JP6762867B2 - Method for removing precious metal-containing dissimilar metal multilayer film and method for recovering precious metal - Google Patents

Description

The present invention relates to a method for removing a noble metal-containing dissimilar metal multilayer film. More specifically, an etching solution is used to remove a dissimilar metal multilayer laminated film including a noble metal layer laminated on a part of a semiconductor manufacturing apparatus, recycle the part, and recover valuable metal from the removed multilayer laminated film. It's about the method.

In the field of semiconductor devices, a plurality of metal thin films are formed as a low resistance wiring layer in a semiconductor chip or an adhesion layer with a die by a semiconductor manufacturing apparatus such as a sputtering apparatus (PVD). The inside of the semiconductor manufacturing apparatus used in the semiconductor manufacturing process has a structure in which a plurality of parts (hereinafter, may be referred to as "members") are assembled, and at regular processing times or of parts. Depending on the state of contamination, each part is disassembled and removed, and the film and dirt adhering to the parts are removed and cleaned to the same level as new, and then reused repeatedly. In addition, some of the deposits of the parts contain precious metals, which are recovered and reused after purification (Patent Document 1).

The parts of the above equipment are usually made of stainless steel (SUS) base material, but there are two major known means for removing deposits from such parts and recovering the precious metals contained in them: the physical method and the wet etching method. There is.
As a physical method, there is a sandblasting method in which an abrasive such as silica or alumina is sprayed on the deposits to physically remove the deposits, and there is an advantage that the deposits can be removed regardless of the type of the deposits. However, there were problems such as damage to parts, large-scale incidental equipment such as cyclones and bug filters, and difficulty in separating abrasives and precious metals.

Therefore, in recent years, a wet etching method that can be processed in a small-scale facility has been used. The wet etching method chemically dissolves and removes precious metals with an etching solution, and has the advantages of less damage to parts and easy recovery of precious metals contained in deposits, but for deposits that can be dissolved with an etching solution. There is a problem that it is difficult to remove multi-layer deposits including a layer that cannot be dissolved by the etching solution.

In order to improve the removal of deposits on semiconductor devices and the recovery of precious metals from semiconductor devices in such a wet etching method, a method of forming a silver and / or copper coating layer in advance on the adhesion surface of a stainless steel substrate has been proposed. (Patent Document 2). However, there still remains a problem in making it possible to remove multiple layers of deposits including a layer that cannot be dissolved by the etching solution.

Further, a vapor deposition jig and a regeneration method thereof have been proposed in which Au, Ag, and Pd adhering to the surface during vapor deposition can be recovered and regenerated (Patent Document 3), and aqua regia or nitric acid is proposed as a solution for precious metals. , Cyan, etc., as well as a solution (etching solution) containing iodine and / or iodide ion is disclosed.

However, the etching solution for precious metals described in Patent Document 3 is assumed to have Au, Ag, and Pd as objects as described above, and a large number of types adhered to the semiconductor manufacturing apparatus parts, which is the object of the present invention. It is not intended for a multilayer film in which noble metals or metals (Au, Ti, etc.) are laminated in dozens of layers.

Therefore, there is a problem that simply applying the above-mentioned conventional etching solution hinders etching by a metal film layer that is poorly soluble or insoluble in the chemical solution, and it is difficult to completely remove the adhered film. In particular, the film containing Ti is poorly soluble in the conventional etching solution, and when the adhesive film is a multilayer film containing a layer insoluble in the etching solution such as Ti, etching is inhibited there and the deposits are completely removed. However, it is possible to completely remove the deposits by alternately switching to an etching solution that dissolves Ti or the like and etching, but there is a problem that the work becomes complicated.

Further, the conventional etching solution does not assume semiconductor manufacturing equipment parts (SUS base material), and simply applying the etching solution damages the base material parts by the chemical solution, and the parts cannot be used repeatedly. Alternatively, there is a problem that the number of repeated uses is reduced.

Japanese Unexamined Patent Publication No. 5-230628 Japanese Unexamined Patent Publication No. 4-120266 Japanese Unexamined Patent Publication No. 7-21652529

Under such circumstances, the present invention is a multilayer film in which dozens of layers of metals containing a plurality of kinds of precious metals (Au, Ti, Ni, Ag, Pt, W, Al, etc.) adhering to semiconductor manufacturing equipment parts are laminated. An object of the present invention is to provide a method for removing deposits on semiconductor manufacturing equipment parts, which can remove (adhesions) and do not cause damage to the base material. Furthermore, it is an object of the present invention to provide a method for recovering a precious metal from a semiconductor manufacturing apparatus part by such a removing method.

As a result of diligent research to solve the above problems, the present inventor has found that the following invention meets the above object, and has reached the present invention.

That is, the present invention relates to the following invention.
<1> Manufacture of a semiconductor to which a noble metal-containing dissimilar metal multilayer film having a plurality of different layers including a layer of a noble metal or a noble metal alloy selected from the group consisting of Au, Ag, Pt, Pd, Rh, Ir, Ru and Os is attached. The apparatus includes a step of removing the noble metal-containing dissimilar metal multilayer film adhering to the semiconductor manufacturing apparatus part by wet etching while immersing the apparatus part in an etching solution for dissolving the noble metal and irradiating with ultrasonic waves.
A method for removing a noble metal-containing dissimilar metal multilayer film, wherein the etching solution is an etching solution containing iodine and / or an iodide salt and contains an inhibitor.
<2> Manufacture of a semiconductor to which a noble metal-containing dissimilar metal multilayer film having a plurality of different layers including a layer of a noble metal or a noble metal alloy selected from the group consisting of Au, Ag, Pt, Pd, Rh, Ir, Ru and Os is attached. The apparatus includes a step of removing the noble metal-containing dissimilar metal multilayer film adhering to the semiconductor manufacturing apparatus part by wet etching while immersing the apparatus part in an etching solution for dissolving the noble metal and irradiating with ultrasonic waves.
A method for removing a noble metal-containing dissimilar metal multilayer film, wherein the etching solution is an etching solution containing a cyanide salt and contains an inhibitor.
<3> The method for removing a noble metal-containing dissimilar metal multilayer film according to <1> or <2>, wherein the frequency of the ultrasonic waves is 800 kHz or less.
<4> The method for removing a noble metal-containing dissimilar metal multilayer film according to any one of <1> to <3>, wherein the inhibitor is sodium nitrite.
<5> The method for removing a noble metal-containing dissimilar metal multilayer film according to <1>, wherein the inhibitor is sodium nitrite and the molar ratio of sodium nitrite / iodine ion is 1.0 or more. ..
<6> The noble metal or noble metal of the noble metal-containing dissimilar metal multilayer film removed from the semiconductor manufacturing apparatus part into the etching solution by the removing step in the removing method according to any one of <1> to <5>. A method for recovering a precious metal, which comprises a step of recovering an alloy.

According to the present invention, it is possible to remove a multilayer film (adhesion) in which dozens of layers of metals containing a plurality of kinds of precious metals adhered to semiconductor manufacturing equipment parts, and damage to the base material does not occur. It is possible to provide a method for removing deposits on semiconductor manufacturing equipment parts and a simple method for recovering precious metals from a multilayer film in which metals containing multiple kinds of precious metals adhered to semiconductor manufacturing equipment parts are laminated in dozens of layers. it can.

It is a conceptual diagram of a semiconductor manufacturing apparatus (sputtering apparatus). It is a cross-sectional SEM image (× 3000 times) of a dissimilar metal laminated film. It is the appearance photograph of the sample before and after the film removal treatment. It is an SEM image (× 5000 times) and an EDX analysis chart of the sample before and after the film removal treatment.

Embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is an example (representative example) of the embodiments of the present invention, and the present invention is described below unless the gist thereof is changed. It is not limited to the contents of. In addition, when the expression "-" is used in the present specification, it is used as an expression including numerical values before and after the expression.

In the present invention, a semiconductor manufacturing equipment part to which a noble metal-containing dissimilar metal multilayer film containing a layer of a noble metal alloy is attached is immersed in an etching solution for dissolving the noble metal and adhered to the semiconductor manufacturing equipment part while irradiating ultrasonic waves. The present invention relates to a method for removing a noble metal-containing dissimilar metal multilayer film including a step of removing a noble metal-containing dissimilar metal multilayer film containing a layer of a noble metal or a noble metal alloy by wet etching.

The semiconductor manufacturing device parts of the present invention refer to parts (members) used in a thin film forming device such as ion plating, vacuum deposition method, and sputtering used in semiconductor manufacturing. In the field of semiconductor devices, a plurality of metal thin films are formed by a semiconductor manufacturing apparatus such as a sputtering apparatus (PVD) as a low resistance wiring layer in a semiconductor chip or an adhesion layer with a die. The inside of the semiconductor manufacturing apparatus used in the semiconductor manufacturing process has a structure in which a plurality of parts are assembled.

FIG. 1 shows a conceptual diagram of a sputtering apparatus which is one of the semiconductor manufacturing apparatus according to the embodiment of the present invention. As illustrated in FIG. 1, the sputtering apparatus 8 is provided in a vacuum chamber 1 at a position where particles sputtered from a target 7 which is a constituent material of a target metal film are opposed to the target 7. It is a device for forming a metal film having a predetermined film thickness by incident on it. The sputtering apparatus constitutes the vacuum chamber 1 and is also composed of parts (shield 12) for fixing the target 7 and the substrate 8 to be processed. As the part base material, stainless steel (SUS) such as austenitic stainless steel and ferritic stainless steel and titanium material are generally used from the viewpoints of prevention of impurities from being mixed into the substrate 8 to be treated, outgassing characteristics, mechanical strength, and heat resistance. Has been done. It should be noted that these are merely examples, and the target base material is particularly limited as long as the method of the present invention can be applied to suppress base material damage and remove the dissimilar metal multilayer laminated film containing a noble metal. Not done.

By the way, when the sputtering apparatus is in operation, the target material adheres to parts (shutter 9, shield 12) other than the substrate 8 to be processed. Therefore, the parts are disassembled and removed at regular operating hours or according to the contamination status of each part, and the film and dirt adhering to the parts are removed and cleaned to the same level as new, and each part is reused repeatedly. Is being done. In addition, some of the deposits on the parts contain precious metals, which are generally recovered and reused after purification.

The noble metal-containing multilayer laminated film containing a layer of a noble metal or a noble metal alloy of the present invention refers to a multilayer laminated film of a metal containing at least a layer of a noble metal or a noble metal alloy adhering to the above-mentioned semiconductor manufacturing equipment parts. In the present invention, the noble metal and the noble metal alloy may be collectively referred to as "precious metal".
With the recent increase in precision and miniaturization of semiconductor devices, thin films of target materials (sputtered materials) made of various precious metals or precious metal alloys have come to be deposited in multiple layers on a semiconductor substrate.
Examples of such precious metals include Au, Ag, Pt, Pd, Rh, Ir, Ru and Os, and examples of precious metal alloys include these alloys.

Further, the plurality of noble metal layers are those in which the above-mentioned noble metal layer is composed of at least two or more different kinds of different noble metal layers, and in addition to the noble metal layer, W, Ni, Al, Ti, Ta, Co. , Cu, Mo, Mg, Nb, Sn, Cr and other metals, AlSi, AlCu, WSi, TiW and other metal alloys, SiO ₂ , ITO, Nb ₂ O _{5 and} other oxides or Si ₃ N ₄ , TiN, AlTi. , AlTiN, TaN and the like may contain a layer of carbides such as nitride SiC and the like.
That is, the types of metal layers used and the number of layers thereof differ depending on the requirements for manufacturing semiconductor devices, and the semiconductor manufacturing equipment parts of the present invention have a multilayer laminated film composed of these metal layers. As a result, they will be laminated. These multilayer laminated films are random multilayer films in which each thin film is made of a precious metal such as Au or Pd or a metal such as Ti, W, Ni, or Al, and is a number of thin films on a SUS substrate which is a part substrate. It adheres and is laminated in sequence over ten layers.
Then, in the semiconductor manufacturing equipment parts, each part is disassembled at regular processing times or according to the contamination status of the parts, and the multilayer film attached by removing these is removed. In this case, the multilayer film on the parts is removed. The standard of the degree of lamination of the film is generally 20 to 100 layers, and the thickness is about 1 μm or less.
If the thickness is larger than this, the removal time of the multilayer film adhering from the parts by the etching solution of the present invention described below becomes too long and is not efficient.

The etching solution of the present invention is for dissolving a noble metal-containing dissimilar metal multilayer film containing a plurality of noble metal layers adhering to the semiconductor manufacturing apparatus parts. Examples of the etching solution include iodine-based etching solutions such as I ₂ and KI, and cyan-based etching solutions such as NaCN and KCN.

A preferred example of the etching solution of the present invention comprises iodine and / or an iodide salt as a constituent requirement. Further, it is preferable to add an inhibitor to iodine and / or iodide salt. It is an object of the present invention to efficiently dissolve a noble metal-containing dissimilar metal multilayer film containing a plurality of noble metal layers laminated on a part, and to have a structure that does not damage the SUS base material which is a part.

In general, the etching rate of an iodine / iodide salt aqueous solution etching solution depends on the concentration of iodine, which is an oxidizing agent. The iodine concentration of the etching solution of the present invention is preferably 1% by weight or more, more preferably 3% by weight or more, preferably 10% by weight or less, still more preferably 7% by weight or less. When the iodine concentration is at least the above lower limit, it is easy to secure a sufficient etching rate due to the oxidizing action. Further, if the iodine concentration exceeds the above upper limit, the etching rate may slow down.

Iodine has low solubility in water. Therefore, in the present invention, iodine is dissolved in water by making it a double salt by using an iodide salt together with iodine. The iodide salt used in the etching solution of the present invention may act as an anion when dissolving iodine in water, and is not particularly limited. The iodide salt used in the etching solution of the present invention may be any one capable of dissolving iodine in water. The valence of the iodide salt may be monovalent or divalent. Specific examples of the iodide salt include sodium iodide, ammonium iodide, potassium iodide and the like. One of these iodide salts may be used alone, or two or more thereof may be used in combination.

When iodine is dissolved in water as a double salt, the higher the iodide salt concentration, the higher the solubility of iodine. The iodide salt concentration of the etching solution of the present invention is preferably in the following range from the viewpoint of water solubility of iodine and reduction of the amount of residual iodine after etching. That is, the concentration of the iodide salt in the etching solution of the present invention has a lower limit of preferably 5% by weight, more preferably 6% by weight, and an upper limit of preferably 30% by weight, still more preferably 25, as a potassium iodide equivalent concentration. It is% by weight.

The molar concentration ratio of iodide salt / iodine in the etching solution of the present invention preferably has a lower limit of 1.5, more preferably 2.0, and an upper limit of 15 from the viewpoint of etching rate and the like. It is preferably 0.0, and more preferably 9.0. The total concentration of iodine and iodide salt in the etching solution of the present invention is preferably 6 to 35% by weight.

The etching rate of the etching solution of the present invention may be affected by the presence of components other than iodine and iodide salts. In general, the etching rate tends to decrease as the concentration of components other than iodine and iodide salts in the etching solution increases. Therefore, the iodine and iodide salt concentrations of the etching solution need to be appropriately adjusted so that the required etching rate can be obtained according to the type and concentration of the components other than iodine and iodide salt.

The etching solution of the present invention preferably uses an inhibitor in addition to the iodine / iodide salt. The inhibitor of the present invention is for preventing damage during etching of SUS, which is a base material of a part. The SUS substrate is usually protected from corrosion by a passivation film of hydrated chromium oxyhydroxide, but if the passivation film is destroyed for some reason, pitting corrosion (pitching) occurs. Since the etching solution of the present invention contains iodine / iodide salt, iron iodide (FeI ₂ ) is likely to be produced, and this iodide is hydrolyzed to produce iodic acid, which lowers the pH and causes corrosion (pitting corrosion). It is believed to be promoted. The inhibitor of the present invention is considered to repair the passivation film of the SUS substrate and prevent damage during etching of the SUS which is the substrate of the part.

As the inhibitor, an oxidizing agent can be used. Among these, nitrites such as sodium nitrite and potassium nitrite, chromate such as potassium chromate and ammonium chromate, molybdates such as potassium molybdate, and tungstate such as potassium tungstate can be mentioned. .. Further, among these, sodium nitrite is preferably used.

The amount of the inhibitor of the present invention to be used may be an iodine equivalent value or more, and the molar concentration ratio of nitrite / iodine ion is usually 1.0 or more. The upper limit is not particularly limited, but from the viewpoint of the etching rate, the molar concentration ratio of nitrite / iodine ion is preferably 5.0 or less, more preferably 3.0 or less.

Another example of the etching solution of the present invention is an etching solution containing a cyanide salt. The cyanide salt used in the present invention is not particularly limited as long as it is soluble in water. For example, an aqueous solution of PbCN, AuCN, AgCN or the like can be used, but one containing NaCN, KCN or the like is particularly desirable. The concentration of the cyanide salt is preferably 1% by weight to 30% by weight in terms of cyanide concentration. If it is less than 1%, the dissolution rate of Au, Ag and the like decreases. On the other hand, since the cyanide salt has strong toxicity, the concentration is preferably as low as possible, and is preferably 30% by weight or less.

Further, as the cyanide salt used in the present invention, it is preferable to use one to which an accelerator for promoting the dissolution of the metal is added. As the accelerator, organic accelerators such as formic acid, chloroacetic acid, nitrobenzoic acid, chlorobenzoic acid, oxalic acid and malonic acid, and inorganic accelerators such as ozone, hypochlorous acid and hydrogen peroxide can be used. The addition amount thereof is preferably 1 to 50 g / L.

The etching solution of the present invention also contains a balanced amount of water, and the amount thereof is usually 1% by weight or more, preferably 10% by weight or more, and usually 90% by weight or less, preferably 90% by weight or less, based on the entire etching solution. Is 80% by weight or less.

The etching solution of the present invention may contain components other than the above-mentioned iodine and / or iodide salt, cyanide salt, and water as long as the effects of the present invention are not significantly impaired. Examples of such a component include a surfactant for improving the wettability of the object to be treated and a buffer for stabilizing the solubility of the noble metal. The concentration of the components of the etching solution may be any amount as long as it can be dissolved by chemically reacting with the metal film to be dissolved and removed, and the concentration is not particularly limited.

The method for producing the etching solution of the present invention is not particularly limited, and for example, in the case of an iodine-based etching solution, it can be obtained by mixing an iodine source, an inhibitor, and other components to be blended as necessary in a predetermined blending. Can be done. Preferably, a method of adding iodine to a solution containing an iodide salt and an inhibitor is used.

Next, the method for removing the noble metal-containing dissimilar metal film of the present invention will be specifically described. The present invention contains a noble metal, which comprises a step of wet-etching a multilayer laminated film containing a plurality of precious metal or noble metal alloy layers adhering to a semiconductor manufacturing apparatus part while irradiating an object with an etching solution using an etching solution. The present invention relates to a method for removing a multilayer film of dissimilar metals, and a method for removing an etching solution containing iodine and / or an iodide salt as an etching solution will be described below as an example.

The multilayer laminated film containing a plurality of layers of a plurality of noble metals or noble metal alloys attached to the semiconductor manufacturing equipment parts, which is the object of the present invention, and the etching solution containing iodine and / or iodide salt are as described above.
The method for removing a noble metal-containing dissimilar metal multilayer film including a step of wet etching of the present invention is characterized in that wet etching is performed while irradiating an object with ultrasonic waves. Hereinafter, the method for removing the noble metal-containing dissimilar metal multilayer film of the present invention will be described in detail with reference to FIG.

(1) In FIG. 1, a noble metal-containing dissimilar metal multilayer film (adhesion) containing several tens of various noble metal layers is formed on the part (12) of the sputtering apparatus 1 after a certain processing time has passed. They are appropriately removed to remove deposits, for example, before the layer thickness reaches 1 mm.

(2) Each removed part is subjected to a wet etching step individually or simultaneously.
In wet etching, a solution containing an inhibitor such as iodine and / or iodide salt and sodium nitrate is used as the etching solution.
Wet etching is performed by immersing a part as an object in an etching solution and irradiating the object with ultrasonic waves. If it is not irradiated with ultrasonic waves, the etching effect is inferior, and it is difficult to efficiently remove deposits in an industrial sense.
The conditions for wet etching can be appropriately selected depending on the object to be treated, but if the temperature at which the etching solution is brought into contact with the object to be treated is excessively high, the solute may be precipitated due to evaporation of the solvent component of the solution, and the temperature may be excessive. If it is low, solidification or solubility of the noble metal is lowered. Therefore, it is preferably in the range of 5 to 80 ° C, preferably 10 to 70 ° C, and more preferably 15 to 65 ° C.

The contact (immersion time) differs depending on the shape (number of layers, thickness) of the object to be treated, but it is sufficient if the time is such that the dissimilar metal multilayer laminated film can be removed. The higher the temperature, the shorter the time, but the work efficiency. The desired time may be set in consideration of the above. Usually, about 1 to 100 hours is sufficient. The amount of the etching solution used may be any amount as long as it can sufficiently dissolve the noble metal in the object to be treated according to its composition, and is not particularly limited. However, in the etching solution of the present invention, the noble metal is usually used. Since it can be dissolved in an amount of about 0.01 to 10% by weight, the amount of etching used may be appropriately determined according to the dissolution concentration.

Further, the present invention is characterized in that a metal laminated film that cannot be dissolved and removed by the etching solution is physically peeled and removed between a base material or a multilayer film by using ultrasonic waves in combination. The action of ultrasonic waves is the removal of peeling by the shock wave of cavitation. In general, the higher the frequency of ultrasonic waves, the weaker the impact force, and conversely, the lower the frequency, the stronger the impact force, and the higher the peeling removal effect. However, if the impact force is too strong, the impact force on the surface of the base material also becomes strong, so it is necessary to consider that the base material itself is damaged by erosion. The ultrasonic wave used in the present invention has a frequency of 800 kHz or less, preferably 500 kHz or less, and more preferably 300 kHz or less.

(3) The object subjected to wet etching is subjected to another process as necessary, and the recycled parts are reused.
Other steps include, for example, a step of removing stains on the surface of parts by ultrasonic cleaning, rinsing cleaning by ultrapure water immersion cleaning, and finally removing water by forced drying by baking.

(4) On the other hand, the noble metal dissolved in the wet etching step is treated by a known noble metal recovery method such as adding a reducing agent to the etching solution in which the metal is dissolved to reduce the noble metal ion and precipitating the noble metal. , Can be separated and collected.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is changed.

(1) Production of object (precious metal-containing dissimilar metal laminated film on parts) The test piece (sample) to be etched was prepared as follows. First, a 5 cm square SUS304 substrate was prepared, and one surface of the substrate surface was uniformly treated with a gravity blasting machine using a white alumina 60-count abrasive. After removing the abrasive on the surface of the base material by air blowing, Au and Ti were alternately laminated and formed on the surface of the base material that had been blasted to a thickness of 1 μm using a sputtering device. The amount of film formation was confirmed by the change in weight, and the number of film formations was 20 times each for Au and Ti. FIG. 2 shows a cross-sectional SEM image (× 3000 times) of the laminated film.

(2) Reagents used Iodine is a 99.7% pure product manufactured by Joint Resources Industry Co., Ltd., potassium iodide is a 99.5% pure product manufactured by Joint Resources Industry Co., Ltd., and other reagents are pure Wako. A special grade reagent manufactured by Yakuhin Kogyo Co., Ltd. was used.

<Example 1>
The etching solution is prepared by first dissolving potassium iodide (KI) in pure water to a concentration of 16.7% by weight, then adding iodine (I ₂ ) at a concentration of 4.2% by weight and stirring and dissolving. did.
The etching test was performed as follows. First, an ultrasonic oscillator of an ultrasonic cleaner (Branson S8500, frequency 28 kHz) was installed at the bottom of a 40 cm square SUS tank. A SUS mesh-shaped mount having a height of 10 cm higher than that of the vibrator was prepared and installed so as to cover the vibrator. A 500 mL glass beaker containing 400 mL of the etching solution was installed on the gantry. The test piece was placed on the bottom of the beaker with the laminated film facing up, and water was filled in the SUS tank so as to be at the same height as the liquid level of the etching solution. While installing a chiller in the SUS tank and adjusting the temperature so that the water temperature became 25 ° C., the power of the ultrasonic cleaner was turned on and ultrasonic cleaning was started. The test piece was taken out every hour from the start of washing, and after washing with water and drying, the presence or absence of film removal was confirmed. The film removal confirmation means was carried out by appearance and scanning electron microscope (SEM) / energy dispersive X-ray spectroscopy (EDX). The scanning electron microscope was manufactured by JEOL Ltd., and the energy dispersive X-ray spectroscopy was manufactured by Edax Japan Co., Ltd.

Table 1 shows the evaluation conditions such as the etching solution composition, etching conditions, ultrasonic conditions, and the evaluation results of deposit removability and pitching. In addition, "adhesion removability" means that "○" was able to remove the deposits, "△" means that there is a residue of the deposits but it is at a usable level, and "pitching" means "pitching". "○" indicates that no pitching was observed and there was no damage to the base material, and "△" indicates that pitching was observed but the level was usable.
FIG. 3 shows a photograph of the appearance of the sample before and after the film removal treatment. The appearance of the sample before the film removal treatment was a slightly yellowish color due to the gold film in the adhered multilayer film, but after the film removal treatment, the multilayer film was removed and the SUS of the base material was used. Shown the color. In addition, no pitching of the base material due to the film removal treatment was observed. FIG. 4 shows the results of SEM / EDX analysis (× 5000 times) of the sample before and after the film removal treatment. In the sample before the film removal treatment, peaks caused by Au and Ti in the multilayer film can be confirmed, but after the film removal treatment, the peaks caused by Au and Ti disappear, and instead, the SUS of the base material is used. It was confirmed that the resulting peaks of Fe and Cr could be confirmed, and that the multilayer film was completely removed by the film removal treatment.

<Example 2>
The test piece to be etched was prepared in the same manner as in Example 1 using a 5 cm square SUS316 base material.
The adjustment of the etching solution and the etching test were carried out in the same manner as in Example 1. Table 1 shows the evaluation conditions and evaluation results. It was confirmed that the multilayer film was completely removed by the film removal treatment. In addition, no pitching was observed on the substrate due to the film removal treatment.

<Example 3>
The test piece to be etched was prepared in the same manner as in Example 1 using a 5 cm square SUS430 base material. The adjustment of the etching solution and the etching test were carried out in the same manner as in Example 1. Table 1 shows the evaluation conditions and evaluation results. It was confirmed that the multilayer film was completely removed by the film removal treatment. In addition, no pitching was observed on the substrate due to the film removal treatment.

<Example 4>
The test piece to be etched was prepared in the same manner as in Example 3.
The etching solution is prepared by dissolving potassium iodide (KI) at a concentration of 16.7% by weight and sodium nitrite at a concentration of 9.2% in pure water, and then adding iodine (I ₂ ) at a concentration of 4.2% by weight. It was prepared by adding and stirring and dissolving.
The etching test was performed in the same manner as in Example 1. Table 1 shows the evaluation conditions and evaluation results. It was confirmed that the multilayer film was completely removed by the film removal treatment. In addition, no pitching was observed on the substrate due to the film removal treatment.

<Example 5>
The test piece to be etched and the etching solution were prepared in the same manner as in Example 4.
The etching test was carried out in the same manner as in Example 1 except that the temperature was not adjusted by the chiller and the etching was performed at a natural liquid temperature (about 60 ° C.). Table 1 shows the evaluation conditions and evaluation results. It was confirmed that the multilayer film was completely removed by the film removal treatment. In addition, no pitching was observed on the substrate due to the film removal treatment.

<Example 6>
The test piece to be etched and the etching solution were prepared in the same manner as in Example 4.
The etching test was carried out in the same manner as in Example 5 except that the ultrasonic cleaner was changed to Branson S8500 and the frequency was 80 kHz. Table 1 shows the evaluation conditions and evaluation results. It was confirmed that the multilayer film was completely removed by the film removal treatment. In addition, no pitching was observed on the substrate due to the film removal treatment.

<Example 7>
The test piece to be etched and the etching solution were prepared in the same manner as in Example 3.
The etching test was performed in the same manner as in Example 5. Table 1 shows the evaluation conditions and evaluation results. It was confirmed that the multilayer film was completely removed by the film removal treatment, but a level of pitching that could be used for the substrate was observed. It is considered that this is because the temperature of the etching solution is as high as 60 ° C., the etching solution does not contain an inhibitor, and there is no effect of preventing damage to the base material.

<Example 8>
The test piece to be etched and the etching solution were prepared in the same manner as in Example 4.
The etching test was carried out in the same manner as in Example 5 except that the ultrasonic cleaner was changed to a C-88S-71 type manufactured by Kaijo and a frequency of 950 kHz. Table 1 shows the evaluation conditions and evaluation results. The film removal treatment confirmed a usable level of multilayer film residue. This is because the frequency of the ultrasonic waves used in the film removal process is too high, so the particle size of the generated cavitation becomes too fine, and as a result, the impact force due to cavitation becomes weak, and the multilayer film can be sufficiently removed. It is probable that it was not broken.

<Comparative example 1>
The test piece to be etched and the etching solution were prepared in the same manner as in Example 3.
In the etching test, 400 mL of the etching solution was charged in a 500 mL glass beaker, and the test piece was placed on the bottom of the beaker with the laminated film facing up. A beaker was placed in the SUS tank, and water was filled in the SUS tank so that the level of the etching solution was the same as that of the etching solution. A chiller was installed in the SUS tank, and etching was performed while adjusting the temperature so that the water temperature was 25 ° C. The film removal was confirmed in the same manner as in Example 1.
Table 2 shows the evaluation conditions such as the etching solution composition, the etching conditions, and the ultrasonic conditions, and the evaluation results of the deposit removability and pitching. It was confirmed that the multilayer film was hardly removed by the film removal treatment. It is probable that this is because the multilayer film was not sufficiently removed because there was no physical peeling effect by ultrasonic waves in the film removal treatment.

<Comparative example 2>
The test piece to be etched and the etching solution were prepared in the same manner as in Example 4.
In the etching test, 400 mL of the etching solution was charged in a 500 mL glass beaker, and the test piece was placed on the bottom of the beaker with the laminated film facing up. A beaker was placed in the SUS tank, and water was filled in the SUS tank so that the level of the etching solution was the same as that of the etching solution. Etching was performed while installing a heater in the SUS tank and adjusting the temperature so that the water temperature became 60 ° C. The film removal was confirmed in the same manner as in Example 1. Table 2 shows the evaluation conditions and evaluation results. It was confirmed that the multilayer film was hardly removed by the film removal treatment for 4 hours. Further, the film removal treatment was extended to 6 hours, and the same result was obtained. It is probable that this is because the multilayer film was not sufficiently removed because there was no physical peeling effect by ultrasonic waves in the film removal treatment.

<Example 9>
The test piece to be etched was prepared in the same manner as in Example 3.
The etching solution was prepared by dissolving sodium cyanide in pure water at a concentration of 2.2% by weight and sodium metanitrobenzoate at a concentration of 0.3% by weight.
The etching test was carried out in the same manner as in Example 5 while bubbling 0.5 L / min of air in the etching solution.
Table 3 shows the evaluation conditions such as the etching solution composition, the etching conditions, the ultrasonic conditions, and the evaluation results of the deposit removability and pitching.
It was confirmed that the multilayer film was completely removed by the film removal treatment. In addition, no pitching was observed on the substrate due to the film removal treatment.

<Comparative example 3>
The test piece to be etched and the etching solution were prepared in the same manner as in Example 7.
The etching test was carried out in the same manner as in Comparative Example 2 while bubbling 0.5 L / min of air in the etching solution. Table 3 shows the evaluation conditions and evaluation results. It was confirmed that the multilayer film was hardly removed by the film removal treatment. It is probable that this is because the multilayer film was not sufficiently removed because there was no physical peeling effect by ultrasonic waves in the film removal treatment.

According to the present invention, it is possible to remove a multilayer film (adhesion) in which dozens of layers of a plurality of types of metals including precious metals are laminated on semiconductor manufacturing equipment parts, and a semiconductor that does not cause damage to the base material. A method for removing deposits on manufacturing equipment parts and a method for recovering precious metals adhering to semiconductor manufacturing equipment parts are provided.

1. 1. Vacuum chamber 2. Vacuum exhaust port 3. Vacuum exhaust device 4. Cathode electrode 5. Matching box 6. RF power supply 7. Target (metal material source)
8. Substrate to be processed 9. Shutter 10. High pressure gas container 11. Piping system 12. shield

Claims (6)

Semiconductor manufacturing equipment parts to which a noble metal-containing dissimilar metal multilayer film having a plurality of different layers including a layer of a noble metal or a noble metal alloy selected from the group consisting of Au, Ag, Pt, Pd, Rh, Ir, Ru and Os is attached. , while irradiating the immersed and ultrasonic wave to the etchant to dissolve the precious metals, viewed contains a step of removing by wet etching the noble metal-containing heterogeneous metal multilayer film adhered to the semiconductor manufacturing apparatus parts,
A method for removing a noble metal-containing dissimilar metal multilayer film, wherein the etching solution is an etching solution containing iodine and / or an iodide salt and contains an inhibitor . Semiconductor manufacturing equipment parts to which a noble metal-containing dissimilar metal multilayer film having a plurality of different layers including a layer of a precious metal or a noble metal alloy selected from the group consisting of Au, Ag, Pt, Pd, Rh, Ir, Ru and Os is attached. , The step of removing the noble metal-containing dissimilar metal multilayer film adhering to the semiconductor manufacturing apparatus parts by wet etching while immersing in an etching solution for dissolving the noble metal and irradiating ultrasonic waves.
A method for removing a noble metal-containing dissimilar metal multilayer film, wherein the etching solution is an etching solution containing a cyanide salt and contains an inhibitor. The method for removing a noble metal-containing dissimilar metal multilayer film according to claim 1 or 2 , wherein the frequency of the ultrasonic waves is 800 kHz or less. The method for removing a noble metal-containing dissimilar metal multilayer film according to any one of claims 1 to 3 , wherein the inhibitor is sodium nitrite. The method for removing a noble metal-containing dissimilar metal multilayer film according to claim 1, wherein the inhibitor is sodium nitrite, and the molar ratio of sodium nitrite / iodine ion is 1.0 or more. The step of recovering a noble metal or a noble metal alloy of a noble metal-containing dissimilar metal multilayer film removed from the semiconductor manufacturing apparatus part in the etching solution by the removing step in the removing method according to any one of claims 1 to 5. How to recover your precious metal.