Heterogeneous Integration of CMOS Sensors and Fluidic Networks Using Wafer-Level Molding

Direct sensing in liquids using CMOS-integrated optical and electrical sensors is attractive for lab-on-chip applications, where close physical proximity between sample and sensor can obviate optical lenses, enhance electrical sensitivity, and decrease noise due to parasitics. However, controlled delivery of fluid samples to the chip surface presents an ongoing challenge for lab-on-CMOS development, where traditional wire-bond packaging prevents integration of planar microfluidics. In this paper, we present a method for scalable heterogeneous integration of microfluidic channels and silicon-integrated circuit substrates using a commercial fan-out wafer-level packaging approach. The planar surface supports multiple approaches for fluidic integration; we present both a stacked laser-cut fluidic assembly and the fabrication of monolithic SU-8 microchannels over the IC surface. As a proof-of-principle, both electrical and fluidic routing are provided to a custom 0.18-μm CMOS optical sensor IC, and optical transmission and fluorescence measurement experiments are demonstrated.