A low-temperature fabrication process integrated carbon nanotubes-based sensor device into CMOS IC

This paper presents a low temperature fabrication method of carbon nanotubes(CNTs)-based sensors device on a CMOS integrated circuit chip made by TSMC 0.35 ¿m CMOS process. Low temperature processes are the better ways to integrate carbon nanotubes (CNTs) with CMOS chips into array-type gas sensors. Almost the metal used in CMOS is Al-Si-Cu alloy, which make the sustainable temperature of CMOS structures be in the range of 400-500°C. The silicon oxide substrate of CMOS chip was modified with 3-aminopropyltriethoxysilane (APTS) to form aminoterminated (-NH₂) on the surface of self-assembled monolayer (SAM). The chemical adhesion of CNTs to surface treated is due to the presence of positive charges or amine groups on the surface. After CNTs film was deposited on silicon oxide, we formed interdigitated electrode (IDE) by lift-off process. Furthermore, the area of CNTs-based sensor device was 500 ¿m ×400 ¿m, and the IDE finger width was 10 ¿m and the smallest gap size was 4 ¿m.