Japan's Rohm Co Ltd has started mass production of what it claims is the first silicon carbide (SiC) MOSFET (metal-oxide-semiconductor field-effect transistor) with a trench structure (where the gate is formed on the sidewall of a groove in the chip surface). Unlike planar-type MOSFETs, junction gate (JFET) resistance does not exist, enabling greater miniaturization (which is expected to result in on-resistance close to the performance of the original SiC material).
In recent years the requirement to address power supply issues on a global scale has brought increased attention to power supply conversion and the efficient delivery of generated power, says Rohm. SiC power devices are expected to play a major role as key solutions that dramatically reduce loss during power conversion.
As the performance and characteristics of silicon approach their theoretical limits, Rohm was early to focus on SiC as a viable successor to silicon as a semiconductor material due to its higher voltage resistance and lower loss (higher efficiency). The firm claims to have been the first supplier to successfully mass produce SiC MOSFETs in 2010 and it continues to develop products that achieve further reductions in power loss.
Although adopting a trench construction in SiC MOSFETs has been attracting increased attention due to its effectiveness in reducing on-resistance, there has been a need to establish a structure for mitigating the electric field generated in the trench gate region in order to guarantee long-term reliability.
Compared with existing planar-type SiC MOSFETs, in Rohm's new trench-type SiC MOSFET (which uses a proprietary structure) the switching performance is improved (with input capacitance reduced by 35%) and on-resistance is halved in the same chip size. This makes it possible to significantly decrease power loss in a variety of equipment, from industrial inverters and power supplies to power conditioners for solar power systems.
Rohm has also developed a full-SiC power module that incorporates the latest trench-type SiC MOSFETs in a 2-in-1 circuit together with integrated SiC Schottky barrier diodes (SBDs). The 1200V/180A module also features the same rated current as silicon insulated-gate bipolar transistor (IGBT) modules while reducing switching loss by about 42% compared with planar-type SiC MOSFETs.
In addition, the lineup of discrete trench-type SiC MOSFETs is being expanded to include three models for each rated voltage of 650V and 1200V, with rated currents of 118A (650V) and 95A (1200V) respectively.
