A review of interferometry for geometric measurement

Traditional MEMS sensing systems do not scale down well to the nanoscale due to resolution and fabrication limitations. Therefore, new sensing systems need to be developed in order to meet the range and resolution requirements of nanoscale mechanical systems. Several nanoscale mechanical sensing systems have emerged that take advantage of nanoscale phenomena to improve the quality of nanoscale sensors. In this paper, we will discuss some of the fundamental limitations in scaling mechanical sensors down to the nanoscale and some of the emerging technologies for nanoscale sensing.

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Scaling electromechanical sensors down to the nanoscale

Large range nanopositioning stage design: A three-layer and two-stage platform

We present an overview of design approaches for nanometrology measuring setups with a focus on interferometry techniques and associated problems. The design and development of a positioning system with interferometric multiaxis monitoring and control is presented. The system is intended to operate as a national nanometrology standard combining local probe microscopy techniques and sample position control with traceability to the primary standard of length.

https://www.degruyter.com/downloadpdf/j/phys.2012.10.issue-1/s11534-011-0093-5/s11534-011-0093-5.xml

Multiaxis interferometric displacement measurement for local probe microscopy

A high-speed metrological large range AFM (Met. LR-AFM) which is capable of fast, accurate, and large range measurements of surfaces and nanostructures is presented. In its design, the z scanner is realized by combining a piezo stage and a large range mechanical stage (referred to as a nanopositioning and nanomeasuring machine, NMM) which move the sample in parallel, thus providing both a high dynamic positioning capability and a large motion range. A contact mode AFM which offers both a short response time and a large sensing range is applied for measuring the surfaces of interest. Sensor signals from the AFM, the piezo stage, and the NMM are combined to derive the surface topography, thus offering high bandwidth for high-speed measurements. To reduce the distortion in the measured profiles, the time delay of the sensors is corrected as well as the displacements of the AFM and the piezo stage being traceably calibrated referring to the z-interferometer of the NMM in situ. Experimental results have demonstrated the high image quality obtainable at a scan speed of 500 μm s−1. The measurement repeatability at different scan speeds ranging from 10 μm s−1 to 1000 μm s−1 reaches nm for step height measurements and × 10−6 for grating pitch measurements, respectively. The study has improved the measurement speed of the Met. LR-AFM by a factor of more than 20, and thus significantly enhanced its measurement throughput and reduced its measurement drift.

https://iopscience.iop.org/article/10.1088/0957-0233/26/9/095402/pdf

High-speed metrological large range AFM

Nanomeasuring and nanopositioning engineering

The paper describes traceable nanometrology based on a nanopositioning machine with integrated nanoprobes. The operation of the high-precision nanomeasuring machine having a resolution of 0,1 nm over the range of 25 mm x 25 mm x 5 mm is explained. Single beam-, double beam- and triple beam interferometer arranged with an Abbe offset-free design are installed into the nanomeasuring machine in order to measure and control the six degrees of freedom. The high performance of the machine is described with a metrological analysis. This analysis shows some today´s limits of nanopositioning and nanomeasuring engineering.

An initial description of the design and operation of compact miniature interferometers that employ fiberoptic lightguides for all of their optical couplings and are suitable for general-purpose use is followed by a metrological analysis of their mode of operation and examples of their broad applicability, based on several typical instrumental setups.

Miniature interferometers for applications in microtechnology and nanotechnology

An interferometer has a diaphragm (11) between an interferometer divider (1) and a beam divider (2), and allows greater angular mobility of a measuring reflector (7) by means of a lens (15, 16) which images the diaphragm, one lens being located in each of the two outlets of the beam divider. A radiation-sensitive face of a photodetector (19,20) is used to detect each of the two diaphragm images (17,18). It can be preferably used for measurement tasks in which changes in the interference structure to be scanned occur during measurement. it allows optically contactless scanning of plane and any type of curved surfaces (7) as well as, for example, use in pressure measuring chambers in which the gas flowing into and out of the chamber causes turbulence in the interference structure.

H.-J. Büchner

Papers

Nanomeasuring and nanopositioning engineering

Nanomeasuring and nanopositioning engineering

Miniature interferometers for applications in microtechnology and nanotechnology

A contactless interferometric sensor for incremental scanning of variable interference structures

Nanomeasuring and Nanopositioning Engineering