9/28/2005 Nanoscale Nanoscale Imaging of Semiconductor and Imaging of Semiconductor and Biological Systems Biological Systems M. Selim Ünlü Boston University www.bu.edu/OCN Electrical Engineering Physics Biomedical Engineering Photonics Center / CNN LEOS DL Talk – 1 2005 1 Outline Outline • Nano-Optics – Aperture NSOM • Earlier results (brief) • Solid Immersion Lens Microscopy • Numerical Aperture Increasing Lens (NAIL) • Applications in IC imaging, thermal microscopy • Quantum Dot Spectroscopy • Spectral Self-interference Microscopy • Preliminary results on lipid bilayers • DNA conformation studies LEOS DL Talk – 1 2005 2 M. Selim Ünlü - Boston University 1
9/28/2005 Mo Motivat tivation on: Resolution Resolution Limitation Limitation in in Optics Optics = α n NA sin f 2w 10 f 2w 20 = f # w 2 01 λ = λ 2 4 ≈ spotsize f # π π n NA LEOS DL Talk – 1 2005 3 Aperture Near-Field Microscopy Aperture Near-Field Microscopy Light or RF d a Resolution limited by a an d d 100 X Resolution limited by and Synge 1928 • concept, scanning 1970’s RF metal plate LEOS DL Talk – 1 2005 4 M. Selim Ünlü - Boston University 2
9/28/2005 Aperture NSOM Imaging of PBG, Waveguide Devices and Lasers 9/28/2005 LEOS DL Talk – 1 www.bu.edu/OCN Wavegui Waveguide Experimental Setup e Experimental Setup 2.0 2.0 y (microns) y (microns) 1.0 1.0 0.0 0.0 -1.0 -1.0 Refractive index -2.0 optical field -2.0 -3.0 -3.0 -4 -3 -2 -1 0 1 2 3 4 -4 -3 -2 -1 0 1 2 3 4 x (microns) x (microns) LEOS DL Talk – 1 2005 6 M. Selim Ünlü - Boston University 3
9/28/2005 Optical fiber with wedged lens and AR coating Optical fiber with wedged lens and AR coating 980 nm GRINSCH LD 980 nm GRINSCH LD LEOS DL Talk – 1 2005 7 Laser Diode Facet under 40X microscope Laser Diode Facet under 40X microscope Laser NSOM Diode Probe AR-facet pointing pointing away towards from viewing viewing direction direction LEOS DL Talk – 1 2005 8 M. Selim Ünlü - Boston University 4
9/28/2005 Lat Latera ral Beam Shift l Beam Shifts in in t the Near- e Near-Field ield a and Po d Poin inting in ng in the Far-Field du the Far-Field due to M e to Mode de Be Beating ating ⎡ ⎤ ⎡ ⎤ ⎡ ⎤ w x y 2 2 = U x y z A 0 G G ( , , ) ⎢ ⎥ ⎢ ⎥ ⎢ ⎥ l , m l , m l m w z w z w z ⎣ ( ) ⎦ ( ) ( ) ⎣ ⎦ ⎣ ⎦ ⎡ + ⎤ 2 2 x y ⎛ ⎞ z × − − + + + × − 1 jkz jk j l m ⎜ ⎟ exp ( 1 ) tan ⎢ ⎥ z ⎝ ⎠ 2 R ( z ) ⎣ ⎦ 0 PTL Dec 2000 LEOS DL Talk – 1 2005 9 Outline Outline • Nano-Optics – Aperture NSOM • Earlier results (brief) • Solid Immersion Lens Microscopy • Numerical Aperture Increasing Lens (NAIL) • Applications in IC imaging, thermal microscopy • Quantum Dot Spectroscopy • Spectral Self-interference Microscopy • Preliminary results on lipid bilayers • DNA conformation studies LEOS DL Talk – 1 2005 10 M. Selim Ünlü - Boston University 5
9/28/2005 Throughput vs. spot size Throughput vs. spot size SIL 1 Glass Si GaP 10 -1 Sapphire 10 -2 Diffraction limit 10 -3 in air Throughput Near-field 10 -4 fiber tips 10 -5 10 -6 10 -7 0.10 0.15 0.4 0.5 1.0 Spot size in units of wavelength SIL with GaP Q Wu, G.D. Feke, R.D. Grober and L.P. Ghislain, Appl. Phys. Lett. 75, 4064 (1999) LEOS DL Talk – 1 2005 11 Solid Immersion Lens Techniques Solid Immersion Lens Techniques Surface microscopy Surface microscopy Standard Solid Immersion Lens Super - SIL LEOS DL Talk – 1 2005 12 M. Selim Ünlü - Boston University 6
9/28/2005 Subsurface microscopy Subsurface microscopy Object is already “immersed” Object is already “immersed” Standard Standard Numerical Aperture oil Immersion subsurface Increasing Lens (NAIL) LEOS DL Talk – 1 2005 13 Need for Backside Imaging for ICs Need for Backside Imaging for ICs Opaque metal above buried devices often make imaging through the substrate preferable Stephen Ippolito, PhD May 2004 LEOS DL Talk – 1 2005 14 M. Selim Ünlü - Boston University 7
9/28/2005 Si IC failure analysis – Si IC failure analysis – resolution (?) esolution (?) LEOS DL Talk – 1 2005 15 Two types of stigmatic NAILs central NAIL aplanatic NAIL D = R - X D = R ( 1+1 / n ) - X 16 M. Selim Ünlü - Boston University 8
9/28/2005 Comparison of limitations conventional NAIL Light-gathering power Light-gathering power θ a = sin -1 ( 1/n ) θ a = π / 2 NA = 1 NA = n Lateral spatial resolution Lateral spatial resolution λ 0 / 2 λ 0 / 2n Longitudinal spatial resolution Longitudinal spatial resolution n λ 0 ( 1+ cos θ a ) λ 0 / n 17 Qualitative Qualitative Comparison Comparison 100X objective Conventional State-of-the-art 10 µm Hamamatsu µ AMOS-200, IC Failure Analysis System 1.3 µ m laser confocal scanning optical microscope 5X , 10X , 20X , and 100X objectives 10X with NAIL Images are courtesy of Boston University Hamamatsu Photonics LEOS DL Talk – 1 2005 18 M. Selim Ünlü - Boston University 9
9/28/2005 Hig High r resolution NIR inspection mic solution NIR inspection microsc oscope Optimized confocal microscope at λ=1.05 µm Resolution: 230 nm lateral 1.3 µm axial APL 2001 19 Thermal Imaging on Al Wires Thermal Imaging on Al Wires thermal w/ NAIL w/o NAIL LEOS DL Talk – 1 2005 20 M. Selim Ünlü - Boston University 10
9/28/2005 Application: Failure Analysis Application : Failure Analysis Dave Vallett and Ted Levin (IBM Microelectronics Division - Burlington, VT) Reflectivity image Overlay of LIVA and @ 1340nm reflectivity using NAIL Reflectivity image with NAIL @ 1340nm LIVA image with NAIL @ 1064nm LEOS DL Talk – 1 2005 21 LIVA images at 1064nm 50X + AR 20X + NAIL 10 µm LEOS DL Talk – 1 2005 22 M. Selim Ünlü - Boston University 11
9/28/2005 Commercial Commercial Product Product Patent US 6,687,058 – Feb. 3,04 LEOS DL Talk – 1 2005 23 QD Spectroscopy Resolution and stability Linecut • Improvement in resolution λ ≈ D NA 2 • Improvement in throughput ∝ − θ I ( 1 cos ) • Improvement in stability ′ d = M d 9/28/2005 LEOS DL Talk – 1 www.bu.edu/OCN M. Selim Ünlü - Boston University 12
9/28/2005 Use of Aplanatic NAIL Quantify Collection Efficiency Increase NA = .6 1st InGaAsQ >100nm Ds 500µm λ ex = 840nm GaAs T = 8 K NA=.12 2nd ~500µm How can we utilize this increase in ~max 8x colleciton efficiency?? 9/28/2005 LEOS DL Talk – 1 www.bu.edu/OCN Outline Outline • Nano-Optics – Aperture NSOM • Earlier results (brief) Mehmet Dogan, • Solid Immersion Lens Microscopy Physics, PhD 2006 • Numerical Aperture Increasing Lens (NAIL) • Applications in IC imaging, thermal microscopy • Quantum Dot Spectroscopy • Spectral Self-interference Microscopy • Preliminary results on lipid bilayers • DNA conformation studies Lev Moiseev, Bio, PhD May 2003 LEOS DL Talk - 1 2005 26 M. Selim Ünlü - Boston University 13
9/28/2005 Interference of Fluorescent Emission • 1898 O. Wiener discovers standing waves on top of silver mirror covered with photosensitive material • 1960’s K. Drexhage studies fluorescence lifetime of dyes on lipid multilayers. • 1996 P. Fromherz shows fluorescence interferometry can determine the height of buried emitters above mirror 9/28/2005 LEOS DL Talk – 1 www.bu.edu/OCN Interference of Fluorescent Emission Fluorescence emission intensity Lipid multilayers with fluorescent dye on top Mirror Mirror Monomolecular layers of fluorescent dyes on top of a stair- like lipid multilayers show dependence of fluorescent emission on the thickness of the lipid film Drexhage et al , Prog. Optics , XII , p. 163, 1974 9/28/2005 LEOS DL Talk – 1 www.bu.edu/OCN M. Selim Ünlü - Boston University 14
9/28/2005 Basic Reflectivity Model Direct wave Reflected wave Fluorophore d R TE,TM SiO 2 spacer layer D Si substrate 9/28/2005 LEOS DL Talk – 1 www.bu.edu/OCN From Spectrum to Axial Position Measured Oscillatory Spectral = x Spectrum Component Envelope 0.18 180 0.0012 0.16 160 0.001 0.14 140 Fluorescence (a.u.) 0.12 120 0.0008 0.1 100 = x 0.0006 0.08 80 0.06 60 0.0004 0.04 40 0.0002 20 0.02 0 0 0 16000 16500 17000 17500 18000 18500 16000 16500 17000 17500 18000 18500 16000 16500 17000 17500 18000 18500 wave number (1/ cm) wave number (1/cm) wave number (1/cm) data model Axial Position with sub-nm accuracy 9/28/2005 LEOS DL Talk – 1 www.bu.edu/OCN M. Selim Ünlü - Boston University 15
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