JP2749202B2 - Charged object neutralization structure, clean room, transport device, living room, plant growing room, positive and negative charge generation method, charged object neutralization method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates primarily to a method for generating positive and negative charges in a gas, and further relates to a method for neutralizing a charged object, a neutralizing structure and a neutralizing structure using the method. Transport equipment, wet benches, clean rooms, etc.

BACKGROUND ART For example, in LSI and liquid crystal manufacturing processes, charging of a silicon wafer and a liquid crystal substrate has become a major problem, and establishment of antistatic technology is urgently required. This device generates gas molecule ions or electrons from such a background,
This has been developed to neutralize the charge of the charged object. With this device, it is possible to neutralize the surface charges of all the positively or negatively charged objects in a short time, not to mention the silicon wafer and the liquid crystal substrate, and to prevent various kinds of obstacles due to static electricity. . In the following, as an example, the actual state of charging of a wafer and the troubles caused by the charging will be described, and then the problems of the current antistatic technology will be described, and the background to the present invention will be described.

(Charging of Wafer) A wafer is usually handled with insulating fluororesin or quartz from the viewpoint of prevention of impurity contamination and chemical resistance. For this reason, the wafer is easily charged to a very high potential. As an actual measurement example, FIG. 16 shows a table of the measurement results of the wafer charging potential in the photolithography process. As can be seen from this result, it is understood that the wafer is charged at the KV level.

(Obstacles Due to Wafer Charging) Wafer charging gives a serious obstacle to the manufacturing process.
The main ones are adhesion of suspended particles due to electrostatic force, device damage due to electrostatic discharge, and electron trajectory obstacles that are problematic during electron beam exposure. Hereinafter, this obstacle will be briefly described.

-Attachment of particles by electrostatic force Five factors such as gravity, inertial force, electrostatic force, Brownian diffusion, and thermophoretic force are involved in the attachment of floating particles to a wafer, and the magnitude of the effect varies depending on the particle size. 0.1μm
In the following particles, the latter three factors are dominant, and the influence of electrostatic force is extremely large.

FIG. 1 shows the result of the actual measurement of the relationship between the wafer potential and the suspended particle deposition rate. In this case, the particle diameter is 0.5 μm or more. It is clear that the particle adhesion speed is increasing due to the effect of electrostatic force.

Next, FIG. 2 shows theoretical calculation results in order to investigate the effect of electrostatic force when the particles are further reduced. The calculated comparison particle diameters are three types of 2 μm, 0.5 μm and 0.1 μm, and the wafer potential is 1000 V. Here, the floating range of the adhered particles was calculated by considering only the gravity and the electrostatic force as the adhesive force. The attachment range of the 2 μm particles is very narrow, indicating that they hardly adhere to the wafer.

However, as the particle diameters become smaller, 0.5 μm and 0.1 μm, the range of attachment to the wafer is rapidly increasing.
This indicates that when the particle size of the charged particles is reduced, the influence of the electrostatic force on the adhesion becomes extremely large.
As described above, in an environment in which the controlled particle size is becoming smaller and smaller in a clean room, it is of course not only to prevent the generation of particles, but also at the same time, it is very important to take measures against static electricity in order to minimize the adhesion.

-Device destruction by electrification Device destruction by electrification is becoming a more and more serious problem with thinner insulating films and finer circuit patterns. Since device destruction depends on voltage and current, there is a need to consider not only reduction of the charged potential but also reduction of electrostatic energy in preventing device breakdown.

The dominant voltage due to device breakdown is mainly dielectric breakdown of an oxide insulating film or the like. In this case, as the oxide film thickness becomes smaller, the breakdown voltage naturally becomes lower. Generally, the dielectric breakdown strength of an oxide film is about 10 MV / cm.

On the other hand, the current is dominant is a wiring disconnection fault. This is due to the melting of the circuit by Joule heat. The device destruction due to the wafer charging is remarkably generated at a low charging potential, more than the adhesion of floating particles due to electrostatic force. It is very important to prevent static electricity during wafer transfer as well as to prevent static electricity during wafer processing in the apparatus.

(Conventional wafer antistatic technology) As a conventional wafer antistatic technology, there is a method as described below.

Ions are generated by a corona discharge method, and the ions neutralize the charge on the charged wafer.

The charge on the wafer is neutralized by handling the wafer with a grounded conductive material (metal or conductive resin).

However, these neutralization methods have some disadvantages and cannot be used as a countermeasure for neutralizing charged wafers in the future unless they are improved.

First, the corona discharge method has four main disadvantages.

1) Generation of fine particles from the discharge electrode 2) Generation of residual potential due to bias of ion polarity 3) Generation of induced voltage by high voltage discharge electrode 4) Generation of ozone 1) The electrode material itself generates dust due to abrasion such as the ion spattering action, and the dust generated when impurities in the air solidify due to a chemical reaction or the like and adhere to and accumulate on the electrode surface during discharge. The former dust generation was solved by protecting the discharge electrodes with quartz glass developed recently. However, the latter problem has not been solved.

The problem 2) is a problem that occurs because the polarity of the voltage applied to the discharge electrode alternates between positive and negative. When the polarity of the discharge electrode is positive, positive ions are supplied to the charge removal object, and when the discharge electrode is negative, negative ions or electrons are supplied to the charge removal object. Even after the static elimination, a residual potential is generated due to the supply of the charges having such a biased polarity. Since the residual potential becomes higher as the ion generator is closer to the object to be neutralized, it is necessary to take a certain distance to carry the ions by air flow in order to reduce this obstacle.

In recent years, a method for reducing the residual potential by applying a DC potential to the vicinity of the ion generation unit has been developed. However, the method cannot be used in the vicinity of the static elimination object because the induced voltage described later becomes a problem. The need to keep the distance in this way is a major cause of slowing the static elimination speed. It is impossible in principle to completely solve this problem by the corona discharge method.

The generation of the induced voltage in 3) becomes a problem when the discharge electrode is close to the charge removing object. The only way to prevent this obstacle is to increase the distance between the discharge unit and the object. As in the case of the residual potential in 2), the charge removal time is delayed by the distance.

4) In ozone generation, oxygen atom radicals formed by dissociation of oxygen molecules are the main sources. Such a dissociation phenomenon is promoted by collision with a low energy electron of 10 eV or less and photon absorption. In the corona discharge method, this phenomenon is observed in the corona region, and as a result, ozone is generated. The ozone concentration varies depending on the structure of the discharge electrode, applied voltage and air flow.
reach m. Since the ozone has a very strong oxidizing power, it not only promotes the formation of a natural oxide film on the wafer surface, but also promotes the deterioration of the surrounding polymer material.

Next, the wafer charging can be almost completely prevented, but the risk of serious contamination such as impurity contamination increases. Impurities mixed into the fluororesin or the like for imparting conductivity, as well as metal, contaminate the wafer due to contact abrasion with the wafer and become a major cause of deterioration of electrical characteristics. This problem is more serious than static electricity, and in order to prevent it, the current situation is that wafers are handled with insulating resin materials.

The present invention relates to a device for simultaneously generating positive and negative charges capable of neutralizing the charge of a charged object in a short time under any atmosphere, and to eliminate static electricity without all the above-mentioned disadvantages. The present invention relates to a method for neutralizing a charged object capable of completely preventing generation thereof, a neutralized structure, and various devices using the same.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the relationship between wafer potential and adhered particles. FIG. 2 is a graph showing the particle size dependence of particle adhesion due to electrostatic force. FIG. 3 is a side view showing an example of the X-ray unit used in the present invention. FIG. 4 is a conceptual diagram of the apparatus used for the neutralization experiment. FIG. 5 is a graph showing the target voltage dependence of the static elimination performance. FIG. 6 is a graph showing the target current dependence of the static elimination performance. FIG. 7 is a graph showing the atmospheric pressure dependence of the static elimination performance. FIG. 8 is a perspective view of the clean room according to the present embodiment. FIG. 9 is a perspective view of the wet bench according to the present embodiment. FIG. 10 is a conceptual diagram illustrating a transfer system for a wafer and a liquid crystal substrate according to the present embodiment. FIG. 11 is a perspective view of the wet bench according to the present embodiment. FIG. 12 is a perspective view of the spin dryer according to the present embodiment. FIG. 13 is a perspective view illustrating the inside of the closed transport system and the manufacturing apparatus according to the present embodiment. FIG. 14 is a conceptual diagram of a living room showing an embodiment relating to a living room of a building. FIG. 15 is a conceptual diagram of a plant cultivation room showing an example relating to the plant cultivation room. FIG. 16 is a table showing the measurement results of the wafer charging potential in the photolithography process. FIG.
It is a conceptual diagram which shows the static elimination method at the time of glass substrate conveyance. Fig. 18
Is a graph showing changes in the surface potential of the glass substrate.
FIG. 19 is a conceptual diagram showing a static elimination method when pulling up a glass substrate. FIG. 20 is a graph showing a change in the surface potential of the glass substrate.

DISCLOSURE OF THE INVENTION In the charge neutralizing structure of the present invention, a soft X-ray unit is disposed at an appropriate position where soft X-rays having a wavelength of 1 to several hundreds of mm can be directly irradiated toward ambient air around a charged object. It is characterized by having.

In the clean room of the present invention, in a clean room in which clean air flows down from the ceiling toward the floor, the soft X-rays having a wavelength of 1 to several hundreds of mm can be directly irradiated substantially parallel to the ceiling surface. A soft X-ray unit is provided.

The transfer device according to the present invention, in a transfer device having a transfer chamber for transferring an object to be processed to a process device, is capable of directly irradiating an ambient gas in the transfer chamber with soft X-rays having a wavelength of 1 to several hundreds of degrees. And an X-ray unit is provided.

The living room of the present invention has air introducing means for supplying air from the outside to the inside of the living room. In a living room of a building or a vehicle, soft X-rays having a wavelength of 1 to several hundreds of mm are directly applied to the air. A means for generating positive ions and negative ions and / or electrons in the air by irradiation is provided.

The plant cultivation room of the present invention directly irradiates the air with soft X-rays having a wavelength of 1 to several hundreds of mm in a plant cultivation room having an air introduction means for supplying air from outside to the inside of the plant cultivation room. Thereby, a means for generating positive ions and negative ions and / or electrons in the air is provided.

The method for generating positive and negative charges using soft X-rays according to the present invention is as follows.
By irradiating soft X-rays having a wavelength of ~ 100Å to air under pressure, atmospheric pressure or reduced pressure, positive ions and negative ions and / or electrons are generated in the air. .

The charge neutralization method of the present invention provides a soft X having a wavelength of 1 to several hundreds of degrees.
By directly irradiating the ambient air around the charged object with the line, the ambient air is ionized to generate positive ions, negative ions and / or electrons, and the generated positive ions cause a negative charge to be generated. It is characterized in that positive charges are neutralized by ions and / or electrons.

As an X-ray unit for generating electromagnetic waves in the soft X-ray region, for example, an X-ray unit as shown in FIG. 3 is preferably used. That is, this X-ray unit
A target 35 is used in which a thin target film 33 made of a material that receives electrons and emits X-rays is formed on an X-ray transparent base 34, and a target 35 is provided between the electron source (filament 31) and the target 35. It is preferable to use an electrode provided with a grid electrode 32 (for example, JP-A-2-297850). Since the X-ray unit 30 is of a so-called transmission type in which the X-rays 37 are emitted from the side opposite to the electron source because the target film 33 is thin, the X-ray unit 30 can be miniaturized. It has the advantage of being able to. Also, a grid electrode is provided between the electron source and the target 35.
Since 32 is provided, the target current can be controlled.

Electromagnetic waves in the soft X-ray region are generated by certain substances (for example, W:
It can be easily obtained by irradiating tungsten) with an electron beam having a predetermined energy.

Although the wavelength of the generated X-rays varies depending on the target to which the electrons are irradiated, it is preferable to use soft X-rays having a wavelength in the range of 1 Å to several hundred Å.
In particular, soft X-rays of 1 to several tens of angstroms are preferred.

Further, as an electromagnetic wave in the soft X-ray region, an electron beam is generated by setting a target voltage (acceleration voltage) to 4 kV or more.
It is preferable to use an electromagnetic wave generated by accelerating to kV or more and colliding with a target. Further, it is preferable to use an electromagnetic wave generated by setting the target current to 60 μA or more.

The present invention is applicable even when the gas irradiated with the electromagnetic wave in the soft X-ray region (atmosphere gas of the charged object in the case of the charge neutralization structure) is, for example, nitrogen gas or argon gas in addition to air. It is. This gas need not be an airflow gas. For example, in the case of neutralization of a charged object, one of the features of the present invention is that a sufficient neutralizing action of the charged object can be performed without using a gas stream. Of course, when the X-ray unit irradiates electromagnetic waves in the X-ray region at a position distant from the charged object, it is preferable that the atmospheric gas be an airflow gas toward the charged object. In a pure nitrogen gas atmosphere having an impurity concentration of several ppb or less, a particularly remarkable effect can be obtained.

Further, the pressure of the atmospheric air is preferably in the range of 1000 Torr to 1 Torr, and more preferably in the range of 1000 Torr to 20 Torr.

The gas ion generator according to the present invention is suitably applied, for example, when the purpose is to neutralize a charged object. Also,
It is also applied to cases other than neutralization. For the purpose of neutralization, for example, handling a clean room, a wafer / liquid crystal substrate, a transfer device, a wet processing device, an ion implantation device, a plasma device, an ion etching device, an electron beam device, a film manufacturing device, and other charged objects. It can be suitably applied to devices and the like. On the other hand, for various purposes, for example, buildings, vehicles (eg, cars, airplanes, trains, etc.)
The present invention is also applied to a living room, a plant cultivation room, and the like.

It should be noted that the product of the present invention has a concentration of 10 ⁴
~ 10 ₈ ion pairs / cm ³ · sec, preferably 10 ⁵ ~
It has been found that it is more preferable to be 10 ⁸ ion pairs / cm ³ · sec. At such concentrations, the lifetime of the ions is 10-
It was also found to be 1000 seconds. Therefore, the ion concentration
An ion is generated at an ion concentration of 10 ³ to 10 ⁴ (ion pairs / cm ³ ), and the distance L between the position of the airflow gas irradiated with the electromagnetic wave in the soft X-ray region and the charged object is given by the following relationship. If it is set, the charged object can be sufficiently neutralized.

L / v <10 to 1000 L: Distance between irradiation position and charged object (m) v: Velocity of airflow gas (m / sec) In the present invention, for example, a transport device, an ion implanter Needless to say, the present invention can be suitably applied to a plasma reaction device, an ion etching device, an electron beam device, a film manufacturing device, and other devices requiring neutralization of charged objects.

Function In the present invention, positive ions and negative ions or electrons are generated by utilizing ionization of gas molecules and atoms by irradiation of electromagnetic waves in the soft X-ray region.

According to this ionization method, all the problems of the corona discharge ionization method and the ultraviolet irradiation ionization method described above are solved.

In the corona discharge method, dust is generated at the tip of the discharge electrode due to a sputtering effect at the time of discharge, but the present invention can generate positive and negative charges without dust generation.

Also, in the corona discharge method, positive and negative charges are supplied to the periphery in synchronization with the polarity applied to the discharge electrode, so that positive and negative space potentials are generated. Residual potential is generated. Then, in order to reduce the residual potential, the ion generator had to be kept away from the charge removing object. On the other hand, in the present invention, since the same number of positive and negative charges are always generated around the neutralization object, there is no deviation of the space potential after the neutralization, and no residual potential is generated in the neutralization object. Therefore, the X-ray unit can be brought close to the charge removing object to a desired position, and high charge removal performance can be achieved.

Although a high voltage is applied inside the X-ray unit, no electric field is generated outside because the casing is electrostatically shielded. Therefore, induced voltage from the discharge electrode, which is a problem in the corona discharge method, does not occur at all. Therefore, there is no problem in bringing the X-ray unit close to the charge removing object to a desired position.

A major feature of the present invention is that even when a gas containing oxygen such as air is used, the gas can be ionized without generating ozone. Therefore, problems of the conventional method such as oxidation of the semiconductor wafer and deterioration of the polymer material can be solved.

For ozone generation, the energy of photons is several hundred eV to several
Since it is very high in the order of keV, gas molecules and atoms can be ionized efficiently, and as a result, the number of neutral oxygen atom radicals, which are thought to most contribute to ozone generation, decreases, and the generation of ozone is suppressed. You.

The gas molecules and atoms absorb electromagnetic waves in the soft X-ray region and lead to direct ionization. The ionization energy of gas molecules and atoms is at most about ten to twenty and several eV, which is several tens to several hundreds of the photon energy in the soft X-ray region. Therefore, a single photon can ionize a plurality of atomic molecules or generate ions of two or more valences.

By irradiating soft X-rays to a gas atmosphere around the charged object, high-concentration ions and electrons are generated, and charge of the charged object is neutralized. In this case, substantially the same static elimination performance can be obtained with any gas regardless of the type of gas around the charged object. Also, unlike neutralization by corona discharge ionization, gas can be ionized near the charged object, and the generated ions and electrons can be efficiently used for neutralization, resulting in a dramatic increase in static elimination performance. Will be higher. Further, the static elimination performance is improved 100 to 1000 times as compared with the case where the ionized gas is transported by a pipe or the like.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described. In addition, the present invention
It is needless to say that the present invention is not limited to the following embodiments, and design changes, numerical value changes, detours, and the like that can be easily made by those skilled in the art are also included in the scope of the present invention.

(Example 1) A neutralization experiment of a charged wafer according to the present invention will be described with reference to obtained data.

The experimental apparatus is shown in FIG. Made of SUS chamber 41, as a soft X-ray from the outside can be irradiated, the entrance 42 is provided on the side wall, further 50mm diameter at its entrance 42, the length 1 ₂ port
43 is installed. Port 43 length 1 ₂
By setting the length such that the charged object (wafer) 44 cannot be seen from the opening at the tip of 43 (that is, the wafer cannot be seen from the opening at the tip), direct irradiation of X-rays on the wafer 44 can be prevented. . In this example, the port 43 has a double cylinder structure, and the outer cylinder 45 is slidable. Therefore, if the size of the wafer 44 changes, the wafer 44 and the entrance
If ask distances 1 ₁ and 42 are changed freely length 1 ₂ of the port 43 by sliding the outer cylinder 45 is also changed, can be from the opening of the port distal to the wafer 44 is not expected .

In addition, a filter 46 for isolating the inside and the outside of the chamber 41 can be attached to the front end opening of the port 43. Atmospheric gas (for example, N _{2 ′} Air, Ar) is introduced from a gas inlet 47 provided at one end (right side in the drawing) of the chamber 41. In this example, the three-way valve 48 is connected to the gas inlet 47.
a is provided so that the introduced gas can be switched. A gas outlet 49 is provided at the other end (left side in the drawing) of the chamber 41, and a three-way valve 48b is also provided at the gas outlet 49, and one of the three-way valves 48b is connected to the ozone meter 50. . The ozone concentration is monitored by the ozone meter 50 on the exhaust side.

In order to carry out an evaluation experiment, an electrode 51 is provided near the wafer 44 so that a predetermined initial potential on the wafer 44 can be applied by a DC power supply. A surface potentiometer is connected to the wafer 44. The static elimination performance was evaluated by monitoring the decay time of the surface potential of the wafer 44 with a surface voltmeter.

The specifications of the X-ray unit 52 used in the experiment are as follows.

Target material: W Target voltage: 2 to 9.7 kV Target current: 0 to 180 μA Using the apparatus shown in FIG. 4, experiments were performed on the following items.

1) Dependency of target voltage and current on static elimination performance First, the dependence of target voltage on current was examined under the following experimental conditions.

Wafer capacitance: 10 pF Atmospheric gas: air, pure nitrogen (nitrogen with an impurity concentration of several ppb or less) Target voltage: 4 to 9.7 kV Target current: 120 μA constant 1 ₁ : 11 cm 1 ₂ : 9 cm Initial wafer potential ± 3 kV The ambient gas was irradiated with soft X-rays generated under the above conditions, and the time until the wafer potential became ± 0.3 kV was measured.

 The result is shown in FIG.

Next, the dependence of the target current was examined under the following experimental conditions.

Wafer capacitance: 10 pF Atmospheric gas: air, pure nitrogen (nitrogen with an impurity concentration of several ppb or less) Target voltage: 8 kV Target current: changes in the range of 30 to 180 μA 1 ₁ : 11 cm 1 ₂ : 9 cm The evaluation was performed by irradiating the atmosphere gas with soft X-rays generated under the above conditions while setting the initial wafer potential to ± 3 kV, and measuring the time until the wafer potential became ± 0.3 kV.

 FIG. 6 shows the result.

As shown in FIGS. 5 and 6, it can be seen that the charge elimination time of the charged object greatly depends on the target voltage and the target current. In particular, the former greatly depends. It can be seen that when the target voltage is 4 kV or less, there is almost no charge removal ability, and the gas ionization rate is extremely low. In this case, if the target voltage is 6 to 7 kV or more, static elimination of the charged object can be performed in a very short time.

Although the current dependency is smaller than the voltage dependency, it is preferable that the target current be 60 μA or more in order to perform neutralization in a short time.

By the way, in both FIG. 5 and FIG. 6, the static elimination tendency is slightly different between air and pure nitrogen (nitrogen having an impurity concentration of ppb or less). In air, the static elimination performance is the same for both positive and negative,
In pure nitrogen, the charge removal performance of positive charges is high. This difference lies in the difference in the abundance of the negative ion sources. That is, in air, oxygen, CO ₂ , NO _X , SO _{X and the} like combine with electrons ionized from gas molecules to generate relatively stable negative ions. Thus, it is the positive and negative ions that have approximately equal mobilities that neutralize the charged charge.

On the other hand, in pure nitrogen, such a negative ion source hardly exists (below the ppb level), so many of the electrons ionized from gas molecules directly contribute to the neutralization of positive charges without forming negative ions. I do. The mobility of the electrons in the electric field is several orders of magnitude higher than that of the ions. Therefore, the generated electrons can reach the charged object in a very short time, neutralization by recombination with positive ions and extinction by diffusion are suppressed, and contribute to the neutralization of the charged object efficiently. As a result,
The charge removal speed of the positive charge is faster.

2) Dependence of static elimination performance on irradiation window material Soft X-rays are very easily absorbed by substances, unlike hard X-rays. Therefore, when soft X-rays are radiated inside through a filter window in static elimination in a certain special atmosphere, the static elimination performance may decrease.

This was confirmed by conducting an experiment under the following conditions. Without a filter, the static elimination performance was compared between a polyimide film that is relatively stable to radiation and high in transmittance and a synthetic quartz with a thickness of 2 mm.

Wafer electrostatic container: 10 pF Atmosphere gas: Air wafer potential: ± 300 V → ± 30 V Target voltage: 8kV target _{current: 120μA 1 1: 11cm 1 2} : 9cm port of the tip opening: polyimide film placed unfiltered 0.12 mm, 2 mm synthetic Quartz installation The measurement results were as follows.

In the case of a filter made of a polyimide film, the static elimination performance was relatively good, and 82% of the static elimination performance was obtained compared to the case without the filter. On the other hand, in the synthetic quartz window, the static elimination effect is completely lost, and it can be seen that almost 100% of soft X-rays have been absorbed.

From this result, when irradiating soft X-rays through a filter in such a special atmosphere (for example, a closed system in which atmosphere gas is hermetically sealed), polyimide which is relatively transparent to radiation is used. It is preferable to use a filter made of such a material.

3) Atmospheric gas pressure dependence of static elimination performance Next, the atmospheric pressure dependence of static elimination performance was examined.
The experimental conditions are as follows.

Wafer capacitance: 10 pF Atmosphere gas: Air Target voltage: 8kV target _{current: 120μA 1 1: 11cm 1 2} : 9cm Note that neutralization performance, the initial wafer potential and ± 300 V, the soft X-ray generated under the above conditions The evaluation was performed by irradiating the atmosphere gas and measuring the time until the wafer potential became ± 30 V.

 FIG. 7 shows the results.

It can be seen that the static elimination performance obviously changes depending on the atmospheric pressure. At about 100torr, the performance has gradually improved, and static elimination has been completed up to twice as fast.
However, since then it's getting slower and about 20torr
At about atmospheric pressure, 10 times slower at 1 torr. From this result, it is possible to remove electricity under a reduced pressure of about 1 torr, but below that, the electricity removal time is very long and not very effective.

4) Ozone concentration in static elimination atmosphere An experiment was conducted on ozone generation, which often poses a problem in static elimination in air.

 The experimental conditions were as follows.

Atmosphere gas: Air Target voltage: 9.7KV target current: 190μA 1 _2: measured amount of generated ozone at an ozone meter 50 in 9cm Figure 4.
As shown in FIG. 4, the ozone concentration was measured with an ozone meter 50 by pulling the gas in the chamber 41 at a suction rate of 21 / min. Note that the measurement was performed 30 minutes after the irradiation of the electromagnetic wave in the X-ray region.

The results are shown below. For comparison, the background (BG) concentration and the amount of ozone in the case of ultraviolet irradiation (UV irradiation) are also shown.

Example: 8 to 10 ppb BG: 8 to 10 ppb UV irradiation: 20 ppm (after 30 minutes) As a result of the measurement, there is no increase in the ozone concentration even at the time of soft X-ray irradiation, whereby the generated concentration is below the ppb level. This has been proven.

On the other hand, in the case of ultraviolet irradiation performed for comparison, the ozone concentration increased to 20 ppm (about 2,000 times the BG value).

As described above, the electrostatic neutralization performance by soft X-rays is very excellent. A high-concentration ion pair can be generated without generating ozone, and as a result, the charge of the charged object can be neutralized in a short time. In addition, since soft X-rays are rapidly attenuated, it is very easy to take measures to block such soft X-rays from irradiating the human body.

It is effective to provide a shielding plate (preferably, a shielding plate capable of totally reflecting X-rays) in the radiating portion in order to further condense the radiated light of the soft X-ray lamp and make it closer to parallel light.

Embodiment 2 FIG. 8 shows an embodiment in which an X-ray unit 81 is installed in a clean room 80.

In this example, the soft X is almost parallel to the ceiling surface of the clean room 80.
An X-ray unit 81 is attached to a ceiling 82 so as to emit a ray. The reason why the soft X-rays are irradiated substantially parallel to the ceiling surface is to prevent X-rays from being irradiated on a person or a wafer (or a liquid crystal substrate or the like) 85 in the clean room 80.

A filter 83 for removing dust is provided on the ceiling 82, and a so-called downflow airflow A from the ceiling 82 to the floor 84 is generated. Since the X-rays radiated from the X-ray unit 81 are radiated to the upstream portion of the airflow, ions and electrons generated by the X-ray irradiation are
The wafer is carried to the downstream wafer 85 by the air flow,
Neutralize.

In this example, the X-ray unit 81 is mounted on the ceiling 82, but the position is not limited to the ceiling 82 as long as the position in the clean room 80 can be prevented from irradiating a person or the wafer 85.

Third Embodiment FIG. 9 shows an example in which an X-ray unit 19 is provided on a wet bench 90.

On the other hand, FIG. 10 shows an example in which an X-ray unit 102 is provided in an open transfer device for a wafer or a liquid crystal substrate 101. In the transfer device 103 shown in FIG. 10, the X-ray unit 102 is brought as close as possible to the wafer 101,
A shielding plate 104 for shielding X-rays is provided to avoid exposure to the human body.

Fourth Embodiment FIG. 11 shows an example of application to static elimination in a wet process.
Reference numeral 12 denotes an example of application to static elimination in spin dryer drying.

On the other hand, FIG. 13 shows an example in which the present invention is applied to a closed transport system. In this example, the nitrogen gas (from the lower side of the transfer chamber, the impurity concentration
Floating transfer of the wafer is performed by injecting air having a nitrogen concentration of less than ppb or less or a water concentration of several ppb or less. The wafer is loaded from the transfer chamber into the process device via the load lock chamber (load lock chamber). The X-ray units are provided on the side of the transfer chamber in the transfer direction and on the side of the load lock chamber. The transfer chamber may be formed of a material transparent to soft X-rays, for example, polyimide, and the soft X-ray may be irradiated to the atmosphere gas in the transfer chamber through the polyimide.

However, in order to prevent oxidation of the wafer surface, the transfer chamber is made of stainless steel having a passivation film formed by thermal oxidation on the surface, and nitrogen gas with an impurity concentration of several ppb or less is used as a transfer gas. Attempts have been made to use them. It is more preferable to use a stainless steel on which a passivation film having a Cr / Fe (atomic ratio) of 1 or more on the surface is formed, since water release from the surface can be prevented.

Further, a port as shown in FIG. 4 is formed on the side of the transfer chamber, and soft X-rays are irradiated through the opening of the port to an atmosphere gas in the transfer chamber (transfer nitrogen gas becomes an atmosphere gas). The carrier gas in the transfer chamber can be irradiated with soft X-rays. Incidentally, the port length (1 ₂ in FIG. 4) is not expected to be a wafer transfer chamber from the distal end opening of the port (i.e., the wafer is not visible from the distal end opening) is as dimensions. This dimension is determined by the diameter of the wafer, the distance between the X-ray irradiation port and the wafer (see FIG. 4).
1 ₁ ) The structure can change the port length because it changes depending on the conditions.

Since the transport device of this example is a closed system, polyimide is formed at the tip opening of the port.

Embodiment 5 FIG. 14 shows an embodiment relating to a living room of a building. That is,
FIG. 14 shows the living rooms of the building.

In this example, an air introduction pipe is provided on the ceiling of the living room, and air sent from outside through this air supply pipe is
It is introduced into the interior of the living room through the supply port of the air supply pipe.

An X-ray unit is provided in the air supply pipe, and an opening is provided in the air supply pipe. Soft X-rays from the X-ray unit are converted into air flowing through the air supply pipe through the opening. Irradiated. Needless to say, without providing the opening, the air supply pipe may be made of a material transparent to soft X-rays such as polyimide.

When irradiated with soft X-rays, positive ions and negative ions and / or electrons are generated in the air, and positive ions and negative ions and / or
Alternatively, the air containing the electrons is brought into the interior of the living room by the air flow.

A living room having a size of about 5 tsubo was prepared, an X-ray unit was arranged in the configuration shown in FIG. 14, and tests were performed with and without soft X-ray irradiation (Example) and without (Comparative Example).

 The number of panelists was set to 20, and evaluation was made based on physical experience.

When irradiating with X-rays,
Fifteen people answered that the room was refreshing. Five persons answered that there was no difference between the case where X-ray irradiation was performed and the case where X-ray irradiation was not performed.

A Geiger counter was provided on the table of FIG. 14, and the amount of X-ray exposure was measured. The number of counters was the same between when X-rays were irradiated and when X-rays were not irradiated.

Embodiment 6 FIG. 15 shows an embodiment relating to a plant growing room. That is, the figure
In Fig. 15, a cultivation room for plants (flowers, vegetables, etc.) is shown.

Irradiation with soft X-rays was performed for one week throughout the day and night with the configuration shown in FIG. One week later, when the color of the leaves of the flower was observed, it showed a brighter green color than without soft X-ray irradiation.

It goes without saying that the X-ray unit may be provided as shown in FIG.

(Example 7) In this example, static electricity generated during transport and cleaning of a glass substrate in a liquid crystal manufacturing apparatus was neutralized by using the present invention and a conventional static eliminator, and the results were compared.

FIG. 17 shows the state of static elimination performed in the glass substrate transfer system. The glass substrate is conveyed from the left by a rubber ring, and once positioned on a circular stage, is stored in a carrier on the right. In the present example, static elimination was performed at the alignment section, and the static elimination characteristics were measured by changing the irradiation angle to the substrate as shown in the figure. In addition, the measurement was performed on a blower type ionizer using a corona discharge method as a conventional static eliminator under the same conditions. FIG. 18 shows the measurement results.

In FIG. 18, the vertical axis represents the charging potential, and the horizontal axis represents the elapsed time. The dotted line indicates soft X-rays, and the solid line indicates static elimination characteristics by the ionizer. The charge potential without static elimination always showed a value exceeding the limit of the surface electrometer -3.3 kV. When static elimination was performed by soft X-rays in this example, the peak potential was -0.4 kV at the maximum after static elimination was started, and the static elimination time up to 0 V was at most about 2 seconds. It was also found that no change in the static elimination performance due to the irradiation angle was observed. On the other hand, when the conventional ionizer was used, it was found that the static elimination performance greatly depends on the irradiation angle, and that the static elimination performance was significantly inferior to this embodiment. For example, the peak potential can reach -3 kV and the time took at least 5 seconds or more.

Next, the state of static elimination at the time of cleaning the glass substrate is shown in FIG. When the substrate was pulled out of the tank after overflow cleaning with ultrapure water, the potential of the substrate reached −3.3 kV or more. FIG. 20 shows the measurement results of the static elimination characteristics when static elimination was performed simultaneously with the lifting. By the soft X-ray irradiation, the maximum charging potential is suppressed to 0.1 kV or less, and the time until the voltage reaches 0 V is about 1 second, which indicates that charging can be effectively prevented. on the other hand,
When the ionizer was used, the voltage reached 1.7 KV at the maximum, and the charge elimination time also took 4 to 5 seconds.

As described above, according to the present invention, even if it is a glass substrate, the charged charge can be completely eliminated in a short time, and the charge can be prevented.

INDUSTRIAL APPLICABILITY The use of the ion generator by soft X-ray irradiation according to the present invention makes it possible to generate positive and negative ions without generating dust.

Also, when neutralizing a charged object, it is possible to neutralize the charge of the charged object in a short time under any atmosphere, and by applying this device to the charged part, the generation of static electricity can be completely prevented. Can be prevented.

This leads to the prevention of defects due to static electricity and the reduction of product reliability in the production of semiconductors and liquid crystals, and increases the production yield. In particular, the use of a pure fluorine resin-based wafer carrier has been a problem due to the problem of static electricity, but the application of the static elimination method has completely eliminated such concerns.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Jin Inaba 3-24-8 Nakamachi, Machida-shi, Tokyo (72) Inventor Tomoyuki Ikedo 581-3-504, Hatsusei-cho, Hamamatsu-shi, Shizuoka (56) References 1-274396 (JP, A) JP-A-2-68899 (JP, A)

Claims (20)

(57) [Claims] (1) The temperature of ambient air around a charged object is 1 °.
A neutralizing structure for a charged object, wherein a soft X-ray unit is disposed at an appropriate position where soft X-rays having a wavelength of about several hundreds of mm can be directly irradiated. 2. The soft X-ray unit according to claim 1, wherein said atmosphere air is air current flowing toward a charged object, and said soft X-ray unit is adapted to directly irradiate electromagnetic waves in a soft X-ray region toward air upstream of said charged object. The neutralizing structure for a charged object according to claim 1, wherein is provided. 3. In a clean room in which clean air is flowing down from the ceiling to the floor, soft X-rays having a wavelength of 1 to several hundreds of mm can be directly irradiated substantially parallel to the ceiling surface. A clean room in which an X-ray unit is provided. 4. A transfer apparatus having a transfer chamber for transferring an object to be processed to a process apparatus, wherein an atmosphere gas in the transfer chamber can be directly irradiated with soft X-rays having a wavelength of 1 to several hundreds of degrees. A transport device comprising an X-ray unit. 5. A soft X-ray having a wavelength of 1 to several hundreds of millimeters, wherein a load lock chamber is interposed between the transfer chamber and the process apparatus so that the atmosphere gas in the load lock chamber can be directly irradiated with soft X-rays having a wavelength of 1 to several hundreds of degrees. The transport device according to claim 4, wherein a line unit is provided. 6. The transfer chamber is provided with a soft X having a wavelength of 1 to several hundreds of degrees.
The transport device according to claim 4, wherein the transport device is formed of a material that is transparent to the line. 7. The transfer device according to claim 6, wherein polyimide is used as a material transparent to the soft X-rays having a wavelength of 1 to several hundreds of degrees. 8. The transfer chamber is made of stainless steel having a thermal oxidation passivation film having a Cr / Fe (atomic ratio) of 1 or more on its surface, and 1 to several hundreds of mm in an appropriate position in the transfer chamber. An inlet for directly irradiating soft X-rays of a wavelength is provided, and soft X-rays of 1 to several hundreds of wavelengths are directly irradiated to the atmosphere gas in the transfer chamber through the inlet. The transport device according to claim 4 or 5, wherein 9. A port portion protruding to the outside is provided at the entrance, and the length of the port portion is set so that an object to be processed in the transfer chamber cannot be seen from the front end opening of the port portion. 9. The conveying apparatus according to claim 8, wherein a filter made of a material transparent to soft X-rays having a wavelength of 1 to several hundreds of mm is provided at an opening at the end of the port. 10. The transfer device according to claim 4, wherein the transfer device is a transfer device that floats and transfers the transferred object by ejecting gas from below the transfer chamber. Transport device. 11. The transfer apparatus according to claim 10, wherein the gas ejected from below the transfer chamber is nitrogen gas having an impurity concentration of several ppb or less or air having a moisture concentration of several ppb or less. 12. In a living room of a building or a vehicle having an air introducing means for supplying air from outside to the inside of the living room, the air is directly irradiated with soft X-rays having a wavelength of 1 to several hundreds of degrees. A living room, further comprising means for generating positive ions and negative ions and / or electrons in the air. 13. A plant growing room having an air introducing means for supplying air from outside to the inside of the plant growing room,
A plant cultivation room provided with means for generating positive ions and negative ions and / or electrons in the air by directly irradiating the air with soft X-rays having a wavelength of 1 to several hundreds of square meters. 14. Soft X-rays having a wavelength of 1 to several hundreds of degrees are pressurized,
A positive / negative charge generation method using soft X-ray irradiation, characterized by directly irradiating air under atmospheric pressure or reduced pressure to generate positive ions and negative ions and / or electrons in the air. 15. An atmosphere air around a charged object is directly irradiated with soft X-rays having a wavelength of 1 to several hundreds of degrees to ionize the atmosphere air to convert positive ions and negative ions and / or electrons. A method for neutralizing a charged object, comprising: generating, neutralizing a negative charge with the generated positive ions, and neutralizing a positive charge with the negative ions and / or electrons. 16. The neutralization of a charged object according to claim 14, wherein the soft X-rays having a wavelength of 1 to several hundreds of degrees are electromagnetic waves generated by setting a target voltage to 4 KV or more. Method. 17. The soft X-ray having a wavelength of 1 to several hundreds of degrees is an electromagnetic wave generated by setting a target current to 60 μA or more. Method for neutralizing charged objects. 18. The air according to claim 14, wherein the atmospheric air has a water concentration of several ppb or less.
Item 9. A method for neutralizing a charged object according to the item. 19. The pressure of the atmospheric air is 1000 Torr to 1T.
19. The method for neutralizing a charged object according to any one of claims 14 to 18, wherein the method is orr. 20. The pressure of the ambient air is 1000 Torr to 20 Torr.
20. The method for neutralizing a charged object according to claim 19, wherein the method is Torr.