2 D nano-positioning system with a sub-nanometric repeatability over millimetre displacement range (original) (raw)
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Measurement Science and Technology, 2007
We propose a 2D displacement control system with sub-nanometric repeatability on position over the millimetre travel range on both axes. It could be useful for nanofabrication processes or other applications related to the nanotechnology community. In our case, the apparatus is planned to be used in atomic force microscopes and lithography systems as a sample-holding device. The method is based on a heterodyne interferometric sensor and a home-made high frequency phase-shifting electronic board. This paper presents the complete mechanical system and gives experimental results showing a repeatability of 0.5 nm over a moving range of 5 mm.
Heterodyne interferometric technique for displacement control at the nanometric scale
Review of Scientific Instruments, 2003
We propose a method of displacement control that addresses the measurement requirements of the nanotechnology community and provide a traceability to the definition of the mèter at the nanometric scale. The method is based on the use of both a heterodyne Michelson's interferometer and a homemade high frequency electronic circuit. The system so established allows us to control the displacement of a translation stage with a known step of 4.945 nm. Intrinsic relative uncertainty on the step value is 1.6ϫ10 Ϫ9. Controls of the period of repetition of these steps with a high-stability quartz oscillator permits to impose an uniform speed to the translation stage with the same accuracy. This property will be used for the watt balance project of the Bureau National de Métrologie of France.
A serial-kinematic nanopositioner for high-speed atomic force microscopy
Review of Scientific Instruments, 2014
A flexure-guided serial-kinematic XYZ nanopositioner for high-speed Atomic Force Microscopy is presented in this paper. Two aspects influencing the performance of serial-kinematic nanopositioners are studied in this work. First, mass reduction by using tapered flexures is proposed to increased the natural frequency of the nanopositioner. 25% increase in the natural frequency is achieved due to reduced mass with tapered flexures. Second, a study of possible sensor positioning in a serial-kinematic nanopositioner is presented. An arrangement of sensors for exact estimation of cross-coupling is incorporated in the proposed design. A feedforward control strategy based on phaser approach is presented to mitigate the dynamics and nonlinearity in the system. Limitations in design approach and control strategy are discussed in the Conclusion.
MEMS Nanopositioner for On-Chip Atomic Force Microscopy: A Serial Kinematic Design
Journal of Microelectromechanical Systems, 2015
The design and characterization of a twodegree-of-freedom serial kinematic microelectromechanical systems (MEMS) nanopositioner for on-chip atomic force microscopy (AFM) is reported. A novel design is introduced to achieve a serial kinematic mechanism based on a standard siliconon-insulator MEMS fabrication process. The nanopositioner comprises a slow axis with a resonance frequency of 2.4 kHz and a fast axis with a resonance frequency of above 4.4 kHz, making it ideal for rastering, as required in the AFM. Strokes of 14 and 9 µm are experimentally achieved for the fast and slow axes, respectively. The serial kinematic design of the stage enables the cross-coupling between the two axes of motion to be as low as −60 dB. Electrothermal displacement sensors are incorporated in the device, which may be used to enable feedback control as required in high-speed AFM.
2013
As a result of the progress in the multidisciplinary nanotechnology field the demand for precision positioning systems has sensibly increased in the last years. In this line, a novel two-dimensional moving nano-platform (NanoPla) is being designed. The set requirements of the initial prototype are not only high positioning accuracy and resolution but also long working range (50x50 mm), increasing the number of potential applications. The presented paper demonstrates an illustrative part of the complete state-of-art realized, justifying and concluding with an optimal positioning system. Different long range stages have been considered and classified depending on their structure, motion system and relative motion between sample and probe. The final result is the definition of a three-layer and two-stage architecture to characterize surface topography of larger areas with an integrated Atomic Force Microscopy (AFM) system. In order to meet the requirements (nanometer resolution and submicrometer accuracy) several different precision engineering principles and finite elements method software have been used.
Dual actuation for high-bandwidth nanopositioning
2008 47th IEEE Conference on Decision and Control, 2008
The imaging speed of atomic force microscopes (AFM) is limited by the bandwidth of the feedback loop to measure the sample topography. In contact mode as well as tapping mode operation, this feedback loop is crucial to control and minimize the force between the probing tip and the sample, which is done by controlling the vertical tip sample distance via a piezo actuator. For fast imaging, control of the probe-sample distance requires a high closed-loop bandwidth. To achieve this goal without reducing the existing positioning range, a second, high-bandwidth actuator is introduced to an existing AFM setup. A model-based controller is designed and implemented to improve the bandwidth of the primary feedback loop for tapping mode and contact mode imaging. For highest imaging bandwidth in contact mode, an accessory high-performance controller is designed and implemented on the dual actuated AFM system. The improved performance of the new controlsystem is experimentally demonstrated.
A monolithic MEMS position sensor for closed-loop high-speed atomic force microscopy
Nanotechnology, 2016
The accuracy and repeatability of atomic force microscopy (AFM) imaging significantly depend on the accuracy of the piezoactuator. However, nonlinear properties of piezoactuators can distort the image, necessitating sensor-based closed-loop actuators to achieve high accuracy AFM imaging. The advent of high-speed AFM has made the requirements on the position sensors in such a system even more stringent, requiring higher bandwidths and lower sensor mass than traditional sensors can provide. In this paper, we demonstrate a way for high-speed, high-precision closed-loop AFM nanopositioning using a novel, miniaturized MEMS position sensor in conjunction with a simple PID controller. The sensor was developed to respond to the need for small, lightweight, high-bandwidth, long-range and subnm-resolution position measurements in high-speed AFM applications. We demonstrate the use of this sensor for closed-loop operation of conventional as well as high-speed AFM operation to provide distortion-free images. The presented implementation of this closed-loop approach allows for positioning precision down to 2.1 Å, reduces the integral nonlinearity to below 0.2%, and allows for accurate closed loop imaging at line rates up to 300 Hz.
On dual actuation in atomic force microscopes
… Control Conference, 2004 …, 2004
In this paper, the problem of dual actuation in the atomic force microscope (AFM) is analyzed. The use of two actuators to balance the trade-off between bandwidth, range, and precision has been recently extended to nano-positioning systems. Despite existing demands, this concept undergoes fundamental limitations towards its extension to AFMs. This is attributed to the non-conventional requirement imposed on the control signal response, as it used to create the image of the characterized surface.
Design and characterisation of a serial-kinematic nanopositioner for high-speed AFM
2014 IEEE/ASME International Conference on Advanced Intelligent Mechatronics, 2014
A flexure-guided serial-kinematic XYZ nanopositioner for high-speed Atomic Force Microscopy (AFM) is presented in this paper. Two aspects influencing the performance of serial-kinematic nanopositioners are studied in this work. First, mass reduction by use of tapered flexures is used to enhance the natural frequency of the nanopositioner. Second, a study of possible sensor positioning in a serial-kinematic nanopositioner is presented. An arrangement of sensors for exact estimation of cross-coupling is incorporated in the proposed design. Characterization in terms of range, hysteresis, cross-coupling and dynamic response of the nanopositioner is presented. Scanning results up to 640 Hz are also furnished. Outcomes and future work are discussed in conclusion.
An optimized nano-positioning stage for Bristol’s Transverse Dynamic Force Microscope
IFAC-PapersOnLine, 2016
This paper presents the design process for the optimisation of a nano-precision actuation stage for a Transverse Dynamic Force Microscope (TDFM). A TDFM is an advanced type of Atomic Force microscope (AFM) that does not contact the specimen and therefore has potential for increased accuracy and decreased damage to the specimen. The nano-precision stage actuates in a horizontal plane within a region of 1m1m and with a resolution of 0.3 nm. The non-contact TDFM has been developed at Bristol University for the precise topographical mapping of biological and non-biological specimens in ambient conditions. The design objective was to maximise positional accuracy during high speed actuation. This is achieved by minimising vibrations and distortion of the stage during actuation. Optimal performance was achieved through maximising out-of-plane stiffness through shape and material selection, as well optimisation of the anchoring system. The design was subject to constraints including an in-plane stiffness constraint, space constraints and design features relating to the laser interferometry position sensing system and subsequent controller design.