Technique for determining the end point of an etching process
First Claim
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1. A method for detecting the end point of the etching of a pattern formed in a layer of material by etching through openings in an etch resistant coating on the surface of the material, the method comprising the steps of:
- simultaneously etching;
(1) the material, through the openings, and (2) a Fresnel zone plate, located proximate the pattern, comprised of a plurality of annular zones which are alternately formed of the etch resistant material and the exposed material to be etched;
monitoring light reflected from the Fresnel zone plate during etching; and
terminating the etch process when the intensity of light reflected from the Fresnel zone plate falls below a predetermined level.
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Abstract
A method for detecting the end point of the plasma etching of a pattern (36) in an aluminum layer (33) on a silicon wafer (16). The pattern (36) and portions of a Fresnel zone plate (30) are simultaneously etched in the aluminum layer (33). The intensity of the light reflected from the Fresnel zone plate (30) during plasma etching is monitored and the etching process terminated when the intensity falls below a predetermined level.
36 Citations
14 Claims
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1. A method for detecting the end point of the etching of a pattern formed in a layer of material by etching through openings in an etch resistant coating on the surface of the material, the method comprising the steps of:
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simultaneously etching;
(1) the material, through the openings, and (2) a Fresnel zone plate, located proximate the pattern, comprised of a plurality of annular zones which are alternately formed of the etch resistant material and the exposed material to be etched;monitoring light reflected from the Fresnel zone plate during etching; and terminating the etch process when the intensity of light reflected from the Fresnel zone plate falls below a predetermined level. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for detecting the end point of the etching of a pattern in an aluminum layer that coats a P-glass layer on a semiconductor substrate, the pattern being etched through openings in a photoresist coating on the aluminum layer, comprising the steps of:
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simultaneously plasma etching;
(1) the pattern, and (2) a Fresnel zone plate comprised of a plurality of annular zones which are alternately formed of the photoresist and exposed portions of the aluminum layer;monitoring light reflected from the Fresnel zone plate during plasma etching; and terminating the plasma etching process when the intensity of the light reflected from the Fresnel zone plate falls below a predetermined level. - View Dependent Claims (12, 13, 14)
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Specification