Die-level photolithography and etchless parylene packaging processes for on-CMOS electrochemical biosensors

Integrated sensor arrays on CMOS instrumentation chips are attractive to many biological and biomedical sensor applications. However, the packaging of CMOS circuitry for use within a liquid environment remains as an open challenge. Reliable post-CMOS electrode fabrication and packaging processes that are critical to the development of integrated electrochemical biosensors are presented in this paper. A die-level photolithography process was developed that provides uniform coverage for accurate patterning over 87% of a 3×3mm² silicon substrate. In addition, a new process has been developed to package post-CMOS fabricated electrode arrays. This etchless parylene packaging reduces processing time and improves fabrication yield. These techniques enable realization of on-CMOS biosensors operating in liquids.