Yuichi Harada

600 V-IGBT with reverse blocking capability

A vertical 600 V-50 A IGBT with reverse blocking capability is developed for the first time. Our measurement shows reverse blocking capability up to 900 V. This IGBT can be used as a bi-directional IGBT in combination with another reverse blocking IGBT. Bi-directional IGBTs realize the low-loss AC-AC direct conversion circuit. There is great possibility to improve the performance of the reverse blocking IGBT by utilizing the FZ-NPT-IGBT structure.

A new IGBT with a monolithic over-current protection circuit

A new IGBT structure with a monolithic overcurrent sensing and protection circuit has been developed. The feature of this device is a novel integration of a sensing and protection circuit which consists of a sensing IGBT, lateral n-MOSFET, polycrystalline silicon diode and resistor with an IGBT structure. The conventional IGBT fabrication process is available to this device with only one more photomask. Comparison of not only a short circuit safe operating area but both a trade-off characteristics between an on-state voltage drop and a turn-off loss and reverse biased safe operating area with a conventional IGBT has been investigated. Since exhibiting a large short circuit safe operating area without deterioration of any other device characteristics, this device can be applied to not only a soft switching application like voltage resonant circuit but a hard switching application like snubberless inductive load circuit.

A new vertical IGBT structure with a monolithic over-current, over-voltage, and over-temperature sensing and protecting circuit

A new 600 V vertical Insulated Gate Bipolar Transistor (IGBT) structure with monolithically integrated over-current, over-voltage, and over-temperature sensing and protecting functions has been developed to exploit an extremely excellent trade-off characteristic between an on-state voltage drop and turn-off time for the first time. This device can be easily made by the conventional IGBT fabrication process. An accurate and a real-time device temperature detection, as well as a high withstand capability against over-current and over-voltage conditions (short circuit immunity of 30 /spl mu/sec, clamped collector voltage of 640 V), have been achieved. Furthermore, an excellent trade-off characteristic of 1.40 V as an on-state voltage drop and of 0.18 /spl mu/sec as a fall time is also obtained.<<ETX>>

1200 V MCCT: a new concept three terminal MOS-gated thyristor

High power semiconductor devices are required for various applications like a motor control in traction system. Desired device characteristics for such applications are low forward voltage drop, high current capability and large blocking voltage capability. Insulated Gate Bipolar Transistor (IGBT) is now widely accepted for many applications due to its simple gate control and current saturation feature, and many studies have been done for its high voltage application. It has been found that this device structure has a high forward voltage drop at a large current density when designed for the high voltage application. As an alternative, MOS-gated thyristor structures such as MOS Controlled Thyristor (MCT) and Base Resistance controlled Thyristor(BRT) have been studied for the high voltage application because of its simple gate drive capability and low forward voltage drop. However, since this device does not have the current saturation feature, passive protection must be provided for its stable operation. In this paper, a new class of MOS-gated thyristor structure named MOS Controlled Cascode Thyristor (MCCT) which exhibits a superior short circuit withstand capability as well as the low forward voltage drop will be demonstrated for the first time. Furthermore, this device shows a fast switching speed which is comparable to that of an IGBT and an excellent maximum turn-off capability, simultaneously.

High Performance SiC IEMOSFET/SBD Module

SiC power module with low loss and high reliability was developed by utilizing IEMOSFET and SBD. The IEMOSFET is the SiC MOSFET with high channel mobility in which the channel region is the p-type carbon-face epitaxial layer with low acceptor concentration. Elemental technologies for the high channel mobility and the high reliability of the gate oxide have been developed to realize the excellent characteristics by the IEMOSFET. The SBD was designed so as to minimize the forward voltage drops and the reverse leakage current. For the fabrication of these SiC power devices, the mass production technology such as gate oxidation, ion implantation and following activation annealing have been also developed.

A new concept for high voltage MCCT with no J-FET resistance by using a very thin wafer

A high voltage non-punch-through MCCT with newly developed thyristor-centered cells was successfully fabricated for the first time. A 4.22 mm/spl square/ high voltage MCCT with its blocking voltage of 1460 V was fabricated using an inexpensive and an extremely thin bulk wafer of 200 /spl mu/m with low breakage rate of less than 4%. This low breakage rate can be attained by the improvement of wafer grinding method to smooth the wafer edge and so on. Less junction-FET resistance and the thin bulk wafer application are highly effective to achieve a superior electrical characteristic to the punch-through type device using an epi wafer.

2nd generation dual gate MOS thyristor

2nd generation dual gate MOS thyristor (2nd gen.-DGMOS) with 900 V blocking capability are presented to realize an extremely excellent trade-off characteristic between an on-state voltage drop and a turn-off loss with a high turn-off capability and to overcome the IGBTs characteristics for the first time. A superior on-state voltage drop (Von) of 1.29 V at 10 A(71.3 A/cm/sup 2/) with the turn-off loss (Eoff) of 101 /spl mu/J is successfully achieved. These values of Von, Eoff indicate the much superior trade-off characteristic to the IGBT. Furthermore, it should be noted that the 2nd gen.-DGMOS achieves better turn-off capability of approximately 500 A/cm/sup 2/ in a voltage resonant circuit, which is 3.0 times higher than that of the conventional DGMOS.

Analysis of MCCT's turn-on and short circuit operation

The turn-on characteristic and oscillation waveform in the short circuit test of a 1200 V MOS controlled cascode thyristor (MCCT) are described for the first time. A smaller turn-on loss can be successfully achieved in the MCCT than that of an IGBT which was fabricated using the same epitaxial wafer with the MCCT. In the MCCT, the oscillation waveform in the short circuit test takes place for the whole duration. However, a smaller optimized gate capacitance successfully achieves elimination of the oscillation without degradation of the electrical characteristics.

Experimental demonstration of 600 V MCCT

This paper presents the characteristics of a MCCT (MOS controlled cascode thyristor) device with a blocking capability of 600 V for the first time. It should be noted that a superior on-state voltage drop of 2.0 V can be achieved while exhibiting a fast turn-off speed which is comparable to that of an IGBT. Furthermore, the MCCT shows a superior short circuit withstand capability of more than 16 /spl mu/s and a maximum turn-off capability of over 660 A/cm2 at a high temperature condition of 125/spl deg/C, simultaneously, by the application of an n/n/sup +/ source region structure.