Silicon tip sharpening based on thermal oxidation technology

Thermal oxidation at low temperatures (below 1050 °C) is widely used in the microfabrication of sharp silicon tips. However, the influences of the oxidation temperature on morphology of the tips have not been investigated in detail. This work systematically studied the dependence of tip profile on the oxidation temperature. Thermal oxidation were performed in four groups at 900, 950, 1000 and 1050 °C. The results show that a trade-off between the tip aspect ratio and diameter should be taken into account when choosing the oxidation temperature. The optimized oxidation temperature to make tips with small apex, high aspect ratio, and smooth surface is around 1000 °C. The tip with a diameter of 6.3 nm was realized through oxidation at 1000 °C.