US6048651A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fresnel zone mask for pupilgram
Assignee: International Business Machines Corp
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Filing: 1998-10-23
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Granted: 2000-04-11
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Expires: 2018-10-23
Abstract
Abstract A test photomask comprising a fresnel zone target (FZT) pattern may be used to verify the adjustment of a precision projector illumination system of an image projection system. The method comprises the steps of creating the FZT pattern on a photomask, projecting a pupil diagram onto an image plane using the FZT pattern, and evaluating the pupil diagram to determine the illumination system adjustment.
Inventors
- 👤 Timothy A. Brunner
- 👤 Joseph P. Kirk
- 👤 Christopher J. Progler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 11:44
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/70483; G03F7/70591; G03F1/00; G03F1/26; G03F1/38; G03F1/44; G03F1/68; G03F1/82; G03F1/84; G03F7/70058; G03F7/70141
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
38 words
A photomask for verifying an adjustment of a precision projector illumination system, the photomask comprising a fresnel zone target pattern disposed over a surface of the photomask and adapted to project a pupil diagram onto an image plane.
Claim 2
Dependent Claim
38 words
A photomask for verifying an adjustment of a precision projector illumination system, the photomask comprising a fresnel zone target pattern disposed over a surface of the photomask and adapted to project a pupil diagram onto an image plane.
Claim 3
Dependent Claim
21 words
The photomask according to claim 1, wherein the fresnel zone target pattern is disposed over a back surface of the photomask.
Claim 4
Dependent Claim
21 words
The photomask according to claim 1, wherein the fresnel zone target pattern is disposed over a front surface of the photomask.
Claim 5
Dependent Claim
26 words
The photomask according to claim 1, wherein the fresnel zone target pattern is formed over a pellicle membrane offset from the front surface of the photomask.
Claim 6
Dependent Claim
15 words
The photomask according to claim 1, wherein the fresnel zone target pattern is substantially linear.
Claim 7
Dependent Claim
15 words
The photomask according to claim 1, wherein the fresnel zone target pattern is substantially circular.
Claim 8
Dependent Claim
137 words
The photomask according to claim 6, having an index of refraction and a thickness, and adapted to be used with light having a wavelength, wherein the fresnel zone target pattern has a focal length and comprises a plurality of rings corresponding to one or more periods having one or more phases in each period, each ring having a width according to the equation W.sub.j =s.sub.j -s.sub.j-1 for j=1 . . . N*n where: s m =((F*λ*2*m)/(I*n)) 1/2 for m=0 . . . N*n, N is the number of periods, n is the number of phases in each period, N*n is the number of rings, F is the focal length of the freznel zone target pattern and is equal to the photomask thickness, λ is the light wavelength, and I is the index of refraction of the photomask.
Claim 9
Dependent Claim
15 words
The photomask according to claim 7, wherein the wavelength is less than about 436 nm.
Claim 10
Dependent Claim
38 words
The photomask according to claim 7, wherein the wavelength is selected from the group consisting of about 436 nm, 365 nm, 248 nm, 193 nm, 157 nm, and in the range of about 10 nm to 15 nm.
Claim 11
Dependent Claim
17 words
The photomask according to claim 7, wherein the number of phases n is a positive even integer.
Claim 12
Dependent Claim
31 words
The photomask according to claim 10, wherein the number of phases n=2, and the phases consist of a plurality of light transmissive regions alternating with a respective plurality of opaque regions.
Claim 13
Dependent Claim
19 words
The photomask according to claim 10, wherein the number of phases n=2, and the phases are 0° and 180°.
Claim 14
Dependent Claim
21 words
The photomask according to claim 10, wherein the number of phases n=4, and the phases are 0°, 90°, 180°, and 270°.
Claim 15
Dependent Claim
137 words
The photomask according to claim 6, having an index of refraction and a thickness, and adapted to be used with light having a wavelength, wherein the fresnel zone target pattern has a focal length and comprises a plurality of rings corresponding to one or more periods having one or more phases in each period, each ring having a width according to the equation W.sub.j =s.sub.j -s.sub.j-1 for j=1 . . . N*n-1 where: s m =((F*λ*2*m)/(I*n)) 1/2 for m=0 . . . N*n-1, N is the number of periods, n is the number of phases in each period, N*n-1 is the number of rings, F is the focal length of the freznel zone target pattern and is equal to the photomask thickness, λ is the light wavelength, and I is the index of refraction of the photomask.
Claim 16
Dependent Claim
15 words
The photomask according to claim 14, wherein the wavelength is less than about 436 nm.
Claim 17
Dependent Claim
38 words
The photomask according to claim 14, wherein the wavelength is selected from the group consisting of about 436 nm, 365 nm, 248 nm, 193 nm, 157 nm, and in the range of about 10 nm to 15 nm.
Claim 18
Dependent Claim
18 words
The test photomask according to claim 14, wherein the number of phases n is a positive even integer.
Claim 19
Dependent Claim
31 words
The photomask according to claim 17, wherein the number of phases n=2, and the phases consist of a plurality of light transmissive regions alternating with a respective plurality of opaque regions.
Claim 20
Dependent Claim
19 words
The photomask according to claim 17, wherein the number of phases n=2, and the phases are 0° and 180°.
Claim 21
Dependent Claim
21 words
The photomask according to claim 17, wherein the number of phases n=4, and the phases are 0°, 90°, 180°, and 270°.
Claim 22
Independent Claim
53 words
A method for verifying the adjustment of an illumination system, the method comprising the steps of: creating a fresnel zone target pattern on a photomask; projecting a pupil diagram created by the fresnel zone target pattern onto an image plane; and evaluating the pupil diagram to determine an adjustment of the illumination system.
Claim 23
Independent Claim
53 words
A method for verifying the adjustment of an illumination system, the method comprising the steps of: creating a fresnel zone target pattern on a photomask; projecting a pupil diagram created by the fresnel zone target pattern onto an image plane; and evaluating the pupil diagram to determine an adjustment of the illumination system.
Claim 24
Dependent Claim
30 words
The method according to claim 21, further comprising the step of capturing an image of the pupil diagram on one of i) a resist-coated wafer and ii) a photosensitive film.
Claim 25
Dependent Claim
22 words
The method according to claim 21, further comprising the step of evaluating the pupil diagram by comparison to a predetermined pupil diagram.
Claim 26
Dependent Claim
34 words
The method according to claim 21, further comprising the steps of: capturing the pupil diagram on a photosensitive film, and evaluating the captured pupil diagram by creating a microdensitometer trace of the photosensitive film.
Claim 27
Dependent Claim
23 words
The method according to claim 21, further comprising the step of capturing an image of the pupil diagram with an electronic image detector.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2003-04-11 | 2003-10-11 | 2004-04-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-04-11 | 2007-10-11 | 2008-04-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-04-11 | 2011-10-11 | 2012-04-11 | $7700.00 | Window Closed / Lapsed |