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 monitoring thickness change in a film on a substrate comprising(i) a bifurcated fiber-optic cable having a common leg and two bifurcated legs,(ii) a rotating fiber-optic cable with two ends,(iii) a light source,(iv) means for analyzing a light signal to determine thickness change and stopping thickness change when the thickness reaches a predetermined endpoint, and(v) a rotating coupler having a stationary end and a rotating end,wherein the first bifurcated leg of the bifurcated fiber-optic cable is connected to the light source, the second bifurcated leg is connected to the means for analyzing a light signal, and the common leg is connected to the stationary end of the rotating coupler,and wherein one end of the rotating fiber-optic cable is connected to the rotating end of the rotating coupler and the other end is held in close proximity to the substrate.
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Accused Products
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.
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Citations
100 Claims
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1. An apparatus for monitoring thickness change in a film on a substrate comprising
(i) a bifurcated fiber-optic cable having a common leg and two bifurcated legs, (ii) a rotating fiber-optic cable with two ends, (iii) a light source, (iv) means for analyzing a light signal to determine thickness change and stopping thickness change when the thickness reaches a predetermined endpoint, and (v) a rotating coupler having a stationary end and a rotating end, wherein the first bifurcated leg of the bifurcated fiber-optic cable is connected to the light source, the second bifurcated leg is connected to the means for analyzing a light signal, and the common leg is connected to the stationary end of the rotating coupler, and wherein one end of the rotating fiber-optic cable is connected to the rotating end of the rotating coupler and the other end is held in close proximity to the substrate.
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3. In a chemical mechanical polishing device for planarizing a film on a substrate, the improvement comprising
(i) a bifurcated fiber-optic cable having a common leg and two bifurcated legs, (ii) a rotating fiber-optic cable with two ends, (iii) a light source, (iv) means for analyzing a light signal to determine thickness and stopping thickness change when the thickness reaches a predetermined endpoint, and (v) a rotating coupler having a stationary end and a rotating end, wherein the first bifurcated leg of the bifurcated fiber-optic cable is connected to the light source, the second bifurcated leg is connected to the means for analyzing a light signal, and the common leg is connected to the stationary end of the rotating coupler, and wherein one end of the rotating fiber-optic cable is connected to the rotating end of the rotating coupler and the other end is held in close proximity to the substrate undergoing chemical mechanical polishing.
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5. In a chemical mechanical polishing device for planarizing a film on a substrate, the improvement comprising
(i) a bifurcated fiber-optic cable having a common leg and two bifurcated legs, (ii) a rotating fiber-optic cable with two ends, (iii) a light source, (iv) means for analyzing a light signal based on interferometry or spectrophotometry, and (v) a rotating coupler having a stationary end and a rotating end, wherein the first bifurcated leg of the bifurcated fiber-optic cable is connected to the light source, the second bifurcated leg is connected to the means for analyzing a light signal, and the common leg is connected to the stationary end of the rotating coupler, and wherein one end of the rotating fiber-optic cable is connected to the rotating end of the rotating coupler and the other end is held in close proximity to either side of the substrate undergoing chemical mechanical polishing to illuminate a section of the film.
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7. In a chemical mechanical polishing device for planarizing a film on a substrate comprising a polishing table, the improvement comprising
(i) a bifurcated fiber-optic cable having a common leg and two bifurcated legs, (ii) a rotating fiber-optic cable with two ends, (iii) a light source, (iv) means for analyzing a light signal to determine thickness and stopping thickness change when the thickness reaches a predetermined endpoint, and (v) a rotating coupler having a stationary end and a rotating end, wherein the first bifurcated leg of the bifurcated fiber-optic cable is connected to the light source, the second bifurcated leg is connected to the means for analyzing a light signal, and the common leg is connected to the stationary end of the rotating coupler, and wherein one end of the rotating fiber-optic cable is connected to the rotating end of the rotating coupler and the other end is held in close proximity to a side of the substrate undergoing chemical mechanical polishing, said other end illuminating a section of the film of the substrate and said analyzing means measuring a light signal returning from the section.
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12. In a chemical mechanical polishing device for planarizing a film on a substrate, the improvement comprising
(i) a bifurcated fiber-optic cable having a common leg and two bifurcated legs, (ii) a rotating fiber-optic cable with two ends, (iii) a light source, (iv) means for analyzing a light signal to determine thickness and stopping thickness chance when the thickness reaches a predetermined endpoint, and (v) a rotating coupler having a stationary end and a rotating end, wherein the first bifurcated leg of the bifurcated fiber-optic cable is connected to the light source, the second bifurcated leg is connected to the means for analyzing a light signal, and the common leg is connected to the stationary end of the rotating coupler, and wherein one end of the rotating fiber-optic cable is connected to the rotating end of the rotating coupler and the other end is held in close proximity to a side of the substrate which is not undergoing chemical mechanical polishing, said other end illuminating a section of the film of the substrate and said analyzing means measuring a light signal returning from the section.
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15. In a chemical mechanical polishing device for planarizing a film on a substrate comprising a polishing table, the improvement comprising
(i) a bifurcated fiber-optic cable having a common leg and two bifurcated legs, (ii) an electrical slipring, (iii) a light source, and (iv) means for analyzing a light signal, wherein the first bifurcated leg of the bifurcated fiber-optic cable is connected to the light source, the second bifurcated leg is connected to the means for analyzing a light signal, and the common leg is connected at one end to the electrical slipring, and wherein another end of the common leg of the fiber-optic cable is held in close proximity to a side of the substrate undergoing chemical mechanical polishing, said end illuminating a section of the film of the substrate and said analyzing means analyzing a light signal returning from the section based on interferometry or spectrophotometry.
- 20. A chemical mechanical polisher for planarizing a film on a substrate comprising at least one light source that illuminates at least one section of the film on the substrate to create at least one reflected light signal received by a photodetector positioned in close proximity to the reflected light signal, which converts the reflected light signal into an electrical signal and transmits the electrical signal to an electrical slip ring, said electrical slip ring uncoupling the electrical signal from rotation and being operably connected to an analyzer that analyzes the electrical signal to monitor the progress of planarization.
- 24. An apparatus for monitoring thickness change in a film on one side of a substrate having two sides comprising a light source that illuminates a section of the film on one side of the substrate to create a reflected light signal and a decoupler which decouples the reflected light signal from rotation, said decoupler being operably connected to means for monitoring thickness change based on the reflected light signal.
- 29. An apparatus for monitoring thickness change in a film on one side of a substrate having two sides, said apparatus comprising at least one light source that illuminates at least one section of the film on the substrate to create at least one reflected light signal that is received by at least one decoupler that decouples the reflected light signal from rotation and transmits the reflected signal to at least one device that monitors thickness change based on the reflected light signal.
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37. An apparatus for chemical mechanical polishing of a wafer, comprising
(a) a rotatable polishing platen with an overlying polishing pad wetted with an abrasive slurry; -
(b) a rotatable chuck for holding the wafer against the polishing pad, the wafer comprising a semiconductor substrate underlying an oxide layer; and (c) an endpoint detector, comprising (c1) a laser interferometer capable of generating a laser beam directed towards the wafer and detecting light reflected from the wafer, and (c2) a hole formed through the platen and polishing pad allowing the laser beam to reflect off a section of the wafer when the hole is positioned over said section of the wafer. - View Dependent Claims (38, 39)
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40. A chemical mechanical polisher for polishing a film over a substrate comprising
at least one light source capable of transmitting light through a rotatable polishing pad to the film; and at least one device that detects interferometric change in reflected light generated when light is transmitted through the polishing pad to the film. - View Dependent Claims (41, 42, 43, 44, 45, 46, 47, 48, 49, 50)
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51. A method of processing a film comprising
polishing the film with a rotating polishing pad; -
illuminating at least one section of the film with light transmitted through the rotating polishing pad during polishing of said at least one section; and detecting interferometric change in light reflected from the at least one illuminated section of the film. - View Dependent Claims (52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72)
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73. A method of making a planarized substrate comprising
polishing a film over a substrate with a rotating polishing pad; -
illuminating at least one section of the film with light transmitted through the rotating polishing pad during polishing of said at least one section; and detecting interferometric change in light reflected from the at least one illuminated section of the film. - View Dependent Claims (74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95)
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- 96. In a chemical mechanical polisher for polishing a film over a substrate, the improvement comprising a polishing pad having at least one optical access through which light can be transmitted to a portion of the film on the substrate for the purpose of detecting interferometric change in reflected light generated when light is transmitted through the polishing pad to the at least one portion of the film.
Specification