JP2001240985A - Treatment method and treating liquid for solid surface and method for manufacturing electronic device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To etch and melt noble metals represented by ruthenium, within a practicably usable time range. SOLUTION: An oxidizing agent having a sufficiently higher oxidation reduction potential as compared to the metal to be treated is used and the reaction with the oxygen atoms released from this oxidizing agent is utilized in the process of reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching process for a solid surface and a processing solution thereof, and more particularly to a method for manufacturing an electronic device using the same.

[0002]

2. Description of the Related Art In general, in a process of manufacturing an electronic device, a treatment of dissolving a solid represented by a metal in a treatment liquid by a chemical reaction between the solid and a treatment liquid is one method of solid processing. It is widely applied to an etching method, a cleaning method for removing specific foreign matter from a solid surface, and the like. The processing liquid is a fluid or a stationary body containing at least a liquid, and may be composed of only a liquid phase, or a liquid phase and a gas phase, or a liquid phase and a solid phase. Furthermore, the liquid phase in the processing liquid may be composed of two or more liquid phases.

However, an oxidizing agent is indispensable for performing the above-described reactions such as etching and dissolving of a solid. For example, when etching copper, an aqueous solution of potassium hexacyanoiron (III) or an aqueous solution of sodium sodium peroxodisulfate is used as an oxidizing agent, and an aqueous solution of alkaline potassium permanganate is used for dissolving chromium. Metals such as copper and chromium are oxidized by these oxidizing agents, and are dissolved in a solution by binding to an appropriate ligand. This ligand may be a solvent molecule, for example a water molecule,
Ammonia or cyanide may be added as needed.

On the other hand, in the process of manufacturing an electronic device typified by a silicon-based semiconductor element, generally, hydrogen peroxide is mainly used as an oxidizing agent. The reason for this is
When an oxidizing agent containing a metal element such as hexacyanoiron (III) ion is used, a semiconductor element or the like may be newly contaminated by the metal element contained in the oxidizing agent, and thus does not contain a metal element. The use of an oxidizing agent is indispensable, and the hydrogen peroxide solution is industrially easily available because the technology for purifying hydrogen peroxide has been established.

As an example, metals such as cobalt and titanium used in the process of forming the source and drain electrodes of a field effect transistor include an aqueous solution obtained by mixing hydrochloric acid and hydrogen peroxide solution, or an aqueous solution obtained by mixing ammonia water and peroxide. It is dissolved by an aqueous solution obtained by mixing hydrogen water. When removing a metal element from the surface of a semiconductor wafer, an aqueous solution containing hydrochloric acid and aqueous hydrogen peroxide, an aqueous solution containing sulfuric acid and aqueous hydrogen peroxide, or an aqueous solution containing hydrofluoric acid and aqueous hydrogen peroxide Is often used.

[0006]

The condition to be satisfied by the oxidizing agent is that the oxidizing agent used has a higher oxidation-reduction potential than that of the solid to be treated. That is, taking the case of copper etching, which is a conventional example, as an example, Chemical Handbook Revised 4th Edition, Basic Edition II (hereinafter referred to as Document 1)
As described in the above, since the oxidation-reduction potential of Cu ²⁺ / Cu is 0.340 V (with reference to the standard hydrogen electrode: all potentials below are with respect to the standard hydrogen electrode), the hexacyanoiron (II)
I) The oxidation of copper is promoted by ions (redox potential: 0.361 V) and peroxodisulfate ions (redox potential: 1.96 V), but hexacyanochrome (III)
The ion (redox potential: −1.14 V) does not cause the oxidation reaction of copper.

Therefore, it is necessary to consider the above-mentioned electrochemical reaction also in the etching of a noble metal such as ruthenium, which is used in accordance with recent advances in high integration and high speed of semiconductor devices.

However, aqueous hydrogen peroxide which has been generally used in the past cannot be used for dissolving precious metals such as ruthenium. That is, hydrogen peroxide has an oxidation-reduction potential (H) that is sufficiently higher than that of ruthenium.
Redox potential of ₂ O ₂ / H ₂ O at pH = 0: 1.763
V; according to Document 1), a processing solution using aqueous hydrogen peroxide cannot provide a sufficient etching rate for ruthenium.

Furthermore, even if a chemical solution containing peroxodisulfate or nitric acid, which has been conventionally used for etching copper or iron, is used, it is necessary to ensure a sufficient etching rate for noble metals such as ruthenium. Is difficult.

In view of the above background, in a semiconductor device manufacturing process, it is widely desired to develop a processing solution having a sufficient etching rate for the above-mentioned noble metal, and by realizing this, a semiconductor exhibiting excellent performance is realized. The emergence of devices will greatly contribute to the development of industrial fields such as communication, information, and image display.

[0011]

For example, ruthenium, which is a noble metal element of white metal, is considered to be extremely difficult to be oxidized.
In the oxidation treatment, it is necessary to use an oxidizing agent having a strong oxidizing power, that is, a high oxidation-reduction potential.

When considering the etching of ruthenium, ruthenium can be made soluble by changing it into ruthenium tetroxide (RuO ₄ ) bonded to four oxygen atoms.

At this time, the standard electrode potential of ruthenium and ruthenium tetroxide is 1.13 V (M. Pou
rbaix; "Atlas of Electrochemical Equilibria in Aqu
eousSolutions ", 1st English Edition, Chapter IV, P
ergamon, Oxford (1966): hereinafter referred to as Reference 2).
Further, the potential at which ruthenium tetroxide is electrochemically generated from ruthenium is further increased when overvoltage is included.
4 to 1.47 V (Reference 2). Therefore,
As an oxidizing agent to be used for etching ruthenium,
For example, when used at pH = 0, it is desirable that the oxidation-reduction potential be at least 1.13 V, and if possible, 1.4 V or more.

[0014] Further, in the oxidative dissolution of ruthenium, a bond with an oxygen atom is indispensable, as can be seen from the molecular formula of the product. Therefore, an oxidizing agent or water is a candidate as a source for supplying this oxygen atom.However, in the reaction in the aqueous solution, since the activity of water is almost constant, the oxygen atom is positively released and is combined with ruthenium. Use of such an oxidizing agent is effective for efficient oxidative dissolution of ruthenium.

In other words, an oxidizing agent such as a noble metal typified by ruthenium used for generating a compound bonded to oxygen and dissolving it efficiently has an oxidation-reduction potential of the oxidizing agent which tends to dissolve. It is necessary that the oxidizing agent release oxygen atoms above the oxidation-reduction potential of the metal dissolution reaction and in the course of the reaction.

The oxidizing agent that releases an oxygen atom in the oxidation reaction means the following oxidizing agent. That is, among the atoms constituting the oxidizing agent, the atom whose oxidation number decreases in the course of the reaction is referred to as an oxidation center atom, and one or more of the oxygen atoms bonded to the oxidation center atom becomes the oxidation center atom. An oxidizing agent that breaks a bond with an atom and newly bonds to an oxidized atom.

Next, the mechanism by which the oxidizing agent that releases oxygen atoms efficiently oxidizes and dissolves ruthenium will be described below.

Many oxidation reactions of ruthenium ions instead of ruthenium metal have been reported so far, for example, nitrosyl ruthenium ions ([Ru ^II (NO)] ₃ ⁺ )
Is oxidized by nitric acid and peroxodisulfate ions to become ruthenium tetroxide.

However, according to the study by the inventors,
Ruthenium metal is not oxidized and dissolved by nitric acid or peroxodisulfate ion. Why ruthenium metal is not oxidized melted by nitric acid, the oxidation-reduction potential (HNO ₃ / NO ₂ required for the oxidation of nitric ruthenium metal ^- the standard electrode potential of 0.
835 V; this is because it does not have Reference 1).

The reason that ruthenium is not oxidized and dissolved even by peroxodisulfate ions is because oxygen atoms are not released in the course of the reaction as shown in the following (Formula 1).

S ₂ O ₈ ²⁻ +2 e ⁻ → 2SO ₄ ²⁻ (Equation 1) From the above, it is determined whether or not the oxidizing agent releases an oxygen atom in the process of further oxidizing the ruthenium ion having a positive oxidation number. Although this does not greatly affect, in the process of oxidizing and dissolving ruthenium metal having an oxidation number of 0, it is essential that oxygen atoms be released from the oxidizing agent. That is, the oxidizing agent that releases oxygen atoms contributes to the process of oxidizing ruthenium metal having an oxidation number of 0.

The metal to be dissolved is not limited to ruthenium. For example, noble metals such as osmium can be considered in exactly the same manner. Oxidizing agents suitable for dissolving these noble metals include oxidizing agents that donate oxygen atoms, and as such, hypochlorite ion, chlorite ion, chlorate ion, Perchlorate ion, hypobromite ion, bromite ion, bromate ion, perbromate ion, hypoiodite ion, iodite ion, iodate ion, permanganate ion, chromate ion, Any material containing any of ions such as chromate ion, nitrate ion and nitrite ion and periodic acid may be used.

By the way, the treatment solution containing periodic acid is
Ion comprising at least +7 valent iodine (I (OH)
_{^{6 +, IO 4 -, H}} 4 IO 6 -, refers to H ₃ IO ₆ ^2-, etc.) or a treatment solution containing one of orthoperiodic acid (H ₅ IO _6). The term periodate concentration refers to the sum of the concentration of ions consisting of + 7-valent iodine and ortho periodate contained in the treatment liquid.

Among the above-mentioned oxidizing agents, for example, when a treatment solution containing periodic acid is used under certain conditions, ruthenium or osmium can be more efficiently dissolved. That is, when the pH of the treatment liquid containing periodic acid is 2 or more and 10 or less, more preferably 4 or more and 8 or less, and the concentration of periodic acid contained in the treatment liquid is 0.01 mol / L or more, industrial It is possible to secure a sufficient throughput for manufacturing an electronic device or the like on a large scale.

In general, orthoperiodic acid which has a sufficiently low concentration of an alkali metal ion or an alkaline earth metal ion or does not contain an alkali metal salt or an alkaline earth metal salt can be used. It is possible to apply a processing solution utilizing these to a semiconductor manufacturing process.

[0026]

Embodiments of the present invention will be described below in detail with reference to the drawings.

The target substance to which this embodiment is applied is not particularly limited, and examples thereof include a substance containing ruthenium or osmium. Further, the shape of the target substance is not particularly limited, as it has a film shape, a particle shape, and other complicated structures.

The details of the concentration of the oxidizing agent and the processing conditions (heating temperature, stirring method, etc.) will be described in detail in the following examples, but are not limited to these examples unless they exceed the gist. It is not something to be done.

(First Example) Ruthenium metal was used as a typical example of a noble metal, and the etching effect on oxidizing agents containing various ions was examined. The results are summarized in Table 1.

The etching was performed using a well-known method. That is, a ruthenium thin film (thickness: 200 nm) is formed on a silicon wafer (30 × 40 mm) by using a normal sputtering method, and a photoresist film is coated and baked on a part of the ruthenium thin film by a well-known method. This wafer is immersed in a solution containing an oxidizing agent at room temperature for about 1 to 30 minutes. Thereafter, the photoresist film was sufficiently washed and washed, and then the photoresist film was removed by a well-known method. Then, the etching step formed on the surface of the ruthenium thin film was measured using a commonly used stylus step meter. Note that the film thickness measurement is not limited to the above method, and a method using, for example, fluorescent X-rays may be used.

[0031]

[Table 1]

As is clear from these results, when an oxidizing agent containing hydrogen peroxide solution, peroxodisulfate ion, nitric acid and iodine was used, the ruthenium thin film was hardly dissolved, but hypochlorous acid was used. When bromate, bromate and periodate were used, remarkable etching of the ruthenium thin film was observed. All of these oxidants release oxygen atoms in the following reactions.

ClO ⁻ → Cl ⁻ + (O) (Equation 2) BrO ₃ ⁻ → Br ⁻ +3 (O) (Equation 3) IO ₄ ⁻ → IO ₃ ⁻ + (O) (Equation 4) H ₄ IO ₆ ⁻ → IO ₃ ⁻ + 2H ₂ O + (O) (Equation 5) On the other hand, even with an oxidizing agent having an oxidation-reduction potential sufficient for oxidizing ruthenium metal, there is a case where etching of ruthenium metal is hardly confirmed. For example, the above-mentioned reaction of peroxodisulfuric acid does not release an oxygen atom as shown in (Equation 1), and iodine does not release as shown in the following reaction formula.

I ₂ + 2e ⁻ → 2I ⁻ (Equation 6) Accordingly, since the oxygen atom to be bonded to the ruthenium metal is not supplied from the oxidizing agent, the etching reaction of the ruthenium metal does not proceed, or it is confirmed by a usual method. It is concluded that the etching reaction is too slow.

FIG. 1 schematically shows the difference in behavior between the oxidizing agent that releases oxygen atoms and the oxidizing agent that does not release oxygen atoms.

[0036] Here, the hydrogen peroxide and the reaction which releases oxygen atom (7), two OH without release oxygen atoms ^- ions decompose the reaction and (Equation 8) can be considered.

H ₂ O ₂ → H ₂ O + (O) (Equation 7) H ₂ O ₂ + 2e ⁻ → 2OH ⁻ (Equation 8) However, as is clear from the results in Table 1, etching of ruthenium metal is performed. Is not recognized, it is considered that when the treatment liquid contains aqueous hydrogen peroxide, the reaction of the above (Equation 8) is in progress.

That is, as described above, although the redox potential of hydrogen peroxide is higher than that of ruthenium metal, oxygen atoms are not released in the reaction, so that etching of ruthenium metal does not occur.

In FIG. 1, (a) shows an oxygen atom 101
Oxidizing agent that does not release iodine. The iodine atom 102 is converted into two iodide ions by the reaction, and the oxygen atom 101 is not released.

As a result, the ruthenium metal has an oxygen atom of 10
Since 1 cannot be received, it cannot be ruthenium tetroxide (RuO ₄ ) 111 and does not dissolve.

On the other hand, FIG. 1B shows a case where a metaperiodate ion 113 which is an oxidizing agent releasing an oxygen atom 101 is used. Metaperiodic acid has four oxygen atoms in one ion, and one of them is released in the course of the reaction to become iodate ion 112 having three oxygen atoms. Ruthenium receives the oxygen atoms 101 released in this process to become ruthenium tetroxide 111 and dissolves.

As described above, when a noble metal typified by ruthenium metal is dissolved by etching, a practical solution can be obtained by using a solution containing at least hypochlorous acid, bromic acid, periodic acid, or the like as a processing solution. The processing can be performed within a short time range.

The treatment liquid is not limited to a solution containing hypochlorous acid, bromic acid, periodic acid, or the like, but releases an oxygen atom in the reaction, that is, an oxidizing agent having an oxygen atom donating property. If the solution contains, it is possible to obtain the same processing effects as in this embodiment.

(Second Embodiment) As a second embodiment, an example of a specific preparation method of the above-mentioned treatment solution containing periodic acid will be described.

In the manufacture of a semiconductor device containing ruthenium, the processing solution used therein does not contain alkali metal ions and alkaline earth metal ions which are generally considered to have a significant effect on the performance of the semiconductor device. Or their concentrations are required to be sufficiently low.

Thus, as an example of a method for preparing a periodate-containing treatment solution in which the concentrations of alkali metal ions and alkaline earth metal ions are sufficiently low, for example, orthoperiodic acid was used.

The reason for this is that, even with orthoperiodic acid, which is commonly used, the concentration of alkali metal ions can easily be reduced to 50 ppm or less and the concentration of alkaline earth metal ions can be reduced to 5 ppm or less. Thus, using these, a processing solution suitable for the etching treatment of ruthenium metal can be prepared.

The pH of the treatment liquid is adjusted by adding an acid or base having a sufficiently low concentration of alkali metal ions and alkaline earth metal ions.

In this example, for example, nitric acid was added as an acid, and tetramethylammonium hydroxide (TMAH) was added as a base. The acids and bases are not limited to the above-mentioned chemicals as long as the alkali metal ions and alkaline earth metal ions contained therein have sufficiently low concentrations.

The relationship between the pH and the dissolution rate of ruthenium metal was examined by the following method using the treatment solution containing periodic acid prepared as described above.

In a 200 mL beaker equipped with a stirrer and a thermometer, 148 mL of a 0.2 mol / L orthoperiodic acid-treated solution adjusted to a predetermined pH was placed, and the beaker was placed in a constant temperature bath to raise the temperature of the treatment solution to 60 ° C. It was fixed. The pH of the treatment liquid was adjusted from 0 to 12 by changing the addition amounts of the above-mentioned nitric acid and tetramethylammonium hydroxide. In addition, the concentration of periodic acid is constant for each pH (0.01 mol
/ L).

Although this concentration is not specified at all, as will be described later, when etching a metal such as ruthenium using a processing solution containing periodic acid, the throughput of the production line is taken into consideration. For example, 7
A dissolution rate of 0 nm / min or more can be obtained.
It is desirably at least 01 mol / L.

The ruthenium metal for the etching study is as follows.
What was formed as a smooth film having a thickness of 100 nm on a 5 cm × 2.0 cm plate-like silicon (Si) by a usual method was used. This ruthenium plate is fixed to the center of the bottom surface of the beaker in a direction perpendicular to the liquid surface of the prepared processing solution using a fixing jig, so that the entire surface of the ruthenium plate to be dissolved is in contact with the processing solution. I made it. During the ruthenium dissolution reaction,
The stirrer arranged at the center of the bottom of the beaker was always rotated at 180 rpm so that a constant amount of the reaction molecules of the treatment liquid was always supplied to the surface of the ruthenium plate. The pH of the treatment liquid was measured at room temperature (about 23 ° C.) before and after dissolution of ruthenium.

Table 2 summarizes the results obtained.

Table 2 Relationship between pH of treatment liquid and dissolution rate of ruthenium ｐＨ Dissolution of pH of treatment liquid Speed ０ 0 to less than 2 × 2 to less than 4 △ 4 to less than 8 ○ 8 to less than 10 △ 10 ~ <12 XX In the above Table 2, the dissolution rate of ruthenium was evaluated as follows. .

That is, assuming that a semiconductor device using ruthenium is produced, and considering the throughput of the production line, it was determined that the higher the dissolution rate, the higher the industrial utility value. Here, as an example, the dissolution rate is 70 n
The case where m / min or more was obtained was evaluated with a symbol of Δ, and the case where a more desirable dissolution rate was obtained was evaluated with a symbol of ○.

As a result, as the pH of the treatment liquid increases, the dissolution rate of ruthenium increases, and the pH becomes 2 to 10
Within this range, an industrially usable dissolution rate can be secured. It has been found that the most desirable range is pH 4 to 8. By the way, the behavior of the dissolution rate of ruthenium shown in Table 2 can be described as a change in activity distribution of ionic species accompanying a change in pH in a treatment solution containing periodic acid. That is, since the dissociation constant of orthoperiodic acid has already been determined, the activity of each ionic species at each pH can be determined using the value.

Since the dissolution of ruthenium proceeds efficiently in the range of pH 2 or more and 10 or less where IO ₄ ⁻ is the main component, IO ₄ ⁻ or H ₄ IO ₆ ⁻ which is always present at a constant ratio to ruthenium is converted to ruthenium. Clearly governs the dissolution of The factor that controls the dissolution of ruthenium at a pH of 2 or less is based on the dissociation constant of periodic acid.
(OH) is considered to ₆ ^+.

The dissolution rate of ruthenium varies depending on the dissolution conditions such as the concentration and pH of periodic acid in the treatment liquid, the temperature of the treatment liquid, the amount of the treatment liquid, the method of stirring the treatment liquid, and the speed thereof.

In the above embodiment, in order to improve the ruthenium dissolution efficiency, the treatment liquid was heated and the temperature was raised to 6 ° C.
Although the temperature is fixed at 0 ° C., the heating temperature of the treatment liquid is not limited to this, and the treatment can be performed at the most desirable temperature determined in consideration of the capacity of production equipment, production efficiency, and the like.

As a result of a series of experiments conducted by the inventors, when a treatment solution containing periodic acid is used, for example, if the treatment temperature is in the range of 30 ° C. to 100 ° C., the industrially usable 70 nm / cm min or more dissolution rate can be achieved.

Further, the method of stirring the processing solution, the speed thereof, and the like are not limited to the above-mentioned methods, and it goes without saying that the part to be dissolved, such as ruthenium, may be moved relative to the processing solution. No.

Further, as is apparent from the results described in the present embodiment, under the condition that the liquid property of the processing solution is in the neutral region,
Not only can a high dissolution rate for ruthenium be obtained, but the burden on the apparatus of the processing liquid can be reduced, and the processing can be performed with an inexpensive and simple facility structure.

For example, in a general semiconductor device manufacturing process, a strongly alkaline chemical solution obtained by mixing ammonia water and hydrogen peroxide solution is used, and a strongly acidic hydrofluoric acid is used for etching a silicon oxide film. There are many steps to perform such a process, and an apparatus using these chemical solutions must use many expensive fluororesin members in consideration of chemical resistance. As a result, the cost of manufacturing equipment has increased significantly, and the cost of products has also increased.

However, if the pH exemplified in the present embodiment is 4 to 8 (near the neutral region) and a chemical solution having an excellent processing ability can be used, for example, a chemical solution pipe or the like is inexpensive. It is also possible to substitute a simple PVC pipe or the like, which contributes to a reduction in production equipment costs. Further, the processing operation using these processing liquids is facilitated, and greatly contributes to the improvement of the working efficiency, that is, the productivity.

Although the treatment of ruthenium has been described above, it goes without saying that these are equally effective for the treatment of osmium.

(Third Embodiment) As a third embodiment, an example of processing an electronic device will be described.

FIG. 2 is a view for schematically explaining a manufacturing process of an electronic device.

First, the concave portion 2 and the convex portion 3 are formed on one surface of the silicon substrate 1 by using, for example, a well-known processing method, for example, a wet etching method, a dry etching method, or a mechanical polishing method.

Next, a ruthenium thin film 11 was formed on the substrate 1 on which the concave portions 2 and the convex portions 3 were formed by using, for example, a well-known sputtering method. Next, an appropriate amount of a colloidal silica solution was applied thereon and dried to cover only the concave and convex portions 2 with the colloidal silica 12.

Thereafter, the substrate 1 is immersed in a 10% aqueous solution of potassium hypochlorite to remove the ruthenium film 11 of the projection 3 and form a cup-shaped ruthenium film pattern on the side and bottom surfaces of the recess 2. Was done.

As described above, in a process of manufacturing an electronic device in which a ruthenium thin film is etched to form a ruthenium thin film only in a groove provided on a substrate, a solution containing an oxygen atom-donating oxidizing agent, for example, By using a solution containing hypochlorous acid, etching can be performed within a practical time range, and as a result, an electronic device can be manufactured.

The treatment liquid is not limited to a solution containing hypochlorous acid, but may be any solution containing an oxygen atom-donating oxidizing agent such as bromic acid or periodic acid. Can be obtained.

(Fourth Embodiment) As a fourth embodiment, a treatment solution containing periodic acid prepared by using the method described in the second embodiment as a treatment solution for ruthenium (pH = 6.
2) was used. Then, the same processing as in the third embodiment was performed except for the processing liquid.

As a result, as in the case of the third embodiment,
The ruthenium film 11 formed on the convex portion 2 could be removed, and as a result, a cup-shaped ruthenium thin film 11 pattern could be formed on the side and bottom inside the concave portion 3.

As described above, in the process of manufacturing an electronic device in which the ruthenium thin film is etched to form the ruthenium thin film only in the groove provided on the substrate, the surface of the ruthenium thin film is treated with a treatment solution containing periodic acid. , The etching process can be performed within a practical time range, and as a result, an electronic device can be manufactured.

Further, since the processing solution used in this embodiment has almost neutral property (pH = 6.2), the load on the device manufacturing apparatus is reduced, and the etching process can be performed easily. Can be done.

Further, as described in the second embodiment, the processing liquid used in the above-mentioned etching treatment has a sufficiently low concentration of alkali metal ions and alkaline earth metal ions. Even when applied to the device manufacturing process, the device characteristics were not affected at all.

(Fifth Embodiment) Next, an example applied to the cleaning step of the fifth embodiment will be described with reference to FIG.

As described in the third and fourth embodiments, when the ruthenium thin film 11 is formed on the substrate 1 by the sputtering method, a large number of ruthenium fine particles 51 are formed in the film forming chamber of the apparatus. Existing. Therefore, in the substrate 1 on which the ruthenium thin film 11 is formed on one surface, a large number of ruthenium fine particles 51 adhere to the edge portion and the other surface.

At this time, in order to improve the adhesion between the substrate 1 and the ruthenium thin film 11, the film is often formed by raising the temperature of the substrate 1 in many cases. Therefore, since the ruthenium fine particles 51 attached to the edge portion and the other surface of the substrate 1 are attached relatively firmly, it is difficult to remove them by a cleaning method using pure water which is often used.

When the substrate 1 on which the ruthenium fine particles 51 are adhered as described above is directly transported to a device for performing the next processing, the inside of the device is contaminated with the ruthenium fine particles 51, and finally the device characteristics are reduced. Is expected to have a significant effect on Therefore, it is considered necessary to remove the ruthenium fine particles 51 also in the manufacturing process.

Then, as one example, the amount of the ruthenium fine particles 51 adhering to the substrate 1 was examined.

In the third embodiment, the concentration of ruthenium present on the surface (back surface) of the substrate 1 opposite to the surface on which the ruthenium thin film 11 was formed was measured using a well-known total reflection X-ray fluorescence analysis method. However, the number of the fine particles is 2 × 10 ¹⁸ at
oms / m ² .

Then, a 50% orthoperiodic acid aqueous solution was supplied only to the back surface of the substrate 1 so that the surface of the substrate 1 was covered with, for example, a protective film, and the cleaning treatment was performed for about 2 minutes. It was confirmed that it was reduced to 2 × 10 ¹⁵ atoms / m ² or less.

As described above, not only the etching of the noble metal thin film but also the removal of the noble metal fine particles adhering to the substrate, the substrate to which the solution containing the oxygen atom-donating oxidizing agent is to be removed is attached. It can be performed effectively by supplying it to the surface.

(Sixth Embodiment) As a sixth embodiment, a processing solution containing periodic acid (pH = 6.2) prepared by the method of the second embodiment was used as the processing solution. The same cleaning process as in the fifth embodiment was performed.

As a result, although the initial concentration of the ruthenium fine particles was 2 × 10 ¹⁸ atoms / m ² , the concentration was reduced to 2 × 10 ¹⁵ atoms / m ² or less when the above-described cleaning treatment was performed. I confirmed that.

In this embodiment, since the processing solution has almost neutral property (pH = 6.2), the load on the cleaning apparatus is greatly reduced. Further, the processing work is facilitated, and the work efficiency is improved.

(Seventh Embodiment) Next, a case where osmium is used will be described as a seventh embodiment.

In the present embodiment, the noble metal to be treated is osmium, and when this osmium metal is also oxidized, it becomes osmium tetroxide (OsO ₄ ) via a reaction similar to that of ruthenium metal, indicating solubility. Will be.

As one example, a substrate whose surface is contaminated with fine particles of osmium metal was cleaned by the method described in the third embodiment. As a result, the concentration of osmium fine particles existing on the substrate before washing was 5 × 10 ¹⁸ atoms / m ² , but about 5 minutes using an aqueous solution of about 1 mol / L potassium permanganate adjusted to pH = 6. After washing, the concentration of the fine particles was reduced to 3 × 10 ¹⁵ atoms / m ² .

As described above, even in the case of osmium metal, etching or cleaning can be performed by using an oxygen atom donating treatment solution.

[0094]

By using the processing fluid according to the present invention, it has become possible to etch and dissolve metal solids which have been difficult in the past within a practical time range.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the behavior of an oxidizing agent that releases oxygen atoms and an oxidizing agent that does not release oxygen atoms.

FIG. 2 is a diagram for explaining an etching process of a ruthenium thin film.

FIG. 3 is a diagram for explaining a cleaning process of ruthenium fine particles.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... concave part, 3 ... convex part, 11 ... ruthenium thin film, 12 ... colloidal silica solution, 51 ... ruthenium fine particles, 101 ... oxygen atom, 102 ... iodine atom, 104
... ruthenium atom, 111 ... ruthenium tetroxide molecule, 1
12 ... iodate ion, 113 ... metaperiodate ion.

Continuing from the front page (72) Inventor Confectionery Mieko 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside of Hitachi, Ltd. Production Technology Research Institute (72) Inventor Takuya Nise 5-2-1, Josuihoncho, Kodaira-shi, Tokyo No. F-term in Hitachi ULSI Systems, Ltd. (reference) 3B201 AA03 AB01 BB02 BB92 BB96 4K057 WA10 WB01 WC10 WE02 WE05 WE08 WE09 WE11 WE23 WE25 WG02 WK10 WM03 WN01 5F043 AA26 BB10 DD

Claims (27)

[Claims] 1. A processing method for performing an etching process on a solid surface by supplying a processing solution containing an oxidizing agent to the surface of the solid, wherein the oxidizing agent provides oxygen atoms to the surface of the solid, and A method for treating a solid surface, wherein the oxidation-reduction potential of the oxidizing agent is higher than the oxidation-reduction potential of the solid. 2. The method for treating a solid surface according to claim 1, wherein the solid comprises at least ruthenium or osmium. 3. The treatment liquid according to claim 1, wherein the treatment liquid is at least hypochlorite ion, chlorite ion, chlorate ion, perchlorate ion,
Hypobromite ion, bromite ion, bromate ion, perbromate ion, hypoiodite ion, iodate ion, iodate ion, permanganate ion, chromate ion, dichromate ion, nitric acid ion 2. The method for treating a solid surface according to claim 1, wherein the treatment liquid comprises one of ions and nitrite ions, and the treatment liquid is supplied to the solid surface. 4. The method for treating a solid surface according to claim 1, wherein the treatment liquid contains periodic acid, and the treatment liquid is supplied to the solid surface. 5. The method for treating a solid surface according to claim 4, wherein the pH of the treatment solution containing periodic acid is 2 to 10, and the treatment solution is supplied to the solid surface. 6. The method for treating a solid surface according to claim 4, wherein the pH of the treatment solution containing periodic acid is 4 or more and 8 or less, and the treatment solution is supplied to the solid surface. 7. The solid surface treatment according to claim 4, wherein the concentration range of the treatment solution containing periodic acid is 0.01 mol / L or more, and the treatment solution is supplied to the solid surface. Method. 8. The treatment solution containing periodic acid is a monovalent anion (IO ₄ ^- or H ₄ IO ₆₎ composed of + 7-valent iodine.
^- ), And the concentration range of the anion is 0.01 mol / L.
The method for treating a solid surface according to claim 4, wherein the treatment liquid is supplied to a solid surface. 9. A treatment liquid containing periodic acid, wherein the concentration of alkali metal ions contained in the treatment liquid is 50 pp.
m or less and the concentration of alkaline earth metal ions is 5
The method for treating a solid surface according to claim 4, wherein the amount is not more than ppm. 10. The method for treating a solid surface according to claim 4, wherein the treatment solution containing periodic acid contains at least an inorganic or organic ammonium salt. 11. A processing method for supplying a treatment liquid containing periodic acid to a solid surface to perform an etching treatment on the solid surface, wherein the temperature of the treatment liquid is 30 ° C. or more and 100 ° C. or more.
The method for treating a solid surface according to claim 4, wherein the temperature is lower than or equal to ° C. 12. The method for treating a solid surface according to claim 1, wherein the etching of the solid surface comprises forming at least a pattern on the solid surface or cleaning the solid surface. 13. A treatment liquid supplied to a solid surface to perform an etching treatment on the solid surface, comprising an oxidizing agent for donating oxygen atoms to at least the solid surface,
A processing solution, wherein the oxidation-reduction potential of the oxidizing agent is higher than the oxidation-reduction potential of the solid. 14. The treatment liquid according to claim 1, wherein said treatment liquid comprises at least hypochlorite ion, chlorite ion, chlorite ion, perchlorate ion, hypobromite ion, bromite ion, bromate ion, perbromate ion. , Hypoiodite ion, iodate ion, iodate ion, permanganate ion, chromate ion, dichromate ion, nitrate ion, or nitrite ion. Item 14. The treatment solution according to Item 13. 15. The processing liquid according to claim 13, wherein said processing liquid contains periodic acid. 16. The treatment solution containing periodic acid has a pH of 2
The treatment liquid according to claim 15, wherein the treatment liquid is not less than 10 and not more than 10. 17. The treatment solution containing periodic acid has a pH of 4
The treatment liquid according to claim 15, wherein the treatment liquid is not less than 8 and not more than 8. 18. A treatment solution containing the periodic acid,
The processing solution according to claim 15, wherein the concentration range of the periodic acid is 0.01 mol / L or more. 19. A treatment liquid containing the periodic acid,
It contains a monovalent anion (IO ₄ ⁻ or H ₄ IO ₆ ⁻ ) composed of + 7-valent iodine, and the concentration range of the anion is 0.
The amount is at least 01 mol / L.
The processing solution described in the above. 20. A treatment liquid containing the periodic acid,
The concentration of alkali metal ions contained in the treatment solution is 50 p
The treating solution according to claim 15, wherein the treating solution is not more than pm and the concentration of alkaline earth metal ion is not more than 5 ppm. 21. The processing liquid according to claim 15, wherein the processing liquid containing periodic acid contains at least an inorganic or organic ammonium salt. 22. A thin film forming step of forming a thin film above a substrate, a thin film processing step of processing at least a part of the thin film, and a cleaning step of cleaning a substrate including the thin film, wherein at least oxygen atoms are removed. Using a treatment solution containing an oxidizing agent to be provided and having a redox potential of the oxidizing agent higher than the redox potential of the thin film, at least processing of the thin film or cleaning of a substrate including the thin film is performed. Manufacturing method of electronic device. 23. The thin film contains at least ruthenium or osmium, and the treatment liquid is at least hypochlorite ion, chlorite ion, chlorate ion, perchlorate ion, hypobromite ion, bromite. Any of ion, bromate ion, perbromate ion, hypoiodite ion, iodate ion, iodate ion, permanganate ion, chromate ion, dichromate ion, nitrate ion, or nitrite ion The method of manufacturing an electronic device according to claim 22, comprising: 24. The method according to claim 22, wherein the thin film contains at least ruthenium or osmium, and at least processing of the thin film or cleaning of a substrate containing the thin film is performed using a processing solution containing periodic acid. Method of manufacturing electronic device. 25. The method according to claim 24, wherein at least processing of the thin film or cleaning of a substrate including the thin film is performed using the treatment liquid containing periodic acid and having a pH of 2 or more and 10 or less. Method of manufacturing electronic device. 26. The method according to claim 24, wherein at least processing of the thin film or cleaning of a substrate including the thin film is performed using the treatment liquid containing periodic acid and having a pH of 4 to 8. Method of manufacturing electronic device. 27. The method according to claim 22, wherein the electronic device is a semiconductor element or a resistance heating element.