US5838448A
Expired / Lapsed
US
⏱️ 0.0 years remaining
CMP variable angle in situ sensor
Assignee: Nikon Corp
•
Filing: 1997-03-11
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Granted: 1998-11-17
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Expires: 2017-03-11
Abstract
Abstract A chemical-mechanical polishing (CMP) optical process monitor apparatus allows in situ measurement of the thickness of a thin film being polished. As the incidence angle of the incident light on the wafer being polished is changed, the reflected intensity of the light from the thin film on the wafer undergoes a variation in local maxima and minima. The angle at which the light intensity is a maximum or minimum determined by the thin film interference equation, thus providing a measurement of the thin film thickness and/or the change in the thin film thickness.
Inventors
- 👤 Arun A. Aiyer
- 👤 Paul Derek Coon
- 👤 Henry K. Chau
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 11:38
CPC Classifications
G; G01; G01B; G01B11/00; G01B11/02; G01B11/06; G01B11/0616; G01B11/0683
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
85 words
A method of measuring a thickness or thickness change of a film formed on a principal surface of a substrate, comprising the steps of: illuminating the substrate and film; detecting a total intensity of the illumination reflected from the substrate and film; measuring the total reflected illumination intensity at each of a plurality of incidence angles, and determining an incidence angle at which the total reflected illumination intensity is at a minimum or maximum, thereby to determine the thickness or thickness change of the film.
Claim 2
Independent Claim
85 words
A method of measuring a thickness or thickness change of a film formed on a principal surface of a substrate, comprising the steps of: illuminating the substrate and film; detecting a total intensity of the illumination reflected from the substrate and film; measuring the total reflected illumination intensity at each of a plurality of incidence angles, and determining an incidence angle at which the total reflected illumination intensity is at a minimum or maximum, thereby to determine the thickness or thickness change of the film.
Claim 3
Dependent Claim
29 words
The method of claim 1, wherein the illumination is initially incident on a backside surface of the substrate, the film being formed on an opposing surface of the substrate.
Claim 4
Dependent Claim
24 words
The method of claim 2, wherein the substrate is supported on a polishing pad and the illumination does not pass through the polishing pad.
Claim 5
Dependent Claim
26 words
The method of claim 1, wherein the illumination is initially incident on a surface of the film and then passes through the film to the substrate.
Claim 6
Dependent Claim
26 words
The method of claim 1, wherein the illumination is initially incident on a surface of the substrate and then passes through the substrate to the film.
Claim 7
Dependent Claim
40 words
The method of claim 1, wherein a change of the film thickness detected by: measuring a relative thickness of the film; reducing the thickness of the film; and measuring the relative thickness of the film after the step of reducing.
Claim 8
Dependent Claim
14 words
The method of claim 6, wherein the step of reducing includes chemical mechanical polishing.
Claim 9
Dependent Claim
20 words
The method of claim 1, wherein the minimum or maximum is for a particular fringe order of the reflected illumination.
Claim 10
Dependent Claim
13 words
The method of claim 1, wherein the substrate is a crystalline silicon wafer.
Claim 11
Dependent Claim
19 words
The method of claim 1, wherein a wavelength of the illumination is equal to or greater than 1.1 μm.
Claim 12
Dependent Claim
34 words
The method of claim 1, further comprising the steps of placing the surface of the substrate on which the film is formed on a polishing pad prior to the steps of illuminating and detecting.
Claim 13
Dependent Claim
32 words
The method of claim 1, wherein in the step of measuring, the plurality of incidence angles is between a local minimum and a local maximum of a reflectance curve of the film.
Claim 14
Dependent Claim
19 words
The method of claim 1, wherein the minimum and maximum are respectively a local minimum and a local maximum.
Claim 15
Independent Claim
75 words
An apparatus for measuring a thickness or thickness change of a film formed on a principal surface of a transparent substrate, comprising: a polishing pad for supporting the substrate, the film resting on the polishing pad; a source of illumination located to illuminate the film and the substrate; and a detector located to detect a total intensity of illumination reflected from the film and the substrate, at each of a plurality of angles of reflection.
Claim 16
Independent Claim
75 words
An apparatus for measuring a thickness or thickness change of a film formed on a principal surface of a transparent substrate, comprising: a polishing pad for supporting the substrate, the film resting on the polishing pad; a source of illumination located to illuminate the film and the substrate; and a detector located to detect a total intensity of illumination reflected from the film and the substrate, at each of a plurality of angles of reflection.
Claim 17
Dependent Claim
31 words
The apparatus of claim 14, wherein the source of illumination is located to initially illuminate a backside surface of the substrate, the film being on an opposing surface of the substrate.
Claim 18
Dependent Claim
15 words
The apparatus of claim 15, wherein the illumination does not pass through the polishing pad.
Claim 19
Dependent Claim
32 words
The apparatus of claim 14, wherein the source of visible illumination is located to initially illuminate a surface of the film and the illumination then passes through the film to the substrate.
Claim 20
Dependent Claim
18 words
The apparatus of claim 14, wherein the detector includes means for determining an absolute thickness of the film.
Claim 21
Dependent Claim
22 words
The apparatus of claim 14, wherein the detector include means for determining a change in a thickness of the film over time.
Claim 22
Dependent Claim
20 words
The apparatus of claim 14, wherein the maximum or minimum is for a particular fringe order of the reflected illumination.
Claim 23
Dependent Claim
22 words
The apparatus of claim 14, wherein a wavelength of the illumination from the source is equal to or greater than 1.1 μm.
Claim 24
Dependent Claim
20 words
The apparatus of claim 14, wherein a wavelength of the illumination from the source is in the visible light spectrum.
Claim 25
Dependent Claim
26 words
The apparatus of claim 14, wherein the plurality of angles are between a local minimum and a local maximum of a reflectance curve of the film.
Claim 26
Dependent Claim
30 words
The apparatus of claim 14, further comprising a carrier for holding the substrate, wherein the carrier defines passages for the illumination illuminating and reflected from the film and the substrate.
Claim 27
Dependent Claim
13 words
The apparatus of claim 24, wherein an optical fiber extends through each passage.
Claim 28
Dependent Claim
19 words
The apparatus of claim 14, wherein the minimum and maximum and respectively a local minimum and a local maximum.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-11-16 | 2002-05-18 | 2002-11-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-11-16 | 2006-05-18 | 2006-11-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-11-16 | 2010-05-18 | 2010-11-17 | $7700.00 | Window Closed / Lapsed |