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Method and apparatus for measuring bandwidth of an optical spectrum output of a very small wavelength very narrow bandwidth high power laser

A laser and bandwidth technology, applied in lasers, measurement optics, interference spectroscopy, etc., can solve problems such as insufficient measurement accuracy and laser distortion

Active Publication Date: 2006-08-02
西默有限公司
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Problems solved by technology

This complexity distorts the laser being measured in many ways (e.g., in terms of bandwidth), which is now or will soon be such that measurements of, for example, full width at half maximum ("FWHM") are not sufficiently accurate to properly monitor laser output

Method used

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  • Method and apparatus for measuring bandwidth of an optical spectrum output of a very small wavelength very narrow bandwidth high power laser

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Embodiment Construction

[0008] Applicants have found that the above-mentioned coefficients A and C can vary approximately with changes in the specific spectral shape of the light source which can be predicted from operating conditions or light source lifetime.

[0009] look now figure 1 , which shows a schematic diagram of a laser bandwidth control system 10 according to an embodiment of the present invention. System 10 may include, for example, a laser 12, such as an excited atom gas discharge laser, such as the XLA-100 currently sold by the assignee of the present application. The laser may emit a beam 14, say nominally at 193.368 nm, with a bandwidth of, say, 0.1-0.3 pm.

[0010] Beam 14 may be incident on a beam splitter 16 which may pass, for example, substantially 99 percent of the light in beam 14 to form beam 20 and reflect substantially the remainder of the beam as beam 22 . The beam 22 may pass through a broadband detector, such as a dispersive or interferometric broadband detector, such ...

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Abstract

An apparatus and method for controlling a laser system is disclosed which may comprise a spectrometer adapted to measure an unknown bandwidth of a spectrum of light emitted from the laser, which may comprise an optical bandwidth measuring unit adapted to provide as an output a measured parameter, which is indicative of a parameter of the unknown bandwidth of the spectrum being measured; a reported parameter computing unit adapted to compute a reported parameter of the unknown bandwidth of the spectrum being measured according to the formula: Reported Parameter (''RP'')=A*(Measured Parameter (''MP''))+C, wherein the RP and MP are a different type of parameter and the values of A and C are determined based upon calibration of the optical bandwidth measuring unit MP response for light of known valued of RP. The optical bandwidth measuring unit may comprise an interferometric or dispersive optical instrument, such as an etalon. RP may be, e.g., at FWXM and MP may be, e.g., FWX'M, wherein X<>X'. RP may be, e.g., at EX % and MP may be, e.g., at FWXM.

Description

technical field [0001] The present invention relates to accurate estimation of the bandwidth of a light source, such as the bandwidth of laser light emitted by a laser emitting light with a narrow bandwidth. Background of the invention [0002] It is well known that spectrometers can be used to measure the wavelength and bandwidth of light sources such as lasers. For example using a position sensitive detector such as a photodiode array ("PDA") well known in the art, the output of such a bandwidth meter is actually the result of the measurement. A bandwidth meter has its own response function that modifies the spectrum being measured during the bandwidth measurement. [0003] However, due to, for example, the increasing demand for features with narrower critical dimension lines (CD reduction) in the fabrication of integrated circuits for ultra-large-scale integrated circuits ("ULSI"), there is a need for Ultraviolet - "DUV" and extreme ultraviolet - "EUV"), with purity def...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01B9/02G01J1/42G01J3/02G01J3/28G01J3/45G01J9/00H01S3/13H01S3/225
CPCH01S3/225G01J3/027G01J3/02G01J1/4257G01J3/28H01S3/1305G01J3/45G01J9/00G01J1/42
Inventor R·J·拉法克
Owner 西默有限公司