Effect of sputtered Mo interlayers on Si (100) substrates for the deposition of diamond film by hot filament chemical vapor deposition

Dense, ultra-smooth and well-distributed nanocrystalline diamond films have been grown by hot filament chemical vapor deposition (HFCVD) on Si (100) substrates with a sputtered Mo interlayer in only 20 min. In order to investigate the effect of a Mo interlayer on the growth of CVD diamond films, each substrate was mounted over a range of HF-substrate separations, df. Spatially resolved scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, X-ray diffraction (XRD), secondary ion mass spectroscopy (SIMS) and focused ion beam (FIB) milling of the deposited material provide a detailed relation of the evolution of film morphology, growth rate, surface roughness, grain size, sp3/sp2 content and phases with df in deposited samples. The deposited diamond film shows no internal stress. It is also found that the diamond nucleation density on sputtered Mo substrate after diamond powder pretreatment is more than 1014/m2, which is a remarkable improvement compared with 1011/m2 on bulk Mo substrate. The reason for the improvement is discussed in detail. This method can be a potential way to produce ultra-smooth nano-crystalline diamond for various applications. Also, the growth time of diamond can be greatly reduced.