Method for detecting focus variation between wafer center and wafer edge and compensation method thereof

Abstract

The invention relates to a method for detecting a focus variation between a wafer center and a wafer edge and relates to the integrated circuit manufacturing technology. The method comprises the stepsof (S1) providing a wafer with a plurality of cutting ways, (S2) designing a plurality of pattern and placing the plurality of the patterns on cutting ways on a wafer center area and cutting ways ona wafer edge area, and (S3) performing lithographic exposure on the wafer provided in step (S2), and (S4) measuring the change amount of the size of the patterns on the cutting ways on the wafer edgearea relative to the size of the patterns on the cutting ways on the wafer center area after exposure to obtain the focus variation between the wafer center and the wafer edge so as to detect the focus variation between the wafer center and the wafer edge in advance in the early stage of development.

Description

technical field [0001] The invention relates to integrated circuit manufacturing technology, in particular to a method for detecting focus variation between the center and edge of a wafer and a compensation method thereof. Background technique [0002] In the integrated circuit manufacturing process, the photolithography process is one of the important processes, which uses a photolithography machine to transfer the pattern on the mask plate to the photoresist on the wafer. In order to ensure that the pattern on the mask is accurately transferred to the photoresist, that is, the position and shape of the pattern on the photoresist are consistent with the pattern on the mask, the photolithography machine first aligns, that is, the pattern on the wafer The alignment mark is aligned with the alignment mark on the mask; then, focus, that is, adjust the height of the wafer in the lithography machine so that the wafer is within the focus range of the optical system of the lithogra...

AI Technical Summary

Problems solved by technology

[0003] However, the integrated circuit manufacturing process includes hundreds of steps, and some processes will cause the thickness of the wafer to be inconsistent. For example, after the copper grinding process is completed, the height of the wafer center and edge film will change dramatically, generally from the center of the wafer. The thickness of the film gradually decreases to the edge of the wafer, that is, the thickness of the central area of ​​the wafer and the edge area are inconsistent, and the thickness of the largest to the smallest film can be as low as 300 angstroms (A). The chip in the center is set as a standard. In this way, when the lithography machine performs the lithography process on the wafer, under the same lithography conditions, the focus of the chip on the edge of the wafer will be greatly affected. The current The focus detection ability of the lithography machine for the edge of the wafer is limited. It can only detect the 147mm, and the part beyond 147mm cannot be detected. In other words, there is no ability to compensate for the focus, and the edge of the wafer will produce In the case of out-of-focus, it will also cause out-of-focus phenomenon in the graphic area, which will cause graphic distortion. If the photolithography graphic is distorted, after etching, not only the critical dimension (CD) will exceed the specification, but also affect the yield of the product

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