Aligning system and aligning method for lithography equipment

Abstract

The invention provides an aligning system and an aligning method for a lithography equipment, which adopts two or more groups of amplitude-type reference grating and aligning marks of different periods; each branch grating of the reference grating and the aligning marks consist of bar-shaped structures with equidifferent arrangement widths so as to lead the scanning intensity signal peak to be sharper and improve the reliability of the aligning system; during the aligning process, only (plus and minus) 1 stage of diffracted beam with aligned marks is used; after the small period grating coherent image and corresponding reference gratings in the aligned marks are scanned, the obtained scanning signal intensity peak is used as coarse capture; based on coarse capture, the precise capture information is obtained by the phase information of the large period grating coherent images in the aligned marks; furthermore, the phase information obtained by scanning the large period grating coherent image and the corresponding reference grating in the aligned marks is used for precise alignment; and the alignment position error caused by asymmetric deformation of the alignment marks is reduced, the complexity of the optical system is reduced and the utilization ratio of the optical energy is improved.

Description

technical field [0001] The present invention relates to lithographic equipment, and in particular to an alignment system and an alignment method for lithographic equipment. Background technique [0002] The lithography equipment in the prior art is mainly used in the manufacture of integrated circuits (ICs) or other micro devices. Through photolithography equipment, multi-layer masks with different mask patterns are sequentially exposed and imaged on a silicon wafer coated with photoresist under precise alignment. The current lithography equipment is roughly divided into two categories, one is stepping lithography equipment, the mask pattern is exposed and imaged on one exposure area of ​​the silicon wafer, and then the silicon wafer moves relative to the mask to move the next exposure area Go to the mask pattern and under the projection objective lens, again expose the mask pattern on another exposed area of ​​the silicon wafer, and repeat this process until all exposed ar...

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Problems solved by technology

However, when using a wedge array, the requirements for the surface shape and wedge angle consistency of the two wedges with the same positive and negative orders of refraction are very high; and the requirements for the manufacturing, assembly and adjustment of the wedge plate group are also very high. It is difficult and expensive to realize the project

[0007] Furthermore, Chinese Patent Publication (Announcement) No. 200710044152.1 patent "an alignment system for lithography equipment", the alignment system uses a three-period phase grating with a combination of thickness and thickness, and only uses the three-period phase grating The first-order diffracted light is used as an alignment signal, which can achieve a large capture range and high alignment accuracy. Only using the first-order diffracted light of each cycle can obtain a stronger signal strength and improve the system signal-to-noise ratio. The multi-channel high-order diffraction components are separated by means of adjustment devices such as wedges, which simplifies the optical path design and debugging difficulty, but the alignment marks in the alignment system are arranged in a line on the silicon wafer and the reference plate, which reduces the utilization of the light source. Moreover, this arrangement will cause crosstalk of scanning signals when each group of grating images of the alignment mark scans the corresponding reference grating in the alignment scanning, and the grating images of different periods scan a reference grating at the same time, which is not conducive to the lithography equipment. alignment

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