Cooling sputtering target for ion source

Abstract

An ion source having a target holder for holding a solid dopant material is disclosed. The target holder is mounted to a shaft, which may be in communication with an actuator, allowing the solid dopant material to be inserted into or retracted from the arc chamber. The shaft and / or target holder is actively cooled such that the solid dopant material remains below its melting point. In this way, the solid dopant material can be inserted into the arc chamber without any melting. The cooling mechanism used may include gas cooling, liquid cooling, thermoelectric cooling, or other cooling techniques.

Description

[0001] This application claims priority to U.S. Patent Application No. 18 / 232,169, filed August 9, 2023, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0002] Embodiments of this disclosure relate to implanters and ion sources, and more specifically, to ion sources comprising a target scaffold for holding a solid dopant material, wherein the temperature of the dopant material can be maintained below its melting point. Background Technology

[0003] Various types of ion sources can be used to generate ions used in semiconductor processing equipment. For example, an indirect heated cathode (IHC) ion source operates by supplying current to a filament disposed behind a cathode. The filament emits thermionic electrons, which are accelerated and heat the cathode, causing the cathode to emit electrons into the arc chamber of the ion source. The cathode is disposed at one end of the arc chamber, and a repulsive electrode may be disposed at the end of the arc chamber opposite the cathode. The cathode and repulsive electrode may be biased to repel electrons, guiding them back to the center of the arc chamber. In some embodiments, a magnetic field is used to further confine the electrons within the arc chamber. Multiple sides are used to connect the two ends of the arc chamber.

[0004] Extraction openings are positioned along one of these sides, close to the center of the arc chamber, through which ions generated in the arc chamber can be extracted.

[0005] In some embodiments, it may be necessary to utilize materials in solid form as dopant. For example, in some systems, it may be necessary to generate ions of aluminum, gallium, indium, magnesium, antimony, tin, lead, or various metals. Typically, a crucible is used to evaporate these metals or metal-containing compounds. However, these systems may be limited by the beam current that may be generated. Furthermore, using solid pure dopant may result in molten metal that may overflow into the ion source or be ejected uncontrollably due to the vacuum environment. Alternatively, dopant-containing materials containing the desired dopant material may be used; however, these materials may introduce unwanted substances and reduce the effective desired dopant beam current.

[0006] Therefore, it would be beneficial to have an ion source that can be used with solid dopant materials (such as certain metals) that have low melting temperatures. Summary of the Invention

[0007] An ion source having a target holder for holding solid doped material is disclosed. The target holder is mounted to a shaft, which can communicate with an actuator, thereby allowing the solid doped material to be inserted into or retracted from an arc chamber. The shaft is actively cooled so that the solid doped material is held below its melting point. Thus, the solid doped material can be inserted into the arc chamber without any melting. The cooling mechanism used may include air cooling, liquid cooling, thermoelectric cooling, or other cooling techniques.

[0008] According to one embodiment, an ion source is disclosed. The ion source includes an arc chamber, a target holder, a shaft, and a cooling system. The arc chamber includes a plurality of walls connecting a first end and a second end. The target holder is used to hold a solid dopant material. The shaft connects to the target holder to extend the target holder into the arc chamber. The cooling system is used to actively cool the solid dopant material. In some embodiments, the cooling system actively cools the shaft. In some embodiments, the shaft is made of copper, and at least a portion of the shaft is covered by a sheath made of a non-copper material. In some embodiments, the shaft is cooled using a cooling fluid.

[0009] In some embodiments, the shaft includes a hollow cavity with an inlet passage and an outlet passage, allowing cooling fluid to flow through the interior of the shaft. In some embodiments, a baffle is located within the hollow cavity and separates the inlet and outlet passages. In some embodiments, the shaft includes two tubes, with the hollow cavity defining an outer tube and an inner tube disposed within the outer tube and not extending to a distal end of the shaft, wherein the two tubes form the inlet and outlet passages.

[0010] In some embodiments, the shaft is cooled by directing cooling gas to the outside of the shaft. In some embodiments, the ion source further includes a cooling tube in fluid communication with a fluidic refrigerator, and the cooling tube is wound around a portion of the shaft. In some embodiments, the ion source further includes a cooling plate fixed to the proximal end of the shaft, and the cooling plate serves as a heat sink. In some embodiments, channels are disposed in the cooling plate and cooling fluid flows through the cooling plate to maintain the cooling plate within a predetermined temperature range. In some embodiments, the shaft and / or target holder is actively cooled by using a heat pump attached thereto. In some embodiments, the target holder is actively cooled using cooling fluid flowing through it.

[0011] According to another embodiment, an ion implanter is disclosed. The ion implanter includes an ion source for generating an ion beam and one or more beamline assemblies to guide the ion beam to a workpiece. The ion source includes an arc chamber, a target holder, a shaft, and a cooling system. The arc chamber includes a plurality of walls connecting a first end and a second end. The target holder is used to hold a solid dopant material. The shaft connects to the target holder to extend the target holder into the arc chamber. The cooling system is used to actively cool the solid dopant material. In some embodiments, the cooling system actively cools the shaft. In some embodiments, the shaft is made of copper, and at least a portion of the shaft is covered by a sheath made of a non-copper material. In some embodiments, the shaft is cooled using a cooling fluid. In some embodiments, the ion implanter also includes a thermocouple and a controller. The thermocouple is used to measure the temperature of the solid dopant material, and the controller uses information from the thermocouple to maintain the solid dopant material within a desired temperature range. In some embodiments, the controller actively cools the shaft to maintain the solid dopant material within a desired temperature range. In some embodiments, the shaft is cooled by a fluid flowing through the interior of the shaft or a fluid flowing through the exterior of the shaft, and the controller controls the temperature of the solid dopant material by controlling the flow rate of the fluid. In some embodiments, the shaft is cooled by attaching a cooling plate to the proximal end of the shaft, and the controller controls the temperature of the solid dopant material by controlling the temperature of the cooling plate. In some embodiments, the shaft and / or target holder is cooled by attaching one or more heat pumps, and the controller controls the temperature of the solid dopant material by controlling the power supplied to the one or more heat pumps. In some embodiments, the target holder is cooled by a fluid flowing through the interior of the target holder, and the controller controls the temperature of the solid dopant material by controlling the flow rate of the fluid. Attached Figure Description

[0012] For a better understanding of this application, please refer to the accompanying drawings, which are incorporated herein by reference, and wherein:

[0013] Figure 1 This is a schematic diagram of an indirect heated cathode (IHC) ion source including a target holder with a cooling system according to one embodiment.

[0014] Figure 2A-2D The connection between the target scaffold and the solid dopant material is shown according to some embodiments.

[0015] Figure 3A-3G Different cooling systems are shown for cooling the shaft.

[0016] Figure 4 The cooling system cooling target support is shown.

[0017] Figure 5 An ion implanter that can utilize any ion source described herein is shown. Detailed Implementation

[0018] As mentioned above, at very high temperatures, solid dopants in the ion source may melt and produce unwanted and / or uncontrolled dopant build-up in the arc chamber, and material may be ejected or deflected into the chamber.

[0019] Figure 1 An ion source, which may be an IHC (Indirectly Heated Cathode) ion source 10, is shown, comprising a target holder that allows sputtering of solid dopant materials without melting. The IHC ion source 10 includes a target holder comprising opposing ends and a plurality of walls 101 connecting these ends. The walls 101 of an arc chamber 100 may be constructed of a conductive material and may be electrically connected to each other. In some embodiments, a liner may be disposed near one or more walls 101. A cathode 110 is disposed in the arc chamber 100 at a first end 104 of the arc chamber 100. A filament 160 is disposed behind the cathode 110 and is connected to a filament power supply 165 configured to pass current through the filament 160, causing the filament 160 to emit thermionic electrons. A cathode bias power supply 115 applies a negative bias voltage to the filament 160 relative to the cathode 110, thus accelerating these thermionic electrons from the filament 160 toward the cathode 110 and heating the cathode 110 as they strike the back of the cathode 110. The cathode bias power supply 115 can bias the filament 160 so that it has a voltage that is more negative than the voltage of the cathode 110, for example, between 200V and 1500V. The voltage difference between the cathode 110 and the filament 160 can be called the cathode bias. Then, the cathode 110 emits thermionic electrons from its front surface into the arc chamber 100.

[0020] Therefore, filament power supply 165 provides current to filament 160, and cathode bias power supply 115 biases filament 160 so that filament 160 has a more negative voltage than cathode 110, thus attracting electrons from filament 160 to cathode 110. In some embodiments, cathode 110 may be biased relative to arc chamber 100, for example, by bias power supply 111, and the voltage difference between arc chamber 100 and cathode 110 may be referred to as arc voltage. In other embodiments, cathode 110 may be electrically connected to arc chamber 100 to be at the same voltage as the wall 101 of arc chamber 100. In these embodiments, bias power supply 111 may not be used, and cathode 110 may be electrically connected to the wall 101 of arc chamber 100. In some embodiments, arc chamber 100 is connected to electrical ground.

[0021] A repulsion electrode 120 may be provided at a second end 105 opposite to the first end 104. The repulsion electrode 120 may be biased relative to the arc chamber 100 by a repulsion electrode bias power supply 123. In other embodiments, the repulsion electrode 120 may be electrically connected to the arc chamber 100 so that it is at the same voltage as the wall 101 of the arc chamber 100. In these embodiments, the repulsion electrode bias power supply 123 may not be used, and the repulsion electrode 120 may be electrically connected to the wall 101 of the arc chamber 100. In some embodiments, a bias power supply 111 may be used to bias the repulsion electrode 120. In still other embodiments, the repulsion electrode 120 may not be used and may be electrically floating.

[0022] The cathode 110 and the repulsive electrode 120 are each made of a conductive material (e.g., metal or graphite).

[0023] In some embodiments, a magnetic field is generated in the arc chamber 100, which is designed to confine electrons in one direction. This magnetic field is typically parallel to the wall 101 from the first end 104 to the second end 105. For example, electrons may be confined in a column parallel to the direction from the cathode 110 to the repulsive electrode 120 (i.e., the y-direction), so that the electrons are not subjected to any electromagnetic force moving in the y-direction. However, the movement of electrons in other directions may be subject to electromagnetic forces.

[0024] An extraction opening 140 may be provided on one side of the arc chamber 100 (referred to as the extraction plate 103). Figure 1 In this configuration, the extraction opening 140 is located on a side parallel to the XY plane (perpendicular to the page). Furthermore, the IHC ion source 10 also includes a gas inlet 106 through which the gas to be ionized is introduced into the arc chamber 100. In some embodiments, multiple gases are mixed and can enter the arc chamber 100 through the gas inlet 106. In other embodiments, multiple gas inlets can be used to introduce different gases.

[0025] In some embodiments, the first electrode and the second electrode may be disposed on their respective opposing walls 101 of the arc chamber 100, such that the first electrode and the second electrode are located on the wall adjacent to the extraction plate 103 within the arc chamber 100. The first electrode and the second electrode may each be biased by a corresponding power supply. In one embodiment, the first electrode and the second electrode may be connected to a common power supply. However, in other embodiments, for maximum flexibility and the ability to adjust the output of the IHC ion source 10, the first electrode may be connected to a first electrode power supply, and the second electrode may be connected to a second electrode power supply.

[0026] The controller 180 may be connected to one or more power sources, such that the voltage or current supplied by these power sources can be modified. The controller 180 may include a processing unit, such as a microcontroller, personal computer, special-purpose controller, or other suitable processing unit. The controller 180 may also include a non-transitory storage element, such as semiconductor memory, magnetic memory, or other suitable memory. This non-transitory storage element may contain instructions and other data that allow the controller 180 to perform the functions described herein.

[0027] The IHC ion source 10 also includes a target holder 190, which can be inserted into and retracted from the arc chamber 100. Figure 1 In the illustrated embodiment, the target holder 190 is positioned in an extended position within the arc chamber 100. In some embodiments, the target holder 190 enters the arc chamber 100 along one of the walls 101 of the arc chamber 100. In some embodiments, the target holder 190 may enter the arc chamber 100 at a mid-plane between the first end 104 and the second end 105. In another embodiment, the target holder 190 may enter the arc chamber 100 at a location different from the mid-plane. Figure 1 In the illustrated embodiment, the target holder 190 enters the arc chamber 100 through the side opposite to the extraction opening 140. However, in other embodiments, the target holder 190 may enter through the side adjacent to the extraction plate 103. The target holder 190 is movable between a first position and a second position.

[0028] The target holder 190 includes a first surface facing the arc chamber 100. A solid dopant material 195 may be fixed to the first surface of the target holder 190. The solid dopant material may be a pure metal, such as indium, aluminum, magnesium, antimony, gallium, tin, lead, or other metals, or a dopant containing the material. The solid dopant material 195 may be in the form of a block of material. In some embodiments, the solid dopant material may be a pure metal, wherein more than 95% of the dopant material comprises a metal. In other embodiments, the solid dopant material 195 may be a compound containing the dopant material, such as an alloy or ceramic material. For example, if aluminum is the desired dopant, the solid dopant material can be pure aluminum, Al-X alloys (where X = B, Cr, Co, Cu, Fe, Mo, Sc, Ti, Zn, Mg, Zr, Dy, Er, Gd, Mn, Nd, Ni, Sm, Ag, Ta, V) or ceramics such as Al2O3, AlF3, AlN, AlP, Al2Se3, Al2S3, Al2Te3, and Al2TiO5.

[0029] In some embodiments, thermocouple 198 may be located near target holder 190 or solid dopant material 195 to measure the temperature of solid dopant material 195. Thermocouple 198 may be in communication with controller 180. Thermocouple 198 may include one or more wires 199 electrically connecting thermocouple 198 to controller 180.

[0030] The target holder 190 is located at the distal end of the shaft 200. In some embodiments, the target holder 190 may be a separate component fixed to the distal end of the shaft 200. In other embodiments, the target holder may be the distal end of the shaft 200, such that the distal end of the shaft 200 is directly fixed to the solid dopant material 195. In some embodiments, the target holder 190 may have a larger diameter than the rest of the shaft to increase the surface area in contact with the solid dopant material 195.

[0031] Shaft 200 can be made of thermally conductive materials, such as aluminum, stainless steel, tungsten, copper or other materials.

[0032] The proximal end of shaft 200 can be coupled to actuator 210. Operation of actuator 210 allows target holder 190 to linearly move into or retract from arc chamber 100. Shaft 200 passes through vacuum seal 197 such that a first portion of shaft 200 is disposed within cavity 196 communicating with arc chamber 100, and a second portion of shaft is disposed under atmospheric conditions. The lengths of the first and second portions vary depending on the position of target holder 190.

[0033] During operation, filament power supply 165 applies current through filament 160, causing filament 160 to emit thermionic electrons. These electrons strike the back side of cathode 110, which may be more positively charged than filament 160, causing cathode 110 to heat up and subsequently emit electrons into arc chamber 100. Under the influence of a magnetic field, these electrons collide with gas molecules supplied to arc chamber 100 via gas inlet 106. Carrier gas, such as argon, and / or etching gas, such as nitrogen, fluoride, or chlorine, can be introduced into arc chamber 100 through appropriately positioned gas inlet 106. The combination of electrons from cathode 110, gas, and positive potential generates plasma. In some embodiments, electrons and positive ions may be confined to some extent by a magnetic field. In some embodiments, the plasma is confined to the vicinity of the center of arc chamber 100, near extraction opening 140. Solid dopant material 195 is converted into a gaseous phase and ionized by chemical etching or physical sputtering of the plasma. The ionized feed can then be extracted through extraction opening 140 and used to generate an ion beam.

[0034] Negative ions and neutral atoms sputtered or otherwise released from the solid dopant material 195 are attracted to the plasma because the plasma is maintained at a more positive voltage than the target support 190.

[0035] The controller 180 can control the actuator 210 such that the outermost surface of the solid dopant material 195 is flush with the wall 101. When the solid dopant material 195 is sputtered, the controller 180 can cause the actuator 210 to translate axis 200 to extend further into the arc chamber 100, thereby holding the surface of the solid dopant material in that position. In other embodiments, the solid dopant material 195 can extend into the arc chamber 100 to expose more of the solid dopant material 195 to the plasma.

[0036] It is worth noting that in some embodiments, a cooling system 215 is used to actively cool the shaft 200. In this way, the temperature of the target holder 190 is reduced due to its physical contact with the cooled shaft. Furthermore, the temperature of the solid dopant material 195 is also reduced by the cooling system 215 because it is in physical contact with the target holder 190. In other embodiments, the cooling system 215 actively cools the target holder 190. For example, in some embodiments, thermal paste is used to fix the solid dopant material 195 to a first surface of the target holder 190. Furthermore, the shape and / or contour of the first surface of the target holder 190 and the solid dopant material 195 can be configured to maximize the surface area of ​​the target holder 190 in contact with the solid dopant material 195.

[0037] For example, Figure 2A-2D Various configurations of the target support 190 and solid dopant material 195 are shown to increase the surface area of ​​the contact region of these components. Figure 2A In this configuration, the solid dopant material 195 is formed to extend beyond the outer edge of the target holder 190, such that a portion of the solid dopant material surrounds the outer periphery of the target holder 190. Additionally, one or more protrusions 193 may be formed on the first surface of the target holder 190, these protrusions 193 increasing the contact area and providing a more secure connection. Figure 2B In this configuration, the target holder 190 has a larger diameter than the rest of the shaft 200, which allows for the attachment of larger volumes of solid dopant material 195 to the target holder 190 and also creates a larger contact area between these components. One or more protrusions 193 may also be located on the first surface of the target holder 190. Figure 2C One embodiment is shown, wherein the protrusion 193 includes an annular ring disposed along the outer edge of the first surface, and... Figure 2B Similarly, the diameter of the target support 190 is larger than the rest of the shaft 200. Note that... Figure 2B and 2C The embodiments shown can be combined such that the interior of the first surface has a protrusion 193 and a protrusion positioned along the outer periphery. Figure 2D Showing something similar to Figure 2BIn some embodiments, however, the target holder 190 has the same diameter as the rest of the shaft 200.

[0038] As described above, the shaft 200 or the target support 190 is actively cooled by the cooling system 215, which can be achieved in a variety of different ways.

[0039] Figure 3A-3G Various embodiments are shown in which the shaft 200 is actively cooled. These figures illustrate the shaft 200, which has a first portion located within a cavity 196 and a second portion located in the atmospheric environment, and these two portions are separated by a vacuum seal 197. Note that the dimensions of the first and second portions change as the shaft 200 moves. The remainder of the IHC ion source 10 is as follows... Figure 1 As shown.

[0040] Figure 3A A first embodiment is shown, in which a cooling channel is formed within the shaft 200. The shaft 200 may be made of a material with suitable mechanical strength, thermal stability, and thermal conductivity, such as copper, tungsten, stainless steel, aluminum, or another material. Specifically, an inlet channel 301 is disposed within the shaft 200 and may extend to or near the distal end of the shaft 200. A fluid chiller 300 may be used to allow a cooling fluid (e.g., water or gas) to circulate through the shaft 200. An outlet channel 302 is also disposed in the shaft 200 and attached to the inlet channel 301 to allow cooling fluid to flow from the fluid chiller 300 through the inlet channel 301, the outlet channel 302, and back into the fluid chiller 300. Conduits 304 and 305 may be used to connect the fluid chiller 300 to the inlet channel 301 and the outlet channel 302, respectively. These conduits 304 and 305 may be flexible to allow the shaft 200 to translate while the fluid chiller 300 remains stationary.

[0041] In one embodiment, such as Figure 3A As shown, a large channel is formed in the shaft 200, and a partition 303 is inserted into the shaft 200 to divide the large channel into an inlet channel 301 and an outlet channel 302. Figure 3A The cross-section of the shaft 200 is also shown. In this embodiment, the shaft 200 may be tungsten, while the partition 303 may be stainless steel.

[0042] Figure 3B A cross-section of shaft 200 using cooling fluid according to another embodiment is shown. The rest of the system is as follows. Figure 3AAs shown. In this embodiment, the inlet and outlet channels can be implemented using two concentric tubes of different diameters, wherein the shaft 200 is hollow and forms the outer tube. The inner tube 202 is located inside the outer tube but does not extend to the distal end of the shaft 200. In this embodiment, cooling fluid flows from the fluid chiller 300 through the inner tube 202 to the end of the shaft 200, then flows through the gap 203 between the outer diameter of the inner tube 202 and the inner diameter of the outer tube, and returns to the fluid chiller 300. Alternatively, cooling fluid can flow from the fluid chiller 300 through the gap 203, then through the inner tube 202 and return to the fluid chiller 300.

[0043] Note that, if desired, the shaft 200 may contain more than two channels. In another embodiment, the shaft 200 with cooling channels may be formed using laminated manufacturing. The coolant fluid may be any suitable fluid, such as deionized water or a cooling gas such as nitrogen or air. In some embodiments, the flow rate of the cooling fluid may be greater than 1 L / min. Note that, due to the vacuum seal 197, the fluid chiller 300 is arranged in an atmospheric environment.

[0044] Figure 3C The second embodiment is shown. In this embodiment, the shaft 200 is actively cooled using a fan 320. The fan 320 blows cooling gas, such as air, at a flow rate of up to 10 m / s onto the shaft 200, which may be at room temperature. In some embodiments, such as Figure 3D As shown, instead of using a fan to blow out cooling gas, the shaft 200 is cooled by cooling gas flowing along the direction of the shaft 200 through one or more pipes 340, and the cooling gas is collected by one or more exhaust ports 341. The exhaust ports 341 may include one or more pumps to draw cooling gas through the shaft 200; this design allows for a greater airflow of cooling gas, thereby improving cooling capacity. In both embodiments, the cooling gas flows over the exterior of the shaft 200. In these embodiments, the shaft 200 may be made of aluminum, tungsten, stainless steel, or a different metal alloy, or other materials. In another embodiment, the shaft 200 may be made of copper due to its excellent thermal conductivity. In this embodiment, a sheath 201 made of a non-copper material may be disposed on the outer surface of the shaft 200. Note that in some embodiments, the sheath 201 extends the entire length of the shaft 200. In other embodiments, the sheath 201 may be applied only to the portion of the shaft 200 configured within the cavity 196. The thickness of the sheath 201 may be approximately 1 mm, and it may be made of tungsten or another non-copper material. Note that if the shaft 200 is made of a metal other than copper, the sleeve 201 can also be applied. Furthermore, this sleeve 201 can also be used if needed. Figure 3A , 3B The embodiments shown in 3E, 3F and 3G.

[0045] To further enhance heat transfer, the air-guided portion of shaft 200 may include fins or other structures to increase its surface area.

[0046] Other cooling systems 215 can be used to cool the exterior of the shaft 200. For example, Figure 3E One embodiment is shown in which a cooling pipe 360 ​​is wrapped around a second portion of a shaft 200 located in the atmospheric environment. The cooling pipe 360 ​​is in fluid communication with conduits 304 and 305, which connect the cooling pipe 360 ​​to a fluid chiller 300. Cooling fluid can flow through the cooling pipe 360, thereby cooling the shaft 200. In some embodiments, the cooling fluid may be a gas. Alternatively, the cooling fluid may be a liquid.

[0047] In some embodiments, conduits 304, 305 and cooling pipe 360 ​​are fixed in place such that shaft 200 slides relative to cooling pipe 360, thus the cross-section of shaft 200 in contact with cooling pipe 360 ​​varies based on the position of target support 190. In another embodiment, cooling pipe 360 ​​may be fixed to shaft 200 and thermally coupled via an interface medium (e.g., thermally conductive paste). In this embodiment, conduits 304, 305 may be flexible to allow translation of cooling pipe 360 ​​while the fluid chiller 300 remains stationary.

[0048] Figure 3F Another embodiment of the cooling system 215 is shown. In this embodiment, a cooling plate 330 is fixed to the proximal end of the shaft 200. Note that in this embodiment, the actuator 210 can linearly translate the cooling plate 330 and the shaft 200. This cooling plate 330 can serve as a radiator and can be maintained within a predetermined temperature range. For example, channels can be provided in the cooling plate 330 such that a cooling fluid can flow through the cooling plate 330 and maintain it within the predetermined temperature range; this cooling fluid can be deionized water or a cooling gas, such as nitrogen or air. The conduits 304, 305 connecting the fluid chiller 300 to the channels in the cooling plate 330 can be flexible, allowing them to expand and contract as the cooling plate 330 and the shaft 200 translate toward and away from the arc chamber 100. In some embodiments, the shaft 200 is further cooled by using a fan 320, which provides air cooling. In other embodiments, the fan 320 may not be present. In some embodiments, the shaft 200 is further cooled by using a pipe 340 with complementary exhaust ports 341. In some embodiments, the cooling plate 330 is also located around a portion of the shaft 200, thereby increasing the contact area and cooling efficiency without interfering with the movement of the shaft 200.

[0049] therefore, Figures 3A-3FSome embodiments of a cooling system 215 for cooling shaft 200 are shown, including flowing fluid over the outside of shaft 200, for example by gas cooling. Figure 3C or cooling pipes Figure 3D-3E ), and to allow cooling fluid to flow through the interior of shaft 200, for example, by using channels in shaft 200 ( Figures 3A-3B ) and attachment of the cooling plate 330 fixed to the proximal end of the shaft 200 ( Figure 3F It should be noted that, for each of these embodiments, the cooling device is arranged in an atmospheric environment.

[0050] However, other techniques can also be used to cool the shaft 200. For example, such as... Figure 3G As shown, thermoelectric cooling (e.g., using a heat pump 350, which may be a Peltier heat pump) can also be used to cool the shaft 200. In some embodiments, the heat pump 350 surrounds the shaft 200. In other embodiments, the heat pump 350 is placed at different locations along the shaft 200. The heat pump 350 can be connected to a heat pump power supply 351 using wires 352, which can be long enough to allow the heat pump 350 to move with the shaft 200. Thermoelectric cooling can be implemented around the shaft 200, at the proximal end of the shaft 200, at or near the target holder 190, or a combination thereof. In some embodiments, a thermosiphon or heat pipe is used in or attached to the shaft 200, along with a suitable combination of materials such as copper and water.

[0051] In some embodiments, cooling of the solid dopant material 195 is achieved by directly cooling the target support 190. Figure 4 One embodiment is shown in which conduits 304 and 305 pass through vacuum seal 197 and are located within cavity 196, delivering cooling fluid directly to target holder 190. Channels may exist within the target holder to allow cooling fluid to pass through the interior of target holder 190. In some embodiments, telescopic hose 370 may be used to isolate conduits 304 and 305 from conditions within arc chamber 100.

[0052] In another embodiment, Figure 3G The heat pump 350 is placed at or near the target holder. Note that if the heat pump 350 is placed near the target holder 190, the wire 352 passes through the vacuum seal 197 and enters the cavity 196. The amount of wire 352 arranged within the cavity 196 is such that the wire 352 is properly positioned at the vacuum seal 197, so that there is no relative movement between the wire 352 and the vacuum seal 197 even when the shaft 200 translates. Figure 4 As shown, the flexible conduit 370 can be used to protect the conductor 352. Alternatively, a protective sheath can be provided around the conductor 352.

[0053] This embodiment simplifies the design of shaft 200 at the cost of using flexible telescopic hoses to cool target holder 190. Temperature control and other features of this design are similar to those described herein.

[0054] Therefore, in each of these embodiments, there is a cooling system 215 for cooling the solid dopant material 195. In some embodiments, the cooling system 215 is configured to cool the shaft 200, while in other embodiments, the cooling system 215 is configured to cool the target support. However, in all embodiments, the solid dopant material is actively cooled by the cooling system 215.

[0055] In some embodiments, the amount of cooling provided by the cooling system 215 to the shaft 200 and / or the target holder 190 can be predetermined or established based on one or more parameters. For example, in Figures 3A-3B In the embodiments shown in Figure 4, the flow rate of the cooling fluid through shaft 200 or target support 190 can be fixed. In other embodiments, the flow rate can be set based on the desired temperature range of the solid dopant material 195, the power applied to the cathode 110, the magnetic field power, the desired beam current, and / or other parameters. In some embodiments, the speed of fan 320 (see Figure 4) is also considered. Figure 3C ) or the flow rate of the cooling gas in pipe 340 (see Figure 3D The speed of fan 320 or the flow rate of cooling gas in tube 340 can be fixed. In other embodiments, the speed of fan 320 or the flow rate of cooling gas in tube 340 can be set based on the desired temperature range of solid dopant material 195, the power applied to cathode 110, the magnetic field power, the desired beam current and / or other parameters. Similarly, through Figure 3E The cooling pipes in the 360 ​​and Figure 3F The flow rate of the cooling fluid in the cooling plate 330 can be fixed or set based on the desired temperature range of the solid dopant material 195, the power applied to the cathode 110, the magnetic field power, the required beam current, and / or other parameters. Similarly, the flow rate of the cooling fluid applied to the cathode 110 can be controlled in a similar manner. Figure 3G The heat pump in the middle has a power of 350.

[0056] However, in other embodiments, closed-loop control can be employed. As described above, in some embodiments, a thermocouple 198 may be present in communication with the shaft 200 or the target support 190. The controller 180 can use the output of the thermocouple 198 to control the speed of the fan 320, the flow rate of the cooling gas in the pipe 340, the flow rate of the cooling fluid through the shaft 200 or the target support 190, the flow rate of the cooling fluid through the cooling pipe 360 ​​or the cooling plate 330, or the power supplied to the heat pump 350, to achieve the desired temperature range of the solid dopant material 195.

[0057] While the foregoing disclosure describes cooling the target support and / or shaft in an indirectly heated cathode ion source, this disclosure is not limited to this embodiment. Cooling system 215 can also be used for other ion or plasma sources, such as capacitively coupled plasma sources, inductively coupled plasma sources, Bernas sources, or other suitable sources.

[0058] Figure 5 An ion implanter is illustrated that can utilize any of the ion sources described herein. The ion implanter includes an ion source 500, which can be any of the ion sources described above. As mentioned above, in some embodiments, the ion source 500 can be an IHC ion source. In another embodiment, the ion source 500 can be a radio frequency (RF) ion source. In this embodiment, the RF antenna can be disposed against a dielectric window, which can form part or all of one of the chamber walls. The RF antenna can include a conductive material, such as copper. An RF power supply is electrically connected to the RF antenna, and the RF power supply can provide the RF antenna voltage to the RF antenna. The power provided by the RF power supply can be between 0.1 and 10 kW and can be any suitable frequency, for example, between 1 and 100 MHz. Furthermore, the power provided by the RF power supply can be pulsed. Other embodiments are also possible. For example, plasma can be generated in different ways, such as by a Bernas ion source, a capacitively coupled plasma (CCP) source, a microwave, or an electron-cyclotron-resonance (ECR) ion source. The present invention does not limit the manner in which plasma is generated.

[0059] One chamber wall (referred to as an extraction plate) includes an extraction opening. The extraction opening may be an aperture through which ions 501 generated in the ion source chamber are extracted and directed to the workpiece 590. The extraction opening can be of any suitable shape. In some embodiments, the extraction opening may be elliptical or rectangular.

[0060] Extraction optics 510 are disposed outside the ion source 500 and near the extraction opening. In some embodiments, extraction optics 510 includes one or more electrodes. In some embodiments, extraction optics 510 includes a suppression electrode 511, which is negatively biased relative to the plasma to attract ions through the extraction opening. The suppression electrode 511 can be electrically biased using a suppression power supply. The suppression electrode 511 can be biased to be more negative than the extraction plate of the ion source 500.

[0061] In some embodiments, the extraction optics 510 includes a second electrode 512. The second electrode 512 may be positioned close to the suppression electrode 511, and may be electrically connected to a second electrode power supply. In other embodiments, the second electrode 512 may be electrically grounded, thereby eliminating the need for a second electrode power supply.

[0062] In other embodiments, the extraction optics 510 may include more than two electrodes, such as three or four electrodes. In these embodiments, the electrodes may be similar in function and structure to those described above, but may be biased at different voltages.

[0063] The mass analyzer 520 is located downstream of the extraction optics 510. The mass analyzer 520 uses a magnetic field to guide the path of the extracted ions 501; the magnetic field influences the ion's flight path based on its mass and charge. A mass resolution device 530 with a resolution orifice 531 is positioned at the output or distal end of the mass analyzer 520. By appropriately selecting the magnetic field, only those ions 501 with a selected mass and charge will be guided through the resolution orifice 531; other ions will collide with the walls of the mass resolution device 530 or the mass analyzer 520 and will not travel further in the system.

[0064] One or more beamline assemblies may be disposed downstream of the quality resolution apparatus 530. For example, a collimator 540 may be disposed downstream of the quality resolution apparatus 530. The collimator 540 receives extracted ions 501 passing through the resolution aperture 531 and generates a band-shaped ion beam formed by multiple parallel or nearly parallel sub-beams. In other embodiments, the ion beam may be a point beam. In this embodiment, an electrostatic scanner is used to move the point beam in a first direction, as defined below.

[0065] Downstream of the collimator 540 may be an acceleration / deceleration stage 550. The acceleration / deceleration stage 550 may be an electrostatic filter. The electrostatic filter is a beamline lens assembly configured to independently control the deflection, deceleration, and focusing of the ion beam. Downstream of the acceleration / deceleration stage 550 is a workpiece holder 560.

[0066] The workpiece 590 may be, for example, a silicon wafer, a silicon carbide wafer, or a gallium nitride wafer, and is disposed on the workpiece support 560.

[0067] The embodiments described above in this application offer numerous advantages. The melting temperature of aluminum is approximately 660°C, which can be achieved within the arc chamber 100. The temperature of the solid dopant material 195 can be controlled via the active cooling shaft 200 and / or the target support 190. In some simulations, the temperature of the solid dopant material reached a maximum of below 400°C with a plasma power of 800 W; this maximum temperature can be further reduced by selecting the materials of the cooling system and the shaft. Therefore, the solid dopant material 195 can be inserted into the arc chamber 100, and the possibility of melting can be reduced or eliminated through the use of active cooling.

[0068] The scope of this disclosure is not limited to the specific embodiments described herein. In fact, based on the foregoing description and drawings, various other embodiments and modifications of this disclosure will become apparent to those skilled in the art, in addition to those described herein. Therefore, these other embodiments and modifications are all intended to fall within the scope of this disclosure. Furthermore, although this disclosure has been set forth herein for a specific purpose, in a specific setting, and in the context of a specific implementation, those skilled in the art will recognize that its effectiveness is not limited thereto and that this disclosure can be advantageously practiced for any number of purposes and in any number of settings. Therefore, the claims should be interpreted in accordance with the full scope and spirit of the invention as set forth herein.

Claims

1. An ion source for generating an ion beam, comprising: An electric arc chamber includes multiple walls connecting a first end and a second end; Target scaffold, used to hold solid dopant materials; axis; Connect the target support to extend the target support into the arc chamber; as well as A cooling system for actively cooling the solid dopant material.

2. The ion source according to claim 1, wherein the cooling system actively cools the shaft.

3. The ion source of claim 2, wherein the shaft is made of copper, and at least a portion of the shaft is covered by a sheath made of a non-copper material.

4. The ion source of claim 2, wherein the shaft is cooled using a cooling fluid.

5. The ion source according to claim 4, wherein the shaft includes a hollow cavity, the hollow cavity including an inlet channel and an outlet channel, such that the cooling fluid flows through the interior of the shaft.

6. The ion source according to claim 5, wherein the partition is located within the hollow cavity and separates the inlet channel from the outlet channel.

7. The ion source of claim 5, wherein the shaft comprises two tubes, the hollow cavity defining an outer tube, and an inner tube disposed within the outer tube and not extending to the distal end of the shaft, wherein the two tubes form the inlet channel and the outlet channel.

8. The ion source of claim 2, wherein the shaft is cooled by directing a cooling gas flow to the outside of the shaft.

9. The ion source of claim 2 further includes a cooling pipe in fluid communication with a fluid chiller, wherein the cooling pipe is wound around a portion of the shaft.

10. The ion source according to claim 2 further includes a cooling plate fixed to the proximal end of the shaft, wherein the cooling plate serves as a heat sink.

11. The ion source of claim 10, wherein the channel is disposed in the cooling plate and cooling fluid flows through the cooling plate to maintain the cooling plate within a predetermined temperature range.

12. The ion source of claim 1, wherein the shaft and / or the target support is actively cooled by using a heat pump attached thereto.

13. The ion source of claim 1, wherein the target support is actively cooled using a cooling fluid flowing through the target support.

14. An ion implanter, comprising: An ion source used to generate an ion beam; as well as One or more beam-guided assemblies guide the ion beam to the workpiece. The ion source includes: An electric arc chamber includes multiple walls connecting a first end and a second end; Target scaffold, used to hold solid dopant materials; Axis; connecting the target support to extend the target support into the arc chamber; and A cooling system for actively cooling the solid dopant material.

15. The ion implanter according to claim 14, further comprising: Thermocouples are used to measure the temperature of the solid dopant material; A controller, wherein the controller uses information from the thermocouple to maintain the solid dopant material within a desired temperature range.

16. The ion implanter of claim 15, wherein the controller actively cools the shaft to maintain the solid dopant material within the desired temperature range.

17. The ion implanter of claim 15, wherein the shaft is cooled by a fluid flowing through the interior of the shaft or a fluid flowing through the exterior of the shaft, and the controller controls the temperature of the solid dopant material by controlling the flow rate of the fluid.

18. The ion implanter of claim 15, wherein the shaft is cooled by attaching a cooling plate to the proximal end of the shaft, and the controller controls the temperature of the solid dopant material by controlling the temperature of the cooling plate.

19. The ion implanter of claim 15, wherein the shaft and / or the target support is cooled by attaching one or more heat pumps, and the controller controls the temperature of the solid dopant material by controlling the power supplied to the one or more heat pumps.

20. The ion implanter of claim 15, wherein the target support is cooled by a fluid flowing through the interior of the target support, wherein the controller controls the temperature of the solid dopant material by controlling the flow rate of the fluid.

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