Wk. Choi et al., X-ray photoelectron spectroscopy studies of modified surfaces of alpha-Al2O3, SiO2, and Si3N4 by low energy reactive ion beam irradiation, J VAC SCI A, 17(6), 1999, pp. 3362-3367
Reactions of N-2(+) ion beams with oxide surfaces of alpha-Al2O3(0001) sing
le crystal and chemical vapor deposition (CVD) SiO2, and reactions of O-2(), ion beams with a nitride surface of Si-rich CVD Si3N4 were investigated
as a function of ion beam energy (200-1000 V) and dose (1X10(15)-1X10(17)/c
m(2)). The thickness modified by the irradiation of a reactive low kinetic
energy ion beam was measured using high resolution cross-sectional images o
f transmission electron microscopy (HR-XTEM). and the formation of new bond
ing induced by chemical reaction was analyzed by x-ray photoelectron spectr
oscopy (XPS). New bonding of Al-O-N on alpha-Al2O3(0001) Started to be obse
rved at 600 V N-2(+) ion energy and a dose of 1X10(16)/cm(2), and Al-N bond
ing could be found at an ion beam energy of 1 keV. The thickness of the alu
minium oxynitride layer after 800 V N-2(+) bombardment has been determined
to be 10-50 Angstrom by HR-XTEM analysis. In the case of CVD SiO2 surface m
odification, new bonding related to nitrogen was not clearly resolved in th
e XPS spectra, irrespective of the change of ion beam energy from 200 to 10
00 V and ion dose from 1X10(15) to 1X10(17)/cm(2). However, widening of the
full width at half maximum of Si 2p core-level XPS spectra for the modifie
d SiO2 surface and the peak position of N Is around 399 eV were evidence of
the existence of nitrogen-related bonding like Si-O-N in the modified CVD
SiO2 surfaces. Moreover, it was very interesting that the Si 2p peak of ele
mental Si appeared in the sample irradiated at a dose of 1X10(17)/cm(2). It
s occurrence was considered to be due mainly to the preferential sputtering
effect, and was found to be largely dependent on the ion beam energy as we
ll ass on the ion dose. In the surface modification of low-pressure CVD Si3
N4 by direct ken O-2(+) ion irradiation, Si-O-N bonding could be successful
ly created at an ion beam energy of 200 V and it evolved significantly at i
on beam energies higher than 500 V. From the above results, low energy reac
tive ion beam irradiation can successfully create new bonding structures on
oxide and nitride surfaces due to a surface chemical reaction like nitrida
tion or oxidation, and is expected to be very useful for the formation of n
ew ultrathin functional layers on ceramic surfaces. (C) 1999 American Vacuu
m Society. [S0734-2101(99)01306-8].