CN117672914A

CN117672914A - Focusing system for wafer detection, wafer detection system and focusing method

Info

Publication number: CN117672914A
Application number: CN202311633188.9A
Authority: CN
Inventors: 李二朋; 汤庚
Original assignee: Meijie Photoelectric Technology Shanghai Co ltd
Current assignee: Meijie Photoelectric Technology Shanghai Co ltd
Priority date: 2023-11-30
Filing date: 2023-11-30
Publication date: 2024-03-08

Abstract

A focusing system for wafer detection, a wafer detection system and a focusing method, wherein the focusing system for wafer detection comprises: the device comprises a moving device and a plurality of light path components arranged on the moving device, wherein the plurality of light path components are different in magnification to an object to be detected on a wafer; the moving device is used for adjusting the distance between the optical path components in the plurality of optical path components and the object to be measured on the wafer for a plurality of times so as to acquire imaging information of the object to be measured on the wafer; and adjusting the distance between at least one optical path component in the plurality of optical path components and the object to be measured on the wafer at one time, wherein different distances between the optical path components and the object to be measured on the wafer correspond to imaging information with different accuracies of the object to be measured on the wafer. By adopting the technical scheme of the invention, one machine is multifunctional, simultaneously, objects to be detected with different sizes can be detected, the detection range is enlarged, the detection precision can be improved, and the cost performance is very high.

Description

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

Technical Field

The invention relates to the field of semiconductor wafer detection, in particular to a focusing system for wafer detection, a wafer detection system and a focusing method.

Background

Wafer inspection is a key step in semiconductor manufacturing, requiring the use of a focusing system; the focusing system is a system that focuses incident light for inspecting a wafer onto the wafer surface. With the rapid development of semiconductor manufacturing technology, the precision requirement of the focusing system is increasingly significant. Therefore, how to improve the precision of the focusing system is a technical problem that needs to be solved by those skilled in the art.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a wafer detection precision focusing system, a wafer detection system and a focusing method, which are used for improving the precision of the focusing system and further improving the wafer detection effect.

In view of the above, the present invention provides an aggregation system for wafer inspection, comprising: the device comprises a moving device and a plurality of light path components arranged on the moving device, wherein the plurality of light path components are different in magnification to an object to be detected on a wafer; the moving device is used for adjusting the distance between the optical path components in the plurality of optical path components and the object to be measured on the wafer for a plurality of times so as to acquire imaging information of the object to be measured on the wafer; and adjusting the distance between at least one optical path component in the plurality of optical path components and the object to be measured on the wafer at one time, wherein different distances between the optical path components and the object to be measured on the wafer correspond to imaging information with different accuracies of the object to be measured on the wafer.

Optionally, the moving device is configured to adjust, for multiple times, a distance between an optical path component of the plurality of optical path components and an object to be measured on the wafer, where the distance includes: and in the first direction and the second direction, the distance between the optical path component in the plurality of optical path components and the object to be measured on the wafer is adjusted for multiple times.

Optionally, the moving device includes a displacement table that moves in a first direction, a stepping motor, and a moving shaft that moves in a second direction; the displacement table is used for moving and positioning the wafer in a first direction; the plurality of light path components are arranged on the moving shaft, and the moving shaft moves in a second direction so as to drive the plurality of light path components to move in the second direction; the stepping motor is used for controlling the displacement table and the moving shaft to move.

Optionally, the plurality of different optical path components includes a first optical path component, a second optical path component, and a main optical path component; the first light path component amplifies the object to be tested on the wafer by a factor smaller than that of the second light path component.

Optionally, the main light path component comprises a main light path camera, a main light path objective lens and a light source sensor; the light source sensor provides incident light to an object to be measured on the wafer through the main light path objective lens; after being reflected by an object to be detected on the wafer, the incident light is transmitted to a main light path objective lens; the main light path camera is used for collecting reflected light passing through the main light path objective lens, and the reflected light represents imaging information of an object to be detected on the wafer; the first light path component comprises a first light source, a first camera and a first objective lens; the second light path component comprises a second light source, a second camera and a second objective lens; the first light source provides incident light to an object to be measured on the wafer through the first objective lens; after the incident light is reflected by an object to be detected on the wafer, the reflected light is transmitted to a first objective lens; the first camera is used for collecting reflected light passing through the first objective lens, and the reflected light represents imaging information of an object to be detected on the wafer; the second light source provides incident light to an object to be measured on the wafer through the second objective; after the incident light is reflected by an object to be detected on the wafer, the reflected light is transmitted to a second objective; the second camera is used for collecting reflected light passing through the second objective, and the reflected light represents imaging information of an object to be detected on the wafer.

Optionally, the main light path component further includes: a mechanical fine tuning module and a piezoelectric ceramic displacement device; the mechanical fine adjustment module is used for carrying out first calibration on the distance between the main light path objective lens and the object to be measured on the wafer, and 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; the piezoelectric ceramic displacement device is arranged on the main light path objective lens and is used for performing second calibration on the distance between the main light path objective lens and an object to be measured on the wafer, and the precision of the second calibration is higher than that of the first calibration.

Optionally, a spectrum ranging system is arranged on the moving axis and is used for measuring the distance from the objective lens in each light path component to the object to be measured on the wafer;

the spectrum ranging system comprises a spectrum sensor, a transmitter and a receiver; the spectrum sensor provides optical signals with different frequencies for the emitter and is used as incident light of different objects to be detected on the wafer; the receiver is used for receiving reflected light signals of different objects to be tested on the wafer; the light intensity information of the reflected light signals represents the distances between different objects to be detected on the wafer and the spectrum sensor.

Optionally, the method further comprises: a control system; the control system is used for controlling the stepping motor.

Optionally, the method further comprises: an optical system, a single axis motion platform; the optical system is used for focusing the optical signals of the light source sensor to an object to be detected on the wafer; the single-axis motion platform is used for manually calibrating the distance between the second objective and the object to be measured on the wafer.

The invention also provides a wafer detection system, which comprises: a focusing system, a data processing system; the focusing system is any one of the focusing systems described above; the data processing system is used for analyzing and processing imaging information of an object to be detected on the wafer.

Correspondingly, the invention also provides a focusing method for wafer detection, which is applied to the focusing system described in any one of the above; comprising the following steps: determining optical path components with the same magnification in the plurality of optical path components, and adjusting the distances between the optical path components with the same magnification and the object to be measured on the wafer for a plurality of times until the acquired imaging information of the object to be measured on the wafer meets the definition requirement; and determining the optical path components with different amplification factors in the plurality of optical path components, and adjusting the distances between the optical path components with different amplification factors and the surface of the wafer for a plurality of times until the acquired imaging information of the object to be tested on the wafer meets the definition requirement.

By adopting the technical scheme, a plurality of light path components are arranged, the light path components have different amplification factors on the object to be tested, the moving device adjusts the distances between the plurality of light path components and the object to be tested on the wafer for a plurality of times, the light path components suitable for the object to be tested are found, and the focusing precision is improved.

Drawings

Fig. 1 to 7 are focusing diagrams of a wafer inspection according to a first embodiment of the present invention;

FIG. 8 is a block diagram of a focusing system for wafer inspection of the present invention;

FIG. 9 is an exploded view of a focusing system for wafer inspection according to the present invention;

FIG. 10 is a schematic view of objective imaging of various light path components of the present invention;

FIG. 11 is a schematic diagram of a mechanical trimming module of the present invention;

FIG. 12 is a schematic diagram of a spectral ranging system of the present invention;

FIG. 13 is a schematic diagram of the focusing system of the present invention for measuring the tilt of the respective objective lens and the wafer surface;

fig. 14 to 16 are flowcharts of a focusing method for wafer inspection according to an embodiment of the present invention

Detailed Description

The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.

Regarding existing wafer inspection, the following focusing system is employed:

traditional mechanical focusing system realizes focusing through manual adjustment light ring in order to adjust the camera lens position, and mechanical focusing system exists mechanical abrasion, leads to mechanical motion precision and stability to be restricted, is difficult to reach the detection demand of high accuracy, and mechanical focusing system debugging and maintenance cost are higher after mechanical abrasion simultaneously.

The ultrasonic focusing system realizes non-contact focusing by utilizing the characteristic of ultrasonic, however, when facing complex environments (such as high temperature, high humidity and the like), the performance of the system can be greatly influenced, so that the cost of the ultrasonic focusing system is increased in order to keep suitable for an ultrasonic measurement environment, the ultrasonic focusing system is unfavorable for large-scale application, and the requirement of high stability is difficult to meet.

Active optical focusing system: automatically adjusting lens parameters according to imaging definition degree by an active control system to realize focusing; although such systems have some accuracy, they have high debugging complexity and perform poorly in dynamic environments (detection when the wafer is moving), and the response speed of the active optical focusing system is slow relative to the wafer motion, which makes it difficult to meet the real-time detection requirements of high speed.

The existing wafer detection focusing system is difficult to meet the requirements of high precision, high speed and high stability, and becomes a bottleneck for restricting the improvement of the semiconductor manufacturing process. In order to solve the problem, the embodiment of the invention provides a focusing system for wafer detection, which can realize real-time monitoring of the position and the surface morphology of a wafer so as to realize high-precision and high-stability detection; the problems of mechanical abrasion and precision loss of the traditional mechanical focusing system are avoided; the focusing system adopts intelligent control, reduces the operation complexity and improves the production efficiency.

The invention has stronger environmental adaptability and can keep stable performance under different process conditions. The focusing system has higher cost performance and is suitable for large-scale application and popularization.

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to fig. 1 to 16 of the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments of the present invention, and the following embodiments and features of the embodiments may be combined with each other without conflict.

Embodiment one:

the present embodiment provides a focusing system for wafer inspection, including: the device comprises a moving device and a plurality of light path components arranged on the moving device, wherein the light path components are different in magnification of objects to be detected on a wafer.

The moving device is used for adjusting the distance between the optical path components in the plurality of optical path components and the object to be measured on the wafer for a plurality of times so as to acquire imaging information of the object to be measured on the wafer; and adjusting the distance between at least one optical path component in the plurality of optical path components and the object to be measured on the wafer at one time, wherein different distances between the optical path components and the object to be measured on the wafer correspond to imaging information with different accuracies of the object to be measured on the wafer.

The objects to be measured are distributed in any area on the wafer. The object to be measured on the wafer can be a transmission signal line, a metal film layer, an insulating film layer, a semiconductor groove, a photoresist coating layer and the like. The imaging information of the object to be measured on the wafer comprises the form information of the object to be measured, and can be the line width and line distance of metal wiring, the thickness of a film layer, the size of a via hole, the defect of the film layer (such as short wiring and open circuit, excessive etching or incomplete etching of the film layer, electrostatic damage) and the like.

With the focusing system as described above, the range of the object to be measured on the wafer is determined by, for example, eyes or optical or electrical devices before wafer inspection. And selecting at least one proper light path component according to the different sizes of the objects to be detected, and focusing and detecting the objects to be detected. The following is a description with reference to fig. 1 to 7.

If the size of the object A1 to be measured is in the micrometer level or above, one optical path component of the plurality of optical path components is adjusted to the position (within the range B) of the object A1 to be measured on the wafer 100 at a time by the moving device, and the moving device adjusts the distance between the optical path component and the object A1 to be measured for a plurality of times; for the rest light path components, repeating the steps until the light path component C1 suitable for the magnification of the object to be detected A1 is found in the plurality of light path components, and obtaining the image of the object to be detected A1 meeting the imaging definition requirement, as shown in FIG. 1, and FIG. 2 is a top view of FIG. 1.

If the size of the object to be measured is below the micron level, the object to be measured is controlled by segmentation, namely: the light path component is used to obtain the range B of the object A2 to be measured on the wafer 100, i.e. the so-called coarse alignment. And then acquiring a specific position D of the object to be measured in the range B, namely the precise focusing, and finally acquiring imaging information of the object to be measured in the specific position D, namely the precise regulation. The method comprises the following steps: firstly, one optical path component in a plurality of optical path components is adjusted to a range B where an object A2 to be detected is located at one time through a moving device, and the moving device adjusts the distance between the optical path component and the range B where the object A2 to be detected is located for a plurality of times; for the remaining light path components, the above steps are repeated until the light path component C2 suitable for the range B is found among the plurality of light path components, that is, the light path component that satisfies the requirement for the definition of the imaging information of the range B is found, as shown in fig. 3, and fig. 4 is a top view of fig. 3.

Then, one optical path component of the plurality of optical path components is adjusted to the range B where the object to be detected is located at one time by the moving device, the moving device adjusts the distance between the optical path component and the range B for a plurality of times, and the steps are repeated for the rest optical path components until the optical path component which is suitable for the specific position D in the range B is found in the plurality of optical path components, namely the optical path component C3 which enables the definition of the imaging information of the specific position D to meet the requirement is found, namely the imaging information of the object to be detected A2 is found in the optical path component C3, as shown in fig. 5, and fig. 6 is a top view of fig. 5.

Finally, one optical path component in the plurality of optical path components is adjusted to the specific position D of the object to be detected A2 at one time through the moving device, the moving device adjusts the distance between the optical path component and the specific position D for a plurality of times, and the steps are repeated for the rest optical path components until the optical path component which is suitable for the object to be detected A2 at the specific position D is found, namely the optical path component which enables the definition of imaging information of the object to be detected A2 at the specific position D to meet the requirement is found. The focusing and the detection of the object A2 to be measured are completed as shown in fig. 7.

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

By adopting the focusing system provided by the embodiment of the invention, proper light path components are selected according to different sizes of objects to be detected. The focusing detection can be carried out on the object to be detected through at least one light path component, the focusing detection can be carried out on the object to be detected through the matching of a plurality of light path components, the multifunctional device is realized, meanwhile, the objects to be detected with different sizes can be detected, the detection range is enlarged, the detection precision can be improved, and the cost performance is very high.

As an optional implementation manner, the moving device is configured to adjust, for multiple times, a distance between an optical path component of the plurality of optical path components and an object to be measured on the wafer, and includes: and in the first direction and the second direction, the distance between the optical path component in the plurality of optical path components and the object to be measured on the wafer is adjusted for multiple times.

The first direction is an adjustment direction of the wafer 100, the second direction is an adjustment direction of the plurality of optical path components, and the first direction and the second direction are perpendicular; in an alternative 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;

moving the direction of the adjustment wafer 100 in the first direction a plurality of times so as to be opposite to at least one of the plurality of optical path components; and adjusting the distance between the at least one light path component and the object to be measured in the second direction for multiple times in the second direction, and acquiring imaging information of the object to be measured on the wafer so as to meet the definition requirement. In embodiments thereof, a plurality of optical path components may also be adjusted to oppose the wafer 100.

As an alternative embodiment, referring to fig. 8, the moving means includes a displacement stage 200 that moves in a first direction, a stepping motor, and a moving shaft 201 that moves in a second direction; the displacement table 200 is used for moving and positioning the wafer 100 in a first direction; the plurality of light path components are arranged on the moving shaft 201, and the moving shaft 201 drives the plurality of light path components to move in a second direction; the stepper motor is used to control the displacement table 200 and the displacement shaft 201 to move.

The displacement table 200 is provided with a plurality of vacuum adsorption holes, the wafer 100 is fixed on the displacement table 200 through vacuum adsorption, and when the displacement table 200 drives the wafer 100 to move in the first direction, the wafer 100 slides on the displacement table 200, so that the optical path component is not beneficial to acquiring the specific position of the object to be tested on the wafer. When the displacement table 200 is rapidly moved, the sliding wafer 100 runs the risk of striking the edge of the displacement table 200, resulting in breakage of the wafer. In alternative implementations, the surface material of the displacement table 200 may be a metal material, such as aluminum or an aluminum alloy, and in other embodiments, the surface material of the displacement table 200 may also be an antistatic plexiglass plate or an antistatic polyvinyl chloride plate.

The number of the movable shafts 201 is single, and the positions of the plurality of light path components on the movable shafts 201 can be set according to actual needs. The moving shaft 201 may drive the plurality of light path components to move together in the second direction; the aforementioned moving device drives the plurality of light path components to move in the second direction, that is, the moving device drives the moving shaft 201 to move, and the moving shaft 201 drives the plurality of light path components to move in the second direction. In other embodiments, the plurality of moving shafts 201 may be one of a plurality of moving shafts, so as to drive a part of optical path components in the plurality of optical path components to move in the second direction; in other embodiments, the number of the moving shafts 201 may be the same as the number of the plurality of optical path components, so that one moving shaft correspondingly drives one optical path component to move in the second direction, thereby reducing the abrasion speed of the moving shaft 201 when a single moving shaft 201 drives all the optical path components to move.

The stepper motor has the advantages of no setting time (the time required by the stepper motor to reach a stable state rapidly is short, the real-time detection can be adapted), high control precision and high in-situ stability, the displacement table 200 and the movement of the movable shaft 201 can be better controlled, the requirements of high precision, high speed, high stability and real-time detection when the wafer is detected and focused are met, and meanwhile, the stepper motor is used, each object to be detected on the wafer can be accurately focused and detected, so that the detection range is further enlarged.

As an alternative embodiment, referring to fig. 9, the plurality of different optical path components includes a first optical path component 301, a second optical path component 302, and a main optical path component 303; the magnification of the first light path component 301 to the object to be measured on the wafer 100 is smaller than that of the second light path component 302; the magnification of the second light path component 302 to the object to be measured on the wafer 100 is smaller than that of the main light path component 303; in alternative implementations, the number of optical path components may be 3, and in other embodiments, the number of optical path components may be greater than 3, the number of optical path components being selected based on the focus requirements at wafer inspection.

When the wafer is detected and focused, at least one optical path component which is suitable for 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 alternative implementation, when the size of the object to be measured is greater than or equal to 3 micrometers, the first optical path component 301 is selected for focusing the object to be measured; when the size of the object to be measured is greater than or equal to 1 micron and less than 3 microns, selecting the second light path component 302 for focusing the object to be measured; when the size of the object to be measured is smaller than 1 micrometer, the first optical path component 301, the second optical path component 302 and the main optical path component 303 are selected to focus the object to be measured together for detection, wherein the first optical path component 301 is used for focusing and searching the range of the object to be measured on the wafer 100, the second optical path component 302 is used for focusing and determining the specific position of the object to be measured in the range, and the main optical path component 303 is used for focusing the imaging information of the object to be measured in the specific position; in summary, the focusing system for wafer detection can realize one machine with multiple functions, is applicable to objects to be detected with different sizes, and expands the detection range; in addition, the first light path component 301 and the second light path component 302 are matched with the main light path component 303, so that the focusing speed of the object to be tested is improved and the detection efficiency is improved compared with the focusing by only using the main light path component 303.

As an alternative embodiment, with continued reference to fig. 9, the main optical path assembly 303 includes a main optical path camera 304, a main optical path objective lens 305, and a light source sensor 306;

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 optical path objective lens 305; the main optical path camera 304 is configured to collect, in real time, reflected light passing through the main optical path objective 305, where the reflected light represents imaging information of an 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;

the first light source 307 provides incident light to an object to be measured on the wafer through the first objective 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 309; the first camera 308 is configured to collect, in real time, reflected light passing through the first objective 309, where the reflected light represents imaging information of an object to be measured on the wafer;

the second light source 310 provides incident light to the object to be tested on the wafer through the second objective 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 configured to collect, in real time, reflected light passing through the second objective 312, where the reflected light represents imaging information of an object to be measured on the wafer.

The imaging principle of the main light path camera 304, the first camera 308, and the second camera 311 for obtaining imaging information of the object 401 to be measured on the wafer is an objective imaging principle, and the objective lens includes a first objective lens 309, a second objective lens 312, and a main light path objective lens 305. As shown in fig. 10, the object 401 to be measured is imaged as 402 after passing through the objective lens 400, and the imaged 402 can be acquired by the first camera 308, the second camera 311 and the main optical path camera 304.

As an alternative embodiment, with continued reference to fig. 9, the main optical path assembly further includes: a mechanical trimming module 313 and a piezoelectric ceramic displacement device 314;

the mechanical fine tuning module 313 is configured to perform a first calibration on the distance between the main optical path objective 305 and the object to be measured on the wafer, where different distances between the main optical path objective 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 disposed on the main optical path objective 305, and is used for performing a second calibration on the distance between the main optical path objective 305 and the object to be measured on the wafer, where the accuracy of the second calibration is higher than that of the first calibration.

The piezoelectric ceramic displacement device 314 is disposed on the main optical path objective 305, and is used for accurately calibrating the distance between the main optical path objective and the object to be measured on the wafer, and the adjustment accuracy of the piezoelectric ceramic displacement device 314 is better than that of the mechanical fine adjustment module 313. For example, the mechanical fine tuning module 313 is suitable for focusing adjustment of objects to be measured on the wafer in the micron order and above, and the piezoceramic displacement device 314 is suitable for focusing adjustment of objects to be measured on the wafer in the micron order and below. In an alternative implementation, as shown in fig. 11, when the displacement platform 200 switches the first object W1 to be measured under the main optical path objective 305 to the second object W2 to be measured, the first object W1 to be measured is not in the same plane as the second object W2 to be measured, and there is a height difference d1, then the distances between the main optical path objective 305 and the first object W1 to be measured and between the second object W2 to be measured are different, d2 and d3 respectively, and if the imaging definition of the second object W2 to be measured in the main optical path camera 304 does not meet the requirement, at this time, the distance between the second object W2 to be measured and the main optical path objective 305 needs to be adjusted by the mechanical fine adjustment module 313 until the imaging definition of the second object W2 to be measured in the main optical path camera 304 meets the requirement. In other embodiments, the distance between the second object W2 to be measured and the main optical path objective 305 can also be adjusted by the piezo-ceramic displacement device 314. In other embodiments, the mechanical fine tuning module 313 may also be used to adjust the distances between the first objective 309 and the second objective 312 and the object to be measured. The piezo-ceramic displacement device 314 may also be used to adjust the distance between the first objective 309 and the second objective 312 and the object to be measured.

The piezoelectric ceramic in the piezoelectric ceramic displacement device 314 is a special material, and has sensitive physical characteristics, namely when voltage is applied to the piezoelectric ceramic displacement device, an electric polarization phenomenon is generated in the piezoelectric ceramic material, so that the length or shape of the material is changed, the piezoelectric ceramic can generate nano-level displacement, the movement of each objective lens is controlled by utilizing the characteristic of the piezoelectric ceramic material through the piezoelectric ceramic displacement device 314, and the distance between each objective lens and an object to be detected on a wafer is adjusted with high precision, so that the object to be detected is focused with high precision, and the accuracy of data detection is improved.

As an alternative embodiment, with continued reference to fig. 8 and fig. 9, the moving axis 201 is further provided with a spectrum ranging system 315, for measuring the distance between each objective lens in each optical path component and the object to be measured on the wafer; referring to fig. 12, the spectrum ranging system includes a spectrum sensor 500, a transmitter and a receiver, where the spectrum sensor 500, the transmitter and the receiver are used to measure the distance between the spectrum sensor 500 and the surface of the wafer 100 in real time. As shown in fig. 12, a distance limit e1 between the spectrum sensor 500 and the surface of the wafer 100 is preset in the spectrum ranging system 315 as a reference, when the distance between the spectrum sensor 500 and the surface of the wafer 100 reaches the limit e1 from e2, the spectrum sensor 500 is fed back to the control system through the data processing system, and at the moment, the distance between the main optical path objective lens 305 and the surface of the wafer 100 also reaches the limit e3, the control system controls the moving shaft 201 to stop moving, so as to prevent collision between each objective lens and the surface of the wafer 100. The spectral ranging system 500 also measures the limiting distances of 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 the light can be reflected, the spectrum ranging system 315 can be used to measure the distance between the object to be measured and the spectrum sensor 500, so that the range of the object to be measured is enlarged, the distance between each objective lens and the object to be measured on the wafer 100 is measured under different environments, the environment adaptability is high, and the stable performance is maintained under different process conditions.

The spectrum sensor 500 provides optical signals with different frequencies for the emitter, and the optical signals are used as incident light of different objects to be detected on the wafer; the receiver is used for receiving reflected light signals of different objects to be tested on the wafer; the light intensity information of the reflected light signal represents the distance between different objects to be measured on the wafer and the spectrum sensor 500, and the greater the light intensity value of the reflected light signal is, the closer the distance between the spectrum sensor 500 and the surface of the wafer is.

The spectrum sensor 500 provides optical signals with different frequencies, the optical signals are transmitted to the film layer to be tested on the surface of the wafer through the transmitter, reflected optical signals with different intensities are obtained, the intensity of the reflected optical signals is tested, the maximum intensity of the reflected optical signals is found out, and accordingly the incident optical signals which are most matched with the film layer are obtained.

In the wafer detection process, the moving shaft 201 drives each optical path component and the spectrum ranging system 315 to move towards the wafer, and the spectrum ranging system 315 tests the distance between each optical path component objective lens and the surface of the wafer in real time, so that each objective lens of each optical path component is prevented from colliding with the wafer, and the objective lens and the wafer are prevented from being damaged. When the receiver of the spectral ranging system 315 obtains the maximum reflected light intensity signal of the film, it indicates that the distance between the objective lens of each optical path component and the wafer reaches the limit, and each optical path component stops moving toward the wafer.

As an alternative embodiment, the focusing system further comprises a control system; the control system is used to control the stepper motor and the movement of the movement shaft 201. The control system sends a control signal to the stepper motor, and the stepper motor drives the movable shaft 201 to move in the second direction, so that each optical path component is driven to move. In other embodiments, the control system may also control the movement of the mechanical trimming module 313 and the piezoceramic displacement device 314, as well as the switching between the optical path components of the optical path components. The control system is utilized to realize self-energizing control, and the wafer detection efficiency is greatly improved.

As an alternative embodiment, as shown in connection with fig. 9, the focusing system further includes an optical system, a single axis motion stage 316; the optical system is used for focusing the optical signal of the light source sensor 306 to the object to be tested on the wafer, for example, the optical signal can be collected through an optical objective lens; before the wafer is inspected, the distance between the second objective lens 312 and the object to be inspected on the wafer is manually calibrated by 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.

Embodiment two:

the embodiment of the invention also provides a wafer detection system, which comprises: a focusing system, a data processing system; the focusing system may be the focusing system of any one of the preceding embodiments; the data processing system is used for analyzing and processing imaging information of an object to be detected on the wafer. The first camera 308, the second camera 311, and the main light path camera 304 feed imaging information of the object to be measured on the wafer acquired in real time back to the data processing system, the data processing system pre-stores imaging information of the object to be measured, for example, light intensity corresponding to the imaging information of each object to be measured, the data processing system automatically determines and analyzes whether the imaging information of the object to be measured meets the definition requirement, if the definition does not meet the requirement, the data processing system sends a signal to the control system, so as to automatically adjust the distance between each objective lens and the wafer, and continue to acquire the imaging information of the object to be measured until the definition of the object to be measured meets the requirement. The self-energizing control is realized by combining the data processing system with the control system.

The focusing method for wafer inspection, which is applied to the focusing system according to any one of the foregoing embodiments; comprising the following steps: determining optical path components with the same magnification in the plurality of optical path components, and adjusting the distance between the optical path components with the same magnification 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 is obtained to meet the definition requirement; and determining the optical path components with different amplification factors in the plurality of optical path components, and adjusting the distances between the optical path components with different amplification factors and the surface of the wafer for a plurality of times until the imaging information of the object to be detected on the wafer is obtained to meet the definition requirement.

In order to make the embodiments of the present invention more clearly understood and implemented by those skilled in the art, the working principle of the focusing system for wafer inspection will be described with reference to fig. 13 to 16.

The embodiment of the invention provides a focusing method for wafer detection, which is applied to a focusing system in any one of the previous embodiments.

Before focus test, the inclination of each objective lens of the focusing system and the surface of the wafer needs to be checked. As shown in fig. 13, the wafer is placed on the displacement table 200, a feeler, such as a wedge feeler 600, is inserted between the first objective 309 and the wafer 100, and if the readings of the two wedge feelers 600 are not equal and the tilting degree cannot meet the testing requirement of the focusing system, the first objective 309 or the displacement table 200 is calibrated to be horizontal by means of a level gauge, so that the surface of the first objective 309 is kept parallel to the surface of the wafer. The above steps are repeated to align the surfaces of the second objective lens 312 and the main optical path objective lens 305 to remain parallel to the wafer surface.

First, the focusing method for an object to be measured of 3 μm or more in size includes the steps of:

step S10: and adjusting the relative position of the first objective lens and the wafer.

The moving device moves each light path component to the upper part of the displacement table 200, the control system controls the light path component to be switched to the first light path component 301, and the moving device drives the displacement table 200 to move horizontally in the first direction so as to enable the first objective 309 to be opposite to the object to be tested on the wafer 100;

step S11: and adjusting the first objective lens to acquire imaging information of the object to be detected.

The moving axis 201 drives the first objective 309 of the first optical path component 301 to move along the second direction perpendicular to the surface of the wafer 100, and the moving axis 201 adjusts the distance between the first objective 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 is acquired to meet the definition requirement, and open loop logic control is adopted in the multiple adjustment process of the moving axis 201, that is, the adjustment process is not required to be fed back to the control system to accurately adjust the distance between the first objective 309 and the object to be measured on the wafer.

Step S12: the image processing is carried out on imaging information of the object to be detected.

The imaging information of the object to be measured is subjected to image processing to present a clear image of the object to be measured on the first camera 308.

Next, the focusing method for the object to be measured having a size of more than 1 micron and less than 3 microns includes the steps of:

step S20: and adjusting the relative position of the second objective lens and the wafer.

The moving device moves each light path component to the upper part of the displacement table 200, the control system controls the light path components to be switched to the second light path component 302, and the moving device drives the displacement table 200 to move horizontally in the first direction so that the second objective 312 of the second light path component 302 is opposite to the object to be tested on the wafer;

step S21: and adjusting the second objective to obtain imaging information of the object to be detected.

The moving axis drives the second objective lens 312 to move along the second direction perpendicular to the surface of the wafer, and the moving axis adjusts the distance between the second objective lens 312 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 is obtained to meet the definition requirement, and open loop logic control is adopted in the multiple adjustment process of the moving axis 201, that is, the adjustment process is not required to be fed back to the control system to accurately adjust the distance between the first objective lens 309 and the object to be measured on the wafer.

Step S22: the image processing is carried out on imaging information of the object to be detected.

The imaging information of the object to be measured is subjected to image processing to present a clear image of the object to be measured on the second camera 311.

Finally, the focusing method for the object to be measured with the size smaller than 1 μm comprises the following steps, as shown in fig. 16:

step S30: searching the range of the object to be detected on the wafer.

The moving device moves each optical path component above the displacement table 200, the control system controls the optical path component to be switched to the first optical path component 301, and the moving device drives the displacement table to move in the horizontal direction of the first direction, so that the first objective 309 of the first optical path component 301 searches the range of the object to be detected on the wafer; the moving axis 201 drives the first objective 309 to move along the second direction perpendicular to the surface of the wafer, and the moving axis 201 adjusts the distance between the first objective 309 and the object to be tested on the wafer for multiple times until the range of the object to be tested on the wafer is obtained to meet the definition requirement.

Step S31: and acquiring the specific position of the object to be measured in the range of the wafer.

The control system controls the light path component to be switched to the second light path component 302, and the moving device drives the displacement table to move in the horizontal direction in the first direction so as to enable the second objective 312 of the second light path component 302 to acquire the specific position of the object to be detected in the range of the wafer; the moving axis 201 drives the second objective 312 to move along the second direction perpendicular to the surface of the wafer, and the moving axis 201 adjusts the distance between the second objective 312 and the object to be tested on the wafer for multiple times until the position of the object to be tested on the wafer is obtained to meet the definition requirement.

Step S32: and acquiring imaging information of the specific position of the object to be measured on the wafer.

The control system controls the light path component to be switched to the main light path component, and the moving device drives the displacement table 200 to move in the horizontal direction in the first direction so as to enable the main light path objective 305 of the main light path to be opposite to the position of the object to be detected on the wafer; and judging whether the imaging definition of the object to be tested on the main light path camera meets the requirement or not through image processing. If the definition does not meet the requirement, the distance between the main optical path objective 305 and the object to be measured at a specific position is measured and adjusted multiple times by the spectrum ranging system 315, the piezoelectric ceramic displacement device 314 and the moving axis 201, so that the definition of the object to be measured meets the requirement.

In summary, the aggregation system for wafer inspection provided by the present invention includes: the device comprises a moving device and a plurality of light path components arranged on the moving device, wherein the amplification factors of objects to be detected on the wafers of the light path components are different; the moving device is used for adjusting the distance between the optical path components in the plurality of optical path components and the object to be measured on the wafer for a plurality of times so as to acquire imaging information of the object to be measured on the wafer; and adjusting the distance between at least one optical path component in the plurality of optical path components and the object to be measured on the wafer at one time, wherein different distances between the optical path components and the object to be measured on the wafer correspond to imaging information with different accuracies of the object to be measured on the wafer. By adopting the technical scheme, one machine is multifunctional, simultaneously, objects to be detected with different sizes can be detected, the detection range is enlarged, the detection precision can be improved, and the device has high cost performance and is suitable for large-scale application and popularization.

Although the present invention has been described in terms of the preferred embodiments, it is not intended to be limited to the embodiments, and any person skilled in the art can make any possible variations and modifications to the technical solution of the present invention by using the methods and technical matters disclosed above without departing from the spirit and scope of the present invention, so any simple modifications, equivalent variations and modifications to the embodiments described above according to the technical matters of the present invention are within the scope of the technical matters of the present invention.

Claims

1. An aggregation system for wafer inspection, comprising: the device comprises a moving device and a plurality of light path components arranged on the moving device, wherein the plurality of light path components are different in magnification to an object to be detected on a wafer;

2. The focusing system of claim 1, wherein the means for moving for adjusting the distance between the optical path assembly of the plurality of optical path assemblies and the object to be measured on the wafer a plurality of times comprises: and in the first direction and the second direction, the distance between the optical path component in the plurality of optical path components and the object to be measured on the wafer is adjusted for multiple times.

3. Focusing system according to one of claims 1 or 2, characterized in that the displacement means comprise a displacement stage which is moved in a first direction, a stepper motor, and a displacement axis which is moved in a second direction;

the displacement table is used for moving and positioning the wafer in a first direction;

the plurality of light path components are arranged on the moving shaft, and the moving shaft moves in a second direction so as to drive the plurality of light path components to move in the second direction;

the stepping motor is used for controlling the displacement table and the moving shaft to move.

4. The focusing system of claim 3, wherein the plurality of different optical path components includes a first optical path component, a second optical path component, and a main optical path component; the first light path component amplifies the object to be tested on the wafer by a factor smaller than that of the second light path component.

5. The focusing system of claim 4, wherein the main optical path assembly comprises a main optical path camera, a main optical path objective lens, a light source sensor;

the light source sensor provides incident light to an object to be measured on the wafer through the main light path objective lens; after being reflected by an object to be detected on the wafer, the incident light is transmitted to a main light path objective lens;

the main light path camera is used for collecting reflected light passing through the main light path objective lens, and the reflected light represents imaging information of an object to be detected on the wafer;

the first light path component comprises a first light source, a first camera and a first objective lens; the second light path component comprises a second light source, a second camera and a second objective lens;

the first light source provides incident light to an object to be measured on the wafer through the first objective lens; after the incident light is reflected by an object to be detected on the wafer, the reflected light is transmitted to a first objective lens;

the first camera is used for collecting reflected light passing through the first objective lens, and the reflected light represents imaging information of an object to be detected on the wafer;

the second light source provides incident light to an object to be measured on the wafer through the second objective; after the incident light is reflected by an object to be detected on the wafer, the reflected light is transmitted to a second objective;

the second camera is used for collecting reflected light passing through the second objective, and the reflected light represents imaging information of an object to be measured on the wafer.

6. The aggregation system of claim 5, wherein the main optical path assembly further comprises: a mechanical fine tuning module and a piezoelectric ceramic displacement device;

the mechanical fine adjustment module is used for carrying out first calibration on the distance between the main light path objective lens and the object to be measured on the wafer, and 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;

the piezoelectric ceramic displacement device is arranged on the main light path objective lens and is used for performing second calibration on the distance between the main light path objective lens and an object to be measured on the wafer, and the precision of the second calibration is higher than that of the first calibration.

7. The focusing system according to claim 3, wherein a spectrum ranging system is disposed on the moving axis for measuring a distance from the objective lens in each optical path component to the object to be measured on the wafer;

8. The focusing system of claim 3, further comprising: a control system; the control system is used for controlling the stepping motor.

9. The focusing system of claim 5, further comprising: an optical system, a single axis motion platform;

the optical system is used for focusing the optical signals of the light source sensor to an object to be detected on the wafer;

the single-axis motion platform is used for manually calibrating the distance between the second objective and the object to be measured on the wafer.

10. A wafer inspection system, comprising: a focusing system, a data processing system; the focusing system being a focusing system according to any one of claims 1-9; the data processing system is used for analyzing and processing imaging information of an object to be detected on the wafer.

11. A focusing method for wafer inspection, characterized by being applied to the focusing system according to any one of claims 1 to 9; comprising the following steps:

determining optical path components with the same magnification in the plurality of optical path components, and adjusting the distances between the optical path components with the same magnification and the object to be measured on the wafer for a plurality of times until the acquired imaging information of the object to be measured on the wafer meets the definition requirement; and determining the optical path components with different amplification factors in the plurality of optical path components, and adjusting the distances between the optical path components with different amplification factors and the surface of the wafer for a plurality of times until the acquired imaging information of the object to be tested on the wafer meets the definition requirement.