JP2000219982A - Wet processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a wet processing without causing any environmental pollution by achieving the liquid processing such as cleaning of works using active acid ionic water or alkaline ionic water containing electrolytic ions generated in the electrolysis of water containing electrolytes. SOLUTION: Alkaline ionic water is generated in an OH- ion water tank 1-A equipped with an electrode 3a forming a cathode, and acid ionic water is generated in an H+ ionic water tank 1-B equipped with an electrode 3b forming an anode by causing an electrolytic current to flow. The generated alkaline ionic water is taken out in a processed water tank 6a and the acid ionic water is taken out in a processed water tank 6b. A Si wafer is placed in a wafer carrier 7a or 7b, and immersed in the processed water tank 6a or 6b. The ionic water is of flowing water type where water is constantly supplied to the Si wafer. The waste water from the processed water tank 6a or 6b is stored in a waste water storage tank 8, and supernatant liquid is formed pure water through a water purifier 10 and an ion exchanger 9, and introduced in a water tank 1 for electrolysis to be recycled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet treatment method used in a material treatment process for industrial products, pharmaceutical products and the like.

[0002]

2. Description of the Related Art In recent years, global environmental problems have attracted interest in various fields as new environmental problems. 2. Description of the Related Art Modern industries have become active, and industrial wastes, medical wastes, industrial wastewaters, and the like have been released into the global environment, causing environmental problems on a global scale. Especially in the process of manufacturing industrial and pharmaceutical products,
In the case of cleaning, etching, and post-processing, the processing has been performed using a solution containing halogen or chlorofluorocarbon, an acidic solution or an alkaline solution such as hydrochloric acid, or a gas containing halogen or chlorofluorocarbon. On the other hand, city water is electrolyzed and Na and Ca
Devices that generate high-concentration alkaline ionized water and use it as health drinking water, and that use acidic ionized water as beauty and face wash have been commercially available since ancient times.

[0003]

Conventionally, a treatment is performed using a solution containing halogen or chlorofluorocarbon such as chlorine, an acid solution or an alkaline solution such as hydrochloric acid, or a gas containing halogen or chlorofluorocarbon which has been used in a cleaning process or the like. In such a case, a halogen compound or a chlorofluorocarbon compound is formed, thereby producing industrial waste which is difficult to treat. On the other hand, with the recent miniaturization of elements constituting a semiconductor integrated circuit, there is an increasing need for a smooth and clean semiconductor wafer surface without damage. Smoothing can be obtained by polishing with a solution containing colloidal silica. After polishing using this solution, colloidal silica remains on the wafer surface. As a method for removing the residual colloidal silica, an aqueous solution of a quaternary alkyl ammonium salt (for example, aqueous ammonia) is used before the wafer is dried. And a hydrogen peroxide solution (pH 10 or more) (see JP-B-56-45295). However, the colloidal silica used here is dried using an aqueous solution of a quaternary alkylammonium salt (for example, a mixed solution of aqueous ammonia and aqueous hydrogen peroxide) after the completion of this step on the wafer surface. Cleaning and removal becomes difficult. There is a possibility that the removal effect can be obtained by treating with the above solution for a long time,
Aluminum dissolves in this solution and is not applicable for embedding where the metal surface is exposed. Also, when the aluminum wiring portion is covered with the interlayer film, the cleaning solution permeates through the pinholes in the interlayer film, so that the aluminum wiring may be eroded. An object of the present invention is to provide a wet processing method and a processing apparatus that can solve such conventional problems.

[0004]

SUMMARY OF THE INVENTION According to the present invention, there is provided a method for treating an electrolyte using active acidic ionic water containing electrolyte ions or active alkaline ionic water containing electrolyte ions produced by electrolyzing water containing electrolyte. This is a wet processing method characterized by performing cleaning, etching or other liquid processing of an object. In the method of the present invention, it is preferable to perform the washing, etching or other liquid treatment of the object to be treated in running active acidic ionized water or active alkaline ionized water, and this includes, for example, water containing an electrolyte. A first step of electrolyzing to produce active acidic ionized water containing electrolyte ions or active alkaline ionized water containing electrolyte ions, and cleaning the object using the active acidic ionized water or alkaline ionized water; A second step of performing etching or other liquid treatment, a third step of mixing the discharged acidic ionic water and the alkaline ionic water to regenerate water containing an electrolyte, and a water containing the regenerated electrolyte Electrolyzing to generate active acidic ionized water or alkaline ionized water containing electrolyte ions, and the second to fourth steps It is possible by repeatedly performing extent.

Further, in the present method, the electrolysis of high-purity water is preferably performed by applying a high electrolysis strength between the anode and the cathode, and the electrolysis current strength and / or electrolysis efficiency of the DC power supply is preferably reduced. It is preferable to control the concentration of acidic ions and the concentration of alkaline ions by adjusting the amount of the substance to be added. According to the present invention, the acidic ionized water is used to remove halide or heavy metal contamination adhering to the object to be processed, and the particle contamination or the contamination adhering to the object to be processed using the alkaline ionized water. A wet treatment method comprising removing organic contamination is provided.

[0006] The treatment method of the present invention can be applied to materials of industrial products and pharmaceutical products without using conventionally used solutions containing halogen or Freon, acidic solutions or alkali solutions, or gases containing halogen or Freon. Processing can be performed. According to this processing method, heavy metal contaminants on a silicon wafer used in a semiconductor manufacturing process are removed by always performing processing with newly supplied acidic ionized water. This is because heavy metals tend to become complex ions having OH groups as ligands in alkaline washing water and are easily adsorbed on the wafer surface, but acidic ionic water does not form such complex ions with heavy metals, so the wafer surface is difficult to form. This is because it is difficult to be adsorbed on the surface.

[0007] In the present treatment method, the pH value of the generated water can be controlled by adjusting the direct current during electrolysis or by adjusting the amount of a substance that increases the electrolysis efficiency. In this case, according to the Purvey diagram, the metal material has a certain range of pH (for example,
Fe: pH 3 to 10) and stable.
If is large or small, the metal material dissolves (etches). Therefore, in the process of manufacturing industrial products and pharmaceutical products, when removing residual halogens such as residual chlorine, treatment with acidic ionized water at a pH within the specified range may damage metal parts. No residue can be removed. For example, in microfabrication of an aluminum alloy film in a semiconductor manufacturing process, etching is performed using chlorine-based gas plasma. After etching, residual chlorine is removed in the form of HCl with acidic ionized water, and then activated. Aluminum surface can be treated with alkaline ionized water to stabilize the aluminum surface. This processing method has a greater corrosion prevention effect and less damage to the processed aluminum film and the base film than the conventionally used wet processing using pure water. In addition, since convection occurs directly on the aluminum surface as compared with the gas ashing process, the effect of removing chlorine remaining on the side surface and the surface of the wiring film is large. When a metal material is treated at a pH exceeding a specified range, it can be used as an etching solution. For example, conventionally, wet etching of a metal material with HC1, phosphoric acid, or the like has been performed, but it can be used as a solution instead of these.

In addition, in the electrolysis of water, the electrolysis is performed in a state in which a substance for increasing the electrolysis efficiency is added, so that the resistance value of pure water is reduced and the generation efficiency is improved. In a process such as a semiconductor manufacturing process in which contamination by heavy metals becomes a problem, carbon dioxide or a supporting electrolyte salt (combination of a quaternary alkylammonium and a cation other than halogen) is suitable as the substance for improving the electrolysis efficiency. When ionic water is generated by electrolysis of pure water, it is preferable to apply high electrolytic strength between the anode and the cathode in order to improve the efficiency of electrolysis. The electrolytic strength at this time is 10 3
A suitable value is about 〜１０10 4 V / cm. Further, when the treatment is performed by the present method, the acid ion concentration and the alkaline ion concentration appropriate for the treatment are adjusted by adjusting the electrolytic current intensity of the DC power supply and / or the amount of the substance that increases the electrolysis efficiency as described above. In addition, it is preferable to perform the treatment while controlling the temperature of the treatment water tank and the treatment time.
Further, according to the present invention, the used waste liquid is converted into pure water through a water purifier and an ion exchanger, and can be reused to effectively use water resources.

Further, the wet treatment method of the present invention can remove colloidal silica remaining after the polishing or smoothing process, and is particularly effective for washing and removing dried colloidal silica. In addition, the ionic water used in the present treatment is an unstable ion because an excessive amount of alkaline ions is temporarily generated by electrolysis. Therefore, the solution returns to the neutral solution with the passage of time, so that even if the aluminum solution penetrates through the pinhole of the interlayer film, it does not erode the aluminum wiring. Furthermore, the conventionally used alkaline solution consumes a large amount of solution for cleaning, requires high cost for waste liquid treatment, and may cause a problem for environmental pollution. On the other hand, the present cleaning method can perform processing without using a solution, so that the process cost can be drastically reduced, and it is also temporarily alkaline, reacts with the object to be treated, and forms a solution in a neutral region. Returning is a very environmentally friendly process.
Further, as described above, the present treatment method can control the pH value of the generated water by varying the DC current during the electrolysis, so that the A
It can be applied to the washing of the colloidal silica solution within a range that does not erode l.

[0010]

Next, an embodiment of the present invention will be described.

FIG. 1 shows a schematic configuration diagram of a processing apparatus used in the wet processing method of the present invention. Electrolysis tank 1 of FIG.
Then, pure water generated through the ion exchanger 9 is supplied from a pure water introduction pipe. A porous membrane 2 of polysilicon or the like is formed as a diaphragm in the electrolysis water tank 1, and an electrode rod 3a made of Pt or carbon is formed in each of the water tanks (1-A) and (1-B). , 3b. A variable DC power supply 5 is connected to the electrode rods 3a and 3b, and an electrolytic current is applied to the electrode rods 3a and 3b, so that a water tank (1
The -A) OH ^- (alkaline) ionized water, the water tank has electrodes 3b which serves as an anode (1-B) generates H ⁺ (acidic) ionized water. The generated OH-ion water is treated in the treatment tank 6a.
Then, the H ⁺ ion water is taken out to the treated water tank 6b. An Si wafer, which is a typical object to be processed in a semiconductor manufacturing process, is placed in a wafer carrier 7a or 7b and immersed in the processing water tank 6a or 6b. In this case, the ion water is always S
It takes the form of running water supplied to the i-wafer. The waste liquid from the treated water tank 6a or the treated water tank 6b is stored in a waste liquid storage tank 8, and the supernatant liquid is made into pure water through a water purifier 10 and an ion exchanger 9, and introduced into the electrolysis water tank 1 from a pure water introduction pipe. Reuse. When cleaning the Si wafer, the treatment may be performed only with the OH ^- water in the treatment water tank 6a or the H ⁺ water in the treatment water tank 6b, or the H ⁺ water treatment may be performed after the OH ^- water treatment.
After H ⁺ water treatment, treatment with OH ^- water may be performed. Also,
In order to reduce the resistance value of pure water supplied from the ion exchanger and increase the electrolysis efficiency, bubbling and supplying carbon dioxide, or a substance addition system that adds a supporting electrolytic salt such as ammonium acetate to pure water 11 is installed. Further, pH sensors 4a installed in the treated water tanks 6a and 6b,
At 4b, the H ⁺ concentration and the OH ^- concentration are detected, and the results are fed back to the electrolytic current intensity of the DC power supply 5 and the addition amount from the substance addition system 11 through the pH concentration control system 12. When pure water or high-resistance water is electrolyzed, high electrolysis (1 kv or more) is applied between the electrodes 3a and 3b.
Therefore, it is preferable to provide an electrode rod (not shown) for grounding in the treatment water tanks 6a and 6b.

Next, an embodiment of the wet processing method according to the present invention will be described. FIG. 2A is a cross-sectional view of the semiconductor device before the smoothing process. The metal wiring 21 is covered with an interlayer insulating film 22 such as a plasma oxide film.
Has a step 22a. FIG. 2B is a cross-sectional view of the semiconductor device after the step 22a has been removed by polishing using a solution containing colloidal silica slurry and the surface of the interlayer insulating film has been smoothed. After the smoothing process, as shown in FIG. 2B, the colloidal silica slurry 23 remains on the surface of the interlayer insulating film. This wafer is immersed in a treatment tank of OH ^- ion water generated by the apparatus as shown in Example 1 and washed at 70 ° C for 5 to 10 minutes. In this case, the pH is controlled to about 9 to 10. The wafer washed with ion water is treated with pure water for several minutes. In order to increase the electrolysis efficiency of the purified water, carbon dioxide is supplied by bubbling, or a supporting electrolyte salt such as ammonium acetate is added to the purified water in order to increase the electrolysis efficiency of the purified water. Further, the OH ^- concentration is detected by a pH sensor installed in the processing tank, and the pH concentration is controlled. The control in this case is
The measurement is performed based on the electric field current intensity of the DC power supply and the amount of the electrolytic supporting salt added. When electrolyzing pure water or high-resistance water, a high electric field (1 kV or more) is applied between the electrodes.

[0013]

According to the present invention, in the process of manufacturing industrial products and pharmaceutical products, when cleaning, etching or other liquid processing cleaning of an object to be processed, contamination with halogen, chlorofluorocarbon or its compound, or difficult-to-treat industrial waste is caused. However, according to the present invention, processing can be performed without causing environmental pollution as described above. Also, when a substance that enhances the electrolysis efficiency is added to pure water, it can serve as a small amount of acid and alkali solutions that have been conventionally used, greatly reducing the process cost and reducing the amount of waste. Can be drastically reduced. Therefore, it is possible to drastically reduce industrial waste, medical waste, industrial wastewater, and the like, which are released to the global environment and are a source of environmental problems caused on a global scale. Further, by reusing the treatment waste liquid as pure water, water resources can be effectively used. Further, according to the wet processing method of the present invention, it is possible to remove colloidal silica remaining after a polishing or smoothing process in the manufacture of a semiconductor device. In this case, the treatment method of the present invention is effective for removing dried colloidal silica, and does not cause erosion of the metal wiring portion incorporated in the semiconductor device.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a wet processing apparatus used in the present invention.

FIG. 2 is a cross-sectional view of a semiconductor device for explaining an example of a wet processing method according to the present invention.

[Explanation of symbols]

1 electrolysis tanks 1-A OH ^- ionized water aquarium 1-B H ⁺ ionized water tub 2 porous membrane (diaphragm) 3a electrode rod (cathode) 3b electrode rod (anode) 4a, 4b pH sensor 5 DC power source 6a, 6b Treated water tank 7a, 7b Wafer carrier 8 Waste liquid storage tank 9 Ion exchanger 10 Water purifier 11 Substance addition system 12 pH concentration control system 21 Metal wiring 22 Interlayer insulating film 22a Stepped portion 23 Colloidal silica slurry

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/3063 H01L 21/306 L

Claims (7)

[Claims] 1. An object for cleaning an object to be treated using active acidic ion water containing electrolyte ions or active alkaline ion water containing electrolyte ions generated by electrolyzing water containing an electrolyte, or other liquids. A wet treatment method comprising performing treatment. 2. The wet treatment method according to claim 1, wherein the object to be treated is washed or another liquid treatment is performed in flowing water of the active acidic ion water or the active alkaline ion water. 3. a first step of electrolyzing water containing an electrolyte to produce active acidic ionic water containing electrolyte ions or active alkaline ionic water containing electrolyte ions;
The second step of washing the object to be treated using the active acidic ionized water or alkaline ionized water, or performing other liquid treatment, and mixing the discharged acidic ionized water and alkaline ionized water to include an electrolyte A third step of regenerating water; and a fourth step of electrolyzing water containing the regenerated electrolyte to produce active acidic ionized water or alkaline ionized water containing electrolyte ions. A wet treatment method comprising repeating the fourth step. 4. The wet treatment method according to claim 1, wherein the electrolysis of water is performed by applying a high electrolytic strength between the anode and the cathode. 5. The method according to claim 1, wherein the concentration of acid ions and the concentration of alkaline ions are controlled by adjusting the amount of a substance that enhances the intensity of electrolytic current and / or the efficiency of electrolysis of the DC power supply. 5. The wet treatment method according to any one of 4. 6. The wet treatment method according to claim 1, wherein the acidic ionized water is used to remove a halide or heavy metal contamination adhering to the object to be treated. 7. The wet processing method according to claim 1, wherein the alkaline ionized water is used to remove particle contamination or organic substance contamination adhering to the object to be processed.