Method for manufacturing micro-nano structure of optical element surface

Abstract

The present application relates to a kind of micro-nano structure manufacturing method, by the improvement of traditional reactive ion beam etching technology, first using colloidal ball self-assembly technology to prepare nanosphere array of periodic structure on the surface of element, then etching colloidal ball using wide-beam ion source, and control process conditions such as working gas pressure, temperature, time, etching power, adjust the duty cycle between colloidal ball.Then using the low-temperature deposition method of film, thin film mask is plated into the gap between colloidal ball, then colloidal ball is removed using matching solution.Finally, using wide-beam ion source etching element, the pattern of thin film mask is transferred to element, and finally micro-nano structure element is obtained.The present application can provide sample for the experimental research or industrial production of high-power laser window.

Description

Technical Field

[0001] This invention belongs to the field of ion beam etching. In particular, it relates to a new process for the preparation of large-diameter thin film masks and ion beam etching. Background Technology

[0002] Research on high-power, large-aperture lasers has been a crucial focus in the field of high-power lasers since the 1970s, reflecting significant national needs. Due to the high energy density of the laser beam in high-power laser systems, the laser anti-reflection window often suffers surface damage under intense laser irradiation. Damage to laser components under intense laser irradiation severely impacts their lifespan and is a major factor hindering the long-term safe and stable operation of high-power laser systems. Addressing the challenges of improving the damage threshold of traditional dielectric film transmission elements and the limitations of conventional reactive ion etching (RIE) techniques for fabricating large-aperture optical elements, this paper proposes an improvement to traditional RIE techniques. First, a large-aperture periodic nanosphere array is fabricated on the element surface using colloidal sphere self-assembly technology. Then, a wide-beam ion source is used to etch the colloidal spheres, controlling process conditions such as working gas pressure, temperature, time, and etching power to adjust the duty cycle between the colloidal spheres. Next, a thin-film mask is deposited between the colloidal spheres using a low-temperature thin-film deposition method, followed by the removal of the colloidal spheres using a specific solution. Finally, a wide-beam ion source is used to etch the element, transferring the pattern of the thin-film mask onto the element, ultimately yielding a micro / nanostructured element. The spectral results of the tested element agree well with the simulation calculations, and the high damage threshold proves the feasibility of the method. This method is easily scaled up and can provide theoretical support and technical guidance for the fabrication of meter-scale micro / nano structures. Summary of the Invention

[0003] The purpose of this invention is to provide a method for fabricating large-aperture micro / nano structures. This method employs a wide-beam ion source etching technique and a low-temperature environment for thin film mask deposition, resulting in micro / nano structures with excellent performance.

[0004] This invention first utilizes colloidal sphere self-assembly technology to fabricate a large-aperture periodic nanosphere array on the surface of a device. Next, a wide-beam ion source is used to etch the colloidal spheres, and process conditions such as working gas pressure, temperature, time, and etching power are controlled to adjust the duty cycle between the colloidal spheres. Then, a thin-film mask is deposited between the colloidal spheres using a low-temperature thin-film deposition method, followed by the removal of the colloidal spheres using a specific solution. Finally, the device is etched using a wide-beam ion source to transfer the pattern of the thin-film mask onto the device, ultimately obtaining a micro / nanostructured device.

[0005] The source used to generate the ion beam can be an anode-layer linear ion source, a radio frequency ion source, a Hall ion source, or a Kaufman ion source.

[0006] Deposition equipment used to prepare thin film masks can be sputtering deposition equipment, thermal evaporation deposition equipment, etc.

[0007] The temperature used for depositing the thin film mask is room temperature - 100°C.

[0008] The gas used for ion beam etching can be O2, Ar, Kr, etc.

[0009] Thin films used as masks can be made of materials such as Ti, Cr, and Al2O3.

[0010] This invention first utilizes colloidal sphere self-assembly technology to fabricate a large-aperture periodic nanosphere array on the surface of a device. Next, a wide-beam ion source is used to etch the colloidal spheres, and process conditions such as working gas pressure, temperature, time, and etching power are controlled to adjust the duty cycle between the colloidal spheres. Then, a thin-film mask is deposited between the colloidal spheres using a low-temperature thin-film deposition method, followed by the removal of the colloidal spheres using a specific solution. Finally, the device is etched using a wide-beam ion source to transfer the pattern of the thin-film mask onto the device, ultimately obtaining a micro / nanostructured device. This invention can provide samples for experimental research or industrial production of large-aperture high-power laser windows.

[0011] Advantages of this invention:

[0012] 1) Compared with traditional reactive ion beam etching technology, this technology can realize the fabrication of large-aperture micro and nano structures.

[0013] 2) The thin film mask prepared in this technology has strong etching resistance and high selectivity of etching gas for the thin film mask and substrate.

[0014] 3) The etching device in this technology is inexpensive and easy to promote on a large scale. Attached Figure Description

[0015] Figure 1 Flowchart of a novel ion beam etching method;

[0016] Figure 2 The antireflective structural morphology of a quartz substrate;

[0017] Figure 3 Transmittance spectrum of the antireflective structure on a quartz substrate. Detailed Implementation

[0018] To better illustrate the present invention, a detailed description will be provided below in conjunction with the accompanying drawings.

[0019] like Figure 1The diagram illustrates a novel large-aperture micro / nano structure manufacturing method of this invention. First, a large-aperture periodic nanosphere array is fabricated on the surface of a device using colloidal sphere self-assembly technology. Next, the colloidal spheres are etched using a wide-beam ion source, with process conditions such as working gas pressure, temperature, time, and etching power controlled to adjust the duty cycle between the colloidal spheres. Then, a thin-film mask is deposited between the colloidal spheres using a low-temperature thin-film deposition method, followed by the removal of the colloidal spheres using a specific solution. Finally, the device is etched using a wide-beam ion source to transfer the pattern of the thin-film mask onto the device, ultimately obtaining the micro / nano structure device.

[0020] The ion source power beam current in the etching process is adjustable from 0 to 1700 mA; the substrate bias voltage is 0 to 1400 V; the argon flow rate is 0 to 50 sccm; and the oxygen flow rate is 0 to 100 sccm.

[0021] In the mask fabrication process: background vacuum level: 5×10 -3 Pa to 5×10 -4 Between Pa; working air pressure: adjustable from 0.1 to 1 Pa; evaporation current: 0 to 1000 mA.

[0022] Example 1:

[0023] The size is A circular quartz substrate was ultrasonically cleaned in water for 5 minutes. After cleaning, it was placed in a large vessel, and styrene colloidal spheres with a particle size of 600 nm were used to self-assemble in an aqueous solution, forming a monolayer of colloidal spheres on the substrate surface. After completion, the substrate was placed in the vacuum chamber of the equipment and evacuated to a vacuum level of <10⁻⁶. 2 Pa, after the temperature stabilizes at 50℃, continue evacuating the vacuum to 9.5×10 Pa. -4 Oxygen was introduced at Pa, and the argon inlet flow rate was controlled by a mass flow meter and stabilized at 60 sccm. The ion source and rotating disk were turned on, with the ion source beam current and beam voltage set to 500 mA and 500 V, respectively, and the rotation speed stabilized at 40 r / min. The small spheres were etched, with a material removal uniformity of 5‰ for the wide-beam ion source and an etching time of 1800 s. The size of the colloidal spheres after etching was 50% of the original particle size. After the process was completed, the electron gun current was set to 800 mA, the deposition temperature was room temperature, and a metallic Ti film was deposited. The mask thickness was 30% of the etched colloidal sphere particle size. After the film was deposited, the substrate was removed and ultrasonically cleaned at a frequency of 40 kHz for 3 min to remove the colloidal spheres. The substrate was then dried using an ion air gun. Finally, it was placed in an etching machine, and the vacuum was evacuated to 1.5 × 10⁻⁶. -3The workpiece was filled with oxygen at 60 sccm using a mass flow meter, and the argon inlet flow rate was stabilized at 60 sccm. The ion source and orbital disk were turned on, and the ion source beam current and beam voltage were set to 900 mA and 900 V, respectively. Etching began and lasted for 23 minutes. After etching was completed, the workpiece was removed for micro / nano structure and optical property testing and characterization. The test results are as follows: Figure 2 , 3 As shown in the figure, a micro / nanostructure with pores was finally obtained on the surface of the quartz substrate. The micro / nanostructure has a period of 600 nm, a pore duty cycle of 50.5%, a pore thickness of 270 nm, and a single-sided transmittance of 95.8%, indicating a very ideal structure. The morphology and transmittance of the prepared microstructure substrate were measured using an ORION NANOFAB scanning helium ion microscope manufactured by Zeiss and a Lambda 950 UV-Vis-NIR spectrophotometer manufactured by PE.

Claims

1. A method for manufacturing micro / nano structures on the surface of an optical element, characterized in that, Includes the following steps: (1) Substrate cleaning: Place the substrate in water and clean it with ultrasonic waves for 1-40 minutes; (2) Colloidal sphere self-assembly: Prepare a colloidal sphere solution with a particle size of 10 nanometers to 100 micrometers, and perform colloidal sphere self-assembly on the substrate to form a single layer of colloidal spheres on the substrate surface; (3) Etching of colloidal spheres: The substrate after the colloidal spheres are self-assembled is taken out and dried. According to the characteristic size of the micro-nano structure, the colloidal spheres are etched by ion beam, and the size of the colloidal spheres is adjusted to 10-90% of the particle size before etching. (4) Coating the mask plate: Coating a thin film mask between the gaps of the colloidal spheres; (5) Removal of colloidal balls: The colloidal balls are washed away by ultrasonic cleaning and then dried; (6) Structure etching: The structure is transferred to the substrate by etching the substrate surface with a mask using an ion beam, and the target micro / nano structure is finally obtained. The ion source used for etching the substrate is a wide-beam ion source; The material removal uniformity of the wide-beam ion source is better than 5‰; The etching gas is one or more of O2, Ar, and Kr gases; The ion beam parameters for step (3) are: beam current of 10-500 mA and beam voltage of 10-500 V; the ion beam parameters for step (6) are: beam current of 350-5000 mA and beam voltage of 350-5000 V. The substrate material is one or more of the following: quartz, silicon, sapphire, microcrystalline glass, metallic conductor, or semiconductor material; The colloidal spheres are made of one or more of the following materials: polystyrene, SiO2, and Al2O3. The thin film mask is made of one or more of the following materials: Ti, Cr, and Al2O3. The thickness of the mask is 5-60% of the particle size of the colloidal spheres after etching. The deposition temperature of the thin film mask is room temperature - 100℃; The surface area of ​​the substrate is 100 mm. 2 -50 m 2 ; The shape of the base is one or a combination of two or more of the following: circular, square, and irregular shapes.

2. The method according to claim 1, characterized in that: In step (2), the colloidal spheres self-assemble: prepare a colloidal sphere solution with a particle size of 50 nanometers to 10 micrometers; In step (3), the colloidal spheres are etched: the size of the colloidal spheres is adjusted to 30-60% of the particle size before etching; The ion beam parameters in step (3) are: beam current of 50-300 mA and beam voltage of 50-300 V. The ion beam parameters in step (6) are: beam current of 600-3000 mA and beam voltage of 600-3000 V; The thickness of the mask is 20-50% of the particle size of the colloidal spheres after etching.

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