JP2006231130A - Wet processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wet processing apparatus inexpensively manufacturable, reducing environmental load, reducing electric damage of a treating object, and improving processing capacity. <P>SOLUTION: This wet processing apparatus 20 includes a nozzle 22 having a slit-like discharge port 38. The nozzle 22 is provided with a radical forming part 37 radically activating processing liquid. The radical forming part 37 comprises a first electrode 39 constituting a discharge port 38, a second electrode 40 provided as a counter electrode of the first electrode 39, and a sheet-like solid electrolyte 41 contacting the first and second electrodes 39, 40, disposed in a space 36 in the nozzle 22 to come into contact with the treated liquid discharged from the discharge port 38. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wet processing apparatus.

  Conventionally, an RCA cleaning method is used for cleaning a semiconductor silicon substrate, a liquid crystal glass substrate, and the like. In the RCA cleaning method, an acid such as sulfuric acid or hydrochloric acid or an alkali such as ammonia is added and dissolved in a high concentration aqueous solution of hydrogen peroxide as a base, and the substrate is immersed in a concentrated chemical solution heated to a high temperature. This is a method for removing and cleaning a substance to be removed such as particles, organic matter, metal, and oxide film adhering to the substrate.

  In this RCA cleaning method, after removal of the substance to be removed, waste water for rinsing water used to wash away the chemical solution adhering to the substrate is generated. This waste water contains acid, alkali, contaminants removed from the substrate surface, etc. contained in the chemical solution. In the cleaning apparatus, volatile components, acid gas, and the like are generated. These are often undesirable materials for the natural environment, and cannot be disposed as they are in the external environment, so facilities for treating them are required. Thus, in the RCA cleaning method, there is a problem in that the cost of wastewater treatment and the cost of maintenance and inspection of facilities for treating wastewater are required, and the running cost increases.

  Recently, as the size of the semiconductor wafer and the mother substrate of the liquid crystal panel has increased, the amount of waste liquid generated in the cleaning process has tended to increase. Yes. On the other hand, circuit design rules in semiconductors and liquid crystals are further miniaturized, and practical use has been made to the level of 0.1 μm or less for semiconductors and to the submicron level for liquid crystals. In order to improve the manufacturing yield of semiconductors and liquid crystals whose circuit design rules are miniaturized, it is necessary to further improve the cleaning power in the cleaning process.

  As means for solving such problems and achieving both low environmental load and high detergency, there is a method using radical species derived from oxygen atoms and hydrogen atoms constituting water molecules. In this method, radical species are generated in the cleaning water, and cleaning water containing the radical species is discharged onto the surface of the object to be processed, thereby cleaning the object to be processed. Examples of radical species derived from an oxygen atom and a hydrogen atom include a hydrogen radical (atomic hydrogen), an oxygen radical (atomic oxygen), a hydroxyl radical, and a superoxide radical. These radical species are highly reactive, react instantly with the reactive species, and change to water, hydrogen gas, oxygen gas, etc., so there is almost no burden on the environment and the reactivity is very high. Since it is high, it has sufficient detergency even at a concentration of several tens of ppm. Since radical species are mainly obtained by electrolyzing water, it is not necessary to use a chemical solution, and waste water and harmful gases that require special treatment are not generated, so that facilities for treating these are not required. Therefore, methods using radical species generally have the advantage of being clean and low in cost.

  Various conventional techniques related to cleaning using radical species derived from oxygen atoms and hydrogen atoms have been proposed (see, for example, Patent Document 1). FIG. 4 is a cross-sectional view schematically showing a configuration of the substrate cleaning apparatus 1 which is one of the prior arts.

The substrate cleaning apparatus 1 of the prior art includes a cleaning tank 2 that can store a cleaning liquid in its internal space, and the internal space of the cleaning tank 2 is composed of two H ⁺ ion exchange membranes 3a and 3b. ^The two anode chambers 5a and 5b formed by the central cathode chamber 4 located between the ⁺ ion exchange membranes 3a and 3b, the two H ⁺ ion exchange membranes 3a and 3b, and the inner wall of the cleaning tank 2 It is divided into three rooms. Inner electrodes 6a and 6b made of a porous plate are fixed to the surface of each H ⁺ ion exchange membrane 3a and 3b on the cathode chamber 4 side, and an outer electrode 7a made of a porous plate is attached to the surface on the anode chambers 5a and 5b side. 7b are fixed. An ultrasonic oscillator 8 is provided at the bottom of the cleaning tank 2 facing the cathode chamber 4.

The substrate cleaning apparatus 1 performs electrolysis of water by introducing pure water into the cleaning tank 2, applying a negative voltage to the inner electrodes 6a and 6b, and applying a positive voltage to the outer electrodes 7a and 7b. After the cathode chamber 4 is made OH ^- rich, radicals are activated by the action of ultrasonic waves oscillated from the ultrasonic oscillator 8 to clean the object 9 to be cleaned placed in the cathode chamber 4. Is to do.

  A substrate cleaning apparatus having a configuration in which the arrangement of the cathode chamber and the anode chamber is reversed has also been proposed (see Patent Document 2). In the cleaning method using the substrate cleaning apparatus of Patent Document 1 and Patent Document 2, since the object to be cleaned 9 is immersed in the cleaning tank 2 for cleaning, a large amount of cleaning water is required, and there is a concern about the reattachment of dirt. The Further, in order to clean the object to be cleaned, it is necessary to repeat the operation of immersing in the cleaning tank 2 and pulling it up after the cleaning is completed, so that continuous processing is difficult and it is difficult to shorten the processing time.

  In order to solve such a problem, a method has been proposed in which cleaning is performed by spraying a cleaning liquid without using a cleaning tank (see, for example, Patent Document 3). FIG. 5 is a cross-sectional view schematically showing a configuration of a substrate cleaning apparatus 10 as another conventional technique. The substrate cleaning apparatus 10 is similar to the above-described substrate cleaning apparatus 1, and corresponding portions are denoted by the same reference numerals and description thereof is omitted.

The substrate cleaning apparatus 10 includes a nozzle 11 that discharges a cleaning liquid, and the internal space of the nozzle 11 is positioned between the two H ⁺ ion exchange membranes 3a and 3b by the two H ⁺ ion exchange membranes 3a and 3b. The inner processing chamber 12 is divided into two outer processing chambers 13 a and 13 b formed by the two H ⁺ ion exchange membranes 3 a and 3 b and the inner wall of the nozzle 11. Inner electrodes 6a and 6b and outer electrodes 7a and 7b made of a porous plate are fixed to the respective H ⁺ ion exchange membranes 3a and 3b, and the nozzle ports 11a of the nozzles 11 are located above the inner processing chamber 12. An ultrasonic oscillator 14 is provided at the part facing the surface.

The substrate cleaning apparatus 10 introduces pure water into the inner processing chamber 12 and the outer processing chamber 13, applies a negative (or positive) voltage to the inner electrodes 6a and 6b, and applies a positive (or negative) voltage to the outer electrodes 7a and 7b. ) Is applied to make the inner treatment chamber 12 rich in OH ⁻ (or H ⁺ ), and then the ultrasonic wave oscillated from the ultrasonic oscillator 14 is applied to act as radicals. The substrate to be cleaned is processed by being activated and discharging the radical-containing cleaning liquid 15 from the nozzle port 11a.

In the method using the substrate cleaning apparatus 10 of Patent Document 3, the ultrasonic oscillator 14 is indispensable for radical activation of the cleaning liquid. Even if there is no action of ultrasonic waves, a small amount of radical species are generated together with ions during electrolysis of water, but the radical species are generated at the contact surfaces of the H ⁺ ion exchange membranes 3a and 3b and the electrodes 6 and 7. Therefore, the generated radical species are difficult to be carried on the water stream, and the site where the radical species are generated is separated from the nozzle port 11a from which the cleaning liquid containing the radical species is discharged. There is a problem that the seed disappears before reaching the nozzle opening 11a and a sufficient cleaning effect cannot be obtained.

Japanese Patent No. 2832171 Japanese Patent No. 2832173 Japanese Patent No. 3286539

  An object of the present invention is to provide a wet processing apparatus that can be manufactured at a low cost, reduces the environmental load, reduces electrical damage to an object to be processed, and realizes an improvement in processing capacity.

The present invention relates to a wet processing apparatus for processing a processing object by a processing liquid discharged from a nozzle having a discharge port that is arranged facing the processing object and is formed in a slit shape.
The nozzle is provided with a radical generator for radically activating the treatment liquid,
The radical generator is
A first electrode constituting a discharge port formed in a slit shape;
A second electrode provided as a counter electrode of the first electrode;
A wet processing apparatus comprising: a sheet-like solid electrolyte that is in contact with the first and second electrodes and is provided in contact with a processing liquid that is in a space in the nozzle and is to be discharged from the discharge port .

  In the present invention, the surface of the first electrode facing the processing liquid in the space in the nozzle is formed in a curved shape.

  Further, the present invention is characterized in that the first electrode has a plate-like shape whose thickness changes continuously, and is arranged so that the thickness becomes thinner as it approaches the discharge port.

  In the present invention, the solid electrolyte is a cation exchange material having an acidic cation exchange ability or an anion exchange material having a basic anion exchange ability.

  In the invention, it is preferable that one or both of the first and second electrodes include one or more selected from the group consisting of gold, platinum, carbon, titanium, palladium, and nickel. And

  In the invention, it is preferable that the treatment liquid is pure water having a specific resistance value of 1 MΩ · cm or more.

  According to the wet processing apparatus of the present invention, the nozzle having the slit-shaped discharge port is provided with the radical generation unit that radically activates the processing liquid, and the radical generation unit includes the first electrode that forms the slit-shaped discharge port. A second electrode serving as a counter electrode thereof, and a sheet-like solid electrolyte provided in contact with the first and second electrodes and in contact with the processing liquid to be discharged from the discharge port in the space in the nozzle. Therefore, more radical species can be contained in the treatment liquid, and more radical species can be contained immediately before discharge, so that more radical species can be supplied to the object to be processed. . Therefore, the processing capacity and processing speed are high, and for example, particles to be removed such as particles derived from fine particles adhering to the surface to be processed, organic substances such as resist residues can be easily removed, and the electrical characteristics of the object to be processed are not limited. Therefore, a wet processing apparatus capable of processing an object to be processed without electrically destroying the object to be processed is realized regardless of whether the object to be processed is a conductor, a semiconductor, an insulator, or the like.

  According to the present invention, since the surface of the first electrode facing the processing liquid in the space in the nozzle is formed in a curved surface shape, the electric field strength in the radical generator can be further increased. As a result, more radical species can be generated, so that more radical species can be contained in the treatment liquid.

  Further, according to the present invention, the first electrode has a plate shape whose thickness changes continuously, and is arranged so that the thickness becomes thinner as it approaches the discharge port. The processing liquid can be quickly supplied to the surface to be processed of the object to be processed. This can reduce the amount of radical species that have high reactivity but short life before they reach the surface to be treated, so that the treatment liquid containing a high concentration of radical species can be treated. Can be supplied to the surface.

  According to the present invention, the solid electrolyte is a cation exchange material having an acidic cation exchange ability or an anion exchange material having a basic anion exchange ability. Since the amount of active species generated can be further increased, it is possible to further improve the processing capacity.

  According to the invention, either or both of the first and second electrodes comprise one or more selected from gold, platinum, carbon, titanium, palladium, and nickel. The electrolysis efficiency can be further improved, the amount of radical species generated can be further increased, and the processing capacity can be further improved.

  Further, according to the present invention, pure water having a specific resistance value of 1 MΩ · cm or more is used as the treatment liquid, so that it is not necessary to use a special chemical liquid. Therefore, it is possible to reduce the cost for the chemical solution, and to reduce the environmental load without requiring equipment for processing the generated waste liquid, waste gas, and the like.

  FIG. 1 is a perspective view showing a simplified configuration of a wet processing apparatus 20 according to an embodiment of the present invention, and FIG. 2 is perpendicular to the long side direction of a nozzle 22 provided in the wet processing apparatus 20 shown in FIG. It is sectional drawing. The wet processing apparatus 20 is used to wet-process the processing object 21 with the processing liquid 23 that is disposed to face the processing object 21 and that is discharged from a nozzle 22 having a discharge port 38 that is formed in a slit shape.

  Here, the wet treatment is to remove, dissolve, and remove a substance to be removed present on the object to be processed by discharging a treatment liquid to the surface (surface to be processed) of the object to be installed facing the surface. It is peeling or decomposing, or dissolving, peeling or decomposing the workpiece itself, and subjecting the workpiece to treatment such as washing, grinding, processing, and surface modification. In this embodiment, as the wet process, for example, a cleaning process for removing organic substances and / or inorganic substances from an object to be processed is illustrated. However, the cleaning process is merely an example of the wet process, and the wet process in which the present invention is used. Is not limited to cleaning.

  The wet processing apparatus 20 generally includes the nozzle 22, a processing liquid supply unit 24 that supplies the processing liquid to the nozzle 22, and a power supply unit 25 that supplies power to the radical generation unit 37 of the nozzle 22. . In FIG. 1, the wet processing apparatus 20 and the workpiece 21 are installed so as to face each other in the vertical direction. Not. In particular, when the workpiece 21 is arranged so as to be parallel to the vertical direction, the treatment liquid 23 discharged from the nozzle 22 of the wet treatment apparatus 20 to the workpiece 21 does not stay on the surface of the workpiece 21. Since it flows down, the effect which prevents the removal target object once removed from adhering to the surface of the to-be-processed object 21 is anticipated.

  The to-be-processed object 21 may be comprised including a conductor and / or a nonconductor. That is, in the wet processing apparatus 20 of the present invention, it is possible to perform wet processing regardless of whether the workpiece 21 is a conductor or a nonconductor, and even if the workpiece 21 is a nonconductor, The treatment can be performed efficiently and stably in a short time without causing electrical breakdown during the treatment. Examples of the workpiece 21 that can be suitably processed by the wet processing apparatus 20 include a silicon wafer and a glass substrate.

  The substance to be removed to be removed from the workpiece 21 is generally an organic substance and an inorganic substance, and may be any substance that can be removed, dissolved, peeled off or decomposed by radical species present in the treatment liquid. It is not limited. Further, the substance to be removed may be in any form such as a liquid, a gel-like material, an adhesive material, and a solid material. Specific examples of the organic substance include, for example, resist residues and other organic contaminants. Specific examples of the inorganic substance include, for example, metal, metal oxide, fine particles (particles) containing other inorganic substances, and the like.

  The processing liquid supply means 24 includes a processing liquid storage tank 31, a pressurizing pump 32, a processing liquid supply pipe 33, and the like. The processing liquid supply pipe 33 includes a supply main pipe 33a provided with the pressurizing pump 32, a first branch pipe 33b in which the supply main pipe 33a is branched into four, and each of the first branch pipes 33b in two. And a second branch pipe 33 c connected to the nozzle 22. The processing liquid stored in the processing liquid storage tank 31 is pumped by the pressurizing pump 32, flows through the processing liquid supply pipe 33, and is supplied to the nozzle 22.

  In the present embodiment, the treatment liquid 23 is purified water obtained by sterilizing microorganisms by ultraviolet irradiation and removing organic substances and inorganic substances to the limit with a membrane filter, and has a specific resistance value of 1 MΩ · cm or more. Pure water is used. Here, purified water having a specific resistance value of 10 MΩ · cm or less is simply referred to as pure water, and pure water having a specific resistance value exceeding 10 MΩ · m and up to 18.3 MΩ · cm is ultrapure. Called water. In the precision cleaning field that requires a clean environment such as a liquid crystal panel and a semiconductor device manufacturing process by using pure water or ultrapure water having the above specific resistance value with high generation efficiency of radical species as the treatment liquid 23, Particularly effective.

  The nozzle 22 includes a nozzle body 35 and a radical generator 37 that is provided in the internal space 36 of the nozzle body 35 and radical-activates the treatment liquid (pure water or ultrapure water). The radical generator 37 is in contact with the first electrode 39 constituting the discharge port 38 formed in a slit shape, the second electrode 40 provided as a counter electrode of the first electrode 39, and the first and second electrodes 39, 40. And a sheet-like solid electrolyte 41 provided in the space 36 in the nozzle body 35 so as to be in contact with the processing liquid to be discharged from the discharge port 38, and an insulator 42.

  The nozzle body 35 is made of, for example, stainless steel (SUS316L defined in JIS G4305) as a base material and plated with platinum having a thickness of 2 μm. The cross-sectional shape has an E shape. That is, the nozzle body 35 has one surface of a rectangular parallelepiped shape opened, and the second branch pipe 33c of the processing liquid supply means 24 is connected to the surface 35a opposite to the surface to be opened, and the internal space of the surface 35a on the opposite side. A half partition plate 43 is formed extending in the longitudinal direction at substantially the center in the lateral direction on the 36th side. Therefore, the half partition plate 43 partitions the internal space 36 into two spaces that extend in the longitudinal direction and are substantially symmetrical.

  The radical generator 37 is provided so as to seal the opening of the nozzle body 35 except for the discharge port 38. Therefore, the nozzle main body 35 is closed except that the internal space 36 is connected to the outside by the slit-like discharge port 38 and the second branch pipe 33c of the processing liquid supply means 24.

  The radical generator 37 is disposed with the first electrode 39 facing outward, the solid electrolyte 41 is disposed on the first electrode 39 on the inner space side of the first electrode 39, and is more than the solid electrolyte 41. The second electrode 40 is disposed on the solid space 41 on the internal space side. The insulator 42 partially insulates the interface between the first electrode 39 and the solid electrolyte 41 near the nozzle body 35 and partially insulates the interface between the solid electrolyte 41 and the second electrode 40 near the nozzle body 35. Are arranged and provided.

  The first electrode 39 is a substantially plate-like member extending in an elongated shape, and is provided in a pair so as to face each other, and is attached to the nozzle main body 35 on one surface forming a long side. A slit-like discharge port 38 is formed between the free end portions of the mounted first electrode 39 facing each other. The interval between the slit-like discharge ports 38 is preferably about several tens to several hundreds of μm, and is set to 15 μm, for example. Further, the surface of the first electrode 39 facing the processing liquid 23 in the internal space 36 of the nozzle body 35 is formed in a curved surface shape, and the thickness of the first electrode 39 continuously changes in this curved surface. It is formed so that the thickness becomes thinner as it approaches the discharge port 38. Although the curved surface shape may be formed over the entire length of the first electrode 39 in the short direction, it approaches the discharge port 38 only in the vicinity of the free end portion because of the ease of installation of the second electrode 40 and the like. Accordingly, it is preferable that the thickness is reduced.

  The first electrode 39 is applied with a voltage from an external power supply 45 of the power supply means 25 described later, and the surface thereof is exposed to active species. Therefore, the first electrode 39 may be a conductive material having high durability against a chemical oxidation-reduction reaction. Preferably, for example, it comprises one or more selected from gold, platinum, carbon, titanium, palladium and nickel. Further, the entire electrode does not need to be made of the above-mentioned material, and for example, a stainless steel (SUS316L) as a base material and gold, platinum or the like plated on the surface thereof to a thickness of about 2 μm may be used.

  The second electrode 40 provided as a counter electrode of the first electrode 39 with the solid electrolyte 41 interposed therebetween is a plate-like member extending in an elongated shape, and the short-side dimension is shorter than the short-side dimension of the first electrode 39. Is done. A pair of second electrodes 40 are also provided opposite to each other, and are attached to the nozzle body 35 on one side forming a long side. The material for the second electrode 40 is the same as that for the first electrode 39.

  The solid electrolyte 41 is obtained by imparting ion exchange capability to a porous, network, fibrous, particulate, nonwoven fabric, or film sheet substrate. In particular, a film sheet having an ion exchange capacity is most preferable from the viewpoint of ease of handling during assembly of the nozzle, safety during use, and the like. By appropriately changing the type or amount of ion exchange groups in the solid electrolyte 41, the generation concentration of radical species can be controlled.

  As a material for imparting ion exchange capacity to the solid electrolyte 41, for example, it has a function of accelerating an ion exchange reaction in pure water and increasing an ion product of pure water, and is present in the same state before and after the ion exchange reaction. Any substance that can be used can be used without particular limitation. For example, an ion exchange resin is preferably used. The ion exchange resin is a water-insoluble synthetic resin having an acidic group or a basic group capable of ion exchange. Ion exchange resins are roughly classified into three types: cation exchange resins, anion exchange resins, and amphoteric exchange resins. Among these ion exchange resins, resins obtained by introducing an acidic cation group or a basic anion group having a large function of increasing the ion product of pure water are preferable, and sulfonic acid group-introduced resins, quaternary ammonium group-introduced resins and the like are preferable. Further preferred are ion exchange resins that increase the ion product Kw of the fluid in the range of 14 ≧ −log Kw.

  As a specific example of such a solid electrolyte 41, for example, a sheet made of a strongly acidic cation exchange resin in which a film having a thickness of 0.5 to 1.0 mm made of a fluororesin is used as a base material and a sulfonic acid group is introduced thereinto. Etc.

In the wet treatment apparatus 20, the solid electrolyte 41 acts to promote an ion exchange reaction in pure water as a treatment liquid and increase the ion product of pure water. When the solid electrolyte 41 is provided and, for example, a voltage of 50 V is applied in ultrapure water having a specific resistance value of 18.2 MΩ · cm, the concentration of hydroxyl ions and hydrogen ions increases, and a current of about 10 A / cm ² is obtained.

On the other hand, when a voltage of 50 V is applied in ultrapure water under the same conditions except that no solid electrolyte is provided, only a current value of about 10 ⁻² mA / cm ² is observed. That is, by providing the solid electrolyte 41, a current amount 10 ⁶ times that obtained when the solid electrolyte 41 is not provided can be obtained. This amount of current directly affects the amount of radical species generated in pure water. Therefore, when the solid electrolyte 41 is provided, the concentration of radical species is 10 ⁶ times that when electrolysis is performed without providing the solid electrolyte. Radical-containing water can be obtained, and high treatment performance can be obtained.

  The sheet-like solid electrolyte 41 is provided so as to be sandwiched between the first electrode 39 and the second electrode 40, and on the free end side of the first and second electrodes 39, 40, the first and second electrodes are provided. It is in contact with the electrodes 39, 40 and in the internal space 36 of the nozzle body 35 so as to be in contact with the processing liquid to be discharged from the discharge port 38.

  The first electrode 39 and the solid electrolyte 41 are insulated by the insulator 42 at a portion near the mounting portion to the nozzle body 35, and the second electrode 40 and the solid electrolyte 41 are near the mounting portion to the nozzle body 35. Insulating part 42 is insulated by insulator 42. The insulator 42 is a film-like member and is made of, for example, a polyimide resin.

  The power supply means 25 includes a first power supply terminal 43 connected to the first electrode 39, a second power supply terminal 44 connected to the second electrode 40, an external power supply 45, an external power supply 45, and first and second power supply. And a cable 46 for connecting the terminals 43 and 44. As the external power supply 45, for example, a DC voltage power supply is used.

  A voltage is applied from the external power supply 45 to the first electrode 39 and the second electrode 40 via the first and second power supply terminals 43 and 44 so that the anode and the cathode or the cathode and the anode are respectively connected. The A voltage is applied between the first electrode 39 and the second electrode 40, a solid electrolyte 41 is installed so as to touch the first and second electrodes 39, 40, and the solid electrolyte 41 is purified water in the nozzle body 35. Therefore, an electric current flows using ions derived from pure water as carriers. The amount of current that flows depends on the distance between the first electrode 39 and the second electrode 40 when the solid electrolyte 41 used is the same, and the shorter the distance, the more current flows. Therefore, the shorter the distance between the first electrode 39 and the second electrode 40, the better from the viewpoint of electrical characteristics.

  Due to the voltage applied to both electrodes 39 and 40, the ions that migrate inside solid electrolyte 41 and reach one electrode are exchanged with electrons, so that they are changed to other ions, radicals, gases, and the like. On the other hand, the other electrode on the opposite side continues to generate ions, radicals, gases, and the like derived from pure water serving as carriers by transferring electrons.

  As described above, since radicals are generated at the portions where the electrodes 39 and 40 and the solid electrolyte 41 are in contact with each other, the first electrode 39 faces the pure water in the space 36 in the nozzle body 35 as in this embodiment. The surface on the side is curved, that is, the side facing the pure water is convex so that a strong electric field can be generated by concentrating the lines of electric force near the curved surface. It becomes possible to do.

  Further, by disposing the first electrode 39, which has a continuously changing thickness and has the curved surface, so that the thickness becomes thinner as it approaches the discharge port 38, the pressure loss of the water flow is reduced. Since it can reduce, more radicals can be put on the flow of the pure water 23 with a stronger water flow. Although the radical lifetime is very short, the radical generator 37 in the wet processing apparatus 20 is arranged in the immediate vicinity of the discharge port 38 so that the first electrode 39 itself constituting the radical generation unit 37 forms the discharge port 38. Since it is installed, the amount of radical species that disappear before reaching the workpiece 21 is small, and the wet treatment can be performed with the treatment liquid 23 containing the radical species at a high concentration.

The amount of current that flows when a voltage is applied between the first electrode 39 and the second electrode 40 directly affects the amount of radical species generated. When the amount of pure water supplied to the nozzle 22 is Q (liters / minute) and the amount of current flowing between both electrodes is I (A), hydrogen radicals and hydroxyl radicals in radical-containing water generated in pure water The total concentration C (mol / liter) is expressed by the following formula (1).
C = 60I / 96500Q (1)

  For example, when the flow rate of pure water is 36 liters / minute and the current amount is 8 A, the radical concentration contained in the radical-containing water is 138 μmol / liter. When radical-containing water having this radical concentration is discharged at a flow rate of 100 m / second from, for example, a discharge port 38 having a length of 400 mm and a slit interval of 15 μm, the hydrogen radical concentration on the surface of the workpiece 21 is 4 μmol / second. Become a liter.

  Hereinafter, the cleaning processing operation of the workpiece 21 by the wet processing apparatus 20 will be described. The wet processing apparatus 20 generates radical species in a radical generation unit 37 provided in the nozzle 22 based on pure water which is a processing liquid supplied from the processing liquid supply unit 24, and contains a radical containing this radical species. Water 23 is supplied to the surface of the object to be processed 21 from the discharge port 38, and a cleaning process is performed by causing radical species to act on a substance to be removed that adheres, adheres to, or deposits on a part or the entire surface of the object 21. .

  When performing the cleaning process of the workpiece 21 using the wet processing apparatus 20, the nozzle 22 is disposed at a position where radicals can be supplied to the workpiece 21. Here, the position where radical supply is possible is a position where the radical-containing water 23 can be supplied from the nozzle 22 to the workpiece 21 with an amount and flow rate effective for carrying out the treatment.

  At the time of processing, the nozzle 22 may be arranged such that the direction in which the radical-containing water 23 is discharged with respect to the workpiece 21 has an inclination angle. Although the angle at which the nozzle 22 is inclined is not particularly limited, when the workpiece 21 is transported, the discharge port 38 of the nozzle 22 faces the surface of the workpiece 21 toward the upstream side in the transport direction of the workpiece 21. In the case where the workpiece 21 is fixed and the nozzle 22 moves, the discharge port 38 of the nozzle 22 faces the downstream side in the moving direction of the nozzle 22. It is preferable to incline so as to approach the object surface.

  This is because the treatment liquid supplied to the surface of the object to be treated 21 and used for cleaning the object to be treated 21 contains substances to be removed such as fine particles and organic residues, for example. When the treatment liquid containing the substance comes into contact with the portion of the object to be treated 21 after being cleaned, the substance to be removed may be reattached to the cleaned surface of the object to be treated 21. This is because it is possible to prevent the removal target substance from adhering again without the treatment liquid containing the removal target substance coming into contact with the cleaned surface of the object to be treated 21 by inclining the 22.

  Further, although the separation distance between the nozzle 22 and the workpiece 21 is not particularly limited, for example, when the discharge speed of the processing liquid 23 is set to 10 to 100 m / second, the pressure pump 32 that supplies the processing liquid to the nozzle 22. In consideration of utilities such as warpage of the workpiece 21, distortion, etc., it is preferably set to about 5 to 10 mm.

  In the cleaning processing operation of the wet processing apparatus 20 set as described above, pure water as a processing liquid is first supplied from the processing liquid supply unit 24 to the nozzle 22. Next, a voltage is applied from the external power supply 45 to the first and second electrodes 39 and 40 via the first and second power supply terminals 43 and 44. By this voltage application, radical species are generated in the pure water supplied to the internal space 36 of the nozzle body 35.

  FIG. 3 is a cross-sectional view showing a state in which hydroxyl radicals (.OH) 51 are generated in the first electrode 39. With reference to FIG. 3, the radical generation mechanism will be described in the case where the solid electrolyte 41 is a cation exchange resin. Here, although the case where the hydroxyl radical 51 is generated with the first electrode 39 as an anode is illustrated, the hydrogen radical (· H) is generated in the second electrode 40 by the same principle as in the first electrode 39 at this time. appear. Further, if the first electrode 39 is a cathode, radicals generated in the first electrode 39 and the second electrode 40 are reversed, and if the solid electrolyte 41 is an anion exchange resin, the ionic species moving in the solid electrolyte 41 can be reduced. Change.

As shown in FIG. 3, in the vicinity of the first electrode 39, the water molecule (H ₂ O) 52 is deprived of the electrons (e ⁻ ) 53 by the first electrode 39 and is electrolyzed, so that a hydroxyl radical (.OH) 51 is obtained. And hydrogen ions (H ⁺ ) 54. The hydrogen ions 54 are attracted toward the second electrode 40 in the solid electrolyte 41 by the action of an electric field. The pure water contains the remaining hydroxyl radicals 51 and becomes radical-containing water, which is discharged from the slit-shaped discharge port 38 and supplied to the surface of the workpiece 21.

  The chemical reaction formula shown below shows a state in which radical species generated by the mechanism shown in FIG. 3 and radical species derived from pure water derived from the reaction between the radical species and pure water are generated. Reaction formulas (2) to (4) show the generation of radical species.

  Specifically, the reaction formula (2) shows a state in which pure water is dissociated into hydrogen ions and hydroxyl ions. Reaction formula (3) shows the generation of hydroxyl radicals by electrolytic oxidation. Reaction formula (4) shows the generation of hydrogen radicals by electrolytic reduction. The reaction formulas (5) to (9) are obtained in a state where radical species derived from pure water derived from the reaction between radical species or radical species and pure water, that is, reaction between radicals or radicals and pure water. Indicates a state that disappears or changes.

  As active species derived from pure water, in addition to hydrogen radicals and hydroxyl radicals, oxygen radicals, superoxide anion radicals, HO₂Radical, HO₃There are radicals, ozone and hydrogen peroxide. In addition, other radical species can be generated by a gas such as oxygen, hydrogen, nitrogen, and carbon dioxide contained in water, and the radical species generating means of the present invention generates the radical species described herein. It is not limited to only.
      H₂O ⇔OH⁻+ H⁺                                  ... (2)
      OH⁻          ⇔ ・ OH + e⁻                                ... (3)
      H⁺+ E⁻  ⇔ ・ H                                       (4)
      ・ OH + ・ OH ⇔H₂O₂                                ... (5)
      H₂O + ・ OH ⇔OH + H₂O                                 ... (6)
      H₂O + ・ H ⇔H₂+ OH                                 ... (7)
      ・ H + ・ H     ⇔H₂                                        ... (8)
      ・ OH + ・ H   ⇔H₂O                                       ... (9)

  The treatment liquid 23 in which radical species are generated by the reaction as described above to become radical-containing water is discharged from the discharge port 38 toward the object 21 to be processed. At this time, for example, in the internal space 36 of the nozzle body 35, when the pressure applied to the treatment liquid 23 is about several MPa to 10 MPa and the interval between the discharge ports 38 is several tens of μm, the discharged radical-containing water is 10 A flow rate of about ~ 100 m / s is obtained.

  Since radical species generated from pure water are highly reactive, for example, silanol formed between the surface of fine particles as a removal target and the surface of a silicon substrate or glass substrate as a typical object 21 to be processed. By breaking the bond and inactivating dangling bonds, which are active sites for binding fine particles such as a silicon substrate, it is possible to reduce the adhesion between the fine particles and the substrate and improve the removal force of the fine particles. In addition, radical species are also effective for removing contamination due to resist residues, organic components derived from the manufacturing process, etc. In this case, the organic substance is a carbon-carbon, carbon-hydrogen covalent bond, etc. in the organic substance. When the strong bond is broken and oxidized, it is decomposed and removed into low molecular weight organic molecules or carbon dioxide and water.

  As described above, in the wet processing apparatus 20, the workpiece 21 is cleaned using the cleaning power of the radical species generated by the radical generator 37.

  As described above, according to the wet processing apparatus of the present invention, it is possible to reduce the environmental load, suppress electrical damage to the object to be processed, and realize a high processing capacity at a low equipment cost. .

It is a perspective view which simplifies and shows the structure of the wet processing apparatus 20 which is one Embodiment of this invention. It is sectional drawing perpendicular | vertical to the long side direction of the nozzle 22 with which the wet processing apparatus 20 shown in FIG. 1 is equipped. 6 is a cross-sectional view showing a state in which hydroxyl radicals (.OH) 51 are generated in the first electrode 39. FIG. It is sectional drawing which shows schematically the structure of the board | substrate cleaning apparatus 1 which is one of the prior arts. It is sectional drawing which shows schematically the structure of the board | substrate cleaning apparatus 10 which is another prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Wet processing apparatus 21 To-be-processed object 22 Nozzle 23 Processing liquid 24 Processing liquid supply means 25 Power supply means 35 Nozzle main body 36 Internal space 37 Radical generation part 38 Discharge port 39 1st electrode 40 2nd electrode 41 Solid electrolyte 42 Insulator

Claims (6)

In a wet processing apparatus for processing an object to be processed by a processing liquid discharged from a nozzle having a discharge port that is disposed opposite to the object to be processed and formed in a slit shape,
The nozzle is provided with a radical generator for radically activating the treatment liquid,
The radical generator is
A first electrode constituting a discharge port formed in a slit shape;
A second electrode provided as a counter electrode of the first electrode;
A wet processing apparatus comprising: a sheet-like solid electrolyte that is in contact with the first and second electrodes and is provided in contact with a processing liquid that is in a space in the nozzle and is to be discharged from the discharge port. The first electrode is
2. The wet processing apparatus according to claim 1, wherein the surface facing the processing liquid in the space in the nozzle is formed in a curved surface shape. The first electrode is
The wet processing apparatus according to claim 1, wherein the wet processing apparatus has a plate-like shape whose thickness changes continuously, and is arranged so that the thickness becomes thinner as it approaches the discharge port. Solid electrolyte is
The wet processing apparatus according to any one of claims 1 to 3, which is a cation exchange material having an acidic cation exchange ability or an anion exchange material having a basic anion exchange ability. One or both of the first and second electrodes are
The wet processing apparatus according to claim 1, comprising one or more selected from the group consisting of gold, platinum, carbon, titanium, palladium, and nickel. Treatment liquid is
The wet processing apparatus according to any one of claims 1 to 5, wherein the wet processing apparatus is pure water having a specific resistance value of 1 MΩ · cm or more.

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