JP2019089267A - Method for producing rare earth hydride, hydrogen sensor and thin film transistor - Google Patents

Abstract

To provide a method for producing a rare earth hydride that can generate a rare earth hydride semiconductor even in an atmosphere at low temperature (particularly, room temperature) and low concentration hydrogen.SOLUTION: In a method for producing a rare earth hydride, a laminate film with a platinum film formed on a rare earth element film is heat-treated in an atmosphere containing hydrogen; a rare earth element in the film is hydrogenated, and it turns into a film with rare earth hydride generated therein.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing rare earth hydrides (that is, hydrides of rare earth elements), and a hydrogen sensor and a thin film transistor using the rare earth hydride.

Conventionally, switching mirrors (for example, Non-Patent Document 1, Patent Document 1 etc.) and hydrogen sensors (for example, Non-patent document 2) using metal-semiconductor transition between rare earth dihydrides and rare earth trihydrides have been studied. In addition, cold cathode tubes and the like are known as devices utilizing rare earth hydride metals (for example, Non-Patent Document 3, Patent Document 2 etc.). That is, rare earth dihydrides (for example, YH ₂ (yttrium dihydride) and the like) are metals (hereinafter referred to as “rare earth hydride metals”), and rare earth trihydrides (for example, YH ₃ (yttrium trihydride) Etc.) are called semiconductors (hereinafter, rare earth hydride semiconductors). ). A characteristic property of the rare earth hydride metal is that the difference in concentration between the hole and the electron is small (ambipolar conduction) and the difference in mobility between the two is also small, so that the hole voltage is extremely small. As a device utilizing the property of metal, for example, a spin current generating element is known (Patent Documents 3, 4 and the like).

Japanese Patent Application Publication No. 11-514107 JP 2004-91284 A Patent No. 5551912 gazette Patent No. 5601976 Unexamined-Japanese-Patent No. 2015-065282 JP, 2015-118994, A

Physical Review B vol 57 (1998) pp. 4943-4949 Mater. Trans. 48 (2007) pp. 635-636 Jpn. J. Appl. Phys. Vol 39 (2000) pp. 4933-4938 Thin Solid Films Vol. 624 (2017) pp. 175-180 J. Alloy. Com. Vol. 239 (1996) pp. 158-171

As a method of producing a rare earth hydride, for example, there is a method of heat treating a film of a rare earth element in an atmosphere containing hydrogen (Non-patent Document 3). However, since rare earth element films are extremely susceptible to oxidation, this method requires a furnace capable of being evacuated and having a high ultimate vacuum degree as a hydrogenation furnace to prevent oxidation, which is an expensive vacuum apparatus. I can only cope with it. In addition, under a low hydrogen partial pressure atmosphere (for example, a mixed gas of 3% by volume of hydrogen and 97% by volume of inert gas), the atmosphere containing hydrogen is less than the explosion limit which is easy to handle , YH ₂ ) but not a rare earth hydride semiconductor (eg, YH ₃ ). Also known is a method of heating a laminated film in which a hydrogen selective permeation film is formed on a rare earth element film under an atmosphere containing hydrogen (for example, a mixed gas atmosphere of 3% by volume of hydrogen + 97% by volume of inert gas) (Non-patent document 4 etc.). FIG. 14 shows a laminated film (Pd: 80 nm / Y: 500 nm laminated film) in which a Pd (palladium) film is formed as a hydrogen selective permeable film on a Y (yttrium) film in a mixed gas atmosphere of 3 vol% hydrogen + 97 vol% Ar It shows the ratio of YH ₂ (metal) and YH ₃ (semiconductor) formed in the Y film when heat-treated at various temperatures. From FIG. 14, metal (YH ₂ ) is formed at room temperature to 200 ° C., and semiconductor (YH ₃ ) is formed at 300 ° C. or more, but the semiconductor (YH ₃ ) is Y film even when heated to 400 ° C. It can be seen that it does not reach more than half of the Further, FIG. 15 shows a laminated film (Ni: 80 nm / Y: 500 nm laminated film) in which a Ni (nickel) film is formed as a hydrogen selective permeable film on a Y film is mixed gas atmosphere of 3% by volume of hydrogen + 97% by volume of Ar (following , “Abbreviated as“ 3 vol% H ₂ +97 vol% Ar atmosphere ”), the ratio of YH ₂ (metal) to YH ₃ (semiconductor) formed in the Y film when heat treated at various temperatures, FIG. When a laminated film (Ni / Pd: 95 nm / Y: 500 nm laminated film) in which a Ni / Pd film is formed as a hydrogen selective permeable film on a Y film is heat-treated at various temperatures in an atmosphere of 3 vol% hydrogen + 97 vol% Ar The ratio of YH ₂ (metal) and YH ₃ (semiconductor) formed in the Y film is shown. When using the Pd film to selective hydrogen permeation membrane, when used generation of YH ₃ (semiconductor) is confirmed at 115 ° C. (FIG. 15), hydrogen permselective membrane (Ni / Pd layer), _YH 3 ( It can be seen that the temperature generated by the semiconductor is further lowered (FIG. 16). However, in either case, it is difficult to form a rare earth hydride semiconductor at room temperature.

  According to the findings of the present inventors, it is expected that the mobility is high because the rare earth hydride semiconductor is polycrystalline. Therefore, it can be expected to apply a rare earth hydride semiconductor to the channel layer of a thin film transistor, and if it is possible to produce (produce) the rare earth hydride semiconductor at a lower temperature, organic light emitting diode (OLED: Organic Light Emitting) Application to a channel layer of a high mobility thin film transistor (TFT: Thin Film Transistor) in a display panel or the like utilizing an organic EL (Electro-Luminescence) element represented by Diode) can also be expected. In addition, if it is possible to generate (produce) the rare earth hydride semiconductor at a lower temperature, it is possible to easily form a film of the rare earth hydride semiconductor also on the flexible substrate.

  Therefore, the problem to be solved by the present invention is to provide a method for producing a rare earth hydride that can form a rare earth hydride semiconductor even under a low concentration (at room temperature) low concentration hydrogen atmosphere. Another object of the present invention is to provide a hydrogen sensor which can be used in a room temperature environment, and to provide a thin film transistor having a rare earth hydride semiconductor as a channel layer and a method of manufacturing the same.

  As a result of intensive studies to solve the above-mentioned problems, the inventors have found that the above-mentioned problems can be solved by adopting the following configuration.

That is, the present invention is as follows.
[1] A method for producing a rare earth hydride, comprising heat treating a laminated film in which a platinum film is formed on a rare earth element film in an atmosphere containing hydrogen.
[2] The method of the above-mentioned [1], wherein the rare earth hydride is a rare earth hydride semiconductor.
[3] The method according to the above [1] or [2], wherein the atmosphere containing hydrogen is an atmosphere containing hydrogen in an amount below the explosion limit.
[4] The method according to any one of the above [1] to [3], wherein the heat treatment temperature is room temperature.
[5] The rare earth element film is any one or more elements selected from the group consisting of Sc (scandium), Y (yttrium), Gd (gadolinium), Eu (europium) and Yb (ytterbium) The method according to any one of the above [1] to [4].
[6] A hydrogen sensor comprising a rare earth metal hydride film and a platinum film formed on the rare earth metal hydride film.
[7] A thin film transistor characterized in that the channel layer contains a rare earth hydride semiconductor.
[8] A method for producing a thin film transistor having a channel layer containing a rare earth hydride semiconductor, the method comprising the following steps A and B:
Process A: on an insulating substrate
Gate electrode,
A gate insulating film covering the gate electrode,
A rare earth element film disposed on the gate insulating film;
A source electrode and a drain electrode disposed on the rare earth element film;
The rare earth element film, a passivation film covering the source electrode and the drain electrode, and a platinum film covering the passivation film are sequentially formed.
Step B: The laminated structure obtained through Step A is heat-treated in an atmosphere containing hydrogen.
[9] Instead of step A, it has the following step C, and step B is changed to the step of heat treating the laminated structure obtained through the following step C in an atmosphere containing hydrogen, 8] The method described.
Step C: A gate electrode, a gate insulating film covering the gate electrode, and a source electrode and a drain electrode disposed on the gate insulating film are sequentially formed on an insulating substrate, and then the source on the gate insulating film is formed. An electrode, the drain electrode and a rare earth element film covering only the peripheral portion of the electrodes, and a platinum film covering the rare earth element film are sequentially formed.
[10] The method according to the above [8] or [9], wherein the atmosphere containing hydrogen is an atmosphere containing hydrogen in an amount below the explosion limit.
[11] The method according to any one of the above [8] to [10], wherein the heat treatment temperature is room temperature.

  According to the present invention, it is possible to provide a method for producing a rare earth hydride capable of producing a rare earth hydride semiconductor under a low temperature (in particular, room temperature) and a low concentration hydrogen atmosphere, in particular, a low temperature (in particular, room temperature) It is possible to provide a method for producing a rare earth hydride capable of forming a polycrystalline rare earth hydride semiconductor film in a low concentration hydrogen atmosphere.

  Also, according to the present invention, a hydrogen sensor that can be used in a room temperature environment can be provided.

  Further, according to the present invention, it is possible to provide a thin film transistor having a polycrystalline rare earth hydride semiconductor as a channel layer and a method of manufacturing the same.

FIG. 1 shows an X-ray of a Y film after treating a laminated film of Pt (20 nm) / Y (400 nm) in the example of the present invention in a 3 vol% H ₂ +97 vol% Ar atmosphere at various temperatures for 15 minutes. It is a diffraction chart. FIG. 2 is an X-ray diffraction chart of the Y film after the laminated film of Ni (20 nm) / Y (400 nm) in Comparative Example 1 is treated at various temperatures for 15 minutes in a 3 vol% H ₂ +97 vol% Ar atmosphere. It is. FIG. 3 is an X-ray diffraction chart of a Y film after treating a laminated film of Ti (20 nm) / Y (400 nm) in Comparative Example 2 for 15 minutes at various temperatures in a 3 vol% H ₂ +97 vol% Ar atmosphere. It is. FIG. 4 is an X-ray diffraction chart of the Y film after processing the laminated film of Au (20 nm) / Y (400 nm) in Comparative Example 3 in an atmosphere of 3 vol% H ₂ +97 vol% Ar at various temperatures for 15 minutes. It is. FIG. 5 is a schematic perspective view of an example of the hydrogen sensor of the present invention. 6A and 6B are a schematic plan view and a schematic cross-sectional view of another example of the hydrogen sensor of the present invention. FIG. 6 (B) shows a cross section taken along line bb in FIG. 6 (A). 7 (A) to 7 (D) are schematic cross-sectional views showing the steps of manufacturing the hydrogen sensor shown in FIGS. 6 (A) and 6 (B), and FIG. 7 (E) is a rare earth metal hydride film in the hydrogen sensor. FIG. 6 is a schematic cross-sectional view showing a state in which a rare earth hydride semiconductor film is converted. 8 (A) and 8 (B) show the final process (heat treatment process under an atmosphere containing hydrogen) and the process immediately before in the manufacturing process of an example of the thin film transistor using the rare earth hydride semiconductor in the char layer of the present invention. It is a schematic cross section showing. 9 (A) and 9 (B) are a schematic plan view and a cross-sectional view of another example of a thin film transistor using a rare earth hydride semiconductor for the char layer of the present invention. FIG. 9 (B) shows a cross section taken along line bb in FIG. 9 (A). 10 (A) to 10 (D) are schematic cross-sectional views according to process, showing the process of manufacturing the thin film transistor of FIG. 11 (A) and 11 (B) are schematic cross-sectional views according to each process showing a manufacturing process of the thin film transistor of FIG. FIG. 12 is an X-ray diffraction chart of a rare earth metal hydride film which is a yttrium hydride film mainly composed of the metal phase (YH ₂ ) in the hydrogen sensor of the embodiment of the present invention. FIG. 13 is a 30 min treatment (temperature rise time 5) of the laminated film of Pt (10 nm) / Yb (290 nm) in the thin film transistor of the example of the present invention under various atmospheres of 3 vol% H ₂ + 97 vol% Ar atmosphere. 5 is an X-ray diffraction chart of the Yb film after the FIG. 14 is transcribed from Non-Patent Document 4, and the layered film (Pd: 80 nm / Y: 500 nm stacked film) in which a Pd (palladium) film is formed as a hydrogen selective permeable film on Y film is 3% by volume H ₂ +97 vol% Ar atmosphere, a diagram showing the ratio of the generated YH ₂ (metal) and YH ₃ (semiconductor) when treated at various temperatures. FIG. 15 is transcribed from Non-Patent Document 4, and the layered film (Ni: 80 nm / Y: 500 nm stacked film) in which a Ni (nickel) film is formed as a hydrogen selective permeable film on Y film is 3% by volume H2 + 97. under vol% Ar atmosphere, a diagram showing the ratio of the generated YH 2 _(metal) and YH 3 _{(semiconductor)} when treated at various temperatures. FIG. 16 is transcribed from Non-Patent Document 4, and the layered film (Ni / Pd: 95 nm / Y: 500 nm laminated film) in which a Ni / Pd film is formed as a hydrogen selective permeable film on Y film is 3% by volume H ₂ +97 vol% Ar atmosphere, a diagram showing the ratio of the generated YH ₂ (metal) and YH ₃ (semiconductor) when treated at various temperatures.

Hereinafter, the present invention will be described in detail in line with its preferred embodiments.
1. Method for Producing a Rare Earth Hydride The method for producing a rare earth hydride of the present invention (hereinafter, also simply referred to as "the present invention method") is a laminated film in which a platinum film is formed on a rare earth element film under an atmosphere containing hydrogen. Including heat treatment.
By the heat treatment, the rare earth element film is converted into a film (hereinafter, also referred to as a “rare earth hydride film”) in which the rare earth element in the film is hydrogenated to generate a rare earth hydride.

  The “rare earth element” in the method of the present invention includes Sc (scandium), Y (yttrium) and 15 elements from La (lanthanum) of the lanthanoid series of the periodic table of the elements to Lu (lutetium), preferably Sc It is any one or more selected from the group consisting of (scandium), Y (yttrium), Gd (gadolinium), Eu (europium) and Yb (ytterbium). In addition, an alloy composed of any one or more elements selected from such an element group and another element other than the element group is also included in the “rare earth element”.

In the rare earth hydride manufactured by the method of the present invention, the “rare earth hydride semiconductor” has a resistivity of 10 ⁻³ Ω · cm or more at normal temperature. Specific examples of rare earth hydride semiconductors include ScH ₃ , YH ₃ , trihydrides of lanthanoid series elements other than Eu and Yb, EuH ₂ , YbH ₂ , YbH _2.6 , etc. ScH ₃ , YH ₃ , GdH ₃ , YbH ₂ and YbH _2.6 are preferable from the viewpoint of ease of handling and stability after hydrogenation.

  In addition, "normal temperature" in the above-mentioned "resistivity at normal temperature" is a range of 20 ° C ± 15 ° C (5 to 35 ° C) defined in JIS Z 8703.

In the “laminated film in which a platinum film is formed on a rare earth element film” in the method of the present invention, (1) an embodiment of a laminated film (platinum film / rare earth element film) in which a platinum film is formed directly on the surface of the rare earth element film. And (2) There is an aspect of a laminated film (platinum film / insulation film / rare earth element film) in which an insulation film is formed on the surface of the rare earth element film and a platinum film is formed on the surface of the insulation film. The method for manufacturing a thin film transistor according to the present invention described later utilizes the method according to the present invention (embodiment of the above (2)), and a passivation film made of Ta ₂ O ₅ described later corresponds to the insulating film mentioned here.

  In the method of the present invention, the platinum film is a "hydrogen selectively permeable film" as referred to in the above prior art documents, that is, a film having a catalytic function of selectively supplying hydrogen to the rare earth element film to combine the rare earth element and hydrogen. When the laminated film is a laminated film (Pt film / insulation film / rare earth element film) in which an insulation film is formed on the surface of a rare earth element film and a platinum film is formed on the surface of the insulation film, By the heat treatment, hydrogen is permeated to the insulating film, hydrogen is selectively supplied to the rare earth element film, and the rare earth element and hydrogen are combined.

  In the method of the present invention, the method for producing the “laminated film in which a platinum film is formed on a rare earth element film” is not particularly limited, but the rare earth element film and the platinum film are usually formed by physical vapor deposition. As a preferred embodiment, for example, after a rare earth element film is formed on an insulating substrate by a sputtering method, an electron beam (EB) evaporation method or the like, the sputtering method, an electron beam evaporation method or the like on the rare earth element film , Forms a platinum film. Note that in the case of manufacturing a stacked film in which an insulating film is formed on the surface of a rare earth element film and a platinum film is formed on the surface of the insulating film, the insulating film may be formed, for example, by sputtering after forming the rare earth element film. It is formed by CVD (chemical vapor deposition) method or the like.

  The insulating substrate is used as a support in the process of heat treatment of the laminated film in which the platinum film is formed on the rare earth element film. Therefore, as the insulating substrate, for example, a glass substrate, an alumina substrate, a silicon substrate with a thermal oxide film, or the like is used. In addition, a laminated film in which a platinum film is formed on a rare earth element film, an insulating film is formed on the surface of the rare earth element film, and a laminated film in which a platinum film is formed on the surface of the insulating film (rare earth element film / insulating film In the case of a platinum film), as the insulating substrate, those which can be used as the insulating substrate of the thin film transistor in the method of manufacturing the thin film transistor of the present invention described later are suitable. Non-alkali glass substrates, flexible substrates and the like can be used.

  In the method of the present invention, the "hydrogen-containing atmosphere" is not particularly limited as long as it is an atmosphere containing an amount of hydrogen necessary for the compound (hydrogenation) of the rare earth element with hydrogen in the rare earth element film. From the viewpoint of (safety), an atmosphere containing hydrogen in an amount equal to or less than the explosion limit is preferable, and an atmosphere consisting of a mixed gas of hydrogen and an inert gas in an amount equal to or less than the explosion limit is more preferable. As the inert gas, noble gases such as helium gas, neon gas, argon gas and the like and nitrogen can be mentioned, preferably noble gases, more preferably argon gas. The mixed gas of hydrogen and inert gas preferably has a mixing ratio of hydrogen and inert gas (hydrogen / inert gas) of 0.05 to 12% by volume / 99.95 to 88% by volume, and more preferably 1 to 3 It is volume% / 99-97 volume%.

  Further, in the method of the present invention, “heat treatment” refers to placing a laminated film in which a platinum film is formed on a rare earth element film in an atmosphere containing hydrogen set to a temperature of room temperature or higher. In addition, "room temperature" here refers to 5-35 degreeC. Therefore, when the laminated film in which the platinum film is formed on the rare earth element film is placed in an atmosphere containing hydrogen set at room temperature, the temperature of the atmosphere containing hydrogen is maintained at room temperature without using heating means In the case, heating means are not always necessary. When heat treatment is performed by setting the atmosphere containing hydrogen to a temperature higher than room temperature, a heating means is usually required.

  In the case of heat treatment at room temperature, for example, a sample (insulating substrate / rare earth element film / platinum film) is set in an annealing furnace, vacuumed (in-furnace pressure: 10 Pa or less), and hydrogen in an amount below the explosion limit. It is left for about 1 to 30 minutes while flowing a mixed gas of an inert gas (for example, a mixed gas of 3% by volume of hydrogen and 97% by volume of argon gas).

  As a specific procedure in the case of performing heat treatment at a temperature higher than room temperature, for example, if the thickness of the platinum film is less than 5 nm, the rare earth element film may not be completely covered with platinum. It is necessary to perform gas replacement carefully so that a part of is not oxidized. For example, the annealing furnace is evacuated (in-furnace pressure: 10 Pa or less), and an inert gas such as argon gas or a mixed gas of 3% by volume of hydrogen and 97% by volume of argon gas flows to perform preheating 10 to 2 After about a minute, the sample (insulating substrate / rare earth element film / platinum film) is set, vacuuming (in-furnace pressure: 0.01 Pa or less), mixing of hydrogen and inert gas in an amount below the explosion limit The heating is performed for a predetermined time while flowing a gas (for example, a mixed gas of 3% by volume of hydrogen and 97% by volume of argon gas). When the thickness of the platinum film is 5 nm or more, preheating is not necessarily required, but preheating may be performed.

  In the method of the present invention, the temperature of the heat treatment can be selected in the range of room temperature to 450 ° C. When the temperature of the heat treatment exceeds 450 ° C., formation of a rare earth hydride semiconductor phase (in particular, a semiconductor phase of rare earth trihydride) in the rare earth hydride film becomes difficult. By the heat treatment, the rare earth element in the rare earth element film is hydrogenated to form a rare earth hydride, and the heat treatment time is extended to form a rare earth hydride film in which a large number of rare earth hydride semiconductors are produced. Therefore, in the case of producing a rare earth hydride semiconductor (that is, in the case of producing a rare earth hydride film mainly composed of a rare earth hydride semiconductor), the heat treatment time is preferably 5 minutes or more, more preferably 10 to 30 minutes.

  In the method of the present invention, the thickness of the rare earth element film is not particularly limited, but is preferably 50 nm or more, more preferably 100 nm or more, and preferably 500 nm or less, more preferably 300 nm or less from the viewpoint of mass productivity (throughput). It is. The thickness of the platinum film is not particularly limited, but is preferably 0.5 nm or more, more preferably 1 nm or more, and preferably 40 nm or less, more preferably 20 nm or less. If the thickness of the platinum film is less than 5 nm, the entire surface of the rare earth element film may not be covered with a normal device (for example, a magnetron sputtering device), and if it exceeds 40 nm, the heat treatment time becomes long. , Not efficient.

The mobility of the rare earth hydride semiconductor is high, and preferably exhibits a mobility of 10 cm ² / Vs or more, more preferably 40 cm ² / Vs or more. Therefore, when the rare earth hydride film obtained by the method of the present invention is a rare earth hydride film in which a large amount of rare earth hydride semiconductor is formed, ie, a rare earth hydride semiconductor film in which the main constituent of the rare earth hydride is a rare earth hydride semiconductor The rare earth hydride semiconductor film can be used as a channel layer of a thin film transistor, and the rare earth hydride film obtained by the method of the present invention is a rare earth hydride film in which a large amount of rare earth hydride metal is generated. In the case of a rare earth hydride metal film which is a hydride metal, the rare earth hydride metal film can be used for a hydrogen sensor or a spintronics device.

The rare earth hydride semiconductor film that can be used as a channel layer of a thin film transistor is a film in which preferably 80 to 100 mol%, more preferably 99 to 100 mol% of the rare earth hydride constituting the film is a rare earth hydride semiconductor. Preferably, the rare earth metal hydride film usable for a hydrogen sensor or a spintronics device is preferably 80 to 100 mol%, more preferably 99 to 100 mol% of the rare earth metal hydride constituting the film. Certain membranes are preferred. The rare earth hydride semiconductor in the rare earth hydride semiconductor film that can be used as the channel layer of the thin film transistor is preferably ScH ₃ , YH ₃ , RH ₃ (R: element of La series excluding Eu, Yb), or YbH ₂ And / or YbH _2.6 , and the rare earth hydride metal in the rare earth hydride metal film which can be used for a hydrogen sensor or a spintronics device is preferably ScH ₂ , YH ₂ , RH ₂ (R: excluding Eu, Yb La series of elements). The composition of such rare earth hydrides is allowed to deviate from the stoichiometric composition within the composition range which is the same as the crystal structure of the stoichiometric ratio with respect to the crystal structure in the case of the stoichiometric ratio. .

2. Hydrogen Sensor The hydrogen sensor of the present invention is configured using the laminated film (rare earth hydride metal film / platinum film) in which a platinum film is formed on the rare earth hydride metal film obtained by the method of the present invention as it is.

  FIG. 5 shows an example of the hydrogen sensor according to the present invention, in which 1 is a rare earth metal hydride film, 2 is a platinum film, 3 is an insulating substrate, 4 is an electrode, 5 is a wiring, and the electrode 4 is , And the wiring 5 is connected to a constant current source voltmeter (not shown). That is, in the hydrogen sensor of the present invention, as shown in the example of the sensor 100, the electrode 4 is attached to the laminated film 7 in which the platinum film 2 is formed on the rare earth hydride metal film 1 obtained by the method of the present invention And be configured.

  As described above, the platinum membrane which is a hydrogen selective permeation membrane has a catalytic function of selectively supplying hydrogen to the rare earth element at room temperature to hydrogenate the rare earth element. Therefore, when the hydrogen sensor of the present invention is placed in an atmosphere containing hydrogen, the rare earth hydride metal (dihydride) in the rare earth hydride metal film 1 is a trihydride by the catalytic action of the platinum film. Conversion to the oxide semiconductor changes the electrical resistance and optical characteristics of the film. Therefore, the hydrogen can be detected by reading the change in the electrical resistance and / or the optical property of the film, and can be used as a sensor or the like for detecting a hydrogen gas leak in a room temperature environment. The platinum film has a catalytic function of hydrogenating a rare earth element not only at room temperature but also at temperatures exceeding room temperature, so it can be used as a sensor or the like for detecting hydrogen gas leak even in a temperature environment exceeding room temperature. it can.

  6 (A) and 6 (B) show another example of the hydrogen sensor of the present invention. 6B shows a cross section taken along the line b-b in FIG. 6A, and in FIGS. 6A and 6B, the same reference numerals as in FIG. 5 denote the same or corresponding parts.

  In the hydrogen sensor 101 of this other example, electrodes 4 having a square planar shape are disposed at four corners of the main surface of the glass substrate 3 having a square planar shape, and one corner of each of the four electrodes 4 is arranged Is formed at the center of the main surface of the glass substrate 3 so that the planar shape of the size smaller than the planar size of the glass substrate 3 is square, and the entire surface of the rare earth hydride metal film 1 is covered. Is covered with a platinum film 2. The electrode 4 is connected to a constant current source voltmeter (not shown) via a wire (not shown). Here, "square" means "showing a square in the outline", and therefore strictly the lengths of the four sides are the same and the angles of all four corners are 90 °. It is not necessary.

  7A to 7D are diagrams for explaining the manufacturing method and the sensor operation of the hydrogen sensor 101 of FIG. 6, FIGS. 7A to 7D show manufacturing steps, and FIG. 7E is a rare earth hydrogen in the hydrogen sensor. A state in which the metal hydride film is converted to the rare earth hydride semiconductor film is shown.

  The hydrogen sensor 101 is manufactured, for example, as follows. First, an insulating substrate 3 such as a non-alkali glass substrate is prepared (FIG. 7A), and a hard mask (metal mask) (not shown) having a hole of a predetermined size for electrode formation is mounted. The electrode metal is formed on the corner portion of the main surface of the insulating substrate 3 through the holes of the hard mask (metal mask) by the method, resistance heating evaporation method, EB evaporation method or the like to form the electrode 4 (FIG. 7 (B)). After formation of the electrode 4, the hard mask (metal mask) is replaced with a hard mask (metal mask) (not shown) having a hole of a predetermined size for forming a rare earth element film, electron beam evaporation, sputtering, resistance heating A rare earth element film 6 is formed on the central portion of the main surface of the glass substrate 3 by evaporation or the like so as to cover a part of the electrode 4 through the holes of the hard mask (metal mask). A platinum film 2 is formed on the surface 6 (FIG. 7 (C)). Then, when the laminated structure 8 thus obtained is placed in an atmosphere containing hydrogen for a predetermined time, the rare earth element film 6 becomes the rare earth hydride metal film 1, and the hydrogen sensor 101 is completed (FIG. 7). (D)).

  When the completed hydrogen sensor 101 is placed in an atmosphere containing hydrogen, even if the atmosphere containing hydrogen is an atmosphere at room temperature, the rare earth hydride metal film (dihydride) 1 is a rare earth hydrogen by the catalytic action of the platinum film 2 Conversion to fluoride semiconductor (dihydride) 1 'to change the electric resistance and optical properties of the film (FIG. 7E), and detecting hydrogen by reading the change in electric resistance and / or optical properties Can.

  In the hydrogen sensor of the present invention, the insulating substrate 3 is preferably a non-alkali glass substrate from the viewpoint of operational stability.

The rare earth metal hydride film 1 is preferably a YH ₂ (yttrium dihydride) film, a ScH ₂ (scandium dihydride) film, a Gd (gadolinium dihydride) film or the like from the viewpoint of operation stability. More preferred is a YH ₂ (yttrium dihydride) film.

  The material of the electrode 4 is not particularly limited, but in the case of the hydrogen sensor 100 of the example of FIG. 5, the electrode 4 is preferably an Au electrode, Ta, Au, from the viewpoint of difficulty in transmitting hydrogen to the lower surface of the electrode 4. The Au / Ta electrode etc. which formed the film in order are used. The Au / Ta electrode is more preferably an Au / Ta electrode in which Ta and Au are sequentially formed by sputtering. Although the Au / Ta electrode can also be used in the hydrogen sensor 101 in the example of FIG. 6, in the case of the hydrogen sensor 101, the electrode 4 is preferably a material with a low work function which can easily make an ohmic contact with the rare earth hydride semiconductor. Electrodes and Mg alloy electrodes are preferred. Although the rare earth element is a low work function, it is not preferable in an environment where a sensor is used, because deterioration is likely to proceed due to water or oxygen other than hydrogen.

The size of the hydrogen sensor of the present invention is not particularly limited, but generally, the planar size (the area of the insulating substrate 3) is approximately 10 to 100 mm ² . The thickness of the rare earth hydride metal film 1 is preferably about 200 to 300 nm from the viewpoint of the operating speed and durability, and the thickness of the platinum film 2 is the operating speed and protection of the rare earth element from moisture and oxygen. From the viewpoint of coexistence, about 10 to 40 nm is preferable.

  The hydrogen sensor 100 of the example of FIG. 5 has a reduced number of hard masks (metal masks) due to its structure, which is advantageous in terms of manufacturing process, and the hydrogen sensor 101 of the example of FIG. There is almost no current flowing through the platinum film at the time of measurement, which is advantageous in terms of sensitivity.

  As a preferable dimensional configuration of the hydrogen sensor 101 of the example of FIG. 6, for example, the plane of the insulating substrate 3 is a square having a side of about 3 to 10 mm, and the planes of the rare earth hydride metal film 1 and the platinum film 2 have a side of 2 to 2 A square of about 8 mm, a thickness of rare earth hydride metal film 1 of about 200 to 300 nm, a thickness of platinum film 2 of about 10 to 40 nm, and a flat surface of square electrode 4 is a square of one side of about 1 to 7 mm The thickness of about 100-400 mm is mentioned.

  It is preferable that the length of one side of the square of the electrode 4 having a square plane is 1 mm or more. With such a size, it is possible to form an electrode using the above-mentioned hard mask (metal mask), and it becomes unnecessary to apply a resist for electrode formation and a resist patterning step, and the manufacturing process can be simplified. .

3. Thin film transistors The mobility of rare earth hydride semiconductors is expected to be generally high, and when calculated from the numerical values described in Non-Patent Document 5, for example, the mobility at room temperature of bulk polycrystalline YH ₃ indicates that the carrier concentration is 1.9 × In the case of 10 ¹⁹ cm ⁻³ , it is about 40 cm ² / Vs. This carrier concentration means that the donor concentration is very high, and is at the degenerate semiconductor level. Conversely, if it is the carrier concentration of a normal semiconductor, a mobility of 100 cm ² / Vs or more can be expected. According to the data obtained by the present inventors, the mobility of the rare earth hydride semiconductor film YH ₃ film obtained by the method of the present invention is 23 cm ² / Vs when the carrier concentration is 1 × 10 ¹⁶ cm ⁻³ . This mobility is higher than that of an IGZO film (amorphous semiconductor film composed of indium (Indium), gallium (Gallium), zinc (Zinc) and oxygen (Oxygen)), which is famous for its high mobility. high.

  In recent years, in a display panel (organic EL display panel) using an organic EL (Electro-Luminescence) element represented by an organic light emitting diode (OLED: Organic Light Emitting Diode), for reduction of power consumption and high definition, There is a demand for high mobility thin film transistors (TFTs). Further, the channel layer (semiconductor film) of the high mobility TFT needs to be formed by a room temperature process from the viewpoint of preventing thermal deterioration of the plastic sheet used as the organic EL element or the flexible insulating substrate.

  The method of the present invention can produce a polycrystalline rare earth hydride semiconductor film in a room temperature process as described above. Therefore, by utilizing the method of the present invention, a high mobility thin film transistor having a channel layer for an organic EL display panel or a liquid crystal display panel made of a rare earth hydride semiconductor film is obtained at a process temperature substantially similar to that of a conventional amorphous thin film transistor. A thin film transistor having a bottom gate structure can be manufactured. The bottom gate structure is used in a conventional amorphous thin film transistor, and by being able to manufacture a thin film transistor with a bottom gate structure, the consistency with the conventional process is also good, and there is an advantage of excellent mass productivity.

  8 (A) and 8 (B) show the final steps of the manufacturing process of an example of the thin film transistor (hereinafter also referred to as "thin film transistor of the present invention") in which the char layer is a rare earth hydride semiconductor film using the method of the present invention. A heat treatment process under an atmosphere containing hydrogen and a process just before the final process are shown. In the figure, 11 is an insulating substrate, 12 is a gate electrode, 13 is a gate insulating film, 14 is a rare earth element film, 14 'is a rare earth hydride film, 15 is a rare earth hydride semiconductor (region), and 16 is a rare earth metal hydride. (Area), 17 is a source electrode, 18 is a drain electrode, 19 is a passivation film, 20 is a platinum film, 102 is a thin film transistor, 102 a is a laminated structure, open arrows are hydrogen in an atmosphere containing hydrogen Indicates

  That is, in the thin film transistor of the present invention, as can be seen from the thin film transistor 102 (FIG. 8 (B)) of the example, the gate electrode 12 is formed on the insulating substrate 11 and the rare earth is a char layer on the gate electrode 12 It is a bottom gate thin film transistor in which a hydride semiconductor film (region) 15 is formed.

  The thin film transistor 102 (FIG. 8B) of the example is manufactured, for example, through the following step A and step B.

[Step A]
A gate electrode 12; a gate insulating film 13 covering the gate electrode 12; a rare earth element film 14 disposed on the gate insulating film 13; a source electrode 17 disposed on the rare earth element film 14; A stacked structure 102 a is fabricated by sequentially forming a drain electrode 18; a passivation film 19 covering the rare earth element film 14, the source electrode 17 and the drain electrode 18; and a platinum film 20 covering the passivation film 19.

  As the insulating substrate 11, non-alkali glass substrate, quartz glass substrate, plastic sheet (for example, polymethyl methacrylate, polyacrylate, polycarbonate, polystyrene, polyethylene sulfide, polyether sulfone, polyolefin, polyethylene terephthalate, polyethylene naphthalate, cycloolefin At least one synthetic resin selected from the group consisting of polymers, polyether sulfone, polyvinyl fluoride, ethylene-tetrafluoroethylene copolymer, weather-resistant polypropylene, transparent polyimide, fluorine-based polymer and cyclic olefin polymer Sheets formed, etc.), glass fiber reinforced acrylic resin sheets, glass fiber reinforced polycarbonate sheets, etc. can be used, but limited thereto It is not.

  For the gate electrode 12, the source electrode 17 and the drain electrode 18, silver (Ag), copper (Cu), cobalt (Co), tantalum (Ta), molybdenum (Mo), chromium (Cr), aluminum (Al), nickel Metals such as (Ni), tungsten (W), platinum (Pt), and titanium (Ti) can be used. However, it is desirable that the source electrode 17 and the drain electrode 18 have a low work function in terms of the ease of obtaining an ohmic contact, and from such a viewpoint, tantalum (Ta) and aluminum (Al) are preferable. These electrodes can be formed by a vacuum evaporation method, an ion plating method, a sputtering method, a laser ablation method, a plasma CVD method, a photo CVD method, a photo CVD method, a screen printing, a letterpress printing, an ink jet method, etc. Alternatively, known general methods for forming this type of electrode can be used. The patterning of the electrode metal can be performed, for example, by forming a protective film on the pattern-formed portion using photolithography and removing an unnecessary portion by etching, but this method is not limited to this method. Known general patterning methods can be used.

The gate insulating layer 13 can be formed over the entire surface of the substrate 1 as shown in FIGS. Materials used for the gate insulating layer 13 include inorganic materials such as SiO ₂ , SiN x, SiON, Al ₂ O ₃ , Ta ₂ O ₅ , Y ₂ O ₃ , HfO ₂ , HfAlO, ZrO ₂ , TiO _2, etc .; PMMA Polyacrylates such as (polymethyl methacrylate); PVA (polyvinyl alcohol); PS (polystyrene): transparent polyimide; polyester; epoxy resin; polyvinyl phenol; polyvinyl alcohol etc., but it is not limited thereto. In order to suppress the gate leak current, the resistivity of the insulating material of the gate insulating layer 13 is preferably 10 ¹¹ Ωcm or more, and more preferably 10 ¹⁴ Ωcm or more. The gate insulating layer 13 can be formed by, for example, dry deposition such as vacuum evaporation, ion plating, sputtering, laser ablation, plasma CVD, photo CVD, hot wire CVD, spin coating, dip coating, or the like. And a wet film forming method such as a screen printing method.

  For the rare earth element film 14, any of Sc, Y, and 15 elements from lanthanide-based La to Lu of the periodic table of the elements is used. Among them, Sc, Y, Gd or Yb is preferable. The rare earth element film 14 is formed by physical vapor deposition (preferably sputtering, electron beam (EB) vapor deposition, etc.). The thickness of the rare earth element film 14 is not particularly limited, but is preferably 50 nm or more, more preferably 100 nm or more, and from the viewpoint of mass productivity, preferably 500 nm or less, more preferably 300 nm or less.

The passivation film 19 is not particularly limited, and known passivation films in thin film transistors for organic EL display panels and liquid crystal display panels can be used. For example, SiO ₂ , Si ₃ N ₄ , Al ₂ O ₃ , Ta ₂ O ₅ or the like Can be mentioned. Among them, hydrogen permeability (that is, a hydrogen selective permeation film at the time of converting (hydrogenation) a portion of the rare earth element film 14 located on the gate electrode 12 into the rare earth hydride semiconductor, which is performed in the second step described later) Ta ₂ O ₅ is preferable from the viewpoint of hydrogen permeability in which hydrogen selectively permeated through the platinum film 20 is permeated to the rare earth element film 14.

  The platinum film 20 is formed by physical vapor deposition (preferably sputtering, electron beam (EB) vapor deposition, etc.). The thickness of the platinum film 20 is not particularly limited, but is preferably 0.5 nm or more, more preferably 1 nm or more, and from the viewpoint of processing time, preferably 40 nm or less, more preferably 20 nm or less.

[Step B]
The stacked structure 102 a (FIG. 8A) obtained through the step A is heat-treated in an atmosphere containing hydrogen. By this heat treatment, the rare earth element film 14 of the stacked structure becomes the rare earth hydride film 14 ', and the portion of the rare earth hydride film 14' located on the gate electrode 17 becomes the rare earth hydride semiconductor (region) 15; A portion under the drain electrode 17 and the drain electrode 18 is a rare earth metal hydride (region) 16 to obtain a thin film transistor 102 having the rare earth hydride semiconductor (region) 15 of the rare earth hydride film 14 'as a channel layer (FIG. 8). (B)).

  The step B is a heat treatment of a laminated film in which a platinum film is formed on a rare earth element film in the method of the present invention under an atmosphere containing hydrogen, and detailed processing conditions, equipment (conditions), etc. are as described above. It is. Preferably, the atmosphere containing hydrogen is an atmosphere having hydrogen at or below the explosion limit (for example, a mixed gas atmosphere of 3% by volume of hydrogen and 97% by volume of argon gas), and the temperature of the heat treatment is room temperature or room temperature Even if higher than 350 ° C or less.

  FIG. 9 shows another example of the thin film transistor of the present invention, FIG. 9 (A) shows a plan view of the thin film transistor, and FIG. 9 (B) shows a cross section along line bb in FIG. 9 (A). In FIGS. 9A and 9B, the same reference numerals as in FIGS. 8A and 8B denote the same or corresponding parts, 103a denotes a stacked structure, and 103 denotes a thin film transistor.

  The thin film transistor 103 of the other example has a simplified structure as compared with the thin film transistor 102 shown in FIG. 8, and is a thin film transistor which is the simplest in manufacturing process in the thin film transistor of the present invention. The thin film transistor 103 (FIGS. 9A and 9B) of the other example is manufactured through the following process C.

[Step C]
10A to 10D and FIGS. 11A and 11B show the manufacturing process of the thin film transistor 103, and the same reference numerals as in FIGS. 9A and 9B indicate the same or corresponding parts. , 21 indicates a resist.

After the gate electrode 12 made of, for example, tantalum (Ta) is formed on the insulating substrate 11 (FIG. 10A), the gate insulating film 13 made of, for example, SiO ₂ is formed (FIG. 10B) . Thereafter, the source electrode 17 and the drain electrode 18 are formed on the gate insulating film 13 (FIG. 10C). The source electrode 17 and the drain electrode 18 desirably have a low work function, and are preferably formed of, for example, tantalum (Ta), aluminum (Al), or the like. Alternatively, the source electrode 17 and the drain electrode 18 may be formed of a magnesium alloy or a rare earth element which is a material having a work function lower than that of tantalum (Ta) or aluminum (Al). Among the rare earth elements, yttrium (Y), scandium (Sc), gadolinium (Gd) and the like which are difficult to oxidize are preferable.

In the case of forming the source electrode 17 and the drain electrode 18 with a rare earth element, a step of hydrogenating a rare earth element film 14 made of ytterbium (Yb), which will be described later, comprises yttrium (Y), scandium (Sc) or gadolinium (Gd). It is necessary to select conditions under which a hydride semiconductor is not formed. For example, when an ytterbium (Yb) film is formed to 290 nm by resistance heating evaporation, platinum is deposited to a thickness of 10 nm on the top surface, and treated at 200 ° C. for 30 minutes in a 3% hydrogen + 97% argon atmosphere, a semiconductor of YbH ₂ Gadolinium (Gd) is deposited to 280 nm by sputtering, and platinum is deposited to a thickness of 20 nm on the top surface under the same atmosphere and processing conditions (ie, 3% hydrogen + 97% argon atmosphere, 200 ° C, 30 minutes) When a heat treatment is carried out, it has become of metal GdH _2. Therefore, if gadolinium (Gd) is deposited by sputtering as the source electrode 17 and drain electrode 18 and ytterbium (Yb) is deposited by evaporation as the rare earth film 14, the electrodes 17 and 18 become hydride semiconductors. It is possible to make the rare earth film 14 semiconductive under conditions that do not

  After the formation of the source electrode 17 and the drain electrode 18, a resist 21 is applied, and the resist 21 in a region where a rare earth element film for forming a channel layer is to be formed is removed. That is, the resist in the region covering the source electrode 17 and the drain electrode 18 on the gate insulating film 13 and the peripheral portion is removed. Thereafter, a rare earth element film 14 composed of ytterbium (Yb) is formed to a thickness of 200 (nm), and a platinum film 20 is formed on the rare earth element film 14 to a thickness of 10 (nm) (FIG. 10D). As a result, a rare earth element film (ytterbium (Yb) film) 14 for forming a channel layer and a platinum film 20 remain on the gate insulating film 13 to obtain a laminated structure 103a (FIG. 11A).

  After the gate electrode 12, the gate insulating film 13 covering the gate electrode 12, and the source electrode 17 and the drain electrode 18 disposed on the gate insulating film 13 are sequentially formed on the insulating substrate 11 described above, the gate insulating film 12 is formed. And sequentially forming the source electrode 17, the drain electrode 18, the rare earth element film (ytterbium film) 14 covering only those electrodes and their peripheral portions, and the platinum film 20 covering the rare earth element film (ytterbium film) 14 (Step C) corresponds to Step A in which a laminated structure having a laminated film including the rare earth element film 14 and the hydrogen selective permeation film (platinum film) 20 on the insulating substrate 11 in the manufacture of the thin film transistor 102 described above Do.

Thereafter, the layered structure body 103a obtained through the above step C is placed in an atmosphere having hydrogen at or below the explosion limit (for example, a mixed gas of 3% by volume of hydrogen and 97% by volume of argon gas) to obtain ytterbium ( The rare earth element film 14 made of Yb) becomes a semiconductor film 15 in which ytterbium (Yb) is hydrogenated to ytterbium dihydride (YbH ₂ ), and a thin film transistor 103 is obtained.

In the thin film transistor 103 of this other example, although it appears that a short occurs between the source electric 17 and the drain electrode 18 at first, the presence of the platinum film 20 causes the work function of platinum to be as large as 5.7 eV, On the other hand, since the work function of ytterbium (Yb) is as small as 2.6 eV and the work function of ytterbium dihydride (YbH ₂ ) is also small, the platinum film 20 and the ytterbium dihydride (YbH ₂ ) semiconductor film 15 have Schottky junctions. It becomes. Therefore, the influence on the operation of the thin film transistor 103 is small. In addition, the stacked structure of the platinum film 20 / ytterbium dihydride (YbH ₂ ) semiconductor film 15 is stable, and there is little concern that hydrogen is released as it is. In addition, it is considered that there is no problem even if the laminated structure of the platinum (Pt) / Ta ₂ O ₅ / ytterbium dihydride (YbH ₂ ) semiconductor film is formed, and the operation is more stable.

  EXAMPLES Hereinafter, the present invention will be more specifically described by way of examples and comparative examples, but the present invention is not limited by the following examples and the like, and is appropriately selected within the scope which can conform to the above It is of course possible to make modifications and implementation, and all of them are included in the technical scope of the present invention.

Example 1
Sample Preparation A 400 nm thick Y film and a 20 nm thick Pt film were sequentially formed on a quartz glass substrate (0.5 mm thick) to prepare a sample (Sample 1: Pt (20 nm) / Y (400 nm) / quartz glass) A laminate of substrates was produced. The film formation of the Pt film and the Ti film was performed by an EB vapor deposition apparatus.

Hydrogen treatment 1
Heat treatment was performed at room temperature, 100 ° C, 200 ° C, 325 ° C in an atmosphere containing hydrogen of 3 vol% H ₂ + 97 vol% Ar as an annealing furnace using an infrared anneal furnace capable of gas substitution after evacuation. . For heat treatment at room temperature, sample 1 was set in an annealing furnace, vacuum was applied (in-furnace pressure: 5 × 10 ⁻⁴ Pa), mixed gas of 3% by volume of hydrogen and 97% by volume of argon gas for 15 minutes Flowed. The heat treatment at 100 ° C., 200 ° C. and 325 ° C. evacuates the annealing furnace (in-furnace pressure: 5 × 10 ⁻⁴ Pa) and flows a mixed gas of 3% by volume of hydrogen and 97% by volume of argon gas After heating for 10 minutes, sample 1 is set, vacuum is applied (in-furnace pressure: 5 × 10 ^-4 Pa), furnace temperature is set to 100 ° C., 200 ° C. or 325 ° C., hydrogen 3% by volume And a mixed gas of 97% by volume of argon gas were flowed for 15 minutes.

Hydrogen treatment 2
Sample 1 is set in an annealing furnace (in-furnace temperature: room temperature), vacuumed (in-furnace pressure: 5 × 10 ^-4 Pa), mixed gas of 3% by volume of hydrogen and 97% by volume of argon gas is flowed for 90 seconds did.

(Comparative example 1)
A sample (sample 2: Ti (20 nm) / Y (400 nm) / quartz glass substrate) was prepared in the same manner as in Example 1 except that the Pt film (20 nm) was changed to a Ti film (20 nm). The same hydrogenation process as the hydrogenation processes 1 and 2 was performed.

(Comparative example 2)
A sample (sample 3: Au (20 nm) / Y (400 nm) / quartz glass substrate) was prepared in the same manner as in Example 1 except that the Pt film (20 nm) was changed to an Au film (20 nm). The same hydrogenation process as the hydrogenation processes 1 and 2 was performed.

(Comparative example 3)
A sample (sample 4: Ni (20 nm) / Y (400 nm) / quartz glass substrate) was prepared in the same manner as in Example 1 except that the Pt film (20 nm) was changed to a Ni film (20 nm). The same hydrogenation process as the hydrogenation processes 1 and 2 was performed. Sample 4 is a sample for comparison with the existing results described in Non-Patent Document 4.

  The X-ray crystal structure analysis of the Y film after hydrogenation treatment 1 and 2 of Samples 1 to 4 according to Example 1 and Comparative Examples 1 to 3 was performed using an X-ray diffraction apparatus. 1 to 4 are X-ray diffraction charts of samples 1 to 4, respectively.

Sample 4 from FIG. 2 (Ni (20nm) / Y (400nm) / quartz glass substrate), the room temperature and 100 ° C., YH ₃ film as a semiconductor phase is hardly formed, and YH ₃ film at 200 ° C. or higher formed It can be seen that the formation temperature of the semiconductor phase YH ₃ film is higher than the existing result described in Non-Patent Document 4.

  In sample 2 (Ti (20 nm) / Y (400 nm) / quartz glass substrate) of FIG. 3, the diffraction peak intensity of the Y film decreased, probably because of the diffusion of Ti.

Not only the formation of the YH ₃ film as the semiconductor phase but also the formation of the YH ₂ film as the metal phase was not confirmed in sample 3 (Au (20 nm) / Y (400 nm) / quartz glass substrate) of FIG. However, if the Y (002) plane is shifted to the low angle side and this is due to the hydrogen penetration into the Y film, it is presumed that hydrogen molecules are decomposed and transmitted on the surface.

In sample 1 (Pt (20 nm) / Y (400 nm) / quartz glass substrate) of FIG. 1 of Example 1, a YH ₃ film which is a semiconductor phase is confirmed at room temperature.

From the above results and the existing results in Non-Patent Document 4, Table 1 below compares the ease of forming a YH ₃ film that is a semiconductor phase at room temperature (RT) and 100 ° C.

(Example 2)
Hydrogen sensor First, a square of 6 mm x 6 mm in plane and a square of 2 mm square (a square of 2 mm x 2 mm in plane size) at the four corners of the non-alkali glass substrate with a thickness of 0.5 mm A / Ta electrode (Au film: 100 nm, Ta film: 50 nm) was formed. This electrode does not need to be patterned using a resist, and a hard mask (metal mask) with a hole of 2 mm square is attached to the substrate, and an Au film and a Ta film are sequentially formed by sputtering. It could be easily formed. Next, remove the hard mask (metal mask) used for this electrode formation, attach a hard mask (metal mask) with a hole of 4 mm square (square size 4 mm × 4 mm square) to the substrate, A Y film with a plane size of 4 mm × 4 mm square and a thickness of 400 nm is formed, and a 4 mm square (a plane size of 4 mm × 4 mm square) 20 nm is formed on the top surface, and Pt (20 nm) ) / Y (400 nm) was obtained. The film formation of the Y film and the Pt film was performed by continuous film formation in vacuum by an electron beam evaporation method. The Y film is hydrogenated by placing the laminated structure thus obtained in a mixed gas atmosphere (room temperature) of 3% by volume of hydrogen and 97% by volume of argon gas for 90 seconds, as shown in FIG. 6 (A) (B). The hydrogen sensor of the structure shown is completed.

FIG. 12 is an X-ray diffraction chart of the Y film after the above Pt (20 nm) / Y (400 nm) laminated film is treated for 90 seconds at room temperature in a 3 vol% H ₂ +97 vol% Ar atmosphere. It can be seen that the metal phase YH ₂ is the main component, the semiconductor phase YH ₃ is small, and the film is a rare earth hydride metal film.

(Example 3)
Thin film transistor- Yb film with a thickness of 290 nm and Pt film with a thickness of 10 nm are sequentially formed on a quartz glass substrate (0.5 mm in thickness) and a sample (sample 1: Pt (10 nm) / Yb (290 nm) / quartz glass After that, a substrate (500 nm) was prepared, using an infrared annealing furnace capable of gas substitution after evacuation with vacuum as an annealing furnace, in a mixed gas atmosphere of 3 volume% hydrogen and 97 volume% argon gas, room temperature, 100 ° C. Heat treatment was carried out at 200 ° C. and 250 ° C. Fig. 13 shows the result of X-ray diffraction of the sample 1 together with the result before treatment Ytterbium dihydride (YbH ₂ ) is obtained at room temperature, and hydrogen is released. Therefore, the rare earth hydride semiconductor film to be the channel layer of the thin film transistor can be formed on the insulating substrate at room temperature process. I could be sure.

Reference Signs List 1 rare earth metal hydride film 2 platinum film 3 insulating substrate 4 electrode 5 wiring 11 insulating substrate 12 gate electrode 13 gate insulating film 14 rare earth element film 14 'rare earth hydride film 15 rare earth hydride semiconductor (area)
16 rare earth hydride metals (area)
17 source electrode 18 drain electrode 19 passivation film 20 platinum film 100 hydrogen sensor 101 spin current conversion device 102 thin film transistor

Claims (11)

  A method for producing a rare earth hydride, comprising heat treating a laminated film in which a platinum film is formed on a rare earth element film under an atmosphere containing hydrogen.   The method of claim 1, wherein the rare earth hydride is a rare earth hydride semiconductor.   The method according to claim 1 or 2, wherein the atmosphere containing hydrogen is an atmosphere containing hydrogen in an amount below the explosion limit.   The method according to any one of claims 1 to 3, wherein the heat treatment temperature is room temperature.   The rare earth element film contains any one element or two or more elements selected from the group consisting of Sc (scandium), Y (yttrium), Gd (gadolinium), Eu (europium) and Yb (ytterbium) 5. A method according to any one of the preceding claims.   A hydrogen sensor comprising a rare earth metal hydride film and a platinum film formed on the rare earth metal hydride film.   A thin film transistor characterized in that the channel layer contains a rare earth hydride semiconductor. A method of manufacturing a thin film transistor having a channel layer containing a rare earth hydride semiconductor, the method including the following steps A and B.
Process A: on an insulating substrate
Gate electrode,
A gate insulating film covering the gate electrode,
A rare earth element film disposed on the gate insulating film;
A source electrode and a drain electrode disposed on the rare earth element film;
The rare earth element film, a passivation film covering the source electrode and the drain electrode, and a platinum film covering the passivation film are sequentially formed.
Step B: The laminated structure obtained through Step A is heat-treated in an atmosphere containing hydrogen. The method according to claim 8, wherein the step A has a step C described below, and the step B is changed to a step of heat treating the laminated structure obtained through the step C described below in an atmosphere containing hydrogen. Method.
Step C: A gate electrode, a gate insulating film covering the gate electrode, and a source electrode and a drain electrode disposed on the gate insulating film are sequentially formed on an insulating substrate, and then the source on the gate insulating film is formed. An electrode, the drain electrode and a rare earth element film covering only the peripheral portion of the electrodes, and a platinum film covering the rare earth element film are sequentially formed.   The method according to claim 8 or 9, wherein the atmosphere containing hydrogen is an atmosphere containing hydrogen in an amount below the explosion limit.   The method according to any one of claims 8 to 10, wherein the heat treatment temperature is room temperature.