Role of polymers in CVD growth of nanocrystalline diamond films on foreign substrates



Spin coating of PVA polymer with fine grained diamond powder is used as the nucleation treatment for achieving growth of nanocrystalline diamond (NCD) thin films. The growth is realized by standard microwave plasma chemical vapor deposition (CVD). The morphology and character of deposited NCD film is strongly related to the growth temperature. The low temperature process (430°C) results in a growth of well-faceted continuous films. The high temperature process (830 °C) results in voids and openings in the layer. Addition of PVA as the interlayer between the substrate and the seeding polymer composite leads to more openings. The effect is the most pronounced at 830 °C. This is assigned to thermal instability of PVA and oxygen chemistry present in the early beginning of the CVD growth. An optimized seeding process based on the polymer composite procedure at low substrate temperature and low PVA amount allows the diamond growth on extremely soft substrates.