Jg. Hong et G. Turban, Etching process of hydrogenated amorphous carbon (a-C : H) thin films in adual ECR-r.f. nitrogen plasma, DIAM RELAT, 8(2-5), 1999, pp. 572-576
Hydrogenated amorphous carbon (a-C:H) films deposited from CH4, in a dual e
lectron cyclotron resonance (ECR)-r.f. plasma were treated in N-2 plasma at
different r.f. substrate bias voltages after deposition. The etching proce
ss of a-C:H films in N-2 plasma was observed by in situ kinetic ellipsometr
y, mass spectrometry (MS), and optical emission spectroscopy (OES). Ex situ
atomic force microscopy (AFM) and X-ray photoelectron spectroscopy ( XPS)
were used to characterize the etched film surface. XPS analysis proves that
the nitrogen treatment on the a-C:H film, induced by r.f. substrate bias,
causes a direct nitrogen incorporation in the film surface up to 15-17 at.%
to a depth of about 20-40 A depending on the r.f. bias. Various bonding st
ates between carbon and nitrogen, such as tetrahedral sp(3) C-N, and trigon
al sp(2) C-N were confirmed by the deconvolution analysis of C 1s and N 1s
core level spectra. The evolution of etching rate and the surface roughness
in the film measured by AFM exhibit a clear dependence on the applied r.f.
bias. MS and OES show the various neutral species in the N-2 plasma such a
s HCN, CN, and C2N2, which may be considered as the chemical etching produc
ts during the N-2 plasma treatment of a-C:H film. (C) 1999 Elsevier Science
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