JPH03200327A - Washer for semiconductor wafer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for cleaning the surface of a semiconductor wafer, and particularly to the structure of the cleaning apparatus.

[Conventional technology]

A conventional cleaning tank for carrying out this type of cleaning will be explained with reference to FIG.

FIG. 3 is a diagram showing a conventional cleaning tank, in which 1 is a semiconductor wafer, 2 is a cleaning tank, and 3 is a cleaning liquid. The shape of the cleaning tank 2 is usually rectangular, and the wafer is immersed in the cleaning liquid in this tank. In addition, in order to enhance the cleaning effect, it was sufficient to apply ultrasonic energy and perform cleaning.

However, as integrated circuits become finer, as in the dynamic RAM shown in Figure 4, the irregularities on the wafer surface become larger (as typified by trenches, for example), and it becomes necessary to clean every corner of these irregularities. Therefore, it is impossible to fill the holes with cleaning solution by simply immersing the wafer in a cleaning tank as shown in FIG. 3 under normal pressure.

Therefore, in cleaning the trench grooves as shown in FIG. 4, it is conceivable to immerse the wafer in a cleaning liquid under reduced pressure, and then apply normal pressure or even higher pressure to fill the cleaning liquid into the finer details of the trench grooves for complete cleaning.

[Problem to be solved by the invention]

However, a device for immersing a wafer in such a reduced pressure state has not been realized so far.

This invention was made in order to solve the problems of the conventional ones as described above, and it is possible to realize a device that supplies cleaning liquid to a wafer under reduced pressure, and also to suppress the generation of mist when the pressure is reduced. The purpose is to obtain a cleaning device for semiconductor wafers.

[Means to solve the problem]

The semiconductor wafer cleaning apparatus according to the present invention has a two-layer structure consisting of a cleaning tank and a cleaning liquid storage tank in order to realize a reduced pressure state in the cleaning tank, and the cleaning liquid supply system and drainage system are constantly filled with N2 or pure water. The system is kept clean by rinsing, and the drainage system and vacuum exhaust system are shared for the cleaning tank to keep the vacuum exhaust system clean.

[Effect]

In this invention, the cleaning liquid supply system, drainage system, and vacuum exhaust system can be kept clean with respect to the cleaning tank, and dirt on the wafer in the cleaning tank can be prevented, especially airflow turbulence caused by changes in vacuum and normal pressure. , and the generation of mist can be prevented. Moreover, by separating the cleaning tank and the liquid storage tank, the cleaning liquid can be used repeatedly, and the amount of cleaning liquid used can be reduced.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a semiconductor wafer cleaning apparatus according to an embodiment of the present invention. In this embodiment, the configuration of the cleaning tank A is
As shown in the figure, the outer tank 11 and N13 can form a sealed structure, and the outer tank 11 has an inner tank 12 inside.
It is in a heavy tank.

Further, a supply port 14 for supplying cleaning liquid or pure water is provided in the inner lower part of the inner tank 12. The cleaning liquid overflowing the inner tank 12 passes through the outer tank 11 and is discharged from the tank through the drain 34. The wafer 1 to be cleaned is placed in the inner bath 12 and will be cleaned.

Next, the operation and function of the cleaning device will be explained using the cleaning sequence shown in FIG. 2 as an example.

■ After storing the wafer 1 in the inner tank 12, open the outer tank 1 with the lid 13.
1, and the cleaning tank A is made airtight (step SL).

(2) Connect the outer tank 11 and the inner tank 12 to the vacuum pump 38 using the three-way valves 24, 25, and 26, and reduce the pressure in both the outer tank 11 and the inner tank 12 (several 100 tons to several tons or less) (step S2).

(2) Close the three-way valves 24 and 25, connect the cleaning liquid storage tank B and the cleaning tank A using the three-way valve 23, and supply the cleaning liquid from tank B to the inner tank 12 (step S3).

- With the cleaning liquid overflowing the inner tank 12 or completely immersing the wafer 1, close the valve 23 and open the valve 21.
Inner tank 12. Fill the outer tank 11 with an inert gas such as Nz,
Bring to normal pressure. At this time, the uneven portions (including the trench grooves) on the surface of the wafer 1 are completely covered with the cleaning liquid.

After that, the outer tank 11 and the liquid storage tank B are connected by the three-way valve 25, and the cleaning liquid overflowing from the inner tank 12 to the outer tank 11 is transferred to the liquid storage tank B.
Return to Further, the valve 23 connects the liquid storage tank B and the inner tank 12 of the cleaning tank A, and the pressure pump 40 is used to constantly supply filtered cleaning liquid from the liquid storage tank B to the inner tank 12, and from the outer tank 11 to the inner tank 12. The return to the liquid tank B is repeated, and the surface of the wafer 1 is constantly cleaned with a clean cleaning liquid (step S4).

■ Close the 3-way valve 23, stop the liquid supply from the liquid storage tank B to the inner tank 12, open the 3-way valve 24, open the valve 21, and turn the N
! Wash! ! The cleaning liquid in the inner tank 12 and the outer tank 11 is returned to the liquid storage tank B. At this time, it is necessary to completely expel the cleaning liquid from the pipe 32 by supplying Nt from the pipe 32 to the inner tank 12 using the valves 22 and 23 (step S5).

■ Stop N2 with valve 21, stop inner tank 12 and liquid storage tank B with valve 25, and supply pure water to inner tank 1 with valves 22 and 23.
Supply to 2. Furthermore, the outer tank 11 is connected to the drain 12 by means of valves 24,26. The pure water flows in the order of the inner tank 12 → outer tank 11 → drain port, and the wafers 1 in the inner tank 12 are rinsed with the pure water (step S6).

(2) The valve 21 supplies N2 to the outer tank 11, the valve 22 stops the supply of pure water to the inner tank 12, and supplies N2. connecting the inner tank 12 to the drain 12 by means of valves 25 and 27;
Inner tank 12. The pure water in the outer tank 11 is drained to the drain port (step 37).

■ N to cleaning tank A by valves 21 and 23.

The supply is stopped and the inner tank 12. Connect outer tank 11 to vacuum pump 38. Cleaning tank A is brought to a reduced pressure state,
The pure water remaining in tank A and the surface of wafer 1 is evaporated to dry wafer 1 (step S8).

(2) Close the valves 24 and 25, open the valve 21, supply N2 to the cleaning tank A, return the inside of the tank to normal pressure, open the lid 13, and take out the cleaned and dried wafer (step 39).

■ The subsequent drying process can also be performed using a separate drying device.

〔Effect of the invention〕

As explained above, according to the cleaning device according to the present invention,
The dual structure of a cleaning tank and a cleaning liquid storage tank allows the cleaning liquid to be supplied to the wafer surface under reduced pressure, allowing the cleaning liquid to cover the entire wafer surface (including the trenches), ensuring complete cleaning. becomes possible.

Also, keep the system clean by constantly rinsing the cleaning liquid supply system and drainage system with N2 or pure water, and keep the vacuum exhaust system clean by using the same drain system and vacuum exhaust system for the cleaning tank. Therefore, the cleaning liquid supply pipe and the drain pipe can be incorporated into the sequence of always washing with pure water, and the clean state can be maintained.

Furthermore, since the drain pipe and vacuum tube can be shared for the cleaning tank, there is no excess liquid reservoir and no cleaning liquid mist is generated.

Furthermore, since the vacuum tube can be cleaned with pure water, it is possible to prevent the generation of cleaning liquid mist due to pressure fluctuations between reduced pressure and normal pressure.

Furthermore, since cleaning liquid can be prevented from entering the vacuum pump, deterioration of the vacuum pump can be prevented.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a semiconductor wafer cleaning apparatus according to an embodiment of the present invention, FIG. 2 is a diagram showing an example of a cleaning sequence according to the present invention, FIG. 3 is a diagram showing a conventional cleaning apparatus, and FIG. 4 is a diagram showing an example of a cleaning sequence according to the present invention. 1 is a cross-sectional structural diagram of a horizontal capacitor cell including a trench. In the figure, 11 is an outer tank, 12 is an inner tank, 13 is a lid, 14 is a supply port, and 34 is a drain. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (5)

[Claims] (1) In a cleaning device consisting of a cleaning tank and a cleaning liquid storage tank, the cleaning tank is equipped with a pressure reduction means, an inert gas supply means, a cleaning liquid supply means, and a pure water supply means, and the cleaning tank is supplied from the liquid storage tank to the cleaning tank. A cleaning device characterized by having a configuration in which a cleaning liquid is supplied and the treated cleaning liquid is returned from a cleaning tank to a liquid storage tank. (2) The cleaning device according to claim 1, wherein the cleaning tank has a means for supplying cleaning liquid or pure water during depressurization, and is configured to be able to be pressurized with an inert gas at normal pressure or pressurization. Characteristic cleaning equipment. (3) In the cleaning device according to claim 1, the cleaning tank has means for supplying pure water or an inert gas such as N_2 to the cleaning liquid supply pipe, and the cleaning liquid supply pipe can be constantly purged with pure water or N_2. A cleaning device characterized by having a configuration. (4) The cleaning device according to claim 1, characterized by having a pure water discharge means in the cleaning liquid discharge pipe and the vacuum exhaust pipe, so that the cleaning liquid discharge pipe and the vacuum exhaust pipe can be constantly purged with pure water. cleaning equipment. (5) The cleaning device according to claim 4, wherein the cleaning device has a configuration in which a cleaning liquid drain pipe from the cleaning tank and a vacuum exhaust pipe are shared.