Nitrogen Content Limitation Due to Chemical Sputtering in Dual Ion Beam Deposited Carbon Nitride films

Carbon nitride films were synthesized in a dual ion beam deposition facility by bombarding a growing carbon film with a focused nitrogen ion beam of energies between 150-600 eV. Thereby a central zone of the film is exposed to highest and outer zones to progressively decreasing ion intensity. This feature allowed us to correlate - in a wide range and with one film - the ratio i/a of bombarding nitrogen ions to depositing carbon atoms with film properties such as nitrogen content, infrared absorption, hardness and film thickness. No film growth was observed in zones of i/a>1 indipendent of the nitrogen ion energy due to mainly chemical sputtering by which volatile CN based compounds are formed. These were evidenced by highly sensitive quadrupole mass analysis. Chemical sputtering effects also a limitation of the nitrogen content (N)/(C). Highest (N)/(C) values of 40% as determined by Auger analysis and highest hardness values of 30 Gpa as determined by nanoindentetion were found just at the edge of beginning of film growth at i/a~1. Neither by ESCA nor by IR analysis C3N4 type similar film structures as predicted by Liu and Cohen were found.

HAMMER Peter;  HAUPT Justus;  GISSLER Wolfram; 

1996-05-15

JRC13106