The Effect of Nitridation on SiC MOS Oxides as Evaluated by Charge Pumping

Daniel B. Habersat; Aivars J. Lelis; J.M. McGarrity; F. Barry McLean; Siddharth Potbhare

doi:10.4028/www.scientific.net/MSF.600-603.743

Paper Titles

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Effect of Post-Oxidation Annealing on High-Temperature Grown SiO₂/4H-SiC Interface
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Influence of Ambient, Gate Metal and Oxide Thickness on Interface State Density and Time Constant in MOSiC Capacitor
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High Frequency Inversion Capacitance Measurements for 6H-SiC n-MOS Capacitors from 450 to 600 °C
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The Effect of Nitridation on SiC MOS Oxides as Evaluated by Charge Pumping
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Criteria for Accurate Measurement of Charge-Pumping Current in 4H-SiC MOSFETs
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Optimization of 4H-SiC MOS Properties with Cesium Implantation
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A Study of Deep Energy-Level Traps at the 4H-SiC/SiO₂Interface and Their Passivation by Hydrogen
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Interface and Carrier Transport Behaviour in Al/HfO₂/SiO₂/SiC Structure
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The Effect of Nitridation on SiC MOS Oxides as Evaluated by Charge Pumping

Abstract:

We have analyzed the effect of post-oxidation nitride anneals (usually with either NO or N2O gases) on SiC MOSFETs. Two 4H:SiC wafers were identically prepared except that one wafer had a nitridation anneal after the gate oxide was formed, while the other was tested as-oxidized. We compared the two processes by making measurements on lateral MOSFETs and MOS capacitors using ID-VGS, C-V, and charge pumping. There was no change in either flatband voltage or interface trap density near the valence band, suggesting that the net fixed charge remained constant (within a few 1011cm-2). However, there was a large shift in the threshold voltage which, when combined with the C-V results, indicates a strong reduction of interface traps near the conduction band of roughly 6.0x1012cm-2 by using the nitridation process. The charge pumping measurements also showed a strong reduction of interface traps. Charge pumping measured a trapping density of 2.5x1012cm-2 for the as-oxidized samples and 5.3x1011cm-2 for the nitrided samples. The frequency-dependence of the charge pumping signal also indicates a spatial distribution of traps, with volumetric trap densities of roughly 1.3x1019cm-3 over 25Å on as-oxidized and 3.8x1018cm-3 over 19Å for nitrided.