A. Scorzoni et al., NONLINEAR RESISTANCE BEHAVIOR IN THE EARLY STAGES AND AFTER ELECTROMIGRATION IN AL-SI LINES, Journal of applied physics, 80(1), 1996, pp. 143-150
A common result obtained in electromigration experiments carried out o
n Al-Si lines using different high resolution resistometric methods, i
s a monotonous non-linear resistance increase at the very beginning of
the high current electromigration test, and a decrease after the high
stressing current is switched off. These effects have often been attr
ibuted to the attainment of a steady state of vacancy concentration du
ring and after electromigration. This paper shows how even small abrup
t temperature steps, always present at the beginning and after electro
migration tests, are the triggering events for different, often revers
ible, physical phenomena contributing to non-linear resistance changes
. Precipitation-dissolution of alloyed elements appears to be the most
significant one. Abrupt temperature changes also induce a change of t
he hydrostatic stress of passivated lines. The relaxation of the hydro
static stress could be coupled with a void volume change, and the tota
l resistance is a function of both the hydrostatic stress (through res
istivity) and of void volume. However, we demonstrate that in our expe
riments the effect of hydrostatic stress relaxation on resistance vari
ations is negligible with respect to the action of precipitation-disso
lution. These non-linear, thermally induced effects, however, do not e
xclude possible simultaneous resistance changes due to the accumulatio
n/relaxation of the electromigration damage. Experimental results are
collected by means of different, complementary techniques. (C) 1996 Am
erican Institute of Physics.