Microwave plasma spray gun

Abstract

The utility model discloses a microwave plasma spray gun for an ion implanter. The microwave plasma spray gun comprises a microwave generator, a waveguide assembly, a plasma chamber, a working gas supply device, a medium tube and a conducting rod, wherein the open end of the dielectric tube is arranged outside the plasma chamber and connected to the waveguide assembly, and the closed end of the dielectric tube is arranged inside the plasma chamber; the conducting rod is hollow and is coaxially arranged in the inner cavity of the dielectric tube, the first end of the conducting rod extends to the open end of the dielectric tube, and the second end of the conducting rod extends to the closed end of the dielectric tube. According to the microwave plasma spray gun, metal pollution can be greatly reduced, electrons provided by the microwave plasma spray gun are uniformly distributed, and charge neutralization reaction can be better realized.

Description

Technical Field

[0001] The utility model generally relates to the field of semiconductor processing equipment, and in particular to a microwave plasma spray gun used in an ion implanter. Background Art

[0002] Ion implantation is an important doping technology in the integrated circuit manufacturing process. Ion implantation is an indispensable process in the manufacturing 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, and the ions or plasma can be accelerated by the electric field, and the direction of their movement can be changed by the magnetic field, so as to control the ions to enter the silicon wafer with a certain energy to achieve the purpose of doping.

[0003] During the ion implantation process, after the charged ions are injected into the silicon wafer, the charge will accumulate on the surface of the silicon wafer, generating static high voltage, which will damage the devices already made on the silicon wafer in severe cases. To solve this problem, the ion implanter uses a plasma spray gun, and the plasma spray gun is set on the path of the ion beam in front of the silicon wafer, so that the electrons ejected by the plasma spray gun reach the surface of the silicon wafer under the attraction of the ion beam space charge, and neutralize the positive charge accumulated on the surface of the silicon wafer. The traditional plasma spray gun is provided with a closed arc chamber, and the inert gas is fed into the arc chamber. The electrons emitted by the filament in the arc chamber ionize the gas atoms or molecules and generate plasma. The arc chamber is provided with an opening facing the ion beam. When the potential of the positively charged ion beam passing near the arc chamber is greater than the potential of the arc chamber, the low-energy electrons in the plasma in 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 spatial charge of the ion beam and weakening the divergence of the ion beam caused by the spatial charge. At the same time, the electrons that follow the ion beam to the surface of the silicon wafer neutralize the positive charge accumulated on it, protecting the devices on the silicon wafer from damage caused by electrostatic high voltage.

[0004] However, metal contamination in the cavity is very harmful to semiconductor devices, especially some devices (such as CIS, CMOS image sensors) are very sensitive to metal contamination, and extremely small amounts of metal contamination will cause the performance of the device to degrade or even fail. Since traditional plasma spray guns use metal filaments (usually tungsten filaments) to excite plasma, it is inevitable to introduce a certain amount of metal contamination, so the demand for plasma spray guns without metal contamination has become quite urgent. To solve this technical problem, a filamentless plasma spray gun can be used, for example, by exciting the plasma with microwaves. However, the microwave excitation method has the problem of uneven distribution of electron emission. When microwaves enter the arc chamber through an end face, there will be a diffuse emission, and its angle and density distribution are uneven. In addition, there is an exponential decay in the microwave power during the conduction from the injection end to the far end, which will cause uneven power distribution in the arc chamber. Many of the above problems will cause uneven density of plasma generated in the arc chamber, and ultimately lead to uneven distribution of electrons ejected from the opening.

[0005] Therefore, a plasma spray gun is needed that can reduce metal contamination and make the sprayed electrons evenly distributed, so as to meet the requirements of the ion implantation process. Utility Model Content

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

[0007] According to the technical solution of the utility model, the utility model provides a microwave plasma spray gun. The microwave plasma spray gun comprises: a microwave generator; a waveguide assembly for transmitting microwaves generated by the microwave generator; a plasma chamber, a first side of which is provided with an opening, in which microwaves act on a working gas 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 arranged outside the plasma chamber and connected to the waveguide assembly, and the closed end being arranged inside the plasma chamber; a conductive rod, which is hollow and coaxially arranged in 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 conductive rod is a hollow tube, and the inner cavity of the conductive rod is communicated with the inner cavity of the medium tube.

[0009] Preferably, the first end of the conductive rod exceeds the open end of the dielectric tube and extends to the outside of the waveguide assembly.

[0010] Preferably, the dielectric tube passes through a first end of the plasma chamber, and the closed end extends to a second end of the plasma chamber opposite to the first end.

[0011] Preferably, the portion of the dielectric tube extending outside the plasma chamber is wrapped by the conductive tube.

[0012] Preferably, the opening of the plasma chamber is a slit, and the length direction of the slit is consistent with the length direction of the dielectric tube in the plasma chamber.

[0013] Preferably, the waveguide assembly comprises a rectangular waveguide and a waveguide converter for converting an electromagnetic wave mode transmitted in the rectangular waveguide into an electromagnetic wave mode transmitted in the coaxial waveguide.

[0014] Preferably, a magnetic device is provided outside the plasma chamber, and the magnetic device is used to form a cusped magnetic field.

[0015] Furthermore, the magnetic device comprises a permanent magnet and a magnetic conductive material, wherein the permanent magnet is arranged on the second side and the third side of the plasma chamber, and the magnetic conductive material wraps the outer side of the permanent magnet.

[0016] Preferably, the inner wall of the plasma chamber is detachably provided with a protective plate, which covers the inner surface of the plasma chamber.

[0017] Compared with the prior art, the beneficial technical effects of a microwave plasma spray gun of the utility model are as follows:

[0018] 1. The utility model adopts microwave to excite plasma, which can eliminate the metal pollution caused by metal filaments. In addition, the utility model does not use a metal wire or metal probe in the process of microwave excitation plasma, which also avoids metal pollution.

[0019] 2. The utility model introduces gas into the dielectric waveguide through the hollow conductive rod, which can achieve the effect of cooling the dielectric tube and also achieve the effect of dust removal and reduce metal pollution.

[0020] 3. The microwave plasma spray gun of the utility model has a simple structure and low maintenance cost. By arranging a coaxial surface wave coupling structure inside the plasma chamber, electrons can be more easily emitted from the plasma chamber 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 charge on the surface of the wafer and improving the yield of the wafer. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0022] Figure 1It is a schematic diagram of the principle structure of a microwave plasma spray gun according to an embodiment of the utility model;

[0023] Figure 2 is a partial schematic diagram of a gas path of a microwave plasma spray gun according to an embodiment of the utility model; and

[0024] Figure 3 It is a schematic diagram of the overall frame structure of a microwave plasma spray gun according to another embodiment of the utility model.

[0025] Explanation of the reference numerals in the accompanying drawings: 1: plasma chamber; 2: conductive rod; 3: water-cooling channel; 4: dielectric tube; 5: protective plate; 6: permanent magnet; 7: magnetic conductive material; 8: plasma detection probe; 9: working gas supply device; 10: conductive tube; 11: microwave generator; 12: rectangular waveguide; 13: waveguide converter; 14: impedance matcher; 17: process chamber; 20: waveguide assembly; z: z-axis direction.

[0026] For the sake of brevity, the drawings illustrate the general construction mode, and the description and details of known features and technologies are omitted to avoid unnecessary confusion in the discussion of the embodiments of the utility model. In addition, the elements in the drawings are not necessarily drawn to scale. For example, the size of some elements in the drawings may be enlarged relative to other elements to help improve the understanding of the various embodiments of the utility model. The same reference numerals in different drawings represent the same elements, and similar reference numerals may but do not necessarily represent similar elements. DETAILED DESCRIPTION

[0027] The utility model is described in detail below 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 and the uses of these embodiments. As used herein, the wording "exemplary" means "used as an example, instance or explanation". Any implementation described as exemplary herein should not be interpreted as necessarily preferred or superior to other implementations. Furthermore, there is no intention to be bound by any representation or implicit theory presented in the aforementioned technical field, background technology, utility model content or the following detailed description.

[0028] The terms "first", "second", "third", etc. in the specification and claims are used to distinguish between similar elements, and are not necessarily used to describe a specific order or time sequence. It is to be understood that these terms used in this way are interchangeable where appropriate, such as to enable the utility model embodiments described herein to operate in other orders different from those described or shown herein. Similarly, if the method described herein includes a series of steps, the order of these steps presented herein is not necessarily the only order in which these steps can be performed, and some of the stated steps can be omitted and / or some other steps not described herein can be added to the method. In addition, the terms "comprise", "include", "have" and any variation thereof are intended to be applicable to non-exclusive inclusion, so that the process, method, product or device including a series of elements is not necessarily limited to those elements, but may include other elements that are not explicitly listed or inherent to these processes, methods, products or devices.

[0029] The utility model provides a microwave plasma spray gun, which can be applied to an ion implanter in the field of semiconductor processing technology. The microwave plasma spray gun can generate plasma with uniform density distribution in a plasma chamber, and can provide a uniformly distributed low-energy electron beam to the ion implanter to better achieve a charge neutralization reaction. The microwave plasma spray gun of the utility model includes a microwave generator, a waveguide assembly, a plasma chamber, a working gas supply device, a dielectric tube and a conductive rod. Among them, the microwave generator is used to generate microwaves; the waveguide assembly is used to transmit the microwaves generated by the microwave generator; the working gas supply device is used to provide working gas to the plasma chamber; the microwaves are transmitted inside the plasma chamber via the dielectric tube and the conductive rod, and the microwaves can act on the working gas in the plasma chamber to generate plasma. An opening is provided on the first side of the plasma chamber, and the opening can be used to output low-energy electrons in the plasma.

[0030] Figure 1 FIG. 2 shows a schematic diagram of the principle structure of a microwave plasma spray gun according to an embodiment of the utility model. Figure 1 As shown, the microwave generator 11 generates microwaves, which are transmitted through the waveguide assembly 20. The microwaves transmitted to the inside of the plasma chamber 1 continue to be transmitted inside the plasma chamber via the dielectric tube 4 and the conductive rod 2. The working gas supply device 9 delivers working gas to the plasma chamber 1. Inside the plasma chamber 1, the microwaves excite the working gas fed into the chamber 1, thereby generating plasma.

[0031] The microwave generator 11 is a device for providing microwave energy to the microwave plasma spray gun. As an example, the microwave generator 11 may include a magnetron, and may further include an isolator for unidirectional transmission of microwaves. In other examples, the microwave generator 11 may include a solid-state microwave source or a solid-state microwave generator. The microwave generator 11 may convert electrical energy into microwave energy of a rated frequency (e.g., 2.45 GHz, etc.), and may realize regulation of microwave power.

[0032] The waveguide assembly 20 of the present invention may adopt any suitable structure and configuration, and the specific configuration in each embodiment is not intended to limit the present invention. In one embodiment, the waveguide assembly 20 may include a rectangular waveguide and a waveguide converter, wherein the waveguide converter is used to convert the electromagnetic wave mode transmitted in the rectangular waveguide into the electromagnetic wave mode transmitted in the coaxial waveguide. The waveguide assembly 20 may further include an impedance matcher for impedance matching between the rectangular waveguide and the coaxial waveguide, thereby reducing the loss of microwaves in the transmission path.

[0033] The plasma chamber 1 is a closed chamber surrounded by a side wall and two opposite ends, and it works in a vacuum environment. The first end and the second end of the plasma chamber 1 can be set to be roughly parallel, which is conducive to the uniform distribution of plasma in the plasma chamber 1. An opening is provided on the side wall of the plasma chamber 1 for ejecting low-energy electrons in the plasma. The shape of the opening is not limited, and it can be a hole or a slit. The opening can be one or more, and the specific number and position can be set as needed. In one embodiment, the opening on the side wall of the plasma chamber 1 is in the shape of a long and narrow gap, such as a long strip slit. In another embodiment, the opening on the side wall of the plasma chamber 1 is a plurality of holes arranged in a long strip. The plasma chamber 1 can be made of a metal material, such as an aluminum alloy, to have conductive properties. In one example, two parallel metal plates can be used as the first end and the second end, respectively, and the two parallel metal plates and several rectangular metal walls together constitute the plasma chamber 1.

[0034] The working gas supply device 9 is used to supply working gas to the plasma chamber 1, and the working gas 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 in the plasma chamber 1. In one embodiment, the working gas is monitored and adjusted by the plasma detection probe 8. The working gas can be selected as an inert gas, such as xenon. In one embodiment, the working gas supply device 9 includes a ventilation pipeline, and the outlet of the ventilation pipeline is arranged at the second end of the plasma chamber 1. Figure 1As shown, the ventilation duct can pass through the second end of the plasma chamber 1 and continue to extend inward for a distance along the z-axis direction, and its outlet is arranged near the second end. In other examples, the ventilation duct can penetrate from the side wall of the plasma chamber 1, and the outlet is arranged near the second end; in addition, a vent hole can also be arranged on the second end or at a position on the side wall close to the second end, and the vent hole is the outlet of the ventilation duct, thereby providing working gas to the plasma chamber 1 through the vent hole. Since the first end of the plasma chamber 1 is the microwave inlet end, the outlet of the ventilation duct is arranged near the second end, so that the density of the working gas has a decreasing density distribution from the second end to the first end, which in turn offsets the decreasing distribution of microwave power from the first end to the second end, so as to make the plasma density distribution more uniform.

[0035] The dielectric tube 4 has an open end and a closed end, wherein the open end is arranged outside the plasma chamber 1 and connected to the waveguide assembly 20, and the closed end is arranged inside the plasma chamber 1. In one embodiment, the dielectric tube 4 passes through a first end of the plasma chamber 1, and the closed end thereof extends to a second end of the plasma chamber 1 opposite to the first end. Figure 1 As shown, a hole is provided at the first end of the plasma chamber 1, and the dielectric tube 4 passes through the hole from the first end into the plasma chamber 1. The dielectric tube 4 is a hollow tube, one end of which is located outside the plasma chamber 1 is open, and the other end of which is located inside the plasma chamber 1 is closed, so that the dielectric tube 4 forms an inner cavity between its open end and the closed end. 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 in the length direction of the chamber 1, and its closed end is arranged near the second end. In a specific example, the closed end of the dielectric tube 4 and the air outlet of the venting line of the working gas supply device 9 are both arranged at a position close to the second end in the plasma chamber 1, and the positions of the two are adjacent. In other embodiments, the dielectric tube 4 may extend a distance in the z-axis direction after penetrating the plasma chamber 1, and its closed end is arranged at other positions in the plasma chamber 1, not close to the second end. In the present 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 pipeline can be further adjusted accordingly, and the two cooperate with each other to make the plasma density distribution more uniform.

[0036] A sealing device is provided at the hole where the dielectric tube 4 penetrates into the plasma chamber 1. The inner cavity of the dielectric tube 4 is in the atmospheric environment, while the outer wall of the part of the dielectric tube 4 extending inside the plasma chamber 1 is in the vacuum environment, that is, the inside of the plasma chamber 1 reaches a certain vacuum degree. The dielectric tube 4 is made of dielectric material, for example, quartz, ceramic and other dielectric materials can be used. The use of dielectric tubes such as quartz tubes can isolate metal materials (such as metal parts such as conductive rods 2) from the plasma chamber 1, thereby preventing metal materials from directly contacting the plasma to cause metal contamination.

[0037] Since the plasma in the plasma chamber 1 continuously generates heat, it is necessary to cool down the medium tube 4 to avoid overheating. Therefore, in the utility model, the conductive rod 2 is specially designed to be hollow, and the hollow conductive rod 2 is arranged in the inner cavity of the medium tube 4 and is coaxial with the medium tube 4. In one embodiment, the conductive rod 2 is a hollow tube, both ends of which are not closed, and the inner cavity of the conductive rod 2 is connected to the inner cavity of the medium tube 4. Moreover, there is a certain gap between the outer wall of the conductive rod 2 and the inner wall of the medium tube 4 to facilitate the passage of gas through the gap. In this way, gas can be introduced into the medium tube 4 through the inner cavity of the conductive rod 2, and the flowing gas takes away the heat, thereby achieving the effect of cooling the medium tube 4. In addition, the conductive rod 2 works as a microwave transmission antenna in an atmospheric environment, and a small amount of metal pollution can also be taken out by using this air inlet ventilation structure.

[0038] Figure 2 FIG. 1 shows a partial schematic diagram of the gas path of a microwave plasma spray gun according to an embodiment of the utility model. Figure 2 As shown, the gas enters the inner cavity of the conductive rod 2 from the first end of the conductive rod 2, continues to flow in the inner cavity of the conductive rod 2 to the second end of the conductive rod 2, and is poured into the inner cavity of the dielectric tube 4 at the second end; the gas entering the inner cavity of the dielectric tube 4 flows from the closed end of the dielectric tube 4 to the open end of the dielectric tube 4 outside the conductive rod 2, and enters the cavity of the waveguide component 20 at the open end; the gas returning to the cavity of the waveguide component 20 flows out through a plurality of air outlets arranged on the side of the cavity, thereby taking out heat and achieving a cooling effect.

[0039] In the present invention, the first end of the conductive rod 2 extends to the open end of the dielectric tube 4, and the second end of the conductive rod 2 extends to the closed end of the dielectric tube 4. In one embodiment, the first end of the conductive rod 2 exceeds the open end of the dielectric tube 4 and extends to the outside of the waveguide assembly 20. The conductive rod 2 can be made of metal. In one example, the conductive rod 2 is a hollow copper tube.

[0040] The conductive rod 2 can be used as an antenna for microwave transmission and works in an atmospheric environment. Microwaves can be transmitted into the plasma chamber 1 through this antenna, emitting microwave power into the chamber, exciting the ionization of the working gas in the chamber, and thus generating plasma. Once plasma is generated, the outer wall of the dielectric tube 4 will be wrapped by the conductive plasma, so that the conductive rod 2 and the plasma around the dielectric tube 4 form an equivalent coaxial waveguide. In the coaxial waveguide, the conductive rod 2 is the inner conductor of the coaxial waveguide, and the plasma on the outer wall of the dielectric tube 4 is equivalent to the outer conductor of the coaxial waveguide. The impedance of the coaxial waveguide is mainly determined by the outer diameter of the dielectric tube 4 and the outer diameter of the conductive rod 2. Inside the plasma chamber 1, microwaves are transmitted in the coaxial waveguide, and the power loss is very small, and a relatively uniform microwave power distribution can be obtained in the z-axis direction. Moreover, microwaves can continuously deliver power to the plasma through surface wave coupling of the outer wall of the dielectric tube 4, thereby maintaining the long-term stability of the plasma in the plasma chamber 1.

[0041] Figure 3 FIG. 2 shows the structure of a microwave plasma spray gun according to another embodiment of the present invention. In this embodiment, some components and structures of the microwave plasma spray gun are similar to those of FIG. Figure 1 or Figure 2 The embodiments shown are substantially the same, so mainly the different parts will be described.

[0042] 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, wherein the waveguide assembly includes a rectangular waveguide 12, a waveguide converter 13 and an impedance matcher 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 magnetic conductive material 7. It can be understood that the many components listed here are for exemplary purposes, and the purpose of the utility model can still be achieved even without some of the components.

[0043] The dielectric tube 4 passes through the first end of the plasma chamber 1. Outside the plasma chamber 1, the dielectric tube 4 extends in the z-axis direction 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 wrapped by a conductive tube. Figure 3As shown, for the tube body portion of the dielectric tube 4 extending outside the plasma chamber 1, the outer wall of the tube body is wrapped by a conductive tube 10. The conductive tube 10 can be made of a metal tube, and its inner diameter is substantially equal to the outer diameter of the dielectric tube 4. There is only a small gap between the inner wall of the conductive tube 10 and the outer wall of the dielectric tube 4 for easy assembly. In the utility model, the conductive tube 10 and the conductive rod 2 in the dielectric tube 4 form a coaxial waveguide, wherein the conductive rod 2 is the inner conductor of the coaxial waveguide, and the conductive tube 10 is the outer conductor of the coaxial waveguide. Therefore, outside the plasma chamber 1, microwaves will be transmitted losslessly in the coaxial waveguide. In addition, the coaxial waveguide is connected and matched with the rectangular waveguide 12 to transmit the microwave energy provided by the microwave generator 11 to the plasma chamber 1.

[0044] Inside the plasma chamber 1, the dielectric tube 4 can extend a distance along the z-axis direction so that its closed end reaches a certain set position in the plasma chamber 1. In the z-axis direction, the position of the closed end of the dielectric tube 4 can be set to be closer to the second end compared with the opening on the side wall of the plasma chamber 1. In some examples, the dielectric tube 4 can also continue to extend toward the second end along the z-axis direction until its closed end approaches the second end of the plasma chamber 1. The closed end of the dielectric tube 4 and the vent outlet of the working gas supply device 9 can be arranged near the second end, and the two cooperate with each other to make the generated plasma density distribution more uniform.

[0045] The conductive rod 2 is a hollow tube with openings at both ends, and the inner cavity of the conductive rod 2 is connected to the inner cavity of the dielectric tube 4. In this way, gas can be introduced into the dielectric tube 4 through the inner cavity of the conductive rod 2, so that the gas flows from the closed end to the open end of the dielectric tube 4, and the gas is discharged from a plurality of gas outlets provided on the side of the cavity of the rectangular waveguide 12, thereby taking out heat, achieving the effect of cooling the dielectric tube 4, and also taking out a small amount of metal pollution.

[0046] exist Figure 3 In the illustrated embodiment, the first end of the conductive rod 2 extends beyond the open end of the dielectric tube 4 to the outside of the rectangular waveguide 12, and the second end of the conductive rod 2 extends to the closed end of the dielectric tube 4. Inside the plasma chamber 1, the conductive rod 2 and the plasma around the outer wall of the dielectric tube 4 form an equivalent coaxial waveguide, which helps to achieve lossless transmission of microwaves in the plasma chamber 1. In this embodiment, the microwave generator 11 generates microwaves of a specific frequency, which are successively transmitted in the rectangular waveguide 12 and in the coaxial waveguide formed by the conductive tube 10 and the conductive rod 2; after entering the interior of the plasma chamber 1, the microwaves continue to be transmitted along the conductive rod 2, and the lossless transmission of microwaves in the plasma chamber 1 is achieved through the equivalent coaxial waveguide formed by the conductive rod 2 and the plasma around the outer wall of the dielectric tube 4. Inside the plasma chamber 1, the microwaves excite the working gas fed into the chamber 1, thereby generating plasma.

[0047] like Figure 3 As shown, a water cooling channel 3 may be arranged in the wall of the plasma chamber 1 to cool the chamber 1. A plasma detection probe 8 may also be arranged in the plasma chamber 1 to monitor the state of the plasma using the working principle of the Rum probe, such as collecting parameters such as electron temperature and density. In addition, the inner wall of the plasma chamber 1 is detachably provided with a protective plate 5, which covers the inner surface of the plasma chamber 1. The protective plate 5 is used to prevent the metal material of the plasma chamber 1 from directly contacting the plasma, thereby eliminating the metal contamination caused by the sputtering of the metal under the action of the plasma, and at the same time, it can also protect 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. As needed, the protective plate 5 can be regularly maintained or replaced. In one example, the protective plate 5 is a layer of quartz plate, which 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] An opening is provided on the side wall of the plasma chamber 1 for ejecting low-energy electrons in the plasma. The opening is a slit, and the length direction of the slit is consistent with the z-axis direction or the length direction of the medium tube 4 in the chamber 1. The opening can be provided on the side through which the ion beam passes, that is, the first side of the plasma chamber. In another embodiment, a graphite plate may be provided on the outside of the first side of the plasma chamber, and the graphite plate has a slit or hole corresponding to the opening. As an example, the side wall of the plasma chamber provided with the opening is covered with a graphite plate, and a slit or a small hole is provided on the graphite plate at a position corresponding to the opening. For example, if the opening is a slit, a slit or a plurality of small holes may be provided on the graphite plate accordingly; if the opening is a plurality of holes, a plurality of small holes may be provided on the graphite plate accordingly.

[0049] In the present invention, a magnetic device may be provided outside the plasma chamber 1, and the magnetic device is used to form a cusp magnetic field to make the plasma in the chamber 1 evenly distributed and limit the movement of electrons toward the inner wall of the chamber 1. Figure 3In the illustrated embodiment, the magnetic device includes a permanent magnet 6 and a magnetic conductive material 7, both of which are arranged along the z-axis direction. The permanent magnet 6 is arranged on the second side and the third side of the plasma chamber 1, and the magnetic conductive material 7 wraps the outer side of the permanent magnet 6. In one example, the second side and the third side of the plasma chamber 1 are both arranged to be opposite to the first side or not adjacent to the first side. The magnetic conductive material 7 can be soft iron or other magnetic conductive materials. The cusp magnetic field formed by the magnetic device helps the generation of plasma. When microwave excitation generates electrons, the electrons are constrained by the cusp magnetic field and are not easy to collide with the inner wall of the plasma chamber 1 and lose. In this way, the electrons are restricted to move in the chamber 1, which increases the probability of electrons colliding with gas atoms or molecules for the second time to generate plasma. In addition, due to the effect of the cusp magnetic field, the plasma generated by the ionized gas can be evenly distributed in the z-axis direction or in the length direction of the plasma chamber 1, thereby facilitating the extraction of large-sized low-energy electron beams.

[0050] The microwave plasma spray gun of the utility model can be installed at the top of the process chamber 17 of the ion implanter, and a part of it passes through the process chamber 17 from the top, and the process chamber 17 can serve as its base to support and fix it. Figure 3 As shown, the plasma chamber 1 of the microwave plasma spray gun is disposed as a whole inside the process chamber 17, in a vacuum environment required for plasma operation. When the ion beam used for silicon wafer implantation passes near the opening of the plasma chamber 1, the low-energy electrons in the plasma in 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, so that the space charge of the ion beam is neutralized, and the divergence of the ion beam caused by the space charge is weakened; at the same time, the electrons following the ion beam to the surface of the silicon wafer neutralize the positive charge accumulated thereon, thereby protecting the devices on the silicon wafer from damage caused by electrostatic high voltage.

[0051] A detailed description is given herein with reference to specific exemplary embodiments. However, it is apparent that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the utility model as described in the appended claims. Although specific embodiments of the utility model have been shown and described, it is apparent that a person skilled in the art may make many changes, variations and modifications without departing from the scope of the appended claims. Therefore, the specification and the drawings should be considered to be illustrative rather than restrictive. Moreover, the above-mentioned use of embodiments and other exemplary languages ​​does not necessarily refer to the same embodiment or the same example, but may refer to different and unique embodiments, or may be the same embodiment. The appended claims will include within their scope all such changes, variations and modifications that fall within the true scope and spirit of the utility model.

Claims

1. A microwave plasma spray gun, characterized in that: include: Microwave generator; A waveguide assembly, used for transmitting microwaves generated by the microwave generator; A plasma chamber, wherein a first side of the plasma chamber is provided with an opening, and in the plasma chamber, the microwave acts on the working gas to generate plasma; A working gas supply device, used for providing the working gas to the plasma chamber; a dielectric tube having an open end and a closed end, wherein the open end is disposed outside the plasma chamber and connected to the waveguide assembly, and the closed end is disposed inside the plasma chamber; A conductive rod is hollow and coaxially arranged in the inner cavity of the medium tube, a first end of the conductive rod extends to the open end of the medium tube, and a second end of the conductive rod extends to the closed end of the medium tube.

2. The microwave plasma spray gun according to claim 1, characterized in that: The conductive rod is a hollow tube, and the inner cavity of the conductive rod is communicated with the inner cavity of the medium tube.

3. The microwave plasma spray gun according to claim 1, characterized in that: The first end of the conductive rod exceeds the open end of the dielectric tube and extends to the outside of the waveguide assembly.

4. The microwave plasma spray gun according to claim 1, characterized in that: The medium tube passes through a first end of the plasma chamber, and the closed end extends to a second end of the plasma chamber opposite to the first end.

5. The microwave plasma spray gun according to claim 1, characterized in that: The portion of the dielectric tube extending outside the plasma chamber is wrapped by a conductive tube.

6. The microwave plasma spray gun according to claim 1, characterized in that: The opening of the plasma chamber is a slit, and the length direction of the slit is consistent with the length direction of the dielectric tube in the plasma chamber.

7. The microwave plasma spray gun according to claim 1, characterized in that: The waveguide component includes a rectangular waveguide and a waveguide converter, wherein the waveguide converter is used to convert an electromagnetic wave mode transmitted in the rectangular waveguide into an electromagnetic wave mode transmitted in a coaxial waveguide.

8. The microwave plasma spray gun according to claim 1, characterized in that: A magnetic device is arranged outside the plasma chamber, and the magnetic device is used to form a cusped magnetic field.

9. The microwave plasma spray gun according to claim 8, characterized in that: The magnetic device comprises a permanent magnet and a magnetically conductive material, wherein the permanent magnet is arranged on the second side and the third side of the plasma chamber, and the magnetically conductive material wraps the outer side of the permanent magnet.

10. The microwave plasma spray gun according to claim 1, characterized in that: The inner wall of the plasma chamber is detachably provided with a protection plate, and the protection plate covers the inner surface of the plasma chamber.

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