Method for improving registration accuracy

Abstract

The invention relates to the technical field of semiconductor manufacturing, in particular to a method for improving registration accuracy. An actual pattern of an internal registration structure of a chip is obtained by electron beam scanning and is analyzed to obtain a registration offset of the actual pattern; data are modeled to generate a novel exposure compensation program; and a photoetching technique is carried out on the chip by a photoetching machine by virtue of the novel exposure compensation program, so that the registration accuracy of a semiconductor product is improved; and meanwhile, the yield of the semiconductor product is improved.

Description

technical field [0001] The invention relates to the technical field of semiconductor manufacturing, in particular to a method for improving registration accuracy. Background technique [0002] With the development of semiconductor technology, the critical dimensions of semiconductor devices are continuously reduced, so there are higher requirements for registration accuracy. [0003] The existing registration accuracy is obtained by measuring the registration reference marks on the registration accuracy measurement machine after the wafer is in the photolithography process. After obtaining the registration accuracy data, the exposure in the product manufacturing process is obtained by modeling. Compensation program (CorrectionperExposure). [0004] Existing defect scanning equipment can use high-intensity electron beam surface reflection to obtain the pattern of the current layer and the front layer after etching, so as to know whether there is a short circuit or an open ci...

AI Technical Summary

Problems solved by technology

This registration accuracy measurement method has the following defects: First, the registration fiducial marks are usually placed on the streets used for cutting into chips, so the number that can be placed is limited, so the modeling accuracy will be limited

Second, the location of the alignment fiducial marks on the street between the chips is inconsistent with the actual key alignment position in the chip, which will also cause deviations in the accuracy of the modeling

3. The registration fiducial mark is different from the key graphic design of the chip, so the offset caused by the influence of optical aberration will also be different, so the registration accuracy obtained by measuring the registration fiducial mark is not necessarily the actual chip Registration accuracy of internal key figures

Fourth, the registration fiducial marks will be deformed by the influence of CMP and other processes, which will also cause measurement errors in registration accuracy

Five, the registration fiducial mark is measured after photolithography, and some layers will go through the etching process in the next step, and the etching process will also cause the deviation of the registration accuracy to a certain extent

Therefore, the registration accuracy measurement value obtained before the etching process is not necessarily the final registration accuracy, and the defect scanning equipment can tell whether there is a short circuit or an open circuit between the current layer and the previous layer, but there is no actual numerical output for the registration accuracy. Feedback, which is undesirable for those skilled in the art

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