A CMOS-Compatible AFM Tip Fabrication Process and Integrated AFM Cantilevers Fabricated with this Process

Mizuki Ono*, Dirk Lange, Oliver Brand, Christoph Hagleitner, and Henry Baltes

Physical Electronics Laboratory, ETH Zuich, Hoeggerberg, HPT-H6, CH-8093 Zuich, Switzerland
*on leave from Advanced LSI Technology Laboratory, TOSHIBA Corporation, Corporate Research and Development Center, 8, Shin-Sugita-cho, Isogo-ku, Yokohama, 235-8522 Japan

A CMOS-compatible process for the fabrication of AFM cantilevers with integrated tips has been developed. For the first time, the tips are fabricated after the completion of the regular CMOS process sequence. On-chip circuit components, such as piezoresistive deflection sensors, deflection actuators, and amplifiers, are fabricated on the mirror-polished surface of the wafer, ensuring optimal performance. The tip fabrication process is based on anisotropic silicon etching at low temperature using a TMAH solution. The anisotropic etching process has been optimized to ensure process controllability. Using the described process, CMOS-based cantilevers with piezoresistive deflection sensors and integrated tips have been successfully fabricated. Force-distance curves and scanning images in constant-force mode have been recorded. With the same technology, more complex micro systems for surface analysis, including force sensor arrays with integrated deflection sensors, actuators, and tips, as well as on-chip circuit components, can be fabricated.