surface, whereinsaid semiconductor base includes:
- a first semiconductor layer of a first conductivity type being exposed to said top major surface;
a second semiconductor layer of a second conductivity type being formed in a portion of said top major surface within said first semiconductor layer;
a third semiconductor layer of the second conductivity type formed in a portion of said top major surface within said first semiconductor layer by selectively diffusing an impurity, said third semiconductor layer being deeper than said second semiconductor layer, said third semiconductor layer being linked to said second semiconductor layer, said third semiconductor layer surrounding said second semiconductor layer; and
a fourth semiconductor layer of the first conductivity type being selectively formed in a portion of said top major surface within said second semiconductor layer, in said semiconductor base, a trench is formed which is open in said top major surface, which penetrates said fourth and said second semiconductor layers and which reaches said first semiconductor layer, said device further comprises;
a gate insulation film covering an inner wall of said trench;
a gate electrode which is buried within said trench, with said gate insulation film located between said gate electrode and said semiconductor base;
a gate wire line which is disposed on said top major surface through an insulation film so as to extend along said third semiconductor layer, said gate wire line being electrically connected to said gate electrode;
a first major electrode which is disposed on said top major surface, said first major electrode being electrically connected to said second and said fourth semiconductor layers; and
a second major electrode which is disposed on said bottom major surface, said second major electrode being electrically connected to said bottom major surface, said first major electrode is also electrically connected to a side diffusion region which is adjacent to said second semiconductor layer within said third semiconductor layer and has a convexly sloping diffusion structure on a side of said side diffusion region which is adjacent to said second semiconductor layer, and said fourth semiconductor layer is not formed within said third semiconductor layer including said side diffusion region,said trench extends between opposed portions of said third semiconductor layer which face each other across said second semiconductor layer and extend parallel to each other, said trench extending across said side diffusion region in each of said opposed portions of said third semiconductor layer, said trench extending to a portion of said third semiconductor layer located outside said side diffusion region and immediately under said gate wire line, said gate insulation film is not formed immediately on said gate electrode which fills in a longitudinal end portion of said trench located within said portion of said third semiconductor layer immediately under said gate wire line, and said gate electrode filling in said longitudinal end portion is electrically connected to said gate wire line.
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Accused Products
Abstract
The RBSOA of a device is improved. A gate electrode (10) is linked to a p base layer (4) which is formed in a cell region (CR), and a p semiconductor layer (13) is formed to surround the cell region (CR). An emitter electrode (11) is connected to a top surface of a side diffusion region (SD) of the p semiconductor layer (13) and to a top surface of a margin region (MR) which is adjacent to the side diffusion region (SD), through a contact hole (CH). Further, in these regions, an n+ emitter layer (5) is not formed. Most of avalanche holes (H) which are created in the vicinity of the side diffusion region (SD) when a high voltage is applied pass through the side diffusion region (SD), while some of the avalanche holes (H) pass through the margin region (MR) and are then ejected to the emitter electrode (11). Since there is no n+ emitter layer (5) in these paths, a flow of the holes (H) does not conduct a parasitic bipolar transistor. As a result of this, the RBSOA is improved.
20 Citations
11 Claims
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1. An insulated gate semiconductor device comprising a semiconductor base defining a top major surface and a bottom major surface, wherein
said semiconductor base includes: -
a first semiconductor layer of a first conductivity type being exposed to said top major surface;
a second semiconductor layer of a second conductivity type being formed in a portion of said top major surface within said first semiconductor layer;
a third semiconductor layer of the second conductivity type formed in a portion of said top major surface within said first semiconductor layer by selectively diffusing an impurity, said third semiconductor layer being deeper than said second semiconductor layer, said third semiconductor layer being linked to said second semiconductor layer, said third semiconductor layer surrounding said second semiconductor layer; and
a fourth semiconductor layer of the first conductivity type being selectively formed in a portion of said top major surface within said second semiconductor layer, in said semiconductor base, a trench is formed which is open in said top major surface, which penetrates said fourth and said second semiconductor layers and which reaches said first semiconductor layer, said device further comprises;
a gate insulation film covering an inner wall of said trench;
a gate electrode which is buried within said trench, with said gate insulation film located between said gate electrode and said semiconductor base;
a gate wire line which is disposed on said top major surface through an insulation film so as to extend along said third semiconductor layer, said gate wire line being electrically connected to said gate electrode;
a first major electrode which is disposed on said top major surface, said first major electrode being electrically connected to said second and said fourth semiconductor layers; and
a second major electrode which is disposed on said bottom major surface, said second major electrode being electrically connected to said bottom major surface, said first major electrode is also electrically connected to a side diffusion region which is adjacent to said second semiconductor layer within said third semiconductor layer and has a convexly sloping diffusion structure on a side of said side diffusion region which is adjacent to said second semiconductor layer, and said fourth semiconductor layer is not formed within said third semiconductor layer including said side diffusion region, said trench extends between opposed portions of said third semiconductor layer which face each other across said second semiconductor layer and extend parallel to each other, said trench extending across said side diffusion region in each of said opposed portions of said third semiconductor layer, said trench extending to a portion of said third semiconductor layer located outside said side diffusion region and immediately under said gate wire line, said gate insulation film is not formed immediately on said gate electrode which fills in a longitudinal end portion of said trench located within said portion of said third semiconductor layer immediately under said gate wire line, and said gate electrode filling in said longitudinal end portion is electrically connected to said gate wire line. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification