Measuring method and system using a diffraction pattern

Details Measuring method and system using a diffraction pattern Measuring method and system using a diffraction pattern

1974-01-25

1976-05-18

Corbin, John K.

Optics: measuring and testing

Refraction testing

Prism engaging specimen

250550, 356109, 356159, G01B 902

Patent

active

039573761

ABSTRACT:
A spot of collimated monochromatic radiation is applied to a semiconductor wafer to obtain a diffraction pattern from two edges within an area, which is the size of the spot, on the wafer. The diffraction pattern is reflected to a photodiode array wherein the light intensity of the diffraction pattern at each of a plurality of positions is obtained. Each of the photodiodes is scanned separately for the same period of time to determine the light intensity at its location. The distance between the zero intensity positions on the photodiode array is determined very precisely and utilized with the wavelength of a laser, which supplies the spot of collimated monochromatic radiation, and the effective focal length of the lens system, which images the diffraction pattern to the photodiode array, to calculate the linear distance between the edges.

REFERENCES:
patent: 3518007 (1970-06-01), Ito
patent: 3664239 (1972-05-01), Pryor
patent: 3709610 (1973-01-01), Kruegle
patent: 3764216 (1973-10-01), Bliek et al.
patent: 3797939 (1974-04-01), Pryor
watkins et al., "Dynamic Wire Measurements by New Inspection Techniques," JASA, Vol. 46, No. 2, pp. 314-315, Aug. 1969.
Watkins et al., "Dynamic Wire Measurements. . .," IEEE J. of Quant. Elec., Vol. QE6, No. 1, p. 2, Jan. 1970.
Computer Design, Vol. 12, No. 6, p. 50, June 1973.

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