Wafer edge detection system and detection method

Abstract

The invention discloses a wafer edge detection system and detection method. The detection system comprises a bottom plate; the optical axes of the two optical machines face different directions, the driving assembly is in driving connection with the bottom plate and used for driving the bottom plate to move in the radial direction of the wafer to be measured so as to adjust the focal planes of the two optical machines, and any optical machine conducts focusing according to the difference value of the focal planes of the two optical machines till the parfocal lengths of the two optical machines are kept consistent. According to the invention, the two optical machines are used for wafer edge detection, the number of the detection optical machines is reduced while the detection resolution is not reduced, the focusing of the two optical machines can be completed through single focusing, repeated focusing of multiple optical machines is avoided, and defect detection of the whole wafer edge can be rapidly completed.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor detection technology, and in particular to a wafer edge detection system and a detection method. Background Art

[0002] Wafer defect detection is an important part of semiconductor manufacturing. The side edges of some wafers present irregular curved surfaces. Figure 1 Figure 1 is a schematic diagram of the structure of a wafer. Figure 1 As shown, the side edge of the wafer can be subdivided into five areas (A1, A2, A3, A4, A5), and the five areas face different directions, which brings great difficulty to edge detection.

[0003] In the existing technology, 3D structured light is difficult to apply due to problems such as detection accuracy and reflection angle. The principle of microscopic imaging is usually used for wafer defect detection. In order to meet the detection resolution requirements, most of them need to use high-magnification objective lenses, high numerical aperture (NA value) and high light intensity for detection. The larger the numerical aperture, the smaller the depth of field, and the greater the detection difficulty. If three to five cameras are used to perform wafer defect detection separately, it will lead to problems such as increased equipment costs and difficult layout. Summary of the invention

[0004] The present invention provides a wafer edge detection system and detection method to solve the problems of high detection difficulty, great equipment layout difficulty and high cost when performing defect detection on the wafer edge in the existing wafer detection technology, and reduce the number of detection optical machines without reducing the detection resolution.

[0005] According to one aspect of the present invention, there is provided a wafer edge detection system, comprising: a rotating stage for placing a wafer to be tested; a base plate; two optical machines with optical axes facing different directions; a driving assembly connected to the base plate and used to drive the base plate to move along the radial direction of the wafer to be tested so as to adjust the focal planes of the two optical machines; any one of the optical machines is focused according to the difference between the focal planes of the two optical machines until the focal lengths of the two optical machines remain consistent.

[0006] Optionally, the optical machine includes: a bright field light source, which is arranged toward the side area of ​​the wafer to be tested; the wafer edge detection system also includes: a scatterer assembly, which is fixed to the base plate and is used to scatter the output light of the bright field light source to the side area; the scatterer assembly includes a scatterer body and a scatterer mounting seat, which is fixed to the base plate and is used to fix the scatterer body; the scatterer body and the scatterer mounting seat are provided with an opening structure, and the opening structure is used to accommodate the side area of ​​the wafer to be tested.

[0007] Optionally, the optical machine also includes: an objective lens assembly, which is fixed to the bottom plate via a base, and the distance between the objective lens assembly and the wafer to be measured is adjustable along the optical axis; the objective lens assembly includes: a high-power objective lens body, an objective lens mounting seat, an adjustment sleeve and a first adjustment subassembly; the high-power objective lens body is fixedly mounted on the first side of the objective lens mounting seat, and the second side of the objective lens mounting seat is fixedly connected to the adjustment sleeve; the first adjustment subassembly is arranged on the first side of the objective lens mounting seat, and is used to adjust the focal length of the optical machine and adjust the resolution of the optical machine.

[0008] Optionally, the optical machine also includes: a tube lens assembly, which is fixed to the bottom plate via a base; the tube lens assembly includes a tube lens body, a tube lens mounting seat and a tube lens sleeve; the first side of the tube lens mounting seat is fixedly mounted with the tube lens body, the second side of the tube lens mounting seat is fixedly connected to the tube lens sleeve, the tube lens mounting seat and the tube lens sleeve are fixedly mounted on the base; the axial hole between the tube lens sleeve and the adjustment sleeve is matched; the tube lens body and the high-power objective lens body are infinitely conjugated.

[0009] Optionally, the optical machine also includes: a Sham imaging assembly, which is fixed to the bottom plate via a base; the Sham imaging assembly includes: a camera, a tilting pad, a second adjusting subassembly and a fixing member; the camera is arranged on the tilting pad; the tilting pad is fixedly mounted on the base via the second adjusting subassembly and the fixing member; the second adjusting subassembly is used to adjust the tilt angle of the camera.

[0010] Optionally, the camera is a time-delay integration camera; the time-delay integration camera is provided with a plurality of rectangular pixel units, and the long sides of the rectangular pixel units are oriented toward the rotation direction of the wafer to be measured.

[0011] Optionally, the Sham imaging assembly further includes: a transflective mirror and a transflective mirror mounting seat, wherein the transflective mirror mounting seat is fixedly mounted on the base; the transflective mirror is fixedly mounted on a first side of the transflective mirror mounting seat, and a hole structure is provided on a second side of the transflective mirror mounting seat, wherein the hole structure is used to accommodate a bright field light source of the optical machine.

[0012] Optionally, the wafer edge detection system further includes: a dark field light source, arranged toward a side area of ​​the wafer to be tested; an angle between an emitting light direction of the dark field light source and the side area is less than 30°.

[0013] Optionally, the power of the dark field light source is greater than or equal to 50W and less than or equal to 70W.

[0014] According to another aspect of the present invention, there is provided a wafer edge detection method, which is implemented based on the above-mentioned wafer edge detection system, wherein the wafer edge detection system includes two optical machines arranged on the same base plate, and the detection method includes: controlling a driving component to drive the base plate to move along the radial direction of the wafer to be tested, performing a first focusing until one optical machine is clearly imaged, and recording a first position of the driving component; controlling the driving component to drive the base plate to move along the radial direction of the wafer to be tested, performing a second focusing until the other optical machine is clearly imaged, and recording a second position of the driving component; calculating the difference between the focal planes of the two optical machines according to the first position and the second position, focusing any one optical machine based on the difference until the focal lengths of the two optical machines are consistent; collecting imaging data of the two optical machines after focusing is completed; and performing defect detection on the side area of ​​the wafer to be tested according to the imaging data.

[0015] The technical solution of the embodiment of the present invention is to set a rotating stage, a base plate, two optical machines with the same structure and a driving assembly. The rotating stage drives the wafer to be tested to rotate synchronously. The two optical machines are fixed to the same base plate, and the base plate is driven by the driving assembly to move along the radial direction of the wafer to be tested to adjust the focal planes of the two optical machines; any optical machine is focused according to the difference between the focal planes of the two optical machines until the focal lengths of the two optical machines are kept consistent, which solves the problems of high detection difficulty, great equipment layout difficulty and high cost when the existing wafer inspection technology is used for defect detection on the edge of the wafer. Without reducing the detection resolution, the number of detection optical machines is reduced, the equipment cost is saved, and the defect detection of the entire wafer edge can be completed quickly with high detection efficiency and detection accuracy.

[0016] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 A schematic diagram of the structure of a wafer;

[0019] Figure 2 A schematic structural diagram of a wafer edge detection system provided by an embodiment of the present invention;

[0020] Figure 3A front view of a wafer edge detection system provided by an embodiment of the present invention;

[0021] Figure 4 A side view of a wafer edge detection system provided by an embodiment of the present invention;

[0022] Figure 5 A stereogram of an objective lens assembly provided by an embodiment of the present invention;

[0023] Figure 6 A stereogram of an objective lens assembly provided by an embodiment of the present invention;

[0024] Figure 7 A schematic diagram of a Sham imaging structure of a wafer edge detection system provided by an embodiment of the present invention;

[0025] Figure 8 An imaging principle diagram of Sham imaging provided by an embodiment of the present invention;

[0026] Fig. 9 A flowchart of a wafer edge detection method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0028] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0029] The embodiment of the present invention provides a wafer edge detection system, which includes: a rotating stage for placing a wafer to be tested; a base plate; two optical machines with optical axes facing different directions; a driving assembly connected to the base plate for driving the base plate to move along the radial direction of the wafer to be tested to adjust the focal planes of the two optical machines; any optical machine focuses according to the difference between the focal planes of the two optical machines until the focal lengths of the two optical machines remain consistent. The focusing of the two optical machines can be completed by a single focusing, avoiding repeated focusing of multiple optical machines.

[0030] Figure 2 A schematic diagram of the structure of a wafer edge detection system provided by an embodiment of the present invention, Figure 3 A front view of a wafer edge detection system provided by an embodiment of the present invention; Figure 4 This is a side view of a wafer edge detection system provided by an embodiment of the present invention. This embodiment is applicable to the application scenario of defect detection on the edge of a wafer with an irregular curved surface. Figures 2 to 4 As shown, the wafer edge detection system of the present application includes: a rotating stage 100 , a base plate 200 , two optical machines 300 with the same structure, and a driving assembly 600 .

[0031] The rotating stage 100 is used to place the wafer to be tested 01. In this embodiment, the wafer to be tested 01 rotates synchronously with the rotating stage 100, so that the optical machine 300 can uniformly capture the image of the entire wafer edge.

[0032] The optical axes of the two optical engines 300 face in different directions. Figure 3 and Figure 4 As shown, the optical machine 300 of the present application includes: a first optical machine 300I and a second optical machine 300II. The main optical axes of the first optical machine 300I and the second optical machine 300II are respectively obliquely upward and obliquely downward along the edge of the wafer 01 to be tested. The specific orientation angle of the main optical axis is determined based on the curved surface shape of the side area of ​​the wafer 01 to be tested, and is not limited thereto. The first optical machine 300I and the second optical machine 300II have the same structure. Each optical machine is provided with an objective lens assembly, a tube lens assembly, a Sham imaging assembly and a bright field light source. Among them, the Sham imaging assembly can be understood as a camera for image scanning and detection based on the Sham imaging principle. The bright field light source can be understood as a light source that directly irradiates the surface of the object to be illuminated (such as the wafer 01 to be tested), and most of the reflected light returns to the camera along the original path. In this embodiment, the objective lens assembly can use a high-power objective lens. Optionally, the power of the bright field light source 301 is greater than or equal to 20W, and less than or equal to 30W. By setting a high-intensity detection light source, the imaging clarity is improved and the edge detection resolution is improved.

[0033] See also Figures 2 to 4The first optical machine 300Ⅰ is provided with a first objective lens assembly 310Ⅰ, a first tube lens assembly 320Ⅰ, a first Sham imaging assembly 330Ⅰ and a first bright field light source 301Ⅰ. The first bright field light source 301Ⅰ is arranged toward the side area of ​​the wafer 01 to be measured. The first objective lens assembly 310Ⅰ, the first tube lens assembly 320 and the first Sham imaging assembly 330Ⅰ are fixed to the bottom plate 200 via a first base 340Ⅰ, and the distance between the first objective lens assembly 310Ⅰ and the wafer 01 to be measured is adjustable along the main optical axis direction of the first optical machine 300Ⅰ. The second optical machine 300Ⅱ is provided with a second objective lens assembly 310Ⅱ, a second tube lens assembly 320Ⅱ, a second Sham imaging assembly 330Ⅱ and a second bright field light source 301Ⅱ. The second bright field light source 301Ⅱ is arranged toward the side area of ​​the wafer 01 to be measured. The second objective lens assembly 310Ⅱ, the second tube lens assembly 320Ⅱ and the second Sham imaging assembly 330Ⅱ are fixed to the bottom plate 200 via a second base 340Ⅱ, and the distance between the second objective lens assembly 310Ⅱ and the wafer 01 to be measured is adjustable along the main optical axis direction of the second optical machine 300Ⅱ.

[0034] See also Figures 2 to 4 , the wafer edge detection system of the present application also includes a dark field light source 400. The dark field light source 400 is arranged toward the side area of ​​the wafer 01 to be tested. Among them, the dark field light source 400 can be understood as a light source that irradiates the surface of the object to be illuminated (such as the side area of ​​the wafer 01 to be tested) at a large angle, so that the reflected light of the dark field light source in the side area does not enter the camera, and the scattered light of the dark field light source at the defects in the side area can enter the camera. The imaging data formed by the different curved surfaces of the side area of ​​the wafer 01 to be tested under the irradiation of the dark field light source is an image with a dark background and bright defects. Optionally, the power of the dark field light source 400 is greater than or equal to 50W, and less than or equal to 70W. By setting a high-intensity detection light source, the imaging clarity is improved and the edge detection resolution is improved.

[0035] See also Figures 2 to 4 The wafer edge detection system of the present application also includes a scatterer assembly 500, which is fixed to the bottom plate 200 and is used to scatter the emitted light of the bright field light source (the first bright field light source 301Ⅰ and the second bright field light source 301Ⅱ) to the side area. In this embodiment, the emitted light of the bright field light source 301 is scattered to the side curved surface area of ​​the wafer after passing through the scatterer assembly 500. The scattered light irradiates the side edge of the wafer and can return to the optical system along the original path to finally reach the Sham imaging assembly 330. The imaging data formed by the side area of ​​the wafer 01 to be tested under the irradiation of the bright field light source is an image with bright background and dark defects.

[0036] See also Figure 3 and Figure 4, the driving assembly 600 is connected to the base plate 200 for driving the base plate 200 to move along the radial direction (X or X') of the wafer 01 to be tested. The driving assembly 600 adjusts the focal planes of the two optical machines 300 so that the focal planes of the two optical machines 300 remain at the same position, and then focuses any optical machine according to the difference between the focal planes of the two optical machines, and adjusts the distance between the objective lens assembly and the wafer to be tested until the two optical machines 300 are clearly imaged at the same focal plane, that is, the focal lengths of the two optical machines are kept consistent. Among them, the focal plane can be understood as the plane where the focus of the optical machine 300 is located, and the focal plane is perpendicular to the main optical axis of the optical machine 300. The focal length can be understood as the distance from the positioning surface of the objective lens body (such as the objective lens mounting surface) to the object surface (such as the side surface of the wafer 01 to be tested) after the focal planes of the two optical machines 300 are kept consistent and the focusing is completed. Optionally, the driving assembly 600 includes at least a driving motor. The base plate 200 is driven to move along the radial direction (X or X') of the wafer 01 to be tested by adjusting the rotation angle and rotation speed of the driving motor.

[0037] In this embodiment, the focal planes of the two optical engines 300 are kept at the same position, and the focusing of the two optical engines can be completed by a single focusing, thereby avoiding repeated focusing of multiple optical engines.

[0038] Specifically, in the wafer edge detection system of the present application, two optical machines are arranged on a bottom plate 200 driven by the same driving component 600. The optical machine adopts a structure of a high-power objective lens and a Sham imaging component, and simultaneously adopts a bright field light source and a dark field light source to illuminate the side area of ​​the wafer 01 to be tested, and uses a scatterer component to scatter the emitted light of the bright field light source to the side area. During the focusing process, on the one hand, the distance between the objective lens component and the wafer 01 to be tested along the main optical axis direction is adjusted, and on the other hand, the bottom plate 200 is driven by the driving component 600 to drive the two optical machines 300 to move along the radial direction of the wafer 01 to be tested, so as to adjust the focal planes of the two optical machines so that the focal planes of the two optical machines 300 remain at the same. position, and then focus any one of the optical machines according to the difference in the focal planes of the two optical machines, until the two optical machines 300 are clearly imaged at the same focal plane, that is, the focal lengths of the two optical machines are kept consistent, and the focusing of the two optical machines can be completed by a single focusing, thereby avoiding repeated focusing of multiple optical machines. This solves the problems of high detection difficulty, high equipment layout difficulty and high cost in the existing wafer inspection technology when performing defect detection on the wafer edge curve. Without reducing the detection resolution, the number of inspection optical machines is reduced, thereby saving equipment costs. By rotating the stage to drive the wafer to be tested to rotate synchronously, the defect detection of the entire wafer edge can be completed quickly, thereby improving the edge detection efficiency and detection accuracy.

[0039] Optionally, the angle between the direction of the emitted light of the dark field light source 400 and the side area is less than 30°. Through the large-angle illumination of the dark field light source 400, the reflected light of the dark field light source in the side area does not enter the camera, and the scattered light of the dark field light source at the defect in the side area can enter the light source of the camera, forming an image with a dark background and bright defects.

[0040] See also Figure 3 As shown, the scatterer assembly 500 includes a scatterer body 501 and a scatterer mounting seat 502, and the scatterer mounting seat 502 is fixed to the base plate 200 and is used to fix the scatterer body 501; the scatterer body 501 and the scatterer mounting seat 502 are provided with an opening structure, and the opening structure is used to accommodate the side area of ​​the wafer 01 to be tested; the light beam emitted by the dark field light source 400 is irradiated to the side area through the opening structure.

[0041] Optionally, the scatterer body 501 can be made of milky white polymethylmethacrylate (PMMA) material. PMMA material has the advantages of high transparency, low price, and easy processing, and can reduce equipment costs while ensuring the scattering effect.

[0042] In this embodiment, the specific size and shape of the opening structure can be established based on the side area size of the wafer 01 to be tested and the incident angle of the dark field light source 400. Optionally, the opening structure can be set as a U-shaped groove structure. Preferably, the size (i.e., width) of the U-shaped groove structure in the direction perpendicular to the main optical axis can be set to any value greater than or equal to 3 mm and less than or equal to 6 mm.

[0043] Specifically, the scatterer assembly 500 is provided with a groove-shaped scatterer body 501 and a scatterer mounting seat 502. For example, a U-shaped groove with a width of 3 to 6 mm is opened between the scatterer body 501 and the scatterer mounting seat 502, and the scatterer body 501 is fixed on the scatterer mounting seat 502. At the same time, the side area of ​​the wafer 01 to be tested is inserted into the opening structure (for example, the U-shaped groove) of the scatterer assembly 500, and finally fixedly mounted on the bottom plate 200. After passing through the scatterer assembly 500, the emitted light of the first bright field light source 301I and the second bright field light source 301II is scattered to the curved surface area on the side of the wafer, so as to avoid the bright field light source from failing to cover curved surfaces at different angles, and improve the imaging effect under the bright field light source.

[0044] Figure 5 This is a front view of an objective lens assembly provided by an embodiment of the present invention. Figure 5As shown, taking the first optical machine 300Ⅰ as an example, the objective lens assembly of the present application (taking the first objective lens assembly 310Ⅰ as an example) includes: a high-power objective lens body 311, an objective lens mounting seat 312, an adjustment sleeve 313 and a first adjustment subassembly 314; the high-power objective lens body 311 is fixedly mounted on the first side of the objective lens mounting seat 312, and the second side of the objective lens mounting seat 312 is fixedly connected to the adjustment sleeve 313; the first adjustment subassembly 314 is arranged on the first side of the objective lens mounting seat 312, and is used to adjust the focal length of the optical machine and adjust the resolution of the optical machine.

[0045] See also Figure 5 As shown, the first adjustment subassembly 314 includes a first adjustment seat 3141, two springs 3142, two screws 3143 and a differential head 3144. Among them, the spring 3142, the screw 3143 and the differential head 3144 are all fixed to the first adjustment seat 3141. In this embodiment, the adjustment sleeve 313 cooperates with the shaft hole of the tube lens assembly. In the focusing process, the first focusing is performed by the driving assembly 600. The first focusing can give priority to ensuring that the imaging of the optical machine 300Ⅰ is clear, and the first position A of the driving assembly 600 is recorded at this time; then the driving assembly 600 performs the second focusing, and the second focusing can give priority to ensuring that the imaging of the optical machine 300Ⅱ is clear, and the second position B of the driving assembly 600 is recorded at this time; the difference between the first position A and the second position B is used to calculate the difference between the two optical machine focal planes, and then the first adjustment subassembly 314 adjusts the position of one of the optical machines (300Ⅰ or 300Ⅱ). The first adjustment subassembly 314 drives the high-power objective lens body 311 to move along the main optical axis by tightening or loosening the screw 3143, and adjusts the distance between the objective lens assembly and the wafer to be measured until both optical machines have clear images, that is, the focal lengths are consistent. The resolution of the optical machine is adjusted by adjusting the differential head 3144. In this embodiment, the adjustment accuracy of the differential head 3144 can reach 0.01 mm.

[0046] Figure 6 An exploded view of a tube lens assembly and a Sham imaging assembly provided by an embodiment of the present invention. Figure 6 As shown, taking the first optical machine 300Ⅰ as an example, the tube lens assembly of the present application (taking the first tube lens assembly 320Ⅰ as an example) includes a tube lens body 321, a tube lens mounting seat 322 and a tube lens sleeve 323; the tube lens body 321 is fixedly mounted on the first side of the tube lens mounting seat 322, and the tube lens sleeve 323 is fixedly connected to the second side of the tube lens mounting seat 322, and the tube lens mounting seat 322 and the tube lens sleeve 323 are fixedly mounted on the first base 340Ⅰ; the shaft hole between the tube lens sleeve 323 and the adjustment sleeve 313 is matched; the tube lens body 321 and the high-power objective lens body 311 are infinitely conjugated. By setting the infinite conjugated structure composed of the tube lens body 321 and the high-power objective lens body 311, the imaging clarity is improved.

[0047] See also Figure 6As shown, taking the first optical machine 300I as an example, the Sham imaging assembly of the present application (taking the first Sham imaging assembly 330I as an example) includes: a camera 331, a tilting pad 332, a second adjustment subassembly 333 and a fixing member 334. The second adjustment subassembly 333 includes a tilt adjustment seat 3331, a tilt adjustment cylinder 3332 and a fine-tuning screw group 3333. Among them, the fixing member 334 can be a clamp.

[0048] See also Figure 4 and Figure 6 As shown, the camera 331 is arranged on the tilting pad 332; the tilting pad 332 is fixedly mounted on the base (such as the first base 340Ⅰ) via the second adjusting subassembly 333 and the fixing member 334; the second adjusting subassembly 333 is used to adjust the tilting angle of the camera 331. In this embodiment, the tilting angle of the image plane relative to the mirror plane is the Sham angle of the Sham imaging assembly.

[0049] Optionally, the camera 331 is a time delay integration camera (Time Delay Integration, TDI for short); the time delay integration camera is provided with a plurality of rectangular pixel units, and the long sides of the rectangular pixel units face the rotation direction of the wafer to be tested 01. Specifically, during the edge detection process, the wafer to be tested 01 is placed on the rotating stage 100, and the long sides of the rectangular pixel units of the time delay integration camera face the rotation direction of the wafer to be tested 01. As the rotating stage 100 rotates, it is ensured that the reflected light in the side area returns to the original path and enters the camera 331, thereby improving the imaging effect.

[0050] See also Figure 6 As shown, taking the first optical machine 300Ⅰ as an example, the Sham imaging assembly of the present application (taking the first Sham imaging assembly 330Ⅰ as an example) also includes: a transflective mirror 335 and a transflective mirror mounting seat 336, the transflective mirror mounting seat 336 is fixedly mounted on a base (such as the first base 340Ⅰ); the transflective mirror 335 is fixedly mounted on the first side of the transflective mirror mounting seat 336, and a hole structure 337 is provided on the second side of the transflective mirror mounting seat 336, and the hole structure 337 is used to accommodate the bright field light source 301.

[0051] Specifically, the reflective mirror 335 is installed and fixed on one side of the reflective mirror mounting seat 336 and is fixed on a base (such as the first base 340Ⅰ), and a hole structure 337 is provided on the other side of the reflective mirror mounting seat 336. The hole structure 337 can allow the bright field light source 301 to be inserted, so that the light beam of the bright field light source 301 is reflected through the reflective mirror 335, while effectively reducing the external dimensions of the optical machine.

[0052] Figure 7 A schematic diagram of a Sham imaging structure of a wafer edge detection system provided by an embodiment of the present invention; Figure 8 An imaging principle diagram of Sham imaging provided in an embodiment of the present invention.

[0053] See also Figure 7 and Figure 8 As shown, in the imaging structure of the wafer edge detection system of the present application, the angle between the mirror plane where the objective lens 311 is located and the object plane of the wafer 01 to be measured is defined as the lens angle α, the tilt angle of the image plane relative to the mirror plane is the Sham angle β, and the angle between the line L' connecting the focus and the center of the wafer 01 to be measured and the main optical axis L is equal to 90°-α. In the Sham imaging structure, the lens angle α, the Sham angle β, the focal length f', the object distance f, the magnification x, the foreground depth of field X and the back depth of field X' satisfy the following formula 1:

[0054]

[0055] Combined with the above formula 1, a high-power objective lens and a TDI camera are selected according to the actual detection resolution requirements of the Sham imaging structure, and the layout structure of the optical machine is designed in combination with the side dimensions of the wafer 01 to be tested. During the focusing process, the focal lengths of the two optical machines are adjusted by adjusting the components and driving the bottom plate to move, so that both optical machines can obtain clear images and the focal lengths of the two optical machines remain consistent.

[0056] Based on the same inventive concept as the above embodiments, an embodiment of the present invention further provides a wafer edge detection method, which is implemented based on the above wafer edge detection system, and performs wafer edge detection based on the corresponding control strategy of the above wafer edge detection system, with high detection efficiency and detection accuracy.

[0057] See also Figure 3 and Figure 4 As shown, in this embodiment, the wafer edge detection system includes two optical machines ( 300Ⅰ and 300Ⅱ) arranged on the same base plate 200 .

[0058] See also Figure 3 and Figure 4 As shown, the wafer edge detection method of the present application includes: controlling the driving component to drive the base plate to move along the radial direction of the wafer to be tested, performing the first focusing until one optical machine is clearly imaged, and recording the first position of the driving component; controlling the driving component to drive the base plate to move along the radial direction of the wafer to be tested, performing the second focusing until the other optical machine is clearly imaged, and recording the second position of the driving component; calculating the difference between the focal planes of the two optical machines according to the first position and the second position, and focusing any one of the optical machines based on the difference until the focal lengths of the two optical machines are consistent; after the focusing of the two optical machines is completed, collecting imaging data of the optical machines; and performing defect detection on the side area of ​​the wafer to be tested according to the imaging data.

[0059] Fig. 9 A flow chart of a wafer edge detection method provided by an embodiment of the present invention. Fig. 9As shown, the wafer edge detection method of the present application specifically includes the following steps:

[0060] S1: Control the driving component to drive the base plate to move along the radial direction of the wafer to be tested, perform the first focusing, until a clear optical image is formed, and record the first position of the driving component.

[0061] S2: Control the driving component to drive the base plate to move along the radial direction of the wafer to be tested, perform a second focusing, until another optical machine forms a clear image, and record the second position of the driving component.

[0062] S3: Calculate the difference between the focal planes of the two optical machines according to the first position and the second position, and adjust the distance between the objective lens assembly of any optical machine and the wafer to be measured based on the difference until the focal lengths of the two optical machines remain consistent.

[0063] See also Figures 2 to 8 As shown, during the focusing process, the first focusing is performed by the driving component 600. The first focusing can give priority to ensuring that the image of the optical machine 300Ⅰ is clear, and the first position A of the driving component 600 is recorded at this time; then the driving component 600 performs the second focusing, and the second focusing can give priority to ensuring that the image of the optical machine 300Ⅱ is clear, and the second position B of the driving component 600 is recorded at this time; the difference between the first position A and the second position B is used to calculate the difference between the focal planes of the two optical machines, and then the first adjustment subassembly 314 adjusts the position of one of the optical machines (300Ⅰ or 300Ⅱ). The first adjustment component (such as the first adjustment seat 3141, two springs 3142, two screws 3143 and the micrometer head 3144) adjusts the distance between the objective lens assembly and the wafer 01 to be measured along the main optical axis until both optical machines have clear images, that is, the focal lengths are kept consistent. The focusing of the two optical machines can be completed by a single focusing, avoiding repeated focusing of multiple optical machines.

[0064] S4: After the two optical machines have completed focusing, they collect imaging data of the side areas under bright field light sources and dark field light sources.

[0065] In this embodiment, the imaging data formed by the side area of ​​the wafer to be tested under the illumination of a bright field light source is an image with a bright background and dark defects; the imaging data formed by different curved surfaces of the side area of ​​the wafer to be tested under the illumination of a dark field light source is an image with a dark background and bright defects.

[0066] Optionally, the power of the bright field light source is greater than or equal to 20 W and less than or equal to 30 W; and / or the power of the dark field light source is greater than or equal to 50 W and less than or equal to 70 W.

[0067] Optionally, the angle between the light emission direction of the dark field light source and the side area of ​​the wafer to be tested is less than 30°

[0068] S5: Perform defect detection on the side area according to the imaging data.

[0069] Specifically, the two optical machines simultaneously collect imaging data under bright field light sources and dark field light sources, and through image recognition technology, obtain defect detection results at different angles, which can avoid missing defects on irregular side surfaces and improve edge detection efficiency and detection accuracy.

[0070] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0071] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A wafer edge detection system, characterized in that: include: A rotating stage for placing the wafer to be tested; Base plate; Two optical machines with optical axes facing different directions; A driving assembly, drivingly connected to the base plate, and used for driving the base plate to move along the radial direction of the wafer to be tested, so as to adjust the focal planes of the two optical machines; Any one of the optical machines is focused according to the difference between the focal planes of the two optical machines until the focal lengths of the two optical machines remain consistent.

2. The wafer edge detection system according to claim 1, characterized in that: The optical machine comprises: a bright field light source, wherein the bright field light source is arranged toward the side area of ​​the wafer to be tested; The wafer edge detection system further includes: a scatterer assembly fixed to the bottom plate, and configured to scatter the emitted light of the bright field light source to the side edge region; The scatterer assembly comprises a scatterer body and a scatterer mounting seat, wherein the scatterer mounting seat is fixed to the bottom plate and is used to fix the scatterer body; The scatterer body and the scatterer mounting seat are provided with an opening structure, and the opening structure is used to accommodate the side area of ​​the wafer to be tested.

3. The wafer edge detection system according to claim 1, characterized in that: The optical machine further comprises: an objective lens assembly, wherein the objective lens assembly is fixed to the bottom plate via a base, and the distance between the objective lens assembly and the wafer to be measured is adjustable along the optical axis direction; The objective lens assembly comprises: a high-power objective lens body, an objective lens mounting seat, an adjustment sleeve and a first adjustment subassembly; The high-power objective lens body is fixedly mounted on a first side of the objective lens mounting seat, and the adjustment sleeve is fixedly connected to a second side of the objective lens mounting seat; The first adjustment subassembly is disposed on a first side of the objective lens mounting seat, and is used to adjust the focal length of the optical machine and the resolution of the optical machine.

4. The wafer edge detection system according to claim 3, characterized in that: The optical machine further comprises: a tube lens assembly, wherein the tube lens assembly is fixed to the bottom plate via a base; The tube lens assembly comprises a tube lens body, a tube lens mounting seat and a tube lens sleeve; The tube mirror body is fixedly mounted on a first side of the tube mirror mounting seat, the tube mirror sleeve is fixedly connected to a second side of the tube mirror mounting seat, and the tube mirror mounting seat and the tube mirror sleeve are fixedly mounted on the base; The axial hole between the tube mirror sleeve and the adjusting sleeve is matched; The tube lens body and the high-power objective lens body are infinitely conjugated.

5. The wafer edge detection system according to claim 1, characterized in that: The optical machine further comprises: a Sham imaging assembly, wherein the Sham imaging assembly is fixed to the bottom plate via a base; The Sham imaging assembly includes: a camera, a tilting pad, a second adjustment subassembly and a fixing member; The camera is arranged on the inclined pad; The tilting pad is fixedly mounted on the base via the second adjusting subassembly and the fixing member; The second adjusting subassembly is used to adjust the tilt angle of the camera.

6. The wafer edge detection system according to claim 5, characterized in that: The camera is a time-delay integration camera; The time delay integration camera is provided with a plurality of rectangular pixel units, and the long sides of the rectangular pixel units face the rotation direction of the wafer to be measured.

7. The wafer edge detection system according to claim 5, characterized in that: The Sham imaging assembly further includes: a transflective mirror and a transflective mirror mounting seat, wherein the transflective mirror mounting seat is fixedly mounted on the base; The reflective mirror is fixedly mounted on a first side of the reflective mirror mounting seat, and a hole structure is provided on a second side of the reflective mirror mounting seat, wherein the hole structure is used to accommodate a bright field light source of the optical machine.

8. The wafer edge detection system according to any one of claims 1 to 7, characterized in that: Also includes: A dark field light source is arranged toward the side area of ​​the wafer to be tested; The angle between the light emission direction of the dark field light source and the side area is less than 30°.

9. The wafer edge detection system according to claim 8, characterized in that: The power of the dark field light source is greater than or equal to 50W and less than or equal to 70W.

10. A wafer edge detection method, characterized in that: The wafer edge detection system according to any one of claims 1 to 9 is implemented, wherein the wafer edge detection system comprises two optical machines arranged on the same base plate, and the detection method comprises: Control the driving assembly to drive the base plate to move along the radial direction of the wafer to be tested, perform a first focusing, until a clear optical image is formed, and record a first position of the driving assembly; Controlling the driving assembly to drive the base plate to move along the radial direction of the wafer to be tested, performing a second focusing, until another optical machine forms a clear image, and recording a second position of the driving assembly; Calculating a difference between two optical machine focal planes according to the first position and the second position, and focusing any one of the optical machines based on the difference until the focal lengths of the two optical machines remain consistent; After the two optical machines have completed focusing, the imaging data of the optical machines are collected; Defect detection is performed on the side area of ​​the wafer to be tested according to the imaging data.

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