Low temperature diamond film fabrication using magneto-active plasma CVD

Using magneto-active plasma CVD, diamond films have been fabricated at 0.01 torr with a substrate temperature of about 400°C. From the viewpoint of increasing plasma density, a gas mixture, CH₃OH (H₂ + He), obtained by adding a helium to a usually-used gas mixture CH₃OH H₂, has been employed in this study. For a constant CH₃OH concentration (30%), microcrystalline diamond films of good quality can be obtained at a ratio of He (H₂ + He) up to 50%, and the growth rate increases with an increase in the ratio. When He (H₂ + He) is higher than 50%, graphite appears in the film because of the heavy bombardment on the diamond surface by the accelerated helium species in the plasma at low pressure (0.01 torr).