Overview of tomography techniques to measure wafer thickness in MEMS structures

This report investigates possible metrology solutions to the industrial requirement for the measurement of the wafer thickness and internal structure of MEMS sensors. A range of optical and electrical techniques were reviewed and the report recommends optical coherence tomography as the most suitable technique. Optical coherence tomography is considered from a theoretical perspective and a range of system designs and commercially available instruments are discussed, including some images of a MEMS sensor as proof of concept. Finally recommendations are made for further research in image processing in order to obtain sub-micrometre axial resolution for MEMS measurement.

[1]  B. Sopori,et al.  Principles and Applications of Reflectometery in PV Manufacturing , 2001 .

[2]  Ruikang K. Wang,et al.  Time-resolved simultaneous measurement of group index and physical thickness during photopolymerization of resin-based dental composite. , 2007, Journal of biomedical optics.

[3]  R. Zawadzki,et al.  Numerical dispersion compensation for Partial Coherence Interferometry and Optical Coherence Tomography. , 2001, Optics express.

[4]  Vincent Loriette,et al.  Full-field birefringence imaging by thermal-light polarization-sensitive optical coherence tomography. II. Instrument and results. , 2003, Applied optics.

[5]  K P Chan,et al.  Coherent detection techniques in optical imaging of tissues. , 1997, Physics in medicine and biology.

[6]  Bin Liu,et al.  Group velocity dispersion effects with water and lipid in 1.3 microm optical coherence tomography system. , 2004, Physics in medicine and biology.

[7]  B. Sopori,et al.  Rapid mapping of AR coating thickness on Si solar cells using GT-FabScan 6000 , 2005, Conference Record of the Thirty-first IEEE Photovoltaic Specialists Conference, 2005..

[8]  J. Sun,et al.  Subsurface damage measurement in silicon wafers with cross-polarisation confocal microscopy , 2006 .

[9]  Kate Grieve,et al.  In vivo anterior segment imaging in the rat eye with high speed white light full-field optical coherence tomography. , 2005, Optics express.

[10]  Joseph M. Schmitt,et al.  MODEL OF OPTICAL COHERENCE TOMOGRAPHY OF HETEROGENEOUS TISSUE , 1997 .

[11]  C. Boccara,et al.  Ultrahigh-resolution full-field optical coherence tomography. , 2004, Applied optics.

[12]  Harald Sattmann,et al.  A thermal light source technique for optical coherence tomography , 2000 .

[13]  Richard C. Tozer,et al.  Electrical impedance tomography applied to semiconductor wafer characterization , 1996 .

[14]  B. Sopori,et al.  Process monitoring in solar cell manufacturing , 1999 .

[15]  Peter J. de Groot,et al.  Optical Topography Measurement of Patterned Wafers , 2005 .

[16]  Leslie L Deck,et al.  Fourier-transform phase-shifting interferometry. , 2003, Applied optics.

[17]  A. Fercher,et al.  Parallel Fourier domain optical coherence tomography for in vivo measurement of the human eye. , 2005, Optics express.

[18]  Vladimir Shidlovski,et al.  Ultrahigh resolution optical coherence tomography imaging with a broadband superluminescent diode light source. , 2004, Optics express.

[19]  B E Bouma,et al.  Spectrally-modulated full-field optical coherence microscopy for ultrahigh-resolution endoscopic imaging. , 2006, Optics express.

[20]  Subsurface Imaging with Widefield and Confocal Numerical Aperture Increasing Lens Microscopes , 2006, LEOS 2006 - 19th Annual Meeting of the IEEE Lasers and Electro-Optics Society.

[21]  Eugene A. Irene,et al.  Handbook of Ellipsometry , 2005 .

[22]  Daniel Mansfield,et al.  The distorted helix: thin film extraction from scanning white light interferometry , 2006, SPIE Photonics Europe.

[23]  P. Andersen,et al.  Swept wavelength source in the 1 microm range. , 2005, Optics express.

[24]  Robert J. Zawadzki,et al.  Dispersion compensation for optical coherence tomography depth-scan signals by a numerical technique , 2002 .

[25]  B. Sopori.  Principle of a new reflectometer for measuring dielectric film thickness on substrates of arbitrary surface characteristics , 1988 .

[26]  James G. Fujimoto,et al.  Ultrahigh resolution optical coherence tomography , 2002 .

[27]  Ruikang K. Wang,et al.  Stereoscopic optical coherence tomography in the frequency domain for refractive index sensitive imaging , 2007, European Conference on Biomedical Optics.

[28]  H. Y. Fan,et al.  Optical Properties of Semiconductors. III. Infra-Red Transmission of Silicon , 1949 .

[29]  B E Bouma,et al.  Optical Coherence Tomographic Imaging of Human Tissue at 1.55 μm and 1.81 μm Using Er- and Tm-Doped Fiber Sources. , 1998, Journal of biomedical optics.

[30]  J. Fujimoto,et al.  In vivo ultrahigh-resolution optical coherence tomography. , 1999, Optics letters.

[31]  Peter H. Tomlins,et al.  Simultaneous analysis of refractive index and physical thickness by Fourier domain optical coherence tomography , 2006 .

[32]  H. Tiziani,et al.  Three-dimensional image sensing by chromatic confocal microscopy. , 1994, Applied optics.

[33]  Ruikang K. Wang,et al.  Matrix approach to quantitative refractive index analysis by Fourier domain optical coherence tomography. , 2006, Journal of the Optical Society of America. A, Optics, image science, and vision.

[34]  B. Brown,et al.  Applied potential tomography: possible clinical applications. , 1985, Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics.

[35]  R. Azzam,et al.  Ellipsometry and polarized light , 1977 .

[36]  Roy T. Blunt.  White Light Interferometry - a production worthy technique for measuring surface roughness on semiconductor wafers , 2006 .

[37]  Maciej Wojtkowski,et al.  High-speed frequency swept light source for Fourier domain OCT at 20 kHz A-scan rate , 2005, SPIE BiOS.

[38]  B E Bouma,et al.  Ultrahigh-resolution full-field optical coherence microscopy using InGaAs camera. , 2006, Optics express.

[39]  W. Stumpf.  Investigation and Simulation of the Optical Properties of Doped Silicon , 2001 .

[40]  Daniel Mansfield,et al.  Thin film extraction from scanning white light interferometry , 2007, Optifab.

[41]  Patrick Sandoz,et al.  Thickness measurement of nontransparent free films by double-side white-light interferometry : Calibration and experiments , 2006 .

[42]  R.J. Pryputniewicz,et al.  Hybrid Methodology for Development of MEMS , 2006, 2006 IEEE/ION Position, Location, And Navigation Symposium.

[43]  James C. Wyant,et al.  White light interferometry , 2002, SPIE Defense + Commercial Sensing.

[44]  A. Fercher,et al.  Submicrometer axial resolution optical coherence tomography. , 2002, Optics letters.

[45]  J. Izatt,et al.  Swept source optical coherence tomography using an all-fiber 1300-nm ring laser source. , 2005, Journal of biomedical optics.

[46]  L. Goldberg,et al.  Characteristics of a Yb-doped superfluorescent fiber source for use in optical coherence tomography. , 1998, Optics express.

[47]  Harald Sattmann,et al.  Spectroscopic Fourier domain optical coherence tomography: principle, limitations, and applications , 2005, SPIE BiOS.

[48]  A. Boccara,et al.  Thermal-light full-field optical coherence tomography. , 2002, Optics letters.

[49]  Multiparameter measurements of thin films using beam‐profile reflectometry , 1993 .

[50]  Peter de Groot,et al.  Optical interferometry for measurement of the geometric dimensions of industrial parts. , 2002, Applied optics.

[51]  Y Fainman,et al.  Nontranslational three-dimensional profilometry by chromatic confocal microscopy with dynamically configurable micromirror scanning. , 2000, Applied optics.

[52]  Peter J. de Groot,et al.  Signal modeling for low-coherence height-scanning interference microscopy , 2004 .

[53]  W. Gao.  Dispersion properties of grating-based rapid scanning optical delay lines. , 2007, Applied optics.

[54]  Feng Gao,et al.  Measurement of structured surface using stylus, AFM and optical methods , 2007 .

[55]  Rainer Wilhelm,et al.  A novel low-coherence fibre optic interferometer for position and thickness measurements with unattained accuracy , 2006, Speckle: International Conference on Speckle Metrology.

[56]  Jorge R. Torga,et al.  Wide band interferometry for thickness measurement. , 2003, Optics express.

[57]  C. Pickering,et al.  Optical characterization techniques for process monitoring , 2001 .

[58]  Feng Gao,et al.  Surface measurement errors using commercial scanning white light interferometers , 2007 .

[59]  A. Boccara,et al.  Full-field birefringence imaging by thermal-light polarization-sensitive optical coherence tomography. I. Theory. , 2003, Applied optics.

[60]  Peter J. de Groot,et al.  Surface profiling by frequency-domain analysis of white light interferograms , 1994, Other Conferences.

[61]  B E Bouma,et al.  Self-phase-modulated Kerr-lens mode-locked Cr:forsterite laser source for optical coherence tomography. , 1996, Optics letters.

[62]  D. Kane,et al.  Common-path interferometer for frequency-domain optical coherence tomography. , 2003, Applied optics.

[63]  Michael Pircher,et al.  En-face scanning optical coherence tomography with ultra-high resolution for material investigation. , 2005, Optics express.

[64]  J. Fujimoto,et al.  Amplified, frequency swept lasers for frequency domain reflectometry and OCT imaging: design and scaling principles. , 2005, Optics express.

[65]  Joseph A. Izatt,et al.  Heterodyne swept-source optical coherence tomography for complete complex conjugate ambiguity removal , 2005, SPIE BiOS.

[66]  Joseph M. Schmitt,et al.  An optical coherence microscope with enhanced resolving power , 1997 .

[67]  Ruikang K. Wang,et al.  Theory, developments and applications of optical coherence tomography , 2005 .

[68]  Joseph A Izatt,et al.  Heterodyne swept-source optical coherence tomography for complete complex conjugate ambiguity removal. , 2005, Journal of biomedical optics.

[69]  Daniel L Marks,et al.  Inverse scattering for frequency-scanned full-field optical coherence tomography. , 2007, Journal of the Optical Society of America. A, Optics, image science, and vision.

[70]  A. Fercher,et al.  Measurement of intraocular distances by backscattering spectral interferometry , 1995 .

[71]  K Grieve,et al.  Three-dimensional cellular-level imaging using full-field optical coherence tomography. , 2004, Physics in medicine and biology.

[72]  Michael W. Davidson,et al.  LASER SCANNING CONFOCAL MICROSCOPY , 2005 .

[73]  Masato Ohmi,et al.  Low-coherence interferometer system for the simultaneous measurement of refractive index and thickness. , 2002, Applied optics.

[74]  M. Brezinski.  Optical Coherence Tomography: Principles and Applications , 2006 .

[75]  Jon Opsal,et al.  Beam profile reflectometry: A new technique for dielectric film measurements , 1992 .

[76]  M.V.P. Kruger,et al.  Electrical impedance tomography based sensors for semiconductor manufacturing , 2002, Proceedings of the 2002 American Control Conference (IEEE Cat. No.CH37301).