Semiconductor device
AssigneeMitsubishi Electric Corporation
InventorYoshiaki HISAMOTO
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Abstract
A semiconductor device having the present high withstand voltage power device IGBT has at a back surface a p collector layer with boron injected in an amount of approximately 3×1013/cm2 with an energy of approximately 50 KeV to a depth of approximately 0.5 μm, and an n+ buffer layer with phosphorus injected in an amount of approximately 3×1012/cm2 with an energy of 120 KeV to a depth of approximately 20 μm. To control lifetime, a semiconductor substrate is exposed to protons at the back surface. Optimally, it is exposed to protons at a dose of approximately 1×1011/cm2 to a depth of approximately 32 μm as measured from the back surface. Thus snapback phenomenon can be eliminated and an improved low saturation voltage (Vice (sat))-offset voltage (Eoff) tradeoff can be achieved.
Claims7
A semiconductor device comprising:
- a semiconductor element region provided at a front surface of a semiconductor substrate of a first conduction type;
- a collector layer of a second conduction type and a buffer layer of said first conduction type provided in said semiconductor substrate in a direction of a depth of said semiconductor substrate as seen from a back surface of said semiconductor substrate;
- and
- a donor layer including a defect layer in said semiconductor substrate at a region located at a depth of approximately 32 μm as measured from the back surface of said semiconductor substrate, wherein
- said collector layer includes a region of an impurity of said second conduction type in said semiconductor substrate at a region located from the back surface of said semiconductor substrate to a depth of approximately 0.5 μm, with said impurity of said second conduction type injected in an amount of at most 5×1013/cm2,
- said buffer layer contains an impurity of said first conduction type in said semiconductor substrate at a region located at a depth from approximately 0.5 μm to approximately 20 μm as measured from the back surface of said semiconductor substrate, with said impurity of said first conduction type having a concentration with a maximum value of approximately 3×1015/cm3,
- said donor layer includes a defect layer formed with a dose of protons of at most 5×1011/cm2 for exposure, and
- said amount of said impurity injected in said collector layer and said dose of protons forming said defect layer reducing snapback voltage at low temperatures to be approximately less than 2V.
Dependencies are inferred from the claim text.