Effect of Temperature on Static Friction Characteristics for Silicon Wafer/Silicon Wafer Contact

Abstract

Silicon wafer is often used for a micromachine because of its excellent mechanical characteristics. However, silicon shows a large adhesive force at a high temperature, so it is predicted that a movement of micromachine would get worse with increase of a temperature. Therefore, it is necessary to understand the effect of the temperature on static friction for silicon wafer and it is also necessary to reduce an adhesive force at a high temperature.
In the present study, static friction coefficients of silicon wafer against silicon wafer, SiO₂ and Al thin films were measured by using a milimeter sized mover at the temperature from 20°C to 200°C. We also measured an adhesive forces of silicon wafer against silicon wafer, SiO₂ and Al thin films with increasing a temperature.
It was found that the static friction coefficient of silicon wafer against silicon wafer was increased with the increase of the temperature. This caused by the increase of the adhesive force between silicon wafers. However, if we depositted an SiO₂ and Al thin films on the surface of a silicon wafer with the thickness over 100nm, the frictional force did not vary the temperature and those showed an almost constant small value.