Five process factors are varied to find conditions necessary for alpha and beta phase formation in tantalum thin films deposited on SiC. These are: sputtering time, input power, presputter etch time, preheat time at 250 degreesC, and sputtering temperature. An empirical model is developed that predicts the maximum or minimum amount of beta phase possible over a large range of him thickness (similar to 25-similar to 2000 nm). The maximum predicted (average) percent beta phase at the maximum sputtering temperature is only 8%, with 95% confidence bounds of [3%, 17%]. The other factors place a much lower restriction on beta phase formation. Pure alpha phase is easily produced over a wide range of operating conditions. Only a weak relationship is found between film thickness and phase composition. The Ta film resistivity increases with the amount of beta phase, in agreement with the literature.