Abstract:iamond possesses excellent electronic and thermal properties. Uniform diamond films with large area are essential to their industrial applications in electronics. Using microwave plasma chemical vapor deposition technology, diamond films were deposited on the silicon wafer of 51~76 mm in diameter. The surface morphology of the diamond films were observed with SEM, and the resistivity of diamond films were measured with ZC36 high resistance instrument. The uniformity of diamond films were characterized by the uniformity of surface morphology and resistivity. The results indicated that the processes of nucleation and growth of diamond film are different because the substrate temperature, the concentration of different carbonic radicals, and the concentration of atom hydrogen vary with the substrate position. So the uniformity of film is different. The film deposited on 51 mm wafer at the appropriate substrate position is more uniform than that on 76 mm wafer. But the resistivity at the center of the films is similar to that at the edge both on 51 mm wafer and 76 mm wafer, which is up to 108 Ω·cm.