Shape Control and Roughness Reduction of SiC Trenches by High-Temperature Annealing

概要

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The high-temperature annealing of SiC trenches has been investigated for improving the shape of trenches and the smoothness of trench sidewalls. In a SiH4-added Ar (SiH4/Ar) atmosphere, the transformation of SiC trenches required a pressure of 80 Torr and a temperature of 1700 °C; The inner surface of the trenches became smoother without significant etching, while the sample surface became rougher. From the time dependence of the curvature at the trench upper corner, the authors consider that both surface diffusion and evaporation–condensation contribute to the transformation, as opposed to the annealing in H2 reported by another group where transformation is driven mainly by evaporation–condensation. The present authors did not observe a significant change in trench shape in a H2 atmosphere at annealing temperatures up to 1400 °C, except for a smoothening of sample surfaces. The proposed two-step annealing process, consisting of annealing at 1700 °C in SiH4/Ar followed by annealing at 1400 °C in H2, realized rounded trench corners and smooth surfaces simultaneously without significant etching.
2009-11-25