Effect of Ar addition on uniformity of diamond growth by using microwave plasma chemical vapor deposition

Single-crystal diamond was grown over inch size area by using microwave plasma chemical vapor deposition with introduction of Argon. Increase of the growth rate was confirmed by Ar addition under various gas pressures. Improvement of the uniformity of the substrate temperature as well as the growth rate was observed by introducing Ar; over 40% non-uniformity was reduced to < 10% without sacrificing the absolute magnitude of the growth rate over 1.5 in. area under some optimized condition. However, distributions of the temperature do not entirely correspond to that of the growth rate. Numerical simulations indicate differences between the major radicals, which have relatively higher concentrations, in the cases with and without the Ar addition. These results suggest that the importance of the hydrocarbon radicals with many lone pair electrons rather than CH3 to explain the growth rate uniformity.