Formation of hydrogenated amorphous carbon films of controlled hardness from a methane plasma
- Center for Advanced Materials, Materials and Chemical Sciences Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (US) Department of Chemistry, University of California at Berkeley, Berkeley, California 94720
Studies of amorphous hydrogenated carbon ({ital a}-C:H) film deposition revealed that methyl radicals are the precursor species responsible for the bulk mass deposition of the films, while the ions act to improve the mechanical properties. The films were deposited on Si(100) substrates both on the powered (negatively self-biased) and on the grounded electrodes from a methane rf plasma (13.56 MHz) at 68 to 70 mTorr and 300 to 370 K. The films produced on the powered electrode exhibited superior mechanical properties, such as high hardness. A mass spectrometer was used to identify neutral species and positive ions incident on the electrodes from the plasma, and also to measure ion energies. Methyl radicals were incident on the electrode surface with an estimated flux of 10{sup 16} cm{sup {minus}2} s{sup {minus}1}, for a rf power of 50 W. Methyl radicals appear to be the dominant intermediates in the growth of the soft carbon polymer, and there is a remarkable decrease in deposition rate due to the introduction of NO, a radical scavenger. A novel pulsed biasing technique was used so that the role of ions in the plasma could be studied separately. It was found that the hardness of the films depends on the power supplied by the ions to the growing film surface (the time averaged difference between the plasma potential and the electrode potential), but not on the energy of individual ions. The pulsed biasing technique offers an efficient method to adjust the film hardness by independent control of the neutral radical and ion fluxes to the surface.
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 6860962
- Journal Information:
- Physical Review, B: Condensed Matter; (USA), Vol. 41:5; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CARBON
DEPOSITION
HYDROGENATION
AMBIENT TEMPERATURE
AMORPHOUS STATE
FILMS
HARDNESS
LOW PRESSURE
SILICON
CHEMICAL REACTIONS
ELEMENTS
MECHANICAL PROPERTIES
NONMETALS
SEMIMETALS
360601* - Other Materials- Preparation & Manufacture
656003 - Condensed Matter Physics- Interactions between Beams & Condensed Matter- (1987-)