Nanomeasuring Machine Research Articles

Novel control scheme for a high-speed metrological scanning probe microscope

Some time ago, an interferometer-based metrological scanning probe microscope (SPM) was developed at the Institute of Process Measurement and Sensor Technology of the Ilmenau University of Technology, Germany. The specialty of this SPM is the combined deflection detection system that comprises an interferometer and a beam deflection. Due to this system it is possible to simultaneously measure the displacement, bending and torsion of the probe (cantilever). The SPM is integrated into a nanopositioning and nanomeasuring machine (NPM machine) and allows measurements with a resolution of 0.1 nm over a range of 25 mm × 25 mm × 5 mm. Excellent results were achieved for measurements of calibrated step height and lateral standards and these results are comparable to the calibration values from the Physikalisch-Technische Bundesanstalt (PTB) (Dorozhovets N et al 2007 Proc. SPIE 6616 661624–1–7). The disadvantage was a low attainable scanning speed and accordingly large expenditure of time. Control dynamics and scanning speed are limited because of the high masses of the stage and corner mirror of the machine. For the vertical axis an additional high-speed piezoelectric drive is integrated in the SPM in order to increase the measuring dynamics. The movement of the piezoelectric drive is controlled and traceable measured by the interferometer. Hence, nonlinearity and hysteresis in the actuator do not affect the measurement. The outcome of this is an improvement of the bending control of the cantilever and much higher scan speeds of up to 200 µm s−1.

Measurement of deep groove structures using a self-fabricated long tip in a large range metrological atomic force microscope

Metrological atomic force microscopes are widely used in national metrology institutes for measuring step height, lateral pitch and surface roughness. However, the maximum measurable depth or height variation is limited by both the vertical scanning range of the AFM and the tip height and sharpness of the tip at the end of the cantilever. A normal commercial AFM typically has a vertical scanning range less than 10 µm and a tip height of the cantilever only up to 15 µm so that it can be used to detect only relatively smooth surfaces or shallow structures up to several micrometres. To overcome these limitations, we have successfully integrated a long diamond tip of up to 120 µm developed at Namiki Precision Jewel Co., Ltd of Japan onto our large range metrological atomic force microprobe (LRM-AFM) for deep groove structure measurement. The LRM-AFM is based on a nano-measuring machine with a large scanning range of 25 mm in the X and Y axes and 5 mm in the Z axis. This paper describes the long diamond tip fabrication process and especially its application in the LRM-AFM for measuring deep groove structures of a step height of up to 100 µm. In addition, the mechanical quality factor (Q) of the diamond tip micro-cantilever was detected in the system. The results demonstrate that the system is capable of calibrating and measuring the surface structure with deep groove in tens of micrometres.

A nanomeasuring machine based white light tilt scanning interferometer for large scale optical array structure measurement

White light vertical scanning interferometry (VSI) has been well developed during the past two decades and it is well suited for optical component evaluation due to its non-contact nature. However, because of its inherent limits in the field of view, the VSI is incapable of performing large range measurements. For large surfaces, stitching must be employed. In this paper, a nanomeasuring machine (NMM) based white light tilt scanning interferometer (TSI) is described, which can evaluate an optical array component in one round, without the need for stitching. By integrating a NMM, the tilt angle in the TSI no longer will require to be calibrated, easing in this way the realization of the TSI. With a tilt stage mounted on the NMM, the proposed system has two angles related to the measurement, which can provide excellent “fringes slipping out” correction ability. The analysis and the experiments are given.

Metrological atomic force microscope with self-sensing measuring head

A metrological atomic force microscope (AFM) adapting compact measuring head for the micro-nano dimensional measurement is introduced in this paper. Based on a novel self-sensing probe the head does not need any optical detector to measure the bending of the cantilever, significantly saving the working space to integrate with other measuring methods. This AFM operates in tapping mode and adapts frequency modulation (FM) mode to enhance measuring speed. A z-axis piezoelectric positioning stage (compact z-stage), with high resonant frequency, is responsible for the rapid motion of the sample in z-direction. A high-end digital signal processing (DSP) servo control system further guarantees high measurement speed. A nano-measuring machine (NMM) is equipped as the lateral moving stage to realize three-dimensional measurement. Three interferometers in the NMM enable the measurement to be traced to the meter definition. After calibration, the measurement of one-dimensional grating has been made. According to experimental results, the resolution of the AFM can reach nanometer level.

Performance and limitation of nanomeasuring technology

The paper describes traceable nanometrology based on a nanomeasuring machine. The high performance of the machine is explained with a metrological analysis. This analysis shows some of today’s limits of the nanopositioning and nanomeasuring engineering. The limits are based, for instance, on the metre definition as redefined in 1983 as well as on the comparison between an iodine-stabilised helium-neon laser and a stabilised helium-neon laser to be stabilised and on the influence of the refractive index of the air. In addition to the stability of the machine’s metrological frame, the realisation of the Abbe comparator principle plays a fundamental role in machine design and represents a significant challenge when being applied in all axes simultaneously. There are various machines for positioning and measuring samples which are based on different working modes: scanning probe mode, mixed scanning mode and sample scanning mode. These modes are analysed with respect to first- and second-order Abbe errors.

Measurements of dimensional standards and etalons with feature size from tens of micrometres to millimetres by using sensor strengthened nanomeasuring machine

A laser focus sensor and a contact inductive sensor have been coupled to an ultra high precision positioning stage, referred to as a nanomeasuring machine (NMM), for measurements of dimensional standards with a large measurement volume of 25 mm × 25 mm × 5 mm. Control and measurement software have been designed and complemented. The measurement uncertainty of strengthened NMM has been analyzed and discussed. Groove depth and step height standards with feature heights of tens of micrometres to millimetres as well as aspherical surface etalons are calibrated by nanomeasuring machine. The paper also introduces a method for characterising the measured aspheric surface by least square fitting the measured data to a quadratic paraboloid function. The obtained quadratic coefficients are compared to that measured by a conventional coordinate measuring machine (CMM) and a stylus profiler, showing a good agreement.

Three-dimensional nanopositioning and nanomeasuring machine with a resolution of 0.1 nm

The paper describes traceable nanometrology based on a nanopositioning machine with integrated nanoprobes. The operation of a high-precision long-range three-dimensional nanopositioning and nanomeasuring machine (NMM-1) having a resolution of 0.1 nm over the positioning and measuring range of 25 × 25 × 5 mm is explained. Various developed probe systems have been integrated into the NMM-1 machine, including a focus sensor, a white light sensor, and tactile nanoprobes. Single-beam, double-beam, and triple-beam interferometers are installed into the NMM-1 machine to measure and control the six degrees of freedom. Measured results are presented.

Nanomeasuring and nanopositioning engineering

The paper describes traceable nanometrology based on a nanopositioning machine with integrated nanoprobes. The operation of a high-precision long range three-dimensional nanopositioning and nanomeasuring machine (NPM-Machine) having a resolution of 0.1 nm over the positioning and measuring range of 25 mm × 25 mm × 5 mm is explained. An Abbe offset-free design of three miniature plan mirror interferometers and applying a new concept for compensating systematic errors resulting from mechanical guide systems provide very small uncertainties of measurement. The NPM-Machine has been developed by the Institute of Process Measurement and Sensor Technology of the Technische Universität Ilmenau and manufactured by the SIOS Messtechnik GmbH Ilmenau. The machines are operating successfully in several German and foreign research institutes including the Physikalisch-Technische Bundesanstalt (PTB), Germany. The integration of several, optical and tactile probe systems and nanotools makes the NPM-Machine suitable for various tasks, such as large-area scanning probe microscopy, mask and wafer inspection, nanostructuring, biotechnology and genetic engineering as well as measuring mechanical precision workpieces, precision treatment and for engineering new material. Various developed probe systems have been integrated into the NPM-Machine. The measurement results of a focus sensor, metrological AFM, white light sensor and tactile stylus probes are presented. Single beam-, double beam- and triple beam-interferometers built in the NPM-Machine for six degrees of freedom measurements are described.

Asymmetric motion profile planning for nanopositioning and nanomeasuring machines

This work presents an analytic fourth-order trajectory planning algorithm, which is able to plan asymmetric motions with arbitrary initial and final velocities. Furthermore, the proposed algorithm is based on a set of quadratic derivates of jerk (djerk) functions and generates continuously differentiable trajectories in jerk, acceleration, velocity, and position under consideration of kinematic constraints in all these kinematical values. The trajectories planned by the algorithm also have time-optimal characteristics, and a synchronization between the three motion axes of the Cartesian coordinate system is ensured by the proposed method. These characteristics make it ideally suited for use as a trajectory planning algorithm in high-precision applications such as nanopositioning and nanomeasuring machines.

Limitations of precision length measurements based on interferometers

The most important principles, the basis and operation of heterodyne and homodyne interferometers are discussed. Their benefits and limitations are covered based on a metrological analysis. The resolution of interferometers can be determined by calculating the smallest resolvable distance increment. Also, it is shown here how the Abbe comparator principle can be fulfilled in all three measuring dimensions by using interferometers. Other factors in addition to the Abbe errors are discussed which affect the measurement uncertainty of interferometric length measurements. The Abbe-error-free design is explained using the example of a nanopositioning and nanomeasuring machine developed at the Institute of Process Measurement and Sensor Technology (Ilmenau University of Technology) and manufactured at the SIOS Meßtechnik GmbH Ilmenau, Germany.

Advanced three-dimensional scan methods in the nanopositioning and nanomeasuring machine

The nanopositioning and nanomeasuring machine developed at the Ilmenau University of Technology was originally designed for surface measurements within a measuring volume of 25 mm × 25 mm × 5 mm. The interferometric length measuring and drive systems make it possible to move the stage with a resolution of 0.1 nm and a positioning uncertainty of less than 10 nm in all three axes. Various measuring tasks are possible depending on the installed probe system. Most of the sensors utilized are one-dimensional surface probes; however, some tasks require measuring sidewalls and other three-dimensional features. A new control system, based on the I++ DME specification, was implemented in the device. The I++ DME scan functions were improved and special scan functions added to allow advanced three-dimensional scan methods, further fulfilling the demands of scanning force microscopy and micro-coordinate measurements. This work gives an overview of these new functions and the application of them for several different measurements.

The Metrological Basis and Operation of Nanopositioning and Nanomeasuring Machine NMM-1Metrologische Grundlagen und Wirkungsweise der Nanopositionier- und Messmaschine NMM-1

Abstract After an explanation of the set-up of a nanomeasuring machine NMM-1, its high performance is described with a metrological analysis. This analysis shows some of today´s limits of nanopositioning and nanomeasuring engineering. Single, double and triple beam plane mirror interferometers are applied in the nanomeasuring machine in order to measure and control the six degrees of freedom of the 3D nanopositioning stage. The various applications of the nanomeasuring machine are based on the installation of optical and tactile nanoprobes above the 3D nanopositioning stage. The set-up, function and measurement results of some zero-point nanoprobes in combination with the nanomeasuring machine are explained.

Development of 3D Force Sensors for Nanopositioning and Nanomeasuring Machine

In this contribution, we report on different miniaturized bulk micro machined three-axes piezoresistive force sensors for nanopositioning and nanomeasuring machine (NPMM). Various boss membrane structures, such as one boss full/cross, five boss full/cross and swastika membranes, were used as a basic structure for the force sensors. All designs have 16 p-type diffused piezoresistors on the surface of the membrane. Sensitivities in x, y and z directions are measured. Simulated and measured stiffness ratio in horizontal to vertical direction is measured for each design. Effect of the length of the stylus on H:V stiffness ratio is studied. Minimum and maximum deflection and resonance frequency are measured for all designs. The sensors were placed in a nanopositioning and nanomeasuring machine and one point measurements were performed for all the designs. Lastly the application of the sensor is shown, where dimension of a cube is measured using the sensor.

Model-driven development and multiprocessor implementation of a dynamic control algorithm for nanopositioning and nanomeasuring machines

This article presents a computationally intensive adaptive trajectory tracking control algorithm for dynamic control of nanopositioning and nanomeasuring machines. To realize the required high sample rate of the control algorithm, an embedded multiprocessor architecture has been chosen as development target. The model-oriented development approach studied here aims to narrow the gap between the control system design environment MATLAB/Simulink® and the actual distributed implementation on the custom platform by introducing a custom code generation target intending the utilization of automatic code generation facilities.

Nanotopographic characterization of spotted micro arrays on polyvinyl alcohol films by high‐resolution long‐range nanoprofiling

The nanopositioning and nanomeasuring machine was applied for the nanotopographic characterization of polymer micro spot arrays of fluorimetric chemochips. Chemochips are arrays of fluorescence dyes in a hydrogel matrix with different response behaviors of chemical components determination of chemical and physico-chemical properties of analytes by a pattern recognition approach. For the characterization and quality control of the spots, a nanometer resolution is needed over a scan range of several millimeters. This challenge could be met by use of a scanning probe sensor in connection with a laser interferometer controlled high-precision positioning and measuring device. This way, topographic scans with the resolution of atomic force microscope could be achieved over these demandingly large ranges. The technique was used in order to determine the quality of thin film micro spots made from fluorescence dye solutions on preformed polymer films and also tested for characterization of monomolecular films in the form of micro spots. The nanotopographic measurements reflect the strong influence of solvent/matrix interaction, wetting, swelling and material transport during the application of picoliter droplets in the spotting process. The measurement clarifies the reason for the formation of roughness in the nanometer range by nano-crystal formation in the upper part of polymer film and the rim formation of micro spots during solvent evaporation. The studies show the effect of application of different numbers of droplets in a dispensing series for spot formation and prove the high importance of polymer/solvent interaction for the quality of formed micro spots as well as for spot arrays of monomolecular films.

Traceable Nanometrology Realized by Means of Nanopositioning and Nanomeasuring Machine

The today’s nanometrology limits the accuracy of the precision engineering. These limits are based on the meter definition as redefined in 1983. It is proposed to define precision mechatronics as the science and engineering of high level precision systems and machines. The paper describes a precision mechatronic machine. This device represents a long range positioning machine having a resolution of 0.1 nm over the range of 25 mm x 25 mm x 5 mm. The integration of several optical and tactile nanoprobes makes the 3D-nanopositioning suitable for various tasks. New developed nanoprobes (optical focus probe, nanoindenter, metrological scanning force microscope) and results of measurement will be presented.

集成聚焦式测头的纳米测量机用于台阶高度标准的评价

集成聚焦式测头的纳米测量机用于台阶高度标准的评价

An atomic force microscope head designed for nanometrology

An atomic force microscope (AFM) head designed for nanometrology is accomplished in this study. It is the sensing component of the nano-measuring machine, a nanometrological instrument with a working range of 50 mm × 50 mm × 2 mm, as well as a part of the metrological system of the instrument. Three reference mirrors are mounted on the head and arranged without Abbe error. Relative displacement of the AFM head and the specimen is measured by interferometers and results are traceable. The optical beam deflection method is used to detect the atomic force. The laser beam is introduced through a single-mode polarization-maintaining optical fibre from an external laser diode. With a compact design, a 100 mm optical lever is realized inside the AFM head that is less than 20 mm in thickness and 200 g in weight. A force–distance curve is obtained using a gauge block in a test. Furthermore, online tests of the measurement of a step scale have been made. According to the calculation and experimental verification, the resolution of our AFM head reaches 0.05 nm.

Investigations and calculations into decreasing the uncertainty of a nanopositioning and nanomeasuring machine (NPM-Machine)

Continuously increasing demands on nanopositioning and nanomeasuring (NPM) machines require a detailed analysis of and a decrease in measurement uncertainty. Initial studies have been done in the field of length and angle measurement. The analysis resulted in updated assemblies, which were investigated further. Significant improvements in mechanical stability, drift behaviour and temperature dependence were produced. To minimize the undesired heat production by the non-self-locking vertical linear drive systems, an improved weight force compensation arrangement adaptable to different object masses was developed and tested. Also, the system's natural frequencies were analysed. A modified structure with increased stiffness of the vertical drive system was designed to improve the NPM's dynamic behaviour.

New applications of the nanopositioning and nanomeasuring machine by using advanced tactile and non-tactile probes

With the nanopositioning and nanomeasuring machine (NPM-Machine) developed at the Technische Universität Ilmenau, subnanometre resolution and nanometre uncertainty in a measuring volume of 25 × 25 × 5 mm3 have been demonstrated in the last few years. This machine allows the most various measuring problems to be solved. In practice, however, there are too many different requirements for sensing surfaces or for detecting structures. So, this paper deals with the development and also the improvement of several optical and tactile probes for application in the NPM-Machine. A focus probe with a spot size of approximately 0.5 µm, a working distance of 1.5 mm and a resolution of less than 1 nm was developed and adopted in the NPM-Machine. In the next step, the working distance was improved to exploit the full vertical range of the NPM-Machine of 5 mm. To realize tactile sensing, an atomic force probe and tactile stylus probe were developed on the basis of the focus probe. These probing systems can acquire measuring data only by scanning the surface sequentially and point-by-point. To increase data acquisition, we realized a sensor based on a white-light interference microscope and parallel sampling of 1600 × 1200 data points. First results of fringe evaluation with laser interferometer reference are presented.