Building Solder Bumps on GaAs Flip Chip Schottky Devices
Keywords: under bump metallurgy (UBM), plating, photolithography, solder bumps, high temperature reverse bias (HTRB), and Joint Electron Devices Engineering Council (JEDec)
The semiconductor industry has made astonishing improvements in decreasing circuit dimensions and more importantly, greater performance. Making connections with gold contacts on GaAs devices using solder bumps instead of silver Epoxy offers lower contact resistance and hence, better performance. Further more, solder bump application to GaAs devices is amenable to high volume production and ease of manufacturing. Benefits from using solder bumps then become obvious for connections. This paper describes a process development using our existing technology of wafer processing in both wet and dry chemistries to build solder bumps on GaAs wafer for flip chip Schottky devices. Eutectic Sn/Pb solder bumps and Pb-free solder bumps were investigated. Detailed processing and chemistry will be discussed. Reliability of solder bumps on GaAs flip chip Schottky devices will also be presented.