Focusing device, focusing method and system for wafer detection and computer storage medium

Abstract

The invention provides a focusing device, a focusing method, a focusing system and a computer storage medium for wafer detection, in the focusing device, a light beam emitted by a light source emitting device is collimated by a first collimating lens and then enters a mask plate to generate linear array stripe structured light with alternate brightness and darkness; the light passes through the semi-transparent and semi-reflective prism, the plurality of second collimating lenses and the microscope objective in sequence and is converged to the surface of the wafer to be detected; the linear array stripe structured light reflected by the surface of the wafer to be detected sequentially passes through the microscope objective, the plurality of second collimating lenses, the semi-transparent and semi-reflective prism and the convergent lens and is converged to the photoelectric detector; and the photoelectric detector converts the linear array stripe structured light into a light current signal so as to determine the defocusing amount of the surface of the wafer to be detected according to the light current signal. Accurate real-time focusing can be provided for different wafers to be detected, the influence of pattern shapes or reflectivity differences of points to be detected on the wafers on a measurement result in the focusing process only depending on a defocusing relation calibration curve is overcome, and the defect detection sensitivity is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of wafer detection, and in particular relates to a focusing device, a focusing method, a system and a computer storage medium for wafer detection. Background Art

[0002] In the semiconductor wafer manufacturing process, defect detection plays a vital role in chip manufacturing. With the urgent market demand and the ultimate pursuit of chip cost and power consumption, it is the main driving force for the continuous increase in chip process requirements, which makes the chip defect size requirements higher and higher. Therefore, accurately identifying the type and size of defects is an important factor in improving product yield. In order to improve product yield and reduce production costs, the wafer defect detection system is one of the keys to process control and yield management in the semiconductor manufacturing process.

[0003] During the wafer inspection process, the focal depth of the high-resolution objective lens is short and is affected by the platform flatness and wafer warpage. In order to obtain better imaging quality and defect detection sensitivity, it is necessary to keep the wafer surface in the focal plane or focal depth of the objective lens.

[0004] The focusing of the wafer surface is usually achieved based on a defocus calibration curve, but different wafers have different pattern shapes and different reflectivities. The defocus calibration curves obtained based on wafers with different pattern shapes and different reflectivities will also be different, which will affect the focusing of the wafer surface. Summary of the invention

[0005] The present invention provides a focusing device, a focusing method, a system and a computer storage medium for wafer detection, so as to solve the problem in the prior art that different wafers have different pattern shapes and different reflectivities, which affects the focusing of the wafer surface.

[0006] In a first aspect, the present invention provides a focusing device for wafer inspection, comprising a light source emitting device, a first collimating lens, a first mask, a semi-transparent and semi-reflective prism, a plurality of second collimating lenses, a microscope objective lens, a converging lens and a photodetector;

[0007] The light beam emitted by the light source emitting device is collimated by the first collimating lens and then incident on the first mask to generate a linear array stripe structure light with light and dark alternating; the linear array stripe structure light sequentially passes through the semi-transparent and semi-reflective prism, a plurality of second collimating lenses and a microscope objective lens, and converges to the surface of the wafer to be tested;

[0008] The surface of the wafer to be tested reflects the linear array stripe structured light; the reflected linear array stripe structured light passes through the microscope objective, multiple second collimating lenses, semi-transparent and semi-reflective prisms and converging lenses in sequence, and converges to the photodetector; the photodetector converts the linear array stripe structured light into a photocurrent signal to determine the defocus amount of the surface of the wafer to be tested according to the photocurrent signal.

[0009] Optionally, the focusing device for wafer inspection provided in the first aspect further includes an optical switch, and the number of the first collimating lens, the first mask, the semi-transparent and semi-reflective prism, the converging lens and the photodetector are all multiple; the light source emitting device emits a light beam to the optical switch, and the optical switch includes multiple light beam exit channels, each of the light beam exit channels corresponds to one of the first collimating lenses, and each of the first collimating lenses corresponds to one of the first mask;

[0010] The light beam emitted by the light source emitting device is incident on the target first collimating lens through the target light beam exit channel, and after being collimated by the target first collimating lens, is incident on the target first mask to generate a linear array stripe structured light with light and dark alternating.

[0011] The reflected linear array stripe structured light sequentially passes through the microscope objective lens, a plurality of second collimating lenses, a target semi-transparent and semi-reflective prism and a target converging lens, and converges to a target photoelectric detector.

[0012] Optionally, a focusing device for wafer inspection provided in the first aspect further includes a reflector, and the reflector is used to reflect the linear array stripe structure light passing through the multiple second collimating lenses to the microscope objective lens.

[0013] Optionally, the focusing device for wafer inspection provided in the first aspect further includes an optical coupling device, which is used to converge the light beam emitted by the light source emitting device and couple it into the optical fiber input port of the optical switch.

[0014] Optionally, the photodetector is a PD detector or an APD detector.

[0015] In a second aspect, the present invention provides a focusing method, which is applied to the focusing device for wafer detection described in the first aspect, and the focusing method comprises:

[0016] Acquire the focal length of the microscope objective lens, the equivalent focal lengths of the second collimating lenses, and the beam diameter of the linear array stripe structured light;

[0017] When the surface of the wafer to be measured is at the focus of the microscope objective lens, the position of the target stripe in the linear stripe structured light on the light receiving surface of the photodetector is obtained as the first position;

[0018] Acquire the position of the target stripe in the linear stripe structured light in the current state on the light receiving surface of the photodetector as the second position;

[0019] According to the focal length of the microscope objective lens, the equivalent focal length of the second collimating lenses, the beam diameter of the linear array stripe structured light, the first position and the second position, the defocus amount of the surface of the wafer to be measured is determined, so as to adjust the surface of the wafer to be measured to the focal position of the microscope objective lens according to the defocus amount.

[0020] Optionally, determining the defocus amount of the surface of the wafer to be measured according to the focal length of the microscope objective lens, the equivalent focal lengths of the plurality of second collimating lenses, the beam diameter of the linear array stripe structured light, the first position and the second position includes:

[0021] The defocus value δ of the wafer surface to be measured is calculated according to the following formula:

[0022]

[0023] Wherein, Δ is the distance between the first position and the second position; f1 is the focal length of the microscope objective lens; f2 is the equivalent focal length of the plurality of second collimating lenses; and d is the beam diameter of the linear array stripe structured light.

[0024] In a third aspect, the present invention provides a focusing system, which is applied to the focusing device for wafer detection described in the first aspect, and the focusing system comprises:

[0025] A first acquisition module is used to acquire the focal length of the microscope objective lens, the equivalent focal lengths of the second collimating lenses, and the beam diameter of the linear array stripe structured light;

[0026] A second acquisition module is used to acquire the position of the target stripe in the linear array stripe structured light on the light receiving surface of the photodetector as the first position when the surface of the wafer to be measured is at the focus of the microscope objective lens;

[0027] A third acquisition module is used to acquire the position of the target stripe in the linear stripe structured light on the light receiving surface of the photodetector in the current state as a second position;

[0028] A defocus amount determination module is used to determine the defocus amount of the surface of the wafer to be measured according to the focal length of the microscope objective lens, the equivalent focal lengths of the plurality of second collimating lenses, the beam diameter of the linear array stripe structured light, the first position and the second position, so as to adjust the surface of the wafer to be measured to the focal position of the microscope objective lens according to the defocus amount.

[0029] Optionally, the defocus amount determination module includes:

[0030] The defocus amount calculation unit is used to calculate the defocus amount δ of the surface of the wafer to be tested according to the following formula:

[0031]

[0032] Wherein, Δ is the distance between the first position and the second position; f1 is the focal length of the microscope objective lens; f2 is the equivalent focal length of the plurality of second collimating lenses; and d is the beam diameter of the linear array stripe structured light.

[0033] In a fourth aspect, the present invention provides a computer-readable storage medium for storing a computer program; when the computer program is executed by a processor, the steps of the focusing method described in the second aspect are implemented.

[0034] The present invention provides a focusing device, a focusing method, a system and a computer storage medium for wafer detection. In the focusing device, the light beam emitted by the light source emitting device is collimated by the first collimating lens and then incident on the mask to generate a linear array stripe structure light with light and dark alternating therebetween; the linear array stripe structure light sequentially passes through the semi-transparent and semi-reflective prism, a plurality of second collimating lenses and a microscope objective lens, and converges to the surface of the wafer to be tested; the surface of the wafer to be tested reflects the linear array stripe structure light; the reflected linear array stripe structure light sequentially passes through the microscope objective lens, a plurality of second collimating lenses, a semi-transparent and semi-reflective prism and a converging lens, and converges to the photodetector; the photodetector converts the linear array stripe structure light into a photocurrent signal, so as to determine the defocus amount of the surface of the wafer to be tested according to the photocurrent signal. The present invention can provide accurate real-time focusing for different wafers to be tested, overcome the influence of the pattern shape and reflectivity difference of the test point on the wafer on the measurement result in the process of focusing only relying on the defocus relationship calibration curve, and improve the imaging quality and defect detection sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 A schematic structural diagram of a focusing device for wafer inspection provided by an embodiment of the present invention;

[0037] Figure 2 A schematic diagram of the structure of an optical switch provided in an embodiment of the present invention;

[0038] Figure 3 A schematic diagram of a flow chart of a focusing method provided by an embodiment of the present invention;

[0039] Figure 4 A schematic diagram of the structure of a focusing system provided in an embodiment of the present invention.

[0040] Among them, 1. light source emitting device; 2. first collimating lens; 3. first mask; 4. semi-transparent and semi-reflective prism; 5. second collimating lens; 6. microscope objective lens; 7. converging lens; 8. photodetector; 9. wafer to be tested; 10. optical switch; 11. reflector; 12. optical coupling device; 13. second mask. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions 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 are within the scope of protection of the present invention.

[0042] Example 1

[0043] like Figure 1 As shown, this embodiment provides a focusing device for wafer detection, including a light source emitting device 1, a first collimating lens 2, a first mask 3, a semi-transparent and semi-reflective prism 4, a plurality of second collimating lenses 5, a microscope objective 6, a converging lens 7 and a photodetector 8.

[0044] The light beam emitted by the light source emitting device 1 is collimated by the first collimating lens 2 and then incident on the first mask 3 to generate a linear array stripe structured light with alternating light and dark; the linear array stripe structured light passes through the semi-transparent and semi-reflective prism 4, multiple second collimating lenses 5 and the microscope objective lens 6 in sequence, and converges to the surface of the wafer 9 to be tested.

[0045] The surface of the wafer 9 to be tested reflects the linear array stripe structured light; the reflected linear array stripe structured light passes through the microscope objective 6, multiple second collimating lenses 5, the semi-transparent and semi-reflective prism 4 and the converging lens 7 in sequence, and converges to the photodetector 8; the photodetector 8 converts the linear array stripe structured light into a photocurrent signal to determine the defocus amount of the surface of the wafer 9 to be tested according to the photocurrent signal.

[0046] In this embodiment, the focusing device for wafer detection also includes an optical switch 10, a reflector 11 and an optical coupling device 12. The number of the first collimating lens 2, the first mask 3, the semi-transparent and semi-reflective prism 4, the converging lens 7 and the photodetector 8 are all multiple; the light source emitting device 1 emits a light beam to the optical switch 10, and the optical switch 10 includes multiple light beam exit channels, each light beam exit channel corresponds to a first collimating lens 2, and each first collimating lens 2 corresponds to a first mask 3; the light beam emitted by the light source emitting device 1 passes through the target light beam exit channel and is incident on the target first collimating lens 2, and after being collimated by the target first collimating lens 2, it is incident on the target first mask A linear array stripe structured light with alternating light and dark is generated on the plate 3; the reflected linear array stripe structured light passes through the microscope objective 6, multiple second collimating lenses 5, the target semi-transparent and semi-reflective prism 4 and the target converging lens 7 in sequence, and converges to the target photodetector 8; the reflector 11 is used to reflect the linear array stripe structured light passing through the multiple second collimating lenses 5 to the microscope objective 6; the optical coupling device 12 is used to converge the light beam emitted by the light source emitting device 1 and couple it into the optical fiber input port of the optical switch 10; the photodetector 8 is a PD detector or an APD detector.

[0047] The focusing device for wafer inspection provided in this embodiment includes two main optical paths: an optical path from the light source to the end of the wafer to be tested and an optical path from the end of the wafer to be tested to the PD detector. The light source emitting device 1 emits an LED light source, and the LED divergent light beam is converged by the optical fiber coupling device 12 and then coupled into the optical fiber input port of the optical switch 10; the LED light beam emitted through the light beam exit channel is shaped into a light beam with a small divergence angle by the corresponding first collimating lens 2, and then incident on the corresponding first mask 3.

[0048] Exemplarily, the focusing device for wafer inspection further includes a plurality of second masks 13. After the reflected linear stripe structured light passes through the semi-transparent and semi-reflective prism 4, it first passes through the second mask 13. If the light and dark interval positions of the reflected linear stripe structured light coincide with those of the second mask 13, the reflected linear stripe structured light passes through the second mask 13 and is incident on the converging lens 7. The light spot formed by the reflected linear stripe structured light passing through the converging lens 7 is located on the photosensitive surface of the PD detector or the APD detector, generating a photocurrent signal, and then the defocus amount of the surface of the wafer 9 to be tested is inferred based on the size of the photocurrent signal.

[0049] The optical switch 10 may be a mechanical optical switch or a MEMS (Micro-Electro-Mechanical System) optical switch. Figure 2As shown in the figure, the working principle of the MEMS optical switch mainly involves moving or changing the angle of the MEMS micromirror through the drive of electrostatic force or magnetic force, so as to switch the input light to different output ends of the optical switch to achieve the switching and on-off of the optical path. This optical switch uses micro-electromechanical system (MEMS) technology to carve a number of tiny mirrors on the silicon crystal, and through the action of electrostatic force or electromagnetic force, these movable micromirrors are raised, lowered, rotated or moved. This mechanical movement then changes the propagation direction of the input light to achieve the on-off function of the optical path. This working mode of the MEMS optical switch gives it the advantages of low insertion loss, low crosstalk, low polarization sensitivity, etc., and at the same time has the characteristics of high extinction ratio and high switching speed and small size of waveguide switches.

[0050] Example 2

[0051] like Figure 3 As shown, this embodiment provides a focusing method of the focusing device for wafer inspection provided in Embodiment 1, comprising:

[0052] Step 101, obtaining the focal length of the microscope objective lens, the equivalent focal lengths of the second collimating lenses, and the beam diameter of the linear array stripe structured light.

[0053] Step 102 : When the surface of the wafer to be measured is at the focus of the microscope objective lens, the position of the target stripe in the linear stripe structured light on the light receiving surface of the photodetector is obtained as the first position.

[0054] Step 103 , obtaining the position of the target stripe in the linear stripe structured light on the light receiving surface of the photodetector in the current state as the second position.

[0055] Step 104, determining the defocus amount of the surface of the wafer to be measured according to the focal length of the microscope objective, the equivalent focal lengths of the plurality of second collimating lenses, the beam diameter of the linear array stripe structured light, the first position and the second position, so as to adjust the surface of the wafer to be measured to the focal position of the microscope objective according to the defocus amount.

[0056] Exemplarily, the defocus amount δ of the surface of the wafer to be measured is calculated according to the following formula:

[0057]

[0058] Wherein, Δ is the distance between the first position and the second position; f1 is the focal length of the microscope objective lens; f2 is the equivalent focal length of the plurality of second collimating lenses; and d is the beam diameter of the linear array stripe structured light. In this embodiment, the specific value of the target stripe movement amount (i.e., the distance between the first position and the second position) is equivalent to the magnitude of the photocurrent signal.

[0059] In summary, the focusing method provided in this embodiment can provide accurate real-time focusing for different wafers to be tested, overcome the influence of the pattern shape and reflectivity differences of the test points on the wafer on the measurement results during the focusing process relying only on the defocus relationship calibration curve, and improve the imaging quality and defect detection sensitivity.

[0060] Example 3

[0061] Based on the same inventive concept as Example 2, this embodiment provides a focusing system. Since the principle of solving the problem by this system is similar to the focusing method provided in the aforementioned Example 2, the implementation of this system can refer to the implementation of the focusing method provided in Example 2.

[0062] like Figure 4 As shown, the focusing system comprises:

[0063] The first acquisition module 10 is used to acquire the focal length of the microscope objective lens, the equivalent focal lengths of the second collimating lenses, and the beam diameter of the linear array stripe structured light.

[0064] The second acquisition module 20 is used to acquire the position of the target stripe in the linear stripe structured light on the light receiving surface of the photodetector as the first position when the surface of the wafer to be measured is at the focus of the microscope objective lens.

[0065] The third acquisition module 30 is used to acquire the position of the target stripe in the linear stripe structured light on the light receiving surface of the photodetector in the current state as the second position.

[0066] The defocus determination module 40 is used to determine the defocus of the surface of the wafer to be measured according to the focal length of the microscope objective, the equivalent focal lengths of the plurality of second collimating lenses, the beam diameter of the linear array stripe structured light, the first position and the second position, so as to adjust the surface of the wafer to be measured to the focal position of the microscope objective according to the defocus.

[0067] Exemplarily, the defocus amount determination module includes:

[0068] The defocus amount calculation unit is used to calculate the defocus amount δ of the surface of the wafer to be tested according to the following formula:

[0069]

[0070] Wherein, Δ is the distance between the first position and the second position; f1 is the focal length of the microscope objective lens; f2 is the equivalent focal length of the plurality of second collimating lenses; and d is the beam diameter of the linear array stripe structured light.

[0071] For more specific working processes of the above modules, please refer to the corresponding contents disclosed in Example 2, which will not be repeated here.

[0072] Example 4

[0073] This embodiment provides a computer device, including a processor and a memory; wherein the processor implements the steps of the focusing method described in Embodiment 2 when executing a computer program stored in the memory.

[0074] For more specific details of the above method, please refer to the corresponding contents disclosed in Example 2, which will not be repeated here.

[0075] Example 5

[0076] This embodiment provides a computer-readable storage medium for storing a computer program; when the computer program is executed by a processor, the steps of the focusing method described in Embodiment 2 are implemented.

[0077] For more specific details of the above method, please refer to the corresponding contents disclosed in Example 2, which will not be repeated here.

[0078] Example 6

[0079] This embodiment provides a computer program product, including computer executable instructions or a computer program. When the computer executable instructions or the computer program are executed by a processor, the steps of the focusing method described in Embodiment 2 are implemented.

[0080] For more specific details of the above method, please refer to the corresponding contents disclosed in Example 2, which will not be repeated here.

[0081] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the systems, devices, storage media, and computer program products disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0082] Those skilled in the art can clearly understand that the technology in the embodiments of the present invention can be implemented by means of software plus a necessary general hardware platform. Based on this understanding, the technical solution in the embodiments of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which can be stored in a storage medium such as ROM / RAM, a disk, an optical disk, etc., and includes a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment of the present invention or some parts of the embodiments.

[0083] In some embodiments, computer executable instructions may be in the form of a program, software, software module, script or code, written in any form of programming language (including compiled or interpreted languages, or declarative or procedural languages), and may be deployed in any form, including as a stand-alone program or as a module, component, subroutine or other unit suitable for use in a computing environment.

[0084] As an example, computer-executable instructions may, but need not, correspond to a file in a file system, may be stored as part of a file that stores other programs or data, such as in one or more scripts in a HyperText Markup Language (HTML) document, in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files storing one or more modules, subroutines, or code portions).

[0085] As an example, computer executable instructions may be deployed to be executed on one electronic device, or on multiple electronic devices located at one site, or on multiple electronic devices distributed at multiple sites and interconnected by a communication network.

[0086] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A focusing device for wafer inspection, characterized in that: It includes a light source emitting device, a first collimating lens, a first mask, a semi-transparent and semi-reflective prism, a plurality of second collimating lenses, a microscope objective lens, a converging lens and a photoelectric detector; The light beam emitted by the light source emitting device is collimated by the first collimating lens and then incident on the first mask to generate a linear array stripe structured light with alternating bright and dark colors; The linear array stripe structured light sequentially passes through the semi-transparent and semi-reflective prism, a plurality of second collimating lenses and a microscope objective lens, and converges to the surface of the wafer to be measured; The surface of the wafer to be tested reflects the linear array stripe structure light; the reflected linear array stripe structure light passes through the microscope objective lens, a plurality of second collimating lenses, a semi-transparent and semi-reflective prism and a converging lens in sequence, and converges to the photodetector; The photodetector converts the linear array stripe structure light into a photocurrent signal to determine the defocus amount of the surface of the wafer to be measured according to the photocurrent signal.

2. The focusing device according to claim 1, characterized in that: It also includes an optical switch, wherein the first collimating lens, the first mask, the semi-transparent and semi-reflective prism, the converging lens and the photodetector are all multiple in number; the light source emitting device emits a light beam to the optical switch, and the optical switch includes multiple light beam exit channels, each of the light beam exit channels corresponds to one of the first collimating lenses, and each of the first collimating lenses corresponds to one of the first mask; The light beam emitted by the light source emitting device is incident on the target first collimating lens through the target light beam exit channel, and after being collimated by the target first collimating lens, is incident on the target first mask to generate a linear array stripe structured light with light and dark alternating. The reflected linear array stripe structured light sequentially passes through the microscope objective lens, a plurality of second collimating lenses, a target semi-transparent and semi-reflective prism and a target converging lens, and converges to a target photoelectric detector.

3. The focusing device according to claim 1, characterized in that: It also includes a reflector, which is used to reflect the linear array stripe structure light passing through the plurality of second collimating lenses to the microscope objective lens.

4. The focusing device according to claim 2, characterized in that: It also includes an optical coupling device, which is used to converge the light beam emitted by the light source emitting device and couple it into the optical fiber input port of the optical switch.

5. The focusing device according to claim 1, characterized in that: The photoelectric detector is a PD detector or an APD detector.

6. A focusing method, characterized in that: Applicable to the focusing device for wafer inspection as claimed in any one of claims 1 to 5, the focusing method comprising: Acquire the focal length of the microscope objective lens, the equivalent focal lengths of the second collimating lenses, and the beam diameter of the linear array stripe structured light; When the surface of the wafer to be measured is at the focus of the microscope objective lens, the position of the target stripe in the linear stripe structured light on the light receiving surface of the photodetector is obtained as the first position; Acquire the position of the target stripe in the linear stripe structured light in the current state on the light receiving surface of the photodetector as the second position; According to the focal length of the microscope objective lens, the equivalent focal length of the second collimating lenses, the beam diameter of the linear array stripe structured light, the first position and the second position, the defocus amount of the surface of the wafer to be measured is determined, so as to adjust the surface of the wafer to be measured to the focal position of the microscope objective lens according to the defocus amount.

7. The focusing method according to claim 6, characterized in that: The method of determining the defocus amount of the surface of the wafer to be measured according to the focal length of the microscope objective lens, the equivalent focal lengths of the plurality of second collimating lenses, the beam diameter of the linear array stripe structured light, the first position and the second position comprises: The defocus value δ of the wafer surface to be measured is calculated according to the following formula: Wherein, Δ is the distance between the first position and the second position; f1 is the focal length of the microscope objective lens; f2 is the equivalent focal length of the plurality of second collimating lenses; and d is the beam diameter of the linear array stripe structured light.

8. A focusing system, characterized in that: Applicable to the focusing device for wafer inspection as claimed in any one of claims 1 to 5, the focusing system comprising: A first acquisition module is used to acquire the focal length of the microscope objective lens, the equivalent focal lengths of the second collimating lenses, and the beam diameter of the linear array stripe structured light; A second acquisition module is used to acquire the position of the target stripe in the linear array stripe structured light on the light receiving surface of the photodetector as the first position when the surface of the wafer to be measured is at the focus of the microscope objective lens; A third acquisition module is used to acquire the position of the target stripe in the linear stripe structured light on the light receiving surface of the photodetector in the current state as a second position; A defocus amount determination module is used to determine the defocus amount of the surface of the wafer to be measured according to the focal length of the microscope objective lens, the equivalent focal lengths of the plurality of second collimating lenses, the beam diameter of the linear array stripe structured light, the first position and the second position, so as to adjust the surface of the wafer to be measured to the focal position of the microscope objective lens according to the defocus amount.

9. The focusing system according to claim 8, characterized in that: The defocus amount determination module comprises: The defocus amount calculation unit is used to calculate the defocus amount δ of the surface of the wafer to be tested according to the following formula: Wherein, Δ is the distance between the first position and the second position; f1 is the focal length of the microscope objective lens; f2 is the equivalent focal length of the plurality of second collimating lenses; and d is the beam diameter of the linear array stripe structured light.

10. A computer-readable storage medium, characterized in that: Used to store computer programs; when the computer programs are executed by a processor, the steps of the focusing method described in any one of claims 6 to 7 are implemented.

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