4.5-kV 20-mΩ.cm² Implantation-Free 4H-SiC BJT with Trench Structures on the Junction Termination Extension

Abstract

Abstract.A single-mask junction termination extension with trench structures is formed to realize a 4.5 kV implantation-free 4H-SiC bipolar junction transistor (BJT). The trench structures are formed on the base layer with dry etching using a single mask. The electric field distribution along the structure is controlled by the number and dimensions of the trenches. The electric field is distributed by the trench structures and thus the electric field crowding at the base and mesa edges is diminished. The design is optimized in terms of the depth, width, spacing, and number of the trenches to achieve a breakdown voltage (V B ) of 4.5 kV, which is 85% of the theoretical value. Higher efficiency is obtainable with finer lithographic resolution leading to smaller pitch, and higher number and narrower trenches. The specific on-resistance (R ON ) of 20 mΩ.cm 2 is measured for the small-area BJT with active area of 0.04 mm 2 . The BV-R ON of the fabricated device is very close to the SiC limit and by far exceeds the best SiC MOSFETs.

An Intermediate Frequency Amplifier for High-Temperature Applications

“…The final collector mesa to the p-isolation layer was formed to separate the on-wafer devices from each other. The etching uniformity of ±7% was achieved by controlled SiC dry etching [11], [12]. Improving the surface morphology after dry etching and surface passivation minimizes the surface recombination and significantly increase the current gain.…”

Modification of Etched Junction Termination Extension for the High Voltage 4H-SiC Power Devices

“…4H-SiC high voltage bipolar junction transistors (BJTs) are interesting due to their low onresistance (R ON ) and high current density (J C ). Different etching-based junction termination techniques (JTEs) have been shown to improve the breakdown voltage (BV) [1][2][3][4][5][6][7][8][9][10]. Since the etching plays a key role in this type of terminations, it has been a common study to optimize the depths of the JTEs to find the optimum remaining dose for the JTEs whereas the JTEs mostly have equal lengths [1][2][3][4][5][6][7].…”

“…Different etching-based junction termination techniques (JTEs) have been shown to improve the breakdown voltage (BV) [1][2][3][4][5][6][7][8][9][10]. Since the etching plays a key role in this type of terminations, it has been a common study to optimize the depths of the JTEs to find the optimum remaining dose for the JTEs whereas the JTEs mostly have equal lengths [1][2][3][4][5][6][7]. In this paper we experimentally investigated and optimized the etched-JTEs in terms of the length (L JTE ) and remaining dose (D JTE ).…”

“…This technique can be employed for multi-step etched-JTE [1][2][3][4][5] to minimize the total termination length and total device area. Moreover, it can be combined with other termination techniques such as etched rings [6,7], implanted field rings [11][12][13][14][15], bevel-JTE [16] etc. to further improve the termination efficiency.…”