US5953115A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for imaging surface topography of a wafer
Assignee: International Business Machines Corp
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Filing: 1997-10-28
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Granted: 1999-09-14
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Expires: 2017-10-28
Abstract
Abstract A method for imaging surface topography is based on Total Internal Reflection (TIR) and is particularly useful for imaging surface topography of wafers used in the manufacture of integrated circuits. This surface topography includes scratches, which are more localized, and dishing, which is a gentle dip over a larger area. In practice, a wafer is placed with the surface of interest in close contact with a prism or other internal reflection element (IRE). Light of suitable wavelength is incident at a suitable incident angle through the IRE of suitable refractive index in order to allow total internal reflectance at the surface of the IRE in close contact with the wafer surface. The reflected beam is then imaged to give a map of the location and dimensions, and some information on the depth, of the various surface features on the wafer.
Inventors
- 👤 William Francis Landers
- 👤 Jyothi Singh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 14:41
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/55; G01N21/552
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
204 words
A method for detecting and imaging irregularities in a flat, polished surface on an object, wherein the object has an index of refraction n O , the flat polished surface has an index of refraction n S , and air has an index of refraction n air and wherein the irregularities are indentations into the flat polished surface, the method comprising: A. providing a transparent base having an optically flat surface, an incident surface, an exit surface, and an index of refraction n b ; B. contacting the flat polished surface of the object to the optically flat surface of the transparent base to form an interface comprising an air/transparent base interface section at the irregularities; C. directing a beam of radiation, having a spectral band width with a central wavelength, through the incident surface of the transparent base onto the interface at an angle θ which is greater than a critical angle defined by the relationship of n b and n air , to produce totally internally reflected radiation at the air/transparent base interface section at the irregularities which passes through the exit surface of the transparent base; and D. detecting and converting the reflected radiation into a visible image of the irregularities.
Claim 2
Independent Claim
204 words
A method for detecting and imaging irregularities in a flat, polished surface on an object, wherein the object has an index of refraction n O , the flat polished surface has an index of refraction n S , and air has an index of refraction n air and wherein the irregularities are indentations into the flat polished surface, the method comprising: A. providing a transparent base having an optically flat surface, an incident surface, an exit surface, and an index of refraction n b ; B. contacting the flat polished surface of the object to the optically flat surface of the transparent base to form an interface comprising an air/transparent base interface section at the irregularities; C. directing a beam of radiation, having a spectral band width with a central wavelength, through the incident surface of the transparent base onto the interface at an angle θ which is greater than a critical angle defined by the relationship of n b and n air , to produce totally internally reflected radiation at the air/transparent base interface section at the irregularities which passes through the exit surface of the transparent base; and D. detecting and converting the reflected radiation into a visible image of the irregularities.
Claim 3
Dependent Claim
17 words
The method of claim 1 wherein the object is a wafer comprising one of silicon and germanium.
Claim 4
Dependent Claim
20 words
The method of claim 2 wherein the flat polished surface is one of an oxide, nitride, and metal surface layer.
Claim 5
Dependent Claim
17 words
The method of claim 3 wherein the flat polished surface was polished by a chemical-mechanical polishing method.
Claim 6
Dependent Claim
25 words
The method of claim 1 wherein compositions of the flat polished surface and the object are the same and wherein n O =n S .
Claim 7
Dependent Claim
27 words
The method of claim 1 wherein the angle θ is less than a second critical angle defined by the relationship of n b and n S .
Claim 8
Dependent Claim
22 words
The method of claim 1 wherein the transparent base is selected from the group consisting of silicon, germanium, sapphire, and magnesium fluoride.
Claim 9
Dependent Claim
14 words
The method of claim 1 wherein the beam of radiation is a laser beam.
Claim 10
Dependent Claim
13 words
The method of claim 1 wherein the beam of radiation is infrared radiation.
Claim 11
Dependent Claim
17 words
The method of claim 1 wherein the flat polished surface is translated across the optically flat surface.
Claim 12
Dependent Claim
12 words
The method of claim 1 wherein the transparent base is a prism.
Claim 13
Dependent Claim
38 words
The method of claim 1 wherein the reflected radiation is detected and converted into the visible image electronically and wherein the visible image is displayed as an image on at least one of a monitor and a printer.
Claim 14
Dependent Claim
17 words
The method of claim 1 wherein the irregularities are at least one of scratches and concave voids.
Claim 15
Dependent Claim
22 words
The method of claim 1 wherein the angle θ is varied whereby penetration depth of the radiation into the interface is varied.
Claim 16
Dependent Claim
22 words
The method of claim 1 wherein the central wavelength is varied whereby penetration depth of the radiation into the interface is varied.
Claim 17
Independent Claim
225 words
A method for detecting and imaging irregularities in a flat, polished surface on an object, wherein the object has an index of refraction n O , the flat polished surface has an index of refraction n S , and air has an index of refraction n air and wherein the irregularities are indentations into the flat polished surface, the method comprising: A. providing a transparent base having an optically flat surface, an incident surface, an exit surface, and an index of refraction n b ; B. contacting the flat polished surface of the object to the optically flat surface of the transparent base to form an interface; C. directing a beam of radiation, having a spectral band width with a central wavelength, through the incident surface of the transparent base onto the interface at an angle θ which is greater than a critical angle defined by the relationship of n b and n air and which is greater than a second critical angle defined by the relationship of n b and n S , to produce reflected radiation from the irregularities which passes through the exit surface of the transparent base; and D. detecting and converting the reflected radiation into a visible image of the irregularities wherein a portion of the reflected radiation is analyzed spectroscopically to determine the composition of the flat polished surface.
Claim 18
Independent Claim
225 words
A method for detecting and imaging irregularities in a flat, polished surface on an object, wherein the object has an index of refraction n O , the flat polished surface has an index of refraction n S , and air has an index of refraction n air and wherein the irregularities are indentations into the flat polished surface, the method comprising: A. providing a transparent base having an optically flat surface, an incident surface, an exit surface, and an index of refraction n b ; B. contacting the flat polished surface of the object to the optically flat surface of the transparent base to form an interface; C. directing a beam of radiation, having a spectral band width with a central wavelength, through the incident surface of the transparent base onto the interface at an angle θ which is greater than a critical angle defined by the relationship of n b and n air and which is greater than a second critical angle defined by the relationship of n b and n S , to produce reflected radiation from the irregularities which passes through the exit surface of the transparent base; and D. detecting and converting the reflected radiation into a visible image of the irregularities wherein a portion of the reflected radiation is analyzed spectroscopically to determine the composition of the flat polished surface.
Claim 19
Dependent Claim
39 words
The method of claim 16 wherein the band width of the beam of radiation encompasses at least one of the visible spectral region and the infrared spectral region, and wherein the reflected radiation is analyzed spectroscopically with a spectrograph.
Claim 20
Dependent Claim
52 words
The method of claim 16 wherein the band width of the beam of radiation is narrowed to within a few wavelengths of the central wavelength and the central wavelength is varied through at least one of the visible spectral region and the infrared spectral region, whereby the reflected radiation is analyzed spectroscopically.
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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) | 2002-09-13 | 2003-03-15 | 2003-09-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-09-13 | 2007-03-15 | 2007-09-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-09-13 | 2011-03-15 | 2011-09-14 | $7700.00 | Window Closed / Lapsed |