JP2022008633A - Manufacturing method of rare earth hydride, hydrogen sensor, and thin film transistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a rare earth hydride that produces a rare earth hydride semiconductor even at low temperature (particularly at room temperature) and in low concentration hydrogen atmosphere, and a thin film transistor in which a channel layer includes the rare earth hydride semiconductor.

SOLUTION: A manufacturing method of a rare earth hydride includes a step A of sequentially forming, on an insulating substrate 11, a gate electrode 12, a gate insulating film 13 covering the gate electrode 12, a rare earth element film 14 arranged on the gate insulating film 13, a source electrode 17 and a drain electrode 18 arranged on the rare earth element film 14, 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, and a step B of heat-treating a laminated structure obtained through the step A in an atmosphere containing hydrogen.

SELECTED DRAWING: Figure 8

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a method for producing a rare earth hydride (that is, a hydride of a rare earth element), and a hydrogen sensor and a thin film 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 a metal-semiconductor transition between a rare earth dihydride and a rare earth trihydride have been studied. Further, a cold cathode tube or the like is known as a device using a rare earth hydride metal (for example, Non-Patent Document 3, Patent Document 2, etc.). That is, the rare earth dihydride (for example, YH ₂ (yttrium dihydride), etc.) is a metal (hereinafter referred to as "rare earth hydride metal"), and the rare earth trihydride (for example, YH ₃ (yttrium trihydride)). ) Etc.) are referred to as semiconductors (hereinafter referred to as rare earth hydride semiconductors). ). The characteristic properties of rare earth hydride metals are that the hole voltage is extremely small because the difference in concentration between holes and electrons is small (bipolar conduction) and the difference in mobility between the two is small. As a device utilizing the properties of a metal, for example, a spin current generating element is known (Patent Documents 3, 4, etc.).

Special Table No. 11-514107 Gazette Japanese Unexamined Patent Publication No. 2004-911284 Japanese Patent No. 55519112 Japanese Patent No. 5601976 JP-A-2015-065282 JP-A-2015-118994

Physical Review B vol57 (1998) pp.4943-4949 Mater.Trans.48 (2007) pp.635-636 Jpn.J.Appl.Phys. Vol39 (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 for 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 the rare earth element membrane is extremely easy to oxidize, this method requires a hydrogenation furnace that can be evacuated and has a high level of ultimate vacuum in order to prevent oxidation, and is an expensive vacuum device. Can only be handled with. Further, in an atmosphere containing hydrogen, which is easy to handle and has a low hydrogen partial pressure below the explosion limit (for example, a mixed gas of 3% by volume of hydrogen and 97% by volume of an inert gas), a metal of a rare earth hydride (for example). , YH ₂ ), but not rare earth hydride semiconductors (eg, YH ₃ ). Further, a method of heating a laminated film in which a hydrogen selective permeation film is formed on a film of a rare earth element in an atmosphere containing hydrogen (for example, a mixed gas atmosphere of 3% by volume of hydrogen + 97% by volume of an inert gas) is known. (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 on a Y (ittrium) film as a hydrogen selective permeation film under a mixed gas atmosphere of 3% by volume of hydrogen + 97% by volume of Ar. YH ₂ produced in the Y film when heat-treated at various temperatures (
The ratio of (metal) and YH ₃ (semiconductor) is shown. From FIG. 14, a metal (YH ₂ ) is formed at a temperature of 200 ° C. from room temperature, and a semiconductor (YH ₃ ) is formed at a temperature of 300 ° C. or higher, but the semiconductor (YH ₃ ) is a Y film even when heated to 400 ° C. It can be seen that the ratio does not reach more than half of. Further, FIG. 15 shows a mixed gas atmosphere of 3% by volume of hydrogen + 97% by volume of Ar in a laminated film (Ni: 80 nm / Y: 500 nm laminated film) in which a Ni (nickel) film is formed as a hydrogen selective permeation film on the Y film. , "3% by volume H ₂ + 97% by volume Ar atmosphere"), the ratio of YH ₂ (metal) and YH ₃ (semiconductor) produced in the Y film when heat-treated at various temperatures, FIG. 16 shows. 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 permeation film on a Y film is heat-treated at various temperatures under an atmosphere of 3% by volume hydrogen + 97% by volume of Ar. The ratio of YH ₂ (metal) and YH ₃ (semiconductor) produced in the Y film is shown. When a Pd membrane was used for the hydrogen selective permeable membrane, the formation of YH ₃ (semiconductor) was confirmed at 115 ° C. (Fig. 15), and when (Ni / Pd membrane) was used for the hydrogen selective permeable membrane, YH ₃ (Ni / Pd membrane) was used. It can be seen that the temperature generated by the semiconductor) is further lowered (FIG. 16). However, in either case, it is difficult to produce a rare earth hydride semiconductor at room temperature.

According to the findings of the present inventors, the rare earth hydride semiconductor is expected to have high mobility because it is polycrystal. Therefore, if it can be expected that the rare earth hydride semiconductor can be applied to the channel layer of the thin film, and if the rare earth hydride semiconductor can be produced (manufactured) at a lower temperature, the organic light emission diode (OLED: Organic Light Emitting) can be expected. It is also expected to be applied to the channel layer of a high mobility thin film (TFT) in a display panel or the like using an organic EL (Electro-Luminescence) element typified by Diode). Further, if the rare earth hydride semiconductor can be produced (manufactured) at a lower temperature, a film of the rare earth hydride semiconductor can be easily formed on the flexible substrate.

Therefore, it is an object of the present invention to provide a method for producing a rare earth hydride capable of producing a rare earth hydride semiconductor even in a low concentration hydrogen atmosphere at a low temperature (particularly, room temperature). Another object of the present invention is to provide a hydrogen sensor that can be used in a room temperature environment, and further to provide a thin film having a rare earth hydride semiconductor as a channel layer and a method for manufacturing the same.

As a result of diligent research to solve the above problems, the present inventors have found that the above 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, which comprises heat-treating a laminated film having a platinum film formed on a rare earth element film in an atmosphere containing hydrogen.
[2] The method according to the above [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 an amount of hydrogen equal to or less than 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] 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) for the rare earth element film. The method according to any one of the above [1] to [4], which comprises.
[6] A hydrogen sensor having a rare earth hydride metal film and a platinum film formed on the rare earth hydride metal film.
[7] A thin film characterized in that the channel layer contains a rare earth hydride semiconductor.
[8] A method for manufacturing a thin film including a rare earth hydride semiconductor in which the channel layer includes the following steps A and B.
Step 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,
Source and drain electrodes disposed on the rare earth element film,
The rare earth element film, the passivation film covering the source electrode and the drain electrode, and the platinum film covering the passivation film are sequentially formed.
Step B: The laminated structure obtained through the step A is heat-treated in an atmosphere containing hydrogen.
[9] Instead of the step A, the following step C is provided, and the step B is changed to a 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, a source electrode and a drain electrode arranged on the gate insulating film are sequentially formed on the insulating substrate, and then the source on the gate insulating film is formed. A rare earth element film covering only the electrode, the drain electrode, and the peripheral portion of these 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 an amount of hydrogen equal to or less than 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 at a low temperature (particularly at room temperature) and in a low concentration hydrogen atmosphere, particularly at a low temperature (particularly at room temperature) and at a low concentration. It is possible to provide a method for producing a rare earth hydride capable of forming a polycrystalline rare earth hydride semiconductor film under a low concentration hydrogen atmosphere.

Further, according to the present invention, it is possible to provide a hydrogen sensor that can be used in a room temperature environment.

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

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

Hereinafter, the present invention will be described in detail according to the preferred embodiment thereof.
1. 1. Method for producing rare earth hydride The method for producing a rare earth hydride of the present invention (hereinafter, also simply abbreviated as "method of the present invention") is a laminated film in which a platinum film is formed on a rare earth element film under an atmosphere containing hydrogen. Includes heat treatment.
By such heat treatment, the rare earth element film is converted into a film in which the rare earth element in the film is hydrogenated to produce a rare earth hydride (hereinafter, also referred to as “rare earth hydride film”).

The "rare earth element" in the method of the present invention includes 15 elements from Sc (scandium), Y (yttrium) and the lanthanoid-based La (lanthanum) to Lu (lutetium) in the periodic table of elements, preferably Sc. Any one or more selected from the group consisting of (scandium), Y (yttrium), Gd (gadrinium), Eu (europium) and Yb (itterbium). Further, an alloy composed of any one or more kinds of elements selected from such an element group and an element other than the element group is also included in the "rare earth element".

In the rare earth hydride produced by the method of the present invention, the "rare earth hydride semiconductor" has a resistivity of ^10-3 Ω · cm or more at room temperature. Specific examples of rare earth hydride semiconductors include
Examples include trihydrides of lanthanoid series elements other than ScH ₃ , YH ₃ , Eu and Yb, EuH ₂ , YbH ₂ , YbH _2.6 , etc., which are easy to handle such as difficulty in oxidation and stable after hydrogenation. From the viewpoint of sex, ScH ₃ , YH ₃ , GdH ₃ , YbH ₂ , and YbH _2.6 are preferable.

The "normal temperature" in the above "resistivity at room temperature" is in the range of 20 ° C. ± 15 ° C. (5 to 35 ° C.) specified in JIS Z 8703.

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

In the method of the present invention, the platinum membrane is a "hydrogen selective permeation membrane" referred to in the above-mentioned prior art document, that is, as a membrane having a catalytic function of selectively supplying hydrogen to a rare earth element membrane to combine the rare earth element with hydrogen. If the laminated film is a laminated film (Pt film / insulating film / rare earth element film) in which an insulating film is formed on the surface of the rare earth element film and a platinum film is formed on the surface of the insulating film, the laminated film functions. By heat treatment, hydrogen is permeated through the insulating film, and hydrogen is selectively supplied to the rare earth element membrane to combine the rare earth element with hydrogen.

In the method of the present invention, the method for producing the "laminated film in which the platinum film is formed on the rare earth element film" is not particularly limited, but the rare earth element film and the platinum film are usually formed by a physical vapor deposition method. As a preferred embodiment, for example, a rare earth element film is formed on the insulating substrate by a sputtering method, an electron beam (EB) vapor deposition method, or the like, and then the rare earth element film is formed by a sputtering method, an electron beam vapor deposition method, or the like. , An embodiment of forming a platinum film. In the case of producing a laminated film in which an insulating film is formed on the surface of the rare earth element film and a platinum film is formed on the surface of the insulating film, the insulating film is used, for example, by a sputtering method after the film formation of the rare earth element film. CVD (chemical vapor deposition)
Formed by law.

The insulating substrate is used as a support in the process of heat-treating 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. Further, 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 platinum film is formed on the surface of the insulating film (rare earth element film / insulating film). / Platinum film), the insulating substrate is preferably one that can be used as an insulating substrate for a thin film in the method for manufacturing a thin film of the present invention described later, and is used, for example, for a general back plane. It is possible to use a non-alkali glass substrate, a flexible substrate, or the like.

In the method of the present invention, the "atmosphere containing hydrogen" is not particularly limited as long as it contains an amount of hydrogen required for the combination (hydrogenation) of the rare earth element with hydrogen in the rare earth element film, but the handleability is not particularly limited. 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. Examples of the inert gas include rare gases such as helium gas, neon gas, and argon gas, and nitrogen, but the inert gas is preferably a rare gas, and more preferably an argon gas. The mixed gas of hydrogen and an inert gas preferably has a mixed ratio of hydrogen and an inert gas (hydrogen / inert gas) of 0.05 to 12% by volume / 99.95 to 88% by volume, more preferably 1 to 3%. Volume% / 99-97 volume%.

Further, in the method of the present invention, "heat treatment" is to place a laminated film having a platinum film formed on a rare earth element film in an atmosphere containing hydrogen set at a temperature of room temperature or higher. The "room temperature" here means 5 to 35 ° C. 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 a heating means. In some cases, heating means is 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, evacuated (in-core pressure: 10 Pa or less), and an amount of hydrogen below the explosion limit is applied. Leave it 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 for heat treatment at a temperature higher than room temperature, for example, when the thickness of the platinum film is less than 5 nm, the rare earth element film may not be completely covered with platinum, so that the rare earth element film may not be completely covered. Careful gas replacement is required to prevent partial oxidation of the gas. For example, the annealing furnace is evacuated (pressure in the furnace: 10 Pa or less), and preheating is performed 10 to 2 while flowing an inert gas such as argon gas or a mixed gas of 3% by volume of hydrogen and 97% by volume of argon gas. After about a minute, set the sample (insulating substrate / rare earth element film / platinum film), vacuum (internal pressure: 0.01 Pa or less), and mix the amount of hydrogen and inert gas below the explosion limit. It is heated 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 always necessary, but preheating may be performed.

In the method of the present invention, the temperature of the heat treatment can be selected within the range of room temperature to 450 ° C. When the temperature of the heat treatment exceeds 450 ° C., it becomes difficult to form a rare earth hydride semiconductor phase (particularly, a rare earth hydride semiconductor phase) in the rare earth hydride film. By the heat treatment, the rare earth element in the rare earth element film is hydrogenated to generate a rare earth hydride, and the heat treatment time is lengthened to obtain a rare earth hydride film in which a large amount of rare earth hydride semiconductors are produced. Therefore, when producing a rare earth hydride semiconductor (that is, when 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 from the viewpoint of mass productivity (throughput), preferably 500 nm or less, more preferably 300 nm or less. 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 by a normal device (for example, a magnetron sputtering device), and if it exceeds 40 nm, the heat treatment time becomes long. , Inefficient.

The mobility of the rare earth hydride semiconductor is high, preferably 10 cm ² / Vs or more, and 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 semiconductors are produced, that is, a rare earth hydride semiconductor film in which the main component 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 film, 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 produced, that is, the main component of the rare earth hydride is rare earth. 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 the channel layer of the thin film is preferably a film in which 80 to 100 mol%, more preferably 99 to 100 mol% of the rare earth hydride constituting the film is a rare earth hydride semiconductor. The rare earth hydride metal film that is suitable and can be used for hydrogen sensors and spintronics devices is preferably 80 to 100 mol%, more preferably 99 to 100 mol% of the rare earth hydride metal constituting the film. Certain films are suitable. The rare earth hydride semiconductor in the rare earth hydride semiconductor film that can be used as the channel layer of the thin film is preferably ScH ₃ , YH ₃ , RH ₃ (R: La series elements excluding Eu and Yb), or YbH ₂ . And / or YbH _2.6 , the rare earth hydride metal in the rare earth hydride metal film that can be used for hydrogen sensors and spintronics devices is preferably ScH ₂ , YH ₂ , RH ₂ (R: Eu, Yb excluded). It is an element of the La series). It should be noted that the composition of the rare earth hydride 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. 2. Hydrogen sensor The hydrogen sensor of the present invention is configured by using as it is a laminated film (rare earth hydride metal film / platinum film) in which a platinum film is formed on a rare earth hydride metal film obtained by the method of the present invention.

FIG. 5 shows an example of the hydrogen sensor of the present invention. In the figure, 1 is a rare earth hydride metal film, 2 is a platinum film, 3 is an insulating substrate, 4 is an electrode, 5 is a wiring, and the electrode 4 is a wiring, respectively. , Is connected to a constant current source voltmeter (not shown) via wiring 5. That is, in the hydrogen sensor of the present invention, as shown in the sensor 100 of the example, 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. It is composed of.

As described above, the platinum film, which is a hydrogen selective permeation film, has a catalytic function of selectively supplying hydrogen to a 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 trihydride due to the catalytic action of the platinum film. Converted to a compound semiconductor, the electrical resistance and optical characteristics of the film change. Therefore, hydrogen can be detected by reading the change in electrical resistance and / or the change in optical characteristics of the film, and can be used as a sensor or the like for detecting a gas leak of hydrogen in a room temperature environment. Since the platinum film has a catalytic function of hydrogenating rare earth elements not only at room temperature but also at temperatures above room temperature, it can be used as a sensor for detecting hydrogen gas leaks even in a temperature environment above room temperature. can.

6 (A) and 6 (B) show another example of the hydrogen sensor of the present invention. 6 (B) shows a cross section in line bb in FIG. 6 (A), and in FIGS. 6 (A) and 6 (B), the same reference numerals as those in FIG. 5 indicate the same or corresponding portions.

In another example of the hydrogen sensor 101, electrodes 4 having a square planar shape are arranged at four corners of the main surface of a glass substrate 3 having a square planar shape, and one corner of each of the four electrodes 4 is arranged. A rare earth hydride metal film 1 having a square planar shape smaller than the plane size of the glass substrate 3 is formed in the center of the main surface of the glass substrate 3 so as to cover the entire surface of the rare earth hydride metal film 1. Is covered with the platinum film 2. The electrode 4 is connected to a constant current source voltmeter (not shown) via wiring (not shown). In addition, "square" here means "presenting a square in the appearance", and therefore, it means that the lengths of the four sides are exactly the same and the angles of all four corners are 90 °. Not necessarily required.

7 is a diagram for explaining the manufacturing method and sensor operation of the hydrogen sensor 101 of FIG. 6, FIGS. 7A to 7D show a manufacturing process, and FIG. 7E shows rare earth hydrogen in a hydrogen sensor. It shows a state in which a hydride metal film is converted into a rare earth hydride semiconductor film.

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. 7 (A)), a hard mask (metal mask) (not shown) having holes of a predetermined size for forming electrodes is attached, and sputtering is performed. An electrode metal is formed on the corners of the main surface of the insulating substrate 3 through the holes of the hard mask (metal mask) by a method, a resistance heating vapor deposition method, an EB vapor deposition method, or the like to form the electrode 4. (FIG. 7 (B)). After forming the electrode 4, the hard mask (metal mask) is replaced with a hard mask (metal mask) (not shown) having holes of a predetermined size for forming a rare earth element film, and an electron beam vapor deposition method, a sputtering method, and resistance heating are performed. A rare earth element film 6 is formed on the central portion of the main surface of the glass substrate 3 so as to cover a part of the electrode 4 through the holes of the hard mask (metal mask) by a vapor deposition method or the like, and further, a rare earth element film is formed. A platinum film 2 is formed on the 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, the rare earth hydride metal film (dihydride) 1 becomes rare earth hydrogen due to the catalytic action of the platinum film 2 even if the atmosphere containing hydrogen is an atmosphere at room temperature. Converting to a compound semiconductor (dihydride) 1'changes the electrical resistance and optical characteristics of the film (FIG. 7 (E)), and detecting hydrogen by reading this change in electrical resistance and / or optical characteristics. Can be done.

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 hydride metal film 1 is preferably a YH ₂ (yttrium dihydride) film, a ScH ₂ (scandium dihydride) film, a Gd (gadrinium dihydride) film, or the like, from the viewpoint of operational stability. A YH ₂ (yttrium dihydride) film is more preferred.

The material of the electrode 4 is not particularly limited, but in the case of the hydrogen sensor 100 in the example of FIG. 5, from the viewpoint that hydrogen is difficult to permeate through the lower surface of the electrode 4, the electrode 4 is preferably an Au electrode, Ta, Au. Au / Ta electrodes or the like in which the deposits are sequentially formed are used. The Au / Ta electrode is more preferably an Au / Ta electrode in which Ta and Au are sequentially formed by a sputtering method. The Au / Ta electrode can also be used in the hydrogen sensor 101 of the example of FIG. 6, but in the case of the hydrogen sensor 101, the electrode 4 is preferably a material having a low work function that makes it easy to make ohmic contact with the rare earth hydride semiconductor, and Al. Electrodes and Mg alloy electrodes are suitable. Although rare earth elements have a low work function, they are not preferable because they are easily deteriorated by water other than hydrogen, oxygen, etc. in the environment where the sensor is used.

The size of the hydrogen sensor of the present invention is not particularly limited, but generally, the plane size (area of the insulating substrate 3) is about 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 operating speed and durability, and the thickness of the platinum film 2 is the operating speed and protection of rare earth elements from moisture and oxygen. From the viewpoint of compatibility, it is preferably about 10 to 40 nm.

The hydrogen sensor 100 in the example of FIG. 5 is advantageous in terms of the manufacturing process because the number of hard masks (metal masks) is reduced due to its structure, and the hydrogen sensor 101 in the example of FIG. 6 has resistance due to its structure. There is almost no current flowing through the platinum film during measurement, which is advantageous in terms of sensitivity.

As a preferable dimensional configuration of the hydrogen sensor 101 in 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 to. A square of about 8 mm, the thickness of the rare earth hydride metal film 1 is about 200 to 300 nm, the thickness of the platinum film 2 is about 10 to 40 nm, and the flat surface of the square electrode 4 is a square with a side of about 1 to 7 mm, the electrode 4 A configuration having a thickness of about 100 to 400 mm can be mentioned.

It is preferable that the electrode 4 having a square plane has a size of 1 mm or more on one side of the square. With such a size, it is possible to form an electrode using the above-mentioned hard mask (metal mask), which eliminates the need for resist coating and resist patterning steps for electrode formation, and simplifies the manufacturing process. ..

3. 3. The mobility of the thin film-rare earth hydride semiconductor is generally expected to be high, and when calculated from the numerical values described in Non-Patent Document 5, for example, the mobility of the bulk polycrystalline YH ₃ at room temperature has a carrier concentration of 1.9 ×. In the case of 10 ¹⁹ pieces cm ^-3 , it is about 40 cm ² / Vs. This carrier concentration means that the donor concentration is extremely high, and is at the degenerate semiconductor level. Conversely, if the carrier concentration of a normal semiconductor is used, 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 _YH3 film, which is a rare earth hydride semiconductor film obtained by the method of the present invention, is 23 cm ² / Vs when the carrier concentration is 1 × 10 ¹⁶ pieces cm ^-3 . , This mobility is the IGZO film (Indium, gallium), which is famous for its high mobility.
Higher mobility than (amorphous semiconductor film composed of Gallium), zinc (Zinc) and oxygen (Oxygen).

In recent years, display panels (organic EL display panels) using organic EL (Electro-Luminescence) elements represented by organic light emitting diodes (OLEDs) have been used to reduce power consumption and improve definition. High mobility thin film (TFT: Thin Film Transistor) is required. Further, the channel layer (semiconductor film) of the high mobility TFT needs to be able to be formed by a room temperature process from the viewpoint of preventing thermal deterioration of the plastic sheet used as an organic EL element or a flexible insulating substrate.

As described above, the method of the present invention can produce a polycrystalline rare earth hydride semiconductor film by a room temperature process. Therefore, by using the method of the present invention, a high mobility thin film in which the channel layer for an organic EL display panel or a liquid crystal display panel is made of a rare earth hydride semiconductor film can be produced at a process temperature almost the same as that of a conventional amorphous thin film. It can be manufactured, and a thin film having a bottom gate structure can be manufactured. The bottom gate structure is used in a conventional amorphous thin film, and since a thin film having a bottom gate structure can be manufactured, there is a merit that the consistency with the conventional process is good and the mass productivity is excellent.

8 (A) and 8 (B) show the final step of the manufacturing process of an example of a thin film in which the char layer made of a rare earth hydride semiconductor film (hereinafter, also referred to as “thin film of the present invention”) using the method of the present invention (hereinafter, also referred to as “thin film of the present invention”). The heat treatment process in an atmosphere containing hydrogen) and the process immediately 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 hydride metal. (Region), 17 is a source electrode, 18 is a drain electrode, 19 is a passion film, 20 is a platinum film, 102 is a thin film, 102a is a laminated structure, and white arrows are hydrogen in an atmosphere containing hydrogen. Is shown.

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

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

[Step A]
The gate electrode 12; the gate insulating film 13 covering the gate electrode 12; the rare earth element film 14 disposed on the gate insulating film 13; the source electrode 17 and the source electrode 17 arranged on the rare earth element film 14 on the insulating substrate 11. The drain electrode 18; the passivation film 19 covering the rare earth element film 14, the source electrode 17, and the drain electrode 18; and the platinum film 20 covering the passivation film 19 are sequentially formed to prepare the laminated structure 102a.

Examples of the insulating substrate 11 include a non-alkali glass substrate, a quartz glass substrate, and a plastic sheet (for example, polymethylmethacrylate, polyacrylate, polycarbonate, polystyrene, polyethylene sulfate, polyether sulfone, polyolefin, polyethylene terephthalate, polyethylene naphthalate, cycloolefin). With one or more synthetic resins selected from the group consisting of polymers, polyether sulfone, polyvinyl fluoride, ethylene-tetrafluoroethylene copolymers, weather resistant polypropylene, transparent polyimides, fluoropolymers and cyclic olefin polymers. (Formed sheet, etc.), glass fiber reinforced acrylic resin sheet, glass fiber reinforced polycarbonate sheet, etc. can be used, but the present invention is not limited thereto.

The gate electrode 12, the source electrode 17, and the drain electrode 18 have silver (Ag), copper (Cu), cobalt (Co), tantalum (Ta), molybdenum (Mo), chromium (Cr), aluminum (Al), and 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 from the viewpoint of easy acquisition of ohmic contact, and from this viewpoint, tantalum (Ta) and aluminum (Al) are preferable. These electrodes can be formed by a vacuum vapor deposition method, an ion plating method, a sputtering method, a laser ablation method, a plasma CVD method, an optical CVD method, screen printing, letterpress printing, an inkjet method, etc., but are limited thereto. Instead, a known and general method 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 forming portion using a photolithography method and removing unnecessary portions by etching, but the present invention is not limited to this method, and this type of electrode formation is performed. A general known patterning method in the above can be used.

As shown in FIGS. 8A and 8B, the gate insulating layer 13 can be formed over the entire surface of the substrate 1. Materials used for the gate insulating layer 13 include inorganic materials such as SiO ₂ , SiNx, SiON, Al ₂ O ₃ , Ta ₂ O ₅ , Y ₂ O ₃ , HfO ₂ , HfAlO, ZrO ₂ , and TiO ₂ ; PMMA. Polyacrylates such as (polymethylmethacrylate); PVA (polyvinyl alcohol); PS (polystyrene): transparent polyimide; polyester; epoxy resin; polyvinylphenol; polyvinyl alcohol and the like, but are not limited thereto. In order to suppress the gate leak current, the resistivity of the insulating material constituting the gate insulating layer 13 is preferably 10 ¹¹ Ω cm or more, and more preferably 10 ¹⁴ Ω cm or more. The gate insulating layer 13 includes, for example, a dry film forming method such as a vacuum vapor deposition method, an ion plating method, a sputtering method, a laser ablation method, a plasma CVD method, an optical CVD method, and a hot wire CVD method, a spin coating method, and a dip coating method. , Is formed by a wet film forming method such as a screen printing method.

For the rare earth element film 14, any one of 15 elements from La to Lu of the lanthanoid system of Sc, Y and the periodic table of elements is used. Of these, Sc, Y, Gd, or Yb is preferable.
The rare earth element film 14 is formed by a physical vapor deposition method (preferably a sputtering method, an electron beam (EB) vapor deposition method, etc.). The film 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, 500 nm or less is preferable, and 300 nm or less is more preferable.

The passivation film 19 is not particularly limited, and a known passivation film in a thin film for an organic EL display panel or a liquid crystal display panel can be used, for example, SiO ₂ , Si ₃ N ₄ , Al ₂ O ₃ , Ta ₂ O ₅ , etc. Can be mentioned. Among them, it is a hydrogen permeable film (that is, a hydrogen selective permeable film for converting (hydrogenating) a portion of the rare earth element film 14 located on the gate electrode 12 into a 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 that allows hydrogen that has been selectively permeated through the platinum film 20 to permeate to the rare earth element film 14).

The platinum film 20 is formed by a physical vapor deposition method (preferably a sputtering method, an electron beam (EB) vapor deposition method, 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 treatment time, it is preferably 40 nm or less, more preferably 20 nm or less.

[Step B]
The laminated structure 102a (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 laminated structure becomes a rare earth hydride film 14', and the portion of the rare earth hydride film 14' located on the gate electrode 17 becomes a rare earth hydride semiconductor (region) 15 and becomes a source electrode. The portion below the 17 and the drain electrode 18 becomes a rare earth hydride metal (region) 16, and a thin film 102 having the rare earth hydride semiconductor (region) 15 of the rare earth hydride film 14'as a channel layer can be obtained (FIG. 8). (B)).

Such step B is the heat treatment in the method of the present invention in an atmosphere containing hydrogen of the laminated film in which the platinum film is formed on the rare earth element film, and the detailed treatment conditions, equipment (conditions) and the like are as described above. Is. The atmosphere containing hydrogen is preferably an atmosphere having hydrogen 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 heat treatment temperature is room temperature or room temperature. Even if it is higher than 350 ° C.

9 shows another example of the thin film of the present invention, FIG. 9A shows a plane of the thin film, and FIG. 9B shows a cross section taken along line bb in FIG. 9A. In FIGS. 9A and 9B, the same reference numerals as those in FIGS. 8A and 8B indicate the same or corresponding portions, 103a indicates a laminated structure, and 103 indicates a thin film.

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

[Process C]
10 (A) to (D) and FIGS. 11 (A) and 11 (B) show the manufacturing process of the thin film film 103, and the same reference numerals as those of FIGS. 9 (A) and 9 (B) indicate the same or corresponding portions. , 21 indicate a resist.

After forming the gate electrode 12 made of, for example, tantalum (Ta) on the insulating substrate 11 (FIG. 10 (A)), for example, the gate insulating film 13 made of SiO ₂ is formed (FIG. 10 (B)). .. After that, the source electrode 17 and the drain electrode 18 are formed on the gate insulating film 13 (
FIG. 10 (C). The source electrode 17 and the drain electrode 18 preferably have a low work function, and are preferably formed of, for example, tantalum (Ta) or aluminum (Al). Further, 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 lower work function than 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 suitable.

When the source electrode 17 and the drain electrode 18 are formed of rare earth elements, yttrium (Y), scandium (Sc) or gadolinium (Gd) can be used in the step of hydrogenating the rare earth element film 14 made of ytterbium (Yb), which will be described later. It is necessary to select conditions that prevent the formation of hydride semiconductors. For example, when a ytterbium (Yb) film is formed at 290 nm by a resistance heating vapor deposition method, platinum is formed on the upper surface thereof at 10 nm, and treated in a 3% hydrogen + 97% argon atmosphere at 200 ° C. for 30 minutes, the semiconductor of YbH ₂ is formed. Then, gadolinium (Gd) was formed into a film of 280 nm by a sputtering method, platinum was formed into a film of 20 nm on the upper surface thereof, and under the same atmosphere and treatment conditions (that is, under a 3% hydrogen + 97% argon atmosphere, 200 ° C., 30 minutes). After heat treatment, it became a metal of GdH ₂ . Therefore, if gadolinium (Gd) is formed as a source electrode 17 and a drain electrode 18 by a sputtering method and ytterbium (Yb) is formed as a rare earth film 14 by a vapor deposition method, the electrodes 17 and 18 become hydride semiconductors. It is possible to make the rare earth film 14 into a semiconductor under the condition that it does not become.

After forming the source electrode 17 and the drain electrode 18, the resist 21 is applied to remove the resist 21 in the region where the rare earth element film for obtaining the channel layer should be formed. That is, the resist of the source electrode 17 and the drain electrode 18 on the gate insulating film 13 and the region covering these peripheral portions is removed. Then, a rare earth element film 14 made of itterbium (Yb) was formed by 200 (nm), and a platinum film 20 film was formed on the rare earth element film 14 by 10 (nm) (FIG. 10 (D)), and the resist 21 was formed. Is removed, a rare earth element film (itterbium (Yb) film) 14 and a platinum film 20 for forming a channel layer remain on the gate insulating film 13, and a laminated structure 103a is obtained (FIG. 11A).

The gate electrode 12, the gate insulating film 13 covering the gate electrode 12, the source electrode 17 and the drain electrode 18 arranged on the gate insulating film 13 are sequentially formed on the insulating substrate 11 as described above, and then the gate insulating film 12 is formed. The above step of sequentially forming the source electrode 17, the drain electrode 18, the rare earth element film (itterbium film) 14 covering only these electrodes and their peripheral portions, and the platinum film 20 covering the rare earth element film (itterbium film) 14. (Step C) corresponds to step A of obtaining a laminated structure having a laminated film including a rare earth element film 14 and a hydrogen selective permeation film (platinum film) 20 on an insulating substrate 11 in the above-mentioned manufacturing of the thin film film 102. do.

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

In the thin film 103 of the other example, it seems that a short circuit occurs between the source electricity 17 and the drain electrode 18 due to the presence of the platinum film 20, but the work function of platinum is as large as 5.7 eV. On the other hand, 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. Therefore, the platinum film 20 and the ytterbium dihydride (YbH ₂ ) semiconductor film 15 are shot key bonded. Will be. Therefore, the influence on the operation of the thin film 103 is small. Further, the laminated structure of the platinum film 20 / ytterbium dihydride (YbH ₂ ) semiconductor film 15 is stable, and there is little concern that hydrogen will escape as it is. It should be noted that there is no problem even in the laminated structure of platinum (Pt) / Ta ₂ O ₅ / ytterbium dihydride (YbH ₂ ) semiconductor film, and it is considered that the operation is more stable.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited by the following Examples and the like, and is appropriately applicable to the above and the following purposes. It is of course possible to implement it with modifications, all of which are within the technical scope of the invention.

(Example 1)
Sample preparation
A Y film having a thickness of 400 nm and a Pt film having a thickness of 20 nm are sequentially formed on a quartz glass substrate (thickness 0.5 mm) to form a sample (Sample 1: Pt (20 nm) / Y (400 nm) / quartz glass substrate. Laminated body) was produced. The Pt film and the Ti film were formed by an EB vapor deposition apparatus.

Hydrogenation treatment 1
An infrared annealing furnace capable of gas substitution after vacuuming was used as the annealing furnace, and heat treatment was performed at room temperature, 100 ° C., 200 ° C., and 325 ° C. under an atmosphere containing 3% by volume H ₂ + 97% by volume Ar of hydrogen. .. For heat treatment at room temperature, sample 1 is set in the annealing furnace, evacuated (pressure in the furnace: 5 × 10 ^-4 Pa), and a mixed gas of 3% by volume of hydrogen and 97% by volume of argon gas is mixed for 15 minutes. I shed it. For heat treatment at 100 ° C., 200 ° C. and 325 ° C., the annealing furnace is vacuumed (internal pressure: 5 × 10 ^-4 Pa), and a mixed gas of 3% by volume of hydrogen and 97% by volume of argon gas is flowed as a preliminary gas. After heating for 10 minutes, the sample 1 is set, evacuated (in-furnace pressure: 5 × 10 ^-4 Pa), the in-furnace temperature is set to 100 ° C., 200 ° C. or 325 ° C., and 3% by volume of hydrogen is used. And a mixed gas of 97% by volume of argon gas was flowed for 15 minutes.

Hydrogenation treatment 2
Sample 1 is set in the annealing furnace (inner temperature: room temperature), evacuated (internal pressure: 5 × 10 ^-4 Pa), and a 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 the Ti film (20 nm). The same hydrogenation treatment as in the hydrogenation treatments 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 the Au film (20 nm). The same hydrogenation treatment as in the hydrogenation treatments 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 treatment as in the hydrogenation treatments 1 and 2 was performed. The 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 the hydrogenation treatments 1 and 2 of the samples 1 to 4 according to Examples 1 and Comparative Examples 1 to 3 was performed by an X-ray diffractometer. 1 to 4 are X-ray diffraction charts of samples 1 to 4, respectively.

From FIG. 2, in sample 4 (Ni (20 nm) / Y (400 nm) / quartz glass substrate), the _YH3 film, which is a semiconductor phase, is hardly formed at room temperature or 100 ° C., and the _YH3 film is formed at 200 ° C. or higher. It can be seen that the formation temperature of the _YH3 film, which is the semiconductor phase, is higher than the existing results 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 was reduced probably due to the diffusion of Ti.

In sample 3 (Au (20 nm) / Y (400 nm) / quartz glass substrate) of FIG. 4, not only the formation of the YH ₃ film which is the semiconductor phase but also the formation of the YH ₂ film which is the metal phase was not confirmed. However, if the Y (002) plane is shifted to the low angle side and this is caused by the ingress of hydrogen into the Y membrane, it is presumed that the hydrogen molecules are decomposed and permeated on the surface.

In sample 1 (Pt (20 nm) / Y (400 nm) / quartz glass substrate) of FIG. 1 of Example 1, a _YH3 film which is a semiconductor phase is confirmed at room temperature.

Based on the above results and the existing results of Non-Patent Document 4, Table 1 below compares the easiness of forming the _YH3 film, which is a semiconductor phase at room temperature (RT) and 100 ° C.

(Example 2)
Hydrogen sensor
First, Au / Ta having a flat surface of 6 mm × 6 mm and a size of 2 mm square (a square with a flat surface size of 2 mm × 2 mm) at the four corners of the main surface of a non-alkali glass substrate having a thickness of 0.5 mm. Electrodes (Au film: 100 nm, Ta film: 50 nm) were formed. For this electrode, a hard mask (metal mask) having a hole with a size of 2 mm square is attached to the substrate without the need for patterning using a resist, and an Au film and a Ta film are sequentially formed by a sputtering method. This made it easy to form. Next, the hard mask (metal mask) used for forming the electrodes was removed, and a hard mask (metal mask) having a hole of 4 mm square (square with a flat size of 4 mm × 4 mm) was attached to the substrate and 4 mm square (4 mm square) (4 mm square). A Y film having a thickness of 400 nm with a flat surface of 4 mm × 4 mm is formed, and a Pt film of 4 mm square (square with a flat size of 4 mm × 4 mm) is formed on the upper surface of the Y film with a thickness of 200 nm to form a Pt (20 nm). ) / Y (400 nm) laminated film was obtained. The Y film and Pt film were formed by continuous film formation in vacuum by an electron beam vapor deposition method. The laminated structure thus obtained was placed in a mixed gas atmosphere (room temperature) of 3% by volume of hydrogen and 97% by volume of argon gas for 90 seconds to hydrogenate the Y film, as shown in FIGS. 6A and 6B. A hydrogen sensor with the structure shown is completed.

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

(Example 3)
Thin film
A Yb film having a thickness of 290 nm and a Pt film having a thickness of 10 nm are sequentially formed on a quartz glass substrate (thickness 0.5 mm) to form a sample (Sample 1: Pt (10 nm) / Yb (290 nm) / quartz glass substrate (sample 1: Pt (10 nm) / Yb (290 nm)). 500 nm) was prepared. After that, an infrared annealing furnace capable of gas substitution after vacuuming was used as the annealing furnace, and the temperature was 100 ° C. and 200 ° C. under a mixed gas atmosphere of 3% by volume of hydrogen and 97% by volume of argon gas. , 250 ° C., respectively. FIG. 13 shows the result of X-ray diffraction of the sample 1 together with the result before the treatment. Ytterbium dihydride (YbH ₂ ) was obtained at room temperature, and there was no loss of hydrogen. It had a stable structure. Therefore, it was confirmed that a rare earth hydride semiconductor film to be a channel layer of a thin film film can be formed on an insulating substrate by a room temperature process.

1 Rare earth hydride metal film 2 Platinum film 3 Insulation substrate 4 Electrode 5 Wiring 11 Insulation substrate 12 Gate electrode 13 Gate insulating film 14 Rare earth element film 14'Rare earth hydride film 15 Rare earth hydride semiconductor (region)
16 Rare earth hydride metal (region)
17 Source electrode 18 Drain electrode 19 Passivation film 20 Platinum film 100 Hydrogen sensor 101 Spin current conversion element 102 Thin film totangister

Claims (5)

A thin film characterized in that the channel layer contains a rare earth hydride semiconductor. A method for manufacturing a thin film containing a rare earth hydride semiconductor, wherein the channel layer includes the following steps A and B:
Step 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,
Source and drain electrodes disposed on the rare earth element film,
The rare earth element film, the passivation film covering the source electrode and the drain electrode, and the platinum film covering the passivation film are sequentially formed;
Step B: The laminated structure obtained through the step A is heat-treated in an atmosphere containing hydrogen. The second aspect of the present invention, wherein instead of the step A, the following step C is provided, and the step B is changed to a step of heat-treating the laminated structure obtained through the following step C in an atmosphere containing hydrogen. Method:
Step C: A gate electrode, a gate insulating film covering the gate electrode, a source electrode and a drain electrode arranged on the gate insulating film are sequentially formed on the insulating substrate, and then the source on the gate insulating film is formed. A rare earth element film covering only the electrode, the drain electrode, and the peripheral portion of these electrodes, and a platinum film covering the rare earth element film are sequentially formed. The method according to claim 2 or 3, wherein the atmosphere containing hydrogen is an atmosphere containing an amount of hydrogen equal to or less than the explosion limit. The method according to any one of claims 2 to 4, wherein the heat treatment temperature is room temperature.

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