The process of depositing Me/C: H composite films in an argon/n-hexane
gas mixture using a DC unbalanced magnetron was analysed by energy se
lective mass spectrometry and microgravimetric techniques. With only a
rgon as the working gas the ion mass spectra show contributions typica
lly expected from the process gas and sputtered metal. The plasma comp
osition changes with n-hexane admixture, resulting in densely packed i
on mass spectra from CxHY+ fragments and oligomer ions of higher molec
ular mass than the parent molecule. Poisoning of the nickel target is
revealed by the time dependent ion current signals. The ion energy dis
tribution is dominated by two groups of ions: a low energy peak genera
ted by thermalised plasma ions gaining an energy of several eV during
transit across a small plasma sheath in front of the grounded discharg
e anode, and high energy ions produced either by direct ionisation of
high energy neutrals from the sputter process, by elastic collisions w
ith the high energy neutrals, or by backscattering of neutralised prim
ary ions. The collisional processes require ions with a sufficiently h
igh elastic collision cross-section and low dissociation probability.
As a result of the influence of the discharge parameters on the ion en
ergy distribution, the grounded substrate is bombarded mainly by posit
ive CH3+, Ar+ and Ni+ ions with a mean energy of between 2 and 10 eV.
(C) 1998 Published by Elsevier Science Ltd. All rights reserved.