Testing, repairing and packaging technology for the CMOS-MEMS integrated tactile sensor

The CMOS-MEMS integrated tactile sensor enables the robot to have dense and large area tactile sensor on the whole body. The ASIC (Application Specific Integrated Circuit) with the CMOS technology provides the communication function for the bus connected tactile sensor. The size of integrated chips is reduced by wafer-level-packaging (WLP) technology down to mm-scale size. Because the yield of the fabrication process of the tactile sensor will be a critical issue for this sensor network system, the testing and repairing procedure should be developed at the experimental phase, as well as designing the wafer-level fabrication process. The testing and repairing process in the middle of the fabrication provides a quick feedback to the yield optimization. In this paper, a novel process flow for testing and repairing in the process of the fabrication was developed. The test environments were prepared at each checkpoint of the fabrication process, and repairing process with Focused Ion Beam (FIB) was also applied to modify and repair the device. Finally, completed tactile sensors are fabricated with about 40% yield, and mounted on the flexible cable by the developed low-temperature flip chip bonding technology.