Apparatus and method for electric field assisted laser induced plasma processing of transparent hard and brittle materials

Abstract

The application belongs to the technical field of microfabrication, and particularly discloses a device and method for electric field assisted laser-induced plasma processing of transparent hard and brittle materials, wherein the device comprises a computer, a laser processing system, and a longitudinal electric field generating device; the laser processing system comprises a laser, a beam expander, a mirror, and a scanning galvanometer; the longitudinal electric field generating device comprises electrode sheets and a direct current stabilized power supply; the computer is connected with the laser in the laser processing system; and the longitudinal electric field generating device is connected with a transparent conductive film on a surface to be processed of the transparent hard and brittle material and metal target materials below the material through the electrode sheets to form a longitudinal electric field. The application improves the electric field application mode, shortens the distance between the two electrode plates, and makes the electrode distance reach the micron level, so that a larger electric field force can be generated at a lower voltage; the transparent conductive film is used as the electrode, so that the incident laser can pass through the electrode for processing without being blocked, and the processing device is more simple and the processing mode is more flexible.

Description

Technical Field

[0001] The present invention belongs to the technical field of micro-machining, and in particular relates to a device and method for processing transparent hard and brittle materials using electric field-assisted laser-induced plasma. Background Art

[0002] Transparent hard and brittle materials, with their high light transmittance, high heat resistance, and good corrosion resistance, are widely used in aerospace, microelectronics, and optical components. However, due to their high hardness and low toughness, transparent hard and brittle materials are prone to brittle fracture during processing, making their microstructural processing a technical challenge.

[0003] To address the difficulties in micromachining transparent, hard, and brittle materials, some researchers have proposed laser-induced plasma-assisted ablation (LIPA). This technique focuses a high-energy laser beam onto a metal target beneath the transparent, hard, and brittle material, generating a high-temperature, high-pressure plasma. The plasma then expands upward and strikes the back of the transparent, hard, and brittle material above the target, etching the material. LIP etching offers advantages such as lower cost, lower energy consumption, less surface buildup, and reduced thermal stress, making it a novel and advantageous method for micromachining transparent, hard, and brittle materials. However, existing LIP etching techniques still suffer from the problem of uncontrollable plasma. To address this, many researchers have utilized electromagnetic fields to control the plasma. Chinese patent CN 102064213A discloses a transmissive laser-electromagnetic field coupled thruster. This patent accelerates the plasma through an electric field and applies a Lorentz force to the plasma through a magnetic field, thereby achieving a higher ionization rate and ejection rate, thereby generating a thrust pulse. However, because the electrode sheet is made of a non-transparent material, holes or grooves must be drilled to allow the laser to enter through the holes or grooves, increasing the complexity of the device. Chinese patent CN 107234342 B discloses a laser-induced plasma direct writing deposition method and device. The patent implements the screening of plasma through a filter, electric / magnetic field, etc., and realizes the focused injection of plasma through a high-temperature conical nozzle. Combined with the relative movement of the direct writing nozzle and the substrate, it can realize the direct preparation of a patterned thin film coating. However, the patent only mentions that the electric field is set to set an electric field generating device in the processing head or rely on an external device to apply the electric field, and does not describe and illustrate the specific electric field generating device. Chinese patent CN 113310969A discloses a method for improving the repeatability of laser-induced breakdown spectroscopy based on time modulation. The patent modulates the plasma through electric field, magnetic field or electromagnetic field, so that the signal acquisition time is 10-500ns earlier than the conventional method, further improving the measurement accuracy. However, the electric field in the patent is set as a transverse electric field, which cannot accelerate the generated plasma longitudinally.

[0004] Therefore, it is very necessary to develop a new device and method for electric field assisted laser induced plasma processing of transparent hard and brittle materials. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the existing technology and provide an electric field-assisted laser-induced plasma processing device and method for transparent hard and brittle materials. By improving the electric field application method, the distance between the two electrode plates is shortened, so that the electrode distance can reach the micron level, and a larger electric field force can be generated under low voltage; using a transparent conductive film as an electrode, the incident laser can pass through the electrode for processing without being blocked, making the processing device simpler and the processing method more flexible.

[0006] In order to achieve the above objectives, one of the technical solutions of the present invention is: an electric field-assisted laser-induced plasma processing device for transparent hard and brittle materials, including a computer, a laser processing system, and a longitudinal electric field generating device, the laser processing system including a laser, a beam expander, a reflector, and a scanning galvanometer, the longitudinal electric field generating device including an electrode sheet and a DC regulated power supply; the computer is connected to the laser in the laser processing system; the longitudinal electric field generating device is connected to the transparent conductive film and the metal target material on the surface to be processed of the transparent hard and brittle material through the electrode sheet to form a longitudinal electric field.

[0007] The metal target is below the transparent hard and brittle material.

[0008] In a preferred embodiment of the present invention, a clamp is further included for clamping the material and controlling the distance between the material and the metal target.

[0009] Further preferably, the fixture can adjust the height of the material to be processed by a micrometer screw micrometer head, so as to achieve the effect of controlling the distance between the processing material and the metal target.

[0010] In a preferred embodiment of the present invention, the wavelength of the laser is greater than the absorption band edge of the material, so that the laser can pass through the processed material and focus on the metal target material, avoiding laser ablation on the material surface.

[0011] In a preferred embodiment of the present invention, the longitudinal electric field generating device coats the surface of the material to be processed with a transparent conductive film as the negative electrode, and the metal target material is used as the positive electrode, and the distance between the two electrodes can reach the micron level. The longitudinal electric field generating device can output different voltages and can generate an electric field of up to 1000kV / m, accelerating the movement of the plasma through the electric field force.

[0012] In a preferred embodiment of the present invention, the transparent conductive film on the surface of the transparent hard and brittle material to be processed is a thin film material with high transmittance and low resistivity. The material can be at least one of indium tin oxide, aluminum-doped zinc oxide, fluorine-doped tin oxide, and antimony-doped tin oxide, and is deposited on the surface of the transparent hard and brittle material to be processed by spraying, magnetron sputtering, thermal evaporation, electron beam evaporation, chemical vapor deposition, physical vapor deposition, atomic layer deposition, molecular beam epitaxy, sol-gel method and the like.

[0013] In order to achieve the above objectives, the second technical solution of the present invention is: a method for processing transparent hard and brittle materials based on the above-mentioned device, the specific steps including: coating the processing surface of the transparent hard and brittle material with a transparent conductive film and then fixing it above the metal target through a clamp; connecting the negative electrode in the longitudinal electric field generating device to the transparent conductive film on the processing material surface through the electrode sheet, and connecting the positive electrode to the metal target; turning on the electric field generating device, generating a longitudinal electric field between the coating surface of the transparent hard and brittle material and the metal target, and the direction of the electric field force is directed from the metal target to the material to be processed; turning on the laser, and the laser emitted by the laser is expanded by a beam expander to increase the beam diameter, and then enters the scanning galvanometer through a reflector and focuses on the surface of the metal target, exciting high-temperature and high-pressure metal plasma, which rapidly expands upward and bombards the back of the material to be processed in the reverse direction, and the etching of the transparent hard and brittle material is achieved under the combined action of the mechanical bombardment of the plasma and the laser ablation.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. The present invention utilizes the electric field force provided by the longitudinal electric field to longitudinally accelerate the plasma generated by laser ablation of the target material. The accelerated plasma has greater kinetic energy, thereby improving the material removal efficiency.

[0016] 2. This invention improves the electric field application method. The surface of the material to be processed is coated with a transparent conductive film as the negative electrode, and the metal target material is used as the positive electrode. This electric field application method shortens the distance between the two electrodes to the micron level, and can generate a larger electric field force at a lower voltage.

[0017] 3. The present invention uses a transparent conductive film as an electrode, which allows the incident laser to pass through the electrode for processing without being blocked, making the processing device simpler, the processing method more flexible, and the device simpler;

[0018] 4. The present invention introduces a longitudinal electric field to regulate the flight speed and motion trajectory of the plasma, which can accelerate the longitudinal kinetic energy of the plasma induced by the laser and make the processing process more efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1Schematic diagram of an apparatus for processing transparent hard and brittle materials using electric field-assisted laser-induced plasma according to an embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram of the principle of electric field regulation of plasma in the present invention;

[0021] Figure 3 The cross-sectional curve diagram of the sapphire microgroove under the conditions of applying an electric field and not applying an electric field according to the present invention;

[0022] In the figure: 1-computer, 2-laser, 3-beam expander, 4-reflector, 5-scanning galvanometer, 6-transparent hard and brittle material, 7-electrode, 8-DC regulated power supply, 9-metal target, 10-fixture, 11-transparent conductive film. DETAILED DESCRIPTION

[0023] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is described in more detail below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to these embodiments.

[0024] A device for electric field-assisted laser-induced plasma processing of transparent hard and brittle materials comprises a computer, a laser processing system, and a longitudinal electric field generating device. The laser processing system comprises a laser, a beam expander, a reflector, and a scanning galvanometer. The longitudinal electric field generating device comprises an electrode sheet and a DC regulated power supply. The computer is connected to the laser in the laser processing system. The longitudinal electric field generating device is connected to a transparent conductive film and a metal target material on the surface to be processed of the transparent hard and brittle material via the electrode sheet to form a longitudinal electric field.

[0025] The electric field assisted laser induced plasma processing device for transparent hard and brittle materials also includes a clamp for clamping the material and controlling the distance between the material and the metal target.

[0026] The fixture can adjust the height of the material to be processed through the micrometer screw micrometer head, so as to achieve the effect of controlling the distance between the processing material and the metal target.

[0027] The wavelength of the laser is greater than the absorption band edge of the material, so that the laser can pass through the processing material and focus on the metal target material, avoiding causing laser ablation on the surface of the material.

[0028] In the longitudinal electric field generating device, the surface of the material to be processed is coated with a transparent conductive film to serve as the negative electrode, and the metal target material is used as the positive electrode. The distance between the two electrodes can reach the micron level. The longitudinal electric field generating device can output different voltages and can generate an electric field with a maximum of 1000kV / m, accelerating the movement of plasma through the electric field force.

[0029] The transparent conductive film on the surface of the transparent hard and brittle material to be processed is a thin film material with high transmittance and low resistivity. The material can be at least one of indium tin oxide, aluminum-doped zinc oxide, fluorine-doped tin oxide, and antimony-doped tin oxide, and is deposited on the surface of the transparent hard and brittle material to be processed by spraying, magnetron sputtering, thermal evaporation, electron beam evaporation, chemical vapor deposition, physical vapor deposition, atomic layer deposition, molecular beam epitaxy, sol-gel method and other methods.

[0030] A method for processing transparent hard and brittle materials based on the above-mentioned device includes the following specific steps: coating the processing surface of the transparent hard and brittle material with a transparent conductive film and then fixing it above a metal target via a clamp; connecting the negative electrode of a longitudinal electric field generating device to the transparent conductive film on the processing material surface via an electrode sheet, and connecting the positive electrode to the metal target; turning on the electric field generating device to generate a longitudinal electric field between the coating surface of the transparent hard and brittle material and the metal target, with the direction of the electric field force pointing from the metal target to the material to be processed; turning on a laser, and transmitting the laser light to a beam expander to increase the beam diameter, and then passing through a reflector to enter a scanning galvanometer and focus on the surface of the metal target, thereby exciting high-temperature and high-pressure metal plasma, which rapidly expands upward and reversely bombards the back of the material to be processed, thereby achieving etching of the transparent hard and brittle material under the combined action of mechanical bombardment of the plasma and laser ablation.

[0031] Combine Figure 1 This embodiment provides an electromagnetic field-assisted laser-induced plasma processing device for transparent materials, comprising: a computer 1, a laser 2, a beam expander 3, a reflector 4, a scanning galvanometer 5, and a fixture 10; the transparent hard and brittle material 6 is fixed above a metal target 9 by the fixture 10, the DC regulated power supply 8 sets the coated transparent hard and brittle material as the negative electrode and the target as the positive electrode through an electrode sheet 7, the scanning galvanometer 5 is set above the metal target 9, the pulsed laser emitted by the laser 2 is suitable for being focused by the scanning galvanometer 5 onto the metal target 9, and the generated plasma etches the transparent hard and brittle material 6 under the control of the longitudinal electric field.

[0032] In a specific application example, electric field assisted laser induced plasma etching technology is used to process sapphire. The processed surface of the sapphire is coated with an indium tin oxide film by magnetron sputtering. The sapphire is fixed by a fixture 10. The laser uses a 1064nm infrared laser. The laser generates a laser beam focused on a metal iron target, generating iron plasma to bombard the back of the sapphire, thereby producing an etching effect. Figure 2 , the electric field force provided by the electric field is used to accelerate the generated plasma longitudinally. The accelerated plasma has stronger kinetic energy, which improves the etching efficiency. Figure 3 ,It can be seen from the cross-sectional curve that the groove etched ,is deeper when the electric field is applied compared to the groove ,crosssection processed without applying the electric field.

[0033] In this embodiment, laser processing parameters, including laser wavelength, repetition rate, laser power, pulse width, scanning speed, and number of scans, can be set in real time before processing. For example, in this embodiment, the laser wavelength can be set to 1064nm, the repetition rate to 90kHz, the laser power to 10.8W, the pulse width to 30ns, the scanning speed to 10mm / s, and the number of scans to 5. Before processing, the distance between the material to be processed and the target can be set by raising and lowering the fixture. For example, in this example, the distance can be set to 200μm. After the pre-processing parameters are set, the electric field generator is activated, and the voltage of the electric field generator can be set to 100V.

[0034] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electric field assisted laser induced plasma processing device for transparent hard and brittle materials, characterized in that: The invention comprises a computer, a laser processing system, and a longitudinal electric field generating device. The laser processing system comprises a laser, a beam expander, a reflector, and a scanning galvanometer. The longitudinal electric field generating device comprises an electrode sheet and a DC regulated power supply. The computer is connected to the laser in the laser processing system. The longitudinal electric field generating device forms a longitudinal electric field by connecting the electrode sheet to a transparent conductive film and a metal target material on the surface to be processed of a transparent hard and brittle material. In the longitudinal electric field generating device, the transparent conductive film plated on the surface of the transparent hard and brittle material to be processed is used as the negative electrode, the metal target material is used as the positive electrode, and the distance between the two electrodes can reach the micron level; the longitudinal electric field generating device can output different voltages.

2. The electric field assisted laser induced plasma processing device for transparent hard and brittle materials according to claim 1, characterized in that: Also includes clamps.

3. The electric field assisted laser induced plasma processing device for transparent hard and brittle materials according to claim 2, characterized in that: The fixture adjusts the height of the material to be processed through a micrometer screw micrometer head.

4. The electric field assisted laser induced plasma processing device for transparent hard and brittle materials according to claim 1, characterized in that: The wavelength of the laser is greater than the absorption band edge of the material.

5. The electric field assisted laser induced plasma processing device for transparent hard and brittle materials according to claim 1, characterized in that: The material of the transparent conductive film is at least one of indium tin oxide, aluminum-doped zinc oxide, fluorine-doped tin oxide, and antimony-doped tin oxide.

6. The electric field assisted laser induced plasma processing device for transparent hard and brittle materials according to claim 1, characterized in that: The transparent conductive film is deposited by one of spraying, magnetron sputtering, thermal evaporation, electron beam evaporation, chemical vapor deposition, physical vapor deposition, atomic layer deposition, molecular beam epitaxy, and sol-gel method.

7. A method for processing transparent hard and brittle materials based on the electric field assisted laser induced plasma processing device for transparent hard and brittle materials according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: coating a transparent conductive film on the processing surface of a transparent hard and brittle material and fixing the film on top of a metal target material by a clamp; connecting the negative electrode of a longitudinal electric field generating device to the transparent conductive film on the processing material surface through an electrode sheet, and connecting the positive electrode to the metal target material; Turn on the electric field generator, and a longitudinal electric field is generated between the coating surface of the transparent hard and brittle material and the metal target. The direction of the electric field force is from the metal target to the material to be processed. Turn on the laser, and the laser emitted by the laser will increase the beam diameter through the beam expander, and then enter the scanning galvanometer through the reflector and focus on the surface of the metal target, exciting high-temperature and high-pressure metal plasma. The plasma quickly expands upward and bombards the back of the material to be processed in the opposite direction. Under the combined action of the mechanical bombardment of the plasma and the laser ablation, the etching of transparent hard and brittle materials is achieved.

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