Preparation method of laser-induced period-adjustable oxidation periodic structure

Abstract

The embodiment of the invention relates to the technical field of semiconductor material preparation, in particular to a preparation method of a laser-induced period-adjustable oxidation periodic structure, which comprises the following steps: sequentially preparing a substrate, a metal layer and a semiconductor layer from bottom to top by using a physical deposition method to form a substrate-metal layer-semiconductor layer bottom-to-top structural film; a femtosecond laser is used for emitting pulse laser, the pulse laser sequentially passes through a half-wave plate, a polarization beam splitter prism and a cylindrical lens and then is focused on the surface of the structural film, and an oxidized periodic structure is formed; by changing the thickness of the semiconductor layer, the period of the formed oxidation periodic structure is regulated and controlled, and the period of the oxidation periodic structure is reduced along with the increase of the thickness of the semiconductor layer. According to the method, the period of the oxidation periodic structure can be flexibly regulated and controlled under the condition of not depending on laser wavelength and incident angle modulation, the processing efficiency is very high, and the method can be well suitable for large-area production.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of semiconductor material preparation, and in particular to a method for preparing a laser-induced periodically adjustable oxidation periodic structure. Background Art

[0002] In the technical fields of materials science, optical devices, microelectronics and biomedicine, surface processing technology of micro-nanoscale periodic structures has a wide range of applications. Surface micro-nanostructures can not only greatly change the physical, chemical, optical and biological properties of materials, but also improve their functional performance in high-tech fields such as sensors, optical components and electronic devices. In these technical fields, efficient, economical and controllable surface structure manufacturing is crucial.

[0003] Laser-Induced Periodic Surface Structures (LIPSS) is a technology that uses laser to form periodic micro-nano structures (oxidation periodic structures) on the surface of materials. LIPSS has the advantages of low cost, high efficiency and high flexibility, and can significantly improve the optical absorption rate, surface hydrophilicity and other properties of materials. Compared with traditional micro-nano manufacturing methods (such as photolithography, electron beam lithography, nanoimprinting and focused ion beam), LIPSS not only gets rid of the dependence on complex and expensive equipment and high-cost materials, but also can greatly improve processing efficiency. Therefore, it has received more and more attention in surface micro-nano manufacturing.

[0004] However, LIPSS still has some limitations. For example, LIPSS usually relies on adjusting the period of the surface structure by modulating spatial light parameters such as the wavelength and incident angle of the laser. The laser wavelength is usually fixed or the adjustment range is relatively narrow, and the period formed by adjusting the incident angle is not easy to stably control. Therefore, LIPSS lacks flexibility in period regulation. In addition, when preparing LIPSS, the laser is usually applied directly to a single layer of material, which can easily cause bending and bifurcation of the surface microstructure, making it difficult to ensure the uniformity and collimation of the processed structure. At the same time, because traditional laser processing uses point spot technology and the spot size is small, the processing efficiency is low, and it is difficult to meet the needs of large-area processing. Summary of the invention

[0005] In view of this, the embodiments of the present application propose a method for preparing a laser-induced periodically adjustable oxidized periodic structure, which can achieve flexible regulation of the period of the oxidized periodic structure without relying on laser wavelength and incident angle modulation, and has high processing efficiency and can adapt to large-scale production.

[0006] In the first aspect, an embodiment of the present application proposes a method for preparing a laser-induced periodically adjustable oxidized periodic structure, the method comprising the following steps: using a physical deposition method to sequentially prepare a substrate, a metal layer and a semiconductor layer from bottom to top to form a substrate-metal layer-semiconductor layer structural film from bottom to top; using a femtosecond laser to emit a pulsed laser, which passes through a half-wave plate, a polarization beam splitter prism and a cylindrical lens in sequence, and is focused on the surface of the structural film to form an oxidized periodic structure; wherein the energy of the pulsed laser is increased by rotating the half-wave plate; and by changing the thickness of the semiconductor layer, the period of the formed oxidized periodic structure is regulated, and the period of the oxidized periodic structure decreases with the increase of the thickness of the semiconductor layer.

[0007] Optionally, the metal material selected for the metal layer is a metal material with balanced reflectivity over the entire visible light band.

[0008] Optionally, the thickness of the metal layer is greater than 50 mm.

[0009] Optionally, the semiconductor material selected for the semiconductor layer is a high absorption semiconductor material.

[0010] Optionally, the semiconductor layer has a thickness of 10 nm to 150 nm.

[0011] Optionally, the pulse laser emitted by a femtosecond laser is linearly polarized light, with a pulse width of 750fs to 10ps, a repetition frequency of 5KHz to 200KHz, a wavelength of 1030nm, and a focal length of the cylindrical lens of 20mm.

[0012] Optionally, during the processing, the laser energy of the pulsed laser is gradually increased by rotating the half-wave plate until it reaches a preset oxidation threshold, thereby forming an oxidized periodic structure.

[0013] Optionally, a femtosecond laser is used to emit pulsed laser, which passes through a half-wave plate, a polarization beam splitter prism and a cylindrical lens in sequence and then is vertically focused on the surface of the structural film to form an oxidized periodic structure perpendicular to the laser polarization.

[0014] Through the above-mentioned method, the present application prepares an oxidized periodic structure with adjustable period by laser induction. The main part of the oxidized periodic structure is a double-layer membrane structure, including a metal layer and a semiconductor layer. The double-layer membrane structure and the bottom substrate together form a substrate-metal layer-semiconductor layer bottom-up structural film, which effectively ensures the high uniformity and regularity of the processed structure. When the pulsed laser emitted by the femtosecond laser acts on the processed structural film, the metal layer will excite a large number of hot electrons, promote the absorption of light by the upper semiconductor layer, thereby reducing the formation threshold of the oxidized periodic structure. By changing the thickness of the semiconductor layer, the period of the oxidized periodic structure can be effectively regulated without complex and cumbersome spatial light modulation, and has a high period tuning sensitivity. In addition, the use of a cylindrical lens to focus the laser to form a line spot greatly improves the processing efficiency, is very suitable for large-area processing scenarios, and has a high commercial application value.

[0015] In a second aspect, an embodiment of the present application proposes a computer-readable storage medium storing a computer program, which, when executed by a processor, can implement a method for preparing a laser-induced periodically adjustable oxidative periodic structure as described in the first aspect above.

[0016] It can be understood that the beneficial effects of the second aspect mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the related technologies, the drawings required for use in the embodiments of the present application or the related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a flow chart of a method for preparing a laser-induced periodically adjustable oxidation periodic structure provided in one embodiment of the present application;

[0019] Figure 2 It is a schematic structural diagram of a bottom-up structure film of a substrate-metal layer-semiconductor layer provided in one embodiment of the present application;

[0020] Figure 3 It is a schematic diagram of using a femtosecond laser to emit pulsed laser, which passes through a half-wave plate, a polarization beam splitter prism and a cylindrical lens in sequence and then is focused on the surface of a structural film to form an oxidized periodic structure, provided in an embodiment of the present application;

[0021] Figure 4This is a schematic diagram of an oxidized periodic structure formed by using 100nm copper for the metal layer and 30nm, 50nm, and 60nm silicon for the semiconductor layer under an optical microscope, provided in one embodiment of the present application;

[0022] Figure 5 A scanning electron microscope image of an oxidized periodic structure formed by using 100nm copper for the metal layer and 30nm silicon for the semiconductor layer is provided in one embodiment of the present application;

[0023] Figure 6 is a graph showing a corresponding relationship between the thickness of a semiconductor layer and the period of an oxidized periodic structure formed, provided in one embodiment of the present application;

[0024] Figure 7 An embodiment of the present application provides a corresponding relationship diagram between the period of the oxidation periodic structure and the laser repetition frequency and the laser pulse width. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the embodiments of the present application will be described in detail below in conjunction with the accompanying drawings. In the various embodiments of the present application, many technical details are proposed in order to make the reader better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical scheme claimed in the present application can also be implemented. The division of the following embodiments is only for the convenience of description, and the specific implementation mode of the present application should not constitute any limitation. The various embodiments can be combined with each other and referenced to each other under the premise of no contradiction.

[0026] Although LIPSS has gotten rid of the reliance on complex and expensive equipment and high-cost materials, and can also improve processing efficiency, it still has certain limitations. For example, LIPSS usually relies on modulating spatial light parameters such as the wavelength and incident angle of the laser to adjust the period of the surface structure. The laser wavelength is usually fixed or the adjustment range is relatively narrow, and the period formed by adjusting the incident angle is not easy to stably control. Therefore, LIPSS lacks flexibility in period regulation. In addition, when preparing LIPSS, it is usually necessary to directly apply the laser to a single layer of material, which can easily cause bending and bifurcation of the surface microstructure, making it difficult to ensure the uniformity and collimation of the processed structure. At the same time, because traditional laser processing uses point spot technology and the spot size is small, the processing efficiency is low, and it is difficult to meet the needs of large-area processing.

[0027] The periodic regulation methods proposed for LIPSS have a limited regulation range and a relatively low regulation sensitivity. For example, Oktem et al. directly used a 1030nm femtosecond laser to generate LIPSS on a titanium film. When the thickness of the titanium film increased from 50nm to 500nm and the period increased from 625nm to 850nm, the corresponding regulation sensitivity was only 0.5nm·nm. -1 The period of LIPSS formed by Dostovalov et al. on amorphous silicon using a 1030nm femtosecond laser is not continuously adjustable. When the silicon film is less than 100nm, the period is 700nm. When the thickness of the silicon film increases to 200nm, the period suddenly jumps to 950nm. Subsequently, the period does not change when the thickness of the silicon film is increased.

[0028] In order to solve the above technical problems, an embodiment of the present application proposes a method for preparing a laser-induced periodically adjustable oxidative periodic structure. The implementation details of the method for preparing a laser-induced periodically adjustable oxidative periodic structure proposed in this embodiment are described in detail below. The following content is only the implementation details provided for the convenience of understanding and is not necessary for the implementation of this solution.

[0029] The specific process of the method for preparing a laser-induced periodically adjustable oxidation periodic structure proposed in this embodiment can be as follows: Figure 1 As shown, including:

[0030] S1, using a physical deposition method to sequentially prepare a substrate, a metal layer and a semiconductor layer from bottom to top, to form a substrate-metal layer-semiconductor layer structure film from bottom to top.

[0031] In a specific implementation, the first step in preparing an oxidized periodic structure is to prepare its basic structure. This step requires using a physical deposition method to sequentially prepare a substrate, a metal layer, and a semiconductor layer from bottom to top, thereby forming a Figure 2 The substrate-metal layer-semiconductor layer structure film from bottom to top is shown.

[0032] In one example, the substrate may be a silicon substrate.

[0033] In one example, the metal material selected for the metal layer is a metal material with balanced reflectivity over the entire visible light band, such as copper deposited on a silicon substrate to form a metal layer, and the thickness of the metal layer is greater than 50 mm.

[0034] In one example, the semiconductor material selected for the semiconductor layer is a high absorption semiconductor material, such as depositing amorphous silicon on the surface of the metal layer to form a semiconductor layer, and the thickness of the semiconductor layer is 10 nm to 150 nm.

[0035] In one example, when preparing the base structure, a magnetron sputtering coating device can be used to deposit 100nm of copper on a silicon substrate to form a metal layer, and then amorphous silicon of different thicknesses is deposited on the metal layer by controlling the sputtering time to form a semiconductor layer with a thickness of 10nm to 70nm, ultimately forming a bottom-up structural film of substrate-metal layer-semiconductor layer.

[0036] S2 uses a femtosecond laser to emit pulsed laser, which passes through a half-wave plate, a polarization beam splitter prism and a cylindrical lens in sequence, and then focuses on the surface of the structural film to form an oxidized periodic structure.

[0037] In the specific implementation, after the preparation of the basic structure (structural film) is completed, the oxidized periodic structure can be prepared on the basis of the structural film by laser induction. This step requires the use of a femtosecond laser to emit pulsed laser, which passes through a half-wave plate, a polarization beam splitter prism and a cylindrical lens in sequence, and then focuses on the surface of the structural film to form an oxidized periodic structure. In the process, the energy of the pulsed laser is increased by rotating the half-wave plate.

[0038] In one example, a femtosecond laser is used to emit pulsed laser light, which passes through a half-wave plate, a polarization beam splitter prism, and a cylindrical lens in sequence and is focused on the surface of a structured film. The process of forming an oxidized periodic structure can be described as follows: Figure 3 As shown. The femtosecond laser is used to emit femtosecond laser (pulse laser), the half-wave plate and polarization beam splitter prism are used to continuously change the energy of the laser to obtain pulse laser of required energy, and finally the laser is focused on the surface of the structural film after the action of the cylindrical lens to form an oxidized periodic structure.

[0039] In one example, the pulsed laser emitted by the femtosecond laser is linearly polarized light, with a pulse width of 750fs to 10ps, a repetition frequency of 5KHz to 200KHz, a wavelength of 1030nm, and a focal length of the cylindrical lens of 20mm. During the processing, the laser energy of the pulsed laser can be gradually increased by rotating the half-wave plate until the preset oxidation threshold, thereby forming an oxidized periodic structure. The oxidation threshold can be set by a technician in this field according to actual needs.

[0040] In one example, a femtosecond laser is used to emit pulsed laser light, which passes through a half-wave plate, a polarization beam splitter prism, and a cylindrical lens in sequence and is then vertically focused on the surface of the structured film to form an oxidized periodic structure perpendicular to the laser polarization.

[0041] S3, by changing the thickness of the semiconductor layer, the period of the formed oxidized periodic structure is regulated, and the period of the oxidized periodic structure decreases as the thickness of the semiconductor layer increases.

[0042] In a specific implementation, the period of the formed oxidized periodic structure can be regulated by changing the thickness of the semiconductor layer, and the period of the oxidized periodic structure decreases as the thickness of the semiconductor layer increases. The entire regulation process does not require complex and cumbersome spatial light modulation, and has a high period tuning sensitivity.

[0043] In an example, Figure 4 As shown in the figure, the prepared oxidized periodic structure can be observed through an optical microscope. Three silicon films (semiconductor layers) of different thicknesses form oxidized periodic structures of different periods. Silicon films of 30nm, 50nm, and 60nm thickness correspond to periods of 965nm, 858nm, and 793nm, respectively. As the thickness of the silicon film increases, the period of the oxidized periodic structure decreases significantly. It can also be seen that the change in period is accompanied by a corresponding change in surface color. This color change is due to the oxidation process changing the thickness of the silicon film. The metal layer-semiconductor layer structure acts as a broadband optical reflector. Their reflection spectrum changes with the thickness of the silicon film. The oxide layer can affect the reflection spectrum and thus the perceived structural color.

[0044] In an example, Figure 5 As shown, the oxidized periodic structure of the silicon film with a thickness of 30 nm can be observed using a scanning electron microscope. The oxidized periodic structure is very uniform and has a high degree of regularity.

[0045] Figure 6 The periodic changes of the oxidized periodic structure formed by changing the thickness of the semiconductor layer are shown. Figure 6 It can be seen that the period of the oxidized periodic structure gradually decreases with the increase of silicon film thickness. As the silicon film thickness increases from 15nm to 70nm, the period decreases from 1005nm to 764nm, and the corresponding period tuning sensitivity is 4.4nm·nm -1 . Large-scale, high-sensitivity periodic regulation on semiconductor materials has been successfully achieved.

[0046] Figure 7 The corresponding relationship between the period of the oxidation periodic structure and the laser repetition frequency and laser pulse width is shown. Figure 7 It can be seen that the period of the oxidized periodic structure is only slightly affected by the laser repetition frequency and the laser pulse width.

[0047] In this embodiment, a periodically adjustable oxidation periodic structure is prepared by laser induction. The main part of the oxidation periodic structure is a double-layer membrane structure, including a metal layer and a semiconductor layer. The double-layer membrane structure and the bottom substrate together form a bottom-up structural film of substrate-metal layer-semiconductor layer. The structural film effectively ensures the high uniformity and regularity of the processed structure. When the pulsed laser emitted by the femtosecond laser acts on the processed structural film, the metal layer will excite a large number of hot electrons, promote the absorption of light by the upper semiconductor layer, and thus reduce the formation threshold of the oxidation periodic structure. By changing the thickness of the semiconductor layer, the period of the oxidation periodic structure can be effectively regulated without complex and cumbersome spatial light modulation, and has a high period tuning sensitivity. In addition, the use of a cylindrical lens to focus the laser to form a line spot greatly improves the processing efficiency, is very suitable for large-area processing scenarios, and has a high commercial application value.

[0048] The step division of the above methods is only for clear description. When implemented, they can be combined into one step or some steps can be split and decomposed into multiple steps. As long as they include the same logical relationship, they are all within the scope of protection of this application; adding insignificant modifications to the algorithm or process or introducing insignificant designs without changing the core design of the algorithm and process are all within the scope of protection of this application.

[0049] Correspondingly, another embodiment of the present application proposes a laser-induced periodically adjustable oxidation periodic structure preparation system. The implementation details of the laser-induced periodically adjustable oxidation periodic structure preparation system proposed in this embodiment are specifically described below. The following content is only the implementation details provided for the convenience of understanding and is not necessary for the implementation of this example.

[0050] The preparation system is mainly composed of a magnetron sputtering coating device, a femtosecond laser, a half-wave plate, a polarization beam splitter prism and a cylindrical lens. During the preparation process, the magnetron sputtering coating device is used to prepare a substrate, a metal layer and a semiconductor layer in sequence from bottom to top by a physical deposition method to form a substrate-metal layer-semiconductor layer bottom-up structural film. A femtosecond laser is used to emit pulsed laser, which passes through the half-wave plate, the polarization beam splitter prism and the cylindrical lens in sequence. By rotating the half-wave plate and adjusting the polarization beam splitter prism, the laser energy of the pulsed laser can be gradually increased until a preset oxidation threshold value, and finally the pulsed laser is focused on the surface of the structural film to form an oxidized periodic structure, thereby completing the preparation of the oxidized periodic structure.

[0051] If the period of the oxidized periodic structure needs to be regulated, the thickness of the semiconductor layer needs to be changed. The period of the oxidized periodic structure decreases as the thickness of the semiconductor layer increases.

[0052] It is worth mentioning that all modules involved in this embodiment are logic modules. In practical applications, a logic unit can be a physical unit, a part of a physical unit, or a combination of multiple physical units. In addition, in order to highlight the innovative part of this application, this embodiment does not introduce units that are not closely related to solving the technical problems proposed by this application, but this does not mean that there are no other units in this embodiment.

[0053] It is not difficult to find that this embodiment is a system embodiment corresponding to the above method embodiment, and this embodiment can be implemented in conjunction with the above method embodiment. The relevant technical details and technical effects mentioned in the above embodiments are still valid in this embodiment, and in order to reduce repetition, they are not repeated here. Accordingly, the relevant technical details mentioned in this embodiment can also be applied in the above embodiments.

[0054] Another embodiment of the present application provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it can implement a method for preparing a laser-induced periodically adjustable oxidative periodic structure as described in the above method embodiments.

[0055] That is, those skilled in the art can understand that all or part of the steps in the above method embodiments can be completed by instructing the relevant hardware through a program, and the program is stored in a storage medium, including a number of instructions for a device (such as a single-chip microcomputer, chip, etc.) or a processor to execute all or part of the steps described in the various method embodiments of the present application. The aforementioned storage medium includes, but is not limited to: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, and other media that can store program codes.

[0056] Those skilled in the art will appreciate that the above embodiments are specific embodiments for implementing the present application, and in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present application.

Claims

1. A method for preparing a laser-induced periodically adjustable oxidation periodic structure, characterized in that: include: A substrate, a metal layer and a semiconductor layer are sequentially prepared from bottom to top using a physical deposition method to form a bottom-up structural film of substrate-metal layer-semiconductor layer; A femtosecond laser is used to emit pulsed laser, which passes through a half-wave plate, a polarization beam splitter prism and a cylindrical lens in sequence and is focused on the surface of the structured film to form an oxidized periodic structure. The energy of the pulsed laser is increased by rotating the half-wave plate. By changing the thickness of the semiconductor layer, the period of the formed oxidized periodic structure can be regulated, and the period of the oxidized periodic structure decreases as the thickness of the semiconductor layer increases.

2. The method for preparing a laser-induced periodically adjustable oxidation periodic structure according to claim 1, characterized in that: The metal material selected for the metal layer is a metal material with balanced reflectivity over the entire visible light band.

3. The method for preparing a laser-induced periodically adjustable oxidation periodic structure according to claim 2, characterized in that: The thickness of the metal layer is greater than 50 mm.

4. The method for preparing a laser-induced periodically adjustable oxidation periodic structure according to claim 1, characterized in that: The semiconductor material selected for the semiconductor layer is a highly absorbing semiconductor material.

5. The method for preparing a laser-induced periodically adjustable oxidation periodic structure according to claim 4, characterized in that: The thickness of the semiconductor layer is 10 nm to 150 nm.

6. The method for preparing a laser-induced periodically adjustable oxidation periodic structure according to claim 1, characterized in that: The pulsed laser emitted by the femtosecond laser is linearly polarized light, with a pulse width of 750fs to 10ps, a repetition frequency of 5KHz to 200KHz, a wavelength of 1030nm, and a focal length of the cylindrical lens of 20mm.

7. The method for preparing a laser-induced periodically adjustable oxidation periodic structure according to claim 6, characterized in that: During the processing, the laser energy of the pulsed laser is gradually increased by rotating the half-wave plate until it reaches a preset oxidation threshold, thereby forming an oxidized periodic structure.

8. The method for preparing a laser-induced periodically adjustable oxidation periodic structure according to claim 7, characterized in that: A femtosecond laser is used to emit pulsed laser, which passes through a half-wave plate, a polarization beam splitter prism and a cylindrical lens in sequence, and then is focused vertically on the surface of the structural film to form an oxidized periodic structure perpendicular to the laser polarization.

9. A method for preparing a laser-induced periodically adjustable oxidation periodic structure according to any one of claims 1 to 8, characterized in that: The substrate, metal layer and semiconductor layer are prepared sequentially from bottom to top using a physical deposition method to form a substrate-metal layer-semiconductor layer bottom-up structure film, including: Using a magnetron sputtering coating device, 100nm of copper is deposited on a silicon substrate to form a metal layer. Then, amorphous silicon of different thicknesses is deposited on the metal layer by controlling the sputtering time to form a semiconductor layer with a thickness of 10nm to 70nm, ultimately forming a bottom-up structural film of substrate-metal layer-semiconductor layer.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, it can implement a method for preparing a laser-induced periodically adjustable oxidized periodic structure as claimed in any one of claims 1 to 9.

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