JP2859081B2 - Wet processing method and processing apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet processing method and a processing apparatus used in a material processing process for industrial products, pharmaceutical products, and the like , and is particularly effective for a semiconductor device manufacturing process.
And a wet processing method .

[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. In particular, semiconductor manufacturing
Metal used in the process contaminates silicon wafers
Problems such as short-circuits caused by adhering as objects,
The chlorine-based gas used as the etching gas is the substrate
There are also problems that remain above. Remove these, and
Obtaining a cleaning solution that does not attack aluminum
It is very difficult with existing technologies. 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 The present invention provides new OH ^- ion water produced by electrolyzing water.
To clean and remove colloidal silica on the semiconductor surface
Produced by electrolysis of water
Metals on Semiconductor Surface by Supplying New H ⁺ Ion Water
This is a wet treatment method characterized by washing and removing contaminants . In the present method, the electrolysis of water is preferably performed in a state where a substance that enhances electrolysis efficiency is added to water, and high electrolysis strength is applied between the anode and the cathode. by adjusting the addition amount of substances which increase the electrolysis current intensity and / or electrolysis efficiency, H ⁺ concentration and OH ^- it is preferably performed while controlling the concentration.

[0005] Further, a processing apparatus for carrying out this method includes a pure water introduction pipe provided with a substance addition system for adding a substance for increasing the electrolysis efficiency to water supplied to the electrolysis water tank, and an H 2 inside. A porous membrane for separating ⁺ ion water and OH ⁻ ion water is provided, and an electrolysis water tank for electrolyzing pure water introduced from the introduction pipe; and a porous membrane in the electrolysis water tank via the porous membrane. an electrode pair provided Te, a DC power source for supplying a direct current to the electrode pairs, the H ⁺ ion water obtained by electrolysis tanks and OH ^- ion water as well as reservoir respectively separately, in which A treatment water tank for treating an object to be treated. In the present apparatus measures the pH value of the treating tank, by adjusting the amount of substances which increase the electrolysis current intensity and / or electrolysis efficiency of the DC power source, H ⁺ concentration and OH in the treated water tank ^- the concentration It is preferable that a pH concentration control system for controlling is provided, and a waste liquid storage tank for storing waste liquid used in the treatment water tank, a water purifier for purifying a supernatant liquid of the waste liquid storage tank with pure water, and ion exchange It is preferable that the obtained pure water is reused through a pure water introduction pipe.

[0006]

The treatment method of the present invention can be applied to industrial products and pharmaceutical products without using a conventionally used solution containing halogen or chlorofluorocarbon, an acidic solution or an alkaline solution, or a gas containing halogen or chlorofluorocarbon. Processing can be performed, and it is particularly effective for cleaning semiconductor products . 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 H ⁺ ion water. This is because heavy metals OH groups in alkaline wash water tends to complex ion with a ligand, easily adsorbed on the surface of the wafer but, H ⁺
This is because ionic water does not form such complex ions with heavy metals, and thus is not easily adsorbed on the wafer 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, in particular , in the process of manufacturing semiconductor products, when removing residual halogens such as residual chlorine, using H ⁺ ion water, if treated at a pH within a specified range, The residue can be removed without damaging the metal material portion. For example, in the 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 HC1 using H ⁺ ionized water, and then activated. The treated aluminum surface can be treated with OH ^- ionized water to stabilize the aluminum surface. In this processing method,
Compared to conventionally used wet processing using pure water, the effect of preventing corrosion is large, and damage to the processed aluminum film and the underlying film is small. 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. When the treatment is performed by the present method, the H ⁺ concentration and the OH ⁻ concentration appropriate for the treatment are adjusted by adjusting the amount of the substance that enhances the electrolytic current intensity of the DC power supply and / or 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. Further, the ionized water used in the present treatment is an unstable ion because an excessive OH ^- ion 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. Embodiment 1 FIG. 1 shows a schematic configuration diagram of a wet processing apparatus of the present invention.
Pure water generated through the ion exchanger 9 is supplied to the electrolysis water tank 1 of FIG. 1 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 the respective water tanks (1-A) and (1-B) are formed.
Are provided with electrode rods 3a and 3b made of Pt or carbon. By connecting a variable DC power supply 5 to these electrode rods 3a and 3b and flowing an electrolytic current, OH ^- ion water and an electrode 3b as an anode are placed in a water tank (1-A) having an electrode 3a as a cathode. H ⁺ ion water is generated in a certain water tank (1-B). 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 to be supplied to the i-wafer. The waste liquid discharged 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 electrolytic 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 the water treatment, treatment with OH ^- water may be performed. In addition, in order to reduce the resistance value of the pure water supplied from the ion exchanger and increase the electrolysis efficiency, a substance in which carbon dioxide is supplied by bubbling or a supporting electrolytic salt such as ammonium acetate is added to the pure water. The addition system 11 is installed. Furthermore,
PH sensors 4a, 4b installed in treated water tanks 6a and 6b
, 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, a high electrolysis (1 kv or more) is applied between the electrodes 3a and 3b. Is preferably installed.

Embodiment 2 Next, an embodiment of a 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.
2a. FIG. 2 is a cross-sectional view of the semiconductor device after the step 22a has been removed and the surface of the interlayer insulating film has been smoothed by polishing using a solution containing colloidal silica slurry.
(B). 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 pure water, carbon dioxide is bubbled and supplied, or a supporting electrolyte salt such as ammonium acetate is added to the pure water to increase the electrolysis efficiency of the ionic water. Furthermore, the OH ^- concentration is detected by a pH sensor installed in the processing tank, and the pH is measured.
Control the concentration. The control in this case is performed based on the electric field current intensity of the DC power supply and the amount of electrolytic supporting salt added. When pure water or high-resistance water is electrolyzed, a high electric field (1 kV
Above).

[0012]

[Effect of the Invention] In the process of manufacturing industrial products and pharmaceutical products, when cleaning, etching, and post-processing are performed
Halogen and Freon or its compounds, or cause pollution by difficult-to-treat industrial waste, according to the present invention, it is possible to treat without causing environmental pollution as described above, especially in the semiconductor product manufacturing process
It is valid . Also, when a substance that enhances 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 process costs 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 according to the present invention.

FIG. 2 is a 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

Claims (10)

(57) [Claims] 1. A wet treatment method comprising supplying fresh OH ^- ion water generated by electrolyzing water to wash and remove colloidal silica on a semiconductor surface. 2. A wet processing method comprising supplying fresh H ⁺ ion water generated by electrolyzing water to wash and remove heavy metal contaminants on a semiconductor surface. Electrolysis wherein water is wet processing method according to claim 1 or 2, wherein is carried out by applying a high electric field intensity between the anode and the cathode. 4. A wet processing method according to claim 3, wherein the electrolytic strength of 10 ³ ~10 ⁴ V / cm. 5. The wet treatment method according to claim 1, wherein the electrolysis of water is performed in a state in which a substance that increases electrolysis efficiency is added to water. 6. An H ⁺ concentration and an OH ⁻ concentration are controlled by adjusting the amount of a substance that enhances the electrolytic current intensity and / or the electrolysis efficiency of the DC power supply.
5. The wet treatment method according to any one of 5 . 7. A state in which a substance for improving electrolysis efficiency is added.
H ⁺ generated by electrolyzing water at
Supplying ion water or OH ^- ion water to the semiconductor surface
In the wet processing method for cleaning and removing the metal, the etching gas remaining on the finely processed metal film is removed by using H ⁺ ionized water whose pH value is controlled so as not to affect the metal material, and then activated. The surface of the metal film
^- wet processing method, characterized by treating with ion water. 8. A pure water introduction pipe provided with a substance addition system for adding a substance for improving electrolysis efficiency to water supplied to an electrolysis water tank, and H ⁺ ion water and OH ^- ion water are separated inside. A porous membrane is provided, an electrolysis water tank for electrolyzing pure water introduced from the introduction pipe, an electrode pair provided in the electrolysis water tank via the porous membrane, and the electrode pair. A DC power supply for supplying a DC current to the H ⁺ ion water and an OH ⁻ ion water obtained in the electrolysis water tank are separately stored, and a half of the object to be treated is stored therein.
A wet treatment apparatus comprising: a treatment water tank for treating a conductor material . 9. measuring the pH value of the treating tank, by adjusting the amount of substances which increase the electrolysis current intensity and / or electrolysis efficiency of the DC power source, H ⁺ concentration and OH in the treated water tank ^- the concentration The wet treatment apparatus according to claim 8, further comprising a pH concentration control system for controlling. 10. A waste water storage tank for storing waste liquid used in a treatment water tank, a purifier for purifying supernatant liquid of the waste liquid storage tank and an ion exchanger, and the obtained pure water is water. The wet processing apparatus according to claim 8 , wherein the wet processing apparatus is reused through an introduction pipe.