Semiconductor device and method for producing the same

A semiconductor device comprising:

• a p-type base layer that is provided in a surface layer of a first main surface of a semiconductor substrate, which is an n-type drift layer, and has a higher concentration than the drift layer;
• an n-type emitter layer that is provided in the base layer and has a higher concentration than the base layer;
• a gate insulating film that is provided so as to come into contact with the base layer, the emitter layer, and the drift layer;
• a gate electrode that is provided on a surface of the gate insulating film so as to face the base layer, the emitter layer, and the drift layer;
• an emitter electrode that is provided on the surfaces of the emitter layer and the base layer and is insulated from the gate electrode by an interlayer insulating film;
• a p-type collector layer that is provided on a second main surface of the semiconductor substrate;
• and
• at least one n-type intermediate layer that is provided between the drift layer and the collector layer and includes a pair of layers comprising (i) an n-type field stop layer with a higher concentration than the drift layer and (ii) an n-type disorder reduction region with a lower concentration than the field stop layer,
• wherein, when q is an elementary charge, Nd is the average concentration of the drift layer, εs is the permittivity of the semiconductor substrate, Vrate is a rated voltage, JF is rated current density, and vsat is a saturated velocity in which a carrier speed is saturated with predetermined electric field intensity, a distance index L is represented by the following Expression (1):
• L
• =
• ɛ
• S
• ⁢
• V
• rate
• q
• ⁡
• (
• J
• F
• qv
• sat
• +
• N
• d
• )
• Expression
• ⁢
• ⁢
• (
• 1
• )
• and when the depth of the position where the carrier concentration is the maximum in the field stop layer which is adjacent to the base layer, with the drift layer interposed therebetween, from the second main surface is X and the thickness of the semiconductor substrate is W0, X=0−γL is established and γ is in the range of 0.2 to 1.5.

A semiconductor device comprising:

• a p-type anode layer that is provided in a surface layer of a first main surface of a semiconductor substrate, which is an n-type drift layer, and has a higher concentration than the drift layer;
• an n-type cathode layer that is provided on a second main surface of the semiconductor substrate;
• and
• at least one n-type intermediate layer that is provided between the drift layer and the collector layer and includes a pair of layers comprising (i) an n-type field stop layer with a higher concentration than the drift layer, positioned at a range of at least 15 μm from the second main surface of the semiconductor substrate and (ii) an n-type disorder reduction region with a lower concentration than the field stop layer, which is adjacent to the collector layer side and is closer to the collector layer than is the field stop layer.