Study of Vertical Capacitance in an n-Type 4H-SiC Stepped Thick-Oxide Trench MOS Structure
Author(s): Guo, ZY (Guo, Zhiyu); He, Z (He, Zhi); Wang, FX (Wang, Fengxuan); Wu, JM (Wu, Jingmin); Yang, X (Yang, Xiang); Fan, ZC (Fan, Zhongchao); Yang, FH (Yang, Fuhua)
Source: IEEE TRANSACTIONS ON ELECTRON DEVICES DOI: 10.1109/TED.2022.3179995 Early Access Date: JUN 2022
Abstract: In this work, characteristics of trench sidewall capacitance were investigated in a 4H-SiC stepped thick-oxide (STO) trench metal-oxide-semiconductor (MOS) structure. Multigroup SiC trench MOS capacitor test patterns with different structures and geometric parameters were designed and fabricated. From the capacitance-voltage measurements, the characteristics of the described SiC STO trench MOS were calculated and analyzed, including the thicknesses of the oxide at different locations in trench, the position of the oxide step at trench sidewall, and the flat-band voltages as well as the oxide charge densities of MOS from the upper part and lower part of oxide step at trench sidewall. Results showed that the flat-band voltages of MOS from the upper part (10.2 V) and lower part (12.5 V) of trench sidewall step had pronounced positive shifts over the ideal flat-band voltage (0.36 V), indicating a massive negative charges in the sidewall oxide film. Meanwhile, the net oxide charge density of MOS from the lower part of sidewall step (-0.92 x 10(12) cm(-2)) was smaller than that from the upper part (-2.41 x 10(12) cm(-2)), which was likely attributed to the massive shallow states in the oxide and to the poor quality of the thick-oxide film grown via chemical vapor deposition technology. The present works are providing a convenient technology tomonitor the trench MOS structure by measuring the capacitance during SiC trench MOSFETs fabrication.
Accession Number: WOS:000826405600001
Author Identifiers:
Author Web of Science ResearcherID ORCID Number
Guo, Zhiyu 0000-0002-7868-4065
ISSN: 0018-9383
eISSN: 1557-9646
Full Text: https://ieeexplore.ieee.org/document/9796142