A method for manufacturing a power semiconductor device includes: forming a drift region of a first conductivity type, a second emitter region of a second conductivity type, a pn-junction between the second emitter region and drift region, and a first emitter region having a first doping region of the first conductivity type and a second doping region of the first conductivity type; forming a first emitter metallization in contact with the first emitter region to form an ohmic contact between the first emitter metallization and the first doping region, and to form a non-ohmic contact between the first emitter metallization and the second doping region; and forming a second emitter metallization in contact with the second emitter region. The first emitter region is formed using a mask that is aligned with respect to the second emitter region, so that the first and second doping regions are formed in aligned relation.

A semiconductor device includes a semiconductor part having a first surface and a second surface opposite to the first surface, a first electrode on the first surface, a second electrode on the second surface, first to third control electrodes between the first electrode and the semiconductor part. The first to third control electrodes are biased independently from each other. The semiconductor part includes a first layer of a first-conductivity-type, a second layer of a second-conductivity-type, a third layer of the first-conductivity-type and the fourth layer of the second-conductivity-type. The second layer is provided between the first layer and the first electrode. The third layer is selectively provided between the second layer and the first electrode. The fourth layer is provided between the first layer and the second electrode. The second layer opposes the first to third control electrode with insulating films interposed.

Provided is a method for manufacturing a semiconductor device that improves the reliability of the semiconductor device under thermal stress and the assembly performance of the semiconductor device in manufacturing steps. The method includes the following: forming a first electrode by depositing a first conductive film onto one main surface of a semiconductor substrate and patterning the first conductive film; forming a first metal film corresponding to a pattern of the first electrode onto the first electrode; forming a second electrode by depositing a second conductive film onto the other main surface of the semiconductor substrate; forming a second metal film thinner than the first metal film onto the second electrode; and collectively forming a third metal film onto each of the first metal film and the second metal film by electroless plating.

A predetermined relational expression holds where a first distance along the in-plane direction from a channel of the first semiconductor layer to a third semiconductor layer that is the other of the collector layer and the cathode layer is designated as W, a second distance from the channel of the first semiconductor layer to the second semiconductor layer is designated as S, and a diffusion coefficient and a lifetime of a part of the semiconductor substrate between the channel of the first semiconductor layer and the third semiconductor layer are designated as D and τ, respectively.

At least one circuit element may be formed on a front side of a ringed substrate, and the ringed substrate may be mounted on a mounting chuck. The mounting chuck may have an inner raised portion configured to receive the thinned portion of the substrate thereon, and a recessed ring around a perimeter of the mounting chuck configured to receive the outer ring of the ringed substrate therein. At least one solder bump may be formed that is electrically connected to the at least one circuit element, while the ringed wafer is disposed on the mounting chuck.

In a semiconductor device, a p.sup.+ back gate region (PBG) is arranged in a main surface (S1) between first and second portions (P1, P2) of an n.sup.+ source region (SR), and arranged on a side closer to an n.sup.+ drain region (DR) with respect to the n.sup.+ source region (SR). Thereby, a semiconductor device having a high on-state breakdown voltage can be obtained.

Power is inverted using double-base-contact bidirectional bipolar transistors in a three-level-inverter topology. The transistors not only switch to synthesize a PWM approximation of the desired AC waveform, but also have transient phases of diode conduction before each full turn-on or turn-off.

An electric assembly includes a reverse conducting switching device and a rectifying device. The reverse conducting switching device includes transistor cells for desaturation configured to be, under reverse bias, turned on in a desaturation mode and to be turned off in a saturation mode. The rectifying device is electrically connected anti-parallel to the switching device. In a range of a diode forward current from half of a maximum rating diode current of the switching device to the maximum rating diode current, a diode I/V characteristic of the rectifying device shows a voltage drop across the rectifying device higher than a saturation I/V characteristic of the switching device with the transistor cells for desaturation turned off and lower than a desaturation I/V characteristic of the switching device with the transistor cells for desaturation turned on.

A driver circuit (101) is connected to a control terminal of a semiconductor switching element (1). The driver circuit (101) includes an input circuit (3) connected to an input terminal (50), and an output control circuit (4) connected to the input circuit (3). A pulse signal output from the output control circuit (4) is input to a dead time adjustment circuit (13). The dead time adjustment circuit (13) includes a delay circuit which can delay the rising edge and the falling edge of the pulse signal output from the output control circuit (4) on the basis of signals from temperature analog output circuits (11) and (12). An output from the dead time adjustment circuit (13) is input to the drive circuit (5). The drive circuit (5) outputs a drive signal to an output terminal (51) of the driver circuit (101).

A power device comprises at least one power semiconductor module comprising a wide bandgap semiconductor element; and a cooling system for actively cooling the wide bandgap semiconductor element with a cooling medium, wherein the cooling system comprises a refrigeration device for lowering a temperature of the cooling medium below an ambient temperature of the power device; wherein the cooling system is adapted for lowering the temperature of the cooling medium in such a way that a temperature of the wide bandgap semiconductor element is below 100° C.