Alignment system for photolithography equipment

Abstract

The invention proposes an alignment system for lithography equipment, which includes an illumination branch and a coherent imaging branch, wherein the illumination branch includes a dual light source, a light source mixer, an optical fiber, an achromatic collimator lens, and a polarization beam splitter The coherent imaging branch includes a first beam branch and a second beam branch, and the first beam branch and the second beam branch both include a wedge plate, an imaging lens, a reference grating, and Detector, the first beam in the diffracted light returns to the polarizing beam splitter and passes through directly, deflected by the wedge plate, and the imaging lens is imaged on the reference grating, the detector receives the scanning signal for alignment, and the second beam in the diffracted light After returning to the polarizing beam splitter, it is reflected and separated from the first beam, and then deflected by the wedge plate, imaged by the imaging lens on the reference grating, and the detector receives the scanning signal for alignment. The invention mixes two beams of incoming light into one beam and coaxially illuminates the mark, eliminating the relative inclination between the two beams of light. It not only simplifies the system, but also improves alignment accuracy and process adaptability.

Description

Technical field [0001] The present invention relates to the technical field of semiconductor manufacturing, and in particular to an alignment system for lithography equipment. Background technique [0002] In the manufacturing process of semiconductor IC integrated circuits, a complete chip usually needs to undergo multiple photolithography exposures to be completed. Except for the first photolithography, the other levels of photolithography must be accurately positioned before exposure to the graphics of the level and the graphics left by the previous level of exposure, so as to ensure the correct relative position between each layer of graphics. Instant accuracy. Under normal circumstances, the overlay accuracy is 1 / 3 to 1 / 5 of the resolution index of the lithography machine. For a 100nm lithography machine, the overlay accuracy index requires less than 35nm. The overlay accuracy is one of the main technical indicators of the projection lithography machine, and the alignment ...

AI Technical Summary

Problems solved by technology

In severe cases, the position of the best focal plane of the advanced level, different colors of light are not on the same focal plane, which will affect its process adaptability function

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