Device and method for processing transparent hard and brittle material by using laser-induced plasma assisted by electric field

Abstract

The invention belongs to the technical field of micromachining, and particularly discloses a device and method for machining transparent hard and brittle materials through electric field assisted laser induced plasmas, the device comprises a computer, a laser machining system and a longitudinal electric field generation device, and the laser machining system comprises a laser device, a beam expander, a reflector and a scanning galvanometer. The longitudinal electric field generating device comprises an electrode plate and a direct-current stabilized power supply; the computer is connected with a laser in the laser processing system; and the longitudinal electric field generating device is connected with the transparent conductive film on the to-be-processed surface of the transparent hard and brittle material and the metal target below the material through an electrode plate to form a longitudinal electric field. According to the invention, the distance between the two electrode plates is shortened by improving an electric field applying mode, so that the distance between the electrodes can reach a micron level, and a relatively large electric field force can be generated under a relatively low voltage; the transparent conductive film is used as the electrode, so that the incident laser can penetrate through the electrode for processing without being blocked, the processing device is simpler, and the processing mode is more flexible.

Description

Technical Field

[0001] The 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 with electric field-assisted laser-induced plasma. Background Art

[0002] Transparent hard and brittle materials have high light transmittance, high heat resistance and good corrosion resistance, and are widely used in aerospace, microelectronic devices 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 the microstructure processing of transparent hard and brittle materials a technical challenge.

[0003] In view of the difficulty in processing the microstructure of transparent hard and brittle materials, some scholars have proposed laser-induced plasma-assisted ablation technology, which focuses a high-energy laser beam on a metal target material below the transparent hard and brittle material to stimulate a high-temperature and high-pressure plasma. The plasma expands upward and reversely bombards the back of the transparent hard and brittle material above the target material to achieve the effect of etching the material. Laser-induced plasma etching technology has lower costs, lower energy consumption, less surface deposits, and smaller thermal stress. It is a new and advantageous micro-processing method for transparent hard and brittle materials. However, the existing laser-induced plasma etching technology still has the problem of uncontrollable plasma. For this reason, many scholars use electromagnetic fields to regulate plasma. Chinese patent CN 102064213A discloses a transmission laser-electromagnetic field coupled thruster, which accelerates the plasma through the action of an electric field and applies a Lorentz force to the plasma through a magnetic field, so that the plasma obtains a higher ionization rate and ejection rate, thereby forming a thrust pulse. However, in this patent, since the electrode sheet is a non-transparent material, it is necessary to open a hole or make a groove so that the laser is incident from the hole or groove, which increases 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 filters, electric / magnetic fields, etc., and implements the focused injection of plasma through a high-temperature conical nozzle. Combined with the relative movement of the direct writing nozzle and the substrate, the direct preparation of a graphic thin film coating can be achieved. However, the patent only mentions that the electric field is set to set an electric field generating device in the processing head or to 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 combination, 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, and the generated plasma cannot be accelerated longitudinally.

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

[0005] The purpose of the present invention is to overcome the defects of the prior art 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 electrodes 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, comprising a computer, a laser processing system, and a longitudinal electric field generating device, wherein the laser processing system comprises a laser, a beam expander, a reflector, and a scanning galvanometer, and 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 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, thereby avoiding laser ablation on the material surface.

[0011] In a preferred embodiment of the present invention, in the longitudinal electric field generating device, a transparent conductive film is coated on the surface of the material to be processed to serve as the negative electrode, and a 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, thereby 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 purpose, the second technical solution of the present invention is: a method for processing transparent hard and brittle materials based on the above-mentioned device, and the specific steps include: 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 surface of the processing material through an 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 from the metal target to the material to be processed; turning on the laser, and the laser emitted by the laser increases the beam diameter through a beam expander, 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, the plasma rapidly expands upward, and reversely bombards the back of the material to be processed, 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 the laser ablation target material. The accelerated plasma has greater kinetic energy, thereby improving the material removal efficiency;

[0016] 2. The present invention improves the electric field application method, by coating the surface of the material to be processed with a transparent conductive film as the negative electrode and using the metal target as the positive electrode. The above electric field application method shortens the distance between the two electrodes, so that the electrode distance can reach the micron level, and a larger electric field force can be generated 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 1A schematic diagram of a device for processing transparent hard and brittle materials using electric field-assisted laser-induced plasma provided in an embodiment of the present invention;

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

[0021] Figure 3 It is a 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 sheet, 8-DC regulated power supply, 9-metal target, 10-fixture, 11-transparent conductive film. DETAILED DESCRIPTION

[0023] In order to make the purpose, 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] An electric field-assisted laser-induced plasma processing device for 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 stabilized voltage 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 a surface to be processed of a transparent hard and brittle material through 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 material.

[0027] 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, thereby avoiding laser ablation on the surface of the material.

[0028] In the longitudinal electric field generating device, a transparent conductive film is plated on the surface of the material to be processed to serve as the negative electrode, and a 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 of up to 1000kV / m, thereby 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 use 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 device, specifically comprising the following steps: coating a processing surface of the transparent hard and brittle material with a transparent conductive film and then fixing it above a metal target through a clamp; connecting the negative electrode in 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; 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, 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 increases the beam diameter through a beam expander, and then enters a scanning galvanometer through a reflector and focuses 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, so that the transparent hard and brittle material is etched under the combined action of mechanical bombardment of the plasma and laser ablation.

[0031] Combination Figure 1 The present embodiment provides an electromagnetic field assisted laser induced plasma processing transparent material device, 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 on the 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 through the electrode sheet 7, and sets the target material as the positive electrode, the scanning galvanometer 5 is set above the metal target 9, the pulse laser emitted by the laser 2 is suitable for being focused to the metal target 9 by the scanning galvanometer 5, and the generated plasma etches the transparent hard and brittle material 6 under the regulation 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 reversely 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 after applying the electric field is deeper than the groove ,cross-section processed without applying the electric field.

[0033] In this embodiment, before processing, the laser processing parameters can be set in real time, including laser wavelength, repetition frequency, laser power, pulse width, scanning speed, and number of scans; for example, in this embodiment, the laser wavelength can be set to 1064nm, the repetition frequency 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 material can be set by lifting the fixture; for example, in this example, the spacing can be set to 200μm. After the parameters are set before processing, the electric field generating device is started, and the voltage of the electric field generating device 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 it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions 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: It includes a computer, a laser processing system, and a longitudinal electric field generating device. The laser processing system includes a laser, a beam expander, a reflector, and a scanning galvanometer. The longitudinal electric field generating device includes an electrode sheet and a DC stabilized 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 a surface to be processed of a transparent hard and brittle material through the electrode sheet to form a longitudinal electric field.

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: 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.

6. The electric field assisted laser induced plasma processing device for transparent hard and brittle materials according to claim 5, characterized in that: The longitudinal electric field generating device can output different voltages.

7. The electric field assisted laser induced plasma processing device for transparent hard and brittle materials according to claim 1 or 5, 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.

8. The electric field assisted laser induced plasma processing device for transparent hard and brittle materials according to claim 1 or 5, characterized in that: The deposition method of the transparent conductive film is 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.

9. A method for processing transparent hard and brittle materials based on the electric field assisted laser induced plasma processing transparent hard and brittle material device according to any one of claims 1 to 8, 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 the surface of a metal target by a clamp; connecting the negative electrode in 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; Turn on the electric field generating device, and a longitudinal electric field is generated between the coating surface of the transparent hard and brittle material and the metal target, and 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 reverse 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.

Images