Abstract
In this experiment, Cu wire bonding takes place over a variety of probe marks on integrated circuit bond pads of 0.8µm and 3µm aluminum (Al) thicknesses. Probe marks were created by cantilever probe tips, typical of probes in manufacturing for bond pads of 75µm width or greater. Three probe cards were built to simulate different contact forces on the pads. Integrated circuit test wafers were probed using each probe card, one half wafer with smooth tips, and the other half wafer with roughened tips. This resulted in a variety of probe mark topographies to use in experimentation. Wire bonding over probe marks was done with 25µm bare copper (Cu) wire with a single bond recipe typical of manufacturing for 3µm pad Al. Data analysis was approached using design of experiment (DOE) factorial methods, bond shear force being the output of interest. Bond shear force values are affected by Al thickness, shear test direction relative to ultrasonic generator (USG) vibration direction, and also probe mark characteristics for Cu bonds on thick pad Al.
Published Version
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