JPS61268391A - Apparatus for making pure water - Google Patents

Abstract

PURPOSE:To enhance washing efficiency, by connecting a carbon dioxide supply part to a pure water supply route reaching a pure water using part from a pure water supply source. CONSTITUTION:In a carbon dioxide supply part 13, carbon dioxide sent out from a carbon dioxide source 6 is brought to predetermined pressure by a regulator 7 and reaches a filter 10 through a flowmeter 8 and a solenoid valve 9 to remove impurities therein and met with pure water flowing through supply piping 4 through a reverse flow preventing valve 11 and an opened valve 12 to be dissolved therein. The specific resistance value of pure water having carbon dioxide dissolved therein and lowered in the specific resistance value is detected by a specific resistance meter 14. The opening degree of the solenoid valve 9 is adjusted on the basis of the detected resistance value and the amount of carbon dioxide is controlled and the specific resistance value of pure water is sent to a precdetermined value. By this method, workability is enhanced and productivity is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a technology for producing pure water, and particularly to a technology that is effective when applied to the production of pure water used for cleaning processing in the manufacture of semiconductor devices.

[Background Art] Normally, in the manufacturing of semiconductor devices, a plurality of predetermined semiconductor elements are simultaneously formed in a regular array on a substrate, that is, a wafer, made of a semiconductor such as silicon by photolithography technology, and then the wafer is arranged in a grid pattern. Dividing into pellets each consisting of individual semiconductor elements is performed by so-called dicing.

In this case, in order to prevent an increase in cutting resistance during dicing, extend the lifespan of the dicing tool blade, and remove cutting debris, the wafer is cleaned by spraying highly purified water at high pressure from a designated nozzle. Wafer cleaning is performed with increased efficiency.

On the other hand, the specific resistance value of pure water is generally extremely high, and therefore the wafer is charged by static electricity caused by friction between the pure water and the nozzle or the wafer surface. The inventors of the present invention have discovered that defects occur due to destruction, which causes a decrease in the yield of semiconductor devices.

In addition, the literature explaining cleaning of wafers with pure water includes "Electronic Materials J 1982 Special Issue, P109~" published by Industrial Research Association Co., Ltd., November 10, 1982.
There is P116.

[Object of the Invention] An object of the present invention is to provide a pure water production technique that can reduce the specific resistance value without reducing the impurity purity of the pure water.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Summary of the Invention] A brief overview of typical inventions disclosed in this application is as follows.

That is, by connecting a carbon dioxide gas supply section that melts carbon dioxide into the pure water flowing through this pure water supply path to the pure water supply path from the pure water supply source to the pure water use section,
The specific resistance value is lowered without lowering the impurity purity of pure water.

[Example 1] FIG. 1 is an explanatory diagram showing the main parts of a pure water production apparatus which is an example of the present invention.

Pure water of a predetermined purity sent from an ultrapure water supply unit 1 (pure water supply source) passes through a supply pipe 4 (pure water supply path) equipped with a backflow prevention valve 2, a filter 3, etc., and is then delivered to, for example, a wafer. Dicing section 5 where dicing (not shown) is performed
(pure water usage section) and is configured to perform cleaning of wafers, etc.

The ultrapure water supply section 1 includes, for example, a filter, a reverse osmosis membrane,
It is composed of an ion exchange section (not shown), etc., and contains particulates,
Pure water with extremely high purity and high specific resistance value from which organic matter and various ions have been removed is sent to the supply pipe 4.

In this case, the supply pipe 4 includes a carbon dioxide gas source 6 and a regulator 7 that sets the pressure of the carbon dioxide gas supplied from the carbon dioxide gas source 6 to a predetermined value, as well as a flow meter 8, a solenoid valve 9, a filter 10, A carbon dioxide gas supply section 13 consisting of a backflow prevention valve 11, a valve 12, etc. is connected, and a predetermined amount of carbon dioxide gas is dissolved in the pure water flowing through the supply piping 4.

Therefore, the pure water with a relatively high resistivity value sent from the ultrapure water supply section 1 has impurity purity reduced by hydrogen ions generated by dissociation of carbonic acid produced by dissolving carbon dioxide gas. The specific resistance value is reduced without any problem.

Further, a resistivity meter 14 is provided downstream of the portion of the supply piping 4 to which the carbon dioxide gas supply section 13 is connected, and the supply piping 4 is changed by dissolving carbon dioxide from the carbon dioxide gas supply section 13. is configured so that the specific resistance value of pure water inside is measured.

The opening degree of the solenoid valve 9 provided in the carbon dioxide gas supply unit 13 and adjusting the amount of carbon dioxide gas supplied into the supply piping 4 is controlled based on the measured value of the resistivity meter 14.
By adjusting the amount of carbon dioxide gas to be dissolved, the resistivity value of the pure water supplied to the dicing section 5 etc. can be set to a predetermined value.

The operation of this embodiment will be explained below.

First, pure water having a predetermined purity and specific resistance value is sent from the ultrapure water supply section 1 to the supply pipe 4.

On the other hand, in the carbon dioxide gas supply section 13 connected to the supply pipe 4, the carbon dioxide gas sent from the carbon dioxide gas source 6 is brought to a predetermined pressure in the regulator, passes through the flow meter 8 and the solenoid valve 9, and is sent to the filter 10. After the impurities are removed, the check valve 11 and the opened valve 12 are opened.
It is joined with the pure water flowing through the supply pipe 4 and dissolved therein.

Carbonic acid is generated in pure water in which carbon dioxide gas is dissolved, and hydrogen ions and other substances generated by the dissociation of the generated carbonic acid reduce the ratio of pure water in which carbon dioxide gas is dissolved, without reducing the purity of impurities. The resistance value is reduced.

Then, the resistivity value of the pure water whose resistivity value has been reduced by dissolving carbon dioxide gas is detected by a resistivity meter 14 provided on the downstream side of the supply piping 4, and the resistivity value of the pure water detected by this resistivity meter is The opening degree of the solenoid valve 9 is adjusted based on the resistivity value of the solenoid valve 9, and the amount of carbon dioxide dissolved in the pure water flowing through the supply pipe 4 from the carbon dioxide gas supply section 13 is adjusted. The specific resistance value of pure water supplied to the equipment, etc. is set to a relatively low predetermined value.

In this way, the resistivity value of the supplied pure water is reduced without reducing the impurity purity of the pure water, so that, for example, in the dicing section 5, pure water is injected onto the wafer at high pressure before and after the dicing operation. During the cleaning operation, static electricity generated by friction between the sprayed pure water and the wafer is quickly discharged through the pure water, which has a lower specific resistance value and improved conductivity. The wafer is prevented from being charged due to static electricity, the wafer is not contaminated with impurities, and the occurrence of defects due to electrostatic breakdown of semiconductor elements formed on the wafer is avoided.

In addition, by controlling the amount of carbon dioxide gas dissolved in pure water based on the specific resistance value of pure water, the specific resistance value of pure water, which changes due to the dissolution of carbon dioxide gas, can be adjusted to a predetermined value. For example, it becomes possible to set the resistivity value according to the purpose of pure water, and the workability of cleaning work using pure water is improved.

[Effects] (1) A carbon dioxide gas supply unit that dissolves carbon dioxide in the pure water flowing through the pure water supply route is connected to the pure water supply path from the pure water supply source to the pure water use unit. Because of this structure, it is possible to reduce the specific resistance value of pure water without reducing the purity of impurities in the pure water. As a result, accumulation of static electricity on the wafer can be avoided, and failures due to electrostatic breakdown of semiconductor elements formed on the wafer can be prevented.

(2) The amount of carbon dioxide gas supplied from the carbon dioxide gas supply section into the pure water supply path is controlled based on the specific resistance value of pure water that changes as the carbon dioxide gas is dissolved, The specific resistance value of the pure water supplied to the use section can be set to a desired value, and workability in the pure water use section is improved.

(3) As a result of +11, the yield of semiconductor devices in the cleaning operation using pure water is improved.

(4) As a result of the above (11 to (3)), productivity in manufacturing semiconductor devices is improved.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, the article to be cleaned with pure water is not limited to a wafer, but may also be a photomask or the like.

[Field of Application] In the above description, the invention made by the present inventor was mainly applied to the cleaning technology in the manufacturing of semiconductor devices, which is the field of application that formed the background of the invention, but the invention is not limited thereto. It can be widely applied to cleaning techniques using pure water for insulators where static electricity buildup is a problem.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the main parts of a pure water production apparatus which is an embodiment of the present invention. 1... Ultrapure water supply section, 2... Backflow prevention valve, 3...
Filter, 4... Supply piping (pure water supply path), 5...
・Dicing section (pure water usage section), 6... carbon dioxide source,
7...Regulator, 8...Flowmeter, 9...Solenoid valve, 1o...Filter, 11...Return prevention valve, 12...Valve, 13...Carbon dioxide gas supply unit, 14・・・
・Resistivity meter.

Claims (1)

[Claims] 1. In the pure water supply path from the pure water supply source to the pure water usage part,
A pure water production apparatus characterized by being connected to a carbon dioxide gas supply section that dissolves carbon dioxide gas in the pure water flowing through the pure water supply path. 2. The amount of carbon dioxide gas supplied from the carbon dioxide gas supply section into the pure water supply path is controlled based on the specific resistance value of pure water, which is changed by dissolving the carbon dioxide gas. A pure water production apparatus according to claim 1. 3. The pure water production apparatus according to claim 1, wherein the pure water is used for cleaning in the manufacture of semiconductor devices.