Oxide semiconductor film, transistor, and production method for oxide semiconductor film

Abstract

An oxide semiconductor film according to the present invention has a region at which the carbon concentration is at least 1×1018 atoms / cm3 but no more than 5×1022 atoms / cm3 and a region at which the hydrogen concentration is at least 1×1018 atoms / cm3 but no more than 5×1022 atoms / cm3 as measured by secondary ion mass spectrometry (SIMS).

Description

Oxide semiconductor film, transistor, and method for manufacturing the oxide semiconductor film

[0001] The present invention relates to an oxide semiconductor film, a transistor, and a method for manufacturing an oxide semiconductor film.

[0002] In recent years, oxide semiconductor films have come to be used not only in display transistors but also in memory FETs (DRAM, NAND, ReRAM, FeRAM), logic IC FETs (CPU, MPU, BEOL, 3D-LSI, CMOS), sensor FETs (CMOS image sensors) and transistors (MOSFETs, power transistors, MESFETs), and research into improving the performance of oxide semiconductor films is progressing. For example, Patent Document 1 discloses a method for manufacturing a transistor that improves long-term reliability by reducing oxygen vacancies in an oxide semiconductor.

[0003] Patent Document 2 discloses a method for manufacturing a semiconductor device using an oxide containing indium (In), zinc (Zn) and aluminum (Al), which is InAlO ３ (ZnO) ｍ (m is 0.1 to 10) and In ２ O ３ Patent Document 2 discloses an oxide semiconductor thin film manufactured using a sputtering target including a sintered body containing a bixbyite structure compound. Patent Document 2 discloses that in an oxide semiconductor film used in a transistor or the like, it is preferable to reduce the carrier concentration in order to prevent leakage current, normally-on, and a decrease in the on-off ratio when an element is constructed, while a high mobility is required when the carrier concentration in the film is increased. This is because, in a field-effect transistor, an increase in carrier concentration due to the field effect is an indicator of high mobility. Furthermore, the carrier concentration and mobility in a film can generally be determined by Hall effect measurement. In the present invention, the carrier concentration and mobility determined by Hall effect measurement are referred to as the carrier concentration and Hall mobility, respectively.

[0004] Currently, sputtering is widely used as a method for forming oxide semiconductor films for display applications (see, for example, Patent Document 3). Meanwhile, memory applications are attracting attention as the next application of oxide semiconductor films. For memory applications, it is necessary to form an oxide semiconductor film on a three-dimensional structure, and atomic layer deposition (hereinafter sometimes referred to as ALD) is attracting attention as an alternative to sputtering (see, for example, Patent Document 4).

[0005] Japanese Patent Application Laid-Open No. 2014-57054 Japanese Patent Application Laid-Open No. 2014-051714 Special Publication No. 2016-511936 International Publication No. 2021 / 106652

[0006] For applications such as higher performance displays, memories, and sensors, oxide semiconductor films are desired that have a lower carrier concentration and exhibit higher hole mobility when the carrier concentration is increased by the field effect.

[0007] It is known that carbon in an oxide semiconductor film affects the electrical characteristics of the oxide semiconductor film. Specifically, it is known that when silicon or carbon, which is one of the Group 14 elements, is contained in an oxide semiconductor film as an impurity, the silicon or carbon acts as a donor and makes the oxide semiconductor film n-type. Therefore, in Patent Document 1, the concentration of silicon or carbon in the oxide semiconductor film is set to 3×10 １８ / cm ３ Patent Document 1 also describes that if hydrogen or moisture is contained in an oxide semiconductor film as an impurity, the hydrogen acts as a donor and causes the oxide semiconductor film to become n-type, and therefore it is preferable to form the film while controlling the atmosphere to contain almost no hydrogen or moisture (such as an inert atmosphere, a reduced-pressure atmosphere, or a dry-air atmosphere). As described above, in conventional oxide semiconductor film formation by sputtering as disclosed in Patent Document 1 and the like, oxide semiconductor films with excellent electrical properties have been manufactured by controlling the amount of carbon and hydrogen contained in the film to be as small as possible.

[0008] Furthermore, although an oxide semiconductor film can be formed by ALD as described above, carbon and hydrogen remain in the formed oxide semiconductor film due to the film formation principle of ALD. Therefore, it has been desired to suppress the deterioration of the electrical properties of the resulting oxide semiconductor film.

[0009] The present inventors have conducted extensive research and found that an oxide semiconductor film containing carbon and hydrogen can have a low carrier concentration and, when the carrier concentration is increased, can have a high hole mobility and good electrical properties, and have completed the present invention. An object of the present invention is to provide an oxide semiconductor film that can have a low carrier concentration and, when the carrier concentration is increased, can have a high hole mobility.

[0010] According to the present invention, the following oxide semiconductor film and the like are provided: 1. A carbon concentration of 1×10 or more as measured by secondary ion mass spectrometry (SIMS) １８ atoms / cm ３ That's it, 5 x 10 ２２ atoms / cm ３ and hydrogen concentration is 1×10 １８ atoms / cm ３ That's it, 5 x 10 ２２ atoms / cm ３An oxide semiconductor film having the following regions: 2. The oxide semiconductor film according to 1, containing indium oxide as a main component. 3. The oxide semiconductor film according to 2, wherein the atomic ratio of In to all metal elements contained in the oxide semiconductor film ([In] / ([In]+[all metal elements other than In])×100) is 62 at% or more. 4. The oxide semiconductor film according to 2 or 3, further containing Ga. 5. The oxide semiconductor film according to 4, wherein the atomic ratio of Ga to all metal elements contained in the oxide semiconductor film ([Ga] / ([Ga]+[all metal elements other than Ga])×100) is 30 at% or less. 6. The oxide semiconductor film according to any one of 2 to 5, further containing one or more additive elements selected from B, Al, Si, Sc, Zn, Ce, Y, Zr, Sn, Sm, Hf, Ta, and Yb. 7. 8. The oxide semiconductor film according to any one of 2 to 7, wherein at least one of an X-ray diffraction pattern in X-ray diffraction and an electron diffraction spot in electron diffraction indicates a bixbyite structure. 9. The oxide semiconductor film according to any one of 2 to 8, wherein a crystal plane with respect to a surface of an underlayer in contact with the oxide semiconductor film is oriented in {111}. 10. The oxide semiconductor film according to any one of 2 to 7, wherein the oxide semiconductor film has an amorphous structure such that no X-ray diffraction pattern in X-ray diffraction and no electron diffraction spot in electron diffraction are observed. 11. The oxide semiconductor film according to any one of 1 to 10, wherein the film thickness is less than 20 nm. 12. The oxide semiconductor film according to any one of 2 to 7, wherein at least one of an X-ray diffraction pattern in X-ray diffraction and an electron diffraction spot in electron diffraction indicates a bixbyite structure. ３ 13. The oxide semiconductor film according to any one of 1 to 12, which has a surface roughness Ra of 0.6 nm or less. 14. The oxide semiconductor film according to any one of 1 to 12, which has a carrier concentration of 5×10 at room temperature. １９ cm －３ 15. The oxide semiconductor film according to any one of 1 to 13, wherein the hole mobility is 40 cm or less. ２16. The oxide semiconductor film according to any one of 1 to 15, wherein the oxide semiconductor film has a carbon concentration of 1×10 or more as measured by secondary ion mass spectrometry (SIMS). １８ atoms / cm ３ That's it, 5 x 10 ２２ atoms / cm ３ and hydrogen concentration is 1×10 １８ atoms / cm ３ That's it, 5 x 10 ２２ atoms / cm ３18. An oxide semiconductor film having the following region: an atomic ratio of In to all metal elements contained in the oxide semiconductor film ([In] / ([In]+[total metal elements other than In])×100) is 80 at % or more, and at least one of an X-ray diffraction pattern in X-ray diffraction and an electron beam diffraction spot in electron beam diffraction exhibits a bixbyite structure. 18. The oxide semiconductor film according to 17, further containing Ga. 19. A transistor comprising, on a substrate, a layer made of the oxide semiconductor film according to any one of 1 to 18, an insulating film layer, and an electrode. 20. The transistor according to 19, which is a bottom-gate / top-contact type. 21. The transistor according to 19, which is a top-gate / top-contact type. 22. The transistor according to any one of 19 to 21, wherein the insulating film layer is mainly composed of hafnium oxide. 23. The transistor according to any one of 19 to 21, wherein the insulating film layer is mainly composed of silicon oxide. 24. The transistor according to any one of 19 to 21, wherein the insulating film layer is mainly composed of aluminum oxide. 25. The transistor according to any one of 19 to 24, wherein the electrode is primarily composed of titanium nitride. 26. The transistor according to any one of 19 to 24, wherein the electrode is primarily composed of tungsten. 27. A semiconductor device comprising the transistor according to any one of 19 to 26. 28. An electronic circuit comprising the semiconductor device according to 27. 29. An electric device, an electronic device, a vehicle, or a power plant comprising the electronic circuit according to 28. 30. A method for producing the oxide semiconductor film according to any one of 1 to 18, comprising a step of depositing the oxide semiconductor film by atomic layer deposition (ALD) using an indium-containing precursor. 31. The method according to 30, wherein triethylindium is used as the indium-containing precursor. 32. The method according to 30 or 31, wherein a gallium-containing precursor is used in addition to the indium-containing precursor. 33. In the film-depositing step, H is used as an oxidizing agent. ２ 34. The method according to any one of 30 to 32, wherein O plasma is used as an oxidizing agent in the film forming step. ２ 35. The method according to any one of 30 to 32, wherein plasma is used. ３36. The method according to any one of 30 to 32, wherein the oxide semiconductor film is an indium oxide film. 37. The method according to any one of 30 to 36, wherein a container containing the indium-containing precursor is heated to a temperature in the range of 75 to 125°C.

[0011] According to the present invention, it is possible to provide an oxide semiconductor film in which the carrier concentration is reduced and the hole mobility is high when the carrier concentration is increased.

[0012] In the ALD method, H ２ O plasma or O ２ 1 is a graph showing the growth amount of an oxide semiconductor film when plasma is used and the substrate temperature is changed. It is a schematic diagram showing the structure of a bottom-gate bottom-contact (BGBC) transistor. It is a schematic diagram showing the structure of a bottom-gate top-contact (BGTC) transistor. It is a schematic diagram showing the structure of a top-gate bottom-contact (TGBC) transistor. It is a schematic diagram showing the structure of a top-gate top-contact (TGTC) transistor. It is a schematic diagram showing the cross section of a three-dimensional vertical channel transistor memory. It is a schematic diagram showing the film formation result of an oxide semiconductor film when a three-dimensional vertical channel layer is formed by a sputtering method. It is a schematic diagram showing the film formation result of an oxide semiconductor film when a three-dimensional channel layer is formed by an ALD method. It is a graph showing the depth profiles of carbon (C) concentration, hydrogen (H) concentration, and indium concentration (detected as InO) of Example 6 by SIMS depth profile analysis. It is a diagram showing diffraction spots A to I obtained in a bixbyite structure of indium oxide. In the ALD method, O ２ Plasma and H ２ Carrier concentration [N ｅ ( / cm ３ )] and Hall mobility [μ (cm ２ 1 is a graph showing the relationship between the O ２ Plasma and H ２ 1 is a graph showing the relationship between carrier concentration and hole mobility when H and O plasma are used at a ratio of 3:1 or 5:1. ２6 cycles with O plasma, then O ２ When 170 cycles were performed with plasma, and H ２ 30 cycles with O plasma, followed by O ２ 10 is a graph showing the relationship between carrier concentration and Hall mobility when 130 cycles are performed with plasma.

[0013] 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 of the numerical ranges can be combined in any combination. In addition, a combination of two or more of the individual embodiments of the present invention described below is also an embodiment of the present invention.

[0014] In this specification and the like, the terms "film" or "thin film" and "layer" can be used interchangeably in some cases.

[0015] In this specification, "electrically connected" includes a connection 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 allows electrical signals to be transmitted and received between the connected objects. For example, "something that has some kind of electrical function" includes electrodes, wiring, switching elements (transistors, etc.), resistive elements, inductors, capacitors, and other elements with various functions.

[0016] In this specification, the functions of the source and drain of a transistor may be interchanged when transistors of different polarities are used or when the direction of current flow changes during circuit operation, etc. Therefore, in this specification, the terms source and drain may be used interchangeably.

[0017] 1. Oxide Semiconductor Film The oxide semiconductor film of one embodiment of the present invention has a carbon concentration of 1×10 or less, as measured by secondary ion mass spectrometry (hereinafter referred to as SIMS). １８ atoms / cm ３ That's it, 5 x 10 ２２ atoms / cm ３ and hydrogen concentration is 1×10１８ atoms / cm ３ That's it, 5 x 10 ２２ atoms / cm ３ The oxide semiconductor film is characterized by having the following regions: When the oxide semiconductor film has the regions with the above carbon and hydrogen concentrations, the carrier concentration can be reduced, and when the carrier concentration is increased, high hole mobility can be achieved. The carbon and hydrogen concentrations are measured by SIMS under the conditions described in Examples.

[0018] Here, the oxide semiconductor film of this embodiment "has a region" having the above-mentioned predetermined carbon concentration and hydrogen concentration means that the carbon and hydrogen concentrations in the depth direction (film thickness direction) at a certain location (point) in the oxide semiconductor film, as measured by SIMS, which will be described later, may satisfy the above-mentioned ranges. Therefore, it is not necessary for the carbon and hydrogen concentrations to be satisfied throughout the entire oxide semiconductor film.

[0019] The carbon concentration is 1×10 １８ atoms / cm ３ The lower limit is 5 × 10 １８ atoms / cm ３ , 8 x 10 １８ atoms / cm ３ , 1×10 １９ atoms / cm ３ , 3 x 10 １９ atoms / cm ３ , 5 x 10 １９ atoms / cm ３ , 1×10 ２０ atoms / cm ３ , 5 x 10 ２０ atoms / cm ３ , or 1 × 10 ２１ atoms / cm ３ The carbon concentration may be 5×10 ２２ atoms / cm ３ The upper limit is 1 × 10 ２２ atoms / cm ３ , 5 x 10 ２１ atoms / cm ３ , 3 x 10 ２１ atoms / cm ３ , 1×10 ２１atoms / cm ３ , 5 x 10 ２０ atoms / cm ３ , 3 x 10 ２０ atoms / cm ３ , 1×10 ２０ atoms / cm ３ , 5 x 10 １９ atoms / cm ３ , or 1 × 10 １９ atoms / cm ３ may be.

[0020] The hydrogen concentration is 1×10 １８ atoms / cm ３ The lower limit is 5 × 10 １８ atoms / cm ３ , 1×10 １９ atoms / cm ３ , 5 x 10 １９ atoms / cm ３ , 1×10 ２０ atoms / cm ３ , or 5 x 10 ２０ atoms / cm ３ The hydrogen concentration may be 5×10 ２２ atoms / cm ３ The upper limit is 1 × 10 ２２ atoms / cm ３ , 5 x 10 ２１ atoms / cm ３ , 2 × 10 ２１ atoms / cm ３ , 1×10 ２１ atoms / cm ３ , 5 x 10 ２０ atoms / cm ３ , or 1 × 10 ２０ atoms / cm ３ may be.

[0021] The carbon concentration in the oxide semiconductor film of this embodiment is 1×10 １８ atoms / cm ３ That's it, 5 x 10 ２２ atoms / cm ３To achieve the above, in the case of ALD, the substrate temperature and the type and amount of oxidizing agent during film formation can be controlled, and in the case of sputtering, the carbon content of the sputtering target used can be controlled.

[0022] The hydrogen concentration in the oxide semiconductor film of this embodiment is 1×10 １８ atoms / cm ３ That's it, 5 x 10 ２２ atoms / cm ３ To achieve the above, in the case of ALD, the substrate temperature and the type and amount of oxidizing agent during film formation can be controlled, and in the case of sputtering, the amount of water introduced during sputtering can be controlled.

[0023] The oxide semiconductor constituting the oxide semiconductor film of this embodiment is not particularly limited, and may be any oxide capable of functioning as a semiconductor. Specific examples include metal oxides, and examples of metals used include In, Ga, Zn, Al, and Sn. Specific examples of metal oxides include indium oxide (IO), indium gallium oxide (IGO), indium gallium zinc oxide (IGZO), indium gallium aluminum oxide (IGAO), indium gallium tin zinc oxide (IGTZO), and indium tin zinc oxide (ITZO).

[0024] In one embodiment, the oxide semiconductor film of this embodiment contains indium oxide as a main component.

[0025] The phrase "mainly composed of indium oxide" means that the oxide semiconductor constituting the oxide semiconductor film of this embodiment is composed of more than 50 mass% indium oxide. The indium oxide content may be 55 mass% or more, 60 mass% or more, 70 mass% or more, 80 mass% or more, 90 mass% or more, 95 mass% or more, 97 mass% or more, 98 mass% or more, 99 mass% or more, or even 100 mass%.

[0026] In one embodiment, the oxide semiconductor film of this embodiment further contains Ga. In one embodiment, the atomic ratio of Ga to all metal elements contained in the oxide semiconductor film of this embodiment ([Ga] / ([Ga]+[all metal elements other than Ga])×100) is 30 at % or less, and may be 25 at % or less, 22 at % or less, or 20 at % or less.

[0027] In one embodiment, the oxide semiconductor film of this aspect further contains one or more additive elements selected from B, Al, 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 all metal elements contained in the oxide semiconductor film of this aspect ([total amount of additive elements] / ([total amount of additive elements]+[total metal elements other than additive elements])×100) is 10 at % or less, and may be 8 at % or less, 5 at % or less, or 3 at % or less.

[0028] In one embodiment, the oxide semiconductor film of this aspect contains indium oxide as a main component, and at least one of an X-ray diffraction pattern obtained by X-ray diffraction and an electron diffraction spot obtained by electron diffraction shows a bixbyite structure. The X-ray diffraction pattern obtained by X-ray diffraction or the electron diffraction spot obtained by electron diffraction is obtained by a method and under conditions described in Examples, and the presence or absence of the bixbyite structure is determined. The phrase "at least one of an X-ray diffraction pattern obtained by X-ray diffraction (XRD) and an electron diffraction spot obtained by electron diffraction (ED) shows a bixbyite structure" for the oxide semiconductor film of this aspect means, for example, that even if the X-ray diffraction pattern does not show a bixbyite structure, the oxide semiconductor film is determined to have a bixbyite structure if the electron diffraction spot shows a bixbyite structure.

[0029] Here, XRD methods are broadly classified into in-plane measurement and out-of-plane measurement, but out-of-plane measurement is used in this specification. In this specification, regarding the crystal planes of the bixbyite structure, the (001) plane includes the (001) plane as well as the equivalent (100) and (010) planes, and these are collectively expressed as {100}. Similarly, the (101) plane includes the (101) plane as well as the equivalent (110) and (011) planes, and these are collectively expressed as {110}. Furthermore, the (111) plane may be expressed as {111}. Furthermore, in each plane, "1" may be "-1", and these planes are considered to be equivalent to each plane.

[0030] In addition to {100}, crystal faces include {h00} (h is a natural number other than 1), {hk0} faces (h ≠ k, h and k are natural numbers), {hhl} faces (h ≠ l, h and l are natural numbers), and {hkl} faces (h ≠ k ≠ l, h, k, and l are natural numbers). In this specification, when h, k, and l in {} have a common divisor, the face obtained by dividing by the greatest common divisor can be treated as an equivalent face.

[0031] When an oxide semiconductor film has crystallinity, a peak appears at a predetermined diffraction angle (2θ) in the diffraction pattern measured out of plane. For example, a conventional crystalline oxide semiconductor film containing 50% or more indium element and having a bixbite structure has peaks at diffraction angles near 31° and near 44° in the diffraction pattern. The peak at a diffraction angle near 31° is attributed to the (222) plane (equivalent to {111}) of the bixbite structure. The peak at a diffraction angle near 44° is attributed to the (422) plane (equivalent to {211}) of the bixbite structure. Furthermore, the peak intensity at a diffraction angle near 31° is significantly greater than the peak intensity at a diffraction angle near 44°. This means that many crystals having {111} planes parallel to the surface of the oxide semiconductor film are present.

[0032] Note that the diffraction angle of the diffraction pattern of an oxide semiconductor film may vary depending on the composition of metal elements contained in the oxide semiconductor film or the manufacturing conditions of the oxide semiconductor film, and therefore, in this specification, the vicinity of the diffraction angle peak is considered to include a range of ±2°.

[0033] The assignment of the diffraction patterns for each plane will be discussed more specifically using a database of indium oxide powder XRD. In this specification, the powder XRD results for indium oxide listed in the powder diffraction database (JCPDS Card No. 06-0416) will be used. Diffraction from the (222) plane appears at 2θ = 30.580°, with a relative intensity of 100. Diffraction from the (400) plane appears at 2θ = 35.466°, with a relative intensity of 30. Diffraction from the (440) plane appears at 2θ = 51.037°, with a relative intensity of 35. Diffraction from the (662) plane appears at 2θ = 60.676°, with a relative intensity of 25.

[0034] Here, in XRD measurement, the oxide semiconductor film being a polycrystalline film with a bixbyite structure means that at least two diffraction peaks from the above-mentioned major specific planes (222), (400), (440), and (662) are observed. Also, in electron beam diffraction measurement, the oxide semiconductor film being a polycrystalline film with a bixbyite structure means that two or more diffraction peaks corresponding to (111), (100), and (110) or {111}, {100}, and {110} are observed from the same plane of the thin film in the diffraction pattern shown in Figure 4 of WO202363352.

[0035] Here, when discussing the orientation of a specific plane of an oxide semiconductor film, the peak intensity I of the diffraction pattern of the specific plane actually measured in the XRD measurement of the oxide semiconductor film is （ｈｋｌ） Relative intensity R （ｈｋｌ） For example, if the (222) plane is preferentially oriented relative to the (400) plane, then I （２２２） / 100 is I （４００） The value is greater than / 35.

[0036] Furthermore, the orientation ratio OR of two specific planes is I （ｈｋｌ） / R （ｈｋｌ） I （ｈｋｌ）‘ / R （ｈｋｌ）’ For example, the orientation ratio of the (222) plane to the (400) plane OR （２２２）／（４００） (I （２２２） / 100) / (I （４００） / 35). Furthermore, in this specification, the orientation ratio OR of the two specific planes may be considered to coincide with the area ratio of the specific planes directly observed by electron diffraction or electron backscatter diffraction (EBSD). Accuracy may be improved by calculating a correction factor by comparing the orientation ratio from XRD measurement with the orientation ratio from electron diffraction measurement or EBSD.

[0037] Regarding the oxide semiconductor film having a bixbyite structure, OR （２２２）／（４００） is OR （１１１）／（１００） It can also be expressed as OR ｛１１１｝／｛１００｝ In this specification, the OR value is based on the XRD measurement result.

[0038] (Crystalline Oxide Semiconductor Film) The crystalline oxide semiconductor film (hereinafter simply referred to as crystalline oxide semiconductor film) in this embodiment contains In element as a main component. The term "In element is the main component" means that the atomic ratio of In to all metal elements in the crystalline oxide semiconductor film ([In] / ([In]+[Total Metal Elements Other Than In])×100) (atomic %: at %) is 50 at % or more. The atomic ratio of In is preferably 62 at % or more, more preferably 70 at % or more, more preferably 80 at % or more, and even more preferably 85 at % or more. When 50 at % or more of the total number of atoms of metal elements constituting the crystalline oxide semiconductor film are In element, a transistor can exhibit sufficiently high mobility when the stacked layer structure according to this embodiment is used in the transistor.

[0039] The phrase "an X-ray diffraction pattern obtained by X-ray diffraction or an electron diffraction spot obtained by electron diffraction exhibits a bixbyite structure" means that at least one of an X-ray diffraction pattern and an electron diffraction spot exhibits a bixbyite structure. When the oxide semiconductor film of this embodiment exhibits a bixbyite structure, the carrier concentration is reduced and hole mobility is also high.

[0040] The oxide semiconductor film of this embodiment containing indium oxide as a main component and having a bixbyite structure may contain any other element within a range in which the bixbyite structure can be maintained.

[0041] In addition to In, the oxide semiconductor film of this embodiment may contain one or more elements selected from the group consisting of H, B, C, N, O, F, Mg, Al, Si, O, S, Cl, Ar, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Sn, Sb, Cs, Ba, Ln, Hf, Ta, W, Re, Os, Ir, Pt, Au, Pb, and Bi.

[0042] In this embodiment, the oxide semiconductor film may consist essentially of elements selected from In, Mg, Al, Si, Zn, Ga, Mo, Sn, Ln elements (lanthanoid elements), and O. Here, "substantially" means that the oxide semiconductor film of this embodiment may contain other components as long as the effects of the present invention resulting from the combination of In, Mg, Al, Si, Zn, Ga, Mo, Sn, Ln, and O are achieved.

[0043] In this embodiment, a more preferred first form of the oxide semiconductor film is one in which the metal elements are composed of In and Ga, and the atomic ratio satisfies the following formula (11): [Ga] / ([In]+[Ga])<22 at% (11). Note that the metal elements may contain inevitable impurities, and may further contain F or H in addition to O. By setting the composition in the above range, the In ratio becomes large, and Ga is substituted for the In site at an annealing temperature of about 300° C., allowing crystallization into a bixbyite structure. Furthermore, by adding Ga, which has a strong bond with oxygen, oxygen vacancies after annealing can be suppressed, and a stable film as a semiconductor can be formed.

[0044] A more preferred second embodiment of the oxide semiconductor film of this aspect comprises a metal element, In, and one or more elements X selected from B, Al, Sc, Mg, Zn, Ti, Y, Zr, Mo, Sn, Hf, W, Nb, Ta, Ge, Si, La, Ce, Pr, Nd, Sm, Dy, Ho, Er, Tm, Yb, and Lu, where X represents a metal element other than In, and satisfies the following atomic ratio: [X] / ([In]+[X])<15 at% (12). The metal element may contain unavoidable impurities, and may further contain F or H in addition to O. The above composition range increases the In ratio, allowing crystallization into a bixbyite structure in which X substitutes for the In site at an annealing temperature of about 300°C. Furthermore, adding an element X that has a strong bond with oxygen suppresses oxygen vacancies after annealing, resulting in the formation of a stable semiconductor film.

[0045] A more preferable third embodiment of the oxide semiconductor film of this aspect includes metal elements In, Ga, and one or more elements X selected from B, Al, Sc, Mg, Zn, Ti, Y, Zr, Mo, Sn, Hf, W, Nb, Ta, Ge, Si, La, Ce, Pr, Nd, Sm, Dy, Ho, Er, Tm, Yb, and Lu, and when a metal element other than In and Ga is an additional element X, the atomic ratios satisfy the following formulas (13) and (14): [Ga] / ([In]+[Ga]+[X])<22.5 at% (13) [X] / ([In]+[Ga]+[X])<8.0 at% (14) The metal elements may include inevitable impurities, and may further include F or H in addition to O. By setting the composition in the above range, the In ratio becomes large, and crystallization into a bixbyite structure in which Ga substitutes for the In site can be achieved at an annealing temperature of about 300° C. Furthermore, by adding an additional element X that has a strong bond with oxygen, oxygen deficiency after annealing can be further suppressed, and a stable film as a semiconductor can be formed.

[0046] A more preferable fourth embodiment of the oxide semiconductor film of this aspect includes metal elements In, Sn, and one or more elements X selected from B, Al, Sc, Mg, Zn, Ti, Y, Zr, Mo, Hf, W, Nb, Ta, Ge, Si, La, Ce, Pr, Nd, Sm, Dy, Ho, Er, Tm, Yb, and Lu, and when a metal element other than In and Sn is element X, the atomic ratios satisfy the following formulas (15) and (16): [Sn] / ([In]+[Sn]+[X])<20 at % (15) [X] / ([In]+[Sn]+[X])<8.0 at % (16) The metal elements may include inevitable impurities, and may further include F or H in addition to O. By setting the composition in this range, the In ratio becomes large, and even when annealed at a low temperature such as 300°C, crystallization can be achieved into a bixbyite structure in which Sn substitutes for the In site. Sn has a large ionic radius and a large overlap of its orbital with In, so high mobility can be maintained. Furthermore, by adding an additional element X that has a strong bond with oxygen, oxygen deficiency after annealing can be further suppressed, and a stable film can be formed as a semiconductor.

[0047] A more preferable fifth aspect of the oxide semiconductor film of this embodiment includes metal elements In, Zn, and one or more elements X selected from B, Al, Sc, Mg, Ti, Y, Zr, Mo, Hf, W, Nb, Ta, Ge, Si, La, Ce, Pr, Nd, Sm, Dy, Ho, Er, Tm, Yb, and Lu, and when a metal element other than In and Zn is element X, the atomic ratios satisfy the following formulas (17) and (18): [Zn] / ([In]+[Zn]+[X])<12 at% (17) [X] / ([In]+[Zn]+[X])<8.0 at% (18) The metal elements may include inevitable impurities, and may further include F or H in addition to O. By setting the composition within the above range, the In ratio becomes large, and crystallization into a bixbyite structure in which Zn substitutes for the In site can be achieved at an annealing temperature of about 300°C. By adding Zn, the film can be made amorphous immediately after deposition, and can be processed without leaving any residue when semiconductor patterning is performed with acid in the production of semiconductor devices such as transistors. Furthermore, by adding an additive element X that has a strong bond with oxygen, oxygen deficiency after annealing can be suppressed, and a stable film can be formed as a semiconductor.

[0048] In another embodiment, the oxide semiconductor film of this embodiment contains indium oxide as a main component and has an amorphous structure in which no X-ray diffraction pattern is observed by X-ray diffraction or no electron diffraction spots are observed by electron diffraction. The oxide semiconductor film of this embodiment is determined to have an amorphous structure when neither an X-ray diffraction pattern nor an electron diffraction spot is observed. The oxide semiconductor film of this embodiment may have a bixbyite structure as described above, or may have an amorphous structure. Even when the oxide semiconductor film of this embodiment has an amorphous structure, the oxide semiconductor film exhibits reduced carrier concentration and high hole mobility.

[0049] In one embodiment, the oxide semiconductor film of this embodiment has a bixbyite structure, and the crystal plane relative to the surface of the underlayer in contact with the oxide semiconductor film is oriented in {111}. The fact that the oxide semiconductor film of this embodiment has a bixbyite structure can be confirmed by the above-mentioned X-ray diffraction method, electron beam diffraction, or other methods. When X-ray diffraction is selected, the fact that "the crystal plane relative to the surface of the underlayer in contact with the oxide semiconductor film is oriented in {111}" can be confirmed by the method described in the Examples. The crystal plane being oriented in {111} has the effect of enabling more uniform film formation on the underlayer due to the low surface energy of the {111} of the bixbyite structure of indium oxide.

[0050] In one embodiment, the oxide semiconductor film of this aspect has a thickness of less than 20 nm. The thickness of the oxide semiconductor film can be measured by X-ray reflectivity or cross-sectional TEM. Specifically, the measurement is carried out by the method described in the Examples. The measurement of the thickness by cross-sectional TEM is carried out based on a cross-sectional TEM observation image.

[0051] <Definition and Measurement Method of Film Thickness and Surface Roughness> Film thickness and surface roughness can be measured using a cross-sectional TEM. The reference line for film thickness and surface roughness does not necessarily need to be parallel to the supporting substrate, but may be parallel to the underlayer. The oxide semiconductor film is defined as a region where the metallic indium composition accounts for 50% or more of the total metal composition, and the distance between the two interfaces above and below the region is used as the film thickness. When the upper layer is air, the upper interface may be defined as the surface. When the upper and lower layers are not parallel, the film thickness may be the distance from the lower layer to the point where a perpendicular line from the lower layer intersects with the upper layer. The film thickness is preferably determined by using an average value obtained from three or more thin-sectioned cross-sectional TEM samples. The film thickness from each cross-sectional TEM sample is preferably obtained from an image of the interface with the underlayer in the perpendicular direction to the film thickness, which is 10 to 100 times larger than the film thickness. The surface roughness can be determined from a cross-sectional TEM image by tracing the irregularities at the interface between the oxide semiconductor film and the upper side, and calculating the arithmetic mean height Ra of the traced line in accordance with JIS B 0601-2001. The cross-sectional TEM is preferably obtained at a magnification such that, when a trace line is drawn at the interface between the noble metal oxide layer and the metal oxide semiconductor, there are five or more maximum values ​​and the difference between adjacent maximum and minimum values ​​can be clearly determined.

[0052] In one embodiment, when the oxide semiconductor film of this embodiment is used, for example, for various memory applications requiring finer spacing, the film thickness is preferably small, and is preferably less than 20 nm, and more preferably 16 nm or less, 12 nm or less, 10 nm or less, 8 nm or less, 6 nm or less, 5 nm or less, 4 nm or less, 3 nm or less, 2 nm or less, or 1 nm or less.

[0053] The film density of the oxide semiconductor film of this embodiment is 6.50 g / cm ３ It is preferable that the film density is 6.50 g / cm or more. ３ With a density as high as 6.75 g / cm or higher, the overlap of the 5s orbitals of In atoms increases, and high mobility can be expected. In addition, it is possible to cope with slight changes in the film state. The film density is preferably 6.75 g / cm. ３ More preferably, 6.85 g / cm ３ The upper limit of the film density is preferably 7.35 g / cm.３ or less, more preferably 7.25 g / cm ３ More preferably, 7.15 g / cm ３ The film density of the oxide semiconductor film is measured by the method described in Examples.

[0054] In one embodiment, the oxide semiconductor film of this embodiment has a carrier concentration of 5×10 at room temperature. １９ cm －３ or less or 1 x 10 １９ cm －３ The carrier concentration at room temperature is 5×10 １９ cm －３ or less or 1 x 10 １９ cm －３ If the carrier concentration is 5×10 or less, the semiconductor film can function more satisfactorily. １９ cm －３ may be equal to or less than 1×10 １９ cm －３ or less, more preferably 5 × 10 １８ cm ―３ or less, and more preferably 1×10 １８ cm ―３ The carrier concentration of the oxide semiconductor film is an index for controlling the threshold voltage of the transistor characteristics. １９ cm －３ or less or 1 x 10 １９ cm ―３ If the carrier concentration of the oxide semiconductor film is less than 100%, a more favorable off-state operation can be confirmed when the oxide semiconductor film is formed into a transistor. The carrier concentration of the oxide semiconductor film is measured by the method described in Examples.

[0055] In one embodiment, the oxide semiconductor film of this embodiment has a hole mobility of 40 cm ２ The hole mobility of the oxide semiconductor film is an index of the field-effect mobility of the transistor characteristics. ２ / Vs or more, the transistor operates satisfactorily. The hole mobility is preferably 45 cm ２ / Vs or more, more preferably 50 cm ２ / Vs or more, and more preferably 80 cm２ The hole mobility of the oxide semiconductor film is measured by the method described in Examples.

[0056] In one embodiment, the surface roughness Ra of the oxide semiconductor film of this embodiment is 0.6 nm or less. Unlike sputtering, when a film is formed by ALD, it is deposited atomically one layer at a time, so it conforms almost faithfully to the surface of the underlayer. Furthermore, the thinner the resulting film, the smaller the surface roughness Ra, and the thicker the film, the larger the surface roughness Ra. The surface roughness Ra of the oxide semiconductor film of this embodiment varies depending on the film thickness, but is preferably 0.5 nm or less, more preferably 0.4 nm or less, and even more preferably 0.3 nm or less. The surface roughness Ra of the oxide semiconductor film is measured by the method described in the Examples.

[0057] The oxide semiconductor film of this embodiment may be produced by any method as long as it has the above-described carbon concentration and hydrogen concentration ranges. Examples of the method include DC sputtering, AC sputtering, RF sputtering, ICP sputtering, reactive sputtering, ion plating, atomic layer deposition (ALD), PLD, MO-CVD, ICP-CVD, a sol-gel method, a coating method, and mist CVD. In one embodiment, the oxide semiconductor film is produced by atomic layer deposition (ALD). A method for producing an oxide semiconductor film by ALD will be described later.

[0058] 2. Method for Producing an Oxide Semiconductor Film A method for producing an oxide semiconductor film according to one aspect of the present invention (hereinafter, sometimes referred to as the method of this aspect) is a method for producing the oxide semiconductor film according to the above-described one aspect of the present invention, and is characterized by including a step of forming the oxide semiconductor film by atomic layer deposition (ALD) using an indium-containing precursor.

[0059] Atomic layer deposition (ALD) is a thin film formation method in which a substrate surface is alternately exposed to a raw material (sometimes referred to as a precursor) containing a metal element that constitutes the oxide semiconductor film and an oxidizing agent, forming one atomic layer per cycle. This cycle is repeated until a desired film thickness is achieved, thereby forming an oxide semiconductor film. Specific steps of ALD will be described later. ALD makes it possible to deposit ultrathin films of several nanometers in thickness using a precisely controlled method. Therefore, ALD is a method for forming oxide semiconductor films that is also suitable for the manufacture of recently developed three-dimensional vertical channel transistor memories and the like.

[0060] Generally, one ALD atomic layer deposition cycle consists of the following four steps: (1) The precursor (the raw material) is vaporized in a container containing the precursor and introduced into the chamber. A predetermined system pressure is applied and the precursor reacts with OH groups on the substrate or film surface for a predetermined time, resulting in monomolecular adsorption. If the vapor pressure of the precursor is low, the container containing the precursor may be heated to promote vaporization. If the vapor pressure of the precursor is high, the container containing the precursor may be cooled to suppress vaporization. (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 precursor metal is oxidized using heat, plasma, or the like. (4) Unreacted oxidant 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) are repeated until the desired film thickness is achieved.

[0061] In the method of this embodiment, a well-known ALD apparatus can be used. Specific examples include an apparatus capable of supplying a precursor by bubbling, and an apparatus having a vaporization chamber. Also included are apparatuses capable of performing plasma treatment on a reactive gas (oxidizer). The apparatus is not limited to a single-wafer apparatus equipped with a deposition chamber, and an apparatus capable of simultaneously processing multiple wafers using a batch furnace can also be used.

[0062] The types of ALD precursors include organometallics (e.g., AlMe ３ ), metal hydrides (e.g., AsH３ ), metal alkoxides (e.g., Ti(OCHMe ２ ) ４ ), metal amides (e.g., Ti(NMe ２ ) ４ ), β-diketonates (e.g., Co(acac) ２ ), metallocenes (e.g., MgCp ２ ), metal amidinates, etc. Various metal compounds used as ALD precursors are commercially available, and a precursor and an oxidizing agent capable of forming a desired oxide semiconductor film may be selected.

[0063] Indium oxide (In ２ O ３ Indium-containing precursors used to deposit layers of InCl by ALD include, for example, 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 ２Examples of the ALD precursor include In(EDPA) (dimethyl(N-ethoxy-2,2-dimethylpropanamido)indium), tris(N,N'-diisopropylacetamidinato)indium(III), etc. These ALD precursors may be used alone or in combination of two or more.

[0064] Furthermore, when the metal cations constituting the oxide semiconductor film are mainly composed of In, a thin film may be formed using a precursor containing other metal cations as an additive.

[0065] Examples of the precursor include a compound of indium or a metal cation with one or more compounds selected from the group consisting of compounds used as organic ligands, such as alcohol compounds, glycol compounds, β-diketone compounds, cyclopentadiene compounds, and organic amine compounds.

[0066] For example, metal cations 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.

[0067] Further, examples of compounds that coordinate to metal cations containing indium include the following. Depending on the valence of the central metal, multiple coordination species from the following coordination species are coordinated, but they may be the same compound, or multiple different coordination species may be combined.

[0068] Examples of the alkyl compounds include methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, isobutyl, tert-butyl, pentyl, isopentyl, and tert-pentyl.

[0069] Examples of alcohol compounds include alkyl alcohols such as methanol, ethanol, propanol, isopropyl alcohol, butanol, sec-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, pentyl alcohol, isopentyl alcohol, and tert-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-1,1-dimethylethanol. Examples thereof include ether alcohols such as ethanol, 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 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 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-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 the cyclopentadiene compound include cyclopentadiene, methylcyclopentadiene, ethylcyclopentadiene, propylcyclopentadiene, isopropylcyclopentadiene, butylcyclopentadiene, sec-butylcyclopentadiene, isobutylcyclopentadiene, tert-butylcyclopentadiene, dimethylcyclopentadiene, and tetramethylcyclopentadiene.

[0073] Examples of the organic amine compound include methylamine, ethylamine, propylamine, isopropylamine, butylamine, sec-butylamine, tert-butylamine, isobutylamine, dimethylamine, diethylamine, dipropylamine, diisopropylamine, ethylmethylamine, propylmethylamine, and isopropylmethylamine.

[0074] Alternatively, chloride or fluoride may be coordinated to the metal cation, or a combination of chloride or fluoride with a compound that coordinates to the metal cation may be used. Also, some or all of the hydrogen atoms in the compound that coordinates to the metal cation may be replaced with chlorine or fluorine.

[0075] Specifically, examples of gallium-containing precursors include trimethylgallium (TMG), triethylgallium (TEG), and gallium triisopropoxide (Ga(OCH(CH ３ ) ２ ) ３ ), gallium trimethoxide (Ga(OCH ３ ) ３ ), gallium trichloride (GaCl ３ ), gallium dichloride dimethylamide (GaCl ２ (N(CH ３ ) ２ )), gallium acetylacetonate (Ga(acac) ３ ), gallium triimide (Ga(NR) ３ , where R is an organic group), gallium tris(2,2,6,6-tetramethyl-3,5-heptanedione) (Ga(tmhd) ３ cyclopentadienylgallium(I) (GaCp), cyclopentadienylgallium(I) (GaEtCp), and ethylcyclopentadienylgallium(I) (GaEtCp). Among these, the gallium-containing precursor is preferably at least one selected from the group consisting of trimethylgallium and triethylgallium.

[0076] Among these precursors, trimethylaluminum, trimethylgallium, triethylgallium, dimethylzinc, and diethylzinc can be used in combination with an indium-based precursor to form an excellent oxide semiconductor film. Among these, trimethylgallium and triethylgallium are particularly preferred.

[0077] Precursors coordinated with the above-mentioned compounds are known in the art, and their production methods are also known. For example, when an alcohol compound is used as the organic ligand, the precursor can be produced by reacting the inorganic salt of the metal or a hydrate thereof described above with an alkali metal alkoxide of the alcohol compound. Examples of inorganic salts of metals or hydrates thereof include metal halides and nitrates. Examples of alkali metal alkoxides include sodium alkoxides, lithium alkoxides, and potassium alkoxides.

[0078] The oxidizing agent used in ALD is H ２ O, O ２ , O ３ , O ２ Plasma, H ２ O plasma, hydrogen peroxide (H ２ O ２ These oxidizing agents may be used alone or in combination of two or more.

[0079] When two or more oxidizing agents are used, the two or more oxidizing agents may be used simultaneously, or the two or more oxidizing agents may be used individually while changing. For example, O ２ Plasma and H ２ By using two types of plasma, O ２ The high mobility obtained when using plasma and H ２ It is possible to utilize both the advantages of using O plasma, namely, the reduction in carbon concentration and the improvement in stability of mobility against heat treatment. By using two or more oxidizing agents, it is possible to adjust high mobility and low carbon concentration. Depending on the desired effect, O ２ Plasma and H ２The proportion of O plasma used, the order of use, the number of cycles, etc. may be selected appropriately.

[0080] 6 to 8 show the results of the experiments using O as an oxidizing agent. ２ Plasma and H ２ 6 is a graph showing the relationship between carrier concentration and hole mobility when two types of O plasma are used. ２ Plasma and H ２ When O plasma was used at a ratio of 1:1 (shown by ● in the graph), O ２ When only plasma was used (indicated by square), H ２ It can be seen that the hole mobility is almost intermediate between that when only O plasma is used (indicated by triangles). ２ Plasma and H ２ When O plasma was used at a ratio of 3:1 (shown by ○ in the graph) and when O plasma was used at a ratio of 5:1 (shown by ●), O ２ Compared to using plasma only (indicated by squares), ２ The influence of O plasma is suppressed, and O ２ It can be seen that the behavior is similar to that of plasma. ２ 6 cycles with O plasma, then O ２ When 170 cycles were performed with plasma (indicated by a circle in the graph), and H ２ 30 cycles with O plasma, followed by O ２ When 130 cycles were performed with plasma (indicated by ●), and ２ When plasma only was used (indicated by squares), and when H ２ 8 is a graph showing the relationship between carrier concentration and hole mobility when only O plasma is used (indicated by triangles). ２ In 6 cycles with O plasma (○), O ２ It is close to the case where only plasma is used (□), and H ２ It can be seen that stable hole mobility is obtained with 30 cycles (●) of O plasma.

[0081] The types of precursors and oxidizing agents are as described above. In one embodiment of the method of this aspect, triethylindium is used as the indium-containing precursor. In one embodiment, a gallium-containing precursor is used in addition to the indium-containing precursor.

[0082] The pressure of the system (inside the film formation chamber) in step (1) may be set appropriately depending on the type of precursor, the substrate temperature, etc., and is, for example, preferably 1 to 10,000 Pa, more preferably 10 to 1,000 Pa, even more preferably 50 to 500 Pa, and particularly preferably 80 to 120 Pa.

[0083] In one embodiment, in the film forming process, H ２ In one embodiment, O plasma is used as an oxidizing agent in the film formation process. ２ In one embodiment, plasma is used as an oxidizing agent in the film formation process. ３ By using these oxidizing agents, the electrical characteristics of the oxide semiconductor film can be controlled to be favorable.

[0084] In one embodiment, the oxide semiconductor film formed is an indium oxide film.

[0085] To vaporize the precursor, the container containing the precursor may be heated as needed to a temperature at which the precursor is sufficiently vaporized. When 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 temperature is preferably in the range of 50 to 150°C, more preferably 75 to 125°C.

[0086] In the method of this embodiment, the substrate temperature during film formation is usually within 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.

[0087] The growth amount of the oxide semiconductor film per cycle of the ALD process varies depending on the precursor and reactive gas used during film formation, as well as the substrate temperature during film formation. ２ O plasma and O ２ FIG. 1 shows the growth amount of an oxide semiconductor film when the substrate temperature is changed using plasma. The substrate temperature during film formation is preferably in a range in which the film growth amount is stable. From the graph in FIG. ２ O plasma and O ２ When plasma is used, it is found that a substrate temperature in the range of 100 to 150° C. during film formation is suitable because the amount of growth is stable.

[0088] The growth amount per cycle of the ALD process is called Growth Per Cycle (GPC), and can be calculated by measuring the film thickness of the oxide semiconductor film after repeating, for example, 30 ALD cycles. Here, GPC varies depending on the combination of precursor, oxidant, and substrate temperature, and also varies depending on the type of substrate. Therefore, the number of cycles varies depending on many factors, such as the type and combination of precursor and oxidant used, the type of substrate, the substrate temperature during film formation, and the desired film thickness, and can be appropriately set taking these factors into consideration.

[0089] In addition, O ３ When using the above, the substrate temperature during film formation is preferably above 100°C, more preferably 110 to 250°C, 120 to 230°C, or 130 to 220°C.

[0090] Examples of inert gases that can be used to purge unreacted raw materials and unreacted oxidizing agent include argon and nitrogen, and in the method of this embodiment, argon or nitrogen is preferred.

[0091] In the method of this aspect, in the step (3) above, plasma of the reactive gas (oxidant) is preferably generated.

[0092] A transistor according to one embodiment of the present invention (hereinafter sometimes referred to as the transistor of this embodiment) includes a layer made of the oxide semiconductor film according to the above embodiment of the present invention, an insulating film layer, and an electrode. The layer made of the oxide semiconductor film according to the above embodiment functions as a channel layer in the transistor.

[0093] The transistor of this embodiment may have any structure as long as it includes a layer including the oxide semiconductor film of one embodiment of the present invention, for example, any of the structures shown in FIGS.

[0094] In one embodiment, the transistor of this aspect is a bottom-gate, top-contact type.In one embodiment, the transistor of this aspect is a top-gate, top-contact type.

[0095] The insulating film layer may be appropriately selected from materials commonly used as insulating film layers of transistors. The insulating film functioning as a gate insulating film can be an insulating film containing one or more of aluminum oxide, magnesium oxide, silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, gallium oxide, germanium oxide, yttrium oxide, zirconium oxide, lanthanum oxide, neodymium oxide, hafnium oxide, and tantalum oxide. The insulating film may also be a stack of the above materials. The insulating film may contain La, N, Zr, or the like as an impurity. An example of a stacked structure of an insulating film will now be described. The insulating film contains, for example, oxygen, nitrogen, silicon, hafnium, or the like. Specifically, it is preferable to include hafnium oxide and silicon oxide or silicon oxynitride. Hafnium oxide and aluminum oxide have a higher dielectric constant than silicon oxide or silicon oxynitride. Therefore, compared to a case where silicon oxide is used, the insulating film can be made thicker for the same insulating film capacitance, thereby reducing leakage current due to tunneling current. That is, a transistor with a low off-state current can be realized. Furthermore, hafnium oxide having a crystalline structure has a higher dielectric constant than hafnium oxide having an amorphous structure. Therefore, in order to obtain a transistor with a small off-state current, it is preferable to use hafnium oxide having a crystalline structure. Examples of the crystalline structure include, but are not limited to, monoclinic and cubic systems.

[0096] In one embodiment, the insulating film layer is primarily composed of hafnium oxide. "To be primarily composed of hafnium oxide" means that more than 50% by mass of the material constituting the insulating film layer is hafnium oxide. Hafnium oxide 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, 99% by mass or more, or even 100% by mass. Having hafnium oxide as the primary component of the insulating film layer has the advantage of increasing the dielectric constant of the insulating film.

[0097] In one embodiment, the insulating film layer is primarily composed of silicon oxide. In another embodiment, the insulating film layer is primarily composed of aluminum oxide. The meaning of "primarily composed of" is the same as that of hafnium oxide described above.

[0098] The electrodes are gate electrodes and source / drain electrodes, and can be formed from materials typically used for transistor electrodes. In one embodiment, the electrodes are primarily composed of titanium nitride. In another embodiment, the electrodes are primarily composed of tungsten. By using titanium nitride or tungsten as the primary component of the electrodes, the effect of reducing contact resistance, which is a parasitic resistance, can be obtained for the oxide semiconductor film. Furthermore, by selecting titanium nitride or tungsten as the electrode material, film formation by ALD becomes possible.

[0099] (Method for manufacturing a transistor) The transistor of this embodiment can be manufactured in the same manner as a normal transistor, except that the oxide semiconductor film layer is formed by ALD. The oxide semiconductor film layer in the transistor manufacturing process can be formed by the method described in the Examples. The components other than the channel layer in the transistor and the manufacturing method thereof are not particularly limited, and known materials, configurations, and manufacturing methods can be used.

[0100] Transistors having various structures such as those shown in FIGS. 2A to 2D can be manufactured, for example, as follows. For example, a silicon substrate with a thermal oxide film is used, with the silicon substrate functioning as a gate electrode and the thermal oxide film functioning as a gate insulating film layer. An oxide semiconductor film layer is formed thereon by the ALD method and patterned. The oxide semiconductor film layer functions as a channel layer. Next, a metal film for forming source and drain electrodes is formed on the oxide semiconductor layer. Thereafter, source and drain electrodes are formed using a lift-off process or the like to complete the transistor. If necessary, a protective film may also be formed.

[0101] <Fabrication Process of Bottom-Gate Transistor> A method for manufacturing a transistor substrate having an oxide semiconductor layer will be described using a bottom-gate transistor as an example. A gate electrode is patterned on a substrate made of glass or the like. The gate electrode material is composed of a single layer or a laminate film of two or more types of materials, such as molybdenum, tungsten, aluminum and aluminum alloys, copper and copper alloys, titanium, and platinum. A gate insulating film is formed on the gate electrode. Gate insulating films are generally silicon oxide films, silicon nitride films, silicon oxynitride films, etc., formed by PE-CVD. The thickness of the gate insulating film is usually 10 to 300 nm. A silicon substrate with a thermal oxide film (substrate resistance of 0.1 Ωcm or less) may be considered as a gate insulating film substrate with a gate electrode. The oxide semiconductor layer on the gate insulating film can be formed by a sputtering method in which a sputtering target of the same composition as the oxide semiconductor is deposited by DC sputtering or RF sputtering; an ALD method in which a film is formed using an organic metal as a precursor; or a liquid-phase method in which an oxide semiconductor layer is formed by applying and baking a precursor solution of a metal alkoxide, a metal organic acid salt, a chloride, or the like, or a dispersion of oxide semiconductor nanoparticles. After patterning the oxide semiconductor layer, source and drain electrodes are patterned. Materials for the source and drain electrodes include molybdenum, tungsten, aluminum and aluminum alloys, copper and copper alloys, titanium, platinum, and the like, and are formed as a single layer or a laminate film of two or more types. After the source and drain electrode layers are formed, a protective film may be formed. The protective film can be, for example, a SiO formed by an ALD method or a CVD method. ２ Alternatively, aluminum oxide formed by RF sputtering or aluminum oxide formed by introducing oxygen into DC sputtering may be used.

[0102] <Step of Annealing the Transistor with the Protective Film Formed> Finally, the transistor is annealed. In devices including oxide semiconductors, protective film formation involves film formation by PVD or CVD, patterning by dry etching or wet etching, and resist stripping. However, these processes can sometimes cause degradation of transistor performance. Therefore, it is desirable to restore performance and adjust carrier concentration through annealing. In the present invention, by performing annealing at, for example, 250°C or higher, the performance of the transistor can be restored even if it is temporarily degraded during patterning. In particular, the present invention is characterized in that even if the transistor characteristics are significantly degraded, annealing in the presence of oxygen can significantly restore performance. Furthermore, depending on the degree of degradation of the oxide semiconductor, increasing the annealing temperature or extending the annealing time can improve transistor performance recovery and device reliability. The annealing temperature is 250°C or higher and 450°C or lower, preferably 300°C or higher and 400°C or lower. The annealing time is 30 minutes or longer, preferably 60 minutes or longer. Annealing is preferably carried out in the presence of oxygen. However, when annealing in the presence of oxygen, it is preferable to carry out the annealing at 400° C. or less, taking into consideration the effects of oxidation of the electrode and coloration due to oxidation of the protective film of the present invention. Annealing may also be carried out in a nitrogen atmosphere.

[0103] <Exposure Step> When patterning the oxide semiconductor layer, electrode, and protective film, a resist is applied and its surface is irradiated with light. Any light source conventionally used in pattern formation methods can be used for the light irradiation. Examples of such light sources include high-pressure mercury lamps, low-pressure mercury lamps, metal halide lamps, xenon lamps, laser diodes, LEDs, and the like. Ultraviolet rays such as g-line, h-line, and i-line are typically used as the irradiated light. Except for ultrafine processing such as semiconductors, light of 360 to 430 nm (high-pressure mercury lamps) is generally used for patterning of several μm to several tens of μm. In particular, light of 430 nm is often used for liquid crystal display devices. The energy of the irradiated light varies depending on the light source and the film thickness of the protective film precursor layer, but is generally 20 to 2000 mJ / cm for positive-tone diazonaphthoquinone derivatives. ２ , preferably 50 to 1000 mJ / cm ２ The irradiation light energy is 20 mJ / cm ２ If the intensity is lower than 2000 mJ / cm, sufficient resolution may not be obtained. ２ If the exposure is higher than 1000 mJ / cm 2 , the exposure may be excessive, which may cause halation. ２ , preferably 10 to 100 mJ / cm ２ The irradiation light energy is 1 mJ / cm ２ If it is lower than 500 mJ / cm, the film loss will be large. ２ If it is higher than this, overexposure may occur and resolution may not be obtained.

[0104] A general photomask can be used to irradiate light in a pattern. Such a photomask can be arbitrarily selected from well-known photomasks. The environment during irradiation is not particularly limited, but generally, the ambient atmosphere (air) or a nitrogen atmosphere can be used. Furthermore, when a film is formed on the entire surface of a substrate, the entire surface of the substrate can be irradiated with light. In the present invention, the patterned film also includes such a case where a film is formed on the entire surface of the substrate.

[0105] <Post-Exposure Baking Step> After exposure, post-exposure baking can be performed as needed to promote the inter-polymer reaction in the film by the reaction initiator generated at the exposed areas. This heating treatment is not performed to completely harden the photoresist layer, but is performed so that only the desired pattern remains on the substrate after development and the remaining parts can be removed by development.

[0106] <Development Step> After exposure and, if necessary, post-exposure baking, the photoresist is developed. The developer used in development can be any developer conventionally used for developing photosensitive polymer materials or photosensitive siloxane compositions. Preferred developers include alkaline developers, which are aqueous solutions of alkaline compounds such as tetraalkylammonium hydroxide, choline, alkali metal hydroxides, alkali metal metasilicate (hydrates), alkali metal phosphate (hydrates), ammonia, alkylamines, alkanolamines, and heterocyclic amines. A particularly preferred alkaline developer is an aqueous TMAH solution. These alkaline developers may further contain water-soluble organic solvents such as methanol and ethanol, or surfactants, as needed. The development method can also be selected from conventional methods. Specific examples include immersion (dipping), puddling, showering, slitting, cap coating, and spraying in the developer. A pattern can be obtained by this development. After development with the developer, it is preferable to wash the substrate with water. In this manufacturing method, the drain electrode can be electrically connected to a transparent electrode (pixel electrode) formed on the protective film through a contact hole formed by development.

[0107] <Post-development irradiation step> When a positive composition is used and the formed protective film is to be a transparent film, it is preferable to carry out light irradiation called bleaching exposure. By carrying out bleaching exposure, unreacted diazonaphthoquinone derivative remaining in the film is photodecomposed, thereby further improving the optical transparency of the film. As a method of bleaching exposure, a high-pressure mercury lamp, a low-pressure mercury lamp, or the like is used, and 100 to 2,000 mJ / cm is applied depending on the film thickness.２ The entire surface is exposed to about 100 to 2,000 mJ / cm (equivalent to the exposure dose at a wavelength of 365 nm). In the case of a negative type, the light irradiation activates the curing aid in the remaining film after development, making subsequent heat curing easier. Depending on the film thickness, the exposure dose is 100 to 2,000 mJ / cm. ２ The entire surface is exposed to about 1000 nm of light (equivalent to an exposure dose at a wavelength of 365 nm).

[0108] The top-gate-top-contact transistor shown in FIG. 2D can be manufactured, for example, as follows. A first insulating film is formed on a substrate made of glass, silicon, or the like. Examples of materials for the first gate insulating film include a single layer or a laminate film of two or more types of materials, such as hafnium oxide, aluminum oxide, silicon oxide, zirconium oxide, and tantalum oxide. In one embodiment, cleaning can be performed on a silicon substrate. A solution (Sulfuric Acid-Hydrogen Peroxide Mixture, abbreviated as SPM solution) containing 1 volume of concentrated sulfuric acid and 0.25 to 1 volume of hydrogen peroxide is heated to around 130°C to remove organic contaminants, and then the silicon substrate is subsequently cleaned with a 1% aqueous solution of hydrofluoric acid to remove the oxide film on the surface. In one embodiment, the silicon substrate is then heated to 250°C, and a hafnium oxide film can be formed by ALD. For example, when a hafnium oxide layer is formed by an ALD apparatus, a first source gas obtained by vaporizing a liquid containing a solvent and a hafnium precursor compound (hafnium alkoxide or hafnium amide such as tetrakisdimethylamidohafnium (TDMAHf)) and ozone (O ３ ) and oxygen (O ２ ) is used as the second source gas. When TDMAHf is used as the first source gas, TDMAHf is supplied from the source supply unit, and the second oxidizing gas supplied from the source supply unit is oxygen. When oxidizing with oxygen, the first source gas may be oxidized by plasma generation. When forming a hafnium oxide film using TDMAHf, the substrate temperature is preferably 100°C to 600°C, more preferably 150°C to 500°C, and from the viewpoint of damage to the device, it is better to set it in the range of 200°C to 400°C, and more preferably 250°C.

[0109] Here, the process of forming a metal oxide film on a substrate in a processing vessel may be performed sequentially, specifically, by supplying a source gas containing an organometallic precursor into the processing vessel, removing residual gas remaining in the processing vessel after the source gas supply step, and subsequently supplying an oxidizing agent into the processing vessel to oxidize the source gas, and removing residual gas remaining in the processing vessel after the oxidizing agent supply step.

[0110] In one embodiment, to deposit a 5 nm hafnium oxide film using TDMAHf, the above steps may be repeated sequentially for 54 cycles at a substrate temperature of 250° C. using oxygen plasma as the oxidizing agent for a plasma oxidation time of 20 seconds.

[0111] After the first insulating film is formed, an oxide semiconductor layer can be formed. Indium oxide is suitable for the oxide semiconductor layer, but a composite oxide containing one or more elements selected from the group consisting of gallium oxide, aluminum oxide, tin oxide, and zinc oxide may also be used.

[0112] When forming an indium oxide layer, a sputtering method using a ceramic target made of indium oxide may be used, or film formation using an ALD method using an indium precursor may be used. When using the ALD method, the indium precursor may be any of the compounds listed above, or trimethylindium, triethylindium, or cyclopentadienylindium. Here, examples of combinations of oxidizing agents when triethylindium is used as the source gas include oxygen, oxygen plasma, ozone, water, and water plasma. Here, the treatment temperature for the oxidizing agent is preferably room temperature to 500°C, more preferably 50°C to 200°C, and the preferred film formation temperature is 100°C to 150°C. If one cycle is defined as the steps from the step of supplying the ALD raw material gas to the step of removing the residual gas remaining in the processing vessel after the step of supplying the oxidizing agent, the film thickness formed per cycle is called GPC (growth per cycle). When triethylindium is oxidized with water plasma at a substrate temperature of 150°C, the GPC tends to be 0.7±0.2 Å / cycle, when triethylindium is oxidized with oxygen plasma at a substrate temperature of 150°C, the GPC tends to be 0.6±0.2 Å / cycle, and when triethylindium is oxidized with ozone at a substrate temperature of 150°C, the GPC tends to be 0.5±0.2 Å / cycle.

[0113] The oxide semiconductor layer is preferably formed to a thickness in the range of 1 Å to 100 nm, more preferably 1 nm to 50 nm. In a microdevice, the parasitic capacitance of the oxide semiconductor layer becomes a problem, so the thickness is 1 nm to 30 nm, more preferably 1 nm to 10 nm, and a suitable range is 1 nm to 5 nm.

[0114] If the oxide semiconductor layer formed is amorphous, it can be easily patterned by wet etching. Patterning can be performed using a resist, with reference to the description of the bottom gate above. The etching agent is preferably one that can dissolve the oxide semiconductor layer but is insoluble in the first insulating film layer, allowing for a selectivity ratio. For example, a hydrochloric acid solution, an oxalic acid solution, or the like can be used. When the crystalline component is high, a hydrochloric acid solution is preferred, and when the amorphous component is predominant, an oxalic acid solution, which is less likely to leave residue, is preferred.

[0115] The oxide semiconductor film patterned into a desired shape can then be annealed to improve its crystallinity. The annealing atmosphere is generally in vacuum, nitrogen, or air. In the case of an air atmosphere, the annealing temperature is preferably 250° C. to 600° C., more preferably 300° C. to 500° C., and the suitable annealing temperature is 350° C. to 450° C. The annealing time is 5 minutes to 2 hours, preferably 30 minutes to 1 hour.

[0116] Next, a second insulating film is formed. The second insulating film can be formed using the same material and method as the first insulating film. When the second insulating film is used as the gate insulating film of a microdevice, it is desirable to make it as thin as possible so that the capacitance of the gate insulating film does not become a parasitic component. For devices with an element size of 50 nm or less, the thickness is preferably 1 Å to 10 nm, more preferably 5 Å to 5 nm, and suitably 10 Å to 2 nm.

[0117] In one embodiment, a hafnium oxide film can be formed using TDMAHf, similar to the first insulating film. Subsequently, contact holes can be formed in the second insulating film by dry etching. When the second insulating film is hafnium oxide, dry etching can be performed using a mixture of chlorine gas and argon gas.

[0118] Next, the gate electrode and source / drain electrodes can be formed. The electrodes are made of titanium nitride, molybdenum, tungsten, aluminum and aluminum alloys, copper and copper alloys, titanium, platinum, or other materials, either as a single layer or as a laminate film of two or more types.

[0119] In one embodiment, the gate electrode and the source / drain electrodes are formed by forming a titanium nitride film by sputtering on a lift-off resist and patterning it.

[0120] Finally, the device characteristics can be stabilized by annealing the fabricated top-gate transistor. The annealing atmosphere is generally vacuum, nitrogen, or air. In the case of air, the annealing temperature is preferably 250°C to 600°C, more preferably 300°C to 500°C, and the suitable annealing temperature is 350°C to 450°C. The annealing time is 5 minutes to 2 hours, preferably 30 minutes to 1 hour.

[0121] In one embodiment, the annealing can be performed at 300° C. in an argon atmosphere or 350° C. in air.

[0122] When fabricating the three-dimensional vertical channel transistor memory shown in FIG. 3A , if a channel layer made of an oxide semiconductor film is formed by sputtering, the opening in the base layer to be covered with the oxide semiconductor film is narrow and cylindrical in the vertical direction, as shown in FIG. 3B . Therefore, the oxide semiconductor film can only be formed near the opening in the cylindrical base layer. In contrast, according to the transistor fabrication method of this embodiment, the oxide semiconductor film layer (channel layer) is formed by ALD. Therefore, even if the opening in the base layer is narrow and cylindrical in the vertical direction, the entire inner surface of the base layer can be uniformly covered with the oxide semiconductor film, as shown in FIG. 3C , resulting in a highly reliable transistor memory. The three-dimensional vertical channel transistor may be a three-dimensional vertical channel all-around type as shown in FIG. 3A , or a three-dimensional vertical gate all-around type. Other three-dimensional vertical channel types include, for example, FinFET and trench gate transistors.

[0123] 4. Semiconductor Device A semiconductor device according to one aspect of the present invention includes the transistor according to the above aspect of the present invention. By including the transistor according to the above aspect, the semiconductor device according to this aspect has excellent electrical characteristics and high reliability. In this specification, the term "semiconductor device" includes display transistors, memory FETs (DRAM, NAND, ReRAM, FeRAM, MRAM), logic IC FETs (CPU, MPU, BEOL, 3D-LSI, CMOS), sensor FETs (CMOS image sensors), and transistors (MOSFETs, power transistors, MESFETs), etc.

[0124] 5. Electronic Circuit An electronic circuit according to one aspect of the present invention includes the semiconductor device according to the above aspect of the present invention. By including the semiconductor device according to the above aspect, the electronic circuit according to this aspect has excellent electrical properties and high reliability.

[0125] 6. Electrical Device, Electronic Device, Vehicle, or Power Engine An electrical device, electronic device, vehicle, or power engine according to one aspect of the present invention is characterized by including the electronic circuit according to the above-described aspect of the present invention. By including the electronic circuit according to the above-described aspect, the electrical device, electronic device, vehicle, or power engine according to this aspect has excellent electrical characteristics and high reliability.

[0126] The present invention will be explained in more detail below using examples and comparative examples, but the present invention is not limited to these examples at all.

[0127] <Oxide Semiconductor Film Production 1> Using triethylindium as an indium precursor and an ALD apparatus (apparatus name: Fiji F200; manufactured by Veeco), an oxide semiconductor film was produced on a glass substrate by ALD under the conditions and steps described in the following Examples 1 to 18. In the following Example 19, an oxide semiconductor film was produced by sputtering.

[0128] The obtained oxide semiconductor film was subjected to measurement of film thickness and film density by X-ray reflectometry (XRR), measurement of carbon concentration and hydrogen concentration in the film by SIMS measurement, measurement of Hall mobility and carrier concentration by Hall measurement, confirmation of crystal orientation by X-ray diffraction (XRD), confirmation of the presence or absence of a bixbyite structure by planar TEM or cross-sectional TEM, and measurement of surface roughness Ra of the thin film surface by atomic force microscope (AFM). The results are shown in Table 1.

[0129] Example 1 An oxide semiconductor film was manufactured under the following conditions and steps. (Conditions) Substrate temperature during film formation: 100°C Reactive gas (oxidizing agent): O ２ (Steps) A series of steps (1) to (4) below constitute one cycle, and 51 cycles were repeated. (1) Triethylindium vapor, vaporized under conditions of a source container heating temperature of 95°C, was introduced into the chamber by opening the valve for 0.06 seconds and exposed to the substrate surface or film surface for 15 seconds at a system pressure of 100 Pa to allow reaction and adsorption. (2) Unreacted source material was removed by argon purging for 15 seconds. (3) The valve of the oxygen cylinder was opened to introduce oxygen into the chamber at a flow rate of 50 sccm, and the chamber was allowed to stabilize for 10 seconds. Thereafter, plasma was generated for 20 seconds using an RF power supply with an output of 300 W. The RF power supply was turned off and the valve was closed. (4) Unreacted source material was removed by argon purging for 45 seconds.

[0130] Example 2 An oxide semiconductor film was produced in the same manner as in Example 1, except that the number of cycles during film formation was 85.

[0131] Example 3 An oxide semiconductor film was produced in the same manner as in Example 1, except that the number of cycles during film formation was 254.

[0132] Example 4 An oxide semiconductor film was produced in the same manner as in Example 1, except that the substrate temperature during film formation was set to 150° C. and the number of cycles was set to 53.

[0133] Example 5 An oxide semiconductor film was produced in the same manner as in Example 1, except that the substrate temperature during film formation was set to 150° C. and the number of cycles was set to 88.

[0134] Example 6 An oxide semiconductor film was manufactured in the same manner as in Example 1, except that the substrate temperature during film formation was set to 150° C. and the number of cycles was set to 263.

[0135] Example 7 An oxide semiconductor film was produced in the same manner as in Example 1, except that the substrate temperature during film formation was set to 250° C. and the number of cycles was set to 273.

[0136] Example 8 An oxide semiconductor film was manufactured under the following conditions and steps. (Conditions) Substrate temperature during film formation: 100° C. Reactive gas (oxidizing agent): H ２ O (Steps) A series of steps (1) to (4) below constitute one cycle, and 43 cycles were repeated. (1) Triethylindium vapor, vaporized under the condition of a source container heating temperature of 95°C, was introduced into the chamber by opening the valve for 0.06 seconds, and exposed to the substrate surface or film surface for 15 seconds at a system pressure of 100 Pa to react and adsorb. (2) Unreacted source material was removed by argon purging for 15 seconds. (3) H ２ Argon is bubbled through a cylinder containing O, and the resulting water vapor is introduced into the chamber at a flow rate of 30 sccm by opening the valve. Wait 10 seconds for stabilization. Then, a plasma is generated for 20 seconds using an RF power supply with an output of 300 W. The RF power supply is turned off, and the valve is closed. (4) Unreacted raw materials are removed by purging with argon for 45 seconds.

[0137] Example 9 An oxide semiconductor film was produced in the same manner as in Example 8, except that the number of cycles during film formation was 71.

[0138] Example 10 An oxide semiconductor film was produced in the same manner as in Example 8, except that the number of cycles during film formation was 214.

[0139] Example 11 An oxide semiconductor film was produced in the same manner as in Example 8, except that the substrate temperature during film formation was set to 150° C. and the number of cycles was set to 43.

[0140] Example 12 An oxide semiconductor film was produced in the same manner as in Example 8, except that the substrate temperature during film formation was set to 150° C. and the number of cycles was set to 71.

[0141] Example 13 An oxide semiconductor film was manufactured in the same manner as in Example 4, except that the substrate temperature during film formation was set to 150° C. and the number of cycles was set to 429.

[0142] Example 14 An oxide semiconductor film was produced in the same manner as in Example 8, except that the substrate temperature during film formation was set to 250° C. and the number of cycles was set to 309. The film density was measured by XRR and found to be 7.15 g / cm ２ It was.

[0143] Example 15 An oxide semiconductor film was produced under the following conditions and steps. (Conditions) Substrate temperature during film formation: 100°C Reactive gas: O ３ (Steps) A series of steps (1) to (4) below constitute one cycle, and 111 cycles were repeated. (1) Triethylindium vapor, vaporized under conditions of a source container heating temperature of 95°C, was introduced into the chamber by opening the valve for 0.06 seconds, and exposed to the substrate surface or film surface for 15 seconds at a system pressure of 100 Pa to allow reaction and adsorption. (2) Unreacted source material was removed by argon purging for 15 seconds. (3) Oxygen gas was supplied to the ozonizer at a flow rate of 500 sccm, and ozone was generated by silent discharge. The ozone-containing oxygen gas was introduced into the chamber by opening the valve for 0.6 seconds. (4) Unreacted source material was removed by argon purging for 45 seconds.

[0144] Example 16 An oxide semiconductor film was produced in the same manner as in Example 15, except that the number of cycles during film formation was 333.

[0145] Example 17 An oxide semiconductor film was produced in the same manner as in Example 15, except that the substrate temperature during film formation was set to 150° C. and the number of cycles was set to 100.

[0146] Example 18 An oxide semiconductor film was produced in the same manner as in Example 15, except that the substrate temperature during film formation was set to 150° C. and the number of cycles was set to 300.

[0147] Example 19 An oxide semiconductor film was formed by sputtering using indium oxide as a sputtering target under the following sputtering conditions: substrate temperature during film formation: 25°C (room temperature); atmospheric gas: Ar+H ２O mixed gas (H ２ O flow rate ratio 2%) Sputtering pressure (total pressure): 0.5 Pa Input voltage: DC 400 W Distance between S (substrate) and T (target): 70 mm

[0148]

[0149] In the table, "film formation temperature" means the substrate temperature during the film formation, and "E+XX" means "×10 ＸＸ " means.

[0150] <Characteristic Evaluation of Oxide Semiconductor Film> (SIMS Measurement of Carbon Concentration and Hydrogen Concentration) (A) Measurement of Carbon Concentration and Hydrogen Concentration in Oxide Semiconductor Film The oxide semiconductor films obtained in Examples and Comparative Examples were annealed at 450° C. in air for 1 hour, and SIMS depth profile analysis was performed by time-of-flight secondary ion mass spectrometry (ToF-SIMS) using a time-of-flight secondary ion mass spectrometer. The elements present in the depth direction were analyzed by detecting the intensity of secondary ions, and the carbon concentration and hydrogen concentration in the oxide semiconductor film were measured. C (mass number 12) and H (mass number 1) were detected as secondary ions. For the secondary ions C and H, standard samples were used. ２ O ３ The measurement conditions are as follows: (Measurement conditions) Measurement device: PHI ADEPT1010; manufactured by ULVAC-Phi Inc. Primary ion species: Cs+ Primary acceleration voltage: 2.0 kV Detection area: 126 x 126 (μm x μm)

[0151] (B) Depth Profile Using the time-of-flight secondary ion mass spectrometer described in the above section (A), SIMS depth profile analysis was performed on the oxide semiconductor film. As an example, the depth profiles of carbon (C) concentration, hydrogen (H) concentration, and indium concentration (detected as InO) in Example 6 are shown in FIG. 4. The left vertical axis of the graph in FIG. 4 (Concentration atoms / cm ３) indicates the carbon concentration (number of carbon atoms per unit volume) and the hydrogen concentration (number of hydrogen atoms per unit volume), the right vertical axis (Intensity counts / sec) indicates the secondary ion intensity of In ions (detected as InO), and the horizontal axis (Depth nm) indicates the depth from the surface side at the time of measurement.

[0152] In this measurement, the InO intensity was constant from 2 nm down from the surface. The interface between the oxide semiconductor film and the substrate was defined as the point beyond the depth where the InO intensity was half of the maximum InO intensity. The carbon and hydrogen concentrations were averaged from a depth of 2 nm down from the surface of the oxide semiconductor film to a depth beyond half the maximum InO intensity. (The measurement interval was 0.14 nm.) For samples with a thickness of 2 nm or less, FIB processing was performed from the backside, allowing measurements to be made without being affected by the surface or upper interface.

[0153] Note that SIMS measurements were performed on the example sample with the largest film thickness under the same film formation conditions (substrate temperature during film formation and oxidation conditions), and the carbon concentration and hydrogen concentration were calculated as described above. For the example sample with a small film thickness under the same film formation conditions, the SIMS data of the sample with the largest film thickness was used to calculate the average carbon concentration and hydrogen concentration at a thickness equivalent to the film thickness from the substrate interface as defined above.

[0154] (Measurement of Carrier Concentration by Hall Measurement) The carrier concentration of the oxide semiconductor film is measured by the following method. A glass substrate with an oxide thin film was cut into a 1 cm square and annealed in air at 450°C for 1 hour. Electrodes were formed at the four corners using In solder to form a Hall effect measurement element, and the carrier concentration was measured. The carrier concentration was determined by AC Hall effect measurement using a ResiTest 8400 model (manufactured by Toyo Corporation) at room temperature. The measurement conditions were as follows. For measurement accuracy, the value of the electron carrier concentration was adopted when the F value was 0.9 or more and the absolute value of the Hall voltage phase was 170° to 180°. Current value: 1×10 －１２ ~1 x 10 －３ A Magnetic field strength: 0.36T

[0155] (Measurement of Hall Mobility by Hall Measurement) Hall mobility was measured by the following method. A glass substrate with an oxide thin film was cut into 1 cm squares and annealed at 450°C for 1 hour. Electrodes were attached to the four corners using In solder to form a Hall effect measurement element. Annealing was performed in a nitrogen atmosphere at 200°C for 5 minutes, 250°C for 5 minutes, and 300°C for 5 minutes to generate oxygen vacancies and improve the carrier concentration, bringing it closer to the carrier concentration during transistor operation. Hall mobility was determined by AC Hall effect measurement using a ResiTest 8400 (manufactured by Toyo Corporation) at room temperature. Although there were multiple samples that varied depending on the annealing conditions, the Hall mobility of the sample showing the highest mobility was used. The measurement conditions were as follows. For measurement accuracy, the Hall mobility value was used when the F value was 0.9 or more and the absolute value of the Hall voltage phase was 170° to 180°. Current value: 1×10 －１２ ~1 x 10 －３ A Magnetic field strength: 0.36T

[0156] (Measurement of Film Thickness and Film Density by XRR) The film thickness and film density of the oxide semiconductor film were determined by X-ray reflectivity (hereinafter referred to as "XRR"). That is, simulation fitting was performed on the measured profile to determine the film thickness and film density. The fitting was performed under the assumption that the oxide semiconductor film was a single-layer film formed on a glass substrate. Furthermore, the accuracy of the XRR measurement results was confirmed for some samples by a cross-sectional TEM measurement method (described in the detailed description). The measurement conditions are shown below. Measurement equipment: SmartLab (manufactured by Rigaku) ​​X-ray source: CuKα ray (1.5418 Å), output 45 kV, 200 mA Incident optical system: parallel beam optical system Receiving side Soller slit: 5.0° Slit: Incident side IS = 1.0 mm Receiving side RS1 = 1.0 mm, RS2 = 1.0 mm Scanning conditions: Scan axis 2θ / θ Scanning speed 2° / min Step width 0.02°

[0157] (Measurement of Crystal Orientation by XRD) The substrate with the oxide thin film was subjected to X-ray diffraction measurement (hereinafter referred to as "XRD") to observe the crystal orientation. Specifically, an X-ray diffractometer ("SmartLab" model, manufactured by Rigaku Corporation) was used to irradiate a beam of CuKα rays (1.5418 Å) onto the oxide thin film, and the diffraction pattern was measured by 2θ / θ measurement in the 2θ range of 5 to 80°. The measurement conditions are shown below. Measurement equipment: SmartLab (manufactured by Rigaku) ​​X-ray source: CuKα ray (1.5418 Å), output 45 kV, 200 mA Incident optical system: parallel beam optical system Receiving side Soller slit: 5.0° Slit: Incident side IS = 1.0 mm Receiving side RS1 = 1.0 mm, RS2 = 1.0 mm Scanning conditions: Scan axis 2θ / θ Scanning speed: 2° / min Step width: 0.02°

[0158] For the oxide semiconductor film samples from which peaks were obtained, the peaks were attributed to the (222) and (400) peaks of the bixbyite structure of indium oxide. The peak areas of the (222) and (400) peaks in the obtained spectra were calculated. （２２２）／（４００） is shown in Table 1.

[0159] Orientation rate OR （２２２）／（４００） When the value of the {111} orientation is 1 or more, it is determined that the crystal structure is dominated by the {111} orientation. This can also be confirmed by using TEM-EBSD.

[0160] (Determination of bixbyite structure by electron diffraction in TEM) The crystalline state was determined by observing the electron diffraction pattern of a sample obtained by cross-sectional or planar TEM observation using a glass substrate with an oxide thin film. For ultrathin films that lacked strength in cross-sectional TEM, electron diffraction patterns were obtained by increasing the strength using planar TEM. Specifically, using an electron microscope (JEOL Ltd., "JEM-F200"), the oxide thin film area observed in a planar TEM image at a magnification of 1,000,000x was irradiated with an electron beam at an irradiation area of ​​approximately 100 nmφ and an acceleration voltage of 200 kV using a selected area aperture, and the diffraction pattern was measured. Ten fields of view were extracted at approximately equal intervals within a 10 μm range of the planar TEM image sample so that the observation points did not overlap. When the length in the channel length direction was short and the extraction range was limited to less than 10 μm, ten fields of view were extracted at approximately equal intervals so that the observation points did not overlap. The oxide thin film that did not show a clear diffraction spot in any of the ten extracted fields was judged to be "amorphous." On the other hand, the oxide thin film that showed a symmetric diffraction spot in any field was judged to be crystalline.

[0161] Furthermore, to identify the crystal structure, electron diffraction simulation software ReciPro (free software ver. 4.641 (2019 / 03 / 04)) was used to simulate the In ２ O ３A simulation of the electron diffraction pattern of the bixbyite structure was carried out. In the simulation, the crystal structure data of the bixbyite structure was 14388 from the Inorganic Crystal Structure Database (ICSD: Chemical Information Association), with a space group of Ia-3, a lattice constant of a = 10.17700 Å, and atomic coordinates of In site (0.250, 0.250, 0.250), In site (0.466, 0.000, 0.250), and O site (0.391, 0.156, 0.380). The measurement was performed by adjusting the beam shape of selected-area electron diffraction (SAED) so that a single spot was obtained, and the electron diffraction pattern of the oxide thin film was compared with the diffraction spot results for the obtained simulation pattern to determine whether or not the indium oxide had a bixbyite structure. For reference, Figure 5 shows examples of diffraction spots A to I obtained with an indium oxide bixbyite structure.

[0162] (Measurement of surface roughness by AFM) The surface of the glass substrate with the oxide thin film was measured using an AFM (atomic force microscope), and the arithmetic average roughness Ra was calculated over a 5 μm × 5 μm square field of view. Measuring device: E-SWEEP (manufactured by Hitachi High-Technologies) Probe: SI-DF40 Measurement mode: DFM Scanning speed: 2 s / line Resolution: 512 × 256 Note that when the surface cannot be obtained due to a protective film or the like, Ra can be calculated from cross-sectional TEM measurement.

[0163] The results in Table 1 show that the oxide semiconductor films of Examples 1 to 19, which were produced by ALD or sputtering and had carbon and hydrogen concentrations within the predetermined ranges, had low carrier concentrations, high hole mobility, and sufficient electrical properties, and were suitable for use in semiconductor devices.

[0164] <Production 1 of Bottom-Gate / Top-Contact Transistor> (Production 1 of Transistor A) Example A-1 A conductive n-type silicon substrate was used as the substrate, and a thermally oxidized film with a thickness of 60 nm was formed. The thermally oxidized film functions as a gate insulating film, and the conductive silicon portion functions as a gate electrode. First, the surface of the gate insulating film was treated with SPM liquid and UV / O ３ A cleaned surface was obtained by the treatment. An oxide semiconductor film was formed on the gate insulating film by the ALD method under the conditions described in Example 2 above. To improve adhesion between the oxide semiconductor layer and the positive photoresist, hexamethyldisilazane (HMDS) was applied to the surface of the oxide semiconductor layer. To pattern the oxide semiconductor layer, a positive photoresist was used, which was applied, prebaked (90°C, 1 minute 30 seconds), and exposed. Post-exposure baking was performed at 110°C for 1 minute 30 seconds. After development, the film was postbaked (110°C, 1 minute 30 seconds) and etched with a 500 mM oxalic acid aqueous solution to pattern the desired shape. When etching did not proceed or residues were generated using the oxalic acid aqueous solution, dilute hydrochloric acid heated to 50°C was used as an etchant. The photoresist was then stripped, and the oxide semiconductor film surface was cleaned by UV / O irradiation at 115°C for 10 minutes. ３ The patterned oxide semiconductor film was subjected to a heat treatment (annealing treatment) at 450° C. for 120 minutes in a hot air furnace.

[0165] After that, after forming a lift-off resist, tungsten (80 nm) and platinum (20 nm) were sequentially formed by RF sputtering, and then patterned into the desired shape as source / drain electrodes by the lift-off method. ３ The surface of the oxide semiconductor film was cleaned by this treatment. Then, a lift-off resist was formed to open contact holes, and a 200 nm thick aluminum oxide film was formed by RF sputtering. After lift-off, the film was used as a protective film. Finally, the film was annealed at 350° C. in a nitrogen atmosphere to obtain a transistor.

[0166] Examples A-2 to A-13 Transistors were obtained in the same manner as in Example A-1, except that oxide semiconductor films were formed by ALD under the conditions described in Examples 3, 5, 6, 9 to 13, and 15 to 18, respectively, instead of Example 2.

[0167] The transistors obtained in Examples A-1 to A-13 were evaluated for the following characteristics, and the results are shown in Table 2.

[0168] (Production of Transistor B 1) Example B-1 A transistor was obtained in the same manner as in Example A-1, except that a conductive silicon substrate with a thermally oxidized film having a thickness of 85 nm was used as the substrate.

[0169] Examples B-2 to B-13 Transistors were obtained in the same manner as in Example B-1, except that oxide semiconductor films were formed by an ALD method under the conditions described in Examples 3, 5, 6, 9 to 12, and 15 to 19, respectively, instead of Example 2.

[0170] The transistors obtained in Examples B-1 to B-13 were evaluated for the following characteristics, and the results are shown in Table 3.

[0171]

[0172]

[0173] <Transistor Characteristic Evaluation> The mobility, threshold voltage, S value, and reliability of the transistors fabricated in Examples A-1 to A13 and Examples B-1 to B-13 were evaluated. The results are shown in Tables 2 and 3. Specifically, the transistors obtained in the above examples were measured using a semiconductor device analyzer (Agilent Technologies' "B1500A") at room temperature in a light-shielded environment (in a shielded box). The drain voltage (Vd) was set to 0.1 V. For each Vd applied, the gate voltage (Vg) was varied from -20 V to 20 V or from -0.5 V / nm to 0.5 V / nm in 0.05 V or 0.002 V / nm steps to measure the current value Id, thereby obtaining Id-Vg characteristics. Here, the unit of applied voltage, V / nm, was defined as the applied voltage divided by the EOT (equivalent oxide thickness) of the gate insulating film. The EOT is calculated by dividing the high-dielectric-constant film thickness by the SiO ２EOT is the value converted into the electrical thickness equivalent to the film, and is calculated as follows: EOT = [film thickness of target insulating film] x [SiO ２ In other words, it is not the physical high dielectric constant film thickness, but the SiO ２ This is the equivalent film thickness when converted into film thickness. For example, hafnium oxide film has a relative dielectric constant of 20, so SiO ２ The equivalent film thickness is 5.1 times the thickness of the film (dielectric constant 3.9). Various parameters calculated from the Id-Vg characteristics are shown in Tables 2 and 3. The calculation method for each parameter is as follows:

[0174] (a) Maximum value of linear mobility (μlin Max) The maximum value of linear mobility when Vd = 0.1 V was determined by creating a graph of Id-Vg characteristics, calculating the transconductance (Gm) for each Vg, and deriving the linear mobility (μlin) using the equation for the linear region. Specifically, Gm was calculated by ∂(Id) / ∂(Vg). Furthermore, μlin was calculated using the following equation (c) for the linear region: μlin = (Gm L) / (W Ci Vd) ... (c) In equation (c), Ci is the capacitance of the gate insulating film, and is determined by the gate insulating film thickness, SiO ２ The relative dielectric constant of 3.9 and the dielectric constant of vacuum is 8.85 x 10 －１４ Ci [F / cm] calculated based on [F / cm] ２ ] was used. In formula (c), L is the channel length (L length), and W is the channel width (W length). Furthermore, from each Vg-μlin graph, the maximum value of μlin at Vg = -20 V to 20 V or -0.5 V / nm to 0.5 V / nm was calculated and designated as "μlin Max." In addition, in Tables 2 and 3, the mobility at a gate voltage where Vg-Vth = 18 V is designated as μlin at Vg-Vth = 18 V [cm ２ / Vs]. The threshold voltage Vth is defined as follows.

[0175] (b) S value and threshold voltage Vth The S value and threshold voltage (Vth) were evaluated from the graph of each Id-Vg characteristic. Specifically, the S value and threshold voltage (Vth) were evaluated from the graph of each Id-Vg characteristic. －７ ~5 x 10 －６In the [mA / mm] region, the value obtained by the following formula (d) was calculated as the S value. Furthermore, the current value Id = 1 nA or 5 × 10 －６ The value of Vg in [mA / mm] was calculated as the threshold voltage (Vth). Here, the unit of the current value Id is a value normalized by dividing the measured current value by the channel width W.

[0176]

[0177] (C) Reliability The reliability of the transistor was evaluated by stress testing. A positive bias stress test (PBS) and a negative bias stress test (NBS) were performed. For the PBS, Vg = +20 V was applied at 25°C, and the threshold voltage (Vth) after 10,000 seconds was compared with the threshold voltage before the test, and the difference was defined as ΔVth. For the NBS, Vg = -20 V was applied at 25°C, and the threshold voltage (Vth) after 10,000 seconds was compared with the threshold voltage before the test, and the difference was defined as ΔVth. The threshold voltage (Vth) was defined as the gate voltage value at which the current value Id = 1 nA. In Tables 2 and 3, the above data is described as "PBS shift ΔVth [V] Vg at Id = 1 nA" and "NBS shift ΔVth [V] Vg at Id = 1 nA," respectively.

[0178] The results in Tables 2 and 3 show that a transistor including, as a channel layer, an oxide semiconductor film having carbon concentrations and hydrogen concentrations in predetermined ranges is excellent in all of mobility, threshold voltage, and S value.

[0179] <Production of Oxide Semiconductor Film 2> Using triethylindium (TEI) as an indium precursor and trimethylgallium (TMG) as a gallium precursor, an oxide semiconductor film was produced on a glass substrate by an ALD method under the conditions and steps described in Examples 20 to 27 below, using an ALD apparatus (apparatus name: Fiji F200; manufactured by Veeco).

[0180] The obtained oxide semiconductor film was subjected to the following measurements: film thickness by X-ray reflectometry (XRR), carbon concentration and hydrogen concentration in the film by SIMS, hole mobility and carrier concentration by Hall measurement, confirmation of crystal orientation by X-ray diffraction (XRD), confirmation of the presence or absence of a bixbyite structure by planar TEM or cross-sectional TEM, and measurement of the surface roughness Ra of the thin film surface by atomic force microscope (AFM). The results are shown in Table 5.

[0181] Example 20 An oxide semiconductor film was produced under the following conditions and steps. (Conditions) Substrate temperature during film formation: 150°C Reactive gas (oxidizing agent): O ２ (Steps) Using triethylindium (TEI) as a precursor, steps (1) to (4) described below in the "Indium Film Formation Step" were repeated 22 times to obtain Film 1. Using trimethylgallium (TMG) as a precursor, steps (1) to (4) described below in the "Gallium Film Formation Step" were performed once on Film 1 to obtain Film 2. Using triethylindium (TEI) as a precursor, steps (1) to (4) described below in the "Indium Film Formation Step" were performed 22 times on Film 2 to obtain Film 3. Furthermore, a super cycle, in which each step related to the formation of Films 1 to 3 was defined as a subcycle and the operation of forming Films 1 to 3 in succession was defined as one cycle, was repeated a total of two times to obtain an oxide semiconductor film. The manufacturing conditions shown in Table 4 were used.

[0182] (Indium Film Formation Process) A series of steps consisting of the following (1) to (4) constitute one cycle, and were repeated a predetermined number of times. (1) The precursor vapor, vaporized under the condition of a source container heating temperature of 85°C, was introduced into the chamber by opening the valve for 0.06 seconds, and exposed to the substrate surface or film surface at a system pressure of 100 Pa to react and adsorb. (2) Unreacted source material was removed by argon purging for 15 seconds. (3) Oxygen (O ２(4) The gas was introduced into the chamber at a flow rate of 50 sccm by opening the valve, and the gas was allowed to stabilize for 10 seconds. Then, a plasma was generated for 20 seconds using an RF power supply with an output of 300 W. The RF power supply was turned off, and the valve was closed. (5) Unreacted raw materials were removed by purging with argon for 30 seconds.

[0183] (Gallium Film Formation Process) A series of steps consisting of the following (1) to (4) constitute one cycle, and were repeated a predetermined number of times. (1) The source container was set to room temperature of 25°C, and the vaporized precursor vapor was introduced into the chamber by opening the valve for 0.02 seconds, and exposed to the substrate surface or film surface at a system pressure of 100 Pa, causing reaction and adsorption. (2) Unreacted source material was removed by argon purging for 15 seconds. (3) Oxygen (O ２ (4) The gas was introduced into the chamber at a flow rate of 50 sccm by opening the valve, and the gas was allowed to stabilize for 10 seconds. Then, a plasma was generated for 20 seconds using an RF power supply with an output of 300 W. The RF power supply was turned off, and the valve was closed. (5) Unreacted raw materials were removed by purging with argon for 30 seconds.

[0184] Similarly, in Examples 21 to 25, oxide semiconductor films (oxide semiconductor layers) were manufactured using the number of film formations, the number of super cycles, and precursors shown in Table 4.

[0185] Example 26 An oxide semiconductor film was manufactured under the following conditions and steps. (Conditions) Substrate temperature during film formation: 150° C. Reactive gas (oxidizing agent): H ２In the oxide semiconductor film formation method of Example 26, triethylindium (TEI) was used as a precursor, and steps (1) to (4) described below in the "Indium Film Formation Step" were repeated 19 times to obtain Film 1. Trimethylgallium (TMG) was used as a precursor, and steps (1) to (4) described below in the "Gallium Film Formation Step" were performed once on Film 1 to obtain Film 2. Triethylindium (TEI) was used as a precursor, and steps (1) to (4) described below in the "Indium Film Formation Step" were performed 19 times on Film 2 to obtain Film 3. Furthermore, a super cycle, in which each step related to the formation of Films 1 to 3 was defined as a subcycle and the operation of forming Films 1 to 3 in succession was defined as one cycle, was repeated a total of two times to obtain an oxide semiconductor film. The conditions shown in Table 4 were used as the production conditions.

[0186] (Indium Film Formation Process) A series of steps consisting of the following (1) to (4) was considered as one cycle, and was repeated a predetermined number of times. (1) The precursor vapor, vaporized under the condition of a source container heating temperature of 85°C, was introduced into the chamber by opening the valve for 0.06 seconds, and exposed to the substrate surface or film surface at a system pressure of 100 Pa, causing reaction and adsorption. (2) Unreacted source material was removed by argon purging for 15 seconds. (3) The precursor was heated at room temperature of 25°C with H ２ Argon was bubbled through a cylinder containing O, and the resulting water vapor was introduced into the chamber at a flow rate of 10 sccm by opening the valve. The chamber was then allowed to stabilize for 10 seconds. Plasma was then generated for 20 seconds using an RF power supply with an output of 300 W. The RF power supply was then turned off, and the valve was closed. (4) Unreacted raw materials were removed by purging with argon for 30 seconds.

[0187] (Gallium Film Formation Process) A series of steps consisting of the following (1) to (4) was considered as one cycle, and was repeated a predetermined number of times. (1) The source container was set to room temperature of 25°C, and the vaporized precursor vapor was introduced into the chamber by opening the valve for 0.02 seconds, and exposed to the substrate surface or film surface at a system pressure of 100 Pa, causing reaction and adsorption. (2) Unreacted source material was removed by argon purging for 15 seconds. (3) H ２Argon was bubbled through a cylinder containing O, and the resulting water vapor was introduced into the chamber at a flow rate of 10 sccm by opening the valve. The chamber was then allowed to stabilize for 10 seconds. Plasma was then generated for 20 seconds using an RF power supply with an output of 300 W. The RF power supply was then turned off, and the valve was closed. (4) Unreacted raw materials were removed by purging with argon for 30 seconds.

[0188] Similarly, in Example 27, an oxide semiconductor film (oxide semiconductor layer) was manufactured using the number of film formations, the number of super cycles, and precursors shown in Table 4.

[0189]

[0190]

[0191] The results in Table 5 show that the oxide semiconductor films of Examples 20 to 27, which were produced using ALD and had carbon and hydrogen concentrations within the specified ranges, had low carrier concentrations, high hole mobility, and sufficient electrical properties, and can be suitably used in semiconductor devices.

[0192] <Production of Bottom-Gate / Top-Contact Transistor 2> (Production of Transistor B 2) Examples B-14 to B-17 Transistors were obtained in the same manner as in Example A-1, except that a conductive silicon substrate with a thermally oxidized film having a thickness of 85 nm was used as the substrate, and an oxide semiconductor film was formed by the ALD method under the conditions described in Examples 20, 22, 24, and 26, respectively, instead of Example 2.

[0193] The transistors obtained in Examples B-14 to B-17 were evaluated for the above characteristics, and the results are shown in Table 6.

[0194]

[0195] The results in Table 6 show that a transistor including, as a channel layer, an oxide semiconductor film having carbon concentrations and hydrogen concentrations in predetermined ranges is excellent in all of mobility, threshold voltage, and S value.

[0196] <Production of Oxide Semiconductor Film 3> Using ethylcyclopentadienyl indium(I) (InEtCp) as an indium precursor and an ALD apparatus (apparatus name: Fiji F200; manufactured by Veeco Electronics), oxide semiconductor films were produced on glass substrates by an ALD method under the conditions and steps described in Examples 28 to 32 below.

[0197] The obtained oxide semiconductor film was subjected to the following measurements: film thickness by X-ray reflectometry (XRR), carbon concentration and hydrogen concentration in the film by SIMS, hole mobility and carrier concentration by Hall measurement, confirmation of crystal orientation by X-ray diffraction (XRD), confirmation of the presence or absence of a bixbyite structure by planar TEM or cross-sectional TEM, and measurement of the surface roughness Ra of the thin film surface by atomic force microscope (AFM). The results are shown in Table 7.

[0198] Example 28 An oxide semiconductor film was produced under the following conditions and steps. (Conditions) Substrate temperature during film formation: 150°C Reactive gas (oxidizing agent): O ２ (Steps) A series of steps (1) to (4) below constitute one cycle, and 50 cycles were repeated. (1) Ethylcyclopentadienyl indium (I) vapor, vaporized under conditions of a source container heating temperature of 85°C, was introduced into the chamber by opening the valve for 0.04 seconds and exposed to the substrate surface or film surface for 15 seconds at a system pressure of 100 Pa to allow reaction and adsorption. (2) Unreacted source material was removed by argon purging for 15 seconds. (3) The valve of the oxygen cylinder was opened to introduce oxygen into the chamber at a flow rate of 50 sccm, and the chamber was allowed to stabilize for 10 seconds. Thereafter, plasma was generated for 60 seconds using an RF power supply with an output of 300 W. The RF power supply was turned off and the valve was closed. (4) Unreacted source material was removed by argon purging for 45 seconds.

[0199] Example 29 An oxide semiconductor film was produced in the same manner as in Example 28, except that the number of cycles during film formation was 150.

[0200] Example 30 An oxide semiconductor film was produced in the same manner as in Example 28, except that the substrate temperature during film formation was set to 250° C. and the number of cycles was set to 102.

[0201] Example 31 An oxide semiconductor film was produced under the following conditions and steps. (Conditions) Substrate temperature during film formation: 150° C. Reactive gas (oxidizing agent): H ２ O (Steps) A series of steps consisting of the following (1) to (4) constitute one cycle, and 38 cycles were repeated. (1) Ethylcyclopentadienyl indium (I) vapor, vaporized under the condition of a source container heating temperature of 85°C, was introduced into the chamber by opening the valve for 0.04 seconds, and exposed to the substrate surface or film surface for 15 seconds at a system pressure of 100 Pa to cause reaction and adsorption. (2) Unreacted source material was removed by argon purging for 15 seconds. (3) H ２ Argon was bubbled through a cylinder containing O, and the resulting water vapor was introduced into the chamber at a flow rate of 30 sccm by opening the valve. The chamber was then allowed to stabilize for 10 seconds. Plasma was then generated for 60 seconds using an RF power supply with an output of 300 W. The RF power supply was then turned off, and the valve was closed. (4) Unreacted raw materials were removed by purging with argon for 45 seconds.

[0202] Example 32 An oxide semiconductor film was produced in the same manner as in Example 31, except that the number of cycles was set to 114.

[0203]

[0204] The results in Table 7 show that the oxide semiconductor films of Examples 28 to 32, which were produced using ALD and had carbon and hydrogen concentrations within the specified ranges, had low carrier concentrations, high hole mobility, and sufficient electrical properties, and can be suitably used in semiconductor devices.

[0205] <Production of Bottom-Gate / Top-Contact Transistor 3> (Production of Transistor B 3) Examples B-18 and B-19 Transistors were obtained in the same manner as in Example A-1, except that a conductive silicon substrate with a thermally oxidized film having a thickness of 85 nm was used as the substrate, and an oxide semiconductor film was formed by the ALD method under the conditions described in Examples 28 and 31, respectively, instead of Example 2.

[0206] The transistors obtained in Examples B-18 and B-19 were evaluated for the above characteristics, and the results are shown in Table 8.

[0207]

[0208] The results in Table 8 show that a transistor including, as a channel layer, an oxide semiconductor film having carbon concentrations and hydrogen concentrations in predetermined ranges is excellent in all of mobility, threshold voltage, and S value.

[0209] <Production of Oxide Semiconductor Film 4> Using triethylindium (TEI) as an indium precursor and triethylgallium (TEG) as a gallium precursor, an oxide semiconductor film was produced on a glass substrate by an ALD method under the conditions and steps described in Examples 34 to 41 below, using an ALD apparatus (apparatus name: Fiji F200; manufactured by Veeco Electronics).

[0210] The obtained oxide semiconductor film was subjected to the following measurements: film thickness by X-ray reflectometry (XRR), carbon concentration and hydrogen concentration in the film by SIMS, hole mobility and carrier concentration by Hall measurement, confirmation of crystal orientation by X-ray diffraction (XRD), confirmation of the presence or absence of a bixbyite structure by planar TEM or cross-sectional TEM, and measurement of the surface roughness Ra of the thin film surface by atomic force microscope (AFM). The results are shown in Table 10.

[0211] Example 33 An oxide semiconductor film was produced under the following conditions and steps. (Conditions) Substrate temperature during film formation: 150°C Reactive gas (oxidizing agent): O ２ (Steps) Using triethylindium (TEI) as a precursor, steps (1) to (4) described below in the "Indium Film Formation Step" were repeated 22 times to obtain Film 1. Using triethylgallium (TEG) as a precursor, steps (1) to (4) described below in the "Gallium Film Formation Step" were performed once on Film 1 to obtain Film 2. Using triethylindium (TEI) as a precursor, steps (1) to (4) described below in the "Indium Film Formation Step" were performed 22 times on Film 2 to obtain Film 3. Furthermore, a super cycle, in which each step related to the formation of Films 1 to 3 was defined as a subcycle and the operation of forming Films 1 to 3 in succession was defined as one cycle, was repeated a total of two times to obtain an oxide semiconductor film. The manufacturing conditions shown in Table 9 were used.

[0212] (Indium Film Formation Process) A series of steps consisting of the following (1) to (4) constitute one cycle, and were repeated a predetermined number of times. (1) The precursor vapor, vaporized under the condition of a source container heating temperature of 85°C, was introduced into the chamber by opening the valve for 0.06 seconds, and exposed to the substrate surface or film surface at a system pressure of 100 Pa to react and adsorb. (2) Unreacted source material was removed by argon purging for 15 seconds. (3) Oxygen (O ２ (4) The gas was introduced into the chamber at a flow rate of 50 sccm by opening the valve and allowed to stabilize for 10 seconds. Then, a plasma was generated for 20 seconds using an RF power supply with an output of 300 W. The RF power supply was turned off and the valve was closed. (5) Unreacted raw materials were removed by purging with argon for 30 seconds.

[0213] (Gallium Film Formation Process) A series of steps consisting of the following (1) to (4) constitute one cycle, and were repeated a predetermined number of times. (1) The source container was set to room temperature of 25°C, and the vaporized precursor vapor was introduced into the chamber by opening the valve for 0.06 seconds, and exposed to the substrate surface or film surface at a system pressure of 100 Pa, causing reaction and adsorption. (2) Unreacted source material was removed by argon purging for 15 seconds. (3) Oxygen (O ２ (4) The gas was introduced into the chamber at a flow rate of 50 sccm by opening the valve, and the gas was allowed to stabilize for 10 seconds. Then, a plasma was generated for 20 seconds using an RF power supply with an output of 300 W. The RF power supply was turned off, and the valve was closed. (5) Unreacted raw materials were removed by purging with argon for 30 seconds.

[0214] Similarly, in Examples 34 to 40, oxide semiconductor films (oxide semiconductor layers) were manufactured using the number of film formations, the number of super cycles, and precursors shown in Table 9.

[0215]

[0216]

[0217] The results in Table 10 show that the oxide semiconductor films of Examples 33 to 40, which were produced using ALD for film formation and had carbon and hydrogen concentrations within the specified ranges, had low carrier concentrations, high hole mobility, and sufficient electrical properties, and can be suitably used in semiconductor devices.

[0218] <Production of Oxide Semiconductor Film 5> An oxide semiconductor film was produced on a glass substrate by an ALD method using triethylindium (TEI) as an indium precursor and an ALD apparatus (apparatus name: Fiji F200; manufactured by Veeco Electronics) under the conditions and steps described in Example 41 below.

[0219] The obtained oxide semiconductor film was subjected to the following measurements: film thickness measurement by X-ray reflectometry (XRR), carbon concentration and hydrogen concentration measurement in the film by SIMS measurement, hole mobility measurement and carrier concentration measurement by Hall measurement, confirmation of crystal orientation by X-ray diffraction (XRD), confirmation of the presence or absence of a bixbyite structure by planar TEM or cross-sectional TEM, and measurement of the surface roughness Ra of the thin film surface by atomic force microscope (AFM). The results are shown in Table 11.

[0220] Example 41 An oxide semiconductor film was produced under the following conditions and steps. (Conditions) Substrate temperature during film formation: 150° C. Reactive gas (oxidizing agent): H ２ O (Steps) A series of steps consisting of the following (1) to (4) were repeated. (1) Triethylindium vapor, vaporized under the condition of a source container heating temperature of 95°C, was introduced into the chamber by opening the valve for 0.06 seconds, and exposed to the substrate surface or film surface for 15 seconds at a system pressure of 100 Pa to allow reaction and adsorption. (2) Unreacted source material was removed by argon purging for 15 seconds. (3) H ２ Argon is bubbled through a cylinder containing O, and the resulting water vapor is introduced into the chamber at a flow rate of 10 sccm by opening the valve. Wait 10 seconds for stabilization. Then, a plasma is generated for 20 seconds using an RF power supply with an output of 300 W. The RF power supply is turned off, and the valve is closed. (4) Unreacted raw materials are removed by purging with argon for 45 seconds.

[0221]

[0222] The results in Table 11 show that the oxide semiconductor film of Example 41, which was produced using ALD for film formation and had carbon and hydrogen concentrations within the predetermined ranges, had a low carrier concentration, high hole mobility, and sufficient electrical properties, and can be suitably used in semiconductor devices.

[0223] The oxide semiconductor film of the present invention is suitable as a channel layer of a transistor and can be used in various semiconductor devices, particularly in display transistors, memory FETs (DRAM, NAND, ReRAM, FeRAM), logic IC FETs (CPU, MPU, BEOL, 3D-LSI, CMOS), sensor FETs (CMOS image sensors), and transistors (MOSFETs, power transistors, MESFETs).

[0224] Although several embodiments and / or examples of the present invention have been described in detail above, those skilled in the art will readily be able to make numerous modifications to these exemplary embodiments and / or examples without substantially departing from the novel teachings and advantages of the present invention. Accordingly, these numerous modifications are within the scope of the present invention. The contents of all documents cited in this specification and of the applications from which this application claims priority under the Paris Convention are incorporated by reference in their entirety.

Claims

1. Carbon concentration was 1 x 10 measured by secondary ion mass spectrometry (SIMS). １８ atoms / cm ３ That's it, 5 x 10 ２２ atoms / cm ３ and hydrogen concentration is 1×10 １８ atoms / cm ３ That's it, 5 x 10 ２２ atoms / cm ３ An oxide semiconductor film having the following regions:

2. The oxide semiconductor film according to claim 1, which contains indium oxide as a main component.

3. The oxide semiconductor film according to claim 2, wherein the atomic ratio of In to all metal elements contained in the oxide semiconductor film ([In] / ([In]+[all metal elements other than In])×100) is 62 at % or more.

4. The oxide semiconductor film according to claim 2 or 3, further containing Ga.

5. The oxide semiconductor film according to claim 4, wherein the atomic ratio of Ga to all metal elements contained in the oxide semiconductor film ([Ga] / ([Ga]+[all metal elements other than Ga])×100) is 30 at % or less.

6. The oxide semiconductor film according to any one of claims 2 to 5, further comprising one or more additive elements selected from B, Al, Si, Sc, Zn, Ce, Y, Zr, Sn, Sm, Hf, Ta, and Yb.

7. The oxide semiconductor film according to claim 6, wherein the atomic ratio of the total amount of the additive elements to all metal elements contained in the oxide semiconductor film ([total amount of additive elements] / ([total amount of additive elements]+[total metal elements other than additive elements])×100) is 10 at % or less.

8. The oxide semiconductor film according to any one of claims 2 to 7, wherein at least one of an X-ray diffraction pattern obtained by X-ray diffraction and an electron beam diffraction spot obtained by electron beam diffraction shows a bixbyite structure.

9. The oxide semiconductor film according to any one of claims 2 to 8, which has a bixbyite structure and has a crystal plane oriented in {111} with respect to a surface of the underlayer in contact with the oxide semiconductor film.

10. The oxide semiconductor film according to any one of claims 2 to 7, which has an amorphous structure in which no X-ray diffraction pattern is observed in an X-ray diffraction method and no electron beam diffraction spots are observed in an electron beam diffraction method.

11. The oxide semiconductor film according to any one of claims 1 to 10, having a film thickness of less than 20 nm.

12. Film density is 6.50 g / cm ３ The oxide semiconductor film according to any one of claims 1 to 11.

13. The oxide semiconductor film according to any one of claims 1 to 12, having a surface roughness Ra of 0.6 nm or less.

14. The carrier concentration at room temperature is 5 x 10 １９ cm －３ The oxide semiconductor film according to any one of claims 1 to 13, wherein:

15. The hole mobility is 40 cm ２ The oxide semiconductor film according to claim 1 , wherein the Vref is 0.1 V.

16. The oxide semiconductor film according to any one of claims 1 to 15, which is formed by atomic layer deposition (ALD).

17. Secondary ion mass spectrometry (SIMS) measurements reveal that the carbon concentration is 1 x 10 １８ atoms / cm ３ That's it, 5 x 10 ２２ atoms / cm ３ and hydrogen concentration is 1×10 １８ atoms / cm ３ That's it, 5 x 10 ２２ atoms / cm ３ an atomic ratio of In to all metal elements contained in the oxide semiconductor film ([In] / ([In]+[all metal elements other than In])×100) is 80 at % or more; and at least one of an X-ray diffraction pattern obtained by X-ray diffraction and an electron beam diffraction spot obtained by electron beam diffraction exhibits a bixbyite structure.

18. The oxide semiconductor film according to claim 17, further containing Ga.

19. A transistor comprising a layer made of the oxide semiconductor film according to any one of claims 1 to 18, an insulating film layer, and an electrode on a substrate.

20. The transistor of claim 19, which is a bottom-gate, top-contact type.

21. The transistor of claim 19, which is a top-gate, top-contact type.

22. The transistor according to any one of claims 19 to 21, wherein the insulating film layer is primarily composed of hafnium oxide.

23. The transistor according to any one of claims 19 to 21, wherein the insulating film layer is primarily made of silicon oxide.

24. The transistor according to any one of claims 19 to 21, wherein the insulating film layer is primarily composed of aluminum oxide.

25. The transistor according to any one of claims 19 to 24, wherein the electrode is primarily composed of titanium nitride.

26. The transistor of any one of claims 19 to 24, wherein the electrode is primarily made of tungsten.

27. A semiconductor device comprising a transistor according to any one of claims 19 to 26.

28. An electronic circuit comprising the semiconductor device of claim 27.

29. An electrical device, electronic device, vehicle, or power plant comprising the electronic circuit of claim 28.

30. A method for producing the oxide semiconductor film according to any one of claims 1 to 18, comprising the step of depositing the film by atomic layer deposition (ALD) using an indium-containing precursor.

31. The method of claim 30, wherein triethylindium is used as the indium-containing precursor.

32. The method of claim 30 or 31, wherein a gallium-containing precursor is used in addition to the indium-containing precursor.

33. In the film formation process, H is used as an oxidizing agent. ２ The method according to any one of claims 30 to 32, wherein O plasma is used.

34. In the film formation process, O is used as an oxidizing agent. ２ The method according to any one of claims 30 to 32, wherein plasma is used.

35. In the film forming process, O is used as an oxidizing agent. ３ The method according to any one of claims 30 to 32, wherein 36. The method according to any one of claims 30 to 35, wherein the oxide semiconductor film is an indium oxide film.

37. The method of any one of claims 30 to 36, wherein the vessel containing the indium-containing precursor is heated to a temperature in the range of 75 to 125°C.

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