Manufacturing method of thin-film solid-state secondary battery

Abstract

To provide a manufacturing method for tantalum oxide thin film such that a film thickness is substantially uniform under atmospheric pressure and film thickness control is easy and inexpensive by adjusting a supply time of mist, and a thin film solid secondary battery which comprises a tantalum oxide thin film, manufactured by the manufacturing method, on a solid electrolyte.SOLUTION: A manufacturing method for tantalum oxide thin has the processes of: preparing a raw material solution 140 by dissolving organic tantalum in an organic solvent; making the raw material solution 140 into mist in a mist generation vessel 150 to form the mist M1 of organic tantalum; introducing the mist M1 into a reaction furnace 110 with carrier gas G1, and transporting it to a surface of a substrate 40 where a tantalum oxide thin film is to be deposited; and depositing the tantalum oxide film on the substrate 40. The process of depositing the tantalum oxide film includes a process of adjusting the temperature of the substrate 40. Further, there is provided a thin film solid secondary battery comprising the tantalum oxide thin film, manufactured by the manufacturing method, on a solid electrolyte.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] In this embodiment, Manufacturing method of thin-film solid-state secondary battery Regarding. [Background technology]

[0002] A solid-state secondary battery is an example of a device that has a solid electrolyte. Thin-film solid-state secondary batteries using silicon oxide containing tin oxide have been proposed.

[0003] Additionally, the mist CVD (Chemical Vapor Deposition) method has been reported as a method for forming thin films at atmospheric pressure. In the mist CVD method, a solution containing the main components is atomized into a mist, which is then supplied to a substrate in the mist state, where it reacts on the substrate to form a film. By controlling the mist supply conditions and designing the reactor, it is possible to manufacture thin films with high uniformity. In addition, the mist CVD method has a low environmental impact and low operating costs.

[0004] On the other hand, tantalum oxide is used as a high dielectric material in capacitors and the like. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-140053 A [Patent Document 2] JP 2019-71479 A [Patent Document 3] JP 2019-33142 A Summary of the Invention [Problem to be solved by the invention]

[0006] The inventors have fabricated a thin-film solid-state secondary battery using nickel hydroxide as the positive electrode active material, titanium oxide as the negative electrode active material, and a tantalum oxide thin film fabricated by sputtering as the solid electrolyte, and have confirmed the charge / discharge operation. As a result, a problem occurred in that the tantalum oxide thin film fabricated by sputtering had high interface resistance with the nickel hydroxide positive electrode active material. In addition, the method of forming a film using a vacuum device, such as the sputtering method, is generally expensive.

[0007] In this embodiment, the film thickness is approximately uniform at atmospheric pressure, the film thickness can be easily controlled by adjusting the mist supply time, and it is inexpensive. Manufacturing method of thin-film solid-state secondary battery to provide. [Means for solving the problem]

[0008] According to one aspect of the present embodiment, the method includes the steps of preparing a raw material solution by dissolving organic tantalum in an organic solvent, misting the raw material solution in a mist generating vessel to form a mist of the organic tantalum, introducing the mist into a reactor using a carrier gas or a carrier gas and a dilution gas to transport the mist to a surface of a substrate on which a tantalum oxide thin film is to be formed, and forming the tantalum oxide thin film on the substrate, the step of forming the tantalum oxide thin film including a step of adjusting the temperature of the substrate. and transporting the mist to the surface of the substrate further comprises supplying ozone gas to the surface of the substrate to assist in the oxidation of the tantalum on the substrate. Method for manufacturing tantalum oxide thin film forming a tantalum oxide thin film as a solid electrolyte layer; A positive electrode active material layer disposed on the upper surface of the solid electrolyte layer, the positive electrode active material being nickel hydroxide (Ni(OH) 2 forming the positive electrode active material layer (22) containing A negative electrode active material layer is disposed on the lower surface of the solid electrolyte layer, facing the positive electrode active material layer, and is made of titanium oxide (TiO x ), or titanium dioxide (TiO x ) and silicon oxide (SiO x and forming the negative electrode active material layer containing the mixed layer of the above as a negative electrode active material. A method for manufacturing a thin-film solid-state secondary battery is provided. Effect of the Invention

[0011] According to this embodiment, the film thickness is approximately uniform at atmospheric pressure, and film thickness control is easy and inexpensive by adjusting the mist supply time. Manufacturing method of thin-film solid-state secondary battery can be provided. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic configuration diagram of a manufacturing apparatus applicable to a method for manufacturing a tantalum oxide thin film according to an embodiment. [Diagram 2] 3 is a process flow chart illustrating a method for manufacturing a tantalum oxide thin film according to an embodiment. [Diagram 3] 3 is a scanning electron microscope image of a cross section of a tantalum oxide thin film formed by a method for producing a tantalum oxide thin film according to an embodiment. [Figure 4] A composition ratio X (the value of X when the composition of the tantalum oxide thin film is Ta2OX) calculated by X-ray photoelectron spectroscopy analysis of a tantalum oxide thin film formed by a method for producing a tantalum oxide thin film according to an embodiment. [Diagram 5] 4 is a result of measuring the hydrogen concentration distribution in a tantalum oxide thin film formed by a tantalum oxide thin film manufacturing method according to an embodiment, by secondary ion mass spectrometry. [Figure 6A] FIG. 2 is a schematic cross-sectional structural diagram of a thin-film solid-state secondary battery having a solid electrolyte layer made of a tantalum oxide thin film formed by the method for producing a tantalum oxide thin film according to the embodiment. [Figure 6B] FIG. 2 is another schematic cross-sectional structural view of a thin-film solid-state secondary battery having a solid electrolyte layer made of a tantalum oxide thin film formed by the method for producing a tantalum oxide thin film according to the embodiment. [Figure 7] 4 is an example of discharge characteristics of a thin film solid state secondary battery having a solid electrolyte layer made of a tantalum oxide thin film formed by the method for producing a tantalum oxide thin film according to an embodiment. [Figure 8] 1 shows the film formation temperature dependence of the internal resistance of a thin-film solid-state secondary battery having a solid electrolyte layer made of a tantalum oxide thin film formed by a method for producing a tantalum oxide thin film according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Next, the present embodiment will be described with reference to the drawings. In the description of the drawings below, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions of each component is different from the actual ones. Therefore, the specific thickness and dimensions should be determined in consideration of the following description. Of course, there are also parts where the dimensional relationships and ratios are different between the drawings.

[0014] Furthermore, the embodiments shown below exemplify apparatuses and methods for embodying the technical idea, and do not specify the materials, shapes, structures, arrangements, etc. of each component. Various modifications can be made to this embodiment within the scope of the claims.

[0015] Also, in the following description, the expression tantalum oxide includes tantalum pentoxide and oxygen-deficient tantalum oxide Ta2O x (4 < x ≤ 5). Moreover, those containing hydrogen are also included.

[0016] (Apparatus for manufacturing tantalum oxide thin film) The schematic configuration of the manufacturing apparatus 101 applicable to the method for manufacturing a tantalum oxide thin film according to the present embodiment is represented as shown in FIG. 1. The manufacturing apparatus 101 for a tantalum oxide thin film according to the present embodiment includes atomizers (150, 160) and a reaction furnace 110 that vaporizes mist droplets and performs a gas-phase reaction.

[0017] The atomizers (150, 160) include a mist generation container 150 that stores a raw material solution 140 in which an organic tantalum is dissolved in an organic solvent, and a mistifier 160, and have a function of atomizing the raw material solution 140 in which the organic tantalum is dissolved to produce a solution mist. As the mistifier 160, for example, an ultrasonic generator or the like can be applied.

[0018] 1, a carrier gas G1 (first inert gas) is introduced into the sprayers (150, 160), and a solution mist (hereinafter, mist M1) is transported to the reactor 110 via a path L1 (mist path). In addition, a dilution gas G2 (second inert gas) for adjusting the flow rate of the mist M1 in the path L1 may be introduced into the path L1. For the carrier gas G1 that carries the mist M1, an inert gas that is not active in the film formation process, such as nitrogen N2 or argon Ar, is suitable. In addition, in order to set the transport speed of the mist M1 to a predetermined value or to change it appropriately, and further to change it during film formation, it is desirable to provide a flow rate adjustment means such as a flow meter or a mass flow controller that can adjust the amount of the carrier G1 introduced in the introduction path of the carrier G1.

[0019] As the dilution gas G2, an inert gas that has no activity in the film formation process, such as nitrogen N2 or argon Ar, is used, and preferably, the same type of gas as the carrier gas G1 is used.

[0020] In addition, it is desirable to provide a flow rate control means such as a flow meter or a mass flow controller in the introduction path of the dilution gas G2 so that the concentration of the mist M1 can be set to a predetermined value or changed appropriately, and even changed during film formation, thereby adjusting the amount of the dilution gas G2 introduced.

[0021] The reactor 110 is made up of an introduction section for the mist M1 and a section where the mist M1 flows over the substrate 40, and has a built-in heater plate 130 for heating the reactor up to 450° C. The substrate 40 for depositing tantalum oxide is placed in the reactor.

[0022] Mist M1 introduced from the sprayers (150, 160) is transported onto the substrate 40 placed in the reactor 110. The reactor 110 has a necessary heat capacity to be kept at a constant temperature by the heater plate 130. In addition, in FIG. 1, the exhaust gas after the mist gas-phase reaction on the surface of the substrate 40 is indicated by G3.

[0023] (Method of manufacturing tantalum oxide thin film) The method for producing a tantalum oxide thin film according to the embodiment is shown in the process flow chart of FIG.

[0024] 2, the method for producing a tantalum oxide thin film according to the embodiment includes a first step (step S1) of preparing a raw material solution 140 in which organic tantalum is dissolved in an organic solvent, a second step of producing a mist M1 of a tantalum oxide solution by turning the raw material solution 140 in which organic tantalum is dissolved in an organic solvent into a mist in a mist generating container 150, a third step (step S3) of introducing the mist M1 into a reactor 110 by a carrier gas and transporting it to the surface of a substrate 40 on which a tantalum oxide thin film is to be formed, and a fourth step (step S4) of forming a tantalum oxide thin film on the substrate 40. The fourth step includes a step of adjusting the temperature of the substrate 40 by heating the reactor 110.

[0025] The organic tantalum includes tantalum (V) alkoxide. Here, the tantalum (V) alkoxide may include tantalum (V) pentaethoxide. A tantalum (V) pentaethoxide solution (raw material solution 140) diluted with methyl alcohol is placed in a mist generating container 150 and is converted into mist by a mist generator 160. The mist M1 in the mist generating container 150 is transported to the reactor 110 using an inert gas such as nitrogen gas as a carrier gas G1. The mist M1 transported from the mist generating container 150 can also be diluted with a dilution gas G2. The reactor 110 for reaction includes an inlet and an outlet for the transported mist M1, and is otherwise sealed. The substrate 40 is heated and controlled to a predetermined temperature. The mist M1 introduced onto the substrate 40 evaporates, and a tantalum oxide thin film is formed by a gas-phase reaction on the substrate 40.

[0026] The carrier gas G1 is an inert gas such as nitrogen gas or argon gas that has no activity in the film formation process.

[0027] Similarly, the dilution gas G2 is an inert gas such as nitrogen gas, argon gas, etc. By controlling the flow rates of the carrier gas G1 and dilution gas G2, the growth rate, film quality, and uniformity of the formed film can be adjusted.

[0028] Furthermore, in order to assist the oxidation of tantalum on the substrate 40, ozone gas can be supplied to the surface of the substrate 40 in addition to the dilution gas G2. The supply of ozone gas can improve the film formation rate.

[0029] The temperature of the substrate 40 can be set in the range of 200°C to 450°C. The film properties of the formed tantalum oxide thin film can be controlled by controlling the substrate temperature. For example, a tantalum oxide thin film having ionic conductivity can be formed in the range of 200°C to 300°C. The ionic conductivity can be reduced by increasing the temperature. Ionic conduction is believed to be caused by the movement of hydrogen ions (protons).

[0030] (Example of forming a tantalum oxide thin film) The tantalum oxide thin film was formed using the manufacturing apparatus 101 shown in Fig. 1. The raw material solution 140 was prepared by diluting approximately 9.3 g (0.046 mol / l) of tantalum (V) pentaethoxide (chemical formula Ta(C2H5O)5) with 500 ml of methyl alcohol.

[0031] Since tantalum (V) pentaethoxide is prone to hydrolysis, the raw material solution 140 was prepared in a nitrogen atmosphere. The raw material solution 140 was placed in a sealed container and stirred using a magnetic stirrer.

[0032] Next, the raw material solution 140 was placed in a mist generating container 150, and a mist M1 was generated using a mist generator 160 such as an ultrasonic vibrator. The generated mist M1 was generated by mixing a carrier gas G1 at 2.5 slm (2.5×10 -3 m 3 / min), and the dilution gas G2 for flow rate adjustment was 7.5 slm (7.5 × 10 -3 m 3The substrate 40 was transported to the reactor 110 at a rate of 1000 rpm (100 / min). The reactor 110 used was placed on a heater plate 130, and the temperature of the substrate 40 was controlled within a range of approximately 200° C. to 450° C. The temperature of the substrate 40 was measured by a thermocouple placed on the back surface of the substrate 40.

[0033] (SEM image of a cross section of a tantalum oxide thin film) A scanning electron microscope (SEM) image of a cross section of the tantalum oxide thin film formed under the above conditions using the tantalum oxide thin film manufacturing method according to the embodiment is shown in Fig. 3. The substrate temperature is 250°C.

[0034] In the SEM image of the cross section of the tantalum oxide thin film, a flat film with no visible grains is formed, as shown in Figure 3. Furthermore, no clear peaks were observed in the analysis of the deposited tantalum oxide thin film by X-ray diffraction (XRD), and it is believed to be in an amorphous state.

[0035] (XPS analysis results of tantalum oxide thin film) The composition ratio X calculated by X-ray photoelectron spectroscopy (XPS) analysis of the tantalum oxide thin film formed by the manufacturing method of the tantalum oxide thin film according to the embodiment is shown in Fig. 4. In Fig. 4, the composition X near the surface of the tantalum oxide thin film calculated by XPS analysis is compared with the tantalum oxide thin film formed by sputtering and the tantalum oxide thin film formed by the sputtering method. The composition of the tantalum oxide thin film is TaO X The value of X when

[0036] The results of XPS analysis of the tantalum oxide thin film formed by this film formation method are shown in the example in Figure 4. On the other hand, the results of XPS analysis of the tantalum oxide thin film formed by the sputtering method are shown in SP1 and SP2 in Figure 4. SP1 and SP2 differ in the pressure during film formation by the sputtering method. SP1 is formed under a higher pressure than SP2.

[0037] As shown in Figure 4, the composition ratio X of the tantalum oxide thin film formed by this film formation method was 4.9 both on the outermost surface and 0.5 nm inside, confirming that the composition was almost Ta2O5. On the other hand, the tantalum oxide thin film (SP1) formed by sputtering method had a composition ratio of 5.0 on the outermost surface but dropped to 4.6 0.5 nm inside. The tantalum oxide thin film (SP2) formed by sputtering method had a composition ratio of 4.9 on the outermost surface but dropped to 4.6 0.5 nm inside.

[0038] (SIMS analysis results) The results of secondary ion mass spectrometry (SIMS) analysis of the hydrogen concentration distribution in the tantalum oxide thin film formed by the tantalum oxide thin film manufacturing method according to the embodiment are shown in FIG. 5. The substrate temperature during film formation of this sample was 250° C. In FIG. 5, the SIMS analysis result of the tantalum oxide thin film formed by this film formation method is represented by the curve of Example in FIG. 5. On the other hand, the SIMS analysis result of the tantalum oxide thin film formed by the sputtering method corresponding to FIG. 4 is represented by the curves SP1 and SP2 in FIG. 5.

[0039] As shown in the example curve of FIG. 5, the tantalum oxide thin film formed by the tantalum oxide thin film manufacturing method according to the embodiment has a hydrogen concentration of about 6×10 at a depth of about 10 nm or more from the surface. 21 atoms / cm 3 In the tantalum oxide thin film (SP1) formed by sputtering, the hydrogen concentration is about 4×10 at a depth of about 10 nm or more from the surface. 21 atoms / cm 3 In the tantalum oxide thin film (SP2) formed by sputtering, the hydrogen concentration is about 3×10 at a depth of about 10 nm or more from the surface. 21 atoms / cm 3 The following is the result.

[0040] From the above, this method can be used to form a 6×10 21 atoms / cm 3It was confirmed that a tantalum oxide thin film with a high hydrogen concentration could be formed.

[0041] (Example of thin-film solid-state secondary battery production) FIG. 6A shows a tantalum oxide thin film (TaO X The structure of a thin-film solid-state secondary battery 30 in which nickel hydroxide (Ni(OH)2) is used as the solid electrolyte layer 18 is shown. The positive electrode active material layer 22 is made of nickel hydroxide (Ni(OH)2), and the negative electrode active material layer 16S is made of titanium oxide (TiO x ), or titanium dioxide (TiO x ) and silicon oxide (SiO x ) as a negative electrode active material.

[0042] The titanium oxide (TiO2) layer 14 under the negative electrode active material layer 16S is an electron transport layer, and was formed by sputtering. Between the negative electrode current collector 12 and the titanium (TiO2) layer 14, a Ti layer 15 was formed by sputtering.

[0043] The negative electrode active material layer 16S was prepared by coating and baking a mixture of fatty acid titanium and silicone oil diluted with an organic solution.

[0044] The positive electrode active material layer 22 was prepared by dispersing nickel hydroxide (Ni(OH)2) microcrystals in an organic solution, coating, and drying.

[0045] The positive electrode current collector 26 was formed by depositing aluminum by sputtering.

[0046] The negative electrode current collector 12 was formed by depositing tungsten by sputtering.

[0047] Fig. 6B shows another structure of a thin film solid state secondary battery 30 in which a tantalum oxide thin film formed by the method for producing a tantalum oxide thin film according to the embodiment is used as a solid electrolyte layer 18. In Fig. 6B, a nickel oxide (NiO) layer 24 between a positive electrode active material layer 22 and a positive electrode current collector 26 is an electron (hole) transport layer, and was formed by sputtering. The other configurations are the same as those of the structure in Fig. 6A.

[0048] (Discharge characteristics) Fig. 7 shows the discharge characteristics of the thin-film solid-state secondary battery having the structure of Fig. 6A. The discharge voltage is from about 2 V to 1.5 V, and it is understood that the tantalum oxide thin film formed by the tantalum oxide thin film manufacturing method according to the embodiment functions as a solid electrolyte layer.

[0049] (Temperature dependence of internal resistance) Next, the internal resistance was calculated from the discharge voltage of the thin film solid state secondary battery. In other words, the difference between the open circuit voltage and the discharge voltage divided by the discharge current was used as the internal resistance. In the method for producing a tantalum oxide thin film according to the embodiment, the internal resistance of a thin film solid state secondary battery produced using a tantalum oxide thin film as a solid electrolyte layer is shown in FIG. 8 with the substrate temperature as a parameter.

[0050] When the substrate temperature is 250°C and 300°C, the internal resistance is about 1 kΩ, but at 350°C, it increases to 4 kΩ. This indicates that the ionic conductivity decreases as the substrate temperature during film formation increases. On the other hand, the internal resistance of a thin-film solid secondary battery using a tantalum oxide thin film formed by a sputtering method as the solid electrolyte layer is nearly 8 kΩ. It was found that the tantalum oxide thin film formed by the sputtering method has a high interface resistance with the positive electrode active material layer (nickel hydroxide) 22. It is considered that the tantalum oxide thin film formed by the tantalum oxide thin film manufacturing method according to the embodiment has a lower interface resistance with the positive electrode active material layer 22 and a higher ionic conductivity. The tantalum oxide thin film formed by the sputtering method is formed at the high pressure described above.

[0051] According to this embodiment, a tantalum oxide thin film having a high hydrogen (H) content and ion conductivity can be obtained by forming the film using the above-mentioned method for producing a tantalum oxide thin film.

[0052] According to the present embodiment, it is possible to provide a method for manufacturing a tantalum oxide thin film which has a substantially uniform film thickness at atmospheric pressure and which allows easy control of the film thickness by adjusting the mist spray time, and a thin film solid state secondary battery which includes, as a solid electrolyte, a tantalum oxide thin film produced by the above-mentioned manufacturing method.

[0053] A tantalum oxide thin film is formed at low film formation cost without using a sputtering method that requires a vacuum.

[0054] In addition, a thin film of tantalum oxide having low interfacial resistance with the active material is formed as a solid electrolyte for a thin film solid secondary battery having nickel hydroxide as a positive electrode active material and titanium oxide as a negative electrode active material.

[0055] In this embodiment, the electrolyte can be used as a solid electrolyte for the thin-film solid-state secondary battery.

[0056] According to another aspect of the present embodiment, a tantalum oxide thin film having a high hydrogen (H) content and ion conductivity is provided by forming the tantalum oxide thin film using the above-described method for producing a tantalum oxide thin film.

[0057] (Application of tantalum oxide thin film) The tantalum oxide thin film produced by this manufacturing method can be formed at a higher substrate temperature, for example 450°C, and then annealed with Ar, making it possible to use the film as a thin film with a high dielectric constant and little leakage.

[0058] The tantalum oxide thin film produced by this manufacturing method exhibits ionic conductivity when formed at low substrate temperatures of 200°C to 300°C, making it possible to use it as an electrochromic thin film.

[0059] In addition, the structure of the thin-film solid-state secondary battery shown as the embodiment is just one example, and the present invention can also be applied to a solid-state secondary battery that functions by the conduction of H or OH ions.

[0060] [Other embodiments] As described above, although several embodiments have been described, the descriptions and drawings forming a part of the disclosure are illustrative and should not be understood as limiting. From this disclosure, various alternative embodiments, examples and operating techniques will become apparent to those skilled in the art.

[0061] In this manner, this embodiment includes various embodiments that are not described here. [Industrial Applicability]

[0062] The secondary battery of this embodiment can be used in various consumer devices and industrial devices, and can be applied to a wide range of application fields, such as secondary batteries for communication terminals and wireless sensor networks, and secondary batteries for system applications capable of transmitting various sensor information with low power consumption. [Explanation of symbols]

[0063] 12...Negative electrode current collector 14...Titanium oxide (TiO2) layer 15...Ti layer 16S…Negative electrode active material layer 18...Solid electrolyte layer 22...Cathode active material layer 24...Nickel oxide (NiO) layer 26...Positive electrode current collector 30…Thin film solid state secondary battery 40…Substrate 101...Manufacturing equipment 110…Reactor 130…Heater plate 140...raw material solution 150…Mist generating container 160…Mist generator L1…Route M1…Mist G1…Carrier gas (first inert gas) G2: Dilution gas (second inert gas)

Claims

1. a step of forming a tantalum oxide thin film by a method for producing a tantalum oxide thin film, the method comprising the steps of: preparing a raw material solution by dissolving organic tantalum in an organic solvent; turning the raw material solution into mist in a mist generating vessel to form a mist of the organic tantalum; introducing the mist into a reaction furnace by a carrier gas or a carrier gas and a dilution gas, and transporting the mist to a surface of a substrate on which a tantalum oxide thin film is to be formed; and forming the tantalum oxide thin film on the substrate, the step of forming the tantalum oxide thin film including a step of adjusting a temperature of the substrate, and the step of transporting the mist to the surface of the substrate further including a step of supplying an ozone gas to the substrate surface to assist the oxidation of the tantalum on the substrate; preparing a positive electrode active material layer disposed on an upper surface of the solid electrolyte layer, the positive electrode active material layer including nickel hydroxide (Ni(OH)2) as a positive electrode active material; a step of preparing an anode active material layer disposed on the lower surface of the solid electrolyte layer opposite to the cathode active material layer, the anode active material layer including titanium oxide (TiO x ) or a mixture of titanium oxide (TiO x ) and silicon oxide (SiO x ) as an anode active material; The method for producing a thin-film solid-state secondary battery includes the steps of:

2. The method for producing a thin film solid state secondary battery according to claim 1 , wherein the organotantalum comprises a tantalum alkoxide.

3. The method for producing a thin film solid state secondary battery of claim 2 , wherein the tantalum alkoxide comprises tantalum pentaethoxide.

4. 2. The method for producing a thin film solid state secondary battery according to claim 1, wherein in the step of producing the positive electrode active material layer, the positive electrode active material layer is produced by dispersing nickel hydroxide microcrystals in an organic solution, applying the solution, and drying the solution.

5. 5. The method for producing a thin film solid state secondary battery according to claim 4, wherein in the step of producing the negative electrode active material layer, the negative electrode active material layer is produced by coating and baking a mixed solution in which fatty acid titanium and silicone oil are diluted with an organic solution.

6. The hydrogen concentration in the formed tantalum oxide thin film is 5×10 21 (atoms / cm 3 4. The method for producing a thin film solid state secondary battery according to claim 1, wherein the first and second electrodes are connected to each other.

7. 2. The method for producing a thin film solid state secondary battery according to claim 1, wherein the step of transporting the mist to the surface of the substrate further comprises a step of adjusting an amount of the carrier gas introduced by a first flow rate adjusting means provided in an introduction path of the carrier gas to set a transport speed of the mist to a predetermined value.

8. 3. The method for producing a thin film solid state secondary battery according to claim 1, wherein the step of transporting the mist to the surface of the substrate further comprises a step of adjusting an amount of the dilution gas introduced by a second flow rate adjusting means provided in an introduction path of the dilution gas to set a concentration of the mist to a predetermined value.

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