US5982800A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Narrow band excimer laser
Assignee: Cymer LLC
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Filing: 1997-10-10
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Granted: 1999-11-09
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Expires: 2017-10-10
Abstract
Abstract A very narrow band pulse excimer laser capable of producing pulses at a rate in the range of about 500 to 2000 Hz with enhanced energy dose control and reproducibility. A prior art burst mode "slug effect" occuring at one gas circulation time after the beginning of a burst of pulses is eliminated by the addition of a minute quantity of oxygen. In a preferred embodiment very narrow bandwidth is achieved by reducing fluorine partial pressure to less than 0.10 percent and by increasing the reflectance of the output coupler to greater than 25 percent. In a preferred embodiment, prior art fused silica beam expansion prisms used in the prior art line narrowing module were replaced with calcium fluoride prisms.
Inventors
- 👤 Toshihiko Ishihara
- 👤 Thomas Hofmann
- 👤 Palash P. Das
- 👤 Alexander I. Ershov
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 22:26
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/70008; G03F7/70025; G03F7/70041; G03F7/70216; G03F7/70483; G03F7/7055; G03F7/70558; G03F7/70575; H; H01; H01S; H01S3/00; H01S3/02; H01S3/03; H01S3/10; H01S3/13; H01S3/131; H01S3/134; H01S3/14; H01S3/22; H01S3/223; H01S3/225; H01S3/036; H01S3/05; H01S3/08; H01S3/08004; H01S3/08009; H01S3/081; H01S3/0811; H01S3/0812; H01S3/09; H01S3/097; H01S3/0971; H01S3/09713; H01S3/2251; H01S3/2256
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
82 words
A very narrow band excimer laser comprising: A. a laser chamber comprised of fluorine compatible materials and containing: (1) two elongated electrodes; (2) at least one preionizer; (3) laser gas defining a total pressure and comprised of a noble gas, fluorine, a buffer gas, and oxygen, said oxygen having a concentration of between 2 and 50 ppm. B. a line narrowing module comprised of: (1) at least one beam expanding prism; (2) a grating; (3) a tuning means for tuning the grating.
Claim 2
Dependent Claim
82 words
A very narrow band excimer laser comprising: A. a laser chamber comprised of fluorine compatible materials and containing: (1) two elongated electrodes; (2) at least one preionizer; (3) laser gas defining a total pressure and comprised of a noble gas, fluorine, a buffer gas, and oxygen, said oxygen having a concentration of between 2 and 50 ppm. B. a line narrowing module comprised of: (1) at least one beam expanding prism; (2) a grating; (3) a tuning means for tuning the grating.
Claim 3
Dependent Claim
25 words
A very narrow band excimer laser as in claim 1 wherein said fluorine has a partial pressure of less than 0.10 of the total pressure.
Claim 4
Dependent Claim
23 words
A very narrow band excimer laser as in claim 1 and further comprising an output coupler having a reflectance of at least 25%.
Claim 5
Dependent Claim
16 words
A very narrow band excimer laser as in claim 1 wherein said noble gas is krypton.
Claim 6
Dependent Claim
16 words
A very narrow band excimer laser as in claim 1 wherein said noble gas is argon.
Claim 7
Dependent Claim
21 words
A very narrow band excimer laser as in claim 1 wherein said at least one prism is comprised of calcium fluoride.
Claim 8
Dependent Claim
23 words
A very narrow band excimer laser as in claim 1 wherein at least one prism is three prisms, all comprised of calcium fluoride.
Claim 9
Dependent Claim
26 words
A very narrow band excimer laser as in claim 1 wherein the partial pressure of fluorine is less than 0.06 percent of the total gas pressure.
Claim 10
Dependent Claim
28 words
A very narrow band laser as in claim 1 wherein said excimer laser is an ArF excimer laser and the concentration of oxygen is less than 5 ppm.
References Cited (Backward Citations)
JPH0688481A
Cited
US5307364A
Cited
US5559816A
Cited
US5668067A
Cited
US5708495A
Cited
JPH09260749A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2002-11-08 | 2003-05-10 | 2003-11-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-11-08 | 2007-05-10 | 2007-11-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-11-08 | 2011-05-10 | 2011-11-09 | $7700.00 | Window Closed / Lapsed |