Design and Fabrication of a 1.2kV 4H-SiC Trench-Gate Accumulation Channel Mosfet

In this study, we have designed and fabricated a novel <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1.2 \text{kV} 4 \mathrm{H}-\text{SiC}$</tex> trench-gate accumulation channel MOSFET for the first time. The proposed SiC trench MOSFET is generated simultaneously during ion implantation in the N Enrich region. It only needs to be controlled by design and no additional process steps are required. By optimizing the thickness and angle of the hard mask side wall during ion implantation in the N -Enrich region, the concentration of the channel region can be controlled. A low enough channel concentration can form an accumulation channel, which improves the electrical characteristics of the device. The reduction of the thickness of the side wall will lead to the decrease of the breakdown voltage and the specific onresistance. The third quadrant characteristics of the device can be further optimized. With the decrease of the side wall angle, the breakdown voltage is basically unchanged and the specific on-resistance is reduced. The on-state voltage in the third quadrant of the device will also gradually decrease. When the side wall thickness is 300 nm and the angle is 86°, the breakdown voltage of the device is 1760 V, and the specific on-resistance is <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2.5 ~\mathrm{m} \Omega \cdot ~\text{cm}^{2}$</tex>. The on-state voltage in the third quadrant is 1.9 V at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$I_{\text{sd}}=10 ~\mathrm{A}$</tex>. It is further confirmed that the device can be turned off normally when the gate voltage is 0 V. The proposed 4H-SiC trench-gate accumulation MOSFET greatly improve the on-state characteristics and the third quadrant characteristics of the device. In addition, the fabrication and SEM image of the trench-gate accumulation MOSFET are presented in detail.