Method for on-line monitoring lens astigmatism

Abstract

The utility model discloses an on-line monitoring method for monitoring the diffused light of the lens. The monitoring method thereof is listed as follows: the self-exposed light wave of the photo-etching machine can record the aerial images on the aerial image collecting & detecting array of a focal plane via a lens system. The aerial images are collected together on the mask plate surface and the silicon wafer plane, and then the comparison is made between the two groups of the aerial images which are recorded on the array of the electronic detector, so as to calculate out the object distance compensation of the lens along X-direction and Y-direction. As per the measuring result, a feedback system is used to adjust the environmental parameters of the lens assembly, so as to realize the compensation for the diffused light of the entire lens assembly. The lens system at least includes a main lens assembly, a 45o beam splitting plate series (close to the fourier plane), a 45o mirror assembly, a projection lens, a focal plane aerial image collecting & detecting array and a electronic controlled optical shutter series. This method solves the low utilization rate of productive capacity and the divergence of the machines arising from the traditional off-line measuring, so as to improve the reliability and the service efficiency of the photo-etching machine's accuracy control.

Description

technical field [0001] The invention relates to a method for on-line monitoring of lens astigmatism of a lens imaging system in a projection lithography machine. Background technique [0002] With the development of semiconductor technology and the progress of processing and manufacturing technology, the critical dimension (CD Critical Demotion) of semiconductor devices is getting smaller and smaller, and the difficulty of processing and manufacturing is also increasing. How to better and more precisely control the pattern on the silicon wafer is the key to improving the photolithography process. The astigmatism of the lens group will cause the pattern on the silicon wafer to have differences in the X and Y directions, thereby affecting the control accuracy of the CD in the process. Traditional measurement of lens astigmatism (astigmatism) must be performed by exposing the silicon wafer on the imaging platform or recording by the photodetector on the platform, both of which...

AI Technical Summary

Problems solved by technology

The astigmatism of the lens group will cause the pattern on the silicon wafer to have differences in the X and Y directions, thus affecting the control accuracy of the CD in the process

Traditional measurement of lens astigmatism (astigmatism) must be performed by exposing the silicon wafer on the imaging platform or recording by the photodetector on the platform, both of which require the lithography machine to stop production, wasting production time

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