US6313467B1
Expired / Lapsed
US
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Broad spectrum ultraviolet inspection methods employing catadioptric imaging
Assignee: KLA Corp
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Filing: 2000-06-16
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Granted: 2001-11-06
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Expires: 2020-06-16
Abstract
Abstract An ultraviolet (UV) catadioptric imaging system, with broad spectrum correction of primary and residual, longitudinal and lateral, chromatic aberrations for wavelengths extending into the deep UV (as short as about 0.16 μm), comprises a focusing lens group with multiple lens elements that provide high levels of correction of both image aberrations and chromatic variation of aberrations over a selected wavelength band, a field lens group formed from lens elements with at least two different refractive materials, such as silica and a fluoride glass, and a catadioptric group including a concave reflective surface providing most of the focusing power of the system and a thick lens providing primary color correction in combination with the focusing lens group. The field lens group is located near the intermediate image provided by the focusing lens group and functions to correct the residual chromatic aberrations. The system is characterized by a high numerical aperture (typ. greater than 0.7) and a large flat field (with a size on the order of 0.5 mm). The broad band color correction allows a wide range of possible UV imaging applications at multiple wavelengths.
Inventors
- 👤 David R. Shafer
- 👤 Yung-ho Chuang
- 👤 Bin-ming B. Tsai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 18:16
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/70216; G03F7/70225; G02; G02B; G02B13/00; G02B13/14; G02B13/143; G02B17/00; G02B17/08; G02B17/0804; G02B17/0808; G02B17/0856; G02B17/0892; G02B21/00; G02B21/16; G03F1/00; G03F1/68; G03F1/82; G03F1/84; G03F7/70275; G03F7/70483; G03F7/70605; G03F7/70616; G03F7/7065
Claims Analysis
Total Claims: 38
Claim 1
Independent Claim
35 words
A method of observing features of an object, comprising: illuminating an object with ultraviolet radiation at multiple wavelengths; forming a multi-wavelength ultraviolet image with a single broadband objective lens; and detecting the multi-wavelength ultraviolet image.
Claim 2
Independent Claim
35 words
A method of observing features of an object, comprising: illuminating an object with ultraviolet radiation at multiple wavelengths; forming a multi-wavelength ultraviolet image with a single broadband objective lens; and detecting the multi-wavelength ultraviolet image.
Claim 3
Dependent Claim
17 words
The method of claim 1 , wherein the object being observed comprises a wafer surface including photoresist.
Claim 4
Dependent Claim
15 words
The method of claim 1 , wherein the object being observed comprises a phase-shift photomask.
Claim 5
Dependent Claim
20 words
The method of claim 1 , further comprising analyzing the multi-wavelength image to identify and classify defects on the object.
Claim 6
Dependent Claim
28 words
The method of claim 1 , wherein the multi-wavelength ultraviolet image formed by the broadband objective lens comprises a field size of at least approximately 0.5 mm diameter.
Claim 7
Dependent Claim
33 words
The method of claim 1 , wherein forming the multi-wavelength ultraviolet image comprises moving the relative position of the object to the objective lens whereby different portions of the object are successively imaged.
Claim 8
Dependent Claim
16 words
The method of claim 1 , wherein the object is illuminated by an incoherent multi-wavelength source.
Claim 9
Dependent Claim
24 words
The method of claim 1 , wherein detecting the multi-wavelength ultraviolet image comprises passing the image through one or more wavelength-selective ultraviolet transmission filters.
Claim 10
Dependent Claim
22 words
The method of claim 1 , further comprising converting the detected multi-wavelength ultraviolet image to a visible light image for visual observation.
Claim 11
Dependent Claim
15 words
The method of claim 1 , wherein the object being observed comprises a semiconductor wafer.
Claim 12
Dependent Claim
19 words
The method of claim 1 , wherein the broadband objective lens comprises a component of a catadioptric imaging system.
Claim 13
Dependent Claim
16 words
The method of claim 1 , wherein the object is illuminated by a coherent light source.
Claim 14
Dependent Claim
14 words
The method of claim 1 , wherein the object being observed comprises a photomask.
Claim 15
Dependent Claim
14 words
The method of claim 1 , wherein the object being observed comprises a reticle.
Claim 16
Dependent Claim
18 words
The method of claim 1 , wherein the object being observed comprises a material undergoing masking or cutting.
Claim 17
Dependent Claim
15 words
The method of claim 1 , wherein the object being observed comprises a biological sample.
Claim 18
Dependent Claim
15 words
The method of claim 1 , wherein the object being observed comprises a metallurgical sample.
Claim 19
Dependent Claim
17 words
The method of claim 1 , wherein the object being observed comprises a sample undergoing spectroscopic analysis.
Claim 20
Dependent Claim
15 words
The method of claim 1 , wherein the objective lens comprises a focusing lens group.
Claim 21
Dependent Claim
15 words
The method of claim 1 , wherein the objective lens comprises a field lens group.
Claim 22
Dependent Claim
15 words
The method of claim 1 , wherein the objective lens comprises a catadioptric lens group.
Claim 23
Dependent Claim
20 words
The method of claim 1 , wherein the objective lens comprises a focusing lens group and a field lens group.
Claim 24
Dependent Claim
20 words
The method of claim 1 , wherein the objective lens comprises a focusing lens group and a catadioptric lens group.
Claim 25
Dependent Claim
20 words
The method of claim 1 , wherein the objective lens comprises a field lens group and a catadioptric lens group.
Claim 26
Dependent Claim
24 words
The method of claim 1 , wherein the objective lens comprises a focusing lens group, a field lens group, and a catadioptric lens group.
Claim 27
Dependent Claim
31 words
The method of claim 1 , wherein the objective lens comprises a focusing lens group, the method further comprising correcting chromatic variation of monochromatic image aberrations with the focusing lens group.
Claim 28
Dependent Claim
28 words
The method of claim 1 , wherein the objective lens comprises a field lens group, the method further comprising correcting residual color aberrations with the field lens group.
Claim 29
Dependent Claim
27 words
The method of claim 1 , wherein the objective lens comprises a catadioptric lens, the method further comprising correcting primary color aberrations with the catadioptric lens group.
Claim 30
Independent Claim
84 words
A method of observing features of an object, comprising: illuminating an object with ultraviolet radiation at multiple wavelengths separated substantially from one another; for each of at least a portion of the ultraviolet illumination wavelengths, forming a corresponding ultraviolet image slice of the object at a different focal plane from image slices corresponding to the other illumination wavelengths; and forming a composite image of the image slices, the composite image characterized by a greater depth of focus than any of its constituent image slices.
Claim 31
Independent Claim
84 words
A method of observing features of an object, comprising: illuminating an object with ultraviolet radiation at multiple wavelengths separated substantially from one another; for each of at least a portion of the ultraviolet illumination wavelengths, forming a corresponding ultraviolet image slice of the object at a different focal plane from image slices corresponding to the other illumination wavelengths; and forming a composite image of the image slices, the composite image characterized by a greater depth of focus than any of its constituent image slices.
Claim 32
Dependent Claim
38 words
The method of claim 29 , wherein forming each image slice employs a confocal microscope configuration with a broadband ultraviolet catadioptric objective and a set of ultraviolet image detectors having bandpass filters corresponding to each ultraviolet illumination wavelength.
Claim 33
Dependent Claim
27 words
The method of claim 29 , wherein the object being illuminated and imaged at different focal planes comprises a patterned wafer having a substantially non-planar surface profile.
Claim 34
Dependent Claim
25 words
The method of claim 29 , further comprising forming additional image slices of the object so that each focal plane is imaged at multiple wavelengths.
Claim 35
Dependent Claim
15 words
The method of claim 29 , wherein forming a composite image comprises using computer integration.
Claim 36
Dependent Claim
15 words
The method of claim 29 , wherein the composite image comprises a three-dimensional (3-D) image.
Claim 37
Dependent Claim
23 words
The method of claim 29 , further comprising forming the composite image by integration of image slices to produce a three-dimensional (3-D) image.
Claim 38
Dependent Claim
41 words
The method of claim 29 , further comprising forming additional image slices of the object so that each focal plane is imaged at multiple wavelengths, and forming the composite image by integration of image slices to produce a three-dimensional (3-D) image.
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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) | 2004-11-05 | 2005-05-07 | 2005-11-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-11-05 | 2009-05-07 | 2009-11-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-11-05 | 2013-05-07 | 2013-11-06 | $7700.00 | Window Closed / Lapsed |