Pw. May et al., DEPOSITION OF DIAMOND FILMS ON SAPPHIRE - STUDIES OF INTERFACIAL PROPERTIES AND PATTERNING TECHNIQUES, DIAMOND AND RELATED MATERIALS, 3(11-12), 1994, pp. 1375-1380
Polycrystalline diamond films were grown on single crystal sapphire su
bstrates using hot filament chemical vapour deposition (CVD). Problems
with poor adhesion, stress and film cracking became severe for deposi
ted areas greater than about (100 mum)2. Scanning electron microscopy
analysis showed the films to be failing both at the interface and in t
he diamond layer itself. Transmission electron microscopy cross-sectio
ns of the interface showed that the interface was clean and free from
non-diamond carbon impurities. Spallation problems in the diamond film
could be reduced by introducing a barrier layer of epitaxial silicon
grown on the sapphire prior to the diamond CVD step. Patterned silicon
-on-sapphire wafers were then used as substrates for CVD of diamond in
order to define features of linewidth more than 10 mum in the diamond
films. Two methods were used: selective nucleation and lift off.