Design Considerations of CMOS Micro-heaters to Directly Synthesize Carbon Nanotubes for Gas Sensing Applications

Compact and low cost gas sensors can be produced by growing Carbon Nanotubes (CNTs) as sensing material on a CMOS chip. Direct CNT synthesis on CMOS is possible by local resistive heating on suitable CMOS conductive layers. However, this synthesis process using thermal chemical vapor deposition requires near 900 degrees C temperature, which can compromise the functionalities of CMOS circuits. Therefore, CMOS micro heaters have been modelled and simulated to investigate the achievability of the designs on actual chips. This paper will present the design considerations of the simulated CMOS micro heaters, demonstrating how global heating of the microsystem can be avoided and mechanical integrity of the micro-heaters maintained. The required CMOS post-processing is outlined.