Focusing system for wafer inspection, wafer inspection system and focusing method

Abstract

A focusing system for wafer detection, a wafer detection system and a focusing method, the focusing system for wafer detection comprising: a mobile device, and a plurality of optical path components arranged on the mobile device, the plurality of optical path components having different magnifications for the object to be detected on the wafer; wherein the mobile device is used to adjust the distance between the optical path components in the plurality of optical path components and the object to be detected on the wafer for multiple times to obtain imaging information of the object to be detected on the wafer; wherein the distance between at least one of the plurality of optical path components and the object to be detected on the wafer is adjusted at one time, and different distances between the optical path component and the object to be detected on the wafer correspond to imaging information of different precisions of the object to be detected on the wafer. The technical solution of the present invention is adopted to realize one machine with multiple functions, and can detect objects to be detected of different sizes at the same time, expand the detection range, and improve the detection accuracy, which has a high cost performance.

Description

Technical Field

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

[0002] As a key link in semiconductor manufacturing, wafer inspection requires the use of a focusing system; a focusing system is a system that focuses the incident light used to inspect the wafer onto the wafer surface. With the rapid development of semiconductor manufacturing technology, the precision requirements of the focusing system are becoming increasingly significant. Therefore, how to improve the precision of the focusing system has become a technical problem that technicians in this field need to solve urgently. Summary of the invention

[0003] In view of the shortcomings of the existing methods, the present invention proposes a wafer detection precision focusing system, a wafer detection system and a focusing method, which are used to improve the precision of the focusing system and thus improve the effect of wafer detection.

[0004] In view of this, the present invention provides a focusing system for wafer detection, comprising: a mobile device, and a plurality of optical path components arranged on the mobile device, wherein the plurality of optical path components have different magnification factors for the object to be measured on the wafer; wherein the mobile device is used to adjust the distance between the optical path components among the plurality of optical path components and the object to be measured on the wafer for multiple times to obtain imaging information of the object to be measured on the wafer; wherein the distance between at least one optical path component among the plurality of optical path components and the object to be measured on the wafer is adjusted at one time, and different distances between the optical path component and the object to be measured on the wafer correspond to imaging information of different precisions of the object to be measured on the wafer.

[0005] Optionally, the moving device is used to multiple times adjust the distance between an optical path component among the multiple optical path components and the object to be measured on the wafer, including: multiple times adjusting the distance between an optical path component among the multiple optical path components and the object to be measured on the wafer in a first direction and a second direction.

[0006] Optionally, the moving device includes a translation stage that moves in a first direction, a stepper motor, and a moving axis that moves in a second direction; the translation stage is used to move and position the wafer in the first direction; the multiple optical path components are arranged on the moving axis, and the moving axis moves in the second direction to drive the multiple optical path components to move in the second direction; the stepper motor is used to control the movement of the translation stage and the moving axis.

[0007] Optionally, the multiple different optical path components include a first optical path component, a second optical path component and a main optical path component; the magnification of the first optical path component on the object to be measured on the wafer is smaller than that of the second optical path component.

[0008] Optionally, the main light path component includes a main light path camera, a main light path objective lens, and a light source sensor; the light source sensor provides incident light to the object to be measured on the wafer through the main light path objective lens; after the incident light is reflected by the object to be measured on the wafer, the reflected light is transmitted to the main light path objective lens; the main light path camera is used to collect the reflected light passing through the main light path objective lens, and the reflected light represents the imaging information of the object to be measured on the wafer; the first light path component includes a first light source, a first camera, and a first objective lens; the second light path component includes a second light source, a second camera, and a second objective lens; the first light source The first objective lens is used to provide incident light to the object to be measured on the wafer; after the incident light is reflected by the object to be measured on the wafer, the reflected light is transmitted to the first objective lens; the first camera is used to collect the reflected light passing through the first objective lens, and the reflected light represents the imaging information of the object to be measured on the wafer; the second light source is used to provide incident light to the object to be measured on the wafer through the second objective lens; after the incident light is reflected by the object to be measured on the wafer, the reflected light is transmitted to the second objective lens; the second camera is used to collect the reflected light passing through the second objective lens, and the reflected light represents the imaging information of the object to be measured on the wafer.

[0009] Optionally, the main optical path component also includes: a mechanical fine-tuning module and a piezoelectric ceramic displacement device; the mechanical fine-tuning module is used to perform a first calibration on the distance between the main optical path objective lens and the object to be measured on the wafer, and different distances between the main optical path objective lens and the object to be measured on the wafer correspond to different objects to be measured on the wafer; the piezoelectric ceramic displacement device is placed on the main optical path objective lens, and is used to perform a second calibration on the distance between the main optical path objective lens and the object to be measured on the wafer, and the accuracy of the second calibration is higher than that of the first calibration.

[0010] Optionally, a spectral distance measurement system is provided on the moving axis for measuring the distance from the objective lens in each optical path component to the object to be measured on the wafer;

[0011] The spectral ranging system includes a spectral sensor, a transmitter and a receiver; the spectral sensor provides the transmitter with light signals of different frequencies as incident light for different objects to be measured on the wafer; the receiver is used to receive reflected light signals from different objects to be measured on the wafer; the light intensity information of the reflected light signal represents the distance between the different objects to be measured on the wafer and the spectral sensor.

[0012] Optionally, it also includes: a control system; the control system is used to control the stepper motor.

[0013] Optionally, it also includes: an optical system and a single-axis motion platform; the optical system is used to focus the light signal of the light source sensor onto the object to be measured on the wafer; the single-axis motion platform is used to manually calibrate the distance between the second objective lens and the object to be measured on the wafer.

[0014] The present invention also provides a wafer detection system, comprising: a focusing system and a data processing system; the focusing system is any one of the focusing systems described above; the data processing system is used to analyze and process imaging information of an object to be detected on a wafer.

[0015] Correspondingly, the present invention also provides a focusing method for wafer detection, which is applied to the focusing system described in any one of the above items; it includes: determining an optical path component with the same magnification factor among multiple optical path components, and adjusting the distance between the optical path component with the same magnification factor and the object to be measured on the wafer multiple times until the imaging information of the object to be measured on the wafer obtained meets the clarity requirements; and determining an optical path component with different magnification factors among multiple optical path components, and adjusting the distance between the optical path components with different magnification factors and the wafer surface multiple times until the imaging information of the object to be measured on the wafer obtained meets the clarity requirements.

[0016] By adopting the above technical solution, multiple optical path components are set, and the optical path components have different magnification factors for the object to be measured. The moving device repeatedly adjusts the distance between the multiple optical path components and the object to be measured on the wafer to find an optical path component suitable for the object to be measured, thereby improving the focusing accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figures 1 to 7 is a focusing schematic diagram of a wafer inspection according to the first embodiment of the present invention;

[0018] Figure 8 It is a structural diagram of a focusing system for wafer inspection of the present invention;

[0019] Fig. 9 is an exploded diagram of a focusing system for wafer inspection of the present invention;

[0020] Fig.10 It is a principle diagram of objective lens imaging of each optical path component of the present invention;

[0021] Fig.11 It is the principle diagram of the mechanical fine-tuning module of the present invention;

[0022] Fig.12 It is the principle diagram of the spectrum ranging system of the present invention;

[0023] Fig.13 This is a schematic diagram of the inclination measurement principle of each objective lens and wafer surface of the focusing system of the present invention;

[0024] Figures 14 to 16 This is a flow chart of the focusing method for wafer detection according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0026] Regarding existing wafer inspection, the following focusing system is used:

[0027] The traditional mechanical focusing system achieves focusing by manually adjusting the aperture to adjust the lens position. The mechanical focusing system is subject to mechanical wear, which limits the mechanical movement accuracy and stability, making it difficult to meet high-precision detection requirements. At the same time, the debugging and maintenance costs of the mechanical focusing system are high after mechanical wear.

[0028] Ultrasonic focusing systems use the characteristics of ultrasound to achieve non-contact focusing. However, the performance of such systems will be greatly affected when facing complex environments (such as high temperature, high humidity, etc.). In order to maintain a suitable ultrasonic measurement environment, the cost of the ultrasonic focusing system increases, which is not conducive to large-scale applications and is difficult to meet the needs of high stability.

[0029] Active optical focusing system: Through an active control system, the lens parameters are automatically adjusted to achieve focusing according to the clarity of the image. Although this type of system has a certain degree of accuracy, its debugging complexity is relatively high, and it performs poorly in a dynamic environment (detection when the wafer is moving). The response speed of the active optical focusing system is relatively slow compared to the movement of the wafer, and it is difficult to meet the needs of high-speed real-time detection.

[0030] Existing wafer detection focusing systems often fail to meet the requirements of high precision, high speed and high stability, becoming a bottleneck restricting the improvement of semiconductor manufacturing processes. To address this problem, an embodiment of the present invention provides a wafer detection focusing system that can monitor the wafer position and surface morphology in real time to achieve high-precision and high-stability detection; it avoids the mechanical wear and precision loss problems of traditional mechanical focusing systems; the focusing system of the present invention adopts intelligent control, reduces the complexity of operation, and improves production efficiency.

[0031] The invention has strong environmental adaptability and can maintain stable performance under different process conditions. The focusing system of the invention has high cost performance and is suitable for large-scale application and promotion.

[0032] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the following will be combined with the embodiments of the present invention. Figures 1 to 16, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0033] Embodiment 1:

[0034] This embodiment provides a focusing system for wafer inspection, including: a moving device, and a plurality of optical path components disposed on the moving device, wherein the plurality of optical path components have different magnification factors for an object to be inspected on a wafer.

[0035] Wherein, the moving device is used to adjust the distance between the optical path components among the multiple optical path components and the object to be measured on the wafer multiple times to obtain imaging information of the object to be measured on the wafer; wherein, the distance between at least one optical path component among the multiple optical path components and the object to be measured on the wafer is adjusted at one time, and different distances between the optical path component and the object to be measured on the wafer correspond to imaging information of different precisions of the object to be measured on the wafer.

[0036] The objects to be tested are distributed in any area on the wafer. The objects to be tested on the wafer may be transmission signal lines, metal film layers, insulating film layers, semiconductor grooves, photoresist coatings, etc. The imaging information of the objects to be tested on the wafer includes the morphological information of the objects to be tested, which may be the line width and line spacing of metal traces, film thickness, via size, film defects (such as short circuits, excessive or incomplete etching of the film, electrostatic damage), etc.

[0037] Using the focusing system as described above, the range of the object to be tested on the wafer is determined by the naked eye, optical equipment, or electrical equipment before wafer inspection. According to the size of the object to be tested, at least one suitable optical path component is selected to focus and detect the object to be tested. Figures 1 to 7 Provide explanation.

[0038] If the size of the object A1 to be measured is micrometer level or above, one of the multiple optical path components is adjusted once by the mobile device to the position of the object A1 to be measured on the wafer 100 (within the range B), and the mobile device adjusts the distance between the optical path component and the object A1 to be measured multiple times; for the remaining optical path components, the above steps are repeated until the optical path component C1 suitable for the magnification of the object A1 to be measured is found among the multiple optical path components, and an image of the object A1 to be measured that meets the imaging clarity requirements is obtained, such as Figure 1 As shown, Figure 2 yes Figure 1 Top view of the .

[0039] If the size of the object to be measured is below the micron level, segmented control is used, that is: the range B where the object A2 to be measured is located on the wafer 100 is first obtained through the optical path component, which is the so-called coarse alignment. Then the specific position D of the object to be measured within the range B is obtained, which is the so-called precision focusing, and finally the imaging information of the object to be measured at the specific position D is obtained, which is precise control. Specifically as follows: first, a mobile device is used to adjust one of the multiple optical path components to the range B where the object A2 to be measured is located at one time, and the mobile device adjusts the distance between the optical path component and the range B where the object A2 to be measured is located multiple times; for the remaining optical path components, the above steps are repeated until an optical path component C2 suitable for range B is found among the multiple optical path components, that is, an optical path component is found that makes the clarity of the imaging information of range B meet the requirements, such as Figure 3 As shown, Figure 4 yes Figure 3 Top view of the .

[0040] Then, one of the multiple optical path components is adjusted once by the mobile device to the range B where the object to be measured is located. The mobile device adjusts the distance between the optical path component and the range B multiple times. The above steps are repeated for the remaining optical path components until an optical path component suitable for the specific position D in the range B is found among the multiple optical path components, that is, an optical path component C3 is found so that the clarity of the imaging information of the specific position D meets the requirements, that is, the imaging information of the object to be measured A2 is found in the optical path component C3. Figure 5 As shown, Figure 6 yes Figure 5 Top view of the .

[0041] Finally, the mobile device adjusts one of the multiple optical path components at a time to the specific position D of the object A2 to be measured, and the mobile device adjusts the distance between the optical path component and the specific position D multiple times. The above steps are repeated for the remaining optical path components until an optical path component suitable for the object A2 to be measured at the specific position D is found, that is, an optical path component that makes the clarity of the imaging information of the object A2 to be measured at the specific position D meet the requirements is found. The above completes the focusing and detection of the object A2 to be measured, as shown in FIG. Figure 7 shown.

[0042] In addition, different distances between the optical path component and the object to be measured on the wafer 100 correspond to imaging information of the object to be measured with different precisions, that is, when the distances between the optical path component and the object to be measured are different with the same magnification, the imaging precision of the object to be measured in the optical path component is different.

[0043] The focusing system of the embodiment of the present invention is used to select a suitable optical path component according to the different sizes of the objects to be measured. The object to be measured can be focused and then detected by at least one optical path component, or the object to be measured can be focused and then detected by multiple optical path components. This realizes a one-machine multi-function, and can detect objects of different sizes at the same time, expand the detection range, and improve the detection accuracy, which has a high cost performance.

[0044] As an optional embodiment, the moving device is used to multiple times adjust the distance between an optical path component among the multiple optical path components and the object to be measured on the wafer, including: multiple times adjusting the distance between an optical path component among the multiple optical path components and the object to be measured on the wafer in a first direction and a second direction.

[0045] The first direction is the adjustment direction of the wafer 100, the second direction is the adjustment direction of the plurality of optical path components, and the first direction and the second direction are perpendicular; in an optional implementation, the first direction is a horizontal direction, and the second direction is a vertical direction; in other embodiments, the first direction is a vertical direction, and the second direction is a horizontal direction;

[0046] The direction of the wafer 100 is adjusted by moving it multiple times in the first direction so that it is opposite to at least one of the multiple optical path components; the distance between the aforementioned at least one optical path component and the object to be measured in the second direction is adjusted multiple times in the second direction to obtain imaging information of the object to be measured on the wafer to meet the definition requirement. In its embodiment, multiple optical path components can also be adjusted to be opposite to the wafer 100.

[0047] As an alternative implementation, refer to Figure 8 The moving device includes a translation stage 200 that moves in a first direction, a stepper motor, and a moving shaft 201 that moves in a second direction; the translation stage 200 is used to move and position the wafer 100 in the first direction; the multiple optical path components are arranged on the moving shaft 201, and the moving shaft 201 drives the multiple optical path components to move in the second direction; the stepper motor is used to control the movement of the translation stage 200 and the moving shaft 201.

[0048] The translation stage 200 is provided with a plurality of vacuum adsorption holes, and the wafer 100 is fixed on the translation stage 200 by vacuum adsorption, so as to prevent the wafer 100 from sliding on the translation stage 200 when the translation stage 200 drives the wafer 100 to move in the first direction, which is not conducive to the optical path component obtaining the specific position of the object to be measured on the wafer. When the translation stage 200 moves quickly, there is a risk that the sliding wafer 100 hits the edge of the translation stage 200 and causes the wafer to be damaged. In an optional implementation, the surface material of the translation stage 200 can be a metal material, such as aluminum or aluminum alloy. In other embodiments, the surface material of the translation stage 200 can also be an antistatic organic glass plate or an antistatic polyvinyl chloride plate.

[0049] The number of the movable shaft 201 is single, and the positions of the multiple optical path components on the movable shaft 201 can be set according to actual needs. The movable shaft 201 can drive the multiple optical path components to move together in the second direction; in the aforementioned moving device driving the movement of the multiple optical path components in the second direction, that is, the moving device drives the moving shaft 201 to move, the movable shaft 201 drives the movement of the multiple optical path components in the second direction. In other embodiments, there can be multiple movable shafts 201, which can be one of the multiple movable shafts, driving some of the multiple optical path components to move in the second direction; in other embodiments, the number of the movable shafts 201 can be the same as the number of the multiple optical path components, so that one movable shaft drives one optical path component to move in the second direction, thereby reducing the wear rate of the movable shaft 201 when a single movable shaft 201 drives all optical path components to move.

[0050] The stepper motor itself has the advantages of no setting time (the stepper motor needs a short time to quickly reach a stable state and can adapt to real-time detection), high control accuracy and high in-situ stability. It can better control the movement of the translation stage 200 and the moving axis 201, and meet the requirements of high precision, high speed, high stability and real-time detection during wafer detection and focusing. At the same time, the use of a stepper motor can accurately focus on and detect each object to be tested on the wafer, thereby further expanding the detection range.

[0051] As an alternative implementation, refer to Fig. 9 , the multiple different optical path components include a first optical path component 301, a second optical path component 302 and a main optical path component 303; the first optical path component 301 has a smaller magnification of the object to be measured on the wafer 100 than the second optical path component 302; the second optical path component 302 has a smaller magnification of the object to be measured on the wafer 100 than the main optical path component 303; in an optional implementation, the number of multiple optical path components can be 3, and in other embodiments, the number of multiple optical path components can be greater than 3, and the number of optical path components is selected according to the focusing requirements during wafer inspection.

[0052] When the wafer is detected and focused, at least one optical path component that is adapted to the size of the object to be detected is selected from a plurality of optical path components according to the size of the object to be detected; in an optional implementation, when the size of the object to be detected is greater than or equal to 3 microns, the first optical path component 301 is selected to focus on the object to be detected; when the size of the object to be detected is greater than or equal to 1 micron and less than 3 microns, the second optical path component 302 is selected to focus on the object to be detected; when the size of the object to be detected is less than 1 micron, the first optical path component 301, the second optical path component 302 and the main optical path component 303 are selected to focus on the object to be detected together, wherein the first optical path component 301 It is used to focus and find the range where the object to be measured is located on the wafer 100, the second optical path component 302 is used to focus and determine the specific position of the object to be measured within the range, and the main optical path component 303 is used to focus the imaging information of the object to be measured at the specific position; in summary, the focusing system of the wafer detection can realize one machine with multiple functions, is suitable for objects to be measured of different sizes, and expands the detection range; in addition, the first optical path component 301 and the second optical path component 302 cooperate with the main optical path component 303, compared with simply using the main optical path component 303 to focus, which improves the focusing speed of the object to be measured and improves the detection efficiency.

[0053] As an alternative implementation, continue to refer to Fig. 9 , the main light path component 303 includes a main light path camera 304, a main light path objective lens 305, and a light source sensor 306;

[0054] The light source sensor 306 provides incident light to the object to be measured on the wafer through the main light path objective lens 305; after the incident light is reflected by the object to be measured on the wafer, the reflected light is transmitted to the main light path objective lens 305; the main light path camera 304 is used to collect the reflected light passing through the main light path objective lens 305 in real time, and the reflected light represents the imaging information of the object to be measured on the wafer; the first light path component 301 includes a first light source 307, a first camera 308, and a first objective lens 309; the second light path component 302 includes a second light source 310, a second camera 311, and a second objective lens 312;

[0055] The first light source 307 provides incident light to the object to be measured on the wafer through the first objective lens 309; after the incident light is reflected by the object to be measured on the wafer, the reflected light is transmitted to the first objective lens 309; the first camera 308 is used to collect the reflected light passing through the first objective lens 309 in real time, and the reflected light represents the imaging information of the object to be measured on the wafer;

[0056] The second light source 310 provides incident light to the object to be measured on the wafer through the second objective lens 312; after the incident light is reflected by the object to be measured on the wafer, the reflected light is transmitted to the second objective lens 312; the second camera 311 is used to collect the reflected light passing through the second objective lens 312 in real time, and the reflected light represents the imaging information of the object to be measured on the wafer.

[0057] The imaging principle of the main light path camera 304, the first camera 308 and the second camera 311 to obtain the imaging information of the object to be measured 401 on the wafer is the objective lens imaging principle, and the objective lens includes the first objective lens 309, the second objective lens 312 and the main light path objective lens 305. Fig.10 As shown, the image 402 of the object 401 to be measured after passing through the objective lens 400 is obtained, and the image 402 can be acquired by the first camera 308 , the second camera 311 and the main light path camera 304 .

[0058] As an alternative implementation, continue to refer to Fig. 9 , the main optical path component also includes: a mechanical fine-tuning module 313 and a piezoelectric ceramic displacement device 314;

[0059] The mechanical fine-tuning module 313 is used to perform a first calibration on the distance between the main light path objective lens 305 and the object to be measured on the wafer. Different distances between the main light path objective lens 305 and the object to be measured on the wafer correspond to different objects to be measured on the wafer. The piezoelectric ceramic displacement device 314 is placed on the main light path objective lens 305 and is used to perform a second calibration on the distance between the main light path objective lens 305 and the object to be measured on the wafer. The accuracy of the second calibration is higher than that of the first calibration.

[0060] The piezoelectric ceramic displacement device 314 is placed on the main light path objective lens 305, and is used to accurately calibrate the distance between the main light path objective lens and the object to be measured on the wafer. The adjustment accuracy of the piezoelectric ceramic displacement device 314 is better than that of the mechanical fine-tuning module 313. For example, the mechanical fine-tuning module 313 is suitable for focusing adjustment of objects to be measured at the micron level and above on the wafer, and the piezoelectric ceramic displacement device 314 is suitable for focusing adjustment of objects to be measured below the micron level on the wafer. In an optional implementation, such as Fig.11 As shown, when the displacement stage 200 switches the first object to be measured W1 under the main light path objective lens 305 to the second object to be measured W2, the first object to be measured W1 and the second object to be measured W2 are not in the same plane, and there is a height difference d1. Then, the distances between the main light path objective lens 305 and the first object to be measured W1 and the second object to be measured W2 are different, namely, d2 and d3. If the imaging clarity of the second object to be measured W2 in the main light path camera 304 does not meet the requirements, the distance between the second object to be measured W2 and the main light path objective lens 305 needs to be adjusted by the mechanical fine-tuning module 313 until the imaging clarity of the second object to be measured W2 in the main light path camera 304 meets the requirements. In other embodiments, the distance between the second object to be measured W2 and the main light path objective lens 305 can also be adjusted by the piezoelectric ceramic displacement device 314. In other embodiments, the mechanical fine-tuning module 313 can also be used to adjust the distances between the first objective lens 309 and the second objective lens 312 and the object to be measured. The piezoelectric ceramic displacement device 314 can also be used to adjust the distance between the first objective lens 309 and the second objective lens 312 and the object to be measured.

[0061] The piezoelectric ceramic in the piezoelectric ceramic displacement device 314 is a special material with sensitive physical properties, that is, when voltage is applied to it, electric polarization will occur inside the piezoelectric ceramic material, causing the length or shape of the material to change, and the piezoelectric ceramic will produce nanometer-level displacement. By utilizing this characteristic of the piezoelectric ceramic material, the movement of each objective lens is controlled by the piezoelectric ceramic displacement device 314, and the distance between each objective lens and the object to be measured on the wafer is adjusted with high precision, thereby achieving high-precision focusing of the object to be measured and improving the accuracy of data detection.

[0062] As an alternative implementation, continue to refer to Figure 8 and Fig. 9 The moving axis 201 is also provided with a spectral distance measuring system 315 for measuring the distance from each objective lens in each optical path component to the object to be measured on the wafer; Fig.12 As shown, the spectral distance measurement system includes a spectral sensor 500, a transmitter and a receiver, and the spectral sensor 500, the transmitter and the receiver are used to measure the distance between the spectral sensor 500 and the surface of the wafer 100 in real time. Fig.12 As shown, the spectral distance measurement system 315 is pre-set with a distance limit e1 between the spectral sensor 500 and the surface of the wafer 100 as a reference. When the distance between the spectral sensor 500 and the surface of the wafer 100 reaches the limit value e1 from e2, the spectral sensor 500 controls the system through the data processing system feedback. At this time, the distance between the main optical path objective lens 305 and the surface of the wafer 100 also reaches the limit value e3, and the control system controls the moving axis 201 to stop moving to prevent each objective lens from colliding with the surface of the wafer 100. The spectral distance measurement system 500 also measures the limit distance between the first objective lens 309, the second objective lens 312 and the surface of the wafer 100. In addition, no matter what material the object to be measured is, as long as it can reflect light, the spectral distance measurement system 315 can be used to measure the distance between it and the spectral sensor 500, thereby expanding the range of objects to be measured, and realizing the measurement of the distance between each objective lens and the object to be measured on the wafer 100 under different environments, having strong environmental adaptability and maintaining stable performance under different process conditions.

[0063] The spectral sensor 500 provides a transmitter with light signals of different frequencies as incident light for different objects to be measured on the wafer; the receiver is used to receive reflected light signals from different objects to be measured on the wafer; the light intensity information of the reflected light signal represents the distance between the different objects to be measured on the wafer and the spectral sensor 500, and the larger the light intensity value of the reflected light signal, the closer the distance between the spectral sensor 500 and the wafer surface.

[0064] The spectral sensor 500 provides light signals of different frequencies, which are transmitted to the film layer to be tested on the surface of the wafer through the transmitter, and reflected light signals of different intensities are obtained. By testing the intensity of the reflected light signal, the maximum reflected light signal intensity is found, thereby obtaining the incident light signal that best matches the aforementioned film layer. Through this method, the optimal incident light signal corresponding to all film layers is found, thereby achieving high-precision testing of the distance between the spectral sensor 500 and the surface of the wafer 100.

[0065] During the wafer inspection process, the moving shaft 201 drives each optical path component and the spectral distance measurement system 315 to move toward the wafer. The spectral distance measurement system 315 tests the distance between the objective lens of each optical path component and the surface of the wafer in real time to prevent the objective lens of each optical path component from colliding with the wafer and damaging the objective lens and the wafer. When the receiver of the spectral distance measurement system 315 obtains the maximum reflected light intensity signal of the film layer, it indicates that the distance between the objective lens of each optical path component and the wafer has reached the limit, and each optical path component stops moving toward the wafer.

[0066] As an optional embodiment, the focusing system further includes a control system; the control system is used to control the movement of the stepper motor and the moving shaft 201. The control system sends a control signal to the stepper motor, and the stepper motor drives the moving shaft 201 to move in the second direction, thereby driving the movement of each optical path component. In other embodiments, the control system can also control the movement of the mechanical fine-tuning module 313 and the piezoelectric ceramic displacement device 314, as well as the switching between the optical path components of each optical path component. The control system is used to realize self-energization control, which greatly improves the wafer detection efficiency.

[0067] As an optional embodiment, combined with Fig. 9 As shown, the focusing system further includes an optical system and a single-axis motion stage 316; the optical system is used to focus the light signal of the light source sensor 306 onto the object to be measured on the wafer, for example, by focusing through an optical objective lens; before inspecting the wafer, the distance between the second objective lens 312 and the object to be measured on the wafer is first manually calibrated through the single-axis motion stage 316. In other embodiments, the single-axis motion stage 316 can also be used to manually calibrate the distance between the first objective lens 309 and the object to be measured on the wafer.

[0068] Embodiment 2:

[0069] The embodiment of the present invention also provides a wafer detection system, including: a focusing system and a data processing system; the focusing system can be the focusing system described in any one of the aforementioned embodiments; the data processing system is used to analyze and process the imaging information of the object to be tested on the wafer. The first camera 308, the second camera 311, and the main light path camera 304 feed back the imaging information of the object to be tested on the wafer acquired in real time to the data processing system. The data processing system will pre-store the imaging information of the object to be tested before detection, such as the light intensity corresponding to the imaging information of each object to be tested. The data processing system automatically determines and analyzes whether the imaging information of the object to be tested meets the clarity requirements. If the clarity does not meet the requirements, the data processing system sends a signal to the control system to automatically adjust the distance between each objective lens and the wafer, and continue to acquire the imaging information of the object to be tested until the clarity of the object to be tested meets the requirements. By combining the data processing system with the control system, self-energizing control is achieved.

[0070] A focusing method for wafer inspection is applied to the focusing system described in any one of the aforementioned embodiments; comprising: determining an optical path component with the same magnification among multiple optical path components, and adjusting the distance between the optical path component with the same magnification and an object to be measured on the wafer for multiple times until imaging information of the object to be measured on the wafer meets the clarity requirement; and determining optical path components with different magnifications among multiple optical path components, and adjusting the distance between the optical path components with different magnifications and the wafer surface for multiple times until imaging information of the object to be measured on the wafer meets the clarity requirement.

[0071] In order to enable those skilled in the art to more clearly understand and implement the embodiments of the present invention, the following Figures 13 to 16 , the working principle of the focusing system for wafer inspection is described.

[0072] An embodiment of the present invention provides a focusing method for wafer inspection, which is applied to the focusing system in any of the aforementioned embodiments.

[0073] Before the focusing test, the inclination of each objective lens of the focusing system and the wafer surface must be calibrated. Fig.13 As shown, the wafer is placed on the translation stage 200, and a feeler gauge, such as a wedge-shaped feeler gauge 600, is inserted between the first objective lens 309 and the wafer 100. If the readings of the left and right wedge-shaped feeler gauges 600 are not equal and the tilting degree cannot meet the focus system test requirements, the first objective lens 309 or the translation stage 200 is calibrated to a horizontal level with the help of a level meter so that the surface of the first objective lens 309 is parallel to the surface of the wafer. Repeat the above steps to calibrate the second objective lens 312 and the surface of the main optical path objective lens 305 to be parallel to the surface of the wafer.

[0074] First, a focusing method for an object to be measured with a size greater than or equal to 3 microns includes the following steps: Fig.14 As shown:

[0075] Step S10: adjusting the relative position between the first objective lens and the wafer.

[0076] The moving device moves each optical path component to above the displacement stage 200, the control system controls the optical path component to switch to the first optical path component 301, and the moving device drives the displacement stage 200 to move horizontally in the first direction so that the first objective lens 309 faces the object to be measured on the wafer 100;

[0077] Step S11: adjusting the first objective lens to obtain imaging information of the object to be measured.

[0078] The movable axis 201 drives the first objective lens 309 of the first optical path component 301 to move along the second direction perpendicular to the surface of the wafer 100. The movable axis 201 adjusts the distance between the first objective lens 309 and the object to be measured on the wafer for multiple times until the imaging information of the object to be measured on the wafer meets the clarity requirement. The movable axis 201 adopts open-loop logic control during the multiple adjustments, that is, there is no need to feed back the adjustment process to the control system to accurately adjust the distance between the first objective lens 309 and the object to be measured on the wafer.

[0079] Step S12: image processing the imaging information of the object to be measured.

[0080] Image processing is performed on the imaging information of the object to be measured so as to present a clear image of the object to be measured on the first camera 308 .

[0081] Secondly, the focusing method for the object to be measured with a size greater than 1 micron and less than 3 microns includes the following steps: Fig.15 As shown:

[0082] Step S20: adjusting the relative position between the second objective lens and the wafer.

[0083] The moving device moves each optical path component to above the displacement stage 200, the control system controls the optical path component to switch to the second optical path component 302, and the moving device drives the displacement stage 200 to move horizontally in the first direction so that the second objective lens 312 of the second optical path component 302 faces the object to be measured on the wafer;

[0084] Step S21: adjusting the second objective lens to obtain imaging information of the object to be measured.

[0085] The moving axis drives the second objective lens 312 to move perpendicularly to the wafer surface along the second direction. The moving axis adjusts the distance between the second objective lens 312 and the object to be measured on the wafer multiple times until the imaging information of the object to be measured on the wafer meets the clarity requirement. Open-loop logic control is adopted during the multiple adjustments of the moving axis 201, that is, there is no need to feed back the adjustment process to the control system to accurately adjust the distance between the first objective lens 309 and the object to be measured on the wafer.

[0086] Step S22: image processing the imaging information of the object to be measured.

[0087] Image processing is performed on the imaging information of the object to be measured so as to present a clear image of the object to be measured on the second camera 311 .

[0088] Finally, the focusing method for the object to be measured with a size less than 1 micron includes the following steps: Fig.16 As shown:

[0089] Step S30: Finding the range where the object to be tested is located on the wafer.

[0090] The moving device moves each optical path component to above the displacement stage 200, and the control system controls the optical path component to switch to the first optical path component 301. The moving device drives the displacement stage to move horizontally in the first direction, so that the first objective lens 309 of the first optical path component 301 can find the range where the object to be measured is located on the wafer; the moving axis 201 drives the first objective lens 309 to move perpendicular to the wafer surface along the second direction, and the moving axis 201 adjusts the distance between the first objective lens 309 and the object to be measured on the wafer for multiple times until the range where the object to be measured on the wafer is located meets the clarity requirement.

[0091] Step S31: obtaining the specific position of the object to be measured within the range on the wafer.

[0092] The control system controls the optical path component to switch to the second optical path component 302, and the moving device drives the translation stage to move horizontally in the first direction, so that the second objective lens 312 of the second optical path component 302 can obtain the specific position of the object to be measured within the range on the wafer; the moving axis 201 drives the second objective lens 312 to move perpendicular to the wafer surface along the second direction, and the moving axis 201 adjusts the distance between the second objective lens 312 and the object to be measured on the wafer for multiple times until the position of the object to be measured on the wafer meets the clarity requirement.

[0093] Step S32: Obtain imaging information of the specific position of the object to be measured on the wafer.

[0094] The control system controls the optical path component to switch to the main optical path component, and the moving device drives the displacement stage 200 to move horizontally in the first direction, so that the main optical path objective lens 305 of the main optical path is directly at the position of the object to be measured on the wafer; through image processing, it is determined whether the imaging clarity of the object to be measured on the main optical path camera meets the requirements. If the clarity does not meet the requirements, the distance between the main optical path objective lens 305 and the object to be measured at a specific position needs to be measured and adjusted multiple times through the spectral distance measurement system 315, the piezoelectric ceramic displacement device 314 and the moving axis 201, so that the clarity of the object to be measured meets the requirements.

[0095] In summary, the present invention provides a focusing system for wafer detection, including: a mobile device, and multiple optical path components arranged on the mobile device, wherein the magnification of the object to be measured on the wafer of the multiple optical path components are different; wherein the mobile device is used to adjust the distance between the optical path components in the multiple optical path components and the object to be measured on the wafer for multiple times to obtain the imaging information of the object to be measured on the wafer; wherein the distance between at least one of the multiple optical path components and the object to be measured on the wafer is adjusted at one time, and different distances between the optical path component and the object to be measured on the wafer correspond to imaging information of different precisions of the object to be measured on the wafer. The above technical solution is adopted to realize one machine with multiple functions, and can detect objects of different sizes at the same time, expand the detection range, and improve the detection accuracy. It has a high cost-effectiveness and is suitable for large-scale application and promotion.

[0096] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A focusing system for wafer inspection, characterized in that: include: A mobile device, and a plurality of optical path components disposed on the mobile device, wherein the plurality of optical path components have different magnification factors for the object to be measured on the wafer; The moving device is used to drive the multiple optical path components, adjust the distance between the optical path components among the multiple optical path components and the object to be measured on the wafer for multiple times, so as to obtain the imaging information of the object to be measured on the wafer, and select the optical path component whose clarity of the imaging information of the object to be measured meets the requirements, so as to focus and detect the object to be measured; wherein the distance between at least one optical path component among the multiple optical path components and the object to be measured on the wafer is adjusted at one time, and different distances between the optical path component and the object to be measured on the wafer correspond to imaging information of different precisions of the object to be measured on the wafer; Wherein, the plurality of optical path components include a first optical path component, a second optical path component and a main optical path component; When the size of the object to be measured is less than 1 micron, the mobile device selects the first optical path component, the second optical path component and the main optical path component to jointly focus on the object to be measured for detection, wherein the first optical path component is used to focus on finding the range of the object to be measured on the wafer, the second optical path component is used to focus on determining the specific position of the object to be measured within the range, and the main optical path component is used to focus on the imaging information of the object to be measured at the specific position; The main optical path component further comprises: a main optical path objective lens and a piezoelectric ceramic displacement device, wherein the piezoelectric ceramic displacement device is placed on the main optical path objective lens and is used for performing a second calibration on the distance between the main optical path objective lens and the object to be measured on the wafer.

2. The focusing system according to claim 1, characterized in that The moving device is used to adjust the distance between an optical path component among the multiple optical path components and the object to be measured on the wafer for multiple times, including: adjusting the distance between an optical path component among the multiple optical path components and the object to be measured on the wafer for multiple times in a first direction and a second direction.

3. The focusing system according to claim 1 or 2, characterized in that The moving device includes a translation stage that moves in a first direction, a stepping motor, and a moving axis that moves in a second direction; The translation stage is used to move and position the wafer in a first direction; The plurality of optical path components are disposed on the moving shaft, and the moving shaft moves in the second direction to drive the plurality of optical path components to move in the second direction; The stepper motor is used to control the movement of the translation stage and the moving axis.

4. The focusing system according to claim 1, wherein: The magnification of the first optical path component on the object to be measured on the wafer is smaller than that of the second optical path component.

5. The focusing system according to claim 1, wherein: The main light path component includes a main light path camera and a light source sensor; The light source sensor provides incident light to the object to be measured on the wafer through the main light path objective lens; After the incident light is reflected by the object to be measured on the wafer, the reflected light is transmitted to the main light path objective lens; The main light path camera is used to collect reflected light passing through the main light path objective lens, where the reflected light represents imaging information of the object to be measured on the wafer; The first optical path component includes a first light source, a first camera, and a first objective lens; the second optical path component includes a second light source, a second camera, and a second objective lens; The first light source provides incident light to the object to be measured on the wafer through the first objective lens; after the incident light is reflected by the object to be measured on the wafer, the reflected light is transmitted to the first objective lens; The first camera is used to collect reflected light passing through the first objective lens, where the reflected light represents imaging information of the object to be measured on the wafer; The second light source provides incident light to the object to be measured on the wafer through the second objective lens; After the incident light is reflected by the object to be measured on the wafer, the reflected light is transmitted to the second objective lens; The second camera is used to collect reflected light passing through the second objective lens, where the reflected light represents imaging information of the object to be measured on the wafer.

6. The focusing system according to claim 5, characterized in that The main optical path assembly also includes: a mechanical fine-tuning module; The mechanical fine-tuning module is used to perform a first calibration on the distance between the main light path objective lens and the object to be measured on the wafer. Different distances between the main light path objective lens and the object to be measured on the wafer correspond to different objects to be measured on the wafer.

7. The focusing system according to claim 3, characterized in that The moving axis is provided with a spectral distance measuring system for measuring the distance from the objective lens in each optical path component to the object to be measured on the wafer; The spectral ranging system includes a spectral sensor, a transmitter and a receiver; the spectral sensor provides the transmitter with light signals of different frequencies as incident light for different objects to be measured on the wafer; the receiver is used to receive reflected light signals from different objects to be measured on the wafer; the light intensity information of the reflected light signal represents the distance between the different objects to be measured on the wafer and the spectral sensor.

8. The focusing system according to claim 3, characterized in that Also includes: Control system; the control system is used to control the stepper motor.

9. The focusing system according to claim 5, characterized in that Also includes: Optical system, single-axis motion platform; The optical system is used to focus the optical signal of the light source sensor onto the object to be measured on the wafer; The single-axis motion platform is used to manually calibrate the distance between the second objective lens and the object to be measured on the wafer.

10. A wafer inspection system, characterized in that: include: A focusing system and a data processing system; the focusing system is a focusing system as claimed in any one of claims 1 to 9; the data processing system is used to analyze and process imaging information of an object to be measured on a wafer.

11. A focusing method for wafer inspection, characterized in that: A focusing system applied to any one of claims 1 to 9; comprising: Determine an optical path component with the same magnification among multiple optical path components, and adjust the distance between the optical path component with the same magnification and the object to be measured on the wafer multiple times until the imaging information of the object to be measured on the wafer obtains meets the clarity requirement; and determine optical path components with different magnifications among multiple optical path components, and adjust the distance between the optical path components with different magnifications and the wafer surface multiple times until the imaging information of the object to be measured on the wafer obtains meets the clarity requirement.

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