Metrological large range scanning probe microscope

Abstract

We describe a metrological large range scanning probe microscope (LR-SPM) with an Abbe error free design and direct interferometric position measurement capability, aimed at versatile traceable topographic measurements that require nanometer accuracy. A dual-stage positioning system was designed to achieve both a large measurement range and a high measurement speed. This dual-stage system consists of a commercially available stage, referred to as nanomeasuring machine (NMM), with a motion range of 25 mm×25 mm×5 mm along x, y, and z axes, and a compact z-axis piezoelectric positioning stage (compact z stage) with an extension range of 2 μm. The metrological LR-SPM described here senses the surface using a stationary fixed scanning force microscope (SFM) head working in contact mode. During operation, lateral scanning of the sample is performed solely by the NMM. Whereas the z motion, controlled by the SFM signal, is carried out by a combination of the NMM and the compact z stage. In this case the compact z stage, with its high mechanical resonance frequency (greater than 20 kHz), is responsible for the rapid motion while the NMM simultaneously makes slower movements over a larger motion range. To reduce the Abbe offset to a minimum the SFM tip is located at the intersection of three interferometer measurement beams orientated in x, y, and z directions. To improve real time performance two high-end digital signal processing (DSP) systems are used for NMM positioning and SFM servocontrol. Comprehensive DSP firmware and Windows XP-based software are implemented, providing a flexible and user-friendly interface. The instrument is able to perform large area imaging or profile scanning directly without stitching small scanned images. Several measurements on different samples such as flatness standards, nanostep height standards, roughness standards as well as sharp nanoedge samples and 1D gratings demonstrate the outstanding metrological capabilities of the instrument.

Metrological atomic force microscope using a large range scanning dual stage

“…9,11 In this article, we present the design and implementation of MAFM using a large range scanning dual stage. The uncertainty budget in displacement measurement was estimated through the performance evaluation of the dual stage.…”

“…[3][4][5][6][7][8] But, the measurement range of MAFM is usually limited less than 100 µm, and so the scanning range should be expanded to satisfy metrological requirements in various application fields such as micro roughness measurement and nanometrology on wafer surface. 9 However, the expansion of scanning range of AFM is still challenging issue since PZT actuators and flexure hinge guides, which are usually used in nanoscanners, have a limitation in moving range. Compact displacement sensor such as capacitive sensors and strain gauges can not be applied due to their short measurement range and this increases the complexity of implementation still more.…”

Large area high-speed metrology SPM system

“…On particular, well defined samples (e.g. calibration gratings) this approach can even be simplified using several very long profiles [11]. However, this approach cannot be used generally for unknown samples.…”

Investigation of Short-term Amplitude and Frequency Fluctuations of Lasers for Interferometry

“…It is able to cover measurement ranges from kilometers in long-distance interferometers to subnanometer distances in the most precise laboratory machines like interferometric comparators, nanometrology systems and metrological CMMs (coordinate measurement machines [1][2][3][4][5][6][7][8]). In case of fundamental metrology laboratory devices it is also crucial that the laser as a source for powering the interferometer directly fulfills the demand for traceability to the primary standard of length -it follows one of the recommendations for realization of the meter standard [9].…”