Method for simultaneously monitoring photolithography exposure condition and registration photoetching precision

Abstract

The invention discloses a method for monitoring photoetching exposure condition and alignment precision simultaneously. A rhombic measuring pattern is used for arranging a photoetching-alignment pattern, and the length, width and space period of each rhombus are small enough, so that macroscopic optical measurement can not distinguish all rhombuses from the photoetching-alignment pattern, while microcosmic photoetching can distinguish all rhombuses from the photoetching-alignment pattern; and then, an optical microscope is used for measuring the photoetching exposure condition and the photoetching-alignment precision simultaneously. Therefore, the method not only simplifies processing steps, reduces production cost and shortens production period of silicon chips, but also can monitor the change of exposure energy and the change of exposure focus for monitoring the exposure condition, so as to improve on-line monitoring capability for the exposure condition.

Description

technical field [0001] The invention relates to the on-line monitoring technology of photolithography process in semiconductor manufacturing, in particular to a method capable of simultaneously monitoring photolithography exposure conditions and overlay accuracy. Background technique [0002] In semiconductor manufacturing, the requirements for photolithography processes are generally photolithographic overlay accuracy and critical dimensions. There are generally two corresponding online monitoring methods: one is the measurement of lithography overlay accuracy, and the other is the measurement of key dimensions (ie, exposure conditions). Often a lithography level will have a monitoring process that includes the above two steps. There are two main factors affecting the critical dimension of lithography: exposure energy and exposure focal length. In the prior art, the measurement of the critical dimension can only reflect the change of the exposure energy, but lacks the abil...

AI Technical Summary

Problems solved by technology

In the prior art, the monitoring of exposure conditions is generally done through a scanning electron microscope (SEM), but the measurement steps are relatively cumbersome, and SEM measurement can only automatically perform changes in key dimensions, and it is difficult to automatically measure the light output. The shape of the resist changes with the exposure focal length, and the critical dimension of the general online monitoring pattern is not sensitive enough to the change of the exposure focal length, so the change of the exposure focal length is difficult to be automatically measured by SEM; in addition, although SEM can also measure some The overlay accuracy of the lithography level, but its scope of application is not wide, and it is impossible to measure the overlay accuracy of all lithography levels, that is, it is difficult to measure the shape change after the same substrate material is fully deposited and for different Conductive substrate materials cannot be measured after the SEM electron beam is focused due to the electron concentration effect; moreover, the measurement cost of using SEM to measure the overlay accuracy is relatively high, and the measurement process is time-consuming. In addition, the SEM equipment is relatively expensive, so the existing The measurement of overlay accuracy in the process is generally done through an optical microscope

Therefore, in the existing process, it is generally necessary to use an optical microscope and a SEM at the same time to monitor the lithography exposure conditions and overlay accuracy at the same time, so the measurement process is more complicated and the implementation cost is higher

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