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Investigation of diamond deposition uniformity and quality for freestanding film and substrate applications

: Zuo, S.S.; Yaran, M.K.; Grotjohn, T.A.; Reinhard, D.K.; Asmussen, J.


Diamond and Related Materials 17 (2008), Nr.3, S.300-305
ISSN: 0925-9635
Fraunhofer ILT ()

In this paper, we report on microwave CVD deposition of high quality polycrystalline diamond and on related post-processing steps to produce smooth, flat and uniformly thick films or diamond substrates. The deposition reactor is a 2.45 GHz microwave cavity applicator with the plasma confined inside a 12 cm diameter fused silica bell jar. The deposition substrates utilized are up to 75 mm diameter silicon wafers. The substrate holder is actively cooled with a water-cooled substrate holder to achieve a substrate surface temperature of 600-1150 C. The pressure utilized is 60-180 Torr and the microwave incident power is 2-4.5 kW. Important parameters for the deposition of thick films with uniform quality and thickness include substrate temperature uniformity as well as plasma discharge size and shape. As deposited thickness uniformities of ± 5% across 75 mm diameters are achieved with simultaneous growth rates of 1.9 m/h. The addition of argon to the deposition gases improv es film deposition uniformity without decreasing growth rate or film quality, over the range of parameters investigated. Post-processing includes laser cutting of the diamond to a desired shape, etching, lapping and polishing steps.