Lead-free interconnection between structures and lead-free die attachment are growing trends, particularly in the semiconductor industry. Part of this trend is driven by concern over the use of lead, with some governing bodies scheduled to ban the use of lead in the semiconductor industry. Soldered interconnections containing lead are commonly used for highly conductive interconnects.
Thus, a highly conductive lead-free interconnection that may replace a soldered interconnection would be desirable. Some options for achieving a conductive lead-free interconnection have included sintering or diffusion soldering. In both of these cases, there are a number of important boundary process conditions that require consideration.
For example, neither the pressure used for the sintering or diffusion bonding, nor the temperature for the sintering or diffusion bonding may be too high in order to prevent damage to semiconductor structures, as well as being able to be achieved by existing equipment. In addition, prior to the final fixation of a die, it must be placed in position with high precision and remain in that position during subsequent handling steps. These boundary conditions may place requirements that may not be optimal for the processes of sintering or diffusion soldering, or may not be suitable for carrying out the processes with conventional interconnection and die attach equipment. It would be desirable that a final interconnection be achieved at relatively low temperatures and that there is no excess support material in or around an interconnect.