Wafer bonding by low-temperature soldering

Recently. wafer level packaging received lots of attention in microsystems because it shows the potential to reduce the packaging cost, while the yiel d of devices after dicing and packaging can be increased. However, there is a limitation of commercialized wafer bonding technology. i.e., the high pr ocess temperature, such as 1000 degrees C of silicon fusion bonding, and 45 0 degrees C of anodic bonding. A novel tow-temperature wafer bonding with p rocess temperature lower than 160 degrees C is proposed, it applies the In- Sn alloy to form the interface of wafer bonding. The experiment results sho w helium leak test of 6 x 10(-9) Torr 1/s, and a tensile strength as high a s 200 kg/cm(2). Reliability test after 1500 temperature cycles between -10 degrees C and 80 degrees C also shows no trace of degradation compared to t he initial quality of the samples. This low-temperature soldering process d emonstrates its promising potential at the wafer level packaging in industr ial production. (C) 2000 Elsevier Science. S.A. All rights reserved.