JP2926757B2 - Overflow circulation system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to an overflow circulation system used for immersing a semiconductor substrate in a chemical solution or pure water for wet processing.

[Conventional technology]

Conventionally, this type of overflow circulation system has
As shown in FIG. 2, an air-driven diaphragm pump
The liquid in the outer tank 3 constituting the overflow tank was sent to the filter 10 by the 12 or air-driven bellows pump and passed therethrough.

That is, the liquid stored in the outer tank 3 is sent to the inner tank 11 constituting the overflow tank through the filter 10 by the air-driven diaphragm pump 12, and the semiconductor substrate is immersed in the inner tank 11 for processing. Was composed.

[Problem to be Solved by the Invention] The above-mentioned conventional overflow circulation system is
Since an air-driven diaphragm pump or an air-driven bellows pump is used, (1) dust is generated from the diaphragm or the bellows, (2) the life of the diaphragm or the bellows is short, and (3) the pulsation is large. There are drawbacks such as poor performance and (4) difficulty in sending high-temperature liquid.

[Means for solving the problem]

An overflow circulation system according to the present invention includes an overflow tank composed of an inner tank and an outer tank, a plurality of liquid storage tanks connected by piping to the inner tank and the outer tank, and having a larger capacity than the inner tank, and an airtight structure. A pressurizing chamber for separately storing the liquid storage tanks, pressurizing means for pressurizing the inside of the pressure chamber, an excess means provided in a pipe between the liquid storage tank and the internal tank, and the liquid storage tank And a liquid level sensor for detecting a liquid level in the inside.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view of one embodiment of the present invention. The overflow tank 1 is composed of an outer tank 3 and an inner tank 11, in which a semiconductor substrate is immersed in the inner tank 11.

Two liquid storage tanks 4a and 4b made of resin are connected to the outer tank 3 and the inner tank 11 by piping, and these are connected to the liquid storage tanks 4a and 4b.
Are housed in metal pressurized chambers 6a and 6b having an airtight structure, and are individually pressurized by compressed air 13. A filter 10 is provided in a pipe between the liquid storage tanks 4a, 4b and the inner tank 11, and upper and lower liquid level detection sensors 8a, 8b and 9a, 9b are provided outside the liquid storage tank. Is provided.

The three-way valve 2 supplies the liquid in the outer tank 3 to either the liquid storage tank 4a or the liquid storage tank 4b.
5b is for sending the compressed air 13 to the pressurizing chambers 6a and 6b, respectively, or for releasing the compressed air to the atmosphere. The three-way valve 7 is for preventing one of the liquids in the liquid storage tanks 4a and 4b from flowing out, and preventing the other liquid from flowing out. The upper limit liquid level sensors 8a and 8b detect the upper limit position of the liquid level of the storage tanks 4a and 4b, respectively, and output a signal, and the lower limit liquid level sensors 9a and 9b respectively detect the liquid level of the storage tanks 4a and 4b. It detects the lower limit position of the surface and outputs a signal. Filter 10
Is for passing the liquid flowing out of the three-way valve 7 and sent to the inner tank 11 of the overflow tank.

Next, a description will be given of a movement from a state where there is no liquid in the present embodiment configured as described above to a steady state when the semiconductor substrate is immersed.

First, the liquid is supplied to the outer tank 3 of the overflow tank. The liquid stored in the outer tank 3 passes through the three-way valve 2 and enters the liquid storage tank 4a. At that time, the three-way valve 7 is in a state where the liquid in the liquid storage tank 4b can flow out.
Is in a state where it cannot flow out, and the three-way valve for air 5a and
Reference numeral 5b denotes a state in which the supply of the compressed air 13 is shut off and both the pressurizing chambers 6a and 6b are opened to the atmosphere. Then the storage tank
When the liquid level of 4a rises and the upper limit liquid level sensor 8a detects the liquid level and outputs a signal, the three-way valve 2 and the three-way valve 7 are switched, and the supplied liquid flows into the liquid storage tank 4b and rises. I do. Next, when the upper limit liquid level sensor 8b detects the liquid level, the supply of the liquid to the outer tank 3 is stopped. This completes the liquid supply to the overflow circulation system. The switching of the three-way valves 2 and 7 may be performed by an operator based on a signal from the liquid level detection sensor, or may be automatically performed by connecting a sequencer between the liquid level detection sensor and the valve.

Next, a description will be given of a movement up to a steady state when the semiconductor substrate is immersed.

First, switch the three-way valve 5a for air, and pressurize the chamber.
Press 6a. At that time, the three-way valve 7 is in a state in which the liquid in the liquid storage tank 4a can flow out.
Flow into 11. When this state is continued, the liquid level in the liquid storage tank 4a drops, and drops to a position where the lower limit liquid level sensor 9a detects the liquid level. At this time, since the capacity of the liquid storage tank 4a is larger than the capacity of the inner tank 11, the inner tank 11 is filled with the liquid and overflows to the outer tank 3.

Also, at this timing, the three-way valves for air 5a and 5b,
The three-way valves 2 and 7 are switched, the pressure chamber 6a is opened to the atmosphere, and the liquid flowing from the outer tank 3 is stored in the liquid storage tank 4a. On the other hand, the pressurized chamber 6a is in a pressurized state, and the liquid in the liquid storage tank 4b is sent to the inner tank 11 via the three-way valve 7 filter 10. Then, when the liquid level of the liquid storage tank 4b drops to the position where the lower limit liquid level detection sensor 9b detects, the three-way valves 5a and 5b for air and the three-way valves 2 and 7 are switched again to perform the reverse movement.

Thereafter, by repeating this movement, the liquid for processing the semiconductor substrate circulates.

As described above, according to the present embodiment, since the liquid is circulated by the compressed air, it is possible to eliminate defects such as dust generation when using an air-driven bellows pump or a diaphragm pump as in the related art.

In the above embodiment, the case where a resin storage tank and a metal pressurized chamber are used has been described, but the liquid storage tank and the pressurized chamber may be integrated with a resin. Further, an inert gas such as nitrogen may be used instead of air as the pressurized gas.

〔The invention's effect〕

As described above, the present invention is provided with a plurality of liquid storage tanks connected to the inner tank and the outer tank constituting the overflow tank, and a pressurized chamber having an airtight structure for storing the liquid storage tanks, such as compressed air. By sending and circulating the liquid in the liquid storage tank by pressurizing means, particle reduction, failure rate reduction,
This has the effect of improving the particle removal performance of the filter by reducing the size of the artery and making it possible to feed a high-temperature liquid.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of one embodiment of the present invention, and FIG. 2 is a schematic diagram of a conventional overflow circulation system. 1 ... overflow tank, 2,7 ... three-way valve, 3 ... outer tank, 4a, 4b ... liquid storage tank, 5a, 5b ... three-way valve for air, 6a, 6
b… Pressurized chamber, 8a, 8b …… Upper limit liquid level detection sensor, 9a, 9b …… Bottom liquid level detection sensor, 10 …… Filter, 11 …… Inner tank, 12 …… Air driven diaphragm pump, 13 …… Compressed air.

Claims (2)

(57) [Claims] 1. An overflow tank comprising an inner tank filled with a processing liquid and an outer tank receiving the processing liquid overflowing from the inner tank, first and second storage tanks, and the first and second storage tanks. Means for supplying the processing liquid stored in the outer tank to the other storage tank in response to the processing liquid stored in one of the liquid tanks reaching an upper limit water level; In response to the processing liquid stored in one of the storage tanks reaching the lower limit water level, the other storage tank is pressurized and the processing liquid stored therein is supplied to the inner tank via a filter. Means for performing an overflow circulation filtration. 2. The overflow circulating filtration system according to claim 1, wherein the capacity of the first and second storage tanks is larger than the capacity of the inner tank.