CMOS monolithic mechatronic microsystem for surface imaging and force response studies

Abstract

We report on a standalone single-chip (7 mm /spl times/10mm) atomic force microscopy (AFM) unit including a fully integrated array of cantilevers, each of which has individual actuation, detection, and control units so that standard AFM operations can be performed only by means of the chip without any external controller. The system offers drastically reduced overall size and costs and can be fabricated in standard CMOS technology with some post-CMOS micromachining steps to form the cantilevers. Full integration of microelectronic and micromechanical components on the same chip allows for controlling and monitoring all system functions. The on-chip circuitry notably improves the overall system performance. Circuitry includes analog signal amplification and filtering stages with offset compensation, analog-to-digital converters, digital proportional-integral-derivative (PID) deflection controllers, sensor-actuator compensation (SAC) filters, and an on-chip digital interface for data transmission. The microsystem characterization evidenced a vertical resolution of better than 1 nm and a force resolution of better than 1 nN as shown in the measurement results. This CMOS monolithic AFM microsystem allows for precise and fully controlled mechanical manipulation in the nanoworld.