Analysis of 3-Dimensional 4H-SiC MOS Capacitors Grown by Atomic Layer Deposition of Al2O3
3-Dimensional 4H-SiC metal-oxide-semiconductor capacitors have been fabricated to determine the effect of the sidewall on the characteristics of 3-Dimentional gate structures. Al2O3 deposited by Atomic Layer Deposition (ALD) was used as the gate dielectric layer on the trench structure. The 3-D MOS capacitors exhibit increasing accumulation capacitance with excellent linearity as the sidewall area increases, indicating that ALD results in a highly conformal dielectric film. The capacitance – voltage characteristics also show evidence of a second flatband voltage, located at a higher bias than that seen for purely planar devices on the same sample. We also observe that the oxide capacitance of planar and 3-D MOS capacitors increases with temperature. Finally, we have found that the 3-D MOS capacitor has a weaker temperature dependence of flatband voltage in comparison to the conventional planar MOS capacitor due to the incorporation of the (1120) plane in the sidewall.
Robert Stahlbush, Philip Neudeck, Anup Bhalla, Robert P. Devaty, Michael Dudley and Aivars Lelis
M. I. Idris et al., "Analysis of 3-Dimensional 4H-SiC MOS Capacitors Grown by Atomic Layer Deposition of Al2O3", Materials Science Forum, Vol. 924, pp. 490-493, 2018