Yuichi Onozawa

A study on the short-circuit capability of field-stop IGBTs

The short-circuit failure mechanism of 1200 V trench gate field-stop insulated gate bipolar transistor (IGBT) has been investigated in this paper. Experimental testing shows that most of the devices failed during the blocking state after a few hundred microseconds of the short-circuit turn-off condition. This unusual failure mode was analyzed both with experimental and numerical investigation. It has been determined that due to significantly large leakage current, thermal run-away can occur causing device failure after short circuit turn-off. Due to the smaller heat capacity of the FS-IGBT structure, the device temperature after the turn-off becomes so high that the local heating produced by the high temperature leakage current results in the thermal run-away.

Investigation on the short-circuit capability of 1200 V trench gate field-stop IGBTs

The short circuit failure mechanism of newly developed 1200 V/150 A trench gate field-stop IGBT has been investigated. The devices mainly fail after a few hundred microseconds of the short-circuit turn-off. It has been found that the leakage current due to extreme temperature rise in the backside layers results in thermal runaway during off-state. The device with improved backside layer achieved more than 15 /spl mu/s of short circuit capability while keeping the low on-state voltage drop of 1.55 V.

Development of the 1200V FZ-diode with soft recovery characteristics by the new local lifetime control technique

This paper presents the new 1200V FZ-Diode chip using the newly developed local lifetime control technique which is a combination of the electron irradiation and the back-side laser annealing in order to realize the optimum carrier profile. Furthermore, 20% lower resistivity bulk can be utilized due to optimization of the edge termination structure to have a uniform electric field distribution. As a result, the new 1200V FZ-diode with very soft recovery characteristics has been successfully developed without increase of the reverse recovery losses compared to a conventional diode.

Advanced thin wafer IGBTs with new thermal management solution

This paper presents the new design concepts for improving the short-circuit capability of thin wafer power devices, such as field-stop (FS) IGBTs, by thermal management techniques. The experimental results of thin wafer IGBTs, with lead-frame connection via solid copper emitter electrode, have achieved approximately 34% increase in the critical short circuit energy. In addition, compared to the conventional assembling techniques, the new techniques make it possible to keep the lower device temperature during the normal switching operation. It has been found out that 30% reduction in die size can be expected under the conditions of having the same junction temperature increase (/spl Delta/Tj).

Great improvement in turn-on power dissipation of IGBTs with an extra gate charging function

This paper presents a new gate drive circuit using an extra RC-network to realize low turn-on dissipation of IGBTs. The extra capacitance in the gate circuit assists in charging Miller capacitance, therefore the collector voltage tail region during the turn-on period can be reduced drastically without the turn-on dI/sub c//dt increasing. The proposed gate drive method has been achieved 40% reduction in the turn-on switching power dissipation of 1200V-150A IGBT compared with the conventional gate driving.

600V trench-gate IGBT with Micro-P structure

This paper describes the next generation 600V trench-gate IGBT utilizing the Micro-P structure to realize low noise and low power dissipation. We have achieved “better turn-on di/dt controllability”, “oscillation free turn-off” and “improved Von-Eoff trade-off relationship” in the 600V IGBTs. In a typical inverter operation, the new chip has realized 10% lower power dissipation and the dT<inf>j-c</inf> can be reduced by 2.5deg.C.

1200-V Low-Loss IGBT Module With Low Noise Characteristics and High

This paper presents the enhanced characteristics of a newly developed low-loss and low-noise 1200-V insulated gate bipolar transistor (IGBT) module. In order to realize low-noise emission, it is necessary not only to improve the reverse recovery characteristics of the free wheeling diode (FWD) but also to reduce the low-current turn-on dIC/dt of the IGBT. The new IGBTs with high turn-on dIC /dt controllability and low turn-on power dissipation have been successfully developed by the reduction of Miller capacitance resulting from an optimization of the surface. The 1200-V 450-A IGBT module utilizing the new IGBT and optimized FWD chips has been able to realize 30% reduction of the switching power dissipation when compared to the conventional IGBT module under the operating condition to set the same noise emission level

{d}I_{C}/{d}t

This paper describes the investigation of the IGBT turn-off phenomena especially focused on the di/dt controlling in order to suppress the spike voltage. The design concepts for improvement of the trade-off relationship between the turn-off power dissipation and the spike voltage are represented. The new turn-off di/dt control method, the combination of the smaller gate resistance and controlling the collector injection efficiency, has been able to realize about 30% reduction in the turn-off energy compared to the conventional method, under the condition of the same spike voltage

Controllability

In this paper, a new 1200 V-class ultra-narrow-mesas fin p-body IGBT (U-Fin-P IGBT) is proposed. Different from the previously demonstrated fin p-body IGBT, a much narrower fin (mesa) width (~0.5 μm) is adopted in the U-Fin-P IGBT to further reduce the conduction loss; whereas the difficulty of doing emitter contact lithography on top of the ultranarrow mesa regions is resolved by using a self-aligned contact formation process design. It is found from numerical simulations that for the same turn-off energy loss, the on-state voltage drop Von (at 150°C) of the U-Fin-P IGBT is ~21% lower than that of the fin p-body IGBT. Furthermore, the U-Fin-P IGBT also shows excellent turn-on dVldt controllability.

Investigation of carrier streaming effect for the low spike fast IGBT turn-off

In this paper, the transient turn-ON performance of the 1200 V-class fin p-body insulated gate bipolar transistor (Fin-p IGBT) is numerically analyzed and experimentally characterized. Analysis shows that the gate self-charging effect at the turn-ON transient of the device can effectively be suppressed due to its unique structural features of wide trenches and spacer gates. As a result, the Fin-p IGBT demonstrates excellent controllability on the turn-ON dVCE/dt of the IGBT, and hence the reverse-recovery dVKA/dt of the free-wheeling diode. Compared with conventional floating p-body IGBTs, the Fin-p IGBT can achieve a significant reduction (up to 82%) in the reverse-recovery dVKA/dt, which is of great merit in suppressing the electromagnetic interference noise. Moreover, the turn-ON energy loss of the Fin-p IGBT can be reduced by 53% compared with that of the conventional one at the same reverse-recovery dVKA/dt of 10 kV/μs.