CN117723490B - Wafer detection system and method and wide-spectrum coherent light interference self-focusing light path - Google Patents
Wafer detection system and method and wide-spectrum coherent light interference self-focusing light path Download PDFInfo
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Abstract
The application provides a wafer detection system and a method, a wide-spectrum coherent light interference self-focusing light path, which are applied to the technical field of wafer detection, adopt the intensity of an interference signal of wide-spectrum coherent light as a self-focusing signal, and a detection light source is flexibly selected according to actual requirements, and the self-focusing light and the detection light are combined or split through a dichroic mirror.
Description
Technical Field
The application relates to the technical field of wafer detection, in particular to a wafer detection system and method and a wide-spectrum coherent light interference self-focusing light path.
Background
Wafer inspection is critical in semiconductor manufacturing. Automated wafer inspection systems typically include a self-focusing system for placing a wafer at the focal plane of an inspection lens and an inspection system for inspecting and measuring a wafer pattern.
Interference-based self-focusing systems have the advantages of independent focusing signals from wafer patterns, fast focusing speed, etc., and are favored, but have the following problems:
the generation of interference signals needs to be guaranteed by means of an optical-mechanical system with high precision, high price and extremely high performance requirements, and a light source can only emit a single spectrum light beam and cannot adapt to the application requirements of different wafer processes on detection light.
These problems result in the current wafer inspection systems having high cost, poor universality and limited application range.
Based on this, a new wafer inspection system and method, a broad spectrum coherent light interference self-focusing optical path is needed.
Disclosure of Invention
In view of this, the embodiments of the present disclosure provide a wafer detection system and method, and a wide-spectrum coherent light interference self-focusing optical path, which are applied to the wafer detection technical field, and use the wide-spectrum coherent light as a self-focusing light source, so that interference signals can be generated without a high-precision optical-mechanical system, an optical-mechanical adjustment or a vibration isolation platform; in addition, the detection light source is not shared with the self-focusing light source any more, but is flexibly selected according to the process requirements of the wafer to be detected, so that the system structure is simplified, the applicability is wider, the cost is reduced, and the wafer detection efficiency and accuracy are improved.
The embodiment of the specification provides the following technical scheme:
The embodiment of the specification provides a wide-spectrum coherent light interference self-focusing optical path, which is applied to wafer detection, and comprises: a self-focusing light source 1, a first dichroic mirror 3, a beam splitter-combiner 4, a detection objective 8, a wafer detection light source 10, a detection camera 14, a shutter 5, a reference objective 6, a total reflection mirror 7, a second dichroic mirror 12 and a detector 16, wherein the total reflection mirror 7 is located on the focal plane of the reference objective 6;
the self-focusing light source 1 is a wide-spectrum coherent light source and is used for emitting wide-spectrum coherent light;
the wafer inspection light source 10 is a wafer inspection light source for providing inspection light;
The first dichroic mirror 3 is configured to transmit the wide-spectrum coherent light to the beam splitter-combiner 4, and reflect the detection light to the beam splitter-combiner 4;
The beam splitter/combiner 4 is configured to split the broad spectrum coherent light to obtain a first transmitted beam and a first reflected beam, where the first transmitted beam is re-incident to the beam splitter/combiner 4 after passing through the shutter 5, the reference objective 6, and the total reflection mirror 7, and the first reflected beam is re-incident to the beam splitter/combiner 4 after being reflected by the detection objective 8 and the wafer to be tested, and the first combined beam is output by the beam splitter/combiner 4;
The beam splitter/combiner 4 is further configured to split the detection light to obtain a second transmitted beam and a second reflected beam, where the second transmitted beam is blocked by the shutter 5, and the second reflected beam is reflected by the detection objective 8 and the wafer to be detected and then re-enters the beam splitter/combiner 4, and the beam splitter/combiner 4 outputs a second combined beam;
The second dichroic mirror 12 is configured to transmit the first combined beam light to the detector 16 and reflect the second combined beam light to the detection camera 14;
the detector 16 is configured to detect the first combined beam, so as to determine whether the wafer to be measured is located on the focal plane of the detection objective 8 according to the interference intensity of the first combined beam;
the inspection camera 14 is used for imaging inspection of the wafer to be inspected which is already located on the focal plane of the inspection objective 8.
Embodiments of the present disclosure also provide a wafer inspection system, applying the broad spectrum coherent light interference self-focusing optical path of any one of claims 1 to 7, including: a self-focusing system and a detection system;
The self-focusing system includes: the method comprises the steps that wide-spectrum coherent light emitted by a self-focusing light source 1 is split by a beam splitter and combiner 4 to obtain a first transmission light beam and a first reflection light beam, wherein the first transmission light beam is re-incident to the beam splitter and combiner 4 after passing through a shutter 5, a reference objective lens 6 and a total reflection mirror 7, and the first reflection light beam is re-incident to the beam splitter and combiner 4 after being reflected by a detection objective lens 8 and a wafer to be detected, and the first beam splitter and combiner 4 outputs first combined light;
obtaining a focal plane of the detection objective lens 8 according to the interference intensity of the first combined beam light;
The detection system includes: the detection light emitted by the wafer detection light source 10 is split by the beam splitting and combining device 4 to obtain a second transmission light beam and a second reflection light beam, wherein the second transmission light beam is blocked by the shutter 5, and the second reflection light beam is reflected by the detection objective lens 8 and the wafer to be detected and then is re-incident to the beam splitting and combining device 4, and the second beam splitting and combining device 4 outputs second beam combining light;
And processing the second combined beam according to the detection camera 14 to obtain a detection result corresponding to the wafer to be detected.
The embodiment of the present specification also provides a wafer inspection method, which is characterized in that the method is applied to the broad spectrum coherent light interference self-focusing optical path as set forth in any one of claims 1 to 7, and includes:
The method comprises the steps that wide-spectrum coherent light emitted by a self-focusing light source 1 is split by a beam splitter and combiner 4 to obtain a first transmission light beam and a first reflection light beam, wherein the first transmission light beam is re-incident to the beam splitter and combiner 4 after passing through a shutter 5, a reference objective lens 6 and a total reflection mirror 7, and the first reflection light beam is re-incident to the beam splitter and combiner 4 after being reflected by a detection objective lens 8 and a wafer to be detected, and the first beam splitter and combiner 4 outputs first combined light;
transmitting the first combined light to detector 16 using second dichroic mirror 12;
detecting the interference intensity of the first combined beam by using a detector 16 to obtain a focal plane of the detection objective lens 8;
Placing a wafer to be detected on the focal plane of the detection objective lens 8;
The detection light emitted by the wafer detection light source 10 is split by the beam splitting and combining device 4 to obtain a second transmission light beam and a second reflection light beam, wherein the second transmission light beam is blocked by the shutter 5, and the second reflection light beam is reflected by the detection objective lens 8 and the wafer to be detected and then is re-incident to the beam splitting and combining device 4, and the second beam splitting and combining device 4 outputs second beam combining light;
Reflecting the second combined beam light toward the detection camera 14 with the second dichroic mirror 12;
the wafer to be inspected, which is located on the focal plane of the inspection objective 8, is inspected by the inspection camera 14.
Compared with the prior art, the beneficial effects that above-mentioned at least one technical scheme that this description embodiment adopted can reach include at least:
The self-focusing light source adopts wide-spectrum coherent light, the detection light source is not shared with the self-focusing light source any more, but is flexibly selected according to the process requirements of the wafer to be detected, the interference signal can be generated without a high-precision optical-mechanical system, an optical-mechanical adjustment or a vibration isolation platform, the system structure can be simplified, the cost is reduced, the applicability is improved, and the wafer detection efficiency is improved. Specifically, by selecting the self-focusing light source 1 for emitting wide-spectrum coherent light in the wafer detection system, an interference signal can be generated without a high-precision optical system, thereby being beneficial to improving the generation of the interference signal, being easier to realize self-focusing and improving the precision of wafer detection; further, the flexible control of the range of the light path difference can adapt to the processes of different wafers, and the applicability of the system is improved.
In addition, the detection light source is not shared with the self-focusing light source, and after the self-focusing light source is turned off, the wafer can be detected by using the detection light source, different light sources can be selected according to actual requirements, and the detection mode can be adjusted according to the process or the requirement of the wafer, so that the flexibility and the applicability of the system are improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of an automated wafer inspection system based on broad spectrum coherent light interference self-focusing according to an embodiment of the present application;
FIG. 2 is a schematic diagram of a prior art wafer inspection system;
FIG. 3 is a flow chart of an automated wafer inspection method based on broad spectrum coherent light interference self-focusing according to an embodiment of the present application;
In the figure: 1. a self-focusing light source; 2. a first collimating lens; 3. a first dichroic mirror; 4. a beam splitting and combining lens; 5. a shutter; 6. a reference objective; 7. a total reflection mirror; 8. detecting an objective lens; 9. a wafer to be inspected; 10. a wafer inspection light source; 11. a second collimating lens; 12. a second dichroic mirror; 13. a first focusing lens; 14. detecting a camera; 15. a second focusing lens; 16. a detector; 201. detecting a camera; 202. a reference objective; 203. an object to be measured; 204. a light source.
Detailed Description
Embodiments of the present application will be described in detail below with reference to the accompanying drawings.
Other advantages and effects of the present application will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present application with reference to specific examples. It will be apparent that the described embodiments are only some, but not all, embodiments of the application. The application may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present application. It should be noted that the following embodiments and features in the embodiments may be combined with each other without conflict. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
It is noted that various aspects of the embodiments are described below within the scope of the following claims. It should be apparent that the aspects described herein may be embodied in a wide variety of forms and that any specific structure and/or function described herein is merely illustrative. Based on the present disclosure, one skilled in the art will appreciate that one aspect described herein may be implemented independently of any other aspect, and that two or more of these aspects may be combined in various ways. For example, apparatus may be implemented and/or methods practiced using any number and aspects set forth herein. In addition, such apparatus may be implemented and/or such methods practiced using other structure and/or functionality in addition to one or more of the aspects set forth herein.
It should also be noted that the illustrations provided in the following embodiments merely illustrate the basic concept of the present application by way of illustration, and only the components related to the present application are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complicated.
In addition, in the following description, specific details are provided in order to provide a thorough understanding of the examples. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details.
The self-focusing light source and the detection light source of the automatic wafer detection system in the existing scheme are the same incoherent white light source, and the working mode is to split the white light into reference light and detection light.
Specifically, as shown in fig. 2, the existing automated wafer inspection system uses one incoherent light as both a self-focusing light source and an inspection light source. When detecting a wafer, the light source 204 is split into reference light and detection light, the reference light passes through the reference objective 202 and then is reflected by a reflector arranged on the focal plane of the reference objective 202, and passes through the reference objective 202 again to reach the beam combiner; the detection light passes through the detection objective lens with the same parameters as the reference objective lens, then is reflected by the detected object 203 (the wafer to be detected) and passes through the detection lens again to reach the beam combiner, the reference light and the detection light are combined by the beam combiner, when the detected object 203 (the wafer to be detected) is placed on the focal plane of the detection lens, the reference light and the detection light have the same optical path length, the strongest interference signal is generated, when the wafer deviates from the focal plane of the detection lens, the interference signal is gradually weakened until the interference signal disappears, the wafer is placed on the focal plane of the detection lens according to the intensity of the interference signal, then the reference light is closed, and the detection light is adopted for detecting the wafer.
In view of this, the inventors have studied and found in the improvement search: the self-focusing light source and the detection light source in the existing automatic wafer detection system based on the interference self-focusing system are the same incoherent white light source, the requirements of the generation of interference signals on the precision of an optical machine system, the optical machine assembly and a vibration isolation platform are extremely high due to the arrangement of the light sources, the interference signals can be generated only by the optical machine with extremely high processing precision, a precise piezoelectric adjusting frame and an active vibration isolation platform, and therefore the cost is relatively high, the universality is relatively poor, and the application range is limited.
In an improvement for self-focusing light sources, it was further found that: the detection light source and the self-focusing light source of the current automatic wafer detection system are the same incoherent white light source, so that the detection light source cannot be flexibly adjusted according to the wafer process, and the flexibility and the applicability of the system are limited.
Based on this, the embodiment of the present specification proposes a broad-spectrum coherent light interference self-focusing optical path: as shown in fig. 1, a self-focusing light source 1 is a wide-spectrum coherent light source, emits wide-spectrum coherent light, transmits through a dichroic mirror 3, and then is split by a beam splitter-combiner 4 to obtain a first transmitted light beam and a first reflected light beam. The first transmitted light beam is a reference light beam, and after being reflected by a total reflection mirror 7 arranged on the focal plane of the reference objective 6 after passing through a shutter 5 and the reference objective 6, the first transmitted light beam reaches a beam splitting and combining device 4 after passing through the reference objective 6 and the shutter 5 again; the first reflected light beam is a measuring light beam, the first reflected light beam passes through the detection objective lens 8 to reach the wafer 9 to be detected, after being reflected by the wafer 9 to be detected, the first reflected light beam passes through the detection objective lens 8 again to reach the beam splitting and combining device 4, and then the beam splitting and combining device 4 combines the beam into first combined light beam, the first combined light beam passes through the dichroic mirror 12 and reaches the detector 16, and the detector 16 detects the first combined light beam to judge whether the wafer to be detected is positioned on the focal plane of the detection objective lens 8.
The wafer detection light source 10 provides detection light for a wafer to be detected, the detection light is combined with a wide-spectrum coherent light beam through the first dichroic mirror 3, the combined detection light beam is split into a second transmission light beam and a second reflection light beam through the beam splitting and combining device 4, wherein the second transmission light beam is blocked by the shutter 5, the second reflection light beam is focused on the wafer 9 to be detected through the detection lens 8, reflected from the wafer 9 to be detected, passes through the detection lens 8 and the beam splitting and combining device 4, reflected to the detection camera 14 through the second dichroic mirror 12, and then the detection camera 14 performs imaging detection on the wafer to be detected which is located on the focal plane of the detection objective lens 8.
It should be noted that, the wafer inspection light source 10 may be flexibly selected according to the wafer process, and any single-color and wide-spectrum coherent or incoherent light may be selected according to the actual requirement, or a self-focusing light source may be used as the inspection light.
The self-focusing light and the detection light can be selectively turned on or off according to actual requirements.
Wafer inspection can also be performed simultaneously with the inspection light and the self-focusing light.
Therefore, the intensity of the interference signal of the broad-spectrum coherent light is used as the self-focusing signal, the detection light source is flexibly selected according to the actual requirement, the self-focusing light and the detection light are combined or split through the dichroic mirror, the self-focusing light and detection light beam splitter has the advantages of simple optical machine structure, simple debugging, high focusing speed, good universality and the like, and the defects of complex optical machine structure, complex debugging, limited detection light source and the like of the self-focusing wafer detection system based on white light interference are overcome, so that the requirements and the adjustment process of the system are simplified, the cost is reduced, the detection efficiency of a wafer is improved, and the self-focusing light beam splitter can be widely applied to the automatic detection of the wafer.
The following describes the technical scheme provided by each embodiment of the present application with reference to the accompanying drawings.
As shown in fig. 1, an embodiment of the present disclosure provides a broad spectrum coherent light interference self-focusing optical path, including: a self-focusing light source 1, a first dichroic mirror 3, a beam splitter-combiner 4, a detection objective 8, a wafer detection light source 10, a detection camera 14, a shutter 5, a reference objective 6, a total reflection mirror 7, a second dichroic mirror 12 and a detector 16, wherein the total reflection mirror 7 is located on the focal plane of the reference objective 6;
The self-focusing light source 1 is a wide-spectrum coherent light source, emits wide-spectrum coherent light, transmits through the dichroic mirror 3, and then is split by the beam splitter-combiner 4 to obtain a first transmitted light beam and a first reflected light beam. The first transmitted light beam is a reference light beam, and after being reflected by a total reflection mirror 7 arranged on the focal plane of the reference objective 6 after passing through a shutter 5 and the reference objective 6, the first transmitted light beam reaches a beam splitting and combining device 4 after passing through the reference objective 6 and the shutter 5 again; the first reflected light beam is a measuring light beam, the first reflected light beam passes through the detection objective lens 8 to reach the wafer 9 to be detected, after being reflected by the wafer 9 to be detected, the first reflected light beam passes through the detection objective lens 8 again to reach the beam splitting and combining device 4, and then the beam splitting and combining device 4 combines the beam into first combined light beam, the first combined light beam passes through the dichroic mirror 12 and reaches the detector 16, and the detector 16 detects the first combined light beam so as to determine whether the wafer to be detected is positioned on the focal plane of the detection objective lens 8 according to the interference intensity of the first combined light beam.
In practice, when the optical path difference between the reference optical path and the measuring optical path is zero, the interference signal is the largest after the transmitted light and the reflected light are combined, that is, the wafer to be measured is positioned on the focal plane of the detection objective lens 8, and when the optical path difference between the reference optical path and the measuring optical path is increased, the interference signal is reduced until the interference signal disappears.
Because the self-focusing light source is a wide-spectrum coherent light source, interference can be generated only by meeting the requirement that the optical path difference between a reference optical path and a measuring optical path is within the range of the coherent length of the wide-spectrum coherent light source 1, and the transmitted light and the reflected light are completely aligned without precise adjustment.
The optical path is adjusted so that the distance between the beam splitter and combiner 4 and the reference objective lens 6 is equal to the distance between the beam splitter and combiner 4 and the detection objective lens 8, and when the distance between the reference objective lens 6 and the total reflection lens 7 is equal to the distance between the detection objective lens 8 and the wafer 9 to be detected, that is, when the wafer to be detected is in the focal plane of the detection objective lens 8, the interference signal is strongest, and at this time, the wafer detection can be performed.
The wafer detection light source 10 provides detection light for a wafer to be detected, the detection light is combined with a wide-spectrum coherent light beam through the first dichroic mirror 3, the combined detection light beam is split into a second transmission light beam and a second reflection light beam through the beam splitting and combining device 4, wherein the second transmission light beam is blocked by the shutter 5, the second reflection light beam is focused on the wafer 9 to be detected through the detection lens 8, reflected from the wafer 9 to be detected, passes through the detection lens 8 and the beam splitting and combining device 4, reflected to the detection camera 14 through the second dichroic mirror 12, and then the detection camera 14 performs imaging detection on the wafer to be detected which is located on the focal plane of the detection objective lens 8.
In summary, the intensity of the interference signal of the wide-spectrum coherent light is used as a self-focusing signal, the interference signal can be generated on the premise of not needing a high-precision optical-mechanical system, an optical-mechanical adjustment and a vibration isolation platform, and the detection light source is flexibly selected according to the wafer process, so that the requirements and adjustment processes of the system are simplified, the cost is reduced, the applicability of the system is improved, and the detection efficiency of the wafer is improved.
In one embodiment, the broad spectrum coherent light emitted from the focusing light source 1 is first collimated by the first collimating lens 2, so that the light can be ensured to propagate in a more concentrated and parallel manner, and then is split into a first transmission light path and a first reflection light path by the first beam splitter-combiner 4 after passing through the first dichroic mirror 3.
In one embodiment, the detection light provided by the wafer detection light source 10 is collimated by the second collimating lens 11, so as to ensure that the detection light can propagate in a more concentrated and parallel manner, and then passes through the first dichroic mirror 3 to combine with the self-focusing light beam.
In one embodiment, the first combined beam light passes through the dichroic mirror 12 and is focused onto the detector 16 through the second focusing lens 15, so that the detector 16 can conveniently detect the first combined beam light signal (i.e. detect the interference signal intensity of the self-focusing light), and then determine the optical path difference between the reference optical path and the measuring optical path according to the detected intensity of the first combined beam light signal, so as to determine whether the wafer to be detected is in the focal plane of the detection lens, thereby determining the optimal detection position of the wafer and improving the accuracy of wafer detection.
In one embodiment, detector 16 may be a single pixel detector (e.g., a conventional photodiode, avalanche diode, or photomultiplier tube)
In one embodiment, detector 16 may be an area array detector.
In one embodiment, the second combined beam (i.e., the second reflected beam) is focused by the first focusing lens 13 onto the inspection camera 14 after being reflected by the dichroic mirror 12, so as to obtain a high quality image in the inspection camera 14, thereby improving the accuracy of wafer inspection.
In one embodiment, the detection camera 14 may be an area-array camera or a line-array camera.
In one embodiment, the wafer inspection light source 10 may be turned off and the broad spectrum coherent light from the self-focusing light source 1 alone may be used to inspect whether the wafer to be inspected is located at the focal plane of the inspection objective 8.
In one embodiment, the self-focusing light source 1 may be turned off. In practice, the wafer to be inspected is placed on the focal plane of the inspection objective lens 8, and then the self-focusing light source 1 is turned off, and the inspection light emitted by the wafer inspection light source 10 is used alone to inspect the wafer to be inspected.
In one embodiment, the wafer inspection light source 10 may be a blue or white halogen lamp or a light emitting diode, and a suitable inspection light source is selected according to different wafer process requirements, so that system adjustment and optimization are easier to perform, and efficiency and performance of the system are improved.
In one embodiment, the self-focusing light can be split into two beams again through the second dichroic mirror 12, one beam is used as the focal plane of the self-focusing signal acquisition detection objective lens 8, the other beam is used as the detection light to detect the wafer to be detected, and another option is provided for wafer detection, i.e. wavelength detection can be replaced if the two wavelengths are different.
In one embodiment, the beam combination/splitting of the self-focusing light and the detection light can also be realized by a non-polarized beam-splitting and combining Shu Qijia filter and a polarized beam-splitting and combining Shu Qijia analyzer.
In one embodiment, the switching of the self-focusing light and the detection light can be achieved either by controlling the power supply of the light source or by adding an aperture stop or shutter behind the light source.
In combination with the foregoing embodiment, the present invention further provides a wafer detection system, which includes: a self-focusing system and a detection system;
The self-focusing system includes: the method comprises the steps that wide-spectrum coherent light emitted by a self-focusing light source 1 is split by a beam splitter and combiner 4 to obtain a first transmission light beam and a first reflection light beam, wherein the first transmission light beam is re-incident to the beam splitter and combiner 4 after passing through a shutter 5, a reference objective lens 6 and a total reflection mirror 7, and the first reflection light beam is re-incident to the beam splitter and combiner 4 after being reflected by a detection objective lens 8 and a wafer to be detected, and the first beam splitter and combiner 4 outputs first combined light;
The detector 16 detects the interference intensity of the first combined beam light to obtain a focal plane of the detection objective lens 8;
The detection system includes: the detection light emitted by the wafer detection light source 10 is split by the beam splitting and combining device 4 to obtain a second transmission light beam and a second reflection light beam, wherein the second transmission light beam is blocked by the shutter 5, and the second reflection light beam is reflected by the detection objective lens 8 and the wafer to be detected and then is re-incident to the beam splitting and combining device 4, and the second beam splitting and combining device 4 outputs second beam combining light;
And processing the second combined beam according to the detection camera 14 to obtain a detection result corresponding to the wafer to be detected.
In one embodiment, the wafer inspection system further includes a first collimating lens 2, and the broad spectrum coherent light emitted from the focusing light source 1 is first collimated by the first collimating lens 2, so as to ensure that the light can propagate in a more concentrated and parallel manner.
In one embodiment, the wafer inspection system further includes a second collimating lens 11, and the inspection light provided by the wafer inspection light source 10 is collimated by the second collimating lens 11, so as to ensure that the inspection light can propagate in a more concentrated and parallel manner.
In one embodiment, the wafer inspection system further includes a second focusing lens 15, and in implementation, the first beam of light is focused onto the detector 16 through the second focusing lens 15 after passing through the dichroic mirror 12, so as to enhance the capturing efficiency and accuracy of the detector 16 on the interference signal, and thus more accurately find the focal plane of the inspection objective lens 8.
In one embodiment, the wafer inspection system further includes a first focusing lens 13, and in implementation, the second combined beam (i.e. the second reflected beam) is focused by the first focusing lens 13 onto the inspection camera 14 after being reflected by the dichroic mirror 12, which is helpful for enhancing the definition and detail of the wafer image to be inspected, and is helpful for improving the inspection efficiency of the inspection system.
In combination with the foregoing embodiment, fig. 3 is a schematic diagram of a broad spectrum coherent light interference self-focusing optical path, and as shown in fig. 3, the method for detecting a wafer according to an embodiment of the present invention includes: step S1 to step S12. In step S1, the wide-spectrum coherent light emitted by the self-focusing light source 1 is split by the beam splitter/combiner 4 to obtain a first transmitted light beam and a first reflected light beam.
Specifically, the self-focusing light source 1 emits wide-spectrum coherent light, the wide-spectrum coherent light is split by the first beam splitter/combiner 4 to obtain a first transmitted light beam and a first reflected light beam, wherein the first transmitted light beam is a reference light path, and the first reflected light beam is a measurement light path.
Step S2, the first transmitted beam is re-incident to the beam splitting and combining device 4 after passing through the shutter 5, the reference objective 6 and the total reflection mirror 7.
And S3, reflecting the first reflected light beam by the detection objective lens 8 and the wafer to be detected, and then re-entering the beam splitting and combining device 4.
And S4, outputting first beam combination light by the beam splitting and combining device (4).
Specifically, when the first transmission light path and the first transmission light path reach the first beam splitter/combiner 4 after being reflected, the first beam splitter/combiner 4 splits the beam to output a first split beam.
Step S5, transmitting the first combined beam to the detector 16 by using the second dichroic mirror 12.
Specifically, the first combined beam passes through the second dichroic mirror 12, can be focused by the second focusing lens 15, and reaches the single-pixel detector 16.
Step S6, the detector 16 is used for detecting the interference intensity of the first combined beam light to obtain the focal plane of the detection objective lens 8.
Specifically, the interference intensity of the first combined beam is detected by the detector 16, the interference signal after combining the transmitted light and the reflected light is maximum when the optical path difference between the reference optical path and the measuring optical path is zero, and the interference signal is reduced until it disappears when the optical path difference between the reference optical path and the measuring optical path is increased, and the focal plane of the detection objective lens 8 is detected by the interference signal therebetween.
And S7, placing the wafer to be detected on the focal plane of the detection objective lens 8.
Specifically, the optical path is adjusted such that the distance between the beam splitter and combiner 4 and the reference objective lens 6 is equal to the distance between the beam splitter and combiner 4 and the detection objective lens 8, and when the distance between the reference objective lens 6 and the total reflection mirror 7 is equal to the distance between the detection objective lens 8 and the wafer 9, i.e. the wafer is in the focal plane of the detection objective lens 8.
Step S8, the wafer inspection light source 10 is used to provide the inspection light, and the inspection light is split by the beam splitter/combiner 4 to obtain a second transmitted beam and a second reflected beam.
Specifically, the detection light is combined with the wide-spectrum coherent light beam by the first dichroic mirror 3, and the combined detection light is split into a second transmitted light beam and a second reflected light beam by the beam splitting and combining device 4. The detection light can be collimated by the second collimating lens 11 and then combined with the wide-spectrum coherent light beam by the first dichroic mirror 3, so that the detection result of the wafer can be improved.
Step S9, the second transmitted light is blocked by the shutter 5.
Step S10, the second reflected light beam is reflected by the detection objective lens 8 and the wafer to be detected and then re-enters the beam splitting and combining device 4.
Step S11, the second dichroic mirror 12 reflects the second combined beam light toward the detection camera 14.
Specifically, the second combined beam, i.e., the second reflected beam, after being reflected by the second dichroic mirror 12, may be focused on the detection camera 14 by the first focusing lens 13.
Step S12, the wafer to be tested located on the focal plane of the test objective 8 is tested by using the test camera 14.
In combination with the above embodiment, when the wafer to be inspected is located on the focal plane of the inspection objective lens 8, the self-focusing light source 1 may be turned off, and the wafer to be inspected is directly inspected by using the inspection light.
In this specification, identical and similar parts of the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, the description is relatively simple for the embodiments described later, and reference is made to the description of the foregoing embodiments for relevant points.
The foregoing is merely illustrative of the present application, and the present application is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the scope of the present application should be included in the present application. Therefore, the protection scope of the application is subject to the protection scope of the claims.
Claims (10)
1. The utility model provides a wide spectrum coherent light interference self-focusing light path which characterized in that is applied to the wafer detection, the wide spectrum coherent light interference self-focusing light path includes: a self-focusing light source (1), a first dichroic mirror (3), a beam splitting and combining device (4), a detection objective lens (8), a wafer detection light source (10), a detection camera (14), a shutter (5), a reference objective lens (6), a total reflection mirror (7), a second dichroic mirror (12) and a detector (16), wherein the total reflection mirror (7) is positioned on the focal plane of the reference objective lens (6);
the self-focusing light source (1) is a wide-spectrum coherent light source and is used for emitting wide-spectrum coherent light;
the wafer detection light source (10) is a wafer detection light source and is used for providing detection light;
The first dichroic mirror (3) is used for transmitting the wide-spectrum coherent light to the beam splitting and combining device (4) and reflecting the detection light to the beam splitting and combining device (4);
The beam splitting and combining device (4) is used for splitting the wide-spectrum coherent light to obtain a first transmission light beam and a first reflection light beam, wherein the first transmission light beam is re-incident to the beam splitting and combining device (4) after passing through the shutter (5), the reference objective lens (6) and the total reflection mirror (7), and the first reflection light beam is re-incident to the beam splitting and combining device (4) after being reflected by the detection objective lens (8) and the wafer to be detected, and the first beam splitting and combining device (4) outputs first combined light;
The beam splitting and combining device (4) is further used for splitting the detection light to obtain a second transmission light beam and a second reflection light beam, wherein the second transmission light beam is blocked by the shutter (5), the second reflection light beam is reflected by the detection objective lens (8) and the wafer to be detected and then is re-incident to the beam splitting and combining device (4), and the beam splitting and combining device (4) outputs second combined light;
A second dichroic mirror (12) for transmitting the first combined beam towards the detector (16) and reflecting the second combined beam towards the detection camera (14);
The detector (16) is used for detecting the first combined beam so as to determine whether the wafer to be detected is positioned on the focal plane of the detection objective lens (8) according to the interference intensity of the first combined beam;
the inspection camera (14) is used for imaging and inspecting the wafer to be inspected which is positioned on the focal plane of the inspection objective lens (8).
2. The broad spectrum coherent light interference self-focusing optical path of claim 1, further comprising: a first collimating lens (2) and a second collimating lens (11);
the first collimating lens (2) is used for collimating the wide-spectrum coherent light emitted by the self-focusing light source (1);
the second collimating lens (11) is used for collimating the detection light emitted by the wafer detection light source (10).
3. The broad spectrum coherent light interference self-focusing optical path of claim 2, further comprising: a first focusing lens (13) and a second focusing lens (15);
the first focusing lens (13) is used for focusing the second combined beam light onto a detection camera (14);
the second focusing lens (15) is used for focusing the first combined beam onto a detector (16).
4. The broad spectrum coherent light interference self-focusing light path of claim 1, wherein said self-focusing signal detector (16) comprises a single pixel detector or an area array detector.
5. The broad spectrum coherent light interference self-focusing light path according to claim 1, characterized in that said detection camera (14) comprises an area array camera or a line array camera.
6. The broad spectrum coherent light interference self-focusing optical path of claim 1, wherein said wafer inspection light source (10) comprises a blue light, white light halogen lamp or light emitting diode.
7. The broad spectrum coherent light interference self-focusing optical path according to claim 1, characterized in that the self-focusing light source (1) is in an off state.
8. A wafer inspection system employing the broad spectrum coherent light interference self-focusing optical path of any one of claims 1-7, comprising: a self-focusing system and a detection system;
The self-focusing system includes: the method comprises the steps that wide-spectrum coherent light emitted by a self-focusing light source (1) is split by a beam splitting and combining device (4) to obtain a first transmission light beam and a first reflection light beam, wherein the first transmission light beam is re-incident to the beam splitting and combining device (4) after passing through a shutter (5), a reference objective lens (6) and a total reflection mirror (7), and the first reflection light beam is re-incident to the beam splitting and combining device (4) after being reflected by a detection objective lens (8) and a wafer to be detected, and the first beam splitting and combining device (4) outputs first beam combining light;
obtaining a focal plane of the detection objective lens (8) according to the interference intensity of the first combined light;
The detection system includes: the detection light emitted by the wafer detection light source (10) is split by the beam splitting and combining device (4) to obtain a second transmission light beam and a second reflection light beam, wherein the second transmission light beam is blocked by the shutter (5), the second reflection light beam is reflected by the detection objective lens (8) and the wafer to be detected and then is re-incident to the beam splitting and combining device (4), and the second beam splitting and combining device (4) outputs the second beam splitting and combining light;
and processing the second combined beam according to the detection camera (14) to obtain a detection result corresponding to the wafer to be detected.
9. A wafer inspection method, applied to the broad spectrum coherent light interference self-focusing optical path of any one of claims 1 to 7, comprising:
The method comprises the steps that wide-spectrum coherent light emitted by a self-focusing light source (1) is split by a beam splitting and combining device (4) to obtain a first transmission light beam and a first reflection light beam, wherein the first transmission light beam is re-incident to the beam splitting and combining device (4) after passing through a shutter (5), a reference objective lens (6) and a total reflection mirror (7), and the first reflection light beam is re-incident to the beam splitting and combining device (4) after being reflected by a detection objective lens (8) and a wafer to be detected, and the first beam splitting and combining device (4) outputs first beam combining light;
Transmitting the first combined beam of light to a detector (16) with a second dichroic mirror (12);
detecting the interference intensity of the first combined beam by using a detector (16) to obtain a focal plane of a detection objective lens (8);
placing a wafer to be detected on the focal plane of the detection objective lens (8);
the detection light emitted by the wafer detection light source (10) is split by the beam splitting and combining device (4) to obtain a second transmission light beam and a second reflection light beam, wherein the second transmission light beam is blocked by the shutter (5), the second reflection light beam is reflected by the detection objective lens (8) and the wafer to be detected and then is re-incident to the beam splitting and combining device (4), and the second beam splitting and combining device (4) outputs the second beam splitting and combining light;
reflecting the second combined beam towards a detection camera (14) with a second dichroic mirror (12);
a wafer to be inspected, which is located on the focal plane of the inspection objective lens (8), is inspected by an inspection camera (14).
10. Wafer inspection method according to claim 9, characterized in that the self-focusing light source (1) is turned off when the wafer to be inspected is located in the focal plane of the inspection objective (8).
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