Post-CMOS microelectrode fabrication and packaging for on-CMOS electrochemical biosensor array

Miniaturized biosensor arrays are attractive for parallel analysis of multiple parameters and targets. Without the need for bulky bench-top instruments the miniaturized sensor arrays enable many applications such as DNA testing, drug screening, antibody and protein analysis and biosensing. With the advance of CMOS technology and microfabrication it becomes possible to integrate and miniaturize the sensors and CMOS electronics on a single chip. The integration work involves multidisciplinary knowledge including CMOS design, biosensing and biointerface, post-CMOS microfabrication and packaging. In this thesis, it seeks to overcome the challenges in the post-CMOS fabrication and packaging to interface with the CMOS electronics. Specifically, for the first time, CMOS-compatible die-level photolithography was characterized and developed besides wafer-level photolithography. The photolithographic photoresist spin coating was carried on 1.5x1.5mm2 and 3x3mm 2 silicon substrates and characterized. Then, the result was later applied to the fabrication of on-CMOS microelectrode array. After that, to enable on-CMOS biosensor measurement, the CMOS die with on-CMOS microelectrode array was wire-bonded into ceramic package and properly insulated by parylene. A novel masking method was developed to selectively etch away parylene to expose on-CMOS electrode to form biointerface. The cytochrome C biointerface was formed and characterized on CMOS to verify the functionality of the packaging and electronics. The instrumentation and post-CMOS fabrication processes reported here are suitable for forming single-chip electrochemical analysis microsystems with a wide range of biological and chemical sensor interfaces.