JP3333830B2 - Method and apparatus for rinsing and drying substrates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for rinsing and drying a substrate for an electronic device requiring an ultraclean surface, and more particularly to a final rinsing and drying of a substrate after wet cleaning.

[0002]

2. Description of the Related Art Substrates for the electronics industry, such as semiconductor wafers and glass for liquid crystals, require cleaning in the device manufacturing process to sufficiently remove fine particles and chemical contamination on the surface. Since treatment with a liquid is most effective for removing fine particles, so-called wet cleaning is usually an indispensable cleaning method. Originally, wet cleaning mainly uses a chemical solution to remove chemical contaminants. From the viewpoint of productivity, dozens of substrates are often placed in a carrier to perform cleaning processing. At the same time, single-wafer processing has been attempted. After this chemical treatment, rinsing with ultrapure water is generally performed, and drying completes the cleaning process.

[0003] The degree of cleanliness of a substrate required in an electronic device manufacturing process is extremely high, and the degree of cleanliness must be sufficiently maintained even in drying. Particularly in the case of semiconductor devices, silicon wafers are required to have extremely strict cleanliness for fine particles and harmful metal impurities.
Conventionally, two methods are the mainstream as a drying method satisfying such requirements.

[0004] One is a centrifugal drying method in which a carrier is rotated at a high speed so that the substrate surface becomes a rotating surface, and attached water is blown off by centrifugal force. Another is an organic solvent that is hydrophilic and has a low latent heat of vaporization (usually isopropyl alcohol is used).
Is a vapor drying method in which the solvent is condensed on a substrate and falls on a substrate to displace and remove the attached water. After dehydration, drying is performed by heating with a solvent vapor. The former is more productive,
Although desirable in terms of economy, the static electricity may cause secondary contamination due to scattered mist or dust particles in the apparatus, and the mechanical stress may cause chipping at the wafer periphery, so semiconductor wafers This is disadvantageous for substrates having a tendency to have a large diameter. The latter is advantageous in terms of recontamination and mechanical stress because it does not operate at high speed and hardly generates static electricity.However, it requires the use of a high-purity solvent, which is a disadvantage in terms of cost and management, and reduces hydrophilic solvent vapor. There is a problem in terms of common ignition hazards. Further, since the solvent molecules are adsorbed on the substrate surface, it cannot be said that a clean surface is always obtained.

Therefore, a drying method using only water as a solvent and not having to operate the wafer at a high speed has been attempted. As one of the methods, there is a method called a hot water pulling method in which a substrate surface is gradually lifted vertically from warm water in order to increase the drying speed and lower the surface tension of the liquid, and the substrate is separated from the water surface and dried at the same time. In addition, the clean gas that has passed through a pleated high-performance dust filter such as a HEPA filter is heated and sprayed almost parallel to the vertical substrate surface pulled up from the rinsing water. Then, there is a so-called hot-air drying method of evaporating and drying this.

[0006]

The hot water pulling method is advantageous in drying a large-diameter substrate in that mechanical stress on a wafer is small, and has no problem in safety. However, although this method has a slight track record in the semiconductor field, it has hardly been put to practical use. There are difficulties in maintenance, such as being susceptible to vibration and difficult to manage bubbles and fine particles in warm water.

In the hot water pulling method, it is necessary to carry out rinsing with hot ultrapure water for a sufficient amount of time for a sufficient amount of time in order to obtain a satisfactory clean surface with few fine particles. However, after an alkali treatment such as ammonia-hydrogen peroxide cleaning that is effective for removing fine particles, a very small amount of heavy metal, which is present even in ultrapure water, is immersed in room temperature water in a wafer immersed in heated ultrapure water. The present inventor has found that it is easier to adsorb than the case where it is. For example, when 0.1 ppb of Fe labeled with the radioactive isotope ⁵⁹ Fe is added to ultrapure water at 50 ° C., and the silicon wafer after the alkali treatment is immersed for 10 minutes, the adsorption of Fe on the surface becomes 3 × 10 ¹⁰ atoms /. It has been confirmed by the tracer method that it reaches cm ² . This amount cannot be ignored in the semiconductor device manufacturing process. Fe in ultrapure water can usually be controlled to 0.01 ppb or less,
General purity standard for metal elements in ultrapure water production equipment is 0.1 pp
b, there is no guarantee that the Fe concentration will not degrade to about 0.1 ppb. Cu, Al, Zn, etc. in ultrapure water are F
E tends to be adsorbed on the silicon surface more or less than e. Thus, immersion rinsing with high-temperature water is more likely to cause chemical contamination than room-temperature water.

[0008] The method of removing water adhering to an object to be dried by blowing hot air is one of the most common drying methods. However, this method is rarely used for drying in semiconductor wafer cleaning. Although semiconductors have a very high requirement for cleanliness against particulate contamination, conventional hot-air dryers have a quarter-micron level called haze even when a ULPA filter with higher performance than HEPA is used to remove gas. Ultrafine particles are frequently generated, and even stripe contamination that can be seen with the naked eye is likely to occur. Such contamination is reduced by increasing the speed of the hot air to be blown, but at least 8 to 1 to obtain this effect.
A wind speed of 0 m / s is required. However, HEPA filters were originally made for clean rooms, and the optimal wind speed was 0.5
１1 m / sec. 8 or more orders of magnitude faster than this
When a gas flow with a wind speed of 10 m / sec is passed for a long time, HE
Since the PA filter has a folded structure of a thin fiber cloth, the reliability of dust removal is reduced. Further, such a filter structure may cause a leak when there is a sudden change in wind pressure, and thus needs to be continuously used. Then, the amount of gas used becomes enormous.

Further, according to the study of the present inventor, even if the flow rate of the hot air is 10 m / sec, unless the gas is high-purity nitrogen or oxygen using liquefied gas as a raw material or air mixed with these gases, the fine particles on the wafer surface may be used. Levels cannot be satisfactorily reduced. The air could not be used for ultra-clean hot air drying, no matter how high-performance the filter was. Such a drying method that requires a large amount of high-purity gas is difficult to put into practical use in terms of economy.

Accordingly, the present invention provides a method of spraying a gas having a high quality of gas cleanliness in immersing and rinsing a substrate to which a chemical has adhered, such as after a chemical cleaning treatment, with a liquid at room temperature and then blowing and drying the gas. It is an object of the present invention to provide a drying method and apparatus capable of obtaining a surface with sufficient cleanliness for the electronic industry even if the amount of gas sprayed is small. Normally, the surface that is well wetted by the rinsing liquid is likely to produce striped stains with hot air drying,
In particular, it enables the substrate to be dried with good cleanliness for such a substrate.

[0011]

In order to achieve the above-mentioned object, the present invention provides a method for contacting a substrate with a rinsing liquid, and then bringing the substrate into the air from the liquid surface of the rinsing liquid while the substrate surface is vertical. The drying method of the substrate, in which a high-purity gas flow is blown parallel to the substrate surface and along the liquid surface at the time of the lifting, and the liquid surface of the rinsing liquid in contact with the leeward portion of the substrate A method for drying a substrate after rinsing, comprising adjusting the flow rate of the high-purity gas flow and the rising speed of the substrate so that the substrate rises.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Substrates to be dried in the present invention include semiconductors such as silicon and gallium arsenide, glass for liquid crystal devices, glass for photomasks, and synthetic resins for circuit boards, etc. The entire substrate includes a cleaning stage in the production process.

Rinse liquid Ultrapure water is generally used as the rinse liquid. In the present invention, since the liquid surface needs to rise at the downwind portion of the substrate as described above, an organic solvent having a low surface tension such as isopropyl alcohol, methyl alcohol, acetone, dichloromethane, and freon is used for a substrate that is poorly wetted with water. Among them, a solvent having a low boiling point, low toxicity and low flammability, such as dichloromethane, is preferable. Alternatively, rinsing ultrapure water is replaced with an organic solvent rinsing liquid and used. Specifically, for example, after rinsing with ultrapure water, the ultrapure water is once replaced with methanol, and then methanol is replaced with a dichloromethane rinse solution. The use of organic solvents is generally disadvantageous in terms of economy, but by attaching a distillation purifier to the drying equipment used, the organic solvent can be recycled and used while distilling and purifying, reducing the economical difficulties. it can.

The purity of the rinsing liquid at the time of lifting the substrate must be sufficiently purified to such an extent that no harmful amount of residue or adsorption is produced on the substrate for electronic device production. Speaking of ultrapure water, it can be used if it has a purity that satisfies the 1986 SEMI standard. But,
Since there is a possibility of contamination from the piping in the apparatus, it is desirable to check the residue due to the evaporation and drying of the droplets on a high-purity substrate in advance to check the cleanliness of the environmental atmosphere before use.

According to the method of the substrate elevation and high purity gas flow present invention, by adjusting the velocity of elevated speed and a high purity gas flow of the substrate, leeward portion of the substrate that is being raised parsley from the rinsing liquid surface So that swelling of the liquid surface occurs. That is, the raising speed and the wind speed of the high-purity gas flow are controlled using the occurrence of the bulge as an index. The rising of the liquid surface occurs, for example, when a standard-shaped silicone wafer having a diameter of 6 inches and a thickness of 650 μm is lifted from ultrapure water, if the rising is too large, for example, if it exceeds 50 to 60 mm, If the surface rises while the surface is wet, surface contamination is likely to occur. If the surface is too small, it becomes difficult to adjust the lifting speed and the air current. Therefore 10-30
mm is preferable, and particularly preferably 10 to 20 mm.

As described above, as the rinsing liquid, a solvent with good wettability of the substrate is selected, so that if the substrate pulling speed is too high or the blowing air flow speed is too low, the liquid surface rises too large. Then, the substrate is separated from the surface of the rinsing liquid without being completely dried, and drying is left to natural drying in an atmosphere. As a result, the cleanliness of the dried part decreases. On the other hand, if the lifting speed of the substrate is too high, the fine particles in the rinsing liquid are likely to remain on the substrate surface. Because it is actually extremely difficult to completely remove the fine particles in the rinsing liquid, some fine particles exist, but most of the fine particles exist on the liquid surface due to surface tension. This is because the rinsing liquid rises on the substrate surface as a liquid film due to surface tension, but fine particles accompany the liquid film. However, in the present invention, such a disadvantage does not occur because the pulling speed of the substrate is controlled as described above. On the other hand, if the pulling speed of the substrate is too low, productivity is undesirably reduced.

In order to realize such an appropriate pulling speed, in the present invention, high-purity gas is sprayed so as to crawl on the liquid surface, and vaporization on the substrate surface which has passed through the liquid surface and appeared in the gas phase is performed. Facilitate. As the high-purity gas to be blown, it is practically possible to use high-purity nitrogen or oxygen using a liquefied gas as a raw material or air mixed with these. Because, as described above, the swelling of the liquid surface in the leeward part of the substrate is used as an index for adjusting the flow velocity of the high-purity gas flow,
This is because the amount of the high-purity gas may be much smaller than the conventional hot air drying method. However, it is most preferable to accelerate a part of the circulating clean air flow described later and guide it as the high-purity gas flow for use in terms of running cost.

If the high-purity gas stream blown onto the substrate is heated, the drying of the substrate can be accelerated, and the rise of the liquid level in the leeward portion of the substrate is very small and good. The temperature of the gas flow is preferably from room temperature to 200 ° C. depending on the type of the rinsing liquid. More specifically, when the rinsing liquid is ultrapure water, the temperature is preferably from 70 ° C to 100 ° C. When the rinsing liquid is a low-boiling volatile organic solvent such as dichloromethane, the temperature is preferably from room temperature to The boiling point of the organic solvent is preferably used.

When water having a high heat of vaporization is used as the rinsing liquid, if the high-purity gas stream used for spraying is heated, the liquid film crawling from the liquid surface onto the substrate even when the substrate lifting speed is increased. Can be minimized to provide a visually unobservable range. According to the method of the present invention, optimization of the pulling speed of the substrate, the wind speed of the high-purity gas stream, and the temperature thereof is performed so that the liquid level rises in the leeward portion of the substrate with an appropriate size. Can be performed visually easily.

Preferred Embodiment In the case where the substrate after drying by the method of the present invention is put into a step where the adsorbed water remaining on the surface adversely affects, for example, the case where it is put into a polycrystalline silicon film growth step In order to ensure dehydration by drying, when the substrate is separated from the liquid level, the substrate is subsequently moved to, for example, 110 ° C.
Heating at 200 ° C. is effective.

In the method of the present invention, it is desirable that the rinsing liquid moves on the liquid surface in the direction of the high-purity gas flow. This is because, in the method in which the rinsing liquid is simply overflowed from the liquid tank, the surface of the liquid rises in the center of the rinsing tank due to surface tension, and fine particles collect there and do not overflow. However, when the rinsing liquid moves as described above, the fine particles on the liquid surface flow out, so that the concentration of the fine particles on the liquid surface is kept at the minimum level, and the adhesion of the fine particles to the substrate is suppressed.

The method of the present invention further comprises a filter for removing an acidic gas, a filter for removing a basic gas, an activated carbon filter for removing organic substances, and a flow rate passing through a purification system comprising a filter for removing dust. 0.2
It is preferably carried out in a stream of clean air circulating at ~ 2.0 m / sec.

As a filter for removing an acidic gas,
Pleated structure with low pressure loss made of an anion-exchange fiber cloth or an activated carbon impregnated cloth impregnated with an alkali.A filter for removing basic gases is a cation-exchange fiber cloth or activated carbon impregnated with zinc chloride, etc. A pleated structure made of impregnated cloth with low pressure loss, an activated carbon filter for removing organic substances, a pleated structure made of activated carbon impregnated cloth or activated carbon fiber cloth with low pressure loss, and a HEPA filter for dust removal
Alternatively, an ULPA filter can be used. Since these filters having a small pressure loss can be used in series and circulated, it is possible to create a clean air flow of each gas molecule of 0.1 ppb or less, and the present invention is most effective under such a clean environment. Demonstrate. The reason is as follows.

A typical acid cleaning for making the surface of a silicon wafer hydrophilic is hydrochloric acid / hydrogen peroxide cleaning agent (SC-2, a standard composition is 1 volume of hydrochloric acid + 1 volume of hydrogen peroxide). +
(5 volumes of water) and a sulfuric acid / hydrogen peroxide detergent (standard composition is 1 volume of sulfuric acid + 3 volumes of hydrogen peroxide). The present inventor washed the former hydrochloric acid with a detergent labeled with the radioactive isotope ³⁶ Cl, then rinsed it with 18 MΩcm ultrapure water for 15 minutes, dried it, and absorbed it on the surface from the amount of radioactivity remaining on the wafer. When the amount of hydrochloric acid was calculated, it was found to be about 5 × 10 ¹⁴ molecules (30 ng) / cm ² . Also, when the latter cleaning agent was washed with a cleaning agent labeled with radioactive isotope ³⁵ S, and similarly rinsed with ultrapure water, it was found that it also had an adsorbing power of 10 ¹⁴ molecules (20 ng) / cm ² or more. Was. Ammonia / hydrogen peroxide cleaner (SC-1), which produces a strong hydrophilic surface with a typical alkali cleaner, has a standard composition of 1 volume of ammonia + 1 volume of hydrogen peroxide + 5 volumes of water ) But also 10 ¹⁴ molecules (10 ng) / cm ²
The occurrence of the above adsorption was found by ultrapure water elution and ion chromatography analysis. On the other hand, in clean rooms of ordinary semiconductor factories, fine particles are thoroughly cleaned, but in some places acidic molecules such as sulfuric acid, hydrochloric acid, and nitrogen dioxide reach about several tens of ppb, and ammonia and Alkaline molecules such as amines can range from tens of ppb to more than 100 ppb in some locations. Organic molecules also reach tens of ppb. That is, such molecules are present in tens to hundreds of ng in 1 L of atmospheric air. Therefore, if hot air drying is performed on the substrate after rinsing as described above in such an atmosphere, molecules in the hot air can very easily dissolve into the liquid film immediately before drying on the substrate, and the acid or ammonia remaining on the surface can be dissolved. Also reacts with. As the liquid dries, the solute crystallizes on the surface as fine particles of salt.
Some of the organic substances in the atmosphere should adsorb such fine particles as nuclei, and the fine particles become even larger.
By the way, wafer-like contamination called haze is a collection of ultra-fine particles at the quarter micron level. Assuming that these fine particles are 0.1 μm diameter spheres of a salt having a specific gravity of 2, the weight is 10 ⁻⁶ ng. Therefore, it is considered that a large amount of fine particles are generated by the above-described mechanism, and this haze occurs.

Using a chemical filter as described above,
Drying is performed in an atmosphere in which molecules of acids, alkalis, and organic substances have been removed to 0.1 ppb or less, or in a high-purity gas of the same level made from a liquefied gas. Does not happen. Therefore, a substrate having a clean surface with a low concentration of fine particles can be obtained.

The rinsing and drying of the method of the present invention described apparatus above, for example, a means for contacting the substrate with the rinsing liquid, from the liquid surface of the holding the substrate with the substrate surface is vertical and the rinse liquid Means for gradually lifting into the gas phase, means for spraying a high-purity gas flow parallel to the substrate surface and crawling the liquid surface of the rinsing liquid during lifting of the substrate, and at least, A substrate rinsing and drying apparatus having a container means for isolating the gas phase on the liquid surface, which is brought into contact with the substrate raised, from the external environment and supplying a purified gas to the gas phase. be able to. The apparatus may further include a transport unit that receives the dried substrate and transports the substrate out of the apparatus, and / or a unit that grips the transported substrate and loads the substrate onto a required transport carrier.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The method and apparatus of the present invention will be specifically described below with reference to the drawings. All the examples show the case of single-wafer processing. In the first embodiment, a batch system for processing a plurality of substrates is also possible, but the drawing becomes complicated because the holding device of the substrate is changed to a plurality of substrates, and the structure is not related to the essence of the present invention. This is because Examples 2 and 3 are dedicated to single-wafer processing. In the following, a vertical cross section viewed from a direction perpendicular to the substrate surface is referred to as a front cross section, and a vertical cross section viewed from a direction parallel to the substrate surface is referred to as a side cross section. To facilitate the description of the direction of substrate movement, the direction of the high-purity gas flow is X, the opposite direction is X ', the forward direction perpendicular to the substrate surface is Y, and the opposite direction is Y', upward. Is Z, and the direction in which Z is set is Z ′.

Embodiment 1 FIG. 1 shows an example of a rinsing / drying apparatus according to the present invention. After the chemical solution treatment for obtaining the hydrophilic surface such as the SC-1 treatment of the standard composition is completed, the silicon wafer stored in the ultrapure water after the ultrapure water rinse is finished is further rinsed using this apparatus. An example of drying and drying will be described. FIG.
FIG. 1B is a front sectional view of the device, and FIG. 1A shows a direction in FIG. 1A. FIG. 2B is a side cross-sectional view of the device as viewed in the X ′ direction from the X side in FIG. 1B, and FIG. 2A shows the direction in the device. An automatic mechanism is desirable for loading the wafer into the apparatus, but it may be manual.

This apparatus includes a quartz glass tank 1 as means for bringing the substrate into contact with a rinsing liquid, that is, rinsing means. This is suitable for processing a large number of wafers at the same time, that is, for batch processing, in which a immersed wafer breaks down an overflowing liquid level, moves to an upper gas phase, and is dried in the process. . The liquid is supplied from below the tank, and an auxiliary liquid supply port is provided near the liquid surface so that the liquid surface can flow quietly along the substrate surface.

More specifically, each tank is a tank filled with ultrapure water 2 for performing final overflow rinsing, and a portion of one of the side walls 3 is slightly cut so that only the ultrapure water is supplied therefrom. It is made to overflow. This tank 1 has a first supply means 4 of ultrapure water at the bottom, and the liquid flows in the direction X over the entire surface of the rinsing liquid 2 above the side wall 5 facing the side wall 3 (just below the upper end). As described above, there is the second ultrapure water supply means 6. In this embodiment, the first ultrapure water supply means 4 is introduced from the outside of the tank 1 and comprises a pipe having holes 7 formed at equal intervals in the upper part. It is joined to the upper part of the housing and is constituted by an open pipe.

The rinsed wafer is loaded into the tank 1, but the loading means is not shown. Such a loading mechanism must be an automatic mechanism. Wafer 6
In this embodiment, a carrier 9 for loading a wafer 8 is provided as a means for holding the wafer so that its surface is vertical and lifting it from the rinsing liquid. The carrier 9 comprises a wafer 8
And a handle 11 for supporting the gripper 10 so that its surface is vertical. The end 11 a of the handle 11 is connected to a column 13 that is driven up and down by a vertical movement drive mechanism 12. The carrier 9 can be raised and lowered arbitrarily by the vertical movement drive mechanism 12. This device includes:
Means for receiving and transporting the wafer 8 lifted in the Z direction by the vertical movement drive mechanism 12 from the carrier 9 is provided. The means comprises a clamping jig 14 and a driving mechanism 15 therefor.
(Omitted in FIG. 1B). The jig 14 has, in this embodiment, an arc-shaped concave pinching surface 16 that matches the circumference of the disk-shaped wafer 8, which pinches and holds the wafer 8, and further holds the wafer 8 in the Z and Z ′ directions and X direction. It can move freely in the direction and the X 'direction.

Above the quartz glass tank 1, there are provided hoods 17 each having a wall made of a quartz glass plate and having upper and lower portions opened. Are joined. Furthermore, the handle 11 of the carrier 9
A slit 18 is provided on the side wall in the Y 'direction so that the column 13 for supporting the wafer can be vertically moved by the power of the movement driving mechanism 12, and the slit 19 is similarly formed so that the wafer gripping means 14 can be vertically moved in the vertical direction. Direction side wall. Further, according to 15, a hole 20 is opened in the side wall in the X direction so that the holding jig 14 holding the wafer can take out the wafer from the hood 17, and closed with a fluorine resin window cover 21 when unnecessary. Have been.

The means for blowing the high-purity gas stream is, for example,
A gas outlet is provided at a position slightly higher than the liquid surface in a direction parallel to the substrate surface and facing upwind. It is desirable to provide a vertically long slit at the outlet so that the gas flow to be blown out becomes laminar. By such spraying means,
A thick laminar flow along the substrate surface can be created to crawl the liquid surface. In the case of this embodiment, the quartz hood 17
A glass pipe 22 is connected and opened at a lower portion of the side wall in the X ′ direction to introduce a high-purity gas flow.
An exhaust port 24 for the gas flow is opened at a position opposite to the gas outlet on the side wall in the X direction, and a cover 25 for the exhaust port is provided. In addition, outlet 2
3 has a plurality of slits 2 in the vertical direction to make the air flow laminar.
3a is provided.

All of the above mechanisms are housed in an air return type clean booth equipped with the following filter groups. That is, above the upper opening of the hood 17, K
An activated carbon-containing cloth filter impregnated with I and KOH, a pleated cation-exchange fiber cloth filter, and a pleated-type activated carbon-containing cloth filter are stacked in this order from the top, and air from which gaseous impurities have been removed by these is disposed below. The fine particles are supplied to an ULPA filter 26 for removing fine particles. The air that has passed through these filters flows through the inside and outside of the above-described mechanism in a closed space in the clean booth, and most of the air returns to the filter group.

After the apparatus was constructed as described above, the air in the apparatus was analyzed by impinger ion chromatography. It is harmful because Cl, SO ₂ , NO ₂ , SO ₄ and NH ₃ are all less than 0.1 ppb and the contact angle of water drops hardly changes even after leaving the hydrophilic wafer in the apparatus for 24 hours. After confirming that the organic matter was at a harmless level, the apparatus was operated.

A double-tube quartz glass gas heater (not shown) is directly fused to the pipe 22 forming the gas outlet 23. The gas heater has a double tube structure made of quartz glass, has a heating element in an inner tube, and heats a gas passing between the inner tube and the outer tube. After heating high-purity nitrogen for semiconductor device production through a precision ceramic dust filter for 0.01 μm size with a gas heater, it can be introduced into the hood from the gas outlet 23. The gas thus blown flows in parallel with the surface of the wafer 8, that is, along the liquid surface in the X direction.

Hereinafter, an example of wafer drying by this apparatus will be described. After the wafer is set in the rinsing tank 1 as shown in FIG. 1A and the final rinsing is performed, ultrapure water is supplied from the second ultrapure water supply means 6 to the rinsing liquid 2 over the entire liquid surface.
It is supplied to such an extent that the movement in the direction can be visually confirmed. After this, with the numerical values confirmed in the preliminary wafer pull-up test,
Gas flow (put a flow meter in front of the filter),
Set the temperature of the gas heater and the pulling speed of the wafer. When pulling up a spare wafer, wafers cleaned by the same method,
In this case, a wafer of SC-1 treatment is used, and when the wafer is pulled up, that is, when the wafer breaks up and rises, FIG.
As shown in (b), the liquid level 26 is 2
Find the condition that excites like 7. A P (100) wafer having a diameter of 6 inches and a thickness of 650 μm was prepared using standard composition SC.
The wafer is cleaned at 70 ° C. for 10 minutes under the standard conditions of −1. In this apparatus, when the heater set temperature of the gas heater is 300 ° C. and nitrogen is 30 L / min, the pulling speed is 5 to 13 cm. / Min, a favorable swell was obtained.
Therefore, the lifting speed was set to 10 cm / min, and the heater temperature was set to 30 cm / min.
At 0 ° C., the gas flow rate was 30 L / min. In this case, the gas temperature at the outlet 23 was 90 ° C.

At the same time as the pulling of the wafer is started, the driving mechanism 15 is operated to open the wafer holding jig 14 and lower the jig 14 to the lowest position (the position of the virtual line 14a). When the center of the wafer reaches the intermediate point between the two clamping devices, the lifting of the wafer carrier 9 is stopped, and the driving mechanism 1 is immediately stopped.
5 is moved and the edge of the already dried wafer 8a is sandwiched by the sandwiching jig 14, and pulling is performed continuously at the same speed as the carrier rising speed. When the wafer has separated from the liquid surface, the ascent is stopped for 20 seconds, the water droplets remaining at the lower end of the wafer are surely dried, and then the jig 14 is again moved to the highest position (the jig 14 is shown by a solid line, and the wafer is shown by a virtual line 8a) Position). By opening the window 21 and moving the jig 14 in the X direction, a dried wafer can be taken out.

The wafer thus dried was similarly subjected to SC-1 cleaning and then compared with a wafer surface (comparative example) which was centrifugally dried in a conventional type clean room equipped with only an ULPA filter. Oblique light inspection in a dark room showed no significant difference between the two in haze and fine particle concentration. The wafer of this comparative example was immersed in ultrapure water, and the solution was subjected to ion chromatographic analysis. As a result, SO ₄ ions were found to be 3 × 10 ¹³ / c on the wafer surface.
5 × 10 ¹² / cm ^{2 of} m ² and Cl ions were detected, and as a result of analyzing this solution with a TOC (total organic carbon content) analyzer, 100 ng / cm ² or more was detected. In the example wafer, all ions have a detection limit of 5
× 10 ¹¹ / cm ² or less, and TOC was 1 detection limit
0 ng / cm ² or less.

Embodiment 2 When the diameter of the Si wafer is increased from 8 inches to 12 inches and further to 16 inches, the cleaning must be performed on a single wafer. In this embodiment, a single-wafer-only mechanism is provided, since a single-wafer is naturally preferable for drying. Also in this case, the wafer rises by breaking the liquid surface, and the mechanism for receiving the wafer is the same as that of the first embodiment, so that the description of the mechanism and operation is omitted. Therefore, the description mainly focuses on how to raise the liquid surface and the rise of the wafer. FIG. 3B is a side sectional view of this portion, and FIG. 5B is a plan view from above. The directions in each case are shown in FIGS. 4 (a) and 5 (a).

A slit-shaped opening 42 through which the wafer 8 can pass is provided in the center of the bottom of the quartz glass square tank 41 having a depth of 20 mm.
A plurality of ultrapure water supply ports 43 for rinsing are provided at the bottom of the quartz tank.
To combine. The wafer 8 is rinsed with the ultrapure water 49.

The wafer 8 is placed in the carrier 45, and after the chemical solution treatment and rinsing are completed, a vertically extensible column 47 (at the start position, which is at the lowest position) connected to a mechanism 46 for vertically moving the carrier 45 up and down. Place on top and secure.
In the X 'direction, a gas outlet 48 for creating a gas flow creeping on the liquid surface
Is provided. A high-purity gas stream 50 parallel to the wafer 8 is blown out from the blowout port 48.

Other than what has been described here, that is, the sandwiching jig and its driving mechanism, air circulation system, and gas heating / filter mechanism are all the same as those in the first embodiment. However, a blower was provided in front of the ceramic filter to take in the air immediately below the ULPA filter and send it to the outlet. At this time, a test was conducted in which a small water droplet was placed on a clean wafer and dried with this heated gas within 1 minute, and it was previously confirmed that no residue was left.

Hereinafter, an example of rinsing and drying by this mechanism will be described. After setting the wafer rinsed for 10 minutes at 70 ° C. with SC-2 of standard composition and rinsed with ultrapure water for 10 minutes on the support 47, ultrapure water was introduced from all the supply ports 43,
The ultrapure water 48 in the quartz tank overflows slightly from the edge almost uniformly. If the width of the slit 42 is 3 mm and the wafer is 8 inches, the total amount of ultrapure water introduced from all supply ports may be about 5 L / min. The liquid level is kept almost horizontal,
Most of the supplied ultrapure water falls from the slit 42,
It flows along the hydrophilic wafer surface and the final rinse proceeds.

As in the first embodiment, under the condition that the liquid can swell in the downstream part of the wafer surface, hot air is made to flow from the outlet 48 to the liquid surface, and the wafer is pulled up. After the wafer leaves the liquid surface, the same operation as in the first embodiment is performed. When the rinsed and dried wafer surface was compared with the rinsed and dried wafer surface in Example 1 by oblique light inspection in a dark room, the haze and the concentration of fine particles were clearly inferior to those of Example 1. I was So 1M
The ultrapure water shower nozzle to which the Hz ultrasonic wave was applied was provided below the bottom of the quartz glass tank, and the cleaning treatment was added for 2 minutes before the final rinsing. As a result, the result seemed to be slightly better than that of Example 1. .

Next, by the same surface analysis as in Example 1,
The NH ₃ ions were compared between the wafer surface which was centrifugally dried in a conventional type clean room after the SC-2 cleaning and the wafer surface of the present example. 5 × 10 ^{12 for} centrifugally dried wafers
/ Cm ² , but in this example, the detection limit of 5
× 10 ¹¹ / cm ² or less.

Embodiment 3 As an example of a case where surface adsorption of water is not desirable, a TFT of a flat panel display in which chlorofluorocarbon cleaning is most effective is used.
In the washing before the polyimide coating in the cell process, the following washing was performed instead of CFC. FIG. 6B is a bird's-eye view from above the rinsing means of the used apparatus.
(A) shows the direction in that. The quartz glass tubes 61 and 62 whose both ends are sealed have liquid ejection holes 63 in a row on the side facing each other, and a liquid supply tube 64 is connected thereto.
Liquid is introduced as shown at 6. The TFT substrate 67 was allowed to pass from below at a distance of several mm from the ejection holes between the opposing ejection hole arrays. Further, a gas outlet 65 was provided in the X 'direction.

The substrate before polyimide coating immediately before the cleaning with Freon was set on a large-sized one similar to the up-and-down mechanism of Example 46, and was positioned below the center of the gap between the quartz tubes. A non-flammable distillate of dichloromethane which was microfiltered was used as a supply liquid, and was discharged from the jet port to rinse the substrate and start lifting the substrate. When the top surface of the substrate reaches the position of the quartz tube,
The jet flow is slightly wavy, but forms a substantially horizontal liquid level with the substrate surface. Here, high-purity nitrogen at room temperature
The substrate was raised at a flow rate of 0 L / min while adjusting the rising speed so that a slight bulge could be observed on the leeward side of the substrate. Since this example was a preliminary experiment, at the final stage of the ascent, the substrate was supported by a pinching instrument and manually lifted.
The thus dried product was subjected to steps subsequent to the application of polyimide, and as a product, white spots, black spots, image unevenness, and the like were compared with those of the CFC-washed product, but there was almost no difference.

[0049]

According to the present invention, since there is no mechanical stress, there is little possibility of damage. Since the liquid used is at room temperature and the flow rate of the high-purity gas is relatively low, it is economical and the maintenance of the apparatus is easy. In addition, there is no danger of steam cleaning of flammable organic solvents. In addition to low particulate adhesion levels comparable to conventional major drying methods, surface organic and non-metal ion contamination levels can be significantly reduced compared to the prior art. Therefore, it is possible to respond to the trend of sophistication of electronic devices and enlargement of the substrate area, and the practicality is high.

[Brief description of the drawings]

FIG. 1 (a) shows the direction in (b), and FIG. 1 (b) is a front sectional view of the device of the present invention.

2 (a) shows the direction in FIG. 2 (b), and FIG. 2 (b) is a side sectional view of the same device.

3A is a diagram illustrating a direction in FIG. 3B, and FIG. 3B is an explanatory diagram illustrating a wafer rising from a rinsing liquid level and a swelling state of the liquid level.

4 (a) is a front sectional view showing a direction in (b), and FIG. 4 (b) is a front sectional view showing a state in which a wafer in another apparatus of the present invention is brought into contact with a rinsing liquid and rises from the rinsing liquid.

5 (a) shows the direction in FIG. 5 (b), and FIG. 5 (b) is a side sectional view of the same device part as FIG. 4;

6 (a) shows the direction in FIG. 6 (b), and FIG. 6 (b) is a plan view of means for contacting a wafer with a rinsing liquid in another apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Quartz glass square tank 2 Ultrapure water 6 Second ultrapure water supply means 8 Wafer 12 Vertical movement drive mechanism 14 Clamping jig 15 Drive mechanism 17 Hood 23 Gas outlet 24 Exhaust port 26 ULPA filter

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Mitsunobu Masuda 1-3-3 Dojimahama, Kita-ku, Osaka-shi, Osaka Prefecture Inside Takuma Co., Ltd. (72) Inventor Naoki Irie 1-3-23 Dojimahama, Kita-ku, Osaka-shi, Osaka No. TAKUMA Co., Ltd. (72) Inventor Yuji Fukasawa 1 Kosuka Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Inside the R & D Center (72) Inventor Hisashi Muraoka 3-15-2 Miigaoka, Aoba-ku, Yokohama, Kanagawa Examiner Kenichi Endo (58) Field surveyed (Int. Cl. ⁷ , DB name) B08B 3/10 F26B 19/00 F26B 25/00

Claims (8)

(57) [Claims] 1. A substrate is brought into contact with a rinsing liquid, and then the substrate is gradually lifted from the liquid surface of the rinsing liquid into a gas phase while the substrate surface is vertical. A method of rinsing and drying a substrate that sprays a high-purity gas flow in parallel and along the liquid surface, and the flow rate of the high-purity gas flow so that the liquid surface of the rinsing liquid in contact with the substrate rises in the leeward part of the substrate. A method for drying a substrate after rinsing, comprising adjusting a rising speed of the substrate. 2. The method according to claim 1, wherein said substrate comprises a semiconductor wafer, glass for a liquid crystal device, glass for a photomask, and a synthetic resin plate for a circuit board. 3. A filter for removing an acidic gas, a filter for removing a basic gas, an activated carbon filter for removing an organic substance, and a dust removing device. 0.2-2.0m through a purification system equipped with a filter for
2. The process is performed in a stream of clean air circulating at the rate of 1 / sec.
Or the second method. 4. The high-purity gas stream is heated,
The method according to claim 1. 5. The method of claim 3 wherein said high purity gas stream is introduced by accelerating a portion of said circulating clean air stream. 6. The method according to claim 1, further comprising heating after completely lifting the substrate from the level of the rinsing liquid. 7. A means for bringing a substrate into contact with a rinsing liquid, a means for holding the substrate in a state where the substrate surface is vertical, and gradually raising the substrate from a liquid surface of the rinsing liquid into a gaseous phase; Means for spraying a high-purity gas flow parallel to the substrate surface and creeping up the liquid surface of the rinsing liquid at the time of raising, further comprising at least the substrate contacted with the raised substrate on the liquid surface An apparatus for rinsing and drying a substrate, comprising: a container means for isolating a gas phase from an external environment and supplying a purified gas to the gas phase. 8. A purification system in which the container means includes a filter for removing an acidic gas, a filter for removing a basic gas, an activated carbon filter for removing organic substances, and a filter for removing dust. 8. The apparatus according to claim 7, wherein a clean air stream passing through the system and circulating at a flow rate of 0.2 to 2.0 m / sec is supplied to the gas phase in the vessel.