The Design and Fabrication of High Voltage 4H-SiC Trench Junction Barrier Schottky Diode

• Main Authors: Cheng, Kai-Yu, 鄭凱予
• Other Authors: Huang, Chih-Fang
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/90148417799163668306

碩士 === 國立清華大學 === 電子工程研究所 === 100 === This thesis presents a novel structure of 4H-SiC trench junction barrier schottky diode with floating guard ring edge termination, which has low leakage current and low turn-on voltage. In addition, by incorporating the trench structure in the design, the electric field at the schottky interface and the corresponding barrier lowering effect can be reduced. Therefore, the proposed structure can be fabricated with low work function metal to reduce turn-on voltage without suffering high reverse leakage current. Different p+ spacing, trench depth, schottky metal and doping concentrations were designed, fabricated and characterized. Simulations were also performed to predict device characteristics. TJBS device has leakage current density ten times smaller than the traditional JBS device at 600 V. The forward voltage drop of 2 μm trench Ti-TJBS is 0.96 V while the reverse current density is less than 1×10-7 A/cm2. At room temperature as well as at elevated temperature, the proposed TJBS device has lower leakage current density than that of the SBD and JBS devices. Conductivity modulation behavior is observed in TJBS at high current densities and high temperatures. On the other hand, the blocking voltage of Ti-JBS about 1 kV was achieved using a thermal treatment to increase Schottky barrier height, which is increased from 0.83 eV as deposited to 1.14 eV after 500 °C anneal for 5 minutes. The turn-on voltage is increased from 0.5 V to 1 V.