Second harmonic characterization optical system and detection device based on second harmonic characterization

Abstract

The present invention provides a second harmonic characterization optical system and a detection device based on second harmonic characterization. The second harmonic characterization optical system adds a beam shaping module on the optical path between the polarizer and the first objective lens, shapes the polarized fundamental frequency light of the Gaussian beam into the polarized fundamental frequency light of the flat-top beam, and then focuses it into the fundamental frequency light that meets the test requirements through the first objective lens, and then incidents the fundamental frequency light to the sample to be detected. Compared with the method in the prior art in which the fundamental frequency light incident on the surface of the wafer is a Gaussian beam, the present application makes the light intensity inside the spot of the fundamental frequency light incident on the surface of the sample to be detected uniform, so that the second harmonic signal can be uniformly generated inside the spot, thereby improving the accuracy of the second harmonic characterization of the defects of the sample to be detected.

Description

Technical Field

[0001] The present invention relates to the technical field of characterization using nonlinear optical effects between materials and lasers, and in particular to a second harmonic characterization optical system and a detection device based on second harmonic characterization. Background Art

[0002] As the feature size of microelectronic devices continues to decrease, the problems caused by defects in wafers are becoming more and more serious. In order to improve the performance, yield and reliability of microelectronic devices, a variety of wafer defect characterization technologies have been developed. Such as but not limited to: optical beam induced current (OBIC), X-ray diffraction (XRD), transmission electron microscopy (TEM), and second harmonic generation (SHG). Among them, optical beam induced current can detect the location of defects, but it depends on special device structures; X-ray diffraction can analyze polymorphic dislocations based on diffraction spectra, but it takes a long time to obtain wafer-level defect information; transmission electron microscopy can obtain high-resolution defect images, but sample preparation is destructive. Second harmonic generation, as a fast, non-destructive, and non-contact characterization technology, has been widely used in the field of wafer-level defect characterization. For example, second harmonic generation can be used to locate and identify structural defects such as stacking faults and dislocations on SiC wafers, and second harmonic generation can be used to analyze metal contamination on the surface and buried interface of SOI (Silicon-On-Insulator, silicon on insulating substrate) wafers. Second harmonic generation can be used to measure the electro-active oxygen gap in high-resistance silicon wafers.

[0003] However, in the second harmonic detection system, the laser beam output by the laser is directly passed through the polarizer and the objective lens in sequence to form a fundamental frequency light that meets the test requirements and is incident on the wafer surface. Since the laser beam output by the laser is a Gaussian beam, the light spot obliquely incident on the wafer is elliptical, and the light intensity inside the light spot is uneven, and the second harmonic signal generated in the light spot is also uneven, resulting in a decrease in the accuracy of second harmonic characterization of wafer defects. Summary of the invention

[0004] The present invention provides a second harmonic characterization optical system and a detection device based on second harmonic characterization, which improve the accuracy of second harmonic characterization of defects of a sample to be detected.

[0005] In the first aspect, the present invention provides a second harmonic characterization optical system, which includes a support structure and a sample stage arranged on the support structure and used to hold the sample to be detected thereon. It also includes an incident light path system and an exit light path system. Among them, the incident light path system is used to incident fundamental frequency light on the sample to be detected. After the fundamental frequency light is incident on the sample to be detected, a second harmonic signal carrying sample defect information can be generated, and the second harmonic signal is emitted along the direction of the light beam reflected from the surface of the sample to be detected. The exit light path system includes a detector for collecting the second harmonic signal in the detector. When the incident light path system is set, the incident light path system includes a laser, a polarizer, a beam shaping module and a first objective lens. Among them, the laser is used to emit a laser beam. The polarizer is opposite to the laser position, and is used to polarize the laser beam into a polarized fundamental frequency light with a set polarization state, and the polarized fundamental frequency light is a Gaussian beam. The beam shaping module is opposite to the polarizer position, and is used to shape the polarized fundamental frequency light into a flat-top beam. The first objective lens is opposite to the beam shaping module and is used to focus the flat-top beam into fundamental frequency light that meets the test requirements and to incident the fundamental frequency light onto the sample to be tested.

[0006] In the above scheme, by adding a beam shaping module in the optical path between the polarizer and the first objective lens, the polarized fundamental frequency light of the Gaussian beam is shaped into the polarized fundamental frequency light of the flat-top beam, and then focused into the fundamental frequency light that meets the test requirements through the first objective lens, and the fundamental frequency light is incident on the sample to be tested. Compared with the prior art method in which the fundamental frequency light incident on the surface of the wafer is a Gaussian beam, the present application makes the light intensity inside the spot of the fundamental frequency light incident on the surface of the sample to be tested uniform, so that the second harmonic signal can be uniformly generated inside the spot, thereby improving the accuracy of the second harmonic characterization of the defects of the sample to be tested.

[0007] In a specific embodiment, the beam shaping module is also used to shape the spot of the polarized fundamental frequency light into a parallelogram spot. In the prior art, the spot of the laser beam of the Gaussian beam obliquely incident on the wafer is an ellipse. When performing the second harmonic mapping scan to obtain the surface defect information of the entire sample to be detected, the cross-section of the spot reaching the wafer surface is an ellipse, and the scanning points cannot be accurately spliced ​​and cover the entire wafer, resulting in a decrease in the accuracy of the second harmonic characterization of wafer defects. Compared with the prior art in which the spot obliquely incident on the wafer is an ellipse, the present application further shapes the spot of the fundamental frequency light into a parallelogram spot when shaping the Gaussian beam into a flat-top beam through the beam shaping module, so that when performing the second harmonic mapping scan to obtain the surface defect information of the entire sample to be detected, by making the cross-section of the spot reaching the surface of the sample to be detected a parallelogram, the spots of the adjacent front, back, left, and right scanning points can be accurately spliced ​​and cover the entire surface of the sample to be detected, further improving the accuracy of the second harmonic characterization of the defects of the sample to be detected.

[0008] In a specific embodiment, the parallelogram spot is a rectangular spot. When performing second harmonic mapping scanning to obtain the entire surface defect information of the sample to be detected, the spot of the fundamental frequency light incident on the surface of the sample to be detected is shaped into a rectangular spot, which facilitates the precise splicing of the spots of adjacent front, back, left and right scanning points.

[0009] In a specific embodiment, the rectangular light spot is a square light spot. When performing second harmonic mapping scanning to obtain the surface defect information of the entire sample to be detected, the light spot of the fundamental frequency light incident on the surface of the sample to be detected is shaped into a square light spot, so that the spacing between adjacent scanning points in the front, back, left and right are equal, thereby further facilitating the precise splicing of the light spots of adjacent scanning points in the front, back, left and right.

[0010] In a specific implementation, the beam shaping module is formed by an optical diffraction lens or a liquid crystal on silicon spatial light modulator to simplify the structure of the beam shaping module.

[0011] In a specific embodiment, the support structure includes an arc guide rail, and the sample stage is located at the center of the arc guide rail. An incident arm and an exit arm are slidably mounted on the arc guide rail, and the laser, polarizer, beam shaping module and first objective lens are all arranged on the incident arm, and the exit optical path system is arranged on the exit arm. It is convenient to set the support structure, and it is convenient to change the incident angle of the fundamental frequency light, and it is convenient to collect all the second harmonic signals generated by each scanning point in the detector.

[0012] In a specific embodiment, the output optical path system also includes a second objective lens, an analyzer, and a filter fixed on the output arm. The second objective lens is used to collimate the light beam reflected from the sample to be detected. The analyzer is opposite to the second objective lens, and is used to receive the light beam emitted from the second objective lens and perform polarization analysis to obtain output light of a set polarization state. The filter is opposite to the analyzer, and is used to filter out the fundamental frequency light in the output light to obtain a second harmonic signal. The detector is fixed on the output arm at a position opposite to the filter to receive the second harmonic signal. Simplify the setting of the output optical path system.

[0013] In a specific embodiment, the sample stage can move relative to the circular arc guide on three mutually perpendicular motion axes so that the fundamental frequency light scans the surface of the sample to be tested, facilitating the second harmonic mapping scan of the surface of the sample to be tested to obtain the entire surface defect information of the sample to be tested.

[0014] In a specific embodiment, the second harmonic characterization optical system also includes: a control module that is connected to the sample stage in communication, and is used to control the sample stage to drive the sample to be detected to move according to a preset scanning trajectory, so that when the fundamental frequency light scans the surface of the sample to be detected, the light spot of each scanning point can be seamlessly spliced ​​with the light spots of other adjacent scanning points in the front, back, left, and right directions. By adding a control module, the preset scanning trajectory is input into the control module, and the control module controls the movement of the sample stage, which not only improves the automation level of performing second harmonic mapping scanning on the surface of the sample to be detected to obtain the defect information of the entire surface of the sample to be detected, but also facilitates the precise splicing of the light spots of the adjacent scanning points in the front, back, left, and right directions.

[0015] In the second aspect, the present invention also provides a detection device based on second harmonic characterization, which includes any of the above-mentioned second harmonic characterization optical systems. By adding a beam shaping module in the optical path between the polarizer and the first objective lens, the polarized fundamental frequency light of the Gaussian beam is shaped into the polarized fundamental frequency light of the flat-top beam, and then focused by the first objective lens into the fundamental frequency light that meets the test requirements, and the fundamental frequency light is incident on the sample to be detected. Compared with the method in the prior art in which the fundamental frequency light incident on the surface of the wafer is a Gaussian beam, the present application makes the light intensity inside the spot of the fundamental frequency light incident on the surface of the sample to be detected uniform, so that the second harmonic signal can be uniformly generated inside the spot, thereby improving the accuracy of the second harmonic characterization of the defects of the sample to be detected. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the structure of a second harmonic characterization optical system provided by an embodiment of the present invention;

[0017] Figure 2 A schematic diagram of shaping a Gaussian beam into a flat-top beam provided in an embodiment of the present invention.

[0018] Reference numerals:

[0019] 10-Support structure 11-Sample stage 12-Sample to be tested

[0020] 20-incident arm 21-laser 22-polarizer

[0021] 23- beam shaping module 24- first objective lens 25- fundamental frequency light

[0022] 30- output arm 301- second harmonic signal 31- detector

[0023] 32- second objective lens 33- polarizer 34- filter DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] In order to facilitate understanding of the second harmonic characterization optical system provided by the embodiment of the present invention, the application scenario of the second harmonic characterization optical system provided by the embodiment of the present invention is first described below. The second harmonic characterization optical system is used in the process of detecting parameters such as semiconductor surface defects based on second harmonic characterization. The second harmonic characterization optical system is described in detail below in conjunction with the accompanying drawings.

[0026] refer to Figure 1 and Figure 2 , the second harmonic characterization optical system provided by an embodiment of the present invention includes a support structure 10, and a sample stage 11 arranged on the support structure 10 and used to hold the sample 12 to be detected thereon. It also includes an incident light path system and an exit light path system. Among them, the incident light path system is used to incident fundamental frequency light 25 to the sample 12 to be detected. After the fundamental frequency light 25 is incident on the sample 12 to be detected, it can generate a second harmonic signal 301 carrying sample defect information, and the second harmonic signal 301 is emitted along the direction of the light beam reflected from the surface of the sample 12 to be detected. The exit light path system includes a detector 31, which is used to collect the second harmonic signal 301 in the detector 31. When the incident light path system is set, the incident light path system includes a laser 21, a polarizer 22, a beam shaping module 23 and a first objective lens 24. Among them, the laser 21 is used to emit a laser beam. The polarizer 22 is opposite to the laser 21, and is used to polarize the laser beam into a polarized fundamental frequency light 25 with a set polarization state, and the polarized fundamental frequency light 25 is a Gaussian beam. The beam shaping module 23 is opposite to the polarizer 22, and is used to shape the polarized fundamental frequency light 25 into a flat-top beam. The first objective lens 24 is opposite to the beam shaping module 23, and is used to focus the flat-top beam into a fundamental frequency light 25 that meets the test requirements, and to incident the fundamental frequency light 25 onto the sample 12 to be tested.

[0027] In the above scheme, by adding a beam shaping module 23 on the optical path between the polarizer 22 and the first objective lens 24, the polarized fundamental frequency light 25 of the Gaussian beam is shaped into the polarized fundamental frequency light 25 of the flat-top beam, and then focused by the first objective lens 24 into the fundamental frequency light 25 that meets the test requirements, and the fundamental frequency light 25 is incident on the sample to be tested 12. Compared with the prior art method in which the fundamental frequency light 25 incident on the surface of the wafer is a Gaussian beam, the present application makes the light intensity inside the spot of the fundamental frequency light 25 incident on the surface of the sample to be tested 12 uniform, so that the second harmonic signal 301 can be uniformly generated inside the spot, thereby improving the accuracy of the second harmonic characterization of the defects of the sample to be tested 12. The following is a detailed introduction to the setting method of each of the above structures in conjunction with the accompanying drawings.

[0028] When the support structure 10 is provided, the support structure 10 is used as a carrier for providing the incident light path system, the outgoing light path system and the sample stage 11, and can be composed of a structure having a supporting function such as a frame and a guide rail. Figure 1 A support structure 10 is shown, and the support structure 10 includes an arc guide rail. The arc guide rail extends in an arc shape. A sample stage 11 is arranged at the center of the arc guide rail, and the sample stage 11 is used to place, support and fix a sample 12 to be tested. The sample 12 to be tested can specifically be a sample structure such as a wafer, a substrate, etc.

[0029] When setting the sample stage 11, the sample stage 11 can move relative to the circular arc guide on three mutually perpendicular motion axes, so that the sample 12 to be detected held on the sample stage 11 can move relative to the circular arc guide, so that the fundamental frequency light 25 scans the surface of the sample 12 to be detected, which is convenient for performing a second harmonic mapping scan on the surface of the sample 12 to be detected to obtain the surface defect information of the entire sample 12 to be detected. Specifically, a motion platform can be integrated in the sample stage 11, and the motion platform drives the sample stage 11 to move, and then drives the sample 12 to be detected to move on three mutually perpendicular motion axes, which is convenient for detecting different positions of the sample 12 to be detected, and also convenient for performing a second harmonic mapping scan on the surface of the sample 12 to be detected to obtain the surface defect information of the entire sample 12 to be detected.

[0030] like Figure 1As shown, an incident arm 20 and an exit arm 30 are slidably mounted on the circular arc guide rail, and the incident arm 20 and the exit arm 30 serve as the support structure 10 of the incident light path system and the exit light path system, respectively, and can slide on the circular arc guide rail. And the sliding trajectories of the incident arm 20 and the exit arm 30 are both circular arc trajectories, which can always slide around the sample stage 11. By adopting the above-mentioned setting method, it is convenient to set the support structure 10, and at the same time, it is convenient to change the incident angle of the fundamental frequency light 25, so that all the generated second harmonic signals 301 can be collected in the detector 31. It should be understood that the setting method of the support structure 10 is not limited to the method shown above, and other setting methods can also be adopted in addition to it. And the fixing method of the incident light path system and the exit light path system is not limited to the above-mentioned method of using the incident arm 20 and the exit arm 30, and other methods can also be adopted.

[0031] When setting up the incident light path system, Figure 1 An incident optical path system is shown, and the incident optical path system is used to incident fundamental frequency light 25 to the sample 12 to be detected. Specifically, the incident optical system includes a laser 21, a polarizer 22, a beam shaping module 23 and a first objective lens 24. Among them, the laser 21 is used to emit a laser beam, and the laser beam is a Gaussian beam. The polarizer 22 is opposite to the laser 21, and the polarizer 22 is used to polarize the laser beam into a polarized fundamental frequency light 25 with a set polarization state. Similarly, the polarized fundamental frequency light 25 is still a Gaussian beam. Reference Figure 2 The beam shaping module 23 is opposite to the polarizer 22, and is used to shape the polarized fundamental frequency light 25 into a flat-top beam. The first objective lens 24 is opposite to the beam shaping module 23, and is used to focus the flat-top beam into the fundamental frequency light 25 that meets the test requirements, and incident the fundamental frequency light 25 onto the sample to be tested 12. Compared with the prior art method in which the fundamental frequency light 25 incident on the surface of the wafer is a Gaussian beam, the present application adds a beam shaping module 23 on the optical path between the polarizer 22 and the first objective lens 24, shapes the polarized fundamental frequency light 25 of the Gaussian beam into the polarized fundamental frequency light 25 of the flat-top beam, and then focuses it through the first objective lens 24 into the fundamental frequency light 25 that meets the test requirements, and incidents the fundamental frequency light 25 onto the sample to be tested 12, so that the light intensity inside the light spot of the fundamental frequency light 25 incident on the surface of the sample to be tested 12 is uniform (such as Figure 2 The energy density comparison diagram of the Gaussian beam and the flat top beam shown in the figure) can make the second harmonic signal 301 uniformly generated inside the light spot, thereby improving the accuracy of the second harmonic characterization of the defects of the sample 12 to be detected. When the laser 21, the polarizer 22, the beam shaping module 23 and the first objective lens 24 are specifically fixed, the laser 21, the polarizer 22, the beam shaping module 23 and the first objective lens 24 can be arranged on the incident arm 20 in sequence, and the laser 21, the polarizer 22, the beam shaping module 23 and the first objective lens 24 are all fixed on the incident arm 20.

[0032] When the beam shaping module 23 is specifically set, the beam shaping module 23 can be mainly composed of an optical diffraction lens to simplify the structure of the beam shaping module 23. It should be understood that the configuration of the beam shaping module 23 is not limited to the above-mentioned method of using an optical diffraction lens, and other methods can also be used. For example, a silicon-based liquid crystal spatial light modulator can also be used to form the configuration of the beam shaping module 23.

[0033] In addition, the structural setting in the beam shaping module 23 can be adjusted so that the beam shaping module 23 can further shape the spot shape of the fundamental frequency light 25 while shaping the Gaussian beam into a flat-top beam, so that when the second harmonic Mapping scan is performed on the surface of the sample 12 to be detected to obtain the surface defect information of the entire sample 12 to be detected, it is convenient to seamlessly splice the spots at the adjacent front, back, left and right scanning points. In the specific setting, the beam shaping module 23 can shape the spot of the polarized fundamental frequency light 25 into a parallelogram spot. In the prior art, the spot of the laser beam of the Gaussian beam obliquely incident on the wafer is an ellipse. When performing the second harmonic Mapping scan to obtain the surface defect information of the entire sample 12 to be detected, since the cross-section of the spot reaching the wafer surface is an ellipse, the scanning points cannot be accurately spliced ​​and cover the entire wafer, resulting in a decrease in the accuracy of the second harmonic characterization of wafer defects. Compared with the prior art in which the light spot obliquely incident on the wafer is elliptical, the present application uses the beam shaping module 23 to further shape the light spot of the fundamental frequency light 25 into a parallelogram spot when shaping the Gaussian beam into a flat-top beam. Therefore, when performing the second harmonic mapping scan to obtain the surface defect information of the entire sample 12 to be detected, by making the cross-section of the light spot reaching the surface of the sample 12 to be detected a parallelogram, the light spots of adjacent front, back, left and right scanning points can be accurately spliced ​​and cover the entire surface of the sample 12 to be detected, thereby further improving the accuracy of the second harmonic characterization of the defects of the sample 12 to be detected.

[0034] When the beam shaping module 23 specifically shapes the parallelogram spot shape of the fundamental frequency light 25, the parallelogram spot can be specifically a rectangular spot. When performing the second harmonic mapping scan to obtain the surface defect information of the entire sample 12 to be detected, the spot of the fundamental frequency light 25 incident on the surface of the sample 12 to be detected is shaped into a rectangular spot, so that the spots of adjacent front, back, left, and right scanning points can be precisely spliced. In a more preferred embodiment, the rectangular spot can be a square spot. When performing the second harmonic mapping scan to obtain the surface defect information of the entire sample 12 to be detected, the spot of the fundamental frequency light 25 incident on the surface of the sample 12 to be detected is shaped into a square spot, so that the spacing between adjacent front, back, left, and right scanning points is equal, thereby further facilitating the precise splicing of the spots of adjacent front, back, left, and right scanning points. It should be understood that the above-mentioned parallelogram spot is not limited to the use of a rectangular spot. In addition, a non-rectangular but parallelogram spot shape can also be used. Likewise, the rectangular light spot is not limited to the shape of the square light spot shown above, and may also be in the shape of a long rectangular light spot.

[0035] refer to Figure 1 After the fundamental frequency light 25 emitted by the incident optical path system is incident on the sample 12 to be detected, a second harmonic signal 301 carrying the sample defect information can be generated. The second harmonic signal 301 enters the output optical path system along the direction of the light beam reflected by the sample 12 to be detected, and is collected in the detector 31 that receives the second harmonic signal 301. When setting the output optical path system, as shown in FIG. Figure 1 The output optical path system shown in the figure includes, in addition to the detector 31 fixed on the output arm 30, a second objective lens 32, an analyzer 33, and a filter 34, all of which are fixed on the output arm 30, and the second objective lens 32, the analyzer 33 and the filter 34 are all located on the same transmission optical path. The second objective lens 32 is used to collimate the light beam reflected from the sample 12 to be detected. The analyzer 33 is opposite to the second objective lens 32, and is used to receive the light beam emitted from the second objective lens 32 and perform polarization analysis to obtain the output light of the set polarization state. The filter 34 is opposite to the analyzer 33, and is used to filter out the fundamental frequency light 25 in the output light to obtain the second harmonic signal 301. The detector 31 is fixed on the output arm 30 at a position opposite to the filter 34 to receive the second harmonic signal 301. By adopting the output optical path system shown above, the setting of the output optical path system can be simplified. It should be understood that the above only exemplifies an outgoing light path system. In addition, other outgoing light path systems having a detector 31 and capable of receiving the reflected second harmonic signal 301 may also be used.

[0036] In a more preferred embodiment, a control module can be set up. The control module can be a terminal device such as a host computer, an industrial computer, a computer, a mobile terminal, etc. that can communicate with an external communication device and form a control instruction. The control module is a control module that is communicatively connected to the sample stage 11 to send a control instruction to the sample stage 11, and control the sample stage 11 to drive the sample 12 to be tested to move according to a preset scanning trajectory, so that when the base frequency light 25 scans the surface of the sample 12 to be tested, each scanning point can be seamlessly spliced ​​with the light spots of other adjacent scanning points in the front, back, left and right. The preset scanning trajectory can be set and input by the staff, or it can be calculated and generated by the control module according to a certain calculation algorithm. For example, the preset scanning trajectory can be composed of multiple parallel scanning lines, each scanning line is parallel to two parallel light spot edge lines in the parallelogram light spot, and the spacing between two adjacent scanning lines is equal to the spacing between the above two parallel light spot edge lines of the parallelogram light spot. Each scanning line is composed of multiple scanning points, and the distance between two adjacent scanning points on the same scanning line is equal to the distance between the other two parallel edge lines of the spot on the parallelogram spot. By adopting the above-mentioned preset scanning trajectory, it is possible to seamlessly splice the light spots of the adjacent front, back, left, and right scanning points in the process of performing second harmonic Mapping scanning on the surface of the sample 12 to be detected to obtain the surface defect information of the entire sample 12 to be detected, thereby forming a complete second harmonic Mapping scan to obtain the surface defect information map of the entire sample 12 to be detected. In the above method, by adding a control module, the preset scanning trajectory is input into the control module, and the control module controls the movement of the sample stage 11, which not only improves the degree of automation of performing second harmonic Mapping scanning on the surface of the sample 12 to be detected to obtain the surface defect information of the entire sample 12 to be detected, but also facilitates the precise splicing of the light spots of the adjacent front, back, left, and right scanning points.

[0037] In the various embodiments shown above, by adding a beam shaping module 23 on the optical path between the polarizer 22 and the first objective lens 24, the polarized fundamental frequency light 25 of the Gaussian beam is shaped into the polarized fundamental frequency light 25 of the flat-top beam, and then focused by the first objective lens 24 into the fundamental frequency light 25 that meets the test requirements, and the fundamental frequency light 25 is incident on the sample to be tested 12. Compared with the prior art method in which the fundamental frequency light 25 incident on the surface of the wafer is a Gaussian beam, the present application makes the light intensity inside the spot of the fundamental frequency light 25 incident on the surface of the sample to be tested 12 uniform, so that the second harmonic signal 301 can be uniformly generated inside the spot, thereby improving the accuracy of the second harmonic characterization of the defects of the sample to be tested 12.

[0038] Furthermore, the embodiment of the present invention also provides a detection device based on second harmonic characterization, referring to Figure 1 and Figure 2, the detection device includes any one of the above-mentioned second harmonic characterization optical systems. By adding a beam shaping module 23 to the optical path between the polarizer 22 and the first objective lens 24, the polarized fundamental frequency light 25 of the Gaussian beam is shaped into the polarized fundamental frequency light 25 of the flat-top beam, and then focused by the first objective lens 24 into the fundamental frequency light 25 that meets the test requirements, and the fundamental frequency light 25 is incident on the sample to be detected 12. Compared with the method in the prior art in which the fundamental frequency light 25 incident on the surface of the wafer is a Gaussian beam, the present application makes the light intensity inside the spot of the fundamental frequency light 25 incident on the surface of the sample to be detected 12 uniform, so that the second harmonic signal 301 can be uniformly generated inside the spot, thereby improving the accuracy of the second harmonic characterization of the defects of the sample to be detected 12.

[0039] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A second harmonic characterization optical system, characterized in that: include: Support structure; A sample stage disposed on the support structure and used to hold a sample to be tested thereon; An incident light path system for incident fundamental frequency light onto the sample to be detected; after the fundamental frequency light is incident on the sample to be detected, a second harmonic signal carrying sample defect information can be generated, and the second harmonic signal is emitted along the direction of the light beam reflected from the surface of the sample to be detected; An output optical path system including a detector, wherein the output optical path system is used to collect the second harmonic signal in the detector; Wherein, the incident light path system comprises: a laser for emitting a laser beam; A polarizer located opposite to the laser, the polarizer is used to polarize the laser beam into polarized fundamental frequency light with a set polarization state, wherein the polarized fundamental frequency light is a Gaussian beam; A beam shaping module located opposite to the polarizer, used for shaping the polarized fundamental frequency light into a flat-top beam; A first objective lens located opposite to the beam shaping module, the first objective lens being used to focus the flat-top beam into the fundamental frequency light meeting the test requirements, and to make the fundamental frequency light incident on the sample to be tested; The beam shaping module is also used to shape the light spot of the polarized fundamental frequency light into a parallelogram light spot; A control module connected to the sample stage in communication, the control module is used to control the sample stage to drive the sample to be detected to move along a preset scanning trajectory, the preset scanning trajectory is composed of a plurality of parallel scanning lines, each scanning line is parallel to two parallel spot edge lines in the parallelogram spot, and the spacing between two adjacent scanning lines is equal to the spacing between the two parallel spot edge lines of the parallelogram spot; and each scanning line is composed of a plurality of scanning points, and the spacing between two adjacent scanning points on the same scanning line is equal to the spacing between two other parallel spot edge lines on the parallelogram spot; The support structure includes an arc guide rail, and the sample stage is located at the center of the arc guide rail; the sample stage can move relative to the arc guide rail on three mutually perpendicular movement axes so that the fundamental frequency light scans the surface of the sample to be detected; An incident arm and an exit arm are slidably mounted on the arc guide rail; the laser, polarizer, beam shaping module and first objective lens are all arranged on the incident arm; and the exit optical path system is arranged on the exit arm.

2. The second harmonic characterization optical system according to claim 1, characterized in that: The parallelogram light spot is a rectangular light spot.

3. The second harmonic characterization optical system according to claim 2, characterized in that: The rectangular light spot is a square light spot.

4. The second harmonic characterization optical system according to any one of claims 1 to 3, characterized in that: The beam shaping module is composed of an optical diffraction lens or a silicon-based liquid crystal spatial light modulator.

5. The second harmonic characterization optical system according to claim 1, characterized in that: The output optical path system also includes: A second objective lens fixed on the output arm, used for collimating the light beam reflected from the sample to be detected; An analyzer fixed on the output arm and opposite to the second objective lens, used for receiving the light beam emitted from the second objective lens and performing polarization analysis to obtain output light of a set polarization state; A filter fixed on the output arm and opposite to the analyzer, used for filtering out the fundamental frequency light in the output light to obtain the second harmonic signal; The detector is fixed on the output arm at a position opposite to the filter to receive the second harmonic signal.

6. A detection device based on second harmonic characterization, characterized in that: The invention comprises the second harmonic characterization optical system as claimed in any one of claims 1 to 5.

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