JPH06163502A - Method of manufacturing ultrapure water - Google Patents

Abstract

PURPOSE:To produce ultrapure water by bringing water into contact with metallic silicon and removing the metallic ions and colloidal metallic components present in the water by making them adhere to the surface of the metallic silicon. CONSTITUTION:The primary pure water sent forcedly by a pump 1 passes through a UV bacteria killer 2 and enters an ion exchanger resin 3 whereby the heavy metals contained in the primary pure water are removed by adsorption. The water coming from the ion exchange resin container 3 enters the column 4 and comes into contact with the metallic silicon 5 packed in this column 4. Because of this, very small amounts of heavy metal ions and colloidal heavy metal particles still remaining are removed by the a clsorption by the cleaning surface of the metallic silicon 5. After this, the water coming from the column 4 passes through the UF film 6. In this manner, particles of a specific molecular weight or more are removed from the water thereby producing ultrapure water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for further cleaning ultrapure water used for cleaning semiconductor substrates and the like.

[0002]

2. Description of the Related Art Conventionally, in order to obtain ultrapure water for cleaning semiconductor substrates, etc., metal ions are removed from pure water by ion exchange, and then ultrafiltration, a so-called ultrafilter, is used to remove particles having a certain molecular weight or more. Have been removed.

[0003]

However, in the above-mentioned method for producing ultrapure water according to the conventional method, it is impossible to remove a very small amount of metal ions and colloidal metal by ion exchange resin or ultrafiltration. In some cases, the object to be cleaned may be contaminated by cleaning with ultrapure water. Further, in JP-A-4-45530, reference is made to the purification of alkali with silicon powder, and cleaning with dilute hydrofluoric acid is described as a regeneration method. However, if this means is used for metallic silicon, the surface of the metallic silicon is dissolved by the alkali, so that there is a problem that the adsorbed and removed metal is redissolved to cause recontamination of the alkali.

An object of the present invention is to provide ultra pure water having a metal content of ppq (pg / l) or less by providing a method for further removing an extremely small amount of metal ions and colloidal metal from ultra pure water. It is in.

[0005]

In order to solve the above-mentioned problems, the present invention is to bring ultrapure water into contact with metallic silicon, and the metal ions and colloids in the ultrapure water on the clean surface of the metallic silicon. The metal component is adsorbed and removed. In addition, it is advisable to clean the surface of metallic silicon having a reduced adsorption effect on the clean surface with alkali, hydrochloric acid, or ultrapure water to recycle and use it.

[0006]

According to the above means, when the ultrapure water is brought into contact with the metal silicon, the metal ion particles and the colloidal metal component contained in the ultrapure water are adsorbed and removed on the clean surface of the metal silicon. Further, with respect to metallic silicon having a reduced adsorption drop, it is possible to restore the adsorption effect of the surface by washing the surface with alkali, hydrochloric acid or ultrapure water.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of an ultrapure water production line in which the cleaning method of the present invention has been carried out.
A V sterilizer 2 and an ion-exchange resin demener 3 are arranged in this order from the primary side. Further, 4 provided on the secondary side of the ion exchange resin 3 is a column filled with metallic silicon 5 in the form of particles or porous, wafer, or flakes.
A UF membrane (ultrafiltration membrane) is arranged on the secondary side of the. According to the ultrapure water production line described above, the primary pure water pumped by the pump 1 passes through the UV sterilizer 2 and flows into the ion exchange resin 3, whereby the heavy metals contained in the primary pure water are adsorbed and removed. . The ultrapure water that has passed through the ion-exchange resin denominator 3 flows into the column 4 and comes into contact with the metallic silicon 5 filled in the column 4. As a result, a very small amount of heavy metal ions and colloidal heavy metal that cannot be completely removed by the ion exchange resin 3 are adsorbed and removed on the clean surface of the metal silicon 5. Then, the ultrapure water that has passed through the column 4 passes through the UF membrane 6. The UF film 6 removes particles having a certain molecular weight or more from the ultrapure water passing through the UF film 6 to obtain purified ultrapure water.

FIG. 2 shows an ultrapure water production line in which a regenerating apparatus for metal Si is attached to the above production line, and between the denominator 3 and the column 4 in the line constructed similarly to the line shown in FIG. Is connected to dilute hydrochloric acid and alkali feeders 7 and 8 via valves 7a and 8a. In the above production line, the alkali in the alkali supplier 8 is introduced into the column 4 by the pump 8a, and the surface of the metallic silicon 5 filled in the column 4 is slightly removed. Next, the inside of the column 4 is washed with ultrapure water, the diluted hydrochloric acid in the diluted hydrochloric acid supplier 8 is introduced into the column 4 by the pump 7b, and the heavy metal is removed from the surface of the metallic silicon 5. Then, ultrapure water from the ion exchange resin 3 is introduced into the column 4 to wash the metallic silicon 5 in the column 4, and the washing water is distributed from the drain 20 to the outside of the line system. The above process restores the adsorption effect on the surface of the metallic silicon 5.

FIG. 3 shows a cleaning apparatus for cleaning a semiconductor substrate using the ultrapure water produced by the present invention. 1 in the figure
Reference numeral 0 is a rinse tank, which is a cleaning tank for removing chemicals, particles, etc. used for cleaning the semiconductor substrate a such as Si with purified ultrapure water. An overflow tank 11 is provided around the rinse tank 10 so that pure water overflowing from the rinse tank 10 flows down into the overflow tank 11. A circulating water channel 12 is connected to the rinse tank 10. The circulation water passage 12 is a water passage for circulation that connects the rinse tank 10 and the overflow tank 11, and in the middle thereof, a pump 7, a valve 13, a metal silicon column 4,
The filters 6 are arranged in order. The valve 13 provided in the circulating water passage 12 is an opening / closing valve used when supplying necessary ultrapure water into the water passage 12. By operating the pump 7 in the cleaning apparatus, the purified ultrapure water that has passed through the column 4 and the filter is supplied into the rinse tank 10 in which the semiconductor substrate a is stored, and adheres to the semiconductor substrate a by the ultrapure water. Chemicals, particles, etc. are cleaned. Further, as the ultrapure water is supplied from the circulating water passage 12 to the rinse tank 10, the same amount of cleaning water overflows from the supernatant of the rinse feed 10 and flows into the overflow tank 11. The wash water that has flowed down into the overflow tank 11 is returned to the circulating water passage 12, passes through the column 4 filled with the metallic silicon 5 to be cleaned in the same manner as described above, and is then supplied again to the rinse tank 10. To be done.

The cleaning apparatus shown in FIG. 4 is the cleaning apparatus shown in FIG. 3 provided with a regenerating apparatus for metallic Si, and a rinse tank 10 is connected to dilute hydrochloric acid and alkali feeders 7 and 8. Is configured. The above-mentioned feeder has pumps 7a, 7
b is additionally provided, and by operating these pumps 7a and 7b, the diluted hydrochloric acid and alkali in the supply devices 7 and 8 are supplied into the rinse tank 10. In the above cleaning apparatus, after the alkali of the feeder 18 is introduced into the rinse tank 10 while the supply of ultrapure water to the rinse tank 10 is stopped, the pump 7 is operated to circulate the system. As a result, the surface of the metallic silicon 5 filled in the column 4 is removed by the alkali. Next, the valve 13 is opened to start the supply of ultrapure water, and the alkali is discharged from the system. Then, the dilute hydrochloric acid in the feeder 17 is supplied into the rinse tank 10, and the pump 7 circulates the system again to remove heavy metals from the surface of the metallic silicon in the column 4. Hydrochloric acid in the system is removed through the supply of ultrapure water. Through the above steps, the surface of the metallic silicon 5 is regenerated, and the adsorption effect by the surface is restored.

[0011]

The present invention is as described above. Therefore, metal ions contained in ultrapure water and colloidal metal components are adsorbed and removed by the surface of metallic silicon to remove ppq (metal). It is possible to obtain ultrapure water of pg / l) or less. Further, the surface of metal silicon having a reduced adsorption drop can be washed with alkali, hydrochloric acid or ultrapure water to restore the adsorption effect of the surface. Normal,
When a silicon wafer is immersed in normal pure water, the lifetime value of ultrapure water decreases with time. However, according to the cleaning method of the present invention, the high purity described above can be maintained, so the lifetime value does not decrease. Ultrapure water can be obtained. In addition, this method makes it possible to reuse rinse water that has overflowed, and to use ultrapure water used for cleaning in a range of 1/2 to 1
It can be reduced to about / 3.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a pure water production line for carrying out the cleaning method of the present invention.

FIG. 2 is a schematic diagram showing a pure water line provided with a regenerator.

FIG. 3 is a schematic view showing a cleaning device of the present invention.

FIG. 4 is a schematic diagram showing a cleaning device provided with a regenerating device.

[Explanation of symbols]

 a ... Semiconductor substrate 3 ... Ion exchange resin 4 ... Column 5 ... Metallic silicon 10 ... Rinse tank

Claims (2)

[Claims] 1. Contacting ultrapure water with metallic silicon,
A method for producing ultrapure water, which comprises adsorbing and removing metal ions and colloidal metal components in the ultrapure water on the clean surface of the metallic silicon. 2. The ultrapure water cleaning method according to claim 1, wherein metallic silicon having a reduced adsorption effect on the clean surface is washed with alkali, hydrochloric acid, and ultrapure water, and the clean surface is washed and regenerated for reuse.