Plasma gas discharge electrode preparation method, gas discharge array structure and gas mixing preparation method

Abstract

The invention provides a plasma gas discharge electrode preparation method, a gas discharge array structure and a plasma gas mixing preparation method, and the method comprises the steps: enabling a light source to emit ultraviolet light, enabling the ultraviolet light to pass through a pattern gap of a mask plate, and enabling the ultraviolet light to irradiate a photoresist substrate with a certain thickness; the photoresist in the area irradiated by the ultraviolet light is subjected to a photochemical reaction, interlinks are cut off, a polymer is weakened, a pattern which is the same as or complementary to a mask plate is obtained on a substrate after development, and then pattern transfer is completed through etching and coating technologies. According to the plasma gas mixing method, different inert gases are mixed according to different proportions, the prepared inert gases excite a negative electrode and a positive electrode in a plasma state, a discharge target unit is controlled, and the problem of detection of electromagnetic wave hidden targets such as terahertz and microwaves in a room-temperature complex environment is solved; and the method is of great significance for researching the characteristics of the plasma and providing various applications of the weakly ionized plasma.

Description

Technical Field

[0001] The present invention belongs to the technical field of luminescent discharge, and in particular relates to a method for preparing a plasma gas discharge electrode, a gas discharge array structure and a plasma gas mixing preparation method. Background Art

[0002] Plasma is the fourth physical state besides solid, liquid and gas. Since gas can be excited into plasma state under high temperature or electromagnetic wave, the characteristics of plasma state can be used to detect electromagnetic waves such as terahertz wave and microwave. Plasma state can excite inert gas such as neon and argon to produce glow discharge. By applying DC voltage to the gas-filled gap between the positive and negative electrodes, the electrons generated between the positive and negative electrodes are used to excite neutral atoms or molecules. When the excited particles fall back to the ground state from the excited state, they release excess energy in the form of light. In the excited state, the atoms that make up the molecule gain enough kinetic energy and begin to separate from each other. The outer electrons of the atoms break free from the nucleus and become free electrons. The atoms that lose electrons become positive ions. Plasma is produced through this ionization process.

[0003] At present, the electrode preparation method of large-scale plasma equipment relies on semiconductor and micromachining methods. In 2017, the patent "A method for preparing a plasma discharge electrode" proposed a plasma discharge electrode and its preparation method, which solved the problem that the self-bias effect of the insulating layer of the plasma discharge electrode on its surface has been determined and cannot be adapted to different processes. However, this preparation method is not suitable for micro-nano scale plasma equipment, plasma chambers, plasma detectors, etc. In addition, the existing plasma discharge electrodes are installed on plasma equipment, generally larger plasma equipment, and there are no relevant reports on the preparation methods of micron-level miniaturized plasma detection equipment discharge electrodes and arrayed plasma detection equipment discharge electrodes. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings that the plasma electrodes prepared by the existing methods are only suitable for large plasma equipment but not for micron-level miniaturized plasma detection equipment, and provide a plasma gas discharge electrode preparation method, a plasma gas discharge electrode and a plasma gas mixing method.

[0005] To achieve the above purpose, the technical solution provided by the present invention is:

[0006] A method for preparing a plasma gas discharge electrode comprises the following steps:

[0007] Step 1: Determine the material and size of the plasma gas discharge electrode plate required for the design;

[0008] Step 2: Select a quartz crystal as a substrate for the plasma gas discharge electrode, and clean and dry the substrate;

[0009] Step 3: Apply photoresist on the substrate;

[0010] Step 4: Use ultraviolet light to bake the coated substrate;

[0011] Step 5: After the substrate is cooled to room temperature, a mask plate is placed on the substrate for mask exposure;

[0012] Step 6: Develop the sample after exposure so that the exposed part is fully dissolved and the pattern is displayed, and then use deionized water to wash away the residual developer;

[0013] Step 7: Plating a metal film on the surface of the sample;

[0014] Step 8: Remove the photoresist and excess metal film to obtain the required upper electrode plate and lower electrode plate.

[0015] Furthermore, in step 2, the process of cleaning and drying the substrate is as follows:

[0016] First, the quartz crystal substrate was placed under an ultrasonic device and cleaned with anhydrous ethanol for 30 minutes to remove dust from the substrate;

[0017] Then, the anhydrous ethanol residue was cleaned with deionized water, and the water stains were blown dry with nitrogen to ensure that all the anhydrous ethanol on the crystal surface was evaporated.

[0018] Furthermore, in step 3, high and low speeds are used in the process of spin coating the photoresist. The low speed spin coating ensures that the photoresist is evenly attached to the substrate surface, and the high speed spin coating effectively controls the thickness of the photoresist.

[0019] Furthermore, in step 3, the low speed is 700 r / min to 800 r / min; and the high speed is 2000 r / min.

[0020] Furthermore, in step 4, the baking temperature is selected to be 90° C. and the baking time is 90 seconds.

[0021] Furthermore, in step 5, the exposure time is selected to be 15 minutes.

[0022] Furthermore, in step 6, the developing time is selected to be 15 minutes.

[0023] A plasma gas discharge array structure comprises an upper electrode plate, a middle detection unit and a lower electrode plate which are arranged in sequence from top to bottom. The upper electrode plate and the lower electrode plate are prepared by the plasma gas discharge electrode preparation method.

[0024] A plasma gas mixing preparation method comprises the following steps:

[0025] Step 1, building a plasma gas mixing preparation system, which includes a vacuum pump, a first switch, a second switch, two vacuum gauges, a plurality of gas bottles, a plurality of needle valves, a gas mixing tank and the above-mentioned plasma gas discharge array structure;

[0026] An output port of the vacuum pump is connected to an input end of the gas mixing tank through a first switch, and a first vacuum gauge is connected to a pipeline between the first switch and the gas mixing tank;

[0027] Multiple gas bottles are connected to the gas mixing tank through needle valves respectively;

[0028] The output end of the gas mixing tank is connected to the plasma gas discharge array structure through a needle valve;

[0029] Another output port of the vacuum pump is connected to a second switch, and the second switch is connected to an output end of a needle valve arranged at an output end of the gas mixing tank;

[0030] A second vacuum gauge is arranged on a branch line close to the plasma gas discharge array structure;

[0031] Step 2: Start the vacuum pump. When the vacuum degree of the vacuum pump is less than 1*10 -1 After Pa, close the first switch;

[0032] Step 3, open the pressure reducing valve on each gas bottle, and then slowly open the needle valve connected to each gas bottle, so that the gas in the gas bottle enters the mixed gas tank; monitor the air pressure in the mixed gas tank by the first vacuum gauge to adjust the mixed gas ratio, and when the gas in the mixed gas tank meets the inflation requirements, close the needle valve connected to the gas bottle;

[0033] Step 4, turning on the second switch to evacuate the plasma gas discharge array structure cavity, and then turning off the second switch after the evacuation;

[0034] Step 5, slowly open the needle valve arranged at the output end of the gas mixing tank, and the mixed gas in the gas mixing tank enters the plasma gas discharge array structure cavity;

[0035] The gas pressure in the plasma gas discharge array structure is monitored by a second vacuum gauge. When the gas pressure meets the inflation requirement, the vacuum pump and the needle valve arranged at the output end of the mixing tank are closed to complete the mixing preparation of the plasma gas.

[0036] The advantages of the present invention are:

[0037] 1. In the plasma gas discharge electrode preparation method proposed in the present invention, under ultraviolet light, photoresist is used as a medium to realize mask pattern transfer. The light source emits ultraviolet light, which passes through the pattern gaps of the mask and then irradiates the substrate coated with a certain thickness of photoresist. The photoresist in the area irradiated by ultraviolet light undergoes a photochemical reaction, the crosslinks are cut off, and the polymer is weakened. After development, a pattern identical to or complementary to the mask is obtained on the substrate. Finally, the pattern transfer is completed through etching and coating technology. This method can be used to prepare an electrode array with a minimum line width of 10 microns, which solves the problem of the current lack of electrode preparation methods for miniaturized plasma detection equipment and can be applied to the preparation of electrodes for micro-nano plasma equipment, plasma chambers, plasma detectors, etc.

[0038] 2. The electrode prepared by the method of the present invention is applied to a miniaturized plasma device, and the control efficiency can be improved by controlling the plasma unit by controlling the electrode individually, scanning, discretely, or integrally.

[0039] 3. The present invention provides a plasma gas mixing method, which uses different inert gases to mix gases in different proportions to prepare the required gas, and accurately controls the mixing ratio of different gases during the preparation process to prepare a plasma mixed gas, such as a Penning gas. The method of the present invention improves the efficiency of generating plasma mixed gas and the operating efficiency of plasma equipment, and is suitable for aspects such as charging and replacing gases in plasma equipment and designing plasma detectors.

[0040] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0042] Figure 1 is a flow chart of a method for preparing a plasma gas discharge electrode according to the present invention;

[0043] Figure 2 It is a structural schematic diagram of a plasma gas discharge array structure prepared by the method of the present invention;

[0044] Figure 3 The present invention is a block diagram of the plasma gas mixing system.

[0045] In the figure: 1-middle layer detection unit, 2-upper layer electrode plate, 3-lower layer electrode plate. DETAILED DESCRIPTION

[0046] Embodiments of the present invention are described in detail below. The embodiments are exemplary and intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0047] The method for preparing the plasma gas discharge electrode proposed in this embodiment comprises the following steps:

[0048] Step 1: Build a model. Figure 2 As shown, the plasma discharge array structure mainly includes an upper electrode plate, a middle detection unit and a lower electrode plate. The design model of the upper electrode plate and the lower electrode plate is established to determine the size and material of the lower electrode plate of the upper electrode plate. In this embodiment, the specific implementation parameters are shown in Table 1.

[0049] Table 1 Electrode design parameters

[0050] Overall dimensions Number of electrodes Electrode size Electrode Materials Substrate material Upper electrode plate 70mm*70mm 32 20μm wide ring aluminum Quartz glass Lower electrode plate 70mm*70mm 32 40μm wide straight line aluminum Quartz glass

[0051] The upper electrode plate and the lower electrode plate are prepared by the following steps respectively.

[0052] Step 2: Ultrasonic cleaning. A quartz crystal substrate with a certain thickness is selected, and the quartz substrate is placed under ultrasonic waves and cleaned with anhydrous ethanol for 30 minutes to remove dust from the substrate. In this embodiment, the thickness of the quartz crystal is 500 μm.

[0053] Blow dry with liquid nitrogen. Use deionized water to clean the anhydrous ethanol residue, and blow dry the water stains with nitrogen to ensure that all the anhydrous ethanol on the surface of the crystal is volatilized. Otherwise, since anhydrous ethanol is the stripping liquid of the photoresist, it will cause the photoresist to not adhere well to the wafer, affecting the photolithography effect.

[0054] Step 3: Apply photoresist. Use a desktop coating machine for coating, and use a KW-4A desktop coating machine. In the process of spin coating photoresist, high and low speeds are used for spin coating. The low speed is to ensure that the photoresist is evenly attached to the substrate surface, and the high speed can effectively control the thickness of the photoresist.

[0055] In the specific implementation process of spin coating photoresist, photoresist is spin coated on a double-sided polished silicon substrate through a spin coater. The film obtained by selecting a low speed of 500r / min cannot be evenly adhered to the substrate surface, and some areas even have no photoresist at all. By increasing the low speed, 700r / min and 800r / min are used to obtain a uniformly spin-coated photoresist substrate (the high speed is 2000r / min).

[0056] Step 4: UV baking. In order to increase the adhesion between the film and the substrate and reduce the stress inside the adhesive layer, after spin coating the photoresist, place it on a heating table to bake the coated substrate.

[0057] In the specific implementation of UV baking, a Thermolyne heating table is selected to bake the coated substrate. The baking temperature and time will have an important impact on the experimental results. If the baking time is too short or the temperature is too low, the adhesion between the photoresist and the substrate will be low, and the stress inside the photoresist will be too large, resulting in debonding. Too long a time or too high a temperature will cause the film layer to harden, blacken, wrinkle, reduce the sensitivity of the photoresist, and blur the pattern after development. The best baking temperature is 90°C, and the best baking time is 90s.

[0058] Step 5: Mask exposure: After the substrate cools down to room temperature, a designed mask plate is placed on the substrate and a photolithography machine is used to complete the mask exposure.

[0059] In the specific implementation of mask exposure, exposure time that is too long or too short will affect the quality of photolithography. If the exposure time is too short, the photoresist will not undergo a thorough photochemical reaction, and the exposed photoresist cannot be completely dissolved during development and remains on the substrate surface. If the exposure time is too long, the photoresist in the unexposed area will be easily removed by photochemical reaction due to diffraction and scattering. The optimal exposure time is 15 minutes.

[0060] Step 6: Development. Place the sample in the developer and shake it slightly to fully dissolve the exposed part so that the pattern is displayed, and then use deionized water to wash away the residual developer.

[0061] During the specific implementation of the exposure process, the development time of the exposed substrate in the developer will also affect the photolithography quality. If the time is too short, the photoresist in the exposed area will not be completely dissolved, and the outline of the pattern cannot be clear. If the development time is too long, while dissolving the photoresist in the exposed area, it will also corrode the unexposed pattern edges.

[0062] During the specific implementation of the exposure process, debonding may occur. The reason may be that the baking time is too short or the temperature is too low, which cannot ensure that the photoresist is fully adhered to the double-sided silicon substrate, resulting in debonding of the photoresist in the unexposed area due to poor adhesion during development. The photoresist may not be dissolved after development. On the one hand, the reason may be that the exposure time is too short, and the photoresist that cannot be fully exposed cannot be dissolved during development due to low concentration; on the other hand, it may be caused by the development time being too short. Therefore, the best development time is 15 minutes.

[0063] The specific process parameters of mask lithography in the specific embodiment are shown in Table 2.

[0064] Table 2 Mask lithography process parameters

[0065]

[0066] In a specific embodiment, the upper and lower electrode plate patterns are photolithographically processed on a quartz substrate using the mask photolithography process parameters in Table 2. After a series of photolithography process flows, an electrode pattern with a clear boundary between the exposed and unexposed areas is obtained, and a Nikon ECLIPSE L150 microscope is used to observe different patterns, and it is observed that the patterns after photolithography are complete and clear, and the minimum line width is less than 20 μm.

[0067] Step 7: Metal film coating: Use a vacuum box coating machine to complete the preparation of the metal film.

[0068] In the specific implementation of metal film coating, the ZZS500-2 / G vacuum box coating machine is used to complete the preparation of metal film. Different metal films can be deposited by resistance thermal evaporation and electron beam thermal evaporation technology. The cleaned photolithography substrate is clamped on the workpiece clamp for film preparation. The deposition temperature of the metal film is set to 120°C. The workpiece feedback current is adjusted to ensure that the workpiece rotates at a certain speed to ensure uniform heating and uniform film layer. The vacuum degree in the box is pumped to low vacuum by a mechanical pump, and then converted to a mechanical pump and a diffusion pump to pump the box to high vacuum. When the vacuum degree of the box is 1.0×10 -2 Pa film is plated, and finally cooled and taken out. The prepared metal film is taken out and cooled for a period of time (room temperature). During the entire metal film plating process, ion beam assisted deposition is used to increase the adhesion between the metal film and the substrate. The preparation process is detailed in Table 3.

[0069] Table 3 Metal film preparation process

[0070]

[0071] Step 8: Remove the photoresist and excess metal film using a stripping process to obtain the upper and lower electrode plates.

[0072] In a specific embodiment, a metal aluminum electrode is prepared on a quartz substrate after photolithography according to the above steps, and then a stripping process is used to remove the photoresist and excess metal film to obtain the upper and lower electrode plates. The metal electrode patterns at different positions are observed using a Nikon ECLIPSE L150 microscope, and the metal electrode patterns are complete and clear, consistent with the designed electrodes.

[0073] Based on the plasma gas discharge array structure obtained above, this embodiment takes Penning gas mixing as an example and proposes a plasma gas mixing preparation method comprising the following steps:

[0074] Step 1: Build a plasma gas mixing preparation system, which includes a vacuum pump, a first switch, a second switch, two vacuum gauges, multiple gas bottles, multiple needle valves, a gas mixing tank and the plasma gas discharge array structure.

[0075] An output port of the vacuum pump is connected to an input end of the gas mixing tank through a first switch, and a first vacuum gauge is connected to a pipeline between the first switch and the gas mixing tank;

[0076] A plurality of gas cylinders are connected to the gas mixing tank through a first needle valve, a second needle valve and a third needle valve respectively; the gas cylinders contain different inert gases;

[0077] The output end of the gas mixing tank is connected to the plasma gas discharge array structure through a fourth needle valve;

[0078] Another output port of the vacuum pump is connected to a second switch, and the second switch is connected to an output end of a needle valve arranged at an output end of the gas mixing tank;

[0079] A second vacuum gauge is arranged on a branch line close to the plasma gas discharge array structure.

[0080] Seal and connect the vacuum pump, gas switch, vacuum gauge, gas mixing tank, needle valve, gas bottle, and plasma discharge chamber to ensure that the system is leak-proof, and then close all switches and needle valves.

[0081] In this embodiment, the gas cylinders include neon gas cylinders and argon gas cylinders.

[0082] Step 2: Start the vacuum pump and let it work normally. When the vacuum degree in the vacuum pump is less than 1*10 -1 After Pa, close the first switch.

[0083] Step 3: First open the pressure reducing valves of different gas bottles, then slowly open the respective needle valves at the set opening speed to allow the gas to enter the gas mixing tank. Use the first vacuum gauge to monitor the air pressure in the gas mixing tank and adjust the mixing ratio so that the gas in the gas mixing tank meets the inflation requirements, and then close the needle valve.

[0084] Step 4: Turn on the second switch to evacuate the plasma gas discharge array structure cavity. When the vacuum degree is less than 1*10 -1 After Pa, close the second switch.

[0085] Step 5: Slowly open the fourth needle valve at the set opening speed to allow the mixed gas in the gas mixing tank to enter the discharge array structure. The gas pressure in the discharge array structure is monitored by the second vacuum gauge. When the gas in the discharge array structure meets the inflation requirements, the fourth needle valve and the vacuum pump are closed to complete the mixing preparation of the plasma gas.

[0086] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should be included in the protection scope of the present invention.

Claims

1. A method for preparing a plasma gas discharge electrode, characterized in that: The following steps are involved: Step 1: Determine the material and size of the plasma gas discharge electrode plate required for the design; Step 2: Select a quartz crystal as a substrate for the plasma gas discharge electrode, and clean and dry the substrate; Step 3: Apply photoresist on the substrate; Step 4: Use ultraviolet light to bake the coated substrate; Step 5: After the substrate is cooled to room temperature, a mask plate is placed on the substrate for mask exposure; Step 6: Develop the sample after exposure so that the exposed part is fully dissolved and the pattern is displayed, and then use deionized water to wash away the residual developer; Step 7: Plating a metal film on the surface of the sample; Step 8: Remove the photoresist and excess metal film to obtain the required upper electrode plate and lower electrode plate.

2. The method for preparing a plasma gas discharge electrode according to claim 1, characterized in that: In step 2, the process of cleaning and drying the substrate is as follows: First, place the quartz crystal substrate under an ultrasonic device and use anhydrous ethanol to clean it to remove dust from the substrate; Then, the anhydrous ethanol residue was cleaned with deionized water, and the water stains were blown dry with inert gas to ensure that all the anhydrous ethanol on the crystal surface was evaporated.

3. The method for preparing a plasma gas discharge electrode according to claim 1, characterized in that: In step 3, high and low speeds are used in the process of spin coating the photoresist. The low speed spin coating ensures that the photoresist is evenly attached to the substrate surface, and the high speed spin coating effectively controls the thickness of the photoresist.

4. The method for preparing a plasma gas discharge electrode according to claim 3, characterized in that: The low speed is 700 r / min to 800 r / min; the high speed is 2000 r / min.

5. The method for preparing a plasma gas discharge electrode according to claim 1, characterized in that: In step 4, the baking temperature is selected to be 90° C. and the baking time is 90 seconds.

6. The method for preparing a plasma gas discharge electrode according to claim 1, characterized in that: In step 5, the exposure time is selected to be 15 minutes.

7. The method for preparing a plasma gas discharge electrode according to claim 1, characterized in that: In step 6, the developing time is selected to be 15 minutes.

8. A plasma gas discharge array structure, characterized in that: It comprises an upper electrode plate, a middle detection unit and a lower electrode plate which are arranged in sequence from top to bottom; the upper electrode plate and the lower electrode plate are prepared by the plasma gas discharge electrode preparation method according to claim 1.

9. A plasma gas mixing preparation method, characterized in that: The following steps are involved: Step 1, constructing a plasma gas mixing preparation system, the system comprising a vacuum pump, a first switch, a second switch, two vacuum gauges, a plurality of gas bottles, a plurality of needle valves, a gas mixing tank and the plasma gas discharge array structure according to claim 3; An output port of the vacuum pump is connected to an input end of the gas mixing tank through a first switch, and a first vacuum gauge is connected to a pipeline between the first switch and the gas mixing tank; A plurality of gas cylinders are connected to the gas mixing tank through needle valves respectively; the gas cylinders contain different inert gases; The output end of the gas mixing tank is connected to the plasma gas discharge array structure through a needle valve; Another output port of the vacuum pump is connected to a second switch, and the second switch is connected to an output end of a needle valve arranged at an output end of the gas mixing tank; A second vacuum gauge is arranged on a branch line close to the plasma gas discharge array structure; Step 2, start the vacuum pump, and when the vacuum degree of the vacuum pump is less than the set threshold, close the first switch; Step 3, open the pressure reducing valve on each gas bottle, and then open the needle valve connected to each gas bottle at a set opening speed, so that the gas in the gas bottle enters the mixed gas tank; monitor the air pressure in the mixed gas tank by a first vacuum gauge to adjust the mixed gas ratio, and when the gas in the mixed gas tank meets the inflation requirements, close the needle valve connected to the gas bottle; Step 4, turning on the second switch to evacuate the plasma gas discharge array structure cavity, and then turning off the second switch after the evacuation; Step 5: Open the needle valve at the output end of the gas mixing tank at a set opening speed, and the mixed gas in the gas mixing tank enters the plasma gas discharge array structure cavity; The gas pressure in the plasma gas discharge array structure is monitored by a second vacuum gauge. When the gas pressure meets the inflation requirement, the vacuum pump and the needle valve arranged at the output end of the mixing tank are closed to complete the mixing preparation of the plasma gas.

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