JP2004296112A - Apparatus for generating ion for ion implantation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a short circuit from being formed by a conductive film formed on an electrode part in an arc chamber. <P>SOLUTION: This apparatus for generating ion for an ion implantation device is constituted by disposing the electrode parts face to face in the inner surfaces of end caps 22, 22a forming both ends of the arc chamber 23. In this apparatus 1 for generating ion, the electrode parts are supported in the inside of the arc chamber 23 through an insulating material 24, and a conductive film suppressing member F is applied to the electrode parts 26a, 28a to enhance insulation between the electrode parts and the arc chamber 23. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ion generator in an implantation apparatus for efficiently implanting ions of a target substance into an object to be processed, such as a semiconductor or a liquid crystal device, in a manufacturing process of a semiconductor, a liquid crystal device, or the like.
[0002]
[Prior art]
2. Description of the Related Art Flat panel displays such as liquid crystal displays are widely used for mobile phones, portable information terminals, notebook PCs, monitors for PCs, large televisions, and the like. In the liquid crystal display market, where demand is expected to grow significantly in the future, high precision, low power consumption, low price, and the like are strongly demanded.
[0003]
As a high-current wide-beam ion implantation apparatus used for manufacturing a small flat panel display used for such an application, an ion source that generates a large amount of ions and an ion beam extracted from the ion source are used. A mass separating magnet for expanding, deflecting and converging, a disassembly slit for blocking an undesired beam of the converged beam, and a second deflector for further deflecting and parallelizing the beam passing through the disassembly slit There has been proposed an apparatus which is composed of a magnet and forms a highly uniform wide ribbon beam with a current of 1 mA or more and an energy of several keV or more (for example, see Patent Document 1).
[0004]
In addition, a gas containing a target substance is ionized by plasma in an arc chamber to generate ions, and the ions are deposited in an ion source that moves the ions in the arc chamber to deposit the target substance. An apparatus has been proposed in which a member is disposed in an arc chamber, and ions are made to collide with the member to precipitate a substance, thereby generating an ion beam containing a large amount of a target substance (for example, see Patent Document 2).
[0005]
In addition, the present applicant manufactures and sells an ion beam implantation apparatus to which the basic principle of the patent described in Patent Document 1 is applied as “MD1-100”.
[0006]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 6-342639 [Patent Document 2]
JP-A-8-17375
[Problems to be solved by the invention]
Low-temperature polysilicon thin-film transistor liquid crystal displays that can achieve higher electron mobility than amorphous silicon and can integrate peripheral circuits with the aim of achieving the demands of high precision, high brightness, low power consumption, and low price. It became noticeable. In a process (source / drain) of manufacturing a TFT on a conventional low-temperature p-Si thin film, a method called an ion shower is mainly used. However, in order to manufacture a higher performance thin film transistor (TFT) on a low-temperature p-Si thin film, as described in the above-mentioned Patent Document 1, only ions are required by mass separation as in the semiconductor process. High-precision ion implantation technology that can control the dose accurately.
[0008]
In order to increase the amount of ions, it is sufficient to increase the amount of plasma by increasing the implant current. To achieve this, the beam line is kept at a high vacuum and the amount of the target material supplied into the arc chamber is increased. It is necessary to increase the amount of gas (BF ₃ , PH ₃ ) such as boron fluoride.
[0009]
As shown in FIG. 2, the ion implantation apparatus 1 has an ion source 2 (burner type ion generator) that supplies a large amount of gas containing impurities to generate ions. x is extracted from the ion source 2 by the extraction electrode 3 and accelerated.
[0010]
The ion beam X extracted from the ion source 2 is bent by approximately 90 ° by the mass separation magnet of the mass separation unit 6, and only ions a having a predetermined mass are extracted. At this time, selectable ions c and d such as light ions and heavy ions are excluded.
[0011]
After that, the intensity of the ion beam X is uniformly averaged by the uniform control mechanism 7 (multipole), and then the glass substrate (coated member) attached to the platen (support member) disposed in the process chamber (end station) 8 is used. (Processing body) 9.
[0012]
The vacuum chamber 5 which communicates the path from the ion generation source 2, the mass separation unit 6, and the uniform control mechanism 7 to the process chamber 8 has a high-vacuum vacuum (not shown) particularly at a position subsequent to the uniform control mechanism 7. A pump is connected, and the entire vacuum chamber 5 constitutes a high vacuum evacuation system 10.
[0013]
Now, in order to increase the amount of ions by increasing the amount of plasma, it is necessary to generate ions more efficiently than the ion source 2 (ion generator) as described above. As shown in FIG. 3, this ion generator is formed of a base plate 20, two side plates 21, and two end caps 22, 22a, and has an elongated box-shaped arc chamber 23 having an open surface, A filament 25 and a cathode plate 26 are provided on the end cap 22 with an insulator 24 (gauge) interposed therebetween, and a repeller plate 28 is provided on the other end cap 22a side with an insulator 24a interposed therebetween. The source aperture 23a (FIG. 2, lid) having an elongated opening hole on the opening surface is provided.
[0014]
A magnet 29 is disposed on the two end caps 22 and 22a to apply a static magnetic field 30 from the cathode plate 26 to the repeller plate 28 in the arc chamber 23.
[0015]
When the ion generator 1 is operated, a gas g of a substance for generating a substance for ion implantation is supplied from a gas supply source 31 while maintaining the inside of the arc chamber 23 at a high vacuum by a vacuum pump. An electric current is supplied to the filament 25 from the filament power supply 32 to generate heat at a high temperature (about 2000 ° C. or higher). Further, an arc voltage V is applied between the filament 25 and the arc chamber 23 from the arc power supply 33 so that the cathode plate 26 and the repeller plate 28 A plasma P is generated by an arc discharge in between, and an ion beam X is emitted to a beam line of the ion implanter 1 from an opening of the source aperture 23a.
[0016]
In the arc chamber 23, thermoelectrons generated from the filament 25 and ions in the plasma are affected by the static magnetic field 30, and spirally move (cyclotron motion), so that the ions and electrons collide with molecules of the source gas g. Are repeated to make it easier to maintain the plasma P (FIG. 4).
[0017]
For example, when the static magnetic field 30 is not applied in the ion source 2, ions and electrons move in a linear trajectory, and the chances of the ions and electrons colliding with the molecules of the source gas g are reduced. Thus, by applying a static magnetic field 30 to give spiral motion to ions and electrons to increase the chances of collision with the molecules of the raw material gas g, the plasma P is extruded in a sausage shape toward the center of the arc chamber 23.
[0018]
(Problems of conventional equipment)
A state in which the ion generator is operated while supplying a gas g containing fluorine such as boron trifluoride to the ion generator 2 of the ion implanter 1 will be described. As a result, an unstable state in which the amount of ions x required could not be generated in a large amount occurred because the plasma P generated in 2 gradually decreased.
[0019]
After examining this phenomenon, when a gas containing fluorine such as boron trifluoride was supplied to the molybdenum arc chamber 23, the inner surface of the arc chamber 23 was corroded by the ionized and highly reactive fluorine. It has been found that this causes insulation failure.
[0020]
FIG. 5 is an explanatory view of the state of the insulation failure. Metal atoms generated from the material of the arc chamber 23 are mixed and moved in the ionized gas. A cathode plate 26 is supported on the end cap 22 of the arc chamber 23 via two insulators 24 (portions), and a filament 25 (1.5-turn pigtail shape) penetrates the insulator 24. The metal atoms generated from the material of the arc chamber 23 as described above are deposited on the surface of the insulator 24 to form thin conductive films M1 and M2.
[0021]
The conductive films M1 and M2 are films formed by depositing metal atoms such as molybdenum and tungsten, which are materials of an arc chamber, for example. When this occurs, the cathode plate 26 and the filament 25 pass through the surface of the insulator 24. An electric circuit is formed between the electric circuit and the arc chamber 22, and a leakage current R flows through the electric circuit.
[0022]
Since the insulator 24 is in a state of being electrically degraded by the conductive films M1 and M2, it is difficult to maintain the arc voltage V, and a stable sausage shape over the entire length of the arc chamber 23 as shown in FIG. Is difficult to generate.
[0023]
The behavior of generating metal atoms from the material of the arc chamber 23 will be described as follows.
[0024]
For example, if molybdenum is used for the material of the arc chamber 23, in the case of feed gas trifluoride gas, fluoride gas, "nF ⁺ + Mo → MoFn" is generated, also high fever, "MofN → nF by plasma ⁺⁺ Mo "occurs. The generated molybdenum atoms are deposited as the conductive films M1 and M2 on the insulator 24 as shown in FIG.
[0025]
As the metal material constituting the arc chamber 23, heat-resistant molybdenum, tungsten, or the like is used. However, since the temperature inside the arc chamber 23 becomes high, it is necessary to easily change this material to another material. Can not.
[0026]
An object of the present invention is to eliminate the disadvantage that the insulators 24 and 24a supporting the cathode plate 26, the repeller plate 28, and the like in the prior art described above become defective in insulation and cause plasma degradation.
[0027]
[Means for Solving the Problems]
An ion generator for an ion implantation apparatus according to the present invention for achieving the above object is configured as follows.
[0028]
1) In an ion generator in which an electrode portion is disposed facing an inner surface of an end cap forming both ends of an arc chamber, the electrode portion is supported inside the arc chamber via an insulator, and the electrode portion is electrically conductive. It is characterized in that the insulating property between the electrode section and the arc chamber is enhanced by applying a film suppressing member.
[0029]
2) In an ion generator in which electrode portions are arranged facing the inner surface of an end cap forming both ends of an arc chamber, the one electrode portion includes at least a filament, and the other electrode portion is a repeller plate. A conductive film inhibiting member is provided on the side facing the end cap to enhance insulation between the electrode section and the arc chamber.
[0030]
3) In an ion generator in which an electrode portion is disposed on the inner surface of an end cap forming both ends of an arc chamber, the one electrode portion includes at least a filament, the other electrode portion is a repeller plate, and the end cap Is formed of a conductive film inhibiting member.
[0031]
4) In an ion generator in which electrode portions are arranged on inner surfaces of end caps forming both ends of an arc chamber, the one electrode portion is formed by a filament and a cathode plate, and the other electrode portion is formed by a repeller plate. The cathode plate and the repeller plate are characterized in that a conductive film inhibiting member is provided on the side facing the end cap to enhance insulation between the electrode section and the arc chamber.
[0032]
5) The conductive film inhibiting material is a compound of an element such as aluminum oxide and aluminum nitride that does not form a conductive film in an atmosphere at 1000 to 2500 ° C. after thermal decomposition.
[0033]
6) The ion implantation apparatus generates an ion and sends it to a beam line. The ion implantation apparatus selects the ions sent from the ion source by a mass separation magnet and converts the ions having a predetermined mass into an ion processing station. It is characterized by having a beam line leading to
[0034]
In the present invention, a layer made of a conductive film suppressing material is formed on the surface of the electrode portion, specifically, both the cathode plate and the repeller plate made of a metal plate, or the surface facing the end cap of the member on which the conductive film is easily deposited. The formation prevents the conductive film from growing starting from the cathode plate and the repeller plate. As a result, the gap between the arc chamber 23 and the cathode plate 26 or the arc chamber 23 and the repeller plate 28 as shown in FIG. To prevent or suppress the occurrence of leakage R due to the formation of a conductive circuit.
[0035]
In some cases, the same effect can be obtained even if the inner surface of the end cap is formed of a layer made of the conductive film inhibiting material.
[0036]
As a conductive film inhibiting material, a compound of an element which does not form a conductive film in an atmosphere of 1000 to 2500 ° C. after thermal decomposition using a heat-resistant material such as aluminum oxide, aluminum nitride, boron nitride or the like is used. it can. For example, although aluminum oxide may precipitate at high temperature, aluminum oxide does not deposit a metal film on the surface of the insulator because of its low boiling point.
[0037]
The present invention relates to a cathode plate disposed on an electrode portion such as a cathode plate or a repeller plate, a surface of an insulator supporting the electrode portion during operation of the ion generator, for example, a cathode plate disposed at a root of a filament which is one of the electrodes. Up to the back side, it is intended to prevent the metal atoms forming the arc chamber from depositing and depositing on the surface of the insulator by being formed in a state extended by the conductive film inhibiting material. is there.
[0038]
In this sense, the conductive film inhibiting material is preferably a compound made of an element that does not form a conductive thin film in an atmosphere at 1000 to 2500 ° C. after decomposition, such as aluminum oxide and aluminum nitride. By selecting a substance that does not have a conductive function even when deposited on the surface of the insulator forming the electrode portion, a highly efficient ion source can be configured.
[0039]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present invention will be described with reference to FIG.
[0040]
The configuration of the arc chamber 23 itself is the same as that of the apparatus shown in FIG. 3 and the like. However, in the present invention, the surface layer F made of a material conventionally used for the cathode plate 26a and the conductive film suppressing It is characterized in that a two-layer structure composed of a back layer B made of a material (a heat-resistant insulating material) or a composite plate structure is formed.
[0041]
This composite plate structure is similarly formed not only on the cathode plate 26a but also on the opposing repeller plate 28a side, and has the same effect.
[0042]
The thickness of the back layer B does not need to be as large as that of the front layer F, that is, the thickness of the conventional cathode plate, and the conductive films M1 and M2 are formed on the insulator 24 as shown in FIG. It may be of a degree that can be suppressed, for example, when boron nitride is used for the backside layer B, it may be about 0.2 to 2 mm, and the processing method of the backside layer B is after coating or laminating. Various methods such as lamination and pasting without gaps such as baking can be adopted.
[0043]
Further, the cathode plate 26a and the repeller plate 28a do not have a structure in which two plate members are joined as shown in FIG. The structure may be such that an insulating material is arranged at the bottom.
[0044]
According to the present invention, an electrode including a cathode plate 26a and a repeller plate 28a supported in an arc chamber 23 via an insulator is formed in a two-layer structure including a metal layer and an insulating layer to support the cathode plate 26a and the like. Since the surface in contact with the insulator is formed of an insulating conductive film inhibiting material, metal atoms generated from the material of the arc chamber 23 when forming the plasma adhere and deposit on the insulators 24 and 24a. A conductive film is not formed.
[0045]
Therefore, an arc can be discharged at a high temperature and a high vacuum to form plasma accurately and efficiently in the arc chamber 23, so that ions can be generated stably. As a result, high-performance ion implantation can be performed. An apparatus can be provided.
[0046]
【The invention's effect】
An ion generator for an ion implanter according to the present invention is an ion generator in which an electrode portion is arranged on an inner surface of an end cap forming both ends of an arc chamber with the electrode portion facing each other. In addition to being supported inside, an insulating property between the electrode portion and the arc chamber is enhanced by applying a conductive film inhibiting member to the electrode portion.
[0047]
Therefore, the formation of a conductive film that forms a short circuit between one or both of the cathode plate and the repeller plate and the arc chamber can be suppressed, so that a high-performance ion implanter can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a burner-type ion source according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram of an ion implantation apparatus.
FIG. 3 is a cross-sectional view of a conventional ion source.
FIG. 4 is an explanatory diagram of plasma generated inside an ion generation source.
FIG. 5 is an explanatory diagram of a state of forming a conductive film generated by a conventional ion generating source.
[Brief description of reference numerals]
DESCRIPTION OF SYMBOLS 1 Ion implantation apparatus 2, 2a Ion generation source 3 Extraction electrode 4 Gas shut-off plate 5 Vacuum chamber 6 Mass separation unit 7 Uniform control mechanism 8 Process chamber 9 Glass substrate 20 Base plate 21 Side plate 24 Insulator 22, 22a End cap 23 Arc chamber 25 Filaments 26, 26a Cathode plate 28, 28a Repeller plate 29 Magnet 30 Static magnetic field 31 Gas supply source F Surface layer (metal layer) B Back layer (layer of conductive film inhibiting material)
R Leakage current

Claims (6)

In an ion generator in which an electrode portion is disposed on an inner surface of an end cap forming both ends of an arc chamber, the electrode portion is supported inside the arc chamber via an insulator, and a conductive film is inhibited by the electrode portion. An ion generator for an ion implanter, wherein a member is applied to enhance insulation between the electrode section and the arc chamber. In an ion generator in which an electrode portion is disposed on an inner surface of an end cap forming both ends of an arc chamber, the one electrode portion includes at least a filament, the other electrode portion is a repeller plate, and the end cap of the repeller plate is provided. 2. The ion generator according to claim 1, wherein a conductive film suppressing member is provided on the side facing the electrode chamber to enhance insulation between the electrode section and the arc chamber. In an ion generator in which an electrode portion is disposed facing an inner surface of an end cap forming both ends of an arc chamber, the one electrode portion includes at least a filament, the other electrode portion is a repeller plate, and an inner surface of the end cap. 2. The ion generator for an ion implantation apparatus according to claim 1, wherein said member is formed of a conductive film suppressing member. In an ion generator in which electrode portions are arranged facing the inner surface of an end cap forming both ends of an arc chamber, the one electrode portion is formed by a filament and a cathode plate, and the other electrode portion is formed by a repeller plate. 2. The ion implantation apparatus according to claim 1, wherein a conductive film inhibiting member is provided on a side of the cathode plate and the repeller plate facing the end cap to enhance insulation between the electrode portion and the arc chamber. Ion generator. 2. The ion according to claim 1, wherein the conductive film inhibiting material is a compound of an element such as aluminum oxide or aluminum nitride that does not form a conductive film in an atmosphere at 1000 to 2500 ° C. after thermal decomposition. 3. Ion generator for implanters. The ion implantation apparatus generates an ion and sends it to a beam line, and selects ions sent from the ion source by a mass separation magnet to guide ions of a predetermined mass to an ion processing station. The ion generator according to claim 1, further comprising a beam line.

Images