CMOS-Embedded 3D Micro/Nanofluidics Employing Top-Down Beol Single-Step Wet-Etching Technique

This paper presents CMOS-embedded 3D micro/ nanofluidics for next generation point-of-care (POC) diagnostic devices. We take advantage of the fine line metallization in modern CMOS technology and create 3D micro/nanofluidics through the removal of the metals from the routings using a single-step post-CMOS wet-etching process. We demonstrate the method in both 180-nm and 65-nm CMOS chips with aluminum and copper back-end-of-line (BEOL), respectively. Various fluidic geometries are investigated including (1) a four-channel fluidic splitter; (2) a 3D fluidic channel; and (3) a width-varying channel for resistive pulse sensing (RPS). We also study the impact of etchants on the transistor characteristics and demonstrate functional circuit operation using a 32-bit shift register after prolong etching. Last, we demonstrate resistive pulse sensing in our CMOS-embedded microfluidics. This work presents the first demonstration of CMOS-embedded micro/nanofluidics for biomedical applications.