What’s more, the new device can achieve a world-leading specific on-resistance of 1.84 mΩ (milliohms) cm2, leading to energy savings and equipment downsizing.
SiC-MOSFETs control current flowing through the semiconductor layer between the drain and source electrodes by applying a voltage to the gate electrode. To achieve control with a small voltage, a thin gate-insulating film is required. If high voltage is applied in a trench-type power semiconductor device, a strong electric field can concentrate in the gate and can easily break the insulating film.
To correct this, the electric-field-limiting structure developed by Mitsubishi Electric protects the gate-insulating film. It consists of aluminium and nitrogen ions vertically and obliquely implanted at the bottom of the trench structure, forming an electric-field-limiting layer on the bottom surface of the trench. The electric field applied to the gate-insulating film is reduced to the level of a conventional planar power semiconductor device, thereby improving reliability while maintaining the breakdown voltage of over 1,500V.