JP2004186530A - Cleaning apparatus and cleaning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning apparatus for cleaning an object in a supercritical fluid, wherein an additive is uniformly diffused and easily dissolved into the supercritical fluid and the supercritical state is stably maintained. <P>SOLUTION: The wafer cleaning apparatus 10 comprises a pressure vessel 12 having a lower chamber 12a accommodating an additive and an upper chamber 12b accommodating a supercritical fluid and holding a wafer in the supercritical fluid, a heater 14 for heating the additive, a heater 16 for heating the supercritical fluid, a partition 18 for connecting or disconnecting the lower and upper chambers, a controller 20 for operating the partition 18, and a wafer stage 22. The partition 18 connects the lower and upper chambers to allow additive diffusion into the supercritical fluid or disconnects the two chambers so as not to allow the diffusion. The upper chamber 12b may be replenished with a pure supercritical fluid when the two chambers are disconnected. The pressure vessel 12 has at its top a light take-in window 30 for light to be projected on the supercritical fluid for improving additive dissociation and supercritical fluid cleaning effect, and has at its bottom a ultrasonic wave application unit 32 for ultrasonic wave application for accelerating additive diffusion. The wafer stage 22 has a heating means 34 for heating the wafer for dew condensation prevention. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a cleaning apparatus and a cleaning method for cleaning an object to be cleaned using a supercritical fluid as a cleaning liquid, and more particularly, when using a supercritical fluid as a cleaning liquid, an additive is uniformly dispersed in the supercritical fluid. TECHNICAL FIELD The present invention relates to a cleaning apparatus and a cleaning method which can be easily dispersed and dissolved in water and can stably maintain a supercritical state.
[0002]
[Prior art]
In a manufacturing process of a semiconductor device, an electrode, a wiring pattern, a contact hole, and the like having a desired planar shape are formed by performing pattern etching on an electrode layer, a wiring layer, an insulating film, and the like formed on a substrate. Is performed.
In pattern etching, for example, a resist film is formed on a wiring layer formed on a substrate, and then the resist film is patterned to form a resist mask having a resist pattern having the same shape as a desired wiring pattern. Next, the wiring layer is etched using the resist mask as an etching mask to form a wiring pattern.
After etching the wiring layer, the process proceeds to a mask removing step of removing the resist mask remaining on the wiring pattern.
[0003]
In the mask removing step, conventionally, a substrate on which a resist mask is mounted is immersed in the resist removing liquid for a predetermined time using a sulfuric acid peroxide solution, an amine-based resist / polymer removing agent, a fluorine-based resist / polymer removing agent, etc. as a resist removing liquid. To remove the resist mask.
[0004]
By the way, the wiring width of wiring patterns has become finer with the increase in scale and integration of semiconductor devices, and in recent LSIs (large-scale integrated circuits), the line width is now approaching 100 nm or less. Accordingly, the aspect ratio (height / width) of the wiring pattern is also increasing.
As a result, in the conventional method of removing the resist mask by immersing the substrate in a resist removing liquid, a large suction force is generated at a gas-liquid interface due to a large surface tension of the resist removing liquid, and the formed high aspect ratio is removed. The pattern may be damaged. That is, pattern collapse may occur.
[0005]
The damage to the fine structure such as the pattern collapse occurring in the resist mask removing process is performed by cleaning the micromachine having the hollow structure in the manufacturing process of the micromachine having the hollow structure having the gap between the movable portion and the substrate (MEMS). This also occurs when the porous low dielectric constant interlayer insulating film is cleaned in the process of forming the wiring structure by the damascene method, which is performed in the process of manufacturing the semiconductor device.
In other words, when cleaning an object to be cleaned having a fine structure, it is difficult to clean the object to be cleaned without damaging the fine structure by a conventional cleaning method using a cleaning liquid having a large surface tension.
[0006]
Therefore, a “supercritical fluid technology” that uses a supercritical fluid that does not generate surface tension as a resist removing liquid or a cleaning liquid has been developed. Until now, JP-A-01-200828, JP-A-01-286314, Various proposals have been made in JP-A-09-43857 and JP-A-08-181050.
[0007]
Supercritical fluid technology is a supercritical fluid that has an intermediate property between a liquid and a solid and does not generate surface tension when the material is heated or pressurized above the critical temperature and critical pressure of the material. This is a technique in which such a supercritical fluid is used for a treatment such as a cleaning treatment since it becomes a fluid.
In particular, CO ₂ becomes a supercritical fluid at 31 ° C. and 7.38 MPa, and is industrially easy to use. However, even if the object to be cleaned is washed using the supercritical fluid CO ₂ as a cleaning liquid, the ability to dissociate the resist or the resist residue from the object to be cleaned is poor, and therefore the resist or the resist residue is completely removed from the object to be cleaned. Difficult to remove.
Therefore, it is attempted to easily remove the resist mask from the object to be cleaned by adding a stripping chemical (hereinafter referred to as an additive) for removing the resist or the resist residue from the object to be cleaned or a dissociation solvent thereof. Attempts have been made to do so.
Here, the dissociation solvent is a dissolution aid of the additive, and is a solvent used when the solubility of the additive in the supercritical fluid CO ₂ is not good.
[0008]
In the following, U.S. Patent Publication, Pub No. A method of removing a photoresist film or a photoresist residue from a semiconductor substrate (hereinafter, referred to as a wafer) by applying a supercritical fluid technology will be specifically described based on US 2002/0048731 A1.
First, a wafer having a photoresist film or a photoresist residue attached on the wafer surface is placed in a pressure chamber of a cleaning apparatus. Then, by adjusting the pressure in the pressure chamber, introducing a supercritical fluid CO ₂ and additives to the pressure chamber. Until the photoresist film or the photoresist residue is removed from the wafer, the supercritical fluid containing the additive is dissolved so that the supercritical fluid CO ₂ is in contact with the photoresist film or the photoresist residue. maintaining the wafer in the fluid CO _2. After the photoresist film or photoresist residue is removed from the wafer, the pressure chamber is opened and the wafer is rinsed.
[0009]
According to the above-mentioned publication, it is evaluated that not only the photoresist film and the photoresist residue but also other particles and metal contaminants on the wafer can be similarly removed.
Further, when the additive is hardly soluble in the supercritical fluid CO _2, in addition to the additives, there may be added to dissociate the solvent in the supercritical fluid CO ₂ as connecting a solvent of additive and the supercritical fluid CO ₂ .
[0010]
[Non-patent document 1]
U.S. Patent Publication, Pub No. US2002 / 0048731 A1 (FIG. 1)
[0011]
[Problems to be solved by the invention]
However, the resist removal process with supercritical fluid CO ₂ as disclosed supra publications, has the following problems.
First, in order to improve the performance of removing supercritical fluid CO _{2 from} a photoresist film or an etching residue, it is desired to dissolve as much additive as possible in supercritical fluid CO _2. it is difficult problem to be dissolved in the fluid CO _2.
Second, when the additive and dissociating solvent and the supercritical fluid CO ₂ are mixed in the pressure chamber of the removing device, uniform dispersion or diffusion is difficult, and distribution unevenness is likely to occur.
Third, since the critical point at which a substance enters the supercritical state varies depending on the substance, for example, even if CO ₂ is in a supercritical state, another substance such as an additive or a dissociation solvent is added to the supercritical fluid CO ₂ . At the moment of addition, a phenomenon occurs in which the supercritical state of the supercritical fluid CO ₂ becomes unstable, and it is difficult to clean the object to be cleaned in a stable state and remove the photoresist film or the etching residue. It is.
[0012]
Therefore, an object of the present invention is to provide a cleaning agent that can easily disperse and dissolve additives uniformly in a supercritical fluid and cleanly maintain a supercritical state when cleaning an object to be cleaned with a supercritical fluid. It is to provide an apparatus and a cleaning method.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, a cleaning apparatus according to the present invention includes a lower chamber, and an upper chamber continuously provided above the lower chamber, wherein the lower chamber contains an additive or an additive and a dissociation solvent. A vertical pressure vessel containing a mixed liquid (hereinafter collectively referred to as an additive), containing a supercritical fluid in the upper chamber, and holding the object to be cleaned in the supercritical fluid;
Heating means provided along the lower chamber of the pressure vessel, for heating the additive,
Temperature regulating means provided along the upper chamber of the pressure vessel, heating the supercritical fluid to adjust the temperature of the supercritical fluid,
A partition plate that is provided between the lower chamber and the upper chamber of the pressure vessel, allows the lower chamber and the upper chamber to freely communicate with each other, and shuts off;
An operating device is provided for operating the partition plate from the outside of the pressure vessel to freely connect and disconnect the lower chamber and the upper chamber of the pressure vessel.
[0014]
The heating means provided in the lower chamber of the pressure vessel heats the additive to cause convection of the additive, thereby uniformly diffusing and dissolving the additive in the supercritical fluid. Temperature control means provided in the upper chamber of the pressure vessel heats the supercritical fluid and adjusts the temperature of the supercritical fluid.
The partition plate is provided between the lower chamber and the upper chamber of the pressure vessel, and allows the lower chamber and the upper chamber to freely communicate with each other and shut off by an operation from the outside of the pressure vessel by the operating device. The partition plate allows the additive to diffuse into the supercritical fluid by connecting the lower chamber and the upper chamber, and conversely stops the diffusion of the additive by shutting off the lower chamber and the upper chamber. The chamber can be replaced with pure supercritical fluid, and the object to be cleaned can be rinsed.
[0015]
In a preferred embodiment of the present invention, a light irradiation window for irradiating the supercritical fluid with light is provided with a pressure vessel in order to enhance the dissociation property of the additive to the dissociation target attached to the object to be cleaned and the cleaning effect of the supercritical fluid. In the upper room. In a further preferred embodiment, an ultrasonic wave application device is provided at the bottom of the pressure vessel to apply ultrasonic waves to the additive to facilitate diffusion into the supercritical fluid.
Further, a cleaning member heating means is provided on a holding member for holding the cleaning target. By heating the object to be cleaned, dew formation on the object to be cleaned due to a temperature difference between the object to be cleaned and the supercritical fluid can be prevented.
Furthermore, a temperature control device that controls the temperature of the supercritical fluid in the pressure vessel by adjusting the temperature control means, and an outlet pipe that allows the supercritical fluid to flow out of the pressure device, or allows the supercritical fluid to flow into the pressure device. The inflow pipe is provided with a pressure control device for controlling the pressure of the supercritical fluid in the pressure vessel.
[0016]
In the present invention, the additive is stored in the lower chamber of the pressure vessel in advance, the body to be cleaned is stored in the upper chamber, and then the additive is heated by a heating means and a supercritical fluid is introduced. The object to be cleaned is cleaned by controlling the pressure and temperature of the supercritical fluid while diffusing and dissolving the additive in the supercritical fluid. Next, the communication between the upper chamber and the lower chamber of the pressure vessel is interrupted by the partition plate, and the supercritical fluid is introduced into the upper chamber. The object to be cleaned can be rinse-cleaned while being replaced.
In the present invention, the additive can be uniformly diffused and dissolved in a supercritical fluid such as the supercritical fluid CO ₂ by heating the additive to cause convection of the additive.
Further, the additive is pressurized by a supercritical fluid flowing into the pressure vessel, or a substance that undergoes a phase transition to a supercritical fluid (supercritical fluid generating substance), for example, a flow of CO ₂ and a convective flow of the additive by heating. It can be dispersed with a uniform distribution in the supercritical fluid in the container.
Furthermore, since the additive is gradually dissolved in the supercritical fluid by convection and diffusion, the critical point fluctuates as soon as the additive is added, and the supercritical state becomes unstable, as in the past. And the supercritical fluid in the pressure vessel can be stably maintained in the supercritical state.
[0017]
In the cleaning method according to the present invention, an additive or a liquid mixture of an additive and a dissociation solvent (hereinafter, collectively referred to as an additive) is contained in a lower chamber of a pressure vessel, and an object to be cleaned is placed in an upper chamber of the pressure vessel. A preprocessing step to retain;
Then, while the lower chamber and the upper chamber of the pressure vessel are in communication with each other, the lower chamber and the upper chamber of the pressure vessel are maintained in communication with each other, and a partition plate for partitioning and shutting off is maintained. A cleaning step of introducing the fluid into the upper chamber, diffusing and dissolving the additive in the supercritical fluid, and washing the body to be cleaned by contacting the body to be cleaned with the supercritical fluid in which the additive is dissolved for a predetermined time,
Operate the partition plate to shut off the lower chamber and upper chamber of the pressure vessel, introduce the supercritical fluid into the upper chamber, and convert the supercritical fluid in the upper chamber, in which the additive is dissolved, with pure supercritical fluid. A rinsing cleaning step of rinsing and cleaning the body to be cleaned by replacement.
[0018]
In the cleaning step of the preferred embodiment of the method of the present invention, the supercritical fluid in contact with the object to be cleaned is irradiated with light. Thereby, the dissociation property of the additive to the dissociation target adhered to the object to be cleaned and the cleaning effect of the supercritical fluid can be enhanced. Further, in the washing step, ultrasonic waves are applied to the additive contained in the lower chamber of the pressure vessel. Thereby, the diffusion of the additive into the supercritical fluid can be promoted.
In the washing step, a specific substance that changes phase into a supercritical fluid flows into the upper chamber of the pressure vessel, and the pressure and the temperature are adjusted to change the specific substance to a supercritical fluid in the upper chamber of the pressure vessel. You may do it.
[0019]
In the method of the present invention, any substance that can undergo a phase transition to a supercritical fluid can be applied as a supercritical fluid without limitation, but carbon dioxide gas that can be converted to a supercritical fluid at a relatively low pressure at almost normal temperature is used as a supercritical fluid generating substance. It is suitable.
In the method of the present invention, at least one of HF, hydroxyamine, alkanolamine, alkylamine, and ammonium fluoride is used as an additive, and water, IPA, methanol, ethanol, isopropanol, ethylene Glycol, acetone, methyl ethyl ketone, dimethyl sulfoxide, and / or N-methylpyrrolidine are used.
In the method of the present invention, one type of additive may be used, or a plurality of types of additives may be mixed and used. Further, one kind of dissociation solvent may be used, or a mixture of plural kinds of dissociation solvents may be used.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described specifically and in detail with reference to the accompanying drawings by way of example embodiments.
Embodiment of cleaning apparatus This embodiment is an example of an embodiment of the cleaning apparatus according to the present invention, and FIG. 1 is a schematic cross-sectional view showing a configuration of the cleaning apparatus of the embodiment. .
The cleaning apparatus 10 of this embodiment is a cleaning apparatus for cleaning a wafer with a supercritical fluid, and is provided along a vertical pressure vessel 12 and a lower chamber 12a of the pressure vessel 12, as shown in FIG. Heating means 14, temperature control means 16 provided along upper chamber 12b of pressure vessel 12, and lower chamber 12a and upper chamber 12b provided between lower chamber 12a and upper chamber 12b of pressure vessel 12. And an operating device 20 for operating the partition plate 18 from the outside of the pressure vessel 12 to allow the lower chamber 12a and the upper chamber 12b to freely communicate and shut off, A wafer stage 22 is provided in the upper chamber 12b and holds the wafer W.
[0021]
The pressure vessel 12 is a pressure vessel that contains an additive or a mixture of an additive and a dissociation solvent (hereinafter, collectively referred to as an additive) in a lower chamber 12a and a supercritical fluid in an upper chamber 12b. An inflow pipe 24 through which the supercritical fluid flows into the pressure vessel 12 and an outflow pipe 26 through which the supercritical fluid flows out of the pressure vessel 12 are provided on the side wall of the upper chamber 12b.
Instead of the supercritical fluid, a substance (supercritical fluid generating substance) that undergoes a phase transition in the pressure vessel 12 to become a supercritical fluid is caused to flow into the pressure vessel, and the temperature is controlled by a temperature control device 36 and a pressure control device 38 described later. Alternatively, the temperature and pressure in the pressure vessel 12 may be adjusted to cause the supercritical fluid-producing substance to undergo a phase transition in the pressure vessel 12 to a supercritical fluid.
The heating means 14 heats the additive contained in the lower chamber 12a to generate convection of the additive, and the additive is uniformly diffused and dissolved in the supercritical fluid by the convection of the additive.
The temperature control means 16 heats the supercritical fluid contained in the upper chamber 12b to adjust the temperature of the supercritical fluid.
[0022]
The partition plate 18 is operated by the operating device 20 from the outside of the pressure vessel 12, and freely connects and disconnects the lower chamber 12a and the upper chamber 12b. The partition plate 18 diffuses the additive into the supercritical fluid by connecting the lower chamber 12a and the upper chamber 12b, and stops diffusion of the additive by shutting off the lower chamber 12a and the upper chamber 12b.
In this interrupted state, a supercritical fluid of pure water is caused to flow into the upper chamber 12b, thereby replacing the supercritical fluid in which the additive in the upper chamber 12b is dissolved with the pure supercritical fluid, and The object to be cleaned can be rinse-cleaned.
The operating device 20 includes a link mechanism (not shown) for moving the partition plate 18 up and down. When the partition mechanism 18 is raised by a link mechanism from a ring-shaped member 28 provided around the inside of the pressure vessel 12, the lower chamber 12a And the upper chamber 12b can be communicated. Conversely, when the partition plate 18 is lowered and brought into contact with the ring-shaped member 28, the lower chamber 12a and the upper chamber 12b are shut off, and the additive becomes supercritical fluid. It can be prevented from spreading.
[0023]
The top of the pressure vessel 12 is irradiated with light to the supercritical fluid to increase the dissociation of an additive that dissociates an object to be dissociated from the object to be dissociated, such as a resist residue, and to clean the supercritical fluid. A light irradiation window 30 is provided in order to increase the power. At the bottom of the pressure vessel 12, there is provided an ultrasonic wave applying device 32 for applying ultrasonic waves to the additive in order to promote the diffusion of the additive.
Further, the wafer stage 22 for holding the wafer is provided with a wafer heating means 34 for heating the wafer. By heating the wafer, the wafer heating means 34 can prevent the occurrence of dew condensation on the wafer due to the temperature difference between the wafer and the supercritical fluid.
The heating unit 14, the temperature control unit 16, and the wafer heating unit 34 are heating units each including a heating element such as a heating wire.
[0024]
The cleaning device 10 is provided with a temperature control device 36 that controls the temperature of the supercritical fluid in the pressure vessel 12 in conjunction with the temperature control unit 16.
Further, a pressure control valve is provided in the outflow pipe 26 that allows the supercritical fluid to flow out of the pressure vessel 12, and a pressure control device 38 that controls the pressure of the supercritical fluid in the pressure vessel 12 is provided.
[0025]
In the cleaning device 10, the additive is stored in the lower chamber 12a of the pressure vessel 12 in advance and heated by the heating means 14, and then the supercritical fluid such as the supercritical fluid CO ₂ is supplied to the upper chamber 12a of the pressure vessel 12. And the additive is mixed with the supercritical fluid by the convection of the additive, and the temperature and pressure of the supercritical fluid are controlled by the temperature control device 34 and the pressure control device 36.
Further, in the present cleaning apparatus 10, instead of introducing a supercritical fluid, a specific substance that becomes a supercritical fluid due to phase transition is introduced into the upper chamber 12b, and the pressure and temperature are adjusted, and the specific substance is introduced into the upper chamber 12b. May be caused to undergo phase transition to a supercritical fluid.
In the cleaning apparatus 10, by heating the additive, the additive is uniformly diffused by convection to the supercritical fluid such as supercritical fluid CO _2, dissolved. In addition, due to the flow of the supercritical fluid flowing into the pressure vessel 12 or the flow of the supercritical fluid generating substance, for example, CO ₂ , and the convection flow of the additive generated by heating the additive, the additive is added to the pressure vessel. And dispersed in the supercritical fluid within 12 with a uniform distribution.
Furthermore, since the additive is gradually diffused and dissolved in the supercritical fluid by convection, the critical point fluctuates at the moment the additive is added as in the conventional case, and the supercritical state of the supercritical fluid becomes unstable. The supercritical state in the pressure vessel 12 can be stably maintained without any problem.
[0026]
Embodiment of cleaning method This embodiment is directed to a cleaning method of cleaning a wafer having an etching residue using the above-described cleaning apparatus 10 and using a supercritical fluid CO ₂ as a supercritical fluid. 1 is an example of an embodiment to which the cleaning method according to the above is applied.
In the present embodiment, first, a mixed solution of an additive and a dissociation solvent is accommodated in the lower chamber 12a of the pressure vessel 12, and the wafer W is cleaned on the wafer stage 22 disposed in the upper chamber 12b of the pressure vessel 12. Place as a body.
In this embodiment, for example, HF is used as an additive, and water is used as a dissociation solvent.
[0027]
Next, the operating device 20 is operated to raise the partition plate 18, and while maintaining the partition plate 18 in a state where the lower chamber 12 a and the upper chamber 12 b of the pressure vessel 12 can communicate with each other, the additive and the dissociated solution are heated by the heating means 14. Heat the mixture.
Along with the heating of the mixture, the supercritical fluid CO ₂ is caused to flow into the upper chamber 12b of the pressure vessel 12, and the temperature of the upper chamber 12b of the pressure vessel 12 is maintained at a temperature of 31 ° C. or more, for example, 40 ° C., by the temperature control device 36. At the same time, the pressure in the upper chamber 12b of the pressure vessel 12 is maintained at a pressure of 7.38 MPa or more, for example, 10 MPa by the pressure control device 38.
Then, the wafer W is brought into contact with the supercritical fluid CO _{2 in} which the additive and the dissociation solvent are dissolved for a predetermined time to clean the wafer W.
During the cleaning of the wafer W, the supercritical fluid CO ₂ is irradiated with light through the light irradiation window 30 to enhance the dissociation performance of the additive and the cleaning ability of the supercritical fluid CO ₂ . Further, the wafer W is heated by the wafer heating means 34 so that dew condensation does not occur on the wafer W. Furthermore, dissociation solvent and additive to diffuse rapidly in the supercritical fluid CO _2, ultrasonic waves are applied to the dissociation solvent and additives to launch an ultrasonic application device 32.
[0028]
The wafer W is brought into contact with the supercritical fluid CO ₂ in the upper chamber 12b of the pressure vessel 12 in a state where the partition plate 18 is separated from the ring-shaped member 28 for a predetermined time, and after cleaning, the operating device 20 is operated to operate the partition plate 18. Is lowered to contact the ring-shaped member 28 to shut off the lower chamber 12 a and the upper chamber 12 b of the pressure vessel 12, and then to allow the supercritical fluid CO ₂ to flow into the upper chamber 12 b of the pressure vessel 12.
Thus, it replaced with a supercritical fluid CO ₂ pure supercritical fluid CO ₂ containing the additive was present in the upper chamber 12b of the pressure vessel 12 a dissociation solvent, rinse the wafers W by pure supercritical fluid CO ₂ can do.
Next, the wafer W is dried by vaporizing the supercritical fluid CO ₂ .
[0029]
In this embodiment, by heating the additive, the additive and the dissociation solvent can be uniformly diffused and dissolved in the supercritical fluid CO ₂ by convection. Further, the flow of the supercritical fluid CO ₂ flowing into the pressure vessel 12, the additive and by the convection flow produced by the heat of dissociation solvents, additives and supercritical fluid dissociation solvent pressure vessel 12 CO ₂ It can be dispersed and dissolved in a uniform distribution therein.
Further, since the additive and the dissociated solvent are gradually diffused and dissolved in the supercritical fluid CO ₂ by convection, the critical point fluctuates at the moment when the additive is added as in the conventional case, The supercritical state in the pressure vessel 12 can be stably maintained without the supercritical state of the critical fluid becoming unstable.
[0030]
In the present embodiment, the supercritical fluid CO ₂ is allowed to flow into the pressure vessel 12. However, instead of the supercritical fluid CO ₂ , CO ₂ gas is caused to flow, the pressure and the temperature are adjusted, and the pressure Phase transition to supercritical fluid CO ₂ may be performed.
[0031]
【The invention's effect】
According to the present invention, an additive in the lower chamber, a supercritical fluid is accommodated in the upper chamber, and a vertical pressure vessel holding the object to be cleaned in the supercritical fluid, and a heating means for heating the additive, A pressure vessel comprising: a temperature control means for controlling the temperature of the supercritical fluid; a partition plate for freely communicating and blocking the lower chamber and the upper chamber; and an operating device for operating the partition plate from outside the pressure vessel. The additive is stored in advance in the lower chamber of the supercritical fluid, heated by a heating means, and then the supercritical fluid is introduced, and the additive is diffused and dissolved in the supercritical fluid by the convection of the additive while the pressure of the supercritical fluid is increased. The temperature is controlled to clean the object to be cleaned. Then, a supercritical fluid is introduced into the upper chamber while the communication between the upper chamber and the lower chamber of the pressure vessel is blocked by the partition plate so that the additive is not diffused, and the object to be cleaned is purely supercritical fluid. Rinse and clean.
In the present invention, the additive can be uniformly diffused and dissolved in the supercritical fluid by heating the additive. As a result, the critical point fluctuates at the moment the additive is added as in the conventional case, and the supercritical state does not become unstable, and the supercritical fluid in the pressure vessel is stably maintained in the supercritical state. Can be.
The method of the present invention realizes a cleaning method capable of uniformly dispersing and dissolving an additive in a supercritical fluid and stably maintaining a supercritical state when cleaning an object to be cleaned with a supercritical fluid.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view illustrating a configuration of a cleaning apparatus according to an embodiment.
[Explanation of symbols]
Reference Signs List 10 cleaning apparatus of embodiment, 12 vertical pressure vessel, 14 heating means, 16 temperature control means, 18 partition plate, 20 operating device, 22 wafer stage, 24 ... Inflow pipe, 26... Outflow pipe, 28... Ring-shaped member, 30... Light irradiation window, 32... Pressure control device.

Claims (11)

A lower chamber, and an upper chamber continuously provided above the lower chamber, wherein the lower chamber accommodates an additive or a mixture of the additive and the dissociating solvent (hereinafter, collectively referred to as an additive), and A vertical pressure vessel containing a supercritical fluid in the chamber, and holding the object to be cleaned in the supercritical fluid,
Heating means provided along the lower chamber of the pressure vessel, for heating the additive,
Temperature regulating means provided along the upper chamber of the pressure vessel, heating the supercritical fluid to adjust the temperature of the supercritical fluid,
A partition plate that is provided between the lower chamber and the upper chamber of the pressure vessel, allows the lower chamber and the upper chamber to freely communicate with each other, and shuts off;
A cleaning device, comprising: an operating device for operating a partition plate from the outside of a pressure vessel to freely communicate and shut off a lower chamber and an upper chamber of the pressure vessel. A light irradiation window for irradiating the supercritical fluid with light should be provided in the upper chamber of the pressure vessel in order to enhance the dissociation property of the additive to the dissociation target adhered to the object to be cleaned and the cleaning effect of the supercritical fluid. The cleaning device according to claim 1, wherein The cleaning device according to claim 1, wherein an ultrasonic applying device is provided at a bottom of the pressure vessel. The cleaning device according to any one of claims 1 to 3, wherein a cleaning member heating unit is provided on a holding member that holds the cleaning target. A temperature control device that controls the temperature of the supercritical fluid in the pressure vessel by adjusting the temperature control means, and an outlet pipe that allows the supercritical fluid to flow out of the pressure device, or an inflow pipe that allows the supercritical fluid to flow into the pressure device. The cleaning apparatus according to any one of claims 1 to 4, further comprising a pressure control device that controls a pressure of the supercritical fluid in the pressure vessel. A pretreatment step of storing an additive or a mixture of an additive and a dissociation solvent (hereinafter, collectively referred to as an additive) in a lower chamber of the pressure vessel, and holding a body to be cleaned in an upper chamber of the pressure vessel;
Then, while the lower chamber and the upper chamber of the pressure vessel are in communication with each other, the lower chamber and the upper chamber of the pressure vessel are maintained in communication with each other, and a partition plate for partitioning and shutting off is maintained. A cleaning step of introducing the fluid into the upper chamber, diffusing and dissolving the additive in the supercritical fluid, and washing the body to be cleaned by contacting the body to be cleaned with the supercritical fluid in which the additive is dissolved for a predetermined time,
Operate the partition plate to shut off the lower chamber and upper chamber of the pressure vessel, introduce the supercritical fluid into the upper chamber, and convert the supercritical fluid in the upper chamber, in which the additive is dissolved, with pure supercritical fluid. A rinsing cleaning step of rinsing the object to be cleaned by replacement. In the cleaning step, light is applied to the supercritical fluid in contact with the object to be cleaned in order to enhance the dissociation property of the additive to the object to be dissociated attached to the object to be cleaned and the cleaning effect of the supercritical fluid. The cleaning method according to claim 6, wherein: The cleaning according to claim 6, wherein in the cleaning step, ultrasonic waves are applied to the additive contained in the lower chamber of the pressure vessel to promote diffusion of the additive into the supercritical fluid. Method. In the cleaning step, a specific substance capable of phase transition to the supercritical fluid flows into the upper chamber of the pressure vessel, and the pressure and temperature of the upper chamber of the pressure vessel are adjusted to change the specific substance in the upper chamber to the supercritical fluid. The cleaning method according to claim 6, wherein the cleaning is performed. The method of cleaning according to any one of the claims 6 9, characterized by using supercritical fluid CO ₂ as the supercritical fluid. As an additive, HF, hydroxyamine-based, alkanolamine-based, alkylamine-based, and at least one of ammonium fluoride,
The method according to claim 10, wherein at least one of water, isopropyl alcohol (IPA), methanol, ethanol, isopropanol, ethylene glycol, acetone, methyl ethyl ketone, dimethyl sulfoxide, and N-methylpyrrolidine is used as the dissociation solvent. Cleaning method.

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