Deposition of large area uniform diamond films by microwave plasma CVD

Diamond films with 70 mm in diameter were deposited on silicon substrates with Ar/CH4/H2 gas mixture, using microwave plasma chemical vapor deposition (MPCVD) technique. One designed water-cooling substrate stage was used to improve the uniformity of the surface temperature across the substrate. An uniform substrate surface temperature was obtained at the pressure of 10 kPa when the input microwave power was 5500 W. The condition of the plasma was diagnosed by optical emission spectrum (OES) and the grown diamond films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. The results show that higher microwave power can further improve the uniformity of the temperature distribution across the substrate which in turn increases the uniformity of diamond film. And introducing more H2 into Ar/CH4/H2 gas mixture at high microwave power is effective on the improvement of the quality and the decrease of the stress in the deposited diamond films. The diamond films with low average intrinsic stress of 0.32 GPa were finally deposited with introducing 100 sccm H2 into Ar/CH4/H2 gas mixture at 5500 W.