Optically testing the lateral dimensions of a pattern
AssigneeRCA Corporation
InventorsHans P. Kleinknecht, Wolfram A. Bosenberg
Life of this patent
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Abstract
A method of optically testing the lateral dimensions of a pattern of material disposed on a substrate comprises applying the material to both the main area of the substrate and a test area on the same substrate, and selectively removing the material from both areas on the substrate simultaneously to form respectively the pattern on the main area and a diffraction grating on the test area. The diffraction grating is exposed to a beam of light, and the intensity of two of the diffracted beams is measured to obtain a ratio signal (I.sub.2 /I.sub.1), which is then utilized to determine the lateral dimensional tolerance of the integrated circuit pattern.
Claims17
Apparatus for optically testing the lateral dimensions of a diffraction grating pattern of material disposed on a substrate, said diffraction pattern comprised of a planar array of spaced strips of material having a strip width w and periodicity d, comprising:
- means for exposing said diffraction pattern to a beam of monochromatic light to diffract said beam into diffracted beams of various orders;
- detector means including detectors for measuring the intensity of two of the diffracted beams to obtain two intensity signals (I.sub.1 and I.sub.2) and means responsive to said intensity signals for determining the width w of said strips.
Apparatus for optically testing the lateral dimensions of a pattern of material disposed on a substrate comprising:
- means for applying said material to both said substrate and a test surface;
- means for selectively removing said material from both said substrate and said test surface simultaneously to form, respectively, said pattern on said substrate and a diffraction grating on said test surface including spaced strips of said material having a strip width W and a periodicity d;
- means for exposing said diffraction grating to a beam of monochromatic light, whereby said diffraction grating and said test surface therebeneath function as a relief pattern, diffracting said beam of monochromatic light into diffracted beams of various orders;
- means for measuring the intensity of two of the diffracted beams (I.sub.1 and I.sub.2) to obtain two intensity signals;
- means for transmitting said intensity signals (I.sub.1 and I.sub.2) to processing means for determining the strip width W;
- and
- comparing said strip width W with a pre-established value to obtain a difference signal, whereby the magnitude of said difference signal is a measure for the lateral dimensional tolerance of said pattern.
Dependencies are inferred from the claim text.