Vaporizer, ion source

Abstract

To provide a vaporizer that supplies a halogen-containing gas into a crucible and achieves a stable supply of vapor.SOLUTION: Each of vaporizers V1 to V5 includes a crucible 3 having openings at opposing ends, a nozzle 1 attached to the opening at one end of the crucible 3 and having a steam outlet H for discharging steam generated in the crucible 3 to the outside of the crucible 3, a gas pipe Y attached to the opening at the other end of the crucible 3 and supplying a halogen-containing gas to the crucible 3, a support member Z supporting the crucible 3 on the flange 12 at the other end of the crucible 3, and a thermal insulating member 4 in physical contact with the crucible 3 and the support member Z and disposed between the crucible 3 and the support member Z, and is made of a material having a lower thermal conductivity than the support member Z when the vaporizers V1 to V5 are in operation.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a vaporizer for supplying vapor and an ion source equipped with the vaporizer. [Background technology]

[0002] In an ion source equipped with a vaporizer, plasma is generated from the vapor from the vaporizer, and an ion beam is extracted from the generated plasma.

[0003] For example, in the ion source of Patent Document 1, steam is supplied into a plasma generating chamber through a steam inlet provided on the wall of the plasma generating chamber. This steam is generated by heating a solid material such as aluminum fluoride or pure aluminum.

[0004] Recently, a new type of vaporizer that supplies a halogen-containing gas into a crucible has been developed as a vaporizer of a different type from that described in Patent Document 1. This vaporizer heats a reaction product generated by the reaction between the halogen-containing gas and a solid material, and supplies the vapor of the reaction product to a plasma vessel. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2004-359985 Summary of the Invention [Problem to be solved by the invention]

[0006] In vaporizers, a stable supply of steam is important. The main factor that hinders a stable supply of steam is that the supply of steam or gas is hindered by deposits that form in the low-temperature part of the crucible. When the vapor that has evaporated inside the crucible comes into contact with a low-temperature part inside the crucible, it adheres to that part and accumulates. As the amount of deposits increases over time, the increased deposits clog the vapor supply path and gas supply path, preventing a stable supply of vapor.

[0007] A primary object of the present invention is to achieve a stable supply of vapor in a vaporizer that supplies a halogen-containing gas to a crucible. [Means for solving the problem]

[0008] The vaporizer is a crucible having apertures at opposing ends; a nozzle attached to the opening at one end of the crucible and having a steam outlet for discharging steam generated in the crucible to the outside of the crucible; a gas tube attached to the aperture at the other end of the crucible for supplying a halogen-containing gas to the crucible; a support member that supports the crucible on a flange at the other end of the crucible; a thermal insulator disposed between the crucible and the support member and in physical contact with the crucible and the support member; During operation of the vaporizer, the thermal insulation member is constructed of a material that has a lower thermal conductivity than the support member.

[0009] The vaporizer having the above configuration can prevent the temperature of the crucible from dropping near the gas pipe, which reduces adhesion of vapor and accumulation of adherent matter near the gas pipe, allowing the gas supply to the crucible to continue, thereby realizing a stable supply of vapor.

[0010] At one end of the crucible, the nozzle is fitted into an aperture in the crucible; It is desirable that the diameter of the vapor discharge port varies along the vapor discharge direction and is largest at the other end of the crucible.

[0011] Even if steam adheres to the nozzle and accumulates, the diameter of the steam outlet is maximized at the other end of the crucible, so steam supply does not immediately become impossible and the steam supply path can be secured for a long period of time.

[0012] The gas pipe is made up of a plurality of pipes having different diameters, It is desirable for the tube adjacent the crucible to have the largest diameter.

[0013] There is a concern that vapor may adhere to the gas pipe near the crucible, resulting in the deposition of deposits. However, by maximizing the diameter of the pipe adjacent to the crucible, it is possible to ensure a gas supply path even if deposits accumulate there.

[0014] During operation of the vaporizer, it is desirable that the end of the crucible where the aperture is formed has a higher temperature than the center of the crucible where the solid material is disposed.

[0015] By increasing the crucible temperature in places where vapor is likely to solidify, vapor adhesion and accumulation can be reduced.

[0016] It is desirable that the nozzle, the crucible and the gas pipe are made of the same material.

[0017] Since distortion between components due to thermal expansion is reduced, the vaporizer can operate stably for a long period of time.

[0018] It is desirable that an outer cylinder be provided on the outside of the gas pipe so as to cover the periphery of the gas pipe.

[0019] Since corrosion of the support member due to halogen-containing gas can be prevented, the crucible can be stably supported for a long period of time.

[0020] The ion source is A vaporizer according to any one of the above, A plasma is generated from the vapor supplied from the vaporizer and extracted as an ion beam. Effect of the Invention

[0021] By providing a thermal insulating member that is in physical contact with the crucible and the support member and is disposed between the crucible and the support member, it is possible to prevent the temperature of the crucible near the gas pipe from dropping, which reduces adhesion of vapor and accumulation of adherent matter near the gas pipe, allowing the gas supply to the crucible to continue, thereby realizing a stable supply of vapor. [Brief description of the drawings]

[0022] [Figure 1] Schematic cross-sectional view showing a configuration example of a vaporizer [Diagram 2] FIG. 4 is a schematic cross-sectional view showing another example of the configuration of the vaporizer; [Diagram 3] FIG. 11 is a schematic cross-sectional view showing another example of the configuration of the vaporizer; [Figure 4] FIG. 11 is a schematic cross-sectional view showing another example of the configuration of the vaporizer; [Diagram 5] FIG. 11 is a schematic cross-sectional view showing another example of the configuration of the vaporizer; [Figure 6] Schematic cross-sectional view showing an example of the configuration of an ion source. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] 1 is a schematic cross-sectional view of a vaporizer V1. The vaporizer V1 has a nozzle 1 that supplies vapor to a plasma generating chamber (not shown) and a crucible 3 to one end of which the nozzle 1 is attached. The nozzle 1 has a vapor outlet H for supplying vapor in a vapor emission direction A. A space is formed inside the crucible 3 in which the solid material S is placed. A heater 2 for heating the crucible 3 is wound around the outer periphery of the crucible 3. A gas pipe Y for supplying a halogen-containing gas is connected to the other end of the crucible 3 opposite the end to which the nozzle 1 is attached.

[0024] The gas pipe Y is composed of a large-diameter first gas pipe 11 and a small-diameter second gas pipe 10. The gas pipe Y is connected to a halogen-containing gas supply source 13 on the outside of a flange 12 that forms the support base of the vaporizer V1. The halogen-containing gas supply source 13 is a low-pressure or high-pressure gas bottle.

[0025] When a halogen-containing gas is supplied from the gas pipe Y to the crucible 3, the halogen-containing gas reacts with the solid material S to generate a reaction product on the surface of the solid material S. For example, the solid material S is pure aluminum or aluminum nitride. The solid material S shown in the figure is unevenly distributed on the left side of the crucible 3, but may be evenly distributed inside the crucible 3. The solid material S may be in various shapes, such as a block, pellet, or powder. The same applies to the other vaporizers described below.

[0026] The halogen-containing gas is, for example, chlorine gas, hydrochloric acid gas, or fluorine gas. The reaction between the halogen-containing gas and the solid material S generates reaction products such as aluminum chloride and aluminum fluoride on the surface of the solid material S. The generated reaction products are vaporized by heating the crucible 3 and supplied to a plasma generating vessel (not shown) through the nozzle 1.

[0027] The nozzle 1, the crucible 3, and the gas pipe Y are made of the same material, such as isotropic graphite, which has high heat resistance and high thermal conductivity. By using the same material, it is possible to reduce misalignment between the components due to thermal expansion at high temperatures. This allows the vaporizer V1 to operate stably for a long period of time.

[0028] On the other hand, since such materials are expensive, the support cylinder 6 and the support stand 5, which are the support members that support the crucible 3 on the flange 12, are made of stainless steel.

[0029] The thermal conductivity of stainless steel changes with temperature, and the higher the temperature, the higher the thermal conductivity. During operation of the vaporizer V1, the support 5 that directly supports the crucible 3 becomes hot, promoting heat transfer from the crucible 3 to the support 5. This causes the temperature of the crucible 3 to drop locally, and steam adheres to the cooled area, which may accumulate and impede the gas supply from the gas pipe Y.

[0030] During operation of the vaporizer V1, the crucible 3 is heated to a temperature for vaporizing the reaction products, which may range from about 180° C. to about 1000° C., depending on the type of reaction product. Some types of stainless steel become brittle at temperatures between 400° C. and 500° C. Heat transfer from the crucible 3 may cause the stainless steel to become brittle, which may cause problems in supporting the crucible 3.

[0031] To address these concerns, in vaporizer V1, a thermal insulating member 4 is disposed between crucible 3 and support stand 5. This thermal insulating member 4 is a heat-resistant member, and is made of a material that has a lower thermal conductivity than the material of support stand 5 during operation of vaporizer V1. Specifically, it is a ceramic material such as aluminum oxide, zirconia, or cordierite.

[0032] By providing this thermal insulating member 4, it is possible to prevent the temperature at the gas supply portion of the crucible 3 from decreasing, so that the gas supply to the crucible 3 can be continued, and thus a stable supply of vapor can be realized.

[0033] The tip of the first gas pipe 11 constituting the gas pipe Y is formed in a tapered shape. The first gas pipe 11 is fixed to the crucible 3 by abutting this tapered portion against the bottom of the crucible 3. If a halogen-containing gas containing chlorine or fluorine leaks out from between the gas pipe Y and the crucible 3, it may corrode the support cylinder 6, which is thinner than the support base 5, and cause a problem in supporting the crucible 3.

[0034] As a countermeasure, an outer cylinder X for preventing gas leakage is provided on the outside of the gas pipe Y. This outer cylinder X, like the gas pipe Y, is composed of a first outer cylinder 7 with a large diameter, a second outer cylinder 8 with a small diameter, and a connecting member 9 for both cylinders. Each outer cylinder is fixed to the connecting member 9 by a method such as welding or fitting. The connecting member 9 is made of a material with high thermal resistance, such as aluminum oxide or zirconia, which has a lower heat transfer rate than the material constituting the outer cylinder X.

[0035] By providing the outer cylinder X, even if the outer cylinder X is corroded due to a gas leak, the support cylinder 6 will not be corroded, and the crucible 3 can be stably supported for a long period of time. It is not necessary that the outer cylinder X is provided over the entire length of the gas pipe Y, but it is sufficient that the outer cylinder X is provided around the gas pipe Y to such an extent that the support cylinder 6 can be protected.

[0036] If steam adheres to and accumulates at the steam outlet H of the nozzle 1, the steam outlet H of the nozzle 1 may become clogged, which may hinder a stable supply of steam. 2, the hole diameter is gradually enlarged from D1 to D2 to D3 from the tip of the nozzle 1 toward the crucible 3. The diameter of the vapor outlet H changes along the vapor outlet direction A, and is maximum on the side where the gas pipe Y is attached to the crucible 3.

[0037] The tip of the nozzle 1 is attached to the wall of a plasma generating vessel (not shown), and this part becomes relatively hot. Since the end of the nozzle 1 on the crucible 3 side becomes relatively cold when viewed as the entire nozzle 1, by making the hole diameter of this part larger, even if deposits adhere to the steam outlet H, the time until the stable supply of steam is interrupted can be extended. In the vaporizer V2 shown in FIG. 2, the hole diameter of the nozzle 1 is changed stepwise, but it may be changed linearly or curvedly.

[0038] In the vaporizers V1 and V2 shown in FIGS. 1 and 2, the temperature distribution of the heater 2 in the length direction of the crucible 3 (the vertical direction in the figure) is uniform, but the temperature distribution may be made non-uniform. In FIG. 3, in regions R1 and R3 corresponding to the respective ends of the crucible 3, the number of turns of the coil constituting the heater 2 is increased compared to the region R2 of the crucible 3 in which the solid material S is placed.

[0039] This makes it possible to increase the temperature at the end of the crucible 3 and reduce deposition due to adhesion of vapor. Note that instead of the configuration of Fig. 3, another configuration may be used to make the temperature of the crucible 3 non-uniform. For example, heaters corresponding to each end of the crucible 3 and a heater corresponding to the center are provided separately, and the heater output at each portion is adjusted to make the temperature distribution of the crucible 3 non-uniform.

[0040] In order to improve the heating efficiency of the crucible 3 by the heater 2, a heat shielding plate may be arranged around the heater 2 as in the vaporizer V4 shown in Fig. 4. Specifically, in the vaporizer V4, the heat shielding plate is composed of a first heat shielding plate 21 that presses the heater 2 against the crucible 3 and a second heat shielding plate 22 that is arranged on the outer side of the first heat shielding plate 21.

[0041] By disposing such a heat shielding plate, it is possible to suppress heat escaping from the crucible 3 to the outside, and to maintain a high temperature in the crucible 3. In addition, the first heat shielding plate 21 presses the heater 2 against the crucible 3, thereby making it possible to fix the position of the heater 2. The heater 2 may be fixed in position by forming a groove for fixing the position on the outer periphery of the crucible 3 and fitting the heater 2 into the groove.

[0042] A third heat shield plate 23 and a fourth heat shield plate 24 may be arranged to shield the crucible 3 from heat from the plasma generating vessel (not shown) and to prevent excessive heating of the crucible 3. By providing these heat shield plates, it becomes easy to adjust the temperature of the crucible 3 in the longitudinal direction.

[0043] The number of heat shielding plates is not limited to the configuration shown in Fig. 4. For example, it is sufficient to provide only one of the first heat shielding plate 21 and the second heat shielding plate 22. On the other hand, a configuration in which an additional heat shielding plate is provided outside the second heat shielding plate 22 may also be used. Similarly, there is no limit to the number of third heat shielding plates 23 and fourth heat shielding plates 24. Furthermore, if the main purpose of the first heat shielding plate 21 is to fix the position of the heater 2, the thickness of the first heat shielding plate 21 may be thinner than the thickness of the second heat shielding plate 22.

[0044] The vaporizer V4 in Fig. 4 is equipped with a thermocouple 14 for measuring temperature. The output of the heater 2 may be adjusted based on the measurement result of the thermocouple 14. The measurement result of the thermocouple 14 may also be used as an interlock value for determining whether or not to continue the operation of the vaporizer V4.

[0045] In the above-described embodiment, in the vaporizers V1 to V4, a configuration was adopted in which the first outer cylinder 7 and the second outer cylinder 8 are attached to the connecting member 9 having a large thermal resistance in order to suppress the inflow of heat to the flange 12 side. However, if there is no need to consider the inflow of heat from the outer cylinder X to the flange 12, the outer cylinder X may be formed of only the first outer cylinder 7, as shown in FIG. Similarly, if there is no need to consider the inflow of heat into the flange 12, the gas pipe Y may be configured with only the large-diameter first gas pipe 11 as shown in FIG.

[0046] 6 shows an example of the configuration of an ion source IS equipped with the vaporizers V1 to V5 described in the above embodiment. Vapor supplied from any one of the vaporizers V1 to V5 is introduced into a plasma generating vessel 31, and plasma is generated in the plasma generating vessel 31. To generate the plasma, well-known techniques such as arc discharge or microwave discharge are used.

[0047] An ion extraction port 34 is formed on one surface of the plasma generating vessel 31. The plasma P generated in the plasma generating vessel 31 is extracted to the outside of the plasma generating vessel 31 through the ion extraction port 34 by an extraction electrode E as an ion beam IB.

[0048] The extraction electrode E is composed of, for example, a suppression electrode 32 for suppressing the inflow of electrons into the plasma generating vessel 31 and a ground electrode 33 fixed to a ground potential. A predetermined voltage is applied to the plasma generating vessel 31 and the suppression electrode 32 by a power source (not shown).

[0049] The plasma generating vessel 31 may be provided with a gas supply port 35 through which gas is supplied in addition to the vapor supply from the vaporizers V1-V5. By providing the gas supply port 35, the versatility of the ion source IS is improved.

[0050] In the above embodiment, the heater 2 is a wire-shaped coil heater, but a sheet-shaped coil heater may be used instead of the wire-shaped one. Also, a panel heater with a flexible heating surface may be used. Furthermore, a heater with a thermocouple may be used.

[0051] The nozzle 1 and the crucible 3, the thermal insulating member 4 and the crucible 3, and the thermal insulating member 4 and the support 5 are attached to each other by various methods such as threading, screwing, welding, etc.

[0052] In the above embodiment, the support table 5 and the support cylinder 6 are used as the support member Z, but only one of these members may be used to support the crucible 3 from the flange 12. In addition, the support cylinder 6 is not limited to a cylindrical member. It may be a member that supports the crucible 3 using a plurality of rods or plates.

[0053] In the above embodiment, the nozzle 1 is fitted inside the crucible 3. However, the nozzle 1 may be fitted outside the crucible 3. By fitting the nozzle 1 outside the crucible 3, a large space can be secured inside the crucible 3. On the other hand, since the nozzle 1 is attached to the outer periphery of the crucible 3, there are disadvantages in that it is difficult to attach the heater 2 and the dimensions of the vaporizer become large.

[0054] Furthermore, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0055] 1 nozzle 3 Crucible 4. Thermal insulation materials X Outer cylinder Y Gas Pipe Z support member V1-V5 Carburetor

Claims

1. a crucible having apertures at opposing ends; a nozzle attached to the opening at one end of the crucible and having a steam outlet for discharging steam generated in the crucible to the outside of the crucible; a gas tube attached to the aperture at the other end of the crucible for supplying a halogen-containing gas to the crucible; a support member that supports the crucible on a flange at the other end of the crucible; a thermal insulator disposed between the crucible and the support member and in physical contact with the crucible and the support member; A vaporizer, wherein the thermal insulation member is made of a material having a lower thermal conductivity than the support member during operation of the vaporizer.

2. At one end of the crucible, the nozzle is fitted into an aperture in the crucible; 2. The vaporizer according to claim 1, wherein the diameter of the vapor discharge port varies along a vapor discharge direction, and is largest at the other end side of the crucible.

3. The gas pipe is made up of a plurality of pipes having different diameters, 2. The vaporizer of claim 1, wherein the tube adjacent the crucible has the largest diameter.

4. 2. The vaporizer of claim 1, wherein, during operation of the vaporizer, the end of the crucible where the aperture is formed has a higher temperature than the center of the crucible where the solid material is disposed.

5. 2. The vaporizer of claim 1, wherein the nozzle, the crucible, and the gas tube are constructed of the same material.

6. 2. The vaporizer according to claim 1, further comprising an outer cylinder provided on the outside of said gas pipe to cover the periphery of said gas pipe.

7. An ion source having a vaporizer according to any one of claims 1 to 6, an ion source that generates plasma from the vapor supplied from the vaporizer and extracts an ion beam from the plasma;

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