Device and method for testing deep ultraviolet laser damage threshold of element

Abstract

The invention relates to a device and method for testing a deep ultraviolet laser damage threshold of an element, and the device comprises a first laser module which is set to emit deep ultraviolet laser; the second laser module is set to emit ultrashort pulse laser with the same light spot size as that of the first laser module; the beam combining module is arranged to enable the laser emitted by the first laser module and the laser emitted by the second laser module to be coaxial and emit the modulated laser to a test element; the detection module comprises a first detection unit and a second detection unit which are used for detecting light beam energy, the first detection unit is arranged on a light path of the beam combining module and the test element, and the second detection unit is arranged in a light path penetrating out of the test element; and the control module is respectively connected with the first laser module and the second laser module and is used for controlling laser energy emitted by the first laser module and the second laser module and determining a deep ultraviolet laser damage threshold value of the test element according to information sent by the first detection unit and the second detection unit.

Description

Technical Field

[0001] The present invention relates to the field of testing the laser radiation resistance of components, and to studying or analyzing materials by measuring their chemical or physical properties, and in particular to a device and method for testing the deep ultraviolet laser damage threshold of components. Background Art

[0002] Deep ultraviolet lasers are widely used in semiconductor component fabrication, including chip manufacturing, and immersion deep ultraviolet lithography equipment is a core component of most chip manufacturing. However, the high photon energy of deep ultraviolet lasers not only easily induces irreversible macroscopic material damage in components through multiphoton absorption, but also induces material modifications such as color centers and atomic vacancy defects, which also affect the material's deep ultraviolet optical properties. Therefore, clearly assessing the component's resistance to deep ultraviolet laser irradiation and obtaining an accurate deep ultraviolet laser damage threshold are key to improving semiconductor component manufacturing technology.

[0003] In traditional deep ultraviolet laser damage threshold test methods for components, optical methods are usually used to observe the state of the material after deep ultraviolet laser irradiation, and only focus on whether the material has structural damage. However, the high photon energy characteristics of deep ultraviolet lasers will not only cause irreversible and macrostructural damage to the components, but will also induce microstructural changes such as color centers and defects in the materials. These laser modification effects will also affect the deep ultraviolet optical characteristics and service life of the materials. Since traditional deep ultraviolet laser damage threshold test methods have problems such as low precision and poor sensitivity, there is an urgent need to invent a more precise component deep ultraviolet laser damage threshold test device and method, which is of great significance to the process improvement of improving the component's radiation resistance. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the object of the present invention is to provide a device and method for testing the deep ultraviolet laser damage threshold of a component, so as to achieve precise detection of deep ultraviolet laser-induced material damage.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solutions: a device for testing the deep ultraviolet laser damage threshold of a component, 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 component; a detection module, comprising a first detection unit and a second detection unit for detecting beam energy, the first detection unit being arranged in an optical path between the beam combining module and the test component, and the second detection unit being arranged in an optical path passing through the test component; and a control module, the control module being connected to the first laser module and the second laser module respectively, for controlling the laser energy emitted by the first laser module and the second laser module, and determining the deep ultraviolet laser damage threshold of the test component based on information sent by the first detection unit and the second detection unit.

[0006] As an embodiment of the present invention, the first laser module includes a deep ultraviolet laser and a first attenuator, the deep ultraviolet laser is used to emit deep ultraviolet laser, the first attenuator is used to adjust the laser energy emitted by the deep ultraviolet laser, and the first attenuator is electrically connected to the control module; the second laser module includes an ultrashort pulse laser and a second attenuator, the ultrashort pulse laser is used to emit ultrashort pulse laser, the second attenuator is used to adjust the laser energy emitted by the ultrashort pulse laser, and the second attenuator is electrically connected to the control module.

[0007] As an embodiment of the present invention, the second laser module further includes a spatial light modulator, which is arranged between the ultrashort pulse laser and the second attenuator and is used 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 a Gaussian distribution.

[0008] As an embodiment of the present invention, the beam combining module includes a beam combining mirror, which is arranged on the optical path of the first laser module and the second laser module so that the lasers emitted by the first laser module and the second laser module are coaxial, and the modulated lasers are emitted to the test element. The beam combining module also includes a focusing lens, which is arranged on the optical path of the laser emitted from the beam combining mirror, and is used to focus the laser emitted from the beam combining mirror and then emit it to the test element.

[0009] As an embodiment of the present invention, the first detection unit includes a sampling mirror and a first energy meter. The sampling mirror is arranged on the optical path of the beam combining module and the test element, and is used to divide the light emitted from the beam combining module into refracted light and transmitted light. The first energy meter is arranged on the optical path of the refracted light, and is used to detect the beam quality of the refracted light; the test element is arranged on the optical path of the transmitted light.

[0010] As an embodiment of the present invention, the second detection unit includes an adjustable hole and a second energy meter arranged in sequence in the light path passing through the test element, the adjustable hole is used to adjust the aperture size according to the properties of the test element, and the second energy meter is used to detect the beam quality of the laser after passing through the adjustable hole; wherein, the second detection unit includes a CCD camera for photographing the structural damage of the test element.

[0011] The second aspect of the present invention provides a component deep ultraviolet laser damage threshold testing method, based on the component deep ultraviolet laser damage threshold testing device described in the first aspect of the present invention, the testing method includes: S120: turning off the first laser module, adjusting the second laser module to different laser energies, and obtaining standard refractive index and transmittance ratio values ​​under various ultrashort pulse laser energies; S130: turning off the second laser module, controlling the first laser module to output deep ultraviolet laser according to the first laser energy to irradiate the test component; S150: when it is determined that the morphology is not damaged, turning off the first laser module, controlling the second laser module to output ultrashort pulse laser according to the first laser energy to obtain the refractive index and transmittance ratio value, and judging whether the difference between the refractive index and the standard refractive index and transmittance ratio value under the first laser energy is within a set range; if not, determining the deep ultraviolet laser damage threshold of the test component; if so, adjusting the first laser energy to the second laser energy, and repeating steps S130-S150.

[0012] As an embodiment of the present invention, before step S120, the following steps are also included: S110: obtaining the standard form of the test element and pre-adjusting the deep ultraviolet laser damage threshold test device of the element, the pre-adjustment including adjusting the second laser module so that the ultrashort pulse laser emitted by it has the same size and energy distribution as the laser emitted by the first laser module.

[0013] As an embodiment of the present invention, the pre-adjustment also includes adjusting the beam combiner to make the ultrashort pulse laser and the deep ultraviolet laser coaxial; and / or, the pre-adjustment includes adjusting the aperture of the adjustable hole based on the properties of the test element, and the test element is a fused quartz material or a calcium fluoride crystal.

[0014] As an embodiment of the present invention, after step S130 and before step S150, the following steps are also included: S140: obtaining the morphology of the test element and comparing it with the standard morphology of the test element to observe whether the test element has morphological damage. If so, determining the deep ultraviolet laser damage threshold of the test element; if not, performing step S150.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention uses ultrashort pulse lasers to evaluate the nonlinear self-focusing effect of the test element before and after deep ultraviolet laser irradiation, thereby accurately evaluating the microstructural changes and material modifications after deep ultraviolet laser irradiation. This solves the problem of traditional damage testing methods using purely visual technology solutions, which only focus on whether the material undergoes macrostructural changes as the basis for material damage evaluation, thereby improving test accuracy. 2. This invention focuses on the characteristics of deep ultraviolet laser-induced material modification. By recording the changes in the nonlinear self-focusing effect of the material after deep ultraviolet laser irradiation, that is, the phase change of the ultrashort pulse laser, it can obtain the modification changes that occur in the material's microstructure when the material does not suffer macroscopic structural damage. This can provide more physical information about the process of deep ultraviolet laser-induced material modification and provide assistance for related physical research. 3. The present invention can be used for precise testing of the deep ultraviolet laser damage threshold of any material with different properties, different materials, different sizes, different functions, etc., and has high applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 This is a structural diagram of a device for testing the deep ultraviolet laser damage threshold of a component provided by the present invention; Figure 2 The present invention provides a method for testing the deep ultraviolet laser damage threshold of a component; Figure 3 This is another method for testing the deep ultraviolet laser damage threshold of a component provided by the present invention.

[0018] Description of reference numerals: 8. Test components; 9. Electric displacement platform; 100. First laser module; 1. Deep ultraviolet laser; 2. First attenuator; 200, second laser module; 11, ultrashort pulse laser; 12, spatial light modulator; 13, second attenuator; 300, beam combining module; 3, beam combining mirror; 4, focusing lens; 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; 16. Control module. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention will be described clearly and completely 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, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention. In addition, it should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention. In the present invention, unless otherwise specified, the directional words used, such as "up", "down", "left", "right", "front", and "back", generally refer to the up, down, left, and right of the device in actual use or working state, specifically the drawing direction in the accompanying drawings.

[0020] It should be noted that the order of description of the following embodiments does not limit the preferred order of the embodiments of the present invention. In addition, in the following embodiments, the description of each embodiment has its own focus. For parts not described in detail in one embodiment, please refer to the relevant description of other embodiments.

[0021] The high photon energy of deep ultraviolet lasers can easily induce material failure or damage through multiphoton absorption. Accurately determining a component's deep ultraviolet laser damage threshold not only provides a safe boundary condition for irradiation but also provides reliable information for subsequent improvements in the component's resistance to laser radiation.

[0022] To address the low accuracy of existing deep ultraviolet laser damage threshold testing methods for components, the present invention attempts to provide a device and method for testing the deep ultraviolet laser damage threshold of components. By introducing ultrashort pulse lasers, the nonlinear self-focusing effect of materials before and after deep ultraviolet laser irradiation is evaluated. Combined with the visual observation of component damage in traditional testing methods, this method achieves multi-dimensional observation of the macroscopic damage and microscopic modification effects of materials induced by deep ultraviolet laser irradiation. This not only improves the accuracy of deep ultraviolet laser damage threshold testing, but also provides more information on the interaction between deep ultraviolet laser and matter, providing technical support for improving the component's resistance to laser irradiation.

[0023] See also Figure 1 The present invention first provides a device for testing the deep ultraviolet laser damage threshold of a component, which is used to accurately evaluate the microstructural changes and material modifications of the test component 8 after irradiation with a deep ultraviolet laser. It includes a first laser module 100, a second laser module 200, a beam combining module 300, a detection module 400 and a control module 16. The first laser module 100 is used to emit a deep ultraviolet laser, and the second laser module 200 is used to emit an ultrashort pulse laser. The spot sizes of the lasers emitted by the first laser module 100 and the second laser module 200 are the same. The beam combining module 300 is configured to enable the lasers emitted by the first laser module 100 and the second laser module 200 to be coaxial, and to emit the modulated laser to the test component 8, which is detected by the detection module 400. The detection module 400 is used to detect the laser damage state of the test component. The control module 16 is used to determine the deep ultraviolet laser damage threshold of the test component based on the detection data of the detection module 400.

[0024] This is further explained below.

[0025] See also Figure 1 The first laser module 100 includes a deep ultraviolet laser 1 and a first attenuator 2 disposed on the optical path of the laser light emitted by the deep ultraviolet laser 1. The deep ultraviolet laser 1 is configured to emit deep ultraviolet laser light. The first attenuator 2 is disposed on the optical path of the laser light emitted by the deep ultraviolet laser 1 and is configured to adjust the deep ultraviolet laser energy of the deep ultraviolet laser light emitted by the deep ultraviolet laser 1. Numerous implementations exist in the prior art for the deep ultraviolet laser and the first attenuator, and detailed descriptions thereof will not be repeated.

[0026] The second laser module 200 includes an ultrashort pulse laser 11 and a spatial light modulator 12 and a second attenuator 13, which are arranged in sequence on the optical path of the laser light emitted by the ultrashort pulse laser 11. The ultrashort pulse laser 11, the spatial light modulator 12, and the second attenuator 13 are arranged in sequence along the optical path. The ultrashort pulse laser 11 is used to emit ultrashort pulse laser light. The spatial light modulator 12 is used to adjust the spot size and energy distribution of the ultrashort pulse laser light emitted from the ultrashort pulse laser 11. The spatial light modulator 12 can adjust the spot size of the ultrashort pulse laser light emitted by the ultrashort pulse laser 11 to be consistent with the spot size of the deep ultraviolet laser light emitted by the deep ultraviolet laser 1 in the first laser module 100. The second attenuator 13 is used to adjust the laser energy (i.e., "light intensity") of the laser light emitted after adjustment by the spatial light modulator 12.

[0027] Preferably, the spatial light modulator 12 is used to adjust the spatial energy distribution of the light emitted by the ultrashort pulse laser 11 to a Gaussian distribution. This configuration has the advantage of enabling the ultrashort pulse laser to effectively observe the nonlinear self-focusing effect caused by the microstructural modifications of the test element after irradiation with the deep ultraviolet laser. Specifically, if the microstructure of the test element 8 undergoes modifications, even if the macrostructure remains intact, the nonlinear self-focusing effect can cause a phase shift in the energy focus of the beam when the ultrashort pulse laser is irradiated on the test element. This allows information on the microstructural modifications of the material without macrostructural damage to be obtained, providing more physical information about the deep ultraviolet laser-induced material modification process and assisting related physics research.

[0028] Preferably, the second attenuator 13 is configured so that the laser energy it emits is lower than the damage threshold of the test element 8, so as to ensure that the light intensity during the process of testing the test element using an ultrashort pulse laser based on the nonlinear self-focusing effect is lower than the damage threshold of the test element 8, and will not affect the deep ultraviolet laser damage threshold test results.

[0029] Please continue reading Figure 1 The beam combining module 300 includes a beam combining mirror 3 and a focusing lens 4. The beam combining mirror 3 and the focusing lens 4 are arranged sequentially along the optical path, and the focusing lens 4 is used to receive the light emitted by the beam combining mirror 3. The beam combining mirror 3 is arranged on the optical path of both the first laser module 100 and the second laser module 200, and is used to ensure that the lasers emitted by the first laser module 100 and the second laser module 200 are coaxial. The essence of the beam combining mirror 3 is to use a mirror to selectively reflect or transmit different wavelengths, thereby achieving their propagation along the same path. There are many implementation methods in the prior art, and the details will not be repeated here.

[0030] The focusing lens 4 is disposed on the optical path of the light emitted from the beam combiner 3 , and is used to focus the laser light emitted from the beam combiner 3 , and then emit the focused laser light to the test element 8 .

[0031] Please continue reading Figure 1 Detection module 400 includes a first detection unit 410 and a second detection unit 420. First detection unit 410 is provided in the optical path between beam combining module 300 and test element 8 and is used to detect the incident energy and beam energy of the deep ultraviolet laser before irradiating the test element. Second detection unit 420 is provided in the optical path from test element 8 and is used to detect damage to the test element.

[0032] Specifically, the first detection unit 410 includes a sampling mirror 5, a first energy meter 6, and a beam quality analyzer 7. The sampling mirror 5 is arranged in the optical path between the focusing lens 4 of the beam combining module 300 and the test element 8, and is used to separate the laser light 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 in the optical path of the refracted light, and the test element 8 is arranged in the optical path of the transmitted light. The beam quality analyzer 7 is used to analyze the beam quality of the refracted light, and the first energy meter 6 is used to detect the energy of the refracted light.

[0033] Second detection unit 420 includes a CCD camera 10, an adjustable aperture 14, and a second energy meter 15. CCD camera 10 is positioned near test element 8 to observe structural damage to test element 8, primarily to determine whether irreversible damage has occurred. Adjustable aperture 14 and second energy meter 15 are sequentially positioned in the path of light emitted from test element 8. The aperture of adjustable aperture 14 is adjustable, preferably set to the same size as the diameter of the laser spot emitted from test element 8. Second energy meter 15 is used to detect the energy of the light emitted from test element 8.

[0034] Therefore, the device for testing the deep ultraviolet laser damage threshold of a component provided by the present invention can well realize the measurement of the deep ultraviolet laser damage threshold of the test component.

[0035] Preferably, the device for testing the deep ultraviolet laser damage threshold of a component further includes an electric displacement platform 9, which is used to carry the test component 8 to adjust the position of the test component 8, thereby enabling laser irradiation at different positions of the test component.

[0036] See also Figure 2 、 Figure 3 The following further describes the steps of measuring the deep ultraviolet laser damage threshold using the component deep ultraviolet laser damage threshold testing device provided by the present invention.

[0037] (Optional) S110, obtaining the standard form of the test component and pre-adjusting the deep ultraviolet laser damage threshold test device of the component, wherein the pre-adjustment includes adjusting the second laser module so that the size and energy distribution of the ultrashort pulse laser emitted are the same as those of the laser emitted by the first laser module.

[0038] In order to further ensure the accuracy of the experiment, the test device is pre-adjusted before starting the experiment to ensure the accuracy of the entire experimental results. Of course, when the test device itself has been adjusted or adjusted, you can start directly and skip this step.

[0039] The pre-adjustment involves adjusting the second laser module 200 so that the size and energy distribution of the laser light emitted by the first laser module 100 are the same. When adjusting the second laser module 200, the first laser module 100 is first turned off. The ultrashort pulse laser 11 is then controlled to emit ultrashort pulse laser light, which passes through the spatial light modulator 12. The spatial light modulator 12 then adjusts the spatial size and energy distribution of the ultrashort pulse laser light to ensure that the ultrashort pulse laser light remains consistent with the deep ultraviolet laser light and that the energy distribution is Gaussian.

[0040] Optionally, pre-adjustment includes adjusting the beam combiner 3. At this point, the first laser module 100 and the second laser module 200 are simultaneously activated, and then the beam combiner 3 is adjusted to ensure that the ultrashort pulse laser and the deep ultraviolet laser are coaxial. Of course, pre-adjustment also optionally includes adjusting the adjustable aperture. The aperture of the adjustable aperture 14 can be adjusted accordingly based on the properties of the test element 8, such as the material composition of the test element 8.

[0041] Acquiring the standard form of test element 8 primarily involves capturing the structural form of test element 8 for subsequent determination of whether the morphology of test element 8 is damaged. Of course, this acquisition can preferably be performed using a CCD camera 10, whereby the test element 8 is photographed by the CCD camera 10 to obtain the standard form. It is understood that if the standard form has already been captured using a CCD camera 10 or other means, it is not necessary to reacquire it before the experiment.

[0042] S120 , turning off the first laser module, adjusting the second laser module to different laser energies, and obtaining standard refractive index and transmittance values ​​at various ultrashort pulse laser energies.

[0043] Adjusting the laser energy of the second laser module 200 to different levels is primarily accomplished by adjusting the second attenuator 13. When adjusting the laser energy of the second attenuator 13, the laser energy gradient values ​​can be proportionally divided according to a certain gradient spacing. The specific division criteria can be determined based on the required measurement accuracy, and the details are omitted here.

[0044] The preset ultrashort pulse laser emitted from the second attenuator 13 passes through the beam combiner 3 and reaches the sampling mirror 5 . The sampling mirror 5 divides the incident ultrashort pulse laser into a refracted light portion and a transmitted light portion.

[0045] The laser of the refracted light part is irradiated to the first energy meter 6 and the beam quality analyzer 7 respectively, so as to realize real-time monitoring of the incident laser energy and beam quality. The laser of the transmitted light part 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 hole 14. Preferably, in order to more accurately realize the detection of the refracted light, the sampling mirror 5 can use the front and back surfaces of the mirror to divide the single refracted light into two beams of light. The first energy meter 6 and the beam quality analyzer 7 correspond to the two beams of light respectively, so as to test the energy and beam quality respectively through the two beams of light. Among them, the beam quality analyzer 7 is mainly used to measure the spot size of the light beam to realize the calculation of the spot size at the damage threshold.

[0046] The refractive index and transmittance value is then calculated based on the first energy meter 6 and the second energy meter 15. The refractive index and transmittance value refers to the ratio of the value obtained by the refracted light after passing through the sampling mirror 5 and the value obtained by the reflected light after passing through the test element 8 and the second energy meter 15.

[0047] Subsequently, the ultrashort pulse laser energy emitted by the ultrashort pulse laser 11 is controlled to be adjusted in sequence according to the laser energy gradient value from low to high. 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 hole 14 is recorded when irradiated with different ultrashort pulse laser energies. At this time, the ratio of the first energy meter 6 and the second energy meter 15 at each ultrashort pulse laser energy can be regarded as the standard refractive index and transmittance ratio value, which can be used as a basis for judging whether the test element 8 is damaged in the subsequent test.

[0048] 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, since the damage threshold is unknown, the risk of adjusting from high to low is greater, and it is easy to directly damage the test element 8, resulting in greater cost losses.

[0049] S130 , turning off the second laser module, and controlling the first laser module to output deep ultraviolet laser light according to the first laser energy to irradiate the test element.

[0050] After the deep ultraviolet laser 1 of the first laser module 100 is turned on, the first attenuator 2 is adjusted to output the deep ultraviolet laser according to the first laser energy to irradiate the test element 8 .

[0051] (Optional) S140, obtaining the morphology of the test element and comparing it with the standard morphology of the test element to observe whether the test element has morphological damage. If so, determining the deep ultraviolet laser damage threshold of the test element; if not, proceed to step S150.

[0052] It is understood that the purpose of this step is primarily to observe whether test element 8 exhibits structural damage. After test element 8 is irradiated with a deep ultraviolet laser, a CCD camera 10 is primarily used to photograph test element 8 to obtain its morphology. This morphology is then compared with the standard morphology of test element 8 to determine whether laser damage has occurred. If irreversible damage morphology is observed on test element 8, the preset deep ultraviolet laser energy step is recorded as induced damage, and the deep ultraviolet laser damage threshold of test element 8 is then determined accordingly. If no irreversible damage morphology is observed on test element 8, an ultrashort pulse laser can be used to test whether the material has been modified, thus proceeding to the subsequent steps.

[0053] S150: Turn off the first laser module, control the second laser module to output ultrashort pulse laser light at the first laser energy, obtain a refractive index (R / T) value, and determine whether the difference between the R / T value and the standard R / T value at the first laser energy is within a set range. If not, determine the deep ultraviolet laser damage threshold of the test component. If so, adjust the first laser energy to the second laser energy, and repeat steps S130-S150 until the deep ultraviolet laser damage threshold of the test component is determined.

[0054] In this step, the first laser module 100 must first be turned off, and the second laser module 200 must be controlled to output the same preset laser energy as the first laser module 100. Controlling the second laser module 200 to output the same preset laser energy as the first laser module 100 is primarily accomplished by adjusting the second attenuator 13 to maintain the ultrashort pulse laser energy consistent with the energy step in S1, thereby obtaining the refractive index and transmittance value.

[0055] A determination is made as to whether the refractive index and transmittance ratio of the test element 8 to the standard refractive index and transmittance ratio under the same laser energy are within a set range. If the ratio is not within the set range, then the position of the test element 8 has been modified under deep ultraviolet laser irradiation, thereby causing a change in the nonlinear self-focusing effect. In this case, it can be marked as deep ultraviolet laser-induced damage to the test element 8. It should be noted that the selection of the set range can be freely determined based on the operator's accuracy requirements and is not limited in this regard by the present invention.

[0056] At this time, if it is not within the set range, there are multiple ways to determine the deep ultraviolet laser damage threshold of the test element 8. In one specific embodiment, the previous laser energy can be identified as the deep ultraviolet laser damage threshold, that is, the laser energy used last time before the refractive index and transmittance ratio value changes are considered to be the deep ultraviolet laser damage threshold. In another specific embodiment, the deep ultraviolet laser energy density corresponding to zero damage probability can be obtained by linear fitting based on the recorded damage changes of the deep ultraviolet laser at different energy steps, and used as the deep ultraviolet laser damage threshold of the test element 8.

[0057] It is naturally understood that for deep ultraviolet laser damage thresholds, the laser energy can be directly determined as the laser damage threshold, or it can be a value determined based on the laser energy and other parameters. In one specific embodiment, the laser energy can be directly considered as the laser damage threshold. In another specific embodiment, the laser damage threshold is the ratio of laser energy to spot area, that is, laser damage threshold = laser energy density = laser energy / spot area. In this case, it is also necessary to obtain the value of the spot size obtained by the beam quality analyzer 7 to further determine the laser damage threshold.

[0058] 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 changes under different energy steps of the deep ultraviolet laser are recorded, that is, the laser energy is in a continuously increasing state during the experiment, thereby avoiding irreversible damage to the test element 8.

[0059] In an optional embodiment, when test element 8 is made of a fused silica-like material, calcium fluoride crystal, or the like (e.g., with dimensions of 50 mm * 50 mm * 20 mm), deep ultraviolet laser 1 can be an excimer laser with a wavelength of 100-200 nm, a pulse width of 1-100 ns, a near-field spot diameter of 1-10 mm, and a maximum single-pulse laser energy of 1-500 mJ. Ultrashort pulse laser 11 is an ultrashort pulse laser with a pulse width of 10 fs-800 ps and a wavelength of 100-2000 nm.

[0060] The ultrashort pulse laser emitted by the ultrashort pulse laser 11 passes through the spatial light modulator 12, and its near-field spot diameter is adjusted to be consistent with the near-field spot size of the deep ultraviolet damage test laser. The second attenuator 13 is then 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. 。 Record the change in the ratio of the first energy meter 6 (E1) to the second energy meter 15 (E2), i.e., the refractive index to transmittance ratio. When the incident laser is a Gaussian spot with high energy at the center and low energy at the edges, the refractive index to transmittance ratio (E2 / E1) will gradually decrease with increasing ultrashort pulse laser energy due to the material's nonlinear self-focusing effect. Record the corresponding curve.

[0061] The ultrashort pulse laser 11 was turned off, and the deep ultraviolet laser 1 was turned on. The energy density irradiated to the test element 8 was adjusted to 8 J / cm2 by adjusting the first attenuator 2. After the single pulse of deep ultraviolet laser irradiation was completed, the deep ultraviolet laser 1 was turned off, and the test element 8 was observed using the CCD camera 10, revealing no macroscopic structural damage.

[0062] Restart the ultrashort pulse laser 11 and adjust the single pulse energy from 1 mJ to 200 mJ by adjusting the second attenuator 13, which is determined according to the material. Record the change in the ratio of the first energy meter 6 (E1') to the second energy meter 15 (E2'). If the ratio of E1' / E2' shows a significant change (increase or decrease) from E1 / E2, it indicates that after deep ultraviolet laser irradiation at this location in the test element 8, although no structural damage was induced to the material, its microscopic physical structure was modified.

[0063] Repeat the above steps to test the deep ultraviolet laser damage probability under different energy density steps. And obtain the deep ultraviolet laser energy density (energy ÷ area) with zero damage probability through linear fitting as the deep ultraviolet laser damage threshold of the test element 8.

[0064] Therefore, the present invention introduces an ultrashort pulse laser and a corresponding nonlinear self-focusing effect test device into the test device, compares the nonlinear self-focusing effect of the test component before and after deep ultraviolet laser irradiation, and combines it with the optical visual identification of material damage test methods in traditional testing methods to accurately characterize the macroscopic structural changes and microscopic physical property changes of the component after deep ultraviolet laser irradiation, thereby achieving precise detection of deep ultraviolet laser-induced material damage. The present invention not only solves the problem of low test accuracy in traditional testing methods, but also can obtain more information on deep ultraviolet laser-induced material degradation, providing assistance for in-depth research on the physical laws of deep ultraviolet laser-induced material damage. Experimental example

[0065] The following is a detailed description of the specific implementation of the present invention by way of examples. The test element 8 is made of fused quartz material (size 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 single-pulse laser energy of a maximum of 200mJ. The ultrashort pulse laser 11 is an ultrashort pulse laser with a pulse width of 300fs, a wavelength of 1030nm, a near-field spot diameter of 8mm, and a single-pulse laser energy of a maximum 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 hole 14 is a small hole with a diameter of 1.5 mm, and the sampling mirror 5 is a wedge-shaped plate with a splitting rate of 30%.

[0066] The ultrashort pulse laser emitted by the ultrashort pulse laser 11 passes through the spatial light modulator 12, and its near-field spot diameter is adjusted to 6.5 mm, which is consistent with the near-field spot size of the deep ultraviolet damage test laser, and the spatial energy distribution is adjusted to Gaussian distribution. By adjusting the beam combiner 3, it is coaxial with the deep ultraviolet damage test laser.

[0067] Subsequently, the second attenuator 13 is used to adjust the ultrashort pulse laser energy from low to high, and the single pulse energy is adjusted from 1mJ to 3mJ, and the change in the ratio of the first energy meter 6 (E1) to the second energy meter 15 (E2), that is, the refractive index and transmittance ratio, is recorded. Since the incident laser is a Gaussian spot with high energy at the center and low energy at the edge, under the influence of the nonlinear self-focusing effect of the material, the refractive index and transmittance ratio (E2 / E1) will gradually decrease with the increase of the ultrashort pulse laser energy, and the corresponding change curve is recorded.

[0068] The ultrashort pulse laser 11 is turned off, and the deep ultraviolet laser 1 is turned on. The energy density irradiated to the test element 8 is adjusted to 8 J / cm2 by adjusting the first attenuator 2. After completing the deep ultraviolet laser single pulse irradiation, the deep ultraviolet laser 1 is turned off, and the test element 8 is observed using the CCD camera 10. It is found that no macroscopic structural damage occurs. At this time, the ultrashort pulse laser 11 is turned on again, and the single pulse energy is also adjusted from 1 mJ to 3 mJ by adjusting the second attenuator 13. The change in the ratio of the first energy meter 6 (E1') to the second energy meter 15 (E2') is recorded. If the ratio of E1' / E2' shows a significant change (increase or decrease) from E1 / E2, it indicates that after the deep ultraviolet laser irradiation at this location of the test element 8, although no structural damage is induced in the material, its microscopic physical structure is induced to be modified, which is also recorded as deep ultraviolet laser damage.

[0069] Repeat the above steps to test the deep ultraviolet laser damage probability under different energy density steps, and obtain the deep ultraviolet laser energy density with zero damage probability through linear fitting as the deep ultraviolet laser damage threshold of the test element 8, which is 7.63J / cm2.

[0070] The above is a detailed introduction to the scheme of the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

[0071] 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 invention, and not necessarily in all embodiments. Thus, the various appearances of the phrases "in one embodiment," "in an embodiment," or "in a specific embodiment" in different 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 invention may be combined with one or more other embodiments in any suitable manner. It should be understood that other variations and modifications of the embodiments of the invention described and illustrated herein are possible in light of the teachings herein and are considered part of the spirit and scope of the invention.

[0072] It should also be understood that one or more of the elements shown in the figures may also be implemented in a more separate or more integrated manner, or even removed because they are inoperable in certain circumstances or provided because they may be useful depending on the application.

[0073] In addition, unless otherwise expressly indicated, any marking arrows in the drawings should be regarded as illustrative only and not limiting. Furthermore, unless otherwise indicated, the term "or" as used herein is generally intended to mean "and / or." Where a term is unclear in providing separation or combination capabilities, the combination of components or steps will also be considered as indicated.

Claims

1. A device for testing the damage threshold of a component using deep ultraviolet laser, characterized in that: include: A first laser module is configured to emit deep ultraviolet laser light; a second laser module configured to emit an ultrashort pulse laser having 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 lasers to the test element; a detection module, comprising a first detection unit and a second detection unit for detecting beam energy, wherein the first detection unit is disposed in an optical path between the beam combining module and the test element, and the second detection unit is disposed in an optical path extending from the test element; as well as A control module is connected to the first laser module and the second laser module respectively, and is used 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.

2. The device for testing the deep ultraviolet laser damage threshold of a component according to claim 1, characterized in that: The first laser module includes a deep ultraviolet laser and a first attenuator, the deep ultraviolet laser is used to emit deep ultraviolet laser, the first attenuator is used to adjust the laser energy emitted by the deep ultraviolet laser, and the first attenuator is electrically connected to the control module; The second laser module includes an ultrashort pulse laser and a second attenuator. The ultrashort pulse laser is used to emit ultrashort pulse laser. The second attenuator is used to adjust the laser energy emitted by the ultrashort pulse laser. The second attenuator is electrically connected to the control module.

3. The device for testing the deep ultraviolet laser damage threshold of a component according to claim 2, characterized in that: The second laser module further includes a spatial light modulator, which is disposed between the ultrashort pulse laser and the second attenuator and is used 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 light emitted by the ultrashort pulse laser to a Gaussian distribution.

4. The device for testing the deep ultraviolet laser damage threshold of a component according to any one of claims 1 to 3, characterized in that: The beam combining module includes a beam combining mirror, which is 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 includes a focusing lens, which is disposed on an optical path of the laser light emitted from the beam combining mirror and is used for focusing the laser light emitted from the beam combining mirror and then emitting the laser light to the test element.

5. The device for testing the deep ultraviolet laser damage threshold of a component according to any one of claims 1 to 3, characterized in that: The first detection unit includes a sampling mirror and a first energy meter. The sampling mirror is arranged on the optical path of the beam combining module and the test element, and is used to separate the light emitted from the beam combining module into refracted light and transmitted light. The first energy meter is arranged on the optical path of the refracted light, and is used to detect the beam quality of the refracted light; the test element is arranged on the optical path of the transmitted light.

6. The device for testing the deep ultraviolet laser damage threshold of a component according to claim 5, characterized in that: The second detection unit includes an adjustable hole and a second energy meter sequentially arranged in the optical path from the test element, the adjustable hole is used to adjust the aperture size according to the properties of the test element, and the second energy meter is used to detect the beam quality of the laser after passing through the adjustable hole; Wherein, the second detection unit includes a CCD camera for photographing the structural damage of the test element.

7. A method for testing the damage threshold of a component by deep ultraviolet laser, based on the device for testing the damage threshold of a component by deep ultraviolet laser according to any one of claims 1 to 6, characterized in that: The test method includes: S120: Turn off the first laser module, adjust the second laser module to different laser energies, and obtain standard refractive index and transmittance ratio values ​​at various ultrashort pulse laser energies; S130: Turn off the second laser module and control the first laser module to output deep ultraviolet laser light according to the first laser energy to irradiate the test element; S150: Turn off the first laser module, control the second laser module to output ultrashort pulse laser according to the first laser energy to obtain a refractive index transmittance value, and determine whether the difference between the refractive index value and the standard refractive index transmittance 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 so, adjust the first laser energy to the second laser energy, and repeat steps S130-S150.

8. The method for testing the component deep ultraviolet laser damage threshold according to claim 7, characterized in that: Before step S120, the following steps are also included: S110: Obtaining a standard form of the test component and pre-adjusting the deep ultraviolet laser damage threshold test device of the component, wherein the pre-adjustment includes adjusting the second laser module so that the ultrashort pulse laser emitted by it has the same size and energy distribution as the laser emitted by the first laser module.

9. The method for testing the component deep ultraviolet laser damage threshold according to claim 8, characterized in that: The pre-adjustment further includes adjusting the beam combiner to make the ultrashort pulse laser and the deep ultraviolet laser coaxial; And / or, the pre-adjustment includes adjusting the aperture of the adjustable hole based on properties of the test element, and the test element is fused quartz material or calcium fluoride crystal.

10. The method for testing the component deep ultraviolet laser damage threshold according to any one of claims 7 to 9, characterized in that: After step S130 and before step S150, the following steps are further included: S140: Obtaining the morphology of the test element and comparing it with the standard morphology of the test element to observe whether the test element has morphological damage. If so, determining the deep ultraviolet laser damage threshold of the test element; If not, proceed to step S150.

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