Excimer laser pulse broadening method and device based on two-stage series connection

Abstract

The invention discloses an excimer laser pulse broadening method and device based on two-stage series connection. The device comprises a pre-stage pulse broadening device formed by a single beam splitting element and a confocal resonant cavity, and a post-stage pulse broadening device formed by a dual-beam splitting element and a confocal resonant cavity, wherein the confocal resonant cavity can be formed by a plurality of spherical reflectors. The pre-stage pulse broadening device employs the single beam splitting element to perform beam splitting for an incident laser beam and generate different optical delay output light beams through the confocal resonant cavity to directly combine with the output light beam to form a pulse width broadening light beam. The post-stage pulse broadening device employs the dual-beam splitting element to perform further beam splitting for the light beam broadened by the pre-stage pulse broadening device to generate an output light beam after optical delay of the confocal resonant cavity, wherein the pulse width of the output light beam is further broadened. The excimer laser pulse broadening method and device can greatly improve the laser pulse broadening rate, can further reduce the peak power of the laser beam after broadening and improve the life service of optical elements in the excimer laser optical system.

Description

technical field [0001] The invention relates to a method and a device for regulating and controlling output parameters of a laser, in particular to a method and a device for realizing broadening of an excimer laser pulse width. Background technique [0002] With the continuous development of extremely large-scale integrated circuit manufacturing processes, excimer laser light sources with shorter wavelengths, higher pulse energy and higher repetition rates are used in integrated circuit lithography equipment, such as the output of ArF excimer lasers that are currently mainly used The wavelength is 193nm, the laser pulse energy reaches above 15mJ, and the repetition frequency reaches 6000Hz. In the illumination and exposure optical systems of lithography machines, a large number of expensive deep ultraviolet calcium fluoride and fused silica optical components are used. These deep ultraviolet optical components have the same transmittance, refractive index and material densit...

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Problems solved by technology

[0005] Among the methods and devices mentioned above, the expansion of the pulse width by a single pulse stretching device can no longer meet the requirements for the use of excimer laser light sources for lithography.

However, if two sets of pulse stretching devices based on a single beam splitting element and an optical resonator are connected in series or adopt a device and method for secondary stretching by back reflection, the waveform of the laser pulse after stretching is poor, and the peak power of the pulse after stretching is still relatively low. High, especially when the initial input pulse waveform is poor, it cannot meet the requirements of use

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