handbook of carbon, graphite, diamond and fullerenes

Diamond-Like Carbon 347
The resulting coating can be a-C:H or a soft polymer-like graphite
depending on the applied energy. Deposition rate is 0.5 to 2/jm/hr. Aclean
deposition surface is obtained by chemically etching the substrate followed
by sputter cleaning with argon just prior to the actual deposition.
Since a solid carbon target is not needed and the carbon source is a
gas, greater flexibility is possible in the positioning and geometry of the
substrate(s) as a coating is deposited on every surface exposed to the gas
(as opposed to sputtering which is essentially a line-of-sight process).
Unlike the purely PVD process, large parts can be coated (as long as they
can be electrically contacted) with present production equipment. 11 ^
Deposition by Ion-Beam Activation. A typical ion-beam activated
system has a 30 cm hollow-cathode ion source with its optics masked to 10
cm. Argon is introduced to establish the discharge followed by methane in
a 28/100 ratio of methane molecules to argon atoms. The energy level is
100 eV, the acceleration voltage is 600 V, and the resulting deposition rate
is 0.5/mi/h.
A similar system has a dual ion-beam. A primary beam sputters
carbon while the growing film is being simultaneously bombarded with
argon ions generated from a second ion source J 18 1 Another system is based
on a microwave discharge generated by electron cyclotron resonance
(ECR)J 19 H 20 ) The principle of ECR is described in Ch. 13, Sec. 3.3.
3.4 Substrate Heating
Under normal circumstances during deposition by high-frequency
discharge, the substrate remains at low temperature (