JP2002025962A - Cleaning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a cleaning device used in a semiconductor manufacturing process to be decreased in floor space and to be prevented from deteriorating the upper part of its cleaning tank in cleaning performance. SOLUTION: An overflow tank 22 into which a cleaning solution flowing out from a cleaning tank 2 is made to flow is disposed on the upper end of the inner wall of a cleaning tank 2 which is filled with a cleaning solution and where substrates are freely housed, where the bottom face of the outer wall of the overflow tank 22 is so formed as to make a prescribed angle with the inner wall of the cleaning tank 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning apparatus for immersing a substrate in a cleaning liquid and performing ultrasonic cleaning.

[0002]

2. Description of the Related Art In a manufacturing process of a semiconductor device such as an LSI, a cleaning liquid is used as a cleaning method for removing contamination (contaminants) such as particles, organic contaminants, and metal impurities attached to the surface of a semiconductor wafer. There is known a method in which a semiconductor wafer is immersed in a filled cleaning tank and an ultrasonic vibration is applied to the cleaning liquid. According to this method, a cavity is generated in a cleaning solution by ultrasonic vibration, and an adhering substance on the surface of a semiconductor wafer is removed by an impact force at the time of destruction (cavitation) of the cavity. ing.

FIG. 3 is a cross-sectional view showing the periphery of a cleaning tank in a conventional cleaning apparatus for performing cleaning using such ultrasonic vibration. The cleaning tank 30 is a box-shaped container having a size large enough to accommodate a cleaning target 31 such as a semiconductor wafer from above, and is filled with a cleaning liquid. An overflow tank 32 for receiving a cleaning liquid overflowing from the upper end of the cleaning tank 30 is provided at an outer upper end of the cleaning tank 30.
Are provided so as to surround the opening. Cleaning tank 3
An ultrasonic vibration device 33 that generates ultrasonic vibration by driving the vibration plate 33a is installed below the zero.

The cleaning process in the cleaning tank 30 is as follows. First, for example, a plurality of semiconductor wafers or the like as the object to be cleaned 31 is cleaned by a transfer device (not shown).
And is held by a holding device (not shown) installed in the cleaning tank 30. From this state, the diaphragm 33a
Is driven, a cavity 30a is generated in the cleaning liquid, and the cavity 30a is destroyed in the middle of ascending, and the extraneous matter on the surface of the cleaning object 31 is shaken off by the impact force at the time of destruction. The adhering matter that has come off from the object to be cleaned 31 floats in the cleaning liquid together with the flow of the cavity 30a, and flows into the overflow tank 32 together with the cleaning liquid overflowing from the upper end of the cleaning tank 30.
The cleaning liquid that has flowed into the overflow tank 32 is pumped and cleaned by a pump (not shown), and is supplied again to the cleaning tank 30 from a nozzle (not shown) provided in the cleaning tank 30.

[0005]

In the conventional cleaning tank 30 used for cleaning the semiconductor device as described above, the overflow tank 32 for receiving the overflow of the cleaning liquid is provided with the cleaning tank 30 as shown in FIG. It was provided on the outside as an outer tank. However, in such an installation method, the horizontal size of the cleaning tank 30 is increased by the amount of the overflow tank 32. In the case of a semiconductor wafer cleaning apparatus, many cleaning tanks 30 are often arranged, and such a cleaning apparatus requires a large space for installing the entire apparatus. For this reason,
In order to reduce the installation space, a method of changing the type of cleaning liquid to be used or the cleaning recipe to reduce the number of cleaning tanks 30 to be used, and the like, are performed. There have been problems such as not being able to be obtained or a long cleaning time.

In the cleaning tank 30 using ultrasonic waves as described above, the diaphragm 33a is generally installed below the cleaning tank 30, but the cavity 30a generated by the ultrasonic waves oscillated from the diaphragm 33a The density of the cavity 30a in the cleaning liquid decreases as the distance from the diaphragm 33a increases as the distance from the diaphragm 33a increases because the liquid disappears during the ascent in the cleaning liquid. For this reason, in the ultrasonic cleaning in which the cleaning is performed by the impact force when the cavity 30a disappears, there is a problem that the cleaning effect decreases as the position is higher than the cleaning tank 30.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a cleaning apparatus used in a semiconductor manufacturing process, in which an installation space is reduced and a cleaning ability is not reduced even in an upper portion of a cleaning tank. The purpose is to provide.

[0008]

In order to solve the above-mentioned problems, the present invention provides a cleaning apparatus for immersing a substrate in a cleaning liquid and performing ultrasonic cleaning, comprising: a cleaning tank capable of storing the substrate filled with the cleaning liquid; A cleaning tank, wherein the cleaning liquid overflowing from the cleaning tank flows into the cleaning tank, and an inner tank is disposed at an upper end of an inner wall of the cleaning tank.

In such a cleaning apparatus, the space for receiving the overflow from the cleaning tank is provided as an inner tank inside the cleaning tank, so that the horizontal size of the cleaning tank is reduced, and the installation space for the cleaning apparatus is reduced. Can be reduced. Further, when the inner tank has a shape in which the lower portion of the outer surface forms a predetermined angle from the inner wall of the washing tank to the upper inside direction, the space filled with the washing liquid becomes narrower as approaching the upper opening. In addition, the density of the cavity in the cleaning liquid generated by driving the ultrasonic generator installed in the lower part of the cleaning tank can be made uniform, and the cleaning ability does not decrease even in the upper part of the cleaning tank.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a plan view showing a schematic configuration of the cleaning device of the present invention.

The cleaning apparatus 1 is used in a manufacturing process of a semiconductor device such as an LSI, and is an apparatus for removing contamination such as particles, organic contaminants, and metal impurities attached to the surface of a semiconductor wafer by ultrasonic cleaning. is there. The cleaning apparatus 1 includes a cleaning tank 2 filled with a cleaning liquid, a loader 3 on which a body to be cleaned before cleaning is placed, an unloader 4 on which a body to be cleaned after cleaning is placed, and a body to be cleaned. It is constituted by a transfer device 5 for transferring. As shown in FIG. 2, for example, a plurality of cleaning tanks 2 are provided. Each of the cleaning tanks 2 is filled with various liquids such as various chemicals and pure water to remove organic contaminants, remove metal ions, and rinse cleaning. In general, different cleaning processes are performed on the object to be cleaned in the respective cleaning tanks 2 as described above. The number of the cleaning tanks 2 to be arranged and the type of the cleaning liquid to be filled are arbitrarily determined. In addition, the transport device 5 includes a guide 5a.
And a movable wafer chuck (not shown) for holding the object to be cleaned. The number of the transfer device 5 is not limited to one, and a plurality of transfer devices may be provided.

In the cleaning process using the cleaning device 1, first, a predetermined number of semiconductor wafers are placed on the loader 3, for example, in an aligned manner, and the transfer device 5 is stopped immediately above the loader 3, and The semiconductor wafer is gripped and lifted by the wafer chuck, and slides on the guide 5a to the cleaning tank 2 side. When the transfer device 5 stops on the first cleaning tank 2, the wafer chuck is lowered to immerse the semiconductor wafer in the cleaning liquid filled in the cleaning tank 2. In the cleaning tank 2, for example, a holding device (not shown) for holding the semiconductor wafers in an upright state and keeping them aligned at equal intervals is provided, and the semiconductor wafer carried into the cleaning liquid is transferred from the wafer chuck to the holding device. After the wafer is delivered and held, and the wafer chuck is retracted upward, ultrasonic cleaning is performed to remove excess deposits on the semiconductor wafer.

When a predetermined time has elapsed and the washing is completed,
The wafer chuck of the transfer device 5 descends again to take out the semiconductor wafer and transfer it to the next cleaning tank 2. in this way,
The transfer device 5 sequentially transfers the semiconductor wafers to be cleaned to each of the arranged cleaning tanks 2, and performs ultrasonic cleaning using a filled predetermined cleaning liquid in each of the cleaning tanks 2. After the last cleaning in the cleaning tank 2 is completed, the transfer device 5 aligns and places the semiconductor wafer at a predetermined position on the unloader 4, and thereafter, the semiconductor wafer is dried and the cleaning process is performed. It ends.

Next, FIG. 1 shows a sectional view of a cleaning tank 2 in a cleaning apparatus 1 of the present invention. Note that all of the plurality of cleaning tanks 2 installed in the cleaning apparatus 1 have the same configuration, and therefore only one of them will be described with reference to FIG.

The cleaning tank 2 includes a cleaning target 2 such as a semiconductor wafer.
A box-shaped container large enough to accommodate 1
The cleaning liquid is filled therein. The upper portion of the cleaning tank 2 is open, and the object to be cleaned 21 is carried into the cleaning tank 2 through the opening on the upper surface. At the upper end of the inner wall of the cleaning tank 2, an overflow tank 22 for receiving the cleaning liquid overflowing from the upper end of the cleaning tank 2 is provided.
Is provided so as to surround the opening. The overflow tank 22 has a shape in which the lower surface of the outer tank wall is angled from the inner wall surface of the washing tank 2 toward the upper inside of the tank, and the overflow tank 22 is filled with the washing liquid. The inner diameter of 2 is narrower at the top as it approaches the opening. Further, an ultrasonic vibration device 23 for generating ultrasonic vibration by the vibration of the vibration plate 23a is provided below the cleaning tank 2.

In the cleaning tank 2, for example, a cleaning target 21 composed of a predetermined number of aligned semiconductor wafers is provided.
The wafer is held by the wafer chuck of the transfer device 5, carried into the cleaning tank 2, transferred to a holding device (not shown) installed in the cleaning tank 2, and held in parallel at predetermined regular intervals. Thereafter, the wafer chuck of the transfer device 5 is moved to the cleaning tank 2.
And the ultrasonic vibration device 23 operates to vibrate the diaphragm 23a. In the cleaning liquid filled in the cleaning tank 2, a cavity 2a is generated by ultrasonic vibration emitted from the vibration plate 23a, and the cavity 2a is destroyed during ascending, and an object to be cleaned is generated by an impact force at the time of destruction. Excess deposits on the surface of 21 are shaken off.
The adhering matter that has come off from the object to be cleaned 21 rises in the cleaning solution together with the flow of the cavity 2 a, overflows with the cleaning solution overflowing from the upper end of the cleaning tank 2, and flows into the overflow tank 22. The cleaning liquid that has flowed into the overflow tank 22 is pumped and cleaned by a pump (not shown), and is supplied to the cleaning tank 2 again from a nozzle (not shown) provided in the cleaning tank 2. When the extraneous matter on the object to be cleaned 21 is removed by the above processing, the wafer chuck of the transfer device 5 descends again into the cleaning tank 2, holds the object to be cleaned 21, and rises to the next cleaning tank. 2 or unloader 4.

In this cleaning tank 2, an overflow tank 22 for receiving an overflowing cleaning liquid, which is conventionally provided outside the cleaning tank, is provided inside the cleaning tank 2. By selecting a suitable minimum size diaphragm 23a, the cleaning tank 2
In the horizontal direction can be minimized, and the installation space of the cleaning apparatus 1 used by arranging a plurality of such cleaning tanks 2 in parallel can be reduced as compared with the related art. .

A diaphragm 23a for generating ultrasonic waves is provided at the lowermost portion.
Since a rises and disappears on the way, the density of the cavity 2a in the cleaning liquid decreases as going upward. In such an ultrasonic cleaning in which the cleaning is performed by the impact force when the cavity 2a disappears, the cleaning effect becomes lower as the position is higher than the cleaning tank 2. However, at the upper end of the inner wall of the cleaning tank 2, an overflow tank 2 having an angle on the lower surface from the inner wall surface of the cleaning tank 2 toward the upper inside of the tank.
2, the flow of the cavity 2a in the cleaning tank 2 is narrowed down by the outer wall of the overflow tank 22 to make the flowing cavity 2a dense. Thereby, in the cleaning tank 2, the density of the cavity 2a in the cleaning liquid is maintained to a certain level in the entire tank, and a decrease in the cleaning capacity in the upper part of the tank is prevented. Further, due to the angle given to the lower surface of the overflow tank 22, the rising flow of the cavity 2a does not stay even if the inner diameter is gradually narrowed. Kimono can be efficiently raised and overflowed. As described above, the cleaning tank 2 has a uniform cleaning capability over the entire area in the tank, and can perform efficient cleaning.

[0019]

As described above, since the space for receiving the overflow from the cleaning tank of the present invention is provided as an inner tank inside the cleaning tank, the horizontal size of the cleaning tank is reduced, and the cleaning apparatus is provided. Installation space can be reduced. When the inner tank has a shape in which the lower part of the outer surface forms a predetermined angle from the inner wall of the washing tank toward the upper inside, the space filled with the washing liquid becomes narrower as approaching the upper opening. In the cleaning liquid, a cavity is generated by the driving of the ultrasonic generator installed at the lower part of the cleaning tank, and this cavity disappears on the way up, so that the density of the cavity in the cleaning liquid decreases as going upward. However, since the density of the cavity is increased in the portion where the inner diameter of the cleaning tank is narrowed by the lower part of the inner tank, it is possible to prevent a decrease in the cleaning capacity in the upper part of the cleaning tank.

[Brief description of the drawings]

FIG. 1 shows a sectional view of a cleaning tank in a cleaning apparatus of the present invention.

FIG. 2 is a plan view showing a schematic configuration of a cleaning apparatus of the present invention.

FIG. 3 is a cross-sectional view showing the periphery of a cleaning tank in a conventional cleaning apparatus.

[Explanation of symbols]

1 ... cleaning device, 2 ... cleaning tank, 2a ... cavity,
3 ... loader, 4 ... unloader, 5 ... transfer device, 5
a: wafer chuck, 21: body to be cleaned, 22: overflow tank, 23: ultrasonic vibrator, 23a ...
Diaphragm

Claims (3)

[Claims] 1. A cleaning apparatus for performing ultrasonic cleaning by immersing a substrate in a cleaning liquid, wherein a cleaning tank capable of storing the substrate filled with the cleaning liquid, the cleaning liquid overflowing from the cleaning tank flows, and the cleaning is performed. A cleaning device, comprising: an inner tank disposed at an upper end of an inner wall of the tank. 2. The cleaning device according to claim 1, wherein a lower surface of an outer wall of the inner tub forms a predetermined angle in an upper inner direction from an inner wall of the cleaning tub. 3. The cleaning apparatus according to claim 1, comprising a plurality of said cleaning tanks and said inner tanks.