Nanowire field-effect transistors (nano-FETs) are nano devices capable of highly sensitive, label-free sensing of molecules. However, significant variations in sensitivity across devices can result from poor control over device parameters, such as nanowire diameter and the number of electrode-bridging nanowires. This paper presents a fabrication approach that uses wafer-scale nanowire contact printing for throughput and uses automated nanomanipulation for precision control of nanowire number and diameter. The process requires only one photolithography mask. Using nanowire contact printing and post processing (i.e., nanomanipulation inside scanning electron microscope), we are able to produce devices all with a single nanowire and similar diameters at a speed of ∼1 min/device with a success rate of 95% (n=500). This technology represents a seamless integration of wafer-scale microfabrication and automated nanorobotic manipulation for producing nano-FET sensors with consistent response across devices.

This paper presents a nanomanipulation system for operation inside scanning electron microscopes (SEM). The system is small in size, capable of being mounted onto and demounted from an SEM through the specimen exchange chamber without breaking the high vacuum of the SEM. This advance eliminates frequent opening of the high-vacuum chamber, thus, incurs less contamination to the SEM, avoids lengthy pumping, and significantly eases the exchange of end-effectors (e.g., nano probes and grippers). The system consists of two independent 3-DOF Cartesian nanomanipulators based on piezo motors and piezo actuators. High-resolution optical encoders are integrated into the nanomanipulators to provide position feedback for closed-loop control. A look-then-move control system and a contact detection algorithm are implemented for horizontal and vertical nanopositioning. The system design, system characterization details, and system performance are described.