Apparatus for measuring difference in shallow level

Details Apparatus for measuring difference in shallow level Apparatus for measuring difference in shallow level

1986-04-11

1988-05-17

Willis, Davis L.

Optics: measuring and testing

By dispersed light spectroscopy

Utilizing a spectrometer

350509, G01B 902

Patent

active

047446609

ABSTRACT:
An apparatus for measuring a difference in level in a sample comprises a light source section which provides illumination light of a variable-wavelength. The illumination light is irradiated onto the sample. A group of filters is provided for shielding diffraction light rays of O-order or other than O-order of the light reflected from the sample. The intensity of interference light of the light rays not shielded by the filter group is detected by a light detector which in turn converts it into an electric signal. An arithmetic operation unit receives the electric signal while the wavelength of the illumination light from the light source section is continuously varied. In the arithmetic unit, wavelengths at which the electric signal or detected light intensity takes extreme values are determined, and the level difference in the sample is determined on the basis of those wavelengths.

REFERENCES:
patent: 4030835 (1977-06-01), Firester et al.
patent: 4630926 (1986-12-01), Tanaka et al.
Roach et al., "Diffraction Spectrometry for Video Disc Quality Control" 9/1978, pp. 504-505.
Carter, "Measurement of Second-Order Coherence in a Light Beam Using a Microscope and a Grating", 3/1977, p. 558.
McCarthy et al., "Infrared Spatial Interferometry: Present Status and Future Plans", 1979, pp. 140 & 141.
Kleinknecht, "Optical Monitoring of the Etching of SiO.sub.2 and Si.sub.3 N.sub.4 on Si by the use of Grating Test Patterns", 5/1973.

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