JP5708055B2 - Substrate processing method - Google Patents

Description

  The present invention supports, for example, a substrate such as a glass substrate for a liquid crystal display panel, a semiconductor wafer, a mask substrate for manufacturing a semiconductor (hereinafter simply referred to as “substrate”) on a substrate support member such as a plate or a chuck, The substrate processing apparatus that performs predetermined processing such as heating, cooling, resist coating, HMDS processing, cleaning, and development on the substrate, and particularly effectively prevents peeling charging when the substrate is peeled off from the substrate support member after the processing is completed. Related to improvements.

  For example, in the manufacturing process of a liquid crystal display panel, a glass substrate that has been subjected to a predetermined surface treatment is supplied, and various treatments such as application of resist solution and color filter ink, drying, cooling, and washing are performed. A process is provided. In these processing steps, a glass substrate is adsorbed to a vacuum adsorption table device and transferred while applying a resist solution, etc. by a coater, or adsorbed and held on a hot plate to dry the glass substrate, or adsorbed and held on a cool plate. Or let it cool.

  The vacuum suction table device, the hot plate, the cool plate, etc. all include a suction holding plate for sucking and holding the glass substrate by air suction. This suction holding plate forms a smooth substrate holding surface (board surface) on the upper surface of the aluminum plate body, and an insulating film is formed on the surface of the substrate holding surface by alumite treatment based on Al2O3 or the like. The provided gas passage is opened at the substrate holding surface.

  Then, the glass substrate is placed on the substrate holding surface, and the glass substrate is placed on the substrate holding surface by exhausting air sandwiched between the glass substrate and the substrate holding surface from the air intake holes opened in the substrate holding surface through the gas passage. Adsorb and hold. Conversely, the exhaust from the gas passage is stopped to release the glass substrate, and the glass substrate is peeled from the substrate holding surface by pushing up the glass substrate from the substrate holding surface with the eject pin protruding from the plate body.

  Since the glass substrate is easily charged, static electricity is removed before the start of processing, but it is easily charged during handling up to the suction holding plate and during suction to the suction holding plate. If the glass substrate held on the suction holding plate is charged with static electricity as described above, the coating solution is repelled and uneven coating occurs, or dust adheres to the glass substrate and the product yield rate is good. There is a problem of lowering. In addition, when the glass substrate is charged, when ejecting the eject pin from the plate body and peeling the glass substrate from the substrate holding surface, the glass substrate is attracted to the substrate surface by electrostatic force and bent into a bow shape. A robot hand may enter and break the glass substrate, or a thin glass substrate for a liquid crystal display panel may break due to a large warp. Further, when the glass substrate is peeled off from the substrate holding surface, a spark may run due to discharge between the charged glass substrate and the substrate holding surface, the glass substrate may be damaged, or the glass substrate for a liquid crystal display element In some cases, the TFT (thin film transistor) formed on the substrate was destroyed.

  For this reason, the conventional substrate processing apparatus has a structure in which a gas passage opening in the board surface is provided inside, and air is sucked and exhausted from the board surface through the gas passage and ionized gas is blown out to the board surface through the gas passage. Is known. (Refer to Patent Documents 1 and 2) In this substrate processing apparatus, since the ionized gas is blown out from the board surface, the ionized gas can be sent directly to the close contact surface between the glass substrate and the board surface to efficiently remove static electricity. Since the glass substrate can be lifted from the board surface by the flow of the ionized gas, the glass substrate can be peeled off from the board surface reliably and promptly.

JP-A-7-193118 (FIG. 1) Japanese Patent Application Laid-Open No. 11-233599 (FIG. 2)

  However, in such a charge removal method, since the effect due to recombination of ions in the piping from the ion generation site to the surface of the substrate holding surface is overlooked, effective charge removal cannot be performed. The effect of recombination of ions in the piping will be described with reference to FIG. FIG. 6A shows a situation where ions are recombined in the pipe. When ions are recombined in this way, the number of ions that reach the substrate holding surface from the ion generation site is reduced, so that the charge when the substrate is peeled from the substrate holding surface cannot be effectively neutralized.

  On the other hand, when using an ionizer of the type in which the polarity of generated ions is switched over time, such as an alternating current, pulsed DC method, or pulsed AC method, the ionizer frequency is used to prevent ion recombination. A means of lowering can be considered. That is, the ionizer frequency is a frequency at which the polarity of the generated ions is switched over time, and the ion recombination is prevented by increasing the switching time. FIG. 6 (b) shows this situation, however, the time unevenness of ions is generated in the pipe, which causes the adverse effect of charging the glass substrate.

  In the present invention, there is provided an apparatus and method in which ions in an ionized gas reach the substrate holding surface without recombination, effectively neutralize the back surface of the glass substrate, and do not cause unevenness of ions over time. To do.

A substrate processing method according to the present invention includes a stage for placing an insulating substrate,
A lift pin in the stage for lifting the substrate;
Piping connected to the holes on the stage surface,
A vacuum exhaust unit and a gas supply unit connected to the pipe;
A vacuum valve provided between the hole and the vacuum exhaust part;
A vacuum breaking valve provided between the hole and the gas supply unit;
An ionizer connected to the pipe between the gas supply unit and the vacuum breaking valve, ionizing the gas introduced from the gas supply unit, and further switching the polarity of the generated ions in time;
A frequency control unit capable of changing a frequency at which the polarity of ions generated from the ionizer is switched;
Using a substrate processing apparatus provided with a lift-up control unit that controls the lifting operation of the lift pins,
In a state where the substrate is placed on the stage,
A step of introducing the gas into the pipe by opening the vacuum breaking valve;
Operating the ionizer at a first frequency by the frequency controller;
Starting the separation of the substrate from the stage by raising the lift pins;
While the substrate is spaced from the stage,
And a step of increasing the frequency of the ionizer by the frequency control unit .

  When the lift-up of the substrate is started, the accumulated charge on the back surface of the substrate is the largest, and the accumulated charge is reduced by making ions efficiently reach the back surface of the substrate by using a low frequency ionizer. At this point in time, the ion bias (unevenness) remains, so that the unevenness of the ions is removed by gradually increasing the frequency thereafter. Recombination due to the high frequency occurs, but this is not a problem because the amount of accumulated charge on the back surface of the substrate is reduced by ions from the ionizer having a low frequency at the start of lift-up.

1 is a diagram illustrating a configuration of a substrate processing apparatus according to a first embodiment. FIG. 6 is a diagram showing a relationship between a substrate lift-up operation and a substrate charge amount according to the first exemplary embodiment. (a) In the conventional substrate processing apparatus, it is the figure which showed the relationship between a substrate lift-up operation | movement and the charging amount of a board | substrate when the frequency of an ionizer is low and constant. (b) In the conventional substrate processing apparatus, it is the figure which showed the relationship between the substrate lift-up operation | movement and the charging amount of a board | substrate when the frequency of an ionizer is constant. It is a figure which shows the structure of the substrate processing apparatus concerning Embodiment 2. FIG. It is a figure which shows the structure of the substrate processing apparatus concerning Embodiment 3. FIG. It is the figure which showed the condition of the ion in the piping of the conventional substrate processing apparatus.

  The preferred embodiments of the present invention will be described below. FIG. 1 shows a substrate processing apparatus according to the first embodiment. In the figure, 1 is a glass substrate for a liquid crystal display panel, 2 is a stage for holding the glass substrate 1 for processing the glass substrate 1, and 3 is a lift pin for raising and lowering the glass substrate 1 with respect to the stage 2 It is. A hole 4 is opened on the surface of the stage 2, and the hole 4 is connected to a pipe 5. Further, in the pipe 5, there are a vacuum valve 6 and a vacuum breaking valve 7, and there are a vacuum exhaust part 8 and a gas supply part 9 at the end of each pipe. In other words, the vacuum valve 6 is provided between the vacuum exhaust part 8 and the hole 4, and the vacuum breaker valve 7 is provided between the gas supply part 9 and the hole 4.

  Between the vacuum breaking valve 7 and the gas supply unit 9, an AC ionizer 10 is provided for mixing ions into the air in the pipe 5. The ionizer 10 has a needle tip to which an alternating high voltage is applied, and the frequency of the alternating high voltage can be controlled from an external frequency control unit 11. That is, the frequency control unit 11 can control the frequency of the ionizer, which is a frequency for temporally switching the polarity of ions generated from the ionizer 10. A lift-up control unit 12 moves the lift pin 3 up and down, and exchanges signals with the frequency control unit 11.

  Next, the operation of the substrate processing apparatus according to the present invention will be described. First, while the substrate is being processed such as coating, drying, and cooling, the vacuum breaking valve 7 is closed and the vacuum valve 6 is opened, and the glass substrate 1 is fixed by being vacuum-sucked to the stage 2. Has been.

  When the processing on the substrate is completed, the vacuum valve 6 is closed and the vacuum breaking valve 7 is opened, so that a gas such as air or nitrogen is introduced into the pipe 5 from the gas supply unit 9. Then, at the same time as or after the vacuum breaking valve 7 is opened, an AC high voltage having a first frequency of 1 Hz, for example, is applied to the ionizer 10 to start an ion generation operation.

  On the other hand, the air supplied from the gas supply unit 9 passes through the pipe 5 and is supplied between the glass substrate 1 and the stage 2 through the hole 4. When the vicinity of the hole 4 in the pipe 5 reaches atmospheric pressure, the lift pin 3 starts to rise, and the glass substrate 1 starts to be separated from the stage 2, that is, lifted up.

  Immediately after the start of lift-up, the frequency of the ionizer 10 is as low as 1 Hz as the first frequency, for example, and therefore, temporal nonuniformity occurs in the polarity of ions generated from the ionizer 10. However, on the other hand, recombination of ions in the pipe 5 hardly occurs. Therefore, although there is some loss of ions due to recombination, a sufficient amount of ions can reach the glass substrate 1.

  Further, since the ions supplied to the glass substrate 1 are uneven in polarity as described above, the ions are repelled in the time zone in which ions having the same polarity as the static electricity accumulated on the back surface of the glass substrate 1 are supplied. The static electricity accumulated on the back surface of the glass substrate 1 does not increase. On the other hand, the static electricity on the back surface of the glass substrate 1 is effectively neutralized in the time zone in which the polarity of the ions is switched and ions having the opposite polarity are supplied.

  The lift-up control unit 12 raises the lift pin 3 and sends information that matches the amount of the lift pin 3 to the frequency control unit 11. The frequency control unit 11 processes the information and controls the frequency of the ionizer 10 to continuously increase in accordance with the lift amount of the lift pin 3. At this time, it is more preferable to control in consideration of the time until ions ionized by the ionizer 10 reach the glass substrate 1.

  As the frequency of the AC high voltage of the ionizer 10 is increased, the temporal non-uniformity of the polarity of ions supplied to the glass substrate 1 decreases. In addition, the amount of ions supplied to the glass substrate 1 is also reduced from the initial lift-up. However, the substrate 1 at the time when the lift-up has progressed is not a problem because it is sufficiently neutralized by low-frequency ions such as the first frequency at the beginning of the lift-up.

  Rather, even if the peeling charge of the substrate 1 is sufficiently neutralized, the charging of the substrate 1 is unstablely increased by irradiating with low-frequency ions that cause uneven polarity over time. There is a harmful effect that causes. In the embodiment of the present invention, as the charging of the substrate 1 is neutralized, the time-dependent unevenness of the polarity of ions is reduced, thereby reducing the peeling charge of the substrate 1.

  Then, the frequency control unit 11 performs control so that the ionizer 10 operates at a second frequency, for example, 60 Hz, when the lift pin 3 is completely raised. Here, the second frequency is set higher than the first frequency.

  The above-described static elimination situation and the lift pin 3 rise situation are shown in FIG. 2 as a time-series graph. In FIG. 2, the thin line in the graph indicates the lift height of the lift pin 3, and the thick line indicates the charge amount of the substrate 1. The horizontal axis shows the passage of time. The charge amount of the substrate 1 is zero on the horizontal axis, the polarity is different between the upper side and the lower side of the horizontal axis, and the charge amount increases as the distance from the horizontal axis increases.

  In FIG. 2, since the frequency of switching the polarity of the ionizer is low at the initial stage of the lift pin 3 rising, the charge amount of the substrate 1 varies greatly. However, as the lift pin 3 rises, the frequency increases and the charge amount of the substrate 1 increases. Will converge to zero.

  On the other hand, a similar graph is shown in FIG. 3 as a comparative example. The notation of the graph is the same as in FIG. Here, FIG. 3A is a diagram showing the relationship between the substrate lift-up operation and the substrate charge amount when the frequency of the ionizer 10 is low and constant in a conventional substrate processing apparatus. FIG. 3B is a diagram showing the relationship between the substrate lift-up operation and the charge amount of the substrate when the frequency of the ionizer 10 is high and constant in a conventional substrate processing apparatus.

  In FIG. 3 (a), since the frequency of polarity switching of the ionizer 10 is low, fluctuations in the charge amount of the substrate 1 do not converge and remain large. On the other hand, in FIG. 3B, since the frequency of the ionizer 10 is high, the above-described ion recombination suppresses the static elimination effect, and the increase in the charge amount of the substrate 1 due to the lift-up operation cannot be suppressed. As a result, the charge amount of the substrate 1 is increased. Here, the amount of charge on the substrate increases with the lift-up operation, for example, as described in JP-A-11-271735. This is generally due to changes in the capacity.

  When the lift-up is completed, the vacuum break valve 7 is closed, and at the same time, the ionizer 10 is stopped. At this time, the back surface of the glass substrate 1 can be in a state where static electricity is not accumulated.

  Here, since the ionizer 10 is provided on the gas supply part 9 side of the vacuum breaker valve 7, the inside of the ionizer 10 is not exposed to vacuum, and special considerations such as prevention of vacuum leakage are necessary for the ionizer 10 itself. There is an effect that there is no.

  In addition, if the ionizer 10 operates when no air is flowing through the ionizer 10, ions stay in the vicinity of the needle tip, and foreign matter adheres to the needle tip, deterioration of the piping, etc. progress, and in a short period of time. Although maintenance is required, in the present embodiment, the operation of the ionizer 10 is performed only when the vacuum break valve 7 is open.

  Moreover, although the form in which the frequency of the alternating high voltage of the ionizer 10 reaches the second frequency when the lift pin 3 is completely raised has been described, it is not necessarily limited to this form. If the charging of the substrate 1 is neutralized before the lift pins 3 are completely lifted, it is only necessary to include a step of increasing the frequency of the AC high voltage of the ionizer 10 while the lift pins 3 are lifted. If the charging of the substrate 1 is neutralized before the lift pins 3 are completely raised, the operation of the ionizer 10 may be stopped when the lift pins 3 are completely raised.

  Here, the lowest frequency is 1 Hz and the highest frequency is 60 Hz. However, the most effective frequencies are the pipe length, air flow rate, ionizer position, lift-up amount, lift-up speed, etc. Therefore, the frequency may be determined appropriately in consideration of these.

  For example, if one cycle at the first frequency elapses in the time required from the start to completion of lift-up, the substrate 1 is irradiated with both ions having different polarities, so that the charge is neutralized. Good to do. That is, the first frequency may be set higher than the reciprocal of the lift-up required time.

  Furthermore, in the present embodiment, a mode has been described in which the frequency is increased so as to increase continuously and linearly from the first frequency in accordance with the lift amount of the lift pin, and the second frequency is reached. However, it is not necessarily limited to this, and it may rise step by step or stepwise. For example, if the time required for lift-up is 6 seconds, the first 2 seconds is 1 Hz, the next 2 seconds is 30 Hz, and the last 2 seconds. You may make it operate | move at 60 Hz. Moreover, you may control so that the frequency of an alternating current high voltage increases acceleratingly as lift-up progresses.

Embodiment 2
In the first embodiment, the frequency of the ionizer 10 is controlled based on the information from the lift-up control unit 12 that controls the lifting and lowering of the lift pins 3, but the distance from the stage 3 of the glass substrate 1 as shown in FIG. May be provided, and a signal commensurate with the height of the glass substrate 1 from the sensor 13 may be sent to the frequency control unit 11 to control the frequency of the ionizer 6.

Embodiment 3
In the first embodiment, the ionizer 10 is provided on the air supply side of the vacuum breaker valve 7, but may be provided on the stage side of the vacuum breaker valve 7, as shown in FIG. Since the ions can be arranged closer to the glass substrate 1, recombination of ions in the pipe 5 hardly occurs, and more ions can be supplied to the glass substrate 1 than in the first embodiment even in a high frequency region. Yes, the charge removal capability is increased.

Embodiment 4
In the first embodiment, the ionizer 10 is operated only when the vacuum breaking valve 7 is open. However, if the ionizer 10 is operated before the vacuum breaking valve 7 is opened, the vacuum breaking valve 7 is opened. Therefore, there is no delay in the generation of ions when the air starts to be supplied, and it is preferable that sufficient ions are supplied from the moment when the air is supplied.

Embodiment 5
In the first embodiment, an AC type in which an AC high voltage is applied to one discharge needle is used as the ionizer 10. However, any ionizer in which the polarity of generated ions changes with time can be used. A pulse DC type in which the polarity of ions generated every time is determined and the polarity is switched, or a pulse AC type in which a high voltage in which the polarity is switched in a pulse manner is applied to one discharge needle may be used.

1 substrate, 2 stages, 3 lift pins, 4 holes, 5 piping,
6 Valve for vacuum, 7 Valve for vacuum break, 8 Vacuum exhaust part, 9 Gas supply part,
10 ionizer, 11 frequency control unit, 12 lift-up control unit,
13 sensors

Claims (4)

And stages for placing the insulating substrate,
A lift pin in the stage for lifting the substrate;
Piping connected to the holes on the stage surface,
A vacuum exhaust unit and a gas supply unit connected to the pipe;
A vacuum valve provided between the hole and the vacuum exhaust part;
A vacuum breaking valve provided between the hole and the gas supply unit;
An ionizer connected to the pipe between the gas supply unit and the vacuum breaking valve, ionizing the gas introduced from the gas supply unit, and further switching the polarity of the generated ions in time;
A frequency control unit capable of changing a frequency at which the polarity of ions generated from the ionizer is switched ;
By using a substrate processing apparatus including the lifting-up control unit for controlling the vertical movement of the upper Symbol lift pins,
In a state where the substrate is placed on the stage,
A step of introducing the gas into the pipe by opening the vacuum breaking valve;
Operating the ionizer at a first frequency by the frequency controller;
Starting the separation of the substrate from the stage by raising the lift pins;
While the substrate is spaced from the stage,
And a step of increasing the frequency of the ionizer by the frequency control unit. At the time when the lifting of the lift pin is completed,
The ionizer is operating at a second frequency;
The substrate processing method according to claim 1 , wherein the second frequency is higher than the first frequency. The substrate processing apparatus further includes a sensor that detects a distance between the substrate and the stage,
3. The substrate processing method according to claim 1, wherein in the step of increasing the frequency of the ionizer, a signal is sent from the sensor or the lift-up control unit to the frequency control unit. 4. The substrate processing method according to claim 1, wherein the substrate is subjected to any one of coating, drying, and cooling before the vacuum break valve is opened.

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