A microwave plasma spray gun

Abstract

The application discloses a microwave plasma jet which can be used in ion implantation machines in the field of semiconductor processing technology. The microwave plasma jet comprises a microwave generator, a waveguide assembly, a plasma chamber, a working gas supply device, a dielectric tube and a conductive rod. The open end of the dielectric tube is arranged outside the plasma chamber and connected to the waveguide assembly, and the closed end is arranged inside the plasma chamber. The conductive rod is coaxially arranged in the inner cavity of the dielectric tube, the first end of the conductive rod extends to the open end of the dielectric tube, and the second end extends to the closed end of the dielectric tube. The microwave plasma jet can greatly reduce metal contamination, and the electron distribution is uniform, so that the charge neutralization reaction can be better realized.

Description

Technical Field

[0001] This invention generally relates to the field of semiconductor processing equipment, and more particularly to a microwave plasma spray gun for an ion implanter. Background Technology

[0002] In integrated circuit manufacturing, ion implantation is an important doping technique. It is an indispensable process in the modern manufacture of large-scale integrated circuits. The principle of ion implantation is to ionize atoms or molecules to form plasma. The ions in the plasma carry a certain amount of charge. An electric field can accelerate the ions or plasma, and a magnetic field can be used to change their direction of motion, thereby controlling the ions to enter the silicon wafer with a certain amount of energy to achieve doping.

[0003] During ion implantation, charged ions, once injected into a silicon wafer, accumulate charge on the wafer surface, generating electrostatic high voltage. In severe cases, this can damage devices already fabricated on the wafer. To address this issue, ion implanters utilize plasma guns positioned in front of the silicon wafer along the path of the ion beam. This allows electrons ejected from the plasma gun to reach the silicon wafer surface under the attraction of the ion beam's space charge, neutralizing the accumulated positive charge. Traditional plasma guns feature a closed arc chamber. Inert gas is introduced into the arc chamber, where electrons emitted from the filament ionize gas atoms or molecules, generating plasma. The arc chamber has an opening facing the ion beam. When the potential of a positively charged ion beam passing near the arc chamber exceeds the arc chamber's potential, low-energy electrons in the plasma within the arc chamber are attracted by the electric field and ejected from the opening. The low-energy electrons ejected from the opening interact with the positively charged ion beam, neutralizing the space charge of the ion beam and reducing the divergence caused by the space charge. At the same time, the electrons that follow the ion beam to the silicon wafer surface neutralize the positive charge accumulated thereon, protecting the devices on the silicon wafer from damage caused by electrostatic high voltage.

[0004] However, metal contamination in the cavity is extremely harmful to semiconductor devices, especially certain devices (such as CIS and CMOS image sensors), which are highly sensitive to metal contamination. Even trace amounts of metal contamination can lead to performance degradation or even failure. Since traditional plasma torches use metal filaments (usually tungsten filaments) to excite plasma, a certain amount of metal contamination is inevitably introduced. Therefore, the need for metal-contamination-free plasma torches is quite urgent. To solve this technical problem, filamentless plasma torches can be used, for example, by exciting plasma using microwaves. However, microwave excitation suffers from uneven electron emission distribution. When microwaves enter the arc chamber through one end face, diffuse emission occurs, resulting in uneven distribution of angle and density. Furthermore, microwave power attenuates exponentially during propagation from the injection end to the distal end, leading to uneven power distribution within the arc chamber. All these problems cause uneven plasma density generated within the arc chamber, ultimately resulting in uneven electron distribution ejected from the opening.

[0005] Therefore, a plasma spray gun that can reduce metal contamination and ensure uniform electron distribution is needed to meet the requirements of ion implantation processes. Summary of the Invention

[0006] In view of the technical problems existing in the prior art, the present invention provides a microwave plasma spray gun, which can not only greatly reduce metal contamination to meet the requirements of ultra-low metal contamination, but also provides uniform electron distribution, which can better achieve charge neutralization.

[0007] According to the technical solution of the present invention, the present invention provides a microwave plasma spray gun. The microwave plasma spray gun includes: a microwave generator; a waveguide assembly for transmitting microwaves generated by the microwave generator; a plasma chamber, the first side of which has an opening, wherein microwaves act on a working gas within the plasma chamber to generate plasma; a working gas supply device for supplying working gas to the plasma chamber; a dielectric tube having an open end and a closed end, the open end being disposed outside the plasma chamber and connected to the waveguide assembly, and the closed end being disposed inside the plasma chamber; and a conductive rod coaxially disposed within the inner cavity of the dielectric tube, the first end of the conductive rod extending to the open end of the dielectric tube, and the second end of the conductive rod extending to the closed end of the dielectric tube.

[0008] Preferably, the dielectric tube extends through the first end of the plasma chamber, and the closed end extends to the second end of the plasma chamber opposite to the first end.

[0009] Furthermore, a recess is provided at the center of the second end, and the closed end of the medium tube is received in the recess.

[0010] Preferably, the portion of the dielectric tube extending outside the plasma chamber is wrapped with a conductive tube.

[0011] Preferably, the opening of the plasma chamber is a slit, the length of which is aligned with the length of the dielectric tube within the plasma chamber.

[0012] Preferably, the waveguide assembly includes a rectangular waveguide and a waveguide transducer for converting an electromagnetic wave mode transmitted in the rectangular waveguide into an electromagnetic wave mode transmitted in the coaxial waveguide.

[0013] Preferably, a magnetic device is provided on the outside of the plasma chamber to generate a shear magnetic field.

[0014] Furthermore, the magnetic device includes a permanent magnet and a magnetically conductive material, wherein the permanent magnet is arranged on the second and third sides of the plasma chamber, and the magnetically conductive material wraps around the outside of the permanent magnet.

[0015] Preferably, the inner wall of the plasma chamber is detachably provided with a protective plate that covers the inner surface of the plasma chamber.

[0016] Preferably, the working gas supply device includes a venting pipe with its outlet located at the second end of the plasma chamber.

[0017] Preferably, a graphite plate is provided on the outer side of the first side of the plasma chamber, the graphite plate having holes corresponding to the opening.

[0018] Compared with the prior art, the beneficial technical effects of the microwave plasma spray gun of the present invention are as follows:

[0019] 1. This invention uses microwave-excited plasma, which can eliminate metal contamination caused by metal filaments. Furthermore, this invention avoids the use of igniters in the form of metal wires or metal probes during the microwave-excited plasma process, thus also preventing metal contamination.

[0020] 2. The microwave plasma spray gun of the present invention has a simple structure and low maintenance cost. By setting a coaxial surface wave coupling structure inside the plasma chamber, electrons can be emitted from the plasma chamber more easily and the electron beam uniformity is high, which greatly improves the ability to neutralize the surface charge of the wafer, thereby effectively reducing the accumulation of surface charge on the wafer and improving the yield of the wafer. Attached Figure Description

[0021] The exemplary embodiments disclosed herein can be better understood by reading the following detailed description in conjunction with the accompanying drawings, in which:

[0022] Figure 1 This is a schematic diagram of the principle structure of a microwave plasma spray gun according to an embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of the principle structure of a microwave plasma spray gun according to another embodiment of the present invention;

[0024] Figure 3 This is a schematic diagram of the overall frame structure of a microwave plasma spray gun according to another embodiment of the present invention;

[0025] Figure 4 yes Figure 3 A schematic diagram of the cross-sectional structure of the plasma chamber of the microwave plasma spray gun is shown; and

[0026] Figure 5 yes Figure 3 The diagram shows a three-dimensional structure of the plasma chamber of the microwave plasma spray gun.

[0027] Explanation of reference numerals in the attached figures: 1: Plasma chamber; 2: Conductive rod; 3: Water-cooled channel; 4: Dielectric tube; 5: Protective plate; 6: Permanent magnet; 7: Magnetic material; 8: Plasma detection probe; 9: Working gas supply device; 10: Conductive tube; 11: Microwave generator; 12: Rectangular waveguide; 13: Waveguide converter; 14: Impedance matching device; 15: Recess; 16: Opening; 17: Process cavity; 20: Waveguide assembly; z: Z-axis direction.

[0028] For the sake of brevity, the accompanying drawings illustrate a general construction method, and descriptions and details of well-known features and techniques are omitted to avoid unnecessarily obscuring the discussion of the embodiments of the invention. Furthermore, the elements in the drawings are not necessarily drawn to scale. For example, the dimensions of some elements in the drawings may be enlarged relative to other elements to aid in understanding the various embodiments of the invention. The same reference numerals in different drawings denote the same elements, while similar reference numerals may, but do not necessarily, denote similar elements. Detailed Implementation

[0029] The invention will now be described in detail with reference to the accompanying drawings. It should be understood that the following detailed description is merely exemplary in nature and is not intended to limit the embodiments of the subject matter or application, or the uses of such embodiments. As used herein, the term "exemplary" means "serving as an example, instance, or illustration." Any implementation described herein as exemplary should not be construed as necessarily preferred or superior to other implementations. Furthermore, there is no intention to be bound by any representations or implied theories presented in the foregoing technical field, background art, summary of the invention, or the following detailed description.

[0030] The terms “first,” “second,” “third,” etc., used in the specification and claims are used to distinguish between similar elements and are not necessarily used to describe a particular order or chronological sequence. It should be understood that these terms are interchangeable where appropriate, for example, to allow embodiments of the invention described herein to operate in a different order than that described or shown herein. Similarly, if a method described herein comprises a series of steps, the order of these steps presented herein is not necessarily the only possible order in which they can be performed, and some stated steps may be omitted and / or other steps not described herein may be added to the method. Furthermore, the terms “comprising,” “including,” “having,” and any variations thereof are intended to apply non-exclusive inclusion, such that a process, method, article of manufacture, or apparatus that comprises a series of elements is not necessarily limited to those elements, but may include other elements not expressly listed or inherent to such processes, methods, articles of manufacture, or apparatus.

[0031] This invention provides a microwave plasma spray gun applicable to ion implanters in the field of semiconductor processing technology. This microwave plasma spray gun can generate plasma with a uniform density distribution within a plasma chamber and can provide a uniformly distributed low-energy electron beam to the ion implanter for better charge neutralization. The microwave plasma spray gun of this invention includes a microwave generator, a waveguide assembly, a plasma chamber, a working gas supply device, a dielectric tube, and a conductive rod. The microwave generator generates microwaves; the waveguide assembly transmits the microwaves generated by the microwave generator; the working gas supply device supplies working gas to the plasma chamber; the microwaves are conducted within the plasma chamber via the dielectric tube and the conductive rod, and within the plasma chamber, the microwaves act on the working gas to generate plasma. An opening is provided on the first side of the plasma chamber, which can be used to output low-energy electrons from the plasma.

[0032] Figure 1 A schematic diagram illustrating the principle structure of a microwave plasma spray gun according to an embodiment of the present invention is shown. Figure 1 As shown, microwave generator 11 generates microwaves, which are transmitted through waveguide assembly 20. The microwaves, conducted into plasma chamber 1, continue to be conducted inside the plasma chamber via dielectric tube 4 and conductive rod 2. Working gas supply device 9 supplies working gas into plasma chamber 1. Inside plasma chamber 1, microwaves excite the working gas supplied to chamber 1, thereby generating plasma.

[0033] Microwave generator 11 is a device for providing microwave energy to a microwave plasma gun. As an example, microwave generator 11 may include a magnetron and may further include an isolator for unidirectional microwave transmission. In other examples, microwave generator 11 may include a solid-state microwave source or a solid-state microwave generator, etc. Microwave generator 11 can convert electrical energy into microwave energy at a rated frequency (e.g., 2.45 GHz) and can regulate the microwave power.

[0034] The waveguide assembly 20 of the present invention can adopt any suitable structure and configuration, and the specific configurations in the various embodiments are not intended to limit the invention. In one embodiment, the waveguide assembly 20 may include a rectangular waveguide and a waveguide transducer, wherein the waveguide transducer is used to convert an electromagnetic wave mode transmitted in the rectangular waveguide into an electromagnetic wave mode transmitted in the coaxial waveguide. The waveguide assembly 20 may further include an impedance matching device for impedance matching between the rectangular waveguide and the coaxial waveguide, thereby reducing microwave loss in the transmission path.

[0035] The plasma chamber 1 is a closed chamber surrounded by sidewalls and two opposing ends, operating in a vacuum environment. The first and second ends of the plasma chamber 1 can be configured to be substantially parallel, which facilitates uniform plasma distribution within the chamber. Openings are provided on the sidewalls of the plasma chamber 1 for ejecting low-energy electrons from the plasma. The shape of the openings is not limited; they can be holes or slits. There can be one or more openings, and their specific number and location can be determined as needed. In one embodiment, the opening on the sidewall of the plasma chamber 1 is a narrow slit, such as a long strip slit. In another embodiment, the opening on the sidewall of the plasma chamber 1 is a plurality of holes arranged in a long strip. The plasma chamber 1 can be made of a metallic material, such as aluminum alloy, to have electrical conductivity. In one example, two parallel metal plates can serve as the first and second ends, respectively, and these two parallel metal plates, together with several rectangular metal walls, constitute the plasma chamber 1.

[0036] A working gas supply device 9 is used to supply working gas to the plasma chamber 1, which is required to generate a stable and uniform plasma. The flow rate of the working gas can be adjusted to provide a set density of working gas within the plasma chamber 1. In one embodiment, this is monitored and adjusted by a plasma detection probe 8. The working gas can be an inert gas, such as xenon. In one embodiment, the working gas supply device 9 includes a venting conduit with its outlet located at a second end of the plasma chamber 1. Figure 1As shown, the venting conduit can extend inward along the z-axis for a distance through the second end of the plasma chamber 1, with its outlet located near the second end. In other examples, the venting conduit can penetrate through the side wall of the plasma chamber 1, with its outlet located near the second end; alternatively, a vent hole can be provided on the second end or on the side wall near the second end, serving as the outlet of the venting conduit, thereby supplying working gas to the plasma chamber 1. Since the first end of the plasma chamber 1 is the microwave inlet, placing the outlet of the venting conduit near the second end ensures that the working gas density decreases from the second end to the first end, correspondingly offsetting the decreasing microwave power distribution from the first end to the second end, thus resulting in a more uniform plasma density distribution.

[0037] The dielectric tube 4 has an open end and a closed end, wherein the open end is located outside the plasma chamber 1 and connected to the waveguide assembly 20, and the closed end is located inside the plasma chamber 1. In one embodiment, the dielectric tube 4 extends through a first end of the plasma chamber 1, and its closed end extends to a second end of the plasma chamber 1 opposite to the first end. Figure 1 As shown, a hole is formed at the first end of the plasma chamber 1, through which the dielectric tube 4 enters the plasma chamber 1 from the first end. The dielectric tube 4 is a hollow tube, with one end outside the plasma chamber 1 open and the other end inside the plasma chamber 1 closed, thus forming an inner cavity between the open and closed ends of the dielectric tube 4. Outside the plasma chamber 1, the open end of the dielectric tube 4 is connected to the waveguide assembly 20. Inside the plasma chamber 1, the dielectric tube 4 extends in the z-axis direction or along the length of the chamber 1, with its closed end located near the second end. In one specific example, both the closed end of the dielectric tube 4 and the outlet of the working gas supply device 9 are located inside the plasma chamber 1 near the second end, and their positions are adjacent. In other embodiments, the dielectric tube 4 may extend a distance in the z-axis direction after entering the plasma chamber 1, with its closed end located at other positions within the plasma chamber 1, not near the second end. In this invention, the position of the closed end of the medium tube 4 in the z-axis direction can be adjusted as needed, and the position of the air outlet of the ventilation pipe can be further adjusted accordingly. The two work together to make the plasma density distribution more uniform.

[0038] A sealing device is installed at the opening where the dielectric tube 4 enters the plasma chamber 1. The inner cavity of the dielectric tube 4 is in an atmospheric environment, while the outer wall of the portion of the dielectric tube 4 extending inside the plasma chamber 1 is in a vacuum environment, meaning the interior of the plasma chamber 1 reaches a certain degree of vacuum. The dielectric tube 4 is made of a dielectric material, such as quartz or ceramic. Using a dielectric tube like a quartz tube can isolate metal materials (such as the conductive rod 2 and other metal components) from the plasma chamber 1, thereby preventing direct contact between the metal materials and the plasma, which could cause metal contamination.

[0039] A conductive rod 2 is disposed within the inner cavity of the dielectric tube 4 and is coaxial with the dielectric tube 4. A certain gap may exist between the outer wall of the conductive rod 2 and the inner wall of the dielectric tube 4. In one example, the conductive rod 2 may be made of metal, such as copper. The first end of the conductive rod 2 extends to the open end of the dielectric tube 4, and the second end extends to the closed end of the dielectric tube 4. This conductive rod 2 can serve as an antenna for microwave transmission, operating in an atmospheric environment. Microwaves can be conducted through this antenna into the plasma chamber 1, transmitting microwave power into the chamber and ionizing the working gas within the chamber, thereby generating plasma. Once plasma is generated, the outer wall of the dielectric tube 4 will be enveloped by the conductive plasma, thus forming an equivalent coaxial waveguide with the conductive rod 2 and the plasma surrounding the dielectric tube 4. In this coaxial waveguide, the conductive rod 2 is the inner conductor, and the plasma on the outer wall of the dielectric tube 4 is equivalent to the outer conductor. The impedance of this coaxial waveguide is mainly determined by the outer diameter of the dielectric tube 4 and the outer diameter of the conductive rod 2. Inside plasma chamber 1, microwaves propagate through the coaxial waveguide with minimal power loss, achieving a relatively uniform microwave power distribution along the z-axis. Furthermore, through surface wave coupling on the outer wall of dielectric tube 4, microwaves can continuously deliver power to the plasma, thereby maintaining the long-term stability of the plasma within plasma chamber 1.

[0040] Figure 2 A schematic diagram illustrating the principle structure of a microwave plasma spray gun according to another embodiment of the present invention is shown. In this embodiment, the basic structure of the microwave plasma spray gun is similar to... Figure 1 The embodiments shown are largely the same, so the main differences will be explained.

[0041] like Figure 2As shown, a recess 15 is provided at the center of the second end of the plasma chamber 1, and the closed end of the dielectric tube 4 is housed within the recess 15. By placing the closed end of the dielectric tube 4 in the recess 15, the dielectric tube 4 and the conductive rod 2 span and cover the entire plasma chamber 1 in the z-axis direction. This achieves a relatively uniform microwave power distribution along the entire length of the chamber 1 from the first end to the second end. Furthermore, the coaxial surface wave coupling structure penetrates the entire chamber 1, resulting in a uniform plasma distribution within the chamber 1, thereby significantly improving the uniformity of the ejected electron distribution. In this invention, the structure of the second end of the plasma chamber 1 is not limited to... Figure 1 and Figure 2 The structure shown can also be adapted to other suitable structures. In some examples, the second end can be recessed downwards at its center and protrude outwards to form a cup-shaped structure; or it can be recessed downwards at its center to form a groove structure, but the bottom surface of the second end remains substantially flat.

[0042] Figures 3 to 5 The structure of a microwave plasma spray gun according to yet another embodiment of the invention is shown. In this embodiment, some components and structures of the microwave plasma spray gun are similar to those of... Figure 1 or Figure 2 The embodiments shown are largely the same, so the main differences will be explained.

[0043] like Figure 3 As shown, the microwave plasma spray gun mainly includes a microwave generator 11, a waveguide assembly, a plasma chamber 1, a working gas supply device 9, a dielectric tube 4, and a conductive rod 2. The waveguide assembly includes a rectangular waveguide 12, a waveguide converter 13, and an impedance matching device 14. The microwave plasma spray gun may also include a conductive tube 10, a water-cooling channel 3, a plasma detection probe 8, a protective plate 5, and a magnetic device, wherein the magnetic device further includes a permanent magnet 6 and a magnetically conductive material 7. It is understood that the many components listed herein are for illustrative purposes, and the objectives of the present invention can still be achieved even without some of these components.

[0044] The dielectric tube 4 extends through the first end of the plasma chamber 1. Outside the plasma chamber 1, the dielectric tube 4 extends along the z-axis away from the first end, and its open end is connected to the rectangular waveguide 12. As an example, the portion of the dielectric tube 4 extending outside the plasma chamber 1 is enclosed by a conductive tube. Figure 3As shown, for the portion of the dielectric tube 4 extending outside the plasma chamber 1, its outer wall is wrapped by a conductive tube 10. The conductive tube 10 can be made of metal, and its inner diameter is substantially equal to the outer diameter of the dielectric tube 4. Only a small gap exists between the inner wall of the conductive tube 10 and the outer wall of the dielectric tube 4 to facilitate assembly. In this invention, the conductive tube 10 and the conductive rod 2 inside the dielectric tube 4 constitute a coaxial waveguide, where the conductive rod 2 is the inner conductor of the coaxial waveguide, and the conductive tube 10 is the outer conductor. Therefore, outside the plasma chamber 1, microwaves will be transmitted losslessly within this coaxial waveguide. Furthermore, this coaxial waveguide is connected and cooperates with the rectangular waveguide 12 to transmit the microwave energy provided by the microwave generator 11 to the plasma chamber 1.

[0045] Inside the plasma chamber 1, the dielectric tube 4 can extend a certain distance along the z-axis, so that its closed end reaches a predetermined position within the plasma chamber 1. In the z-axis direction, compared to the opening on the side wall of the plasma chamber 1, the position of the closed end of the dielectric tube 4 can be set closer to the second end. In some examples, the dielectric tube 4 can also continue to extend towards the second end along the z-axis until its closed end approaches the second end of the plasma chamber 1 or is accommodated in a recess within the second end. Both the closed end of the dielectric tube 4 and the outlet of the working gas supply device 9 can be located near the second end, cooperating to ensure a more uniform plasma density distribution. Furthermore, inside the plasma chamber 1, the conductive rod 2 and the plasma surrounding the outer wall of the dielectric tube 4 form an equivalent coaxial waveguide, which facilitates lossless microwave transmission within the plasma chamber 1.

[0046] exist Figure 3 In the illustrated embodiment, microwave generator 11 generates microwaves of a specific frequency. These microwaves propagate sequentially in rectangular waveguide 12 and in a coaxial waveguide formed by conductive tube 10 and conductive rod 2. After entering the plasma chamber 1, the microwaves continue to propagate along conductive rod 2, and lossless transmission within the plasma chamber 1 is achieved through an equivalent coaxial waveguide formed by conductive rod 2 and the plasma surrounding the outer wall of dielectric tube 4. Inside the plasma chamber 1, microwaves excite the working gas introduced into the chamber, thereby generating plasma.

[0047] like Figures 3 to 5As shown, a water-cooling channel 3 can be arranged inside the wall of the plasma chamber 1 to cool the chamber 1. A plasma detection probe 8 can also be installed inside the plasma chamber 1 to monitor the plasma state using the working principle of a rum probe, such as collecting parameters like electron temperature and density. Additionally, a protective plate 5 is detachably installed on the inner wall of the plasma chamber 1, covering the inner surface of the plasma chamber 1. The protective plate 5 prevents the metal materials of the plasma chamber 1 from directly contacting the plasma, thereby eliminating metal contamination caused by sputtering under the action of plasma, and also protecting the inner wall of the plasma chamber 1 from ion contamination. The protective plate 5 can be made of non-metallic materials, such as quartz, graphite, silicon carbide, or other materials. The protective plate 5 can be periodically maintained or replaced as needed. In one example, the protective plate 5 is a quartz plate that is detachably fixed or attached to the inner wall of the plasma chamber 1 and can completely cover the exposed surface of the inner wall.

[0048] like Figure 5 As shown, an opening 16 is provided on the side wall of the plasma chamber 1 for ejecting low-energy electrons from the plasma. The opening 16 is a slit, the length of which is aligned with the z-axis or the length of the dielectric tube 4 within the chamber 1. The opening 16 can be located on the side through which the ion beam passes, i.e., the first side of the plasma chamber. In another embodiment, a graphite plate can also be provided on the outer side of the first side of the plasma chamber, the graphite plate having slits or holes corresponding to the opening. As an example, the side wall of the plasma chamber with the opening is covered with a graphite plate, and slits or holes are formed on the graphite plate at positions corresponding to the opening. For example, if the opening is a slit, one or more slits or holes can be formed correspondingly on the graphite plate; if the opening is multiple holes, multiple holes can be formed correspondingly on the graphite plate.

[0049] In this invention, a magnetic device may be provided on the outside of the plasma chamber 1. This magnetic device is used to form a shear magnetic field, so that the plasma in the chamber 1 is uniformly distributed and the movement of electrons towards the inner wall of the chamber 1 is restricted. Figures 3 to 5 In the illustrated embodiment, the magnetic device includes a permanent magnet 6 and a magnetically conductive material 7, both arranged along the z-axis. The permanent magnet 6 is positioned on the second and third sides of the plasma chamber 1, and the magnetically conductive material 7 surrounds the outer surface of the permanent magnet 6. In one example, the second and third sides of the plasma chamber 1 are either opposite to or not adjacent to the first side. Figure 4As shown, permanent magnets 6 are arranged along the z-axis on two external sides of the plasma chamber 1 to form a tangential magnetic field. The outer side of the permanent magnets 6 is wrapped with a magnetically conductive material 7 to concentrate the magnetic field on the inner wall of the plasma chamber 1 and prevent it from affecting other surrounding components. The magnetically conductive material 7 can be soft iron or other magnetically conductive materials. The tangential magnetic field formed by this magnetic device facilitates plasma generation. When electrons are generated by microwave excitation, they are constrained by the tangential magnetic field and are less likely to collide with the inner wall of the plasma chamber 1 and be lost. This confines the electrons within the chamber 1, increasing the probability of secondary collisions between electrons and gas atoms or molecules to generate plasma. Furthermore, due to the effect of the tangential magnetic field, the plasma generated by ionized gas can form a uniform distribution along the z-axis or along the length of the plasma chamber 1, thereby facilitating the extraction of large-size low-energy electron beams.

[0050] The microwave plasma spray gun of the present invention can be installed at the top of the process chamber 17 of the ion implanter, with a portion extending from the top into the process chamber 17. The process chamber 17 can serve as its base for support and fixation. Figure 3 As shown, the plasma chamber 1 of the microwave plasma torch is entirely located inside the process chamber 17, in the vacuum environment required for plasma operation. When the ion beam used for silicon wafer implantation passes near the opening 16 of the plasma chamber 1, low-energy electrons in the plasma within the chamber 1 are attracted by the electric field and ejected from the opening. The low-energy electrons ejected from the opening interact with the positively charged ion beam, neutralizing the space charge of the ion beam and reducing the divergence caused by the space charge. Simultaneously, electrons following the ion beam to the silicon wafer surface neutralize the positive charge accumulated thereon, thereby protecting the devices on the silicon wafer from damage caused by electrostatic high voltage.

[0051] This document provides a detailed description with reference to specific exemplary embodiments. However, it will be apparent that various modifications and alterations can be made to these embodiments without departing from the broader spirit and scope of the invention as set forth in the appended claims. Although specific embodiments of the invention have been shown and described, it will be apparent to those skilled in the art that many changes, variations, and modifications can be made without departing from the scope of the appended claims. Therefore, the specification and drawings should be considered illustrative rather than restrictive. Moreover, the above use of the language of embodiments and other exemplary examples does not necessarily refer to the same embodiment or the same example, but may refer to different and unique embodiments, or it may refer to the same embodiment. All such changes, variations, and modifications falling within the true scope and spirit of the invention will be included within the scope of the appended claims.

Claims

1. A microwave plasma torch characterized by, The application relates to a microwave plasma generator comprising: a microwave generator; a waveguide assembly for transmitting microwaves generated by the microwave generator; a plasma chamber, a first side of the plasma chamber being provided with an opening, the microwaves acting on a working gas in the plasma chamber to generate plasma; a working gas supply device for providing the working gas to the plasma chamber; a dielectric tube having an open end and a closed end, the open end being arranged outside the plasma chamber and connected to the waveguide assembly, the closed end being arranged inside the plasma chamber; an electrically conductive rod coaxially arranged in an inner cavity of the dielectric tube, a first end of the electrically conductive rod extending to the open end of the dielectric tube, a second end of the electrically conductive rod extending to the closed end of the dielectric tube, the dielectric tube extending through a first end portion of the plasma chamber, the closed end extending to a second end portion of the plasma chamber opposite to the first end portion, a central portion of the second end portion being provided with a recess, the recess accommodating the closed end of the dielectric tube, the opening of the plasma chamber is a slit, a length direction of the slit being consistent with a length direction of the dielectric tube in the plasma chamber.

2. The microwave plasma torch of claim 1, wherein, The part of the dielectric tube extending outside the plasma chamber is wrapped by an electrically conductive tube.

3. The microwave plasma torch of claim 1, wherein, The waveguide assembly comprises a rectangular waveguide and a waveguide converter, the waveguide converter being used for converting electromagnetic wave modes transmitted in the rectangular waveguide into electromagnetic wave modes transmitted in a coaxial waveguide.

4. The microwave plasma torch of claim 1, wherein, The outside of the plasma chamber is provided with a magnetic device, the magnetic device being used for forming a magnetic field.

5. The microwave plasma torch of claim 4, wherein, The magnetic device comprises permanent magnets and a magnetic conductive material, wherein the permanent magnets are arranged on a second side and a third side of the plasma chamber, and the magnetic conductive material wraps the outside of the permanent magnets.

6. The microwave plasma torch of claim 1, wherein, An inner wall of the plasma chamber is detachably provided with a protective plate, the protective plate covering an inner surface of the plasma chamber.

7. The microwave plasma torch of claim 1, wherein, The working gas supply device comprises a ventilation pipeline, an air outlet of the ventilation pipeline being arranged at the second end portion of the plasma chamber.

8. The microwave plasma torch of claim 1, wherein, The outside of the first side of the plasma chamber is provided with a graphite plate, the graphite plate being provided with a hole corresponding to the opening. The application relates to a microwave plasma generator comprising: a microwave generator; a waveguide assembly for transmitting microwaves generated by the microwave generator; a plasma chamber, a first side of the plasma chamber being provided with an opening, the microwaves acting on a working gas in the plasma chamber to generate plasma; a working gas supply device for providing the working gas to the plasma chamber; a dielectric tube having an open end and a closed end, the open end being arranged outside the plasma chamber and connected to the waveguide assembly, the closed end being arranged inside the plasma chamber; an electrically conductive rod coaxially arranged in an inner cavity of the dielectric tube, a first end of the electrically conductive rod extending to the open end of the dielectric tube, a second end of the electrically conductive rod extending to the closed end of the dielectric tube, the dielectric tube extending through a first end portion of the plasma chamber, the closed end extending to a second end portion of the plasma chamber opposite to the first end portion, a central portion of the second end portion being provided with a recess, the recess accommodating the closed end of the dielectric tube, the opening of the plasma chamber is a slit, a length direction of the slit being consistent with a length direction of the dielectric tube in the plasma chamber. The part of the dielectric tube extending outside the plasma chamber is wrapped by an electrically conductive tube. The waveguide assembly comprises a rectangular waveguide and a waveguide converter, the waveguide converter being used for converting electromagnetic wave modes transmitted in the rectangular waveguide into electromagnetic wave modes transmitted in a coaxial waveguide. The outside of the plasma chamber is provided with a magnetic device, the magnetic device being used for forming a magnetic field. The magnetic device comprises permanent magnets and a magnetic conductive material, wherein the permanent magnets are arranged on a second side and a third side of the plasma chamber, and the magnetic conductive material wraps the outside of the permanent magnets. An inner wall of the plasma chamber is detachably provided with a protective plate, the protective plate covering an inner surface of the plasma chamber. The working gas supply device comprises a ventilation pipeline, an air outlet of the ventilation pipeline being arranged at the second end portion of the plasma chamber. The outside of the first side of the plasma chamber is provided with a graphite plate, the graphite plate being provided with a hole corresponding to the opening.

Images