THE HYDROGEN REDUCTION OF WF6 - A KINETIC-STUDY BASED ON IN-SITU PARTIAL-PRESSURE MEASUREMENTS

The kinetics of the hydrogen reduction of tungsten hexafluoride were s tudied. The growth rate was measured as a function of the process cond itions, which were determined in situ by means of laser Raman scatteri ng. The partial pressures were measured at a height of 17 mm above the center of a 100 mm wafer in a cold-wall single-wafer low-pressure che mical vapor deposition reactor The hydrogen reduction reaction was on the order of 1/6 in WF6 and 1/2 in H-2. The activation energy was equa l to 64 kJ mol(-1). An analysis of available reaction paths revealed t hat either the formation or the desorption of HF is the rate-limiting step. Since only one activation energy is present, the rate-limiting s tep is valid for the complete regime that was investigated.