Wafer detection system

Abstract

A wafer detection system comprises a rotating seat, an image acquisition unit and a lighting unit, wherein the image acquisition unit and the lighting unit are arranged at an interval with the rotating seat. The rotating base comprises a carrying table and a driving module used for driving the carrying table to rotate. The image acquisition unit comprises a first line scanning camera; the first line scanning camera is used for shooting a wafer carried on the carrying table; an auxiliary surface passing through the wafer in a direction perpendicular to the wafer is defined, and the auxiliary surface defines a first side on the same side as the first line scanning camera and a second side opposite to the first side. The lighting unit comprises at least one light source which can be arranged on the first side or the second side. When the light source is located on the first side, the first line scanning camera shoots a dark field image, and when the light source is located on the second side, the first line scanning camera shoots a bright field image, so that all-directional detection is achieved.

Description

Technical Field

[0001] This utility model relates to an inspection device for semiconductor components, and more particularly to a wafer inspection system. Background Technology

[0002] In recent years, the wafer fabrication industry has flourished, with increasingly sophisticated technology and significant advancements in process dimensions, quality, and morphological diversity. With such substantial progress in manufacturing technology, back-end inspection to confirm process yield must also adapt. Currently, back-end inspection typically involves acquiring images of the wafer using specialized image-capturing equipment and then employing automated image analysis to identify specific defect features and determine the presence of defects. However, due to the ever-advancing wafer fabrication technology, the fabricated microstructures are not only tiny in scale but may also have unique morphologies, necessitating specific lighting patterns or angles for image capture during back-end inspection to accurately detect defects. Therefore, continuously improving the scope, efficiency, and quality of defect detection to keep pace with the rapid development of fabrication technology has become a crucial research and development challenge for those in the relevant technical fields. Utility Model Content

[0003] The purpose of this invention is to provide a wafer inspection system that can comprehensively perform high-quality inspections on wafers.

[0004] The present invention provides a wafer inspection system comprising a rotating stand, an image capturing unit spaced apart from the rotating stand, and an illumination unit spaced apart from the rotating stand.

[0005] The rotating stand includes a stage suitable for carrying wafers and a drive module connected to the stage for rotating the stage.

[0006] The image capturing unit includes a first line scan camera, which is used to capture dark field images and bright field images while the stage is rotating, facing the wafer supported on the stage.

[0007] An auxiliary surface of the wafer is defined, perpendicular to the wafer, and the auxiliary surface defines a first side on the same side as the first line scan camera and a second side opposite to the first side. The illumination unit includes at least one light source that can be disposed on either the first side or the second side. When the light source is located on the first side, the first line scan camera can capture the dark field image; when the light source is located on the second side, the first line scan camera can capture the bright field image.

[0008] The wafer inspection system of this invention includes an illumination unit comprising two light sources respectively disposed on the first side and the second side.

[0009] In the wafer inspection system of this invention, the auxiliary surface is rotated along the axis of rotation of the stage, defining the first line scan camera to take pictures within a first shooting range, which is the diameter of the wafer on the auxiliary surface.

[0010] In the wafer inspection system of this invention, the auxiliary surface is defined by the axis of rotation of the stage, and the first line scan camera is defined to take pictures within a first shooting range. The first shooting range is the radius of the wafer that is on the auxiliary surface and extends from the axis of rotation.

[0011] In the wafer inspection system of this invention, at least one light source of the illumination unit is yellow linear light.

[0012] The wafer inspection system of this utility model defines the first line scan camera of the image capturing unit as performing shooting in the line scan direction, and the linear extension direction of the at least one light source is the same as the line scan direction.

[0013] The wafer inspection system of this utility model includes an image capturing unit that further includes a second line scan camera disposed on the second side, and an illumination unit that includes two light sources disposed together on the first side or the second side, respectively corresponding to the light sources of the first line scan camera and the second line scan camera.

[0014] In the wafer inspection system of this utility model, the auxiliary surface is defined by the axis of rotation of the stage, defining the first line scan camera to take pictures with a first shooting range and the second line scan camera to take pictures with a second shooting range, wherein the first shooting range and the second shooting range extend from the axis of rotation on the auxiliary surface to opposite sides.

[0015] In the wafer inspection system of this invention, at least one light source of the illumination unit is yellow linear light.

[0016] The wafer inspection system of this utility model defines that the first line scan camera and the second line scan camera of the image capturing unit both perform shooting in the line scan direction, and the linear extension direction of the at least one light source is the same as the line scan direction.

[0017] The beneficial effects of this utility model are as follows: Considering that some types of defects can only be presented under specific lighting and shooting angles, as long as the position of the first line scan camera relative to the wafer is properly configured, and the position of the at least one light source is adjusted accordingly to meet the shooting requirements of the dark field image and the bright field image, when the first line scan camera is shooting using the line scan principle, as long as the stage rotates at least half a turn, the dark field image and the bright field image can be obtained at once, so as to efficiently obtain images and use the dark field image and the bright field image to inspect whether there are defects on the wafer from all angles. Attached Figure Description

[0018] Figure 1 This is a schematic diagram illustrating a first embodiment of the wafer inspection system of this utility model;

[0019] Figure 2 This is a schematic diagram illustrating the operation of the first embodiment and the execution of the detection.

[0020] Figure 3 This is a schematic diagram illustrating another implementation of the first embodiment;

[0021] Figure 4 This is a schematic diagram illustrating a second embodiment of the wafer inspection system of this utility model. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] See Figure 1 The first embodiment of the wafer inspection system of this utility model includes a rotating stand 1, an image capturing unit 2 spaced apart from the rotating stand 1, and an illumination unit 3 spaced apart from the rotating stand 1. In this first embodiment, the method of image analysis is used to inspect a specific type of defect on a wafer 9.

[0024] The rotating base 1 includes a stage 11 suitable for carrying the wafer 9, and a drive module 12 connected to the stage 11 and used to drive the stage 11 to rotate. Preferably, the stage 11 can be configured with a positioning mechanism such as vacuum adsorption to properly position the wafer 9 and prevent it from shifting or falling off the stage 11 during rotation. The drive module 12 is preferably a device such as a stepper motor that can precisely control the rotation amplitude of the stage 11, to facilitate the overall automated testing requirements of this first embodiment.

[0025] The image capturing unit 2 includes a first line scan camera 21. The first line scan camera 21 is used to capture a dark-field image and a bright-field image while the stage 11 rotates, facing the wafer 9 supported on the stage 11. The first line scan camera 21 of the image capturing unit 2 is defined to perform imaging in a line scan direction, thereby improving the precision of detection and catering to certain directional defect categories.

[0026] An auxiliary surface A is defined, passing through a center of the wafer 9 in a direction perpendicular to the wafer 9, which is also the axis of rotation of the stage 11. The auxiliary surface A defines a first side S1, which is on the same side as the first line scan camera 21, and a second side S2, which is opposite to the first side S1. The illumination unit 3 includes two light sources 31 respectively disposed on the first side S1 and the second side S2. The light sources 31 are yellow linear light, and a linear extension direction of the light sources 31 is the same as the line scan direction.

[0027] See also Figure 1 and Figure 2 The first line scan camera 21 is defined to capture images within a first shooting range Z1, which is on the auxiliary surface A and covers the diameter of the wafer 9. Therefore, after the first line scan camera 21 is properly set to shoot at the wafer 9, the illumination light emitted by the light source 31 located on the first side S1, which is the same as the first line scan camera 21, will essentially reflect off the wafer 9 and propagate to the second side S2. When the illumination light is not directly directed towards the first line scan camera 21, the captured image is a so-called dark-field image. However, the light source 31 located on the second side S2, which is different from the first line scan camera 21, will coordinate with the shooting direction of the first line scan camera 21 so that the emitted illumination light, after being reflected by the wafer 9, directly faces the first line scan camera 21, thereby capturing a so-called bright-field image.

[0028] Since the first imaging range Z1 of the first line scan camera 21 basically covers the diameter of the wafer 9, the imaging range will be as follows during detection: Figure 2 The presented scanning range Z' achieves a roughly fan-shaped shooting range with the rotation angle until the drive module 12 controls the stage 11 to rotate half a circle. This allows for scanning and capturing the entire wafer 9 within the first shooting range Z1 without requiring the first line scan camera 21 or the light source 31 to move. Subsequently, through automated image processing that overlays multiple images, both bright-field and dark-field images of the entire wafer 9 can be simultaneously obtained, enabling analysis and judgment targeting specific defects.

[0029] If we consider the type of defect to be identified as "defocus defect," since this type of defect varies in depth, the shooting angle of the first line scan camera 21 and the illumination angle of the light source 31 must be properly set to ensure that this type of defect is accurately presented in the image. Specifically, in response to defocus defects, in this first embodiment, the first line scan camera 21 is set to a shooting angle of 40±5 degrees relative to the auxiliary surface A, and each of the light sources 31 is set to an incident angle of 20±5 degrees relative to the auxiliary surface A. Therefore, since this first embodiment can simultaneously acquire the dark field image and the bright field image captured at appropriate angles in a single operation, image analysis can be used to perform feature analysis on the wafer 9 for the defect to be analyzed, comprehensively confirming whether the wafer 9 has a specific defect.

[0030] See Figure 3 This is another embodiment of the first embodiment, the main difference being that the first shooting range Z1 extends from the rotation axis on the auxiliary surface A and covers the radius of the wafer 9. This embodiment takes into account the existing specifications of the shooting range of the first line scan camera 21. If, for example, the wafer 9 is of a larger size, or if the shooting range cannot be expanded due to focusing limitations, the first shooting range Z1 can also be made to cover only the radius of the wafer 9. By controlling the stage 11 to rotate one revolution, the dark field image and the bright field image of the wafer 9 can be obtained in the same way, so as to continue the subsequent image analysis for specific defects.

[0031] See Figure 4 This is a second embodiment of the wafer inspection system of this utility model. The difference between this second embodiment and the first embodiment is that the image capturing unit 2 further includes a second line scan camera 22 disposed on the second side S2. The first line scan camera 21 is defined to capture images with a first shooting range Z1, and the second line scan camera 22 to capture images with a second shooting range Z2. The first shooting range Z1 and the second shooting range Z2 extend from the rotation axis to opposite sides on the auxiliary surface A. Specifically, this second embodiment uses the first line scan camera 21 and the second line scan camera 22 to capture the dark field image and the bright field image, respectively. Besides being selected based on the specifications of the imaging equipment, the sources of the dark field image and the bright field image are independent, which also facilitates simultaneous image analysis and processing in the backend, thereby further improving the inspection efficiency.

Claims

1. A wafer inspection system; characterized by: A rotation base comprising a stage adapted to carry a wafer, and a driving module connected to the stage and adapted to drive the stage to rotate; an image capturing unit spaced apart from the rotation base and comprising a first line scan camera adapted to capture a dark field image and a bright field image of the wafer carried on the stage while the stage is rotating; and an illumination unit spaced apart from the rotation base, defining a secondary surface passing through the wafer in a direction perpendicular to the wafer, and the secondary surface defining a first side on the same side as the first line scan camera, and a second side opposite to the first side, the illumination unit comprising at least one light source adapted to be disposed on the first side or the second side, the light source being disposed on the first side to enable the first line scan camera to capture the dark field image, and the light source being disposed on the second side to enable the first line scan camera to capture the bright field image. The illumination unit comprises two light sources disposed on the first side and the second side respectively.

2. The wafer inspection system of claim 1, wherein: The secondary surface passes through an axis of rotation of the stage, defining that the first line scan camera captures in a first capturing range on the secondary surface and covering a diameter of the wafer.

3. The wafer inspection system of claim 2, wherein: The secondary surface passes through an axis of rotation of the stage, defining that the first line scan camera captures in a first capturing range on the secondary surface and covering a radius of the wafer.

4. The wafer inspection system of claim 2, wherein: The at least one light source of the illumination unit is yellow linear light.

5. The wafer inspection system of any of claims 1 to 4, wherein: The first line scan camera of the image capturing unit is defined to capture in a line scan direction, and a linear extension direction of the at least one light source is the same as the line scan direction.

6. The wafer inspection system of claim 5, wherein: The image capturing unit further comprises a second line scan camera disposed on the second side, and the illumination unit comprises two light sources disposed on the first side or the second side together and corresponding to the first line scan camera and the second line scan camera respectively.

7. The wafer inspection system of claim 1, wherein: The secondary surface passes through an axis of rotation of the stage, defining that the first line scan camera captures in a first capturing range and the second line scan camera captures in a second capturing range on the secondary surface and extending from the axis of rotation to opposite sides.

8. The wafer inspection system of claim 7, wherein: The at least one light source of the illumination unit is yellow linear light.

9. The wafer inspection system of claim 7 or 8, wherein: The first line scan camera and the second line scan camera of the image capturing unit are defined to capture in a line scan direction, and a linear extension direction of the at least one light source is the same as the line scan direction.

10. The wafer inspection system of claim 9, wherein: ​

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