Inclined slit based automatic focusing method and device

Abstract

The invention discloses an inclined slit based automatic focusing method and device. The device comprises an illumination unit, a beam splitting unit, an object lens (107) and a detection unit; the illumination unit comprises a light source (101), an illumination lens (102) and an illumination slit (103), and is used to provide incident light; the beam splitting unit carries out beam splitting on received light; the object lens (107) carries out imaging on the illumination slit (103) in the surface of a to-be-measured object (109), and reflects an image of the illumination slit (103) to the beam splitting unit; and the detection unit comprises a detection slit (113) and a detector (114), receives the image of the illumination slit (103) from the beam splitting unit and records a confocal signal related to the surface of the to-be-measured object (109), and the detection slit (113) and the illumination slit (103) are arranged inclinedly in the same inclination angles relative to the optical axes of themselves, and is positioned in a confocal position relative to the objective lens (7).

Description

technical field [0001] The invention belongs to the field of semiconductor measurement, and in particular relates to an automatic focusing method and system for wafer detection equipment with patterns on the surface. Background technique [0002] In the manufacturing process of integrated circuit chips, the product yield is an important indicator to measure the chip manufacturing process. As the critical dimensions of integrated circuits continue to shrink and the pattern density continues to increase, the difficulty of process control also increases. Defects that could be ignored in the past may cause the device to not work properly and become a fatal defect that affects the yield. At the same time, new three-dimensional device structures, such as FinFET, and new semiconductor materials (such as copper interconnects, low-k and high-k dielectric materials, and metal gate electrodes) are widely used, bringing new electrical performance defects; new process Processes, such as...

AI Technical Summary

Problems solved by technology

In fact, due to the tilt of the wafer, especially the deformation of the wafer surface caused by vacuum adsorption, the premise of this method is difficult to hold in practice.

In addition, the non-uniformity of slit illumination and the difference in the reflectivity of each layer pattern, especially the unavoidable speckle noise of laser illumination, will affect the position detection of the peak pixel point of the slit confocal image, so the accuracy of the result sex is difficult to guarantee

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