JP2008136983A - Catalyst-aided chemical processing method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide catalyst-aided chemical processing method and apparatus which can process hard-to-process materials, especially, SiC, GaN, etc. whose importance as electronic device materials is increasing these days, with high processing efficiency and high precision even for a space wavelength range of not less than several tens μm. <P>SOLUTION: Such a principle is used in the catalyst-aided chemical processing method and apparatus that the object 10 to be processed is put in a processing liquid containing an oxidizing agent, a solid catalyst 11 for decomposing the oxidizing agent is brought into contact with or close proximity to the object to be processed to produce a compound by a chemical reaction of an active radical, which is produced on the solid catalyst and has strong oxidizing force, with an atom on the surface of the object to be processed and the produced compound is removed or eluted to process the object to be processed. The surface to be processed is processed by applying either one or a combination of two or more of a light irradiation means for irradiating the object to be processed with light during the processing, a voltage application means for applying a voltage between the object to be used and the solid catalyst during the processing and a temperature control means for controlling the temperatures of the solid catalyst, the object to be processed and/or the processing liquid during the processing. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a catalyst-assisted chemical processing method and a processing apparatus, and more specifically, a catalyst-assisted chemical processing method for processing a workpiece using active species generated by decomposing molecules in a processing solution with a catalyst, and The present invention relates to a processing apparatus.

  In general, mechanical processing has been used in various scenes since ancient times. For example, in mechanical polishing, a tool is pressed against a surface to be processed, thereby introducing material defects by mechanical action and stripping off atoms on the surface. Such a mechanical polishing method damages the crystal lattice and makes it very difficult to obtain a highly accurate surface. Therefore, in order to create a thing with high accuracy, it is necessary to use chemical processing that can be processed without generating lattice defects.

  Already, the suspension in which the ultrafine powder is dispersed is caused to flow along the work surface of the work piece, and the ultra fine powder is brought into contact with the work surface in a substantially unloaded state. We already know the processing by so-called EEM (Elastic Emission Machining), which removes and processes the workpiece surface atoms on the order of atomic units by the interaction (a kind of chemical bond) at the interface between the ultrafine powder and the workpiece surface. (Patent Documents 1 to 4). In addition, neutral radicals based on the reaction gas generated by the machining electrode to which a high voltage is applied are supplied to the work surface of the workpiece, and generated by a radical reaction between the neutral radicals and atoms or molecules on the work surface. The volatile material is removed by vaporization, and the processing electrode is processed while being changed relative to the surface to be processed, which is determined according to the type of reaction gas and the material of the workpiece. Plasma CVM (Chemical Vaporization Machining) is also proposed to perform machining by numerically controlling the machining time according to the coordinate difference based on the correlation data between the machining time and machining amount and the coordinate data of the previous machining surface and the target machining surface. (Patent Document 5). In addition, a high-efficiency machining method using a high-density radical reaction using a rotating electrode that forms a gas flow across the machining gap by rotating the rotating electrode at high speed to entrain gas on the surface of the rotating electrode is also proposed. (Patent Document 6).

  The aforementioned EEM and plasma CVM are excellent as a kind of chemical processing. EEM can obtain a smooth surface on an atomic scale, and although plasma CVM is slightly inferior in accuracy to EEM, highly efficient processing comparable to mechanical processing is possible with high accuracy.

The EEM can obtain a very smooth surface with respect to a high-frequency spatial wavelength in view of its processing principle. The EEM is characterized in that fine particles such as SiO ₂ are supplied to the surface with ultrapure water, and the processing proceeds by the atoms on the surface of the fine particles and the atoms on the surface of the workpiece being chemically bonded. At this time, the surface of the fine particles is a very flat surface, which is considered to be a reference surface and transferred to the surface. Therefore, it is possible to create a flat surface with an atomic size order without disturbing the atomic arrangement. However, EEM is difficult to flatten the spatial wavelength region of several tens of μm or more because of its processing principle.

  Plasma CVM is an extremely efficient processing method because it uses active radicals. The plasma CVM processing uses a chemical reaction between neutral radicals in the plasma and the workpiece surface. Processing is performed by generating high-density plasma in a high-pressure atmosphere of 1 atm, causing neutral radicals generated in the plasma to act on atoms on the surface of the workpiece, and changing them into volatile substances. Therefore, it has a machining efficiency comparable to conventional machining without disturbing the atomic arrangement of the work surface. However, since the processing method does not have a reference surface, it is easily affected by the index surface.

On the other hand, chemical mechanical polishing (CMP) uses SiO ₂ or Cr ₂ O ₃ as abrasive grains to reduce the mechanical action and to form a non-disturbed surface by the chemical action. For example, as shown in Patent Document 7, a method is disclosed in which a diamond thin film is immersed in an oxidizing polishing liquid in which abrasive grains having an oxidation catalytic action are dispersed, and the diamond thin film is polished while rubbing the thin film surface with abrasive grains. ing. Here, it is disclosed that chromium oxide or iron oxide is used as abrasive grains, and a polishing liquid in which the abrasive grains are dispersed in a hydrogen peroxide solution, a nitrate aqueous solution or a mixture thereof is disclosed.

Further, in Patent Document 8, the workpiece is arranged in a treatment solution in which molecules containing halogen that are not normally soluble in the workpiece are dissolved, and is made of platinum, gold, or a ceramic solid catalyst. The catalyst is placed in contact with or in close proximity to the work surface of the work piece, and the halogen compound produced by the chemical reaction between the halogen radicals produced on the surface of the catalyst and the surface atoms of the work piece is eluted. Catalyst-assisted chemical processing methods for processing workpieces have been proposed. Here, it is disclosed that the molecule containing halogen is hydrogen halide, specifically hydrogen fluoride or hydrogen chloride is used.
Japanese Patent Publication No. 2-25745 Japanese Patent Publication No. 7-16870 Japanese Patent Publication No. 6-44989 JP 2000-167770 A Japanese Patent No. 2962583 Japanese Patent No. 3069271 Japanese Patent No. 3734722 JP 2006-114632 A

  Therefore, in view of the above-mentioned situation, the present invention intends to solve difficult-to-process products, particularly SiC and GaN, which have recently been increasing in importance as materials for electronic devices, with high processing efficiency and several tens of μm or more. The purpose is to propose a new processing method capable of processing with high accuracy over a spatial wavelength region. In other words, a catalyst-assisted chemical processing method and processing capable of processing a difficult-to-process material such as SiC or GaN by a chemical reaction without crystallographically introducing lattice defects and having high spatial controllability. Propose the device.

  In order to solve the above-mentioned problems, the present invention provides a workpiece in a processing solution containing an oxidant, and brings a solid catalyst that decomposes the oxidant into contact with or close to the workpiece surface of the workpiece. Catalyst-assisted chemical processing method for processing a workpiece by removing or eluting a compound generated by a chemical reaction between an active species having a strong oxidizing power generated on the catalyst and a surface atom of the workpiece In the processing, a light irradiating means for irradiating light to the work surface of the work piece, a voltage applying means for applying a voltage between the work face of the work piece and the solid catalyst, the temperature of the catalyst, Provided is a catalyst-assisted chemical processing method characterized by processing a surface to be processed by applying one or more of temperature control means for controlling the temperature of a workpiece and / or a processing solution, in combination. (Claim 1).

  Here, it is also preferable to control the decomposition rate of the oxidant by adding a stabilizer for stabilizing the oxidant to the treatment liquid (claim 2).

Specifically, the oxidizing agent is preferably H ₂ O ₂ or O ₃ (Claim 3), and the solid catalyst is a transition metal composed of Fe, Ni, Co, Cu, Cr, Ti, platinum It is preferably composed of one or a combination of two or more selected from precious metals such as gold, ceramic metal oxides, and solid basic catalysts. And the effect of this invention is remarkable when the said to-be-processed object is 1 type chosen from crystalline SiC, sintered SiC, GaN, sapphire, ruby, and diamond (Claim 5).

More preferably, the oxidizing agent is H ₂ O ₂ , the solid catalyst is Fe, the workpiece is SiC, GaN, or diamond, and processing is performed using the Fenton reaction.

Further, it is more effective that the oxidizing agent is H ₂ O ₂ and the stabilizer is sodium silicate (Claim 7).

  It is also preferable to disperse the solid catalyst as a fine powder in the treatment liquid of the oxidizing agent, and supply the fine powder of the solid catalyst to the processing surface of the workpiece along with the flow of the treatment liquid. Claim 8).

  The present invention comprises a flat rotating surface plate having a solid catalyst for decomposing an oxidant on the surface, and a holder having a rotating shaft eccentric to the rotating shaft of the surface plate, and the surface of the catalyst and the workpiece The processing liquid containing the oxidizing agent is supplied between the processing surfaces of the workpiece, and the workpiece held in the holder is rotated while being pressed against the surface plate with a predetermined pressing force. In the catalyst-assisted chemical processing apparatus for flattening the surface, during the processing, a light irradiation means for irradiating light to the processing surface of the workpiece, a voltage is applied between the processing surface of the workpiece and the solid catalyst. Applying one or more of temperature control means for controlling the voltage application means to be applied, the temperature of the catalyst, the workpiece, and / or the temperature of the treatment liquid, and machining the work surface. (Claim 9) A catalyst-assisted chemical processing apparatus characterized by the above is configured. .

  Alternatively, in the present invention, a solid catalyst for decomposing the oxidant is dispersed as a fine powder in a treatment liquid containing an oxidant, and the fine powder of the solid catalyst is processed along with the flow of the treatment liquid. The processing liquid and catalyst supply means to be supplied to the surface are essential, the light irradiation means for irradiating the work surface of the work piece with light, and the voltage application means for applying a voltage between the work face of the work piece and the solid catalyst The catalyst is characterized in that the surface to be processed is processed by applying one or a combination of two or more of temperature control means for controlling the temperature of the catalyst, the workpiece, and / or the temperature of the treatment liquid. An assisted chemical processing apparatus was constructed (claim 10).

  Here, since wide band gap materials such as SiC and GaN are chemically very stable, it is difficult to obtain a sufficient reaction rate even when hydroxyl radicals react. In particular, GaN has a very low energy in the valence band, so that hydroxyl radicals cannot extract electrons. Therefore, by irradiating light corresponding to the band gap of the workpiece during the reaction, it becomes possible to activate the workpiece surface and improve the processing speed. The wavelength of the irradiated light is preferably equal to or less than the wavelength corresponding to the band gap of the workpiece. For example, since the band gap of 4H-SiC is 3.26 eV, the wavelength of the irradiated light is 383 nm or less, and since the band gap of GaN is 3.42 eV, the wavelength of the irradiated light is 365 nm or less.

Moreover, since the reaction rate cannot be controlled only by the Fenton reaction on the transition metal surface, it is difficult to improve the processing rate. Here, since the Fenton reaction is a one-electron reduction reaction of H ₂ O ₂ molecules on the catalyst surface, the generation of hydroxyl radicals is promoted by applying a voltage between the catalyst surface plate and the workpiece. Is possible. It is desirable to apply a voltage so that the catalyst serves as a cathode because the reduction reaction is promoted.

  As is known from the Arrhenius equation, the higher the reaction temperature, the higher the chemical reaction. Since the processing method is based on a chemical reaction, the processing speed can be changed by controlling the temperature of the catalyst, the workpiece, and / or the temperature of the processing liquid.

  The light irradiation means, voltage application means, and temperature control means described above can promote chemical reactions that contribute to processing even when used alone, but a plurality of them can also be applied in combination. In that case, there are a case where a plurality of means are applied simultaneously, and a case where they are shifted back and forth over time.

  The catalyst-assisted chemical processing method of the present invention as described above uses a solid catalyst that decomposes an oxidant on the processing reference surface, generates active species from the oxidant on the surface of the catalyst, and is in contact with or in close proximity to the catalyst. The workpiece is processed by removing or eluting the compound formed by the chemical reaction between the surface atoms of the workpiece and the active species. In the present invention, the oxide on the work surface generated by the chemical reaction between the surface atoms and the active species is removed by bringing the solid catalyst into contact with the work surface in the oxidizing agent without using abrasive grains or abrasives. As a result, a new surface to be processed always appears and processing proceeds. Here, since the active species generated on the catalyst surface are inactivated rapidly when they are separated from the catalyst surface, the active species are present only on the catalyst surface which is the reference surface or in the immediate vicinity of the surface, thereby It can be processed in a spatially controlled state.

In the present invention, during the processing, the light irradiation means for irradiating the work surface of the work piece with light, the voltage application means for applying a voltage between the work surface of the work piece and the solid catalyst, Since one or more of temperature control means for controlling the temperature, the workpiece, and / or the temperature of the processing liquid are applied in combination to process the surface to be processed, a chemical reaction that contributes to the processing is performed. Not only can the processing speed be improved, but wide band gap materials such as SiC and GaN, which have been very difficult to process, can be chemically processed at a practical level. In addition, high-precision processing of sapphire, ruby, and diamond can be performed, and there is a possibility that it can be used in a semiconductor manufacturing process. In particular, since H ₂ O ₂ or O ₃ which is easy to handle and inexpensive as an oxidizing agent can be used, the processing cost can be greatly reduced as compared with a method using HF.

  A flat rotating surface plate having a solid catalyst for decomposing an oxidant on the surface; and a holder having a rotating shaft eccentric to the rotating shaft of the surface plate, the surface of the catalyst and the workpiece to be processed The processing liquid containing the oxidizing agent is supplied between the surfaces, and the work piece held in the holder is rotated while pressing the work plate against the surface plate with a predetermined pressing force to flatten the work surface of the work piece. Since the catalyst-assisted chemical processing to be processed is a chemical processing having a processing reference surface, it is possible to highly planarize a spatial wavelength region of several tens of μm or more, which was difficult with EEM or plasma CVM.

  Next, the present invention will be described in more detail based on embodiments. The processing principle of the present invention is that a workpiece is placed in a processing solution containing an oxidant, and a solid catalyst that decomposes the oxidant is brought into contact with or in close proximity to the workpiece surface of the workpiece. The workpiece is processed by removing or eluting the compound generated by the chemical reaction between the generated active species having strong oxidizing power and the surface atoms of the workpiece. And during processing, light irradiation means for irradiating the work surface of the work piece with light, voltage application means for applying a voltage between the work surface of the work piece and the solid catalyst, the temperature of the catalyst, the work piece One or two or more types of temperature control means for controlling the temperature of the object and / or the treatment liquid are applied in combination to process the surface to be processed. Here, in the present invention, both the case where the workpiece and the solid catalyst are immersed in the treatment liquid and the case where the treatment liquid is fluidly supplied to the contact portion between the workpiece and the solid catalyst are included.

  First, the conceptual diagram of the processing method of this invention is shown in FIG. In the figure, reference numeral 1 denotes a solid catalyst, and 2 denotes a work surface of the work piece. As shown in FIG. 1A, when the catalyst 1 is brought into contact with or very close to the workpiece 2 in a treatment liquid containing an oxidizing agent, the active species 3 and surface atoms 4 generated on the surface of the catalyst 1 are formed. React to make compound 5. Here, reference numeral 6 in the figure denotes an oxidant molecule, and 7 denotes a residual molecule in which the active species 3 is generated by dissociation of the oxidant molecule 6. Then, as shown in FIG. 1 (b), when the catalyst 1 is separated from the workpiece 2, the compound 5 is removed from the workpiece surface of the workpiece 2, and the unreacted active species 3 bind to the remaining molecules 7. And inactivate. Therefore, the workpiece 2 is processed only while the catalyst 1 is in contact or in close proximity. And in this invention, it processes, applying a light irradiation means, a voltage application means, and a temperature control means individually or in combination in the above-mentioned process.

Here, H ₂ O ₂ or O ₃ is used as the oxidizer, and the solid catalyst is a transition metal composed of Fe, Ni, Co, Cu, Cr, Ti, a noble metal such as platinum or gold, or a ceramic metal. One or a combination of two or more selected from oxides and solid basic catalysts is used. The object to be processed is difficult to process such as crystalline SiC, sintered SiC, GaN, sapphire, ruby, diamond, and of course, Si can be processed. In particular, it is the most preferable embodiment that the oxidizing agent is H ₂ O ₂ , the solid catalyst is Fe, the workpiece is SiC, GaN, or diamond, and processing is performed using the Fenton reaction.

It is also possible to control the decomposition rate of the oxidant by adding a stabilizer for stabilizing the oxidant to the treatment liquid. In particular, when H ₂ O _{2 is} used as the oxidant and Pt is used as the catalyst, the reaction rate is too high and bubbles grow during the processing, causing trouble, so by adding sodium silicate as a stabilizer, The decomposition reaction of hydrogen peroxide can be suppressed and the growth of bubbles can be prevented. That is, the catalytic reaction can be slowed by adding a stabilizer to the treatment liquid.

  It is also possible to disperse the solid catalyst as a fine powder in the treatment liquid of the oxidizing agent, and supply the fine powder of the solid catalyst to the processing surface of the workpiece as the treatment liquid flows. is there.

The processing principle of the present invention will be described in more detail. First, generation of active species on the catalyst surface will be described. In the catalytic decomposition process of hydrogen peroxide water and ozone water, as shown below, hydroxyl radicals (represented as .OH in the reaction equation) and oxygen atoms (represented as .O in the reaction equation) that have a strong oxidizing power. Will be generated. These active species react with surrounding molecules as soon as they desorb from the catalyst, and change into inactive molecules. Therefore, the workpiece can be processed with reference to the catalyst surface by bringing the workpiece into contact with or in close proximity to the catalyst surface. Can be done.
(Hydrogen peroxide decomposition reaction)

Hydrogen peroxide is on the surface of a solid catalyst such as platinum, gold, or a solid basic catalyst.
H ₂ O ₂ → OH + OH
To generate hydroxyl radicals (see FIG. 2).

Moreover, when using a transition metal (Fe, Ni, Co, Cu, Cr, Ti) as a solid catalyst, it is estimated that a hydroxyl radical is generated according to the following reaction formula.
M + nH ₂ O ₂ → M ^{n +} + n · OH + nOH ⁻

  At this time, it is considered that the transition metal as the catalyst is ionized and dissolved in the solution. However, since the dissolved amount is very small, the surface of the catalyst hardly changes. Since this hydroxyl radical has a very strong oxidizing power and is active, it reacts with chemically stable materials such as SiC, GaN, diamond, and can be used for processing. In addition, hydroxyl radicals desorbed from the catalyst surface return to hydrogen peroxide molecules due to the reaction between hydroxyl radicals, and also lose activity by reacting with water molecules and dissolved oxygen in the solution. Decomposed into oxygen molecules. Since hydrogen peroxide molecules and oxygen molecules are inactive compared to hydroxyl radicals, they do not react with the above chemically stable materials.

(Decomposition reaction of ozone)
Ozone molecules are present on the surface of solid catalysts such as ceramic metal oxides and solid basic catalysts (ion exchange materials).
O ₃ → O ₂ + ・ O ・
Is decomposed into oxygen molecules and oxygen atoms (see FIG. 3). Since this oxygen atom has a very strong oxidizing power and is active, it reacts with chemically stable materials such as SiC, GaN, diamond, and can be used for processing.

Oxygen atoms desorbed from the catalyst surface react with oxygen molecules in the solution or react with each other to become ozone molecules or oxygen molecules.
・ O ・ + O ₂ → O ₃
・ O ・ + ・ O ・ → O ₂

  Since ozone molecules and oxygen molecules are inactive compared to oxygen atoms, they do not react with the above materials.

(Reaction between active species and workpiece)
Here, when the workpiece is SiC, it is presumed that the SiC surface is oxidized by the following reaction by hydroxyl radicals or oxygen atoms, and that part is preferentially processed.
SiC + 4.OH + O ₂ → SiO ₂ + 2H ₂ O + CO ₂ ↑
SiC + 4 · O · → SiO ₂ + CO ₂ ↑

In addition, when the workpiece is GaN, it is presumed that the GaN surface is oxidized by hydroxyl radicals or oxygen atoms by the following reactions, respectively, and that part is preferentially processed.
2GaN + 7.OH + 7 / 4O ₂ → Ga ₂ O ₃ + 7 / 2H ₂ O + 2NO ₂ ↑
2GaN + 7 · O · → Ga ₂ O ₃ + 2NO ₂ ↑

(Improve processing speed by light irradiation)
Since wide band gap materials such as SiC and GaN are chemically very stable, it is difficult to obtain a sufficient processing speed even when hydroxyl radicals or oxygen atoms act. Therefore, by irradiating light corresponding to the band gap of the workpiece during the reaction, the surface of the workpiece is activated and the processing speed is improved. As shown in FIG. 4A, the workpiece 10 is irradiated with excitation light through an excitation light transmission window 13 in which an excitation light source 12 is disposed behind the solid catalyst 11 and can transmit the excitation light. It is performed by irradiating from the back of the catalyst. The material of the excitation light transmission window 13 is preferably quartz (SiO ₂ ), sapphire (Al ₂ O ₃ ), or CaF ₂ . At this time, when a material that does not transmit excitation light is used as the solid catalyst 11, the plurality of through holes 14 are formed in the solid catalyst 11 to irradiate the processing surface of the workpiece 10 with excitation light. It is preferable to use light having a wavelength equal to or less than the wavelength corresponding to the band gap of the workpiece as the wavelength of the excitation light. For example, since the band gap of 4H-SiC is 3.26 eV, the wavelength of the irradiated light is 383 nm or less, and since the band gap of GaN is 3.42 eV, the wavelength of the irradiated light is 365 nm or less.

  Then, as shown in FIG. 4B, when the solid catalyst 11 is approached while irradiating the processing surface of the workpiece 10 with excitation light, the active region 15 on the processing surface of the workpiece 10 becomes It is processed by the active species 16 generated in the vicinity of the surface of the solid catalyst 11 (see FIG. 4C). Here, reference numeral 17 in the figure indicates excitation light. Then, as shown in FIG. 4D, when the solid catalyst 11 is moved away from the workpiece 10, the processing is stopped. As shown in the figure, the convex portion of the workpiece surface of the workpiece 10 is preferentially processed and flattened according to the flatness of the surface of the solid catalyst 11.

In general, in processing a wide gap material by a chemical reaction, it is necessary to extract electrons from the valence band (Ev) to generate holes (denoted as h ⁺ ). When the hydroxyl radical or oxygen atom acts on the SiC surface, the oxidizing power of the hydroxyl radical or oxygen atom is stronger than the valence charge position of SiC,
· OH → OH ^{- +} h +
^{· O · → · O - +} h +
As a result of the reaction, electrons are extracted from the valence band of SiC and holes are generated (process A in FIG. 5). SiC is processed by the action of water molecules and dissolved oxygen in the treatment liquid on the holes (process B in FIG. 4).

  Here, when the surface of the workpiece is irradiated with excitation light having a wavelength equal to or shorter than the wavelength (383 nm) corresponding to the band gap of the workpiece during the reaction, electrons existing in the valence band are transferred to the conductor (Ec). And excited to generate holes (process A in FIG. 6). SiC is processed by the action of water molecules and dissolved oxygen in the treatment liquid on the holes (process B in FIG. 6). Further, the electrons excited to the conductor are consumed by reacting with hydrogen ions in the treatment liquid to form hydrogen molecules (process C in FIG. 6). By simultaneously performing this reaction process and the above-described processing by the active species, the processing speed can be improved.

  Next, consider the case where hydroxyl radicals or oxygen atoms act on GaN. When hydroxyl radicals or oxygen atoms act on the GaN surface, the oxidizing power of hydroxyl radicals and oxygen atoms is weaker than the valence charge position of GaN, so that the reaction does not proceed because electrons cannot be taken from the valence band (FIG. 7). reference).

  Here, when the surface of the workpiece is irradiated with excitation light having a wavelength equal to or shorter than the wavelength (365 nm) corresponding to the band gap of the workpiece during the reaction, electrons existing in the valence band (Ev) are conductors ( Ec) is excited to generate holes and excited electrons (process A in FIG. 8). GaN is processed by the action of water molecules or dissolved oxygen in the treatment liquid on the holes (process B in FIG. 8). At this time, the electrons excited in the conductor are consumed by reacting with hydroxyl radicals or oxygen atoms (process C in FIG. 8).

  Here, when hydroxyl radicals or oxygen atoms do not act, the oxidizing power of the oxidant is weaker than the conductor potential, so that excited electrons cannot be consumed. In this case, the reaction in the process B of FIG. 8 does not proceed, but the recombination of excited electrons and holes occurs and the processing does not proceed. From the above, the processing of GaN proceeds by exciting the surface of the workpiece with excitation light and further consuming excited electrons by hydroxyl radicals and oxygen atoms acting on the surface of the workpiece.

(Improved machining speed by applying voltage)
Since the reaction rate cannot be controlled only by the decomposition reaction with a catalyst, it is difficult to improve the processing rate. Therefore, as shown in FIG. 9A, a DC power source 22 is connected to the workpiece 20 and the solid catalyst 21, and a voltage is applied between the workpiece 20 and the solid catalyst 21, so that the catalyst surface is It activates and promotes the decomposition reaction of the oxidizing agent (FIG. 9B). In the figure, reference numeral 23 is an active species, and 24 is an active region. When the solid catalyst 21 is brought close to the workpiece 20 as shown in FIG. 9C, the convex portion of the workpiece surface of the workpiece 20 is preferentially processed according to the flatness of the surface of the solid catalyst 21. And flattening (FIG. 9D).

In particular, the decomposition reaction of H ₂ O _{2 with} a transition metal is a one-electron reduction reaction of H ₂ O ₂ molecules on the catalyst surface. Can be improved (Haber-Weiss reaction).
H ₂ O ₂ + e ⁻ → OH ⁻ + · OH

  As a result, since a large amount of active species is generated on the catalyst surface, the processing speed of the workpiece can be improved.

(Control of processing speed by temperature control)
As is known from the Arrhenius equation, the higher the reaction temperature, the higher the chemical reaction. Since this processing method is based on a chemical reaction, it is considered that the processing speed can be changed by controlling the temperature of the catalyst, the temperature of the workpiece, and / or the temperature of the processing liquid. The production rate of active species can be controlled by controlling the temperature of the catalyst. By controlling the workpiece temperature, the reaction rate between the surface atoms of the workpiece and the active species can be controlled.

  The processing apparatus shown in FIG. 10 includes a flat rotating surface plate 31 having a solid catalyst for decomposing an oxidant on the surface, and a holder 33 having a rotating shaft 34 eccentric to the rotating shaft 32 of the surface plate 31. The processing liquid containing the oxidizing agent is supplied from the supply nozzle 35 between the surface of the catalyst and the processing surface of the processing object 30, and the processing object 30 held by the holder 33 is applied to the surface plate 31 with a predetermined amount. The surface to be processed of the workpiece 30 is flattened by being rotated while being pressed with a pressing force. Here, the rotating surface plate 31 is provided inside the container 36 to collect the processing liquid. The rotary platen 31 is provided with a flow path 37 therein to circulate a temperature adjusting fluid so that the surface temperature of the rotary platen 31, that is, the temperature of the solid catalyst can be adjusted.

  Further, a heater 39 as a temperature control mechanism for controlling the temperature of the workpiece 30 held by the holder 33 is embedded in the holder 33 so as to extend to the rotating shaft 34. The supply nozzle 35 is provided with a heat exchanger 38 so that the processing liquid controlled to a predetermined temperature can be supplied into the container 36. In this example, a heater 39 as a temperature control mechanism for controlling the temperature of the workpiece 30, a supply nozzle 35 as a temperature control mechanism for controlling the temperature of the processing liquid, and a temperature for controlling the temperature of the rotating surface plate 31. Although an example in which the flow path 37 as a control mechanism is provided is shown, any one may be provided.

  Incidentally, the light irradiation means, the voltage application means, and the temperature control means may be used alone or in an appropriate combination to promote the processing.

BRIEF DESCRIPTION OF THE DRAWINGS It is a conceptual diagram of the processing method of this invention, (a) is the state which made the solid catalyst approach the workpiece in the processing liquid, and the active species acted on the to-be-processed surface of the workpiece, (b) Each of the workpiece surfaces of the workpiece is machined and the solid catalyst is released. It is explanatory drawing which shows the decomposition reaction of hydrogen peroxide by a catalyst. It is explanatory drawing which shows the decomposition reaction of ozone water by a catalyst. It is sectional drawing for description of the processing method by a light irradiation means, (a) is the state before a process, (b) is the state which is irradiating light, (c) is the state in process, (d) is after a process Each state is shown. It is explanatory drawing which shows the reaction process when a hydroxyl radical or an oxygen atom acts on SiC. It is explanatory drawing which shows the oxidation process of SiC at the time of excitation light irradiation. It is explanatory drawing which shows the reaction process when a hydroxyl radical or an oxygen atom acts on GaN. It is explanatory drawing which shows the oxidation process of GaN at the time of excitation light irradiation. It is sectional drawing for description of the processing method which applies a voltage between a to-be-processed object and a solid catalyst, (a) is the state before a process, (b) is the state which is applying the voltage, (c) is in process (D) shows the state after processing. It is a simplified sectional view showing a processing device with a temperature control function.

Explanation of symbols

1 catalyst,
2 Workpiece,
3 active species,
4 surface atoms,
5 compounds,
6 oxidant molecules,
7 Residual molecules,
10 Workpiece,
11 solid catalyst,
12 Excitation light source,
13 Excitation light transmission window,
14 through holes,
15 active region,
16 active species,
17 Excitation light,
20 Workpiece,
21 solid catalyst,
22 DC power supply,
23 active species,
24 active region,
30 Workpiece,
31 rotating surface plate,
32 axis of rotation,
33 holder,
34 rotation axis,
35 supply nozzle,
36 containers,
37 channels,
38 heat exchangers,
39 Heater.

Claims (10)

  A work piece is disposed in a processing solution containing an oxidant, and a solid catalyst that decomposes the oxidant is brought into contact with or in close proximity to the work surface of the work piece, thereby generating strong oxidizing power generated on the catalyst. In a catalyst-assisted chemical processing method for processing a workpiece by removing or eluting a compound generated by a chemical reaction between an active species having and a surface atom of the workpiece, the workpiece is coated during the processing. Light irradiation means for irradiating the processing surface with light, voltage application means for applying a voltage between the processing surface of the workpiece and the solid catalyst, temperature of the catalyst, temperature of the workpiece and / or processing liquid A catalyst-assisted chemical processing method characterized by applying one or more of temperature control means to be combined and processing a surface to be processed.   The catalyst-assisted chemical processing method according to claim 1, wherein a decomposition rate of the oxidizing agent is controlled by adding a stabilizing agent that stabilizes the oxidizing agent to the treatment liquid. The catalyst-assisted chemical processing method according to claim 1 or 2, wherein the oxidizing agent is H ₂ O ₂ or O ₃ .   The solid catalyst is a transition metal composed of Fe, Ni, Co, Cu, Cr, Ti, a noble metal such as platinum or gold, a ceramic metal oxide, or one or a combination of two or more selected from solid basic catalysts The catalyst-assisted chemical processing method according to any one of claims 1 to 3.   The catalyst-assisted chemical processing method according to any one of claims 1 to 4, wherein the workpiece is one selected from crystalline SiC, sintered SiC, GaN, sapphire, ruby, and diamond. The catalyst-assisted chemical processing method according to claim 1 or 2, wherein the oxidizing agent is H ₂ O ₂ , the solid catalyst is Fe, the workpiece is SiC, GaN, or diamond, and processing is performed using the Fenton reaction. The catalyst-assisted chemical processing method according to claim ₂ , wherein the oxidizing agent is H ₂ O ₂ and the stabilizer is sodium silicate.   The solid catalyst is dispersed as a fine powder in the processing solution of the oxidant, and the fine powder of the solid catalyst is supplied to the processing surface of the workpiece along with the flow of the processing solution to be processed. The catalyst-assisted chemical processing method according to any one of the above.   A flat rotating surface plate having a solid catalyst for decomposing an oxidant on the surface, and a holder having a rotating shaft eccentric to the rotating shaft of the surface plate, the surface of the catalyst and the processing surface of the workpiece A processing solution containing the oxidant is supplied between them, and the work piece held by the holder is rotated while being pressed against the surface plate with a predetermined pressing force to flatten the work surface of the work piece. In the catalyst-assisted chemical processing apparatus, during the processing, a light irradiation means for irradiating light on the work surface of the workpiece, a voltage application means for applying a voltage between the work surface of the work piece and the solid catalyst, A catalyst support characterized by processing a surface to be processed by applying one or a combination of two or more of temperature control means for controlling the temperature of the catalyst, the workpiece, and / or the temperature of the processing liquid. Mold chemical processing equipment.   A treatment liquid in which a solid catalyst for decomposing the oxidant is dispersed as a fine powder in a treatment liquid containing an oxidant, and the fine powder of the solid catalyst is supplied to the work surface of the work piece as the treatment liquid flows. And a catalyst supply means are essential, a light irradiation means for irradiating light on the work surface of the work piece, a voltage application means for applying a voltage between the work face of the work piece and the solid catalyst, the temperature of the catalyst, A catalyst-assisted chemical processing apparatus characterized by processing one or two or more types of temperature control means for controlling the temperature of a workpiece and / or a processing solution to process a workpiece surface.

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