Alignment signal processing method in photoetching technology

Abstract

The invention discloses an alignment signal processing method based on amplitude and phase probed separately. The method breaks a rough alignment signal from an alignment signal into sections and summarizes the same as well estimates peak value position; determines a rough alignment position of marker by rough alignment signal model fitting; simplifies and summarizes the accurate alignment signal from the alignment signal and determines peak value point of the accurate alignment signal by accurate alignment signal model fitting; and synthesizes the rough alignment position and the accurate alignment signal peak value point to determine a final alignment position. The alignment signal processing method provided by the invention can effectively improve alignment signal processing efficiency to acquire correct alignment position.

Description

technical field [0001] The invention relates to an alignment signal processing method in semiconductor integrated circuit lithography technology, in particular to an alignment signal processing method using separate detection of amplitude and phase. Background technique [0002] The photolithography apparatus in the prior art is mainly used in the manufacture of integrated circuits (ICs) or other micro devices. Through a photolithography device, multi-layer masks with different mask patterns are sequentially imaged under precise alignment on a photoresist-coated silicon wafer, such as a semiconductor silicon wafer or an LCD panel. Lithography devices are generally divided into two categories, one is stepping lithography devices, the mask pattern is exposed and imaged on one exposure area of ​​the silicon wafer, and then the silicon wafer moves relative to the mask to move the next exposure area to the mask. Underneath the mask pattern and the projection objective lens, the ...

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Problems solved by technology

The advantage of this scheme is that it can achieve automatic capture and high alignment accuracy, but the disadvantage is that it requires a special wedge adjustment device and complicated adjustment. In addition, the high-order signals in the diffracted light are weak, while this method is Higher alignment accuracy is achieved by relying on high-order signals. In practice, as the power of the reflected signal (especially the high-order signal) of the mark (especially the silicon wafer mark) is too low, the high-order signal cannot actually be used. Therefore, it cannot reliably provide the highest alignment accuracy

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