A four-degree-of-freedom laser pointing control system and its control method

Abstract

This application discloses a four-degree-of-freedom laser pointing control system and its control method, including: CO 2 The laser is used to emit a laser beam; the pointing adjustment module includes a first piezoelectric ceramic deflecting mirror and a second piezoelectric ceramic deflecting mirror, which is used to adjust the pointing of the laser beam; a light splitting module is used to divide the laser beam into first light beam and the second light beam; the first light beam bombards the tin target; the second light beam is transmitted to the pointing position monitoring module; the pointing position monitoring module includes a first camera and a second camera, which are used to respectively detect the near-field spot position and the far spot position of the laser pointing Field light spot position is measured; the industrial computer is used to calculate the driving signal applied to the pointing adjustment module according to the deviation between the light spot position in the first camera and the second camera and the predetermined position, so as to adjust the deflection of the first piezoelectric ceramic in real time The horizontal and pitch angles of the mirror and the second piezoelectric ceramic deflection mirror. In this way, the collimation and stable control of laser pointing can be realized, and the jitter of the beam can be significantly reduced.

Description

technical field [0001] The invention relates to the field of laser technology, in particular to a four-degree-of-freedom laser pointing control system and a control method thereof. Background technique [0002] The emergence of extreme ultraviolet (EUV) lithography technology has injected new vitality into the semiconductor industry, which is expected to promote its continued rapid development and enable the continuation of Moore's Law. According to the current research, using high-power narrow pulse width and high repetition frequency CO 2 Laser bombardment of tin targets is the best way to obtain high-quality EUV, that is, laser-induced plasma (Laser Produced Plasma, LPP) technology. To obtain high-quality EUV light, it is necessary to continuously bombard the droplet tin target with a high-precision and high-stability laser beam, but thermal drift inside the laser, air turbulence and temperature gradients, thermal effects in optical components and mirrors, mechanical sup...

AI Technical Summary

Problems solved by technology

The system is based on multi-variable input and output forms. It needs to measure the optical path distance of each section in the optical path and the focal length of the focusing mirror at the front end of the PSD detector. control precision

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