DIAMOND GROWTH ON HARD CARBON-FILMS

A three-step process for enhancing the nucleation density of diamond o n unscratched silicon substrates using microwave-plasma-enhanced chemi cal vapor deposition is described. Hard diamond-like carbon (die) film s with thickness in the range 5-100 nm were first formed on smooth (10 0) silicon surfaces using a vacuum-are plasma deposition technique at room temperature. The dlc-coated silicon substrates were subsequently subjected to a low-temperature pretreatment with a methane-rich plasma for an hour before switching to the diamond nucleation conditions. To investigate the effect of the die film structure on diamond nucleatio n, experiments with silicon substrates coated with evaporated carbon f ilms approximately 50-100 MI thick were also performed under similar p retreatment and diamond nucleation conditions. Diamond films with nucl eation density about 2 x 10(8) cm(-2) were obtained with pretreated di e films, depending on the film thickness and the pretreatment time, wh ereas in the absence of the pretreatment and/or with evaporated carbon films the diamond nucleation density was less than 10(4)cm(-2). The s ignificant enhancement in diamond nucleation density obtained with pre treated die films is attributed to the inherently high etching resista nce of the films resulting from the high fraction of sp(3) bonds. The actual nucleation sites might be very fine carbon or, possibly, SiC pa rticles produced by etching back the die film.