Selective deposition of polycrystalline diamond film on Si, SiN_x, SiO₂, AlN, GaN and Ti surface using hot filament chemical vapor deposition

Due to its promising high thermal conductivity, polycrystalline Chemical Vapor Deposited (CVD) diamond has received significant interest as a heat spreader in electronic devices. Selective deposition of polycrystalline diamond is proposed to realize its ultimate potential as an on-wafer layer for spreading heat. In this study, we report photolithography based selective seeding techniques and CVD polycrystalline diamond on semiconductors (Si, AlN, and GaN), dielectrics (SiO₂, SiN_x) and metal (Ti) surfaces. Selectivity and properties of the diamond films were evaluated with scanning electron microscopy (SEM), atomic force microscopy (AFM), surface profilometry and micro Raman spectroscopy. Selectivity of diamond growth on AlN and GaN were hampered by decomposition of the semiconductor in the CVD environment. A thin layer of dielectric mitigated this problem. Interdiffusion of carbon in Si and the dielectrics was observed from energy dispersive x-ray (EDX) study. For Ti, x-ray diffraction confirmed a thin layer of TiC at the interface between diamond and Ti. Successful seeding and selective growth of CVD diamond have been achieved for all surfaces on 100 mm substrate with feature size as small as 5µm.