Line narrowing unit with flexural grating mount

A technology of fixing parts and gratings, applied in the field of lasers

Inactive Publication Date: 2008-09-03
西默有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Applicants are having difficulty maintaining a consistently narrow bandwidth at these higher repetition rates and duty cycles

Method used

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  • Line narrowing unit with flexural grating mount
  • Line narrowing unit with flexural grating mount
  • Line narrowing unit with flexural grating mount

Examples

Experimental program
Comparison scheme
Effect test

Embodiment Construction

[0046] Preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[0047] Laser performance at high average power

[0048] A prior art beam-narrowed KrF excimer laser operating at relatively low average power, typically less than 5 watts, typically produces a laser centered at about 248 nm with a bandwidth of less than 0.6 picometers bundle. As long as the average power is below 5 Watts, the laser can be operated without problems at high repetition rates up to 2000 Hz or more. Typical pulse energies for lithographic KrF excimer lasers are 10 mJ. Therefore, to avoid increasing the average power, the laser must operate at a lower duty cycle. For example, it may be run at 2 kHz in bursts of 200 pulses with about 0.45 seconds between bursts. Such an operating state will produce the following average power:

[0049]

[0050] Problems with bandwidth control start to show up when the average power increases. This happens, for...

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PUM

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Abstract

A grating based line narrowing device for line narrowing lasers producing high energy laser beams. A flexure grating mount is provided which virtually eliminates stress on the grating caused by differential thermal expansion between the grating and the housing structure. The grating which is comprised of a very thin aluminum surface on a thick ultra low expansion glass substrate is attached to an aluminum housing structure using a flexure grating mount. At least one flexure joint is provided in the grating mount which permits thermal expansion and contraction of the substrate. In some embodiments the mount comprises a metal plate and the flexure joint is a H-Flex joint (124) with four legs (126) which is machined into the metal plate. In another embodiment two H-Flex joints are provided. In other embodiments, the flexure joint is a dovetail joint permitting one end of the mount to slip relative to the other.

Description

technical field [0001] The present invention relates to lasers, particularly high power gas discharge lasers with a line narrowing unit based on a grating. This application claims priority to Application Serial No. 09 / 451,407, filed November 30, 1999, which is based on Application Serial No. 09 / 390,579, filed September 3, 1999, now U.S. Patent No. 6,212,217B1 Partial continuation. Background technique [0002] narrowband gas discharge laser [0003] Gas-discharge ultraviolet lasers used as light sources for integrated circuit lithography are generally beam-narrowed. A preferred prior art beam narrowing technique is to use a grating based beam narrowing unit with an output coupler to form a laser cavity. The gain medium within the cavity is created by discharging into a circulating laser gas such as krypton, fluorine and neon (for KrF lasers); argon, fluorine and neon (for ArF lasers); or fluorine and helium and / or neon (for F 2 for lasers). [0004] Narrow Ray Componen...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01S3/08H01S3/1055H01S3/225G03F7/20H01S3/03H01S3/034H01S3/036H01S3/04H01S3/081H01S3/086H01S3/0943H01S3/13H01S3/134H01S3/137H01S3/139
CPCH01S3/036G03F7/70575H01S3/03H01S3/13H01S3/225H01S3/0401H01S3/086H01S3/1392H01S3/0812H01S3/02H01S3/2256H01S3/034H01S3/08059H01S3/134H01S3/08009G03F7/70025G02B5/06
Inventor C·C·蒂图斯W·G·胡尔布德R·F·西布尔斯基J·M·埃尔格茨M·S·利西克
Owner 西默有限公司
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