JPH0547734A - Cleaning apparatus - Google Patents

Abstract

PURPOSE:To effectively remove impurities on a surface of an optical processing element by incorporating a function of shielding a light in a part of a member to be processed, in contact with chemicals or ultrapure water to be used for cleaning in an apparatus for cleaning or drying the member to be processed. CONSTITUTION:A cleaning vessel 3 for cleaning semiconductor 2 is mounted in a light shielding vessel 1 for shielding an external light. Nitrogen gas 6 is supplied from a nitrogen gas supply unit 4 to the vessel 1 through a tube 5. On the other hand, ultrapure water 9 in which dissolved oxygen is removed, is supplied from an ultrapure water supply unit 7 to the vessel 3 mounted in the vessel 1 through a tube 8. Further, the ultrapure water after the semiconductor 2 is cleaned, is fed to a waste water processor 12 through a waste water reservoir 10 and a piping 11 to be processed. The gas 6 substituted for the atmosphere in the vessel 1 is discharged through a discharge valve 13 and a piping 14. Thus, impurities on the surface of a member to be processed can be effectively removed without adherence of the impurities due to excitation of electrons or holes by a light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is for cleaning or drying an object to be processed, such as a semiconductor wafer, in a step of performing a cleaning process so as to completely remove adhered substances. Involved in cleaning equipment.

[0002]

2. Description of the Related Art Conventionally, cleaning of semiconductors has been performed by using, for example, the following techniques. That is, a mixture of sulfuric acid / hydrogen peroxide water mixed solution, hydrochloric acid / hydrogen peroxide water mixed solution, ammonia / hydrogen peroxide water mixed solution, chemical solution such as hydrofluoric acid / hydrogen peroxide aqueous solution, and ultrapure water are used in combination to obtain an atomic level on the semiconductor surface. This is a technique for removing organic substances, fine particles, metals, and natural oxide films adhering to the semiconductor surface without impairing the flatness in the above. For example, the steps shown below are used. (1) Sulfuric acid / hydrogen peroxide cleaning (sulfuric acid: hydrogen peroxide = 4: 1, volume ratio) 5 minutes (2) Ultrapure water cleaning 5 minutes (3) Sulfuric acid / hydrogen peroxide cleaning (sulfuric acid: hydrogen peroxide = 4: 1, volume ratio) 5 minutes (4) Ultrapure water cleaning 5 minutes (5) Hydrofluoric acid hydrogen peroxide cleaning (hydrofluoric acid 0.5%, hydrogen peroxide 10%) 1 minute (6) Ultrapure water cleaning 5 minutes (7 ) Sulfuric acid hydrogen peroxide cleaning (sulfuric acid: hydrogen peroxide = 4: 1, volume ratio) 5 minutes (8) Ultrapure water cleaning 10 minutes (9) Fluoric acid hydrogen peroxide cleaning (hydrofluoric acid 0.5%, hydrogen peroxide 10 %) 1 minute (10) Ultrapure water cleaning 10 minutes (11) Ammonia hydrogen peroxide cleaning (Ammonia water: Hydrogen peroxide: Ultrapure water = 0.05: 1: 5, Volume ratio) 10 minutes (12) Ultrapure water Cleaning 10 minutes (13) High temperature ultrapure water immersion (about 90 ℃) 10 minutes (14) Fluorine hydrogen peroxide cleaning (hydrofluoric acid 0.5%, hydrogen peroxide 10%) 1 minute (15) Ultrapure water cleaning 10 minutes ( 16) Hydrochloric acid hydrogen peroxide cleaning (hydrochloric acid: hydrogen peroxide: ultrapure water = 1: 1: 6, body Product ratio) 10 minutes (17) High temperature ultrapure water immersion (about 90 ° C) 10 minutes (18) Ultrapure water cleaning 10 minutes (19) Hydrofluoric acid hydrogen peroxide cleaning (hydrofluoric acid 0.5%, hydrogen peroxide 10%) 1 minute (20) Ultrapure water cleaning 10 minutes (21) Nitrogen gas blow drying 2 minutes

[0003]

However, the above-mentioned prior art has at least the following two problems.

First, in the conventional semiconductor cleaning technique, all the steps are performed under illumination, or at least in an environment where light shielding is not taken into consideration. Therefore, a semiconductor which is an object to be cleaned or dried is irradiated. It is excited by the energy of the light. At that time, the number of free electrons and holes in the semiconductor increases as compared with the semiconductor in an environment where light is blocked. For example, silicon (for example, boron (B))
When a semiconductor having a p-type region doped with is washed in an environment with light irradiation, electrons excited by light exchange charge with metal ions (having a positive charge) in the washing liquid, and the metal is a semiconductor. Adsorbs on the surface. On the other hand, for example, when a semiconductor having an n-type region in which, for example, phosphorus (P) is added to silicon is washed in an environment with light irradiation, holes excited by light are anions in the washing liquid. Charges are exchanged with (having a negative charge), and anions are adsorbed on the semiconductor surface.

Further, in the conventional semiconductor cleaning technique, at least ultrapure water is not cleaned in an inert gas atmosphere. Therefore, oxygen in the atmosphere is dissolved in the ultrapure water, so that the semiconductor surface to be processed is treated. As a result, the natural oxide film that deteriorates the characteristics of the semiconductor grows on the surface of the semiconductor during the cleaning with ultrapure water. Moreover, when a natural oxide film grows, a metal that is more easily oxidized than a semiconductor such as silicon, for example,
Iron (Fe), Aluminum (Al), Sodium (N
In the case of a) and the like, metal oxides are generated and taken into the natural oxide film, so that the semiconductor surface is metal-contaminated. That is, when semiconductor cleaning is not performed in an inert atmosphere, it causes metal contamination due to the formation of a natural oxide film which itself deteriorates the characteristics of the semiconductor and the incorporation of metal oxides into the natural oxide film.

The present invention effectively removes impurities on the surface of a semiconductor or the like from the object to be processed, and causes impurities to adhere to the semiconductor surface due to the excitation of electrons or holes by light. It is an object of the present invention to provide a cleaning device that does not cause deterioration of the surface such as a natural oxide film.

[0007]

A cleaning device of the present invention is a device for cleaning or drying an object to be processed, wherein at least a portion of the object to be processed is exposed to a chemical solution or ultrapure water used for cleaning. It is characterized in that means for shutting off is provided.

[0008]

The cleaning apparatus of the present invention has a function of blocking light, in the apparatus for cleaning or drying an object to be processed, since at least a portion where the semiconductor is in contact with the chemical solution or ultrapure water used for cleaning has a function of blocking light. The semiconductor that is the processing body is not excited by the energy of light. As a result, it is possible to effectively remove the impurities on the surface of the object to be processed without causing the adhesion of the impurities resulting from the excitation of electrons or holes (holes) by light to the semiconductor that is the object to be processed. it can. Further, since the cleaning apparatus of the present invention has a container capable of replacing the internal atmosphere, a function of supplying an inert gas into the container, and a function of supplying ultrapure water with reduced dissolved oxygen, It is possible to effectively remove impurities on the surface of the object to be processed without causing deterioration of the natural oxide film or the like on the surface of the object.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention.

A cleaning container 3 for cleaning the semiconductor 2 which is the object to be processed is installed inside the light-shielding container 1 which can block the light from the outside and replace the internal atmosphere.

Nitrogen gas 6 is supplied to the light shielding container 1 from an inert gas (for example, nitrogen gas) supply device 4 through a nitrogen gas supply pipe 5 connected to the nitrogen gas supply device 4. Has been done.

On the other hand, a cleaning container installed in the light-shielding container is connected to the ultrapure water supply device 7 from an ultrapure water supply device 7 having a function of removing dissolved oxygen in water.
The ultrapure water 9 from which dissolved oxygen has been removed is supplied through the ultrapure water supply pipe 8.

Further, the ultrapure water after cleaning the semiconductor 2 is sent to a waste liquid processing unit 12 through a waste liquid receiving container 10 and a waste liquid sending pipe 11 for processing.

Further, the nitrogen gas 6 in which the atmosphere in the light-shielding container has been replaced is exhausted through the gas exhaust valve 13 and the gas exhaust pipe.

Since this embodiment is configured as described above, when the semiconductor 2 which is the object to be processed is washed with ultrapure water 9 from which dissolved oxygen has been removed, the semiconductor is exposed to external light. Therefore, the semiconductor 2 is not excited by the energy of light, and as a result, the semiconductor, which is the object to be processed, is exposed to electrons or holes due to light on the semiconductor surface. It is possible to perform cleaning without causing the adhesion of impurities derived from excitation.

Further, since the present embodiment is configured as described above, when the semiconductor 2 which is the object to be cleaned is cleaned with the ultrapure water 9 from which dissolved oxygen is removed, the inside of the light shielding container 1 is cleaned. Oxygen gas is not dissolved in the ultrapure water 9 from the cleaning atmosphere, and therefore the surface of the semiconductor 2 that is the object to be processed is not oxidized. As a result, cleaning can be performed without causing deterioration of the natural oxide film or the like on the semiconductor surface.

Table 1 shows the deposited metal and natural oxide film thickness on the surface of the silicon wafers after cleaning five silicon wafers (n type 100) using the apparatus shown in FIG. The results are obtained by measuring whether the atmosphere is replaced by gas or not.

The light-shielding container 1 has a volume of 20 l, the flow rate of nitrogen gas supplied to the light-shielding container 1 is 20 l / min, the oxygen concentration in the nitrogen gas is 1 ppb or less, and the water concentration in the nitrogen gas is 1 ppb.
Below. The volume of the cleaning container 3 is 0.5 l, the flow rate of ultrapure water supplied to the cleaning container 3 is 3 l / min, the concentration of dissolved oxygen in the ultrapure water is 10 ppb, and the copper ion (C
u ²⁺ ) concentration is 1 ppt, iron ion (Fe ²⁺ ) in ultrapure water
The concentration was 1 ppt. The cleaning time with ultrapure water was 60 minutes.

[0019]

[Table 1] As shown in Table 1, when the semiconductor, which is the conventional semiconductor cleaning method, is the object to be processed and is irradiated with light, and the semiconductor is cleaned without replacing the atmosphere for cleaning with an inert gas (for example, nitrogen gas), cleaning is performed. After the silicon wafer surface, copper,
Metallic impurities such as iron were detected, and the formation of native oxide film was also detected. On the other hand, in the case of cleaning the semiconductor of the present invention by blocking light to the semiconductor that is the object to be processed and sufficiently replacing the atmosphere for cleaning with an inert gas (for example, nitrogen),
Metal impurities such as copper and iron are not detected on the surface of the silicon wafer after cleaning, and formation of a natural oxide film is not detected.

Further, even if the light to the object to be processed is blocked, unless the atmosphere for cleaning is sufficiently replaced with an inert gas (for example, nitrogen), the surface of the silicon wafer after cleaning is naturally It was found that iron, which is more easily oxidized than silicon, adheres as the oxide film grows.

The above results show that, by using the cleaning apparatus of this embodiment, impurities are attached to the semiconductor surface, which is the object to be cleaned, due to the excitation of electrons or holes by light on the semiconductor surface. This indicates that cleaning was possible without causing deterioration of the natural oxide film or the like on the semiconductor surface.

In the present embodiment, the container 1 capable of shielding light is used to shield the object to be treated, but the light may be shielded by shielding the entire light inside the room where the cleaning is performed. ,
Alternatively, other light shielding means may be used. Further, although the present embodiment has been described using nitrogen gas, argon gas which is inert to the object to be processed may be used similarly to nitrogen gas, and other inert gas may be used. The effect is obtained. Further, although the present embodiment has been described with respect to the ultrapure water cleaning process as an example, even in the drying process after the ultrapure water cleaning, by drying the cleaned semiconductor in a light-shielding and inert atmosphere, more impurities can be attached. Alternatively, it becomes possible to effectively prevent the formation of the natural oxide film. Of course, also in other steps of semiconductor cleaning, in a light-shielding and inert atmosphere,
By drying the washed semiconductor, it becomes possible to effectively prevent the attachment of impurities or the formation of a natural oxide film.

[0023]

As described above, according to the invention of claim 1, in an apparatus for cleaning or drying an object to be processed, at least the object to be processed is a chemical solution or ultrapure water used for cleaning. Since the contacting part has a function of blocking light, the semiconductor or the like to be processed is not excited by the energy of light, and as a result, the semiconductor or the like to be processed is not processed. It is possible to obtain a cleaning apparatus capable of effectively removing impurities on the surface of the object to be processed without causing impurities to adhere to the surface of the body due to excitation of electrons or holes by light.

Further, according to the invention of claim 2,
The apparatus for cleaning or drying the object to be processed has a container capable of replacing the internal atmosphere, a function of supplying an inert gas into the container, and a function of supplying ultrapure water with reduced dissolved oxygen. It is possible to obtain a cleaning device capable of effectively removing impurities on the surface of the object to be processed without causing deterioration of the surface of the object to be processed such as a natural oxide film.

According to the third aspect of the present invention, since at least a portion of the object to be treated is in contact with the chemical solution or ultrapure water used for cleaning in the container capable of displacing the internal atmosphere, the object to be treated is installed. It is more effective to obtain a cleaning device capable of effectively removing impurities on the surface of the object to be processed without causing deterioration of the surface such as a natural oxide film.
According to the invention of claim 4, since at least the object to be processed is installed in the container capable of displacing the internal atmosphere, a portion for final cleaning with ultrapure water and drying of the attached ultrapure water is installed. It is more effective to obtain a cleaning device capable of effectively removing impurities on the surface of the object to be processed without causing deterioration of the surface such as a natural oxide film.

According to the invention of claim 5, since the inert gas is nitrogen, it is effective in reducing the running cost.

According to the invention of claim 6, since the inert gas is argon, it is as inexpensive as nitrogen and easily available, and is effective in reducing running costs.

According to the invention of claim 7, the oxygen concentration in the active gas is 1 ppm or less, and the dissolved oxygen in the ultrapure water in which the dissolved oxygen is reduced is 50 ppb or less. It is more effective to obtain a cleaning device that can effectively remove impurities on the surface of the object to be processed without causing deterioration of the natural oxide film or the like.

According to the invention of claim 8, since the light to be blocked has a function of blocking light having energy of 1.1 eV or more, the energy to be processed by the object to be processed is Is not excited, and as a result, the target object to be processed can be processed without causing impurities to adhere to the surface of the target object due to the excitation of electrons or holes by light. It is effective to obtain a cleaning device capable of effectively removing impurities on the body surface.

The invention according to claim 9 is effective because the light to be blocked has a function of blocking light having energy of 3.4 eV or more. The invention according to claim 10 is more effective because the light to be blocked has a function of blocking light having energy of 6.2 eV or more.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a cleaning device according to an embodiment of the present invention.

[Explanation of symbols]

 1 light-shielding container, 2 semiconductor (object to be processed), 3 cleaning container, 4 inert gas supply device, 5 inert gas supply pipe, 6 inert gas, 7 ultrapure water supply device (having dissolved oxygen removal function), 8 ultrapure water supply pipe, 9 ultrapure water, 10 waste liquid receiving container, 11 waste liquid sending pipe, 12 waste liquid processing device, 13 gas exhaust valve, 14 gas exhaust pipe.

Claims (10)

[Claims] 1. A device for cleaning or drying an object to be processed, characterized in that at least a part of the object to be processed that comes into contact with a chemical solution or ultrapure water used for cleaning is provided with a means for blocking light. Cleaning device. 2. A container which can replace the internal atmosphere, a means for supplying an inert gas into the container, and a means for supplying ultrapure water with reduced dissolved oxygen. The cleaning device according to 1. 3. A container capable of replacing the internal atmosphere,
3. The cleaning apparatus according to claim 1, wherein at least a portion of the object to be treated is in contact with a chemical solution or ultrapure water used for cleaning. 4. A container capable of replacing the internal atmosphere,
The cleaning apparatus according to any one of claims 1 to 3, wherein at least a portion for subjecting the object to be processed to final cleaning with ultrapure water and drying of the attached ultrapure water is installed. 5. The cleaning apparatus according to any one of claims 1 to 4, wherein the inert gas is nitrogen. 6. The cleaning apparatus according to claim 1, wherein the inert gas is argon. 7. The oxygen concentration in the inert gas is 10 p
7. The cleaning apparatus according to claim 1, wherein the dissolved oxygen in the ultrapure water in which the dissolved oxygen is reduced to pm or less is 50 ppb or less. 8. The cleaning apparatus according to claim 1, wherein the light to be blocked has a function of blocking light having an energy of 1.1 eV or more. 9. The cleaning apparatus according to claim 1, wherein the light to be blocked has a function of blocking light having an energy of 3.4 eV or more. 10. The cleaning apparatus according to claim 1, wherein the light to be blocked has a function of blocking light having an energy of 6.2 eV or more.