Aligning system, aligning method for photolithography equipment and enhancement type aligning mark

Abstract

The invention provides an alignment system, an alignment method and an enhanced alignment mark for lithography equipment. By taking advantage of a designed special alignment mark structure, the image signal of the alignment mark can be obtained through an alignment imaging system; through Fourier transformation, the image signal of the alignment mark is conversed to a frequency space so as to extract the frequency information of the marks in different levels; and through Fourier inverse transformation, the alignment signals of each corresponding frequency level are obtained, and contain the inner structure and phase information of the alignment marks; at last, the coarse alignment is carried out through original signals or obtained low level frequency; by making use of the alignment signals of high level frequency to do precision alignment, alignment resolution and precision are enhanced. Moreover, the invention also provides two types of enhanced alignment marks to enhance the signal strength of frequency component in special level, increases the signal-to-noise ratio of the signal of the level and reduces alignment error.

Description

technical field [0001] The invention relates to photolithographic devices in the field of integrated circuit or other micro-device manufacturing, in particular to an alignment system, an alignment method and enhanced alignment marks for photolithographic equipment. Background technique [0002] In the manufacturing process of semiconductor IC integrated circuits, a complete chip usually needs to undergo multiple photolithography exposures before it can be completed. Except for the first photolithography, the photolithography of other levels must be precisely positioned before exposure, so as to ensure the correct relative position between the two layers of graphics, that is, overlay accuracy. Overlay accuracy is one of the key technical indicators of projection lithography machines. There are many factors affecting the overlay accuracy, among which the alignment accuracy between the mask and the silicon wafer is one of the important influencing factors. [0003] The early...

AI Technical Summary

Problems solved by technology

However, reducing the marking line width or increasing the magnification of the imaging system will bring some problems, such as limited by the resolution of the image sensor and the manufacturing and processing capabilities of the marking, the marking line cannot be reduced indefinitely, and the marking line width The smaller it is, the easier it is to be deformed by the semiconductor process

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