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Imaging of EUV radiation from plasma source at high repetition rates

IP.com Disclosure Number: IPCOM000130583D
Publication Date: 2005-Oct-28
Document File: 1 page(s) / 27K

Publishing Venue

The IP.com Prior Art Database

Related People

William C. Cray: ATTORNEY

Abstract

B. Purpose and advantage of invention: Due to the slow readout times of CCD cameras normally images can be captured only at low repetition rates of several exposures per second. By using a fast scanning mirror in the imaging of the EUV light from the micro-plasma onto the CCD chip, the images of sequential plasma pulses can be captured (due to their different position on the chip) even though the exposure and read-out time for a single CCD image takes many milliseconds. EUV plasma source size measurements can be made at high repetition rates, on the order of several kHz. Say, to about 10 kHz.

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Imaging of EUV radiation from plasma source at high repetition rates

B.                 Purpose and advantage of invention:

Due to the slow readout times of CCD cameras normally images can be captured only at low repetition rates of several exposures per second. By using a fast scanning mirror in the imaging of the EUV light from the micro-plasma onto the CCD chip, the images of sequential plasma pulses can be captured (due to their different position on the chip) even though the exposure and read-out time for a single CCD image takes many milliseconds. EUV plasma source size measurements can be made at high repetition rates, on the order of several kHz. Say, to about 10 kHz.

 

C.                 Short description of invention (Include or attach appropriate sketches, and point out novel features):

The EUV light emitted from a micro-plasma (from either a laser-produced or a discharge-produced plasma, for example) is imaged via an arrangement of focusing mirrors. The mirrors are coated with a multilayer coating for high EUV reflectivity. The mirror coatings can have a protective cap layer to increase their lifetime in an etch-gas environment; they can also be made from a high-temperature-stable multilayer structure to withstand high EUV fluxes.

A typical embodiment of an imaging configuration consists of a concave EUV mirror and a flat EUV mirror in a “Z”-shaped configuration with reflection close to normal incidence (for example, at 5 degrees incidence angle). See figure...