A fabrication process with high thermal isolation and vacuum sealed lead transfer for gas reactors and sampling microsystems

This paper describes a six-mask fabrication process for vacuum-scaled microsystems including pressure and flow sensors, reaction chambers and reservoirs, and channels ranging from 100 nm to 10 mum in hydraulic diameter. All structures are countersunk into a glass substrate, resulting in a planar upper surface that eliminates stress concentrations and also facilitates further lithographic processing. The material choices and structural arrangements are designed to provide high thermal isolation (similar to2x10(5) K/W). Lead transfer between the three available levels of interconnect are accomplished with minimal parasitic capacitance (<1 fF), and low resistance (similar to1 Omega). A variety of test structures have been successfully fabricated.