Development of High-Quality Gate Oxide on 4H-SiC Using Atomic Layer Deposition

Abstract:

A systematic post-deposition annealing study on Silicon Carbide (SiC) metal-oxide-semiconductor capacitors (MOSCAPs) using atomic layer deposition (ALD)-deposited silicon dioxide (SiO₂) layers was carried out. Anneals were done in oxidising (N₂O), inert (Ar) and reducing (H₂:N₂) ambients at elevated temperatures from 900°C to 1300°C for 1 hour. Electrical characterisation results show that the forming gas treatment at 1100°C reduces the flatband voltage to 0.23 V from 10 V for as-deposited SiO2 layers. The density of interface traps (D_IT) was also reduced by one order of magnitude to 2×10¹¹ cm^-2 eV^-1 at E_C-E_T = 0.2 eV. As an indicator of the improvement, characterisation by x-ray photoelectron spectroscopy (XPS) showed that silicon enrichment present in as-deposited layers was largely reduced by the forming gas anneal, improving the stoichiometry. Time-dependent dielectric breakdown (TDDB) results showed that the majority of forming gas annealed samples broke down at breakdown fields of 12.5 MV × cm^-1, which is about 2.5 MV × cm^-1 higher than for thermally oxidised samples.

• Periodical: Materials Science Forum (Volume 1004)
• Pages: 547-553
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.1004.547
• Online since: July 2020
• Authors: A. Benjamin Renz*, Oliver James Vavasour, Peter Michael Gammon, Fan Li, Tian Xiang Dai, Siavash Esfahani, G.W.C. Baker, Nicholas E. Grant, J.D. Murphy, Philip Andrew Mawby, Vishal A. Shah
• Keywords: 4H-SiC, Atomic Layer Deposition, MOSCAP, Post-Deposition Annealing, Reliability, SiO₂, TDDB

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