Polycrystalline etch

摘要

The mixture of potassium hydroxide, ethylene glycol and water is used at an elevated temperature to etch polycrystalline silicon and single crystalline silicon. Isopropyl alcohol is used to wet the surface of the polycyrstalline silicon immediately prior to etching with the above solution. This improves the etch uniformity due to immediate intimate contact of the etchant with the silicon surface. The etch rate of the polycyrstalline silicon and monocrystalline silicon is changed by varying the temperature of the mixture and/or the percentage of the water in the mixture. The etched angle at which the polycrystalline silicon is etched varies between 65 DEG to 89 DEG C by varying the temperature of the mixture and/or the percentage of the water.