In-situ real-time monitoring technique and apparatus for endpoint detection of thin films during chemical/mechanical polishing planarization
First Claim
1. An apparatus for chemical mechanical polishing of a wafer, comprising:
- (a) a platen supporting a polishing surface;
(b) a chuck to hold the wafer against the polishing surface;
(c) a motor coupled to at least one of the polishing surface and the chuck to generate relative motion therebetween; and
(d) an endpoint detector, comprising (c1) a light source operable to generate a light beam that is directed through the polishing surface to the wafer and produce, from the light beam that is directed through the polishing surface, a light beam reflected from the wafer, and (c2) a receiver operable to receive the light beam reflected from the wafer, wherein the endpoint detector is operable to determine, based on the light beam reflected from the wafer, when an end point is reached.
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Abstract
A technique and apparatus is disclosed for the optical monitoring and measurement of a thin film (or small region on a surface) undergoing thickness and other changes while it is rotating. An optical signal is routed from the monitored area through the axis of rotation and decoupled from the monitored rotating area. The signal can then be analyzed to determine an endpoint to the planarization process. The invention utilizes interferometric and spectrophotometric optical measurement techniques for the in situ, real-time endpoint control of chemical-mechanical polishing planarization in the fabrication of semiconductor or various optical devices. The apparatus utilizes a bifurcated fiber optic cable to monitor changes on the surface of the thin film.
78 Citations
22 Claims
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1. An apparatus for chemical mechanical polishing of a wafer, comprising:
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(a) a platen supporting a polishing surface;
(b) a chuck to hold the wafer against the polishing surface;
(c) a motor coupled to at least one of the polishing surface and the chuck to generate relative motion therebetween; and
(d) an endpoint detector, comprising (c1) a light source operable to generate a light beam that is directed through the polishing surface to the wafer and produce, from the light beam that is directed through the polishing surface, a light beam reflected from the wafer, and (c2) a receiver operable to receive the light beam reflected from the wafer, wherein the endpoint detector is operable to determine, based on the light beam reflected from the wafer, when an end point is reached. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A chemical mechanical polisher, comprising:
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a polishing surface that is movable relative to a substrate;
at least one light source operable to transmit light through the polishing surface to a film on the substrate and produce, from the light that is transmitted through the polishing surface, light reflected from the film on the substrate; and
at least one device operable to detect a change in the light reflected from the film on the substrate and determine, based on the detected change, when an end point is reached. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A chemical mechanical polisher, comprising:
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a polishing material having at least one optical access through which light can be transmitted to a portion of a film on a substrate;
a platen to support the polishing material;
an interferometer operable to detect interferometric changes in light reflected from the film and passing through the optical access in the polishing material; and
a device operable to determine, based on the detected interferometric changes, when an end point is reached. - View Dependent Claims (20, 21, 22)
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Specification