Tactile 3D probing system for measuring MEMS with nanometer uncertainty : aspects of probing, design, manufacturing and assembly

Measurement underpins manufacturing technology, or in more popular terms: when you cannot measure it, you cannot manufacture it. This is true on any dimensional scale, so for microand nanotechnology to deliver manufactured products it must be supported by reliable metrology. Component miniaturization in the field of precision engineering and the development of micro electromechanical systems (MEMS) thus results in a demand for suitable measurement instruments for complex three-dimensional components with feature dimensions in the micrometer region and associated dimensional tolerances below 100 nm. As will be discussed in the first chapter of this thesis, several ultra precision coordinate measuring machines (CMMs) are developed. These CMMs are suitable for measuring complex threedimensional products, like MEMS and other miniaturized components. From a discussion on available probe systems in the first chapter it is apparent that, with respect to measurement uncertainty and applicability of measurements on MEMS and other miniaturized components, the performance of ultra precision CMMs is currently limited by the performance of available probe systems. The main reason is that the measurement using a probe system is not purely influenced by work piece topography, but also by interaction physics between probe tip and work piece. As the dimensional scale of the measurement decreases, the problems associated with this interaction become increasingly apparent. Typical aspects of this interaction include the influence of contact forces on plastic deformations in the contact region, surface forces and geometric and thermal effects. The influence of these aspects on the measurement result is discussed in the second chapter. This chapter will combine results from literature, simulation and experimental results to discuss the aspects that influence the measurement result in tactile probes. From these results it will become apparent that these aspects underlie the limitation for precision measurements on miniaturized components using tactile CMM metrology. As a result, these interaction aspects are the main challenge when designing ultra precision probes. The analysis of the interaction physics is used in the design of a novel silicon probing system with integrated piezo resistive strain gauges to measure a displacement of the probe tip. The result is a probe system with a colliding mass of 34 mg and an isotropic stiffness at the probe tip with a stiffness down to 50 N/m. The measurement range of the probing system is 30 µm, but in most measurements a range of 10 µm is used which slightly improves the signal to noise ratio. Calibration results using the planar differential laser interferometer setup as discussed in chapter 1 show a standard deviation of 2 nm over 2000 measurement points taken in a 6 hour time frame over a repeated 5.5 µm displacement. The combined 3D uncertainty of the probing system is estimated to be 17.4 nm. In order to measure micrometer scale structures, including holes and trenches, the probing system can be equipped with micrometer scale probe tips. The main limitation is the relative stiffness between the stylus and the suspension of the probing system. By design optimization, a ratio between the length and radius of the measurement part of the stylus of 50 can be obtained, making the probing system highly suitable for measuring these micrometer scale structures. So far, probe tips with a radius of 25 µm have been manufactured and work is being done to decrease this radius even further. The probing system is implemented on a high-accuracy coordinate measuring machine and is suitable for three-dimensional tactile measurements on miniaturized components with nanometer uncertainty. A main limitation when manufacturing the probe is assembly of the probe tip, stylus and chip which is discussed in chapter 4. Assembly of the probe is investigated in a series of experiments on an automated assembler. Based on these results, the design of the probe is optimized for assembly and the automated assembler is made suitable for assembly of the probe by implementation of a novel suction gripper. This resulted in an improvement in placement uncertainty at the tip by a factor of 10 and an increase in yield during assembly from 60 - 80% initially, to over 95%. In chapter 5 several experimental results with the probe system are discussed, including a quantification of the effects of surface forces on tactile measurements. It is shown that these effects are highly repeatable and result in an attraction of 40 µN and 60 µN in the xy- and z-direction, respectively. Moreover, it is shown that the influence of surface forces on a measurement in the xy-plane can be observed for a separation of 500 µm or less. Finally, conclusions and recommendations for further research are discussed in chapter 6

Loneliness literacy scale; development and evaluation of an early indicator for loneliness prevention

To develop and evaluate the Loneliness Literacy Scale for the assessment of short-term outcomes of a loneliness prevention programme among Dutch elderly persons. Scale development was based on evidence from literature and experiences from local stakeholders and representatives of the target group. The scale was pre-tested among 303 elderly persons aged 65 years and over. Principal component analysis and internal consistency analysis were used to affirm the scale structure, reduce the number of items and assess the reliability of the constructs. Linear regression analysis was conducted to evaluate the association between the literacy constructs and loneliness. The four constructs “motivation”, “self-efficacy”, “perceived social support” and “subjective norm” derived from principal component analysis captured 56 % of the original variance. Cronbach’s coefficient a was above 0.7 for each construct. The constructs “self-efficacy” and “perceived social support” were positively and “subjective norm” was negatively associated with loneliness. To our knowledge this is the first study developing a short-term indicator for loneliness prevention. The indicator contributes to the need of evaluating public health interventions more close to the intervention activities

Framing Signals - A Return to Portable Shellcode

Abstract—Signal handling has been an integral part of UNIX systems since the earliest implementation in the 1970s. Nowadays, we find signals in all common flavors of UNIX systems, including BSD, Linux, Solaris, Android, and Mac OS. While each flavor handles signals in slightly different ways, the implementations are very similar. In this paper, we show that signal handling can be used as an attack method in exploits and backdoors. The problem has been a part of UNIX from the beginning, and now that advanced security measures like ASLR, DEP and stack cookies have made simple exploitation much harder, our technique is among the lowest hanging fruit available to an attacker. Specifically, we describe Sigreturn Oriented Programming (SROP), a novel technique for exploits and backdoors in UNIX-like systems. Like return-oriented programming (ROP)

Aspects of tactile probing on a micro scale

Measurement instruments are sensitive to more than one physical quantity. When measuring work piece topography, the measurement result will always be influenced by the environment and (local) variations in the work piece itself. The aspects that influence the interaction between probe tip and work piece become increasingly apparent when the scale of measurement and the required uncertainty decreases

High-accuracy CMM metrology for micro systems

The increasing use of micro systems in industry combined with an ever-increasing demand for higher measurement accuracy has led to ongoing developments in the field of dimensional metrology. Recently, several measuring machines suitable for measuring micro mechanical products have been introduced to the market. This article aims to give an overview of the state-of-the-art methods for these measurement tasks

Aspects of tactile probing on a micro scale

Measurement instruments are sensitive to more than one physical quantity. When measuring work piece topography, the measurement result will always be influenced by the environment and (local) variations in the work piece itself. The aspects that influence the interaction between probe tip and work piece become increasingly apparent when the scale of measurement and the required uncertainty decreases

Analysis of the measurement sensitivity of multidimensional vibrating microprobes

A comparison is made between tactile and vibrating microprobes regarding the measurement of typical high aspect ratio microfeatures. It is found that vibrating probes enable the use of styli with higher aspect ratios than tactile probes and are still capable of measuring with high sensitivity. In addition to the one dimensional sensitivity, the directional measurement sensitivity of a vibrating probe is investigated. A vibrating microprobe can perform measurements with high sensitivity in a space spanned by its mode shapes. If the natural frequencies that correspond to these mode shapes are different, the probe shows anisotropic and sub-optimal measurement sensitivity. It is shown that the closer the natural frequencies of the probe are, the better its performance is when regarding optimal and isotropic measurement sensitivity. A novel proof-of-principle setup of a vibrating probe with two nearly equal natural frequencies is realized. This system is able to perform measurements with high and isotropic sensitivity

Characterization of measurement effects in an MST based nano probe

A tactile probe has been designed at the Eindhoven University of Technology to measure a translation of its tip with a 3D uncertainty of 20 nm or better. The suspension of this probe and the electrical connections are manufactured in a series of etching and deposition steps and can be considered to be a Micro Electro-Mechanical System (MEMS). It will be shown that hysteresis effects can have a dominant influence on the probe measurement uncertainty. Several sources of hysteresis within the probe system are investigated experimentally