Autofocus method and system

Abstract

The invention discloses an automatic focusing method and system, wherein the automatic focusing method comprises the steps of: setting a boundary characteristic area A in the field of view of a shooting mechanism; the shooting mechanism and a measured object move relatively, and the shooting mechanism controls the object during the relative movement The measured object is shot to obtain an image, the image includes the measured object area B and the boundary feature area A, and the relative position information between the shooting mechanism and the measured object is recorded during shooting; the clarity of the image is obtained, and it is judged whether the clarity reaches the peak; if the clarity When the peak value is reached, the relative position information corresponding to when the sharpness reaches the peak value is recorded, and the focus is completed. The autofocus method of the present application can realize autofocus in the process of wafer inspection, improve focusing efficiency, and avoid the problem of being unable to determine whether the focus is successful.

Description

technical field [0001] The present invention relates to the technical field of wafer detection, in particular to an automatic focusing method and system. Background technique [0002] High-magnification lenses are required in wafer inspection, but generally the depth of field of high-magnification lenses is small, and the surface flatness of wafers is poor. As a result, when high-magnification lenses use fixed focal lengths to capture wafer images, it is impossible to guarantee the quality of the wafer. Each test area on the test can be clearly imaged, and the blurred imaging effect cannot meet the high-precision detection requirements. However, the traditional method can only manually adjust the focal length and rely on the naked eye to judge whether the focus position is reached, which is inefficient and expensive. Moreover, the surface of a wafer with a smooth and flawless surface has no features, and it is difficult to judge whether the focus is successful by general foc...

AI Technical Summary

Problems solved by technology

[0002] High-magnification lenses are required in wafer inspection, but generally the depth of field of high-magnification lenses is small, and the surface flatness of wafers is poor. As a result, when high-magnification lenses use fixed focal lengths to capture wafer images, it is impossible to guarantee the quality of the wafer. Each test area on the screen can be clearly imaged, and the blurred imaging effect cannot meet the high-precision detection requirements. However, the traditional method can only manually adjust the focal length and judge whether the focus position is reached by naked eyes, which is inefficient and expensive.

Moreover, the surface of a wafer with a smooth and flawless surface has no features, and it is difficult to judge whether the focus is successful by the general focusing method.

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