JPS61241927A - Steam drying device - Google Patents

Abstract

PURPOSE:To contrive the saving of usage of a liquid substance and the improvement in safety by providing a heating device for controlling the temperature inside the lower side of a processing tank to a predetermined value and arranging at least the processed material which is to be steam-dried between the upper part and the lower part side of the process tank. CONSTITUTION:Isopropyl alcohol (IPA) of 100wt% concentration is put in a process tank 11 from a supply pipe 29 and is contained a liquid collection plate 18. The wafer 27 mounted in a cartridge 28 and arranged in the above is steam- dried. The pure water deposited on the wafer 27 or the cartridge 28 take in IPA and evaporate upward, where those are cooled by a cooling device 13 and are liquefied, or the pure water take into IPA and falls downward. As a result, the concentration of the IPA contained in the liquid accepting part 18a of the liquid collection plate 18 is thinned gradually. The IPA vapor steam- dries the wafer 27 and the cartridge 28 in the above and the vapor is cooled by the cooling device 13 and liquefied and falls. The IPA is thus circulated constantly from liquid to gas, from gas to liquid repeatedly, thereby steam- drying the wafer 27 and the cartridge 28.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a steam drying device, and in particular, to a steam drying device for drying workpieces such as quenchers with high purity using steam such as isopropyl alcohol (hereinafter abbreviated as IPA) or Freon. This invention relates to a steam drying device for drying.

[Background technology]

In the LSI manufacturing process, wafers are often washed with water. For example, when performing a thinning process on a polysilicon layer formed on a wafer to adjust the polysilicon resistance, the wafer is washed with water before the thinning process. Water cleaning is also performed before forming a nitride (Si8N4) film or polysilicon film by the CVD method. After these washes, the queha needs to be thoroughly dried. As a drying device, there is a conventional steam drying device as shown in FIG.

FIG. 3 shows an example of a conventional steam drying apparatus, and in the same figure, l is a processing tank made of quartz or stainless steel and having a square cross-sectional shape. Freon or IPA (in this case, IPA2) is stored in 1. A cooling pipe 3 is arranged so as to be wound around the inner peripheral surface of the earthen wall of the processing tank 1.

Both ends of the cooling pipe 30 are externally connected to an electronic cooling device, and a refrigerant, here cooling water, is circulated within the cooling pipe 3. Then, IPA vapor 2 rose upward in the treatment tank 1.
A cooling device 3 consisting of a cooling pipe 3 cools the liquid, liquefies it, and returns it to the bottom.

A heater 4 is disposed outside the bottom of the processing tank 1 and is configured to heat the IPA 2t in the processing tank 1.

Based on this configuration, the IPA 2 in the processing tank 1 is heated by the heater 4 to the υIPA steam generation temperature. Then, a cartridge 6 loaded with a large number of wafers 5 is placed in the processing bath 1 as shown in the figure, and steam drying is performed. That is, the IPA vapor 2 replaces the pure water adhering to the wafer 5 and the cartridge 6, which is a wafer jig, and dries it. IP is applied to water (water droplets 8) adhering to the wafer 5 and cartridge 6.
Inject A into the cooling device 3 and evaporate the water that falls as drops 7 to liquefy it. Further, the IPA vapor 2' that has reached the upper side is also cooled by the cooling device 3, becomes a liquid, and falls back downward.

However, since the wafer 5 and the wafer jig (cartridge 6) bring water into the processing tank 1,
Also, since a large amount of IPA is exhausted to the outside from the upper part of the processing tank 1, the concentration of the IPA solution decreases, and the primary liquid volume also decreases.On the other hand, the heating temperature remains the same. The IPA concentration in the gas phase decreases, reducing the steam drying effect.

Therefore, in order to increase the steam drying effect, it is necessary to input a large amount of tV of IPA, which poses safety and economic problems.

The above is a case where IPA is used, but similar problems occur even when Freon is used. This poses a particular economic problem when large amounts of fluorocarbons are used.

Regarding the steam drying equipment conventionally used for drying processing, please refer to Japanese Patent Application No. 57-89664 and Japanese Patent Application No. 57-21.
It is described in No. 6925.

[Purpose of the invention]

An object of the present invention is to effectively utilize liquid substances (such as IPA and fluorocarbons) with a lower boiling point than water, even at low concentrations, for steam drying, thereby reducing the amount of liquid substances used. It is an object of the present invention to provide a steam drying device f which is economical and can improve safety.

SUMMARY OF THE INVENTION An object of the present invention is to provide a steam drying apparatus that can prevent water marks from forming on a member to be processed, perform uniform drying, and improve yield. There is a particular thing.

The above and other objects and novel features of the present invention include:
It will become clear from the description of this specification and the accompanying drawings.

[Summary of the invention]

A brief overview of typical inventions disclosed in this application is as follows.

In other words, a cooling device is provided in the upper part of the processing tank, a liquid collection part is provided in the lower part of the processing tank, and a liquid substance having a boiling point lower than water, such as IPA, is stored, and A heating device is provided at the lower part of the processing tank to control the inside of the lower part of the processing tank to a predetermined temperature so that the concentration of the vaporized substance in the gas phase is higher than a predetermined value, and the upper and lower sides of the processing tank are heated. By arranging at least the member to be treated by steam drying between them and carrying out the steam drying, even if the concentration of the substance in the liquid phase becomes low, the lower side of the treated shell is heated by the heating device. Since the inside is controlled to the predetermined temperature, the concentration of the substance in the gas phase is maintained at a predetermined value or higher by vaporization of the substance, and steam drying can be effectively continued without reducing the steam drying effect. can. Since the liquid substance in the liquid phase can be used even at a low concentration, it is possible to reduce the amount of the liquid substance used, which is economical and improves safety. Furthermore, it is possible to prevent the occurrence of water marks on the member to be processed, to perform uniform drying, and to improve the yield.

〔Example〕

Fig. 1 is a simplified configuration diagram showing an embodiment of the steam drying apparatus according to the present invention, and Fig. 2 shows the IPA concentration (wt%) in the liquid phase and the boiling point when IPA is stored in the processing tank. ('C
) and IPA 1 degree (wt%) in the gas phase.Hereinafter, the present invention will be explained using FIG. 1 and FIG. 2. An example will be explained in which the drying process after water cleaning of the semiconductor wafer is performed using IPA vapor.

In figure M1, 11 is a treatment tank using stainless steel, and this treatment is 4%! The horizontal cross-section of 11 has a rectangular shape. Note that quartz may be used as the material for processing 4!111. In addition, a cooling pipe t2 is arranged at the upper part of the processing tank 11 so as to wrap around its inner peripheral surface, and both ends of the pipe t2 are connected to an external electronic cooling device (not shown) for cooling. A refrigerant and cooling water are circulated within the pipe 12'. The cooling device 13 is constructed by circulating cooling water through the cooling pipe 12. Processing tank 11
The IPA vapor that has risen to the top as shown by the arrow 14 is cooled by the cooling device 13, liquefied, and falls.

A liquid collecting section 15 is provided on the lower side of the processing 4!11. The liquid collection section 15 is formed by a plurality of sets (in this case three sets) arranged vertically in which one branch plate 16 is connected to two liquid collection plates 18 by a support rod 17. Branch plate 16
is a member whose cross-sectional shape is F-shaped as shown in the figure, and the processing 1
11 (inner walls parallel to the plane of the paper) facing each other. Further, as shown in the figure, the liquid collecting plate 18 has an end bent to form a liquid receiving portion 18a.
It is provided so as to come into contact with both opposing inner walls of the processing tank 11 (inner walls parallel to the paper surface). One end of each liquid collecting plate 18 is welded to the inner wall of the processing tank 11. The branch plates 16 are attached to one end of a support rod 17, for example, at four locations, two on the left and right, respectively, and the other end of the support rod 17 is attached to a liquid collection plate 18.

Further, a heater 19 as a heating device is disposed outside the bottom of the processing tank 11, so that the entire liquid collecting section 15 on the lower side of the processing tank 11 is controlled at 83 to 81°C.

In addition, a drain pipe 20 is connected to the side wall at the bottom of the processing tank 11, and by opening the valve 21, only the IPA containing a large amount of moisture accumulated at the bottom of the processing tank 11 can be drained. It has become.

Further, at the upper end of the processing tank 11, N gas (an inert gas may be used) flows from one side toward the other side to the opening 22 of the processing tank 11, and a member 23 for forming a curtain is placed at the opening. 22t - mounted in a surrounding manner.This member 23 has an N on one side.

A gas supply port 24 is provided on the other side, and an exhaust port 25t is provided on the other side, and both sides parallel to the plane of the paper are closed. That is, only both sides in the direction perpendicular to the plane of the paper are opened as shown in the figure so that N and gas can be supplied and exhausted. A lid 26 is provided on this member 23 so as to be openable and closable. Only when this lid 26 is opened, N is applied from one side of the member 23 to the other side.
, flow the gas to form a N curtain.

The cartridge 28 loaded with the wafer 27 as a member to be processed to be subjected to steam drying is opened in the processing tank 11 by opening the lid 26.
located between the lower side and the upper side of the Here, when putting the cartridge 28 into the processing tank 11, it is possible to prevent air from being drawn in from the outside by placing a N gas curtain over the opening 22, and also by opening the lid 26 and placing the cartridge 28 in the processing tank 11. When taking it out of the processing tank 11, a curtain of N gas is used to blow it toward the IPATh exhaust port 25 attached to the wafer 27 and cartridge 28 in the atmosphere, and it is possible to prevent outside air from being drawn in.

Also, on the side wall of the processing tank 11, a liquid collection part 14 in the processing tank 11 is provided.
A supply pipe 29 is attached to supply IPA 30 to the processing tank 11, and the IPA 30 is supplied into the processing tank 11 through this supply pipe 29 in advance and during subsequent replenishment. The IPA 30 falls from the supply pipe 29 in the direction of the arrow, and the liquid receivers of the three-stage liquid collecting plate 18 are divided into parts 18& for storage. Note that a separate tray may be prepared as a tray for storing IPA. Further, 31 is a falling liquid, and 32 is a vapor.

In addition, the heater 19 causes the inside of the lower part of the processing tank 11 to
Since the temperature is controlled at 81℃, the IPA concentration in the liquid phase is approximately 20 to 40wt corresponding to this temperature, as shown in Figure 2.
% (approximately 20 wt% at 83°C, approximately 40 wt% at 81°C), that is, the liquid has a water content of approximately 60 to 80 wt%.
The branch plate 16 is installed so that the IPA containing less than
, the liquid collecting plates 18 are arranged in multiple stages, each of which has three stages as shown in the figure. When the IPA concentration in the liquid phase falls below the concentration corresponding to the temperature shown in Figure 2, the liquid does not vaporize and the process is completed.
It will be stored at the bottom of 1. For example, if the temperature is controlled at 83°C, a liquid with an IPA concentration of 20 vt% or more in the liquid phase will be vaporized before it falls from the liquid collection part 15 to the bottom of the processing tank 11, but in the liquid phase IPA concentration is 20w
The liquid below t% (IPA liquid containing a large amount of water) is not vaporized before it falls to the bottom of the processing tank 11, but is stored at the bottom.

Based on the above configuration, first, 30 tons of IPA with a concentration of 100 wt % is introduced into the processing tank 11 through the supply pipe 29 and stored in the liquid collecting plate 18 . Then, the wafer 2 mounted on the cartridge 28 as shown above is steam-dried! l! Do the following.

At this time, the lid 26 is closed and Nm gas is not supplied from the supply port 24 of the member 23. The pure water adhering to the wafer 27 or cartridge 28 mixes with IPAt, evaporates and goes upward, is cooled by the cooling device 13 and becomes liquefied, or the pure water sinks in with IPAt and falls downward. do. As a result, the wafer 27 and the cartridge 28, which is a wafer jig, are steam-dried, and the concentration of IPA stored in the liquid receiver portion 18a of the liquid collecting plate 18 is gradually diluted. On the other hand, IPA vapor is generated one after another and vapor-dries the wafer 27 and cartridge 28 above, and the vapor that reaches the upper part is quickly cooled by the cooling device 13, liquefies, and falls.

In this way, the IPA is constantly cycled from liquid to gas and from gas to liquid, and vapor drying is carried out on the wafer 27 and the cartridge 28.

Here, the IPA concentration and boiling point in the liquid phase and the IP in the gas phase
The relationship with the A concentration is shown in Figure 2. Generally, when IPA in the liquid phase contains 60 to 80 wt% of water, an inflection point occurs in the boiling point and the boiling point becomes high. As can be seen from Figure 2, if the IPA in the liquid phase contains 180 wt% water, it is approximately 83%
An inflection point occurs at the boiling point of °C, and the IPA concentration in the gas phase also decreases to 1
The amount decreased slightly from 30 wt% to approximately 76 wt%. However, when PAFi contains 80 wt% or more of water, not only does the boiling point suddenly rise, but also the IPA 11 degrees in the gas phase suddenly becomes diluted. If the IPAa degree in the liquid phase is 40 wt% or more, the IPA concentration in the gas phase is also high, 80 wt% or more, which is suitable for steam drying. This steam drying effect is sufficient if the IPA concentration in the gas phase is at least about 76 to 80 wt%, so the IPA concentration in the gas phase should be about 76 wt% or more. That is, it is sufficient to make it possible to vaporize even an IPA concentration of 20 wt% in the liquid phase. Tsumashihita 19
The temperature inside the lower part of the processing tank 11 may be controlled to approximately 83°C.

Here, since the temperature is controlled in the range of 83 to 81°C, the limit of IPAm degrees in the liquid phase that can be effectively used for steam drying is also 2 as shown in Figure 2.
It varies in the range of 0 to 40 wt%. However, in this case, the IPA specularity in the gas phase never becomes less than about 76 wt%, and no problem occurs.

At a temperature of 83-81°C, the IPA concentration in the liquid phase is 40°C.
When the content is more than 80% by weight, vaporization occurs dramatically as shown in FIG. 2, and the IPAI 211 degrees in the gas phase becomes 80% by weight or more. Therefore, another wafer 27 mounted on the +7 wafer 28 is continuously replaced with another car and subjected to drying processing, and the wafer 27 is constantly and uniformly vapor dried until the IPA concentration in the liquid phase reaches the limit of 20 to 40 wt%. can continue. For example, if the temperature is constantly controlled at 83°C, until the IPA concentration in the liquid phase reaches approximately 20wt%, the temperature is kept at 82°C.
If the temperature is constantly controlled at ℃, the IPA concentration in the liquid phase will be approximately 3.
Evaporation is performed from the liquid phase of the branching plate 16 and the liquid collecting plate 18 until it becomes 0 wt%, passing through the gap between the branching plate 16 and the liquid collecting plate 18, and rising to 27 locations on the wafer. ,
The IPA concentration in the gas phase can be maintained at the concentration required for steam drying effectiveness, and effective steam drying can continue.

Next, we will discuss replenishment of IPA. For example, if the liquid collection part 15 is constantly controlled at 83°C, the IP in the liquid phase
When the A concentration becomes 20 wt% or more, evaporation will no longer occur, so when the IPA concentration in the liquid phase reaches 20 wt%, IP
By replenishing A through the supply pipe 29, steam drying can be carried out at a high IPA concentration of approximately 76% or more in the gas phase. Here, IPA 11 degrees in the liquid phase is 20wt
% can be calculated in advance, so in reality, it is sufficient to replenish a predetermined amount of IFA from the supply pipe 29 after a predetermined time has elapsed. Therefore, even when controlling at 83 to 81'C, when the IPA temperature in the liquid phase reaches a concentration at which evaporation does not occur, that is, when the preset time has elapsed, IPA
Good for replenishing O.

In addition, after a certain period of time, a predetermined amount of IPA liquid containing sufficient moisture that cannot be used for steam drying is deposited at the bottom of the processing tank 11 (when controlling at a temperature of 83°C, the IPA concentration in the liquid phase is 2).
Less than 0% fluid accumulates. ), the valve 21 can be opened and the liquid can be drained through the drain pipe 20t.

As can be seen from the above, when the temperature is controlled at 83 to 81°C, only the liquid with an IPA concentration of 20 to 40 wt% or more in the liquid phase can be evaporated, and the IPA concentration in the liquid phase is 2.
Even if the concentration is as low as 0 to 40 wt% (IPA containing 60 to 80 wt% of water), it can be evaporated, so the IPA concentration in the gas phase can always be maintained at a high concentration of about 76% or more. Steam drying can be continued effectively without reducing the steam drying effect. In this way, even if the IPAa concentration in the liquid phase becomes low, it can be used effectively (steam drying can be carried out), so it is possible to significantly reduce the amount of IPA used, which is not only economical but also Safety can be improved.

In addition, it is possible to prevent quarter marks from occurring on the wafer 27, which is the member to be processed, and it is possible to perform uniform drying.
Yield is improved.

Furthermore, since the upper part of the processing tank 11 is closed by the lid 26 during steam drying, IPA vapor can be prevented from being released to the outside as in the conventional case, and the loss of IPA can be greatly reduced.

〔effect〕

(1) Even if the concentration of a liquid substance with a boiling point lower than that of water in the liquid phase becomes low, a heating device is used to maintain the temperature of the substance in the gas phase at a predetermined value or higher in the lower part of the treatment tank. Since the inside of the side is controlled to a predetermined temperature, the concentration of the substance in the gas phase is maintained at a predetermined value or higher by vaporizing the substance, and therefore, the vapor drying effect on the workpiece is not reduced and is effectively dried. Steam drying can be continued.

(2) When the concentration of the substance in the liquid phase becomes low, conventionally it is necessary to replenish the substance in large quantities, but in the present invention, even if the concentration of the substance in the liquid phase is low, steam drying can be carried out effectively. Therefore, it is possible to reduce the amount of the substance used,
This makes it possible to improve safety while being economical.

(3) It is possible to prevent the occurrence of water marks on the workpiece to be steam-dried, and it is possible to perform uniform drying, thereby improving the yield.

(4) In addition to being able to dry the member after washing with water, it is also possible to wash (dry) oil adhering to the member.

(5) During steam drying, by covering the processing tank, it is possible to prevent the substance from being released to the outside as steam, thereby reducing the loss of the substance.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. Nor. For example, the liquid collection part 15
The branch plate 16 is attached to the liquid collection plate 18 via the support rod 17, and the liquid collection plate 18 is attached to the inner wall of the processing tank 11. For example, two support rods are made to stand upright at appropriate positions on both the left and right sides of the liquid collection plate 182, and these support rods are bored in each liquid collection plate 182 and branch plate 16, and passed through nine holes to connect these support rods and each liquid collection plate 18 and branch plate. 16 may be welded at the hole.

In addition, the entire liquid collection part 15 in the processing tank 11 is heated to 83 to 81°C by a heater 19 as a heating device, for example, by a sensor (
The temperature distribution in the liquid collecting section 15 is controlled using a branch plate 16. The liquid collecting plate 18 may be controlled at 81° C., and the temperature may be increased as it goes toward the lower stage, so that the temperature at the lowermost liquid collecting plate 18 and below is 83° C. In this case, the liquid with a high IPAfi degree can be evaporated above. Heater 19t - A plurality of separate heaters are disposed not only on the bottom side of the processing tank 11 but also around the outer circumference of the side wall on the lower side of the processing tank 11 in the vertical direction, and each heater is provided with a senna (thermocouple). It is best to control the temperature so that it has a certain temperature distribution.

Furthermore, although the case of drying treatment after washing the wafer with water has been described, it is also possible to perform cleaning (drying) of oil adhering to various members. In this case, in addition to IPA, fluorocarbons and I
A mixed solution of PA and Freon can be used.

[Application field]

In the above explanation, the invention made by the present inventor is mainly applied to the tilting treatment after water washing of semiconductor wafers in the LSI manufacturing process in the field of application, but the invention is not limited to this. For example, it can be applied to the drying process of fine patterned products and other parts after washing with water. In this case, IPA, a liquid substance with a lower boiling point than water, is used for steam drying of water.
It is effective to use e. Furthermore, the present invention can also be applied to, for example, cleaning or drying of pulp used in semiconductor devices, connectors, etc. to remove oil from machining. In this case, it is effective to use IPA, fluorocarbons, or a mixture of IPA and fluorocarbons.

In short, the present invention can be applied not only to drying after washing with water but also to washing (that is, drying) to remove oil.

[Brief explanation of the drawing]

Fig. 1 is a simplified configuration diagram showing an embodiment of the steam drying apparatus according to the present invention, and Fig. 2 shows the IPA concentration and boiling point in the liquid phase and the IP in the gas phase.
A characteristic diagram showing the relationship with the A concentration, and FIG. 3 is a simplified configuration diagram showing an example of a conventional steam drying apparatus. 11... Processing tank, 12... Cooling pipe, 13...
Cooling device, 15... Liquid collecting section, 16... Branch plate, 18
... Liquid collection plate, 19 ... Heater, 20 ... Drain pipe, 21 ... Valve, 22 ... Opening, 26 ... Lid,
27...Wafer, 28...Cartridge, 29...
- Supply pipe, 30...IPA. 31...liquid. Agent: Patent Attorney Katsuo Ogawa 11. .

Claims (1)

[Claims] 1. A cooling device is provided in the upper part of the processing tank, a liquid collection part is provided in the lower part of the processing tank, and a liquid substance having a boiling point lower than water is stored, and Steam drying, characterized in that a heating device is installed at the lower part of the tank to control the inside of the lower part of the processing tank to a predetermined temperature so that the concentration of the vaporized substance in the gas phase is equal to or higher than a predetermined value. Device. 2. The liquid collection section has a multi-stage configuration in which branch plates and liquid collection plates are arranged alternately in the vertical direction, so that the liquid flows down from the upper stage to the lower stage, and the evaporated substance rises. 2. A steam drying apparatus according to claim 1, wherein said steam drying apparatus is provided with a passageway that allows said steam to dry. 3. Claims 1 or 2 in which isopropyl alcohol, chlorofluorocarbon, or the like is used as the liquid substance.
Steam drying equipment as described in Section 1. 4. The steam drying apparatus according to any one of claims 1 to 3, which is configured so that liquid can be drained from the lower part of the processing tank. 5. The steam drying apparatus according to any one of claims 1 to 4, which is capable of forming a curtain of inert gas or N_2 gas at the upper end of the processing tank. 6. The steam drying apparatus according to any one of claims 1 to 5, wherein the processing tank is provided with a lid that can be opened and closed.