A magnetic field enhanced coupling plasma processing apparatus and method

Abstract

The application provides a magnetic field enhanced coupling plasma processing device and method, which comprises a capacitively coupled plasma device and a racetrack magnetic pole device; the capacitively coupled plasma device comprises an upper anode plate and a lower cathode plate, a plasma working area is formed between the upper anode plate and the lower cathode plate, and an electric field is formed between the upper anode plate and the lower cathode plate; the racetrack magnetic pole device comprises a moving device and a racetrack magnetic pole installed on the moving device, the moving device drives the racetrack magnetic pole to move along a plane parallel to the lower cathode plate; the racetrack magnetic pole comprises adjacent permanent magnets with opposite magnetic poles, and the permanent magnets form an additional coupling magnetic field which restricts the bipolar diffusion motion of electrons in the electric field. The application modulates the density, distribution and directional drift of the multi-field coupled plasma, greatly improves the actual processing efficiency of difficult-to-process materials, makes the plasma rapid processing of medium-large aperture optical elements possible, and improves the laser damage resistance of the elements.

Description

Technical Field

[0001] This invention belongs to the field of plasma processing technology and relates to a magnetic field enhanced coupled plasma processing device and method. Background Technology

[0002] Plasma devices are widely used in the manufacturing processes of integrated circuits (ICs), MEMS devices, and medium-to-large aperture optical components. Commonly used plasma devices include capacitively coupled plasma (CCP) devices and inductively coupled plasma (ICP) devices. CCP devices have a simple structure and relatively easy discharge, making them the earliest commercially viable plasma processing technology. However, their biggest problem is the inability to control the energy and density of the plasma. Inductively coupled plasma (ICP) devices utilize a multi-turn radio frequency (RF) antenna coil outside the chamber. During plasma etching, the planar coil is loaded with RF power, which is coupled into the chamber through a dielectric window to excite the process gas introduced into the chamber, forming plasma.

[0003] Although radio frequency capacitively coupled plasma (ICP) has made up for the shortcomings of capacitively coupled plasma (CCP) methods, the processing efficiency of ICP remains low due to limitations in electrode size and plasma uniformity issues. This prevents the mass production of semiconductor devices and the processing of medium and large aperture optical components.

[0004] Existing technologies utilize magnetron sputtering anomalous glow discharge to achieve high-efficiency material processing from line to surface. While this method overcomes the shortcomings of existing plasma processing, magnetron sputtering discharge has two drawbacks: first, the vacuum operating conditions for capacitively coupled discharge and magnetron sputtering anomalous glow discharge are not uniform, making it difficult to achieve the optimal discharge state; second, the processed materials are mostly semiconductors or non-conductive optical components (silicon carbide, fused silica, and sapphire), requiring a large power supply to meet the demands of mass production and processing of medium to large diameter components, thus resulting in high costs.

[0005] Therefore, how to provide a magnetic field-enhanced coupled plasma processing device and method that can achieve plasma density adjustment and efficient etching of workpiece surfaces is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention proposes a magnetic field enhanced coupled plasma processing device and method to solve the technical problems in the prior art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] This invention discloses a magnetic field-enhanced coupled plasma processing apparatus, comprising: a capacitively coupled plasma device and a runway magnetic pole device; wherein,

[0009] The capacitively coupled plasma device includes a vacuum chamber and an upper anode plate and a lower cathode plate located inside the vacuum chamber. The area between the upper anode plate and the lower cathode plate is the plasma working area. A radio frequency power supply is applied to the lower cathode plate to form an electric field between the upper anode plate and the lower cathode plate. The component to be processed is placed on the upper surface of the lower cathode plate.

[0010] The runway magnetic pole device is located in the bottom space of the lower cathode plate and includes a motion device and a runway magnetic pole installed on the motion device. The motion device drives the runway magnetic pole to move along a plane parallel to the lower cathode plate. The runway magnetic pole includes permanent magnets with opposite magnetic properties placed adjacent to each other, forming an arched magnetic field line above the lower cathode plate, forming an additional coupled magnetic field that confines the bipolar diffusion motion of electrons in the electric field.

[0011] Preferably, the motion device includes a guide rail, a stepper motor, and a slider; the guide rail is mounted parallel to the bottom space of the lower cathode plate, one end of the guide rail is connected to the output end of the stepper motor, and the track magnetic pole is connected to the guide rail through the slider and moves linearly along the guide rail.

[0012] Preferably, the runway magnetic poles include an outer ring rectangular magnet and a long rectangular magnet placed horizontally at the center of the axis of symmetry of the outer ring rectangular magnet; the top of the outer ring rectangular magnet is the N pole and the bottom is the S pole; the top of the long rectangular magnet is the S pole and the bottom is the N pole.

[0013] Preferably, both the outer ring rectangular magnet and the long strip rectangular magnet are linearly and densely arranged magnetic pole arrays.

[0014] Preferably, the top of the runway magnetic pole is covered with an insulating pad, and the bottom is provided with a magnetic conductive sheet for conducting the magnetic field lines between the adjacent permanent magnets with opposite magnetic properties.

[0015] Preferably, the distance between the runway magnetic pole and the surface of the component to be processed is 40-60 mm.

[0016] Preferably, the upper anode plate has a hollow structure, the hollow space is a gas mixing chamber, and the bottom of the upper anode plate has a plurality of distributed holes that communicate with the gas mixing chamber; the top of the gas mixing chamber is connected to an inlet pipe for conveying process gas.

[0017] Preferably, a metal shield is installed around the lower cathode plate, with the top of the metal shield open to expose the area where the components to be processed are placed on the lower cathode plate.

[0018] The present invention also discloses a plasma processing method based on the aforementioned magnetic field-enhanced coupled plasma processing apparatus, comprising the following steps:

[0019] The component to be processed is placed in the capacitively coupled plasma device, and a plasma working area is formed between the upper anode plate and the lower cathode plate by capacitively coupled discharge.

[0020] The runway magnetic pole device applies an additional coupling magnetic field to the plasma working area to form a linear plasma region with a density higher than a set threshold.

[0021] The runway magnetic poles are controlled to move along a plane parallel to the lower cathode plate, and the linear plasma region moves accordingly, modulating the plasma density and distribution to complete the etching of the surface of the component to be processed.

[0022] Preferably, the method further includes the step of adjusting the working gas pressure inside the vacuum chamber according to the selection of the component to be processed.

[0023] As can be seen from the above technical solution, compared with the prior art, the beneficial effects of the present invention include:

[0024] Based on capacitive coupling discharge, this invention applies an additional magnetic field to the bottom of the capacitive coupling discharge electrode (lower cathode plate). This magnetic field can move one-dimensionally along the horizontal direction of the electrode. The presence of the magnetic field can modulate the secondary electrons generated by the plasma discharge, thereby modulating the plasma density and distribution to form a linear high-density plasma region, achieving efficient etching of the workpiece surface. Subsequently, as the magnetic field moves horizontally, the high-density plasma region moves directionally, from line to surface, completing uniform etching of the workpiece surface.

[0025] This invention effectively solves the key technical bottleneck of ultra-precision optical components and innovatively proposes a linear magnetic field coupling enhanced plasma polishing technology. By designing a moving magnetic field drive, the density, distribution and directional drift of the plasma are modulated by multi-field coupling, which greatly improves the actual processing efficiency of difficult-to-process materials such as sapphire, expands the range of processed materials, and makes rapid plasma processing of medium and large aperture optical components possible.

[0026] This invention also helps to solve the temperature effect problem in plasma processing, fundamentally ensuring the determinism and reliability of the plasma removal function, avoiding the factors that may cause deformation of high aspect ratio optical elements during processing, effectively realizing the rapid removal of surface and subsurface damage of the processed workpiece, reducing the surface loss of the element, and improving the element's resistance to laser damage. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of a magnetic field-enhanced coupled plasma processing apparatus provided in one embodiment of the present invention;

[0029] Figure 2 This is a partially enlarged schematic diagram of the connection relationship of the lower cathode plate according to an embodiment of the present invention;

[0030] Figure 3 This is a radio frequency capacitively coupled plasma distribution diagram provided in one embodiment of the present invention;

[0031] Figure 4 This is an enhanced magnetic field coupled plasma distribution diagram provided in one embodiment of the present invention;

[0032] Figure 5 This is a schematic diagram of the runway magnetic pole structure and arrangement provided in one embodiment of the present invention;

[0033] Figure 6 A schematic diagram of an array structure of runway magnetic poles provided in one embodiment of the present invention;

[0034] Figure 7 A schematic diagram of the array structure of runway magnetic poles in the CC direction provided in one embodiment of the present invention;

[0035] Figure 8 A schematic diagram of the BB direction of the array structure of runway magnetic poles provided in one embodiment of the present invention;

[0036] Figure 9 This is a cross-sectional view along the CC direction of an array structure of runway magnetic poles provided in one embodiment of the present invention;

[0037] Figure 10 This is a BB-direction cross-sectional view of an array structure of runway magnetic poles provided in one embodiment of the present invention. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] like Figure 1 As shown, the first aspect of the present invention provides a magnetic field enhanced coupled plasma processing apparatus, which can be used to process semiconductor materials, optical components, etc.; it includes: a capacitively coupled plasma device and a racetrack magnetic pole device; the capacitively coupled plasma device includes a vacuum chamber 4 and an upper anode plate 3 and a lower cathode plate 11 located in the vacuum chamber 4, the space between the upper anode plate 3 and the lower cathode plate 11 is a plasma working area 7, a radio frequency power supply is applied to the lower cathode plate 11, and an electric field is formed between the upper anode plate 3 and the lower cathode plate 11; the component to be processed 9 is placed on the upper surface of the lower cathode plate 11; the racetrack magnetic pole device is located in the bottom space of the lower cathode plate 11, including a motion device and a racetrack magnetic pole 13 installed on the motion device, the motion device drives the racetrack magnetic pole 13 to move along a plane parallel to the lower cathode plate 11; the racetrack magnetic pole 13 includes permanent magnets with opposite magnetic properties placed adjacent to each other, forming an arched magnetic field line above the lower cathode plate 11, forming an additional coupled magnetic field that confines the bipolar diffusion motion of electrons in the electric field.

[0040] Without the introduction of an enhancing magnetic field, the distribution of capacitively coupled plasma under radio frequency power supply excitation is as follows: Figure 3 As shown, the distribution of enhanced magnetic field coupled plasma is as follows: Figure 4 As shown, the magnetic agglomeration phenomenon is obvious after the introduction of an additional coupling magnetic field. When only an electric field is present, the particles in the plasma move towards the cathode surface only under the action of the electric field force. During this process, the collision path with gas molecules is short, the probability of collisional ionization between particles is low, and the plasma density is low. The plasma generated by radio frequency excitation exhibits a symmetrical distribution at the geometric center of the discharge region, with a certain distance from the cathode surface. The plasma electron density, electron temperature, and plasma distribution are greatly affected after the plasma is coupled by the magnetic field. The external magnetic field constrains the bipolar diffusion motion of electrons perpendicular to the magnetic field direction, restricting electrons from escaping the magnetic field's binding force. Under the combined action of the electric and magnetic fields throughout the plasma region, active particles generate gyratory motion and drift diffusion on the cathode surface. During the drift diffusion process, the total path length increases, greatly increasing the collisional ionization of particles, resulting in an increase in plasma density above the etched area, a contraction of the distribution towards the center, and a decrease in the voltage of the plasma sheath.

[0041] Furthermore, the magnetic field confines electrons to the cathode surface, reducing electron loss in the discharge region. These electrons also attract reactive ions to the cathode surface, increasing the chemical reaction rate. The electrons attracted to the surface enhance the electric field in the plasma, which in turn increases the ohmic heating process. The enhanced cascade collisions of electrons caused by the magnetic field itself also lead to enhanced random heating, resulting in more high-energy electrons on the cathode surface. This increases the collision rate between electrons and gas molecules, enhances gas ionization, and leads to a more uniform plasma distribution on the cathode surface. Simultaneously, the reduced contact area between the plasma and the processed surface concentrates energy, reducing plasma-surface bombardment and enhancing chemical reactions, thus increasing processing efficiency and improving processing quality. Compared to existing magnetron sputtering discharge methods, plasma requires significantly less power to achieve the same ion flux, saving processing costs.

[0042] In this embodiment, the capacitively coupled plasma device generates plasma through capacitively coupled discharge. Capacitively coupled discharge is easily implemented in a vacuum environment and uses a 13.56MHz radio frequency power supply with a power output of 1–2KW, offering significant cost advantages. The runway magnetic pole device achieves magnetic field coupling modulation. The plasma density can be adjusted by regulating the working gas pressure according to different processing components, thus providing a wide operating range and allowing the working vacuum degree to be adjusted within the range of 1–1000Pa.

[0043] It should be noted that this embodiment uses radio frequency capacitively coupled plasma generation technology. Radio frequency capacitive coupling is a way to couple input power into discharge. It uses two electrodes and their sheath to form a capacitor, which makes it easier to discharge and generate large-area high-density active plasma.

[0044] In one embodiment, the capacitively coupled plasma device adopts a single-frequency drive mode, the discharge frequency of the radio frequency power supply is 13.56MHz, the radio frequency drive voltage is between 100 and 1000V, the radio frequency power is adjustable between 100 and 2000W, and plasma can be generated by discharge at a pressure between 2Pa and 1000Pa.

[0045] The radio frequency (RF) power supply consists of an RF signal generator and a matching network. This ion source primarily generates ions by applying RF voltage (or current) to two electrodes (upper anode plate 3 and lower cathode plate 11) through an external matching network for discharge. The matching network ensures that the RF generator and the vacuum chamber 4 achieve precise conjugate impedance matching automatically. The signal output from the RF power supply is connected to the bottom of the lower cathode plate 11 of the vacuum chamber 4 via an RF signal connector 16. The workpiece is placed on the lower cathode electrode, and a DC negative bias voltage can be applied to the lower cathode plate to adjust the energy of the ions bombarding the workpiece surface. When processing hard and brittle components such as sapphire, silicon carbide, and microcrystalline glass, the plasma energy can be increased, causing the ions to accelerate and bombard the surface.

[0046] In one embodiment, the bottom of the vacuum chamber 4 is supported by a bracket. The vacuum chamber 4 includes a top plate and a side plate. A fixing plate is provided at the bottom of the side plate, and a lower cathode plate 11 is fixedly connected to one end of the fixing plate facing the center of the bottom of the vacuum chamber 4. One of the fixing plates is provided with a vacuum pumping pipe interface 8 for connecting a vacuum pumping pipe to the inside of the vacuum chamber 4.

[0047] In this embodiment, the vacuum extraction pipe interface 8 is located at the bottom edge of the circular vacuum chamber 4, and is externally connected to a vacuum unit. To improve the uniformity of airflow, a vertically placed partition 18 is provided around the lower cathode plate 11, and the vacuum extraction pipe interface 8 is located between the partition 18 and the side plate.

[0048] In one embodiment, the motion device includes a guide rail 1, a stepper motor 2, and a slider; the guide rail 1 is mounted parallel to the bottom space of the lower cathode plate 11, one end of the guide rail 1 is connected to the output end of the stepper motor 2, and the track magnetic pole 13 is connected to the guide rail 1 through the slider transmission and moves linearly along the guide rail 1.

[0049] In practice, the upper electrode plate and lower cathode plate 11 are placed horizontally, and the guide rail 1 is a horizontal guide rail 1, which allows the moving magnetic pole to move in a uniform linear motion along the horizontal direction. The stepper motor 2 can drive the magnetic pole to move in a directional and uniform speed; the other end is connected to a programmable logic controller (PLC) to execute the corresponding instruction operation of the PLC signal.

[0050] In one embodiment, the grounded anode of the upper anode plate 3 (and typically the entire wall of the vacuum chamber 4 is also grounded) is a hollow stainless steel disc. The hollow space serves as a mixing chamber, and several distributed holes, resembling a showerhead, are opened below the disc, communicating with the mixing chamber. An inlet pipe 6 for conveying process gas is connected above the disc, leading to the top of the mixing chamber.

[0051] When the equipment is operating, process gases (such as a mixture of fluorine-containing gases, argon, and oxygen) can enter the mixing chamber at the top of the disk through the inlet pipe 6, and then be evenly introduced into the reaction chamber (vacuum chamber 4) through the holes. To ensure etching uniformity, the area of ​​the upper electrode plate must be larger than that of the lower electrode plate. In this embodiment, the diameter of the upper anode plate 3 is set to 450 mm, and the diameter of the lower cathode plate 11 is set to 350 mm.

[0052] In one embodiment, the lower cathode plate 11 is made of copper and is connected to an RF power supply via a ring-shaped copper RF signal connector 16. The lower cathode plate 11 is a hollow disc-shaped body with a circular groove at the top, and the component 9 to be processed is placed above the lower cathode plate 11. A water cooling device 10 is provided in the hollow space of the lower cathode plate 11, and its water inlet pipe is connected to the hollow space through a through hole on one side of the lower cathode plate 11 and flows out from a through hole on the other side of the lower cathode plate 11.

[0053] It should be noted that in this embodiment, magnetic field coupling is used to increase the plasma density of the magnetic field surface area to form a linear "W" etching region. Although the temperature of the etching region will rise due to ion sputtering during the etching process, the etching region will also move with the magnetic field. In this way, the etching region will be fully cooled by this "line to surface" method, supplemented by the water cooling device 10 of the electrode plate, and the temperature rise of the processed workpiece will be greatly suppressed. At the same time, the applied radio frequency energy mainly acts on the plasma region, and the energy consumed on the electrode (including the workpiece placed on the electrode) is very small and will not have a significant impact on the temperature of the workpiece.

[0054] In one embodiment, the distance between the upper anode plate 3 and the lower cathode plate 11 is adjustable. The upper anode plate 3 is connected to the top plate of the vacuum chamber 4 via a linear actuator 5. The air inlet pipe 6 and the grounding wire are also installed together with the linear actuator 5, which allows the longitudinal position of the upper anode plate 3 to be adjusted, thereby changing the distance between the upper and lower electrodes.

[0055] It should be noted that a high-frequency electric field is applied between the electrodes in the plasma working region 7, which is filled with low-pressure gas, causing the gas to ionize and generate plasma. In reactive ion etching, to ensure that the oscillating electrons driven by radio frequency have a sufficiently long distance to collide and excite with neutral particles during discharge, a sufficient distance is required between the upper and lower electrodes. For example, when the gas pressure is 4 Pa, the mean free path of the ionization collision between electrons and neutral particles is approximately 1 cm. Therefore, the minimum distance between the electrodes is related to the gas pressure and is generally at least greater than 10 mm. In this embodiment, to increase process flexibility, a linear actuator 5 is used to adjust the distance between the upper and lower electrodes, with the electrode spacing set to 40 mm to 150 mm.

[0056] The plasma generation method borrows from radio frequency anomalous glow discharge in radio frequency magnetron sputtering coating technology. When the electric field strength increases to a certain value, the gas breaks down, generating a discharge phenomenon. This device can accommodate both magnetron sputtering and plasma etching processes.

[0057] High-frequency discharge requires a lower gas breakdown voltage than direct current discharge. In low-pressure (2–150 Pa) RF discharge, lower pressures are used for etching, and higher pressures are used for deposition. Typically, the plasma density is between 10¹⁵ and 10¹⁷ m³ / s. -3 Between these values, the temperature of electrons is between 1 and 4 eV.

[0058] For etching processes, the working gas pressure is usually low, generally between 1.33 Pa and 13.3 Pa. For example, in the etching of sapphire, the reaction chamber is filled with reactive gases according to a certain working pressure and mixing ratio. For instance, the BCl2 and Cl2 flow rates are 2:1 (Cl2:20 sccm) when filled into the reaction chamber. With the RF power set at 500 W and the vacuum chamber pressure set at 2 Pa, plasma etching is enhanced by one-dimensional moving magnetic field coupling. The effects of different parameters (RF power, pressure, gas flow rate and ratio, electrode spacing, etc.) on the etching rate and uniformity of sapphire are investigated.

[0059] In magnetron sputtering deposition, the target is placed on a copper cathode plate with DC (RF) bias. An inert working gas, such as Ar, with a partial pressure of approximately 0.1–1 Pa (0.1 Pa–0.05 Pa for RF magnetron sputtering) is filled into a vacuum chamber as a carrier for gas discharge. Electrons collide with argon atoms under the influence of the electromagnetic coupling field, ionizing to produce Ar+ ions and new electrons. The Ar+ ions are accelerated by the electric field and fly towards the cathode target, bombarding the target surface with high energy, causing sputtering of the target material. Neutral target atoms or molecules are deposited on the substrate to form a thin film. One-dimensional moving magnetic poles are controlled to investigate the uniformity of the film formation.

[0060] Plasma polishing falls under the category of pure chemical polishing and can produce high-quality optical surfaces, but its processing efficiency is low. To improve the processing efficiency of plasma polishing, an external magnetic field is used for control. The purpose is to confine charged particles within a certain area, increase the probability of collisions between particles, and thus increase the plasma density. This results in an increase in the number of active atoms participating in the chemical reaction, thereby improving the processing efficiency.

[0061] In one embodiment, the magnet material of the runway magnetic pole 13 is neodymium iron boron (NdFeB), and the arrangement and size structure of this reinforcing magnetic pole are as follows: Figure 5 As shown, the runway magnetic pole 13 includes an outer ring rectangular magnet and a long rectangular magnet placed horizontally in the middle of the axis of symmetry of the outer ring rectangular magnet; the top of the outer ring rectangular magnet is the N pole and the bottom is the S pole; the top of the long rectangular magnet is the S pole and the bottom is the N pole.

[0062] In this embodiment, both the outer ring rectangular magnet and the long rectangular magnet are linearly densely arranged magnetic pole arrays, i.e., composed of linearly densely arranged small magnetic poles, thereby constructing a large-size linear magnetoelectric coupling plasma region. There are two specifications for the small magnetic poles: 23 cuboid magnets with dimensions of 20mm, 10mm, and 10mm are horizontally placed on the long sides of both ends of the outer ring rectangular magnet; 4 cuboid magnets with dimensions of 20mm, 15mm, and 10mm are horizontally placed on the wide sides of both ends of the outer ring rectangular magnet; and 20 cuboid magnets with dimensions of 20mm, 15mm, and 10mm are horizontally placed in the middle. These are arranged horizontally to form an outer ring rectangular magnet array 490mm long and 80mm wide, with the N pole facing upwards. A 400mm long rectangular magnet array is horizontally placed in the middle of the axis of symmetry. The outer ring rectangular magnet and the long rectangular magnet also include soft iron at the bottom of the magnetic pole array. The distribution and dimensions of the runway magnetic poles 13 are as follows. Figure 6-10 As shown.

[0063] A linear length of 300 mm is sufficient to ensure that the plasma used for processing large-diameter optical components is in a uniform, stable, and sufficiently strong magnetic field.

[0064] Using permanent magnets instead of electromagnetic excitation to control plasma can effectively simplify the circuitry in the device and reduce the interaction between the plasma and the external electrical excitation, thus providing stability in the control of plasma distribution.

[0065] Permanent magnets with opposite magnetic poles are placed alternately and fixed by a magnetically conductive iron frame, parallel to each other below the lower cathode plate 11, with the horizontal tangent of the magnetic field lines parallel to the cathode plate. The runway magnetic poles 13 are fixed to a horizontal guide rail 1 parallel to the cathode plate and can reciprocate along the guide rail 1 in one-dimensional motion under the drive of a motor. This type of magnetic pole structure generates a Gaussian distribution of magnetic field lines between adjacent poles, producing the maximum magnetic field strength at the pole surface, which decreases with distance from the pole surface. It is generally believed that the confinement and control of the plasma by the magnetic field mainly occurs at the pole surface, thus increasing plasma density while reducing the influence of the magnetic field on the plasma device.

[0066] By controlling the stepper motor 2 via PLC to drive the track magnetic poles 13 to move directionally along the guide rail 1 in a direction orthogonal to the arrangement, the linearly uniformly distributed high-density plasma is guided to drift along the direction of magnetic pole movement, enabling rapid and uniform etching of large-area optical components from lines to surfaces. Multi-dimensional control of plasma using magnetic field, electric field, and one-dimensional motion field as parameters breaks through the limitations of existing plasma polishing technology, increases the control dimension and control margin of plasma, introduces more reliable control methods for plasma processing, and improves the accuracy of plasma density and distribution control. This method of driving plasma directional drift by magnetic field-directed movement solves the defect of existing vacuum plasma technology being limited by electrode size or plasma density requirements, thus preventing etching of medium and large-diameter components and expanding the application scope of vacuum plasma etching technology in the field of optical component manufacturing.

[0067] In one embodiment, the top of the runway magnetic pole 13 is covered with an insulating pad 12 to prevent the magnetic pole from interfering with the radio frequency electric field; the bottom is provided with a magnetic conductive sheet 14 for conducting magnetic field lines between adjacent permanent magnets with opposite magnetic properties.

[0068] In one embodiment, the distance between the surface of the runway magnetic pole 13 and the surface of the component 9 to be processed is 40–60 mm. The magnetic field strength and uniformity can be controlled by parameters such as the magnetic pole material, magnetic pole spacing, magnetic pole height, magnetic yoke, and pole shoe shape. According to the Gaussian meter, the horizontal component of the magnetic field on the surface of the processed component is above 200 GS, which can ensure that the magnetic field effectively binds electrons. The magnetic field and the electric field form an orthogonal coupling field, forming a high-density plasma, which is used to improve the magnetron sputtering efficiency and etching efficiency.

[0069] In one embodiment, such as Figure 2 As shown, a metal shield 17 is installed around the lower cathode plate 11. The top of the metal shield 17 is open, exposing the area where the component 9 to be processed is placed on the lower cathode plate 11. The radio frequency signal connector 16 is located at the bottom of the outer edge of the lower cathode plate 11. The metal shield 17 covers the outer side and top surface of the radio frequency signal connector 16, so that when the sample stage (lower cathode plate 11) is working, the gas glow discharge is concentrated in the area where the component 9 to be processed is placed, avoiding the cathode from being sputtered. This reduces contamination and greatly improves etching efficiency.

[0070] An insulating sealing gasket 15 is placed between the end of the fixed plate of the vacuum chamber 4 and the lower cathode plate 11 to prevent the cathode from contacting the vacuum chamber 4 and affecting the potential.

[0071] A second aspect of the present invention provides a plasma processing method using the magnetic field-enhanced coupled plasma processing apparatus provided in the first aspect, comprising the following steps:

[0072] The component 9 to be processed is placed in the capacitively coupled plasma device, and a plasma working area 7 is formed between the upper anode plate 3 and the lower cathode plate 11 by capacitively coupled discharge.

[0073] The runway magnetic pole device applies an additional coupling magnetic field to the plasma working region 7, forming a linear plasma region with a density higher than a set threshold.

[0074] The runway magnetic pole 13 is controlled to move along a plane parallel to the lower cathode plate 11, and the linear plasma region moves accordingly, modulating the plasma density and distribution to complete the etching of the surface of the component 9 to be processed.

[0075] In this embodiment, the external magnetic field constrains the bipolar diffusion motion of electrons perpendicular to the magnetic field direction, restricting electrons from breaking free from the magnetic field's binding force. Under the combined action of the electric and magnetic fields throughout the plasma region, active particles generate gyratory motion and drift diffusion on the cathode surface. During the drift diffusion process, the total path length increases, greatly increasing the collisional ionization of particles, thereby increasing the plasma density above the etched area and improving the magnetron sputtering efficiency and etching efficiency.

[0076] In one embodiment, the method further includes adjusting the working pressure in the vacuum chamber 4 according to the selection of the component to be processed 9, thereby adjusting the plasma density. In this embodiment, the working vacuum can be adjusted within the range of 1 to 1000 Pa.

[0077] The magnetic field enhanced coupled plasma processing apparatus and method provided by the present invention have been described in detail above. Specific examples have been used in this embodiment to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

[0078] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined in these embodiments may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A magnetic field-enhanced coupled plasma processing apparatus, characterized in that, include: Capacitively coupled plasma device and runway magnetic pole device; among them... The capacitively coupled plasma device includes a vacuum chamber and an upper anode plate and a lower cathode plate located inside the vacuum chamber. The area between the upper anode plate and the lower cathode plate is the plasma working area. A radio frequency power supply is applied to the lower cathode plate to form an electric field between the upper anode plate and the lower cathode plate. The component to be processed is placed on the upper surface of the lower cathode plate; The runway magnetic pole device is located in the bottom space of the lower cathode plate, and includes a motion device and a runway magnetic pole installed on the motion device. The motion device drives the runway magnetic pole to move along a plane parallel to the lower cathode plate. The runway magnetic pole includes permanent magnets with opposite magnetic properties placed adjacent to each other, forming an arched magnetic field line above the lower cathode plate, forming an additional coupled magnetic field that confines the bipolar diffusion motion of electrons in the electric field. The top of the runway magnetic poles is covered with an insulating pad, and the bottom is provided with a magnetic conductive sheet for conducting the magnetic field lines between the adjacent permanent magnets with opposite magnetic properties.

2. The magnetic field-enhanced coupled plasma processing apparatus according to claim 1, characterized in that, The motion device includes a guide rail, a stepper motor, and a slider; the guide rail is mounted parallel to the bottom space of the lower cathode plate, one end of the guide rail is connected to the output end of the stepper motor, and the track magnetic pole is connected to the guide rail through the slider and moves linearly along the guide rail.

3. The magnetic field-enhanced coupled plasma processing apparatus according to claim 1, characterized in that, The runway magnetic poles include an outer ring rectangular magnet and a long rectangular magnet placed horizontally in the middle of the axis of symmetry of the outer ring rectangular magnet; the top of the outer ring rectangular magnet is the N pole and the bottom is the S pole; the top of the long rectangular magnet is the S pole and the bottom is the N pole.

4. The magnetic field-enhanced coupled plasma processing apparatus according to claim 3, characterized in that, Both the outer ring rectangular magnet and the long rectangular magnet are linearly and densely arranged magnetic pole arrays.

5. The magnetic field-enhanced coupled plasma processing apparatus according to claim 1, characterized in that, The distance between the runway magnetic pole and the surface of the component to be processed is 40-60 mm.

6. The magnetic field-enhanced coupled plasma processing apparatus according to claim 1, characterized in that, The upper anode plate has a hollow structure, and the hollow space is a gas mixing chamber. The bottom of the upper anode plate has several holes arranged in a distributed manner, and the holes are connected to the gas mixing chamber. The top of the gas mixing chamber is connected to an inlet pipe for conveying process gas.

7. The magnetic field-enhanced coupled plasma processing apparatus according to claim 1, characterized in that, A metal shield is installed around the lower cathode plate, with the top of the metal shield open, exposing the area where the components to be processed are placed on the lower cathode plate.

8. A plasma processing method using a magnetic field-enhanced coupled plasma processing apparatus according to any one of claims 1-7, characterized in that, Includes the following steps: The component to be processed is placed in the capacitively coupled plasma device, and a plasma working area is formed between the upper anode plate and the lower cathode plate by capacitively coupled discharge. The runway magnetic pole device applies an additional coupling magnetic field to the plasma working area to form a linear plasma region with a density higher than a set threshold. The runway magnetic poles are controlled to move along a plane parallel to the lower cathode plate, and the linear plasma region moves accordingly, modulating the plasma density and distribution to complete the etching of the surface of the component to be processed.

9. The plasma processing method according to claim 8, characterized in that, It also includes the step of adjusting the working gas pressure inside the vacuum chamber according to the selection of the component to be processed.

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