Mechanical characterization of CMOS metal layers

This paper reports on the strain rate dependence of the mechanical properties of aluminum-based metallization layers. Evaporated Al, sputtered Al
_99%
Cu
_1%
, and multilayers of mum-thick Al
_99%
Cu
_1%
films separated by thinner TiN/Ti layers are characterized using the bulge test, the microcompression method and the microtensile technique. Elastic, ductile and fracture parameters are extracted for strain rates depsiv/dt between 10
^-4
to 10
¹
s
^-1
. The Young's modulus E of sputtered layers, 59 GPa, is marginally lower than that of evaporated films, 63 GPa. Both fracture strain epsiv
_max
and strength sigma
_max
of sputtered Al, 5.5% and 79 MPa, respectively, show no significant variation with de/dt, changing to epsiv
_max
= 2.1 % and sigma
_max
= 200 MPa when such films are stacked with TiN/Ti layers. Regarding evaporated Al, the failure parameters depend strongly on the strain rate: emax decreases from 33.2 to 1.3% and sigma
_max
increases from 153 to 380 MPa within the entire range of tested depsiv/dt values.