Shinichiro Matsunaga

Development of Ultrahigh-Voltage SiC Devices

Ultrahigh-voltage silicon carbide (SiC) devices [p-i-n diodes and insulated-gate bipolar transistors (IGBTs)] and switching test have been investigated. As a result, we have succeeded in developing a 13-kV p-i-n diode, 15-kV p-channel IGBT, and 16-kV flip-type n-channel implantation and epitaxial IGBT with a low differential specific on-resistance (Rdiff,on). It was revealed that a power module fabricated using a nanotech resin, Si3N4 ceramic substrate, and W base plate was suitable for ultrahigh voltage and high temperature. A switching test was carried out using a clamped inductive load circuit, which indicated that the energy loss of a circuit with ultrahigh-voltage SiC devices is lower than that of Si devices.

Integrated Bi-directional Trench Lateral Power MOSFETs for One Chip Lithium-ion Battery Protection ICs

A low specific on-resistance bi-directional trench lateral power MOSFET (BTLPM) has been integrated with a controller in a 0.6mum BiCDMOS process for single-cell lithium-ion battery protector, downsizing the footprint of the protector in chip-scale package to 3mm 2, one-third of its multi-chip counterparts. The first-silicon results of the BTLPM switches demonstrated a breakdown voltage of 22V, a specific on-resistance of 6.8mOmegamm2 at a gate voltage of 4V (a gate electrical field of 2.3MV/cm)

Low V f and highly reliable 16 kV ultrahigh voltage SiC flip-type n-channel implantation and epitaxial IGBT

Flip-type n-channel implantation and epitaxial (IE)-IGBT on 4H-SiC carbon face with an epitaxial p++ collector layer was investigated. In this study, we employed the IEMOSFET as a MOSFET structure with original wet gate oxidation method, to realize high channel mobility. We were able to achieve an ultrahigh blocking voltage of more than 16 kV, extremely low forward voltage drop of 5 V at 100 A/cm2 and small threshold voltage shift (<; 0.1 V). These characteristics are useful for Smart Grid and HVDC systems, the use of which would realize a low carbon emission society.

Low Gate Charge 20V Class Trench-aligning Lateral Power MOSFET

A low gate charge high-side N-channel trench lateral power MOSFET (TLPM) is developed. Using trench self-aligning structure, a short gate length and minimum gate-drain overlap are realized, and low gate charge is achieved. The product of on-resistance and gate charge Ron*Qg of 61mOmega*nC (Ron*Qgd of 16.4 mOmega*nC) is the lowest for 20V class integrated device. Thanks to the deep junction depth of N drift region, TLPM has good electrostatic discharge (ESD) tolerance, which is a weak point of conventional lightly doped drain (LDD) MOS. TLPM withstands 2kV pulse test at human body model (HBM) and 200V pulse tests at machine model (MM)

Device Performance and Switching Characteristics of 16 kV Ultrahigh-Voltage SiC Flip-Type n-Channel IE-IGBTs

Ultrahigh-voltage SiC flip-type n-channel implantation and epitaxial (IE)-IGBTs were developed, and the static and dynamic performance was investigated. A large device (8 mm × 8mm) with a blocking voltage greater than 16 kV was achieved, and an on-state current of 20 A was obtained at the low on-state voltage (Von) of 4.8 V. RonAdiff was 23 mΩ·cm2 at Von = 4.8 V. In order to evaluate the switching characteristics of the IE-IGBT, ultrahigh-voltage power modules were assembled. A chopper circuit configuration was used to evaluate the switching characteristics of the IE-IGBT. Smooth turn-off waveforms were successfully obtained at VCE = 6.5 kV and ICE = 60 A in the temperature range from room temperature to 250°C.

High side n-channel and bidirectional Trench Lateral Power MOSFETs on one chip for DCDC converter ICs

Trench lateral power MOSFETs (TLPMs) are suitable for one chip power ICs due to its low specific on- resistance and ease of fabrication with CDMOS devices. In our smart power IC process we integrated both the high side n- channel and bidirectional TLPMs in one chip. In addition, better device characteristics of both devices were obtained with the process integration technology. The high side MOSFET shows 20 mOmegamm2 specific on-resistance with 25 V breakdown voltage and excellent reliability. The bidirectional MOSFET shows 7.0 mOmegamm2 specific on-resistance, which represents 67% of the current mass production value, with a breakdown voltage of 25 V.

Suppression of the forward degradation in 4H-SiC PiN diodes by employing a recombination-enhanced buffer layer

Application of highly N-doped buffer layers or a (N+B)-doped buffer layer to PiN diodes to suppress the expansion of Shockley stacking faults (SSFs) from the epilayer/substrate interface was studied. These buffer layers showed very short minority carrier lifetimes of 30–200 ns at 250°C. The PiN diodes were fabricated with buffer layers of various thicknesses and were then tested under high current injection conditions of 600A/cm2. The thicker buffer layers with shorter minority carrier lifetimes demonstrated the suppression of SSFs expansion and thus that of diode degradation.

Dynamic characteristics of large current capacity module using 16-kV ultrahigh voltage SiC flip-type n-channel IE-IGBT

4H-SiC carbon face flip-type n-channel implantation and epitaxial (IE)-IGBT with an epitaxial p++ substrate was developed and its switching test was carried out. We were able to achieve an ultrahigh blocking voltage greater than 16 kV, extremely low Von (6.35 V at 20 A), and good temperature stability. The switching operation was achieved by connecting three IGBTs in parallel, with a total ICE of 60 A and VCE 5 kV. The turn-off loss and turn-on loss were about 220 mJ and 120 mJ, respectively at room temperature. They show low switching loss of ultrahigh voltage SiC IE-IGBT and the possibility of large scale module with parallel connection.

Static and dynamic performance evaluation of > 13 kV SiC p-channel IGBTs at high temperatures

To examine the effect of the device structure on the on-state voltage (Von), several types of ultrahigh-voltage 4H-SiC p-channel insulated-gate bipolar transistors (IGBTs) were fabricated. A p-channel IGBT with a retrograde charge storage layer (CSL) and an additional JFET ion implantation region exhibited the lowest Von at 200 °C. To obtain a blocking voltage (BV) greater than 13 kV, a junction termination extension (JTE)-dose dependence of the BV was also investigated. Furthermore, ampere-class p-channel IGBTs with optimized device structures were fabricated for the evaluation of the switching loss (5 kV/1 A). Although the turn-off loss increased with an increase in the temperature, the loss remained as low as less than 10 mJ up to 250 °C. This performance renders the ultrahigh-voltage 4H-SiC p-channel IGBTs suitable for high-temperature and high-power applications.