BONDABILITY ANALYSIS OF BOND PADS BY THERMOELECTRIC TEMPERATURE-MEASUREMENTS

To reduce cost and enhance reliability for microelectronics applicatio ns, a complete understanding of the thermosonic bonding process is req uired. In particular, the question of whether melting, diffusion, or s ignificant heating occurs along the interface during friction has ofte n been raised. We present results obtained with a new device based on thermoelectric temperature measurements to determine the temperature a t the bond interface. In addition to the temperature information, the data characterizes the bonding process in real time on a micrometer sc ale. The basic principle of the developed apparatus is temperature mea surement by an Au-Ni thermocouple fixed within the inside chamfer of a bonding capillary. Different bond substrates with high and low bond c ontact quality have been investigated. The thermoelectric temperature measurements very precisely determines the bonding behavior of the bon d pads. A few nanometers surface contamination on a bond pad significa ntly reduces the temperature rise at the bond interface and therefore impairs bondability of the substrate. These results demonstrate the se nsitivity and accuracy of the measurement principle. The apparatus is a powerful tool to measure the tribology of the bond system and to cha racterize the bondability of different bond pads.