JPH0773991A - Substrate carrying device - Google Patents

Abstract

PURPOSE:To prevent an insulation rupture due to releasing electro static charge when a glass substrate is carried on by providing an air blasing means which blows air higher in relative humidity than a carrying space upon the substrate just before it is parted from a substrate support section. CONSTITUTION:A carrying stage 11 is moved over a rail 15 along each ball screw 14 by the action of a drive means 13. A glass substrate 12 which has been mounted on the stage 11 at one end of the rail 15, is separated from the stage 11 by a vacuum chuck 16 at the other end of the rail 15 so as to be moved to the following process. Humidified air 101 which has a temperature of 23 deg.C, and a relative humidity of 80%, is blown upon the substrate 12 mounted on the stage 11, which is just before it is parted by the vacuum chuck 16 from the stage 11, out of an air blow chamber 10 which is connected to an air blow source 19 composed of a humidifier 17, and of an air blower 18, and also has a jet air stream forming diffuser. By this constitution, let almost of charged electric charge over the surface of the substrate 12 leak to an earthing side through a water molecular layer and the stage 11, so that the static electricity of the substrate 12 can instantly eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer device for removing static electricity generated in an article being transferred at a high speed, and is particularly effective in removing charges generated during the transfer of a large glass substrate in liquid crystal manufacturing. The present invention relates to a glass substrate transport device.

[0002]

2. Description of the Related Art In recent years, with the spread of notebook type personal computers or liquid crystal televisions, establishment of mass production technology of active matrix liquid crystal displays (AM-LCD) using TFTs (thin film transistors) is required.
The AM-LCD manufacturing process is a TFT process of depositing various thin films of amorphous silicon, insulators, conductors, etc. on a glass substrate and patterning them to form display electrodes and wiring for driving TFTs and liquid crystals, TFT substrate and color. Filter (C
F) A panel process of aligning a substrate and injecting liquid crystal into the overlapping gap, and a module process of connecting a drive circuit IC around the panel and mounting a backlight and the like.

In the meantime, in order to promote mass production of LCDs, measures against static electricity are much more important than in the case of LSI manufacturing having a similar manufacturing process, and are the biggest problems for securing the yield. That is, since the substrate material of the LCD is an insulating glass, electrostatic charging is much more likely to occur as compared with the silicon single crystal (semiconductor) which is the substrate material of the LSI, and adsorption of particles and dielectric breakdown of the deposited film. Because it is easy to invite.

However, LCD manufacturing has the following inherent problems as compared with LSI manufacturing. That is, first, since the LCD substrate is rectangular, large and heavy, batch processing is difficult and handling such as transportation is also difficult. Secondly, although the pattern processing accuracy such as the line width and the line interval is one digit less than that of the LSI, the processing uniformity in a wide area which is several times as large as that of the silicon substrate is required. Third
In addition, the concept of yield is different. That is, 1 MDRA
In a 10-inch class TFT-LCD corresponding to M, only 2 panels can be mounted on one glass substrate, and the yield can be three values of 0%, 50% and 100%. LS
In contrast, I can place hundreds of chips on a single silicon substrate.

Therefore, in order to establish a countermeasure against static electricity in the LCD manufacturing process, it is necessary to consider the solution of the above-mentioned inherent problems together. Various ionizers utilizing corona discharge have been conventionally known as a static elimination technology for a charged object based on this viewpoint. Recently, a method has also been developed in which air in the atmosphere surrounding a charged object is irradiated with soft X-rays to ionize and ionize the air to neutralize the charge. The principle of these static elimination techniques is a method in which air is ionized (whether corona or soft X-ray is generated) to neutralize the charge with air ions generated.

Of these techniques, FIG. 5 shows an outline of the liquid crystal ionizer disclosed in Japanese Patent Application No. 5-88172 filed by the inventors of the present application. This ionizer 1
00 is the charging (several kV) of the large glass substrate 102 (300 × 400 mm ² ) carried on the carrier device 101.
99% evenly over the entire surface in 3 seconds
The charge can be removed as described above. The features are shown below.

1) An AC voltage is applied to the discharge electrode 105 from the power unit transformer section 104 which can be controlled by the ion controller 103, and a DC voltage is applied to the counter electrode 10.
6 and simultaneously supplying dust-removed air from the blower unit 107, an air flow containing air ions blows out from the slit nozzle 108, and the air flow spreads so as to cover the entire surface of the large glass substrate 102. Therefore, there is no charge removal unevenness. The air velocity is 12 m / s at the nozzle outlet and 2 to 15 cm away from the nozzle outlet.
It is 3 m / s. The time required for the air flow from the nozzle outlet to reach the glass substrate is as short as one tenth of a second or less, and by irradiating the glass substrate with this air flow for only a few seconds, 90% or more of the electrification of several kV can be removed.

2) Further, by covering the metallic discharge electrode 105 arranged at the outlet of the slit nozzle 108 with quartz glass, it is possible to prevent the deterioration and dust generation of the electrode due to the discharge.

3) Further, a perforated stainless plate was provided as the counter electrode 106 on the downstream side of the discharge electrode. The ion stream blown out from the nozzle passes through this opening. At this time, in order to balance the positive and negative ion concentrations, +30 V to the counter electrode
By applying a DC voltage of +500 V, it is possible to absorb negative ions excessively contained in the airflow in the counter electrode.

Next, a brief description will be given on the recently developed static elimination technology using soft X-rays. This technique irradiates soft X-rays in the vicinity of a charged body to ionize air, and among the generated air ions, ions having a polarity opposite to that of the charge are absorbed by the charged body by the Cloning force, and the charge is removed. . The features are shown below.

1) The ionizer (corona discharge method), which is indispensable, does not require any air flow for transporting the generated ions from the discharge electrode to the charged object.

2) When the positive and negative ions generated like an ionizer are transported by an air flow, the positive and negative ions are bound and neutralized during the transportation until the ions reach the charged object, and the ion concentration is increased. Will decay. On the other hand, with soft X-rays, the air in the vicinity of the charged object is ionized directly, so that the high-concentration ions immediately after ionization reach the charged object without being attenuated and are used for static elimination. This is why the soft X-ray method has a significantly shorter static elimination time than the corona discharge method.

[0013]

By the way, since the above-mentioned liquid crystal ionizer conveys air ions in a stream of air, depending on the velocity of the stream of air, it disturbs the atmosphere around the charged object to be discharged. When it is used in a clean room where the cleanliness is not so high, dust deposited on the surrounding surface is thrown up and the surface of the crystal panel is polluted.

On the other hand, the static elimination method using soft X-rays has a characteristic that the soft X-rays are easily absorbed even by a thin air layer, but in order to completely prevent exposure of workers,
It is necessary to cover the entire irradiation space with something like a PVC plate having a thickness of 1 to 2 mm. The liquid crystal panel will be transported inside the closed space covered with the shielding plate, and in addition to the cleaning technology for the entire clean room, this cleaning technology for the closed space is newly required. Therefore, the cost advantage of the conventional type transfer method, in which the liquid crystal panel is transferred to the clean air in the clean room, is lost.

Furthermore, neither the ionizer nor the soft X-ray neutralization method can prevent the peeling charge and the dielectric breakdown of the element occurring at that moment. The reason will be described with reference to FIG. FIG. 6 is an outline of a large glass substrate transfer device 120. A glass substrate 122 mounted on a transfer belt 121 at one end is lifted by a suction chuck 124 of a transfer arm 123 at the other end. If the glass surface and the belt surface that are in contact with each other rub against each other even during transportation, the glass surface is charged positively and the belt surface is charged negatively. At this stage, the oppositely charged surfaces are in close contact with each other and apparently neutralized with each other. However, when both surfaces are separated by the vacuum chuck 124, the glass substrate 1 is instantaneously peeled off and charged.
An electric field due to positive charging appears in the thickness direction of 25, and the element formed on the glass substrate 125 is dielectrically broken down.

Further, in the method of neutralizing the charge by the air ions such as the ionizer and the soft X-ray, it takes 0.5 seconds to several seconds to remove the charge generated on the glass substrate by the peeling charge, and the element It does not help prevent dielectric breakdown. Also,
When it is attempted to neutralize the charge generated on the glass substrate using air ions, as shown in FIG.
When air ions formed by the neutralization device 131 of the charged article are adsorbed on the surface 130A of 0, the surface of the glass substrate is charged with a different polarity from the charge generated on the back surface 130B of the glass substrate due to peeling charging. . Since the electric field converges only inside the glass substrate, the charge appears to be neutralized, but this causes deterioration of the elements inside the substrate and uneven alignment of liquid crystal molecules.

Further, in both of the ionizer and the soft X-ray source, the range of charge removal per device is limited. Therefore, it is necessary to install a large number of static eliminators at all the places where the charging of the transport path may occur, and if a large number of static eliminators are operated at the same time, the breakdown and maintenance of each static eliminator will be complicated. Will inevitably occur.

Therefore, an object of the present invention is to solve such a problem of a conventional static eliminator used when a glass substrate is transported and to enable mass production of high quality LCDs.

[0019]

In order to solve the above problems, in a substrate transfer device constructed according to the present invention, a contact surface with a substrate to be neutralized is made of a conductive or semiconductive material and is grounded. A transport mechanism having a substrate supporting portion, and an air supply unit for blowing air having a relative humidity higher than that of the transport space onto the substrate at least immediately before the substrate is separated from the substrate supporting portion. I am trying.

Further, the air supply means usable in the apparatus of the present invention may be provided with an air volume adjusting means, a humidity adjusting means, a temperature adjusting means, or an air filtering means. Further, the air supply means may be provided with an air supply port for blowing a uniform air flow, a jet air flow or a curtain air flow onto the substrate. Alternatively, it is possible to provide a sensor for detecting the relative humidity in the vicinity of the substrate support and to control the temperature and humidity of the air supplied from the air supply means according to the signal from the sensor. .

Furthermore, a configuration is provided on the upstream side of the air supply means, such as a corona discharge electrode or a soft X-ray irradiation device, in which a charged substance neutralizing device for neutralizing the charged electric charge by air ions generated by ionizing the air. It is also possible to adopt.

[0022]

The device of the present invention utilizes the phenomenon found by the inventors of the present invention that the electrostatic charge on the surface of an object leaks to the ground side through the surface of the object. Furthermore, the humidity in the air is large. In this case, the electrostatic charge on the surface of the object leaks directly into the air, that is, the attenuation of the electrostatic charge due to so-called “air leakage” is used.

The main reason why the surface charge is greatly attenuated as the relative humidity increases is that the amount of water adsorbed on the glass surface increases and the surface resistance value decreases. That is,
Since the O atom of SiO ₂ which is the main component of glass has a lone pair of electrons, it easily forms a hydrogen bond with H of a water molecule, so that a water molecule layer is easily formed on the glass surface, and the water molecule layer forms a substrate support. Leakage can occur on the ground side via the via. In the manufacturing process of the TFT-LCD, a thin film electrode and an insulating film are formed on a glass substrate, and since a plurality of layers of electrodes are protected by the insulating film, the insulating film forming process occupies the process. The proportion is high. However, the insulating film is SiN, SiO ₂ , Al ₂ O ₃ , Ta ₂ O _5, etc.,
Considering that O and N atoms have a lone electron pair like the O atom of SiO _2, the device of the present invention is effective for such a glass substrate with an insulating film. Further, when the relative humidity is 80% or more, the attenuation of surface charges due to air leakage also effectively acts on the charge removal of the glass substrate surface.

That is, according to the present invention, an air flow having a relative humidity higher than that of the ambient atmosphere discharged from the air supply means is blown onto the substrate, so that the vicinity of the surface of the substrate touched by the air flow has a relative humidity higher than that of the ambient atmosphere. Enclosed in an atmosphere of humidity, most of the charge on the substrate surface leaks to the ground side via the water molecule layer attached to the substrate surface and the substrate support, and part of the charge on the substrate surface is released into the air. It leaks directly. As a result, the electrostatic charges charged on the surface of the substrate are eliminated in a short time, so that the peeling charging phenomenon does not occur even when the substrate is separated from the support table, and the dielectric breakdown of the element formed on the substrate is effectively performed. Can be prevented.

By providing the air supply means with the air volume adjusting means, the humidity adjusting means, the temperature adjusting means, or the air filtering means, it becomes possible to adjust the air volume, the humidity, and the temperature according to the transport environment, or the ULPA filter. By using the air that has been removed by dusting, it is possible to prevent the substrate from being contaminated by fine particles in the air. Further, by devising the air supply port, blown air can be blown onto the substrate as a uniform air flow, a jet air flow, or a curtain air flow according to the transport environment. For example, when air is blown as a uniform air stream with a low wind speed and a large flow rate during normal transportation, and when the surrounding atmosphere is highly clean and there is no risk of contamination of the panel surface due to dust flying up, a high wind speed and a small flow rate will be used. A desired static elimination effect can be obtained by blowing air as a curtain air flow or a jet air flow, or by blowing a uniform flow parallel to the substrate when both sides of the substrate are charged. Further, the sensor detects the relative humidity in the vicinity of the base, and feedback control of the air volume, the humidity, and the temperature according to the signal can provide a more stable static elimination environment.

Furthermore, the apparatus of the present invention is a charging device for neutralizing the charging charge by air ions generated by ionizing air such as a corona discharge electrode or a soft X-ray irradiating device, which is installed on the upstream side of the air supply means. It can also be used in combination with a substance neutralizer. By this combination, static electricity of the new one charged on the substrate by the charged object neutralizer is eliminated as a pretreatment, and peeling charge generated when the substrate is separated from the base by air with high relative humidity is mainly eliminated. , A more complete static elimination effect can be obtained.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of a substrate transfer apparatus constructed according to the present invention will be described below with reference to the accompanying drawings. First, in order to facilitate the understanding of the present invention, paying attention to the humidity of the ambient atmosphere and the dirt on the glass surface, what are the leakage characteristics of the charged charges of the glass substrate for LCD placed in contact with the ground conductor? The experiment which investigated whether it had an influence is demonstrated.

1. Experimental Method (1) Glass Substrate All glass substrates used in the experiment were non-alkali glass (Fusion 7059) manufactured by Corning. Its relative permittivity is 5.84 [-] and its component is Si.
O ₂ : 49%, BaO: 25%, B ₂ O ₃ : 15 and Al ₂ O
_The ratio was ₃ : 10% and the other was 1%.

(2) Measuring method As shown in FIG. 8, 22.5 ± 0.5 ° C., 42 ± 1% R
Corning's alkali-free glass (Fu) used as a glass substrate for liquid crystal in a constant temperature and humidity chamber of H (cleanliness is US Federal Standard 0.5 μm particle size standard Class 1).
(Sion 7059, 50 × 50 × 1.1 ^t mm) was placed on a grounded metal flat plate (the ITO film in the figure corresponds to the metal flat plate). The surface of this glass substrate was corona-charged to the positive polarity. Then, the temperature and humidity conditions in the constant temperature and humidity chamber were changed variously, and the decay characteristics of the charged charge density on the glass substrate were investigated. The surface potential of the glass substrate was measured by a surface potential meter (Model 244) using a probe of the zero method (MONROE Model 1017E). The surface potential was measured at 25 locations on the surface of the glass substrate that were evenly distributed. Regarding the center point of the substrate, the temporal change of the surface potential during the experiment was recorded. The temperature and humidity during measurement are mirror surface cooling type dew point meter (GENERAL EASTERN Hygr
o-M2). The measured value of the surface potential is the following formula (1)
Was converted to surface charge density by.

V _s = V _b −V = σ _d / ε _r ε _o (1) where σ: equivalent surface charge density [Coulomb / m ² ] V _s : potential difference of glass substrate thickness [ V] V _b : Surface potential measurement value [V] V: Potential difference between probe glass surfaces [= 0 V] ε _r : Relative permittivity of glass [= 5.84] ε _o : Permittivity of air [= 8.85 × 10 ¹² F / m] d: Thickness of glass substrate [= 1.1 × 10 ^-3 m]

(3) Measurement of surface resistivity The surface resistivity of the glass substrate was measured under various temperature and humidity conditions. High resistance meter (HP's 4339A) ring electrode part (HP's 16008B, main electrode 50 mm)
φ, guard electrode 60mmφ) is installed in the constant temperature and humidity chamber,
The surface resistivity of the glass substrate (80 × 80 × 1.1 ^t mm) was measured under various humidity conditions. First, temperature and humidity conditions 2
The glass substrate was placed in a bath at 3 ° C. and 40% RH. The transition time from this temperature / humidity condition to a predetermined temperature / humidity condition is 20 minutes. One hour after the atmosphere in the tank reached a predetermined temperature and humidity condition, the glass substrate was loaded into the ring electrode portion and the measurement was performed. All handling of the glass substrate was performed in the tank with the atmosphere inside and outside the tank isolated. The applied voltage was 500 V for 60 seconds. The temperature and humidity during the measurement were recorded using a mirror-cooled dew point meter.

(4) Cleaning of Glass Substrate No matter how clean the glass substrate surface is, only by exposing it to the atmosphere of a clean room, organic impurities derived from hydrocarbon gas in the air adhere to the surface. Usually, this impurity can be completely removed by a method called UV / O ₃ cleaning (Japanese battery DUV-25 × 4A) in which ultraviolet rays and ozone gas are combined. A "cleaned" glass substrate immediately after cleaning, which is a combination of ultrasonic cleaning for 60 minutes with ultrapure water (17 to 18 MΩ · cm) and UV / O ₃ cleaning, and after cleaning 1
For a month, the equipment installed in the clean room was referred to as "unwashed" glass substrate and used for the experiment.

(5) Evaluation of the Contamination State on the Surface of the Glass Substrate To evaluate how much the surface of the glass substrate is contaminated with organic substances, a contact angle meter (Kyowa Interface Science CA-S) is used.
150 type) and X-ray photoelectron spectroscopy (abbreviation XPS: FIS)
ONS Instrument INSPECT
R)). Ultrapure water was used as the droplets.

2. Experimental Results (1) Effect of Humidity on Surface Charge Density Attenuation We investigated the surface charge decay characteristics of corona-charged “unwashed” glass substrates under various humidity conditions.

In FIG. 9, 22.5 ± 0.5 ° C., 42 ± 1%
The average value and standard deviation at each measurement point when the surface charge density at 25 points on the substrate surface in RH is repeatedly measured 5 times are shown. As shown in FIG. 9A, the central portion of the glass substrate was slightly charged as compared with the peripheral portion. The average value of all measurement points of the average surface charge density is 4.3 x
It is 10 ^-5 Coulomb / m ² . Further, as shown in FIG. 9B, the standard deviation differs depending on the measurement point, and is ± 1 × 10.
^-6 to ± 5 × 10 ^-6 Coulomb / m ² .

The temperature inside the constant temperature and humidity chamber is 22.5 ° C. (constant)
FIG. 10 shows the decay rate (= σ / σ _o ) of the surface charge density after exposure to a predetermined relative humidity for 1 hour. The horizontal axis represents the distance of the measurement point from the center point of the glass substrate. The higher the relative humidity was, and the closer to the periphery of the substrate, the greater the decrease in charge density. At 40% RH, the decay rate after 1 hour was σ / σ _o = 0.97, and conversely, a portion where the charge density was slightly increased was also observed.

Next, the relative humidity is 60% RH or 70%
FIG. 11 shows the result of measurement of the attenuation rate when only the temperature is changed, that is, the absolute humidity is changed while keeping the RH (each constant). As shown in the figure, if the relative humidity is the same, the attenuation rate does not change even if the absolute humidity changes.

FIG. 12 shows the calculation of the time decay of the surface charge density with respect to various relative humidity, based on the time constant obtained by measuring the decay time of the surface charge density at the center of the glass substrate. Humidity in the clean room of the manufacturing process is usually 40%
Before and after RH, it can be seen that in this case the charged charge does not readily decay even when the "unwashed" glass substrate is in contact with the ground conductor.

(2) Surface Contamination and Leakage Characteristics of Charged Electric Charge "Cleaning" Glass Substrate (Ultrasonic Cleaning + UV / O ₃ Cleaning)
Then, the “unwashed” glass substrate (which was left in a clean room for one month after the washing) was positively charged with corona, and the surface charge density after 5 minutes was measured. As a result, the surface charge density of the “unwashed” glass substrate was measured. For 4.3 × 10 ⁻⁵ Coulomb / m ² ,
The "washed" glass substrate had a size of 4.7 x 10 ^-8 Coulomb / m ² or less.

FIG. 13 shows that at various relative humidities,
Surface resistance of “cleaned” and “uncleaned” glass substrates (ρ
It is the result of measuring _s [Ω / □]). The surface resistivity of the “unwashed” glass substrate is 10 ² to 1 of the “washed” glass substrate.
0 ⁵ times larger, both both surface resistivity decreased as the humidity increases.

Further, as a result of measuring the contact angles of the "cleaned" and "uncleaned" glass substrate surfaces, "cleaned" was 4
The degree of "unwashed" was 70 degrees (standard deviation was 2 degrees). As described above, the contact angle of “uncleaned” is obviously larger than that of “cleaned”, and it can be seen that surface contamination occurs when the “cleaned” substrate is exposed to the clean room atmosphere for a long time.

Furthermore, XPS (X-ray photoelectron sp
As a result of analyzing the elemental composition ratio (%) on the surface of the glass substrate by ectroscopy), in the case of the “cleaned” glass substrate, C: 4.8,
O: 62.9 (66), Si: 23.8 (25), A
l: 5.7 (6), Ba: 2.8 (3), B: undetected, C: 15.9, O: for the "unwashed" glass substrate.
55.7 (66), Si: 21.3 (25), Al:
4.2 (5), Ba: 2.9 (3), B: not detected. The numbers in parentheses indicate the elemental composition ratio when carbon is not included. Under the XPS measurement conditions this time, a region from the surface to a depth of about 100 Å is analyzed. In this analysis, the elemental composition ratios of O, Si, Al, and Ba, which are the composition elements of the original glass substrate, are the elemental composition ratios obtained from the glass substrate manufacturer's specification values,
That is, O: 67, Si: 19, Al: 5, Ba:
5, almost coincided with B: 5. In addition to these elements, C
Was detected, it is considered that C is derived from the hydrocarbon component in the clean room air. C on the glass substrate surface
Regarding the amount of adhered elements, "unwashed" was about 3 times that of "washed".

3. Discussion From the above experimental data, the effects of humidity and surface contamination on the leakage characteristics of the charged charges of the LCD glass substrate were investigated.

(1) Effect of Humidity The glass substrate for LCD contains the same chemical composition as the alumina / silica adsorbent. Since the amount of water adsorbed by the adsorbent depends on the relative humidity, it is considered that the amount of adsorbed water on the surface of the glass substrate also increased and the surface resistivity decreased as the relative humidity increased. When the surface resistivity decreases, the charges on the surface of the glass substrate easily move on the surface and leak to the ground ITO plate.

(2) Effect of Surface Contamination The surface resistivity decreased as the relative humidity increased, whether "washed" or "unwashed". However, the value of the surface resistivity of "unwashed" was about 10 ² to 10 ⁵ times that of "washed". Further, the reduction rate of the surface charge density of the “cleaned” glass substrate was significantly higher than that of the “uncleaned” glass substrate. These results show the contact angle measurement and XP
From the surface analysis of S, it is explained as follows. UV / O
_{3 Even if} organic contaminants are once removed from the glass substrate surface by washing, exposing the glass substrate surface to a clean room atmosphere for a long time again pollutes the surface with hydrocarbon components derived from the atmosphere. This contamination increases the surface resistivity and makes it difficult for surface charged charges to leak.

Regarding surface contamination by hydrocarbon components derived from the clean room atmosphere, according to Takayuki Hagi, "Surface Organic Matter (Applied Physics Vol. 61 No. 11 (1992) page 1168)", the amount of organic substances on the surface of the silicon wafer Has been reported to increase over time due to storage in air, and to approximately the same level as before UV cleaning in about 3 weeks. However, in the time of 30 minutes or less, the level of 1/10 or less before the cleaning is maintained. Therefore, in air
It is considered that the increase of the surface organic matter can be almost ignored when handled for about 5 minutes. When organic substances adhere to the surface of the glass substrate, there is a problem that the adhesion of the film deteriorates when forming the thin film electrode and the insulating film in the manufacturing process of the TFT-LCD. Therefore, the next process should be performed as soon as possible after cleaning. Need to go to.

By the way, the device of the present invention utilizes the phenomenon that the electrostatic charge on the surface of an object leaks to the ground side through the surface of the object.
6 ((1986.10.) 123) "and" Proceedings of the Japan Society of Electrostatics '87 ((1987.10) 145) ", when the humidity in the air is high, the electrostatic charge on the surface is directly Leakage into the interior (so-called "air leakage") has been reported. Further, according to the experiments conducted by the present inventors, it has been found that the attenuation due to air leakage is not negligible as compared to the leakage attenuation through the surface when the relative humidity is 80% or more.

Next, the operation of the substrate transfer device constructed according to the present invention will be described in detail based on the findings described above. FIG. 14 shows the results of adding the charge leakage characteristics (solid line) of the “unwashed” glass and the charge leakage characteristics (broken line) of the “washed” glass shown in FIG.
The calculated value was obtained as follows.

First, assuming that the capacitance per unit area of the glass substrate is C _a [Farad / m ² ], the charging leakage path resistance R [Ohm], and the time after the start of leakage is t [sec], the initial charge amount σ ₀ The relationship between [Coulomb / m ² ] and the charge amount σ [Coulomb / m ² ] after the lapse of time t [seconds] is expressed by the following equation (2). σ = σ ₀ exp [−t / RC _a ] (2)

In this equation (2), if C _a is assumed to be constant, the ratio of the respective decay times at which the charges of the “unwashed” glass and the “washed” glass decay to a fixed rate, for example 1/10, , And the surface resistance ratios of these glasses (obtained from FIG. 13) match.

From FIG. 14, the time until the charge was attenuated to 1/10 was obtained for the "unwashed" and "washed" glasses and summarized in Table 1. The term "cleaned" glass as used herein means ultrasonic cleaning for 60 minutes with ultrapure water (17 to 18 MΩ · cm), followed by UV / O ₃ cleaning for 10 minutes on each side (Japanese battery DUV-25 × 4A). Refers to. Further, "unwashed" glass means a state of being left in a clean room for one month after washing. As shown in the table, with "washed" glass, when the relative humidity is 70% or more, it is only 1/100.
In the order of seconds, the attenuation is 1/10.

[0052]

[Table 1]

Table 2 shows how the 1/10 attenuation characteristic of the glass substrate left in the clean room after cleaning changes with time at 60% relative humidity. The decay time of 0.2 seconds immediately after cleaning only increases to 1.1 seconds because the organic contamination of the surface has not progressed so much even after being left for 2 hours.

[0054]

[Table 2]

As already described, the TFT process is a cycle of cleaning → film formation → lithography → cleaning, and considering that it does not often take one hour from one cleaning to the next cleaning, In the manufacturing process, by increasing the relative humidity of the atmosphere near the glass substrate and grounding the substrate, the charge can be almost completely leaked and removed in a short time of 1/100 to 1/10 seconds.

It is considered that the main reason why the surface charge is significantly attenuated when the relative humidity is increased is that the adsorption amount of water on the glass surface is increased and the surface resistance value is decreased. Since the O atom of SiO ₂ which is the main component of glass has a lone electron pair,
Hydrogen bond with H of water molecule. Further, in the manufacturing process of the TFT-LCD, a thin film electrode and an insulating film are formed on a glass substrate, and since a plurality of layers of electrodes are protected by the insulating film, the insulating film forming process occupies the process. The proportion is high. The insulating film is made of SiN, SiO ₂ , Al ₂ O ₃ , Ta ₂ O ₅
In consideration of the fact that O and N atoms have a lone electron pair like the O atom of SiO ₂ , the device of the present invention is effective for such a glass substrate with an insulating film. Furthermore, when the relative humidity is 80% or more, attenuation of surface charges due to air leakage can be expected, so that more effective charge removal can be performed.

As described above, according to the device of the present invention,
The air flow discharged from the air supply chamber and having a relative humidity higher than that of the ambient atmosphere can eliminate static electricity from a charged glass having a wide surface area having a width of the air supply chamber or a side length slightly smaller than the width. In particular, when both the front and back surfaces of the glass substrate are charged, it is more effective to project the airflow so as to trace the front and back surfaces of the substrate in parallel with the substrate. The vicinity of the glass surface touched by the air flow is surrounded by an atmosphere with a relative humidity higher than the surrounding atmosphere, and most of the charged charges on the glass surface pass through the water molecule layer attached to the glass surface and the glass substrate support (stage). Then, it leaks to the ground side, and a part of the charged charges on the glass surface leaks directly into the air.

Next, some embodiments in which the present invention is applied to an actual device will be described. FIG. 1 shows an embodiment of a glass substrate transporting device of the present invention installed in a clean room of class 1000 at a temperature of 24 ° C. and a relative humidity of 40%. On the aluminum stage 11,
A glass substrate 12 having TFT elements formed on its surface is mounted. The stage 11 moves the rail 15 along the ball screw 14 by the action of the driving device 13. The glass substrate 12 mounted on the stage 11 at one end of the rail 15 is separated from the stage 11 by the vacuum chuck 16 at the other end of the rail 15 and moves to the next step. Humidifier 17
A humidified air 101 having a temperature of 23 ° C. and a relative humidity of 80% is supplied from an air supply chamber 10 having an outlet for forming a jet airflow, which is connected to an air supply source 19 composed of a blower 18 and
It is sprayed onto the glass substrate 12 mounted on the stage 11 just before leaving the stage 11 by the vacuum chuck 16. Until the glass substrate 12 is separated from the stage 11, the vicinity of the glass surface contacted by the air flow is surrounded by an atmosphere having a relative humidity of 70% or more, and most of the charged charges on the glass surface are water molecule layers attached to the glass surface. And the aluminum substrate 11 which is the glass substrate support, and leaks to the ground side, and a part of the charged charges on the glass surface leaks directly into the air.
The electricity is instantly removed in the order of 100 seconds.

As a comparative example, when the humidified air 101 from the air supply source 19 is stopped and the glass substrate transporting apparatus of the present invention is operated, the glass substrate 12 is vacuum chucked.
The moment the glass substrate 12 is separated from the stage 11 by
Was charged to several kV, and the TFT element was destroyed.

FIG. 2 shows another embodiment of the glass substrate transporting apparatus of the present invention installed in a clean room of class 1000 having a temperature of 24 ° C. and a relative humidity of 40%. TFT is mounted on the robot arm 21 made of aluminum.
A glass substrate 22 having an element formed on its surface is mounted. The robot arm 21 moves to the entrance of the cassette case 24 by the action of the driving device 23, stores the glass substrate 22 mounted on the arm in the case 24, and then the arm 21 separates from the glass substrate 22. From the air supply chamber 20 having an outlet for forming a curtain air flow connected to an air supply source 29 including a humidifier 27 and a blower 28, a temperature of 2
Humidified air 201 at 3 ° C. and 80% relative humidity is blown into the cassette case 24 immediately before being separated from the robot arm 21 and stored in the cassette case 24. Until the glass substrate 22 is separated from the robot arm 21, the vicinity of the glass surface that is contacted by the air flow is surrounded by an atmosphere having a relative humidity of 70% or more, and most of the charged electric charges on the glass surface are water molecules attached to the glass surface. It leaks to the ground side through the layer and the robot arm 21 which is a glass substrate support, and a part of the charged charges on the glass surface leaks directly into the air and is instantly discharged.

As a comparative example, when the humidified air 201 from the air supply source 29 is stopped and the glass substrate transporting apparatus of the present invention is operated, the glass substrate 22 is moved to the robot arm 2.
At the moment when it was separated from 1, the glass substrate 22 was charged with several kV, and the TFT element was destroyed.

FIG. 3 shows another embodiment of the glass substrate transporting apparatus of the present invention installed in a clean room of class 1000 at a temperature of 24 ° C. and a relative humidity of 40%. The difference from the first embodiment is that the air is provided on the rail 35, which is the movement path of the stage 31, and has a blowout port for forming a uniform flow, which is connected to an air supply source 39 so as to cover the entire movement path. This is the point at which the chamber 30 is arranged. Further, a vinyl curtain 301 hangs around the blowout port of the air supply chamber 30 to prevent the uniform flow from the blowout port from being dissipated. The air supply source 39 includes a cooling coil 391, a heating coil 392, a humidifier 393, a blower 394, and an air filter (high-performance filter) 395. The glass substrate 32 is separated from the stage 31 by the vacuum chuck 36 at one end of the rail 35,
Moving to the next step, this transfer operation is performed in a uniform flow blown out from the air supply chamber 30. A relative humidity detection sensor 396 is provided in the vicinity of the glass substrate 32 immediately before leaving the stage 31, and the relative humidity of the ambient atmosphere of the glass substrate 32 and the stage 31 detected by this sensor is from 70% to 75%. The temperature and humidity of the air 301 sent out from the air supply source 39 are feedback-controlled so as to fall within the range.

In the first embodiment shown in FIG. 1 and the second embodiment shown in FIG. 2, since the shape of the air flow blown out from the air supply chamber is a jet air flow or a curtain air flow, the amount of air blown out is uniform. Although it is possible to reduce the amount, it is necessary to set the blowing direction so as to effectively hit the glass substrate surface and the substrate support. On the other hand, FIG.
In the third embodiment shown in (1), since a uniform flow that covers the entire glass substrate transport operation is used, it is not difficult to control the blowing direction like a jet or curtain airflow, but a certain amount of blowing air is required.

In FIG. 4, an ionizer 42 for ionizing air by corona discharge is provided with a discharge electrode 40 and a counter electrode 41 on the upstream side of the air supply chamber 10 of the embodiment shown in FIG. 1, that is, on the upstream side in the conveying direction. There is shown a substrate transfer device including. In this manner, by providing another static eliminator on the upstream side of the air feeding chamber 10 in the transport direction, the pretreatment static eliminator cleanly eliminates the charge on the surface of the glass substrate, and then the apparatus of the present invention is used to remove the above-mentioned glass. It is also possible to remove the charge before the substrate is separated from the transfer base to prevent peeling charge. In the embodiment shown in FIG. 4, an ionizer using a corona discharge electrode is installed as a pretreatment static eliminator, but instead of this,
It is also possible within the scope of the invention to employ an air ionizer such as soft X-ray irradiation.

The structure of the air supply source in the present invention may be any structure as long as it can achieve the purpose of discharging a clean air flow having a relative humidity higher than that of the surrounding atmosphere from the air supply chamber, such as humidification, cooling and cleaning of air. It is possible to use various combinations of different devices. For example, it is also possible to combine devices that perform heating for the purpose of preventing supercooling or aiming at the effect of cooling the blown heated air when the ambient air is involved and increasing the relative humidity. In addition, for example, a combination of a humidifier and a blower, a combination of an air filter and a humidifier and a blower, a combination of a cooling coil and a blower, a combination of an air filter and a cooling coil and a blower, a cooling coil and a heating coil and a blower Combination, air filter / cooling coil / heating coil / blower combination, cooling coil / humidifier / blower combination, air filter / cooling coil / humidifier / blower combination, heating coil / humidifier / blower combination, A combination of an air filter, a heating coil, a humidifier and a blower, a combination of a cooling coil, a heating coil, a humidifier and a blower, a combination of an air filter, a cooling coil, a heating coil, a humidifier and a blower, etc. It is considered within the scope of the technical idea of the present invention described in 1.

Furthermore, according to the present invention, a sensor for detecting the humidity or temperature around the glass substrate to which air having a high relative humidity is blown is provided, and each of the above output devices is controlled by a signal from the sensor. By performing feedback control, it is possible to always build an optimal static elimination environment, prevent dielectric breakdown of the substrate, and improve the product yield.

[0067]

As described above, according to the apparatus of the present invention, the contact surface on which the glass substrate is placed is conductive or semi-conductive, and the glass substrate is conveyed on the grounded substrate support. At least immediately before the glass substrate leaves the substrate support, by blowing an air flow with a relative humidity higher than that of the transfer space, most of the charged charges on the surface of the glass substrate adhere to the glass surface. Since it is possible to leak a part of the charged charges on the glass surface directly into the air through the layer and the glass substrate support base to the ground side, it is possible to instantly eliminate the charge on the glass substrate. As a result, it is possible to prevent dielectric breakdown due to peeling charges of the elements formed on the substrate, so that the yield of products can be dramatically improved.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an embodiment in which a substrate transfer device configured according to the present invention is applied to a glass substrate transfer stage.

FIG. 2 is a schematic explanatory view showing an embodiment in which a substrate transfer device configured according to the present invention is applied to a glass substrate transfer arm.

FIG. 3 is a schematic explanatory view showing an embodiment in which the substrate transfer device configured according to the present invention is applied to an air supply means having a uniform flow type outlet.

FIG. 4 is a schematic explanatory view showing an embodiment in which a substrate transfer device configured according to the present invention is combined with a pretreatment static eliminator.

FIG. 5 is a schematic explanatory view showing main components of a conventional slit nozzle type corona discharge type ionizer.

FIG. 6 is an explanatory diagram showing a configuration of a conventional large-sized glass substrate carrying device.

FIG. 7 is a schematic explanatory diagram showing how a charge neutralizing device removes electricity from a glass substrate whose back surface is positively charged.

FIG. 8 is a block diagram showing a device configuration for measuring a state of a charged electric charge of an LCD glass substrate.

FIG. 9 is a graph showing distributions of measured average values and standard deviations of surface charge densities of glass substrates for LCDs.

FIG. 10 is a graph showing a decay rate of surface charge density after exposing a glass substrate for LCD under a predetermined relative humidity for 1 hour without changing temperature.

FIG. 11 is a graph showing the decay rate of the surface charge density when the temperature environment of the glass substrate for LCD is changed under a predetermined relative humidity.

FIG. 12 is a graph showing the time decay of the surface charge density of LCD glass substrates in various relative humidity environments.

[Figure 13] "Cleaning" in various relative humidity environments
3 is a graph showing the surface resistivity of an “unwashed” glass substrate.

[Fig. 14] "Cleaning" in various relative humidity environments
3 is a graph showing the time decay of surface charge density of an “unwashed” glass substrate.

[Explanation of symbols]

 10 Air Supply Chamber 11 Transfer Stage 12 Glass Substrate 13 Drive Device 14 Ball Screw 15 Transfer Rail 16 Vacuum Chuck 17 Humidifier 18 Blower 19 Air Supply Source

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[Procedure amendment]

[Submission date] November 12, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0030

[Correction method] Change

[Correction content]

[0030]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction content]

(3) Measurement of surface resistivity The surface resistivity of the glass substrate was measured under various temperature and humidity conditions. High resistance meter (HP's 4339A) ring electrode section (HP
Company 16008B, main electrode 50mmφ, guard electrode 60
(mmφ) is installed in a constant temperature and humidity chamber, and a glass substrate (80 x
The surface resistivity of 80 × 1.1 ^t mm) was measured under various humidity conditions. First, the glass substrate was placed in a tank of temperature and humidity conditions of 23 ° C. and 40% RH. The transition time from this temperature / humidity condition to a predetermined temperature / humidity condition is 20 minutes.
One hour after the atmosphere in the tank reached a predetermined temperature and humidity condition, the glass substrate was loaded into the ring electrode portion and the measurement was performed. All handling of the glass substrate was performed in the tank with the atmosphere inside and outside the tank isolated. Ring electrode
The voltage applied to the part was 500 V for 60 seconds. The temperature and humidity during the measurement were recorded using a mirror-cooled dew point meter.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0049

[Correction method] Change

[Correction content]

First, assuming that the capacitance per unit area of the glass substrate is C _a [ farad ], the leakage path resistance R of charging is [ohm], and the time after the start of leakage is t [second], the initial charge amount σ ₀ [Coulomb / m ² ] and the charge amount σ [Coulomb / m ² ] after the lapse of time t [seconds] is expressed by the following equation (2).

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0052

[Correction method] Change

[Correction content]

[0052]

[Table 1]

[Procedure Amendment 5]

[Document name to be corrected] Drawing

[Correction target item name] Figure 8

[Correction method] Change

[Correction content]

[Figure 8]

[Procedure correction 6]

[Document name to be corrected] Drawing

[Correction target item name] Figure 9

[Correction method] Change

[Correction content]

[Figure 9]

Claims (10)

[Claims] 1. A transfer mechanism having a substrate supporting portion whose contact surface with a substrate to be neutralized is made of a conductive or semi-conductive material and is grounded; and at least immediately before the substrate is separated from the substrate supporting portion. And an air supply unit for spraying air having a relative humidity higher than that of the transfer space. 2. The substrate transfer apparatus according to claim 1, wherein the air supply unit further includes an air volume adjusting unit. 3. The substrate transfer apparatus according to claim 1, wherein the air supply unit further includes a humidity control unit. 4. The substrate transfer apparatus according to claim 1, wherein the air supply unit further includes a temperature adjusting unit. 5. The air supply means further comprises an air filtering means.
The board | substrate conveyance apparatus in any one of. 6. The air supply unit further comprises an air supply port for forming a uniform air flow, a jet air flow or a curtain air flow with respect to the substrate.
6. The substrate transfer device according to any one of 3, 4, and 5. 7. A sensor for detecting relative humidity in the vicinity of the substrate support, and control means for controlling the temperature and humidity of the air supplied from the air supply means in response to a signal from the sensor. 7. The substrate transfer apparatus according to claim 1, further comprising: 8. A charged object neutralizing device for neutralizing charged charges by air ions generated by ionizing air is provided upstream of the air supply means.
The substrate transfer device according to any one of 3, 4, 5, 6 and 7. 9. The substrate transfer device according to claim 8, wherein the charged substance neutralizing device includes a corona discharge electrode. 10. The substrate transfer device according to claim 8, wherein the charged substance neutralizing device includes a soft X-ray irradiation device.