A novel approach to the formation of amorphous carbon nitride film on silicon by ECR-CVD

Amorphous carbon nitride films have been synthesized on silicon by using an ECR-CVD system equipped with a DC bias and a mixture of C2H2, N-2 and Ar. Excess argon together with the application of DC bias can increase the rati o of nitrogen to carbon in the film up to 41% as determined by XPS. FTIR sp ectrum shows an absorption band between 1000 and 1700 cm(-1) which proves t he incorporation of nitrogen atoms into the amorphous network of carbon. Th e plasma chemistry of the system was also analyzed by OES to investigate th e active chemical species that were involved in the formation of carbon nit ride. The result indicated that the addition of excess argon (four times mo re than nitrogen) can effectively enrich the excited-state CN radicals whic h subsequently promotes the concentration of nitrogen in the amorphous carb on nitride film. This observation is likely due to the lower ionization ene rgy of argon (15.8 eV), argon's larger cross-section area for collision and its massive weight in comparison with the indispensable hydrogen gas as em ployed in the synthesis of other related materials. (C) 1999 Elsevier Scien ce S.A. All rights reserved.