ATOMIC FORCE MICROSCOPE IMAGING FOR PROCESS CHARACTERIZATION IN DIAMOND FILM DEPOSITION

Atomic force microscope (AFM) images are presented for diamond films deposited using two processes. Films were deposited on polished Si from a CH4-H2 mixture by microwave plasma chemical vapor deposition (CVD) for CH4 concentrations in the range 0.4%-2.0%. At the lowest CH4 concentration, the film surface was rough (R(q) = 80 nm) and contained many grains wider than 1-mu and taller than 0.4-mu. At the highest CH4 concentration, the growth of large grains was suppressed, producing much smoother films (R(q) = 25 nm), which may be suitable as mask substrates for x-ray lithography. Filament-assisted CVD was also used; deposition was halted before a continuous film formed. The tallest grains (100-200-nm high) were clustered in intersecting linear arrays corresponding to marks made by diamond-polishing (seeding). Features a few nm high found in flat regions may be diamond nuclei on bare Si formed much later.