KR101205661B1 - Method of forming metal laminate thin film or oxide thin film using supercritical fluid or subcritical fluid, and film forming apparatus therefor - Google Patents

Abstract

Provided are a method and an apparatus for forming a metal oxide thin film with or without the conductivity of a base material, and at the same time, easily forming a laminated structure of a conductive metal thin film. A metal precursor of a metal oxide to be formed and an oxidizing agent for oxidizing the metal precursor are dissolved in a supercritical fluid or a subcritical fluid, and subjected to oxidation reaction on the surface of the substrate provided in the supercritical fluid or subcritical fluid WND. To form a metal oxide thin film, and then a reducing agent and a conductive metal precursor are dissolved in a supercritical fluid or subcritical fluid WND to reduce the metal oxide thin film formed on the surface of the substrate to a metal thin film, and at the same time the reduced metal thin film phase The conductive precursor is reduced, and a thin film of conductive metal is laminated.

Pipe changers, substrate supports, fluid outlets, agitators, metal precursors

Description

TECHNICAL FIELD OF FORMING METAL LAMINATE THIN FILM OR OXIDE THIN FILM USING SUPERCRITICAL FLUID OR SUBCRITICAL FLUID, AND FILM FORMING APPARATUS THEREFOR

The present invention provides a film forming method of dissolving an oxidizing agent and a metal precursor in a supercritical fluid or subcritical fluid to form an oxide thin film on a substrate, and a method of forming a laminated thin film of metal by reducing the oxide thin film produced by the method. And a film forming apparatus for generating such a film.

In recent years, there is a need for a technique for synthesizing a substance without using a substance with a large environmental load such as an organic solvent. BACKGROUND ART Conventionally, ultrafine processing processes such as the manufacture of integrated circuits are generally performed in a dry process (vacuum process) such as in a vacuum or a lean gas atmosphere, or a plasma discharge atmosphere.

The dry process has developed so far as a very effective means from the fact that single atoms, molecules or ions thereof can be used for direct processing. However, the necessity of the vacuum maintenance equipment, the need of a plasma generation apparatus, etc. become a factor of cost increase. On the other hand, in a wet process using a liquid such as plating or washing, a large amount of waste liquid is generated, which causes environmental problems.

Supercritical fluids using CO ₂ as a medium have specific properties such as intermediate properties between liquid and gas, zero surface tension, and high ability to dissolve other substances (solvent capacity). In addition, it also has advantages such as chemical stability, low cost, harmlessness and low cost. In addition to these, by evaporation and re-liquefied CO ₂ itself, and recycling of the dissolved substance in the liquid CO ₂ it has many features that are available.

Research and development using supercritical CO ₂ are progressing mainly on the wafer cleaning process in an integrated circuit manufacturing process. For example, in the washing process, a process focusing on the solvent capacity, safety, and recyclability of supercritical CO ₂ has been developed. In addition, focusing on the fact that the surface tension is zero in supercritical CO ₂ , research and development of a micromachining process for forming a nano-level wiring is performed.

For example, although one of the main functions in the manufacture of a semiconductor device is the formation of a thin film, a rapid expansion method (Rapid Expansion of Supercritical Solution) is known as a method of forming a thin film using a supercritical fluid. D. Matthews et al. Disclose a technique for expanding supersaturated fluids in which raw materials are dissolved to form supersaturated raw materials. Moreover, the method of generating this, dissolving an oxide complex in a supercritical fluid, spraying on a heated board | substrate, and obtaining a metal oxide thin film is also disclosed (refer patent document 1 and nonpatent literature 1).

Supercritical fluids penetrate very well into nanopores because of their zero surface tension and high diffusion coefficient. If the supercritical fluid itself can be used as a reaction field for forming a thin film, it is possible to form and fill a material in an ultrafine structure, and to construct a low cost green process instead of CVD or plating.

The inventors independently developed a method of dissolving a thin film-forming raw material such as an organic metal in supercritical CO ₂ and performing a film formation reaction as it is. [E. Kondohand H. Kato, Microelectron Eng. Vol. 64 (2002) 495] has been applied to the manufacture of integrated circuit wiring, such as embedding Cu in via holes and trenches, or forming a diffusion barrier film of Cu (Japanese Patent Application Laid-Open No. 2003-17948). Manufacturing Method ", Japanese Patent Application No. 2003-17949" Method of Manufacturing Semiconductor Device "). The same method is also disclosed by Japanese Patent Laid-Open No. 2003-514115.

Patent Document 1: Japanese Patent Laid-Open No. 2003-213425

Non-Patent Document 1: J. Mater. Sci. Vol. 22, No. 1, 1918 (1987)

Patent Document 2: Japanese Patent Application No. 2003-17949

Patent Document 3: Japanese Patent Publication No. 2003-514115

However, in any of these techniques, in order to form a thin film of metal, there is a problem such that a film cannot be formed if there is no conductivity in the substrate (lower base) on which the thin film is formed. For this reason, in order to form a metal thin film as a wiring in a desired place, a processing step for imparting conductivity by sputtering on the formed film is required, which causes a problem such as a complicated process and a high cost. .

Then, the subject of this invention is providing the method of forming a metal laminated thin film, without depending on the characteristic (with or without conductivity) of the base film into which the oxide thin film or the metal laminated thin film was formed. Moreover, it is providing the compact thin film-forming apparatus.

The present invention dissolves a metal precursor of a metal oxide to be formed and an oxidizing agent for oxidizing the metal precursor in a supercritical fluid or in a subcritical fluid, and oxidizes the surface of the substrate provided in the supercritical fluid or in a subcritical fluid. It forms a thin film of the said metal oxide by reaction.

Here, the oxidizing agent is suitably O ₃ , N ₂ O or H ₂ O. When O ₃ decomposes to oxygen on the substrate surface, the atomic oxygen is liberated. This is because such atomic oxygen is unstable and reacts with the metal precursor contained in the supercritical fluid or the subcritical fluid on the substrate surface to form a metal oxide thin film. It is conceivable to use O ₂ as an oxidizing agent, but it has been found that O ₂ cannot produce a dense metal oxide. In addition, the supercritical fluid or subcritical fluid is suitably made of CO ₂ as a medium.

The oxidation reaction is suitably performed at a temperature of 400 ° C. or lower at or above the melting point of the metal precursor and in which the integrated circuit or the like is not destroyed.

Suitably the metal precursor is a Ru compound. This is usually because Cu is used as a raw material for wiring in the integrated circuit fabrication process, because Ru has an effect of preventing the diffusion of Cu. It is also suitable that the O ₃ is diluted with CO ₂ . O ₃ is because there is a risk of explosion. In addition, it is preferable that the medium of the supercritical fluid or the subcritical fluid and the medium for diluting the oxidant are homogeneous. This is because the homogeneous substance does not cause unnecessary reaction or the like by using the substances as impurities.

The present invention provides a metal precursor of a metal oxide to be formed and an oxidizing agent for oxidizing the metal precursor in a supercritical fluid or a subcritical fluid, and the surface of the substrate provided in the supercritical fluid or a subcritical fluid. A metal oxide thin film is formed by an oxidation reaction, and then a reducing agent and a conductive metal precursor are dissolved in a supercritical fluid or a subcritical fluid, and the metal oxide thin film formed on the surface of the substrate is reduced to a metal thin film, and the reduced The conductive precursor is reduced on the metal thin film to laminate a thin film of conductive metal.

The inventors have developed a technique of dissolving an organometallic complex in a supercritical fluid and causing a reduction reaction with the added H ₂ to obtain a metal thin film. However, it has been confirmed so far that when H ₂ is not added, only particles are synthesized and no thin film is formed.

The metal oxide is RuO ₂ , the metal thin film is Ru, and the conductive metal is Cu. This is usually because Cu is used as a raw material for wiring in the integrated circuit fabrication process, because Ru has an effect of preventing the diffusion of Cu.

The reducing agent is preferably in the H _2. Formation of the thin film requires that the heterogeneous reaction proceed continuously on the underlying surface and the growth surface. In order for the reaction to occur preferentially on the lower extremities, the lower extremities need to act catalytically. For the precipitation of Cu has not there is metal to help the dissociation of H _2. The inventors found in the above studies that the H ₂ reduction reaction occurs selectively only on the conductive substrate. This is because the dissociation reaction of H ₂ proceeds preferentially on the metal base.

The present invention provides a method for dissolving a metal precursor of a metal oxide to be formed and an oxidant for oxidizing the metal precursor other than oxygen in a supercritical fluid or a subcritical fluid, and an oxidation reaction on a surface of a substrate provided in the fluid. Means for forming the metal oxide thin film, means for discharging the supercritical fluid or subcritical fluid after completion of the deposition of the metal oxide thin film, and dissolving the conductive metal precursor and the reducing agent in the supercritical fluid or in the subcritical fluid. Means and a means for reducing the metal oxide thin film formed on the surface of the substrate to a metal thin film by a reduction reaction, and at the same time forming the conductive metal precursor on the surface of the metal thin film as a thin film of conductive metal by a reduction reaction. It is a laminated film-forming apparatus of a metal thin film.

The metal film lamination apparatus further includes means for adjusting the temperature of the oxidation reaction and / or the reduction reaction. This is because it is preferable to control the reaction temperature according to the kind of the metal oxide thin film to be formed or the kind of the conductive metal thin film to be formed.

According to the present invention, a metal oxide thin film can be formed regardless of whether or not there is conductivity under the ground in a supercritical fluid or in a subcritical fluid. In addition, such a metal oxide thin film can be reduced to a metal thin film to be a metal thin film, and a thin film of metal commonly used as a wiring material can be laminated on the metal thin film. According to the present invention, the step coverage and embedding properties are good, and the metal oxide thin film and the metal thin film can be formed by a simple process.

1 is a block diagram of a film forming system according to the practice of the present invention.

Figure 2 is a block diagram of a high pressure reaction vessel according to the practice of the present invention.

3 is a cross-sectional SEM photograph of a thin film obtained on a Si substrate.

4 shows the results of depth analysis by X-ray photoelectron spectroscopy.

5 is a SEM photograph of the film formed when O ₂ is used as the oxidizing agent.

6 shows a process of forming a metal laminate structure.

Fig. 7 shows the results of depth analysis by X-ray photoelectron spectroscopy of a metal laminate structure.

[Description of Symbols]

1: Example of system configuration for implementing the present invention

10: schematic diagram of high pressure reaction vessel

11: substrate

12: substrate support

13: thermocouple

14: magnetic stirrer

15: heating wire

16: fluid outlet

17: bolt

18: agitator

19: metal precursor

20: O ₃ supply cylinder

30: CO ₂ supply cylinder

40: high pressure reaction vessel

50: H ₂ supply cylinder

60: pipe changer

In the present specification, the supercritical fluid refers to a state in which a gas, such as CO ₂ , is maintained at a critical point or more, so that a difference in gas and liquid is eliminated and neither a liquid nor a gas is a fluid.

As used herein, subcritical fluid refers to the state of the fluid just below the threshold.

In the present specification, the metal precursor refers to a generic term for an organometallic compound, an organometallic complex, a metal halide, and a halogenated complex.

1 is an example of the configuration of an apparatus for practicing the present invention. The CO ₂ gas, which is the medium of the supercritical fluid, or the subcritical fluid, is liquefied in the liquefier from the CO ₂ cylinder 30 and then boosted in a boost pump and introduced into the high pressure reaction vessel 10. The pressure of the high pressure reaction vessel 10 is suitably maintained at a pressure of 7.4 Mpa or more, which is a critical point of CO ₂ , by a pressure regulating valve and a pressure gauge. The pressure may be slightly lower than the subcritical fluid of 7.4 Mpa.

Downstream of the high pressure reaction vessel 10, a valve and a pressure regulating valve are provided. After the reaction is completed in the high pressure reaction vessel 10, the supercritical fluid in the high pressure reaction vessel is introduced into the vaporization / separator 40 by controlling the opening and closing of each valve. The supercritical CO ₂ fluid is vaporized in the vaporization separator 40, and at the same time, the substance dissolved in the fluid is separated and recovered.

The high pressure reaction vessel 10 is provided with a heater and a thermocouple, whereby they can be heated and maintained at a predetermined temperature, and the temperature can be adjusted. In addition, control of supply of reaction gas is performed by the control valve (not shown) provided in the vicinity of the gas supply hole of the high pressure reaction container 10.

2 shows a configuration example of the high pressure reaction vessel 10. Although the high pressure reaction vessel 10 is suitably a stainless steel pressure-resistant and heat-resistant vessel, it is not limited to this. This high pressure reaction vessel 10 can be produced by, for example, processing an autoclave (pressure defoaming apparatus).

A substrate support 12 is installed inside the high pressure reaction vessel 10, and a substrate to form a thin film is installed on the base support 12. The thin film is formed on the surface of the substrate, but it is preferable to provide the formed surface upward.

In FIG. 2, supercritical fluid, including CO ₂ and additive gas, is supplied from the fluid outlet 16. The supercritical fluid after film formation is discharged to the vaporization / separator 40 through this pipe. In the high pressure reaction vessel 10, a metal precursor 19 of a metal oxide thin film for formation is contained. This metal precursor is stirred by the stirrer 18 rotating by the magnetic stirrer 14 and is uniformly dissolved in the supercritical fluid.

The use of the stirring device and the fixing of the substrate 11 by the substrate support 12 are for supplying the metal precursor to the substrate 11 efficiently, and if this object is achieved, it is not limited to this configuration. . In addition, since the film formation reaction occurs only on the substrate surface, the substrate may be configured to be heated only without heating the entire high-pressure reaction vessel 10.

(First embodiment)

In one embodiment of the present invention, RuO ₂ (ruthenium oxide), which is commonly used as a capacitor electrode of a dynamic random access memory, was formed as a metal oxide thin film.

The metal precursor of the metal oxide for formation is biscyclopentadienyl ruthenium (RuCp ₂ ) which is an organic ruthenium compound. This was weighed in a predetermined amount and placed in a high-pressure container with a 50 ml inner content together with the stirrer 18 shown in FIG. Next, the Si substrate cleaned with dilute hydrofluoric acid for 1 minute is provided in the support 12 of the high pressure reaction vessel 10, and the high pressure reaction vessel is covered with a stainless bolt 17 and sealed.

Next, various valves and pipe changers 60 shown in FIG. 1 are controlled, and 5% O ₃ gas diluted with CO ₂ is supplied from the O ₃ gas supply cylinder 20 to the high pressure reaction vessel 10. . The pressure at this time is 0.1 MPa. As a result, the high-pressure reaction vessel 10 is filled with 5% O ₃ gas at a pressure of 0.1 MPa. Moreover, it is suitable to make the inside of the high pressure reaction container 10 into a vacuum previously by a vacuum pump. In advance, rather than in a vacuum, CO ₂ supply device 30 to a sufficiently lower pressure than 0.1 ㎫ with CO ₂ gas by means of after the inside pressure reaction vessel (10) CO ₂ charging, 0.1 ㎫ a 5% O ₃ You may fill with pressure.

Next, each valve and piping switch 60 are controlled, the liquid CO ₂ is supplied into the high pressure reaction vessel 10 by the CO ₂ supply device 30, and the pressure of the high pressure reaction vessel is 10 Mpa. The temperature of the whole container was made into 250 degreeC by the heater 15, stirring for about 3 minutes, stirring with the stirrer 18 of the high pressure reaction vessel 10, and after closing each valve, heating with the heater 15 is performed. Stop and cool the container.

By opening the valve downstream of the high pressure reaction vessel 10, the fluid in the high pressure reaction vessel 10 is discharged through the vaporization / separator 40, and the cover of the high pressure reaction vessel 10 is opened to open the Si substrate. As a result of taking out, a glossy film-like thing was observed on the Si substrate.

Fig. 3A shows a cross-sectional SEM photograph of the thin film obtained on the Si substrate. It can be seen that a dense and uniform thin film is formed to be about 100 nm. (B) of FIG. 3 is a figure which shows typically the photograph of FIG.

4 shows the results of depth analysis by X-ray photoelectron spectroscopy. 4 is the etching time (seconds), and the vertical axis is the signal strength. In Fig. 4, the Ru and O signals are of substantially uniform intensity up to 350 seconds. On the other hand, the signal of Si is approximately zero. After 300 seconds or more, the strength of Si increases and Ru and O decay. This indicates that a RuO ₂ thin film having a constant ratio of Ru and O is formed on Si.

The film was irradiated with a four-point needle probe, and the resistivity was 200 micro ohm centimeters.

(Comparative Example 1)

As a result of using O ₂ instead of the 5% O ₃ gas diluted with CO ₂ described above, no thin film of RuO ₂ was formed on the Si substrate. Therefore, as a result of setting the temperature from 250 ° C to 350 ° C by the heater 15, a thin film containing a large amount of particles or particles was produced. An SEM photograph of the film formation obtained under such conditions is shown in Fig. 5A. This film formation is considerably weak and the specific resistance cannot be measured, and there is no electrical conductivity. FIG. 5B is a diagram schematically showing FIG. 5A.

From the above examples and comparative examples, it was found that the properties of film formation were significantly different when O ₃ was used and O ₂ was used. This is because O ₃ decomposes into O ₂ at the surface of the substrate, which then releases atomic oxygen. This is because such an atomic oxygen is unstable, and when it reaches the surface of the Si substrate, it is thought that it reacts directly with RuCp ₂ , which is a metal precursor in the supercritical fluid in the high pressure reaction vessel 10, to generate a RuO ₂ compound on the Si substrate. . It is considered that the thin film of RuO ₂ is formed only on the Si substrate because the reaction between the atomic oxygen and RuCp ₂ occurs only on the surface of the Si substrate.

On the other hand, in the case where the O ₂ as an oxidizing agent, since there is no such action, the reaction RuCp ₂ and O ₂ takes place uniformly in the supercritical fluid. As a result, it is thought that a substance which becomes granular by reacting in the supercritical fluid is formed on the Si substrate. In addition, since O ₂ is stable, the reaction between RuCp ₂ and O ₂ does not occur at the reaction temperature of 250 ° C., and it is considered that the reaction occurred at 350 ° C. for the first time.

Higher concentrations of ozone, such as liquid ozone, may be used instead of 5% O ₃ diluted with CO ₂ . However, since high concentration ozone may explode self-decomposing, it is preferable to dilute about 10% or less with a suitable dilution medium. As a dilution medium of O ₃ , an inert gas such as Ar, N ₂ , Xe or CF ₄ can be used. Here, when the medium of the supercritical fluid and the dilution medium are made of the same material, there is an advantage that they do not become impurities and do not affect the critical point of the supercritical fluid of the high pressure reaction vessel.

O ₂ may also be mixed in the dilute O ₃ gas, but as shown in the comparative example, since the temperature of the reaction using O ₂ as an oxidant is high, when the film formation temperature is selected low, an oxide thin film may be formed using only O ₃ as the oxidant. Can be.

The medium of the supercritical fluid is CO ₂ , but inert gases such as Ar, N ₂ and Xe, halogen gases such as CF ₄ , CHF ₃ and Cl ₄ , NH ₃ , CH ₃ OH, H ₂ O and the like. Polar gas of can be used. However, especially in the case where a supercritical medium is not used as a reaction material, CO ₂ is preferable in view of safety, low environmental load, cost and solvent performance. Although the reaction pressure is 10 to ㎫, good critical point of the medium is at least (CO ₂ is 7.4 ㎫), if the power (the solvent ability) to dissolve the raw materials does not matter ah any critical conditions. In the case of CO ₂ , in order to exhibit solvent performance, the pressure is preferably 6 MPa or more, and needs to be determined experimentally.

Although reaction temperature was 250 degreeC, this temperature needs to determine the optimal value suitably according to implementation. In the present example, the melting point of RuCp ₂ (about 100 ° C.) was set as the lower limit, and the process tolerance temperature of the integrated circuit wiring was set to 400 ° C. as the upper limit.

The amounts of RuCp ₂ and O ₃ were determined as follows. First, the volume of the vessel is 50 ml, and since 0.1% MPa of 5% O ₃ was introduced at room temperature, the number of moles of O ₃ was 2.0 mMol (millimolar). Consider the reaction formally, RuCp ₂ + 2O ₃ → RuO ₂ + 2O ₂ + 2Cp, and the required RuCp ₂ is 1.0 mMol, or 230 mg. Based on this amount was determined experimentally. In this example, good results were obtained at 50 mg.

Although the metal compound was set to RuCp ₂ , organic Ru compounds such as Ru (CpMe) ₂ , Ru (C ₅ HF ₆ O ₂ ) ₂ , Ru (C ₁₁ H ₁₉ O ₂ ) ₃ , and oxygen-containing Ru complexes and the like can be used.

The present invention is not limited to the production of RuO ₂ , and the chemical composition is not limited. Examples of the metal oxides include titanium oxide, zinc oxide, bismuth oxide, copper oxide, tantalum oxide, aluminum oxide, tin oxide, antimony oxide, indium oxide, lithium oxide, Si oxide, Mg oxide, lead oxide, and composites composed of them. Oxides, for example, lead zirconate titanate [Pb (Zr, Ti) O ₃ , PZT], YBa ₂ Cu ₃ O ₇ (YBCO) and the like, and various high dielectric constants, ferroelectrics, and superconductor oxides.

At the time of manufacture of a composite oxide, a raw material compound can be mixed previously. As a raw material, a metal halide, an organic metal, a metal complex, an oxygen-containing organometallic compound, a complex, a halogen-containing organometallic compound, or the like can be used. For example, TaBr ₅ , TaCl ₅ , (C ₅ H ₅ ) ₂ TaH ₃ , [(CH ₃ ) ₂ N] ₅ Ta, Ta (OC ₂ H ₅ ) ₅ , Ta (i-OC ₃ H ₇ ) ₅ , Ta (OCH ₃ ) _5, etc. Most of those known as CVD raw materials are also available.

(Second Embodiment)

Next, using the conductive metal oxide thin film formed into a film in Example 1, the film-forming which laminated the conductive metal was produced.

In this embodiment, Si is used as a non-conductive material as a base for forming a thin film. However, an organic thin film such as polyimide or polytetrafluoroethylene (PTFE), an oxide thin film such as SiO ₂ or Al ₂ O ₃ , or a semiconductor such as Si may be used.

First, RuO ₂ which is a conductive metal oxide was formed by the above-described process. The oxidant used at this time is not limited to O ₃ , and N ₂ O, H ₂ O, or the like may be used. However, of course, when O _{3 is used} , a thin film of low resistance can be formed at low temperature. The conditions for forming RuO ₂ were as described above, but the film formation time was shortened to obtain a 50 nm thin film.

After forming a thin film of RuO ₂ , the high pressure reaction vessel 10 is opened once, and then charged with 100% H ₂ gas, 0.1 Mpa. A Cu by a reduction reaction by a not oxide RuO ₂ was formed on a 300 ㎚ RuO _2. Although the order of film-forming of Cu is basically the same as the process of 1st Example, the following point differs.

First, 1) Cu was selected as a metal of the conductive metal thin film for the purpose of formation. As a precursor of Cu, 350 mg of Cu (C ₅ HF ₆ O ₂ ) ₂ , which is a halogen-containing organometallic Cu, was used, and 2) 0.1 MPa of 100% H ₂ gas was added instead of 5% diluted O ₃ , which is an oxidizing agent. , 3) The reaction temperature was 230 ° C, and the 4) reaction time was 5 minutes. The 100% H ₂ gas was supplied from the H ₂ gas supply cylinder 50 shown in FIG. 1 by the control of each valve and the pipe changer 60.

In addition, as a reducing agent, or the like may be used in addition to H _{2 CH 3 OH, CH 3 COOH,} HCOOH, B 2 H 6. This reduction reaction occurred preferentially on the conductive substrate. That is, Cu is not film-forming, and only the film-forming phase do not conductive is given by the RuO ₂ not Si no conductivity.

Here, RuO _{2, which} is a conductive oxide used in this embodiment, is a substance that is easily reduced, and is reduced to a single metal by a reducing agent used in Cu film formation. As a result, a laminated structure of Cu and ruthenium was formed on the Si substrate, not a laminate of thin films of Cu and ruthenium oxide.

In other words, in this embodiment, a thin film of Ru is formed on the Si substrate, and a thin metal film of Cu is formed thereon.

Usually, when forming Cu wiring in the integrated circuit formation process, the Ru thin film is formed by sputtering and the Cu thin film is formed on it. This is because the Ru metal layer was needed as the diffusion barrier film of Cu. In addition, since Ru is much better in electrical conductivity than RuO ₂ , it is preferable that the base is Ru having good conductivity when forming a thin film wiring line of Cu because better wiring is formed.

In this embodiment, a lamination structure of a 300 nm Cu film and a 50 nm Ru was obtained by the same apparatus. Fig. 6A shows a step of forming a metal laminated structure of Ru and Cu on a Si substrate by the process shown in this embodiment. RuO ₂ was produced on the Si substrate by the process of Example 1, and then, RuO ₂ was reduced by H ₂ by the process of Example ₂ , while Cu (C ₅ HF ₆ O ₂ ) ₂ was reduced. To form a thin film of Cu.

Fig. 7 is a result of depth analysis by X-ray photoelectron spectroscopy of the metal laminate structure obtained by the present example. It turns out that Cu, Ru, and Si are laminated one by one. In addition, since Cu, Ru, and Si have different etching rates, the length of etching time does not correspond directly to a film thickness.

As the conductive base, various doping oxides such as tin oxide, antimony oxide, titanium oxide, indium oxide, copper oxide, lithium oxide and the like, and composite oxides containing them and nickel oxide doped with Li can be used. As the metal to be formed, Al may be used in addition to transition metals such as Ru, Cu, Ni, CO, Cr, Mn, Nb, and Ti.

The raw materials required for the film formation may be a metal halide, an organic metal, a metal complex, an oxygen-containing organometallic compound, a complex, a halogen-containing organometallic compound, or a complex. For example, in the case of Cu, (C ₅ H ₅ ) CuP Materials known to those skilled in the art can be used, such as (C ₂ H ₅ ) ₃ , CuCl ₂ (C ₅ H ₅ F ₆ O ₂ ) CuC ₈ H ₁₂ , Cu (hfac) TMVS.

FIG. 6B shows the formation of a metal Ru on the conductive TiN thin film and the formation of a Cu thin film on the Ru thin film using TiN instead of a Si substrate under the same conditions. A film of metal Ru was formed on the TiN thin film, and a thin film of Cu could be formed thereon. However, it was not possible to form a thin film of metal Ru directly on the Si substrate.

As described above, up to now, a conductive thin film such as Cu or Ru cannot be directly formed on a Si substrate in a supercritical fluid or a subcritical fluid. However, as illustrated in the present embodiment, for example, RuO ₂ and It was possible to form a thin film of a conductive metal by forming a thin film of the same metal oxide once and reducing it. This eliminates the necessity of forming another conductive layer in advance on the substrate to be wired by the PVD method or the CVD method, and makes it possible to make use of the supercritical film forming method.

Since the conductive metal oxide thin film and the conductive metal thin film can be formed in the supercritical fluid or in the subcritical fluid, with or without the conductivity of the substrate, a thin film having good step coverage and embedding can be formed. It can be used for the micromachining process represented by a process or MEMS.

Claims (12)

delete delete delete delete delete delete delete A metal precursor of a metal oxide to be formed and an oxidant other than oxygen oxidizing the metal precursor are dissolved in a supercritical fluid or in a subcritical fluid and oxidized on the surface of the substrate provided in the supercritical fluid or in a subcritical fluid. Reaction to form a metal oxide thin film, Next, a reducing agent and a conductive metal precursor are dissolved in a supercritical fluid or a subcritical fluid, and the metal oxide thin film formed on the surface of the substrate is reduced to a metal thin film, and the conductive precursor is reduced on the reduced metal thin film. A thin film deposition method for thin metal films, characterized in that a thin film of conductive metal is laminated. The method of claim 8, wherein the metal oxide is RuO ₂ , the metal thin film is Ru, and the conductive metal is Cu. The method of claim 8, wherein the reducing agent is H ₂ . A high pressure reaction vessel in which a substrate is provided inside and formed on the surface of the substrate by an oxidation reaction or a reduction reaction; Introducing means for introducing a medium fluid of a supercritical fluid or subcritical fluid into the high pressure reaction vessel; Oxidant supply means for supplying an oxidant to the high pressure reaction vessel during an oxidation reaction; Reducing agent supply means for supplying a reducing agent to the high pressure reaction vessel during a reduction reaction; After the oxidation reaction or the reduction reaction is completed, a super thin film or a subcritical fluid is introduced from the high-pressure reaction vessel to vaporize the metal thin film stacking apparatus including a vaporization / separator for separating and recovering the substance dissolved in the fluid. , In the high pressure reaction vessel, Dissolving a metal precursor of a metal oxide to be formed and an oxidant for oxidizing the metal precursor in a supercritical fluid or in a subcritical fluid, The metal oxide thin film is formed on the surface of the substrate provided in the fluid by an oxidation reaction, Discharging the supercritical fluid or subcritical fluid after the film formation of the metal oxide thin film is finished; The conductive metal precursor and the reducing agent are dissolved in a supercritical fluid or in a subcritical fluid, A metal oxide thin film formed on the surface of the substrate is reduced to a metal thin film by a reduction reaction, and the conductive metal precursor is formed on the surface of the metal thin film as a thin film of conductive metal by a reduction reaction. Laminated film forming apparatus. The thin film deposition apparatus of claim 11, wherein the high pressure reaction vessel further comprises a heater and a thermocouple as means for adjusting the temperature of at least one of an oxidation reaction and a reduction reaction.

Images