sputtering performance due to smaller grain size targets
Vibration Casting of AuSn and AuGe Sputtering Targets
of fine grain size in PVD sputtering targets has been shown to improve
the processing performance of the target in the sputtering chamber. Fine
grain size is most commonly developed in a metal through the
introduction of mechanical work and the addition of heat to allow
recrystallization of the metal into small grains. Some alloys, due to
their brittle, nature are not able to be processed by traditional metal
working techniques without experiencing cracking and material failure.
approach to obtaining fine grain size in PVD sputtering targets for
brittle materials has been developed. Gold-Tin (AuSn) and Gold-Germanium
(AuGe) are two brittle alloys formed into targets used to deposit the
solder layer on the device surface. Neither of these two alloys tolerate
appreciable mechanical work. AuSn and AuGe are produced at near-eutectic
composition, leading to the formation of a heterogeneous microstructure.
cast targets exhibit a large varying grain size and a large eutectic
structure that is detrimental to the performance of the target. A method
to introduce vibration energy during casting was developed to address
this problem. The energy of vibration is introduced into the molten
metal leading to small grains being formed. The size of the grains
formed is a function of both frequency and amplitude.
AuSn Regular Cast - 50X
AuSn Vibration Cast - 50X
manufacturing process develops targets that have a smaller grain size
and more uniformly distribute the heterogeneous structure throughout the
target. The vibrational casting process decreases the grain size from 5
mm to 0.5 mm and the eutectic structure by an order of magnitude. The
smaller grain size targets produced by vibrational casting give improved
performance in the chamber.