Fabricating and TCAD Optimization for a SiC Trench MOSFET With Tilted P-Shielding Implantation and Integrated TJBS
Bo Yi, Huan Li, Bingke Zhang, Yi Xu, WenKun Shi, Yong Xiang, Rong Zhou, Junji Cheng, Haimeng Huang, Moufu Kong, Hongqiang Yang
Abstract
In this article, we proposed and fabricated a prototype of single-channel SiC trench MOSFET with integrated trench junction barrier Schottky (TJBS) on the trench side for 1200-V application, named TJBS-MOS. The TJBS is protected by the grounded <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{P}^{+}$ </tex-math></inline-formula> shielding layers under the gate and trench bottom. The measured specific ON-resistance ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{ \mathrm{\scriptscriptstyle ON},\text {sp}}$ </tex-math></inline-formula> ) is 5.95 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}\Omega \cdot $ </tex-math></inline-formula> cm2, with reverse conducting ON-state voltage <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{R\_{} \mathrm{\scriptscriptstyle ON}}$ </tex-math></inline-formula> = 2.6 V at 300 A/cm2, which is reduced by 2.0 V compared with that of the CoolSiC MOSFET. Utilizing TCAD calibration according to the measured results, optimized results show that for the 1200-V-rated TJBS-MOS, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{ \mathrm{\scriptscriptstyle ON},\text {sp}}$ </tex-math></inline-formula> of 2.52 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}\Omega \cdot $ </tex-math></inline-formula> cm2 with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{R\_{} \mathrm{\scriptscriptstyle ON}}$ </tex-math></inline-formula> = 2.04 V at 300 A/cm2 is obtained. Due to reduced channel density, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{ \mathrm{\scriptscriptstyle ON},\text {sp}}$ </tex-math></inline-formula> is increased by 24.8% compared to a CoolSiC MOSFET with the same design rules. Fortunately, a high-frequency figure of merit (HFFOM1: <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{ \mathrm{\scriptscriptstyle ON},\text {sp}} \times {C}_{\text {GD}}$ </tex-math></inline-formula> and HFFOM2: <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{ \mathrm{\scriptscriptstyle ON},\text {sp}} \times {Q}_{\text {GD}}$ </tex-math></inline-formula> ) are improved by 57.2% and 72.9%, respectively, owing to smaller <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${C}_{\text {GD}}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}_{\text {GD}}$ </tex-math></inline-formula> . Combined with reduced reverse recovery charge for the unipolar TJBS, the turn-on loss ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{ \mathrm{\scriptscriptstyle ON}}$ </tex-math></inline-formula> ) and the turn-off loss ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{ \mathrm{\scriptscriptstyle OFF}}$ </tex-math></inline-formula> ) at 25 °C are reduced by 32.8% and 80.7%, respectively. Moreover, under high temperatures, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{ \mathrm{\scriptscriptstyle ON}}$ </tex-math></inline-formula> of the CoolSiC MOSFET increases significantly, while <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{ \mathrm{\scriptscriptstyle ON}}$ </tex-math></inline-formula> of the TJBS-MOS remains unchanged.