A method for coating a surface of a sphere using electromagnetic field interaction

Abstract

This invention discloses a method for coating a sphere surface using electromagnetic field interaction. The method specifically includes: S1. Rotatably arranging multiple substrates in a coating chamber, with the substrates surrounded by multiple excitation coils uniformly arranged on the sidewalls of the chamber; S2. Evacuating the chamber and applying a high-pulse negative bias voltage to a rotating frame supporting and rotating the substrates; S3. Introducing a film-forming material into the coating chamber through a film-forming material release source, where it ionizes under the high-pulse negative bias voltage; S4. Turning on the excitation power supply to the excitation coils and controlling the strength and direction of the excitation magnetic field by controlling the analog input of the excitation power supply, thereby guiding the ionized ions of the film-forming material to circulate within and outside the aggregation area to achieve uniform deposition on the substrate. The rotating fixture provided by this invention for uniformly coating a sphere surface has a very small coating area, high fixture stability, high yield, and good coating uniformity.

Description

Technical Field

[0001] This invention belongs to the field of vacuum coating equipment technology, and specifically relates to a method for coating a sphere surface using electromagnetic field interaction. Background Technology

[0002] In the die-casting process, cryogenic molding glass (400-600°C) and traditional high-temperature molding glass (>700°C) have different characteristics in the application of optical lens manufacturing. Cryogenic molding technology has become an important development direction in the optical industry in recent years, and is particularly suitable for high-precision applications such as AR / VR, smartphone lenses, automotive optics, and micro-optical components.

[0003] On the one hand, low-temperature glass has a high viscosity and poor melt flow, which may lead to surface defects, bubbles, and unfilled areas. Furthermore, uneven shrinkage during cooling may generate residual stress, causing the lens to crack or break at the edges. Secondly, adhesion between the glass and the mold surface can also cause breakage and other problems, resulting in low yield and increased production costs. On the other hand, in the production of spherical vacuum coating, to improve coating uniformity and maximum loading capacity, the fixture needs to move and rotate at a constant speed within the vacuum chamber. Existing fixtures, for the sake of increasing clamping stability, typically increase the clamping area on the sphere surface, leading to an increase in the uncoated area and problems such as uneven coating thickness and large fixture shading points. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a method for coating a sphere surface using electromagnetic field interaction, resulting in a very small coating area, high fixture stability, high yield, and good coating uniformity.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for depositing a film on the surface of a sphere using electromagnetic field interaction, used to simultaneously form film layers on the surfaces of multiple substrates, characterized by comprising the following steps: S1. A plurality of said substrates are rotatably arranged in a coating cavity of a chamber body, and the plurality of said substrates are surrounded by a plurality of excitation coils uniformly arranged on the side wall of the chamber body; S2. Evacuate the vacuum and apply a high-pulse negative bias voltage to the rotating frame that supports and drives the substrate to rotate; S3. The film-forming material is introduced into the coating chamber through the film-forming material release source and ionized into ions under the action of high pulse negative bias voltage; S4. Turn on the excitation power supply of the excitation coil, and control the change in the strength and direction of the excitation magnetic field by controlling the analog input of the excitation power supply, so as to guide the ion aggregation area after the film forming material is ionized to circulate and move inside and outside to achieve uniform deposition on the substrate.

[0006] Furthermore, in S1, the plurality of substrates rotate 360° within the coating cavity while maintaining their own view state.

[0007] Furthermore, in S4, the vertical distance between the plurality of excitation coils and the rotating frame is the same, and the plurality of excitation coils are arranged opposite each other in pairs. The plurality of excitation coils are powered by the same excitation power supply and are connected in series.

[0008] Furthermore, in S4, a waveform change control signal is provided through a waveform generator or through a PLC analog output module to control the output current change of the excitation power supply.

[0009] Furthermore, in S4, the waveform of the output current of the excitation power supply is one of the following: sine wave, triangle wave, sawtooth wave, and rectangular wave.

[0010] The coating equipment for implementing the spherical coating method of the present invention includes a chamber, a film-forming material release source, a plurality of excitation coils evenly distributed in a ring on the side wall of the chamber, and a rotating frame disposed in the coating cavity of the chamber. The film-forming material release source is connected to the coating cavity to introduce the film-forming material into the coating cavity. The plurality of excitation coils are connected to an excitation power supply, and the rotating frame is connected to a high-pulse negative bias power supply to ionize the film-forming material into ions.

[0011] Furthermore, the rotating frame includes a rotating component and multiple clamping disks. The rotating component can be driven to rotate. The multiple clamping disks are evenly distributed in a circle around the central axis of the rotating component, and the multiple clamping disks are all horizontally arranged. The two outer ends of each clamping disk that are arranged opposite to each other are connected to the rotating component. When the rotating component rotates, each clamping disk remains horizontal and revolves around the central axis of the rotating component.

[0012] Furthermore, the rotating assembly includes a guide assembly and a rotating assembly. Multiple clamping discs are disposed on the rotating assembly. The guide assembly includes a guide wheel and multiple guide rods. The guide wheel is located on one side of the rotating assembly's central axis along its length and is horizontally eccentrically positioned relative to the rotating assembly. Multiple guide rods are horizontally distributed along the circumferential sides of the guide wheel. The length direction of each guide rod is perpendicular to the central axis of the guide wheel. Each guide rod corresponds one-to-one with a multiple clamping disc. The two ends of each guide rod are rotatably connected to the guide wheel and the adjacent side of the rotating assembly and the guide wheel, respectively. The end of each clamping disc near the guide wheel is fixedly connected to the end of a guide rod near the rotating assembly along its length. Each guide rod remains horizontal and revolves around the central axis of the guide wheel.

[0013] Furthermore, a first connecting rod and a second connecting rod, parallel to the central axis of the guide wheel, are respectively provided perpendicularly on different sides at both ends of the guide rod along its length. The second connecting rod located between the guide wheel and the guide rod is fixedly connected to the guide wheel and rotatably connected to the guide rod. The second connecting rod located between the guide rod and the rotating assembly is fixedly connected to the guide rod and rotatably connected to the rotating assembly. The end of the first connecting rod is fixedly connected to the clamping disc.

[0014] Furthermore, the rotating assembly includes a drive wheel and a driving wheel arranged coaxially at intervals, and a driving shaft is coaxially connected between the drive wheel and the driving wheel. The driving shaft drives the drive wheel and the driving wheel to rotate. A plurality of clamping discs are disposed between the drive wheel and the driving wheel, and one end of the clamping disc is rotatably connected to the drive wheel. The connecting rod passes through the driving wheel and is rotatably connected to it.

[0015] Furthermore, the guide wheel is either disc-shaped or large annular, and multiple ear plates are evenly distributed on the outer periphery of the disc-shaped or large annular wheel, with the connecting rod fixedly connected to the ear plates.

[0016] Furthermore, the driving wheel and the drive wheel are separate rings or rings with radial rods evenly distributed on the outer circumferential sidewalls of the rings, and one end of the clamping disc and the connecting rod are rotatably connected to the body of the ring or the radial rods.

[0017] Furthermore, the connecting rod connecting the guide wheel, the drive wheel, and the clamping disk has square prism structures on both sides for non-rotational connection with the guide wheel and the clamping disk, and the middle part of the connecting rod is a cylindrical structure that is rotatably connected to the drive wheel through a bearing.

[0018] Furthermore, the clamping disc includes a frame, within which are provided a plurality of horizontal plates, each of which is provided with a plurality of spherical holes arranged in a matrix.

[0019] Furthermore, a locking point is provided on the inner sidewall of each of the spherical holes.

[0020] Using the method of this invention, the uniformity of PECVD DLC coating on curved surfaces is controlled by changing the magnetic field: (1) The electric field formed by the high negative bias during the coating process ionizes the hydrocarbon process gas, and the magnetic field formed by the excitation coil guides the hydrocarbon ion aggregation area to circulate and move, and they are coupled to achieve a uniform and delicate DLC coating. (2) The four excitation coils are connected in positive and negative directions to form a closed magnetic field; the four excitation coils are connected in series with one power supply to ensure the synchronicity of magnetic field changes; (3) This excitation power supply uses a waveform generator as the control analog input; considering that PLC is inexpensive, easy to integrate, and has flexible waveform changes, the PLC analog output module is used as the control analog input of the excitation power supply. Compared with PLC, there are some waveform generators (essentially simple microcontrollers), but the disadvantage is that several waveforms are fixed, and the human-machine interface and system integration are also more difficult; (4) The PLC provides a control signal with a waveform change to control the output current of the excitation power supply to change, thereby controlling the strength and direction of the magnetic field of the excitation coil.

[0021] (5) Changes in the strength and direction of the excitation magnetic field will guide the internal and external circulation of hydrocarbon ion aggregation areas, making the deposition of DLC on the workpiece more uniform.

[0022] In addition, the drive wheel in the rotary fixture for coating the surface of a sphere in this invention is connected to the guide wheel and the fixture disk respectively through the guide rod, which can ensure that the fixture remains horizontal during the movement of the rotating frame. The fixture disk is provided with a horizontal plate with holes. Each hole has a raised locking point on its side wall, which can ensure that the sphere on the horizontal plate will not fall off. It has the advantages of high coating stability, high yield, and good uniformity. Attached Figure Description

[0023] Figure 1 This is a three-dimensional structural schematic diagram of the rotating fixture for coating the surface of a sphere as described in this invention.

[0024] Figure 2 This is a side view of the rotating fixture for coating the surface of a sphere as described in this invention.

[0025] Figure 3 This is a schematic diagram of the connection structure of the clamping disk described in this invention.

[0026] Figure 4 This is a schematic diagram of the structure of the directional rod described in this invention.

[0027] Figure 5 This is a schematic diagram of the structure of the first connecting rod described in this invention.

[0028] Figure 6 This is a schematic diagram of the structure of the clamping disk described in this invention.

[0029] Figure 7 This is a schematic diagram of the coating apparatus described in this invention.

[0030] Among them, 1-guide wheel, 2-guide rod, 3-first connecting rod, 4-drive wheel, 5-drive wheel, 6-drive shaft, 7-ear plate, 8-radial rod, 9-frame, 10-horizontal plate, 11-second connecting rod, 12-bearing, 101-ball hole, 102-clamping point. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0032] like Figures 1-7 As shown, the coating equipment used in the method of coating a sphere surface by electromagnetic field interaction of the present invention includes a chamber, a film forming material release source, multiple excitation coils evenly distributed in a ring on the side wall of the chamber, and a rotating frame disposed in the coating chamber of the chamber. The film forming material release source is connected to the coating chamber to introduce the film forming material into the coating chamber. The multiple excitation coils are connected to an excitation power supply, and the rotating frame is connected to a high-pulse negative bias power supply to ionize the film forming material into ions.

[0033] Specifically, the rotating frame includes a guide assembly and a rotating assembly. Multiple clamping discs are mounted on the rotating assembly. The guide assembly includes a guide wheel 1 and multiple guide rods 2. The guide wheel 1 is located on one side of the rotating assembly's central axis along its length and is horizontally eccentrically positioned relative to the rotating assembly. Multiple guide rods 2 are horizontally distributed along the circumferential sides of the guide wheel 1. The length direction of each guide rod 2 is perpendicular to the central axis of the guide wheel 1. Each guide rod 2 corresponds one-to-one with a multiple clamping disc. The two ends of each guide rod 2 are rotatably connected to the guide wheel 1 and the adjacent side of the rotating assembly to the guide wheel 1, respectively. The end of each clamping disc near the guide wheel 1 is fixedly connected to the end of one guide rod 2 near the rotating assembly along its length. Each guide rod 2 remains horizontal and revolves around the central axis of the guide wheel 1.

[0034] In some embodiments, the guide rod 2 is a flat rod-shaped structure, for example, a rectangular or elliptical plate. A first connecting rod 3 and a second connecting rod 11, parallel to the central axis of the guide wheel 1, are respectively provided perpendicularly on different sides at both ends of the guide rod 2 along its length. The second connecting rod 10, located between the guide wheel 1 and the guide rod 2, is fixedly connected to the guide wheel 1 and rotatably connected to the guide rod 2. The second connecting rod 3, located between the guide rod 2 and the rotating assembly, is fixedly connected to the guide rod 2 and rotatably connected to the rotating assembly, and the end of the first connecting rod 3 is fixedly connected to the clamping disc.

[0035] In some embodiments, the rotating assembly includes a drive wheel 4 and a driving wheel 5 coaxially spaced apart, with a driving shaft 6 coaxially connected between the drive wheel 4 and the driving wheel 5. The driving shaft 6 drives the drive wheel 4 and the driving wheel 5 to rotate. A plurality of clamping discs are disposed between the drive wheel 4 and the driving wheel 5, with one end of each clamping disc rotatably connected to the drive wheel 4. The connecting rod 3 passes through the driving wheel 5 and is rotatably connected to it.

[0036] In order to keep the clamping disk in the present invention horizontal during the movement of the rotating assembly, in some embodiments, the two sides of the square prism structure 31 of the first connecting rod 3 connecting the guide wheel 1, the drive wheel 5 and the clamping disk are non-rotatably connected to the guide wheel 1 and the clamping disk. The middle part of the connecting rod 3 is a cylindrical structure 32, which is rotatably connected to the drive wheel 5 through a bearing.

[0037] In some embodiments, the guide wheel 1 is either disc-shaped or large annular, and multiple ear plates 7 are evenly distributed on the outer periphery of the disc-shaped or large annular shape, and the second connecting rod 10 is fixedly connected to the ear plates 7.

[0038] Furthermore, the driving wheel 4 and the drive wheel 5 are separate rings or rings with radial rods 8 evenly distributed on the outer circumferential sidewall of the ring. One end of the clamping disc and the first connecting rod 3 are rotatably connected to the body of the ring or the radial rods 8.

[0039] Furthermore, the clamping disc includes a frame 9, the two ends of which are rotatably connected to the drive wheel 4 and fixedly connected to the first connecting rod 3, respectively. A plurality of horizontal plates 10 are provided within the frame 9, and each horizontal plate 10 is provided with a plurality of spherical holes 101 arranged in a matrix.

[0040] To ensure that the spheres do not fall off during the coating process, a locking point 102 is provided on the inner sidewall of each sphere hole 101.

[0041] Accordingly, after placing the coated sphere in the above-mentioned coating apparatus, the coating is deposited on the substrate using the method of the present invention, which employs electromagnetic field interaction to coat the surface of the sphere. The method includes the following steps: S1. A plurality of said substrates are rotatably arranged in a coating cavity of a chamber body and surrounded by a plurality of excitation coils uniformly arranged on the side wall of the chamber body; S2. Evacuate a vacuum and connect the rotating frame that supports and drives the substrate to rotate to a high-pulse negative bias voltage through a rotary vacuum power connector; S3. The film forming material release source is introduced into the coating chamber through the process gas pipeline set on the side wall of the chamber body. The film forming material is ionized into ions under the action of high pulse negative bias voltage. The film forming material here is hydrocarbon process gas with a gas flow rate of 10~100 sccm. S4. Turn on the excitation power supply of the excitation coil, and control the change in the strength and direction of the excitation magnetic field by controlling the analog input of the excitation power supply, so as to guide the ion aggregation area after the film forming material is ionized to circulate and move inside and outside to achieve uniform deposition on the substrate.

[0042] In some embodiments, the substrate is disc-shaped, ellipsoidal, rugby ball-shaped, columnar, or spherical. When the diameter of the sphere is 3-50mm, it is easy to attach a 5x5mm silicon wafer at different positions on the sphere. This silicon wafer is used to measure the film thickness. Specifically, it is difficult to measure the thickness directly on the sphere. Marks are made on a small 6x6mm silicon wafer with an oil-based pen, the wafer is attached for film deposition, and after deposition, the wafer is removed. The marks can be washed off with alcohol, and the film thickness can be easily and accurately measured using a profilometer on the silicon wafer.

[0043] Step S1 further includes securing the plurality of spheres onto the fixture disk; the plurality of spheres are relatively stationary with respect to the fixture disk, and the spheres and the fixture disk rotate 360° within the coating cavity while maintaining their own view state.

[0044] The rotating frame can be placed only inside the coating cavity, or the non-rotating side of the rotating frame can be fixedly connected to the cavity body.

[0045] like Figure 7 As shown, the vertical distance between the multiple excitation coils and the rotating frame is the same, and the multiple excitation coils are arranged opposite each other in pairs; in order to ensure the synchronicity of the magnetic field change, the multiple excitation coils are powered by the same excitation power supply and connected in series.

[0046] In step S4, a waveform change control signal can be provided through a waveform generator or a PLC analog output module to control the output current of the excitation power supply, thereby controlling the strength and direction of the magnetic field of the excitation coil. The change in the strength and direction of the excitation magnetic field guides the hydrocarbon ion aggregation area to circulate and move within and outside, resulting in more uniform DLC deposition on the workpiece. Considering cost factors, a PLC analog output module is generally used as the control analog input for the excitation power supply.

[0047] In this invention, the pulse duty cycle of the high-pulse negative bias voltage is 35-99%, the bias voltage is 400V-1500V, the rotation speed of the rotating frame is 1-6 rpm / min, the gas flow rate is 10-100 sccm, and the film deposition rate is 0.3µm-0.5µm / h. Preferably, Under the conditions of a high-pulse negative bias voltage with a pulse duty cycle of 50-80%, a vacuum degree of 0.4Pa-0.7Pa, a voltage of 600V-800V, a rotating frame speed of 1-5rpm / min, and a gas flow rate of 30-50sccm, the film deposition rate is 0.3µm-0.5µm / h, and the resulting film thickness is 1-3µm.

[0048] The waveform of the output current of the excitation power supply is one of sine wave, triangular wave, sawtooth wave, and rectangular wave. For example, in one embodiment, for a sphere with a fixed diameter of 45mm, under the same voltage bias, duty cycle, turntable speed, gas flow rate, vacuum degree and coating deposition rate, coating is performed under different waveforms of excitation power supply output current. The coating thickness variation is shown in Table 1.

[0049] Table 1 As can be seen from the comparative experiments, the order of uniformity from best to worst is sine wave, triangle wave, sawtooth wave, and rectangular wave.

[0050] Within the range of experimental parameters mentioned above, the magnetic field and rotating frame were changed, and the resulting changes in film thickness are shown in Table 2. The results show that the combination of alternating magnetic field and rotating frame can significantly improve the uniformity of the coated film.

[0051] Table 2 Those skilled in the art should understand that the above description is merely a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for depositing a film on the surface of a sphere using electromagnetic field interaction, used to simultaneously form film layers on the surfaces of multiple substrates, characterized in that, Includes the following steps: S1. A plurality of said substrates are rotatably arranged in a coating cavity of a chamber body, and the plurality of said substrates are surrounded by a plurality of excitation coils uniformly arranged on the side wall of the chamber body; S2. Evacuate the vacuum and apply a high-pulse negative bias voltage to the rotating frame that supports and drives the substrate to rotate; S3. The film-forming material is introduced into the coating chamber through the film-forming material release source and ionized into ions under the action of high pulse negative bias voltage; S4. Turn on the excitation power supply of the excitation coil, and control the change in the strength and direction of the excitation magnetic field by controlling the analog input of the excitation power supply, so as to guide the ion aggregation area after the film forming material is ionized to circulate and move inside and outside to achieve uniform deposition on the substrate.

2. The method for coating a sphere surface using electromagnetic field interaction as described in claim 1, characterized in that, In S1, the multiple substrates rotate 360° within the coating cavity while maintaining their own view state.

3. The method for coating a sphere surface using electromagnetic field interaction as described in claim 1, characterized in that, In S4, the vertical distance between the plurality of excitation coils and the rotating frame is the same, and the plurality of excitation coils are arranged opposite each other in pairs. The plurality of excitation coils are powered by the same excitation power supply and are connected in series.

4. The method for coating a sphere surface using electromagnetic field interaction as described in claim 3, characterized in that, In S4, a waveform change control signal is given through a waveform generator or through a PLC analog output module to control the output current change of the excitation power supply; The waveform of the output current of the excitation power supply is one of the following: sine wave, triangle wave, sawtooth wave, and square wave.

5. The method for coating a sphere surface using electromagnetic field interaction according to claim 4, characterized in that, The spherical coating method employs a coating equipment comprising a chamber, a film-forming material release source, multiple excitation coils evenly distributed in a ring on the sidewall of the chamber, and a rotating frame disposed in the coating chamber within the chamber. The film-forming material release source is connected to the coating chamber to introduce the film-forming material into the coating chamber. The multiple excitation coils are connected to an excitation power supply, and the rotating frame is connected to a high-pulse negative bias power supply to ionize the film-forming material into ions.

6. The method for coating a sphere surface using electromagnetic field interaction according to claim 5, characterized in that, The non-rotating side of the rotating frame is connected to the chamber body. The rotating frame includes a rotating assembly and multiple clamping disks. The rotating assembly can be driven to rotate. The multiple clamping disks are evenly distributed in a circle around the central axis of the rotating assembly, and the multiple clamping disks are all horizontally arranged. The two outer ends of each clamping disk that are arranged opposite to each other are connected to the rotating assembly. When the rotating assembly rotates, each clamping disk remains horizontal and revolves around the central axis of the rotating assembly; multiple substrates are clamped on the multiple clamping disks.

7. The method for coating a sphere surface using electromagnetic field interaction according to claim 6, characterized in that, The rotating assembly includes a guide assembly and a rotating assembly. Multiple clamping discs are mounted on the rotating assembly. The guide assembly includes a guide wheel and multiple guide rods. The guide wheel is located on one side of the rotating assembly's central axis along its length and is horizontally eccentrically positioned relative to the rotating assembly. Multiple guide rods are horizontally distributed along the circumferential sides of the guide wheel. The length direction of each guide rod is perpendicular to the central axis of the guide wheel. Each guide rod corresponds one-to-one with a multiple clamping disc. The two ends of each guide rod are rotatably connected to the guide wheel and the adjacent side of the rotating assembly and the guide wheel, respectively. The end of each clamping disc near the guide wheel is fixedly connected to the end of a guide rod near the rotating assembly along its length. Each guide rod remains horizontal and revolves around the central axis of the guide wheel.

8. The method for coating a sphere surface using electromagnetic field interaction according to claim 7, characterized in that, A first connecting rod and a second connecting rod, parallel to the central axis of the guide wheel, are respectively provided on different sides at both ends of the guide rod along its length. The second connecting rod located between the guide wheel and the guide rod is fixedly connected to the guide wheel and rotatably connected to the guide rod. The second connecting rod located between the guide rod and the rotating assembly is fixedly connected to the guide rod and rotatably connected to the rotating assembly. The end of the first connecting rod is fixedly connected to the clamping disc.

9. The method for coating a sphere surface using electromagnetic field interaction according to claim 8, characterized in that, The rotating assembly includes a drive wheel and a driving wheel arranged coaxially at intervals. A driving shaft is coaxially connected between the drive wheel and the driving wheel. The driving shaft drives the drive wheel and the driving wheel to rotate. A plurality of clamping discs are disposed between the drive wheel and the driving wheel. One end of each clamping disc is rotatably connected to the drive wheel. A connecting rod passes through the driving wheel and is rotatably connected to it.

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