Transistor and semiconductor device

Abstract

This transistor includes a first electrode and a second electrode, an oxide semiconductor connecting the first electrode and the second electrode, and a third electrode adjacent to the oxide semiconductor without contacting the oxide semiconductor. At least one of the first electrode and the second electrode is made of a conductive material having physical properties of extracting hydrogen. The oxide semiconductor has a bixbyite structure.

Description

Transistors and semiconductor devices

[0001] This invention relates to transistors and semiconductor devices. Specifically, this invention relates to transistors and semiconductor devices with low operational variability.

[0002] Attempts have been made to apply a transistor having a channel composed of an oxide semiconductor (for example, CAAC-IGZO (indium gallium zinc oxide, which has a hexagonal structure when viewed from the c-axis direction and a layered structure when viewed from a direction perpendicular to the c-axis)) containing indium, element M (where M is aluminum, gallium, yttrium, or tin), and zinc to a DRAM (Dynamic Random Access Memory) (Patent Document 1).

[0003] Japanese Patent Publication No. 2020-053680

[0004] In oxide semiconductors, hydrogen functions as a donor, so transistors using oxide semiconductors with a high hydrogen concentration as the channel layer tend to be normally-on (with a negative threshold voltage). In particular, in miniature transistors such as those used in DRAMs, the semiconductor film thickness is thin, the effect of hydrogen becomes greater, and variations in operation increase. Patent Document 1 attempts to reduce the hydrogen concentration in the oxide semiconductor by composing a conductor that functions as a source electrode or drain electrode using a conductive material that has the property of extracting hydrogen, thereby allowing the conductor to absorb hydrogen from the oxide semiconductor. However, conventional technologies, including Patent Document 1, had room for further improvement in terms of suppressing variations in transistor characteristics.

[0005] One of the objectives of the present invention is to provide transistors and semiconductor devices with low operational variability.

[0006] As a result of diligent research, the present inventors have found that by constructing electrodes that function as source or drain electrodes from a conductive material having properties that allow hydrogen to be extracted, and by using an oxide semiconductor having a bigx-byte structure, hydrogen diffusion into the oxide semiconductor can be suppressed, and as a result, variations in transistor characteristics can be reduced, thus completing the present invention. According to the present invention, the following transistors and the like can be provided: 1. A transistor comprising: a first electrode and a second electrode; an oxide semiconductor connecting the first electrode and the second electrode; and a third electrode adjacent to the oxide semiconductor without contact with the oxide semiconductor, wherein at least one of the first electrode and the second electrode is made of a conductive material having properties that allow hydrogen to be extracted, and the oxide semiconductor has a bigx-byte structure. 2. The transistor according to 1, wherein the first electrode and the second electrode are stacked with at least a first insulating film in between. 3. The transistor according to 2, wherein the oxide semiconductor penetrates at least the first insulating film to connect the first electrode and the second electrode. 4. 1. The transistor according to 2 or 3, further comprising a second insulating film provided between the third electrode and the oxide semiconductor. 5. The transistor according to any one of 2 to 4, wherein the first electrode and the third electrode are stacked via the first insulating film, the third electrode and the second electrode are stacked via the third insulating film, the oxide semiconductor is provided in a columnar shape penetrating the first insulating film, the third electrode, and the third insulating film, and further comprising a second insulating film provided between the third electrode and the oxide semiconductor, the second insulating film being provided so as to surround at least a part of the columnar oxide semiconductor. 6. The transistor according to any one of 2 to 4, wherein the first electrode and the second electrode are stacked via the first insulating film, the oxide semiconductor has a tubular portion provided penetrating the first insulating film, and further comprising a second insulating film provided between the third electrode and the oxide semiconductor, the second insulating film has a tubular portion provided on the inner wall of the tubular portion of the oxide semiconductor, and the third electrode has a portion provided inside the tubular portion of the second insulating film.7. A transistor according to any one of 1 to 6, wherein the channel length of the oxide semiconductor is 1 to 1000 nm. 8. A transistor according to any one of 1 to 7, wherein the oxide semiconductor is mainly composed of indium oxide. 9. A transistor according to any one of 1 to 8, wherein the ratio of indium atoms to all metal atoms contained in the oxide semiconductor is 80 atomic% or more. 10. A transistor according to any one of 1 to 9, wherein the indium oxide content in the oxide semiconductor is 55 mass% or more. 11. A transistor according to any one of 8 to 10, wherein the oxide semiconductor further contains Ga or Al. 12. A transistor according to any one of 8 to 10, wherein the oxide semiconductor further contains Ga. 13. A transistor according to any one of 8 to 10, wherein the oxide semiconductor further contains Ga and Al. 14. A transistor according to any one of 1 to 13, wherein the atomic ratio of Ga to all metal elements contained in the oxide semiconductor ([Ga] / ([Ga] + [all metal elements other than Ga]) × 100) is 0.5 to 25 at%. 15. A transistor according to any one of 1 to 14, wherein the atomic ratio of Zn to all metal elements contained in the oxide semiconductor ([Zn] / ([Zn] + [all metal elements other than Zn]) × 100) is 0 to 3 at%. 16. A transistor according to any one of 1 to 15, wherein the oxide semiconductor substantially does not contain Zn. 17. A transistor according to any one of 1 to 16, wherein the oxide semiconductor has, in order from the third electrode side, a first region, a second region with a lower concentration of indium atoms than the first region, and a third region with a lower concentration of indium atoms than the second region. 18. The composition ratio of the first region is In. Ｘ１ Ga Ｙ１ The composition ratio of the second region is O, and the composition ratio of the second region is In Ｘ２ Ga Ｙ２ The composition ratio of the third region is O, and the composition ratio of the third region is In Ｘ３ Ga Ｙ３A transistor according to 17, wherein the conductive material is O and satisfies the conditions 100 ≥ X1 ≥ X2 ≥ X3 ≥ 50 and 0 ≤ Y1 ≤ Y2 ≤ Y3 ≤ 50. 19. A transistor according to any one of 1 to 18, wherein the conductive material contains Ta. 20. A transistor according to 19, wherein the conductive material further contains N. 21. The composition formula of the conductive material is TaN ｘ O ｙ 21. A transistor according to 19 or 20, wherein 0 < x ≤ 1.67 and 0 ≤ y ≤ 1.0 are satisfied. 22. A transistor according to any one of 1 to 21, wherein at least one of the first electrode and the second electrode has a layer containing Ta and O in at least a portion of the region in contact with the oxide semiconductor. 23. A transistor according to any one of 1 to 22, wherein the oxide semiconductor is a crystalline oxide semiconductor formed by atomic layer deposition. 24. A semiconductor device comprising the transistor according to any one of 1 to 23. 25. A semiconductor device according to 24, which is a semiconductor memory device. 26. A transistor comprising: a first electrode and a second electrode; an oxide semiconductor connecting the first electrode and the second electrode; and a third electrode adjacent to the oxide semiconductor without contact with the oxide semiconductor, wherein the first electrode and the second electrode are stacked with at least a first insulating film in between, at least one of the first electrode and the second electrode is made of a conductive material having the property of extracting hydrogen, the oxide semiconductor is mainly composed of indium oxide and has a bixbite structure, and the atomic ratio of Zn to all metal elements contained in the oxide semiconductor ([Zn] / ([Zn] + [all metal elements other than Zn]) × 100) is 0 to 3 at%.

[0007] According to the present invention, it is possible to provide transistors and semiconductor devices with small variations in operation.

[0008] It is a schematic perspective view showing a cross section of the transistor according to the first embodiment. It is a schematic cross-sectional view of the transistor according to the first embodiment. It is a schematic cross-sectional view of a transistor according to a modification of the first embodiment. It is a schematic cross-sectional view of a transistor according to a further modification of the first embodiment. It is a diagram for explaining an example of the method for manufacturing the transistor according to the first embodiment. It is a schematic perspective view showing a cross section of the transistor according to the second embodiment. It is a schematic cross-sectional view of the transistor according to the second embodiment. It is a schematic cross-sectional view of a transistor according to a modification of the second embodiment. It is a schematic perspective view showing a cross section of the transistor according to the third embodiment. It is a schematic cross-sectional view of the transistor according to the third embodiment. It is a schematic cross-sectional view of a transistor according to a modification of the third embodiment. It is a diagram showing an example of a circuit configuration of a semiconductor memory device. This shows the results of calculating hydrogen diffusivity in a-IGZO (amorphous IGZO), a-In ２ O ３ (amorphous indium oxide), and c-In ２ O ３ (crystalline indium oxide) using molecular dynamics simulation based on first-principles calculations.

[0009] Hereinafter, the transistor and semiconductor device of the present invention will be described in detail. Note that in this specification, "x to y" represents a numerical range of "not less than x and not more than y". The upper and lower limits described for the numerical ranges can be combined arbitrarily. Furthermore, among the individual embodiments of the aspects of the present invention described below, two or more embodiments that do not conflict with each other can be combined, and an embodiment formed by combining two or more embodiments is also an embodiment of the aspect of the present invention.

[0010] 1. Transistor A transistor according to one aspect of the present invention comprises: a first electrode and a second electrode; an oxide semiconductor connecting the first electrode and the second electrode; and a third electrode adjacent to the oxide semiconductor without contact with it, wherein at least one of the first electrode and the second electrode is made of a conductive material having the property of extracting hydrogen, and the oxide semiconductor has a bigxbite structure. The transistor according to this aspect provides the effect of suppressing variations in operation. More specifically, in the transistor according to this aspect, first, at least one of the first electrode and the second electrode is made of a conductive material having the property of extracting hydrogen. By making at least one of the first electrode and the second electrode connected to the oxide semiconductor a conductive material having such properties, hydrogen in the oxide semiconductor can easily diffuse to the electrode, and the hydrogen concentration of the oxide semiconductor can be reduced. However, as in Patent Document 1, even if one attempts to reduce the hydrogen concentration by simply using such an electrode, it is conceivable that the hydrogen concentration may not be sufficiently reduced because hydrogen can diffuse into the oxide semiconductor from the outside (other layers, etc.). In contrast, in this embodiment, the oxide semiconductor has a Bixbite structure with a slow hydrogen diffusion rate, thereby suppressing the diffusion of hydrogen from the outside (other layers, etc.) and significantly reducing the hydrogen concentration in the oxide semiconductor. As a result, variations in transistor operation can be suppressed. Furthermore, while Patent Document 1 describes an oxide semiconductor having a hexagonal crystal structure, the hexagonal crystal structure (hexagonal crystal) is layered, and therefore, especially when applied to fine channels, it may be inferior in terms of strength and stability, such as causing delamination within the hexagonal crystal. In this embodiment, a cubic Bixbite structure is used, which is advantageous from this viewpoint as well.

[0011] (First Embodiment) An example of a transistor according to this embodiment (first embodiment) will be described below with reference to Figures 1 and 2. Figure 1 is a schematic perspective view showing a cross-section of a transistor according to the first embodiment. Figure 2 is a schematic cross-sectional view of the transistor. In this embodiment, the transistor 10 includes a first electrode 11, a second electrode 12, a third electrode 13, an oxide semiconductor 15, a first insulating film 14a, a third insulating film 14b, and a second insulating film 16. The first electrode 11 and the second electrode 12 are stacked via at least the first insulating film 14a (here, the first insulating film 14a and the third insulating film 14b). By having such a structure (vertical structure), the transistor 10 can be arranged at high density in a semiconductor memory device, for example, which also contributes to the miniaturization of the semiconductor memory device. When multiple transistors are arranged at high density, hydrogen diffusion from adjacent transistors is likely to occur. However, in this embodiment, at least one of the first electrode and the second electrode is made of a conductive material having properties that extract hydrogen, and the oxide semiconductor has a bigxbite structure. These factors work synergistically to significantly reduce the hydrogen concentration in the oxide semiconductor. As a result, even when multiple transistors are arranged at high density, variations in the operation of the transistors can be suppressed. The term "stacked" here may mean that at least a portion of the first electrode 11 and at least a portion of the second electrode 12 are arranged along a direction perpendicular to the plane direction of the substrate (not shown) supporting the transistor 10. Also, although not shown, when multiple transistors 10 are connected in a planar manner (in the X-Y direction) (when multiple transistors 10 form a transistor array), at least a portion of the first electrode 11 and at least a portion of the second electrode 12 may be arranged along a direction perpendicular to the plane direction (Z direction). The first insulating film 14a (here, the first insulating film 14a and the third insulating film 14b) may have at least a portion interposed between the first electrode 11 and the second electrode 12. The third electrode 13 is located between the first electrode 11 and the second electrode 12.

[0012] Of the first insulating film 14a and the third insulating film 14b, the first insulating film 14a is located between the first electrode 11 and the third electrode 13. As a result, the first electrode 11 and the third electrode 13 are electrically insulated by the first insulating film 14a. The third insulating film 14b is located between the second electrode 12 and the third electrode 13. As a result, the second electrode 12 and the third electrode 13 are electrically insulated by the third insulating film 14b.

[0013] In the region shown in Figure 2, the third electrode 13 is positioned between the first insulating film 14a and the third insulating film 14b. However, outside the region shown in Figure 2, the first insulating film 14a and the third insulating film 14b may be in contact with each other, forming a single layer. In this case, the third electrode 13 does not need to be positioned between the first insulating film 14a and the third insulating film 14b in that region.

[0014] The oxide semiconductor 15 penetrates at least the first insulating film 14a and is provided to connect the first electrode 11 and the second electrode 12. The oxide semiconductor 15 may also penetrate the third electrode 13 in addition to the first insulating film 14a and the third insulating film 14b. Here, the oxide semiconductor 15 is provided in a columnar shape, penetrating the first insulating film 14a, the third electrode 13, and the third insulating film 14b in this order. In this case, it is preferable that the third electrode 13 surrounds the entire circumference of the oxide semiconductor 15 (around the periphery in the direction perpendicular to the length direction) in a portion of the oxide semiconductor 15 in the longitudinal direction (the central portion in the example of Figure 2) via the second insulating film 16 described later. This makes it easier to prevent leakage current even if the channel length of the oxide semiconductor 15 described later is shortened. At the same time, it is also advantageous in terms of miniaturization. Furthermore, the length direction of the oxide semiconductor 15 as referred to here may be the vertical direction in Figure 2 (the direction connecting the first electrode and the second electrode), the direction along the channel length described later, the thickness direction of the laminate in which the first insulating film 14a, the third electrode 13, and the third insulating film 14b are stacked in this order, and, if the oxide semiconductor 15 is columnar, the height direction of the columnar structure.

[0015] The second insulating film 16 is provided between the third electrode 13 and the oxide semiconductor 15. The oxide semiconductor 15, the second insulating film 16, and the third electrode 13 are arranged in this order. The second insulating film 16 may be provided between the third electrode 13 and the oxide semiconductor 15 to insulate them. In addition to being provided between the third electrode 13 and the oxide semiconductor 15, the second insulating film 16 may also be provided, for example, between the first insulating film 14a and / or the third insulating film 14b and the oxide semiconductor 15. The second insulating film 16 is provided so as to surround the entire circumference of the side surface of the columnar oxide semiconductor 15.

[0016] From one perspective, the transistor 10 can be described as having a laminate in which a first insulating film 14a, a third electrode 13, and a third insulating film 14b are stacked in this order, with a through-hole penetrating the laminate in the thickness direction (vertical direction in Figures 1 and 2), the inner circumferential surface of the through-hole being covered with a cylindrical second insulating film 16, and the inside of the cylindrical second insulating film 16 being filled with an oxide semiconductor 15.

[0017] The dimensions of the transistor 10 may be designed as appropriate depending on its application. The channel length of the oxide semiconductor 15 is, for example, 1 nm to 10 μm, preferably 2 to 1000 nm, more preferably 3 to 100 nm, even more preferably 4 to 50 nm, even more preferably 5 to 30 nm, and even more preferably 6 to 20 nm. The channel length of the oxide semiconductor 15 is the length of the oxide semiconductor 15 along the thickness direction (vertical direction in Figures 1 and 2) of the laminate in which the first insulating film 14a, the third electrode 13, and the third insulating film 14b are stacked in this order, and may coincide with the distance between the first electrode 11 and the second electrode 12. If the oxide semiconductor 15 is columnar, the channel length of the oxide semiconductor 15 corresponds to the height of the columnar structure. The channel length of the oxide semiconductor 15 can be measured by processing the relevant area with a focused ion beam (FIB) to expose it and observing the cross-section with a transmission electron microscope (TEM).

[0018] The channel length of the oxide semiconductor 15 is not particularly limited, but is preferably 1 to 1000 nm, more preferably 1 to 500 nm, and more preferably 2 to 500 nm. By having such a fine channel length, the number of grain boundaries in the oxide semiconductor 15 can be reduced (or made zero). Since grain boundaries can become hydrogen diffusion pathways, reducing them effectively suppresses hydrogen diffusion. The "channel length" of the oxide semiconductor 15 is the distance (length) between the first electrode 11 and the second electrode 12 connected by the oxide semiconductor 15, which is the channel.

[0019] The channel width of the oxide semiconductor 15 is, for example, 1 nm to 1000 nm, preferably 2 nm to 500 nm. The channel width of the oxide semiconductor 15 is the length of the oxide semiconductor 15 along the direction perpendicular to the thickness direction (for example, the left-right direction in Figure 2) of the laminate in which the first insulating film 14a, the third electrode 13, and the third insulating film 14b are stacked in this order. As shown in Figures 1 and 2, if the channel width of the oxide semiconductor 15 is not constant with respect to the channel length direction, the channel width of the oxide semiconductor 15 may be the average width along the channel length direction. The average width along the channel length direction is the average value obtained when the channel width is measured at 10 or more locations along the channel length direction. If the oxide semiconductor 15 is columnar, the channel width of the oxide semiconductor 15 corresponds to the width of the columnar structure. Furthermore, if the channel width of the oxide semiconductor 15 differs depending on the observation direction (for example, if the channel width differs when observed from a direction perpendicular to the plane of Figure 2 and when observed from the left or right direction in Figure 2), the channel width when observed from at least one direction may be within the above range.

[0020] The thickness of the second insulating film 16 is, for example, 1 Å to 500 nm, preferably 1 nm to 100 nm. In order to suppress the capacitance of the second insulating film 16 from becoming a parasitic component, the thickness of the second insulating film 16 may be 50 nm or less, 10 nm or less, or 2 nm or less within the above range. The channel width of the oxide semiconductor 15 and the thickness of the second insulating film 16 can be measured in the same manner as the channel length of the oxide semiconductor 15.

[0021] In transistor 10, the first electrode 11 can function as a source electrode, and the second electrode 12 can function as a drain electrode. In other examples, the first electrode 11 can function as a drain electrode, and the second electrode 12 can function as a source electrode. The third electrode 13 can function as a gate electrode. The oxide semiconductor 15 can function as a channel (current path) of transistor 10. For example, when a gate voltage is applied to the third electrode 13, which is the gate electrode, the first electrode 11 and the second electrode 12 are electrically connected by the oxide semiconductor 15, and transistor 10 is in the ON state. When no gate voltage is applied, the electrical connection between the first electrode 11 and the second electrode 12 by the oxide semiconductor 15 is released, and transistor 10 is in the OFF state.

[0022] Furthermore, in this specification, "electrically connected" includes cases where connections are made via "something that has some kind of electrical function." Here, "something that has some kind of electrical function" is not particularly limited as long as it enables the exchange of electrical signals between the connected objects.

[0023] In the transistor 10, the oxide semiconductor 15 is provided to connect the first electrode 11 and the second electrode 12. "Provided to connect the first electrode 11 and the second electrode 12" means that it is provided in a state in which the first electrode 11 and the second electrode 12 can be electrically connected. Therefore, the oxide semiconductor 15 does not need to be in physical contact with the first electrode 11 and the second electrode 12. For example, a conductive material (conductor) may be provided between the oxide semiconductor 15 and the first electrode 11 and / or the second electrode 12, or an insulating material (insulator) may be provided to the extent that conductivity (electrical connection) is ensured.

[0024] As described above, in this embodiment, the transistor 10 is configured such that at least one of the first electrode 11 and the second electrode 12 is made of a conductive material having the property of extracting hydrogen. By having at least one of the first electrode 11 and the second electrode 12 connected to the oxide semiconductor 15 made of a conductive material having such properties, hydrogen in the oxide semiconductor 15 can easily diffuse to the electrode, and the hydrogen concentration of the oxide semiconductor 15 can be reduced. However, as in Patent Document 1, even if one attempts to reduce the hydrogen concentration simply by using such electrodes, hydrogen can diffuse into the oxide semiconductor from the outside (other layers, etc.), so it is conceivable that the hydrogen concentration will not be sufficiently reduced. In contrast, in this embodiment, the oxide semiconductor 15 has a Bix-byte structure with a slow hydrogen diffusion rate, thereby suppressing the diffusion of hydrogen from the outside (other layers, etc.) and significantly reducing the hydrogen concentration of the oxide semiconductor 15. As a result, variations in the operation of the transistor can be suppressed.

[0025] As described above, the oxide semiconductor 15 has a Bixbite structure. The presence or absence of a Bixbite structure can be determined based on the X-ray diffraction pattern in X-ray diffraction (XRD) or the electron diffraction spots in electron diffraction (particularly the TEM-ED described above).

[0026] In one embodiment, the oxide semiconductor 15 is mainly composed of indium oxide. "Mainly composed of indium oxide" means that more than 50% by mass of the material constituting the crystalline oxide semiconductor 15 is indium oxide.

[0027] In one embodiment, the ratio of indium atoms to the total metal atoms contained in the oxide semiconductor 15 is 80 atomic% or more, 90 atomic% or more, or 95 atomic% or more. The content (atomic ratio) of each metal element in the oxide semiconductor 15 can be analyzed by TEM-EDS (Energy Dispersive X-ray Spectroscopy) measurement using an electron microscope.

[0028] In one embodiment, the oxide semiconductor 15 has a bixbite structure mainly composed of indium oxide and may contain other metal atoms. For example, in addition to indium oxide (IO), the oxide semiconductor 15 may contain indium gallium oxide (IGO), in which gallium is dissolved in the main component indium oxide, or indium gallium aluminum oxide (IGAO), in which gallium and aluminum are dissolved in the main component indium oxide. In one embodiment, the indium oxide content of the oxide semiconductor 15 may be 55% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, 97% by mass or more, 98% by mass or more, or 99% by mass, and may be substantially 100% by mass. In the case of "substantially 100% by mass", unavoidable impurities may be included.

[0029] In one embodiment, the oxide semiconductor 15 contains indium oxide and further contains a trivalent metal. The trivalent metal is preferably Ga and Al, with Ga being more preferred. In one embodiment, the crystalline oxide semiconductor further contains Ga or Al, may contain Ga, may contain Al, or may contain both Ga and Al. In one embodiment, the atomic ratio of the trivalent metal to all metal elements contained in the oxide semiconductor 15 ([trivalent metal] / ([trivalent metal] + [all metal elements other than the trivalent metal]) × 100) may be 0 to 30 at%, 0.5 to 25 at%, 1.0 to 22 at%, 1.5 to 20 at%, 2.0 to 15 at%, or 3.0 to 10 at%. Here, "trivalent metal" may be read as Ga and Al. In one embodiment, the atomic ratio of Ga to all metal elements contained in the oxide semiconductor 15 ([Ga] / ([Ga] + [all metal elements other than Ga]) × 100) may be 0 to 30 at%, 0.5 to 25 at%, 1.0 to 22 at%, 1.5 to 20 at%, 2.0 to 15 at%, or 3.0 to 10 at%. In one embodiment, the atomic ratio of Al to all metal elements contained in the oxide semiconductor 15 ([Al] / ([Al] + [all metal elements other than Al]) × 100) may be 0 to 30 at%, 0.5 to 25 at%, 1.0 to 22 at%, 1.5 to 20 at%, 2.0 to 15 at%, or 3.0 to 10 at%.

[0030] When the oxide semiconductor 15 contains Ga, it is preferable because it tends to enlarge the crystal grains of the oxide semiconductor 15 and reduce the number of crystal grain boundaries in the oxide semiconductor 15. This is because crystal grain boundaries can serve as pathways for hydrogen diffusion.

[0031] In one embodiment, the oxide semiconductor 15 further contains one or more additive elements selected from B, Si, Sc, Zn, Ce, Y, Zr, Sn, Sm, Hf, Ta, and Yb. In one embodiment, the atomic ratio of the total amount of additive elements to the total amount of metal elements contained in the oxide semiconductor 15 ([total amount of additive elements] / ([total amount of additive elements] + [total metal elements other than additive elements]) × 100) is 0 to 10 at%, and may be 0.1 to 8 at%, 0.5 to 5 at%, or 1 to 3 at%.

[0032] In one embodiment, the oxide semiconductor 15 does not need to contain Zn. The atomic ratio of Zn to all metal elements contained in the oxide semiconductor 15 ([amount of Zn] / ([amount of Zn] + [amount of all metal elements other than Zn]) × 100) is 0 to 3 at%, and may be 0 to 1 at%, 0 to 0.1 at%, 0 to 0.01 at%, or substantially 0 at%. In the case of "substantially 0 at%," the oxide semiconductor 15 may contain Zn as an unavoidable impurity. Since Zn has the property of absorbing water molecules (including hydrogen and oxygen atoms), a low Zn content in the oxide semiconductor 15, and especially the absence of Zn in the oxide semiconductor 15, can reduce the hydrogen and oxygen concentrations in the oxide semiconductor 15 and suppress the diffusion of hydrogen and oxygen into the oxide semiconductor 15. This makes it possible to provide transistors with even less variation.

[0033] As described above, at least one of the first electrode 11 and the second electrode 12 is made of a conductive material having the property of extracting hydrogen. In one embodiment, both the first electrode 11 and the second electrode 12 are made of a conductive material having the property of extracting hydrogen. Note that "having the property of extracting hydrogen" means that the hydrogen storage capacity of the electrode made of the conductive material is higher than the hydrogen storage capacity of the oxide semiconductor.

[0034] Examples of conductive materials having the property of extracting hydrogen include conductive materials containing one or more elements selected from the group consisting of Ta (tantalum atoms) and Ti (titanium atoms), with conductive materials containing Ta being particularly preferred. Furthermore, conductive materials having the property of extracting hydrogen preferably contain Ta and also N (nitrogen atoms). Furthermore, conductive materials having the property of extracting hydrogen preferably contain Ta and also N and O (oxygen atoms). In one embodiment, the compositional formula of the conductive material having the property of extracting hydrogen (or an electrode composed of said conductive material) is TaN ｘ O ｙ (However, the conditions 0 < x ≤ 1.67 and 0 ≤ y ≤ 1.0 are satisfied.) This provides better hydrogen extraction properties. Specific examples of conductive materials having hydrogen extraction properties include metallic tantalum, tantalum oxide, tantalum nitride, nitrided tantalum oxide, oxynitrided tantalum, etc., and at least one of the first electrode 11 and the second electrode 12 may contain one or more selected from these conductive materials.

[0035] These conductive materials, especially TaN ｘ O ｙ This material is suitable because it is a conductive material in which hydrogen diffuses easily and oxygen does not diffuse easily. The first electrode 11 and / or the second electrode 12 are made of TaN ｘ O ｙ By configuring the material in this way, during heat treatment in the process following the formation of the conductive film that forms the first electrode 11 and / or the second electrode 12, hydrogen in the oxide semiconductor 15 diffuses to the first electrode 11 and / or the second electrode 12, thereby reducing the hydrogen concentration in the oxide semiconductor 15.

[0036] The above Tan ｘ O ｙ In the composition formula, a high proportion of Ta (or small values ​​of x and y) can improve the conductivity of electrodes made of the conductive material. ｘ O ｙIn the composition formula, a high ratio of N (or a large value of x) can suppress oxidation of the electrode made of the conductive material, and can also reduce the thickness of the layer containing Ta and O (details will be described later) that may be formed by such oxidation.

[0037] Figure 3 illustrates an example of a transistor (a modified example of the first embodiment) in which layers 111 and 121 containing Ta and O are formed in the regions of the first electrode 11 and second electrode 12 that are in contact with the oxide semiconductor 15, respectively, and shows a cross-section similar to that of Figure 2. In this embodiment, the layers 111 and 121 containing Ta and O may be read as layers containing other metal elements and oxygen contained in a conductive material having the property of extracting hydrogen, respectively. In the example of Figure 3, both the first electrode 11 and the second electrode 12 are made of a conductive material having the property of extracting hydrogen. Here, the first electrode 11 extracts oxygen from the oxide semiconductor 15, thereby forming the layer 111 containing Ta and O in the region of the first electrode 11 that is in contact with the oxide semiconductor 15. Similarly, the second electrode 12 extracts oxygen from the oxide semiconductor 15, thereby forming the layer 121 containing Ta and O in the region of the second electrode 12 that is in contact with the oxide semiconductor 15. Compared to, for example, CAAC-IGZO or oxide semiconductors with a hexagonal crystal structure, the oxide semiconductor 15 having a bixbite structure is less prone to oxygen loss. Therefore, even when layers 111 and 112 containing Ta and O are formed, the oxide semiconductor 15 can maintain its semiconductor function well.

[0038] The layers 111 and 121 containing Ta and O contain more oxygen than other regions of the first electrode 11 and second electrode 12, and therefore may have insulating properties. In this case, the three-layer structure of the other regions of the first electrode 11 (or second electrode 12), the layer 111 (or layer 121) containing Ta and O, and the oxide semiconductor 15 can be considered a three-layer structure consisting of a metal-insulator-semiconductor. This is also called an MIS (Metal-Insulator-Semiconductor) structure.

[0039] On the other hand, the region 151 in the oxide semiconductor 15 that is in contact with the first electrode 11 may contain many oxygen vacancies. Similarly, the region 152 in the oxide semiconductor 15 that is in contact with the second electrode 12 may also contain many oxygen vacancies. In this case, in regions 151 and 152, impurities (such as hydrogen) that have entered the oxygen vacancies may function as donors, increasing the carrier density and forming low-resistance regions.

[0040] The thicker the layers 111 and 121 containing Ta and O become, the larger the regions 151 and 152 can become. From the viewpoint of reducing variations in transistor operation, it is preferable not to excessively enlarge regions 151 and 152, and for this purpose, it is preferable to form the layers 111 and 121 containing Ta and O thinly. When the first electrode 11 and the second electrode 12 are formed using conductive materials that are resistant to oxidation, the layers 111 and 112 containing Ta and O, which may have insulating properties, can be formed thinly so as to ensure good carrier movement between the first electrode 11 and the oxide semiconductor 15 (and between the second electrode 12 and the oxide semiconductor 15). Thinly formed layers 111 and 112 containing Ta and O can suppress the deterioration of the electrode-oxide semiconductor interface during annealing. Each of the conductive materials exemplified as having properties to extract hydrogen possesses not only properties to extract hydrogen but also oxidation resistance (oxygen in the oxide semiconductor does not easily diffuse to the electrodes), so layers 111 and 112 containing Ta and O can be formed thinly. The thinness of layers 111 and 112 containing Ta and O also has the effect of making it less likely for the diffusion of hydrogen from the oxide semiconductor 15 to the electrodes to be inhibited.

[0041] From the above perspective, the film thickness of layers 111 and 112 containing Ta and O is, for example, 0.1 nm to 4 nm, preferably 0.5 nm to 3 nm.

[0042] Furthermore, the film thickness of layers 111 and 112 containing Ta and O can sometimes be measured by observing the cross-sectional shape, including the periphery of layers 111 and 112 containing Ta and O, using a transmission electron microscope (TEM). In addition, the film thickness of layers 111 and 112 containing Ta and O can sometimes be calculated by performing line analysis of the composition using energy-dispersive X-ray spectroscopy (EDX) on the periphery of layers 111 and 112 containing Ta and O.

[0043] The above description mainly illustrates the case where at least one of the first electrode 11 and the second electrode 12 has layers 111 and 121 containing Ta and O throughout the entire region in contact with the oxide semiconductor 15, but is not limited to this. At least one of the first electrode 11 and the second electrode 12 may have layers 111 and 121 containing Ta and O in a part of the region in contact with the oxide semiconductor 15. Also, one or both of the layers 111 and 121 containing Ta and O may not be formed. The above description mainly illustrates the case where the oxide semiconductor 15 contains many oxygen vacancies in each of the regions 151 in contact with the first electrode 11 and 152 in contact with the second electrode 12, but is not limited to this. One or both of the regions 151 in contact with the first electrode 11 and 152 in contact with the second electrode 12 may not contain many oxygen vacancies. The above description of layers 111, 121 and regions 151, 152 containing Ta and O may be applied to the second and third embodiments described later.

[0044] The third electrode 13 is not particularly limited as long as it is a conductor. Examples of conductors include indium tin oxide (ITO), indium zinc oxide (IZO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), aluminum (Al), silicon (Si), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), germanium (Ge), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), tantalum (Ta), iridium (Ir), platinum (Pt), tungsten (W), titanium (Ti), titanium nitride (TiN), aluminum nitride (AlN), manganese nitride (MnN), molybdenum nitride (MoN), and nickel nitride (Ni3N).

[0045] The first insulating film 14a, the second insulating film 16, and the third insulating film 14b are not particularly limited as long as they contain an insulator or are films made of an insulator. Examples of insulators include aluminum oxide, magnesium oxide, silicon oxide, silicon oxide nitride, silicon oxide nitride, silicon nitride, gallium oxide, germanium oxide, yttrium oxide, zirconium oxide, lanthanum oxide, neodymium oxide, hafnium oxide, and tantalum oxide. Furthermore, the first insulating film 14a, the second insulating film 16, and the third insulating film 14b may each be a laminated film of the above materials. The insulating films may also contain La, N, Zr, etc. The insulators contained in the first insulating film 14a, the second insulating film 16, and the third insulating film 14b may be the same or different from each other.

[0046] Next, a further modification of the first embodiment will be described with reference to Figure 4. The transistor 10 shown in Figure 4 is the same as the embodiment described above, except that the configuration of the oxide semiconductor 15 is different, and the description of the embodiment described above will be applied. In this modification, the oxide semiconductor 15 has a first region 15a, a second region 15b, and a third region 15c, in that order from the third electrode 13 side. Here, the concentration of indium atoms in the second region 15b is lower than that of the first region 15a. Also, the concentration of indium atoms in the third region 15c is lower than that of the second region 15b. Therefore, it can be said that the concentration of indium atoms is increasing in the order of the third region 15c, the second region 15b, and the first region 15a. By forming a difference in the concentration of indium atoms in each region of the oxide semiconductor 15 in this way, the effect of achieving both high mobility and low leakage can be obtained. In this modification, the composition ratio of the first region 15a is In Ｘ１ Ga Ｙ１ O, and the composition ratio of the second region 15b is In Ｘ２ Ga Ｙ２ It is O, and the composition ratio of the third region 15c is In Ｘ３ Ga Ｙ３ It is preferable that the following conditions are met: 0, 100 ≥ X1 ≥ X2 ≥ X3 ≥ 50, and 0 ≤ Y1 ≤ Y2 ≤ Y3 ≤ 50. This provides the effect of achieving both high mobility and low leakage. In this modified example, the first region 15a is formed in a cylindrical shape so as to be in contact with the inner circumferential surface of the cylindrical second insulating film 16. The second region 15b is also formed in a cylindrical shape so as to be in contact with the inner circumferential surface of the cylindrical first region 15a. Furthermore, the third region 15c is formed inside the cylindrical second region 15b so as to fill (fill) the inside. The above describes a modified example in which the oxide semiconductor 15 has a first region 15a, a second region 15b, and a third region 15c. However, in other modified examples, the second region 15b may be omitted, and the first region 15a and the third region 15c may be provided so as to be in contact with each other (in this case, "third region" may be read as "second region"). The concentration and composition ratio of indium atoms in each region of the oxide semiconductor 15 can be measured by TEM-EDS (Energy Dispersive X-ray Spectroscopy) using an electron microscope.

[0047] An example of a manufacturing method for the transistor 10 according to this embodiment is described below, but the manufacturing method is not limited to this example.

[0048] Figure 5 illustrates an example of a method for manufacturing the transistor 10 according to this embodiment. Figure 5(a) shows the oxide semiconductor 15, the second electrode 12, and the insulating film 19 supporting the second electrode 12 as shown in Figures 1 and 2. Although not shown in Figure 5(a), the second electrode 12 and the insulating film 19 may be formed on another substrate. The second electrode 12 may also be connected to an element outside the transistor according to this embodiment. The insulating film 19 and the second electrode 12 can be formed by known methods.

[0049] Next, as shown in Figure 5(b), the third insulating film 14b, the third electrode 13, and the first insulating film 14a are formed in this order. At this time, as will be described later, the third electrode 13 may be formed to be connected to the word line. Alternatively, the third electrode 13 itself may be used as the word line.

[0050] The third insulating film 14b is formed by, for example, depositing a film containing the above-mentioned insulator by various methods such as chemical vapor deposition (CVD), plasma CVD (PECVD), physical vapor deposition (PVD), atomic layer deposition (ALD), pulsed laser deposition (PLD), sol-gel method, and coating method.

[0051] The third electrode 13 is formed by depositing a conductive material such as tungsten, as described above. The third electrode 13 may be patterned into any shape. The pattern of the third electrode 13 may be formed during film deposition, or it may be formed by etching after film deposition.

[0052] The first insulating film 14a is formed by depositing a film containing the above-mentioned insulator using various methods such as chemical vapor deposition (CVD), plasma CVD (PECVD), physical vapor deposition (PVD), atomic layer deposition (ALD), pulsed laser deposition (PLD), sol-gel method, and coating method.

[0053] Next, as shown in Figure 5(c), through-holes H are formed by etching, penetrating the first insulating film 14a, the third electrode 13, and the third insulating film 14b. Various etching methods, such as dry etching and wet etching, may be used to form the through-holes H. Alternatively, a resist film may be deposited on the first insulating film 14a before etching to define the region where the through-holes H will be formed.

[0054] Next, as shown in Figure 5(d), a second insulating film 16 containing the above-described insulator is formed by various methods such as chemical vapor deposition (CVD), plasma CVD (PECVD), physical vapor deposition (PVD), atomic layer deposition (ALD), pulsed laser deposition (PLD), sol-gel method, and coating method.

[0055] Next, as shown in Figure 5(e), an oxide semiconductor 15 is formed in the through-hole H where the second insulating film 16 is formed. Methods for forming the oxide semiconductor 15 include chemical vapor deposition (CVD), plasma CVD (PECVD), physical vapor deposition (PVD), atomic layer deposition (ALD), pulsed laser deposition (PLD), sol-gel method, and coating method. CVD methods include metal-organic CVD (MO-CVD), inductively coupled plasma CVD (ICP-CVD), and mist CVD. PVD methods include DC sputtering, AC sputtering, RF sputtering, ICP sputtering, reactive sputtering, and ion plating. The oxide semiconductor 15 may also be formed as a crystalline oxide semiconductor by first forming an amorphous oxide semiconductor and then performing post-annealing as described later. A crystalline oxide semiconductor may be formed by performing post-annealing after the formation of an amorphous oxide semiconductor, or post-annealing may be performed after the oxide semiconductor has crystallized and a crystalline oxide semiconductor has been formed. Alternatively, a crystalline oxide semiconductor may be formed without post-annealing, or post-annealing may be performed after the formation of the crystalline oxide semiconductor to adjust the crystallinity of the crystalline oxide semiconductor.

[0056] It is preferable to perform post-annealing on the oxide semiconductor 15 formed in the process shown in Figure 5(e). Post-annealing can be performed after the deposition of the oxide semiconductor film, for example, after or before the formation of the first electrode 11 in the subsequent step. The state of the oxide semiconductor before post-annealing may be amorphous or crystalline. The annealing atmosphere may contain nitrogen or oxygen and may be under vacuum or air. The annealing temperature is preferably 250°C to 600°C, more preferably 300°C to 500°C, and even more preferably 350°C to 450°C. The annealing time is 5 minutes to 2 hours, preferably 30 minutes to 1 hour. The oxide semiconductor 15 can be formed by atomic layer deposition (ALD), which will be described later.

[0057] Next, as shown in Figure 5(f), a first electrode 11 is formed on the upper layer of the oxide semiconductor 15. The first electrode 11 may be patterned into any shape. The first electrode 11 may have a pattern formed during film deposition, or it may have a pattern formed by etching after film deposition.

[0058] As described above, a transistor 10 as shown in Figures 1 and 2 can be obtained.

[0059] In the first embodiment, the case was shown in which the second insulating film 16 completely surrounds the side surface of the columnar oxide semiconductor 15, but it is not necessarily limited to this, and for example, the second insulating film 16 may surround at least a part of the columnar oxide semiconductor 15.

[0060] In the manufacturing method described above, the oxide semiconductor 15 is formed in the through-hole H where the second insulating film 16 is formed. Therefore, atomic layer deposition (ALD) is preferred as the method for forming the oxide semiconductor 15. Atomic layer deposition (ALD) is a thin film formation method in which a process of alternately exposing a raw material (sometimes called a precursor) containing a metal element constituting the film to be deposited (here, the oxide semiconductor 15) and an oxidizing agent to the substrate surface constitutes one cycle, forming one atomic layer in one cycle, and repeating this cycle until the desired film thickness is achieved. Therefore, by using ALD, a dense oxide semiconductor 15 can be formed even in the region near the second electrode 12, which is far from the opening, in the through-hole H where the second insulating film 16 is formed.

[0061] A single atomic layer deposition cycle of ALD may include the following four steps: (1) The precursor, which is the raw material, is vaporized in a container and introduced into the chamber. A predetermined system pressure is applied and the precursor is reacted with the OH groups on the substrate surface or film surface for a predetermined time to adsorb single molecules. If the vapor pressure of the precursor is low, the container containing the precursor may be heated to promote vaporization, and if the vapor pressure of the precursor is high, the container containing the precursor may be cooled to suppress vaporization and adjust the process. (2) Unreacted raw materials and by-product gases are removed from the chamber by purging with an inert gas, and one atomic layer is deposited. (3) A reactive gas is introduced into the chamber, and the metal of the precursor is oxidized using heat, plasma, etc. (4) Unreacted oxidizing agents and by-product gases are removed by purging with an inert gas. After step (4), the process returns to step (1), and steps (1) to (4) may be repeated until the desired film thickness is achieved.

[0062] When performing ALD, various ALD devices can be used. Specifically, examples include devices that can supply a precursor by bubbling, and devices that have a vaporization chamber. Also, devices that can perform plasma treatment on the reactive gas (oxidizer) can be used. Furthermore, not only single-wafer devices equipped with a film deposition chamber, but also devices that can process multiple sheets simultaneously using a batch furnace may be used.

[0063] Examples of ALD precursors include organometallic (e.g., AlMe) ３ ), metal hydrides (e.g., AshH ３ ), metal alkoxides (for example, Ti(OCHMe ２ ) ４ ), metal amides (for example, Ti (NME ２ ) ４ ), β-diketonate (for example, Co(acac) ２ ), metallocene (for example, MgCp ２ Examples include metal amidinates, etc. Various metal compounds are commercially available for use as ALD precursors, and one should select a precursor and oxidizing agent that can form the desired film.

[0064] Examples of precursors include compounds of silicon or metals, which consist of one or more compounds selected from the group consisting of compounds used as organic ligands, such as alkyl compounds, alcohol compounds, glycol compounds, β-diketone compounds, cyclopentadiene compounds, and organic amine compounds.

[0065] Examples of precursor metal species include lithium, sodium, potassium, magnesium, calcium, strontium, barium, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, iron, ruthenium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver, gold, zinc, boron, aluminum, silicon, indium, gallium, germanium, tin, lead, antimony, bismuth, scandium, ruthenium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.

[0066] If the oxide semiconductor 15 contains indium atoms (In), an In-containing precursor may be used. If the oxide semiconductor 15 contains other metals, a precursor containing those metals may be used. When forming an oxide semiconductor using two or more metals, there are two methods: vaporizing and supplying each component independently (sometimes referred to as the "single-source method") and vaporizing and supplying a mixed raw material in which multi-component raw materials are pre-mixed to a desired composition (sometimes referred to as the "cocktail-source method"). In the single-source method, it is preferable that each precursor used has similar thermal and / or oxidative decomposition behavior. In the cocktail-source method, it is preferable that each precursor has similar thermal and / or oxidative decomposition behavior and does not undergo alteration due to chemical reactions during mixing.

[0067] The following are examples of compounds that can be used as organic ligands for precursors. Furthermore, depending on the valency of the central metal, multiple ligands from the following list may coordinate. In a precursor, when multiple ligands coordinate to the central metal, these ligands may be identical to each other, or two or more ligands may be combined.

[0068] Alkyl compounds used as organic ligands for precursors include methyl, ethyl, propyl, isopropyl, butyl, 2-butyl, isobutyl, 3-butyl, pentyl, isopentyl, and 3-pentyl.

[0069] Alcohol compounds used as organic ligands for precursors include alkyl alcohols such as methanol, ethanol, propanol, isopropyl alcohol, butanol, 2-butyl alcohol, isobutyl alcohol, 3-butyl alcohol, pentyl alcohol, isopentyl alcohol, and 3-pentyl alcohol; 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2-(2-methoxyethoxy)ethanol, 2-methoxy-1-methylethanol, 2-methoxy-1,1-dimethylethanol, 2-ethoxy-1,1-dimethylethanol, 2-isopropoxy-1,1-dimethylethanol, and 2-butoxy Examples include ether alcohols such as -1,1-dimethylethanol, 2-(2-methoxyethoxy)-1,1-dimethylethanol, 2-propoxy-1,1-diethylethanol, 2-s-butoxy-1,1-diethylethanol, and 3-methoxy-1,1-dimethylpropanol; and dialkylamino alcohols such as dimethylaminoethanol, ethylmethylaminoethanol, diethylaminoethanol, dimethylamino-2-pentanol, ethylmethylamino-2-pentanol, dimethylamino-2-methyl-2-pentanol, ethylmethylamino-2-methyl-2-pentanol, and diethylamino-2-methyl-2-pentanol.

[0070] Examples of glycol compounds used as organic ligands for precursors include 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 2,4-hexanediol, 2,2-dimethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 1,3-butanediol, 2,4-butanediol, 2,2-diethyl-1,3-butanediol, 2-ethyl-2-butyl-1,3-propanediol, 2,4-pentanediol, 2-methyl-1,3-propanediol, 2-methyl-2,4-pentanediol, 2,4-hexanediol, and 2,4-dimethyl-2,4-pentanediol.

[0071] Examples of β-diketone compounds used as organic ligands for precursors include acetylacetone, hexane-2,4-dione, 5-methylhexane-2,4-dione, heptane-2,4-dione, 2-methylheptane-3,5-dione, 5-methylheptane-2,4-dione, 6-methylheptane-2,4-dione, 2,2-dimethylheptane-3,5-dione, 2,6-dimethylheptane-3,5-dione, 2,2,6-trimethylheptane-3,5-dione, 2,2,6,6-tetramethylheptane-3,5-dione, octane-2,4-dione, 2,2,6-trimethyloctane-3,5-dione, 2,6-dimethyloctane-3,5-dione, 2,9-dimethylnonane-4,6-dione, and 2-methyl-6-ethyl Examples include alkyl-substituted β-diketones such as decane-3,5-dione and 2,2-dimethyl-6-ethyldecane-3,5-dione; fluorine-substituted alkyl β-diketones such as 1,1,1-trifluoropentane-2,4-dione, 1,1,1-trifluoro-5,5-dimethylhexane-2,4-dione, 1,1,1,5,5,5-hexafluoropentane-2,4-dione, and 1,3-diperfluorohexylpropane-1,3-dione; and ether-substituted β-diketones such as 1,1,5,5-tetramethyl-1-methoxyhexane-2,4-dione, 2,2,6,6-tetramethyl-1-methoxyheptane-3,5-dione, and 2,2,6,6-tetramethyl-1-(2-methoxyethoxy)heptane-3,5-dione.

[0072] Examples of cyclopentadiene compounds used as organic ligands for precursors include cyclopentadiene, methylcyclopentadiene, ethylcyclopentadiene, propylcyclopentadiene, isopropylcyclopentadiene, butylcyclopentadiene, 2-butylcyclopentadiene, isobutylcyclopentadiene, 3-butylcyclopentadiene, dimethylcyclopentadiene, and tetramethylcyclopentadiene.

[0073] Examples of organic amine compounds used as organic ligands for precursors include methylamine, ethylamine, propylamine, isopropylamine, butylamine, 2-butylamine, 3-butylamine, isobutylamine, dimethylamine, diethylamine, dipropylamine, diisopropylamine, ethylmethylamine, propylmethylamine, and isopropylmethylamine.

[0074] In addition, metal halogen compounds (e.g., InCl ３ InBr ３ InF ３ (etc.) may be used as precursors. When multiple halogens coordinate to a metal, these halogens may be identical to each other, or two or more halogens may be combined. In addition, some of the halogens may be replaced with hydrogen.

[0075] Examples of indium-containing precursors include InCl ３ , TMIn (trimethyl indium), TEIn (triethyl indium), InCp (cyclopentadienyl indium (I)), InEtCp (ethylcyclopentadienyl indium(I)), In(acac) ３ (indium acetylacetonate), In(tmhd) ３ (indium 2,2,6,6-tetramethyl-3,5-heptanedionate), In[( ｉ PrN) ２ CNR ２ ] ３(R=Me) (indium-tris-guanidinates), Et ２ InN (TMS) ２ (diethyl[bis-(trimethylsilyl)amido]indium), INCA(diethyl[1,1,1-trimethyl-N- (trimethylsilyl)silanaminato]indium), DADI([3-(dimethylamino)propyl]dimethyl indium), In(dmamp) ３ ((1-dimethylamino-2-methyl-2-propoxy)indium), Me ２ Examples include In(EDPA)(dimethyl(N-ethoxy-2,2-dimethylpropanamido)indium) and tris(N,N'-disosopropylacetamidinato)indium(III).

[0076] These ALD precursors may be used individually or in combination of two or more types.

[0077] The precursors described above can be manufactured according to known manufacturing methods. For example, when an alcohol compound is used as an organic ligand, the precursor can be manufactured by reacting the inorganic salt or hydrate of the aforementioned metal with an alkali metal alkoxide of the alcohol compound. Examples of the inorganic salt or hydrate of the metal include metal halides and nitrates. Examples of alkali metal alkoxides include sodium alkoxide, lithium alkoxide, and potassium alkoxide.

[0078] As an oxidizing agent used in ALD, H ２ O, O ２ , O ３ , O ２ Plasma, H ２ O plasma, hydrogen peroxide (H ２ O ２ Examples include the following. These oxidizing agents may be used individually or in combination of two or more.

[0079] When using two or more oxidizing agents, they may be used simultaneously, or they may be used individually while changing between them. For example, as an oxidizing agent, O ２ Plasma and H ２ By using two types of O plasma, ２ High mobility obtained when using plasma, and H ２ By using O plasma, it is possible to take advantage of both the reduction in carbon concentration and the improved stability of mobility during heat treatment. By using two or more oxidizing agents, high mobility and low carbon concentration can be adjusted. Depending on the desired effect, O ２ Plasma and H ２ The proportion of O-plasma used, the order of use, the number of cycles, etc., should be selected as appropriate.

[0080] The pressure in the system (inside the film deposition chamber) in step (1) can be set appropriately according to the type of precursor, substrate temperature, etc. For example, 1 to 10,000 Pa is preferred, 10 to 1,000 Pa is more preferred, 50 to 500 Pa is even more preferred, and 80 to 120 Pa is particularly preferred.

[0081] In one embodiment, in the film formation process, H is used as the oxidizing agent. ２ O plasma is used. In one embodiment, in the film formation process, O is used as the oxidizing agent. ２ Plasma is used. In one embodiment, in the film deposition process, O is used as the oxidizing agent. ３ These oxidizing agents are used. By using these oxidizing agents, it is possible to control the electrical properties of the oxide semiconductor film to a favorable state.

[0082] To vaporize the precursor, the container containing the precursor may be heated to a temperature at which the precursor is sufficiently vaporized, as needed. If a precursor with a high vapor pressure is used, the container containing the precursor may be cooled as needed. In one embodiment, the container containing the indium-containing precursor (e.g., triethylindium) is heated to a temperature in the range of 25 to 150°C. The above temperature is preferably in the range of 50 to 150°C, and more preferably in the range of 75 to 125°C.

[0083] In the manufacturing method described above, the substrate temperature during film formation is usually in the range of 50 to 600°C, preferably 85 to 500°C, more preferably 80 to 350°C, and even more preferably 100 to 250°C.

[0084] Furthermore, the amount of oxide semiconductor film grown per ALD process cycle varies depending on the type of precursor and reactive gas used during film formation, as well as the substrate temperature during film formation.

[0085] The growth rate per ALD process cycle is called Growth per Cycle (GPC), and can be calculated, for example, by measuring the film thickness of the oxide semiconductor after repeating 30 ALD cycles. Here, GPC changes depending on the combination of precursor, oxidizer, and substrate temperature, and also changes depending on the type of substrate. Therefore, the number of cycles can be set appropriately by taking these factors into consideration, as it depends on numerous factors such as the type and combination of precursor and oxidizer used, the type of substrate, the substrate temperature during film formation, and the desired film thickness.

[0086] Also, as an oxidizing agent, O ３ When using, the substrate temperature during film formation is preferably above 100°C, more preferably 110-250°C, 120-230°C, or 130-220°C. H is used as the oxidizing agent. ２ O plasma and O ２ When using plasma, the substrate temperature during film deposition is preferably 100 to 150°C.

[0087] Examples of inert gases used to purge unreacted raw materials and unreacted oxidizing agents include argon and nitrogen, and in the method of this embodiment, argon or nitrogen is preferred.

[0088] Furthermore, as shown in the further modification of the first embodiment (Figure 4), when forming a first region 15a, a second region 15b, and a third region 15c in the oxide semiconductor 15, the composition of the material used in each region can be appropriately adjusted. The same applies to the modifications of the second embodiment and the third embodiment described later.

[0089] (Second Embodiment) Next, another example of the transistor according to this embodiment (second embodiment) will be described with reference to Figures 6 and 7. Figure 6 is a schematic perspective view showing a cross-section of the transistor according to the second embodiment. Figure 7 is a schematic cross-sectional view of the transistor. In Figures 6 and 7, the same reference numerals as in Figures 1 and 2 indicate the same components, and unless otherwise specified, the descriptions given for Figures 1 and 2 will be incorporated by reference.

[0090] In the second embodiment, the transistor 10 includes a first electrode 11, a second electrode 12, a third electrode 13, an oxide semiconductor 15, a first insulating film 14, and a second insulating film 16. At least a portion of the third electrode 13 is located between the first electrode 11 and the second electrode 12. At least a portion of the third electrode 13 may be located on the opposite side of the first electrode 11 from the second electrode 12, or on the opposite side of the second electrode 12 from the first electrode 11. The first insulating film 14 is located between the first electrode 11 and the second electrode 12. Here, the first electrode 11 and the second electrode 12 are stacked with the first insulating film 14 in between. As a result, the first electrode 11 and the second electrode 12 are electrically insulated by the first insulating film 14. The third electrode 13 is provided adjacent to the oxide semiconductor 15 without contacting it. Specifically, the third electrode 13 is adjacent to the oxide semiconductor 15 via the second insulating film 16. The second insulating film 16 may be provided between the third electrode 13 and the oxide semiconductor 15 to insulate the third electrode 13 from the oxide semiconductor 15.

[0091] The oxide semiconductor 15 penetrates at least the first insulating film 14 and is provided to connect the first electrode 11 and the second electrode 12. Here, the oxide semiconductor 15 is provided in a columnar shape, penetrating the first electrode 11 and the first insulating film 14 in that order. The columnar oxide semiconductor 15 has a recess formed from one end (upper side in Figures 6 and 7) to the other end (lower side in Figures 6 and 7), and the second insulating film 16 is formed on the inner circumferential surface and bottom surface of the recess. The third electrode 13 is provided to fill the recess where the second insulating film 16 is formed. From one viewpoint, it can also be said that the oxide semiconductor 15 has a cylindrical portion provided penetrating the first insulating film 14, the second insulating film 16 has a cylindrical portion provided on the inner wall of the cylindrical portion of the oxide semiconductor 15, and the third electrode 13 has a portion provided inside the cylindrical portion of the second insulating film 16.

[0092] In the second embodiment as well, at least one of the first electrode 11 and the second electrode 12 is made of a conductive material having properties that allow hydrogen to be extracted, and the oxide semiconductor 15 has a bigxbite structure. Therefore, variations in the operation of the transistor can be suppressed.

[0093] The dimensions of the transistor 10 may be designed as appropriate depending on its application. The channel length of the oxide semiconductor 15 is, for example, 1 nm to 10 μm, preferably 2 nm to 1000 nm. The channel length of the oxide semiconductor 15 is the length of the oxide semiconductor 15 along the thickness direction (vertical direction in Figures 6 and 7) of the laminate in which the first electrode 11, the first insulating film 14, and the second electrode 12 are stacked in this order, and may coincide with the depth of the recess in the oxide semiconductor 15.

[0094] The thickness of the oxide semiconductor 15 is, for example, 1 nm to 500 nm, preferably 1 nm to 100 nm. The thickness of the oxide semiconductor 15 may be the average thickness along the channel length. The average thickness along the channel length is the average value obtained when the thickness is measured at 10 or more locations along the channel length.

[0095] The thickness of the second insulating film 16 is, for example, 1 Å to 500 nm, preferably 1 nm to 100 nm. In order to suppress the capacitance of the second insulating film 16 from becoming a parasitic component, the thickness of the second insulating film 16 may be 50 nm or less, 10 nm or less, or 2 nm or less.

[0096] The channel length and thickness of the oxide semiconductor 15, and the thickness of the second insulating film 16, can be measured in the same manner as in the first embodiment.

[0097] The first electrode 11, the second electrode 12, the third electrode 13, the first insulating film 14, the second insulating film 16, and the oxide semiconductor 15 may be described by reference to the first embodiment.

[0098] The method for manufacturing the transistor 10 according to the second embodiment is not particularly limited and can be manufactured by known methods with reference to the manufacturing method according to the first embodiment. For example, the transistor 10 according to the second embodiment may be manufactured as follows: After forming a laminate of the second electrode 12, the first insulating film 14, and the first electrode 11, through holes are formed so as to penetrate the first electrode 11 and the first insulating film 14. After forming the oxide semiconductor 15, the second insulating film 16 and the third electrode 13 are formed.

[0099] Next, a modified example of the second embodiment will be described with reference to Figure 8. The transistor 10 shown in Figure 8 is the same as the embodiment described above, except that the configuration of the oxide semiconductor 15 is different, and the description of the embodiment described above will be applied. In this modified example, the oxide semiconductor 15 has a first region 15a, a second region 15b, and a third region 15c, in that order from the third electrode 13 side. Here, the concentration of indium atoms in the second region 15b is lower than that of the first region 15a. Also, the concentration of indium atoms in the third region 15c is lower than that of the second region 15b. Therefore, it can be said that the concentration of indium atoms is increasing in the order of the third region 15c, the second region 15b, and the first region 15a. By forming a difference in the concentration of indium atoms in each region of the oxide semiconductor 15 in this way, the effect of achieving both high mobility and low leakage can be obtained. In this modified example, the composition ratio of the first region 15a is In Ｘ１ Ga Ｙ１ O, and the composition ratio of the second region 15b is InＸ２ Ga Ｙ２ It is O, and the composition ratio of the third region 15c is In Ｘ３ Ga Ｙ３ It is preferable that the conditions 100 ≥ X1 ≥ X2 ≥ X3 ≥ 50 and 0 ≤ Y1 ≤ Y2 ≤ Y3 ≤ 50 are satisfied. This provides the effect of achieving both high mobility and low leakage. In this modified example, the third region 15c has a portion formed in a concave shape (having a recess) so as to be in contact with the inner circumferential surface and bottom surface of a recess that penetrates the first electrode 11 and the first insulating film 14 in that order. The second region 15b also has a portion formed in a concave shape (having a recess) so as to be in contact with the inner circumferential surface and bottom surface of the concave third region 15c. Furthermore, the third region 15c has a portion formed in a concave shape (having a recess) so as to be in contact with the inner circumferential surface and bottom surface of the concave second region 15b. The above describes a modified example in which the oxide semiconductor 15 has a first region 15a, a second region 15b, and a third region 15c. However, in other modified examples, the second region 15b may be omitted, and the first region 15a and the third region 15c may be arranged to be in contact with each other (in this case, "third region" may be read as "second region").

[0100] Next, another example of the transistor according to this embodiment (a third embodiment) will be described with reference to Figures 9 and 10. Figure 9 is a schematic perspective view showing a cross-section of the transistor according to the third embodiment. Figure 10 is a schematic cross-sectional view of the same transistor. In Figures 9 and 10, the same reference numerals as in Figures 1 and 2 indicate the same components, and unless otherwise specified, the descriptions given for Figures 1 and 2 will be incorporated by reference.

[0101] In the third embodiment, the transistor 10 comprises a first electrode 11, a second electrode 12, a third electrode 13, oxide semiconductors 15, 15', and a first insulating film 14. The third electrode 13 is located between the first electrode 11 and the second electrode 12. The first insulating film 14 is located between the first electrode 11 and the third electrode 13. Here, the first electrode 11 and the second electrode 12 are stacked with the first insulating film 14 in between. As a result, the first electrode 11 and the second electrode 12 are electrically insulated by the first insulating film 14. The third electrode 13 is provided adjacent to the oxide semiconductors 15, 15' without contact with them. Specifically, the third electrode 13 is adjacent to the oxide semiconductors 15, 15' via the first insulating film 14 located between the third electrode 13 and the oxide semiconductors 15, 15'. In this sense, it can be said that the first insulating film 14 in the third embodiment also serves the role of the second insulating film 16 in the first and second embodiments.

[0102] The oxide semiconductors 15 and 15' connect the first electrode 11 and the second electrode 12, respectively.

[0103] In the third embodiment, at least one of the first electrode 11 and the second electrode 12 is made of a conductive material having properties that allow hydrogen to be extracted, and the oxide semiconductors 15 and 15' have a bigxbite structure. Therefore, variations in the operation of the transistor can be suppressed.

[0104] The dimensions of the transistor 10 may be designed as appropriate depending on its application. The channel length of the oxide semiconductors 15 and 15' is, for example, 1 nm to 10 μm, preferably 2 nm to 1000 nm. The channel length of the oxide semiconductor 15 is the length of the oxide semiconductors 15 and 15' along the thickness direction (vertical direction in Figures 9 and 10) of the laminate in which the first electrode 11, the first insulating film 14, and the second electrode 12 are stacked in this order, and may coincide with the distance between the first electrode 11 and the second electrode 12.

[0105] The thickness of the oxide semiconductors 15 and 15' is, for example, 1 nm to 500 nm, preferably 1 nm to 100 nm. The thickness of the oxide semiconductor 15 may be the average thickness along the channel length. The average thickness along the channel length is the average value obtained when the thickness is measured at 10 or more locations along the channel length.

[0106] The thickness of the first insulating film 14 is, for example, 1 Å to 500 nm, preferably 1 nm to 100 nm. In order to suppress the capacitance of the first insulating film 14 from becoming a parasitic component, the thickness of the first insulating film 14 may be 50 nm or less, 10 nm or less, or 2 nm or less.

[0107] The channel length and thickness of the oxide semiconductors 15 and 15', and the thickness of the first insulating film 14, can be measured in the same manner as in the first embodiment.

[0108] With respect to the first electrode 11, the second electrode 12, the third electrode 13, the first insulating film 14, and the oxide semiconductor 15, the descriptions in the first and second embodiments may be applied. With respect to the first insulating film 14, the description of the second insulating film 16 in the first and second embodiments may be applied.

[0109] Next, a modified example of the third embodiment will be described with reference to Figure 11. The transistor 10 shown in Figure 11 is the same as the embodiment described above, except that the configuration of the oxide semiconductors 15 and 15' is different, and the explanation given for the embodiment described above will be applied. In this modified example, the oxide semiconductor 15 has a first region 15a, a second region 15b, and a third region 15c, in that order from the third electrode 13 side. Here, the concentration of indium atoms in the second region 15b is lower than that of the first region 15a. Also, the concentration of indium atoms in the third region 15c is lower than that of the second region 15b. Therefore, it can be said that the concentration of indium atoms is increasing in the order of the third region 15c, the second region 15b, and the first region 15a. By forming a difference in the concentration of indium atoms in each region of the oxide semiconductor 15 in this way, the effect of achieving both high mobility and low leakage can be obtained. In this modified example, the composition ratio of the first region 15a is In Ｘ１ Ga Ｙ１ O, and the composition ratio of the second region 15b is In Ｘ２Ga Ｙ２ It is O, and the composition ratio of the third region 15c is In Ｘ３ Ga Ｙ３ It is preferable that the following conditions are met: 0, 100 ≥ X1 ≥ X2 ≥ X3 ≥ 50, and 0 ≤ Y1 ≤ Y2 ≤ Y3 ≤ 50. This provides the effect of achieving both high mobility and low leakage. In this modified example, the first region 15a is formed in layers so as to be in contact with the side surface of the first insulating film 14. The second region 15b is formed in layers so as to be in contact with the surface of the layered first region 15a opposite to the first insulating film 14. Furthermore, the third region 15c is formed in layers so as to be in contact with the surface of the layered second region 15b opposite to the first insulating film 14. The above describes a modified example in which the oxide semiconductor 15 has a first region 15a, a second region 15b, and a third region 15c. However, in other modified examples, the second region 15b may be omitted, and the first region 15a and the third region 15c may be provided so as to be in contact with each other (in this case, "third region" may be read as "second region"). The first region 15a, second region 15b, and third region 15c of the oxide semiconductor 15 have been described above, but similar regions (first region 15a', second region 15b', and third region 15c') are also formed in the oxide semiconductor 15'. The explanation given for the first region 15a', second region 15b', and third region 15c' of the oxide semiconductor 15' can be applied to the first region 15a', second region 15b', and third region 15c' of the oxide semiconductor 15'.

[0110] The method for manufacturing the transistor 10 according to the third embodiment is not particularly limited and can be manufactured by referring to known methods (for example, the method described in International Publication No. 2020 / 076850, etc.) while referring to the manufacturing method according to the first embodiment. The methods for forming the first electrode 11, second electrode 12, third electrode 13, first insulating film 14, and oxide semiconductor 15 may be adapted from the descriptions in the first and second embodiments. The method for forming the first insulating film 14 may be adapted from the descriptions of the second insulating film 16 in the first and second embodiments.

[0111] 2. Semiconductor Devices A semiconductor device according to one aspect of the present invention includes a transistor according to one aspect of the present invention. The semiconductor device according to this aspect can reduce the hydrogen concentration in the oxide semiconductor in the transistor, thus suitably achieving normally-off and high reliability. The type of semiconductor device is not particularly limited, but from the viewpoint of demonstrating the above-mentioned effects significantly, it is preferable to use semiconductor memory devices such as volatile memories such as DRAM (Dynamic Random Access Memory) and SRAM (Static RAM); and non-volatile memories such as mask ROM (Read Only Memory), EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM), flash memory (NOR type flash memory, NAND type flash memory), MRAM (Magnetoresistive RAM), FeRAM (Ferroelectric RAM), ReRAM (Resistive RAM), etc. Alternatively, the semiconductor device according to this embodiment may be a logic device such as TTL (Transistor-Transistor Logic), CMOS (Complementary Metal-Oxide-Semiconductor), BiCMOS, PLD (Programmable Logic Device), FPGA (Field Programmable Gate Array), CPU (Central Processing Unit), or MPU (Microprocessor Unit). Furthermore, since the transistor according to one embodiment of the present invention can be fitted with a vertical structure as shown in each embodiment, it is suitable for densely arranging multiple transistors in a semiconductor memory device and contributes to the miniaturization of the semiconductor memory device. In addition, since the transistor according to one embodiment of the present invention uses an oxide semiconductor as the channel, it tends to have a small leakage current. Therefore, by using it in a semiconductor memory device, the capacitance of the capacitor can be reduced or the capacitor can be omitted. As a result, by using the transistor according to one embodiment of the present invention, the semiconductor memory device can be miniaturized.

[0112] Semiconductor devices can contain a large number of transistors. For example, DRAM contains hundreds of millions of memory cells, and the transistors that make up these memory cells are also in the hundreds of millions. In addition, DRAM uses multiple transistors other than memory cells. According to this embodiment, variations in the performance of each transistor can be suppressed, and variations in the operation of the semiconductor device can also be effectively suppressed.

[0113] Figure 12 shows an example of a circuit configuration of a semiconductor memory device equipped with a transistor according to one aspect of the present invention. As shown in Figure 12, the semiconductor memory device 50 includes a transistor 10, a capacitor 51, a word line WL, and a bit line BL. The source electrode of the transistor 10 is connected to the bit line BL. The drain electrode of the transistor 10 is connected to one end of the capacitor 51. The gate electrode of the transistor 10 is connected to the word line WL. The other end of the capacitor 51 is grounded. The bit line BL may be connected to the first electrode 11 of the transistor 10, or to the second electrode 12. The word line WL may be connected to the third electrode 13 of the transistor 10. One end of the capacitor 51 may be connected to the first electrode 11 of the transistor 10, or to the second electrode 12.

[0114] In the example shown in Figure 12, a single memory cell 52 is formed by a transistor 10 and a capacitor 51. The memory cell 52 can store data based on the charge held by the capacitor 51. Note that the configuration of the memory cell 52 is not limited to this example, and in other examples, the capacitor 51 may be omitted. When the capacitor 51 is omitted, data can be stored based on the charge held by the transistor 10 itself. Furthermore, two or more transistors may be combined to form the memory cell 52. If the transistor 10 itself is to have the function of holding charge, for example, one or more of the configurations described below can be applied. (1) The second insulating film is made of hafnium oxide (HfO ２ ), zirconium oxide (ZrO ２ (2) Use a high dielectric constant insulator such as (Pb, La)(Zr, Ti)O ３(PLZT), SrTiO ３ (STO), yttria-stabilized zirconia (YSZ), and other ferroelectric materials are used. (3) Hysteresis is utilized by adding an element that forms an energy level within the gap of the oxide semiconductor to the oxide semiconductor. (4) Parasitic capacitance is utilized by arranging a part of the source electrode and / or drain electrode and a part of the gate electrode so that they face each other across an insulating film. In (4) above, for example, parasitic capacitance can be utilized by arranging a part of one of the source electrode and drain electrode and a part of the gate electrode so that they face each other across an insulating film. In this case, the other of the source electrode and drain electrode may be arranged away from the gate electrode (for example, the distance between the other of the source electrode and drain electrode and the gate electrode may be longer than the distance between one of the source electrode and drain electrode and the gate electrode).

[0115] The semiconductor memory device 50 can read data stored in the memory cell 52 to the bit line BL by controlling the word line WL, and can also write data transferred to the bit line BL to the memory cell 52. The semiconductor memory device 50 is configured to include a memory cell array (not shown) consisting of a plurality of memory cells 52.

[0116] The following describes embodiments of the present invention, but the present invention is not limited to these embodiments. Molecular dynamics simulations based on first-principles calculations are used to obtain a-IGZO (amorphous-IGZO) and a-In ２ O ３ (Amorphous indium oxide), and c-In ２ O ３ Figure 13 shows the results of calculating the hydrogen diffusivity of (crystal-indium oxide: mainly composed of indium oxide and having a bixbite structure). In Figure 13, the horizontal axis represents time, and the vertical axis represents the mean square displacement (MSD, the part enclosed in < > in the following equation) in the Einstein relation relating to the diffusion coefficient, indicating the diffusivity of hydrogen atoms.

[0117]

[0118] In the above formula, D is a diffusion coefficient, T is time, d is the number of dimensions (=3), t is simulation time, and r(t) is a coordinate at t. The results in FIG. 13 show that a-In ２ O ３ has a lower hydrogen diffusion rate than a-IGZO, and c-In ２ O ３ has a lower hydrogen diffusion rate than a-In ２ O ３ . The reason for this is considered to be that "Amorphous" has less order than "Crystal", and regions lacking atomic order tend to serve as hydrogen diffusion paths. Furthermore, hydrogen diffusion in an oxide semiconductor is more suppressed in a-In ２ O ３ than in a-IGZO. The reason for this is considered to be that, compared to a-In ２ O ３ , a-IGZO has greater variation in the size of constituent metal elements, so hydrogen diffusion paths are more likely to form in the amorphous state. Another possible reason is that zinc oxide reacts more readily with hydrogen than indium oxide, so hydrogen is more easily incorporated therein. From the above results, it is considered that when an oxide semiconductor has a bixbyite structure, hydrogen diffusion into the oxide semiconductor serving as a channel layer is suppressed, and variation in transistor characteristics is prevented.

[0119] 10: Transistor 11: First electrode 111: Layer containing Ta and O 12: Second electrode 121: Layer containing Ta and O 13: Third electrode 16: Second insulating film 14, 14a: First insulating film 14b: Third insulating film 15, 15': Oxide semiconductor 151, 152: Region (in contact with electrode) 19: Insulating film 50: Semiconductor memory device 51: Capacitor 52: Memory cell WL: Word line BL: Bit line

Claims

1. A transistor comprising: a first electrode and a second electrode; an oxide semiconductor connecting the first electrode and the second electrode; and a third electrode adjacent to the oxide semiconductor without contact with it, wherein at least one of the first electrode and the second electrode is made of a conductive material having the property of extracting hydrogen, and the oxide semiconductor has a bigx-byte structure.

2. The transistor according to claim 1, wherein the first electrode and the second electrode are stacked with at least a first insulating film in between.

3. The transistor according to claim 2, wherein the oxide semiconductor penetrates at least the first insulating film to connect the first electrode and the second electrode.

4. The transistor according to claim 2 or 3, further comprising a second insulating film provided between the third electrode and the oxide semiconductor.

5. The transistor according to any one of claims 2 to 4, wherein the first electrode and the third electrode are stacked with respect to the first insulating film, the third electrode and the second electrode are stacked with respect to the third insulating film, the oxide semiconductor is provided in a columnar shape penetrating the first insulating film, the third electrode, and the third insulating film, and further comprises a second insulating film provided between the third electrode and the oxide semiconductor, the second insulating film being provided so as to surround at least a portion of the columnar oxide semiconductor.

6. The transistor according to any one of claims 2 to 4, wherein the first electrode and the second electrode are stacked with respect to the first insulating film, the oxide semiconductor has a cylindrical portion provided through the first insulating film, and further comprises a second insulating film provided between the third electrode and the oxide semiconductor, the second insulating film has a cylindrical portion provided on the inner wall of the cylindrical portion of the oxide semiconductor, and the third electrode has a portion provided inside the cylindrical portion of the second insulating film.

7. The transistor according to any one of claims 1 to 6, wherein the channel length of the oxide semiconductor is 1 to 1000 nm.

8. The transistor according to any one of claims 1 to 7, wherein the oxide semiconductor is mainly composed of indium oxide.

9. The transistor according to any one of claims 1 to 8, wherein the ratio of indium atoms to all metal atoms contained in the oxide semiconductor is 80 atomic percent or more.

10. The transistor according to any one of claims 1 to 9, wherein the indium oxide content in the oxide semiconductor is 55% by mass or more.

11. The transistor according to any one of claims 8 to 10, wherein the oxide semiconductor further comprises Ga or Al.

12. The transistor according to any one of claims 8 to 10, wherein the oxide semiconductor further comprises Ga.

13. The transistor according to any one of claims 8 to 10, wherein the oxide semiconductor further comprises Ga and Al.

14. The transistor according to any one of claims 1 to 13, wherein the atomic ratio of Ga to all metal elements contained in the oxide semiconductor ([Ga] / ([Ga] + [all metal elements other than Ga]) × 100) is 0.5 to 25 at%.

15. The transistor according to any one of claims 1 to 14, wherein the atomic ratio of Zn to all metal elements contained in the oxide semiconductor ([Zn] / ([Zn] + [all metal elements other than Zn]) × 100) is 0 to 3 at%.

16. The transistor according to any one of claims 1 to 15, wherein the oxide semiconductor substantially does not contain Zn.

17. The transistor according to any one of claims 1 to 16, wherein the oxide semiconductor has, in order from the third electrode side, a first region, a second region having a lower concentration of indium atoms than the first region, and a third region having a lower concentration of indium atoms than the second region.

18. The composition ratio of the first region is In Ｘ１ Ga Ｙ１ The composition ratio of the second region is O, and the composition ratio of the second region is In Ｘ２ Ga Ｙ２ The composition ratio of the third region is O, and the composition ratio of the third region is In Ｘ３ Ga Ｙ３ The transistor according to claim 17, wherein the value is O and satisfies the conditions 100 ≥ X1 ≥ X2 ≥ X3 ≥ 50 and 0 ≤ Y1 ≤ Y2 ≤ Y3 ≤ 50.

19. The transistor according to any one of claims 1 to 18, wherein the conductive material includes Ta.

20. The transistor according to claim 19, wherein the conductive material further comprises N.

21. The composition formula of the conductive material is TaN ｘ O ｙ The transistor according to claim 19 or 20, wherein 0 < x ≤ 1.67 and 0 ≤ y ≤ 1.

0.

22. The transistor according to any one of claims 1 to 21, wherein at least one of the first electrode and the second electrode has a layer containing Ta and O in at least a portion of the region that contacts the oxide semiconductor.

23. The transistor according to any one of claims 1 to 22, wherein the oxide semiconductor is a crystalline oxide semiconductor formed by atomic layer deposition.

24. A semiconductor device comprising a transistor according to any one of claims 1 to 23.

25. The semiconductor device according to claim 24, which is a semiconductor memory device.

26. A transistor comprising: a first electrode and a second electrode; an oxide semiconductor connecting the first electrode and the second electrode; and a third electrode adjacent to the oxide semiconductor without contact with the oxide semiconductor, wherein the first electrode and the second electrode are stacked with at least a first insulating film in between; at least one of the first electrode and the second electrode is made of a conductive material having the property of extracting hydrogen; the oxide semiconductor is mainly composed of indium oxide and has a bixbite structure; and the atomic ratio of Zn to all metal elements contained in the oxide semiconductor ([Zn] / ([Zn] + [all metal elements other than Zn]) × 100) is 0 to 3 at%.

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