Semiconductor device and method of manufacturing semiconductor device
AssigneeMitsubishi Electric Corporation
InventorKatsumi NAKAMURA
Life of this patent
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Abstract
A semiconductor substrate includes a drift layer, and a first semiconductor layer and a second semiconductor layer provided between the drift layer and a second electrode. The second semiconductor layer is provided on the second electrode side of the first semiconductor layer, one of the first semiconductor layer and the second semiconductor layer contains point defects, while another of the first semiconductor layer and the second semiconductor layer does not contain point defects, and a maximum oxygen concentration of the semiconductor substrate, maximum [Oi], and an impurity concentration of a first conductivity type in the drift layer, Cdrift, have a predetermined relationship.
Claims29
A semiconductor device comprising:
- a semiconductor substrate that has a first main surface and a second main surface opposite to the first main surface;
- and
- a first electrode and a second electrode that are respectively provided on the first main surface and the second main surface,
- wherein the semiconductor substrate includes:
- a drift layer of a first conductivity type which is provided between the first main surface and the second main surface, and
- a first semiconductor layer and a second semiconductor layer that are provided between the drift layer and the second electrode, each having a peak impurity concentration of the first conductivity type,
- the second semiconductor layer is provided on the second electrode side of the first semiconductor layer,
- one of the first semiconductor layer and the second semiconductor layer contains point defects while another of the first semiconductor layer and the second semiconductor layer does not contain the point defects, and
- when a maximum oxygen concentration in the semiconductor substrate calculated using a conversion coefficient of ASTM F121-79 (Old ASTM) is defined as maximum [Oi] and an impurity concentration of the first conductivity type in the drift layer is defined as Cdrift, a relationship of
- maximum [Oi]=9.40×1016×ln(Cdrift)−2.27×1018
- is satisfied.
A method of manufacturing a semiconductor device, the method comprising:
- a step of preparing a semiconductor substrate of a first conductivity type having a first main surface provided with a first electrode and a second main surface opposite to the first main surface;
- a step of implanting first ions into a portion of the semiconductor substrate on a side closer to the second main surface than a drift layer;
- a step of implanting second ions into the semiconductor substrate on a side closer to the second main surface than the portion into which the first ions have been implanted;
- a step of forming a first semiconductor layer of the first conductivity type by annealing the first ions;
- a step of forming a second semiconductor layer of the first conductivity type by annealing the second ions;
- and
- a step of forming a second electrode on the second main surface,
- wherein one of the first semiconductor layer and the second semiconductor layer contains point defects while another of the first semiconductor layer and the second semiconductor layer does not contain the point defects, and
- when a maximum oxygen concentration in the semiconductor substrate calculated using a conversion coefficient of ASTM F121-79 (Old ASTM) is defined as maximum [Oi] and an impurity concentration of the first conductivity type in the drift layer is defined as Cdrift, a relationship of
- maximum [Oi]=9.40×1016×ln(Cdrift)−2.27×1018
- is satisfied.
Dependencies are inferred from the claim text.