Abstract

In examination of ir-transmitting materials, internal irregularities and inclusions of foreign material can be detected by their effect upon the ir transmittance of the material. A scanning laser ir microscope has been constructed which produces, on an oscilloscope display, a shadowgraph picture of the ir transmittance of the material under examination. The 3.39-μ emission of a He–Ne laser serves conveniently as the ir source since many materials of interest transmit at this wavelength. The scan consists of a raster of 400 lines, and is completed in 1 sec. The detector is a room temperature operated indium arsenide photovoltaic cell, with a time constant of 2 μsec. A sample area of 1.2 cm × 1.2 cm is scanned with a focused spot having a nominal diameter of approximately 0.003 cm. The optical and electromechanical features of the microscope are described, and its application to examination of semiconductor materials is illustrated by several typical examples.

© 1970 Optical Society of America

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References

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  1. F. Roberts, J. Young, Proc. IEEE 99, 747 (1952).
  2. “Optical Scanning Techniques for Semiconductor Device Screening and Identification of Surface and Junction Phenomenae,” C. Potter, D. Sawyer, 1966 Annual Symposium on Physics of Failure in Electronics, Columbus, Ohio.
  3. Philco Corp., Microelectronics Div., Spring City, Pa., 19457. Detector model number: IAU-606.
  4. Bulova Watch Co., American Time Products Div., Woodside, N. Y. 11377. Scanner model number: L-44.
  5. Applied Cybernetics Systems, Inc., Silver Spring, Nd. 20910. Preamplifier model number: 4UA.
  6. W. G. Spitzer, J. M. Whelan, Phys. Rev. 114, 59 (1959).
    [CrossRef]
  7. W. Spitzer, H. Y. Fan, Phys. Rev. 108, 268 (1957).
    [CrossRef]
  8. C. E. Jones, A. R. Hilton, J. Electrochem. Soc. 113, 504 (1966).
    [CrossRef]

1966 (1)

C. E. Jones, A. R. Hilton, J. Electrochem. Soc. 113, 504 (1966).
[CrossRef]

1959 (1)

W. G. Spitzer, J. M. Whelan, Phys. Rev. 114, 59 (1959).
[CrossRef]

1957 (1)

W. Spitzer, H. Y. Fan, Phys. Rev. 108, 268 (1957).
[CrossRef]

1952 (1)

F. Roberts, J. Young, Proc. IEEE 99, 747 (1952).

Fan, H. Y.

W. Spitzer, H. Y. Fan, Phys. Rev. 108, 268 (1957).
[CrossRef]

Hilton, A. R.

C. E. Jones, A. R. Hilton, J. Electrochem. Soc. 113, 504 (1966).
[CrossRef]

Jones, C. E.

C. E. Jones, A. R. Hilton, J. Electrochem. Soc. 113, 504 (1966).
[CrossRef]

Potter, C.

“Optical Scanning Techniques for Semiconductor Device Screening and Identification of Surface and Junction Phenomenae,” C. Potter, D. Sawyer, 1966 Annual Symposium on Physics of Failure in Electronics, Columbus, Ohio.

Roberts, F.

F. Roberts, J. Young, Proc. IEEE 99, 747 (1952).

Sawyer, D.

“Optical Scanning Techniques for Semiconductor Device Screening and Identification of Surface and Junction Phenomenae,” C. Potter, D. Sawyer, 1966 Annual Symposium on Physics of Failure in Electronics, Columbus, Ohio.

Spitzer, W.

W. Spitzer, H. Y. Fan, Phys. Rev. 108, 268 (1957).
[CrossRef]

Spitzer, W. G.

W. G. Spitzer, J. M. Whelan, Phys. Rev. 114, 59 (1959).
[CrossRef]

Whelan, J. M.

W. G. Spitzer, J. M. Whelan, Phys. Rev. 114, 59 (1959).
[CrossRef]

Young, J.

F. Roberts, J. Young, Proc. IEEE 99, 747 (1952).

J. Electrochem. Soc. (1)

C. E. Jones, A. R. Hilton, J. Electrochem. Soc. 113, 504 (1966).
[CrossRef]

Phys. Rev. (2)

W. G. Spitzer, J. M. Whelan, Phys. Rev. 114, 59 (1959).
[CrossRef]

W. Spitzer, H. Y. Fan, Phys. Rev. 108, 268 (1957).
[CrossRef]

Proc. IEEE (1)

F. Roberts, J. Young, Proc. IEEE 99, 747 (1952).

Other (4)

“Optical Scanning Techniques for Semiconductor Device Screening and Identification of Surface and Junction Phenomenae,” C. Potter, D. Sawyer, 1966 Annual Symposium on Physics of Failure in Electronics, Columbus, Ohio.

Philco Corp., Microelectronics Div., Spring City, Pa., 19457. Detector model number: IAU-606.

Bulova Watch Co., American Time Products Div., Woodside, N. Y. 11377. Scanner model number: L-44.

Applied Cybernetics Systems, Inc., Silver Spring, Nd. 20910. Preamplifier model number: 4UA.

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Figures (10)

Fig. 1
Fig. 1

Ray diagram—focused radiation beam passing through transparent material.

Fig. 2
Fig. 2

Optical-mechanical schematic diagram of scanned laser ir microscope.

Fig. 3
Fig. 3

Electrical schematic diagram, scanned ir microscope.

Fig. 4
Fig. 4

Infrared transmission images of Sn-doped GaAs (a) image recorded on an ir-sensitive photographic plate: arrows indicate inclusions of Sn–As phase; (b) image recorded with the 3.39-μ laser microscope. The area of the sample shown is fixed by a 1 cm × 1 cm opening in the sample mount.

Fig. 5
Fig. 5

Infrared transmission images of Si-doped (pulled crystal) GaAs: (a) image recorded on an ir sensitive plate; (b) 3.39-μ image. Area seen is 1 cm × 1 cm.

Fig. 6
Fig. 6

Photomicrographs of Cr-doped GaAs: (a) visible image by reflected light; (b) image recorded on ir-sensitive plate; (c) 3.39-μ image: Small triangular shaped areas are Cr–As inclusions.

Fig. 7
Fig. 7

Infrared transmission image of a silicon IC array: (a) 3.39-μ laser microscope image; (b) image recorded on ir plate. Matching regions in each image are circled.

Fig. 8
Fig. 8

Infrared transmission images of the same kind of silicon IC array shown in Fig. 7 but displaying a different transmission image at 3.39 μ: (a) 3.39-μ image; (b) image on ir plate.

Fig. 9
Fig. 9

Laser microscope image of a wafer cut from GaSb–InSb mixed crystal.

Fig. 10
Fig. 10

Laser microscope images of 0.00025 in. (0.000635 cm) deep As-diffused array in a wafer of germanium: (a) before antireflection coatings; (b) after quarter-wavelength antireflection films of ZnS were applied to front and back surface.

Tables (1)

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Table I Optical Parameters and Best Resolution for Various Sample Thicknesses in the Scanned Laser Infrared Microscope, Without Refocusing

Equations (3)

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D b = 2.44 ( λ / n ) ( A ) ,
D g = ( t / 2 ) ( 1 / 2 n A ) ,
T = ( 1 R ) 2 c a x / 1 R 2 e 2 a x ,

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