Effects of Surface Temperature on High-Rate Etching of Silicon by Narrow-Gap Microwave Hydrogen Plasma

Abstract

Effects of surface temperature on high-rate etching of Si by narrow-gap microwave hydrogen plasma have been investigated. The etch rate strongly depended on the surface temperature. The optimum temperature for the etching at high rate was about 70 °C. With increasing the temperature higher than 70 °C, decrease in etch rate was observed, and activation energy for the reaction process was estimated to be about -1.8 kcal/mol. This value agreed well with the result of the previous studies using low-pressure plasma conditions. In addition, hydrogen concentration was also affected by the surface temperature. The reduction in hydrogen concentration near the surface was observed in the etched sample at higher temperature. From these results, reaction mechanism causing the decrease in etch rate with the temperature increase has been discussed in terms of both desorption and in-diffusion of hydrogen from the surface.