Method for realizing variable free lighting pupil based on micro-reflector array

Abstract

The invention provides a method for realizing a variable free lighting pupil based on a micro-reflector array. The method comprises the steps of measuring a light spot position, optimizing the light spot position, correcting the light spot position and the like, and specifically comprises the steps of measuring a position parameter of a reflected light spot through a CCD (charge coupled device) camera when each micro-reflector unit is static; substituting the parameters into a grid search ant colony algorithm for optimization to obtain a micro-reflector array rotation angle matrix for generating the shape of the required pupil; measuring a light spot position difference between the light intensity distribution and the required light intensity distribution on a target surface loaded with the rotation angle matrix, and correcting a micro-reflector array rotation angle obtained by optimization by taking the light spot position difference as a feedback to enable a result to finally meet a lighting requirement on the target surface. The method can realize various lighting modes including the non-circumferential symmetric complicated lighting pupil, is high in optimization speed, high in convergence and high in accuracy, and has high practicability.

Description

technical field [0001] The invention belongs to the field of microlithography, and relates to a method for realizing a free-illumination pupil in a lithography illumination system, in particular to a method for realizing a variable free-illumination pupil based on a microreflector array. Background technique [0002] Microlithography is a technology for manufacturing integrated circuits, liquid crystal displays and other microstructure devices. In lithography, the two factors that play a key role in image quality are resolution and depth of focus, so it is necessary to obtain better resolution to To form graphics of key dimensions, it is necessary to maintain a suitable depth of focus. With the continuous development of lithography technology and the continuous shrinking of lithography nodes, in addition to reducing the exposure wavelength λ and the numerical aperture NA of the projection objective lens, changing the shape of the exposure light source is one of the important...

AI Technical Summary

Problems solved by technology

[0005] But this method is only suitable for off-axis illumination that produces simple, uniform light intensity distribution, and is no longer suitable for free illumination pupils that produce complex changes in light intensity and shape at the same time

At the same time, due to the various aberrations of the programmable lighting system and the eccentricity of the optical components in the actual use process, there are certain differences between the actual spot distribution and the optimized ideal spot distribution, and these differences will affect the spot distribution on the output pupil plane. Uniformity and score quality on CDs

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