A method of depositing nanocrystalline diamond film on a substrate at a
rate of not less than about 0.2 microns/hour at a substrate temperature
less than about 500.degree. C. The method includes seeding the substrate
surface with nanocrystalline diamond powder to an areal density of not
less than about 10.sup.10sites/cm.sup.2, and contacting the seeded
substrate surface with a gas of about 99% by volume of an inert gas other
than helium and about 1% by volume of methane or hydrogen and one or more
of acetylene, fullerene and anthracene in the presence of a microwave
induced plasma while maintaining the substrate temperature less than
about 500.degree. C. to deposit nanocrystalline diamond on the seeded
substrate surface at a rate not less than about 0.2 microns/hour.
Coatings of nanocrystalline diamond with average particle diameters of
less than about 20 nanometers can be deposited with thermal budgets of
500.degree. C.-4 hours or less onto a variety of substrates such as MEMS
devices.