JPH10335299A - Wafer-drying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide with a simple configuration a wafer-drying device for drying an organic solvent which is used when drying a wet-washed wafer, with no leaking externally at all. SOLUTION: A sealed bath 30 is dropped from an upper portion, so that a wafer W that is dipped into an inner bath 21 of a washing bath 20 can be covered, and an inner space 31 that is sealed with water from the inner bath 21 is formed in the sealed bath 30. Then, N2 gas, containing mist-form isopropyl alcohol continues to be supplied to the inner space 31, the liquid surface of the inner space 31 is lowered due to the gas pressure, and the wafer W is dried by the Marangoni phenomenon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a wafer drying apparatus for drying a wafer after wet cleaning the wafer.

[0002]

2. Description of the Related Art As is well known, the characteristics of a semiconductor device are related to the amount of dust on the surface of a wafer. In order to obtain a semiconductor device having good characteristics, the amount of dust is preferably small. For example, dust remains on the surface of the wafer in each process such as etching and ion implantation. To remove the dust, the wafer is cleaned at the end of each process. There are dry cleaning and wet cleaning as the cleaning method, but the current mainstream is wet cleaning. In wet cleaning, after cleaning with a cleaning solution such as an acid, alkali, or organic solvent, rinsing with pure water to remove these is followed by air drying, leaving a watermark on the wafer and dust. More. In addition, the drying time becomes longer. That is, a semiconductor device having good characteristics cannot be manufactured. Therefore, the wafer is forcibly dried in the final step of the cleaning.

[0003] As a method of drying a wafer, conventionally,
There was a method in which the wafer was rotated at high speed and the surface water was blown off by centrifugal force.However, in this case, the blown water may hit the wall and re-attach to the wafer. A substitution method with a solvent which is hydrophilic and easily evaporates (having a low boiling point) is used. This means that when the wafer comes into contact with the vapor of the solvent, the vapor repeatedly dissolves the water adhering to the wafer and separates from the wafer, thereby drying the wafer. In addition, as is well known, isopropyl alcohol (hereinafter, referred to as IPA) is usually used, because a solvent having good hydrophilicity and high purity can be easily obtained.

[0004] As a method of gasifying IPA, first,
As shown in FIG. 7, there is a method in which a heater h disposed in an IPA (solvent) P sealed in a lower part of a drying container 6 of a drying apparatus is heated to 100 ° C. or higher. Therefore, various equipment (for example, providing a fire extinguisher) and an interlock must be provided in a place not shown for safety, and the entire drying apparatus becomes large. In addition, there is also a method of gasifying with an ultrasonic wave and spraying the gas on the wafer surface.

[0005] Recently, there is a drying method using Marangoni phenomenon, which is different from the replacement method using IPA. This method is performed as follows. As shown in FIG. 8, when the submerged wafer 2 is pulled up (moved in the direction of arrow B) and the atmosphere is filled with the IPA vapor G, the water and the IPA are water-soluble. G diffuses from the surface into water 3 as indicated by arrow A. In the region X of the water 3, since the layer is thin, the concentration of IPA is high, and in the region Y, the concentration of IPA is small because diffusion of the IPA into the water 3 proceeds. Therefore, due to this density difference, the region X
From the surface tension to the area Y, the wafer 2
Water on the surface 2a of the
It is carried from the area X to the area Y as indicated by the arrow F.
Therefore, the wafer 2 can be lifted only by lifting the wafer.
Drying with very little residual moisture is performed. In the above description, the wafer 2 is lifted.
The same drying is performed by draining the water 3 in which the water is flooded from below and lowering the liquid level 3a.

[0006] However, the drying container for performing the above-mentioned drying method using an organic solvent has an IPA gas atmosphere, which is conventionally sealed with a mechanical structure in any drying method. For example, the drying container 6 shown in FIG.
The cover (or cover) 5 is rotatable about a shaft 8, and an O-ring 7 is provided between the cover 5 and the drying container 6. Then, when drying, the lid 5 is disposed as shown by the dotted line, and the inside of the drying container 6 is sealed. However, despite the provision of the O-ring 7, for example, IPA leaks from a gap between the drying container 6 and the drying container 6. This IPA is flammable and easily vaporized, and is so toxic that it is stipulated as a dangerous substance in the Prevention Regulations for Poisoning of Organic Solvents, so if leaked, it may threaten the surrounding environment. In the semiconductor manufacturing process, a chemical reaction with other chemicals or the like may be considered. Therefore, even if IPA leaks from the drying container 6, it is necessary to adopt a configuration in which the IPA does not leak to the outside, or it is necessary to provide safety equipment (for example, a fire extinguisher or the like), thereby simplifying the drying device. could not.

In any of the drying methods using an organic solvent as described above, when the drying device is incorporated in the cleaning device,
That is, in the case of a multifunctional cleaning apparatus, it is necessary to provide an organic exhaust equipment for exhausting the organic solvent. Therefore, also in this case, there is a problem that the entire apparatus becomes large.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has been made in consideration of the above-mentioned problem, and has a simple structure in a wafer drying apparatus using an organic solvent, which does not leak the organic solvent to the outside. The task is to provide

[0009]

The above objects can be attained by providing a wafer drying apparatus for drying a wet-cleaned wafer in a water-sealed space using an organic solvent. By water sealing, the organic solvent in the atmosphere where the wafer is dried does not leak to the outside.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a wet-cleaned wafer is dried in a water-sealed space using an organic solvent used for drying. Since the organic solvent used for drying is soluble, it can be dissolved in the sealed water but does not leak out of the sealed water as a gas. That is, with a simple configuration, it is possible to prevent the organic solvent used for drying from leaking to the outside. Therefore, since a simple configuration is safe, large-scale equipment necessary for conventional safety measures is not required. In addition, if the organic solvent used for drying, which is soluble, is mixed with the water used for water sealing, this organic solvent is drained together with the water. Eliminating equipment, that is, organic exhaust equipment can be eliminated.

As a specific configuration of the drying apparatus, at least a water tank, a vertically movable drying tank disposed at the center of the water tank and having an opening below, and communicating with the inside of the drying tank, are provided. a structure in which the organic solvent has a gas supply pipe for supplying the N ₂ gas contained to be used in, so as to surround the wafer is wet-cleaned is immersed in the water of the aquarium, the drying tank to the tub By lowering, a water-sealed space is formed in the drying tank, and the N ₂ gas containing an organic solvent is supplied to the space to dry the space. At this time, alcohols can be used as the organic solvent, but it is preferable to use IPA which is a high-purity solution having good hydrophilicity and few impurities. Furthermore, for example, by the pressure of the N ₂ gas gas or IPA of IPA was contained, while gradually decreasing the liquid level of the water was a water seal, i.e. using the Marangoni phenomena described above prior art, Drying is also possible. Also, IPA
While supplying the gas to the inner space 31 sealed with water, the liquid level of the water may be lowered while drying the water from below the water tank. Incidentally, in this case, the use IPA is the N ₂ gas contained in the mist state, rather than that the N ₂ gas remains on the wafer W, and IP
The amount of A used can be reduced.

Further, if the water tank containing the water to be water-sealed is a washing tank, that is, if the water used for washing is also used for water-sealing the drying device, it is possible to save water. In addition, since the drying can be performed immediately after the wafer is submerged, the entire processing time can be shortened. Of course, as described above, one washing device and one drying device
In any case, since the organic solvent used for drying is dissolved in water and drained, exhaust equipment for discharging the organic solvent as a gas can be eliminated. That is, it is possible to incorporate a drying device into the cleaning tank with a dry configuration. Conventionally, when the cleaning tank and the drying device were integrated, the entire inside of the cleaning tank had to be in a gaseous atmosphere of IPA. However, in the center of the cleaning tank, water was sealed to cover the wafer. Since a space may be formed, the amount of IPA used for drying can be reduced.

The cleaning tank comprises an inner tank in which wafers are arranged, and an outer tank surrounding the outer periphery of the inner tank. If the upper end of the inner tank is made zigzag up and down, the cleaning tank will Since water flows uniformly from the inner tank to the outer tank, the flow of water does not stagnate in the inner tank. Also, by providing a current plate under the inner tank and providing a member for supporting a cassette containing wafers thereon, the flow of water in the inner tank can be further prevented. . Therefore, by providing such a structure, the wafer can be uniformly cleaned even when the drying device is integrated with the cleaning device.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a front sectional view of an apparatus 10 in which the drying apparatus of the present invention is incorporated in a washing apparatus. FIG. 2 is a plan view taken along the line [2]-[2] in FIG. Is a perspective view. This apparatus 10 includes a washing tank 20 for washing with water.
(For example, made of quartz glass) and a closed tank 30 (for example, made of quartz glass) provided at the center of the cleaning tank 20. The cleaning tank 20 includes an inner tank 21 in which an upper portion 21a is jagged, and an outer tank 22 provided so as to cover the outer periphery of the inner tank 21. This outer tank 22
Has a drain pipe 23 as shown in FIG. 1, receives water flowing from an upper portion 21 a of the inner tank 21, and flows to the drain pipe 23. The height of the inner tank 21 is 300 in this embodiment.
mm to about 400 mm. A pipe 25 is provided at the center of the bottom of the inner tank 21, and is connected to a drain pipe 26 and a water supply pipe 27. Furthermore, the inner tank 21
Inside, a current plate 12 having a large number of holes 12a is horizontally disposed, and a cassette mounting member 14 is disposed at the center of this upper surface. The cassette mounting member 14 is composed of two block-shaped members 14a each having a groove 14aa formed inside.

The cassette 13 is mounted by fitting the lower ends of the two side portions 53 into the grooves 14a of the cassette mounting member 14. The cassette 13 is made of, for example, a synthetic resin and includes two side portions 53 and a thin plate portion 13b connecting these two portions. Side 53
Is provided with a protruding portion 53a that protrudes in the horizontal direction. Also, the lower portion of the side portion 53 is inclined inward, and the inclined portion holds a wafer W (indicated by a dashed line instead of a dotted line in FIG. 3 to distinguish it from the cassette 13). Hole 53b is provided. The wall 13b is provided with a guide groove 53c for holding the wafer W in the hole 53b. The cassette 13 of this embodiment has 25 wafers W,
It can be stored.

On the other hand, the closed tank 30 has a box shape with an open lower surface, and is disposed at the center of the inner tank 21 of the washing tank 20. An exhaust pipe 17 having an exhaust valve 18 and a holding arm 15 are provided on the upper surface. The holding arm 15 is provided at its outer end with, for example, a threaded portion 15 in a locked state such as a ball screw.
a is formed. A screw member 32 rotated by a motor 33 is screwed onto the screw member 32. By rotating the motor 33, the hermetic tank 30 can be moved up and down via the holding arm 15. Further, a gas supply pipe 19 is connected to the holding arm 15, and a hole 15 b for communicating the internal space 31 of the closed vessel 30 with the gas supply pipe 19 is formed in the holding arm 15. I have.

The gas supply tube 19 is in communication with the atomization chamber 45 shown in FIG. 4, the atomization chamber 45, IPA
It is formed by a cover 43 attached to the outer peripheral portion of the nozzle member 42 of the supply device 40. This atomization chamber 45
Is further provided with a transfer pipe 44 to which N ₂ gas is supplied (this is
In order to increase the flow rate, which communicates diameter to have thinner) at the inlet of the atomizing chamber 45, further, the atomization chamber 45
Below the gas supply pipe 19, the remaining IPA
A hole 43a for returning the container to the container 41 is provided.
Incidentally, the hole 43a, the flows from the atomization chamber 45 into the container 41 allows, the flow from the container 41 into the atomization chamber 45 is connected to the bypass 47 provided with a check valve 46 for blocking. The tip of the nozzle member 42 protrudes inside the atomization chamber 45 . The nozzle member 42 is screwed into a container 41 in which liquid isopropyl alcohol I is sealed, and an inner hole 42a of the nozzle member 42 is a tube 41a provided in the container 41.
The inner hole is aligned. The container 41 has an air supply pipe 4
An isopropyl alcohol I is sprayed from the tip of the nozzle member 42 by the pressure of an inert gas (for example, N ₂ gas) supplied from the air supply pipe 48.
The exhaust pipe 4 having the relief valve 50 is provided in the container 41.
9 is connected. The relief valve 50 opens and releases the pressure when the pressure in the container 41 exceeds a certain fixed value.

Apparatus 1 incorporating the drying apparatus of the present embodiment
0 is configured as described above. Next, the drying method will be described.

First, as is well known, the wafer W is cleaned with a cleaning liquid such as an organic solvent or an acid. And FIG.
As shown in FIG.
In the center of the inner hole 21 of the cleaning tank 20,
The lower end of the side portion 53 is inserted into the groove 14 of the cassette mounting member 14.
a. At this time, the threaded portion 1 of the support arm 15
5 a is disposed above the screw member 32, that is, the closed tank 30 is located above the cleaning tank 20.

Then, the wafer W is washed with water by a known overflow method. That is, the water supply pipe 26
Ultrapure water is supplied from the
Is filled with water, water flows uniformly from the upper portion 21a of the inner tank to the outer tank 22 in the direction of arrow E. Further, the ultrapure water continues to be supplied, and the wafer W (including dust adhering to the cassette 13 and the cleaning tank 20) is washed by the flow of the ultrapure water upward in the inner tank 21. The ultrapure water flowing into the outer tank 22 at this time is drained through the drain pipe 23. Then, when the wafer W is sufficiently washed with water, the supply of the ultrapure water is stopped. Then, as shown in FIG.
The wafer W is immersed in the water V. The line indicated by the thin line H indicates the water surface at this time.

When the washing operation is completed, the motor
33 is operated and the closed tank 30 is lowered. This is
Open the air valve 18 to open the internal space of the closed tank 30.31From
Perform while evacuating air. And the closed tank 30 is the
As shown in FIG.
When descending to almost cover set 13, exhaust valve
Close step 18. Then, the internal space of the sealed tank 3031
Becomes a water-sealed space. It should be noted that the dashed line in FIG.
The line shown indicates the water surface H 'in the closed tank 30 at this time.
This is the same height as the water surface H "on the outer periphery of the closed tank 30.
It is.

Next, as shown in FIG. 4, an inert gas such as N ₂ is flowed from the exhaust pipe 48, that is, in the direction of arrow C, at a pressure of 0.5 kg / cm ² , for example. Increase internal pressure. By this pressure, the isopropyl alcohol I is ejected in the form of a mist into the atomizing chamber 45 through the inner hole of the pipe 41a and the inner hole 42a of the nozzle member 42. At the same time, N ₂ gas is supplied from the transfer pipe 44, that is, in the direction of arrow D, at a speed of, for example, 0.1 m / s or more. The supplied N ₂ gas mixes the mist M of IPA in the atomization chamber 45 and flows to the gas supply pipe 19. Incidentally, the IPA became mist in the atomization chamber 45 is not carried by N ₂ gas from the conveyor tube 44, the atomization chamber 4
The IPA that has accumulated below 5 opens the check valve 46 and is returned into the container 41 via the bypass 47.

That is, N containing mist M of IPA
_As shown in FIG. 1, _two gases are supplied from a gas supply pipe 19 to an internal space 31 of a closed vessel 30. Due to the pressure of the supplied gas, the water V in the closed tank 30 is pressed downward, that is, the water surface H ′ of the internal space 31 gradually decreases. Since the supplied IPA mist M has a lower specific gravity than the water V, a part of the mist M is deposited on the liquid surface H ′ to form a film t, but a boundary surface between the water V and the film t ( At the same level as the water surface H ′), the IPA diffuses into the water V. Therefore, as described above in the related art, the wafer W is dried from above as the liquid level of the film t falls due to the Marangoni phenomenon. At this time, the water in the inner tank 21 due to the lowering of the liquid level
As shown by an arrow E, it flows to the outer tank 22 and is drained through a drain pipe 23. Then, as shown in FIG. 6, the liquid level ta of the film t reduced by the gas pressure corresponds to the wafer W
When the pressure falls below the lower end of the gas supply, the supply of the N ₂ gas through the air supply pipe 48 shown in FIG.
That is, the drying of the wafer W is completed.

When the drying is completed, the water V in the inner tank 21 of the washing tank 20 is drained through a drain pipe 26 connected to the pipe 15. At this time, since the IPA supplied to the closed tank 30 is soluble, all of the water V
Melts in. Therefore, by draining the water V in the inner tank 21 of the cleaning tank 20, all the IPA supplied to the closed tank 30 is discharged. Then, after almost all the water in the closed tank 30 is drained, the motor 33 is rotated in a direction opposite to the direction in which the closed tank 30 was lowered, and the closed tank 30 is raised. Then, the cassette 1 containing the dried wafers W
Remove 3.

In this embodiment, since the wafer W is dried in the inner space 31 which is a water-sealed space, the IPA used for drying does not leak outside. The IPA supplied for drying is dissolved in the water V used as a water seal, and is discharged from the cleaning tank 20 together with the water V. Therefore, exhaust equipment for discharging IPA supplied for drying as gas is not required. Further, since the internal space 31 in which the drying is performed may have a volume enough to cover the cassette 13 in which the wafers W are stored, the amount of IPA supplied thereto can be reduced.

In this embodiment, since the mist-like IPA is diffused on the surface of the water while lowering the level of the water sealed in the water, the wafer is dried by the Marangoni phenomenon. Therefore, the effect obtained by drying using the Marangoni phenomenon is also obtained in this embodiment. In addition, since the Marangoni phenomenon is used, mist-like IPA instead of gaseous gas may be supplied to the internal space 31 of the sealed tank 30, and there is no further danger that the IPA leaks from, for example, a pipe joint. Further, since IPA is not a gas, the level of the liquid level in the closed tank 30 is reduced by the mist-like IPA.
Can be controlled by an increase in the pressure of the internal space 31 due to the N ₂ gas carrying the gas. Note that the mist-like IPA is
Since the wafer is transported by _two gases, the N ₂ gas does not remain on the wafer W, and the amount of IPA used can be reduced.

Further, in this embodiment, since the water tank to be water-sealed is the cleaning tank 30, that is, even if the drying apparatus and the cleaning apparatus are integrated, no exhaust equipment is required and the apparatus can be made compact. . Further, the cleaning tank 10 has an inner tank 21.
Since the upper portion 21a is zigzag up and down, when washing with water, water can be uniformly flowed from the periphery of the inner tank 21 to the outer tank. Therefore, the flow of water does not stagnate in the inner tank 21, and the water can be washed uniformly. Further, since the current plate 12 is provided in the inner tank 21, there is an effect that the flow of water becomes uniform.

Although the embodiment of the present invention has been described above, the present invention is, of course, not limited to this, and various modifications can be made based on the technical idea of the present invention.

For example, in the above-described embodiment, the mist-like IPA is transported by N ₂ gas.
May be supplied to the internal space 31 . However, in this case, in order to dry using the Marangoni phenomenon, the liquid level must be lowered by the pressure of the gasified IPA, so that the amount of IPA supplied for drying may increase more than in the above embodiment. There is also. Further, in the above embodiment, drying was performed using the Marangoni phenomenon, that is, drying was performed while lowering the liquid level.However, a water-sealed space was first created in the internal space, and gas was formed here. Is supplied, and drying by the replacement method described in the conventional example is performed.
An organic solvent such as IPA used for drying does not leak to the outside. The present invention can be applied to the case where drying is performed using an organic solvent other than IPA, other alcohols, acetone, xylene, Freon R113, or the like.

Further, in the above-described embodiment, the apparatus 10 in which the washing apparatus for performing the water washing and the drying apparatus can be performed in one tank is described. However, only the drying apparatus may be used, or the cleaning liquid (for example, Cleaning using an acid such as hydrochloric acid, sulfuric acid, hydrofluoric acid, or ammonia, or an organic solvent) may be performed. However, in this case, acid exhaust equipment for exhausting the washed acid is required.

Further, the details of the apparatus, for example, the shape of the cleaning tank 20 and the shape of the cassette 13 need not be limited to those described in the above embodiment, and various types are possible. Further, in the above embodiment, the rotation of the motor 33 is changed to a linear motion to move the closed tank 30 up and down. However, instead of this mechanism, the closed tank 30 may be moved up and down using a cylinder using air pressure. Good. Further, the material of the cleaning tank 20 and the cassette 13 does not need to be limited in the above embodiment. For example, PFA (fluorine compound) or vinyl chloride may be used as long as the cleaning tank is used. However, in order to perform the cleaning using the cleaning liquid in one tank, it is preferable to use quartz glass that is resistant to chemicals other than fluorine.

[0033]

As described above, according to the wafer drying apparatus of the present invention, since the drying is performed in the water-sealed space, the organic solvent used for drying leaks to the outside with a simple configuration. And drying can be performed.

[Brief description of the drawings]

FIG. 1 is a front sectional view of an apparatus in which a cleaning apparatus and a drying apparatus according to an embodiment of the present invention are integrated.

FIG. 2 is a plan view taken along the line [2]-[2] in FIG.

FIG. 3 is a perspective view of an apparatus in which a cleaning apparatus and a drying apparatus according to an embodiment of the present invention are integrated.

4 is a front sectional view of the IPA supply device for the N ₂ gas containing IPA used in the examples is supplied to the interior space of the present invention.

FIG. 5 is a front cross-sectional view of an apparatus in which a cleaning apparatus and a drying apparatus are integrated for explaining a drying method according to the embodiment of the present invention, and shows a state where washing with water is completed.

FIG. 6 is a front cross-sectional view of an apparatus in which a cleaning apparatus and a drying apparatus are integrated for explaining a drying method according to an embodiment of the present invention, and shows a state where drying is completed.

FIG. 7 is a schematic view of a drying apparatus in a conventional example.

FIG. 8 is a schematic diagram for explaining the Marangoni phenomenon.

[Explanation of symbols]

10 device, 12 rectifier plate, 13 cassette, 1
4 cassette mounting member, 15b hole, 19 gas supply pipe, 20 cleaning tank, 21 inner tank, 22 outer tank, 30 closed tank, 31 internal space, 32 ... screw member, 33 ... motor, 40 ... IPA supply device, 41
…… container, 44 …… conveyance pipe, 45 …… atomization room, 48 ……
Air pipe, I: Isopropyl alcohol, H ': Water surface, M: IPA mist, V: Water, W: Wafer.

Claims (8)

[Claims] 1. A wafer drying apparatus for drying a wet-cleaned wafer using an organic solvent, wherein the wafer is dried in a water-sealed space. 2. At least a water tank; a drier tank disposed in the center of the water tank and having an opening below and capable of moving up and down; communicating with the inside of the drying tank, and a gas of the organic solvent or the organic solvent. A gas supply pipe for supplying N ₂ gas containing, wherein the drying tank is lowered into the water tank so as to surround the wafer immersed in the water of the water tank, and _2. The wafer according to claim 1, wherein the space is formed, and the gas of the organic solvent or the N ₂ gas containing the organic solvent is supplied to the space to dry the space. Drying equipment. 3. The wafer drying apparatus according to claim 2, wherein said organic solvent is isopropyl alcohol. 4. The method according to claim 1, wherein the drying is performed while lowering the liquid level of the water by the pressure of the gas of the organic solvent or the pressure of the N ₂ gas containing the organic solvent. The wafer drying apparatus according to claim 3. 5. The wafer drying apparatus according to claim 4, wherein the N ₂ gas containing the organic solvent contains the mist of the organic solvent in the N ₂ gas. 6. The wafer drying apparatus according to claim 2, wherein the water tank is a cleaning tank. 7. The cleaning tank, comprising: an inner tank in which the wafer is arranged; and an outer tank surrounding the outer periphery of the inner tank, wherein the upper end of the inner tank has a zigzag shape up and down. The wafer drying apparatus according to claim 6, wherein 8. A rectifying plate is provided below the inner tank, and a member for supporting a cassette accommodating the wafer is provided on the rectifying plate. 8. The wafer drying apparatus according to 7.