EFFECTS OF HIGH-FLUX LOW-ENERGY (20-100 EV) ION IRRADIATION DURING DEPOSITION ON THE MICROSTRUCTURE AND PREFERRED ORIENTATION OF TI0.5AL0.5N ALLOYS GROWN BY ULTRA-HIGH-VACUUM REACTIVE MAGNETRON SPUTTERING
F. Adibi et al., EFFECTS OF HIGH-FLUX LOW-ENERGY (20-100 EV) ION IRRADIATION DURING DEPOSITION ON THE MICROSTRUCTURE AND PREFERRED ORIENTATION OF TI0.5AL0.5N ALLOYS GROWN BY ULTRA-HIGH-VACUUM REACTIVE MAGNETRON SPUTTERING, Journal of applied physics, 73(12), 1993, pp. 8580-8589
The effects of incident ion/metal flux ratio J(i)/J(Me) and ion energy
E(i) on the microstructure, texture, and phase composition of polycry
stalline metastable Ti0.5Al0.5N films produced by reactive magnetron s
puttering have been investigated using x-ray diffraction (XRD), plan-v
iew and cross-sectional transmission electron microscopy, and Rutherfo
rd backscattering spectroscopy. The films, typically congruent-to 1 mu
m thick, were deposited at a pressure of 20 mTorr (2.67 Pa) in pure N2
on thermally oxidized Si(001) substrates at 250+/-25-degrees-C. The N
2+ ion flux to the substrate was controlled by means of a variable axi
al magnetic field superimposed on the permanent magnetic field of the
magnetron. Films deposited at E(i)=20 eV (congruent-to 10 eV per incid
ent accelerated N) with J(i)/J(Me)=1 exhibited a complete (111) textur
e with a porous columnar microstructure and an average column size of
congruent-to 30 nm. Increasing E(i) from 20 to 85 eV, while maintainin
g J(i)/J(Me) constant at 1, resulted in a small change in texture as t
he XRD intensity ratio I002/(I111 + I002) increased from congruent-to
0 to 0.14, a decrease in average column size to 25 nm, and a reduction
in intracolumn porosity. The stoichiometric ratio N/(Ti+Al) increased
from 1 at E(i)=20 eV with J(i)/J(Me)=1 to 1.23 at E(i)=85 eV indicati
ng trapping of excess N while the lattice constant a0 increased from 0
.4157 to 0.4188 nm due to compressive stress. E(i) values greater-than
-or-equal-to 100 eV led to alloy phase separation. In contrast, mainta
ining E(i) at congruent-to 20 eV and increasing J(i)/J(Me), from 1 to
greater-than-or-equal-to 5.2 resulted in a change from a porous (111)
texture to a dense completely (002)-oriented microstructure with an in
crease in the average column size to 35 nm. N/(Ti+Al) and a0 remained
essentially constant and the alloy remained single phase. Mechanistic
pathways leading to microstructure and texture changes through variati
ons in E(i) at constant J(i)/J(Me) and in J(i)/J(Me) at constant E(i)
were found to be quite different. The average energy deposited per met
al atom, [E(d)]=E(i)(J(i)/J(Me)), is therefore not a universal paramet
er, as has been previously proposed, for describing film growth.