Abstract
In this report, the flow field and the temperature field of a plasma jet for diamond film preparation are calculated. Moreover, chemical species in plasma jet are estimated, and the species reaching on the surface of the substrate are compared with the thickness distribution of the diamond film fabricated. The main species reaching on the surface of a substrate are calculated and found to be H, C2H2 and CH2 in case of the CH4-H2-Ar plasma jet, and H, CO, C2H2 and CH2 in case of the CH4-H2-O2-Ar plasma jet. The shape of a diamond film agrees well with the distributions of H and CH2 in each plasma jet. Therefore, it can be seen that these species play important roles in diamond growth through boundary reactions and surface reactions. When oxygen is added in a CH4-H2-Ar plasma jet, the deposited diamond film has good crystallinity and a more uniform thickness distribution. This is caused by the facts that the etching of diamond is enhanced in the presence of oxygen, and the etch rate is higher near the middle portion of a diamond film.
