Method for controlling orientation of transition metal chalcogenide thin film, method and apparatus for manufacturing, and flexible substrate

Abstract

To provide a technology capable of controlling an orientation direction of a transition metal chalcogenide layer with simple control on a film deposition condition.SOLUTION: A method for controlling orientation of a transition metal chalcogenide thin film includes a step of controlling an orientation direction of a transition metal chalcogenide layer that is formed at a surface of a substrate by controlling an amount of a chalcogen material to be supplied per unit time basis to a transition metal layer of the surface of the substrate.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for controlling the orientation of a transition metal chalcogenide thin film, a manufacturing method, a manufacturing apparatus, and a flexible substrate.

Background Art

[0002] A transition metal chalcogenide thin film, which is a two-dimensional material of a transition metal chalcogenide formed of a transition metal and a chalcogen material, has a layered structure in which nanosheets are stacked. And, since the transition metal chalcogenide thin film has characteristics such as high electron mobility and light absorption coefficient in the in-plane direction of the nanosheet, and high chemical stability against heat and oxygen, it is attracting attention as a new material to replace silicon for verifying physical phenomena in the nano region and realizing nano devices.

[0003] Since the transition metal chalcogenide thin film has high electron mobility in the in-plane direction of the nanosheet, control of the orientation according to the device is important. Patent Document 1 describes that thin films with different orientations are formed by controlling the reaction temperature between the transition metal and the chalcogen material and the amount of the chalcogen material supplied to the transition metal.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the method described in Patent Document 1, in order to control the orientation of the transition metal chalcogenide layer, it is necessary to control both the reaction temperature and the supply amount of the chalcogen material, and each control can be complicated. Therefore, there is a need for a technique capable of controlling the orientation direction of the transition metal chalcogenide layer by simpler control of the film formation conditions.

[0006] An object of the present invention is to realize a technique capable of controlling the orientation direction of a transition metal chalcogenide layer by simply controlling film formation conditions.

Means for Solving the Problems

[0007] In order to solve the above problems, a method for controlling the orientation of a transition metal chalcogenide thin film according to an aspect of the present invention includes a step of controlling the amount of a chalcogen material supplied per unit time to a transition metal layer on the surface of a substrate, thereby controlling the orientation direction of the transition metal chalcogenide layer formed on the surface of the substrate.

[0008] A method for manufacturing a transition metal chalcogenide thin film according to an aspect of the present invention includes a step of supplying a chalcogen material to the surface of a substrate having a transition metal layer and forming a transition metal chalcogenide layer on the surface of the substrate. In the forming step, the orientation direction of the transition metal chalcogenide layer is controlled by the method for controlling the orientation of a transition metal chalcogenide thin film according to an aspect of the present invention.

[0009] A flexible substrate according to an aspect of the present invention has a transition metal chalcogenide layer with a predetermined orientation direction formed on the surface of a substrate having a transition metal layer.

[0010] A manufacturing apparatus for a transition metal chalcogenide thin film according to an aspect of the present invention includes a chalcogen material supply unit that supplies a chalcogen material to a transition metal layer on the surface of a substrate, and a chalcogen material control unit that controls the amount of the chalcogen material supplied per unit time. The chalcogen material control unit controls the orientation direction of the formed transition metal chalcogenide layer to be substantially parallel to the surface of the substrate by making the amount of the chalcogen material supplied to the transition metal layer per unit time less than a predetermined amount, and controls the orientation direction of the formed transition metal chalcogenide layer to be substantially perpendicular to the surface of the substrate by making the amount of the chalcogen material supplied to the transition metal layer per unit time more than a predetermined amount.

Effects of the Invention

[0011] According to one aspect of the present invention, a technique capable of controlling the orientation direction of a transition metal chalcogenide layer can be realized by simple control of film formation conditions.

Brief Description of the Drawings

[0012]

Figure 1

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Figure 9

Mode for Carrying Out the Invention

[0013] 〔Orientation Control Method〕 A method for controlling the orientation of a transition metal chalcogenide thin film according to an aspect of the present invention (hereinafter, also simply referred to as the orientation control method) includes a step of controlling the orientation direction of a transition metal chalcogenide layer formed on the surface of a substrate by controlling the amount of a chalcogen material supplied per unit time to a transition metal layer on the surface of the substrate.

[0014] The inventors of the present invention have found that the orientation direction of the generated transition metal chalcogenide layer can be controlled only by controlling the amount of the chalcogen material supplied to the transition metal layer, and have thus completed the present invention.

[0015] In the controlling step, the amount of the chalcogen material supplied per unit time to the transition metal layer on the surface of the substrate is controlled. Thereby, the amount of contact between the transition metal and the chalcogen material per unit time is controlled. As a result, the orientation direction of the transition metal chalcogenide layer generated by the reaction between the transition metal and the chalcogen material can be controlled. The amount of the chalcogen material supplied per unit time can also be represented by the supply rate of the chalcogen material, the supply concentration of the chalcogen material, the supply flow rate of the fluid containing the chalcogen material, and the like. Here, the unit time can be set as appropriate, and as an example, it is 1 minute (min).

[0016] The chalcogen material whose supply amount is controlled in the controlling step can be any one of sulfur, selenium, and tellurium. The chalcogen material can be supplied in the form of a powder or a fluid, and it is preferable that a gas containing the chalcogen material is supplied. The gas containing the chalcogen material can perform more stable and accurate control of the supply amount. As an example, the gas containing the chalcogen material is C2H6S2. The transition metal layer is a layer containing a transition metal such as tungsten, molybdenum, zirconium, hafnium, platinum, rhenium, titanium, tantalum, niobium, vanadium, cobalt, rhodium, and iridium.

[0017] The transition metal chalcogenide layer has a layered structure in which nanosheets are stacked. Since the transition metal chalcogenide thin film having the transition metal chalcogenide layer has a two-dimensional crystal structure, it has a high specific surface area. Also, since atoms can move between the layers in the transition metal chalcogenide thin film, it can be used as an atomic-level filter. Further, the transition metal chalcogenide thin film can be used as a flexible device. Additionally, the transition metal chalcogenide thin film has high chemical stability, light absorption coefficient, and electron mobility. Due to having these characteristics, the transition metal chalcogenide thin film can contribute to the realization of highly sensitive and multifunctional sensor devices.

[0018] In the step of controlling, by making the amount of the chalcogen material supplied to the transition metal layer per unit time less than a predetermined amount, the orientation direction of the formed transition metal chalcogenide layer can be controlled to be substantially parallel to the surface of the substrate, and by making the amount of the chalcogen material supplied to the transition metal layer per unit time more than a predetermined amount, the orientation direction of the formed transition metal chalcogenide layer can be controlled to be substantially perpendicular to the surface of the substrate.

[0019] Here, the orientation direction of the transition metal chalcogenide layer will be described with reference to FIG. 1. FIG. 1 is a diagram schematically showing the orientation direction of the transition metal chalcogenide layer generated by supplying a chalcogen material to the transition metal layer. As shown in FIG. 1001 of FIG. 1, by controlling the amount of the chalcogen material supplied to the substrate having the transition metal layer 11 formed on the substrate 10, a transition metal chalcogenide layer 12 oriented in a direction substantially parallel to the surface of the substrate 10 as shown in FIG. 1002 is formed. Also, as shown in FIG. 1003 of FIG. 1, by controlling the amount of the chalcogen material supplied to the substrate having the transition metal layer 21 formed on the substrate 20, a transition metal chalcogenide layer 22 oriented in a direction substantially perpendicular to the surface of the substrate 20 as shown in FIG. 1004 is formed.

[0020] In addition, the in-plane direction includes a direction completely parallel to the surface of the substrate and a direction substantially parallel within a predetermined error range. The orientation in the in-plane direction can also be referred to as the in-plane orientation and can be of type II or plain orientation having a van der Waals (VdW) plane parallel to the surface of the substrate. Further, the out-of-plane direction includes a direction completely perpendicular to the surface of the substrate and a direction substantially perpendicular within a predetermined error range. The orientation in the out-of-plane direction can be of type I or vertical orientation having a VdW plane perpendicular to the surface of the substrate.

[0021] The use of the transition metal chalcogenide layer varies depending on its orientation direction. The transition metal chalcogenide layer oriented in the in-plane direction can be used in IC chips, sensor devices, optical sensors, spintronic devices, etc. The transition metal chalcogenide layer oriented in the out-of-plane direction can be used in batteries, memories, catalysts, solar cells, filters, sensor devices, capacitors, etc.

[0022] In the control step, the amount of the chalcogen material supplied to the transition metal layer per unit time is made less than a predetermined amount to control the orientation so as to form a transition metal chalcogenide layer oriented in the in-plane direction. Also, in the control step, the amount of the chalcogen material supplied to the transition metal layer per unit time is made more than a predetermined amount to control the orientation so as to form a transition metal chalcogenide layer oriented in the out-of-plane direction.

[0023] In the control step, the predetermined amount that serves as the criterion for controlling the supply amount is intended to be an amount in which both the orientation in the substantially parallel direction and the orientation in the substantially perpendicular direction are formed. Such a predetermined amount, as an example, when the chalcogen material is C2H6S2 and the transition metal layer is a molybdenum layer, is 200 sccm (= 0.073 mol%) under a vapor pressure of 3.8 kPa of C2H6S2 at 25 degrees. The predetermined amount can be set for each chalcogen material and transition metal used with reference to the amounts exemplified in this specification. The predetermined amount, as an example, is 50 sccm or more and 500 sccm or less, and may be 100 sccm or more and 300 sccm or less under a vapor pressure of 3.8 kPa at 25 degrees.

[0024] When the supply amount of the chalcogen material is controlled to be less than the predetermined amount as described above, for example, 30 sccm (in the case of C2H6S2, 0.011 mol%), a transition metal chalcogenide layer oriented in the substantially parallel direction is formed. When controlling the orientation direction of the transition metal chalcogenide layer to be in the substantially parallel direction, the supply amount of the chalcogen material, as an example, is 10 sccm or more and 80 sccm or less, may be 20 sccm or more and 60 sccm or less, and may be 30 sccm or more and 50 sccm or less under a vapor pressure of 3.8 kPa of C2H6S2 at 25 degrees.

[0025] When the supply amount of the chalcogen material is controlled to be more than the predetermined amount as described above, for example, 1000 sccm (in the case of C2H6S2, 0.367 mol%), a transition metal chalcogenide layer oriented in the substantially perpendicular direction is formed. When controlling the orientation direction of the transition metal chalcogenide layer to be in the substantially perpendicular direction, the supply amount of the chalcogen material, as an example, is 800 sccm or more, may be 900 sccm or more, and may be 1000 sccm or more under a vapor pressure of 3.8 kPa of C2H6S2 at 25 degrees.

[0026] In the control step, in the transition metal layer, the amount of the chalcogen material supplied per unit time may be controlled so that a region where the amount is less than a predetermined amount and a region where the amount is more than the predetermined amount are formed. Thus, by controlling the amount of the chalcogen material supplied to be different for each region of the transition metal layer, transition metal chalcogenide layers having different orientation directions can be formed on the surface of one substrate.

[0027] By providing, for each region of the transition metal layer, a region where the supply amount of the chalcogen material is less than a predetermined amount and a region where the supply amount is more than the predetermined amount, it is possible to control so that both a transition metal chalcogenide layer oriented in a substantially parallel direction and a transition metal chalcogenide layer oriented in a substantially perpendicular direction are formed on the surface of one substrate. The regions for forming the transition metal chalcogenide layers having different orientation directions can be formed for each orientation direction by patterning the surface of the substrate.

[0028] In a multifunctional device such as a smart sensor, there may be a case where transition metal chalcogenide layers having different orientation directions are provided on the surface of one substrate. Such a multifunctional device will be described with reference to FIG. 2. FIG. 2 is a diagram schematically showing a flexible substrate 100 having transition metal chalcogenide layers with different orientation directions. As shown in FIG. 2, the flexible substrate 100 has a transistor portion 103 having a transition metal chalcogenide layer 102 oriented in a substantially parallel direction and a capacitor sensor portion 105 having a transition metal chalcogenide layer 104 oriented in a substantially perpendicular direction on a substrate 101.

[0029] However, the film formation conditions of the transition metal chalcogenide layer oriented in the substantially perpendicular direction and the transition metal chalcogenide layer oriented in the substantially parallel direction are different. Therefore, it was necessary to transfer the transition metal chalcogenide layers in each orientation direction formed on another substrate to the surface of the substrate. In addition to an increase in the manufacturing process, since the transition metal chalcogenide layer is a thin film, the transfer process is not easy. Therefore, it is advantageous if transition metal chalcogenide layers having different orientation directions can be formed on the surface of one substrate without transfer.

[0030] According to the method for controlling the orientation of a transition metal chalcogenide thin film according to one aspect of the present invention, the orientation direction of the formed transition metal chalcogenide layer can be controlled only by controlling the amount of the chalcogen material supplied to the transition metal layer per unit time. Therefore, a plurality of transition metal chalcogenide layers having different orientation directions can be directly formed on the surface of one substrate, and a transfer process is unnecessary. The method for controlling the orientation of a transition metal chalcogenide thin film according to one aspect of the present invention can also be used in the manufacture of multifunctional devices.

[0031] 〔Method for manufacturing a transition metal chalcogenide thin film〕 The method for manufacturing a transition metal chalcogenide thin film according to one aspect of the present invention (hereinafter, also simply referred to as the manufacturing method) includes a step of supplying a chalcogen material to the surface of a substrate having a transition metal layer and forming a transition metal chalcogenide layer on the surface of the substrate. In the forming step, the orientation direction of the transition metal chalcogenide layer is controlled by the method for controlling the orientation of a transition metal chalcogenide thin film according to one aspect of the present invention.

[0032] According to the method for manufacturing a transition metal chalcogenide thin film according to one aspect of the present invention, since the orientation direction of the transition metal chalcogenide layer formed on the surface of the substrate is controlled by the method for controlling the orientation of a transition metal chalcogenide thin film according to one aspect of the present invention, a transition metal chalcogenide thin film having a transition metal chalcogenide layer in a desired orientation direction can be manufactured.

[0033] In the forming step, by supplying a chalcogen material to the surface of the substrate having a transition metal layer, the transition metal reacts with the chalcogen material, and a transition metal chalcogenide layer is formed on the surface of the substrate.

[0034] In the forming step, a transition metal chalcogenide layer oriented in a substantially parallel direction is formed by making the amount of the chalcogen material supplied to the transition metal layer per unit time less than a predetermined amount. Also, in the forming step, a transition metal chalcogenide layer oriented in a substantially perpendicular direction is formed by making the amount of the chalcogen material supplied to the transition metal layer per unit time more than a predetermined amount. Thus, a transition metal chalcogenide layer with a controlled orientation direction can be formed.

[0035] In the forming step, on the surface of one substrate, a transition metal chalcogenide layer oriented in a substantially parallel direction with respect to the surface of the substrate and a transition metal chalcogenide layer oriented in a substantially perpendicular direction with respect to the surface of the substrate can be formed. By only controlling the amount of the chalcogen material supplied to the transition metal layer per unit time, both a transition metal chalcogenide layer oriented in a substantially parallel direction and a transition metal chalcogenide layer oriented in a substantially perpendicular direction can be directly formed on the surface of one substrate. Thus, without performing a transfer process, a plurality of transition metal chalcogenide layers with different orientation directions can be formed on the surface of one substrate.

[0036] In the forming step, when forming a transition metal chalcogenide layer oriented in a substantially parallel direction, the supply amount of the chalcogen material is, for example, 50 sccm or more and 500 sccm or less, and may be 100 sccm or more and 30 sccm or less under the vapor pressure of 3.8 kPa of C2H6S2 at 25 degrees. In the forming step, when forming a transition metal chalcogenide layer oriented in a substantially perpendicular direction, the supply amount of the chalcogen material is, for example, 800 sccm or more, may be 900 sccm or more, and may be 1000 sccm or more under the vapor pressure of 3.8 kPa of C2H6S2 at 25 degrees. In the forming step, the chalcogen material is continuously supplied to the transition metal layer until a desired transition metal chalcogenide layer is formed.

[0037] The substrate having a transition metal layer may be a substrate formed of a material containing a transition metal, or may be a transition metal substrate made of a transition metal. Further, the substrate having a transition metal layer may be one in which a layer containing a transition metal is formed on the surface of a substrate made of a material other than a transition metal, such as a silicon substrate or a sapphire substrate. The substrate having a transition metal layer is preferably a flexible thin plate.

[0038] The thickness of the transition metal layer on the surface of the substrate may be 10 nm or more, 30 nm or more, 50 nm or more, or 80 nm or more, and is preferably 100 nm or more. When the substrate having a transition metal layer is a transition metal substrate, the thickness of the transition metal substrate is preferably 100 nm or more. When the thickness of the transition metal layer or the transition metal substrate is 100 nm or more, it is possible to more suitably form transition metal chalcogenide layers having different orientation directions. The thickness of the transition metal layer may be 120 nm or more, 150 nm or more, 200 nm or more, or 500 nm or more.

[0039] In the forming step, a gas containing a chalcogen material may be supplied to the surface of the substrate. By supplying a gas containing a chalcogen material to the surface of the substrate, it is possible to more stably and accurately control the supply amount. For example, even in the case of stably supplying a small amount of chalcogen material for a certain period of time, stable supply is possible. As an example, the gas containing a chalcogen material is C2H6S2.

[0040] Before the forming step, a step of heat-treating the transition metal layer in a hydrogen atmosphere may be further included. By heat-treating the transition metal layer in a hydrogen atmosphere before the forming step, the grain size of the transition metal chalcogenide layer formed in the forming step can be increased. In the heat-treating step, as an example, the substrate having a transition metal layer is heated at 600 °C or more and 1000 °C or less in a hydrogen atmosphere.

[0041] Regarding the heat treatment step, it may be heat-treated at a temperature for recrystallizing the transition metal layer in a hydrogen atmosphere. By heating at a temperature for recrystallizing the transition metal layer, the grain size of the transition metal chalcogenide layer oriented in a direction substantially parallel to the surface of the substrate having the transition metal layer can be made larger. The recrystallization temperature may be adjusted according to the recrystallization temperature of the transition metal in the transition metal layer. For example, the recrystallization temperature of molybdenum (Mo) is 900 °C or higher and 1200 °C or lower. The recrystallization temperature of tungsten (W) is 1150 °C or higher and 1350 °C or lower. The recrystallization temperature of niobium (Nb) is 950 °C or higher and 1200 °C or lower. The recrystallization temperature of tantalum (Ta) is 1150 °C or higher and 1300 °C or lower. The recrystallization temperature of titanium (Ti) is 700 °C or higher and 900 °C or lower.

[0042] According to the method for manufacturing a transition metal chalcogenide thin film according to one aspect of the present invention, a transition metal chalcogenide thin film having a transition metal chalcogenide layer in a desired orientation direction can be manufactured only by controlling the amount of the chalcogen material supplied per unit time. Therefore, without performing a transfer process, a plurality of transition metal chalcogenide layers having different orientation directions can be directly formed on the surface of one substrate. The method for manufacturing a transition metal chalcogenide thin film according to one aspect of the present invention can also be used in the manufacture of multifunctional devices.

[0043] [Flexible substrate] A flexible substrate according to one aspect of the present invention has a transition metal chalcogenide layer in a predetermined orientation direction formed on the surface of a substrate having a transition metal layer. That is, a flexible substrate according to one aspect of the present invention is a flexible substrate having a transition metal chalcogenide layer formed by the method for manufacturing a transition metal chalcogenide thin film according to one aspect of the present invention described above. Therefore, for the details of the flexible substrate according to one aspect of the present invention, the descriptions of the method for controlling the orientation of the transition metal chalcogenide thin film and the method for manufacturing the transition metal chalcogenide thin film according to one aspect of the present invention described above are incorporated by reference.

[0044] A flexible substrate according to one aspect of the present invention is a flexible substrate in which a transition metal chalcogenide layer oriented in a direction substantially parallel to the surface of the substrate and a transition metal chalcogenide layer oriented in a direction substantially perpendicular to the surface of the substrate are formed on the surface of the same substrate. That is, an example of the flexible substrate according to one aspect of the present invention is the flexible substrate 100 as a multifunctional device shown in FIG. 2.

[0045] In the flexible substrate according to one aspect of the present invention, a plurality of transition metal chalcogenide layers having different orientation directions are directly formed on the surface of one substrate body and have not undergone a transfer process. Therefore, problems such as tearing and warping of the thin film due to the transfer process do not occur, and it has high performance and can be easily manufactured.

[0046] 〔Manufacturing Apparatus for Transition Metal Chalcogenide Thin Film〕 A manufacturing apparatus for a transition metal chalcogenide thin film according to one aspect of the present invention includes a chalcogen material supply unit that supplies a chalcogen material to a transition metal layer on the surface of a substrate body, and a chalcogen material control unit that controls the amount of the chalcogen material supplied per unit time. The chalcogen material control unit controls the orientation direction of the formed transition metal chalcogenide layer to be substantially parallel to the surface of the substrate body by making the amount of the chalcogen material supplied to the transition metal layer per unit time less than a predetermined amount, and controls the orientation direction of the formed transition metal chalcogenide layer to be substantially perpendicular to the surface of the substrate body by making the amount of the chalcogen material supplied to the transition metal layer per unit time more than a predetermined amount.

[0047] That is, the manufacturing apparatus for a transition metal chalcogenide thin film according to one aspect of the present invention is an aspect of an apparatus that executes the manufacturing method for a transition metal chalcogenide thin film according to one aspect of the present invention. Therefore, for the details of the processes executed by each part of the manufacturing apparatus for a transition metal chalcogenide thin film according to one aspect of the present invention, the descriptions of the orientation control method for a transition metal chalcogenide thin film and the manufacturing method for a transition metal chalcogenide thin film according to one aspect of the present invention described above are incorporated.

[0048] Further, an example of the manufacturing apparatus for a transition metal chalcogenide thin film according to one aspect of the present invention is the film forming apparatus 200 shown in FIG. 3, which was used in the examples described later. In the film forming apparatus 200, the raw material tank 204 corresponds to a chalcogen material supply unit that supplies a chalcogen material to the transition metal layer on the surface of the substrate. Further, the vaporization supply device (MFC) 205 corresponds to a chalcogen material control unit that controls the amount of the chalcogen material supplied per unit time. And the vaporization supply device 205 controls the orientation direction of the formed transition metal chalcogenide layer to be substantially parallel to the surface of the substrate by making the amount of the chalcogen material supplied to the transition metal layer per unit time less than a predetermined amount, and controls the orientation direction of the formed transition metal chalcogenide layer to be substantially perpendicular to the surface of the substrate by making the amount of the chalcogen material supplied to the transition metal layer per unit time more than a predetermined amount.

[0049] According to the manufacturing apparatus for a transition metal chalcogenide thin film according to one aspect of the present invention, a transition metal chalcogenide thin film having a transition metal chalcogenide layer in a desired orientation direction can be manufactured only by controlling the amount of the chalcogen material supplied per unit time. Therefore, without performing a transfer process, a transition metal chalcogenide thin film in which a plurality of transition metal chalcogenide layers having different orientation directions are directly formed on the surface of one substrate can be manufactured. The manufacturing apparatus for a transition metal chalcogenide thin film according to one aspect of the present invention can also be utilized in the manufacture of multifunctional devices.

[0050] The manufacturing apparatus for a transition metal chalcogenide thin film according to one aspect of the present invention further includes a film forming unit that forms a transition metal chalcogenide thin film by heat-treating a substrate having a transition metal layer while supplying a chalcogen material by a vapor phase chemical vapor deposition method, a metalorganic chemical vapor deposition method, a plasma vapor phase chemical vapor deposition method, a sulfidation method, or a sputtering method. In the film forming apparatus 200, the chamber 201 corresponds to a film forming unit that heat-treats a substrate having a transition metal layer while supplying a chalcogen material and forms a transition metal chalcogenide thin film. In the chamber 201, a transition metal chalcogenide thin film is formed by any of known film forming methods including a vapor phase chemical vapor deposition method, a metalorganic chemical vapor deposition method, a plasma vapor phase chemical vapor deposition method, a sulfidation method, and a sputtering method.

[0051] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope indicated in the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

Example

[0052] An example of the present invention will be described below. In the example, a transition metal chalcogenide thin film was formed on the surface of a silicon substrate 203 having a molybdenum layer (Mo thin film, thickness of about 200 nm) using the film forming apparatus 200 schematically shown in FIG. 3. The silicon substrate 203 was placed in the chamber 201, and the silicon substrate 203 was heat-treated with hydrogen by heating the silicon substrate 203 with a heater 202 while flowing a mixed gas of argon (Ar) and hydrogen (H2) in the carrier gas tank 206 into the chamber 201. Thereafter, C2H6S2 stored in the raw material tank 204 was vaporized and supplied into the chamber 201 together with the mixed gas of Ar and H2 in the carrier gas tank 206. The gas supply to the chamber 201 was controlled using a vaporization supply device (MFC) 205. While heating the chamber 201 with the heater 202, a MoS2 layer with a controlled orientation direction was formed by supplying a gas containing sulfur.

[0053] The temperature sequence during the supply of C2H6S2 gas is shown in Fig. 4. Fig. 4 is a diagram showing the temperature sequence during the supply of the chalcogen material in the examples. As shown in Fig. 4, during the heating up to 800 °C from the start of supply until 80 minutes, the carrier gas of Ar / H2 was supplied. However, between 80 minutes and 95 minutes when 800 °C was reached, the C2H6S2 gas vaporized by the carrier gas was supplied. After that, when the heating was stopped and natural cooling occurred, the carrier gas was supplied. Note that the temperature sequence shown in Fig. 4 was carried out under atmospheric pressure.

[0054] The results of examining the relationship between the supply amount of C2H6S2 gas supplied to chamber 201 and the orientation direction of the formed transition metal chalcogenide layer are shown in Figs. 5 to 8. Note that the supply of C2H6S2 gas was carried out while heating the inside of chamber 201 at 800 °C for 15 minutes under atmospheric pressure.

[0055] Fig. 5 is a diagram showing the XRD analysis results indicating the relationship between the supply flow rate of the chalcogen material and the orientation direction of the transition metal chalcogenide layer in the examples. Fig. 6 is a diagram showing the XRD analysis results indicating the relationship between the supply concentration of the chalcogen material and the orientation direction of the transition metal chalcogenide layer in the examples. Fig. 7 is a diagram showing the SEM image of the transition metal chalcogenide layer formed in the examples. Fig. 8 is a diagram showing the TEM image of the cross-section of the transition metal chalcogenide layer formed in the examples. Note that in Fig. 8, the lower image showing the MoS2 layer (V-MoS2) oriented in a substantially vertical direction is an enlarged view of the framed portion of the upper image.

[0056] As shown in Fig. 5, it was confirmed by XRD analysis that when the supply flow rate of C2H6S2 gas was 30 sccm, only the MoS2 layer (P-MoS2) oriented in a substantially parallel direction was formed, and when it was 100 sccm and 200 sccm, both the MoS2 layers in the substantially parallel direction and the substantially vertical direction were formed in a mixed state. Also, it was confirmed by XRD analysis that when the supply flow rate of C2H6S2 gas was 500 sccm and 1000 sccm, only the V-MoS2 oriented in a substantially vertical direction was formed.

[0057] As shown in Fig. 6, when the supply concentration of C2H6S2 gas was 0.011 mol%, only P-MoS2 was formed. When it was 0.037 mol% and 0.074 mol%, it was confirmed by XRD analysis that MoS2 layers in both the substantially parallel direction and the substantially perpendicular direction were formed in a mixed state. Also, when the supply concentration of C2H6S2 gas was 0.184 mol% and 0.367 mol%, it was confirmed by XRD analysis that only V-MoS2 was formed.

[0058] Also, as shown in Figs. 7 and 8, the film formation of each layer of P-MoS2 and V-MoS2 was also confirmed by SEM images and TEM images.

[0059] Fig. 9 is a diagram showing the influence of the change in the grain size of Mo due to the heat treatment temperature (800 °C, 1000 °C, or 1100 °C) in a hydrogen atmosphere. Except for the heat treatment temperature in the hydrogen atmosphere, a transition metal chalcogenide thin film was formed at 800 °C on the surface of the silicon substrate 203 having the Mo thin film as described above.

[0060] In Fig. 9, "Mo" indicates the grain size of Mo in the Mo thin film. "P-MoS2" indicates the grain size of MoS2 oriented in the substantially parallel direction. "V-MoS2" indicates the grain size of the MoS2 layer oriented in the substantially perpendicular direction. The grain sizes of Mo in "P-MoS2" and "V-MoS2" were calculated from the XRD data. The vertical axis of Fig. 9 indicates the grain size (unit: nm), and the horizontal axis indicates the heat treatment temperature (unit: °C) of the Mo thin film in the hydrogen atmosphere.

[0061] As shown in Fig. 9, for the Mo thin film, as the heat treatment temperature increased, the grain size of Mo increased. This result was in line with the principle that the grain size of Mo increases by heat treatment at a temperature higher than the recrystallization temperature of Mo (about 980 °C). It was confirmed that as the grain size of Mo increased, the grain size of P-MoS2 also increased. This is because the density of grain boundaries that hinder the growth of P-MoS2 in the Mo thin film decreases due to the increase in grain size.

Description of Reference Numerals

[0062] 100 Flexible substrate 101 Substrate 102, 104 Transition metal chalcogenide layer 200 Film forming apparatus (manufacturing apparatus for transition metal chalcogenide thin film) 201 Chamber (film forming section) 204 Raw material tank (chalcogen material supply section) 205 Vaporization supply device (chalcogen material control section)

Claims

1. A method for controlling the orientation of a transition metal chalcogenide thin film, comprising a step of controlling the amount of chalcogen material supplied per unit time to a transition metal layer on a surface of a substrate, thereby controlling the orientation direction of a transition metal chalcogenide layer formed on the surface of the substrate.

2. In the step of controlling, by reducing the amount of the chalcogen material supplied to the transition metal layer per unit time to less than a predetermined amount, the orientation direction of the formed transition metal chalcogenide layer is controlled to be approximately parallel to the surface of the substrate; By increasing the amount of the chalcogen material supplied to the transition metal layer per unit time to a predetermined amount, the orientation direction of the formed transition metal chalcogenide layer is controlled to be approximately perpendicular to the surface of the substrate. The method for controlling the orientation of a transition metal chalcogenide thin film according to claim 1 .

3. In the step of controlling, controlling the amount of the chalcogen material supplied per unit time in the transition metal layer to form a region in which the amount is less than a predetermined amount and a region in which the amount is more than the predetermined amount; The method for controlling the orientation of a transition metal chalcogenide thin film according to claim 2 .

4. providing a chalcogen material to a surface of a substrate having a transition metal layer thereon to form a transition metal chalcogenide layer on the surface of the substrate; In the forming step, the orientation direction of the transition metal chalcogenide layer is controlled by the method for controlling the orientation of a transition metal chalcogenide thin film according to any one of claims 1 to 3. A method for producing transition metal chalcogenide thin films.

5. In the forming step, a transition metal chalcogenide layer oriented in a direction substantially parallel to the surface of the substrate and a transition metal chalcogenide layer oriented in a direction substantially perpendicular to the surface of the substrate are formed on the surface of one of the substrates. The method for producing the transition metal chalcogenide thin film according to claim 4 .

6. The thickness of the transition metal layer is 100 nm or more. The method for producing the transition metal chalcogenide thin film according to claim 4 .

7. The substrate is a transition metal substrate, or a silicon substrate or a sapphire substrate having a transition metal layer on its surface. The method for producing the transition metal chalcogenide thin film according to claim 4 .

8. In the forming step, a gas containing a chalcogen material is supplied to a surface of the substrate; The method for producing the transition metal chalcogenide thin film according to claim 4 .

9. The method further includes a step of heat treating the transition metal layer in a hydrogen atmosphere prior to the forming step. The method for producing the transition metal chalcogenide thin film according to claim 4 .

10. The method for producing a transition metal chalcogenide thin film according to claim 9 , wherein in the heat treatment step, the heat treatment is performed at a temperature at which the transition metal layer is recrystallized.

11. A flexible substrate having a transition metal chalcogenide layer in a predetermined orientation direction deposited on a surface of a substrate having a transition metal layer.

12. The flexible substrate according to claim 11 , wherein a transition metal chalcogenide layer oriented in a direction approximately parallel to the surface of the substrate and a transition metal chalcogenide layer oriented in a direction approximately perpendicular to the surface of the substrate are formed on the same surface of the substrate.

13. a chalcogen material supplying section for supplying a chalcogen material to the transition metal layer on the surface of the substrate; a chalcogen material control unit that controls an amount of the chalcogen material supplied per unit time, The chalcogen material control unit is by reducing the amount of the chalcogen material supplied to the transition metal layer per unit time to less than a predetermined amount, the orientation direction of the formed transition metal chalcogenide layer is controlled to be approximately parallel to the surface of the substrate; An apparatus for manufacturing a transition metal chalcogenide thin film, comprising: an apparatus for manufacturing a transition metal chalcogenide thin film, the apparatus controlling the orientation direction of the formed transition metal chalcogenide layer to a direction approximately perpendicular to the surface of the substrate by making the amount of the chalcogen material supplied to the transition metal layer per unit time greater than a predetermined amount.

14. 14. The apparatus for manufacturing a transition metal chalcogenide thin film according to claim 13, further comprising a film formation unit that heat-treats a substrate having the transition metal layer while supplying the chalcogen material by vapor phase chemical deposition, metalorganic vapor phase deposition, plasma chemical vapor deposition, sulfurization, or sputtering to form a transition metal chalcogenide thin film.

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