CN107026095A - Wafer Edge Measurement Module - Google Patents

Abstract

A wafer edge measurement module includes: at least one linear scanning camera mounted at a predetermined position of the edge of the wafer; at least one convex lens set located in front of the linear scanning camera, so that the linear scanning camera can perform linear scanning on the middle edge of the wafer edge after passing through the convex lens set; at least one reflector set near the edge of the wafer and composed of a first and a second reflector with the front surface; and the light sources of the at least three light source element groups are respectively projected to pixels on the upper inclined plane edge, the middle end edge and the lower inclined plane edge of the wafer to be linearly scanned so as to respectively form different dark field light sources, all the pixels on the edge of the wafer are made to be in a low gray value area, and when part of the pixels on the edge of the wafer linearly scanned by the linear scanning camera are in a high gray value area, the high gray value area is measured as the defect of the edge of the wafer. The invention has the effects of improving the speed of measuring the edge of the wafer and discovering defects in real time.

Description

Wafer Edge Measurement Module

technical field

The invention relates to a wafer edge measurement module, especially an integrated linear scanning camera, convex lens, reflector and dark field light source, which can also increase the speed of wafer edge measurement and detect defects in real time.

Background technique

In the past, for mass-produced wafer measurement, most of them used a lot of manpower and used many different measuring tools to do the measurement work manually. This manual inspection method, in addition to the disadvantages of high personnel costs, inspection work with human eyes, not only has problems such as boring, eye fatigue, and high turnover rate of personnel, but also the stability of quality is also a problem. Issues worthy of discussion, therefore, gradually replace artificial vision with machine vision. In terms of industrial cameras, they are distinguished by imaging principles, mainly including line-scanning and surface-line scanning technologies. Arranged in a line, only one column of image data can be obtained at a time when taking an image. When the relative motion between the industrial camera and the object to be photographed occurs, two-dimensional image data can be obtained; The image sensing components of the company adopt a two-dimensional matrix type. In terms of optical geometry of machine vision, it uses different combinations of mirrors, concave lenses, convex lenses, focusing mirrors, and plano-convex lenses to perform optical reflection and refraction. degree of research. In terms of the lighting geometry of machine vision, the lighting source can be divided into bright field light source and dark field light source. The bright field light source reflects the light source and directly enters the lens; the dark field light source reflects the light source and does not directly enter the lens.

Secondly, the wafer measurement is mainly on the effective area, not the invalid area. Usually the edge of the wafer belongs to the invalid area, rather than the focus of the measurement. However, due to the gradual vitrification and expansion of the wafer material, if the wafer edge appears Defects are processed, transferred, and transported in the multiple process steps of lithography, diffusion, cleaning, chemical mechanical polishing, and chemical vapor deposition. effective area, so wafer edge defects have quietly become yield-limiting defects.

Therefore, wafer edge measurement has not yet been paid attention to, but how to integrate industrial camera technology of machine vision, optical geometry technology and lighting geometry technology to effectively improve the speed of wafer edge measurement and detect defects in real time. Therefore, there will be more room for improvement.

Contents of the invention

In order to solve the problem of measuring the wafer edge in the prior art, the present invention provides a wafer edge measurement module, which integrates the line scan type of the industrial camera, the convex lens of the optical geometry, the mirror and the dark field of the illumination geometry The light source has the effect of improving the speed of measuring the edge of the wafer and finding defects in real time.

The technical solution adopted by the present invention to solve its technical problems is:

A wafer edge measurement module, comprising: at least one linear scanning camera installed at a predetermined position on the edge of the wafer; at least one convex lens group located in front of the linear scanning camera, allowing the linear scanning camera to pass through the convex lens group Afterwards, the middle edge of the edge of the wafer is linearly scanned; at least one mirror group is close to the edge of the wafer, and it is composed of a first and a second mirror, and the reflective surface faces forward, and The first and second reflection mirrors are symmetrical with the line scan camera as the central reference, and both sides are inclined forward, so that the line scan camera passes through the reflection surfaces of the first and second reflection mirrors, and then respectively Linear scanning of the upper bevel edge and the lower bevel edge of the wafer edge; and at least three light source element groups, the light sources of which are respectively projected onto the upper bevel edge, middle edge and lower bevel edge of the wafer edge to be linearly scanned pixels to form different dark-field light sources respectively, so that all pixels on the edge of the wafer present a low gray value area, when the line scan camera linearly scans some pixels on the edge of the wafer to present a high gray value area, then It is detected that the high gray value area is a defect on the edge of the wafer.

According to the features disclosed above, the light source element group is composed of a first and a second light source assembly, which are close to the edge of the wafer, and make the light source projected forward, and the first and second light source assemblies use the line scan camera as the The central datum is symmetrical and the two sides are inclined forward, so that the first and second light source components present a non-180° parallel light source angle, and make the light source angle be between 60°˜160°.

According to the feature disclosed above, the first and second reflectors exhibit a non-180° parallel reflection angle, and the reflection angle is between 60° and 160°.

According to the disclosed features, a screen is also included to observe the defects at the edge of the wafer.

According to the features disclosed above, it also includes a defect judging unit for automatically judging the defects on the edge of the wafer.

With the help of the above technical means, the present invention selects the fast scanning of the line scanning camera, the mirror body of the convex lens group, the mirror group and the dark field light source of the light source element group to be integrated, and eliminates the non-fast scanning surface line scanning, Non-convex lens groups, mirror bodies and non-contrasting bright-field light sources can also replace manual measurement and application of wafer edges, thereby improving the speed of wafer edge measurement and real-time detection of defects. .

The beneficial effect of the present invention is that it integrates the line scanning type of the industrial camera, the convex lens of the optical geometry, the mirror and the dark field light source of the illumination geometry, and has the effect of improving the speed of measuring the edge of the wafer and finding defects in real time.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

FIG. 1 is a schematic diagram of linearly scanning the edge of a wafer according to the present invention.

FIG. 2 is a schematic diagram of measuring wafer edge defects according to the present invention.

Explanation of symbols in the figure:

10 line scan cameras

20 convex lens groups

30 mirror groups

31 first reflector

32 second reflector

33 reflective surface

40 light source element group

41 The first light source component

42 second light source assembly

50 screens

60 defect judgment unit

D defect

E wafer edge

Beveled edge on E ₁

E ₂ middle edge

E ₃ lower beveled edge

F dark field light source

P pixels

P ₁ low gray value area

P ₂ high gray value area

θ ₁ reflection angle

θ ₂ light source angle

detailed description

First of all, please refer to Fig. 1, the preferred embodiment of the wafer edge measurement module of the present invention includes: at least one linear scan camera 10, set up at a predetermined position on the wafer edge (E), using the linear scan camera 10 of the industrial camera The scanning technology can quickly scan the edge (E) of the wafer through the image projected by the lens on the sensing component, but is not limited thereto.

At least one convex lens group 20 is located in front of the linear scanning camera 10, and after the linear scanning camera 10 passes through the convex lens group 20, the middle edge (E ₂ ) of the wafer edge (E) is linearly scanned, But not limited to this.

At least one reflector group 30 is close to the wafer edge (E), and it is formed by a first and second reflector 31, 32, and makes the reflective surface 33 forward, and the first and second reflector 31, 32 take the line scan camera 10 as the central reference, and make the two sides tilt forward in a symmetrical shape, so that the line scan camera 10 passes through the reflective surfaces 33 of the first and second mirrors 31, 33, and then The upper bevel edge (E ₁ ) and the lower bevel edge (E ₃ ) of the wafer edge (E) are linearly scanned respectively. In this embodiment, the first and second mirrors 31, 32 are not 180° parallel The reflection angle (θ ₁ ), and the reflection angle (θ ₁ ) is between 60°-160°, but not limited thereto.

At least three light source element groups 40, the light sources of which are respectively projected to pixels on the upper bevel edge (E ₁ ), the middle end edge (E ₂ ) and the lower bevel edge (E ₃ ) of the wafer edge to be scanned linearly, to respectively Different dark field light sources (F) are formed so that all pixels (P) of the wafer edge (E) present a low gray value area (P ₁ ), when the line scan camera 10 linearly scans the wafer edge (E) When part of the pixels (P) present a high gray value area (P ₂ ), it is measured that the high gray value area (P ₂ ) is a defect (D) of the wafer edge (E). In this embodiment, The light source element group 40 is composed of a first and a second light source assembly 41, 42, which is close to the edge (E) of the wafer, and makes the projection of the light source forward, and the first and the second light source assembly 41, 42 are The linear scan camera 10 is centered on the reference, and is symmetrical with both sides tilted forward, so that the first and second light source assemblies 41, 42 present a non-180°parallel light source angle (θ ₂ ), and make the light source The included angle (θ ₂ ) is between 60° and 160°.

In addition, also comprise the hardware device of a screen 50, observe the defect (D) of this wafer edge (E), or more can comprise the software device of a defect judging unit 60, automatically judge the defect of this wafer edge (E) ( D), analyzing and interpreting image differences, but not limited thereto.

With the help of above-mentioned technical means, the present invention effectively integrates the fast scanning of the line scan camera 10, the convex lens group 20, the mirror body of the mirror group 30 and the dark field light source of the light source element group 40, not only improving the measurement of the wafer edge (E) speed and real-time discovery of the defect (D), at the same time, it can cooperate with hardware devices or software devices to improve the recognition rate of the defect (D) on the edge of the wafer (E), and correctly determine the type of the defect (D), and Different processing is carried out according to different defects (D) to achieve the optimization of labor cost and equipment cost.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention in any form. Any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention still belong to within the scope of the technical solutions of the present invention.

In summary, the present invention fully meets the needs of industrial development in terms of structural design, practicability and cost-effectiveness, and the disclosed structure also has an unprecedented innovative structure, novelty, creativity and practicability, and meets the requirements of relevant According to the requirements of the invention patent requirements, the application is filed according to law.

Claims (5)

1. A wafer edge measurement module, characterized in that, comprising: At least one linear scanning camera is set up at a predetermined position on the edge of the wafer; At least one convex lens group is located in front of the linear scanning camera, and after the linear scanning camera passes through the convex lens group, the middle edge of the wafer edge is linearly scanned; at least one reflective mirror group, close to the edge of the wafer, and it is composed of a first and a second reflective mirror, with the reflective surface facing forward, and the first and second reflective mirrors take the line scan camera as the central reference , in a symmetrical shape so that both sides are tilted forward, so that the linear scanning camera passes through the reflecting surfaces of the first and second mirrors, and then linearly scans the edge of the upper bevel and the edge of the lower bevel of the edge of the wafer respectively ;as well as At least three light source element groups, the light sources of which are respectively projected to the pixels on the upper bevel edge, the middle end edge and the lower bevel edge of the edge of the wafer to be linearly scanned to form different dark field light sources respectively, so that all of the wafer edge The pixel presents a low gray value area, and when the linear scanning camera linearly scans some pixels on the edge of the wafer presenting a high gray value area, it is measured that the high gray value area is a defect on the wafer edge . 2. The wafer edge measurement module according to claim 1, wherein the light source element group is composed of a first and a second light source assembly, which are close to the edge of the wafer and project the light source toward front, and the first and second light source components take the line scan camera as the central reference, are symmetrical and make both sides tilt forward, so that the first and second light source components present a non-180°parallel light source angle, And the included angle of the light source is between 60° and 160°. 3. The wafer edge measurement module according to claim 1 or 2, wherein the first and second mirrors present a non-180° parallel reflection angle, and the reflection angle is 60° °～160°. 4. The wafer edge measurement module according to claim 3, further comprising a screen for observing defects on the wafer edge. 5. The wafer edge measurement module according to claim 3, further comprising a defect judgment unit for automatically judging defects on the wafer edge.