Why do we care so much about target bonding? This is important because a sputtering target that truly performs will allow greater process flexibility, and higher throughput. An introduction from Eliminating Bond Stresses of Sputtering Targets at Operating Temperatures:
“…It was observed that bonding with reactive multi-layer foil as a localized heat source allows use of higher temperature solders for joining target and backing plates for sputtering. This permits the use of higher power densities and higher operational temperatures, since the bond is generally the first part of the target assembly to fail at higher temperatures.
After learning that a condition of low stress can be set at ambient temperatures, it is a logical next step to explore setting a low stress point at other temperatures. If the theory is true, that a zero stress point could be set at operational temperature, then a sputtering target would be able to operate with no stress imparted by thermal expansion. This would allow higher sputtering power densities, which would result in an increase of throughput.”