Molten liquid delivery for adjustable gasification in ion sources

Abstract

An ion source having a crucible is disclosed. In some embodiments, the crucible comprises a solid dopant material, such as a metal. A porous wicking tip in contact with the solid dopant material is disposed in the crucible. The porous wicking tip may be a tube having one or more internal conduits. Alternatively, the porous tip may be two concentric cylinders with a plurality of rods disposed in an annular ring between the two cylinders. Alternatively, the porous tip may be one or more foil layers wound together. In each of these embodiments, the wicking tip may be used to control the flow rate of the molten dopant material to the arc chamber.

Description

[0001] This application claims priority to U.S. patent application serial number 17 / 835,107 filed on June 8, 2022, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0002] Embodiments of the present disclosure relate to an ion source, and more particularly to an ion source having a crucible with a porous wicking tip. Background Art

[0003] Various types of ion sources can be used to form ions used in semiconductor processing equipment. For example, an indirectly heated cathode (IHC) ion source operates by supplying an electric current to a filament disposed behind the cathode. The filament emits hot ion electrons, which accelerate toward the cathode and heat the cathode, which in turn causes the cathode to emit electrons into an arc chamber of the ion source. The cathode is disposed at one end of the arc chamber. A repeller is typically disposed on the end of the arc chamber opposite the cathode. A bias voltage can be applied to the cathode and repeller to repel the electrons, thereby directing the electrons back toward the center of the arc chamber. In some embodiments, a magnetic field is used to further confine the electrons within the arc chamber.

[0004] In certain embodiments, it may be desirable to utilize a feed material in solid form as the dopant species. However, there are problems associated with using solid feeds with IHC ion sources. For example, vaporizers used with ion sources are difficult to operate at temperatures greater than 750 degrees Celsius. In addition, there may be problems with heat shielding and condensation in the tubes connecting the vaporizer to the arc chamber. These problems may prevent the use of many solids in the vaporizer because the vapor pressure of many of the solids at 750 degrees Celsius is too low. There may also be problems with introducing solid feeds into the ion source. Problems such as spillage and unregulated vaporization may occur.

[0005] Therefore, an ion source that can be used with solid feeds without these limitations would be beneficial. Additionally, it would be advantageous to be able to tune or adjust the gasification rate. Summary of the invention

[0006] An ion source having a crucible is disclosed. In some embodiments, the crucible contains a solid dopant material, such as a metal. This material can be a crystal, a lump, a powder, or a compound material. A porous wicking tip is disposed in the crucible in contact with the solid dopant material. The porous wicking tip can be a tube having one or more internal conduits. Alternatively, the porous tip can be two concentric cylinders with a plurality of rods disposed in an annular ring between the two cylinders. Alternatively, the porous tip can be one or more foil layers wound together. In each of these embodiments, the wicking tip can be used to control the flow rate of the molten dopant material into the arc chamber.

[0007] According to one embodiment, a device for containing a dopant material in an ion source is disclosed. The device includes: a crucible; and a wicking tip disposed in the crucible, wherein the wicking tip includes a body, one or more openings, and a wicking cavity, the body having one or more internal conduits; the one or more openings connect the one or more internal conduits to the outside of the body and the inside of the crucible; the wicking cavity is disposed at the front end of the wicking tip, wherein the one or more internal conduits flow into the wicking cavity. In some embodiments, the body includes a cylindrical portion including a plurality of internal conduits. In certain embodiments, a portion of the body includes a main outer diameter, the main outer diameter being defined such that the plurality of internal conduits are completely contained within the portion having the main outer diameter, and wherein a conveying ring is disposed on the other portion of the body to form the one or more openings, the conveying ring being a region having a diameter smaller than the main outer diameter. In certain embodiments, the cross-sectional area of ​​the passage where the plurality of internal conduits connect to the wicking cavity is smaller than the combined cross-sectional area of ​​the plurality of internal conduits, thereby forming a choke point. In some embodiments, the combined cross-sectional area of ​​the multiple internal conduits is 3 to 12 times larger than the cross-sectional area of ​​the passage where the multiple internal conduits are connected to the wicking cavity. In some embodiments, the body and the one or more internal conduits are curved. In some embodiments, the wicking cavity comprises a concave cavity. In some embodiments, the body comprises only one internal conduit. In some embodiments, the body comprises a hollow outer cylinder and a solid inner cylinder, wherein an annular ring is formed between the hollow outer cylinder and the solid inner cylinder, wherein the wicking tip also comprises a rod disposed in the annular ring, wherein the spacing between the rods in the annular ring comprises the one or more internal conduits. In some embodiments, the body comprises a foil, which is wound to form the body; wherein the spacing between adjacent layers of the foil comprises the one or more internal conduits.

[0008] According to another embodiment, an indirectly heated cathode ion source is disclosed. The IHC ion source comprises: an arc chamber having a first end and a second end; a cathode disposed on the first end; and the above-described apparatus disposed at the second end.

[0009] According to another embodiment, an indirect heated cathode ion source is disclosed. The IHC ion source includes: an arc chamber having a first end, a second end, and a side wall connecting the first end and the second end; a cathode disposed on the first end; an actuator adapted to extend into and retract from the arc chamber; and the above-mentioned device disposed on an end of the actuator.

[0010] According to another embodiment, an apparatus for containing a dopant material in an ion source is disclosed. The apparatus includes: a crucible; and a wicking tip disposed in the crucible, wherein the wicking tip includes a solid inner cylinder and a plurality of rods, the solid inner cylinder being disposed in a hollow outer cylinder to form an annular ring; the plurality of rods being disposed in the annular ring. In some embodiments, the spacing between the plurality of rods forms an inner conduit through which the dopant material travels. In some embodiments, the plurality of rods extend beyond the hollow outer cylinder at the rear end of the wicking tip to provide an opening so that the dopant material can enter the inner conduit. In some embodiments, the hollow outer cylinder extends further than the plurality of rods at the front end to form a cavity into which the dopant material from the inner conduit is collected. In some embodiments, the plurality of rods comprise tantalum, a refractory metal, or a high temperature wire.

[0011] According to another embodiment, an indirectly heated cathode ion source is disclosed. The IHC ion source comprises: an arc chamber having a first end and a second end; a cathode disposed on the first end; and the above-described apparatus disposed at the second end.

[0012] According to another embodiment, an indirect heated cathode ion source is disclosed. The IHC ion source includes: an arc chamber having a first end, a second end, and a side wall connecting the first end and the second end; a cathode disposed on the first end; an actuator adapted to extend into and retract from the arc chamber; and the above-mentioned device disposed on an end of the actuator. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] For a better understanding of the present disclosure, reference is made to the accompanying drawings, which are incorporated herein by reference and in which:

[0014] Figure 1 is an indirectly heated cathode (IHC) ion source having a crucible with a wicking tip according to one embodiment.

[0015] Figure 2Ais an indirectly heated cathode (IHC) ion source having a crucible with a wicking tip in an extended position according to another embodiment.

[0016] Figure 2B is a crucible with a wicking tip in a retracted position Figure 2A An indirectly heated cathode (IHC) ion source is shown.

[0017] Figures 3A-3E A wicking tip according to one embodiment is shown.

[0018] Figures 4A-4B The crucible is shown in Figures 3A-3E Wicking tip shown.

[0019] Figure 4C Show Figure 3A A variation of the wicking tip shown in .

[0020] Figure 4D The crucible is shown in Figures 3A-3E Variations of the wicking tip shown.

[0021] Figure 4E Show Figures 3A-3E Another variation of the wicking tip is shown.

[0022] Figures 5A-5C A wicking tip according to another embodiment is shown.

[0023] Figures 6A-6F A wicking tip according to another embodiment is shown. DETAILED DESCRIPTION

[0024] As described above, a crucible having a wicking tip is disclosed. There are multiple embodiments of the wicking tip.

[0025] There are multiple embodiments of IHC ion sources that can be used with a wicking tip. One of these embodiments includes a crucible located on the second end of the arc chamber. A second embodiment includes a crucible disposed on the side wall. Each of these embodiments will be described in more detail.

[0026] Figure 1A first embodiment of an IHC ion source 10 having a crucible with a wicking tip is shown, the crucible being disposed at a second end. The IHC ion source 10 includes an arc chamber 100, the arc chamber 100 including two opposing ends and a sidewall 101 connected to the ends. The arc chamber 100 also includes a bottom wall and a top wall. The walls of the arc chamber 100 may be constructed of a conductive material and may be electrically connected to each other. 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. The filament 160 is in communication with a filament power supply 165. The filament power supply 165 is configured to pass an electric current through the filament 160 so that the filament 160 emits hot ion electrons. The cathode bias power supply 115 applies a negative bias to the filament 160 relative to the cathode 110 to accelerate the thermionic electrons from the filament 160 toward the cathode 110 and heat the cathode 110 when the thermionic electrons strike the rear surface of the cathode 110. The cathode bias power supply 115 may bias the filament 160 so that the filament 160 has a voltage between, for example, 200 volts (V) and 1500 V negative of the voltage of the cathode 110. The cathode 110 then emits thermionic electrons into the arc chamber 100 on its front surface.

[0027] Thus, the filament power supply 165 supplies current to the filament 160. The cathode bias power supply 115 biases the filament 160 so that the filament 160 has a negative value than the cathode 110, thereby attracting electrons from the filament 160 toward the cathode 110. In some embodiments, the cathode 110 may be biased relative to the arc chamber 100, for example, by the bias power supply 111. In other embodiments, the cathode 110 may be electrically connected to the arc chamber 100 to be at the same voltage as the sidewalls of the arc chamber 100. In these embodiments, the bias power supply 111 may not be employed and the cathode 110 may be electrically connected to the sidewalls of the arc chamber 100. In some embodiments, the arc chamber 100 is connected to an electrical ground.

[0028] In this embodiment, the crucible 120 is disposed in the arc chamber 100 on the second end 105 of the arc chamber 100 opposite the cathode 110. The crucible 120 may be made of a conductive material and may be electrically connected to the sidewall of the arc chamber 100. The top of the crucible 120 may be flush with the second end 105.

[0029] In certain embodiments, a magnetic field 190 is generated in the arc chamber 100. This magnetic field is intended to confine electrons in one direction. The magnetic field 190 is generally parallel to the sidewall 101 from the first end 104 to the second end 105. For example, the electrons may be confined in a column parallel to the direction from the cathode 110 to the crucible 120 (i.e., the y-direction). Thus, the electrons do not experience any electromagnetic forces to move in the y-direction. However, the movement of electrons in other directions may experience electromagnetic forces.

[0030] exist Figure 1 In the embodiment shown in , the first electrode 130a and the second electrode 130b can be disposed on respective opposite sidewalls 101 of the arc chamber 100 such that the first electrode 130a and the second electrode 130b are located within the arc chamber 100. The first electrode 130a and the second electrode 130b can each be biased by a respective power supply. In certain embodiments, the first electrode 130a and the second electrode 130b can be in communication with a common power supply. However, in other embodiments, to enable maximum flexibility and capability to tune the output of the IHC ion source 10, the first electrode 130a can be in communication with a first electrode power supply 135a, and the second electrode 130b can be in communication with a second electrode power supply 135b.

[0031] The first electrode power supply 135a and the second electrode power supply 135b are used to bias the first electrode 130a and the second electrode 130b, respectively, relative to the sidewall of the arc chamber 100. In some embodiments, the first electrode power supply 135a and the second electrode power supply 135b can bias the first electrode 130a and the second electrode 130b positively or negatively relative to the sidewall 101 of the arc chamber 100. In some embodiments, at least one of the electrodes can be biased between 40 volts and 500 volts relative to the sidewall 101 of the arc chamber 100.

[0032] Each of the cathode 110 , the crucible 120 , and the electrodes is made of a conductive material such as metal or graphite.

[0033] On the other side of the arc chamber 100, referred to as the face plate 103, an extraction aperture 140 may be provided. Figure 1 In the embodiment of the present invention, the extraction orifice 140 is arranged on a side parallel to the XY plane (parallel to the page). In addition, the IHC ion source 10 further comprises a gas inlet 106 through which the gas to be ionized is introduced into the arc chamber 100 .

[0034] The controller 180 may be in communication with one or more of the power supplies so that the voltage or current supplied by these power supplies can be changed. The controller 180 may include a processing unit, such as a microcontroller, a personal computer, a dedicated controller, or another suitable processing unit. The controller 180 may also include a non-transitory storage element, such as a semiconductor memory, a magnetic memory, or another suitable memory. This non-transitory storage element may contain instructions and other data that enable the controller 180 to perform the functions described herein.

[0035] A dopant material 125 (e.g., indium, aluminum, antimony, or gallium) may be disposed within the crucible 120. When placed in the crucible 120, the dopant material 125 may be in solid form. In some embodiments, the dopant material 125 may be a crystal, a lump, a powder, or a compound material. However, in certain embodiments, the dopant material 125 may be melted and become liquid. Therefore, in certain embodiments, the ion source 10 is configured such that the crucible 120 is located on the lowest side (i.e., the side closest to the ground) so that the molten dopant material does not flow from the crucible 120 into the arc chamber 100, but remains in the crucible 120. In other words, the ion source 10 is oriented such that the dopant material 125 is retained in the crucible 120 by gravity.

[0036] The wicking tip 170 is disposed in the crucible 120. The wicking tip 170 extends into the crucible 120. In some embodiments, the wicking tip 170 extends to the bottom of the crucible so that the dopant material 125 remains in contact with the wicking tip 170 even when the dopant material is consumed. The crucible 120 may include a front surface that forms a crucible cavity 121. This crucible cavity 121 may be concave or another inward depression. The front surface refers to the surface that communicates with the interior of the arc chamber 100. In some embodiments, the wicking tip 170 includes a wicking cavity 171. The wicking cavity 171 may be concave. However, it should be understood that other shapes may also be used. For example, the wicking cavity 171 may be a counterbore having different shapes. Any inward depression or hole on the front surface may be used as the wicking cavity 171. In some embodiments, both the crucible 120 and the wicking tip 170 have concave cavities. In each of the embodiments, heat from the plasma draws molten dopant material toward the arc chamber. As the dopant material 125 travels upward along the wicking tip 170, the dopant material 125 fills the wicking cavity 171. If excess dopant material fills the wicking cavity 171, a meniscus may form. The introduction of additional dopant material may cause the dopant material to flow from the wicking cavity 171 into the crucible cavity 121. Both of these cavities may be in direct contact with the interior of the arc chamber 100. This facilitates vaporization of the dopant material in the crucible cavity 121 and the wicking cavity 171. In addition, the design of the wicking tip 170 controls the rate at which the dopant material 125 travels upward along the wicking tip 170, thereby controlling the rate at which the dopant material 125 vaporizes.

[0037] During operation, the filament power supply 165 passes an electric current through the filament 160, which causes the filament 160 to emit thermionic electrons. These electrons strike the rear surface of the cathode 110, which may have a more positive value than the filament 160, causing the cathode 110 to be heated, which in turn causes the cathode 110 to emit electrons into the arc chamber 100. These electrons collide with molecules of a gas fed into the arc chamber 100 through the gas inlet 106. A carrier gas (e.g., argon) or an etching gas (e.g., a halogen-containing gas) may be introduced into the arc chamber 100 through the appropriately positioned gas inlet 106. The combination of the electrons from the cathode 110, the gas, and the positive potential forms a plasma 145. The plasma 145 may be confined and manipulated by the electric field formed by the first electrode 130a and the second electrode 130b. Furthermore, in some embodiments, the electrons and positive ions may be confined to some extent by the magnetic field 190. In some embodiments, the plasma 145 is confined near the center of the arc chamber 100, near the extraction orifice 140. In some embodiments, the plasma 145 may be biased at a voltage close to the average of the voltage applied to the first electrode 130a and the voltage applied to the second electrode 130b. The heat within the plasma 145 melts the dopant material 125 in the crucible 120 to form a liquid. The heat draws the liquid toward the arc chamber so that it travels up the wicking tip 170 and flows into the wicking cavity 171. The liquid dopant material is vaporized once it enters the wicking cavity 171, and ions from the dopant material are generated and become part of the plasma 145. Alternatively, some of the liquid dopant material may flow from the wicking cavity 171 into the crucible cavity 121, where it is vaporized.

[0038] In some embodiments, the voltage of cathode 110 has a value that is less positive than the voltage of plasma 145. For example, in one embodiment, cathode 110 can be at the same voltage as the sidewalls of arc chamber 100. First electrode 130a can be biased at 150V, while second electrode 130b can be biased at 0V or 20V. Thus, electrons generated by cathode 110 are attracted toward plasma 145. In some embodiments, these emitted electrons or other particles can also strike dopant material 125, causing dopant material 125 to be sputtered.

[0039] although Figure 1Two electrodes are shown, but it should be understood that in some embodiments, one of these electrodes (e.g., second electrode 130b) and second electrode power supply 135b associated with second electrode 130b can be eliminated. In another embodiment, second electrode 130b is disposed within arc chamber 100 but is electrically connected to sidewall 101 of arc chamber 100. Therefore, in this embodiment, second electrode power supply 135b can be eliminated.

[0040] Figure 2A-2B A second embodiment of an IHC ion source 12 utilizing a crucible 120 having a wicking tip 170 is shown. Many of the components in this IHC ion source 12 are identical to those in the first embodiment and have been given identical reference identifiers. Figure 1 Unlike the IHC ion source 10 shown in FIG. 1 , in this embodiment, the repeller 150 is disposed on the second end 105 opposite the first end 104. The repeller 150 may be biased relative to the arc chamber 100 using a repeller bias power supply 153. In other embodiments, the repeller 150 may be electrically connected to the arc chamber 100 to be at the same voltage as the wall of the arc chamber 100. In these embodiments, the repeller bias power supply 153 may not be employed and the repeller 150 may be electrically connected to the wall of the arc chamber 100. In still other embodiments, the repeller 150 is not employed. The repeller 150 is made of a conductive material (e.g., metal or graphite).

[0041] In this embodiment, the crucible 120 is in communication with one end of the actuator 195 . Figure 2A The actuator 195 is shown in an extended position so that the crucible 120 is disposed within the interior of the arc chamber 100. The opposite end of the actuator 195 can be in communication with a support 197. In certain embodiments, this support 197 can be the housing of the IHC ion source 12. In certain embodiments, the actuator 195 may be capable of varying the overall displacement of the crucible 120. For example, the actuator 195 can be a telescoping design.

[0042] Figure 2B The IHC ion source 12 is shown with the actuator 195 in a retracted position. In this position, the crucible 120 is completely outside the arc chamber 100. In certain embodiments, the dopant material 125 cools while the crucible 120 is outside the arc chamber 100. In this manner, no dopant material 125 enters the arc chamber 100 when the actuator 195 is in the retracted position.

[0043] The crucible 120 enters the interior of the arc chamber 100 through one of the plurality of side walls 101 connecting the first end 104 and the second end 105. In some embodiments, the crucible 120 may enter the interior of the arc chamber 100 through the side wall opposite to the extraction orifice 140. In other embodiments, the crucible 120 may enter the interior of the arc chamber 100 through the side wall adjacent to the panel 103.

[0044] The wicking tip 170 is disposed in the crucible 120. The wicking tip 170 extends into the crucible 120. In some embodiments, the wicking tip 170 extends to the bottom of the crucible so that the dopant material 125 remains in contact with the wicking tip 170 even when the dopant material is being consumed. The crucible 120 may include a front surface forming a crucible cavity 121. In certain embodiments, the wicking tip 170 includes a wicking cavity 171. In some embodiments, both the crucible and the wicking tip have cavities. In each of the embodiments, as the dopant material 125 travels upward along the wicking tip 170, the dopant material 125 fills into the wicking cavity 171. If excess dopant material fills into the wicking cavity 171, a meniscus may be formed. The introduction of additional dopant material may cause the dopant material to flow from the wicking cavity 171 into the crucible cavity 121. Both cavities may be in direct contact with the interior of the arc chamber 100. This facilitates vaporizing the dopant material in the crucible cavity 121 and the wicking cavity 171. Additionally, the design of the wicking tip 170 controls the rate at which the dopant material 125 can travel up the wicking tip 170, thereby controlling the rate at which the dopant material 125 is vaporized.

[0045] Figures 3A-3E A first embodiment of a wicking tip 170 is shown. In this embodiment, the wicking tip 170 includes a wicking tube 200. Figure 3A-3B As shown in FIG. 1 , the wick tube 200 may be a cylindrical body having a length and a main outer diameter. One or more conveying rings 210 are included along the length of the wick tube 200. The conveying ring 210 is a region having an outer diameter that is smaller than the main outer diameter. In some embodiments, the main outer diameter 231 (see FIG. 1 ) is a cylindrical body having a length and a main outer diameter. Figure 3D ) is between 0.125 inches and 0.75 inches, and the outer diameter of the delivery ring 210 is between 0.087 inches and 0.62 inches. The height of the delivery ring 210 is not limited, but can be between 0.25 inches and 2.0 inches depending on the desired flow rate. Specifically, increasing the height of the delivery ring 210 increases the size of the opening that connects the exterior of the wicking tube 200 to the conduit 220.

[0046] Within the wick tube 200 are one or more conduits 220. The diameter of these conduits 220 may vary and in some embodiments may be between 0.062 inches and 0.250 inches. These conduits 220 are completely contained within the main outer diameter 231, such as Figure 3B A top view of Figure 3D In other words, if the entire wick tube 200 has a diameter equal to the major outer diameter 231, the conduit 220 will be completely within the cylindrical body. However, the outer diameter of the delivery ring 210 (in Figure 3E The diameter 232 (shown in FIG. 2 ) is smaller than the diameter required to accommodate the conduit 220. Therefore, the delivery ring 210 cuts into the conduit 220, thereby forming an opening 250 that enables a path from the outside of the wicking tube 200 to the conduit 220.

[0047] Figure 3D-3E Also shown is a wicking cavity 230. Where the wicking cavity 230 overlaps the conduits 220, channels are formed from the conduits 220 to the wicking cavity 230. Since the cross-sectional area of ​​these channels is smaller than the combined cross-sectional area of ​​the plurality of conduits 220, choke points are formed. The size of the choke point and the ratio of the cross-sectional area of ​​the channel to the combined cross-sectional area of ​​the plurality of conduits 220 can determine the flow rate of the dopant material to the wicking cavity 230.

[0048] There may be more than one conduit 220 within the wicking tube 200. In this way, a portion of the wicking tube 200 is even present in the region of the transport ring 210.

[0049] In another embodiment, only one conduit 220 may be used. In this embodiment, an opening 250 may be formed along the length of the wicking tube 200 in a radial direction rather than using a transfer ring to form the opening 250 to connect the outside of the wicking tube 200 to the conduit 220, such as Figure 4D The openings 250 may be tapered, thereby increasing the amount of material that may enter each opening 250 .

[0050] Figure 4E Shown in Figure 4D In this figure, there are multiple lower wicking tubes 201 that merge into upper wicking tubes 202. Figure 4D As shown in FIG. 2 , the lower wick tube 201 has an opening 250. Figure 4D Similar to the conduits in the lower wicking tube 201, the lower wicking tube 201 also has one or more conduits 220. These conduits 220 then enter the upper wicking tube 202 and may remain in the upper wicking tube 202 as separate conduits. In other embodiments, the conduits 220 may merge into one of the conduits in the upper wicking tube 202. At the top of the upper wicking tube 202, the conduits 220 are connected to the wicking cavity 230.

[0051] The wick tube 200 may be made of any suitable material, such as graphite or a refractory metal such as tungsten, tantalum, or molybdenum. The length of the wick tube 200 may be determined based on the depth of the crucible 120. The diameter of the conduit 220 may be selected to control the rate at which the liquid dopant material travels to the wicking cavity 230. A larger diameter would enable more material to be delivered and would also increase the size of the opening that connects the exterior of the wick tube 200 to the conduit 220. Furthermore, the number of conduits may be adjustable.

[0052] like Figure 3C As shown in , in all of these embodiments, the front surface of the wicking tube 200 may include a wicking cavity 230. The term "front surface" refers to the surface that is in communication with the arc chamber 100. The wicking cavity 230 may be concave. However, it should be understood that other shapes may also be used. For example, the wicking cavity 230 may be a countersunk hole with different shapes. Any inward depression or hole on the front surface may be used as the wicking cavity 230. As the molten dopant material 125 travels upward along the conduit 220, the molten dopant material 125 is collected in the wicking cavity 230. The depth, shape, and radius of the wicking cavity 230 may be selected based on the amount of molten dopant material to be exposed to the plasma. A deeper wicking cavity 230 can accommodate more dopant material, thereby resulting in a higher concentration of dopant ions in the plasma.

[0053] In certain embodiments, the conduit 220 may pass through the entire length of the wicking tube 200 from the wicking cavity 230 to the distal end. In other embodiments, the rear end of the wicking tube 200 may be closed so that the conduit 220 is not exposed on the rear end. The term "rear end" refers to the end of the wicking tube 200 opposite to the front surface. However, in all embodiments, the wicking tube 200 includes a structure having one or more conduits 220 disposed within the wicking tube 200. These conduits 220 are connected to the wicking cavity 230 disposed at the front surface of the wicking tube 200. One or more openings 250 may be provided along the length of the wicking tube 200 that connects the outside of the wicking tube 200 to the conduit 220. The number and size of the conduits 220 and the openings can help determine the rate at which the dopant material travels to the wicking cavity 230.

[0054] In addition, despite Figures 3A-3E The wick tube 200 is shown as having a cylindrical body, however other shapes are possible. For example, the wick tube 200 can be a rectangular prism or other shape.

[0055] Figure 4A The embodiment of the present invention is shown in the crucible 120 partially filled with the dopant material 125. Figures 3A-3EWicking tube 200 is shown. Note that in operation, dopant material 125 melts, enters opening 250 along transfer ring 210, and travels up conduit 220 to wicking cavity 230 which communicates with arc chamber 100. Figure 4A The orientation shown in Figure 1 , wherein the crucible 120 is maintained in an upright or vertical position. In this embodiment, the central axis of the wick tube 200 may be coaxial with the central axis of the crucible 120, so that the wick tube 200 is located in the center of the crucible 120 in the radial direction. In these embodiments, the crucible 120 may be a hollow cylinder or a hollow rectangular prism. In other embodiments, the crucible 120 may be tapered so that the top of the crucible is wider than the bottom of the crucible 120.

[0056] Figure 4B Shows orientation in the horizontal direction (e.g. Figure 2A-2B In one embodiment, the wick tube 200 is disposed in the crucible 120 (oriented in the embodiment shown in FIG. 1 ). In this embodiment, it may be beneficial to offset the wick tube 200 relative to the central axis of the crucible 120. In this way, the dopant material 125 may remain in contact with the wick tube 200 even when the dopant material 125 is being consumed. If desired, the wick tube 200 may be disposed in the crucible 120 so that the wick tube 200 contacts or is close to the lowest side of the crucible 120. In these embodiments, the crucible 120 may be a hollow cylinder or a hollow rectangular prism. In other embodiments, the crucible 120 may be tapered so that the top of the crucible is wider than the bottom of the crucible 120. By using a tapered shape, the dopant material 125 may be sucked toward the top of the crucible 120 due to the sloping walls of the crucible 120. The front surface of the crucible 120 may have a cavity, which may be concave, convex, or a fine surface that enables any overflow of the dopant material 125 from the wicking cavity 230 to be retained.

[0057] Figure 4C Shows that Figure 4B 120. In this embodiment, the shape of the wick tube 240 is changed to accommodate the horizontal orientation rather than moving the position of the wicking cavity 230 within the crucible 120. In this embodiment, the body of the wick tube 240 is curved. The conduit 220 within the body will be similarly curved. This configuration positions the front surface of the wick tube 200 (i.e., the wicking cavity 230) along the central axis of the crucible 120 while also allowing at least a portion of the wick tube to be close to the lowest side of the crucible 120.

[0058] Figure 4DA different configuration of the wick tube 200 is shown. In this embodiment, rather than using a delivery ring 210, the cross-sectional area of ​​the body of the wick tube may be constant over at least a portion of the entire length of the wick tube. Openings 250 are provided in the wick tube 200 that communicate with the one or more conduits 220 provided within the cylindrical body of the wick tube 200. As described above, these openings may be tapered to increase the amount of material that can enter each opening 250.

[0059] Figures 5A-5C A wicking tip according to another embodiment is shown. In this embodiment, the wicking tip is configured as a wicking wire assembly 300. Figure 5C A cross-sectional view of a wicking wire assembly 300 is shown. The wicking wire assembly 300 includes a solid inner cylinder 320 disposed in an outer hollow cylinder 310. The cylinder may be constructed of graphite, ceramic, high temperature material, or refractory metal. In an annular ring 340 between the outer hollow cylinder 310 and the solid inner cylinder 320, a plurality of rods 330 are disposed. In one embodiment, the diameter of each of the rods 330 is approximately equal to the width of the annular ring 340. In other embodiments, a plurality of rods 330 may be disposed in the annular ring 340 in a radial direction. The rods 330 are constructed of graphite or refractory metals (e.g., tantalum or tungsten). Although other shapes are possible as long as a space is formed between the rods 330, the rods 330 may have a circular cross section. The space between the rods 330 in the annular ring 340 provides a conduit for the molten dopant material to travel toward the top of the wicking wire assembly 300. In one embodiment, the top end of the rod 330 terminates at a front end before the end of the outer hollow cylinder 310. This forms a wicking cavity at the front end of the wicking wire assembly 300 in which the molten dopant material 125 can be collected. In certain embodiments, the solid inner cylinder 320 can extend beyond the outer hollow cylinder 310 in the front end so that the solid inner cylinder 320 extends into the arc chamber 100. This serves to further heat the solid inner cylinder 320, which helps melt the dopant material 125. In this embodiment, the wicking cavity can be annular in shape. In some embodiments, the rod 330 and the solid inner cylinder 320 extend further in the bottom direction than the outer hollow cylinder 310. By terminating the outer hollow cylinder 310 in the bottom direction before the rod 330 and the solid inner cylinder 320, more surface area can be used to allow the molten dopant material 125 to enter the annular ring 340. The region where the outer hollow cylinder 310 is absent enables the rod 330 to come into direct contact with the dopant material located outside the wicking wire assembly 300. Thus, this region acts as an opening that enables the molten dopant material to enter the inner conduit.

[0060] In some embodiments, the rods 330 may be tantalum wire. In operation, the dopant material 125 melts, enters the space between the rods 330 and travels between the rods 330 in the annular ring 340 to a cavity in communication with the arc chamber 100. The rods 330 may have a diameter between 0.005 inches and 0.125 inches. The annular ring 340 may have a width between 0.125 inches and 0.750 inches. In some embodiments, there may be three to one hundred rods 330 disposed in the annular ring 340. The rods 330 may have the same length or the length may be different. The length may be between 0.5 inches and 2.0 inches.

[0061] Figure 5A The orientation shown in Figure 1 , wherein the crucible 120 is maintained in an upright or vertical position. As described above, the crucible 120 may include a crucible cavity 121 at the front surface of the crucible 120. The rod 330 may extend entirely or substantially to the bottom of the crucible 120 so that the rod 330 is in contact with the dopant material even when the dopant material is being consumed.

[0062] Figure 5B The orientation shown in Figure 2A-2B , wherein the crucible 120 is maintained in a horizontal position. In this embodiment, the wicking wire assembly 300 is disposed within the crucible 120 such that the bottom of the wicking wire assembly 300 contacts the lowermost wall of the crucible 120. Thus, the wicking wire assembly 300 can be disposed at an angle. This enables the molten dopant material to still contact the rod 330 of the wicking wire assembly 300 even after some of the dopant material has been consumed.

[0063] Thus, in this embodiment, the space in the annular ring 340 between the rods 330 acts as a conduit through which the molten dopant material can move. The width of the annular ring and the size and type of the rods determine the rate at which the molten dopant material moves to the front surface of the wicking wire assembly 300.

[0064] Figures 6A-6F Another embodiment of the wicking tip 170 is shown. In this embodiment, the foil 400 is rolled to form a porous cylinder. When rolled, the foil 400 includes multiple foil layers. The term "foil" is used to refer to a sheet of material having a thickness between about 0.005 inches and 0.050 inches. The material used to form the "foil" or "foil layer" can be a refractory metal. The foil 400 can be a rectangular sheet with a plurality of holes 410, such as Fig. 6A As shown in FIG. 4 , holes 410 allow molten dopant material to move between adjacent layers in foil 400. Alternatively, as Figure 6BAs shown in , the foil 400 may have a rectangular sheet with a hole 410 and a protrusion 420. When the foil is rolled, the protrusion 420 tends to ensure a minimum separation or spacing between adjacent layers. In this way, when the foil includes the protrusion 420, the layers of the foil 400 can be further spaced apart. The protrusion 420 can be utilized with metal foils that tend to be very smooth to introduce minimum spacing between layers. In another embodiment, the foil 400 may have the protrusion 420 and may not have a hole. The protrusion 420 may extend outward from the foil 400 and may have a height between 0.5 times and 4.0 times the thickness of the foil 400. The protrusion 420 may be circular, or may be square, triangular, or another shape. As shown in FIG. Figures 6A-6C As shown in , the hole 410 can be circular. However, in other embodiments, the hole can be oval, hexagonal, square, or another shape.

[0065] Alternatively, one edge of the foil 400 may be beveled, such as Figure 6C As shown in Figure 6C As the foil shown is rolled starting from the smaller side, a cavity is formed at the leading end of the foil 400. Similar to the foil 400 in the other embodiments, this enables efficient formation of a wicking cavity.

[0066] The foil 400 can be folded and rolled in a variety of different ways. In one embodiment, Fig. 6E As shown in FIG. 4 , the foil 400 is wound in a spiral. Figure 6C In another embodiment, as shown in Fig.6D As shown in FIG. 4 , the foil 400 is folded into a triangle. In this embodiment, a solid cylinder 450 may be placed inside the triangular shaped foil to control the size of the conduit. The solid cylinder 450 may extend beyond the top surface of the foil 400, reach the top surface of the foil 400, or may terminate before the top surface of the foil. If the solid cylinder 450 terminates before the foil, a cavity is formed at the top of the inside of the foil 400, wherein the space between the foil layers all flows into the cavity. In another embodiment, as shown in FIG. Fig. 6F As shown in , the foil 400 is folded into a hexagon. In this embodiment, a solid cylinder 450 can be placed inside the hexagonal shape of the foil to control the size of the conduit. Of course, the foil 400 can be folded into any desired shape including squares, pentagons, octagons, and ovals. In all of these embodiments, the molten dopant material travels in the gaps between adjacent layers of the foil 400. The holes 410 in the foil 400 enable the molten material to move from one set of layers to another set of layers. This can achieve a more uniform flow through each of the gaps.

[0067] The spacing between adjacent layers of the foil acts as a conduit. The spacing between adjacent layers of the foil and the surface roughness of the foil can determine the rate at which the molten dopant material moves to the front surface of the foil 400. In addition, the holes 410 act as openings that allow the molten dopant material to enter the internal conduit.

[0068] Wrap foil (e.g. Figure 6D-6F ) can be inserted into the crucible 120. In another embodiment, a hollow outer cylinder and a solid inner cylinder can be used to form an annular ring. A wound foil (e.g., Figure 6D-6F In another embodiment, the wrap foil can be placed in this annular ring. The combination of the hollow outer cylinder, the solid inner cylinder and the wrap foil constitutes the wicking tip. In another embodiment, the wrap foil can be contained by clamping the ring or tube around the shape (whether the shape is a cylindrical shape, a triangular shape, a hexagonal shape or another shape). The ring or tube is mechanically compressed around the wrap foil. In another embodiment, the wrap foil can also be nailed in the positive transverse direction. The shape can be any organic shape or geometric shape, as long as there is a passage from back to front.

[0069] In each of the embodiments shown in FIGS. 3-6 , the wicking tip 170 includes a body having one or more internal conduits therein through which the molten dopant material can flow. Figures 3A-3E In the embodiment shown in , this inner conduit is conduit 220. Figures 5A-5C In the embodiment shown in , this internal conduit is the space between the rods 330 in the annular ring 340. Figures 6A-6F In the embodiment shown in , this internal conduit is the spacing between adjacent layers of the wound foil. In addition, in each embodiment, there are one or more openings that enable the internal conduit to communicate with the exterior of the wicking tip. Finally, each embodiment also includes a wicking cavity for collecting the molten dopant material flowing through the internal conduit. In addition, the wicking tip 170 in each of these embodiments is disposed in a crucible. This crucible can have a crucible cavity on the front surface of the crucible to collect the molten dopant material flowing out of the wicking cavity.

[0070] The above-described embodiments in the present application may have many advantages.

[0071] First, the use of the wicking tip described herein enables the molten dopant material to move to the front surface of the crucible at a controlled rate. This rate is determined based on the size of the conduit in the wicking tip that leads to the wicking cavity. In addition, the size and number of openings that connect the exterior of the wicking tip 170 to the conduit also contribute to the flow rate.

[0072] second, Figures 3A-3EThe configuration of the wicking tip in the embodiment includes a choke point. There are multiple conduits 220 in communication with the wicking cavity 230. In some embodiments, the cross-sectional area of ​​the channel where the conduits 220 intersect the wicking cavity 230 is less than the combined cross-sectional area of ​​the conduits 220. Figure 3D As best shown in FIG. 2 , the cross-sectional area of ​​the channel is much smaller than the combined area of ​​the three conduits 220. This can create a choke point that limits the flow of dopant material into the wicking cavity 230. In some embodiments, the combined cross-sectional area of ​​the conduits 220 is 1 to 12 times greater than the cross-sectional area of ​​the channel connecting the conduits 220 to the wicking cavity 230. In some embodiments, the combined cross-sectional area of ​​the conduits 220 is 3 to 12 times greater than the cross-sectional area of ​​the channel connecting the conduits 220 to the wicking cavity 230.

[0073] Third, the wicking tips enable the crucible to be oriented in either a vertical or horizontal configuration. Because the flow rate is controlled, there is little risk of molten dopant material splashing into the arc chamber 100.

[0074] In addition, the wicking tip includes a wicking cavity. The wicking cavity is where a large amount of surface area is provided to the interior of the arc chamber for use when the dopant material is fed thereto by heat. This larger amount of surface area can be concave, convex, countersunk, a single port or multiple ports, and any geometric or organic shape with depth and shape. These shapes are used to supply a usable volume of dopant material that will then be vaporized. The cavity can also contain the dopant material so that the dopant material does not drip or splash into the arc chamber.

[0075] The scope of the present disclosure is not limited by the specific embodiments described herein. In fact, in addition to the embodiments and modifications described herein, various other embodiments of the present disclosure and various modifications to the present disclosure will also be apparent to those of ordinary skill in the art, based on the foregoing description and accompanying drawings. Therefore, these other embodiments and modifications are intended to fall within the scope of the present disclosure. In addition, although the present disclosure has been described herein in the context of a specific embodiment in a specific environment for a specific purpose, it should be recognized by those of ordinary skill in the art that its validity is not limited thereto and that the present disclosure can be beneficially implemented in any number of environments for any number of purposes. Therefore, the claims set forth above should be interpreted in light of the full scope and spirit of the invention as described herein.

Claims

1. An apparatus for placing a dopant material in an ion source, characterized in that include: Crucible; as well as a wicking tip disposed in the crucible, wherein the wicking tip comprises: a body having one or more internal conduits; one or more openings that connect the one or more internal conduits to the exterior of the body and the interior of the crucible; and A wicking cavity is disposed at the leading end of the wicking tip, wherein the one or more internal conduits flow into the wicking cavity.

2. The device according to claim 1, characterized in that The body includes a cylindrical portion containing a plurality of internal conduits.

3. The device according to claim 2, characterized in that wherein a portion of the body includes a major outer diameter, the major outer diameter being defined such that the plurality of internal conduits are completely contained within the portion having the major outer diameter, and wherein a conveying ring is disposed on another portion of the body to form the one or more openings, the conveying ring being a region having a diameter smaller than the major outer diameter.

4. The device according to claim 2, characterized in that The cross-sectional area of ​​the channel where the plurality of internal conduits connect to the wicking cavity is smaller than the combined cross-sectional area of ​​the plurality of internal conduits, thereby forming a choke point.

5. The device according to claim 4, characterized in that Wherein the combined cross-sectional area of ​​the plurality of internal conduits is 3 to 12 times greater than the cross-sectional area of ​​the channel where the plurality of internal conduits connect to the wicking cavity.

6. The device according to claim 3, characterized in that Wherein the body and the one or more internal conduits are curved.

7. The device according to claim 2, characterized in that Wherein the wicking cavity comprises a concave cavity.

8. The device according to claim 1, characterized in that Wherein the body comprises only one internal conduit.

9. The device according to claim 1, characterized in that The body comprises a hollow outer cylinder and a solid inner cylinder, wherein an annular ring is formed between the hollow outer cylinder and the solid inner cylinder, wherein the wicking tip further comprises rods disposed in the annular ring, wherein the spacing between the rods in the annular ring comprises the one or more internal conduits.

10. The device according to claim 1, characterized in that Wherein the body comprises a foil which is rolled up to form the body; and wherein the spaces between adjacent layers of the foil comprise the one or more internal conduits.

11. An indirect heating cathode ion source, characterized in that: include: An arc chamber having a first end and a second end; a cathode disposed on the first end; as well as The device of claim 1, disposed at the second end.

12. An indirect heating cathode ion source, characterized in that: include: An arc chamber having a first end, a second end, and a side wall connecting the first end and the second end; a cathode disposed on the first end; an actuator adapted to extend into and retract from the arc chamber; as well as The device of claim 1, disposed on an end of said actuator.

13. An apparatus for placing a dopant material in an ion source, characterized in that include: Crucible; as well as a wicking tip disposed in the crucible, wherein the wicking tip comprises: a solid inner cylinder disposed within the hollow outer cylinder to form an annular ring; as well as A plurality of rods are disposed in the annular ring.

14. The device according to claim 13, characterized in that Wherein the spacing between the plurality of rods forms an internal conduit through which the dopant material travels.

15. The device according to claim 14, characterized in that Wherein the plurality of rods extend beyond the hollow outer cylinder at a rear end of the wicking tip to provide an opening to enable the dopant material to enter the inner conduit.

16. The device according to claim 14, characterized in that The hollow outer cylinder extends further than the plurality of rods at a front end to form a cavity into which dopant material from the inner conduit is collected.

17. The device according to claim 13, characterized in that The plurality of rods include tantalum, a refractory metal, or a high temperature wire.

18. An indirect heating cathode ion source, characterized in that: include: An arc chamber having a first end and a second end; a cathode disposed on the first end; as well as The device of claim 13, disposed at the second end.

19. An indirect heating cathode ion source, characterized in that: include: An arc chamber having a first end, a second end, and a side wall connecting the first end and the second end; a cathode disposed on the first end; an actuator adapted to extend into and retract from the arc chamber; as well as The device of claim 13, disposed on an end of said actuator.

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