JPH07283194A - Cleaning and drying method and cleaner - Google Patents

Abstract

PURPOSE:To provide a cleaning and drying method and cleaner wherein the state that no water drops deposit on the surface of a work is prepared before or in a drying step to avoid contaminating the surface of the work with water stain, etc., and consumption of a chemical liq. can be minimized. CONSTITUTION:A wafer 12 is immersed in pure water 17 overflowing from a washing tank 16. The water overflowing from this tank is stopped to form a chemical liq. layer 30 different, at least, in surface tension and wetness from the pure water at the interface of the water. The wafer 12 immersed in the tank 16 is moved at specified speed, relative to the layer 30 so as to pass through this layer, and dried after passing through and taken out from the layer 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning / drying method and a cleaning apparatus for cleaning and drying a component such as a semiconductor wafer which is extremely disliked by contamination.

[0002]

2. Description of the Related Art The miniaturization of semiconductor devices is rapidly progressing, and the memory capacities are increasing to 64M DRAM, 256M DRAM and the next, and research and development therefor are actively progressing.

Under such circumstances, the wafer cleaning technique will be a very important technique for ensuring the reliability of devices and the product yield in the future. In particular, it is said that particles up to about 1/10 of the minimum pattern size affect the product yield, and with the miniaturization of devices, the demands on the cleaning apparatus are becoming more severe.

One of the causes of defects caused by cleaning by the cleaning device is water stains, so-called watermarks, which are generated in the drying process after cleaning the wafer. For example, as shown in FIG. 5 (A), if water stains (watermarks) 6 are present on the surface of the wafer 4 on which the underlayer 2 is formed, the water mark 6 itself becomes a mask during etching processing, and FIG. As shown in (1), the etching residual portion 2a and the like are formed in the underlayer 2, causing a process defect.

The following two points can be cited as the causes of generation or generation of the water stains 6 as the watermark. The first reason is that water stains 6 adhering to the wafer become water stains 6 during drying after cleaning.

The second cause is shown in FIGS.
As shown in, oxygen in the air is dissolved in the water droplets 8 attached to the surface of the wafer 4, an oxidation reaction occurs at the interface between the wafer 4 and the water droplets, and the silicon oxide generated as a result is dried. It is conceivable that the water will become water stains 6 by being deposited.

As a method of suppressing the generation of the watermark thus generated, for example, a method of making the atmosphere of the drying step a nitrogen atmosphere has been proposed.

[0008]

However, this method is effective for suppressing the above-mentioned second cause of the watermark, but is not so effective for suppressing the above-mentioned first cause. Can't expect Therefore, the best solution is to create a state where water droplets are not attached to the wafer surface before or during the drying process.

Therefore, for example, Japanese Patent Laid-Open No. 2-301138.
When the cleaning of the wafer with pure water is completed, the pure water in the cleaning tank is discharged in a short time and replaced with a chemical solution such as isopropyl alcohol (IPA), and the wafer is transferred to the IAP. A method has been proposed in which the wafer is taken out and then dried after the immersion.

However, in this method, the inside of the cleaning tank is filled with IP.
Since it is filled with A, there is a problem that a large amount of IPA is required and the manufacturing cost becomes high. Also, a large amount of IP
It is necessary to mount a mechanism for collecting A, which also increases the manufacturing cost. In addition, recently, a method of exposing a wafer after cleaning with pure water to IPA vapor to remove water droplets on the wafer surface has been proposed.
The consumption of A is large, which causes an increase in manufacturing cost.

The present invention has been made in view of such circumstances, and before the drying step or in the drying step, the surface of the object to be cleaned is made to have no water droplets, and the surface of the object to be cleaned is contaminated with water stains. It is an object of the present invention to provide a cleaning / drying method and a cleaning apparatus capable of preventing cation and minimizing the amount of chemical solution used.

[0012]

In order to achieve the above object, a cleaning / drying method according to the present invention comprises a step of immersing an object to be cleaned in a cleaning tank in which pure water overflows, and The step of stopping the overflow of pure water and forming a chemical liquid layer having a surface tension and wettability different from that of pure water on the interface of pure water, and the article to be cleaned immersed in the cleaning tank is There is a step of moving the object to be cleaned relative to the chemical liquid layer so as to pass therethrough, and a step of drying the object to be cleaned exposed or taken out through the chemical liquid layer.

The chemical layer is preferably formed by dropping one selected from methanol, ethanol and isopropyl alcohol on the interface of pure water. The thickness of this chemical liquid layer is not particularly limited, but is preferably 1 mm to 5 cm. If it is too thin, the intended purpose of the present invention cannot be achieved. On the other hand, if it is too thick, the amount of the chemical solution consumed increases, which is not preferable.

A semiconductor wafer can be preferably used as the object to be cleaned. The speed at which the object to be cleaned is moved relative to the chemical layer is preferably 0.1 to
It is 15 mm / sec, more preferably 0.5 to 3 mm / sec. If the speed is too fast, it becomes difficult to achieve the intended purpose of the present invention, and if the speed is too slow, the time required for the washing step becomes long, which is not preferable. Examples of means for relative movement include means for gently pulling up the object to be cleaned from the cleaning tank, and means for gradually discharging the pure water in the cleaning tank and gradually lowering the chemical liquid layer.

As means for drying the object to be cleaned, in addition to ordinary standing drying, physical drying means such as spin dry drying or air flow drying means, for example, a general drying means as a semiconductor wafer drying means. Can be adopted. The cleaning apparatus according to the present invention is such that pure water flows so as to overflow, a cleaning tank capable of accommodating an object to be cleaned therein, and pure water for feeding pure water into the cleaning tank and stopping the feeding of pure water. Water supply control means,
It has a chemical liquid supply means for forming a chemical liquid layer by supplying a chemical liquid having a surface tension and wettability different from that of the pure water to the interface of the pure water in the cleaning tank in a state where the feeding of the pure water is stopped.

The chemical liquid supply means has a chemical liquid supply nozzle, and the chemical liquid supply nozzle is mounted on the upper part of the cleaning tank.
It is preferable that the chemical liquid is dropped from the chemical liquid supply nozzle to the interface of pure water. A heater for heating the chemical liquid in the chemical liquid layer to an appropriate degree may be attached to the outer periphery of the upper portion of the cleaning tank.

[0017]

In the cleaning / drying method according to the present invention, the object to be cleaned is cleaned with pure water, and then the object to be cleaned is passed through the chemical liquid layer. At that time, due to the difference in surface tension between the pure water and the chemical solution and the difference in wettability, the water droplets on the surface of the object to be cleaned are replaced with the chemical solution, and the water droplets do not adhere to the surface of the object to be cleaned. Thing
It is pulled up from the washing tank. Alternatively, the object to be cleaned is left in the cleaning tank while water droplets are not attached to the surface of the object to be cleaned.

After that, if the object to be cleaned is dried, problems such as water stains (water marks) do not occur on the surface of the object to be cleaned. Moreover, in the method of the present invention, the use of a chemical solution for preventing water spots is sufficient for forming a thin chemical layer at the interface of pure water, which is small enough compared to the conventional method.
The amount of chemical solution used can be reduced. As a result, it contributes to the reduction of the cost required for collecting or discarding the chemical liquid, the reduction of the use cost of the chemical liquid, and the reduction of the manufacturing cost as a whole.

By cleaning and drying a semiconductor wafer using the method according to the present invention, it is possible to reduce defective factors (water stains, etc.) in the semiconductor device manufacturing process, and improve the semiconductor device manufacturing yield and reliability. Can be made. The cleaning apparatus according to the present invention has a configuration suitable for performing the method according to the present invention, and the apparatus is not complicated and is inexpensive.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A cleaning / drying method and a cleaning apparatus according to the present invention will be described below in detail based on the embodiments shown in the drawings. 1A to 1C are schematic cross-sectional views showing a semiconductor wafer cleaning apparatus and a method of using the same according to an embodiment of the present invention.

As shown in FIGS. 1A to 1C, the cleaning apparatus 10 according to this embodiment is used for cleaning a semiconductor wafer 12, and a wafer carrier 14 containing the wafer 12 is immersed as it is. Cleaning tank 16 for pure water cleaning
Have. As the wafer carrier 14, a carrier made of fluororesin or the like with less contamination is used, and a plurality of wafers can be housed inside.

The pure water cleaning tank 16 may be used alone in the semiconductor device manufacturing process, or may be used in combination with an alkali cleaning cleaning tank or an acid cleaning cleaning tank. . A pure water supply pipe 18 is connected to the lower portion of the cleaning tank 16 according to this embodiment. Pure water supply pipe 1
Deionized water supply control means such as a control valve (not shown) is attached to the unit 8 to control the supply of deionized water 17 into the cleaning tank 16.

At the time of cleaning the wafer, the control valve is controlled to constantly supply a predetermined amount of pure water from the pure water supply pipe 18 into the cleaning tank 16 (about 2-3 times the inner volume of the cleaning tank 16 / minute). The cleaning tank 16 is supplied and overflows from the upper edge of the cleaning tank 16. The overflowed pure water is washed in the cleaning tank 16
It flows into the gutter part 20 attached around the circumference of the gutter, and is drained from there.

A triangular weir 22 is preferably provided at the upper edge of the cleaning tank 16 as shown in FIG. 2, for example. By providing the triangular weir 22, the flow rate of the pure water that overflows can be adjusted and the liquid surface can be made constant. As shown in FIG. 1, the cleaning tank 16 according to the present embodiment.
A chemical liquid supply pipe 24 as a chemical liquid supply means is attached to the upper part of the. In the example shown in FIG. 1, the nozzle 26 of the chemical solution supply pipe 24 is connected to the wall portion of the cleaning tank 16, but as shown in FIG. It may be mounted at any position where the chemical liquid can be dropped on the interface (liquid surface) of the pure water 17.

The chemical liquid supplied from the chemical liquid supply pipe 24 is different from pure water in surface tension and wettability at least,
A liquid having a lower specific gravity than pure water is used, and preferably methanol, ethanol, isopropyl alcohol (IP
A) is used. Particularly preferably, IPA is used. This is because by using IPA, the chemical liquid layer described later can be kept in a state separated from pure water for a relatively long time.

A control valve (not shown) or the like is attached to the chemical liquid supply pipe 24, and when the cleaning of the wafer 12 due to overflow of pure water 17 is completed, a predetermined amount of chemical liquid is added to the interface (liquid surface) of pure water. It is designed to be dropped or poured. Next, a method of cleaning and drying a wafer using the cleaning apparatus 10 according to this embodiment will be described.

First, as shown in FIG. 1A, pure water 17 is supplied from a pure water supply pipe 18 to fill the inside of the cleaning tank 16 with pure water, and the pure water overflows from the upper edge of the tank 16. Next, the carrier 14 containing the wafer 12 to be cleaned with pure water is immersed in the cleaning tank 16 so that the whole wafer is immersed in pure water.

The state is maintained for, for example, 5 to 15 minutes to clean the wafer. During that time, the pure water 17 always overflows from the upper edge of the cleaning tank 16. As described above, the flow rate is, for example, about 2 to about the inner volume of the tank 16.
3 times / minute. The cleaning time can be appropriately changed according to the conditions of the wafer.

When the cleaning of the wafer with pure water is completed, the supply of pure water from the pure water supply pipe 18 into the tank 16 is stopped. Next, the liquid medicine is dropped or poured from the liquid medicine supply pipe 24,
As shown in FIG. 1B, the chemical liquid layer 30 is formed at the interface with the pure water 17. The thickness of the chemical liquid layer 30 formed by dropping or pouring from the chemical liquid supply pipe 24 is not particularly limited, but is preferably 1 mm to 5 cm. In order to form the chemical liquid layer 30 having such a thickness, depending on the size of the cleaning tank 16, a chemical liquid usage amount of, for example, about 100 cc is sufficient.

Next, in the method of this embodiment, as shown in FIG. 1C, the carrier 14 in which the wafer 12 is accommodated is stored.
With a robot hand or the like. At that time, pay attention to the pulling rate. The pulling rate is preferably 0.1 to 15 mm / sec, more preferably 0.5.
~ 3 mm / sec. If the speed is too fast, water droplets may adhere to the wafer after being lifted, and if the speed is too slow, the time required for the cleaning step becomes long, which is not preferable.

In the method of this embodiment, as shown in FIG. 1C, the wafer 12 is pulled up so that the wafer 12 passes through the chemical layer 30 gently. Due to the difference in surface tension and the difference in wettability between the pure water and the chemical liquid, the water droplets on the surface of the wafer 12 are replaced with the chemical liquid, and the wafer 12 is pulled up in a state where the water droplets do not adhere to the surface of the wafer 12.

After that, if the wafer 12 is dried, problems such as water stains (water marks) do not occur on the surface of the wafer 12. As a method for drying the wafer 12, in addition to ordinary natural standing drying, physical drying means such as spin dry drying or air flow drying means, or other drying means generally used as a wafer drying means can be adopted. .

In the method of the present embodiment, the use of the chemical solution for preventing water spots is small enough to form the thin chemical solution layer 30 at the interface of pure water, which is less than the conventional method. The amount of chemical solution used can be reduced. as a result,
This contributes to the reduction of the cost required for collecting or discarding the chemical liquid, the reduction of the use cost of the chemical liquid, and the overall reduction of the manufacturing cost of the semiconductor device.

That is, according to the method of this embodiment, it is possible to reduce defective factors (water stains, etc.) in the manufacturing process of the semiconductor device, and improve the manufacturing yield and reliability of the semiconductor device. The present invention is not limited to the above-mentioned embodiments, but can be modified in various ways within the scope of the present invention.

FIG. 3 shows a cleaning device 10a according to another embodiment of the present invention. In this embodiment, as shown in FIG. 3, as compared with the cleaning apparatus 10 of the embodiment shown in FIG. 1, the peripheral side wall of the cleaning tank 16a is set higher and a weir 22a for overflow is formed in the middle thereof. . Then, the heater 32 is arranged around the upper portion of the side wall of the tank 16a. This heater 3
2 is controlled so as to assist the evaporation of the chemical liquid from the chemical liquid layer 30 formed on the interface of the pure water 17 when the switch is turned on when the cleaning of the wafer by the overflow of the pure water 17 is completed. Since other configurations are similar to those of the embodiment shown in FIG. 1, some of the common configurations and operations are omitted.

By mounting the heater 32 on the upper portion of the tank 16a as in this embodiment, the chemical liquid such as IPA in the chemical liquid layer 30 is evaporated, and the wafer 12 is taken out into the vapor atmosphere to improve the drying efficiency. It is possible to improve. FIG. 4 shows a cleaning device 10b according to still another embodiment of the present invention.

As shown in FIG. 4, the cleaning apparatus 1 of this embodiment
0b is different from the cleaning apparatus 10a according to the embodiment shown in FIG. 1 only in that a drain pipe 34 is attached to the lower portion of the cleaning tank 16b. Since other configurations are similar to those of the embodiment shown in FIG. 1, common members are denoted by the same reference numerals, and description thereof will be partially omitted.

When the cleaning apparatus 10b according to the present embodiment is used to clean the wafer, after forming the chemical liquid layer 30 at the interface with the pure water 17 as in the embodiment shown in FIG.
The drain pipe 34 is opened, and the pure water 17 is gently drained from there. At that time, be careful not to lose the shape of the chemical liquid layer 30 at the interface. When the pure water 17 is gently drained from the drain pipe 34, the chemical liquid layer 30 is lowered in the tank 16b at a speed corresponding to the pulling speed in the embodiment of FIG. Eventually, the chemical liquid forming the chemical liquid layer 30 is also drained by the drain pipe 34.
Drained from.

As a result, the wafer 12 relatively gently passes through the chemical liquid layer 12, and finally remains (is exposed) in the tank 16b. Even in the case of this embodiment, due to the difference in surface tension and the wettability between the pure water and the chemical liquid, the wafer 1
The water droplets on the surface of No. 2 are replaced with the chemical liquid, and the water droplets do not adhere to the surface of the wafer 12, and the wafer 12 is kept in the tank 16b.
Remain inside. Therefore, also in this embodiment, the same effect as that of the embodiment shown in FIG. 1 can be expected.

Particularly in this embodiment, it is possible to continue the drying process inside the tank 16b. Further, the cleaning apparatus and the cleaning / drying method using the cleaning apparatus according to the present invention are not applied only to semiconductor wafers, but for cleaning and drying parts that are extremely disliked by contamination. It is possible to apply.

[0041]

As described above, according to the present invention, after cleaning the object to be cleaned with pure water, the object to be cleaned is passed through the chemical liquid layer. At that time, due to the difference in surface tension between the pure water and the chemical solution and the difference in wettability, the water droplets on the surface of the object to be cleaned are replaced with the chemical solution, and the water droplets do not adhere to the surface of the object to be cleaned. The item is pulled out from the washing tank. Alternatively, the object to be cleaned is left in the cleaning tank while water droplets are not attached to the surface of the object to be cleaned.

After that, if the object to be cleaned is dried, problems such as water stains (water marks) do not occur on the surface of the object to be cleaned. Moreover, in the method of the present invention, the use of a chemical solution for preventing water spots is sufficient for forming a thin chemical layer at the interface of pure water, which is small enough compared to the conventional method.
The amount of chemical solution used can be reduced. As a result, it contributes to the reduction of the cost required for collecting or discarding the chemical liquid, the reduction of the use cost of the chemical liquid, and the reduction of the manufacturing cost as a whole.

If the semiconductor wafer is washed and dried using the method according to the present invention, it is possible to reduce defective factors (water stains, etc.) in the semiconductor device manufacturing process and improve the semiconductor device manufacturing yield and reliability. Can be made. The cleaning apparatus according to the present invention has a configuration suitable for performing the method according to the present invention, and the apparatus is not complicated and is inexpensive.

[Brief description of drawings]

1A to 1C are schematic cross-sectional views showing a semiconductor wafer cleaning apparatus and a method of using the same according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a modified example of the cleaning tank shown in FIG.

FIG. 3 is a cross-sectional view of a main part of a cleaning device according to another embodiment of the present invention.

FIG. 4 is a cross-sectional view of essential parts of a cleaning device according to still another embodiment of the present invention.

5 (A) and 5 (B) are cross-sectional views of a main part of a wafer surface showing conventional problems.

6A to 6C are schematic views showing an example of a generation process of water stains formed on the wafer surface.

[Explanation of symbols]

 10, 10a, 10b ... Cleaning device 12 ... Wafer 16, 16a, 16b ... Cleaning tank 17 ... Pure water 18 ... Pure water supply pipe 24 ... Chemical liquid supply pipe 26 ... Nozzle 30 ... Chemical liquid layer 32 ... Heater 34 ... Drain pipe

Claims (7)

[Claims] 1. A step of immersing an object to be cleaned in a cleaning tank in which pure water overflows, stopping the overflow of pure water from the cleaning tank, and deionizing the surface of pure water with surface tension and wetting. The step of forming a chemical liquid layer having at least different properties and the relative movement of the object to be cleaned at a predetermined speed with respect to the chemical liquid layer so that the object to be cleaned immersed in the cleaning tank passes through the chemical liquid layer. A cleaning / drying method, which comprises a step of: and a step of drying the object to be cleaned exposed or taken out through the chemical liquid layer. 2. The cleaning / drying method according to claim 1, wherein the chemical liquid layer is formed by dropping one selected from methanol, ethanol and isopropyl alcohol on the interface of pure water. 3. The cleaning / drying method according to claim 1, wherein the object to be cleaned is a semiconductor wafer. 4. The speed at which the object to be cleaned is moved relative to the chemical liquid layer is 0.1 to 15 mm / sec.
The cleaning / drying method according to any one of 3 to 3. 5. The pure water flows so as to overflow,
A cleaning tank capable of accommodating an object to be cleaned, a pure water supply control means for supplying pure water into the cleaning tank and stopping the supply of pure water, and a state where the supply of pure water is stopped, A cleaning device having a chemical liquid supply means for supplying a chemical liquid having a surface tension and a wettability different from those of pure water to the interface of pure water in the cleaning tank to form a chemical layer. 6. The chemical liquid supply means has a chemical liquid supply nozzle, and the chemical liquid supply nozzle is mounted on an upper part of a cleaning tank, and the chemical liquid is dropped from the chemical liquid supply nozzle to an interface of pure water. The cleaning apparatus according to claim 5, wherein 7. The cleaning device according to claim 5, wherein a heater for heating the chemical liquid in the chemical liquid layer to a suitable degree to evaporate the chemical liquid is mounted on the outer periphery of the upper portion of the cleaning tank.