JPH0669184A - Vapor drier - Google Patents

Abstract

PURPOSE:To prevent the occurrence of futile processing time and dry shortage by measuring the concentration of the organic solvent gas inside the exhaust gas, which includes the organic solvent gas evaporated from the object to be processed inside a drying room, with an organic solvent concentration meter positioned in the middle of an exhaust duct. CONSTITUTION:The detector 13 of a one-point independent type IPA gas detector and alarm 12 as an organic solvent concentration meter is interposed in the middle of the duct 11 connected to a dry room 10, and this detector 13 is connected electrically to a directive alarm part 14. What is more, this IPA gas detector and alarm 12 uses a semiconductor type IPA, so if IPA gas contacts with this semiconductor IPA sensor, the electric conductivity of the sensor increases, and the quantity of this increase is taken out as output by a series resistor. Hereby, the point of time of evaporation end of the organic solvent in the object to be processed can be detected, and the dry processing can be finished before the passage of a preset processing time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drying technique, and more particularly to a technique for drying an object to be processed by using an organic solvent vapor, for example, a technique for drying a wafer after washing in a semiconductor device manufacturing process. Regarding what is effective to use.

[0002]

2. Description of the Related Art In a semiconductor device manufacturing process, an organic solvent such as iso-propyl alcohol (IPA) is stored at the bottom of a vapor tank as a drying device for drying a wafer after washing with water, Heat to generate vapor, immerse a plurality of wafers in this vapor atmosphere in a state of being held by a jig, and replace water and an organic solvent that is a droplet of vapor by a temperature difference between the wafer and the vapor, After that, a vapor drying device configured to dry the wafer by evaporating the organic solvent attached to the wafer in a drying chamber,
There is.

In such a vapor drying apparatus, the time for pulling the immersed wafer group out of the vapor atmosphere and from the drying chamber is uniformly set by the following method.

That is, in a state where the wafer and the wafer jig are fully charged in the vapor tank, the time until the moisture adhering to the wafer and the jig is completely replaced by the vapor drops, and the replacement The time required for the organic solvent to completely evaporate in the drying chamber is experimentally determined. The predetermined processing time is uniformly set by adding the margin time obtained by the experience side to the minimum time obtained by this experiment.

Incidentally, as an example in which the vapor dryer is described, Japanese Patent Laid-Open No. 168072/56 and Japanese Utility Model Publication No.
9-138232.

[0006]

In the above-described vapor drying apparatus, since the vapor drying treatment time is set uniformly based on a specific experiment, the present invention has the following problems. Revealed by the person.

(1) Since the drying processing time is uniformly set based on the state of the wafer and the jig holding the wafer in the vapor tank being fully charged, when a small number of wafers are processed, Wastes processing time.

(2) Since the processing time is uniformly set, when an abnormality or a special situation occurs, insufficient drying occurs.

An object of the present invention is to provide a vapor drying apparatus capable of preventing wasteful processing time and preventing insufficient drying.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0011]

The typical ones of the inventions disclosed in the present application will be outlined below.

That is, the organic solvent is stored at the bottom of the vapor tank, the organic solvent is heated to generate vapor, and the object to be treated is immersed in the vapor atmosphere, and the temperature difference between the object to be treated and the vapor is applied. In a vapor drying device configured to replace water with an organic solvent that is a drop of vapor and then evaporate the organic solvent adhering to the object to be processed in a drying chamber to dry the object to be processed, An exhaust duct for collecting exhaust gas containing an organic solvent gas evaporated from the object to be processed is connected to the chamber, an organic solvent concentration meter is provided in the middle of the exhaust duct, and the organic solvent concentration meter exhausts gas. It is characterized in that it is configured to measure the concentration of the organic solvent gas in the exhaust flowing down the duct.

[0013]

According to the above-mentioned means, the concentration value of the organic solvent gas in the exhaust gas can be measured by the organic solvent concentration meter.

After the start of evaporation of the organic solvent in the drying chamber, the concentration of the organic solvent gas in the exhaust gas flowing through the exhaust duct once rises because the organic solvent gas evaporated from the object to be processed is contained in the exhaust gas. Then, when the organic solvent of the object to be treated is completely evaporated and exhausted, the organic solvent gas concentration in the exhaust is restored to the original low concentration.

Therefore, by detecting the time when the concentration of the organic solvent gas in the exhaust gas is recovered, the time when the organic solvent of the object to be treated is completely evaporated can be known. Then, according to the above-mentioned means, since the recovery time can be detected by measuring the concentration of the organic solvent gas in the exhaust gas by the organic solvent concentration meter, the vapor drying treatment time can be appropriately adjusted according to each treatment situation. Can be controlled.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a front sectional view showing a vapor drying apparatus which is an embodiment of the present invention. FIG. 2 is a diagram for explaining the operation.

In the present embodiment, the vapor drying apparatus according to the present invention is provided with a vapor tank 3 which is made of quartz glass and is formed in a substantially rectangular box shape. The vapor tank 3 has an upper portion to be treated. An entrance / exit 4 for opening / closing a holding jig (hereinafter, referred to as a jig) 2 holding a wafer 1 as an object is opened.

A coil-shaped cooling pipe 5 for circulating cooling water is mounted on the inner peripheral wall of the inlet / outlet 4 of the vapor tank 3. At the bottom of the vapor tank 3, isopropyl alcohol (hereinafter referred to as IPA) as an organic solvent.
6 is stored, and the IPA 6 is supplied from the outside of the vapor tank 3 by a liquid supply pipe (not shown).

Below the vapor tank 3, a heating device 8 including an infrared heater or a heat block having a sheathed heater embedded in a block of iron or aluminum is installed. The heating device 8 heats the IPA 6 by heating it. , Is vaporized forcibly to generate the vapor 7.

The vapor tank 3 is installed in a chamber 9, and a drying chamber 10 is set above and outside the vapor tank 3 in the chamber 9. The drying chamber 10 is evacuated by a ventilator or the like (not shown) through an exhaust duct 11 connected to the drying chamber 10, so that the IPA 6 that wets the wafer 1 and the jig 2 can be effectively evaporated. ing.

In the middle of the exhaust duct 11, a detector 13 of a one-point independent type IPA gas detector / alarm 12, which serves as an organic solvent concentration meter, is provided. Connected to each other. The instruction warning unit 14 is installed in a place where the operator can easily confirm it.

The IPA gas detection alarm device 12 uses a semiconductor IPA sensor, and is composed of a sintered body containing SnO ₂ as a main component and a pair of heater coils also serving as electrodes. When the IPA gas comes into contact with the semiconductor type IPA sensor, chemisorption occurs on the surface of the sensor, free electrons move inside the sensor, and the electrical conductivity of the sensor increases. It is taken out as an output by a resistor.

The jig 2 is hung and set in the drying chamber 10 by a handler 15. The jig 2 is made of a fluororesin having good chemical resistance and is used as an object to be treated. It is configured to be able to hold one or a plurality of wafers 1.

In this embodiment, the IPA in the vapor tank 3 is
A tray 20 having an upper opening is installed above the liquid level of 6 so as to be able to receive dripping water droplets. The bottom of the tray 20 communicates with the outside of the vapor tank 3 and the chamber 9. The drainage pipe 21 is connected. Drainage pipe 2
The outlet end of 1 is connected to a recovery tank 22 installed outside the chamber 9.

A drainage pool 23 is provided vertically downward in the middle of the drainage pipe 21 outside the chamber 9, and the drainage pool 23 is always replaced by a new drainage 24. It has a small volume.

An electrode 26 of the IPA resistivity meter 25 is inserted in the drainage reservoir 23.
6 is connected to the measuring unit 27. The IPA resistivity meter 25 detects the resistance of the drainage liquid 24, which changes depending on the mixing ratio of IPA and water, by the electrode 26, and electrically measures the resistivity value of the IPA by the measuring unit 27 to remove the drainage. IPA corresponding to the concentration of IPA in liquid 24
Is configured to measure the ratio of to water.

Next, the operation will be described. The liquid of IPA 6 stored at the bottom of the vapor tank 3 is heated by the heating device 8 and evaporated to generate vapor 7.

The vapor 7 thus heated and generated in the vapor generating portion rises due to the convection phenomenon,
The vapor tank 3 gathers in the object storage part substantially formed in the substantially central part and comes into contact with the wafer 1 and the jig 2 housed in the object storage part.

The contacting vapor 7 is the wafer 1 and the jig 2.
Since it is cooled by, it descends due to the convection phenomenon and is returned to the vapor generating portion at the bottom. Then, the vapor 7 recirculated to the vapor generating portion is heated again, and thus rises again together with the newly generated vapor 7.

In this way, the vapor 7 is forcibly recirculated in the vapor tank 3 due to the convection phenomenon. Therefore, the vapor 7 is continuously supplied to the object storage part.

As shown in FIG. 1, a jig 2 accommodating a plurality of wafers 1 (usually about 25) is suspended by a handler 15 and carried into the chamber 9 and vapor. It descends into the tank 3 from the entrance / exit 4 so as to be accommodated in the object accommodation part.

At the time of loading, since the wafer 1 and the jig 2 were washed with water in the previous step, the wafer 1 and the jig 2 are wet with water and are in a low temperature state.

When the wafer 1 and the jig 2 which are in the low temperature state as described above are immersed in the atmosphere of the vapor 7, the vapor 7 is condensed and adheres on the surface thereof. The dewed IPA 6 gradually replaces the moistened water on the surfaces of the wafer 1 and the jig 2, and the wafer 1 and the jig 2
The replacement is completed when the surface temperature of is equal to the vapor temperature.

On the other hand, the water 16 replaced with the IPA 6 flows down along with the foreign matter remaining on the surface and drops onto the tray 20, is collected by the tray 20 and is discharged to the outside through the drain pipe 21. In this way, it is possible to prevent the mixed water from re-evaporating to become water vapor by preventing the water from mixing into the liquid of the IPA 6 stored in the bottom portion of the vapor tank 3. Therefore, it is possible to prevent reattachment of moisture to the wafer 1.

When the replacement is completed, the jig 2 is pulled up from the vapor tank 3 to the drying chamber 10 by the handler 15. When the jig 2 and the wafer 1 are pulled up to the drying chamber 10, the vapor atmosphere of the jig 2 and the wafer 1 is heated and the temperature is raised. It will vaporize (evaporate) while taking away. When the IPA 6 is completely vaporized, the jig 2 and the wafer 1 are dried. The vaporized IPA 6 is prevented from being sucked into the exhaust duct 11 by a ventilator (not shown) in the drying chamber 10 and diffusing to another place.

By the way, if the jig 2 is lowered by the handler 15 into the vapor tank 3 and is taken up to the drying chamber 10, the drying processing time is uniformly set based on the experiment as described above. However, the following waste occurs.

That is, when the number of the wafers 1 on the jig 2 is smaller than that at the time of full charge (25 wafers) (for example, 20 wafers), the moisture 16 attached to the wafer 1 and the jig 2 is 16
Since the amount of is small by the small number, the replacement of water with the vapor 7 is completed quickly. After the replacement is completed, the time for immersing the wafer 1 and the jig 2 in the atmosphere of the vapor 7 is a waste of time.

Therefore, in the present embodiment, the drainage pipe 21
The specific resistance value of IPA6 of the drainage 24 flowing down the
By monitoring with the resistivity meter 25, in a special processing situation such as the processing of a small number of wafers 1, the correction work for the preset processing time is carried out. Next, the correction work will be described.

First, the vapor 7 is always condensed on the tray 20 itself, and the condensed water is continuously discharged to the drain pipe 21 as the drainage 24. The drainage liquid 24 is temporarily collected in a drainage pool 23 formed in the middle of the drainage pipe 21, and is further drained to the recovery tank 22.

The drainage 24 accumulated in the drainage reservoir 23 is I
The resistance is detected by the electrode 26 of the PA resistivity meter 25. The measuring section 27 of the IPA resistivity meter 25 is the electrode 26.
Based on the resistance value detected by
The specific resistance value of IPA in the drainage 24 collected in 3 is measured.

At a time when the drainage 24 is only condensed on the tray 20 itself, most of it is pure IPA, so the IPA specific resistance value is, for example, 500 MΩ · cm or more.
It is extremely high at 2000 MΩ · cm.

Next, when the wafer 1 and the jig 2 are accommodated in the vapor tank 3, the replacement of the moisture 16 with the vapor 7 is started, and the moisture 16 becomes a drop and is dropped on the tray 20. Flow into the drainage pipe 21 and begin to be discharged to the recovery tank 22.

In the middle of the drainage pipe 21, a drainage liquid 24 containing water 16 flows down into the drainage pipe 21, and a drainage reservoir 23
When it temporarily accumulates in IPA6, water 16 is contained in IPA6.
The resistivity value of is extremely low, for example, 10 MΩ · cm.

After that, when the replacement of the moisture 16 with the vapor 7 on the wafer 1 and the jig 2 is completed, the dropping of the moisture 16 onto the tray 20 is stopped and the drainage 2 flowing through the drainage pipe 21.
The water content 16 in 4 is almost lost.

Therefore, in the middle of the drainage pipe 21,
The drainage 24 temporarily collected in the drainage pool 23 is pure I
Since it is only PA6, the IPA specific resistance value of the drainage 24 measured by the IPA specific resistance meter 25 returns to the original high value.

In this way, the IPA specific resistance value of the drainage liquid 24 measured by the IPA specific resistance meter 25 is the original high value,
Alternatively, the jig 2 is pulled up from the vapor tank 3 by the handler 15 based on the time point when the jig 2 is returned to the preset predetermined value.

In a special situation such as the processing of a small number of wafers, the pulling-up operation of the jig 2 is performed manually by an operator even when the preset processing time has not elapsed. It may be executed, or may be executed by electrically connecting the IPA resistivity meter 25 to the controller of the handler 15 and automatically controlling the handler 15.

Further, after the jig 2 is pulled up to the drying chamber 10 by the handler 15, the jig 9 is moved from the drying chamber 10 to the chamber 9.
If the drying processing time until being carried out is set uniformly based on the experiment as described above, for example, the following waste occurs.

That is, when the number of wafers 1 on the jig 2 is smaller than the number of wafers 1 when fully charged (25 wafers) (20 wafers, for example), the IPA 6 attached to the wafer 1 and the jig 2 is reduced.
Since the amount of is smaller than the number of sheets, the vaporization (evaporation) of IPA6 is completed quickly. After the vaporization is completed, the time for keeping the wafer 1 and the jig 2 in the drying chamber 10 is wasted.

Therefore, in this embodiment, the concentration value of the IPA gas in the exhaust gas exhausted from the exhaust duct 11 is IP.
By monitoring with the A gas detection alarm device 12, in a special processing situation such as the processing of a small number of wafers 1, the correction work for the preset processing time is carried out. Next, the correction work will be described.

The concentration of the IPA gas 17 exhausted to the exhaust duct 11 is constantly detected by the sensor unit 13 and displayed by the display alarm unit 14.

The concentration of the IPA gas 17 in the state before the wafer 1 group and the jig 2 are pulled up into the drying chamber 10 after the above-mentioned replacement work of water and vapor is completed,
As shown in FIG. 2, the concentration is as low as 100 to 600 ppm. This is because the vapor 7 in the vapor tank 3 is cold-trapped by the cooling pipe 5 and does not enter the drying chamber 10.

When the group of wafers 1 and the jig 2 for which the replacement work has been completed are pulled up into the drying chamber 10, the IPA 6 attached to the group of wafers 1 and the jig 2 is rapidly vaporized in the drying chamber 10, so that the drying chamber The concentration of the IPA gas 17 exhausted from 10 is 3000 as shown in FIG.
It shows a high value of ˜3500 ppm.

After that, when the vaporization of the attached IPA 6 is completed, the concentration of the IPA gas 17 exhausted from the drying chamber 10 returns to the original low concentration region as shown in FIG. Become.

In this way, the IPA gas detection alarm device 12
The jig 2 is moved from the drying chamber 10 to the outside of the chamber 9 by the handler 15 based on the time when the concentration of the IPA gas 17 in the exhaust gas measured by the original value is returned to the original low value or the preset predetermined value. Be shipped.

In a special situation such as the processing of a small number of wafers, the unloading operation of the jig 2 is performed even when the preset processing time has not elapsed and the IPA gas detection alarm 12 The operator may manually perform the operation based on an alarm such as a blinking lamp or an alarm sound by the display / alarm unit 14 of FIG. 1, or the IPA gas detection alarm device 12 is electrically connected to the controller of the handler 15. Then, the handler 15 may be executed by automatically controlling the handler 15.

According to the above embodiment, the following effects can be obtained. Tray 20 for receiving drops from the wafer 1 and the jig 2
By providing the IPA resistivity meter 25 in the middle of the drainage pipe 21 connected to, the IPA resistivity value of the drainage liquid 24 flowing down the drainage pipe 21 can be measured. Based on the value, it is possible to detect the time when the replacement of the moisture 16 and the vapor 7 in the wafer 1 and the jig 2 is completed.

By detecting the replacement completion time point as described above, the replacement process can be completed before the processing time set in advance by an experiment, and thus wasteful processing time can be saved.

When the replacement completion time is not detected as described above, it is possible to extend the set processing time, and thus it is possible to prevent the occurrence of insufficient drying.

I evaporated from the wafer 1 and the jig 2
By providing the IPA gas concentration meter 12 in the middle of the exhaust duct 11 for exhausting the PA gas 17, the concentration of the IPA gas 17 flowing down the exhaust duct 11 can be measured. Based on this, it is possible to detect the vaporization completion time of the IPA 6 in the wafer 1 and the jig 2.

By detecting the vaporization completion time point as described above, the vaporization process can be finished before the processing time preset by the experiment has elapsed, so that wasteful processing time can be saved.

When the vaporization completion time point is not detected as described above, it is possible to extend the setting processing time, so that the vaporization shortage can be prevented.

As described above, it is possible to improve the throughput of the entire vapor drying process including a special situation such as the process of processing a small number of wafers and the processing of a large number of wafers, and to improve the quality and reliability of the vapor drying process.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, the IPA densitometer and the IPA specific resistance meter are not limited to be used independently, but may be electrically connected to a controller of a handler or the like to feedback control the entire drying process.

The organic solvent densitometer and the organic solvent resistivity meter are not limited to the IPA densitometer and the IPA resistivity meter, and can be appropriately selected according to the organic solvent used such as tricrel or methanol / alcohol. can do.

The organic solvent concentration meter is not limited to the one in which the detector is directly installed in the exhaust duct, but the sampling pipe is connected to the exhaust duct and the detector is installed in the pipe. You may comprise.

If the equipment for the IPA resistivity meter is omitted, only the vaporization completion point can be detected.

In the above description, the case where the invention made by the present inventor is mainly applied to the vapor drying technique for wafers, which is the field of application which is the background of the invention, has been described.
The present invention is not limited to this, and can be applied to general vapor drying techniques for photomasks, optical lenses, and the like.

[0070]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.

By providing a concentration meter for the organic solvent in the exhaust duct of the drying chamber, the gas concentration of the organic solvent in the exhaust flowing through the exhaust duct can be measured, so that the evaporation of the organic solvent in the object to be treated is completed. The time point can be detected.

Then, by detecting the time point when the evaporation is completed, before the processing time preset by the experiment,
Since the drying process can be completed, wasteful processing time can be saved. Further, when the completion point of evaporation is not detected, the set processing time can be extended, so that the occurrence of insufficient drying can be prevented.

[Brief description of drawings]

FIG. 1 is a front sectional view showing a vapor drying apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation.

[Explanation of symbols]

1 ... Wafer (processing object), 2 ... Jig, 3 ... Vapor bath, 4
... gateway, 5 ... cooling pipe, 6 ... IPA (organic solvent),
7 ... Vapor, 8 ... Heating device, 9 ... Chamber, 10 ... Drying room, 11 ... Exhaust duct, 12 ... IPA gas detection alarm device (organic solvent concentration meter), 13 ... Detection part, 14 ... Display alarm part, 15 ... Handler, 16 ... Moisture, 17 ... IPA gas,
20 ... Tray, 21 ... Drainage pipe, 22 ... Recovery tank, 23
... drainage collecting part, 24 ... drainage, 25 ... IPA resistivity meter (organic solvent resistivity meter), 26 ... electrode, 27 ... measuring part.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noboru Tanuma 2-6-2 Otemachi, Chiyoda-ku, Tokyo Inside Ritsuryitsu Engineering Co., Ltd. (72) Inventor Hiroshi Kanbara 2--6-2 Otemachi, Chiyoda-ku, Tokyo No. 2 Nitto Electronics Engineering Co., Ltd. (72) Inventor Tsutomu Rohata 2-6-2 Otemachi, Chiyoda-ku, Tokyo Inside Nikkei Electronics Engineering Co., Ltd. (72) Inventor Megumi Kawamura Two Otemachi, Chiyoda-ku, Tokyo 6th-2nd, inside NitRitsu Denshi Engineering Co., Ltd.

Claims (3)

[Claims] 1. An organic solvent is stored at the bottom of a vapor tank, the organic solvent is heated to generate vapor, and the object to be treated is immersed in the vapor atmosphere, and the temperature difference between the object and the vapor is applied. In a vapor drying device configured to replace water with an organic solvent that is a drop of vapor, and then evaporate the organic solvent adhering to the object to be processed in a drying chamber to dry the object to be processed, An exhaust duct for collecting exhaust gas containing an organic solvent gas evaporated from the object to be processed is connected to the chamber, an organic solvent concentration meter is provided in the middle of the exhaust duct, and the organic solvent concentration meter is an exhaust gas. A vapor drying apparatus, which is configured to measure the concentration of an organic solvent gas in exhaust flowing down a duct. 2. The vapor drying device according to claim 1, wherein the organic solvent concentration meter is connected to a display alarm. 3. The organic solvent densitometer is connected so as to transmit a measurement result to a control system in a transfer device for transferring the object to be processed into and out of the vapor tank and the drying chamber. The vapor drying device according to claim 1.