Alignment mark search system used for photo-etching equipment and its alignment mark search method

Abstract

The invention provides an alignment mark search system applied to a lithography device and a search method thereof. The system comprises an optical imaging system, a signal conditioning system and a master control system, wherein, the optical imaging system obtains the image of a datum plate and outputs a first light intensity signal, the signal conditioning system receives the first light intensity signal, adopts a digital potentiometer controller to realize bidirectional voltage regulation and outputs light intensity data, the master control system adjusts the position of the datum plate according to the light intensity data. The alignment mark search system of the invention contributes to accurately obtaining corresponding position information concerning reference marks of machines, carrying out demarcation and correction on machine constants relative to machine mark positions rapidly, shortening correction time of the machine constants after complete installation of the machines and improving efficiency of the complete machines after restoring to normal operation.

Description

technical field [0001] The present invention relates to an alignment mark search system and its alignment search method, and in particular to an alignment mark search system and its alignment mark search method for lithography equipment. Background technique [0002] The lithography machine belongs to a kind of key equipment on the process line of chip manufacturing. Its principle is to use the projection lens to illuminate the mask plate through the illumination source, and expose the pattern on the mask to the designated position on the silicon wafer. Due to the needs of the process, the manufacture of chips with certain functions requires multi-layer exposure on the same chip. There is a certain positional relationship between layers and lines. The positional relationship is very strict, which needs to be done through the alignment mark search system. ensure. For the silicon wafer alignment mark search system, the principle is to use an illumination light source differen...

AI Technical Summary

Problems solved by technology

In the actual working process, the initial state of the integrator 3 is consistent with the state after clearing, that is, corresponding to the state with the largest gain. Adjust the gain of the signal, the gain is adjusted from the maximum value to the small value, when the signal output meets the set requirements, the integration is stopped, the gain is temporarily locked, and the alignment process is completed in a short time after the gain is locked, because the gain is locked It is not completely locked. Due to the existence of circuit leakage current, the integrator 3 will slowly self-discharge, which also makes the gain slowly return to the initial state, and the gain becomes the initial maximum value. As a result, the automatic gain The signal output of the link is in a saturated state most of the time, regardless of whether the mark is detected or not, so it is impossible to use the output of its signal to realize the automatic search of this mark, and the adjustment of its signal gain can only be adjusted from a large gain Adjust to small gain, not flexible setting and adjustment

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