λ = 1.15 μm; 40 x objective; 2 μm spaced lines yield 18% resolution. λ = 0.6328 μm; 16 x objective; 3.12 μm spaced lines yield 30% resolution. λ = 1.15 μm; 16 x objective; 4 μm spaced lines yield 13% resolution. λ = 0.6328 μm; 8 x objective; 4 μm spaced lines yield 13% resolution. λ = 1.15 μm; 8 x objective; 8 μm spaced lines yield 10% resolution. λ = 0.6328 μm; 4 x objective; 16 um spaced lines yield 50% resolution. λ = 1.15 μm; 4 x objective; 16 um spaced lines yield 13% resolution. 4. Scanning rates a. horizontal 3 mHz to 100 Hz without incurring significant distortion, and 1.2 kHz b. vertical 3 mHz to 100 Hz 5. Mixer specifications dc to 2 MHz frequency response up to 34 dB gain on each channel 0, 3, 5, 12, 15 V specimen bias 0, -3, -5, -12, -15 V specimen bias On, 330, 1 kn, 3.3 km, 10 kn specimen loads + 20 V offset compensation Tnput impedance 100 kn maximum on all signal outputs 6. Pre-amplifier specifications dc to 2 MHz frequency response up to 52 dB gain FET fast recovery channel up to 40 dB gain channel 0 to 20 V specimen bias O to -20 V specimen bias On, 330 m, 1 kn, 3.3 km loads for specimen +12 V offset compensation at full gain setting (compensation range increases from this as gain is reduced) input impedance 3.3 km maximum 1. DiStefano, T. H., Photoemission and Photovoltaic Imaging of Semiconductor Surfaces, in Semiconductor Measurement Technology: ARPA/NBS Workshop IV. Surface Analysis for Silicon Devices, A. G. Lieberman, ed., NBS Special Publication 400-23 (March 1976) pp. 197-209. 2. Sawyer, D. E., and Berning, D. W., Laser Scanning of Active Semiconductor Devices, Technical Digest, 1975 International Electron Devices Meeting, Washington, D. C., December 1-3, 1975, pp. 111-114. 3. Sawyer, D. E., and Berning, D. W., Laser Scanning of MOS IC's Reveals Internal Logic States Nondestructively, Proc. IEEE 64, 393-394 March (1976). 4. Sawyer, D. E., and Berning, D. W., Mapping Nonlinearities Over the Active Regions of Semiconductor Devices, Proc. IEEE 64, 1635-1637 November (1976). 5. Sawyer, D. E., and Berning, D. W., Thermal Mapping of Transistors With a Laser Scanner, Proc. IEEE 64, 1634-1635 November (1976). 6. Sawyer, D. E., and Berning, D. W., Semiconductor Measurement Technology: Laser Scanning of Active Semiconductor Devices: Videotape Script, NBS Special Publication 400-27 (February 1976). 7. Beiser, L., Laser Beam Scan Enhancement through Periodic Aperture Transfer, Applied Optics 1, 647-650 (1968). 8. Langberg, E., Lincoln Laboratory, MIT, (private communication). The operation of a Scanner Employing the Refocusing Technique has been described by R. E. McMahon: Laser Tests IC's with light touch, Electronics 44, 92-95 (1971). 9. Potter, C. N., and Sawyer, D. E., A Flying-Spot Scanner, Rev. Sci. Instrum. 39, 180-183 (1968). 10. Levy, M. E., Imaging LSI Microcircuits with Optical Spot Scanners, Report No. P76-39, prepared for the National Aeronautics and Space Administration under Contract No. NA58-31239 by Hughes Aircraft Co., January 1976. APPENDIX A Commercial Equipment Used This section contains a list of the commercial equipment that was used to build the scanner. The equipment was selected with the aim that the scanner should be extremely versatile. 1. Microscope Equipment b. C. Binocular microscope suitable for use with polarized 12.5X eyepiece oculars. 4X (NA=0.1), 8X (NA=0.2), 16X (NA=0.35), and 40X (NA=0.6) d. 10X camera tube ocular. 2. Signal Generators b. c. Waveforms: Sine, square, and triangle, ramp, and sync Frequency: 0.005 Hz to 1 MHz. Output impedance: 600 or lower. 3. Lasers b. 0.633 μm, 3 mW cw HeNe, noise less than 2%. 0.633 μm, 5 mW cw HeNe, noise less than 2%, mirrors changed to cause it to operate at 1.15 μm. 4. Analyzer Rotatable polarizing optical component. 5. Half-Wave Plate Mica-between-glass type for 1.15 um radiation. 6. Monochromatic Display 7. a. Bandwidth: dc to 20 MHz on X, Y, and Z inputs. b. Digital dc blanking, blanked +5 V, unblanked -5 V. APPENDIX B Reimaging Lens System The reimaging lens system which is placed between the vertical and horizontal scanning mirrors must refocus the laser beam deflection from the vertical scanning mirror to a point on the horizontal scanning mirror. This is done so that this mirror can be made small for relatively fast scanning rates. As the laser radiation leaves the horizontal scanning mirror, it emerges as a beam deflected in both the vertical and horizontal directions. An additional requirement of the lens system is that the laser radiation impinging on the second scanning mirror must consist of parallel light rays. To satisfy these requirements two lenses back-to-back are used between the vertical and horizontal to form the composite lens system L1. The distance between the vertical deflection mirror and the first principal plane of the first lens is made equal to the focal length f1, and the distance between the first principal plane of the second Tens and the horizontal deflection mirror is made equal to f2, the focal length of the second lens. The separation between the second principal planes of the two lenses is set equal to f1 + f2. The characteristics of the lenses used were: APPENDIX C Mechanical Construction The scanner is designed to be compact, rugged and portable. All equipment required to operate the scanner in any of its services is easily contained on a 2 by 1 meter work bench. It was not found necessary to shock-mount the scanner, or choose a special location to ensure freedom from perturbing influences such as building vibration. The purpose of this appendix is to present enough information on the mechanical design and construction of the scanner so that others may also build scanners with these desirable attributes. A heavy-duty microscope stand serves as the mounting support for all the mechanical items. Most of the scanner components are attached to a rigid, reinforced frame bolted to the stand. With this construction, the entire apparatus tends to move in unison in response to outside mechanical influences, and this minimizes blurring of the scanner images by unwanted deflection of the laser spot on the scanned specimen. In the figures which follow, all dimensions are in millimeters and, unless noted otherwise, the construction material is aluminum. Figures C1 C8 are mechanical drawings of the scanner and the location of the items to be described subsequently can be inferred from the photos in figures C9 C17. Figure C1 shows the support frame. The vertical dimension indicated as 435 mm is tailored to the particular microscope used so that the axis of the horizontal scanning mirror is at the exit pupil point of the microscope camera tube. In general, the mounting holes will vary with the particular choice of the vendor selected to provide items such as lenses and galvanometer deflectors. These choices will also influence the dimensions shown for the mounting hardware in the following figures. Figure C2 shows the holder for the horizontal scanning galvanometer mirror. It is designed to allow rotation of the galvanometer around the axis of its mirror during alinement of the system. Figure C3 shows the holder for the two lenses making up the system described in the main text and in Appendix B. The clamps allow the center-to-center spacing of the lenses to be varied, and the oval holes allow the assembly to be moved for system alignment. Figure C4 shows the holder for the vertical scanning galvanometer mirror. Figure C5 shows the bracket in which is mounted the holder for mirror M1. Figure C6 is an assembly view of the moveable slide which changes the scanning service from one laser to the other. Two small, rectangular |