Line width compression device containing beam shaping and wavelength rotation tuning

Abstract

A line width compression device containing beam shaping and wavelength rotation tuning is composed of a beam shaper, a prism beam expander and a diffraction grating. The long axis of a rectangle beam is split into sub beams in a plurality of directions by placing a prism on a light path, the deflecting sub beams are overlaid with the short axis of an original beam by a high reflective mirror, thus realizing variation of length-width ratio of the beam and further reducing beam length requiring beam expansion and effectively reducing the grating length; the central wavelength tuning mechanism of a laser is realized by rotating the rotating floor of a fixed prism, a stepping motor rotating floor and a PZT nano rotating floor respectively realize rough tuning and precise tuning on two beam expansion prisms, and the incident angle of the beam and the grating is adjusted to realize rough tuning and precise tuning of the central wavelength of the laser. The invention can realize narrow line width laser output, the beam shaping can effectively reduce the size of the diffraction grating, the tuning of the central wavelength causes the structure to be compact and be easy for tuning, and the invention is applicable to multiple lasers, especially an excimer laser.

Description

technical field [0001] The invention relates to a line width compression device of an excimer laser used in photolithography, in particular to a line width compression device including beam shaping and wavelength rotation tuning. Background technique [0002] Excimer lasers can be used as light sources for integrated circuit lithography, that is, by illuminating a mask to project its image onto a wafer. In order to reduce the chromatic aberration caused by the diffraction of the projection lens, it is especially necessary to provide a light source with a narrow spectral linewidth of less than 1pm. For a free-running ArF excimer laser, its spectral bandwidth is about 500pm. Therefore, as a light source for lithography, it is necessary to significantly compress the line width. [0003] The Littrow structure composed of prisms and gratings can select the wavelength of the beam to obtain narrow linewidth laser output. In excimer lasers, a common method is to directly expand t...

AI Technical Summary

Problems solved by technology

On the other hand, in the previous technology, a lever device was used to tune the center wavelength of the laser beam. This technical solution has a complex structure, is difficult to control, and will also affect the stability of the wavelength and bandwidth. See the prior art [US patentNO.2008 / 0151944], while it is convenient and easy to implement rotation tuning on the turntable with fixed prisms, the current nanopositioning system can achieve a rotation accuracy of 0.1μrad, which can meet the requirements of narrow bandwidth laser wavelength tuning

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