Increasing Mobility in 4H-SiC MOSFETs with Deposited Oxide by In-Situ Nitridation of SiC Surface

Abstract:

We present the improvement of SiO₂/4H-SiC interface quality and high field-effect (FE) mobility (µ_FE) in 4H-SiC MOSFETs. This is achieved by introducing a nitrous oxide (N₂O) plasma in-situ pre-treatment before gate stack formation using plasma enhanced chemical vapour deposition (PECVD) oxide followed by a post deposition anneal (PDA) in diluted N₂O for times ranging from 30 to 120 minutes thereby creating an ultra-thin thermally grown SiO₂ layer at the SiO₂/4H-SiC interface. MOS capacitors with SiO₂ deposited on in-situ pre-treated SiC surfaces had a lower density of interface traps (D_IT) for all PDA durations, compared with devices having untreated PECVD oxides or control devices with 30 nm thermally grown oxide. After PDA for 90 minutes, a minimum D_IT value of 1.2×10¹¹ cm^-2·eV^-1 was measured. A peak µ_FE value reaching 94 cm²/(V·s) was measured in n-channel planar MOSFETs fabricated with PECVD oxide on in-situ pre-treated devices, which significantly exceeds a maximum µ_FE of 6 cm²/(V·s) in control devices.

• Periodical: Solid State Phenomena (Volume 359)
• Pages: 157-162
• DOI: https://doi.org/10.4028/p-vY4b9t
• Online since: August 2024
• Authors: Merve Yakut*, Atreyee Roy, Faiz Arith, Andrew Whitworth, Andrew Alexander, Jacek Gryglewicz, Jake Sheriff, Sarah Olsen, Konstantin Vasilevskiy, Anthony O'Neill
• Keywords: Deposited Gate Dielectric, Mobility, MOSFET, N₂O, Nitridation, PECVD, SiO2/SiC Interface

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