EP0455455A2
Expired / Lapsed
EP
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In situ monitoring technique and apparatus for chemical/mechanical planarization endpoint detection
Assignee: AT&T Inc
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Filing: 1991-04-29
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Granted: —
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Expires: 2011-04-29
Abstract
Abstract This invention provides an in situ monitoring technique and apparatus (20) for chemical/mechanical planarization end point detectionin the process of fabricating semiconductor or optical devices. Fabrication of semiconductor or optical devices often requires smooth planar surfaces, either on the surface of a wafer (2) being processed or at some intermediate stage e.g. a surface of an interleaved layer. The detection in the present invention is accomplished by means of capacitively measuring the thickness of a dielectric layer (4) on a conductive substrate. The measurement involves the dielectric layer (4), a flat electrode structure (25) and a liquid (20) interfacing the article and the electrode structure. Polishing slurry acts as the interfacing liquid. The electrode structure includes a measuring electrode (26), an insulator surrounding the measuring electrode (28,29), a guard electrode (27) and another insulator surrounding the guard electrode. In the measurement a drive voltage is supplied to the measuring electrode, and in a bootstrap arrangement to a surrounding guard electrode, thereby measuring the capacitance of the dielectric layer of interest without interfering effect from shunt leakage resistance. The process and apparatus are useful not only for measuring the thickness of dielectric layers on conductive substrates in situ, during planarizing polishing, but also for measuring the dielectric thickness on substrates in other processes, e.g. measuring the dielectric layer thickness prior to or after an etching process.
Inventors
- 👤 Gabriel Lorimer Miller
- 👤 Eric Richard Wagner
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 21:40
CPC Classifications
B; B24; B24B; B24B37/00; B24B37/005; B24B37/013; H; H10; H10P; H10P52/00; G; G01; G01B; G01B7/00; G01B7/02; G01B7/06; G01B7/08; G01B7/085; G01B7/34; G01B7/345
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
96 words
A process for in situ monitoring the thickness of a dielectric material on a surface of an electrically conductive substrate having less than about one megohm-cm resistivity, characterised by placing the substrate so that a surface of an electrode structure faces the dielectric material, interposing between the substrate and the surface of the electrode structure a film of a conductive liquid with resistivity of less than about 100,000 ohm-cm, said film being in contact with the dielectric material and the surface of the electrode structure, and measuring the capacitance between the substrate and the electrode structure.
Claim 2
Dependent Claim
26 words
The process of claim 1 or 14, wherein said measuring includes measuring the capacitance and simultaneously removing from the result the effects of leakage resistance paths.
Claim 3
Dependent Claim
61 words
The process of claim 1, 2, or 14, wherein the capacitive measurement comprises applying a measuring voltage to a measuring electrode of the electrode structure and a bootstrapping guard voltage to a narrow conductive area surrounding the measuring electrode, said measuring electrode and said narrow conductive area being insulated each from another, with or without another insulator surrounding the guard electrode.
Claim 4
Dependent Claim
36 words
The process of claim 3 or 14, wherein said measuring comprises maintaining constant displacement current resulting from said voltage application, the amplitude of the drive voltage thereby being proportional to the thickness of the dielectric layer.
Claim 5
Dependent Claim
74 words
The process of any one of claims 1 to 4, or 14, wherein said conductive material comprises a material selected from silicon, germanium, group III-V compound semiconductors, group II-VI compound semiconductors, and/or the dielectric material comprises a material selected from silicon oxide, silicon nitride, oxynitride, a chemical vapor deposited silicon oxide, plasma enhanced chemical vapor deposited oxide and spin-on glass, the monitoring being conducted in the planarizing of the dielectric on the conductive substrate.
Claim 6
Dependent Claim
141 words
Apparatus for monitoring the thickness of a dielectric layer (4) on a surface (5) of a workpice (2) during polishing with a polishing medium (20), said workpiece having resistivity of less than about one megohm-cm, said apparatus characterised by at least one electrode structure (25) having a flat surface for facing the workpiece to be polished, said electrode structure comprising a conductive measuring electrode (26), an insulator (22) surrounding the measuring electrode, a conductive guard electrode (27) surrounding the insulator and being separated by the insulator from the measuring electrode, means (13) for providing the polishing medium as a conductive liquid medium such that the said face of the workpiece and said surface of the electrode structure interface through the liquid medium, and means (Fig. 9) for measuring the capacitance between the conductive portion of the workpiece and the electrode structure.
Claim 7
Dependent Claim
43 words
The apparatus of claim 6, or 15 wherein the measuring means comprises means (35) for supplying drive voltage to the measuring electrode and in a bootstrap arrangement (32,40) to the guard electrode (27) thereby measuring the capacitance of the dielectric layer undergoing polishing.
Claim 8
Dependent Claim
50 words
The process of claim 5 or 14, or the apparatus of claim 6, or 15 wherein two equal electrode structures are arranged side by side, said measuring voltage is applied to one electrode structure at 180° out of phase to the measuring voltage being applied to the other electrode structure.
Claim 9
Dependent Claim
37 words
The process of claim 3 or 14, or the apparatus of claim 6 or 7 or 15, wherein said measuring voltage is an alternating voltage with an operating frequency up to 5000 Hz, or about 500 Hz.
Claim 10
Dependent Claim
60 words
The apparatus of claim 6, 7 or 9, or 15 wherein said measuring means comprises an electronic system for supplying drive voltage to said measuring electrode and in a bootstrap arrangement to the guard electrode, and for maintaining constant displacement current so that the resulting magnitude of the drive voltage is automatically proportional to the thickness of the dielectric layer.
Claim 11
Dependent Claim
67 words
The apparatus of claim 10 or 15, wherein the apparatus comprises a polishing table (11), a polishing pad (13) on said table, and a movable wafer carrier (12) suspended above the polishing table for bringing the workpiece into contact with said polishing pad, the apparatus having the option that the electrode structure can be imbedded into the polishing table in the same plane as the polishing table.
Claim 12
Dependent Claim
64 words
The apparatus of claim 11 or 15, wherein the polishing pad is secured to the polishing table by an adhesive plastic coating, and in which said plastic coating is provided with apertures permitting the liquid medium to make an electrically conductive path to the flat surface of the electrode structure, or the polishing pad is secured to the polishing table by a conductive adhesive.
Claim 13
Dependent Claim
67 words
The apparatus of claim 12, or 15 wherein the polishing table is of conductive material selected from stainless steel, aluminum and cermets, or of metals such as aluminum, chromium or titanium deposited in suitable patterns on insulating materials, or is of non-conducting material which is non-contaminating with respect to the material of the workpiece, the nonconducting arterial being selected from quartz, ceramic, glass, plastic, and insulator-coated metals.
Claim 14
Dependent Claim
125 words
A process of fabricating a device, which comprises fabricating a device structure on a substrate so as to yield a non-planar surface, said substrate having resistivity of less than about one megohm-cm, forming a layer of dielectric material over the non-planar surface, reducing the thickness of said dielectric layer progressively, monitoring the remaining thickness so as to determine a desired end-point of the reduction, and continue fabrication of said device, characterised in that said end-point is determined by measuring the capacitance between the substrate and an electrode structure facing the substrate while the face of the substrate and the surface of the electrode structure facing the substrate are interfaced by a continuous conductive film of a liquid with resistivity of less than about 100,000 ohm-cm.
Claim 15
Independent Claim
108 words
An apparatus for measuring the thickness of a dielectric region on a lateral face of article having a conductive portion with resistivity of less than about one megohm-cm and dielectric material on a lateral face of the conductive portion, which comprises, an electrode structure having a flat surface, the dielectric layer on said article facing the said flat surface, conductive liquid means for interfacing the conductive article and the flat surface of the electrode structure and for establishing an electrical connection between the conductive article and said flat surface of the electrode structure, and means for measuring the capacitance between the conductive article and the measuring electrode structure.
References Cited (Backward Citations)
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