Enhanced nucleation of diamond films assisted by positive dc bias

Diamond nucleation on untreated silicon was enhanced by positive de biasing in a horizontal microwave plasma chemical vapor deposition system. The eff ects of process parameters of bias voltage, methane content, bias time, wor king pressure and microwave power on the diamond nucleation were investigat ed. A nucleation density higher than 10(10) cm(-2) was achieved on an untre ated, mirror-polished silicon substrate by positive de biasing. With a bias voltage between the range of + 200 and + 300 V,it was found that high meth ane content is effective in the enhancement of diamond nucleation. It was a lso found that amorphous carbon was formed under the positive de bias condi tions. Uniform diamond films were obtained by combining the positive de bia s enhanced nucleation process with subsequent growth under the usual microw ave plasma chemical vapor deposition diamond conditions. Diamond films depo sited were characterized by scanning electron microscopy and Raman spectros copy. The effect of positive de biasing on nucleation at a high methane con tent to generate oriented diamond nuclei on (100) Si substrate was explored . (C) 2001 Elsevier Science B.V. All rights reserved.