JPH04336430A - Cleaning method - Google Patents

Abstract

PURPOSE:To effectively clean processing objects within a small space and improve quality of the processing objects. CONSTITUTION:An exhaust pipe 9a and supply pipe 9b for a cleaning process solution 1 are connected to a processing tank 2 the cleaning process solution 1. A cleaning solution spray nozzle 6 for spraying the cleaning solution against a processing object 3 which is immersed into the cleaning process solution 1 is arranged at the upper part of the processing tank 2. Repetition of exhaustion and supply of the cleaning processing solution 1 enables the effective cleaning of the cleaning object 3 within a small space. The processing object 3 is protected from drying condition and from deterioration of quality due to the drying condition by spraying the cleaning solution 7 on the processing object 3 from the cleaning solution spray nozzle 6.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning method, and more particularly, to a cleaning method in which an object to be processed, such as a semiconductor wafer, is immersed in a processing tank containing pure water or a chemical solution.

0002

[Prior Art] Generally, as a method for cleaning semiconductor wafers, there is a method in which the semiconductor wafer is immersed in a cleaning processing solution contained in a processing tank, or a method in which the semiconductor wafer is immersed in the cleaning processing solution in a processing tank. There are known devices in which gas is injected into the processing liquid from the lower part of the processing liquid and the object to be processed is cleaned by bubbling. By performing these cleaning methods, chemicals, impurities, etc. adhering to the surface of the semiconductor wafer are removed, resulting in a clean state, thereby improving the yield.

0003

However, in conventional cleaning methods, when the semiconductor wafer is not in contact with the cleaning solution after the cleaning process, the semiconductor wafer may be exposed to air and dry. , This drying could cause stains on the surface. These stains not only cause problems in appearance, but also pose a risk of deterioration in quality, such as causing defects or inhibiting electrical characteristics. This problem also appears in cleaning methods other than those described above.

[0004] Generally, in order to improve cleaning efficiency, it is necessary to constantly refresh the cleaning solution, and for this purpose, it is necessary to prepare multiple treatment tanks and perform multiple cleaning processes. There is a problem in that providing a treatment tank requires a large amount of space.

The present invention was made in view of the above-mentioned circumstances, and it is possible to prevent the object to be cleaned from drying out, thereby preventing deterioration in the quality of the object to be treated, and to improve cleaning efficiency in a small space. It is an object of the present invention to provide a cleaning method as described above.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the cleaning method of the present invention provides a method for cleaning an object to be processed by immersing the object in a cleaning solution contained in a processing tank. The method is characterized in that the cleaning treatment liquid is drained and supplied at least once, and when the cleaning treatment liquid is drained, the cleaning liquid is injected onto the object to be treated.

In the present invention, the means for cleaning the object to be processed may be any cleaning method as long as the object to be processed is immersed in a cleaning solution; Any method may be used, such as a method in which the object to be processed is immersed in the cleaning treatment liquid, or a method in which the object to be treated is immersed in the cleaning treatment liquid and air is injected from the bottom to perform bubbling.

[0008] As means for spraying the cleaning liquid, it is possible to use a nozzle disposed at the top of the processing tank, and although this nozzle may be permanently installed at the top of the processing tank, it is preferable to It is preferable that the switch be movable so that it is located above the object to be processed only when in use, and waits outside the processing tank when not in use. In this case, the nozzle may be operated in an ON or OFF mode, injecting the cleaning liquid onto the object to be treated when the cleaning treatment liquid is drained, and stopping spraying the cleaning liquid at other times; however, when the operation is stopped, the cleaning liquid supply source and the nozzle are It is more preferable to take measures to prevent the propagation of bacteria in the cleaning liquid remaining in the conduit between the ON/OFF switching means disposed between the nozzle and the nozzle.

[0009]

[Operation] According to the present invention configured as described above, when cleaning the object by immersing the object in the cleaning solution contained in the processing tank, the cleaning solution is applied at least once. By draining and supplying the liquid as described above, new cleaning treatment liquid can be constantly used in a small space, so that the object to be treated can be cleaned efficiently. In addition, by spraying the cleaning liquid onto the object to be processed when draining the cleaning treatment liquid, the object to be processed is prevented from being exposed to the air and dried, thereby preventing quality deterioration of the object to be processed due to drying. can do.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a schematic cross-sectional view of a cleaning apparatus for carrying out the cleaning method of the present invention.

The cleaning device includes a processing tank 2 that stores a cleaning processing liquid 1 such as pure water, and a processing tank 2 that moves up and down to clean semiconductor wafers 3 (hereinafter referred to as wafers) as objects to be processed using the cleaning processing liquid in the processing tank 2. a wafer holding arm 4 immersed in the cleaning solution 1; an aeration pipe 5 disposed at the bottom of the processing tank 2 and injecting N2 gas supplied from a nitrogen (N2) gas supply source (not shown) into the cleaning processing solution 1; The main parts are composed of a cleaning liquid spray nozzle 6 (hereinafter referred to as a nozzle) arranged at the upper part of the processing tank 2 and a cleaning liquid storage tank 8 that supplies pure water 7, which is a cleaning liquid, to the nozzle 6.

The processing tank 2 includes an inner tank 2a containing the cleaning processing liquid 1, and an inner tank 2a provided around the upper part of the inner tank 2a.
It consists of an outer tank 2b that catches the cleaning treatment liquid 1 overflowing from the upper end, and a drainage pipe 9a for draining the cleaning treatment liquid 1 and a supply line at the bottom of the inner tank 2a. Supply pipe line 9b
are connected, and the cleaning treatment liquid 1 in the processing tank 2 is drained and supplied from a cleaning treatment liquid supply source (not shown) through these drainage and supply pipes 9a and 9b. Therefore, since cleaning can be performed by replacing the cleaning treatment liquid 1 in one treatment tank 2, space can be used effectively.

For example, a plurality of nozzles 6 are installed on the lower surface of a cleaning pipe 13 attached to the lower end of a switching arm 12 connected to a drive shaft 11 of a position switching motor 10 and hanging down to one side of the upper part of the processing tank 2. The pure water 7 is sprayed in the form of a mist or shower over the entire surface of the wafer 3 during cleaning, and when not being cleaned, the switching arm 12 rotates by the drive of the position switching motor 10, and the pure water 7 is sprayed onto the outer tank 2b. The wafer 3 is switched to the standby position and evacuated so as not to interfere with the loading and unloading of the wafer 3 (see FIG. 2).

The nozzle 6 and the cleaning liquid storage tank 8 are connected through a supply line 14, and a bypass line 15 is connected in parallel to a part of the supply line 14. Further, a switching valve 16 for switching between four ports and two positions is provided in the supply pipe line 14 and the bypass pipe line 15, so that the supply pipe line 14 and the bypass pipe line 15 are selectively connected. . Furthermore, a throttle valve 17 is provided in the bypass line 15, and the flow rate of the pure water 7 flowing through the bypass line 15 is set to be small.

In the cleaning apparatus configured as described above, when cleaning the wafer 3, as shown in FIG.
is located above the wafer 3, the supply pipe 14 is connected by the switching valve 16, and the cleaning liquid storage tank 8 is connected.
The pure water 7 inside is sprayed from the nozzle 6 onto the entire surface of the wafer 3. In addition, when not cleaning, as shown in FIG. 2, the bypass pipe 15 is connected by the switching valve 16 with the nozzle 6 located at the upper side of the outer tank 2b, and the pure water 7 in the cleaning liquid storage tank 8 is A small amount of pure water 7 passes through the throttle valve 17 and drops from the nozzle 6 into the outer tank 2b. Therefore, the pure water 7 does not remain between the switching valve 16 and the nozzle 6, and it is possible to prevent the cleaning liquid from turning into dead water and breeding bacteria.

It should be noted that on the outer periphery of the cleaning liquid storage tank 8,
For example, three capacitive sensors 18 are arranged,
This sensor 18 can detect the storage state (liquid amount) of the pure water 7 in the cleaning liquid storage tank 8 without coming into contact with the pure water 7. Therefore, compared to an optical sensor that detects the liquid level by contacting with pure water 7, the lifespan of the sensor can be increased, and the proliferation of bacteria due to light can be prevented. Note that if the cleaning liquid storage tank 8 is made of non-metallic material, the amount of pure water 7 can be detected even if it is non-transparent. That is, capacitive sensor 1
8 may be made of any material as long as it operates properly.

Next, the case where the cleaning method of the present invention is used for cleaning the wafer 3 will be explained with reference to FIG.

First, for example, a plurality of wafers 3 are held upright on the wafer holding arm 4 at the same time, and then the wafer holding arm 4 is lowered and the cleaning processing liquid 1 stored in advance in the processing tank 2 is removed.
The wafer 3 is immersed therein. Then, the N2 gas supplied from the N2 gas supply source is injected into the cleaning treatment liquid 1 from the aeration pipe 5 to generate bubbles, and bubbling with the bubbles is performed for a predetermined period of time, thereby cleaning the surface of the wafer 3 for the first time. is performed (see FIG. 3(a)). At this time, the nozzle 6 is on standby above the outer tank 2b, and a small amount of pure water 7 is dripped into the outer tank 2b.

After the first cleaning, the valve (not shown) of the drain pipe 9a is opened, and the cleaning liquid 1 in the treatment tank 2 is drained.
(see Figure 3(b)), and after draining the supply pipe 9b.
When draining the liquid, the nozzle 6 is moved to a position above the wafer 3, and the switching valve 16 is switched to supply pure water 7 in the cleaning liquid storage tank 8. is sprayed from the nozzle 6 onto the entire surface of the wafer 3 to prevent the wafer 3 from drying (see FIG. 3(c)). This jetting of the pure water 7 from the nozzle 6 is continued until the inner tank 2a of the processing tank 2 is filled with the cleaning processing liquid 1.

After the inner tank 2a is filled with the second cleaning treatment liquid 1, the nozzle 6 is placed on standby above the outer tank 2b, and then N2 gas is injected from the diffuser pipe 5 in the same manner as above. After that, the same operation is repeated to clean the wafer 3.

Therefore, even when the cleaning liquid 1 is drained, the wafer 3 is not exposed to air and is always in contact with the cleaning liquid 1 or pure water 7, so that it does not dry out and cause stains.

In the above embodiment, the cleaning method of the present invention was explained for cleaning the wafer 3, but it is not necessarily limited to cleaning the wafer 3. It can also be applied to a method of washing by immersing it in water.

[0024]

As explained above, according to the cleaning method of the present invention, since it is configured as described above, it is possible to constantly use new cleaning processing liquid in a small space, and it is also possible to The processing body can be efficiently cleaned. Moreover, since the cleaning liquid is sprayed onto the object to be processed when the cleaning treatment liquid is drained, it is possible to prevent the object to be processed from being exposed to the air and drying out, thereby preventing the quality of the object to be degraded due to drying. Excellent effects such as being able to do this can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a cleaning device according to the present invention.

FIG. 2 is a schematic cross-sectional view showing the cleaning liquid spray nozzle in the present invention when it is not in use.

FIG. 3 is a schematic cross-sectional view illustrating the steps of the cleaning method of the present invention.

[Explanation of symbols]

1　Cleaning treatment liquid 2 Processing tank 3 Semiconductor wafer (object to be processed) 6 Cleaning liquid spray nozzle 7　Pure water (cleaning liquid) 9a　Drainage pipe line 9b Supply pipeline

Claims (1)

[Claims] Claim 1: When cleaning an object by immersing the object in a cleaning solution stored in a processing tank, draining and supplying the cleaning solution at least once, A cleaning method characterized in that when draining the treatment liquid, a cleaning liquid is injected onto the object to be treated.