Substrate processing apparatus, substrate processing method, and storage medium storing a computer program for performing substrate processing method

A substrate processing apparatus according to the present invention comprises: a processing part configured to process a substrate; a chemical-liquid storing container configured to store a chemical liquid; a chemical-liquid supply driving part configured to supply the chemical liquid from the chemical-liquid storing container into the processing part; a circulation line configured to circulate the chemical liquid stored in the chemical-liquid storing container; and a mixture generating part provided on the circulation line. An inert-gas supply source is configured to supply an inert gas into the mixture generating part. The mixture generating part is configured to mix the chemical liquid supplied from the chemical-liquid storing container and the inert gas supplied from the inert-gas supply source with each other so as to generate a gas-liquid mixture.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2010-53048 filed on Mar. 10, 2010, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a substrate processing apparatus, a substrate processing method, and a storage medium storing a computer program for performing the substrate processing method. In particular, the present invention relates to a substrate processing apparatus, a substrate processing method, and a storage medium storing a computer program for performing the substrate processing method, which are capable of reducing oxygen dissolved in a chemical liquid so as to improve processing efficiency of a substrate and to improve reliability.

2. Description of Related Art

There has been conventionally known a substrate processing apparatus configured to clean a substrate such as a semiconductor wafer or a glass substrate for LCD (herein referred to simply as “wafer”), by immersing the wafer in a cleaning liquid such as a deionized water or a chemical liquid (e.g., hydrogen fluoride, HF) stored in a cleaning tank (see, JP11-97403A, for example). In such a substrate processing apparatus, the chemical liquid is stored in a chemical-liquid storing container. When a wafer is cleaned with a chemical liquid, the chemical liquid is supplied from the chemical-liquid storing container into the cleaning tank, so that an oxide film on a surface of the wafer is etched. In addition, a deionized water is stored in a deionized-water storing container. When a wafer is cleaned with a chemical liquid, the deionized water is supplied from the deionized-water storing container into the cleaning tank. Further, when a wafer is cleaned with a deionized water, the deionized water is supplied into the cleaning tank, so that the wafer is cleaned (rinsed) with the deionized water.

When oxygen is dissolved in the deionized water to be supplied into the cleaning tank, there occurs a problem in that an oxide film is formed on the surface of the wafer by the oxygen. Thus, the deionized water is generally deaerated beforehand so as to reduce oxygen dissolved in the deionized water.

SUMMARY OF THE INVENTION

On the other hand, when oxygen is dissolved in the chemical liquid, there is a possibility that an oxide film might be formed on the surface of the wafer by the oxygen. In this case, it is difficult to efficiently remove the oxide film from the wafer surface when the wafer is cleaned with the chemical liquid, resulting in deterioration in cleaning efficiency of the wafer.

JP2006-269668A discloses a substrate processing apparatus that removes polymer (resist residue) remaining on a substrate, by using a polymer removal liquid as a cleaning liquid. In JP2006-269668A, oxygen molecules are removed from a chemical liquid by causing the chemical liquid to pass through a hollow fiber separation membrane with the use of a vacuum pump, so as to restrain or prevent an oxidation reaction on the substrate.

However, the chemical liquid such as HF in use for etching an oxide film formed on a wafer W is strongly acidic. Thus, when the method disclosed in JP2006-269668A is used for removing oxygen dissolved in the chemical liquid such as HF, there is a problem in that the vacuum pump corrodes away.

The present invention has been made in view of the above circumstances. The object of the present invention is to provide a substrate processing apparatus, a substrate processing method, and a storage medium storing a computer program for performing the substrate processing method, which are capable of reducing oxygen dissolved in a chemical liquid so as to improve processing efficiency of a substrate and to improve reliability.

The present invention provides a substrate processing apparatus comprising: a processing part configured to process a substrate with the use of a chemical liquid; a chemical-liquid storing container configured to store the chemical liquid; a chemical-liquid supply driving part configured to supply the chemical liquid, from the chemical-liquid storing container into the processing part; a circulation line configured to circulate the chemical liquid stored in the chemical-liquid storing container; a mixture generating part provided on the circulation line; and an inert-gas supply source configured to supply an inert gas into the mixture generating part; wherein the mixture generating part is configured to mix the chemical liquid supplied from the chemical-liquid storing container and the inert gas supplied from the inert-gas supply source with each other so as to generate a gas-liquid mixture, and to supply the gas-liquid mixture into the chemical-liquid storing container.

In the aforementioned substrate processing apparatus, it is preferable that the mixture generating part is formed of an ejector configured to suck the chemical liquid from the chemical-liquid storing container, due to a flow of the supplied inert gas, and to mix the chemical liquid and the inert gas with each other so as to generate the gas-liquid mixture.

In addition, in the aforementioned substrate processing apparatus, it is preferable that the inert-gas supply source is configured to supply an inert gas into the chemical-liquid storing container; a gas supply destination switching part configured to switch a destination of the inert gas supplied from the inert-gas supply source, between the mixture generating part and the chemical-liquid storing container, is disposed between the inert-gas supply source and the mixture generating part; when the chemical liquid is circulated in the circulation line, the inert gas is supplied into the mixture generating part; and when the chemical liquid is supplied into the processing part, the inert gas is supplied into the chemical-liquid storing container.

In addition, in the aforementioned substrate processing apparatus, it is preferable that a first gas supply line configured to supply the inert gas into the mixture generating part is disposed between the inert-gas supply source and the mixture generating part; the first gas supply line is provided with a first gas supply opening and closing valve; a second gas supply line configured to supply the inert gas into the chemical-liquid storing container is disposed between the inert-gas supply source and the chemical-liquid storing container; the second gas supply line is provided with a second gas supply opening and closing valve; and the gas supply destination switching part is formed of the first gas supply opening and closing valve and the second gas supply opening and closing valve.

In addition, in the aforementioned substrate processing apparatus, it is preferable that the chemical-liquid storing container is provided with an inlet part configured to introduce the gas-liquid mixture supplied from the mixture generating part into the stored chemical liquid.

In addition, in the aforementioned substrate processing apparatus, it is preferable that a chemical-liquid supply line configured to supply the chemical liquid into the processing part is disposed between the processing part and the chemical-liquid storing container; the chemical-liquid supply line is provided with a chemical-liquid supply opening and closing valve; the circulation line is provided with a first circulation opening and closing valve on a part where the chemical liquid is supplied from the chemical-liquid storing container into the mixture generating part; when the chemical-liquid supply opening and closing valve is closed, the first circulation opening and closing valve is opened to supply the chemical liquid into the mixture generating part; and when the chemical-liquid supply opening and closing valve is opened, the first circulation opening and closing valve is closed to supply the chemical liquid into the processing part.

In addition, in the aforementioned substrate processing apparatus, it is preferable that a gas discharge line configured to discharge a gas from an inside of the chemical-liquid storing container is connected to an upper part of the chemical-liquid storing container.

In addition, in the aforementioned substrate processing apparatus, it is preferable that the gas discharge line is provided with a gas discharge opening and closing valve, and the gas discharge opening and closing valve is opened when the chemical-liquid supply opening and closing valve is closed.

In addition, in the aforementioned substrate processing apparatus, it is preferable that the circulation line is provided with a second circulation opening and closing valve on a part where the gas-liquid mixture is supplied from the mixture generating part into the chemical-liquid storing container, and the second circulation opening and closing valve is opened when the chemical-liquid supply opening and closing valve is closed, while the second circulation opening and closing valve is closed when the chemical-liquid supply opening and closing valve is opened.

The present invention provides a substrate processing method that processes a substrate by using a substrate processing apparatus including a processing part configured to process a substrate with the use of a chemical liquid, a chemical-liquid storing container configured to store the chemical liquid, and an inert-gas supply source, the substrate processing method comprising: mixing a chemical liquid and an inert gas in a mixture generating part by supplying a chemical liquid from the chemical-liquid storing container into the mixture generating part, and by supplying an inert gas from the inert-gas supply source into the mixture generating part, so as to generate a gas-liquid mixture, and supplying the generated gas-liquid mixture into the chemical-liquid storing container so as to circulate the chemical liquid; and supplying the chemical liquid from the chemical-liquid storing container into the processing part so as to process a substrate in the processing part.

In the aforementioned substrate processing method, it is preferable that the mixture generating part is formed of an ejector, and while the chemical liquid is circulated, the ejector sucks the chemical liquid from the chemical-liquid storing container, due to a flow of the supplied inert gas, and mixes the chemical liquid and the inert gas with each other so as to generate the gas-liquid mixture.

In addition, in the aforementioned substrate processing method, it is preferable that while the substrate is processed, an inert gas is supplied into the chemical-liquid storing container.

In the aforementioned substrate processing method, it is preferable that while the chemical liquid is circulated, a gas is discharged from an inside of the chemical-liquid storing container through a gas discharge line connected to an upper part of the chemical-liquid storing container.

The present invention provides a storage medium storing a computer program for performing a substrate processing method that processes a substrate by using a substrate processing apparatus including a processing part configured to process a substrate with the use of a chemical liquid, a chemical-liquid storing container configured to store the chemical liquid, and an inert-gas supply source, the substrate processing method comprising: mixing a chemical liquid and an inert gas in a mixture generating part by supplying a chemical liquid from the chemical-liquid storing container into the mixture generating part, and by supplying an inert gas from the inert-gas supply source into the mixture generating part, so as to generate a gas-liquid mixture, and supplying the generated gas-liquid mixture into the chemical-liquid storing container so as to circulate the chemical liquid; and supplying the chemical liquid from the chemical-liquid storing container into the processing part so as to process a substrate in the processing part.

According to the present invention, oxygen dissolved in a chemical liquid can be reduced so as to improve processing efficiency of a substrate and to improve reliability.

DETAILED DESCRIPTION OF THE INVENTION

First Embodiment

A first embodiment of the present invention is described with reference toFIGS. 1 and 2.FIGS. 1 and 2are views for explaining the first embodiment of a substrate processing apparatus, a substrate processing method, and a storage medium storing a computer program for performing the substrate processing method.

As shown inFIG. 1, a substrate processing apparatus1includes: a cleaning tank (processing part)10configured to clean a plurality of substrates (e.g., semiconductor wafers, hereinafter referred to simply as “wafers W”) by using a chemical liquid (e.g., hydrogen fluoride, HF) or a deionized water; a chemical-liquid storing container20configured to store the chemical liquid; a chemical-liquid supply driving part23configured to supply the chemical liquid from the chemical-liquid storing container20into the cleaning tank10; and an inert-gas supply source40configured to supply an inert gas (N2gas) into the chemical-liquid storing container20. In this embodiment, the chemical-liquid supply driving part23is formed of the inert-gas supply source40. When the inert-gas supply source40pressurizes an inert gas and supplies the pressurized inert gas into the chemical-liquid storing container20, an inside of the chemical-liquid storing container20is pressurized so that the chemical liquid therein is supplied into the cleaning tank10. In addition, the inert-gas supply source40is configured to supply an inert gas to a mixture generating part31which will be described below. A deionized-water supply source62for supplying a deionized water is connected to the cleaning tank10. Similarly to the above, the deionized-water supply source62is configured to pressurize a deionized water and to supply the pressurized deionized water into the cleaning tank10.

Disposed on a lower part of the cleaning tank10is a nozzle11for jetting a chemical liquid supplied from the chemical-liquid storing container20, or a deionized water supplied from the deionized-water supply source62, toward wafers W. Thus, a chemical liquid or a deionized water is jetted toward wafers W in the cleaning tank10, so that the wafers W are cleaned.

In addition, a drying chamber12for drying cleaned wafers W is disposed above the cleaning tank10. A shutter13is provided between the cleaning tank10and the drying chamber12, whereby the cleaning tank10and the drying chamber12can be shielded from each other.

A chemical-liquid supply line21for supplying a chemical liquid into the cleaning tank10connects the cleaning tank10and the chemical-liquid storing container20with each other. The chemical-liquid supply line21is provided with a chemical-liquid supply opening and closing valve22that opens and closes the chemical-liquid supply line21. Thus, when the chemical-liquid supply opening and closing valve22is opened, a chemical liquid is supplied from the chemical-liquid storing container20into the cleaning tank10. In this embodiment, an end of the chemical-liquid supply line21on the side of the cleaning tank10is connected to the below-described deionized-water supply line63so as to be merged with the deionized-water supply line63.

The chemical-liquid storing container20is equipped with a circulation line30through which a stored chemical liquid circulates. The circulation line30has a first circulation line32and a second circulation line33. The first circulation line32extends between the chemical-liquid storing container20and an ejector31, which will be described below, for supplying a chemical liquid from the chemical-liquid storing container20into the ejector31. The second circulation line33extends between the ejector31and the chemical-liquid storing container20, for supplying a gas-liquid mixture (described below) generated by the ejector31to the chemical-liquid storing container20.

The circulation line30is provided with the ejector (mixture generating part)31that mixes a chemical liquid supplied from the chemical-liquid storing container20and an inert gas supplied from the inert-gas supply source40with each other so as to generate a gas-liquid mixture. Namely, due to a flow of the supplied inert gas that reduces a pressure inside the first circulation line32to a negative pressure, the ejector31sucks a chemical liquid from the first circulation line32, and mixes the misty chemical liquid and the inert gas with each other so as to generate a gas-liquid mixture. Then, the ejector31supplies the gas-liquid mixture into the chemical-liquid storing container20through the second circulation line33. In this embodiment, an end of the first circulation line32on the side of the chemical-liquid storing container20is connected to the chemical-liquid supply line21, so that the first circulation line32is diverged from the chemical-liquid supply line21.

Disposed on the chemical-liquid storing container20is an inlet pipe (inlet part)36that introduces the gas-liquid mixture supplied from the second circulation line33into the chemical liquid stored in the chemical-liquid storing container20. One end of the inlet pipe36is connected to the second circulation line33, and the other end thereof extends to a lower part of the chemical-liquid storing container20, so that the gas-liquid mixture can be introduced from the lower part of the stored chemical liquid into the chemical liquid. Thus, the inert gas of the gas-liquid mixture becomes bubbles and elevates in the chemical liquid (bubbles the chemical liquid) to reach a gaseous phase space formed in an upper part of the chemical-liquid storing container20. Meanwhile, the chemical liquid of the gas-liquid mixture is stored in the chemical-liquid storing container20. In this manner, the chemical liquid is circulated. Since the inlet pipe36extends to the lower part of the chemical-liquid storing container20, a liquid level of the chemical liquid is prevented from waving, whereby detection precision of the liquid level of the chemical liquid by means of the below-described level sensors60can be improved.

The first circulation line32(a part to which the chemical liquid is supplied from the chemical-liquid storing container20to the ejector31) is provided with a first circulation opening and closing valve34that opens and closes the first circulation line32. In addition, the second circulation line33(a part to which the gas-liquid mixture is supplied from the ejector31to the chemical-liquid storing container20) is provided with a second circulation opening and closing valve35that opens and closes the second circulation line33. When the chemical-liquid supply opening and closing valve22closed, the first circulation opening and closing valve34and the second circulation opening and closing valve35are opened to supply the chemical liquid from the chemical-liquid storing container20to the ejector31, so that the chemical liquid is circulated. On the other hand, when the chemical-liquid supply opening and closing valve22is opened, the first circulation opening and closing valve34and the second circulation opening and closing valve35are closed to stop the supply of the gas-liquid mixture from the ejector31to the chemical-liquid storing container20, so that the chemical liquid is supplied from the chemical-liquid storing container20into the cleaning tank10.

A first gas supply line41for supplying an inert gas to the ejector31extends between the inert-gas supply source40and the ejector31. In addition, provided between the inert-gas supply source40and the chemical-liquid storing container20is a second gas supply line42that does not supply an inert gas into the ejector31but supplies an inert gas into the chemical-liquid storing container20. An end of the second gas supply line42on the side of the inert-gas supply source40is connected to the first gas supply line41, so that the second gas supply line42is diverged from the first gas supply line41.

The first gas supply line41is provided with a first gas supply opening and closing valve43that opens and closes the first gas supply line41. When the chemical-liquid supply opening and closing valve22is closed, the first gas supply opening and closing valve43is opened to supply an inert gas into the ejector31. On the other hand, when the chemical-liquid supply opening and closing valve22is opened, the first gas supply opening and closing valve43is closed to stop the supply of the inert gas from the inert-gas supply source40into the ejector31.

The second gas supply line42is provided with a second gas supply opening and closing valve44that opens and closes the second gas supply line42. When the chemical-liquid supply opening and closing valve22is opened, the second gas supply opening and closing valve44is opened to directly supply an inert gas into the chemical-liquid storing container20. In this case, the inside of the chemical-liquid storing container20is pressurized so that the chemical liquid is supplied into the cleaning tank10. When the chemical-liquid supply opening and closing valve22is closed, the second gas supply opening and closing valve44is closed to stop the supply of the inert gas from the inert-gas supply source40to the chemical-liquid storing container20through the second gas supply line42.

The above-described first gas supply opening and closing valve43and the second gas supply opening and closing valve44constitute a gas supply destination switching part45that switches a supply destination of an inert gas from the inert-gas supply source40, whereby a destination of the supplied inert gas can be switched between the chemical-liquid storing container20and the ejector31.

Connected to an upper part of the chemical-liquid storing container20is a gas discharge line50for discharging a gas from the inside thereof. The gas discharge line50is provided with a gas discharge opening and closing valve51that opens and closes the gas discharge line50. When the chemical-liquid supply opening and closing valve22is closed, the gas discharge opening and closing valve51is opened to discharge a gas containing oxygen, which has been removed from the chemical liquid, together with the inert gas, from the upper part of the chemical-liquid storing container20. When the chemical-liquid supply opening and closing valve22is opened, the gas discharge opening and closing valve51is closed.

The chemical-liquid storing container20is equipped with the plurality of level sensors60for detecting a liquid level of the chemical liquid stored therein. A control unit70, which will described below, is connected to the respective level sensors60. In addition, a chemical-liquid supply source61for supplying a chemical liquid into the chemical-liquid storing container20is connected to the chemical-liquid storing container20. Based on detection signals from the level sensors60, the control unit70is configured to control the chemical-liquid supply source61, such that a chemical liquid is supplied (replenished) from the chemical-liquid supply source61to the chemical-liquid storing container20.

A deionized-water supply line63extends between the cleaning tank10and the deionized-water supply source62. The deionized-water supply line63is provided with a deionized-water supply opening and closing valve64that opens and closes the deionized-water supply line63. When the deionized-water supply opening and closing valve64is opened, a deionized water is supplied from the deionized-water supply source62into the cleaning tank10.

The aforementioned respective opening and closing valves22,34,35,43,44,51and64are connected to the control unit70. When the control unit70circulates the chemical liquid, the control unit70controls the respective opening and closing valves22,34,35,43,44,51and64, such that the chemical-liquid supply opening and closing valve22and the second gas supply opening and closing valve44are closed, and that the first circulation opening and closing valve34, the second circulation opening and closing valve35, the first gas supply opening and closing valve43and the gas discharge opening and closing valve51are opened.

When a cleaning process by means of a chemical liquid is performed in the cleaning tank10, the control unit70controls the respective opening and closing valves22,34,35,43,44,51and64, such that the chemical-liquid supply opening and closing valve22and the second gas supply opening and closing valve44are opened, and that the first circulation opening and closing valve34, the second circulation opening and closing valve35, the first gas supply opening and closing valve43and the gas discharge opening and closing valve51are closed. In addition, at this time, the control unit70opens the deionized-water supply opening and closing valve64. In this manner, a chemical liquid and a deionized water can be supplied into the cleaning tank10. On the other hand, when a cleaning process (rinse process) by means of a deionized water is performed in the cleaning tank10, the control unit70controls the chemical-liquid opening and closing valve22and the deionized-water supply opening and closing valve64, such that the opening and closing valve22is closed and that the opening and closing valve64is opened. In this manner, a deionized water can be supplied into the cleaning tank10.

In this embodiment, the control unit70includes a computer. The computer executes a program previously stored in a storage medium71, so that the cleaning process of wafer W with the use of the substrate processing apparatus1is performed.

Next, an operation of this embodiment as structured above, i.e., a substrate processing method in this embodiment will be described.

As shown inFIG. 2, a chemical liquid is supplied from the chemical-liquid supply source61into the chemical-liquid storing container20, so that the chemical liquid is stored in the chemical-liquid storing container20(step S1).

Then, as shown by the solid arrows inFIG. 1, the chemical liquid is circulated so as to bubble the stored chemical liquid (step S2).

In this case, the control unit70closes the chemical-liquid supply opening and closing valve22and the second gas supply opening and closing valve44, and opens the first circulation opening and closing valve34, the second circulation opening and closing valve35, the first gas supply opening and closing valve43, and the gas discharge opening and closing valve51. Thus, the chemical liquid is supplied into the ejector31from the chemical-liquid storing container20through the first circulation line32. At the same time, an inert gas is supplied to the ejector31from the inert-gas supply source40through the first gas supply line41. Thus, the chemical liquid and the inert gas are mixed with each other in the ejector31so that a gas-liquid mixture is generated therein. That is to say, due to the flow of the supplied inert gas that reduces the pressure inside the first circulation line32to a negative pressure, the ejector31sucks a chemical liquid from the first circulation line32so as to generate a gas-liquid mixture. The thus generated gas-liquid mixture passes through second circulation line33so as to be supplied into the inlet pipe36provided on the chemical-liquid storing container20. Then, the gas-liquid mixture is introduced from the inlet pipe36to the lower part of the stored chemical liquid. Thus, the inert gas of the gas-liquid mixture having been introduced from the inlet pipe36becomes bubbles and elevates in the chemical liquid (bubbles the chemical liquid) to reach the gaseous phase space. Meanwhile, the chemical liquid of the gas-liquid mixture is stored in the chemical-liquid storing container20. In this manner, the chemical liquid is circulated.

The inert gas having become bubbles reaches the gaseous phase space, together with oxygen dissolved in the chemical liquid. The inert gas having reached the gaseous phase space, together with the oxygen, passes through the gas discharge line50so as to be discharged from the chemical-liquid storing container20.

Then, as shown by the dotted arrows inFIG. 1, the chemical liquid having less dissolved oxygen is supplied to the cleaning tank10, and wafers W are cleaned (step S3).

In this case, the control unit70opens the chemical-liquid supply opening and closing valve22and the second gas supply opening and closing valve44, and closes the first circulation opening and closing valve34, the second circulation opening and closing valve35, the first gas supply opening and closing valve43and the gas discharge opening and closing valve51. In this case, a pressurized inert gas is supplied from the inert-gas supply source40to the chemical-liquid storing container20through the second gas supply line42. Thus, the inside of the chemical-liquid storing container20is pressurized, so that the chemical liquid having less dissolved oxygen is supplied from the chemical-liquid storing container20into the cleaning tank10through the chemical-liquid supply line21. In addition, at this time, the deionized-water supply opening and closing valve64is opened by the control unit70. Thus, a pressurized deionized water is supplied from the deionized-water supply source62. The pressurized deionized water is merged and mixed with the chemical liquid in the course of the deionized-water supply line63, and is supplied into the cleaning tank10.

The chemical liquid having been supplied into the cleaning tank10is jetted toward the wafers W from the nozzle11. Thus, oxide films on the surfaces of the respective wafers W are etched, whereby the wafers W are cleaned with the chemical liquid.

Then, a deionized water is supplied into the cleaning tank10, and the wafers W are cleaned (rinsed) (step S4). In this case, the control unit70closes the chemical-liquid supply opening and closing valve22, and opens the deionized-water supply opening and closing valve64. Thus, a deionized water is supplied from the deionized-water supply source62into the cleaning tank10. The deionized water is jetted toward the wafers W, whereby the wafers W are cleaned with the deionized water.

Thereafter, the wafers W are transferred to the drying chamber12, and the shutter13is closed. Then, the wafers W are dried in the drying chamber12(step S5).

In the above-described step S3, since the chemical liquid is supplied from the chemical-liquid storing container20into the cleaning tank10, the amount of the chemical liquid stored in the chemical-liquid storing container20is reduced, so that the liquid level of the chemical liquid lowers. Thus, when the control unit70judges that the liquid level of the chemical liquid lowers up to a predetermined position based on detection signals from the level sensors60for detecting the liquid level of the chemical liquid, a chemical liquid is replenished to the chemical-liquid storing container20from the chemical-liquid supply source61. In this case, as in the above-described step S2, the chemical liquid is circulated so as to bubble the stored chemical liquid, whereby oxygen dissolved in the chemical liquid is reduced.

According to this embodiment, a chemical liquid supplied from the chemical-liquid storing container20through the first circulation line32, and an inert gas supplied from the inert-gas supply source40through the inert-gas supply line41, are mixed with each other by the ejector31, so that a gas-liquid mixture is generated therein. Thus, the generated gas-liquid mixture passes through the second circulation line33so as to be supplied into the inlet pipe36provided on the chemical-liquid storing container20. Then, the gas-liquid mixture is introduced from the inlet pipe36to the stored chemical liquid. The inert gas of the introduced gas-liquid mixture becomes bubbles in the stored chemical liquid. The inert gas together with oxygen dissolved therein elevates in the chemical liquid to reach the gaseous phase space in the upper part of the chemical-liquid storing container20. Thus, the oxygen dissolved in the stored chemical liquid can be reduced. Thereafter, the wafers W are cleaned with the chemical liquid having less dissolved oxygen, whereby an oxide film can be efficiently etched from the surface of each wafer W. As a result, a cleaning efficiency of the wafer W can be improved.

In addition, according to this embodiment, a chemical liquid can be circulated by returning the chemical liquid to the chemical-liquid storing container20sequentially through the first circulation line32, the ejector31, the second circulation line33, and the inlet pipe36. Thus, the stored chemical liquid can be stirred, whereby oxygen dissolved in the stored chemical liquid can be efficiently reduced. Such a circulation of the chemical liquid is performed by the ejector31that sucks the chemical liquid from the chemical-liquid storing container20due to a flow of an inert gas. Thus, as compared with a case in which the circulation line30is provided with a drive part such as a pump for circulating a chemical liquid, the space can be saved and costs can be decreased. Moreover, a lifetime of the apparatus can be elongated, resulting in improvement in reliability of the apparatus.

In addition, according to this embodiment, the inside of the chemical-liquid storing container20is pressurized by an inert gas supplied from the inert-gas supply source40so as to supply a chemical liquid into the cleaning tank10. Thus, as compared with a case in which a drive part such as a pump is provided for supplying a chemical liquid, the space can be saved and costs can be decreased. Moreover, a lifetime of the apparatus can be elongated, resulting in improvement in reliability of the apparatus.

Further, according to this embodiment, a chemical liquid stored in the chemical-liquid storing container20is circulated through the first circulation line32, the ejector31, the second circulation line33and the inlet pipe36, so as to reduce oxygen dissolved in the chemical liquid. After that, the respective opening and closing valve22,34,35,43,44and51are switched, and the chemical liquid is supplied into the cleaning tank10. Thus, the oxygen dissolved in the chemical liquid to be used in the cleaning process of wafers W can be reliably reduced. In addition, while the chemical liquid is being supplied into the cleaning tank10, the chemical liquid stored in the chemical-liquid storing container20is not circulated by the ejector31or the like. Thus, the amount of the chemical liquid to be supplied into the cleaning tank10can be stabilized. As a result, a cleaning efficiency of the wafer W can be improved.

Second Embodiment

Next, a second embodiment of the present invention will be described with reference toFIG. 3.FIG. 3is a view for explaining the second embodiment of a substrate processing apparatus, a substrate processing method, and a storage medium storing a computer program for performing the substrate processing method.

The second embodiment shown inFIG. 3differs mainly from the first embodiment shown inFIGS. 1 and 2, in that the chemical-liquid supply driving part is formed of a pump. Other structure of the second embodiment is substantially the same with that of the first embodiment. InFIG. 3, the same parts as those of the first embodiment shown inFIGS. 1 and 2are shown by the same reference numbers, and detailed description thereof is omitted.

As shown inFIG. 3, a chemical-liquid supply line21is provided, between a chemical-liquid supply opening and closing valve22and a chemical-liquid storing container20, with a chemical-liquid supply pump80for feeding a chemical liquid into a cleaning tank10. The chemical-liquid supply pump80constitutes a chemical-liquid supply driving part23. The chemical-liquid supply pump80is connected to a control unit70, and is configured to be driven based on a control signal from the control unit70.

When wafers W are cleaned with the use of a chemical liquid, the control unit70opens the chemical-liquid supply opening and closing valve22and a second gas supply opening and closing valve44, and closes a first circulation opening and closing valve34, a second circulation opening and closing valve35, a first gas supply opening and closing valve43, and a gas discharge opening and closing valve51. In addition, the chemical-liquid supply pump80is driven. Thus, a chemical liquid is supplied from the chemical-liquid storing container20into the cleaning tank10. In addition, at this time, a deionized-water supply opening and closing valve64is opened by the control unit70. Thus, a pressurized deionized water is supplied from a deionized-water supply source62, and the pressurized deionized water is merged and mixed with the chemical liquid in the course of a deionized supply line63so as to be supplied into the cleaning tank10. For this while, an inert gas is supplied to a gaseous phase space of the chemical-liquid storing container20from an inert-gas supply source40through a second gas supply line42, to thereby prevent oxygen from being dissolved into the stored chemical liquid.

According to this embodiment, it goes without saying that the same effects as those of the first embodiment shown inFIGS. 1 and 2can be obtained. In particular, in this embodiment, since the chemical-liquid supply pump80is used for supplying a chemical liquid from the chemical-liquid storing container20into the cleaning tank10, the chemical liquid can be more smoothly supplied into the cleaning tank10. This is advantageous when a chemical liquid having a high viscosity, which is used in a coating apparatus and a developing apparatus, for example, is supplied into the cleaning tank10.

In this embodiment, even while a chemical liquid is being supplied into the cleaning tank10, it is possible to bubble the chemical liquid stored in the chemical-liquid storing container20by operating the respective opening and closing valves34,35,43and51. Owing to this operation, a concentration of oxygen dissolved in the chemical liquid can be further reduced. In this case, in order to improve precision of a flow rate of the chemical liquid to be supplied into the cleaning tank10, a sensor such as a massflow controller may be provided on the chemical-liquid supply line21so as to control a flow rate of the chemical liquid.

In addition, in this embodiment, the supply of an inert gas from the inert-gas supply source40to the chemical-liquid storing container20through the second gas supply line42is not limited to the time period while a chemical liquid is being supplied into the cleaning tank10. For example, during a circulation of the chemical liquid, an inert gas may be supplied at a predetermined timing into the chemical-liquid storing container20through the second gas supply line42, so as to discharge oxygen present in the gaseous phase space in the upper part of the chemical-liquid storing container20by a gas discharge line50. In this case, a concentration of oxygen dissolved in the chemical liquid can be further reduced.

Although the embodiments of the present invention have been described as above, the present invention can be naturally modified in various ways without the scope of the present invention. Typical modification examples will be described below.

In the above embodiments, the end of the first circulation line32on the side of the chemical-liquid storing container20is connected to the chemical-liquid supply line21. However, not limited thereto, the first circulation line32may be directly connected to the chemical-liquid storing container20.

In addition, in the above embodiments, hydrogen fluoride (HF) is used as a chemical liquid for etching an oxide film on the surface of a wafer W. However, not limited thereto, the present invention can be applied when a chemical liquid is a resist liquid for forming a photoresist film on a wafer W, or a polymer removal liquid for removing polymer (resist residue) formed on a wafer W. Also in this case, oxygen dissolved in the resist liquid or the polymer liquid can be efficiently reduced. Simultaneously, as compared with a case in which the circulation line30is provided with a drive part such as a pump for circulating a chemical liquid, the space can be saved and costs can be decreased. Moreover, a lifetime of the apparatus can be elongated, resulting in improvement in reliability of the apparatus. Further, the present invention can be applied when a chemical liquid is a plating liquid for plating a wafer W. Also in this case, the same effects as described above can be obtained

In addition, in the above embodiments, the gas supply destination switching part45is formed of the first gas supply opening and closing valve43and the second gas supply opening and closing valve44. However, not limited thereto, the gas supply destination switching part45may be constituted by a three-way valve.

Further, in the above embodiments, there is described the cleaning apparatus that cleans a plurality of wafers W by immersing the same in a chemical liquid or a deionized water. However, not limited thereto, the present invention can be applied to a cleaning apparatus of a sheet-fed type (not shown), which cleans wafers one by one.

As described above, the substrate processing apparatus1includes the control unit70having a computer. The respective constituent elements of the substrate processing apparatus1are operated by the control unit70, such that the cleaning process of wafers W can be performed. The present invention claims a storage medium71storing a program executed by the computer of the control unit70, in order to perform the cleaning process of wafers W with the use of the substrate processing apparatus1. The storage medium71may be a memory such as a ROM or a RAM, or may be a disc-shaped storage medium such as a hard disc or a CD-ROM.