Integration of CMOS Image Sensor and Microwell Array Using 3-D WLCSP Technology for Biodetector Application

Integration of microfluidics with integrated circuit chip is a promising method to achieve lab-on-a-chip for its high-level miniaturization and portability in application. In this paper, a novel approach for integration of complementary metal- oxide-semiconductor image sensor and microwell array using the 3-D wafer-level chip scale package (3-D WLCSP) technology for biodetector is presented. The key process including silicon microwell array fabricating, wafer-level bonding, backside grinding, through-silicon via etching, redistribution layer, and ball grid array formation are developed. A high-density serpentine electrical circuit is integrated on the backside of the package to work as a temperature controller. After the fabrication process optimization, a yield rate of 94.6% is obtained. The reliability of the packages is characterized by thermal cycling and highly accelerated stress test temperature storage tests, and the results show a good package level reliability. The proposed 3-D WLCSP provides a low-cost and reliable solution for the fluidic biodetector integration.