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Received Mar 15, 2017; Accepted May 8, 2017
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1. Introduction
Nanoscale manipulations inside scanning electron microscope (SEM) have found many uses in various fields [1]. Examples include nanomaterial characterizations [2–9], nanoelectronic probing [10–12], nanodevices prototyping [13], photonics [14, 15], and biological researches [16–18]. The most common setup involves installing piezo-based manipulator into an SEM. A joystick is used to control the motion of the manipulator, and the SEM provides the real-time image feedback. This combination provides an intuitive hand-eye coordinated method to interact with objectives and in micrometer and nanometer scale.
Several SEM based nanomanipulation systems have been reported in the literature [19–23]. There are also commercially available systems from Kleindiek, DCG Systems (Previously Zyvex), SmarAct, Klocke, and Attocube. The majority of these systems do not have position sensor integrated, thus repeatable motions cannot be made, and the manipulation efficiency relies heavily on the skill of the human operator. Other systems contain optical encoders for position feedback, but the heat generated by the laser diode is difficult to dissipate inside vacuum, leading to high position drift rate. The use of mechanical sliding rails for guiding the piezo stick-slip motion is not repeatable due to frictions in the interfaces and the deformation in the mechanical rails. The stick-slip motion also creates mechanical vibration while in motion, which can cause end-effector (the device at the end of a robotic arm, such as claws and needles) or sample damage.
We have previously reported a new load-lock compatible nanomanipulation system that tackles limitations with existing nanomanipulation systems. The system utilizes unique in-vacuum, low-power electronics for sensing strain gauge deformation, and flexure based positioner design. The system is capable of producing nanometer resolution closed-loop positioning, subnanometer per minute drift, and friction free, vibration free motion inside SEM. The compact system can be mounted onto most SEM using the standard SEM sample holder, thus allowing the system to be added or removed from an SEM within seconds.
In the applications, the manipulations can be guided by SEM’s real-time vision and handled by operators, or computer generating the motion targets according to...