WO2006011227A1

WO2006011227A1 - NEUTRARIZATION APPARATUS EMPLOYING α RAY

Info

Publication number: WO2006011227A1
Application number: PCT/JP2004/010924
Authority: WO
Inventors: Tadahiro Ohmi; Hitoshi Naito; Makoto Moriguchi; Kenji Ueda
Original assignee: Omron Corporation
Priority date: 2004-07-30
Filing date: 2004-07-30
Publication date: 2006-02-02

Abstract

[PROBLEMS] Neutralization equipment employing α-rays in which atmospheric ions produced through ionization by irradiating α-rays can touch an object to be neutralized efficiently while surely avoiding such a situation as the object to be neutralized is irradiated directly with α-rays emitted from an α-ray source. [MEANS FOR SOLVING PROBLEMS] The neutralization equipment employing α-rays comprises an α-ray shield box (10) provided with an ion discharging opening (11), and one or more α-ray sources (12) being contained in the α-ray shield box, wherein atmospheric ions produced through ionization by irradiating α-rays emitted from respective α-ray sources (12) are discharged from the ion discharging opening (11) to touch an object to be neutralized. The α-ray sources (12) in the α-ray shield box (10) are positioned such that the α-ray particles being emitted therefrom do not reach the object to be neutralized and atmospheric ions are produced through ionization at a position facing the ion discharging opening (11).

Description

Specification

Static eliminator using wire

Technical field

TECHNICAL FIELD [0001] The present invention relates to a static eliminator that neutralizes static electricity generated on the surface of a product, for example, in the process of manufacturing a semiconductor wafer, a liquid crystal glass substrate, etc., using an ambient ion source, and in particular, a line source. The present invention relates to a static eliminator using as an atmosphere ion source.

Background art

[0002] In the manufacturing process of products such as semiconductor wafers, glass substrates for liquid crystals, magnetic disks' substrates for optical disks, printed boards, various films, etc., the surface may be charged (static electricity) due to friction between components. Are known. In the case of a semiconductor wafer, the charge generated in this way can be a factor of surface contamination due to element destruction, product performance deterioration, or dust (particle) adhesion.

[0003] Therefore, various types of static eliminator using an atmospheric ionization source have been used as such a charge eliminator in recent years. For example, an atmosphere that is ionized and generated by each atmosphere ionization source has a shielding box that is closed around leaving an ion emission opening, and one or more atmosphere ionization sources that are accommodated in the shielding box. 2. Description of the Related Art There is known a static elimination device that emits ions from an ion emission opening and irradiates a static elimination object. As an ionization source, a tungsten electrode for corona discharge, a UV lamp for ultraviolet radiation, a soft X-ray discharge tube for soft X-ray irradiation, or the like is used (for example, see Patent Document 1).

[0004] In a static eliminator using corona discharge, an electric field having a predetermined strength or higher is generated at the tip of the electrode by applying a high voltage to the tungsten electrode. As a result, ions are generated in the atmosphere, and the charge (charge) on the surface of the object to be neutralized is neutralized by these ions.

[0005] Further, a static eliminator that uses ultraviolet rays utilizes the action of irradiating ultraviolet rays into the atmosphere with a UV lamp, whereby molecules in the atmosphere are ionized. As the atmosphere, for example, nitrogen gas is used. used.

[0006] For those using soft X-rays, a soft X-ray discharge tube is used to irradiate soft X-rays into the atmosphere. This ionizes molecules in the atmosphere.

[0007] By the way, among the static eliminators described above, the static eliminator using corona discharge and ultraviolet rays has a problem when ozone is generated that causes damage to the static eliminator. In the static eliminator using ultraviolet rays and soft X-rays, there is a problem that the tungsten electrode, the UV lamp, the discharge tube, etc. that have a complicated maintenance and a relatively short life must be used. It has been pointed out that it is difficult, and recently, a static eliminator using a wire has been proposed.

In a static eliminator using a strand, generally, a thin piece of americium or polonium is used as a strand source. From this flake, a flight line with a flight distance of about 4 cm is irradiated, and thereby ions are ionized and generated in the atmosphere.

[0009] In the static eliminator using this wire, if the maintenance is complicated and the life is relatively short, it is replaced with a discharge tube having a defect, etc., and the wire source with a long half-life (long life) ( Atmosphere ionization source) is used, and there is no risk of ozone generation, which is advantageous in terms of avoiding contamination of products and ease of maintenance. Various types have been proposed recently. (See, for example, Patent Documents 2 and 3)

Patent Document 1: JP 2001-176691 A

Patent Document 2: JP-A-7-45397

Patent Document 3: Japanese Patent Laid-Open No. 7-211483

Disclosure of the invention

Problems to be solved by the invention

[0010] However, in the static eliminator using α-rays, the following problems (1) and (2) are pointed out.

[0011] (1) Since the flight distance of α-ray particles is as short as about 4 cm, the distance between the a-ray source and the charge removal object must be set in order to efficiently bring the ionized and generated atmospheric ions into contact with the charge removal object. It must be kept relatively short. In such a case, α-rays may be directly irradiated on the object to be neutralized, which immediately causes deterioration of the product of the non-static object.

[0012] (2) exposure by _α rays static elimination target as described above in order to avoid (direct irradiation), the atmosphere ions generated ionized by _α rays, the predetermined distance from the shed-ray source isolated ion release for A method of sending air to the opening by air blowing has been proposed (see, for example, Patent Document 1). However, in such a case, the residence time of the atmospheric ions ionized and generated in the wire shielding box becomes longer, and during that time, the atmospheric ions recombine with each other, so that necessary and sufficient ions cannot be released. Disadvantages are known.

[0013] The present invention has been made by paying attention to the above-mentioned problems, and the object of the present invention is to ensure that the object to be neutralized is directly irradiated with the strands irradiated from the a-ray source. Another object is to provide a static eliminator using a strand that makes it possible to efficiently contact atmospheric ions ionized and generated by the strand irradiation with the object to be neutralized.

[0014] Still other objects and effects of the present invention will be easily understood by those skilled in the art by referring to the description of the following specification.

Means for solving the problem

[0015] In order to achieve the above object, the static eliminator using α rays of the present invention includes an α ray shield surrounding a wire source by a shielding surface for shielding the wire and an ion emission opening. A box and one or more α-ray sources housed in an a-ray shielding box, and ionize atmospheric ions ionized by irradiation of α-rays emitted from each of the radiation sources A neutralization device using a strand that is emitted from the opening for contact with the object to be neutralized. Positioned so that the line never reaches.

[0016] The "position where the static elimination target object is installed" is a position where a predetermined static elimination target object should be placed when using this apparatus. When the installation position has a certain range, it means the position closest to the static eliminator. This position may coincide with the outer surface of the α-ray shielding box where the ion emission opening is located.

[0017] Examples of the "ray source" include almesium and polonium.

[0018] In the case of “the wire cannot reach,” the case where the wire does not collide with the shielding surface and disappears in the surroundings while flying in the atmosphere. Including the case where it interacts with molecules and goes straight, but disappears at the end due to loss of kinetic energy. The maximum reachable distance (α flight distance) at this time is known from the empirical formula. At atmospheric pressure and in the air, it is about 4 to 7 eMV for α-ray particles with kinetic energy. 4cm. It can be considered that the α-ray particle itself does not exist at a point that is more than the α-ray flight distance from the α-ray source.

According to the static eliminator using α-rays of the present invention, it is possible to reliably avoid the situation where the α-rays irradiated from the α-ray source are directly irradiated to the static elimination object. On the other hand, atmospheric ions are generated well in the vicinity of the ion emission opening, and the atmospheric ions can be efficiently brought into contact with the static elimination object, thereby improving the static elimination efficiency.

[0020] Preferably, in the present invention, the outer contour shape of the space where the wire reaches is inside the outer contour shape of the wire shielding box as viewed from the side where the ion emission opening is provided.

[0021] According to such a configuration, in the state where the static eliminator is installed with respect to the static eliminator, even if a human hand may pass around the static eliminator, Even if an object is installed close to the device, it is safe because the a-line is not directly irradiated.

[0022] In the present invention, preferably, the wire shielding box has an objective shielding surface on a surface on the side of the static elimination object, and the shielding surface faces the static elimination object within an _α ray flight distance from the _α ray source. The alpha rays radiated are blocked.

[0023] According to such a configuration, the object to be neutralized is removed from the line flight distance with respect to the static eliminator using the line while reliably avoiding the situation where the α-ray is directly irradiated to the object to be neutralized. Can also be placed close together. At this time, since atmospheric ions are also generated near the object to be neutralized, the number of ions annihilated by recombination before reaching the object to be neutralized decreases, and the efficiency of static elimination increases.

In the present invention, more preferably, the α-ray shielding box is separated from the flight distance of the α-ray in the direction of the α-ray emitted from the α-ray source along the opening surface of the ion emission opening. It has a side shielding surface at the position.

[0025] “The direction of the line to be emitted along the opening surface” is sufficient if it is at least one direction.

[0026] The "side shielding surface" means a shielding surface on the side when the surface with the ion emission opening of the wire shielding box is the front.

[0027] According to such a configuration, the strands emitted in the direction along the opening surface of the ion emission opening are not shielded by the shielding surface at a distance shorter than the strand flight distance. each The maximum amount of ionized ions can be generated for each α-ray.

[0028] In the present invention, more preferably, the α-ray source is arranged so that the shielding surface of the α-ray shielding box is located ahead of all α-ray direct directions assumed from the position of the α-ray source. Is done.

[0029] In atmospheric air, the flying distance of filament particles is about 4cm, but depending on the pressure and the type of atmospheric gas, all filament particles disappear at locations exceeding this flight distance. There may not be. Therefore, if the line source is placed so that the wall shielding surface of the line shield box is located at the front of all the direct radiation directions assumed from the position of the line source, under any operating conditions The possibility of external leakage of filament particles can also be completely eliminated. In addition, according to such a configuration, the radiation source is installed at a position that cannot be seen from the outside, that is, at a deep position, so that it is possible to prevent human exposure due to contact with the radiation source due to carelessness. It can prevent well.

[0030] In the present invention, it is more preferable that a pair of α-ray sources arranged opposite to each other in the α-ray shielding box so as to sandwich the region where the atmospheric ions are ionized and generated by the irradiation of the strands are employed as the radiation source. The

[0031] According to such a configuration, generation of atmospheric ions can be promoted by a pair of α-ray sources.

The invention's effect

[0032] As is clear from the above description, according to the static eliminator of the present invention, it is possible to reliably avoid the situation in which the a-line irradiated from the wire source is directly irradiated to the static elimination object, while the a-line Atmospheric ions ionized by irradiation can be efficiently brought into contact with the object to be neutralized. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a preferred embodiment of a static eliminator using α rays according to the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are merely examples of the present invention, and needless to say, the gist of the present invention is defined only by the claims.

[0034] The configuration of the static eliminator using α rays in the present embodiment (hereinafter referred to as the α ray static eliminator) is shown in the internal perspective view of FIG.

[0035] As shown in the figure, this wire neutralizing device 1 is a substantially rectangular parallelepiped hollow α-ray shielding box 1 A thin piece of americium 12 as an α-ray source is attached to the inner wall surface of 0. In this example, aluminum is used as the material of the wire shield box. In this example, two American thin pieces 12a and 12b are used, and are attached to both side walls (10b_l and 10b_2) along the longitudinal direction of the α-ray shielding box 10 so as to face each other. The americium flakes 12 shown in this example emit less than 3.7MB q of radiation that is not subject to legal regulations.

[0036] At the center of the upper wall surface 10a of the wire shield box 10, an ion emission opening 11 is provided along the longitudinal direction of the wire shield box 10. In the static eliminator 1, atmospheric ions are constantly ionized and generated by the action of the strands irradiated from each of the americium slices 12. The atmospheric ions are released from the ion discharge opening 11 and are subjected to static elimination. Contact objects. Examples of static elimination objects include semiconductor wafers, liquid crystal glass substrates, magnetic disk optical disk substrates, printed circuit boards, and various films. The object to be neutralized is located immediately above the ion emission opening 11 in the direction of the arrow indicated by X in FIG. 1 (the direction orthogonal to the longitudinal direction of the α-ray shielding box 10, hereinafter referred to as a pass line). Moved (scanned). Through this scanning, atmospheric ions leaking from the ion release aperture force are brought into contact with the surface of the object to be neutralized, and the charge on the surface of the object to be neutralized is neutralized.

The arrangement state of the americium flakes 12 in the α-ray static elimination apparatus 1 is shown in FIG. This figure is also a cross-sectional view of the α-ray shielding box 10 shown in FIG.

[0038] The arrival distance of α-ray particles irradiated from americium is about 4 cm, and it is known that it has the property of being absorbed when it hits a metal body. In FIG. 2, the hatched areas indicated by the symbols S 1 and S 2 indicate the arrival area of the α-ray particles from the americium flakes 12 predicted from the properties of the α-ray particles.

[0039] As is clear from the figure, the highest point near the a-line ion emission opening 11 irradiated from each of the americium flakes 12a and 12b is the upper wall 10a of the wire shielding box 10. It may be a line shield (object shielding surface), and is present at the position indicated by the symbols Pl and P2 in the same figure (the bare position that does not go outside from the ion emission opening 11).

[0040] In the present embodiment, the americium flakes 12 are placed in the strand shielding box 10 in consideration of such strand maximum points Pl and P2. In this way, the americium flakes 12 are placed. As a result, it is possible to reliably avoid a situation in which α rays are directly applied to the charge removal object passing through the pass line located immediately above the ion emission opening 11. On the other hand, since α rays reach and reach the ion emission opening 11, an atmosphere ion is always ionized and generated near the ion emission opening 11, and this atmosphere ion is emitted from the ion emission opening 11. As a result, the charge on the surface of the object to be neutralized can be satisfactorily neutralized.

[0041] It should be noted that the atmospheric ions emitted from the ion emission opening 11 are not only those ionized and generated near the ion emission opening 11, but in the wire shielding box 10 (wire particle arrival regions S1, S2 ) Is considered to include all atmospheric ions ionized. However, it has been pointed out that the atmospheric ions ionized and generated in the wire shielding box 10 may cause recombination between positive and negative ions when the existence density is high or the retention time is long. Therefore, in this embodiment, as is clear from FIG. 2, the shortest distance between the americium flakes 12a and the americium flakes 12b is at least twice as long as the reach distance of the filament particles (about 4 cm). It is kept in. By doing so, collision of α-ray particles irradiated from both americium flakes 12 is avoided, thereby suppressing recombination between positive and negative ions generated by ionization.

[0042] However, if the possibility of such recombination between positive and negative ions is not taken into consideration, the shortest distance between the thin film 12a and the thin film 12b is the shortest distance of the filament particles (about 4cm). It can be less than double. In this case, overlapping regions of α-ray particles from both americium flakes are formed, so the generation density of atmospheric ions is increased, and as a result, atmospheric ions contributing to static elimination can be obtained more efficiently. .

Next, a modification of the present invention is shown in FIG. The difference from the embodiment shown in FIG. 2 is that the American thin piece 12 is arranged on the side closer to the object to be neutralized それ, and accordingly, the highest point Pl of wire Pl, Ρ2 force ions It is located outside the discharge opening 11. With this configuration, atmospheric ions are generated near the static elimination object 除, so the number of ions that disappear due to recombination before reaching the static elimination object 減少 is reduced, and the static elimination efficiency is high. Become.

[0044] Next, FIG. 4 shows a first application example of the wire neutralizing device according to the present invention.

[0045] In the first application example, one piece of americium flake 120 and a U-shaped cross-section with the upper surface opened. A container 100 as an α-ray shielding box is used. This figure shows a longitudinal sectional view of the container 100. The americium flake 120 is disposed at the center of the bottom wall of the container 100. In the figure, the hatched area indicated by the symbol S is an α-ray reaching area that is assumed from the arrangement position of the americium slice 120.

[0046] Also in this first application example, the highest point of the shin line irradiated from the americium flake 120 toward the ion emission aperture 110 is at a position that does not go outside from the ion emission aperture 110. Exists. For this reason, similarly, it is possible to reliably avoid a situation in which a line is directly applied to the static elimination object passing through the pass line located immediately above the ion emission opening 110, while the vicinity of the ion emission opening 110 is avoided. In this case, atmospheric ions are always ionized and generated, and the atmospheric ions are discharged from the ion discharge opening 110, so that the charge on the surface of the object to be neutralized can be neutralized well.

[0047] However, in the first application example, since the container 100 without the upper wall is used, a part of the human body (for example, a finger or the like) accidentally enters the ion emission opening 110 and touches the americium flake 120. It also has the disadvantage of being susceptible to radiation exposure. From this point, as shown in Fig. 1, Fig. 2, or Fig. 3, the wire shield box is not easily touched directly with the americium flakes, i.e., the surrounding area leaving the minimum necessary ion emission opening. It would be preferable to use one that is closed.

FIG. 5 shows a second application example of the α-ray static elimination device according to the present invention. This second application example is also a modification of the first application example described above. The difference from the first application example is that the α-ray irradiation region S protrudes outside the ion emission opening 110. However, the outer contour shape of the space where the wire reaches is included in the outer contour shape of the a-line shielding box (inside the imaginary line L1 and imaginary line L2) as viewed from the side where the ion emission opening 110 is provided. The same is true for the points. According to such a configuration, atmospheric ions are generated closer to the static elimination object M, so that the number of ions that disappear due to recombination before reaching the static elimination object M is reduced, resulting in high static elimination efficiency. can do. On the other hand, when a static eliminator is installed on an object to be neutralized, even if a human hand may pass around the static eliminator, an object will be installed close to the static eliminator. Even if this is the case, it is safe because it is not irradiated directly. Next, FIG. 6 shows a third application example of the α-ray static elimination apparatus according to the present invention.

[0050] In the third application example, one americium thin piece 120 and an approximately rectangular parallelepiped α-ray shielding box 100 having an upper wall 100a and provided with an ion emission opening 110 on one side are used. This figure is a longitudinal sectional view of the α-ray shielding box 100.

[0051] In the third application example, the americium flake 120 is arranged on the upper side wall on the left side of the figure. In the figure, the hatched area indicated by the symbol S is a stranded line reaching area where the arrangement position force of the americium slice 120 is also assumed. Also, in the figure, the alternate long and short dash line indicated by the symbol L indicates the highest point ひ in the vicinity of the ion emission opening 110 and the upper end of the americium flake 120 (the point closest to the ion emission opening 110). ).

[0052] Also in this third application example, the highest point ひ of the wire radiated from the americium flake 120 toward the ion emission opening 110 is at a position where it does not go outside from the ion emission opening 110. Exists. The characteristic point is that in the third application example, the position force of the americium flake 120 is located in front of all the assumed direct α-ray directions (for example, the imaginary line L). It is in the point. By adopting such a configuration, it is possible to completely eliminate the possibility of external leakage of filament particles under any use conditions. In addition, according to such a configuration, since the α-ray source is installed at a position that cannot be seen from the outside, that is, at a deep position, it is possible to prevent human exposure due to inadvertent contact with the α-ray source. It can prevent well.

[0053] In this third application example, in the third application example, in the direction of α rays (for example, imaginary line L) emitted from the americium flake 120 along the opening surface of the ion emission aperture 110, α It is considered that the side shielding surface 100b is located at a position separated from the flight distance of the line (about 4cm). With this configuration, the wire emitted in the direction along the opening surface of the ion emission opening 110 is not shielded by the shielding surface at a distance shorter than the wire flight distance. The maximum amount of ionized ions can be generated for each strand.

Next, FIG. 7 shows a fourth application example of the wire neutralizing device according to the present invention. This example is also a modification of the third application example. The difference from the third application example is that the highest point P1 of the wire is located outside the ion emission opening 110. With such a configuration, atmospheric ions as in the modification shown in FIG. 3 are generated closer to the static elimination object M. The power S can be increased by reducing the number of ions that disappear due to recombination before reaching the object M, and increasing the static elimination efficiency.

[0055] In the fourth application example, the same applies to the third application example, but the wire shielding box 100 functions as an objective shielding surface on the surface of the static elimination object M side. It is configured to have an upper wall 100a. This upper wall 100a partially shields the wire radiated from the americium flake 120 toward the static elimination object M. That is, the line flight distance range S2 surrounded by the imaginary line L2 extending to the original maximum line reach point indicated by the symbol P2 and the virtual line L1 extending to the actual line maximum point P1 is shown in FIG. Excluded by upper wall 100a. For this reason, the force S can be placed closer to the neutralization device than the line flight distance S, while avoiding the situation where the filament is directly applied to the neutralization object M. . At this time, since atmospheric ions are also generated near the object to be neutralized, the number of ions that disappear due to recombination before reaching the object to be neutralized is reduced, and the efficiency of static elimination is increased.

As is clear from the above description, according to the present embodiment, it is possible to reliably avoid the situation where the α-ray particles irradiated from the americium flakes are directly irradiated (exposed) to the static elimination object. On the other hand, the ability to efficiently contact atmospheric ions ionized by α-ray irradiation with the object to be neutralized, S, provides a static elimination device with high static elimination efficiency. In addition, by grounding the bottom wall surface of the α-ray shielding box with a conductor, it is possible to further improve the static elimination efficiency of the static elimination object.

[0057] In the above description, polonium may be used as the force α-ray source using americium flakes as the α-ray source. Industrial applicability

[0058] The static eliminator using the wire of the present invention is applied to the surface of a semiconductor wafer, a liquid crystal glass substrate, a magnetic disk, a product such as an optical disk substrate, a printed circuit board, and various films due to friction between components. It is useful for removing the generated static electricity.

Brief Description of Drawings

[0059] FIG. 1 is an internal perspective view showing a configuration of an α-ray neutralizing apparatus according to the present invention.

FIG. 2 shows in detail the arrangement of americium flakes in the wire neutralizing device according to the present invention. It is a figure.

FIG. 3 is a diagram showing a modification of the present invention.

FIG. 4 is a diagram (No. 1) showing an _α- ray static eliminator to which the present invention is applied.

FIG. 5 is a diagram (part 2) showing a wire neutralizing device to which the present invention is applied.

FIG. 6 is a diagram (No. 3) showing a strand neutralizing device to which the present invention is applied.

FIG. 7 is a diagram (No. 4) showing a strand neutralizing device to which the present invention is applied. Explanation of symbols

1 α-ray static eliminator

10 α-ray shielding box

11 Ion emission opening

12 Americium flakes

対象 Target for static elimination

S α ray arrival area

P line maximum reachable point

X pass line (moving direction of static elimination object)

Claims

The scope of the claims

[1] A wire shielding box surrounding the wire source by a shielding surface for shielding the wire and an ion emission opening, and one or more wire sources accommodated in the wire shielding box; Static electricity removal using a wire that discharges atmospheric ions ionized by irradiation of the wire emitted from each wire source and releases the opening force for ion emission to contact the object to be removed The wire source in the wire shielding box is a device in which atmospheric ions are not allowed to reach the position where the object to be neutralized is installed and the alpha rays emitted from each of them reach the opening for ion emission. A static eliminator using alpha rays, characterized by being positioned so as to generate ionization.

[2] The α according to claim 1, wherein the outer contour of the α-ray shielding box viewed from the side where the ion emission opening is provided includes the outer contour of the space where the α-ray reaches. Static eliminator using wires.

[3] The α-ray shielding box has an objective shielding surface on the surface to be neutralized, and the shielding surface is radiated from the α-ray source toward the static elimination object within the α-ray flight distance. The static eliminator using alpha rays according to claim 1, characterized in that the lines are shielded.

[4] The a-line shielding box has a side shielding surface in a direction away from the flight distance of the wire in the direction of the wire that is emitted from the wire source along the opening surface of the ion emission opening. The _α- ray static eliminator according to claim 3, wherein

[5] In any one of claims 3 and 4, wherein the shielding surface of the wire shielding box is located ahead of all the direct radiation directions assumed from the position of the a-ray source Static eliminator using the described wire.

[6] A pair of wire sources that are placed oppositely in the wire shielding box so as to sandwich the region where atmospheric ions are ionized and generated by the wire irradiation are adopted as the wire source. 5. A static eliminator using the wire according to claim 3 or 5.