Self-referencing interferometric alignment system for lithography equipment

Abstract

The invention discloses a self-reference interference alignment system for photoetching equipment. The system comprises a laser light source module, an optical module, a signal acquisition module and a processing module, wherein the laser light source module is used for providing illumination beams; the optical module is used for marking the illumination beams to form a diffraction optical signal; the signal acquisition module is used for processing the optical signal to acquire a light intensity signal; the processing module is used for processing the light intensity signal to acquire an alignment position by combining position data of a workpiece table; the optical module comprises a first optical channel and a second optical channel; an optical signal in the second optical channel is processed to be used for eliminating optical noises in the first optical channel.

Description

technical field [0001] The invention relates to the field of integrated circuit equipment manufacturing, in particular to a self-referencing interference alignment system for photolithography 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 accurately positioned before exposure, so as to ensure the correct relative position between the graphics of each layer. Instant overlay accuracy. Normally, 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 is required to be less than 35nm. Overlay accuracy is one of the main technical indicators of a projection lithography machine, and the alignment accuracy between the mask and the silicon waf...

AI Technical Summary

Problems solved by technology

[0005] In this invention, due to the fluctuation of the light intensity irradiated on the mark (the energy change over time, mainly caused by the fluctuation of the output light intensity of the laser, the energy fluctuation caused by phase modulation and light intensity modulation, the stability of the optical path, and the environmental fluctuations) ), this fluctuation will directly affect the quality of the signal, resulting in alignment errors

Usually 1% fluctuation can cause 0.5nm misalignment

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