Sapphire substrate through hole, superconducting quantum chip manufacturing method and superconducting quantum chip

Abstract

The invention discloses a sapphire substrate through hole, a superconducting quantum chip manufacturing method and a superconducting quantum chip. The sapphire substrate through hole manufacturing method comprises the following steps: cleaning and drying a sapphire substrate; the cleaned and dried sapphire substrate is fixed to a three-dimensional positioning platform, and the three-dimensional positioning platform is used for moving the sapphire substrate according to a preset machining position so as to achieve relative machining Bessel beam nanoscale displacement; a femtosecond laser light source system emits a Bessel beam according to preset laser process parameters, the Bessel beam is focused to at least one position of a to-be-machined through hole of a sapphire substrate according to a preset laser scanning path, and through hole machining is conducted on the at least one position. According to the invention, the problem that the through hole is difficult to be formed in the sapphire substrate is solved, the high-quality requirement of the through hole in the sapphire substrate in the superconducting quantum chip is met, and a solution is provided for the realization of large-scale expansion of superconducting quantum bits in the future.

Description

Technical Field

[0001] The present invention relates to the field of quantum communication technology, and in particular to a sapphire substrate through hole, a superconducting quantum chip manufacturing method and a superconducting quantum chip. Background Art

[0002] Superconducting quantum computing is one of the most likely quantum computing solutions to be put into practical use. Multi-layer stacking is the best solution to achieve large-scale expansion of superconducting quantum bits. In the multi-layer stacking process, through-silicon vias (TSV) are the most core process technology. The advantages of the TSV process are very obvious. The front and back sides are connected by perforating the inside of the wafer, which not only fully utilizes the front and back spaces of the wafer, but also solves the problem of dense wiring occupying space. However, compared with the TSV process in traditional semiconductor packaging technology, the TSV process of superconducting quantum chips has more difficulties to overcome.

[0003] Sapphire wafer substrates (hereinafter referred to as sapphire substrates) have recently been used to extend the coherence time of quantum bits. In the existing technology, the coherence time of quantum bits exceeds 300μs, which is crucial to improving the performance of superconducting quantum computers. In addition to extremely low overall dielectric losses, sapphire substrates have been shown to reduce dielectric losses at the substrate-metal interface compared to silicon substrates. Despite these advantages, sapphire substrates are not currently used for 3D integrated quantum bit chips because the Bosch process (a process for manufacturing deep silicon etching structures) commonly used to etch TSVs is not suitable for sapphire substrates, making the processing technology of sapphire substrates an obstacle to their widespread use in the field of superconducting quantum chip manufacturing.

[0004] Sapphire material itself has the characteristics of high hardness and great brittleness, so it is difficult to process using traditional mechanical or chemical methods. How to process through holes in sapphire substrates and ensure the quality of the processed holes has become an urgent problem to be solved in the development of quantum bit chips. Summary of the invention

[0005] In view of the above problems, the present invention is proposed to provide a sapphire substrate through hole, a superconducting quantum chip manufacturing method and a superconducting quantum chip that overcome the above problems or at least partially solve the above problems.

[0006] In a first aspect, an embodiment of the present invention provides a method for manufacturing a through hole in a sapphire substrate, comprising:

[0007] cleaning and drying the sapphire substrate;

[0008] The cleaned and dried sapphire substrate is fixed on a three-dimensional positioning platform, wherein the three-dimensional positioning platform is used to move the sapphire substrate according to a predetermined processing position to achieve nanometer-level displacement relative to the processed Bessel beam;

[0009] The Bessel beam is emitted according to preset laser process parameters through a femtosecond laser light source system, and the Bessel beam is focused to at least one position of a through hole to be processed on a sapphire substrate according to a preset laser scanning path, and the through hole processing is performed on the at least one position.

[0010] In one embodiment, the through-hole machining at the at least one position is performed in any one of the following ways: single-pulse machining, multi-pulse tapping machining, circular cutting machining and spiral machining.

[0011] In one embodiment, when the processing method is single-pulse processing, the laser process parameters of the Bessel beam emitted by the femtosecond laser light source system are set to: the wavelength of the output Bessel beam is 1030nm, the pulse width is 1-6ps, the single pulse energy range is 10-48μJ / pulse, and the repetition frequency is up to 200kHz.

[0012] In one embodiment, the pulse width of the Bessel beam output by the femtosecond laser light source system is 6 ps, and the energy of a single pulse is greater than 21 μJ / pulse and less than or equal to 48 μJ / pulse.

[0013] In one embodiment, the femtosecond laser light source system includes a femtosecond laser, a half-wave plate, a polarizer, a shutter, an aperture, an aconic lens, a plano-convex lens, a dichroic mirror, and a microscope objective lens, which are sequentially arranged along the optical path;

[0014] Accordingly, the process of emitting the Bessel beam by a femtosecond laser light source system includes:

[0015] The flux of the laser beam emitted by the femtosecond laser is adjusted by using the combination of the half-wave plate and the polarizing plate, and the on-off of the laser beam is controlled by the shutter to control whether the laser beam is used for processing;

[0016] When the laser beam is controlled to be used for processing, the diameter of the incident laser beam is controlled by the aperture, and then the laser beam is transformed into a Bessel beam by the conical lens. Then, the transformed Bessel beam is reduced to a preset size through the plano-convex lens, the dichroic mirror and the microscope objective lens to obtain a micro Bessel beam, and is focused onto the surface of the sapphire substrate so as to perform through-hole processing on the sapphire substrate using the micro Bessel beam.

[0017] In one embodiment, during the through-hole processing, compressed gas is introduced as processing auxiliary gas, and the compressed gas is compressed air or compressed inert gas.

[0018] In one embodiment, the gas pressure of the compressed gas is 1.3-3 MPa.

[0019] In one embodiment, the cleaning and drying of the sapphire substrate comprises:

[0020] The sapphire substrate is immersed in an acetone solution and ultrasonically cleaned for a preset time;

[0021] The sapphire substrate is taken out of the acetone solution and immersed in an isopropanol solution and ultrasonically cleaned for a preset time;

[0022] The sapphire substrate is taken out from the isopropanol solution, immersed in deionized water and subjected to ultrasonic cleaning for a preset time;

[0023] The cleaned sapphire substrate is dried using nitrogen gas.

[0024] In a second aspect, an embodiment of the present invention provides a method for manufacturing a superconducting quantum chip, the method comprising the steps of machining a through hole at at least one position on a sapphire substrate;

[0025] The step of machining a through hole at at least one position on the sapphire substrate is achieved by the aforementioned method for manufacturing a through hole on a sapphire substrate.

[0026] In a third aspect, an embodiment of the present invention provides a superconducting quantum chip, wherein the superconducting quantum chip is made of a sapphire substrate, and a through hole is opened on the sapphire substrate, and the through hole is manufactured by the sapphire substrate through hole manufacturing method as described above.

[0027] The beneficial effects of the above technical solution provided by the embodiment of the present invention include at least:

[0028] The above-mentioned sapphire substrate through hole, superconducting quantum chip manufacturing method and superconducting quantum chip provided by the embodiments of the present invention pioneered the use of non-diffraction Bessel beams to realize the processing of through holes on sapphire substrates, solving the problem of difficulty in opening through holes on sapphire substrates, meeting the high quality requirements of through holes on sapphire substrates, and avoiding the problems of cracks, remelting layers, splashing particles, small hole depth-to-diameter ratio, etc. that exist in the process of manufacturing through holes by traditional Gaussian beam lasers. The embodiments of the present invention well solve the problem of multi-layer stacking of sapphire substrates, and provide a solution for the realization of large-scale expansion of superconducting quantum bits in the future.

[0029] In addition, through the study of the influence of different pulse widths and different energies on the processing effect of sapphire materials, the present application found that when the pulse width is set to 6ps and the single pulse energy of the Bessel beam is greater than 21μJ / pulse and less than or equal to 48μJ / pulse, the processing effect on the sapphire substrate is better, and a through-hole structure with regular morphology and good quality can be produced, and the surface of the material can be kept relatively clean and regular.

[0030] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings.

[0031] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0033] Figure 1 Flow chart of a method for manufacturing a through hole in a sapphire substrate according to an embodiment of the present invention;

[0034] Figure 2 Schematic diagram of various components and optical paths in a femtosecond laser light source system for emitting a Bessel beam in an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0036] In order to solve the problem of processing micro-through holes on sapphire substrates in the prior art and ensure the quality of the processed through holes, the inventors of this application found that femtosecond laser micro-nano manufacturing technology has the characteristics of non-contact, no mask required, simple process, etc., and is suitable for micro-processing of hard and brittle materials. However, experiments have shown that there are problems such as micro-cracks, remelting layers, splashing particles, and small hole depth-to-diameter ratio in the laser processing process based on Gaussian beams, and the quality of sapphire substrate through hole processing cannot be guaranteed.

[0037] Therefore, considering the actual demand for high-quality microstructure of through holes in sapphire substrates used in the field of superconducting quantum chips, the inventors of the present application have designed a non-diffraction Bessel beam laser processing technology to prepare small-diameter, high-aspect-ratio, high-quality through holes required for superconducting quantum chips. The aperture of such through holes is usually above 8um and the depth is within 400um. Of course, the embodiment of the present invention does not limit the specific size and size of the through holes actually required to be processed on the sapphire substrate.

[0038] The inventors of this application chose the Bessel beam as the laser beam for drilling based on the following considerations: the Bessel beam is a laser beam with a special light field distribution, and its light intensity presents the distribution form of the Bessel function in the cross section (the light intensity distribution is concentric rings, the center light intensity is strong, and it decreases in a ring shape outward). It has a non-diffraction characteristic during propagation and can keep the light field distribution unchanged within a certain distance, which is significantly different from the traditional Gaussian beam.

[0039] Within a certain propagation distance, the spot size and shape of the Bessel beam remain basically unchanged. Moreover, the Bessel beam also has self-repairing properties. Even if there are some tiny impurities blocking the beam path, it will not have much impact on the effect of its optical operation.

[0040] Experimental studies have shown that the special intensity distribution and non-diffraction characteristics of Bessel beams can improve processing accuracy and quality. For example, when processing tiny holes, Bessel beams can form a ring-shaped energy deposition, making the processed hole wall smoother and the aperture more accurate.

[0041] The method for manufacturing a through hole in a sapphire substrate provided by an embodiment of the present invention is as follows Figure 1 As shown, the following steps may be included:

[0042] S11, cleaning and drying the sapphire substrate;

[0043] S12, fixing the cleaned and dried sapphire substrate on a three-dimensional positioning platform;

[0044] The three-dimensional positioning platform is used to move the sapphire substrate according to a predetermined processing position to achieve nanometer-level displacement relative to the Bessel beam used for processing;

[0045] S13, emitting a Bessel beam according to preset laser process parameters through a femtosecond laser light source system, and focusing the Bessel beam to at least one position of a through hole to be processed on the sapphire substrate according to a preset laser scanning path, and performing through hole processing on the at least one position.

[0046] When there is more than one position on the sapphire substrate where through holes need to be processed, the corresponding processing positions are scanned according to a preset processing sequence and a preset laser scanning path to achieve precise positioning at different positions.

[0047] In one embodiment, in the above step S11, the sapphire substrate may be cleaned and dried by the following specific implementation methods:

[0048] 1) Soak the sapphire substrate in an acetone solution and apply ultrasonic cleaning for a preset time;

[0049] The soaking and cleaning time in the acetone solution is 5-10 minutes.

[0050] 2) After taking the sapphire substrate out of the acetone (IPA) solution, immerse it in an isopropanol solution and apply ultrasonic cleaning for a preset time;

[0051] The duration of soaking and cleaning in the isopropyl acetone solution is, for example, 5-10 minutes.

[0052] 3) After removing the sapphire substrate from the isopropanol solution, immerse it in deionized water and apply ultrasonic cleaning for a preset time;

[0053] The duration of immersion and cleaning in the plasma water may be, for example, 5-10 minutes.

[0054] 4) Use nitrogen to blow dry the cleaned sapphire substrate.

[0055] The above-mentioned ultrasonic organic cleaning step using acetone, isopropyl ketone solution or the like can effectively remove organic matter and fine particles on the surface of the sapphire substrate, thereby ensuring the quality of subsequent hole opening.

[0056] In one embodiment, the processed sapphire substrate may be, for example, a single-side polished sapphire wafer substrate with a diameter of 50.8 mm and a thickness of 430 um.

[0057] In one embodiment, the three-dimensional positioning platform is mainly used for the initial positioning of sapphire. When the laser starts to scan according to a preset laser scanning path, the laser scanning is completed by moving the lens of the laser emission.

[0058] In the above step S12, the three-dimensional positioning platform can be, for example, a three-dimensional high-precision air-floating platform of the ANT130 model produced by Aerotech, which has a moving resolution of up to 10nm and a movable stroke of up to 160mm. During use, it can be combined with computer software programming control to achieve nanometer-level high-precision displacement of the sample to be processed relative to the laser beam.

[0059] Of course, the embodiments of the present invention are not limited to the above-mentioned three-dimensional positioning platforms, and the above-mentioned are merely examples.

[0060] In the embodiment of the present invention, a femtosecond laser light source system is used to generate and emit the Bessel beam.

[0061] In one embodiment, the femtosecond laser light source system includes a femtosecond laser, a half-wave plate, a polarizer, a shutter, an aperture, an aconic lens, a plano-convex lens, a dichroic mirror, and a microscope objective lens, which are sequentially arranged along an optical path;

[0062] Accordingly, the generation of Bessel beams can be as follows:

[0063] The flux of the laser beam emitted by the femtosecond laser is adjusted by using a combination of a half-wave plate and a polarizing plate, and the on and off of the laser beam is controlled by a shutter to control whether the laser beam is used for processing;

[0064] When the laser beam is controlled to be used for processing, the diameter of the incident laser beam is controlled by the aperture, and then the laser beam is transformed into a Bessel beam through a conical lens, and then the transformed Bessel beam is reduced to a preset size through a plano-convex lens, a dichroic mirror and a microscope objective lens to obtain a micro Bessel beam, and is focused onto the surface of the sapphire substrate, so as to perform through-hole processing on the sapphire substrate using the micro Bessel beam.

[0065] In the embodiment of the present invention, the shutter may be, for example, a mechanical shutter, an electronic shutter, etc.

[0066] In specific implementation, the above process can be realized by a variety of femtosecond laser light source systems with different specific structures, such as Figure 2 An example of the structure of a femtosecond laser light source system is shown below:

[0067] In this example, the components of the femtosecond laser light source system include, in order of generation and transmission of the laser light path: a femtosecond laser, a reflector 1, a half-wave plate, a polarizer, a mechanical shutter, a reflector 2, a reflector 3, an aperture, a reflector 4, a conical lens, a plano-convex lens 1, a dichroic mirror 1 and a microscope objective.

[0068] Figure 2 The auxiliary optical path is also schematically shown, and the auxiliary optical path includes components such as an illumination light source, a dichroic mirror 2, a plano-convex lens 2, a CCD image sensor, etc. The functions of each component will be explained one by one below.

[0069] Figure 2 In the figure, the black part represents the laser beam (including the initial laser beam and the subsequently generated Bessel beam), and the yellow part represents the illumination light provided by the illumination light source.

[0070] The femtosecond laser is used as a laser light source to provide an initial laser beam. The initial laser beam directly emitted by the femtosecond laser is a Gaussian beam, which passes through a series of subsequent optical path components and enters the axicon in parallel, where it is converted into a Bessel beam.

[0071] The above-mentioned half-wave plate is used to change the polarization state of light.

[0072] The above polarizer is used to control the polarization direction of light. The combination of half-wave plate and polarizer can change the flux of laser beam.

[0073] The function of the above-mentioned reflectors 1 to 4 is to reflect and change the propagation direction of the light beam. The specific number and position of the reflectors can be determined according to the number and direction of changes required for the light path.

[0074] The mechanical shutter is used to control the on and off of the laser beam. It is controlled to be open when the sapphire substrate needs to be processed, otherwise, the mechanical shutter is controlled to be closed.

[0075] The aperture is used to limit the diameter of the light beam.

[0076] The axicon is used to transform the parallel incident Gaussian laser to obtain a Bessel beam.

[0077] Due to the special geometric structure of the axicon of the conical lens (for example, the base angle of the axicon (the angle between the generatrix of the conical surface of the axicon and the axis of the axicon) is 1°, and the refractive index n=1.45), the incident Gaussian light beam (radius, for example, 3.8 mm) can be refracted and form a Bessel light beam under certain conditions.

[0078] The plano-convex lens 1 and the microlens form a telescope system, which functions to reduce the generated initial Bessel beam by a set ratio.

[0079] Dichroic mirror (including dichroic mirror 1 and dichroic mirror 2): used to reflect and transmit light of specific wavelengths and play a role in splitting light. Among them, dichroic mirror 1 is used to reflect part of the Bessel light beam coming out of the plano-convex lens into the microscope objective lens, and dichroic mirror 2 is used to split part of the light from the illumination light source to the plano-convex lens 2 and the CCD image sensor.

[0080] CCD image sensor: used to detect Bessel beams and collect image information processed by Bessel beams.

[0081] Microscope objective lens: It works with the plano-convex lens 1 to produce a miniature Bessel beam, generating a micro Bessel beam, and is also used to facilitate observation of the effect of the Bessel beam on drilling holes on the sapphire substrate (the three directions marked as x, y, and z in the figure).

[0082] The illumination light source is used to provide illumination light.

[0083] Figure 2 In the figure, below the microscope objective, the gray square represents the stage and the dark blue square represents the sapphire substrate.

[0084] The working process of the above-mentioned femtosecond laser light source system is briefly described as follows: the laser emitted by the femtosecond laser is processed by optical elements such as reflectors, half-wave plates, polarizers, mechanical shutters, and apertures, and then generates an initial Bessel beam through a conical lens, and then passes through elements such as a plano-convex lens 1 and a microscope objective lens to finally generate a micro Bessel beam for processing. At the same time, a CCD image sensor can be used to collect image information during the Bessel beam processing process.

[0085] It should be noted that Figure 2 What is shown is only an example of a specific femtosecond laser light source system. The embodiment of the present invention does not limit the specific structure of the femtosecond laser light source system, and any structure that can emit a Bessel beam according to preset process parameters is acceptable.

[0086] In one embodiment, in the above step S13, there may be multiple processing methods for processing a through hole on at least one position of the sapphire substrate, such as single pulse processing, multi-pulse tapping processing, circular cutting processing and spiral processing.

[0087] Single-pulse processing is a method of using a single femtosecond laser pulse to create a through hole on the material surface.

[0088] Multi-pulse tapping processing is a method of gradually creating through holes on the material surface by tapping by applying multiple femtosecond laser pulses.

[0089] Circular cutting processing is a method of using a femtosecond laser to perform circular cutting around the contour of the through hole, gradually removing material to form a through hole.

[0090] Spiral processing is a method of using a femtosecond laser to move in a spiral manner on the surface of a material while gradually penetrating deeper into the material to create a through hole.

[0091] In order to select a more suitable processing method, the inventors of the present application used Bessel beams with different numbers of pulses to process a sapphire substrate to obtain a through-hole structure under the same process parameters of laser energy E = 20μJ and laser pulse frequency R = 10Hz. Among them, the number of laser pulses was selected as 1, 5, 10, 50 and 100 respectively. The experimental results show that a single pulse can realize a complete through-hole cavity structure. When the number of pulses is increased, it is not good for improving the quality of the through-hole, but makes the quality of the through-hole worse. The diameter growth rate of the through-hole structure is much greater than the hole depth growth rate, which causes a decrease in the aspect ratio.

[0092] When a single-pulse processing method is used, the micro-Bessel beam can be focused onto the surface of the sapphire substrate to be processed, and the sapphire substrate Wiener structure can be efficiently processed in combination with a "time-of-flight" scanning method.

[0093] Based on this, preferably, in order to realize a slender, uniform and high aspect ratio through-hole structure, a single pulse Bessel beam may be used for processing.

[0094] In one embodiment, in step S13, when the through hole processing method is a single-pulse processing method, the laser process parameters of the femtosecond laser light source system for emitting a Bessel beam can be set to, for example, the wavelength of the output Bessel beam is 1030 nm, the pulse width is 1-6 ps, the single pulse energy range is 10-48 μJ / pulse, and the maximum repetition frequency is 200 kHz.

[0095] The inventor of this application focused on increasing the energy of a single laser pulse within the pulse width range of 1.5ps-10ps. This means that by changing the relevant parameters of the laser, in a specific pulse width variation range, by exploring the effects of different pulse widths and different energies on the processing effect of sapphire materials, the appropriate combination of processing parameters is determined to achieve high-quality micro-through-hole structures, providing a basis for accurate and high-quality processing of sapphire materials.

[0096] Specifically, the research results found that when the single pulse energy of the laser is increased within the range of pulse width of 1.5ps-10ps, the damage threshold of sapphire material is about 10.6μJ under the process parameter conditions of 2.5ps pulse width, and about 15.7μJ under the process parameter conditions of 6ps pulse width.

[0097] The damage threshold is a key indicator, which means that when the energy of a single laser pulse reaches or exceeds this value, the material may undergo damaging changes, such as structural destruction.

[0098] However, shorter pulse widths (1-1.5ps) do not seem to have a good effect on the formation of through-hole structures, and as the energy increases, the through-hole structures gradually disappear, and a shallow pit structure appears in the center of the irradiated area.

[0099] Under the process parameter condition of a pulse width of 6ps, single pulse energy settings of 21.5μJ to 48μJ produced micro-through hole structures with regular morphology and good quality, and no obvious traces of material ablation, splashing or deposition were observed. Only obvious irradiation-like traces were observed around the periphery of the micro-through hole.

[0100] Specifically, when the pulse width is set to 6ps and the single pulse energy is set to 21.5μJ / pulse in the processing parameters, the peak power density of the central spot distributed on the surface of the sapphire sample is about 0.44×10 13 W / cm 2 ; Under this process parameter condition, no damage signs were found.

[0101] The damage threshold of sapphire is affected by the pulse width. When the pulse width varies greatly, it is not accurate to use pulse energy to measure the damage threshold. The power density value is related to factors such as the damage threshold of the material at this pulse width, and can be used to accurately determine whether the material will be damaged. Therefore, peak power density is very suitable as a criterion for judging the damage threshold.

[0102] When the pulse width is set to 6ps and the single pulse energy is set to 48μJ / pulse, the first-order outer ring intensity of the Bessel beam is about 0.22×10 13 W / cm 2 , which is lower than the damage threshold, so the outer ring will not produce damage marks.

[0103] Under the process parameter conditions of pulse width set to 2.5ps and single pulse energy set to 15.7μJ / pulse, the peak power density of the central field of the Bessel beam is 1.06×10 13 W / cm 2 If the single pulse energy is set to 48 μJ / pulse, the first-order outer ring of the Bessel beam is only 0.5×10 13 W / cm 2 , which is also not enough to produce signs of damage.

[0104] Under the process parameter condition of pulse width set to 1ps, the same analysis method was used to find that when the single pulse energy was set to 48μJ / pulse, the peak power density of the outer ring of the Bessel beam reached 1.32×10 13 W / cm 2 , at this time the outer ring energy is as high as 1.32×10 13 W / cm 2 , enough to produce obvious signs of damage.

[0105] The above research shows that as the pulse width changes, the energy limit (damage threshold) that the material can withstand also varies. Under relatively wider pulse widths (6ps vs. 2.5ps), the material can withstand higher single pulse energy without being damaged.

[0106] As for the effect of pulse width on the formation of through-hole structure, it was found that shorter pulse width, that is, in the range of 1-1.5ps, has a poor effect on the formation of through-hole structure. Moreover, as the energy of the single laser pulse increases, the through-hole structure that was originally expected to be formed not only fails to be better presented, but gradually disappears, and is replaced by a shallow pit structure in the center of the irradiated area. This shows that within this pulse width range, the increase in energy does not develop in a direction that is conducive to the formation of through-holes, but instead causes different and undesirable structural changes.

[0107] Under the process parameter condition of a single pulse width of 6ps, the situation is quite different. When the single pulse energy is in the range of 21.5μJ to 48μJ, a through-hole structure with regular morphology and good quality can be produced. In this process, no obvious traces of material ablation, splashing or deposition were observed, and only obvious irradiation-like traces were observed around the through-hole. This shows that the pulse width combined with the corresponding energy range is a processing parameter combination that is more conducive to forming an ideal through-hole structure, has a better processing effect on the material, and can keep the material surface relatively clean and regular.

[0108] From the perspective of power density under different energies, when the processing parameters are 6ps (single pulse width) and 21.5μJ / pulse (single pulse energy), the peak power density of the central spot distributed on the surface of the sapphire substrate is about 0.44×1013W / cm 2 This strength is lower than the damage threshold, so the outer ring will not produce damage marks.

[0109] Under the process parameters of 6ps (single pulse width) and 48μJ / pulse (single pulse energy), the Bessel first-order outer ring intensity is about 0.22×1013W / cm 2 , the intensity is lower than the damage threshold, so no damage marks will be produced on the outer ring.

[0110] This means that under the parameters of 6ps (single pulse width), 21.5-48μJ / pulse, not only can the central area achieve better through-hole structure processing, but the outer ring area can also remain intact without damage due to excessive energy.

[0111] Under the process parameter conditions of 2.5ps (single pulse width) and 15.7μJ / pulse (single pulse energy), the overall impact on the material from the center to the outer ring area has not reached the level of causing damage.

[0112] However, under the process parameter condition of 1ps (single pulse width), using the same analysis method, when the single pulse energy reaches 48μJ / pulse, the peak power density of the outer ring reaches 1.32×1013W / cm 2, this energy is enough to produce obvious damage marks. This shows that in this case of shorter pulse width and higher energy, the outer ring area of ​​the material will be damaged due to excessive energy. Compared with the previous combinations of pulse width and energy, it can be seen that different parameters have obvious differences in the damage caused to the material.

[0113] Based on the above research, it is found that for processing micron-through holes in sapphire, the optimal processing parameter range is a larger pulse width and a high pulse energy. For example, when the pulse width is set to 6ps, the single pulse energy of the Bessel beam is greater than 21μJ / pulse and less than or equal to 48μJ / pulse.

[0114] In one embodiment, the method for manufacturing a through hole in a sapphire substrate provided by the embodiment of the present invention may further introduce compressed gas as a processing auxiliary gas during the through hole processing, and the compressed gas is compressed air or compressed inert gas.

[0115] Furthermore, the pressure of the compressed gas may be, for example, 1.3-3 MPa.

[0116] The auxiliary gas mentioned above can timely remove slag and debris, accelerate cooling, change the energy coupling efficiency between the laser and the material being processed (change the optical properties of the material surface so that the laser can be better absorbed by the material being processed, thereby improving drilling efficiency and quality), etc.

[0117] Through experiments, using the above-mentioned process parameters of single pulse width of 6ps and single pulse energy of 25μJ / pluse, a through hole with an aperture of 8um and a depth of 400um was successfully prepared on a sapphire substrate. The aspect ratio was 50, there were no microcracks around the hole, no remelted layer at the hole mouth, no spatter particles on the hole surface, and the quality and appearance were both good.

[0118] Based on the same inventive concept, an embodiment of the present invention further provides a method for manufacturing a superconducting quantum chip and a related superconducting quantum chip. The principles of the problems solved by the method are similar to those of the aforementioned method for manufacturing a through-hole in a sapphire substrate. Therefore, the implementation of the method for manufacturing a superconducting quantum chip and the related superconducting quantum chip can refer to the implementation of the aforementioned method for manufacturing a through-hole in a sapphire substrate, and the repeated parts will not be repeated.

[0119] An embodiment of the present invention provides a method for manufacturing a superconducting quantum chip, the method comprising the steps of machining a through hole at at least one position on a sapphire substrate;

[0120] The step of machining a through hole at at least one position on the sapphire substrate is achieved by the aforementioned method for manufacturing a through hole on a sapphire substrate.

[0121] An embodiment of the present invention provides a superconducting quantum chip, which is made of a sapphire substrate. The sapphire substrate is provided with a through hole, and the through hole is manufactured by the sapphire substrate through hole manufacturing method as described above.

[0122] The above-mentioned sapphire substrate through hole, superconducting quantum chip manufacturing method and superconducting quantum chip provided by the embodiments of the present invention pioneered the use of non-diffraction Bessel beams to realize the processing of sapphire substrate through holes, solving the problem of difficulty in opening through holes on sapphire substrates, realizing the application of non-diffraction Bessel beam processing technology in the field of superconducting quantum chip manufacturing, meeting the high quality requirements of through holes on sapphire substrates, and avoiding the problems of cracks, remelting layers, splashing particles, small hole depth-to-diameter ratio, etc. that exist in the through hole process of traditional Gaussian beam lasers. The embodiments of the present invention well solve the problem of multi-layer stacking of sapphire substrates, and provide a solution for the large-scale expansion of superconducting quantum bits in the future.

[0123] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for manufacturing a through hole in a sapphire substrate, characterized in that: include: cleaning and drying the sapphire substrate; Fixing the cleaned and dried sapphire substrate on a three-dimensional positioning platform, wherein the three-dimensional positioning platform is used to move the sapphire substrate according to a predetermined processing position to achieve nanometer-level displacement relative to a Bessel beam used for processing; The Bessel beam is emitted according to preset laser process parameters through a femtosecond laser light source system, and the Bessel beam is focused to at least one position of a through hole to be processed on a sapphire substrate according to a preset laser scanning path, and the through hole processing is performed on the at least one position.

2. The method according to claim 1, characterized in that The processing method for performing through-hole processing on the at least one position is any one of the following: single-pulse processing, multi-pulse tapping processing, circular cutting processing and spiral processing.

3. The method according to claim 2, characterized in that When the processing method is single-pulse processing, the laser process parameters of the Bessel beam emitted by the femtosecond laser light source system are set to: the wavelength of the output Bessel beam is 1030nm, the pulse width is 1-6ps, the single pulse energy range is 10-48μJ / pulse, and the maximum repetition frequency is 200kHz.

4. The method according to claim 3, characterized in that The pulse width of the Bessel beam output by the femtosecond laser light source system is 6ps, and the energy of a single pulse is greater than 21μJ / pulse and less than or equal to 48μJ / pulse.

5. The method according to claim 1, characterized in that The femtosecond laser light source system comprises a femtosecond laser, a half-wave plate, a polarizer, a shutter, an aperture, an aconic lens, a plano-convex lens, a dichroic mirror and a microscope objective lens which are sequentially arranged along the optical path; The process of emitting the Bessel beam by a femtosecond laser light source system includes: The flux of the laser beam emitted by the femtosecond laser is adjusted by using the combination of the half-wave plate and the polarizing plate, and the on-off of the laser beam is controlled by the shutter to control whether the laser beam is used for processing; When the laser beam is controlled to be used for processing, the diameter of the incident laser beam is controlled by the aperture, and then the laser beam is transformed into a Bessel beam by the conical lens. Then, the transformed Bessel beam is reduced to a preset size through the plano-convex lens, the dichroic mirror and the microscope objective lens to obtain a micro Bessel beam, and is focused onto the surface of the sapphire substrate so as to perform through-hole processing on the sapphire substrate using the micro Bessel beam.

6. The method according to any one of claims 1 to 5, characterized in that: During the through-hole processing, compressed gas is also introduced as processing auxiliary gas, and the compressed gas is compressed air or compressed inert gas.

7. The method according to claim 6, characterized in that The gas pressure of the compressed gas is 1.3-3Mpa.

8. The method according to any one of claims 1 to 5, characterized in that: The method of cleaning and drying the sapphire substrate comprises: The sapphire substrate is immersed in an acetone solution and ultrasonically cleaned for a preset time; The sapphire substrate is taken out of the acetone solution and immersed in an isopropanol solution and ultrasonically cleaned for a preset time; The sapphire substrate is taken out from the isopropanol solution, immersed in deionized water and subjected to ultrasonic cleaning for a preset time; The cleaned sapphire substrate is dried using nitrogen gas.

9. A method for manufacturing a superconducting quantum chip, characterized in that: The superconducting quantum chip manufacturing method comprises the steps of machining a through hole for at least one position on a sapphire substrate; The step of machining a through hole at at least one position on the sapphire substrate is achieved by the method for manufacturing a through hole in a sapphire substrate as described in any one of claims 1-8.

10. A superconducting quantum chip, characterized in that: The superconducting quantum chip is made of a sapphire substrate, and a through hole is opened on the sapphire substrate. The through hole is manufactured by the sapphire substrate through hole manufacturing method according to any one of claims 1 to 8.

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