An element deep ultraviolet laser damage threshold testing device and method

Abstract

A device and method for testing deep ultraviolet laser damage threshold of an element, the device comprising a first laser module configured to emit deep ultraviolet laser; a second laser module configured to emit ultrashort pulse laser with the same spot size as the first laser module; a beam combination module configured to make the laser emitted by the first laser module and the second laser module coaxial and emit the modulated laser to the test element; a detection module comprising a first detection unit and a second detection unit for detecting the energy of the light beam, the first detection unit being arranged on the light path between the beam combination module and the test element, and the second detection unit being arranged on the light path from the test element; and a control module connected with the first laser module and the second laser module respectively, for controlling the energy of the laser emitted by the first laser module and the second laser module, and determining the deep ultraviolet laser damage threshold of the test element according to the information sent by the first detection unit and the second detection unit.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of testing the anti-laser irradiation capability of elements, relates to the study or analysis of materials by measuring the chemical or physical properties of the materials, and in particular to an element deep ultraviolet laser damage threshold testing device and method. BACKGROUND

[0002] Deep ultraviolet lasers are widely used in the field of semiconductor device preparation such as chip manufacturing, and immersion deep ultraviolet lithography machines are also the core equipment for most chip manufacturing. However, deep ultraviolet lasers have high photon energy characteristics, which can not only easily induce irreversible material macroscopic damage in elements through multi-photon absorption effect, but also induce material modification effects such as color centers and atomic vacancy defects, which will also affect the deep ultraviolet optical properties of the material. Therefore, it is crucial to clearly evaluate the anti-deep ultraviolet laser irradiation capability of elements and obtain accurate deep ultraviolet laser damage thresholds to improve the technology of semiconductor device preparation.

[0003] In the traditional element deep ultraviolet laser damage threshold testing method, the state of the material after deep ultraviolet laser irradiation is usually observed by optical method, and only whether the material has structural damage is concerned. However, the high photon energy characteristics of deep ultraviolet laser will not only cause irreversible and macroscopic structural damage to the element, but also induce microscopic structural changes such as color centers and induced defects. These laser modification effects will also affect the deep ultraviolet optical properties and service life of the material. Since the traditional deep ultraviolet laser damage threshold testing method has low precision and poor sensitivity, it is urgent to invent a more precise element deep ultraviolet laser damage threshold testing device and method, which has great significance for improving the anti-irradiation capability of the element. SUMMARY

[0004] In view of the shortcomings of the prior art, the purpose of the present application is to provide an element deep ultraviolet laser damage threshold testing device and testing method to realize precise detection of deep ultraviolet laser-induced material damage.

[0005] To achieve the above object, the present application adopts the following technical scheme: a device for testing deep ultraviolet laser damage threshold of an element, comprising: a first laser module configured to emit deep ultraviolet laser; a second laser module configured to emit ultrashort pulse laser with the same spot size as the laser emitted by the first laser module; a beam combining module configured to make the lasers emitted by the first laser module and the second laser module coaxial and emit the modulated laser to a test element; a detection module comprising a first detection unit and a second detection unit for detecting beam energy, the first detection unit being arranged on the optical path of the beam combining module and the test element, and the second detection unit being arranged on the optical path from the test element; and a control module connected with the first laser module and the second laser module respectively, configured to control the laser energy emitted by the first laser module and the second laser module, and determine the deep ultraviolet laser damage threshold of the test element according to the information sent by the first detection unit and the second detection unit.

[0006] As an embodiment of the present application, the first laser module comprises a deep ultraviolet laser for emitting deep ultraviolet laser and a first attenuator for adjusting the laser energy emitted by the deep ultraviolet laser, and the first attenuator is electrically connected with the control module; the second laser module comprises an ultrashort pulse laser for emitting ultrashort pulse laser and a second attenuator for adjusting the laser energy emitted by the ultrashort pulse laser, and the second attenuator is electrically connected with the control module.

[0007] As an embodiment of the present application, the second laser module further comprises a spatial light modulator arranged between the ultrashort pulse laser and the second attenuator, configured to adjust the ultrashort pulse laser emitted by the second laser module to have the same spot size as the laser emitted by the first laser module; wherein the spatial light modulator adjusts the spatial energy distribution of the laser emitted by the ultrashort pulse laser to be Gaussian distribution.

[0008] As an embodiment of the present application, the beam combining module comprises a beam combining mirror arranged on the optical path of the first laser module and the second laser module to make the lasers emitted by the first laser module and the second laser module coaxial and emit the modulated laser to the test element, wherein the beam combining module further comprises a focusing lens arranged on the optical path of the laser emitted by the beam combining mirror, configured to focus the laser emitted by the beam combining mirror and emit it to the test element.

[0009] As an embodiment of the present application, the first detection unit comprises a sampling mirror and a first energy meter, the sampling mirror is arranged on the light path of the beam combining module and the test element, and is used for dividing the light emitted from the beam combining module into refracted light and transmitted light, the first energy meter is arranged on the light path of the refracted light, and is used for detecting the beam quality of the refracted light; and the test element is arranged on the light path of the transmitted light.

[0010] As an embodiment of the present application, the second detection unit comprises a second energy meter and an adjustable aperture arranged in sequence on the light path of the test element, the adjustable aperture is used for adjusting the aperture size according to the property of the test element, and the second energy meter is used for detecting the beam quality of the laser after passing through the adjustable aperture; and the second detection unit comprises a CCD camera, which is used for shooting the structural damage of the test element.

[0011] In the second aspect of the present application, a test method for the deep ultraviolet laser damage threshold of an element is provided, which is based on the test device for the deep ultraviolet laser damage threshold of an element in the first aspect of the present application. The test method comprises the following steps: S120, closing the first laser module, adjusting the second laser module to different laser energies, and obtaining the standard transmittance-reflection ratio under each ultrashort pulse laser energy; S130, closing the second laser module, and controlling the first laser module to output deep ultraviolet laser with the first laser energy to irradiate the test element; S150, in the case that the topography is not damaged, closing the first laser module, controlling the second laser module to output ultrashort pulse laser with the first laser energy to obtain the transmittance-reflection ratio, and judging whether the difference between the transmittance-reflection ratio and the standard transmittance-reflection ratio under the first laser energy is within a set range; if not, determining the deep ultraviolet laser damage threshold of the test element; and if yes, adjusting the first laser energy to the second laser energy, and repeating steps S130-S150.

[0012] As an embodiment of the present application, before step S120, the method further comprises the following step: S110, obtaining the standard morphology of the test element, and pre-adjusting the test device for the deep ultraviolet laser damage threshold of an element, wherein the pre-adjusting comprises adjusting the second laser module so that the ultrashort pulse laser emitted by the second laser module has the same size and energy distribution as the laser emitted by the first laser module.

[0013] As an embodiment of the present application, the pre-adjusting further comprises adjusting the beam combining mirror so that the ultrashort pulse laser and the deep ultraviolet laser are coaxial; and / or, the pre-adjusting comprises adjusting the aperture of the adjustable aperture based on the property of the test element, wherein the test element is a fused quartz material or a calcium fluoride crystal.

[0014] As an embodiment of the present application, after the step S130, before the step S150, the method further comprises the following step: S140: obtaining the morphology of the test element, comparing it with the standard morphology of the test element, observing whether the morphology of the test element is damaged, if it is damaged, determining the deep ultraviolet laser damage threshold of the test element; if it is not damaged, performing the step S150.

[0015] Compared with the prior art, the present application has the following beneficial effects:

[0016] 1. The present application evaluates the nonlinear self-focusing effect of the test element before and after deep ultraviolet laser irradiation by introducing an ultrashort pulse laser, accurately evaluates the microstructure changes and material modification of the material after deep ultraviolet laser irradiation, and solves the problem of the traditional damage test method that only uses visual technology and only focuses on whether the material has macrostructure changes as the material damage evaluation basis, thereby improving the test precision.

[0017] 2. The present application is aimed at the deep ultraviolet laser-induced material modification characteristics, records the nonlinear self-focusing effect changes of the material after deep ultraviolet laser irradiation, i.e. the phase changes of the ultrashort pulse laser, can obtain the modification changes of the microstructure of the material when the material has no macrostructure damage, realizes more physical information in the deep ultraviolet laser-induced material modification process, and provides help for related physical research.

[0018] 3. The present application can be used for precise testing of deep ultraviolet laser damage thresholds of any materials with different properties, different materials, different sizes, different functions, etc., and has high applicability. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0020] Figure 1 is a structural diagram of a test device for deep ultraviolet laser damage threshold of an element provided by the present application;

[0021] Figure 2 is a test method for deep ultraviolet laser damage threshold of an element provided by the present application;

[0022] Figure 3 is another test method for deep ultraviolet laser damage threshold of an element provided by the present application.

[0023] MARKED DESCRIPTION:

[0024] 8, test element; 9, motorized displacement stage;

[0025] 100, first laser module; 1, deep-ultraviolet laser; 2, first attenuator;

[0026] 200, second laser module; 11, ultra-short pulse laser; 12, spatial light modulator; 13, second attenuator;

[0027] 300, beam combination module; 3, beam combination mirror; 4, focusing lens;

[0028] 400, detection module; 410, first detection unit; 5, sampling mirror; 6, first energy meter; 7, beam quality analyzer; 420, second detection unit; 10, CCD camera; 14, adjustable aperture; 15, second energy meter;

[0029] 16, control module. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person skilled in the art without creative work fall within the protection scope of the present application. In addition, it should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application. In the present application, the orientation words such as "upper", "lower", "left", "right", "front", "back" generally refer to the upper, lower, left and right of the device in the actual use or working state, and the specific is the direction of the drawing surface in the drawings.

[0031] It should be noted that the description order of the following embodiments is not used as a limitation on the preferred order of the embodiments of the present application. In the following embodiments, the description of each embodiment has its own emphasis, and the parts not described in detail in a certain embodiment can be referred to the related description of other embodiments.

[0032] The deep-ultraviolet laser has the characteristics of high photon energy, which is extremely easy to induce material failure or damage through multi-photon absorption effect. An accurate deep-ultraviolet laser damage threshold of an element not only provides a safe irradiation boundary condition, but also provides reliable information for subsequent improvement of the element's laser irradiation performance.

[0033] In order to solve the problem of low test precision of the original element deep ultraviolet laser damage threshold test method, the element deep ultraviolet laser damage threshold test device and method are provided, the nonlinear self-focusing effect of the material before and after deep ultraviolet laser irradiation is evaluated by introducing ultrashort pulse laser, the macro damage and microscopic modification effect of the material induced by deep ultraviolet laser irradiation are observed in multiple dimensions by combining the visual observation of element damage in the traditional test method, the deep ultraviolet laser damage threshold test precision is improved, and more information of deep ultraviolet laser and material interaction can be obtained, thereby providing technical support for improving the element laser irradiation resistance.

[0034] Please refer to Figure 1 The element deep ultraviolet laser damage threshold test device is used for accurately evaluating the microscopic structure change and material modification of the test element 8 after deep ultraviolet laser irradiation. The device comprises a first laser module 100, a second laser module 200, a beam combination module 300, a detection module 400 and a control module 16. The first laser module 100 is used for emitting deep ultraviolet laser, the second laser module 200 is used for emitting ultrashort pulse laser, and the spot sizes of the lasers emitted by the first laser module 100 and the second laser module 200 are the same. The beam combination module 300 is arranged to make the lasers emitted by the first laser module 100 and the second laser module 200 coaxial, and emit the modulated laser to the test element 8, and the detection module 400 is used for detecting. The detection module 400 is used for detecting the laser damage state of the test element. The control module 16 is used for determining the deep ultraviolet laser damage threshold of the test element based on the detection data of the detection module 400.

[0035] The following will be further described.

[0036] Please refer to Figure 1 The first laser module 100 comprises a deep ultraviolet laser 1 and a first attenuator 2 arranged on the light path of the laser emitted by the deep ultraviolet laser 1. The deep ultraviolet laser 1 is used for emitting deep ultraviolet laser, and the first attenuator 2 is arranged on the light path of the laser emitted by the deep ultraviolet laser 1, and is used for adjusting the deep ultraviolet laser energy of the deep ultraviolet laser emitted by the deep ultraviolet laser 1. There are many embodiments of the deep ultraviolet laser and the first attenuator in the prior art, and details are not repeated.

[0037] The second laser module 200 comprises an ultra-short pulse laser 11 and a spatial light modulator 12 and a second attenuator 13 arranged in sequence on the light path of the laser emitted by the ultra-short pulse laser 11. The ultra-short pulse laser 11, the spatial light modulator 12 and the second attenuator 13 are arranged in sequence along the light path. The ultra-short pulse laser 11 is configured to emit ultra-short pulse laser. The spatial light modulator 12 is configured to adjust the spot size and energy distribution of the ultra-short pulse laser emitted by the ultra-short pulse laser 11. The spatial light modulator 12 can adjust the spot size of the ultra-short pulse laser emitted by the ultra-short pulse laser 11 to be consistent with the spot size of the deep ultraviolet laser emitted by the deep ultraviolet laser 1 in the first laser module 100. The second attenuator 13 is configured to adjust the laser energy (i.e. "light intensity") of the laser emitted by the spatial light modulator 12 after adjustment.

[0038] Preferably, the spatial light modulator 12 is configured to adjust the spatial energy distribution of the light emitted by the ultra-short pulse laser 11 to be Gaussian distribution. The advantage of this arrangement is that by adjusting the spatial energy distribution to be Gaussian distribution, the change in nonlinear self-focusing effect caused by the modification of the microstructure of the test element after being irradiated by the deep ultraviolet laser can be well observed by the ultra-short pulse laser. That is, when the microstructure of the test element 8 is modified, although the macrostructure is not damaged, due to the existence of the nonlinear self-focusing effect, the phase of the light beam energy focus when the test element is irradiated by the ultra-short pulse laser changes, thereby obtaining the information of the modification of the microstructure of the material when the macrostructure of the material is not damaged, and achieving more physical information in the process of deep ultraviolet laser-induced material modification, which helps related physical research.

[0039] Preferably, the second attenuator 13 is arranged such that the laser energy emitted thereby is lower than the damage threshold of the test element 8, so as to ensure that the light intensity during the testing of the test element by the ultra-short pulse laser according to the nonlinear self-focusing effect is lower than the damage threshold of the test element 8, and does not affect the test result of the deep ultraviolet laser damage threshold.

[0040] Please continue to refer to Figure 1 The beam combining module 300 comprises a beam combining mirror 3 and a focusing lens 4. The beam combining mirror 3 and the focusing lens 4 are arranged in sequence along the light path, and the focusing lens 4 is configured to receive the light emitted by the beam combining mirror 3. The beam combining mirror 3 is arranged on the light paths of the first laser module 100 and the second laser module 200, and is configured to make the lasers emitted by the first laser module 100 and the second laser module 200 coaxial. As for the beam combining mirror 3, its essence lies in selectively reflecting or transmitting different wavelengths by using a mirror surface, thereby realizing the propagation along the same path. There are many embodiments of the beam combining mirror 3 in the prior art, and thus no further description is given.

[0041] The focusing lens 4 is arranged on the light path of the light emitted from the beam combining mirror 3, and is used for focusing the laser emitted from the beam combining mirror 3, and then emitting the focused laser to the test element 8.

[0042] Please continue to refer to Figure 1 The detection module 400 comprises a first detection unit 410 and a second detection unit 420. The first detection unit 410 is arranged on the light path between the beam combining module 300 and the test element 8, and is used for detecting the incident energy and the beam energy of the deep ultraviolet laser before irradiating the test element. The second detection unit 420 is arranged on the light path of the light emitted from the test element 8, and is used for detecting the damage condition of the test element.

[0043] Specifically, the first detection unit 410 comprises a sampling mirror 5, a first energy meter 6 and a beam quality analyzer 7. The sampling mirror 5 is arranged on the light path between the focusing lens 4 of the beam combining module 300 and the test element 8, and is used for dividing the laser emitted from the beam combining module 300 into refracted light and transmitted light. The first energy meter 6 and the beam quality analyzer 7 are arranged on the light path of the refracted light, and the test element 8 is arranged on the light path of the transmitted light. The beam quality analyzer 7 is used for analyzing the beam quality of the refracted light, and the first energy meter 6 is used for detecting the energy of the refracted light.

[0044] The second detection unit 420 comprises a CCD camera 10, an adjustable aperture 14 and a second energy meter 15. The CCD camera 10 is arranged close to the test element 8, and is used for observing the structural damage condition of the test element 8, and is mainly used for observing whether the test element 8 produces irreversible damage patterns. The adjustable aperture 14 and the second energy meter 15 are arranged on the light path of the light emitted from the test element 8 in sequence. The aperture of the adjustable aperture 14 is adjustable, and the aperture size is preferably set to be the same as the diameter of the spot of the laser emitted from the test element 8. The second energy meter 15 is used for detecting the energy of the light emitted from the test element 8.

[0045] Therefore, the element deep ultraviolet laser damage threshold test device provided by the present application can well realize the measurement of the deep ultraviolet laser damage threshold of the test element.

[0046] Preferably, the element deep ultraviolet laser damage threshold test device further comprises an electric displacement platform 9, which is used for carrying the test element 8 to adjust the position of the test element 8, so as to realize the laser irradiation on different positions of the test element.

[0047] Please refer to Figure 2 、 Figure 3 The steps of measuring the deep ultraviolet laser damage threshold by using the element deep ultraviolet laser damage threshold test device provided by the present application will be further described below.

[0048] Optionally, S110, a standard form of the test element is obtained, and the element deep ultraviolet laser damage threshold testing device is pre-adjusted, the pre-adjustment including adjusting the second laser module to emit the ultra-short pulse laser with the same size and energy distribution as the laser emitted by the first laser module.

[0049] In order to further ensure the accuracy of the experiment, therefore, before starting the experiment, first of all, the pre-adjustment of the testing device is carried out to ensure the accuracy of the whole experimental results. Of course, when the testing device itself has been adjusted or has been adjusted, it can also start directly and skip this step.

[0050] The pre-adjustment includes adjusting the second laser module 200 to emit the ultra-short pulse laser with the same size and energy distribution as the laser emitted by the first laser module 100. When adjusting the second laser module 200, first of all, the first laser module 100 is closed, and then the ultra-short pulse laser is emitted by the ultra-short pulse laser 11 so that the ultra-short pulse laser passes through the spatial light modulator 12. Then, the spatial size and energy distribution of the ultra-short pulse laser are adjusted by the spatial light modulator 12 to ensure that the ultra-short pulse laser is consistent with the deep ultraviolet laser and the energy distribution is Gaussian distribution.

[0051] Optionally, the pre-adjustment includes adjusting the beam combiner 3. At this time, the first laser module 100 and the second laser module 200 are turned on at the same time, and then the co-axiality of the ultra-short pulse laser and the deep ultraviolet laser is ensured by adjusting the beam combiner 3. Of course, the pre-adjustment also includes adjusting the adjustable aperture 14. The aperture of the adjustable aperture 14 can be adjusted according to the properties of the test element 8, such as the material composition of the test element 8.

[0052] For obtaining the standard form of the test element 8, the structure form of the test element 8 is mainly obtained for subsequent judgment of whether the appearance of the test element 8 is damaged. Of course, the standard form can be obtained by the CCD camera 10. The standard form is obtained by taking a photo of the test element 8 by the CCD camera 10. It can be understood that, when the photo has been taken by the CCD camera 10 or has been obtained by other means, it is not necessary to obtain it again before the experiment.

[0053] S120, the first laser module is closed, the second laser module is adjusted to different laser energy, and the standard transmittance and reflectance values under each ultra-short pulse laser energy are obtained.

[0054] When the second laser module 200 is adjusted to different laser energy, it is mainly achieved by adjusting the second attenuator 13. When the laser energy is adjusted by the second attenuator 13, the laser energy gradient value can be divided in proportion according to a certain gradient interval. The specific division standard can be divided according to the accuracy requirement of the measurement, and the specific division standard is not described here.

[0055] The preset ultrashort pulse laser emitted from the second attenuator 13 reaches the sampling mirror 5 after passing through the beam combiner 3, and the sampling mirror 5 divides the incident ultrashort pulse laser into refracted light and transmitted light.

[0056] The laser of the refracted light irradiates the first energy meter 6 and the beam quality analyzer 7 respectively to realize real-time monitoring of the incident laser energy and the beam quality. The laser of the transmitted light reaches the test element 8, irradiates the test element 8 with deep ultraviolet laser, and is detected by the second energy meter 15 after passing through the adjustable aperture 14. Preferably, in order to more accurately realize the detection of the refracted light, the sampling mirror 5 can divide the single refracted light into two beams by using the front and back two surfaces of the mirror, and the first energy meter 6 and the beam quality analyzer 7 correspond to the two beams respectively to test the energy and the beam quality by the two beams respectively. The beam quality analyzer 7 is mainly used for measuring the spot size of the light beam to realize the calculation of the spot size at the damage threshold.

[0057] Then the transmittance ratio is calculated according to the first energy meter 6 and the second energy meter 15. The transmittance ratio mainly refers to the ratio of the value obtained by the first energy meter when the refracted light of the same incident light reaches the first energy meter and the value obtained by the second energy meter 15 when the reflected light passes through the test element 8.

[0058] Then the ultrashort pulse laser energy emitted by the ultrashort pulse laser 11 is adjusted in order from low to high, and under the premise of ensuring that the ultrashort pulse laser energy density is lower than the damage threshold of the test element 8, the energy ratio of the first energy meter 6 and the second energy meter 15 after passing through the adjustable aperture 14 is recorded when different ultrashort pulse laser energies are irradiated. At this time, the ratio of the first energy meter 6 and the second energy meter 15 under each ultrashort pulse laser energy can be considered as the standard transmittance ratio, which can be used as the basis for judging whether the test element 8 is damaged.

[0059] It can be understood that, in order to avoid damage to the test element 8, the ultrashort pulse laser energy emitted by the ultrashort pulse laser 11 needs to be adjusted from low to high. If it is adjusted from high to low, the risk is greater because the damage threshold is unknown, and the test element 8 is easily damaged directly, resulting in a large cost loss.

[0060] S130, turn off the second laser module, and control the first laser module to output deep ultraviolet laser with the first laser energy to irradiate the test element.

[0061] After turning on the deep ultraviolet laser 1 of the first laser module 100, the deep ultraviolet laser irradiating the test element 8 is output with the first laser energy by adjusting the first attenuator 2.

[0062] S140, (optional) acquiring the morphology of the test element and comparing it with the standard morphology of the test element to observe whether the morphology of the test element is damaged, and if so, determining the deep-ultraviolet laser damage threshold of the test element; if not, performing step S150.

[0063] It can be understood that the purpose of this step is mainly to observe whether the test element 8 is structurally damaged. After the test element 8 is irradiated by the deep-ultraviolet laser, the morphology of the test element 8 is mainly obtained by taking a photo of the test element 8 by the CCD camera 10, and then compared with the standard morphology of the test element 8 to determine whether laser damage occurs. If the test element 8 has an irreversible damage morphology, the preset deep-ultraviolet laser energy step at this point is recorded as having induced element damage, and the deep-ultraviolet laser damage threshold of the test element 8 is determined accordingly. If the test element 8 does not have an irreversible damage morphology, the material can be tested for whether it has been modified by the ultra-short pulse laser, i.e., the subsequent steps are performed.

[0064] S150, turning off the first laser module and controlling the second laser module to output an ultra-short pulse laser at a first laser energy to obtain a ratio of refraction and transmission, and determining whether the ratio is within a set range compared with a standard ratio of refraction and transmission at the first laser energy. If not, determining the deep-ultraviolet laser damage threshold of the test element; if so, adjusting the first laser energy to a second laser energy and repeating steps S130-S150 until the deep-ultraviolet laser damage threshold of the test element is determined.

[0065] In this step, the first laser module 100 needs to be turned off first, and the second laser module 200 is controlled to output the same preset laser energy as the first laser module 100. For controlling the second laser module 200 to output the same preset laser energy as the first laser module 100, the second attenuator 13 is mainly adjusted to keep the ultra-short pulse laser energy consistent with the energy step in S1, so as to obtain the ratio of refraction and transmission.

[0066] It is determined whether the ratio is within a set range compared with a standard ratio of refraction and transmission at the same laser energy. If the ratio is not within the set range, the test element 8 at this position has been modified under deep-ultraviolet laser irradiation, and a change of nonlinear self-focusing effect is formed. At this time, it can be marked that the test element 8 has been damaged by deep-ultraviolet laser. It should be noted that the selection of the set range can be freely determined according to the precision requirement of the operator, and the present application does not limit it.

[0067] At this time, if it is not in the set range, there are various determination methods for determining the deep ultraviolet laser damage threshold of the test element 8. In a specific embodiment, the last laser energy can be identified as the deep ultraviolet laser damage threshold, that is, the last laser energy used before the change in the transmission ratio is considered as the deep ultraviolet laser damage threshold. In another specific embodiment, the deep ultraviolet laser damage threshold corresponding to the zero damage probability can also be obtained by linear fitting according to the recorded damage change of the deep ultraviolet laser at different energy steps, as the deep ultraviolet laser damage threshold of the test element 8.

[0068] It can be understood that the deep ultraviolet laser damage threshold can be directly identified as the laser damage threshold, or can be a value determined according to the laser energy and other parameters. In a specific embodiment, the laser energy can be directly considered as the laser damage threshold, and in another specific embodiment, the laser damage threshold is the ratio of the laser energy to the spot area, that is, the laser damage threshold = laser energy density = laser energy / spot area. At this time, the value of the spot size obtained by the beam quality analyzer 7 also needs to be obtained, and then the laser damage threshold is determined.

[0069] Preferably, in order to more accurately test the deep ultraviolet laser damage threshold of the test element, the second laser energy is preferably set to be greater than the first laser energy, and the damage change of the deep ultraviolet laser at different energy steps is recorded, that is, the laser energy in the experiment is in a state of continuous increase, so as to avoid irreversible damage to the test element 8.

[0070] In an optional embodiment, when the test element 8 is a material similar to quartz, calcium fluoride crystal, etc. (for example, the size is 50mm*50mm*20mm), the deep ultraviolet laser 1 can be an excimer laser with a wavelength of 100-200nm, a pulse width of 1-100ns, a near-field spot diameter of 1-10mm, and a single pulse laser energy of 1-500mJ. The ultrashort pulse laser 11 is an ultrashort pulse laser with a pulse width of 10fs-800ps and a wavelength of 100-2000nm.

[0071] The ultrashort pulse laser emitted by the ultrashort pulse laser 11 passes through the spatial light modulator 12, and the near-field spot diameter thereof is adjusted to be consistent with the near-field spot size of the deep ultraviolet damage test laser. Then the second attenuator 13 is used to adjust the ultrashort pulse laser energy from low to high. In an optional embodiment, the single pulse energy is adjusted from 1mJ to 200mJ 。The ratio change of the first energy meter 6 (E1) and the second energy meter 15 (E2), i.e. the ratio of the fold transmittance, is recorded. When the incident laser is a Gaussian spot with high central energy and low edge, under the influence of the nonlinear self-focusing effect of the material, the ratio of the fold transmittance (E2 / E1) will gradually decrease with the increase of the energy of the ultra-short pulse laser, and the corresponding change curve is recorded.

[0072] The ultra-short pulse laser 11 is turned off, the deep ultraviolet laser 1 is turned on, and the energy density irradiated to the test element 8 is adjusted to 8 J / cm2 by adjusting the first attenuator 2. After the deep ultraviolet laser single pulse irradiation is completed, the deep ultraviolet laser 1 is turned off, and the test element 8 is observed by using the CCD camera 10, and it is found that no macro-structural damage occurs.

[0073] The ultra-short pulse laser 11 is turned on again, and the single pulse energy can be adjusted from 1 mJ to 200 mJ by adjusting the second attenuator 13, and the ratio change of the first energy meter 6 (E1') and the second energy meter 15 (E2') is recorded. If the ratio of E1' / E2' and E1 / E2 changes obviously (increases or decreases), it indicates that after the deep ultraviolet laser irradiation, although no structural damage of the material is induced, the micro-physical structure of the test element 8 is modified.

[0074] The above steps are repeated to test the deep ultraviolet laser damage probability under different energy density steps. And the deep ultraviolet laser energy density (energy / area) at zero damage probability is obtained by linear fitting as the deep ultraviolet laser damage threshold of the test element 8.

[0075] Therefore, by introducing the ultra-short pulse laser and the corresponding nonlinear self-focusing effect testing device into the testing device, the nonlinear self-focusing effect of the test element before and after the deep ultraviolet laser irradiation is compared, and the macro-structural change and the micro-physical change of the element after the deep ultraviolet laser irradiation are precisely characterized by combining the optical visual discrimination material damage testing method in the traditional testing method, so that the precise detection of the deep ultraviolet laser induced material damage is realized. The present application not only solves the problem of low testing precision in the traditional testing method, but also can obtain more information of the deep ultraviolet laser induced material degradation, which provides help for the in-depth study of the physical law of the deep ultraviolet laser induced material damage.

[0076] Experimental example

[0077] The following will be specifically described by examples. The test element 8 is made of fused quartz (50mm*50mm*20mm), the deep ultraviolet laser 1 is an excimer laser with a wavelength of 193nm, a pulse width of 20ns, a near-field spot diameter of 6.5mm, and a maximum single-pulse laser energy of 200mJ. The ultra-short pulse laser 11 is an ultra-short pulse laser with a pulse width of 300fs, a wavelength of 1030nm, a near-field spot diameter of 8mm, and a maximum single-pulse laser energy of 10mJ. The focusing lens 4 is a lens with a focal length of 500mm, and the spot area irradiated to the test element 8 is 0.03mm 2 The adjustable aperture 14 is a small hole with a diameter of 1.5mm, and the sampling mirror 5 is a wedge-shaped plate with a splitting rate of 30%.

[0078] The ultra-short pulse laser emitted by the ultra-short pulse laser 11 passes through the spatial light modulator 12, and the near-field spot diameter is adjusted to 6.5mm, which is consistent with the near-field spot size of the deep ultraviolet damage test laser. The spatial energy distribution is adjusted to be Gaussian distribution, and the co-axiality with the deep ultraviolet damage test laser is adjusted by adjusting the beam combiner 3.

[0079] Then the ultra-short pulse laser energy is adjusted from low to high by the second attenuator 13, and the single-pulse energy is adjusted from 1mJ to 3mJ. The ratio change of the first energy meter 6 (E1) and the second energy meter 15 (E2) is recorded, that is, the transmittance ratio. Due to the Gaussian spot with high central energy and low edge, under the influence of the nonlinear self-focusing effect of the material, the transmittance ratio (E2 / E1) will gradually decrease with the increase of the ultra-short pulse laser energy, and the corresponding change curve is recorded.

[0080] The ultra-short pulse laser 11 is turned off, the deep ultraviolet laser 1 is turned on, and the energy density irradiated to the test element 8 is adjusted to 8J / cm2 by adjusting the first attenuator 2. After the single-pulse irradiation of the deep ultraviolet laser is completed, the deep ultraviolet laser 1 is turned off, and the test element 8 is observed by using the CCD camera 10. It is found that no macro-structural damage occurs. At this time, the ultra-short pulse laser 11 is turned on again, the single-pulse energy is adjusted from 1mJ to 3mJ by adjusting the second attenuator 13, and the ratio change of the first energy meter 6 (E1') and the second energy meter 15 (E2') is recorded. If the ratio of E1' / E2' and E1 / E2 changes obviously (increases or decreases), it indicates that the micro-physical structure of the test element 8 is modified after being irradiated by the deep ultraviolet laser, and the same is recorded as deep ultraviolet laser damage.

[0081] The above steps are repeated to test the deep ultraviolet laser damage probability under different energy density steps, and the deep ultraviolet laser energy density at which the zero damage probability is obtained through linear fitting is taken as the deep ultraviolet laser damage threshold of the test element 8, which is 7.63 J / cm2.

[0082] The above describes the schemes of the present application in detail, and the principles and implementation manners of the present application are described by using specific examples. The above description of the examples is only for helping to understand the method of the present application and its core idea; meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation manners and application ranges will be changed, and the above description of the present application should not be understood as a limitation of the present application.

[0083] Reference throughout this specification to "one embodiment", "an embodiment", or "a specific embodiment", means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present application, and is not necessarily included in all embodiments. Thus, appearances of the phrases "in one embodiment", "in an embodiment", or "in a specific embodiment" in various places throughout this specification are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, or characteristics of any specific embodiment of the present application can be combined in any suitable manner in one or more other embodiments. It is understood that other variations and modifications of the applications described and illustrated herein can be made based on the teachings herein, and are therefore within the scope of the present application.

[0084] It is also to be understood that one or more of the elements of the drawings shown can be implemented in a more separated or more integrated manner, or even removed, because in certain cases this is not operable or because it can be useful according to a specific application.

[0085] In addition, unless explicitly stated otherwise, any arrows shown in the drawings should be understood to represent exemplary directional flows of information, and not limitations. Further, unless specifically stated otherwise, the term "or" as used herein is generally intended to mean "and / or", that is, it is intended to include any and all combinations of one or more of the associated listed items. In the event that "or" is used to associate mutually exclusive items, such usage will be specifically indicated as such.

Claims

1. A device for testing the damage threshold of components using deep ultraviolet laser, characterized in that, The application relates to a deep ultraviolet laser damage threshold test device. The device comprises: a first laser module configured to emit deep ultraviolet laser; a second laser module configured to emit ultrashort pulse laser with the same spot size as the laser emitted by the first laser module; a beam combining module configured to make the lasers emitted by the first laser module and the second laser module coaxial and emit the modulated laser to a test element; a detection module comprising a first detection unit and a second detection unit for detecting the energy of the light beam, the first detection unit is arranged on the light path of the beam combining module and the test element, and the second detection unit is arranged on the light path from the test element; and 2. The device for testing the damage threshold of an element to a deep ultraviolet laser according to claim 1, characterized by, a control module connected with the first laser module and the second laser module respectively, used for controlling the energy of the laser emitted by the first laser module and the second laser module, and determining the deep ultraviolet laser damage threshold of the test element according to the information sent by the first detection unit and the second detection unit. The first laser module comprises a deep ultraviolet laser for emitting deep ultraviolet laser and a first attenuator for adjusting the energy of the laser emitted by the deep ultraviolet laser, and the first attenuator is electrically connected with the control module; 3. The device for testing the damage threshold of an element to a deep ultraviolet laser according to claim 2, characterized in that, The second laser module comprises an ultrashort pulse laser for emitting ultrashort pulse laser and a second attenuator for adjusting the energy of the laser emitted by the ultrashort pulse laser, and the second attenuator is electrically connected with the control module. The second laser module further comprises a spatial light modulator arranged between the ultrashort pulse laser and the second attenuator, used for adjusting the ultrashort pulse laser emitted by the second laser module to have the same spot size as the laser emitted by the first laser module; wherein, 4. The device for testing the damage threshold of an element to a deep ultraviolet laser according to any one of claims 1 to 3, characterized in that, The spatial light modulator adjusts the spatial energy distribution of the laser emitted by the ultrashort pulse laser to be Gaussian distribution. The beam combining module comprises a beam combining mirror arranged on the light path of the first laser module and the second laser module to make the lasers emitted by the first laser module and the second laser module coaxial, and emit the modulated laser to the test element, wherein, 5. The device for testing the damage threshold of an element to a deep ultraviolet laser according to any one of claims 1 to 3, characterized in that, The beam combining module further comprises a focusing lens arranged on the light path of the laser emitted by the beam combining mirror, used for focusing the laser emitted by the beam combining mirror and then emitting the laser to the test element.

6. The device for testing the damage threshold of an optical component for deep ultraviolet laser radiation according to claim 5, characterized in that The first detection unit comprises a sampling mirror arranged on the light path of the beam combining module and the test element, used for dividing the light emitted by the beam combining module into refracted light and transmitted light, and a first energy meter arranged on the light path of the refracted light, used for detecting the beam quality of the refracted light; and the test element is arranged on the light path of the transmitted light. The second detection unit comprises an adjustable aperture and a second energy meter arranged in sequence on the light path from the test element, the adjustable aperture is used for adjusting the aperture size according to the properties of the test element, and the second energy meter is used for detecting the beam quality of the laser after passing through the adjustable aperture. The second detection unit comprises a CCD camera for photographing the structural damage of the test element.

7. A method of testing a deep ultraviolet laser damage threshold of an element based on the apparatus for testing a deep ultraviolet laser damage threshold of an element according to any one of claims 1 to 6, characterized by, The test method comprises: S120: turn off the first laser module, adjust the second laser module to different laser energy, and obtain the standard transmittance reflectance value under each ultra-short pulse laser energy; S130: turn off the second laser module, and control the first laser module to output deep ultraviolet laser at the first laser energy to irradiate the test element; S150: turn off the first laser module, control the second laser module to output ultra-short pulse laser at the first laser energy to obtain the transmittance reflectance value, and determine whether the difference between the transmittance reflectance value and the standard transmittance reflectance value under the first laser energy is within a set range; if not, determine the deep ultraviolet laser damage threshold of the test element; if yes, adjust the first laser energy to the second laser energy, and repeat steps S130-S150.

8. The method of claim 7, wherein the element is a deep-ultraviolet laser damage threshold testing method, characterized by, Before the step S120, the method further comprises the following steps: S110: obtain the standard form of the test element, and pre-adjust the element deep ultraviolet laser damage threshold test device; the pre-adjustment comprises adjusting the second laser module so that the ultra-short pulse laser emitted by the second laser module has the same size and energy distribution as the laser emitted by the first laser module.

9. The method of claim 8, wherein the element is a deep-ultraviolet laser damage threshold testing method, characterized by, The pre-adjustment further comprises adjusting the beam combiner so that the ultra-short pulse laser and the deep ultraviolet laser are coaxial; And / or, the pre-adjustment comprises adjusting the aperture of the adjustable aperture based on the properties of the test element; the test element is a fused quartz material or a calcium fluoride crystal.

10. The method of claim 7-9, wherein, After the step S130 and before the step S150, the method further comprises the following steps: S140: obtain the form of the test element, compare it with the standard form of the test element, and observe whether the test element has morphology damage; if yes, determine the deep ultraviolet laser damage threshold of the test element; If not, perform the step S150.

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