Dr. Jürgen Keller Profile

Dr. Jürgen Keller

Doctor at AMIC GmbH

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Publications (14)

Proceedings Article | 30 April 2007 Paper

NanoDAC: object deformation measurements for micro and nanotechnology applications

Dietmar Vogel, Jürgen Keller, Bernd Michel

Proceedings Volume 6528, 65280B (2007) https://doi.org/10.1117/12.717639

KEYWORDS: Atomic force microscopy, Scanning electron microscopy, Scanning probe microscopy, Digital image correlation, Photomicroscopy, Mechanics, Microelectromechanical systems, Ion beams, Nanotechnology, Reliability

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The manufacturing, handling and control of micro and nano scale devices require the quantification of their geometrical and mechanical properties. While the measurement of geometrical and size data is easily accessible by SFM and SEM imaging equipment, mechanical characterization is a general problem for these objects. Different kinds of size effects more often force material property determination directly on micro/nano objects. Therefore, new strategies for material testing have to be developed. Displacements and their derivatives are two basic properties to be measured during testing for many mechanical material properties. The authors make use of SFM and high resolution SEM imaging in order to obtain spatially resolved displacement data over the scan area. Locally applied cross correlation algorithms are utilized to compute displacement fields and the corresponding first order derivatives. Micrographs are captured subsequently for different object load states. The established technique and measurement system (nanoDAC) is reviewed briefly. The authors present different applications of the nanoDAC method establishing the characterization of micro/nano scale material behaviour. Among the application fields are approaches to measure fracture mechanics criteria from crack opening displacement (COD) fields, a method of measuring residual stresses in thin membranes and testing techniques to measure Young's modulus and Poisson's ratios of thin foils and micro wires. The measurement of fracture mechanics bases on linear elastic fracture mechanics. Measured by AFM, COD fields in the very vicinity of crack tips are used to extract fracture toughness values. Stress determination on membranes utilizes the unique capability of focused ion beam (FIB) equipment, which allows concurrent material milling and micrograph capture with high resolution. A Zeiss XBeam system has been used to mill trenches and holes into membranes of semiconductor structures. Treated that way stress release fields are determined from SEM micrographs. Taking into consideration reasonable stress hypotheses, membrane stresses are calculated from the obtained deformation fields. With the presented methods the basis is provided for an experimental reliability analysis of MEMS/NEMS and nanodevices.

Proceedings Article | 28 April 2006 Paper

High-resolution stress measurements for microsystem and semiconductor applications

Dietmar Vogel, Juergen Keller, Bernd Michel

Proceedings Volume 6188, 61880P (2006) https://doi.org/10.1117/12.669637

KEYWORDS: Digital image correlation, Silicon, Microsystems, Ion beams, Ions, Microelectromechanical systems, Photomicroscopy, Semiconductors, Sensors, Micromachining

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Proceedings Article | 4 April 2006 Paper

Nanoscale deformation measurements for reliability assessment of material interfaces

Astrid Gollhardt, Jürgen Keller, Bernd Michel, Dietmar Vogel

Proceedings Volume 6175, 617504 (2006) https://doi.org/10.1117/12.658637

KEYWORDS: Reliability, Interfaces, Digital image correlation, Scanning probe microscopy, Atomic force microscopy, Finite element methods, Microelectronics, Chemical elements, Microelectromechanical systems, Polymers

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Proceedings Article | 4 April 2006 Paper

FIB-based measurement of local residual stresses on microsystems

Juergen Keller, Neus Sabate, Dietmar Vogel, Bernd Michel, Astrid Gollhardt, Juergen Auersperg

Proceedings Volume 6175, 617505 (2006) https://doi.org/10.1117/12.658298

KEYWORDS: Digital image correlation, Silicon, Microsystems, Ion beams, Ions, Microelectromechanical systems, Photomicroscopy, Micromachining, Sensors, Manufacturing

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Proceedings Article | 16 March 2006 Paper

Nanoscale deformation measurements to improve reliability assessment of sensors and MEMS

Bernd Michel, Jürgen Keller, Hans Walter

Proceedings Volume 6179, 61790J (2006) https://doi.org/10.1117/12.660144

KEYWORDS: Sensors, Atomic force microscopy, Gas sensors, Digital image correlation, Microelectromechanical systems, Reliability, Scanning electron microscopy, Scanning probe microscopy, Ions, Ion beams

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Micro machined micro sensors for gas or flow detection based on physical behaviour of a special layer of a membrane have to fulfil high quality and reliability requirements especially in safety or security applications. Up to now, most of the research studies neglected mechanical issues related to reliability of these structures. In this sense, the study and characterization of the stress distribution on the membranes after fabrication and during their operative life is required. Thin films used in micromachined structures exhibit residual mechanical stress strongly dependent on the layer composition and the deposition process parameters. Often, a deposition of a multilayer is required, and this adds factors like abrupt transitions in thermal, elastic and plastic mismatch across the interfaces that have a direct effect on the resultant stress. Moreover, in operating conditions, a thermal stress originated due to the difference in the thermal expansion coefficient (CTE) of the membrane materials adds to the residual stress of the membrane. The resultant stresses can induce excessive deformation, fracture, delamination and microstructural changes in the material that can lead to the breaking of the structure during the fabrication stage or affect the behaviour of the final device. In the present work, the 2D deformation of a gas and a flow sensor membrane under different thermo-mechanical load states will be analysed by means of the digital image correlation (DIC) techniques based on scanning probe microscopy (SPM) data. With this technique which is introduced as the nanoDAC method (nano Deformation Analysis by Correlation) deformation fields can be determined with nanometer-accuracy. In addition ion milling by focused ion beam (FIB) technique is demonstrated at membrane specimens with residual stresses. Object deformations fields nearby the milling area are measured by fibDAC allowing the evaluation of very local residual stresses. Some principal experiments illustrate the feasibility of the chosen approach.

Proceedings Article | 1 July 2005 Paper

3D deformation analysis of flow and gas sensors membranes for reliability assessment

Neus Sabate, Astrid Gollhardt, Isabel Gracia, Joan Ramon Morante, Dietmar Vogel, Carles Cane, Juergen Keller, Bernd Michel

Proceedings Volume 5836, (2005) https://doi.org/10.1117/12.608660

KEYWORDS: Sensors, Gas sensors, Reliability, Silicon, Platinum, 3D metrology, Temperature metrology, Digital image correlation, Atomic force microscopy, Scanning probe microscopy

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Proceedings Article | 9 May 2005 Paper

FIB based measurements for material characterization on MEMS structures

Astrid Gollhardt, Dietmar Vogel, Bernd Michel, Neus Sabate, Daniel Lieske, Joan Ramon Morante, Juergen Keller

Proceedings Volume 5766, (2005) https://doi.org/10.1117/12.599891

KEYWORDS: Digital image correlation, Ions, Scanning electron microscopy, Microelectromechanical systems, Ion beams, Material characterization, Image resolution, Sensors, Error analysis, Copper

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Proceedings Article | 9 May 2005 Paper

Nanoscale deformation measurements for reliability analysis of sensors

Astrid Gollhardt, Juergen Keller, Bernd Michel, Dietmar Vogel

Proceedings Volume 5770, (2005) https://doi.org/10.1117/12.600713

KEYWORDS: Sensors, Atomic force microscopy, Gas sensors, Scanning probe microscopy, Reliability, Digital image correlation, Platinum, Microelectromechanical systems, Infrared sensors, Temperature metrology

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Proceedings Article | 12 April 2005 Paper

Deformation field measurement on micro and nanotechnology components utilizing SFM and FIB equipment

Astrid Gollhardt, Dietmar Vogel, Bernd Michel, Juergen Keller

Proceedings Volume 5852, (2005) https://doi.org/10.1117/12.621539

KEYWORDS: Atomic force microscopy, Digital image correlation, Sensors, Nanotechnology, Ions, Image resolution, Ion beams, Microsystems, Gas sensors, Platinum

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Proceedings Article | 12 April 2005 Paper

Design methodology of microstructures for enhanced mechanical reliability

Dietmar Vogel, Juergen Keller, Olaf Wittler, Hans Walter, Bernd Michel

Proceedings Volume 5852, (2005) https://doi.org/10.1117/12.621978

KEYWORDS: Reliability, Computer aided design, Failure analysis, Platinum, Atomic force microscopy, Analytical research, Gas sensors, Microsystems, Copper, Modeling

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Proceedings Article | 21 July 2004 Paper

Characterization of microcracks by application of digital image correlation to SPM images

Dietmar Vogel, Astrid Gollhardt, Juergen Keller, Bernd Michel

Proceedings Volume 5392, (2004) https://doi.org/10.1117/12.538433

KEYWORDS: Digital image correlation, Scanning probe microscopy, Atomic force microscopy, Finite element methods, Reliability, Sensors, Gas sensors, Platinum, Microelectronics, Interfaces

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Proceedings Article | 21 July 2004 Paper

Characterization of materials with nanoscopic filler particles by AFM techniques

Dietmar Vogel, Juergen Keller, Bernd Michel

Proceedings Volume 5392, (2004) https://doi.org/10.1117/12.540073

KEYWORDS: Particles, Atomic force microscopy, Polymers, Polishing, Microscopy, Surface finishing, Image resolution, Composites, Scanning electron microscopy, Scanning probe microscopy

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Proceedings Article | 21 July 2004 Paper

Determination of Local Stress Intensity Factor at Crack Tip Using Image Correlation Techniques

Dietmar Vogel, Juergen Keller, Yi-Yang Tsai, Daniel Eylon, Norbert Meyendorf, Bernd Michel

Proceedings Volume 5392, (2004) https://doi.org/10.1117/12.538757

KEYWORDS: Aluminum, Microscopy, Atomic force microscopy, Polishing, Reliability, Diagnostics, Computed tomography, Scanning electron microscopy, Beam splitters, Ultrasonics

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Proceedings Article | 22 July 2003 Open Access

Evaluating microdefect structures by AFM-based deformation measurement

Astrid Gollhardt, Dietmar Vogel, Juergen Keller, Bernd Michel

Proceedings Volume 5045, (2003) https://doi.org/10.1117/12.483826

KEYWORDS: Atomic force microscopy, Sensors, Microelectromechanical systems, Photomicroscopy, Scanning electron microscopy, Reliability, Mechanics, Image resolution, Failure analysis, Digital image correlation

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