Investigation of Shape Transformation of Silicon Trenches during Hydrogen Annealing

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Abstract
We have investigated the corner rounding of a micron-sized silicon trench by annealing under hydrogen pressure of 40–760 Torr in the temperature range of 1000 to 1100°C, and have obtained plots showing the relationship between the curvature of the trench corner and annealing time for various annealing conditions. It was found that the evolution of the curvature of the trench corner follows a time scaling law, expressed by t -1/4. This finding strongly suggests that the shape transformation is attributable to the self-diffusion of the silicon surface under the experimental conditions studied. The surface self-diffusion coefficient in the case of hydrogen pressure of 40 Torr and a temperature of 1000°C was estimated to be approximately 2 ×106 nm2/s.