Planar Radio Frequency Inductive Coupling Discharge Plasma Enhanced Getter Device

Abstract

The present invention relates to a planar radio-frequency inductively coupled discharge plasma enhanced getter device. A hollow cylinder with holes on the wall is provided in a vacuum chamber. The upper end of the hollow cylinder with holes on the wall is sealed, the lower end is open and is hermetically connected to the bottom end of the vacuum chamber. An electric heating element is provided in the hollow cylinder with holes on the wall, and the lower end of the electric heating element extends out of the vacuum chamber through the lower end opening of the hollow cylinder with holes on the wall and is connected to an external power supply. A planar annular radio-frequency coupling coil is provided in the vacuum chamber, and the radio-frequency coupling coil is located above the hollow cylinder with holes on the wall. A radio-frequency power supply system is provided outside the vacuum chamber, and the radio-frequency coupling coil is connected to the radio-frequency power supply system through a circuit. A vacuum pumping system and a gas pressure acquisition system are respectively provided on both sides of the bottom end of the vacuum chamber. The present invention effectively makes up for the disadvantage of the long activation time of large-volume getters in pure heating through the heating and radio-frequency electromagnetic field coupling method, and the plasma generated by the radio-frequency discharge can improve and enhance the gas absorption rate of the getter.

Description

Technical Field

[0001] The present invention relates to the technical field of vacuum adsorption, and more particularly to a planar radio frequency inductively coupled discharge plasma enhanced getter device. Background Art

[0002] Industrial applications and basic scientific research in many fields currently need to be carried out in a vacuum environment, such as coating, heat treatment, microelectromechanical systems, surface science, atomic physics, nanotechnology, and semiconductor industry. For vacuum technology, the internal vacuum environment and the magnitude of the vacuum degree directly affect the working range and efficiency. Especially after entering the 21st century, with the continuous improvement of various application indicators and the in-depth study of basic disciplines, the operating and research environments require high vacuum or even ultra-high vacuum to varying degrees to maintain. This also poses higher requirements and challenges for the process of vacuum packaging and the means of obtaining the subsequent vacuum environment. Therefore, in addition to using conventional vacuum acquisition means, such as mechanical pumps, molecular pumps, cryopumps and other technologies, vacuum adsorption technology developed based on getter materials has gradually attracted attention and shown a more important role.

[0003] Non-Evaporable Getter (NEG) has been applied in scientific research and industrial production such as electro-vacuum devices, ultra-high vacuum acquisition, and atomic energy industry due to its characteristics of low equilibrium pressure, large gas absorption capacity, and high gas absorption rate. Generally speaking, currently, this type of getter material needs to be heat-treated before it can work, and then the getter has the gas absorption function. This process is called the activation process of the getter. The traditional process of activating the getter generally uses an electric heating wire or an electric heating rod for heating, and the getter is activated at high temperature and starts to absorb gas.

[0004] However, although NEG has unique advantages in the application of high-vacuum and ultra-high-vacuum devices and has been widely used, with the acceleration of China's industrialization process in the new century, the limitations of this type of gas absorption method have gradually emerged: ① Industrial devices are no longer limited to small vacuum devices (such as the adsorption system of chemical lasers), and often need to be scaled up. When obtaining high vacuum for large devices, it is still necessary to use getter for adsorption treatment on the basis of conventional acquisition means. In this case, the amount of getter often needs to be increased, that is, a large volume of getter may be required to achieve the high-vacuum effect of large devices. How to ensure the encapsulation and gas absorption of large-volume getter is a technical problem; ② When activating the getter by heating, its electro-thermal conversion efficiency is relatively low. Usually, it takes some time for the getter to be activated and then absorb gas to achieve the purpose of obtaining higher vacuum. Especially for the getter material in large volume in the scaled-up industrial device, it may take a longer time to be activated, which not only requires long-term stable and continuous injection of energy, but also has a low applicability in some flexible, fast-activation gas absorption occasions; ③ The getter has selectivity in the absorption of some gases. According to the type of gas, the gas absorption rate will be greatly affected. At the same time, there are quite large differences in the activation temperature and time of the getter. For some gases that are difficult to absorb, such as nitrogen, it often requires a high temperature of several hundred degrees Celsius to activate the getter, and the gas absorption rate after activation is slow. How to effectively improve the gas absorption rate of quantitative getter for gases that are difficult to adsorb is very important.

[0005] The existence of these problems sometimes limits the comprehensive application function of the getter. It is very important to find a device that adapts to the current application requirements of large-volume getter and improves the activation time and gas absorption rate. Summary of the Invention

[0006] The purpose of the present invention is to provide a planar radio-frequency inductively coupled discharge plasma enhanced getter device, which can effectively make up for the disadvantage of long activation time of large-volume getter in the pure heating method by means of heating and radio-frequency electromagnetic field coupling, and the plasma generated by radio-frequency discharge can increase the number of active particles accordingly, improving the disadvantage of slow gas absorption rate of the getter for some gases that are difficult to adsorb, so as to further accelerate the gas absorption rate of the system.

[0007] The purpose of the present invention is achieved by the following technical solutions:

[0008] A planar radio-frequency inductively coupled discharge plasma enhanced getter device, comprising a gas supply system, a diffuser and a vacuum chamber connected in sequence, wherein a hollow cylinder with holes on the wall is arranged in the vacuum chamber, and the upper end of the hollow cylinder with holes on the wall is sealed, the lower end is open, and the outer wall is hermetically connected to the bottom end of the vacuum chamber. An electric heating element is arranged in the hollow cylinder with holes on the wall, and the lower end of the electric heating element extends out of the lower opening of the hollow cylinder with holes on the wall to the outside of the vacuum chamber and is connected to an external power supply. A planar ring-shaped radio-frequency coupling coil is arranged in the vacuum chamber, and the radio-frequency coupling coil is located above the hollow cylinder with holes on the wall. A radio-frequency power supply system is arranged outside the vacuum chamber, and the radio-frequency coupling coil is connected to the radio-frequency power supply system through a circuit. A vacuum pumping system is arranged on one side of the bottom end of the vacuum chamber, and a gas pressure acquisition system is arranged on the other side.

[0009] The bottom end of the vacuum chamber is provided with a bottom sealing flange upper cover and a bottom sealing flange lower cover stacked together, and the lower end of the hollow cylinder with holes on the wall passes through the bottom sealing flange upper cover and is fixedly connected to the bottom sealing flange lower cover. The bottom sealing flange lower cover is grounded, and a through interface for inserting the power supply heating element into the corresponding hollow cylinder with holes on the wall is arranged on the bottom sealing flange lower cover.

[0010] The upper end of the hollow cylinder with holes on the wall is provided with a detachable threaded cover.

[0011] The top end of the vacuum chamber is provided with a top sealing flange, and the lower end of the diffuser is provided with a diffuser lower flange connected to the top sealing flange.

[0012] The diffuser is a hollow metal cylinder with a thin upper end and a thick lower end.

[0013] The gas supply system includes a gas supply source, a mass flow meter and a diffuser connector. The gas supply source is connected to the diffuser connector through a gas supply pipeline, and the mass flow meter is arranged on the gas supply pipeline. A connector flange is arranged at the lower end of the diffuser connector, and a diffuser upper flange is arranged at the upper end of the diffuser. The connector flange is fixedly connected to the diffuser upper flange.

[0014] The diffuser connector is a hollow metal cylinder with a thin upper end and a thick lower end.

[0015] The vacuum pumping system includes a vacuum pump and a control valve. The vacuum pump is connected to a corresponding interface on the vacuum chamber through a connecting pipeline, and the control valve is arranged on the connecting pipeline. The gas pressure acquisition system includes a vacuum gauge, a vacuum gauge display, a digital information acquisition card and a computer connected in series in sequence.

[0016] The radio frequency coupling coil is a planar ring-shaped metal coil, and the metal coil is in a spiral tube structure along the circumferential direction of the ring. An insulating seal seat is provided on the side wall of the vacuum cavity, and the lower end of the radio frequency coupling coil is fixedly installed on the insulating seal seat. The radio frequency power supply system includes a radio frequency power supply and a matcher connected in series in sequence, and the matcher is respectively connected to both ends of the lower side of the radio frequency coupling coil through different coaxial transmission lines. Both coaxial transmission lines pass through the insulating seal seat, and one of the coaxial transmission lines is connected to the ground wire.

[0017] The vacuum pumping system first pumps out the gas in the vacuum cavity, then the getter in the hollow cylinder with holes on the wall is activated by heating through the electric heating element, and then the radio frequency power supply system is started to make the output power act on the vacuum cavity through the radio frequency coupling coil, and plasma is generated in the vacuum cavity.

[0018] The advantages and positive effects of the present invention are as follows:

[0019] 1. The present invention enables the output power of the radio frequency power supply system to act on the vacuum cavity through the planar ring-shaped radio frequency coupling coil, generates a radio frequency electric field inside the radio frequency coupling coil and forms inductive coupling discharge, so as to generate plasma inside the vacuum cavity, thereby effectively making up for the disadvantage of the long activation time of the large-volume getter in the pure heating method by means of heating and radio frequency electromagnetic field coupling.

[0020] 2. The plasma generated by radio frequency discharge in the present invention can increase the number of active particles accordingly, improve the disadvantage of the slow gas absorption rate of the getter for some gases that are difficult to adsorb, and thus further accelerate the gas absorption rate of the system.

[0021] 3. The present invention can fully meet the application requirements of some large devices that require large-volume getters. Description of the Drawings

[0022] Figure 1 It is a schematic structural diagram of the present invention.

[0023] Among them, 1 - vacuum cavity; 2 - upper cover of bottom sealing flange; 3 - lower cover of bottom sealing flange; 4 - top sealing flange; 5 - electric heating element; 6 - lower flange of diffuser; 7 - diffuser; 8 - upper flange of diffuser; 9 - connector flange; 10 - diffuser connector; 11 - mass flow meter; 12 - gas supply source; 13 - control valve; 14 - vacuum pump; 15 - vacuum gauge; 16 - vacuum gauge display; 17 - digital information acquisition card; 18 - computer; 19 - hollow cylinder with holes on the wall; 20 - threaded seal cover; 21 - radio frequency power supply; 22 - matcher; 23 - coaxial transmission line; 24 - radio frequency coupling coil; 25 - ground wire; 26 - radio frequency power supply system; 27 - air pressure acquisition system; 28 - vacuum pumping system; 29 - gas supply system, 30 - insulating seal seat. Detailed implementation mode

[0024] The present invention will be further described in detail below with reference to the accompanying drawings.

[0025] As Figure 1 shown, the present invention includes a gas supply system 29, a diffuser 7 and a vacuum chamber 1 connected in sequence. A hollow cylinder 19 with holes on the wall is provided in the vacuum chamber 1. The upper end of the hollow cylinder 19 with holes on the wall is sealed, the lower end is open, and the outer wall is hermetically connected to the bottom end of the vacuum chamber 1. An electric heating element 5 is provided in the hollow cylinder 19 with holes on the wall. The lower end of the electric heating element 5 extends out of the vacuum chamber 1 through the lower end opening of the hollow cylinder 19 with holes on the wall and is connected to an external power supply. A planar annular radio frequency coupling coil 24 is provided in the vacuum chamber 1, and the radio frequency coupling coil 24 is located above the hollow cylinder 19 with holes on the wall. A radio frequency power supply system 26 is provided outside the vacuum chamber 1, and the radio frequency coupling coil 24 is connected to the radio frequency power supply system 26 through a line. A vacuum pumping system 28 is provided on one side of the bottom end of the vacuum chamber 1, and a pressure acquisition system 27 is provided on the other side.

[0026] As Figure 1 shown, a bottom end sealing flange upper cover 2 and a bottom end sealing flange lower cover 3 which are stacked together and fixedly connected by bolts are provided at the bottom end of the vacuum chamber 1. A sealing element is provided between the bottom end sealing flange upper cover 2 and the bottom end sealing flange lower cover 3, and the bottom end sealing flange lower cover 3 is grounded. The hollow cylinder 19 with holes on the wall is a hollow cylinder made of a metal material. Its lower end passes through the bottom end sealing flange upper cover 2 and is welded to the bottom end sealing flange lower cover 3 as a whole. A through interface is provided on the bottom end sealing flange lower cover 3, and the center line of the rear end opening of the hollow cylinder 19 with holes on the wall coincides with the center line of the corresponding through interface on the bottom end sealing flange lower cover 3. The electric heating element 5 can be inserted into the vacuum chamber 1 through the through interface by an adapter and sealed. A detachable threaded seal cover 20 is provided at the front end of the hollow cylinder 19 with holes on the wall to achieve sealing. By screwing the threaded seal cover 20 to open it, the addition, storage and replacement of the getter material can be carried out. The outer diameter and length of the hollow cylinder 19 with holes on the wall are both smaller than those of the vacuum chamber 1. During operation, it needs to be placed entirely inside the vacuum chamber 1.

[0027] In this embodiment, the shape of the vacuum chamber 1 is a hollow cylinder, which is made of a sealable and high-temperature-resistant insulating material such as quartz or ceramic. The electric heating element 5 is an electric heating rod. The sealing element can be an oxygen-free copper sealing ring, a graphite sealing ring, an O-ring, a sealant, etc. The adapter can be a flange, a KF joint, a stainless steel through joint, a tetrafluoroethylene through joint, etc.

[0028] As Figure 1As shown, a top sealing flange 4 is provided at the top of the vacuum chamber 1. A diffuser lower flange 6 is provided at the lower end of the diffuser 7, and the diffuser lower flange 6 and the top sealing flange 4 are fixedly connected by bolts, so that the diffuser 7 and the vacuum chamber 1 are integrated. The diffuser 7 is a hollow metal cylinder that is thin at the upper end and thick at the lower end.

[0029] As Figure 1 shown, the gas supply system 29 includes a gas supply source 12, a mass flow meter 11, and a diffuser connector 10. The gas supply source 12 is connected to the diffuser connector 10 through a gas supply pipeline, and the mass flow meter 11 is provided on the gas supply pipeline. A connector flange 9 is provided at the lower end of the diffuser connector 10, and a diffuser upper flange 8 is provided at the upper end of the diffuser 7. The connector flange 9 and the diffuser upper flange 8 are fixedly connected by bolts. The diffuser connector 10 is also a hollow metal cylinder that is thin at the upper end and thick at the lower end. The gas supply pipeline can be a metal hard pipe such as stainless steel or iron, or a high-temperature and high-pressure insulating pipe such as polytetrafluoroethylene or Teflon. The mass flow meter 11 can control the steady-state air pressure in the vacuum chamber by keeping the gas flow rate constant. The gas supply source 12, the gas supply pipeline, the diffuser connector 10, and the diffuser 7 are connected in series in sequence. The diffuser 7 is hermetically connected to the vacuum chamber 1. Thus, the type and pressure of the gas in the vacuum chamber 1 can be adjusted by changing the gas supply source 12, and the flow rate of the gas introduced can be controlled by the mass flow meter 11, the diffuser 7, etc. The mass flow meter 11 is a well-known technology in the art and is a commercially available product.

[0030] As Figure 1 shown, the vacuum pumping system 28 includes a vacuum pump 14 and a control valve 13. The vacuum pump 14 is connected to a corresponding interface on the vacuum chamber 1 through a connecting pipeline, and the control valve 13 is provided on the connecting pipeline. The vacuum pump 14 is turned on to pump the gas in the vacuum chamber 1 to obtain a vacuum, and its initial vacuum degree and pumping rate are controllable through the control valve 13. In this embodiment, the control valve 13 is a needle valve, which is a well-known technology in the art and is a commercially available product.

[0031] As Figure 1 shown, the air pressure acquisition system 27 includes a vacuum gauge 15, a vacuum gauge display 16, a digital information acquisition card 17, and a computer 18 that are connected in series in sequence. The vacuum gauge 15 is connected to a corresponding interface on the vacuum chamber 1 through a pipeline. It is used to monitor the pressure and its changes in the vacuum chamber 1. Its reading can be obtained from the vacuum gauge display 16. At the same time, the pressure changes displayed on the vacuum gauge display 16 can be collected through the digital information acquisition card 17 via the software on the computer 18, and the pressure changes inside the vacuum chamber 1 can be measured effectively and quickly. The vacuum gauge 15, the vacuum gauge display 16, the digital information acquisition card 17, and the computer 18 are all well-known technologies in the art.

[0032] The radio frequency coupling coil 24 is a planar ring-shaped metal coil, which can be one group or multiple groups. Its material can be metals or alloys such as copper, iron, nickel, stainless steel, etc. And the metal coil is in a spiral tube structure along the circumferential direction of the ring, and the winding of the spiral tube can be a metal wire or a metal tube. As Figure 1 shown, the lower end of the radio frequency coupling coil 24 is fixedly installed on an insulating and sealing seat 30, and the insulating and sealing seat 30 is fixedly arranged on the side wall of the vacuum cavity 1.

[0033] As Figure 1 shown, the radio frequency power supply system 26 includes a radio frequency power supply 21, a matcher 22 and a coaxial transmission line 23. Among them, the radio frequency power supply 21 can output a radio frequency signal of 50 - 10,000 watts after passing through the matcher 22 and act on the radio frequency coupling coil 24. The radio frequency coupling coil 24 is arranged inside the vacuum cavity 1 and above all the hollow cylinders 19 with holes on the walls. The high-voltage output ends of the matcher 22 are respectively connected to the lower ends of both sides of the radio frequency coupling coil 24 through different coaxial transmission lines 23. Both coaxial transmission lines 23 pass through the insulating and sealing seat 30, and one of the coaxial transmission lines 23 is connected to the ground wire 25. When the output power of the radio frequency power supply 21 acts on the radio frequency coupling coil 24, a radio frequency electric field is generated inside the radio frequency coupling coil 24 and forms an inductive coupling discharge, so as to achieve the effect of generating plasma inside the vacuum cavity 1. The radio frequency power supply 21, the matcher 22 and the coaxial transmission line 23 are all well-known technologies in the art and are commercially available products.

[0034] The working principle of the present invention is as follows:

[0035] When the present invention works, first, the gas in the vacuum cavity 1 is extracted by the vacuum pumping system 28 to obtain a lower air pressure environment for the getter to work. And the working air pressure, gas type and flow rate can be appropriately adjusted within a certain range through the gas supply system 29 and the diffuser 7. Then, the electric heating element 5 is energized to heat and activate the getter in the hollow cylinder 19 with holes on the wall. And the radio frequency power supply system 26 is started so that the output power acts on the inside of the vacuum cavity 1 through the radio frequency coupling coil 24. A radio frequency electric field is generated inside the radio frequency coupling coil 24 and forms an inductive coupling discharge, so as to achieve the effect of generating plasma inside the vacuum cavity 1. The present invention improves the activation time of the getter by means of the coupled energy of the electric heating and the radio frequency power supply system. At the same time, the active species generated in the plasma can accelerate the gas absorption rate of the getter in the whole device.

Claims

1. A planar radio frequency inductively coupled discharge plasma enhanced getter device, characterized in that: it comprises a gas supply system (29), a diffuser (7) and a vacuum chamber (1) connected in sequence, wherein a hollow cylinder (19) with holes on the wall is provided in the vacuum chamber (1), and the upper end of the hollow cylinder (19) with holes on the wall is sealed, the lower end is open, and the outer wall is hermetically connected to the bottom end of the vacuum chamber (1). An electric heating element (5) is provided in the hollow cylinder (19) with holes on the wall, and the lower end of the electric heating element (5) extends out of the vacuum chamber (1) through the lower end opening of the hollow cylinder (19) with holes on the wall and is connected to an external power supply. A planar ring-shaped radio frequency coupling coil (24) is provided in the vacuum chamber (1), and the radio frequency coupling coil (24) is located above the hollow cylinder (19) with holes on the wall. A radio frequency power supply system (26) is provided outside the vacuum chamber (1), and the radio frequency coupling coil (24) is connected to the radio frequency power supply system (26) through a circuit. A vacuum pumping system (28) is provided on one side of the bottom end of the vacuum chamber (1), and a gas pressure acquisition system (27) is provided on the other side; a bottom-end sealed flange upper cover (2) and a bottom-end sealed flange lower cover (3) are stacked together at the bottom end of the vacuum chamber (1), and the lower end of the hollow cylinder (19) with holes on the wall passes through the bottom-end sealed flange upper cover (2) and is fixedly connected to the bottom-end sealed flange lower cover (3). The bottom-end sealed flange lower cover (3) is grounded, and a through interface for inserting the power supply heating element (5) into the corresponding hollow cylinder (19) with holes on the wall is provided on the bottom-end sealed flange lower cover (3); a detachable threaded cover (20) is provided at the upper end of the hollow cylinder (19) with holes on the wall; the gas supply system (29) comprises a gas supply source (12), a mass flow meter (11) and a diffuser connector (10). The gas supply source (12) is connected to the diffuser connector (10) through a gas supply pipeline, and the mass flow meter (11) is provided on the gas supply pipeline. A connector flange (9) is provided at the lower end of the diffuser connector (10), and a diffuser upper flange (8) is provided at the upper end of the diffuser (7), and the connector flange (9) is fixedly connected to the diffuser upper flange (8); the radio frequency coupling coil (24) is a planar ring-shaped metal coil, and the metal coil is in a spiral tube structure along the circumferential direction of the ring. An insulating and sealing seat (30) is provided on the side wall of the vacuum chamber (1), and the lower end of the radio frequency coupling coil (24) is fixedly installed on the insulating and sealing seat (30). The radio frequency power supply system (26) comprises a radio frequency power source (21) and a matcher (22) connected in series in sequence, and the matcher (22) is respectively connected to the two lower ends of the radio frequency coupling coil (24) through different coaxial transmission lines (23). Both coaxial transmission lines (23) pass through the insulating and sealing seat (30), and one of the coaxial transmission lines (23) is connected to the ground wire (25); The vacuum pumping system (28) first pumps out the gas in the vacuum chamber (1), and adjusts the working pressure, gas type and flow rate through the gas supply system (29) and the diffuser (7). Then, the getter in the hollow cylinder (19) with holes on the wall is heated and activated by the electric heating element (5). Then, the radio frequency power supply system (26) is started, and the output power acts on the vacuum chamber (1) through the radio frequency coupling coil (24), and plasma is generated in the vacuum chamber (1).

2. The planar radio frequency inductive coupling discharge plasma enhanced getter device according to claim 1, characterized in that: a top sealing flange (4) is provided at the top of the vacuum chamber (1), and a diffuser lower flange (6) is provided at the lower end of the diffuser (7) and is connected to the top sealing flange (4).

3. The planar radio frequency inductive coupling discharge plasma enhanced getter device according to claim 2, characterized in that: the diffuser (7) is a hollow metal cylinder with a thin upper end and a thick lower end.

4. The planar radio frequency inductive coupling discharge plasma enhanced getter device according to claim 1, characterized in that: the diffuser connector (10) is a hollow metal cylinder with a thin upper end and a thick lower end.

5. The planar radio frequency inductive coupling discharge plasma enhanced getter device according to claim 1, characterized in that: the vacuum pumping system (28) includes a vacuum pump (14) and a control valve (13). The vacuum pump (14) is connected to the corresponding interface on the vacuum chamber (1) through a connecting pipeline, and the control valve (13) is provided on the connecting pipeline; the air pressure acquisition system (27) includes a vacuum gauge (15), a vacuum gauge display (16), a digital information acquisition card (17) and a computer (18) connected in series in sequence.

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