Alignment system and alignment method for photolithography equipment

Abstract

The invention provides an alignment system which is used for lithography equipment, and an alignment method thereof; the middle branch of a reference mark adopted by the alignment system is a sharing reference mark which consists of bar-shaped amplitude gratings on different directions and thus a new form of reference mark is formed; the position scanning of two directions can be realized; compared with the prior art, the signal-noise ratio and strength of the alignment signals is led to be improved; the energy using efficiency is improved; the obtained alignment scanning signals do not show obvious inflection points, thus being beneficial to the processing of the later signal detection and AGG gain and other parts; and the alignment accuracy is improved.

Description

technical field [0001] The present invention relates to photolithography equipment, in particular to an alignment system and an alignment method for photolithography 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 expose...

AI Technical Summary

Problems solved by technology

However, in the alignment system, the alignment marks are lined up on the silicon wafer and the reference board, and they are all alignment marks in one direction. The corresponding reference marks are divided into eight branches, which will bring many shortcomings: alignment marks The space occupied by the corresponding reference mark is relatively large, which makes the energy utilization rate of the light source low, and factors such as photolithography process and silicon wafer deformation have a relatively large impact on the alignment accuracy; when the coherent image of the diffracted beam of the alignment mark is scanned with the reference mark , the obtained alignment scan signal intensity has an obvious inflection point, which is not conducive to the later AGC gain and other related signal processing; when the middle branch of the reference mark scans in one direction, the two branches of the reference mark scan an alignment at the same time. The coherent image of the beam diffracted by the quasi-mark grating, no light can enter the detection fiber and photodetector behind the reference mark in the blank part of the two branches, which makes the intensity and signal-to-noise ratio of the alignment scanning signal very low, and will cause two The coherent image of a reference mark branch relative to the alignment mark diffracted beam has a phase mismatch problem, which is not conducive to the alignment of the alignment mark and signal processing; two small period reference marks in the same direction are in the case of sufficient alignment signal energy. The lower requirements should be as small as possible, but at the same time, the diameter of the detection fiber behind the reference mark becomes smaller and the space is difficult to couple with the reference mark

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