JPH06103686B2 - Surface drying treatment method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention aims at drying a surface after fluid treatment or wet treatment. In particular, the present invention relates to the manufacture of semiconductor components, and in particular to the preparation of semiconductor wafers prior to high temperature processing steps such as diffusion, ion implantation, epitaxial growth and chemical vapor deposition steps. The invention further relates to a method and apparatus for drying semiconductors after cleaning before diffusion.

(Problems to be Solved by the Prior Art, Technology, and Invention) In the manufacture of semiconductor wafers, several steps of processing require contact between the wafer and fluid. Examples of such processing steps include etching, photoresist stripping and cleaning prior to diffusion. Conventionally used equipment for contacting semiconductor wafers typically consists of a series of tanks or sinks in which a rack of semiconductor wafers is immersed. For example, US Pat. Nos. 3,607,478, 3,964,957 and 3,977,926 describe wafer support vessels. Several difficulties arise with such conventional wet processing equipment.

Since the tank is open to the atmosphere, airborne particles can penetrate into the processing solution. These particles readily transfer to the wafer via surface tension as the wafer is dipped into the sink and lifted from it. This particulate contaminant is very harmful to the microcircuits produced by the wafer manufacturing process. Therefore, it is particularly important to minimize particulate contaminants during pre-diffusion cleaning.

After liquid processing, the wafer usually needs to be dried. This is particularly an objective treatment of the invention, as it is an important treatment that no contaminants should be produced during the drying treatment. Evaporation is not preferred as it often causes spots or streaks. Even with the evaporation of ultrapure water, this ultrapure water is highly corrosive to the wafer surface, and dissolves trace amounts of silicon and silicon oxide even during a short water contact period.
This can cause problems. Subsequent evaporation will leave a residue of solute material on the wafer surface. For other sources of pollution and semiconductor failures, see, for example, J. Scha.
del, “Device failure mechanism in integrated circuits”,
Semiconductor Device 1983 69th Annual Conference (The Physical Society of Japan, London 1984) 105-120.

Conventionally, semiconductors are dried by centrifugal force in a rotary water washing and drying device. Since these devices rely on the centrifugal force to release water from the wafer surface, there are some problems in use. First, mechanical stress is exerted on the wafer, resulting in wafer damage, especially for large wafers. Secondly, since there are many moving parts in the rotary water washing / drying device, it is difficult to suppress contamination. Third,
Conventionally, since the wafer moves at high speed in dry nitrogen, an electrostatic charge is generated on the wafer surface. Airborne particles of opposite charge are rapidly attracted to the wafer surface upon opening the rotary wash dryer, resulting in particle contamination. Fourth, it is difficult to avoid water evaporation from the wafer surface during spin processing with the attendant drawbacks mentioned above.

Recently, methods and apparatus for vapor or chemical drying of wafers have been developed, including in our US Pat.
There is a method and apparatus disclosed in 532. Chemical drying generally consists of two stages. In the first stage, a rinsing fluid, preferably water, is expelled from the wafer,
Replaced with dry fluid, not water. In the second stage,
The non-water drying fluid is evaporated using a pre-drying gas, preferably an inert gas such as nitrogen, at a slow rate.

Another chemical drying process currently used in Japan is to sequentially immerse the wafer support container in a tank of deionized water,
It is then constructed by suspending the wear on a tank of boiling isopropanol. The wafer support container is then gradually withdrawn from the isopropanol vapor to remove water droplets from the wafer surface.

The most important feature of an effective wafer drying technique is that the wafers produced are ultra-clean, that is, they have minimal particulate contamination and minimal chemical residues.
Since many dry solvents are flammable, safety is also a very important consideration. Other important design criteria include low chemical consumption, low waste generation, and automated handling with no or little operator exposure.

(Means for Solving the Problem) The surface drying treatment method of the present invention is a method for drying the surface of an object that is completely immersed in a washing fluid, wherein drying steam is supplied to dry the washing fluid. Substitution of the rinsing fluid with dry vapor sufficiently slow such that after displacing with vapor, the droplets are substantially not left on the surface of the body and the rinsing fluid or dry vapor is not substantially removed by evaporation of the droplets. The method comprises the step of displacing the rinsing fluid with dry steam at a rate by displacing the rinsing fluid directly from the surface of the body, which solves the above conventional problems.

Further, the surface drying treatment apparatus of the present invention is an apparatus for drying the surface of a wet object, which comprises a container for supporting the object for contacting the cleaning object and the dry steam, and an inflow means for introducing the dry steam. An outlet means for letting out the washing fluid and the dry vapor, and substantially no droplets remain on the surface after the washing fluid is replaced with the dry vapor, and the washing fluid or the dry vapor is substantially evaporated by the evaporation of the droplets. Control means for controlling the rate at which the washing fluid flows out of the vessel and the rate at which the drying vapor enters the vessel such that the washing fluid is replaced by the drying vapor at a sufficiently slow rate such that it is not removed. And thus solves the above-mentioned conventional problems.

The method and apparatus according to the present invention comprises rinsing the surface of an object such as a semiconductor wafer with water to remove processing fluids such as etchants, photoresist stripping agents or pre-diffusion cleaners, and then drying the surface. Provided. Dry steam is supplied to the surface such that the steam replaces the flushing fluid by directly displacing the flushing fluid on the surface at a rate such that substantially no droplets remain on the surface after replacing the flushing fluid with dry steam. . Preferably, the dry vapor is supplied from above the object in a fully closed hydraulically-filled system and the wash fluid is forced from the surface by the dry vapor as the liquid level decreases downward.

Since the washing fluid is usually water in the liquid phase, it is preferred that the dry steam be compatible with water and still form an azeotrope of water with a minimum boiling point, with isopropanol being particularly preferred in this respect. Furthermore, the dry steam is substantially pure and saturated or preferably superheated, and the surface needs to be heated to a temperature close to, preferably below, the temperature of the dry steam before contacting. . This may result in some vapor condensation on the surface and over-condensation should be avoided, but heating above the temperature of the dry vapor has poor consequences.

Further included in the method and apparatus of the present invention is a dry inert non-condensable gas supply for purging dry steam after replacement of the wash fluid, and concentrating the mixture of wash fluid and dry steam after exiting the process vessel. There is a boiler and a distillation column.

In a preferred embodiment, the evaporator producing saturated dry steam is provided with an upper boiler section and a lower holding section in which the dry steam is rapidly produced in the boiler section and held in the lower section at just the boiling point of the dry steam. To be done. This can be achieved by providing an insulating gasket that limits the amount of heat transfer from the boiler section to the holding section. The evaporator is preferably fully closed,
Also, the fresh drying fluid is automatically replenished by lowering the temperature of the fluid in the upper holding section so as to create a reduced pressure that draws the fresh drying fluid from a storage source that is preferably maintained below the temperature of the evaporator. . Saturated dry steam with a suitable latent heat curve (pressure-enthalpy diagram) is preferably superheated by means of a pressure drop valve and still filtered between the evaporator and the process vessel.

(Example) The present invention, after various wet treatment or fluid treatment,
Although broadly intended for surface drying of solid objects, especially planar objects, the present invention is described with particular reference to cleaning before diffusion and drying of semiconductor wafers after washing, so that the same general It is understood that the physical principles apply to other wet surfaces.

Further, while the drying system of the present invention can be used with a variety of cleaning, etching or other wafer processing methods and apparatus, the system does not require processing fluids as described and claimed in U.S. Patent No. 4,775,532. It is particularly suitable for use in methods and apparatus for processing wafers using.
Therefore, the present invention is an improvement that can replace the steam or chemical drying system described in that application.

Similarly, a variety of wafer support vessels can be used to suspend semiconductor wafers in flush and dry fluids, as described herein, but in particular, the wafer support vessels described in our US Pat. Have been found suitable for use in the method and apparatus of the present invention. Such a support container is shown in simplified form in Figure 2 of the present application for the purpose of illustrating the invention.

As shown in FIG. 1, the apparatus for carrying out the present invention includes three main apparatuses, namely, an evaporator 10 for producing dry steam.
A container 12 is provided for holding wafers for treatment with flushing fluid and dry steam, and a boiler 14 for concentrating spent flushing fluid and dry vapor for disposal and / or reuse. These three units, along with their associated plumbing, valves and other components, are shown schematically in FIG.

First, referring to FIG. 2, a preferable container 12 used in the present invention will be described. Our US Patent No. 4,577,650
In the upper and lower wafer support vessels 18 and 20 of the type described in more detail in No. 1, two or more rows of side-by-side vertically oriented wafers are shown, as viewed from the side. The semiconductor wafer 16 is suspended. Two such wafer support vessels 18, 20 are shown in FIG. 2 stacked one on top of the other, but vessel 12 may include only one such support vessel, or three or more such vessels. It is also possible to provide. In some instances, vertical stacking may result in undesired dripping into the underlying support vessel.

The wafer support vessels 18 and 20 are held in place by an upper vessel clamp 22 connected to a fluid inlet 24 and a lower vessel clamp 26 connected to a fluid outlet 28. In FIG. 2, the container 12 is filled with dry steam 32 at the top,
The gas in the upper wafer support container 18 is passed through the wafer--the liquid--
The rinsing liquid 30 is partially filled as the solid interface 34 is pushed downwards.

In FIG. 3, the container 12 is a SEMI (Semicondustor Equipm).
ent and Meterial Institure, Inc.) Approved wafer support containers are arranged in parallel. The upper container clamp 22 'in this embodiment is in the form of a bell jar and is sealed on the lower container clamp 26' by a gasket 25 and a clamp fitting 27. Wafer containers 18 'and 20' are supported on rod 21 in lower container clamp 26 'while holding wafer 16'. In FIG. 3, the container 12 'is shown empty of flushing fluid.

Other container arrangements (not shown) in practicing the invention
It is also possible to adopt. For example, in another embodiment, it is located in a lower container clamp with a suitable cover, such as a bell jar type, similar to the upper container clamp 22 'of FIG. 3, to seal the system and remove overflow and waste. There may be more than one wafer support container in the overflow sink. It is important to seal the system in order to gas seal the vapor space around the wafer with dry vapor so as to prevent the inflow of different gases, eg nitrogen gas, during the direct replacement of the flush fluid with the dry fluid. Is.

Referring to FIG. 1, the evaporator 10 is provided with a lower boiler section 36 and an upper holding section 38, and the metal casings of the boiler section 36 and the holding section 38 are separated by an insulating gasket 40, The gasket limits the amount of heat transfer from the lower metal casing to the upper metal casing.

Boiler section 36 is provided with a heating band 42 or other suitable heat transfer device to rapidly heat the drying fluid above its boiling point. The boiler section 36 must be filled with a liquid dry fluid so that the heat transfer surface is always submerged. For this purpose a liquid level detector and a switch (not shown) can be provided, as well as a resistance temperature detector (not shown) for measuring the temperature of the dry liquid and for monitoring the temperature of the heating band.

Insulation gasket 40 may be of any suitable material,
It is constructed of one that withstands the heat of the boiler section 36 and is resistant to corrosion by dry fluids. For example, an enclosure gasket that fits between the two ANSI flanges of boiler section 36 and retaining section 38 is suitable. This insulating gasket prevents the nuisance temperature and pressure overshoot which, together with the metal casing, results in a sudden rise in the internal drying fluid. In this way, the boiler section 36
While at a high temperature to rapidly produce dry vapor, the holding section 38 is adapted to keep exactly at the boiling temperature of the dry fluid, which is the high pressure boiling point.

The holding section 38 substantially holds the liquid volume of the evaporator 10 and separates the liquid and vapor near the upper flange 46. The gasket 48, like the gasket 40 described above, can be placed between the flanges 46 to prevent unwanted heat transfer from the top of the retaining section 38 near the liquid-vapor interface. The holding section 38 can be provided with other accessory devices (not shown) such as, for example, liquid level detectors and switches, external heaters, and water cooling jackets.

The dry liquid and vapor flow into and out of the holding section 38 via the tube 50 and the cross joint 52. Fresh and / or circulated liquid dry fluid is supplied by a valve 54 (preferably a bellows valve) provided in the inflow line 58, and a filter 56 (preferably the trademark "Millip
through a submicron filter (known as an ore) into the evaporator 10, this inflow line being connected through valve 53 to a source of fresh dry fluid (not shown),
And / or is connected to a distillation column 94 and waste liquor receiving tank 95 that provide a circulating drying fluid as described below.

The saturated dry steam flows into the container 12 through a valve 60 (preferably also a bellows valve) provided in the line 64 and a flush valve 62. As explained in detail below, this flash valve can be used to reduce the pressure and thereby superheat the saturated dry steam. Flash valve 62 and 3-way switching valve
After passing 68, the dry steam passes through the final filter 69. This final filter 69 is, for example, a Fast filter from Eeast Technollogy, Inc. because gas is more highly filterable than a liquid.
A 0.01 micron ceramic filter is used, such as the model "PGF-2 filter" manufactured by ek Division.

The joint 52 is also provided with a pressure relief valve 66 for emergency against the overpressure of the evaporator. The evaporator 10 can also be provided with a maintenance drain (not shown) at the bottom of the boiler 36.

Vessel 12 includes other valves 70, 72, 74 and 76 that control various process fluids flowing into and out of vessel 12 for processing wafers 16, such as etching, stripping, cleaning and / or rinsing fluids. Is provided. Methods of controlling the outflow and inflow of these fluids into container 12 are described in detail, for example, in our US Pat. No. 4,778,532, which is not a part of this invention.

When the drying fluid displaces the rinsing fluid from the wafer 16 at the interface 34, the drying fluid mixes with the rinsing fluid, forming a distinct layer of drying fluid on top of the rinsing fluid, the thickness of which may be ½. Can reach up to an inch or more.

This final rinsing fluid and drying fluid layer exits the vessel 12 and enters the boiler 14 for concentrating and / or disposing of the used liquid via a valve 78 or metering pump 79 in line 80. The metering pump 79 is preferably a variable speed pump used to properly control the interfacial descent rate and optimize the drying time. Immediately before the valve 78 and the metering pump 79 in the line 80, there is a capacitance type switch (limit switch), which detects when the container 12 is completely drained. At this point the steam line 64 is closed and the purge gas is closed.
71, 68 and 70, and filter 69 can be passed through to container 12.

The dry steam and purge gas can flow out of the container 12 and into the boiler 14 via the valve 78. In order to better control the rate of descent of the interface 34 and optimize the drying time, the rinsing fluid can be withdrawn by the variable speed metering pump 79, at least during part of the descent. Flushing liquid valve
It is drained to the drain through 79. At the appropriate time, the layer of dry fluid and the layer of rinsing liquid immediately below it are switched through valve 83 into boiler 14.

The boiler 14 is provided with a band heater 92 or an immersion heater to remove the drying fluid or an azeotropic mixture of the drying fluid and the washing fluid from the wastewater. The vapor enters the distillation column 94 and is further concentrated. The water-cooled condenser 86 condenses the dry steam. The cooled non-condensable gas (eg, purge gas) exits through vent 88 while some of the condensate drains.
It flows into the waste liquid receiving tank 95 through 90 and is recycled to the supply line 58 for the evaporator 10.

The distillation column 94 can be a single column or a series of columns of conventional construction, depending on the degree of concentration of the dry fluid required for recycling of the spent fluid or disposal. The steam-removed wastewater exits the boiler 14 through the overflow valve 96 and enters the boiler 14 from the next run as a new batch of spent fluid. Fresh dry fluid can be added to the recirculating fluid through valve 83.

In practicing the method of the present invention, the drying fluid is selected to be compatible with the rinsing fluid and preferably to form an azeotrope with the rinsing fluid with a minimum boiling point. Drying fluids which form an azeotrope with a minimum boiling point with water are particularly preferred, as water is the most readily available and commonly used washing fluid. Generally, the drying fluid must be an organic compound that is non-reactive with the surface to be dried and that has a boiling point below 140 ° C. at atmospheric pressure.

The most effective chemical for drying is isopropyl alcohol (isopropanol). Isopropanol is economical, relatively safe (non-toxic), and forms a minimum boiling azeotrope with water. Also, importantly, isopropanol has a low surface tension and has both hydrophobic and hydrophilic properties (ie it is miscible with both oil and water). Without wishing to be bound by any particular theory, isopropanol tends to break the annoying surface tension between hydrophilic water and relatively hydrophobic water surfaces. Since the solid phase at the interface 34 is the wafer surface and the liquid phase is ultrapure water,
The choice of gas phase properties has a major impact, with isopropanol considered the most satisfactory fluid.

The process according to the invention is carried out with reference to the device described above and the preferred washing fluid (water) and dry steam (isopropanol),
As will be described in detail herein, the method can be carried out using other suitable equipment, as well as for other rinsing and drying fluids.

In the wet processing of semiconductor wafers according to the method of our U.S. Pat.No. 4,778,532, upward flow of fluid through the container 12 such that the fluid inlet 24 is the outlet and the fluid outlet 28 is the inlet is a minor process operation. There are advantages to This also applies to the flush fluid, which normally circulates upward through the vessel. However, in accordance with the present invention, the optimum form of wafer drying has been found to be downward flow.

The last cycle of rinsing with ultrapure water preferably uses warm water (eg, 65-85 ° C) to heat the wafer to near the boiling point of isopropanol (82 ° C). Instead, the wafer 16 is loaded into the wafer support vessels 18 and 20.
It can be heated by direct solid / solid heat transfer through its support vessel by means of a heating band or other heating device attached to the.

After the final wash cycle, the container 12 remains hydraulically filled with warm ultrapure water. Then the valve 78 is opened. However, water does not flow out of the container 12 because no substitute for water has flowed into the top. The flush valve and valve 70 are then opened and pure saturated isopropanol vapor flows into the vessel 12 through the inlet 24. As steam enters the upper vessel 22, water passes through the fluid outlet 28 and valve 78 to the bottom 26
Drained from.

Alternatively, the flush water can be withdrawn from the container 12 by the lightweight pump 79, the flow rate of which varies depending on the stage of the withdrawal cycle. For example, the lightweight pump 79 operates at a very high velocity until the interface 34 is just above the wafer, and then slows as the interface descends through the wafer. Finally, when the interface passes through the last wafer surface 16, the bypass valve 78 around the pump 79 is simply opened and the remaining water and dry fluid is forced out of the container by the purge gas.

The down-velocity of the gas-liquid-solid interface has some compromises to consider, but it is believed that it is important to control it relatively slowly. Therefore, if the wash water flows out of the container 12 too quickly, droplets will remain on the wafer, and evaporation of these droplets will result in contaminants. For this reason, it is preferred that the dry vapor displace the rinsing fluid from the wafer at a rate such that substantially no droplets remain on the wafer surface after replacing the water with isopropanol. On the other hand, a fast interface drop improves the productivity of the dryer and minimizes chemical consumption.

It has been found that interfacial descent rates are generally satisfactory in the range of 1 to 4 inches per minute. Descent rates above 5 inches per minute do not give good results, while descent rates below 1 inch per minute give poor results. Also, a container with a high temperature of about 75 ° C is 60
It has also been found that by lowering the interface faster than a container at a temperature as low as about 0 ° C, good drying performance is exhibited.

Similarly, isopropanol is preferably heated to provide a drier vapor to prevent the risk of vapor condensation on the wafer surface, to meet the requirement that liquid is not removed from the wafer surface by evaporation. The advantage of organic liquids such as isopropanol is that when the pressure drop occurs, saturated vapor is forced into the heating region of the phase diagram due to its pressure and the latent heat curve in the enthalpy diagram sloping backwards. That is. As a result, the saturated vapor generated by the evaporator 10 passes through the flash valve 62 to become a drier saturated vapor and is supplied to the wafer 16 in the container 12.

The holding section 38 of the evaporator 10 preferably holds a sufficient amount of liquid isopropanol so that the evaporator 10 can be charged for several wafers without being replenished.
If it is necessary to add fresh isopropanol to the evaporator 10, the temperature of the boiling isopropanol in the holding section 38 can be lowered to below its boiling point (82 ° C. at atmospheric pressure). Cooling jacket (not shown) attached to retention section 38 to reduce temperature
Useful. When the temperature drops below the boiling point, the vapor pressure in the evaporator 10 is reduced. Then, when valve 54 is opened, liquid isopropanol is drawn by suction from the storage location and into evaporator 10. Since this liquid isopropanol is generally cooler than the evaporator itself, the pressure in the evaporator is further reduced, facilitating the refill operation.

Flush water flows out of container 12 and opens valve 78 or lightweight pump 79.
Upon entry into the drain 81 or valve 83 through the limit switch 82 senses when the liquid has completely drained from the container 12. As soon as this container is completely empty, the line
When 64 is closed, a dry, inert, non-condensable gas such as nitrogen is introduced via valves 71, 68 and 70 to purge the isopropanol vapor from vessel 12. Nitrogen gas is also used with valve 68.
As it passes through the ceramic filter 69 between 70, this filter is essentially purged with nitrogen after passing through isopropanol. This purging prevents condensation of isopropanol in the filter and consequent clogging.

This purging flushes out any remaining vapor in vessel 12 through drain valve 78. The nitrogen gas pushes the isopropanol vapor out of the container and also removes what appears to be a monolayer of isopropanol on the wafer surface. This monolayer is very volatile,
Clearly, the mechanism of its removal differs from that of evaporation.

Finally, the spent water and the last of the isopropanol from the vessel flow into the boiler 14. Boiler 14 and distillation tower 94
The purpose of is to retain a mixture of isopropanol and contaminated water and reconcentrate the isopropanol for recycling or disposal to reduce its volume. Once the liquid in the container 12 is emptied, the nitrogen purge is started. The nitrogen gas passes through the container 12 and flows into the boiler 14, and then flows out through the condenser 86 and the vent 88.

It is clear that the isopropanol concentrates in the top layer of water as the interface 34 descends within the container 12, so
It is not necessary to first remove all the water flowing out of vessel 12. Therefore, most of the water is drained through valve 81 and the last pint of liquid or so much (ie, the isopropanol layer and the water directly below) is the boiler 14
Are stored in and processed. The so small amount of liquid allows the isopropanol / water mixture to boil easily.

When the band heater 92 is energized, the water / isopropanol mixture is heated and the azeotropic mixture of isopropanol and water (bp 79 ° C) is evaporated from the wastewater. This gaseous mixture passes through the distillation column 94, flows into the condenser 86, is condensed, and is stored in the waste liquid receiving tank 95 from the drain 90 or is refluxed to the distillation column 94. The wastewater from which the azeotrope mixture and steam have been removed overflows through valve 94, and the spent water from the next run then flows from vessel 12 to boiler 14.

In effect, the boiler 14 performs an incomplete separation, so the condenser 86
The liquid sent from the distillation column 94 to the distillation column 94 is 50% by weight of water and 50% by weight.
May become isopropanol. The distillation column then separates the azeotrope from the water to an azeotrope of 90 wt% isopropanol and 10 wt% water. This azeotropic mixture has a waste liquid receiving tank 95, a suitable mixing tank,
It can be reintroduced into the evaporator 10 through a filter and / or a filter, if desired, on a batch basis or continuously.

As mentioned above, if water remains on the wafer surface after washing with water,
Stripes, spots and particulate contamination occur almost exclusively. The advantage of using a minimum boiling azeotrope, such as water and isopropanol, is that the residual water film on the wafer surface, when combined with the isopropanol vapor, immediately flushes into the gas layer as an azeotrope. Drying efficiency is the interface
There is one theory that depends on the thickness of liquid isopropanol at the top of the falling wash water at 34, but a thin or no layer of liquid isopropanol reduces disposal problems and Is preferred, which is preferable. Regardless of the validity of this theory, stripes and spots are
It is clear that it is minimized by decreasing the rate of descent of the water surface (interface 34) and yet increasing the dryness (heating) of the steam.

While the above description is for isopropanol recycle (closed group system), or for concentrating organic liquids for disposal, cleaning the recovery with isopropanol or other dry vapors for recycle is It is preferable from the environmental and economic inspection grounds. This azeotropic mixture has a low boiling point and good electrothermal characteristics including heat capacity and transfer coefficient, and clearly improves the particle performance (cleanliness) of the wafer as compared with the case of using fresh pure isopropanol alone. This has been achieved without sacrificing.

Without attempting to be bound by any particular theory, if the interface 34 descends at a low enough velocity, the water / isopropanol interface removes all water droplets and azeotrope mixture droplets from the wafer as the liquid surface descends. It is believed to do. However, if the interface 34 descends too quickly, the surface tension or the affinity of water or other droplets for water will exceed the surface tension of the descending liquid. This leaves droplets on the wafer that evaporate, leaving streaks and contaminants. Thus, the method of the present invention involves physical extrusion by the vapor or pulling by the liquid surface, which results in direct displacement of the liquid by the vapor rather than evaporation of the droplets.

The method and apparatus of the present invention is a fully open, full flow system that is preferably hydraulically filled (ie, sealed) during the rinse and dry stages, which system transfers wafers between rinse and dry. Or it is understood from the description of steam that it does not require handling. The advantages of such a system are disclosed in our US Pat. No. 4,778,532.

According to the present invention, the contamination of the wafer surface due to the dissolved particles and other contaminants existing in the conventional system is reduced, and the drying efficiency of the semiconductor wafer is improved.

The present invention can be embodied in various other forms without departing from the spirit or the main characteristics thereof.

(Effects of the Invention) The surface drying treatment method and apparatus of the present invention are as follows.
The surface of the object can be reliably dried without contamination.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a preferred embodiment of the present invention. FIG. 2 is a detailed sectional view of the wafer container shown in FIG. FIG. 3 is a sectional view showing another embodiment of the wafer container. 10 ... Evaporator, 12 ... Vessel, 14 ... Boiler, 18, 20 ... Wafer support vessel, 24 ... Fluid inlet, 26 ... Lower vessel clamp, 28 ... Fluid outlet, 32 ... Dry steam, 36 ... Boiler section, 38 ... Holding Section, 94 ... Distillation tower, 95 ... Waste liquid receiving tank.

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Claims (47)

[Claims] 1. A method of drying the surface of an object that is completely immersed in a washing fluid, wherein after supplying the drying steam to replace the washing fluid with the drying steam, droplets are deposited on the surface of the object. Direct displacement of the rinsing fluid from the surface of the object with substantially no residue, and with a sufficiently slow rinsing fluid replacement rate of the rinsing fluid with the dry vapor such that the rinsing fluid or dry vapor is not substantially removed by evaporation of the droplets. A surface drying treatment method including the step of substituting the washing fluid with dry steam. 2. The rinsing fluid is water in a liquid phase.
The method described in. 3. The method of claim 2, wherein the surface of the object is heated to about the temperature of the dry steam before being contacted by the dry steam. 4. The method of claim 3, wherein the heating of the dry steam is accomplished by heat transfer from the flushing fluid. 5. The method of claim 3, wherein the heating of the dry steam is accomplished by heat transfer between solids from a support vessel that suspends the object. 6. The method of claim 1, wherein the rinsing fluid is pushed downward by the dry steam. 7. The method of claim 1, wherein the flushing fluid is separated from the object by external pumping means. 8. The method of claim 1, wherein the dry vapor is purged from the surface of the object by introducing a dry, inert, non-condensable gas after displacement of the flushing fluid. 9. The method of claim 8, wherein the gas is nitrogen. 10. The method of claim 1, wherein the dry vapor is saturated. 11. The method of claim 1, wherein the dry steam is superheated. 12. The method of claim 2, wherein the dry steam is compatible with water. 13. The method of claim 2, wherein the dry steam forms an azeotropic mixture with water having a minimum boiling point. 14. The method of claim 13, wherein the dry vapor is isopropanol. 15. The method of claim 1, wherein the dry vapor is an azeotropic mixture. 16. The method of claim 15, wherein the dry vapor is an azeotropic mixture of isopropanol and water. 17. The surface of the rinsing fluid is such that the droplets of the rinsing fluid or the dry steam do not substantially remain on the surface of the object after the rinsing fluid is replaced with the dry steam. To completely drain and flush out the flushing fluid as it descends from and to completely seal the support vessel that suspends the body and introduce the dry vapor from above the body. The method of claim 1. 18. The method of claim 1, wherein the dry vapor is an organic compound that is not reactive with the surface of the body and that has a boiling point below 140 ° C. at atmospheric pressure. 19. The method according to claim 1, wherein no movement or handling of the surface of the object is required between the steps of washing and drying. 20. The method of claim 19, wherein the container on which the object is suspended is hydraulically filled during the washing and drying steps. 21. The method of claim 20, wherein the body is gas sealed with dry steam immediately after withdrawal of the flushing fluid. 22. The object is a semiconductor wafer.
The method described in. 23. The method of claim 1, wherein the dry vapor is filtered in the gas phase before contacting the surface of the object. 24. The method of claim 1, wherein the dry vapor is collected and recycled after drying the surface of the object. 25. The method of claim 24, wherein the dry steam is recycled in the form of an azeotrope with the wash fluid. 26. A surface drying treatment method, wherein the object is a semiconductor wafer, the washing fluid is warm water, the dry vapor is isopropanol, and a supporting container for suspending the object is completely sealed. And injecting isopropanol vapor from above the wafer to remove and replace the water as it descends from the wafer at a rate such that substantially no droplets remain on the wafer surface. 2. The method of claim 1, further comprising the step of: making the wafer substantially the same temperature as the vapor when the wafer contacts the vapor. 27. An apparatus for drying the surface of a wet object, the container supporting the object for coming into contact with the cleaning fluid and the dry vapor, inflow means for allowing the dry vapor to flow in, the rinsing fluid and the Outflow means for letting out the dry steam, and such that after replacement of the washing fluid with dry steam, substantially no droplets remain on the surface, and the washing fluid or dry steam is not substantially removed by evaporation of the droplets. A surface drying treatment apparatus having a control means for controlling a rate at which the washing fluid flows out of the container and a rate at which the drying steam flows into the vessel so that the washing fluid is replaced by the drying vapor at a sufficiently slow rate. . 28. The device of claim 27, which is completely sealed. 29. An apparatus according to claim 27, comprising means for heating the surface of the object to about the temperature of the dry steam before contacting with the dry steam. 30. An apparatus according to claim 27, comprising valve means for reducing the pressure of the dry vapor to superheat the dry vapor before contacting the surface of the object. 31. An apparatus according to claim 27, wherein the inflow means is above the object in the container and the outflow means is below it. 32. An apparatus according to claim 27, further comprising sealing means for gas-sealing an object with dry steam after withdrawal of the washing fluid. 33. The apparatus of claim 27, further comprising means for introducing a dry, inert, non-condensable gas into the vessel after displacement of the flushing fluid with the dry steam. 34. Means for holding the rinsing fluid and dry steam in contact with the rinsing fluid and dry steam in contact with the surface of the object such that the object does not move during passage thereof. The device of claim 27, having. 35. The apparatus of claim 34, including means for hydraulically filling the vessel while the flushing fluid and dry vapor are in contact with the object surface. 36. Apparatus according to claim 27, comprising sealing means for preventing the ingress of different gases during drying. 37. An apparatus according to claim 27, comprising means for concentrating a mixture of rinsing fluid and dry steam after exiting the vessel. 38. An apparatus according to claim 37, comprising means for recycling the concentrated mixture as dry vapor to the vessel. 39. The apparatus of claim 27, including evaporator means for producing saturated dry vapor from the original fluid. 40. The evaporator means is a surface drying treatment method for drying a semiconductor wafer immersed in a container containing hot water as a scavenging fluid for the organic liquid, wherein the liquid is deposited on the wafer surface. Introducing isopropanol vapor from above the wafer to remove and replace the water as the water surface descends from the wafer at a rate such that substantially no drops remain. A method for drying a surface, the method comprising allowing the enclosed water to sufficiently flow out, wherein the temperature is substantially the same as that of the steam when the steam comes into contact with the steam. 40. The apparatus of claim 39, comprising a partial boiler section and an upper holding section, and means for maintaining the temperature of the upper holding section at the boiling point of the organic liquid. 41. The apparatus according to claim 40, wherein the temperature maintaining means is provided with means for limiting an amount of heat transfer from the boiler to the holding section. 42. The apparatus of claim 39, wherein the evaporator means is wholly enclosed. 43. An apparatus according to claim 42, further comprising replenishing means for automatically replenishing the evaporator means with fresh organic liquid and / or recirculated dry fluid. 44. The apparatus according to claim 43, wherein the replenishing means includes means for lowering the temperature of the organic liquid in the holding section below the boiling point of the organic liquid. 45. Apparatus according to claim 44, comprising storage means for maintaining the temperature of the fresh organic liquid and / or recycled dry liquid feed below the temperature of the holding section. 46. The apparatus according to claim 27, further comprising filter means for filtering the dry vapor in the dry vapor phase before flowing into the container means. 47. A surface drying treatment apparatus for drying a semiconductor wafer immersed in a container containing warm water as a washing fluid, wherein a droplet is not substantially left on the wafer surface. Isopropanol vapor is introduced from above the wafer to remove and replace the water as the surface of the water descends from the wafer, and when the wafer comes in contact with the vapor, substantially A surface drying treatment apparatus adapted to allow the enclosed water to sufficiently flow out, so that the temperature is kept the same.