Micro- and Nano-Technology... for Optics

Transcription

1 Micro- and Nano-Technology for Optics U.D. Zeitner Fraunhofer Institut für Angewandte Optik und Feinmechanik Jena Today: 1. Introduction E. Bernhard Kley Institute of Applied Physics Friedrich-Schiller University Jena and Fraunhofer Institut für Angewandte Optik und Feinmechanik Jena

2 Course Content 1. Introduction (today) 2. Basic optical considerations - discussion of physical effects relevant in micro- and nano-optics 3. Fabrication technologies for micro- and nano-structures - Coating technologies - Lithography - Etching technologies - Replication - Ultra-precision micro-machining 4. Characterization techniques - mechanical profiler - AFM - SEM - optical surface profiler - interferometer 5. Applications

3 Additional Information Literature: - S. Sinzinger, J. Jahns Microoptics, Wiley-VCH - H.-P. Herzig Micro-Optics, Taylor & Francis - B.C. Kress, P. Meyrueis Applied Digital Optics, Wiley - C. Mack Fundamental Principles of Optical Lithography, Wiley Course material will be uploaded to: Lecture Micro- and Nano-Technology

4 Micro-Structured Optics in Nature 100µm Lens-arrays as insects eyes 2µm Nano-structures with anti-reflection properties on moth seyes 4µm Colors of butterflies by diffraction gratings

5 Different Approaches Nature Technology!? Bottom-Up Top-Down Lithography

6 Modern and high end optics need micro- und nanostructures 2 prominent examples

7 Vigo Galaxy cluster About 150 galaxies visible in the picture Galaxies are very different and what about our milky way?

8 GAIA s effective medium grating 230mm RVS GAIA (ESA) launched in Dec NGC 6744

9 Spectrometer grating for the Gaia mission of European Space Agency Gaia (Dec. 2011) -1E9 Stars - Magnitude: Distance measurement by read shift measurement Radial Velocity Spectrometer Spektral range: nm Grating

10 Gravitational Waves Gravitational wave Astronomy 1916 General Theory of Relativity [Einstein, AdP 1916] relative length deviation: [

11 Gravitational Wave Detection Reflective Michelson-Interferometer and critical components How to reduce the thermas noise Dl Detector [Drever, Proc. 7th M. Grossmann Meeting 1996

12 Monolithic dielectric mirror Motivation: Cavities for interferometer in gravitational detection and lasers Low optical and mechanical loss is required high reflectivity low mechanical Q-factor high mechanical Q-factor low reflectivity quartz / silicon n H n L n H n L n H n L n H Does a monolithic solution exist?

13 Monolithic resonant Si-mirror ( =1550 nm) waveguide + grating grating/effective media Si Si 99.8% reflectivity 1550nm

14 Silicon-Pattern for Monolithic Mirrors

15 Examples of micro-structured elements huge variety of low and high resolution structures

16 Size scale of micro-optical effects characteristic feature size 1mm micro-lenses, micro-prisms hybride elements 100µm 10µm 1µm 100nm 10nm lens-arrays, refractive beam-shaper diffractive beam-shaper, Fresnel-lenses, diffraction gratings effective media, sub- -gratings, photonic crystals, meta-materials

17 micro optics Size-Scale of Optical Structures optical effects 1m astronomic mirrors optical elements law of refraction and reflection 1mm lenses miniaturized lenses micro-lenses paraxial beam splitters light diffraction effective medium 1µm antireflection pattern, polarizers, phase retarder photonic crystals spectroscopic gratings non paraxial beam splitter spontaneous and stimulated emission 1nm 1Å (atomic size) light sources

18 Effects of Size-Scaling focus: f=5mm 125µm diffractive beam splitter wiregridpolarizer artificial dichroitic materials 2µm structure size 1mm 100µm 10µm 1µm 100nm physical effect: refraction diffraction disturbing useful! effective materialproperties influence of physical effects on optical functions is changing if characteristic feature sizes are scaled

19 Milestones of optical engineering Fourier Fourier expansion Maxwell electromagnetic wave theory Hertz exp. confirm. of Maxwell Personal Computer Fundamental understanding of optics Basics in physics and mathematics Analytical and numerical evaluation of physical optics Fresnel wave theory of the light Abbe theory of opt. image Zuse st calculator Dedicated micro- and nanomachining technologies

20 Fabrication Technologies for Micro-Optics different size and functionality different fabrication methods for micro-optical components compared to classical (macro) optics common micro-optics fabrication methods are lithography (photo-, e-beam-, laser-) ultra precision micro-machining melting / reflow technology more elaborated technologies

21 Lithography Process Chain for Resist pattern 1. Substrate preparation (cleaning, ) 2. Resist coating (e.g. spin coating) 3. Baking 4. Resist exposure e-beam lithography or photolithography 5. Resist development, e - Substrate (e.g. Si-wafer) resist (sensitive to light or electrons) evaporation of solvent patterned resist mask for subsequent processes

22 High-End Lithography Tool microelectronic chips on Si-wafers DUV lithography stepper, =193nm (ASML) EUV lithography stepper, =13.5nm (ASML) very low flexibility

23 Lithography Roadmap (past development) 2010 lithography roadmap

24 Lithography Roadmap (ongoing) International Technology Roadmap for Semiconductors (2015)

25 Lithography for Optical Applications Lithography tools are developed for micro-electronics fabrication! steady development along semiconductor road-map vanishing versatility for other applications Demands of optics on lithography: arbitrary lateral contours (often radially symmetric) several 100mm size of single elements with sub-micron features thick substrates for elements with low wave-front error non-planar substrates possible

26 Typical Optical Surfaces and Contours Contours Profiles lens prism beam shaper characteristic detail >> binary grating blazed grating > subwavelength gratings < complex surface profiles >> > < Courtesy of E.-B. Kley

27 Demanding Micro Optics Applications Pulse compression gratings Computer-Generated Holograms Spectrometry for Space Applications Polarizers

28 Lithography Process Chain for Optics e - 1. Resist exposure with e-beam lithography resist Cr-layer SiO 2 -Substrate 2. Resist development 3. Chromium etching (RIE) 4. Deep etching into substrate (ICP) optional: multiple iterations of the process for multi-level elements

29 Technology for continuous profiles variable dose exposure: intensity modulated exposure beam proportional transfer (RIE): Ions (e.g. CF 4 ) resist substrate development: t 1 t 2 dose dependent profile depth in resist after development process element profile transferred into substrate material