Chemical Etching of Silicon

The etch rate of silicon in solutions of various compositions selected from the system , , , and has been investigated over the temperature range 0° to 50 °C. The activation energy of the etching process has been found to be different in the different composition regions. In the high region values of about 4 kcal/mole have been observed and interpreted as characteristic of a diffusion governed reaction. In compositions containing or diluents the activation energy increases, and two values are found. In the high region two values are also observed, one in the range of 10–14 kcal/mole, and the other in the range of about 20 kcal/mole. The significance of the various values of the activation energy is discussed.