JPH0919661A - Method and apparatus for washing electronic parts and the like - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to wash the ultraclean surfaces of electronic parts, etc., with the min. required consumption of a medicinal liquid by washing the wash, such as semiconductor substrates, glass substrates and electronic parts, with a washing soln. prepd. by dissolving gaseous chlorine into high-purity water. SOLUTION: The water fed from a branched piping 6 from circulating piping 5 of ultra-pure water producing apparatus 1 to 4 is partly sent by a water feed piping 61 to a washing tank 71. The liquid prepd. by dissolving the gaseous chlorine from a gaseous chlorine soln. tank 74 in which the gaseous chlorine is dissolved via a gas permeable membrane is added into the ultra-pure water during the course of this feeding by a pump 75. The ultra-pure water is partly fed as rinsing water from the branch piping through a water feed piping 62 to a rinsing tank 72. The gaseous chlorine dissolved in the liquid forms hypochlorous acid at the time of washing the wash in the washing tank 71, thereby exhibiting an excellent washing effect. As a result, the consumption of chemicals and pure water in the washing stage and the waste water load from the washing stage are drastically reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for cleaning an object to be cleaned such as an electronic component which is required to have an ultraclean surface.

[0002]

2. Description of the Related Art A conventional example of the present invention will be described by taking as an example the cleaning of a silicon wafer used in the manufacture of an LSI, which is one of electronic components required to have an ultraclean surface.

In the LSI manufacturing process, an insulating film of, for example, SiO ₂ is formed on a silicon wafer, a window of a predetermined pattern is formed in this insulating film, and metal silicon under the insulating film is exposed and then washed. Depending on the purpose, a p-type or n-type element is introduced, and a step of burying a metal wiring such as Al is repeated to form an element.

During the introduction of the p-type or n-type element or the step of embedding the metal wiring, foreign matter such as fine particles, impurities such as metal, organic matter and natural oxide film adhere to the exposed metal silicon surface. If there is a metal-
It is necessary to remove impurities adhering to the surface of the wafer as much as possible because it causes defects in device characteristics such as wiring defects of silicon and increase in contact resistance. In particular, in order to manufacture high-performance devices, this silicon wafer ( Surface cleaning of semiconductor wafers is considered to be a very important step.

The conventional cleaning method performed on a semiconductor wafer is performed using the following technique, for example. That is, a mixed solution of sulfuric acid / hydrogen peroxide solution, hydrochloric acid / hydrogen peroxide solution, ammonia / hydrogen peroxide solution, hydrofluoric acid solution, ammonium fluoride solution, and ultrapure water are used in combination to form The steps of removing organic substances, fine particles, metals, and natural oxide films adhering to the semiconductor surface without impairing the flatness at the atomic level, for example, the steps (1) to (13) shown below as an example are performed. Be done.

(1) Sulfuric acid / hydrogen peroxide cleaning (sulfuric acid: hydrogen peroxide solution = 4: 1, volume ratio) 130 ° C.
10 minutes (2) Ultrapure water cleaning 10 minutes (3) Hydrofluoric acid cleaning (hydrofluoric acid 0.5%) 1 minute (4) Ultrapure water cleaning 10 minutes (5) Ammonia hydrogen peroxide cleaning (Ammonia water: peroxide) Hydrogen water: Ultrapure water = 0.05:
(1: 5, volume ratio) 80 ° C., 10 minutes (6) Ultrapure water cleaning 10 minutes (7) Hydrofluoric acid cleaning (hydrofluoric acid 0.5%) 1 minute (8) Ultrapure water cleaning 10 minutes (9) Hydrochloric acid Hydrogen peroxide cleaning (hydrochloric acid: hydrogen peroxide solution: ultra pure water = 1: 1: 6, volume ratio)
80 ° C., 10 minutes (10) Ultrapure water cleaning 10 minutes (11) Hydrofluoric acid cleaning (hydrofluoric acid 0.5%) 1 minute (12) Ultrapure water cleaning 10 minutes (13) Spin drying or IPA vapor drying Explaining the role of each step of the cleaning, which is divided into stages, the sulfuric acid / hydrogen peroxide cleaning of (1) is mainly for removing organic substances adhering to the surface.
The ammonia hydrogen peroxide cleaning in (1) is mainly for removing fine particles adhering to the surface, and the hydrochloric acid hydrogen peroxide cleaning in (9) is mainly for removing adhered metal impurities on the surface.
The hydrofluoric acid cleaning of (3), (7) and (11) is for removing the natural oxide film on the surface.

The main purpose of each cleaning step is as described above, but each cleaning solution often has the ability to remove contaminants other than the main purpose. For example, the sulfuric acid hydrogen peroxide solution used in (1) above. The mixed solution has a strong ability to remove metal deposits in addition to the removal of deposited organic substances. Therefore, in addition to the above-described exemplary cleaning method, there is also a method in which one cleaning liquid is used to remove a plurality of contaminants.

As a method for bringing a cleaning chemical solution containing cleaning chemicals (hereinafter sometimes simply referred to as “chemical solution”) or ultrapure water into contact with the surface of the wafer for cleaning semiconductor wafers, etc., a batch method is generally used. A method called a cleaning method, in which multiple wafers are immersed together in a cleaning tank containing a chemical solution (or ultrapure water), is often used, but the chemical solution in the cleaning tank is circulated and filtered to prevent contamination during cleaning. Or, as a rinsing method, when rinsing with ultrapure water, overflow rinse is used to supply ultrapure water from the bottom of the tank to overflow from the top of the tank, and store ultrapure water until the entire wafer surface is immersed in ultrapure water. It has also been devised such as a quick dump rinse that drains water from the bottom of the tank all at once. Recently, in addition to the batch cleaning method, a method of showering a chemical solution or ultrapure water on the wafer surface, a method of rotating the wafer at a high speed and applying a chemical solution or ultrapure water to the center of the wafer to perform cleaning, etc. The so-called single-wafer cleaning method is also adopted.

The above-described rinsing process performed after the cleaning for the deposit removing step with the chemical liquid is for rinsing (rinsing) the chemical liquid remaining on the wafer surface, and the rinse water is extremely pure. It is common to use ultrapure water produced by a water production device as rinse water. This is because after the step of removing deposits with a chemical solution, that is, after the wafer surface is already in an ultra-clean state with no deposit impurities, contaminants may adhere to the wafer surface again as a result of rinsing. Because the meaning of is lost. Therefore, as the rinse water used for removing the chemical,
High-purity water obtained by removing fine particles, colloidal substances, organic substances, metals, anions, dissolved oxygen, etc. to an extreme level, that is, ultrapure water is often used conventionally.

Ultrapure water (secondary pure water) is prepared by storing first-order pure water in a first-order pure water tank, using an ultraviolet irradiation device, a mixed-bed polisher,
Secondary treatment is carried out sequentially using a membrane treatment device such as an ultrafiltration membrane device or a reverse osmosis membrane device, and the fine particles, colloidal substances, organic substances, metals, anions, etc. remaining in the primary pure water are brought to an extreme level. It is manufactured by removing it. In addition,
The ultrapure water, which is the permeated water of the membrane treatment device of the secondary pure water treatment system, is generally branched from the middle of the circulation line to the point of use for water supply, and the remaining ultrapure water is supplied to this circulation line. The water is usually returned to the above-mentioned primary pure water tank through a return pipe (return pipe), and the amount of water returned to the primary pure water tank through the return pipe is usually 10 to 10 times the amount of water sent from the membrane treatment apparatus.
Most of them are about 30%.

In the state-of-the-art technology, ultrapure water produced by a general ultrapure water producing apparatus for producing LSIs of the submicron design rule has, for example, the water quality shown in Table 1 below. If such ultrapure water quality is achieved, it is said that contaminants derived from ultrapure water will not adhere to the surface during the rinsing process with ultrapure water.

[0012]

[Table 1]

[0013]

By the way, in the field of manufacturing electronic components and the like, it has become an important subject to manufacture the products at a lower cost as well as to improve the performance of the products. LS
As for the I manufacturing process, the cleaning process, which consumes a large amount of liquid, accounts for a large proportion of the cost, and therefore there is a strong demand for improvement in the cleaning process.

From this point of view, the following problems are pointed out. That is, in the prior art which performs the above steps (1) to (13), the cleaning solution is still used without changing the composition and concentration of the solution that has been used before. However, for example, the hydrochloric acid-hydrogen peroxide cleaning solution used to remove adhered metal impurities is a mixed solution of a halogen acid and an oxidizing agent, so that the reaction produces chemical species other than the raw materials hydrochloric acid and hydrogen peroxide. However, it is not always clear which of these chemical species the cleaning effect depends on. As a result,
The current situation is that the chemical composition / ratio cannot be optimized, and the cleaning chemicals are adjusted by relying on the precedent to allow for a margin of effectiveness. However, with this, there is a lot of waste of the used chemicals,
Since the cleaning is performed with an unnecessarily high concentration chemical solution, it is inevitable that the amount of rinse water used thereafter will increase. For this reason, the amount of chemicals and the amount of rinsing water are excessively consumed in the entire cleaning process, and the amount of drainage water from the cleaning process is increased, resulting in an unnecessary increase in operating costs.

The present invention is a method for cleaning an electronic component or the like, in which an object to be cleaned, which is required to obtain an extremely clean surface as described above, is cleaned with a minimum necessary amount of chemical solution. And to provide a device.

[0016]

A feature of the method for cleaning electronic parts and the like of the present invention is that an object to be cleaned requiring an ultra-clean surface is cleaned with a cleaning solution in which chlorine gas is dissolved in high-purity water. There is a place to do it. The dissolved chlorine gas produces hypochlorous acid to exert an excellent cleaning effect, and it is possible to dramatically reduce the amount of chemicals and pure water used in the cleaning process and the drainage load from the cleaning process.

In the present invention, "hypochlorous acid" means a form that hypochlorous acid can take in accordance with the pH of the solution when the hypochlorous acid produced by dissolving chlorine gas is dissolved in water. , Namely chlorine (Cl ₂ ), hypochlorous acid (H
ClO) or a dissolved form of hypochlorite ion (ClO ⁻ ) is included alone or in all coexisting states. Further, the "hypochlorous acid concentration" refers to all of the above dissolved forms converted into chlorine (Cl).

The high-purity water used in the above means, for example, coagulation sedimentation treatment of raw water, sand filtration treatment, activated carbon filtration treatment, reverse osmosis membrane treatment, two-bed three-column type ion exchange treatment, mixed bed type ion exchange treatment, A pure water production system that uses a device that performs coagulation-sedimentation process, sand filtration process, distillation process, etc. on pure water produced using a pure water production device that performs processing such as membrane treatment with a precision filter, or raw water. The pure water produced can be exemplified, but in addition to these, in the case of an object to be cleaned requiring an extremely clean surface such as a silicon wafer, it is produced as described above. By treating pure water in sequence using an ultraviolet irradiation device, a mixed-bed polisher, and an ultrafiltration membrane device, residual particles such as colloidal substances, organic substances, metals, and anions are removed as much as possible. Can be mentioned ultrapure water manufacturing apparatus for producing high-purity water called a particularly typical. However, the high-purity water produced by these pure water producing devices or the like is not limited by the type and structure of the treatment device at each stage constituting the pure water producing device or the like. Further, not only when the pure water that has been subjected to the final stage treatment of the pure water production apparatus (often a membrane treatment apparatus) is used as dilution water or rinsing water for the cleaning solution, at least an ion exchange device, Treated water (also pure water) that has been treated by either the membrane treatment device or the distillation device may be branched without passing through the pure water treatment device in the subsequent stage, and may be used as dilution water for the cleaning solution.

The object to be cleaned by the method of the present invention is a semiconductor substrate, a glass substrate, a product of an electronic component or a material of an electronic component for which an ultraclean surface is required, or an electronic component manufacturing field such as a component for a manufacturing apparatus of these. Examples thereof include various materials and parts used. More specifically, for example, semiconductor substrates such as silicon wafers and III-V semiconductor wafers, substrate materials such as glass substrates for liquid crystals, memory devices,
Examples include finished products such as electronic parts such as CPUs and sensor elements and semi-finished products thereof, or parts for manufacturing equipment such as quartz reaction tubes, cleaning tanks, and wafer carriers. The term "ultra-clean surface" means that in electronic components such as the above-mentioned LSI, etc., adhesion of foreign substances such as fine particles, impurities such as metals, organic substances, and natural oxide films can be made as close to zero as possible. The surface required is generally referred to as a surface that is required to be rinsed with ultrapure water.

The cleaning method is not particularly limited,
For example, any of known methods such as a batch cleaning method, a flow cleaning method, a showering method, and a single plate cleaning method can be adopted. As a method of dissolving chlorine gas in high-purity water, a method of directly injecting into water, a method of using an air diffusing tube, a method of dissolving through a gas permeable membrane, or the like can be used. The method used is preferable because it can prevent the generation of fine particles. It is possible to produce a cleaning solution containing hypochlorous acid by adding chloride ions and an oxidizing agent to high-purity water, but in this case, chloride ions and oxides are completely reacted. Therefore, the method of the present invention in which chlorine gas is dissolved is more preferable because there is a problem that excess chloride ions and an oxidant are required and it is difficult to control the concentration of hypochlorous acid.

When the concentration of hypochlorous acid contained in the cleaning solution by dissolving chlorine gas is preferably 10 ppm or more, the desired cleaning can be effectively achieved, and more preferably 15 to 30 ppm. It is often better to say

An acid other than hypochlorous acid can coexist in the cleaning solution containing hypochlorous acid. The pH of the solution is 2.5 or less, preferably pH 1 to 1 by addition of an acid.
When used as 2, the redox potential can be made higher and a higher oxidizing power can be obtained, and the cleaning ability can be further improved, as compared with the case where a cleaning solution containing hypochlorous acid having a pH of more than 2.5 is used. Can be made. In this case, the acid other than hypochlorous acid to be coexisted in the cleaning solution containing hypochlorous acid is not particularly limited, but hydrochloric acid, sulfuric acid, nitric acid, or the like can be used. Also like this
When it is 2.5 or less, hypochlorous acid concentration is 5-10p
Even in the pm range, a cleaning power equivalent to that of the cleaning solution containing hypochlorous acid having a pH of more than 2.5 can be obtained.

In addition, an oxidizing agent other than hypochlorous acid can coexist in the above-mentioned cleaning solution, whereby an effect of further enhancing the cleaning effect of the cleaning solution can be obtained. As such an oxidizing agent other than hypochlorous acid added to ultrapure water, any oxidizing agent may be used without particular limitation as long as it does not adversely affect the purpose of cleaning, but ozone is particularly preferable. Ozone can facilitate the reduction of load during wastewater treatment, which is one of the objects of the present invention. in this case,
It is preferable to add ozone in a concentration of 3 ppm or more, preferably 5 to 10 ppm in the cleaning solution after mixing.

The cleaning solution of the present invention has the above-mentioned (1) to
It can be used in place of each of the conventional cleaning solutions used in the cleaning step (13), but the order of the cleaning steps is not limited to this.

Another feature of the present invention is to provide an apparatus for producing the above cleaning solution. Specifically, ultrapure water production equipment provided with means for removing ions, fine particles, organic substances, and gas in multiple stages, and semiconductor substrates, glass substrates, electronic component products or product materials, or components for these production equipment, etc. A cleaning device for cleaning the ultra-clean surface of the object to be cleaned with a cleaning solution and then rinsing with ultrapure water, a cleaning solution supply means for feeding the cleaning solution to the cleaning device, and an ultrapure water manufacturing device In a cleaning device for electronic parts, etc., which is provided with a rinse water supply pipe for supplying the purified ultrapure water to the cleaning device, the cleaning solution supply means is used to supply chlorine to the ultrapure water manufactured by the ultrapure water manufacturing device. It is configured to send a liquid in which a gas is dissolved.

The means for producing a cleaning solution in which chlorine gas is dissolved is not limited, but a gas permeable membrane or the like can be mentioned as a particularly preferable one because the amount of fine particles generated during dissolution is small. .

In addition to the means for dissolving chlorine gas, the above-mentioned cleaning apparatus includes a liquid, a solution or a gaseous acid such as hydrochloric acid to enhance the cleaning power by lowering the pH and increasing the redox potential. It is also preferable to additionally provide a mechanism for adding sulfuric acid, nitric acid, and aqueous solutions of these acids. Further, in addition to the mechanism for adding hypochlorous acid and the mechanism for adding acid to the above-mentioned cleaning solution, it is also preferable to attach a horizontal frame for adding an oxidizing agent such as hydrogen peroxide or ozone to the above-mentioned cleaning device. .

The above ultrapure water producing apparatus is generally a coagulating sedimentation apparatus, a sand filtration apparatus, an activated carbon filtration apparatus, a reverse osmosis membrane apparatus, a two-bed three-column ion exchange apparatus, a mixed bed type ion exchange apparatus,
Immediately before the point of use where raw water is processed by a pretreatment device equipped with multiple stages of precision filters and the primary water treatment device to obtain primary water, and then the object to be cleaned is washed, the pure water is further added. Secondary pure water (ultra pure water) treated with an ultraviolet irradiation device, mixed bed polisher, ultrafiltration membrane device, etc. in the secondary pure water treatment system
An ultrapure water producing apparatus for producing a water, which is not necessarily defined by a processing procedure, and is a cleaning water for electronic parts etc. which is required to obtain an ultraclean surface such as a semiconductor substrate which is an object of the present invention. Suitable water as (high-purity water)
Anything can be used.

[0029]

The method and apparatus for cleaning electronic parts and the like according to the present invention uses a cleaning solution containing a low concentration of hypochlorous acid to clean objects to be cleaned such as semiconductor substrates, glass substrates, electronic parts and parts of their manufacturing equipment. In addition to being able to be effectively cleaned, it is capable of removing all types of adherent metal contaminants, including copper contaminants, which were previously considered impossible to remove without a hydrochloric acid / hydrogen peroxide cleaning solution.

Generally, the metal element present in the liquid is easily ionized and dissolved under acidic and oxidizing conditions, while the form of adhesion of the metal to the solid surface is precipitation as a salt, oxide or hydroxide. Alternatively, since the deposition is atomic deposition by giving and receiving electrons to and from the solid surface, the more acidic and oxidizing the cleaning liquid, the stronger the cleaning ability. For this reason, a hydrochloric acid-hydrogen peroxide cleaning solution, which is an acidic and oxidizing cleaning solution, has been used for conventional metal removal. However, the use condition of the hydrochloric acid-hydrogen peroxide cleaning solution, that is, the concentration (for example, hydrochloric acid: peroxidation) Hydrogen: Ultrapure water = 1: 1: 6, volume ratio), temperature (for example, 80 ° C.), etc.
As described above, the amount of the drug solution used is large because it is empirically determined while giving priority to obtaining a stable cleaning effect.

On the other hand, the cleaning solution of the present invention containing hypochlorous acid as an active ingredient achieves the purpose as an extremely dilute aqueous solution as compared with the concentration of the chemical solution such as the conventional hydrochloric acid / hydrogen peroxide cleaning solution. obtain.

Specifically, comparing the results of cleaning a silicon wafer to which copper of about 10 ¹² atoms / cm ² is adhered with an aqueous solution containing hydrogen peroxide, hypochlorous acid, and 100 ppm of chloric acid is compared. Only the aqueous solution of chloric acid removes the copper adhering to the surface of the silicon wafer at 10 ¹⁰ atoms / cm 2.
Up to ² or less can be removed. Furthermore, using the same copper-contaminated silicon wafer as above, the concentration of hypochlorous acid necessary for removing copper was confirmed, and it was found that the amount of residual copper was required to be 10 ¹⁰ atoms / cm ² or less. The concentration of hypochlorous acid is 10 ppm, and more powerful removal effect can be obtained by adjusting the pH of the cleaning solution to 2.5.

As a result, the present invention makes it possible to dramatically reduce the amount of chemical solution used, the amount of ultrapure water used for rinsing, and the cost of wastewater treatment by using hypochlorous acid as an active ingredient.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a cleaning apparatus for electronic parts and the like to which the present invention is applied will be described below with reference to FIGS. 1 and 2.

FIG. 2 is a block diagram showing an outline of the ultrapure water production system in this example. Raw water is supplied to a pretreatment system 1 for performing each of coagulation sedimentation treatment, sand filtration treatment and activated carbon filtration treatment. After being passed, two-bed, three-column type ion exchange treatment,
It is made into primary pure water through a primary pure water treatment device 2 such as a mixed bed type ion exchange treatment, a precision filter, and a membrane treatment by a reverse osmosis membrane treatment, and is stored in a primary pure water tank 3.

Next, this primary pure water is used as an ultraviolet irradiation device 4
1. Non-regeneration type mixed bed type ion exchange resin tower (mixed bed type polisher) 42, fine particles, colloidal substance, organic matter remaining after passing through the secondary pure water device 4 including the ultrafiltration membrane device 43.
Secondary pure water (ultra pure water) from which metals, anions and the like have been removed as much as possible is circulated to the primary pure water tank 3 through the circulation pipe 5, and is branched on the way from the branch pipe 6. Water is sent to the cleaning device, which is the point of use 7.

FIG. 1 shows a part of the cleaning apparatus, in which a rinsing tank 72 is arranged after the batch type silicon wafer cleaning tank 71, and the silicon wafer 8 is passed through the cleaning tank 71 and then the rinsing tank 72 in this order. A cleaning device for transferring the wafer to a spin dryer 73 that performs cleaning after cleaning is shown.

The apparatus of this example is composed of ultrapure water producing apparatuses 1 to 1.
4 part of the water supply from the branch pipe 6 from the circulation pipe 5
Water is supplied to the cleaning tank 71 through a water supply pipe 61, and a liquid in which chlorine gas is dissolved is added from a chlorine gas solution tank 74 by a pump 75 during this process. As a result, a liquid in which chlorine gas is dissolved is sent to the cleaning tank 71 as a cleaning solution. The chlorine gas solution bath 74 uses ultrapure water as a water source and dissolves chlorine gas in the water through a gas permeable membrane.

Further, the branch pipe is configured to send ultrapure water to the rinse tank 72 as rinse water by a water supply pipe 62.

[0040]

EXAMPLES The following practical tests were conducted using the apparatus having the configuration described in FIGS. 1 and 2 above.

Example 1 In this example, a P-type silicon wafer having a diameter of 150 mm and having a clean surface obtained by preliminary cleaning as described in (1) to (4) below was coated with copper (5) and (6). As described above, the cleaning tank 71 is filled with an aqueous solution containing hydrogen peroxide, hypochlorous acid, and chloric acid.
The test was performed by the method of washing each.

(L) Hydrofluoric acid cleaning 0.5% hydrofluoric acid, room temperature, immersion 1 minute (2) Ultrapure water cleaning room temperature, overflow rinse 10 minutes (3) Hydrochloric acid hydrogen peroxide cleaning Hydrochloric acid: Hydrogen peroxide solution: super Pure water = 1: 1: 6 (volume ratio),
80 ° C, immersion 10 minutes (4) Ultrapure water cleaning room temperature Overflow rinse 10 minutes The amount of copper deposited on the surface of the silicon wafer after the preliminary cleaning is 0.3 × 10 ¹⁰ atoms / c
m ² or less. Incidentally, all the amounts of copper deposited on the silicon wafer were measured by the total reflection fluorescent X-ray method.

Next, a copper-contaminated silicon wafer was prepared by the following procedure.

(5) Copper contamination 10% hydrofluoric acid containing 1 ppm of Cu, room temperature, immersion 10
Minute (6) Ultrapure water cleaning Room temperature, overflow rinse 10 minutes The copper adhesion amount of the silicon wafer after the above contamination operation is 2 to 1
It was in the range of 0 × 10 ¹² atoms / cm ² .

Using the copper-contaminated silicon wafer prepared as described above, a cleaning test was performed using the three types of oxidant aqueous solutions shown in Table 2 below.

The three kinds of oxidant aqueous solutions were prepared by the following procedure. That is, in the hydrogen peroxide cleaning solution, a highly pure reagent having a concentration of about 30% was diluted with ultrapure water, and the adjusted concentration was assayed by the potassium permanganate titration method. The hypochlorous acid cleaning solution was aerated with high-purity chlorine gas in ultrapure water to dissolve chlorine, and the concentration was tested by the iodine titration method.
The chloric acid cleaning solution was prepared by dissolving a specified amount of sodium chlorate in ultrapure water, and the concentration of chloric acid was tested by the ion chromatography method. The adjusted hypochlorous acid cleaning solution had a pH of 2.8 due to chloride ions generated by the self-decomposition of hypochlorous acid when chlorine gas was dissolved. The acid cleaning solution was adjusted to pH 2.8 with hydrochloric acid and then subjected to a cleaning test.

(7) Chemical solution cleaning: room temperature (25 ° C.), immersion 10 minutes (8) Ultrapure water cleaning: room temperature, overflow rinse 10 minutes (9) Spin drying or IPA vapor drying Copper residual amount on silicon wafer after cleaning The measurement results are shown in Table 2. In Table 2, when the copper removal effects of 100 ppm aqueous solutions of hydrogen peroxide, hypochlorous acid, and chloric acid are compared, only the hypochlorous acid aqueous solution has a copper residual amount after cleaning of 1%. 0x1
It is possible to set it to 0 ¹⁰ atoms / cm ² or less, and the cleanliness level required in today's semiconductor manufacturing process is achieved. That is, it was shown that hypochlorous acid can be effectively used for removing metals on the surface of a silicon wafer, and at that time, the amount of the chemical solution used can be significantly reduced. Moreover, this cleaning effect is obtained only by immersing the silicon wafer in the aqueous solution of hypochlorous acid at room temperature.
Compared to the hydrochloric acid / hydrogen peroxide cleaning solution used after heating to 0 ° C, etc., the energy cost for heating and the equipment cost required for handling the concentrated hot chemical solution are increased. It was also shown that it can be reduced.

[0048]

[Table 2]

Example 2 The concentration of hypochlorous acid required for removing copper adhering to the surface of a silicon wafer using a hypochlorous acid cleaning solution was investigated.

That is, the hypochlorous acid concentration is 3, 5, 1
A copper-contaminated silicon wafer was washed in the same manner as in Example 1 except that the concentration was adjusted to 0 and 100 ppm, and the washing test was performed when the pH was not adjusted. Table 3 shows the pH values of the hypochlorous acid cleaning solutions having the respective concentrations at this time.

Further, after adjusting the concentration of hypochlorous acid in the hypochlorous acid cleaning solution in the same manner as described above, a copper removal test was conducted with a cleaning solution having a pH of 2.5 with hydrochloric acid to carry out a copper removal effect. I checked. The results are shown in Table 3.

From these results, when the pH was not adjusted, the amount of copper remaining on the silicon wafer was adjusted to 1% or less when the hypochlorous acid concentration was 10 ppm or more. It can be set to 0 × 10 ¹⁰ atoms / cm ² or less, and the surface cleanliness required in today's semiconductor manufacturing process can be obtained. It was also confirmed that by adjusting the pH of the cleaning solution to 2.5, the cleaning effect of hypochlorous acid can be further enhanced, and a predetermined cleaning effect can be obtained at a hypochlorous acid concentration of 5 ppm or more. It was

[0053]

[Table 3]

Example 3 Example 1 except that the washing solution was prepared as follows:
The removal test of the deposited copper on the silicon wafer was conducted by the same method as described in 1.

To adjust the cleaning solution, first, hydrochloric acid was added to ultrapure water to adjust the pH to 2.5, and then ozone gas was aerated to the hydrochloric acid aqueous solution to adjust the ozone concentration to 1 ppm to obtain a cleaning solution. The concentration of hypochlorous acid was 2.9 ppm. In the above concentration measurement, the dissolved ozone concentration in the cleaning solution is measured by collecting a part of the cleaning solution and adjusting the pH to 1.0 with hydrochloric acid.
The measurement was performed by measuring the absorbance at a wavelength of 255 nm, and the hypochlorous acid concentration was adjusted to pH 8.0 with sodium hydroxide by collecting a portion of the washing solution, and the wavelength was 294n.
The absorbance at m was measured.

As a result of cleaning the copper-contaminated wafer with the cleaning solution, the copper on the silicon wafer was 0 × 10 ¹⁰ atom
It was shown that the cleaning effect was reduced to s / cm ² and a good cleaning effect was obtained. Further, in this example, although the hypochlorous acid concentration in the cleaning solution was 2.9 ppm, its copper removing effect was equivalent to that of the cleaning solution in Example 2 having a hypochlorous acid concentration of 5 ppm. Yes, it exceeds the cleaning solution with a hypochlorous acid concentration of 3 ppm in the same example.

This example shows that the coexistence of hypochlorous acid and an oxidizing agent other than hypochlorous acid can further enhance the metal removing effect.

Example 4 Diameter 1 stored in polypropylene box for 3 months
When a 5Omm silicon wafer was washed with a hypochlorous acid cleaning solution, it was found that this cleaning solution has a good organic substance removing effect in addition to the metal removing effect shown in Examples 1 to 3 above. Was done.

The hypochlorous acid cleaning solution was prepared by dissolving chlorine gas in ultrapure water to adjust the hypochlorous acid concentration to 10 ppm, and then adjusting the pH to 2.5 with hydrochloric acid. The cleaning was performed by rotating the silicon wafer at a rotation speed of 300 rpm using a spinner and allowing the cleaning solution to flow to the front and back surfaces of the silicon wafer at a flow rate of 1 liter / min. The temperature of the washing solution was room temperature and the washing time was 10 minutes. After the cleaning with the cleaning solution, ultrapure water at room temperature was continuously flown out for 10 minutes for rinsing, the ultrapure water was stopped, and spin drying was performed to obtain a cleaned wafer.

The amount of organic substances attached to the wafer before and after cleaning was measured by thermal desorption gas chromatography mass spectrometry to evaluate the organic substance removal effect of the hypochlorous acid cleaning solution.

Before cleaning, the amount of organic substances deposited on the silicon wafer, which showed 230 ng, was reduced to 3 ng by the above-mentioned cleaning with the hypochlorous acid cleaning solution. It was shown that it has a good organic substance removing effect.

[0062]

[Effect] According to the method and apparatus for cleaning electronic parts and the like using the cleaning solution in which chlorine gas is dissolved according to the present invention, it is possible to efficiently use components effective for removing metals and organic substances,
As a result, there is no need to use high-concentration chemicals, so there is no unnecessary consumption of chemicals, and since unnecessary high-concentration chemicals are not used for cleaning, the amount of rinse water (ultra pure water) used after cleaning is also high. It is possible to reduce the cost, reduce the running cost as a whole, and prevent waste of resources.

Further, the reduction of the amount of rinsing water leads to the reduction of the amount of waste water from the washing process, and in combination with the reduction of the amount of chemical solution in the waste water, the burden of waste water treatment is reduced and the influence on the surrounding environment is also small. There are advantages.

Further, according to the invention in which the pH of the cleaning solution is set to 2.5 or less, a more excellent cleaning effect can be obtained, thereby further reducing the amount of the cleaning solution.

Furthermore, according to the invention in which ozone is contained in the cleaning solution, an effect of further excellent cleaning effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a schematic configuration of a device that supplies a cleaning solution from an ultrapure water producing device to a cleaning device.

FIG. 2 is a diagram showing an example of a schematic configuration of an ultrapure water production system.

[Explanation of symbols]

1 ... Pretreatment device, 2 ... Primary pure water device, 3 ...
Primary pure water tank, 4 ... Secondary pure water device, 5 ... Circulation pipe, 6 ... Branch pipe, 7 ... Use point (cleaning device), 8 ... Silicon wafer, 61, 62・ ・ ・ Water supply pipe, 41 ・ ・ ・ UV irradiation device, 42 ・ ・ ・ Non-regenerative mixed bed type ion exchange resin tower (mixed bed polisher), 4
3 ... Ultrafiltration membrane device, 71 ... Washing tank, 72 ...
-Rinse tank, 73 ... Spin dryer, 74 ... Chlorine gas solution tank, 75 ... Pump.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Happiness Yamashita 1-4-9 Kawagishi, Toda City, Saitama Organo Research Institute

Claims (8)

[Claims] 1. An ultraclean surface of an object to be cleaned such as a semiconductor substrate, a glass substrate, a product or product material of electronic parts, or parts for manufacturing equipment thereof is cleaned with a cleaning solution prepared by dissolving chlorine gas in high-purity water. A method for cleaning electronic parts and the like characterized by cleaning. 2. The method for cleaning electronic parts according to claim 1, wherein the concentration of hypochlorous acid produced by dissolving chlorine gas is 10 ppm or more. 3. The cleaning of electronic parts and the like according to claim 1, wherein the pH of the cleaning solution is 2.5 or less, and the concentration of hypochlorous acid generated by chlorine gas dissolution is 5 ppm or more. Method. 4. The method according to claim 1, wherein
A cleaning method for electronic parts, wherein the cleaning solution contains ozone together with hypochlorous acid. 5. The method according to any one of claims 1 to 4,
A cleaning method for electronic parts, wherein the temperature of the cleaning solution is 15 to 30 ° C. 6. The method according to any one of claims 1 to 5,
A method for cleaning an electronic component or the like, wherein the object to be cleaned and removed is a metal contaminant and / or an organic contaminant adhered to the surface of the object to be cleaned. 7. An ultrapure water production system provided with multi-stage means for removing ions, fine particles, organic substances and gases, a semiconductor substrate,
A cleaning device that cleans the ultra-clean surface of an object to be cleaned such as glass substrates, electronic parts products or product materials, or parts for these manufacturing devices with a cleaning solution, and then rinses with ultrapure water, and the cleaning device A cleaning solution supply means for supplying a solution, and a rinse water supply pipe for supplying the ultrapure water produced by the ultrapure water producing apparatus to the cleaning apparatus. A cleaning device for electronic parts or the like is characterized in that the means feeds a liquid in which chlorine gas is dissolved in the ultrapure water produced by the above ultrapure water producing device. 8. The cleaning apparatus for electronic parts according to claim 7, wherein the cleaning solution supply means has an acid addition means.