Charge Sheet Super Junction in 4H-Silicon Carbide: Practicability, Modeling and Design

IEEE Journal of the Electron Devices Society

K. Akshay¹  Shreepad Karmalkar¹ 

[1] Department of Electrical Engineering, Indian Institute of Technology Madras, Chennai, India;

关键词: 4H-SiC;    breakdown voltage;    specific on-resistance;    TCAD simulation;    analytical model;    charge imbalance;   

DOI  :  10.1109/JEDS.2020.3021827

来源: DOAJ

【 摘 要 】

We discuss details of the Charge Sheet SuperJunction (CSSJ) in 4H-Silicon Carbide (SiC). This device was earlier proposed in Si material. A CSSJ is obtained by replacing the p-pillar of a SJ by a bilayer insulator, e.g., Al₂O₃/SiO₂; the inter-layer interface of this insulator has a negative charge-sheet, whose magnitude is easily controlled via the insulator deposition temperature. This charge-sheet depletes the n-pillar. Two potential advantages of this structural modification are brought out. First, it can avoid the problems related to SiC SJ's p-pillar fabrication. Second, it can lower the specific-on resistance, R_ONSP, below that of SJ by 5-45 %, since SiC technology allows the insulator to be thinner than the p-pillar. The critical field, E_C, in SiC is > 10 times higher than that in Si. We give an analytical breakdown voltage, VBR, model, which shows that the V_BR sensitivity to charge imbalance due to inevitable process variations is inversely proportional to E_C; hence, this sensitivity of CSSJ in SiC is > 10 times lower than that in Si. On the other hand, we give numerical simulations to establish that, in spite of E_C differences, the SiC CSSJ inherits the advantage of upto 15% higher V_BR compared to SiC SJ, from its Si counterparts. We show how our prior analytical procedure of designing a SJ can be adapted to design a CSSJ having a lower R_ONSP than the SJ, at a specified V_BR in 1-10 kV range and charge imbalance ≤ 20 %. Our work should strengthen the motivation for fabricating the CSSJ in SiC.

【 授权许可】

Unknown