JP2009021066A - Ion doping device and filament for ion doping device, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide: a filament for ion doping device, which improves a lifetime while suppressing increase of input power; its manufacturing method; and an ion doping device having the filament for ion doping device. <P>SOLUTION: The filament 11 is made of a tungsten wire having conductivity, and the tungsten wire is provided with two straight line parts 12 extending in a straight line shape and a connecting part 13 which connects end parts of mutually adjoining straight line parts 12 out of a plurality of straight line parts 12. Then, the straight line part 12 has a large diameter portion 14 formed having a large filament cross-section area that is the cross-section area at the vertical cross-section in a direction in which the tungsten wire extends rather than the connecting part 13. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ion doping apparatus, an ion doping apparatus filament, and a manufacturing method thereof, and more specifically, an ion doping apparatus filament that has an improved life while suppressing an increase in input power, and a manufacturing method thereof, and The present invention relates to an ion doping apparatus provided with a filament for an ion doping apparatus.

  In a manufacturing process of a TFT (Thin Film Transistor) liquid crystal display such as a low-temperature polysilicon liquid crystal display, it is necessary to form the TFT on a large substrate. At this time, an ion doping apparatus is used for forming a source region, a drain region, an LDD (Lightly Doped Drain) region and the like of the TFT, and implanting impurities for the purpose of controlling the threshold value of the TFT.

  The ion doping apparatus includes, for example, an ion source that generates ions, and is provided as a processing chamber for implanting ions into a substrate and a front chamber of the processing chamber for maintaining a high vacuum state of the processing chamber. An L / L (load lock) chamber for loading and unloading a substrate, and a transfer chamber that is disposed between the processing chamber and the L / L chamber and includes a transfer device for transferring the substrate between the chambers. ing. The ion source includes a plasma source for generating target impurity ions, and an electrode for extracting the generated impurity ions and accelerating them to a desired energy.

  Here, as the above-mentioned plasma source, a plasma source using a RF (Radio Frequency) discharge and a plasma source using a DC (Direct Current) discharge are known, but ion implantation into a substrate is known. A method using a DC arc discharge with a large variable range of the beam current density for controlling the amount is mainly used. In the plasma source using the DC arc discharge, a filament made of tungsten (W) or the like is used.

The filament is a consumable item and needs to be replaced at a predetermined frequency. However, if the frequency of interruption of the operation of the ion source due to filament replacement or the like increases, the production efficiency of a liquid crystal display or the like using an ion doping apparatus is reduced, leading to an increase in manufacturing cost. On the other hand, various proposals have been made to suppress the frequency of interruption of the operation of the ion source (see, for example, Patent Documents 1 to 5).
JP-A-1-296548 JP-A-5-28940 JP-A-2-109239 Japanese Patent Laid-Open No. 1-163952 JP-A 61-29057

  In order to suppress the frequency of interruption of the operation of the ion source, it is effective to improve the life of the filament used in the ion source. FIG. 5 is a schematic cross-sectional view showing a conventional filament for an ion doping apparatus. FIG. 6 is a schematic cross-sectional view showing a damaged state in which the ion doping apparatus filament of FIG. 5 is used. With reference to FIG. 5 and FIG. 6, the damage of the conventional filament for ion doping apparatuses is demonstrated.

  Referring to FIG. 5, a filament 110, which is a conventional filament for an ion doping apparatus, is made of a tungsten wire, and two straight portions 120 in which the wire extends linearly, and ends of the two straight portions 120 are arranged. It has a U-shape including a connecting portion 130 to be connected. In the straight line portion 120 and the connecting portion 130, the cross-sectional area (filament cross-sectional area) in a cross section perpendicular to the direction in which the line extends is constant (that is, the thickness of the line is constant). When the filament 110 is used in an ion source of an ion doping apparatus, it is damaged as follows.

That is, when an ion doping apparatus is used to form a P-type source region and a P-type drain region of a TFT, diborane (B ₂ H ₆ ) gas is often used as a source gas. In this case, tungsten constituting the filament 110 reacts with diborane gas and becomes brittle, and the filament may be disconnected in a short time. Therefore, cleaning discharge is performed as a countermeasure against discharge in an argon (Ar) gas atmosphere. Thereby, embrittlement of the filament 110 is suppressed and the life of the filament 110 is improved. However, sputtering by argon gas occurs by performing the cleaning discharge. As a result, as shown in FIG. 6, the damaged portion 190, which is a part of the straight portion 120 of the filament 110, is damaged and thinned, and finally the filament 110 is disconnected at the damaged portion 190.

  FIG. 7 is a schematic cross-sectional view showing another example of a conventional filament for an ion doping apparatus. FIG. 8 is a schematic cross-sectional view showing a damaged state in which the ion doping apparatus filament of FIG. 7 is used. With reference to FIGS. 7 and 8, another example of damage to a conventional filament for an ion doping apparatus will be described.

  Referring to FIG. 7, a filament 210, which is another example of a conventional filament for an ion doping apparatus, is made of a tungsten wire, and the four straight portions 220 in which the wires extend linearly and the four straight portions 220. Among them, it has an M-shaped shape including three connecting portions 230 that connect the end portions of the linear portions 220 adjacent to each other. And in the straight line part 220 and the connection part 230, the cross-sectional area in the cross section perpendicular | vertical to the direction where a line is extended is constant (namely, the thickness of a line is constant). When the filament 210 is used in an ion source of an ion doping apparatus, as in the case of the filament 110, as a result of the cleaning discharge for suppressing the embrittlement of the filament 210, as shown in FIG. The damaged part 290 which is a part of the straight part 220 of 210 is damaged and becomes thin, and finally the filament 210 is disconnected at the damaged part 290.

  As described above, in a conventional filament for an ion doping apparatus, cleaning discharge is performed as a measure for preventing embrittlement due to reaction with a source gas. However, as a result of this cleaning discharge, a part of the filament is damaged. There was a problem of occurrence and disconnection. On the other hand, it is considered that a measure for extending the life of the filament by increasing the thickness of the entire filament is effective. However, in this case, it is necessary to increase the input power supplied to the filament, and a power source having a large capacity is required. Therefore, the measure of simply thickening the entire filament is not necessarily an effective measure.

  Accordingly, an object of the present invention is to provide an ion doping apparatus filament capable of improving the life while suppressing an increase in input power, a method for manufacturing the same, and an ion doping apparatus including the ion doping apparatus filament. is there.

  The filament for an ion doping apparatus according to the present invention is composed of a conductive line, and a plurality of linear portions in which the line extends linearly, and ends of the linear portions adjacent to each other among the plurality of linear portions. And a connecting portion for connecting the two. And the large diameter part with a larger filament cross-sectional area which is a cross-sectional area in the cross section perpendicular | vertical to the direction where a line | wire extends than the connection part is formed in the linear part. Here, the connecting portion is, for example, a curved portion having a curved shape.

The present inventor has conducted detailed studies on damage to the filament for an ion doping apparatus and has obtained the following knowledge. That is, when the whole filament is thickened, the input power to the filament increases as described above. At this time, decomposition of the raw material gas, for example, diborane is promoted, and the ratio (concentration) of B ₂ H _X that is the target impurity ion is reduced. As a result, there arises a problem that the doping efficiency is lowered and the processing capability of the ion doping apparatus is lowered. That is, a measure for extending the life of the filament by increasing the thickness of the entire filament not only requires a large-capacity power supply but also causes a reduction in the processing capability of the ion doping apparatus. Therefore, the measure of simply increasing the thickness of the entire filament is not an effective measure.

  On the other hand, when the ion doping apparatus was operated under various conditions to check the damaged state of the filament, it was found that the damage was concentrated on the linear portion of the filament. In contrast, in the filament for an ion doping apparatus of the present invention, a large-diameter portion having a filament cross-sectional area larger than that of the connecting portion is formed in the straight portion. Thereby, the lifetime of the filament for ion doping apparatuses can be improved. Further, in the filament for an ion doping apparatus of the present invention, since the whole filament is not thick, the above-described problem of the capacity of the power source and the problem of the efficiency reduction of the ion doping apparatus can be suppressed. As described above, according to the filament for an ion doping apparatus of the present invention, it is possible to provide the filament for an ion doping apparatus capable of improving the life while suppressing an increase in input power.

  In the above ion doping apparatus filament, the large-diameter portion is preferably formed so that the filament cross-sectional area gradually decreases toward a region adjacent to the large-diameter portion.

  The damage generated in the straight portion of the filament is gradually alleviated toward both sides in the longitudinal direction of the line constituting the filament with a certain point of the straight portion as a center. Therefore, even when the large-diameter portion is formed in the straight portion as described above, if the region adjacent to the region having the largest cross-sectional area is immediately the same thickness as the connecting portion, the thickness of the filament in the region is May become insufficient for damage, and disconnection may occur in the region. On the other hand, in order to avoid this, when the region having the largest cross-sectional area is extended to the entire damaged region, the problem of reduction in the power source capacity and the processing capacity of the ion doping apparatus becomes large. In contrast, by forming the large-diameter portion toward the region adjacent to the large-diameter portion so that the filament cross-sectional area gradually decreases, while sufficiently securing the filament cross-sectional area in the region where damage is increased The filament cross-sectional area can be gradually reduced toward a region where damage is small, and the problem of a reduction in power source capacity and the processing capacity of the ion doping apparatus can be minimized. The filament cross-sectional area may be reduced so that the surface of the line has a stepped shape, for example, in a cross section along the longitudinal direction of the line constituting the filament, or may be reduced linearly or curvedly.

  In the filament for an ion doping apparatus, preferably, the filament cross-sectional area of the large diameter portion is 1.1 to 4 times the filament cross-sectional area of the connection portion. Furthermore, in the above ion doping apparatus filament, the length of the large diameter portion is preferably 2% or more and 50% or less of the total length of the straight portion and the connecting portion.

  When the filament cross-sectional area of the large-diameter portion is less than 1.1 times the filament cross-sectional area of the connection portion, the effect of improving the filament life cannot be sufficiently obtained. On the other hand, if the filament cross-sectional area of the large-diameter portion exceeds four times the filament cross-sectional area of the connection portion, the electric power to be supplied to the filament may increase beyond the allowable range. Therefore, it is preferable that the filament cross-sectional area of the large diameter portion is 1.1 to 4 times the filament cross-sectional area of the connection portion. Moreover, when the length of the large diameter portion is less than 2% of the total length of the straight portion and the connecting portion, the effect of improving the life of the filament cannot be obtained sufficiently. On the other hand, when the length of the large-diameter portion exceeds 50% of the total length of the straight portion and the connecting portion, the power to be supplied to the filament may increase beyond the allowable range. Therefore, the length of the large diameter portion is preferably 2% or more and 50% or less of the total length of the straight portion and the connecting portion. The filament cross-sectional area of the large-diameter part is 1.2 times or more and 2.3 times or less of the filament cross-sectional area of the connecting part from the balance between the allowable range of increase in power input to the filament and the effect of extending the life of the filament The length of the large diameter portion is particularly preferably 20% or more and 40% or less of the total length of the straight portion and the connecting portion.

  An ion doping apparatus according to the present invention includes the above-described filament for an ion doping apparatus of the present invention.

  By providing the filament for an ion doping apparatus capable of improving the lifetime while suppressing the increase in the input power described above, the ion doping apparatus of the present invention suppresses the increase in the input power and operates efficiently by replacing the filament. This is an ion doping apparatus in which the decrease in the resistance is suppressed.

  The manufacturing method of the filament for ion doping apparatuses according to this invention is a manufacturing method of the filament for ion doping apparatuses which consists of a wire which has electroconductivity. This method for manufacturing a filament for an ion doping apparatus includes a step of preparing a base material and a step of processing the base material into a filament. Then, in the process of processing the base material into a filament, when an ion doping apparatus in which an ion doping apparatus filament is used is mounted with a trial operation filament and a trial operation of the ion doping apparatus is performed, a test operation is performed. In the filament, the filament cross-sectional area, which is the cross-sectional area in the cross section perpendicular to the direction in which the line extends, of the portion corresponding to the damaged portion that is damaged and thinned by the trial operation is greater than the region adjacent to the portion corresponding to the damaged portion. The base material is processed into filaments.

  According to the method for manufacturing a filament for an ion doping apparatus of the present invention, the base material is a filament so that the filament cross-sectional area of the portion corresponding to the damaged portion of the filament is larger than the region adjacent to the portion corresponding to the damaged portion. To be processed. Therefore, a filament for an ion doping apparatus having a large diameter portion at a site that becomes a damaged site can be obtained. As a result, according to the method for manufacturing a filament for an ion doping apparatus of the present invention, it is possible to manufacture an ion doping apparatus filament capable of improving the life while suppressing an increase in input power.

  As is clear from the above description, according to the ion doping apparatus, the ion doping apparatus filament of the present invention, and the manufacturing method thereof, the ion doping apparatus filament capable of improving the lifetime while suppressing an increase in input power, and the method thereof. A manufacturing method and an ion doping apparatus provided with the filament for the ion doping apparatus can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

  FIG. 1 is a schematic diagram showing the configuration of an ion doping apparatus according to an embodiment of the present invention. With reference to FIG. 1, an ion doping apparatus according to an embodiment of the present invention will be described.

  Referring to FIG. 1, an ion doping apparatus 1 in the present embodiment includes a processing chamber 60 for implanting ions into a substrate 99 and a front chamber of the processing chamber 60 for maintaining a high vacuum state of the processing chamber 60. The L / L (load lock) chamber 80 for loading and unloading the substrate 99 before and after processing, and the processing chamber 60 and the L / L chamber 80 are disposed. And a robot chamber 70 in which a transfer robot 71 for transferring the substrate 99 is disposed. Each of the processing chamber 60, the robot chamber 70, and the L / L chamber 80 is connected to a decompression device (not shown) such as a vacuum pump for decompressing the inside. Further, valve doors 91 are disposed between the processing chamber 60 and the robot chamber 70 and between the robot chamber 70 and the L / L chamber 80, respectively. With this decompression device and the valve door 91, the processing chamber 60, the robot chamber 70, and the L / L chamber 80 can each be decompressed independently.

  The L / L chamber 80 includes a table 81 on which the substrate 99 is placed. The L / L chamber 80 is formed with an external communication port (not shown) that communicates with the outside in order to put the substrate 99 in and out of the ion doping apparatus 1. The processing chamber 60 includes a doping stage 61 for placing a substrate 99 into which ions are to be introduced. The transfer robot 71 disposed in the robot chamber 70 has a function of transferring the substrate 99 between the table 81 in the L / L chamber 80 and the doping stage 61 in the processing chamber 60.

  The processing chamber 60 includes an ion source 10 that can generate a plasma using DC arc discharge. The ion source 10 includes a filament 11 as a filament for an ion doping apparatus and a plasma 62 arranged so as to protrude into the processing chamber 60 at a position facing the surface on which the substrate 99 is placed in the doping stage 61. An arc power source 34 for generating and a plurality of magnets 31 which are attached to the wall surface of the processing chamber 60 so as to surround the region where the filament 11 protrudes in the processing chamber 60 and serve to confine the plasma 62. A plurality of (four in this embodiment) filaments 11 are arranged, and are connected to a plurality of (four in this embodiment) filament power sources 33 corresponding thereto. The ion source 10 includes a plasma electrode 41, an extraction electrode 42, a deceleration electrode 43, and a ground electrode 44 in order from the side close to the filament 11 between the filament 11 and the doping stage 61. An extraction power supply 35, an acceleration power supply 36, and a deceleration power supply 37 are provided. The plasma electrode 41, the extraction electrode 42, the deceleration electrode 43, and the ground electrode 44 are formed with a number of through holes so that ions can pass through.

  Next, details of the configuration of the filament 11 will be described. FIG. 2 is a schematic cross-sectional view showing a configuration of a filament for an ion doping apparatus in one embodiment of the present invention. In FIG. 2, a cross section parallel to the longitudinal direction of the lines constituting the filament 11 is shown.

  Referring to FIG. 2, filament 11 as an ion doping apparatus filament in the present embodiment is made of a tungsten wire having conductivity and excellent heat resistance. The filament 11 includes two straight portions 12 in which tungsten wires extend linearly, and a connection portion 13 that connects the ends of the two straight portions 12, and has a U-shaped shape. is doing. The straight portion 12 is formed with a large-diameter portion 14 having a larger filament cross-sectional area that is a cross-sectional area in a cross-section perpendicular to the direction in which the tungsten wire extends than the connection portion 13. The large-diameter portion 14 is formed with a connecting portion 15 in which the filament cross-sectional area gradually decreases toward a region adjacent to the large-diameter portion 14. In the connecting portion 15, the filament cross-sectional area decreases so that the surface of the tungsten wire has a stepped shape in the cross-section along the longitudinal direction of the tungsten wire constituting the filament 11 (cross-section in FIG. 2).

More specifically, the filament 11 is made of a tungsten wire having a total length of 330 mm, and has a wire diameter of 1.2 mm in diameter (cross-sectional area of 1.13 mm ² ). A large diameter portion 14 having a length of 55 mm is formed on each of the two linear portions 12 of the filament 11. The total length of 110 mm of the large diameter portion is 33% of the total length of the straight portion 12 and the connecting portion 13. The central portion of the large-diameter portion 14 has a diameter of 1.5 mm (cross-sectional area of 1.77 mm ² ), which is a thickness corresponding to 1.56 times the cross-sectional area of the connecting portion. Further, each of the connecting portions 15 of the large diameter portion 14 has a length of 5 mm. Further, the large-diameter portion 14 is formed so that the distance from the end portion of the straight portion 12 on the connection portion 13 side includes a region of 60% with respect to the length of each of the two straight portions 12. This region is a portion where the current flows in the opposite direction in parallel, the magnetic fields generated by the flowing current cancel each other, and the thermal electron emission efficiency is high. Therefore, the region is a region that is susceptible to damage in a U-shaped filament.

  Next, the manufacturing method of the filament for ion doping apparatuses in one embodiment of this invention is demonstrated. FIG. 3 is a flowchart showing an outline of a method of manufacturing a filament for an ion doping apparatus in one embodiment of the present invention.

  With reference to FIG. 3, the manufacturing method of the filament for ion doping apparatuses in this Embodiment is a manufacturing method of the filament for ion doping apparatuses which consists of a tungsten wire which is a wire which has electroconductivity. This method for manufacturing a filament for an ion doping apparatus includes a base material preparation step of preparing a base material, and a filament processing step of processing the base material into a filament. In the filament processing step, when a trial operation filament is mounted on an ion doping apparatus in which the filament for the ion doping apparatus is used and the trial operation of the ion doping apparatus is performed, the trial operation filament is damaged by the trial operation. The base material so that the filament cross-sectional area, which is the cross-sectional area in the cross-section perpendicular to the direction in which the line extends, of the portion corresponding to the damaged portion that is a thinned portion is larger than the region adjacent to the portion corresponding to the damaged portion Is processed into a filament.

  More specifically, in the base material preparation step, a tungsten base material made of tungsten is prepared. On the other hand, apart from the manufacturing method of the filament for ion doping apparatus, a trial operation process in which a trial operation filament is mounted on the ion doping apparatus in which the filament for ion doping apparatus is used, and the trial operation of the ion doping apparatus is performed, In the trial operation step, a damaged site confirmation step for confirming a damaged site, which is a site that is damaged and thinned by the trial operation, is performed. In the filament processing step according to the present embodiment, the base material is processed into a filament so that the cross-sectional area of the portion corresponding to the damaged portion is larger than the region adjacent to the portion corresponding to the damaged portion. . Here, as described above, the damaged portion is the straight portion 12 of the filament 11, so that the large diameter portion 14 is formed in the straight portion 12 as shown in FIG. 2. As described above, the filament 11 of the present embodiment is manufactured. In addition, if the filament for the ion doping apparatus to be manufactured has not been used in the ion doping apparatus to be used, the trial operation process and the damaged site confirmation process need to be performed as described above. When there is a track record of use and the damaged part has already been clarified, the filament processing step can be performed so that the large-diameter portion 14 is formed in the part.

  Next, the operation of the ion doping apparatus in this embodiment will be described. Referring to FIG. 1, first, a substrate 99 that is an object to be processed is loaded into an L / L chamber 80 from an external communication port (not shown) and placed on a table 81. The inside of the L / L chamber 80 is decompressed by the exhaust device while the external communication port is closed and sealed. After the pressure is reduced to a desired degree of vacuum, the valve door 91 between the L / L chamber 80 and the robot chamber 70 is opened, and the substrate 99 is moved from the L / L chamber 80 into the robot chamber 70 by the transfer robot 71. It is brought in. Thereafter, the valve door 91 between the L / L chamber 80 and the robot chamber 70 is closed, and the inside of the robot chamber 70 is depressurized to a desired degree of vacuum by the exhaust device. The valve door 91 between the two is opened. Then, after the substrate 99 is carried into the processing chamber 60 from the robot chamber 70 by the transfer robot 71 and placed on the doping stage 61, the valve door 91 between the robot chamber 70 and the processing chamber 60 is closed. Thereafter, a doping process for injecting impurities into the substrate 99 is performed in the processing chamber 60 that has been decompressed to a desired pressure by the exhaust device. Details of the doping process will be described later.

  In the substrate 99 on which the doping process has been performed, the valve door 91 between the loading source chamber and the loading source chamber is opened and closed in a procedure opposite to the above-described case, and the L / L chamber 80 is opened and closed. It is transported to the inside, and finally carried out from the external communication port of the L / L chamber 80. By performing the doping process by moving the substrate 99 in the ion doping apparatus 1 in such a procedure, the processing chamber 60 is always kept at a high vacuum, and a stable doping process is possible.

Next, details of the doping process will be described. Referring to FIG. 1, first, for example, diborane gas is introduced as a raw material gas into a processing chamber 60 decompressed by a decompression device. On the other hand, thermoelectrons are generated by the action of the filament 11 connected to the filament power supply 33, plasma 62 is generated in the processing chamber 60 by the action of the arc power supply 34, and plasma generated by the magnetic field generated by the action of the magnet 31. 62 is confined in a region surrounded by the magnet 31. Thereby, B ₂ H _X which is the target impurity ion is generated in the processing chamber 60. The generated impurity ions are extracted by the plasma electrode 41 and the extraction electrode 42 and then accelerated, and the backflow of secondary electrons is suppressed by the deceleration electrode 43 to form an ion beam, which is irradiated onto the substrate 99. The Thereby, the doping process with respect to the board | substrate 99 is implemented.

  Here, by performing the doping treatment, as described above, tungsten constituting the filament 11 reacts with the diborane gas and becomes brittle, and the filament 11 may be disconnected in a short time. Therefore, after the doping process is performed, cleaning discharge is performed in which discharge is performed in an argon gas atmosphere. At this time, sputtering with argon gas occurs in the filament 11. On the other hand, in the filament 11 in this Embodiment, since the large diameter part 14 is formed in the linear part 12 of the filament 11 damaged by the said sputtering, the lifetime of the filament 11 is improving. Moreover, in the filament 11, since the whole filament 11 is not thick, the problem of the capacity | capacitance of a power supply and the efficiency reduction of an ion doping apparatus is suppressed. As described above, the filament 11 of the present embodiment is a filament for an ion doping apparatus with an improved lifetime while suppressing an increase in input power.

  Next, a modification of the present embodiment will be described. FIG. 4 is a schematic cross-sectional view showing a configuration of a filament for an ion doping apparatus, which is a modification of the embodiment of the present invention. In FIG. 4, a cross section parallel to the longitudinal direction of the lines constituting the filament 21 is shown.

  Referring to FIG. 4, the filament 21 in the present modification basically has the same configuration as the filament 11 in the above-described embodiment described with reference to FIG. However, the filament 21 in the present modification is partially different from the filament 11 in its shape.

  That is, referring to FIG. 4, the filament 21 in the present modification is made of a tungsten wire, and the straight lines adjacent to each other among the four straight portions 22 and the four straight portions 22 in which the tungsten wires extend linearly. It has three connection portions 23 that connect the end portions of the portion 22 and has an M-shaped shape. Each straight portion 22 is formed with a large-diameter portion 24 having a larger filament cross-sectional area that is a cross-sectional area in a cross-section perpendicular to the direction in which the tungsten wire extends than the connection portion 23. The large-diameter portion 24 is formed with a connecting portion 25 in which the filament cross-sectional area gradually decreases toward a region adjacent to the large-diameter portion 24. In the connecting portion 25, the filament cross-sectional area is such that the surface of the tungsten wire decreases linearly in the cross-section (cross-section in FIG. 4) along the longitudinal direction of the tungsten wire constituting the filament 21.

More specifically, the filament 21 is made of a tungsten wire having a total length of 180 mm, and has a wire diameter of 1.2 mm in diameter (cross-sectional area of 1.13 mm ² ). Then, large diameter portions 24 each having a length of 10 mm are formed on the four linear portions 22 of the filament 21. The total length of 40 mm of the large diameter portion is 22% of the total length of the straight portion 22 and the connecting portion 23. The central portion of the large-diameter portion 14 has a diameter of 1.5 mm (cross-sectional area of 1.77 mm ² ), which is a thickness corresponding to 1.56 times the cross-sectional area of the connecting portion. Further, each of the connecting portions 25 of the large diameter portion 24 has a length of 2.5 mm. Furthermore, the large-diameter portion 24 has two straight lines arranged at the center of the straight line portion 22 at a distance from the end of the straight line portion 22 on the connection portion 23 side arranged at both ends in the direction in which the straight line portions 22 are arranged. The four straight portions 22 are formed so as to include a region of 50% with respect to the length of the portion 22. This region is a portion where the current flows in the opposite direction in parallel, the magnetic fields generated by the flowing current cancel each other, and the thermal electron emission efficiency is high. Therefore, the region is a region that is easily damaged in a filament having an M-shape.

  Embodiment 1 of the present invention will be described below. Using the filament for the ion doping apparatus of the present invention and the filament for the conventional ion doping apparatus, the doping process and the cleaning discharge are actually repeated, and the life until the filament breaks and the necessary input power are obtained. Experiments to investigate were conducted. The experimental procedure is as follows.

  First, a filament for an ion doping apparatus according to the present invention shown in FIG. 2 and a conventional filament for an ion doping apparatus shown in FIG. 5 (both are U-shaped) were produced. Thereafter, the filament 11 or the filament 110 is mounted on the ion doping apparatus 1 shown in FIG. 1, and the source gas is diborane gas (hydrogen balance 20% gas) 80 sccm, and each filament current value is 55 to 65 A (arc current 0.8 A). The doping process was performed under conditions. Thereafter, cleaning discharge was performed under the conditions of Ar (argon) gas 10 sccm and filament current values 50 to 70 A (arc current 2 A). Then, this was repeated, and the time of the doping process until the filament 11 or the filament 110 was disconnected was investigated, and this was evaluated as the life of the filament. In addition, the input power required at this time was recorded.

  Next, the results of the experiment will be described. As a result of the above experiment, the filament for an ion doping apparatus according to the present invention required 1.1 times as much input power as the conventional filament for an ion doping apparatus. On the other hand, the lifetime of the ion doping apparatus filament of the present invention is 1.6 times that of the conventional ion doping apparatus filament. From this, the filament for ion doping apparatus of this invention has the outstanding effect that a lifetime can be improved 60%, suppressing the increase in input electric power to 10% with respect to the filament for conventional ion doping apparatuses. It was confirmed.

  In the above-described embodiments and examples, filaments having U-shaped and M-shaped shapes have been described as examples of the filament for an ion doping apparatus of the present invention. However, the shape of the filament for an ion doping apparatus of the present invention is described. Is not limited thereto, and may have a shape including a plurality of linear portions and a connecting portion that connects end portions of adjacent linear portions.

  The embodiments and examples disclosed herein are illustrative in all respects and should not be construed as being restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  INDUSTRIAL APPLICABILITY The ion doping apparatus, the ion doping apparatus filament, and the manufacturing method thereof according to the present invention are required to improve the life while suppressing the increase in input power, the manufacturing method thereof, and the filament replacement. The present invention can be particularly advantageously applied to an ion doping apparatus that requires a reduction in frequency.

It is the schematic which shows the structure of the ion doping apparatus in one embodiment of this invention. It is a schematic sectional drawing which shows the structure of the filament for ion doping apparatuses in one embodiment of this invention. It is a flowchart which shows the outline of the manufacturing method of the filament for ion doping apparatuses in one embodiment of this invention. It is a schematic sectional drawing which shows the structure of the filament for ion doping apparatuses which is a modification of embodiment of this invention. It is a schematic sectional drawing which shows the conventional filament for ion doping apparatuses. It is a schematic sectional drawing which shows the state which the filament for ion doping apparatuses of FIG. 5 was used, and was damaged. It is a schematic sectional drawing which shows the other example of the conventional filament for ion doping apparatuses. It is a schematic sectional drawing which shows the state which the filament for ion doping apparatuses of FIG. 7 was used, and was damaged.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Ion doping apparatus, 10 Ion source, 11, 21 Filament, 12, 22 Straight part, 13, 23 Connection part, 14, 24 Large diameter part, 15, 25 Connection part, 31 Magnet, 33 Filament power supply, 34 Arc power supply, 35 extraction power source, 36 acceleration power source, 37 deceleration power source, 41 plasma electrode, 42 extraction electrode, 43 deceleration electrode, 44 ground electrode, 60 processing chamber, 61 doping stage, 62 plasma, 70 robot chamber, 71 transfer robot, 80 L / L chamber, 81 table, 91 valve door, 99 substrate.

Claims (6)

Consists of conductive wires,
A plurality of linear portions in which the lines extend linearly;
Among the plurality of straight portions, a connection portion that connects ends of the straight portions adjacent to each other, and
The filament for an ion doping apparatus, wherein a large-diameter portion having a larger filament cross-sectional area, which is a cross-sectional area in a cross-section perpendicular to the direction in which the line extends, is formed in the linear portion.   The filament for an ion doping apparatus according to claim 1, wherein the large-diameter portion is formed so that the filament cross-sectional area gradually decreases toward a region adjacent to the large-diameter portion.   3. The filament for an ion doping apparatus according to claim 1, wherein a filament cross-sectional area of the large-diameter portion is 1.1 to 4 times the filament cross-sectional area of the connection portion.   The length of the said large diameter part is a filament for ion doping apparatuses of any one of Claims 1-3 which are 2 to 50% of the full length of the said linear part and the said connection part.   The ion doping apparatus provided with the filament for ion doping apparatuses of any one of Claims 1-4. A method of manufacturing a filament for an ion doping apparatus comprising a conductive wire,
Preparing the base material;
When a trial operation filament is mounted on an ion doping apparatus in which the ion doping apparatus filament is used and the ion doping apparatus is subjected to a trial operation, the trial operation filament is damaged and thinned by the trial operation. The base material so that a filament cross-sectional area, which is a cross-sectional area in a cross section perpendicular to the direction in which the line extends, of a part corresponding to the damaged part is larger than a region adjacent to the part corresponding to the damaged part. A method of manufacturing a filament for an ion doping apparatus, comprising: a step of processing into a filament.

Images