Mutsuhiro Mori

A novel high-conductivity IGBT (HiGT) with a short circuit capability

This paper presents a new high-conductivity IGBT (HiGT) with a DMOS structure and an n-type hole-barrier layer surrounding a p-layer. The hole-barrier layer acts as a barrier to prevent the holes from flowing into the p-layer and stores them in the n-layer. The HiGT provides a collector-emitter saturation voltage (V/sub CE(sat)/) of about 1 V lower than that of the conventional IGBT, while it maintains a high blocking voltage of 3.3 kV by controlling the carrier concentration of the hole-barrier layer. The HiGT has tough short circuit capability of more than 10 /spl mu/s at 125/spl deg/C with a saturation current similar to that of the conventional IGBT.

A novel soft and fast recovery diode (SFD) with thin p-layer formed by Al-Si electrode

A novel, soft and fast recovery diode (SFD) is presented which has extremely thin p-layers formed by an Al-Si electrode and deep p/sup +/-layers. By using the thin p-layer, the hole density in the n/sup -/-layer close to the p-n junction is reduced, and a 1/2.5 lower recovery current peak, 1/3 lower recovery current change, and 1.5 times faster recovery time are realized compared to a conventional p-n diode. Moreover, increasing the barrier height of the p-layer causes the leakage current and forward voltage drop to decrease. It is also demonstrated that electrical noise and turn-on loss of an IGBT module in an inverter circuit can be significantly improved by using the SFD as a free wheeling diode.<<ETX>>

High Gm In0.5Al0.5As/In0.5Ga0.5As high electron mobility transistors grown lattice-mismatched on GaAs substrates

Abstract We have fabricated high quality In 0.5 Al 0.5 As/In 0.5 Ga 0.5 As high electron mobility transistors (HEMTs) with thin buffer layers lattice-mismatched on GaAs substrates by molecular beam epitaxy (MBE). Our step-graded In y Al 1− y As buffer layers efficiently terminate lattice-misfit dislocations at each step interface according to cross-sectional transmission electron microscopy (TEM) and plan-view TEM observations. The buffer layers facilitate high mobility (approximate values of 10,000 cm 2 / V · s at room temperatures), even though the total buffer thickness is smaller than 600 nm. The mobility is comparable to that for HEMTs grown on InP substrates and better than that reported for HEMTs grown on GaAs with much thicker buffers. For a device with a 0.5 μm long, 20 μm wide gate and a 600 nm buffer layer, the peak extrinsic G m is 750 mS/mm, which is higher than that for previously reported HEMTs with the same gate length, including devices on InP substrates. In 0.5 Al 0.5 As/In 0.5 Ga 0.5 As single quantum wells (SQWs) grown on the step-graded In y Al 1− y As buffer layers show intense, sharp photoluminescence spectra, comparable to those of SQWs grown lattice-matched on InP. These results show that the tin step-graded buffer enabled growth of high-quality In 0.5 Al 0.5 As/In 0.5 Ga 0.5 As heterostructures on GaAs substrates.

A Trench-Gate High-Conductivity IGBT (HiGT) With Short-Circuit Capability

This paper describes a new 600-V trench-gate high-conductivity insulated gate bipolar transistor (trench HiGT) that has both a low collector-emitter saturation voltage of 1.55 V at 200 and a tough short-circuit capability of more than 10 . The trench HiGT also has better tradeoff relationship between turn-off switching loss and collector-emitter saturation voltage compared to either an insulated gate bipolar transistor (IGBT) with a planar gate or a conventional trench gate. A reverse transfer capacitance that is 50% lower than that of the planar-gate IGBT and an input capacitance that is 40% lower than that of a conventional trench gate IGBT have been obtained for the trench HiGT.

A Planar-Gate High-Conductivity IGBT (HiGT) With Hole-Barrier Layer

A high-conductivity insulated gate bipolar transistor (IGBT) (HiGT) with a double diffused MOS structure and an n-type hole-barrier layer surrounding a p-layer (planar HiGT) is presented. The hole-barrier layer prevents the holes from flowing into the p-layer and stores them in the n-layer. The planar HiGT provides a better tradeoff between collector-emitter saturation voltage [VcE(sat)] and turn-off loss than conventional IGBTs, regardless of the injection efficiency of the p-layer on the collector side, while it maintains a high blocking voltage by controlling the sheet carrier concentration of the hole-barrier layer. The planar HiGT has a tough short-circuit capability of more than 10 mus at 125degC, with a saturation current similar to that of conventional IGBTs.

High speed, high current capacity LIGBT and diode for output stage of high voltage monolithic three-phase inverter IC

Structure of a high speed, high current capacity Latelal Insulated Gate Bipolar Transistor (LIGBT) and a diode for a 250V1A monolithic three-phase inverter IC are studied. A hybrid structure between Schottky junctions and pn junctions is effective for the diode, but not for the LIGBT. Characteristics of the IC using the LIGBT and diode are also presented.

3.3 kV punchthrough IGBT with low loss and fast switching

This paper presents a new punchthrough (PT) IGBT with a high blocking voltage of 3.3 kV. We numerically show that a high injection efficiency with a p+layer and local lifetime control in an n-layer are more effective in reducing the turn-on and turn-off losses, respectively. A p+epitaxial layer at the collector has been made in order to realize a high injection efficiency, which greatly reduced the turn-on loss, experimentally. When a local lifetime control technique is applied to this new PT IGBT, the turn-off loss is decreased by approximately 50% compared to a conventional PT IGBT with uniform lifetime control of electron irradiation. The new PT IGBT provides fast switching with rise and fall times of about 1 /spl mu/s at 125/spl deg/C. In addition, in this PT IGBT it is easy to apply a high resistivity n-layer without increasing its thickness or losing high blocking voltage in comparison with non-punchthrough (NPT) IGBT, which can get low failure rate (FIT) with cosmic ray.

An insulated gate bipolar transistor with a self-aligned DMOS structure

The authors describe a high-performance insulated-gate bipolar transistor (IGBT) with a self-aligned double-diffused MOS (DMOS) structure (SADMOS). A phosphosilicate glass (PSG) sidewall is used to form the n/sup +/ layer and isolate the gate from the emitter electrode. The DMOS structure, including the 5- mu m gap between the polysilicon gates and the small p-layer region under the n/sup +/ layer, is thus fabricated with a completely self-aligned (SA) process. An SA DMOS IGBT with a breakdown voltage of 500 V had a forward voltage drop of 1.6 V at a forward current density of 1100 A/cm/sup 2/, a fall time of 0.2 mu s and dynamic latching current density of 100 A/cm/sup 2/. The forward voltage drop is reduced by 1/3 over that of an IGBT with a conventional DMOS structure.<<ETX>>

Novel 600-V trench high-conductivity IGBT (Trench HiGT) with short-circuit capability

This paper describes new 600-V trench high-conductivity IGBTs (trench HiGTs) that have lower on-state voltages of 1.42 and 1.55 V at 200 A/cm/sup 2/ and tough short-circuit capabilities of 5 and 10 /spl mu/s, respectively. These HiGT have a better trade-off between turn-off losses and on-state voltages than conventional trench IGBTs, even better than planar IGBTs. They also offer a lower reverse transfer capacitances (-50%) than the planar IGBT. The input capacitance obtained were lower (-30% to -60%) than that of a conventional trench IGBT.

A high power IGBT module for traction motor drive

A 2000-V, 300-A insulated-gate bipolar transistor (IGBT) module consisting of six IGBT chips and two soft-and-fast recovery diode (SFD) chips has been fabricated for the inverter of a traction motor. The module structure and chip layout were designed to provide sufficient reliability and uniform operation among chips. The main electrical characteristics which were obtained from the tradeoff relations between on-state voltages and switching losses of 2000-V chips, namely, a saturation voltage of 3.5 V, a forward voltage of 2.7 V, and a typical turn-off time of 5 mu s, are well suited to driving a motor at a high frequency.<<ETX>>