JP6409324B2 - Oxide sintered body and manufacturing method of semiconductor device - Google Patents

Description

  The present invention relates to an oxide sintered body that can be used as a target when an oxide semiconductor film is formed by sputtering, and a semiconductor device including the oxide semiconductor film.

  Conventionally, in a liquid crystal display device, a thin film electroluminescence (EL) display device, an organic EL display device and the like, an amorphous silicon semiconductor has been used for a channel layer of a thin film transistor (TFT).

  However, in recent years, as a material replacing amorphous silicon, a composite oxide containing indium (In), gallium (Ga), and zinc (Zn), that is, an In—Ga—Zn-based composite oxide (“IGZO (registered trademark)”). ) ") Is also attracting attention. This is because an IGZO-based oxide semiconductor can be expected to have higher carrier mobility than amorphous silicon.

  Currently, such IGZO-based oxide semiconductor films are formed by sputtering using an oxide sintered body as a target (for example, Japanese Patent Application Laid-Open No. 2008-199005 (Patent Document 1), Japanese Patent No. 5189698 (Patent Document). 2)).

JP 2008-199005 A Patent No. 5189698

  In sputtering using the target disclosed in Patent Document 1, an oxide semiconductor film is formed as follows. That is, a voltage is applied to the target disposed in the vacuum chamber of the sputtering apparatus, and the surface of the target is sputtered by rare gas ions. Thereby, the constituent atoms of the target jump out into the vacuum chamber, and the jumped out atoms are deposited on the substrate arranged to face the target to form an oxide semiconductor film. In general, an oxide sintered body obtained by molding and sintering an oxide powder as a raw material is used for such a target.

  At present, further improvements in electron mobility are required for TFTs using oxide semiconductor films. In response to such a request, Patent Document 2 attempts to use tin (Sn). According to Patent Document 2, it is said that the combination of In, Sn, and Zn can improve TFT characteristics (mobility, off-current, threshold voltage) and reliability (threshold voltage shift, moisture resistance). It is known that Sn is an element responsible for electron conduction. Therefore, if the Sn content in the oxide semiconductor film can be increased, improvement in electron mobility is expected.

Here, in order to contain Sn in the oxide semiconductor film, it is necessary to contain Sn in the oxide sintered body as a target. However, when the Sn content in the oxide sintered body is increased, a SnO ₂ crystal phase may be generated inside the oxide sintered body. When the SnO ₂ crystal phase is contained inside the oxide sintered body (target), a suboxide called nodules (for example, SnO) is deposited on the surface of the target during sputtering, and this becomes a starting point of abnormal discharge. Sputtering discharge cannot be maintained stably.

  As a method for suppressing such abnormal discharge, for example, it is conceivable to increase the oxygen partial pressure in a mixed gas of oxygen gas and sputtering gas (generally Ar gas) introduced during film formation. However, in this method, since the film formation rate decreases as the oxygen partial pressure increases, the film formation time increases, resulting in a decrease in production efficiency and an increase in TFT manufacturing cost.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an oxide sintered body (target) containing Sn and capable of sustaining stable sputtering discharge. There is.

The oxide sintered body according to the embodiment of the present invention contains In, Ga, Zn, and Sn, and includes at least one of the In ₆ Ga ₂ Sn ₂ O ₁₆ crystal phase and the In ₂ Ga ₂ ZnO ₇ crystal phase. Including.

  According to the oxide sintered body, sputtering discharge can be maintained.

It is a flowchart which shows the outline of the manufacturing method of the oxide sintered compact concerning one Embodiment of this invention. It is a flowchart which shows the outline of the manufacturing method of the semiconductor device concerning one Embodiment of this invention. It is a typical top view showing an example of the composition of the semiconductor device concerning one embodiment of the present invention. FIG. 4 is a schematic cross-sectional view taken along line IV-IV in FIG. 3.

[Description of Embodiment of the Present Invention]
First, an outline of an embodiment of the present invention (hereinafter also referred to as “this embodiment”) will be described in the following [1] to [15].

[1] The oxide sintered body of the present embodiment contains In, Ga, Zn, and Sn, and includes at least one of the In ₆ Ga ₂ Sn ₂ O ₁₆ crystal phase and the In ₂ Ga ₂ ZnO ₇ crystal phase. Including.

According to the inventor's research, the oxide sintered body containing at least one of the In ₆ Ga ₂ Sn ₂ O ₁₆ crystal phase and the In ₂ Ga ₂ ZnO ₇ crystal phase has no nodule generation during sputtering. Few. Therefore, sputtering discharge can be stably maintained by using this oxide sintered body as a target. Here, the presence of the In ₆ Ga ₂ Sn ₂ O ₁₆ crystal phase or the In ₂ Ga ₂ ZnO ₇ crystal phase in the oxide sintered body is determined by, for example, powder X-ray diffraction (XRD), transmission electron microscope ( This can be confirmed by transmission electron diffraction (TED) using transmission electron microscope (TEM).

[2] It is preferable that the oxide sintered body further includes an InGaZnO ₄ crystal phase in which Sn is dissolved.

According to the study of the present inventor, the InGaZnO ₄ crystal phase in which Sn is dissolved is a crystal phase in which nodules are generated at the time of sputtering despite containing Sn. Therefore, when the oxide sintered body (target) includes an InGaZnO ₄ crystal phase in which Sn is dissolved, abnormal discharge during sputtering can be suppressed. At the same time, Sn can be contained in the oxide semiconductor film formed by sputtering, so that field-effect mobility in the oxide semiconductor film can be increased.

[3] It is preferable that the oxide sintered body further includes a ZnGa ₂ O ₄ crystal phase in which Sn is dissolved.

This is because the ZnGa ₂ O ₄ crystal phase in which Sn is dissolved is also a crystal phase in which nodules are generated very little during sputtering despite containing Sn.

[4] The oxide sintered body preferably further includes a Zn ₂ SnO ₄ crystal phase in which Ga is dissolved.

This is because the Zn ₂ SnO ₄ crystal phase in which Ga is a solid solution is also a crystal phase in which nodule generation is very small during sputtering despite containing Sn.

  [5] The oxide sintered body has, in the diffraction pattern by the powder X-ray diffraction method, a peak having a diffraction angle 2θ in the range of 30.90 ° or more and 30.90 ° or less as a peak, and the diffraction angle 2θ is When one peak in the range of 38.00 ° to 38.15 ° is b peak, the diffraction intensity ratio Ib / Ia of b peak to a peak is 0.02 or more and 0.1 or less. Is preferred.

Here, the “a peak” is a peak derived from the InGaZnO ₄ crystal phase, and the “b peak” is a peak derived from the In ₂ Ga ₂ ZnO ₇ crystal phase. According to the study of the present inventor, when Ib / Ia, which is the diffraction intensity ratio of the b peak to the a peak, is 0.02 or more and 0.1 or less, the oxygen partial pressure that can stably maintain the sputtering discharge. The range of is expanded. This reduces the restrictions on the film formation conditions and improves productivity.

[6] The elemental composition of the oxide sintered body is the following formula (1) to the following formula (5):
0.4 <In / (In + Ga + Zn) ≦ 0.65 (1)
0.3 <In / (In + Ga + Zn + Sn) ≦ 0.50 (2)
0.20 ≦ Sn / (Sn + Zn) <0.33 (3)
0.05 <Sn / (In + Ga + Sn + Zn) <0.2 (4)
0.41 ≦ In / (In + Zn + Sn) ≦ 0.6 (5)
It is preferable to satisfy all of the above.

  According to the inventor's research, when the oxide sintered body (target) satisfies the above formula (1), the field effect mobility in the oxide semiconductor film (channel layer) obtained by sputtering can be increased, Furthermore, the Von value of a semiconductor device (eg, TFT) including an oxide semiconductor film can be a positive value. That is, the semiconductor device can be normally off.

  When the oxide sintered body satisfies the above formula (2), the field-effect mobility in the oxide semiconductor film obtained by sputtering can be increased, and further the OFF current of the semiconductor device including the oxide semiconductor film can be reduced. be able to. That is, the ON characteristic and the OFF characteristic of the semiconductor device can be compatible.

  When the oxide sintered body satisfies the above formula (3), the range of the oxygen partial pressure capable of maintaining a stable sputtering discharge is expanded, and thus productivity is improved.

  When the oxide sintered body satisfies the above formula (4), the field effect mobility in the oxide semiconductor film obtained by sputtering can be increased, and the Von value of the semiconductor device including the oxide semiconductor film can be positive. Can be a value.

  When the oxide sintered body satisfies the above formula (5), the field-effect mobility in the oxide semiconductor film obtained by sputtering can be increased, and further the OFF current of the semiconductor device including the oxide semiconductor film can be reduced. be able to.

  And by satisfy | filling all the said Formula (1)-said Formula (5), these act | operate synergistically and the characteristic of a semiconductor device will improve notably.

  [7] The oxide sintered body is preferably such that no peak is observed within a diffraction angle 2θ of 30.55 ° or more and 30.80 ° or less in a diffraction pattern by a powder X-ray diffraction method.

The presence of a peak at the diffraction angle in this range means that an In ₂ O ₃ crystal phase having a bixbite type crystal structure exists in the oxide sintered body. The In ₂ O ₃ crystal phase is a crystal phase that can cause abnormal discharge, although it does not affect as much as the SnO ₂ crystal phase. Further, when the target contains an In ₂ O ₃ crystal phase, the OFF current of the semiconductor device tends to increase.

[8] Therefore, it is desirable that the oxide sintered body does not include an In ₂ O ₃ crystal phase having a bixbite type crystal structure.

  [9] The oxide sintered body is preferably such that no peak is observed within a diffraction angle 2θ of 34.30 ° or more and 34.50 ° or less in a diffraction pattern by a powder X-ray diffraction method.

The presence of a peak at the diffraction angle in this range means that an SnO ₂ crystal phase having a rutile crystal structure is present in the oxide sintered body. As described above, the oxide sintered body of the present embodiment does not contain Sn in a form that can be a SnO ₂ crystal phase. When the SnO ₂ crystal phase having a rutile crystal structure is present in the oxide sintered body, abnormal discharge occurs during sputtering, and the sputtering discharge cannot be stably maintained. In addition, the OFF current of the semiconductor device tends to increase.

[10] Accordingly, it is desirable that the oxide sintered body does not include a SnO ₂ crystal phase having a rutile crystal structure.

[11] It is preferable that the oxide sintered body does not include an In ₂ O ₃ (ZnO) _m (wherein m is a natural number) crystal phase.

  By not including these crystal phases, the electrical resistance of the oxide sintered body can be reduced. Therefore, an oxide sintered body that does not include these crystal phases is particularly suitable as a target for direct current (DC) sputtering. Further, since the target does not include these crystal phases, the OFF current of the semiconductor device can be reduced.

  [12] The oxide sintered body is made of Ti (titanium), W (tungsten), Hf (hafnium), Zr (zirconium) or Si (silicon) at 1 at. % Or more and 10 at. It is preferable to contain in% or less range.

  When the target contains these elements, the field-effect mobility in the oxide semiconductor film to be formed can be increased, and further, the OFF current of the semiconductor device including the oxide semiconductor film can be reduced. The unit of content “at.%” Indicates “atomic percent”, that is, the atomic number concentration.

  [13] Another aspect of the present embodiment is a semiconductor device, which is formed by sputtering using the oxide sintered body described in any one of [1] to [12] as a target. The oxide semiconductor film is a channel layer.

  This semiconductor device is, for example, a TFT. This semiconductor device is provided with an IGZO-based oxide semiconductor film as a channel layer, and the semiconductor film contains Sn. Therefore, the field effect mobility of the semiconductor film is high. Furthermore, since the oxide sintered body described above is used as a target for manufacturing this semiconductor device, it can be manufactured at low cost.

  [14] Still another aspect of the present embodiment is a method for manufacturing a semiconductor device, which includes preparing the oxide sintered body described in any one of [1] to [12] above. And a step of forming an oxide semiconductor film by sputtering using the oxide sintered body as a target.

  The oxide sintered body of the present embodiment can sustain the sputtering discharge without increasing the oxygen partial pressure (that is, without decreasing the film forming rate). Therefore, a semiconductor device can be manufactured at low cost.

[15] Still another aspect of the present embodiment is a method for manufacturing an oxide sintered body, which includes gallium oxide (Ga ₂ O ₃ ) powder, zinc oxide (ZnO) powder, and tin oxide (SnO _2). ) Mixing the powder to obtain a first mixture, heat-treating the first mixture, heat-treating the first mixture and indium oxide (In ₂ O ₃ ) powder to form a second mixture A step of obtaining the molded body by pressure-molding the second mixture, and a step of heat-treating the molded body.

The oxide sintered body produced through the above steps contains In, Ga, Zn, and Sn, and is at least one of the In ₆ Ga ₂ Sn ₂ O ₁₆ crystal phase and the In ₂ Ga ₂ ZnO ₇ crystal phase. Can be included.

[Details of the embodiment of the present invention]
Hereinafter, although this embodiment is described in more detail, this embodiment is not limited to these.

<First Embodiment: Oxide Sintered Body>
The first embodiment is an oxide sintered body. The oxide sintered body of the embodiment is an oxide containing at least In, Ga, Zn, and Sn. As long as the oxide sintered body contains these elements, it can also contain other elements. Examples of other elements include additive elements described later. The oxide sintered body can be mainly used as a sputtering target. An oxide semiconductor film formed using the oxide sintered body of the embodiment is suitable as a channel layer of a semiconductor device (for example, TFT).

(In ₆ Ga ₂ Sn ₂ O ₁₆ crystal phase and In ₂ Ga ₂ ZnO ₇ crystal phase)
The oxide sintered body of the embodiment is different from a conventional sputtering target in that it includes at least one of an In ₆ Ga ₂ Sn ₂ O ₁₆ crystal phase and an In ₂ Ga ₂ ZnO ₇ crystal phase. And by including these crystal phases, generation | occurrence | production of a nodule can be suppressed at the time of sputtering.

Here, the “crystalline phase” in the present specification does not necessarily indicate a phase composed of only a crystalline substance, and may be a phase containing an amorphous part thereof. Further, for example, “In ₆ Ga ₂ Sn ₂ O ₁₆ crystal phase” or the like indicates a crystal phase mainly containing crystal grains of In ₆ Ga ₂ Sn ₂ O ₁₆ , and In ₆ Ga ₂ Sn ₂ O _It does not exclude the inclusion of a small amount of compounds and foreign elements other than ₁₆ . The phrase “including mainly In ₆ Ga ₂ Sn ₂ O ₁₆ crystal grains” means that approximately 90% by volume or more of the crystal phase is occupied by crystal grains of In ₆ Ga ₂ Sn ₂ O _16. It shall preferably indicate that it is composed only of crystal grains of In ₆ Ga ₂ Sn ₂ O ₁₆ excluding inevitable impurities.

  The presence of each crystal phase in the oxide sintered body can be confirmed by, for example, powder X-ray diffraction (XRD), transmission electron diffraction (TED) using TEM, or the like. That is, the existence of each crystal phase can be confirmed by comparing the diffraction pattern obtained by these methods with the diffraction pattern of each compound described in a JCPDS (Joint Committee on Powder Diffraction Standards) card. .

However, in the XRD or TED diffraction pattern, when the peak derived from In ₆ Ga ₂ Sn ₂ O ₁₆ and the peak derived from In ₂ Ga ₂ ZnO ₇ are very close to each other, it is difficult to distinguish between them. There is also a possibility. In that case, a scanning electron microscope (SEM) and an energy dispersive X-ray detector (EDX) attached thereto (hereinafter collectively referred to as “SEM-EDX”) Or TEM-EDX may be used in combination. That is, in the XRD or TED diffraction pattern, when there is a peak that can be identified as either In ₆ Ga ₂ Sn ₂ O ₁₆ or In ₂ Ga ₂ ZnO ₇ , surface analysis is performed by SEM-EDX or TEM-EDX, When a region in which In, Ga, and Sn are mixed is confirmed, it can be determined that an In ₆ Ga ₂ Sn ₂ O ₁₆ crystal phase exists. Further, it can be determined that the region where the In, Ga, and Zn coexist in the plane analysis If confirmed, In ₂ Ga ₂ ZnO ₇ crystal phase is present.

  Here, when performing surface analysis using SEM-EDX, TEM-EDX, or the like, sufficient attention must be paid to the analysis depth, and conditions for the analysis depth to be equal to or less than the crystal grain size must be selected. At this time, if the analysis depth exceeds the crystal grain size, a plurality of crystal grains may be included in the depth direction of the range to be analyzed, so information derived from the plurality of crystal grains is reflected in the analysis result. It is also conceivable that the analysis accuracy decreases. In the case of SEM-EDX, the analysis depth can be adjusted by the acceleration voltage of the primary electron beam. When using TEM-EDX, it is necessary to reduce the thickness of the sample to a crystal grain size or less.

(ZnGa ₂ O ₄ crystal phase in which Sn is dissolved)
The oxide sintered body of the embodiment preferably further includes a ZnGa ₂ O ₄ crystal phase in which Sn is dissolved. As described above, when the target contains a SnO ₂ crystal phase, nodules are generated and it is difficult to maintain the sputtering discharge. However, if the presence form of Sn in the oxide sintered body is a solid solution form in the ZnGa ₂ O ₄ crystal phase, the generation of nodules is very small. Therefore, since the oxide sintered body contains a ZnGa ₂ O ₄ crystal phase in which Sn is dissolved, stable sputtering discharge can be realized, and semiconductor device characteristics (for example, TFTs) are formed in the oxide semiconductor film to be formed. Sn that is beneficial from the viewpoint of (characteristic) can be contained. In addition, since the oxide sintered body includes the crystal phase, the electrical resistance value is reduced, and it is possible to stably maintain the sputtering discharge in a wide oxygen partial pressure region during film formation.

The ZnGa ₂ O ₄ crystal phase has a spinel crystal structure. In the XRD or TED diffraction pattern, the peak derived from the ZnGa ₂ O ₄ crystal phase in which Sn is dissolved is present at a position close to the peak attributed to ZnGa ₂ O ₄ described in the JCPDS card. The solid solution form of Sn in this crystal phase is not particularly limited, and may be, for example, a form in which a part of the Ga site is substituted by Sn, or a form in which Sn enters between the lattices of ZnGa ₂ O _4. It may be. Therefore, the position of the peak derived from the ZnGa ₂ O ₄ crystal phase in which Sn is dissolved in the present embodiment has a larger face spacing or a smaller face spacing compared to the position of the ZnGa ₂ O ₄ peak in the JCPDS card. It can happen. At this time, in this embodiment, it is preferable that the surface interval is smaller than that of ZnGa ₂ O ₄ in the JCPDS card, that is, the diffraction angle 2θ in the X-ray diffraction pattern is large. Thereby, the field effect mobility of TFT produced using an oxide sintered compact for a sputtering target can be improved.

(Zn ₂ SnO ₄ crystal phase in which Ga is dissolved)
The oxide sintered body of the embodiment preferably further includes a Zn ₂ SnO ₄ crystal phase in which Ga is dissolved. This is because the Zn ₂ SnO ₄ crystal phase in which Ga is a solid solution is also a crystal phase containing Sn and generating little nodules. In addition, since the oxide sintered body includes the crystal phase, the electrical resistance value is reduced, and it is possible to stably maintain the sputtering discharge in a wide oxygen partial pressure region during film formation.

The Zn ₂ SnO ₄ crystal phase has an inverse spinel crystal structure. In the XRD or TED diffraction pattern, the peak derived from the Zn ₂ SnO ₄ crystal phase in which Ga is dissolved is present at a position close to the peak attributed to Zn ₂ SnO ₄ described in the JCPDS card. The solid solution form of Ga in this crystal phase is not particularly limited. For example, it may be a form in which a part of Sn site is substituted by Ga, or a form in which Ga penetrates between lattices of Zn ₂ SnO _4. There may be. Therefore, the position of the peak derived from the Zn ₂ SnO ₄ crystal phase in which Ga of the present embodiment is dissolved is larger or smaller than the position of the Zn ₂ SnO ₄ peak in the JCPDS card. It can happen. At this time, in this embodiment, it is preferable that the surface interval is larger than that of Zn ₂ SnO ₄ in the JCPDS card, that is, the diffraction angle 2θ in the X-ray diffraction pattern is small. Thereby, the OFF current of the TFT manufactured using the oxide sintered body as a sputtering target can be reduced.

(InGaZnO ₄ crystal phase in which Sn is dissolved)
The oxide sintered body according to the embodiment can include an InGaZnO ₄ crystal phase in which Sn is dissolved. Whether or not an InGaZnO ₄ crystal phase in which Sn is dissolved is present in the oxide sintered body can be confirmed by XRD.

In the X-ray diffraction pattern, a peak derived from the InGaZnO ₄ crystal phase in which Sn is dissolved appears in a range where the diffraction angle 2θ is greater than 30.81 ° and not more than 30.90 °. In this specification, this peak is referred to as “a peak”. The a peak has a high angle, that is, a small interplanar spacing compared to the value of InGaZnO _{4 in} the JCPDS card.

According to the inventor's research, the diffraction intensity Ia of the a peak and the diffraction intensity Ib of the peak derived from the In ₂ Ga ₂ ZnO ₇ crystal phase (referred to as “b peak”) satisfy a specific relationship. Thus, it has been found that the range of the oxygen partial pressure capable of maintaining a stable sputtering discharge is expanded.

The b peak is one peak in the X-ray diffraction pattern having a diffraction angle 2θ in the range of 38.00 ° to 38.15 °. This b peak has a higher angle, that is, a smaller interplanar spacing than the value of In ₂ Ga ₂ ZnO ₇ in the JCPDS card.

  Here, when Ib / Ia, which is the ratio of the diffraction intensity Ib of the b peak to the diffraction intensity Ia of the a peak, is 0.02 or more and 0.1 or less, the sputtering discharge can be sustained with a wide range of oxygen partial pressures. When Ib / Ia is less than 0.02, the range of oxygen partial pressure in which sputtering discharge can be sustained may be narrowed. Further, when Ib / Ia exceeds 0.1, the field-effect mobility of the oxide semiconductor film to be formed is lowered, and one of the advantages of using the oxide semiconductor may be impaired. From the viewpoint of making the range of the oxygen partial pressure wider, the range of Ib / Ia is more preferably 0.02 or more and 0.07 or less, and particularly preferably 0.02 or more and 0.05 or less. .

(Element composition of sintered oxide)
The oxide sintered body contains In, Ga, Zn, and Sn, and the composition of the constituent elements is the following formula (1) to the following formula (5):
0.4 <In / (In + Ga + Zn) ≦ 0.65 (1)
0.3 <In / (In + Ga + Zn + Sn) ≦ 0.50 (2)
0.20 ≦ Sn / (Sn + Zn) <0.33 (3)
0.05 <Sn / (In + Ga + Sn + Zn) <0.2 (4)
0.41 ≦ In / (In + Zn + Sn) ≦ 0.6 (5)
It is preferable to satisfy all of the above.

  Regarding the above formula (1), when In / (In + Ga + Zn) is 0.4 or less, the field-effect mobility of the oxide semiconductor film is lowered, which is not preferable. On the other hand, when it exceeds 0.65, the Von value of the TFT characteristics becomes a negative value, which is not preferable. Here, since the “Von value” is a voltage driven by the TFT, it is desired that the voltage is a positive voltage larger than 0 V for the convenience of TFT control. When the Von value becomes a negative value, a range from negative to positive is required as a control voltage of the TFT, and the control may be complicated. From this viewpoint, In / (In + Ga + Zn) is more preferably 0.41 or more and 0.50 or less.

  Regarding the above formula (2), it is not preferable that In / (In + Ga + Zn + Sn) is 0.3 or less because the field-effect mobility of the oxide semiconductor film is lowered. On the other hand, if it exceeds 0.50, the OFF current of the TFT characteristics becomes large, which is not preferable. In / (In + Ga + Zn + Sn) is more preferably 0.35 or more and 0.4 or less.

Regarding the above formula (3), when Sn / (Sn + Zn) is less than 0.20, the field-effect mobility of the oxide semiconductor film is lowered, which is not preferable. On the other hand, if it is 0.33 or more, the SnO ₂ crystal phase may be precipitated in the oxide sintered body and the sputtering discharge may become unstable. In order to suppress the precipitation of the SnO ₂ crystal phase, it is desirable that the Sn element is contained in the Zn ₂ SnO ₄ crystal phase. Here, the theoretical value of Sn / (Sn + Zn) in the ideal Zn ₂ SnO ₄ crystal phase is 0.33. Therefore, if Sn / (Sn + Zn) is less than 0.33, Sn can exist stably in the Zn ₂ SnO ₄ crystal phase, and precipitation of the SnO ₂ crystal phase can be suppressed. As a result, stable sustaining of the sputtering discharge can be realized. Sn / (Sn + Zn) is more preferably 0.21 or more and 0.30 or less.

  Regarding the above formula (4), when Sn / (In + Ga + Sn + Zn) is 0.05 or less, the field-effect mobility of the oxide semiconductor film is lowered, which is not preferable. On the other hand, when it is 0.2 or more, the Von value of the TFT characteristics is a negative value, which is not preferable. Sn / (In + Ga + Sn + Zn) is more preferably 0.06 or more and 0.16 or less.

  Regarding the above formula (5), when In / (In + Zn + Sn) is less than 0.41, the field-effect mobility of the oxide semiconductor film is lowered, which is not preferable. On the other hand, if it exceeds 0.6, the OFF current of the TFT characteristics becomes large, which is not preferable. In / (In + Zn + Sn) is more preferably 0.5 or more and 0.58 or less.

(In ₂ O ₃ crystal phase with bixbite type crystal structure)
The oxide sintered body of the embodiment preferably does not contain an In ₂ O ₃ crystal phase having a bixbite type crystal structure. This is because the crystal phase can be a factor that impedes the duration of sputtering discharge, although the influence is not as great as that of the SnO ₂ crystal phase. In a TFT including an oxide semiconductor film formed from a target including the crystalline phase, the OFF current tends to increase.

The presence or absence of an In ₂ O ₃ crystal phase having a bixbite type crystal structure can also be confirmed by powder X-ray diffraction. In the X-ray diffraction pattern, a peak derived from the crystal phase appears in a range where the diffraction angle 2θ is 30.55 ° or more and 30.80 ° or less. Therefore, in the oxide sintered body of the present embodiment, it is preferable that no peak is observed within the diffraction angle 2θ of 30.55 ° or more and 30.80 ° or less in the X-ray diffraction pattern.

(SnO ₂ crystal phase having rutile crystal structure)
As described above, the oxide sintered body of the embodiment is different from the prior art in that the Sn element is contained in a form in which it is difficult to precipitate as an SnO ₂ crystal phase. The presence or absence of a SnO ₂ crystal phase having a rutile crystal structure can also be confirmed by a powder X-ray diffraction method. In the X-ray diffraction pattern, a peak derived from the crystal phase appears in a range where the diffraction angle 2θ is 34.30 ° or more and 34.50 ° or less. Therefore, in the oxide sintered body of the present embodiment, it is desirable that no peak is observed in the diffraction angle 2θ of 34.30 ° or more and 34.50 ° or less in the X-ray diffraction pattern.

(In ₂ O ₃ (ZnO) _m crystal phase)
According to the study of the present inventor, an oxide sintered body containing a crystal phase of In ₂ O ₃ (ZnO) _m (where m is a natural number) tends to have high electrical resistance. Therefore, it is preferable that the oxide sintered body does not contain an In ₂ O ₃ (ZnO) _m crystal phase, and by not containing it, it can be a target suitable for DC sputtering. In addition, since the oxide sintered body does not include an In ₂ O ₃ (ZnO) _m crystal phase, an OFF current can be reduced in a TFT including an oxide semiconductor film formed using this as a target.

(Additive elements)
The oxide sintered body is made of Ti, W, Hf, Zr or Si at 1 at. % Or more and 10 at. It is preferable to contain in% or less range. When the target contains these elements, the oxide semiconductor film can contain these elements. When the oxide semiconductor film contains these elements, a TFT with high field effect mobility and low OFF current can be realized. The content of the additive element is more preferably 1 at. % Or more and 6 at. % Or less, particularly preferably 1 at. % Or more and 5 at. % Or less.

  The method for adding the above elements to the oxide sintered body is not particularly limited, and for example, when the raw material powder is mixed, it can be added in the form of an oxide powder. In addition to Ti, W, Hf, Zr or Si, aluminum (Al), vanadium (V), chromium (Cr), niobium (Nb), molybdenum (Mo), tantalum (Ta), bismuth (Bi), etc. are added. You can also

<Method for producing oxide sintered body>
The oxide sintered body of the first embodiment described above can be manufactured as follows. FIG. 1 is a flowchart showing an outline of a method for producing an oxide sintered body. As shown in FIG. 1, the oxide sintered body of the first embodiment can be manufactured by sequentially executing the steps S101 to S105.

(Process S101)
In step S101, Ga ₂ O ₃ powder, ZnO powder and SnO ₂ powder are mixed to obtain a first mixture. Here, the purity of each raw material powder is preferably 99.9% or more. The mixing of the raw material powder can be general pulverized mixing. For example, wet or dry pulverization and mixing can be performed using an ordinary ball mill, planetary ball mill, bead mill, or the like. In addition, when wet mixing is performed, the obtained mixture can be dried using a drying method such as natural drying or spray drying.

(Step S102)
In step S102, the first mixture is heat-treated (calcined). The calcination temperature is preferably 800 ° C. or higher and lower than 1200 ° C., more preferably 800 ° C. or higher and 1100 ° C. or lower, and particularly preferably 800 ° C. or higher and 1000 ° C. or lower.

(Step S103)
In step S103, the calcined first mixture and In ₂ O ₃ powder are mixed to obtain a second mixture. The purity of the In ₂ O ₃ powder is preferably 99.9% or more. The mixing method described in step S101 can be used for mixing the first mixture and the In ₂ O ₃ powder. In step S103, TiO ₂ powder, WO ₃ powder, HfO ₂ powder, ZrO ₂ powder, SiO ₂ powder, or the like may be added and mixed together with the In ₂ O ₃ powder.

(Step S104)
In step S104, the second mixture is pressure-molded to obtain a molded body. As a method of pressure molding, for example, uniaxial pressure molding (die press), cold isostatic pressing (CIP), hot isostatic pressing (HIP) or the like is used. Can do.

(Step S105)
In step S105, the compact is heat treated (sintered). The sintering temperature (the firing temperature) is preferably 1375 ° C. or higher and 1450 ° C. or lower. The atmosphere during sintering is preferably an air atmosphere, an oxygen atmosphere, a mixed atmosphere of nitrogen and oxygen, or the like. Sintering can be performed at atmospheric pressure, but may be performed in a pressurized gas in order to suppress evaporation of ZnO. Alternatively, a hot press sintering method such as HIP can be used. However, the most preferable conditions are atmospheric pressure and air atmosphere.

  By performing the above steps, the oxide sintered body of the first embodiment can be manufactured.

<Second Embodiment: Semiconductor Device>
The second embodiment is a semiconductor device. The semiconductor device of the second embodiment includes an oxide semiconductor film formed by sputtering using the oxide sintered body of the first embodiment as a target, and the oxide semiconductor film functions as a channel layer. This semiconductor device exhibits a high electric field transfer effect and can be manufactured at low cost.

  FIG. 3 is a schematic plan view showing an example of the configuration of the semiconductor device of the present embodiment. 4 is a schematic cross-sectional view taken along line IV-IV in FIG. The semiconductor device 10 shown in FIGS. 3 and 4 is a TFT. However, this is merely an example, and the semiconductor device is not limited to the TFT as long as the specific oxide semiconductor film is provided.

  Referring to FIG. 4, the semiconductor device 10 includes a substrate 11, a gate electrode 12, a gate insulating film 13, an oxide semiconductor film 14, a source electrode 15, and a drain electrode 16. The gate electrode 12 is disposed on the substrate 11. The gate insulating film 13 is disposed on the gate electrode 12 and insulates between the gate electrode 12 and the source electrode 15 and between the gate electrode 12 and the drain electrode 16. The oxide semiconductor film 14 is a semiconductor film formed by sputtering using the oxide sintered body of the first embodiment as a target, and functions as a channel layer of the semiconductor device 10. The source electrode 15 and the drain electrode 16 are disposed on the oxide semiconductor film 14 so as not to contact each other.

<Semiconductor device manufacturing method>
The semiconductor device of the second embodiment can be manufactured as follows. FIG. 2 is a flowchart showing an outline of a semiconductor device manufacturing method. As shown in FIG. 2, the semiconductor device manufacturing method includes a step S100 of preparing an oxide sintered body, and a step S400 of forming an oxide semiconductor film by sputtering using the oxide sintered body as a target. As long as the said manufacturing method is equipped with these processes, it can be equipped with the arbitrary processes which may be normally contained in the manufacturing process of a semiconductor device. Examples of such a process include a process S200 for forming an electrode and a process S300 for forming a gate insulating film. The flowchart shown in FIG. 2 is merely an example, and the order of other processes may be changed as long as the process S100 and the process S400 are provided in this order.

(Process S100)
In step S100, an oxide sintered body is prepared. Since this step is step S101 to step S105 described above as the method for manufacturing the oxide sintered body, the same description will not be repeated.

(Process S200)
In step S200, the gate electrode 12 is formed on the substrate 11. The substrate 11 is preferably one having high transparency and surface smoothness, and for example, a quartz glass substrate, an alkali-free glass substrate, or the like is used. The gate electrode 12 may be a metal thin film such as Mo, Ti, W, Al, Cu, for example. Such a metal thin film can be formed by, for example, vacuum deposition, sputtering, or the like.

(Process S300)
In step S300, the gate insulating film 13 is formed on the gate electrode 12. The gate insulating film 13 is preferably an SiO _x film, an SiN _x film, or the like. Such a SiO _x film or the like can be formed by, for example, plasma CVD (Chemical Vapor Deposition).

(Process S400)
In step S400, the oxide semiconductor film 14, that is, the channel layer is formed on the gate insulating film 13 by sputtering using the oxide sintered body of the first embodiment as a target. By using such a specific target, sputtering discharge can be stably maintained and a semiconductor device can be manufactured at low cost.

  In step S400, abnormal discharge can be suppressed by targeting the oxide sintered body of the first embodiment. Therefore, the sputtering discharge can be sustained with a lower oxygen partial pressure than in the prior art. Therefore, the film formation speed can be increased. The molar fraction of oxygen in the mixed gas used in step S400 is preferably 0.1 or more and 0.3 or less, more preferably 0.1 or more and 0.25 or less, and particularly preferably 0.1 or more and 0 or less. .20 or less.

(Process S500)
In step S <b> 500, the source electrode 15 and the drain electrode 16 are formed on the oxide semiconductor film 14. At this time, the source electrode 15 and the drain electrode 16 are formed so as not to contact each other, for example, by patterning using a photoresist and wet etching using a mixed solution of phosphoric acid and acetic acid or an oxalic acid aqueous solution. In addition, the electrode material and the film forming method can be the same as those described in step S200.

  Hereinafter, although this embodiment is described in detail using an example, this embodiment is not limited to these. In the following description, “BET specific surface area” indicates a specific surface area measured based on the BET method.

  Various oxide sintered bodies (samples No. 1 to No. 18) were produced as follows. And the semiconductor device (TFT) was produced by forming an oxide semiconductor film by sputtering using these targets, and the characteristic was evaluated. Here, sample No. 1-No. 16 corresponds to the example, and sample No. 17 and no. 18 corresponds to a comparative example.

<Sample No. 1>
1. Mixing of raw material powder First, as raw material powder, Ga ₂ O ₃ powder (purity: 99.99%, BET specific surface area: 11 m ² / g) and ZnO powder (purity: 99.99%, BET specific surface area; 4 m ² / g) and SnO ₂ powder (purity: 99.9%, BET specific surface area: 5 m ² / g) were prepared.

Each raw material powder is weighed and put into a ball mill so that the molar mixing ratio of Ga ₂ O ₃ , ZnO and SnO ₂ becomes the value shown in Table 1, and pulverized and mixed for 12 hours using the ball mill. (Step S101). This gave a first mixture _{(Ga 2 O 3 -ZnO-SnO} 2 mixture). Ethanol was used as a dispersion medium during pulverization and mixing (wet mixing). The first mixture after pulverization and mixing was dried with a spray dryer.

2. Calcination The first mixture was put in an alumina crucible, and calcination was performed in an air atmosphere at 900 ° C. for 8 hours (step S102). As a result, a crystal phase including a Ga ₂ ZnO ₄ crystal phase and a SnZn ₂ O ₄ crystal phase, in which Sn is dissolved in the Ga ₂ ZnO ₄ crystal phase, or a crystal phase in which Ga is dissolved in the SnZn ₂ O ₄ crystal phase is further added A calcined powder containing was obtained.

3. Mixing of In ₂ O ₃ powder The calcined powder and In ₂ O ₃ powder (purity: 99.99%, BET specific surface area: 5 m ² / g) are shown in Table 1 in the molar mixing ratio of each raw material. It measured so that it might become a value, and it injected | thrown-in to the ball mill, and grind | pulverized and mixed for 12 hours using the ball mill (process S103). The molar mixing ratio at this time was the ratio between the number of moles of In ₂ O ₃ and the number of moles of Ga ₂ O ₃ in the first mixture. As a result, a second mixture (calcined powder-In ₂ O ₃ mixture) was obtained. Ethanol was used as a dispersion medium during mixing. The second mixture after pulverization and mixing was also dried with a spray dryer.

4). Molding and Sintering The second mixture was pressure molded with a uniaxial pressure molding machine (step S104) to obtain a disk-shaped molded body having a diameter of 100 mm and a thickness of about 9 mm. The molded body was fired at a temperature shown in Table 1 for 8 hours in an air atmosphere (step S105) to obtain an oxide sintered body (sample No. 1) according to the example.

5. X-ray diffraction measurement A sample for measurement was collected from a part of the oxide sintered body, and crystal analysis was performed by a powder X-ray diffraction method using an X-ray diffraction apparatus. The characteristic X-ray used for diffraction was CuKα ray, and the diffraction angle 2θ and the diffraction intensity I were measured. The presence or absence of each crystal phase was determined from the X-ray diffraction pattern, and the diffraction intensity ratio Ib / Ia of the b peak to the a peak was calculated. The results are shown in Table 2.

  Using an ICP emission spectrometer, the contents of In, Ga, Zn and Sn in the oxide sintered body [unit: at. %] Was measured, and based on the results, In / (In + Ga + Zn + Sn), Sn / (Sn + Zn), Sn / (In + Ga + Sn + Zn) and In / (In + Zn + Sn) were calculated. The results are shown in Table 3.

6). Preparation of Target The oxide sintered body was processed into a sputtering target having a diameter of 3 inches (76.2 mm) and a thickness of 5.0 mm. The electrical resistivity of this target was measured using a commercially available resistivity meter in accordance with the 4-probe method (JIS R 1637). The results are shown in Table 4.

7). Formation of Oxide Semiconductor Film Next, film formation by DC magnetron sputtering was performed using the above target. The sputter surface was the main surface of the target (3 inches in diameter). The specific procedure of operation is as follows.

First, a synthetic quartz glass substrate of 50 mm × 50 mm × 0.6 mm was prepared as a film formation substrate. In this substrate, a gate electrode made of a Mo metal thin film and a gate insulating film made of amorphous SiO _x are formed on the main surface in advance (steps S200 and S300). .

  This substrate was set on a water-cooled substrate holder in the film forming chamber of the sputtering apparatus. At this time, the substrate was placed facing the target, and the distance between the substrate and the target was 90 mm.

Next, the film formation chamber was evacuated to about 6 × 10 ⁻⁵ Pa, and the target was pre-sputtered. In pre-sputtering, a shutter is sandwiched between the substrate and the target, and a mixed gas composed of Ar gas and oxygen (O ₂ ) gas (O ₂ molar fraction = 0.17) is introduced into the film forming chamber. Further, 80 W direct current power was applied to the target to generate sputtering discharge. Then, pre-sputtering was performed for 10 minutes to clean the surface of the target.

After that, while introducing a mixed gas having a molar fraction of O ₂ of 0.17 into the deposition chamber at a pressure of 0.5 Pa, a sputtering power of 80 W was applied to the target, and the oxide semiconductor film was formed on the substrate. Was formed (step S400). During film formation, no particular bias voltage was applied to the substrate holder, and only water cooling of the holder was performed. The film formation time was set so that the thickness of the oxide semiconductor film was 30 nm.

8). Evaluation of abnormal discharge during sputtering Evaluation of abnormal discharge during sputtering was performed as follows. That is, film formation was performed while applying a sputtering power of 120 W to the target, and it was confirmed whether stable sputtering discharge could be sustained. For those in which sputtering discharge was sustainable, the number of occurrences of abnormal discharge during film formation was counted, and the frequency of occurrence of abnormal discharge (number of times / minute) within a unit time was calculated. The results are shown in Table 4. In Table 4, “Discharge sustainability” in the column “Yes” indicates that the sputtering discharge was sustainable, and “No” indicates that abnormal discharge occurred frequently during the sputtering and glow discharge occurred. Indicates that it could not be sustained.

9. Etching An oxide semiconductor film (thickness 30 nm) was etched to form a channel layer having a predetermined channel length (L) and channel width (W). First, an aqueous etching solution having phosphoric acid: acetic acid: water = 4: 1: 10 (volume ratio) was prepared. Then, the temperature of the etching aqueous solution was adjusted to 40 ° C. in a hot bath, and the substrate on which the oxide semiconductor film was formed was immersed in the etching aqueous solution. The composition of the aqueous etching solution here may be oxalic acid: water = 1: 20 (mass ratio).

10. Formation of source electrode and drain electrode First, a resist is applied on the oxide semiconductor film so that only a portion of the upper surface of the oxide semiconductor film where the source electrode and the drain electrode are to be formed is exposed, and exposure and development are performed. Was done. Next, a source electrode and a drain electrode having a thickness of 100 nm were formed by sputtering on the portion of the top surface of the oxide semiconductor film where the resist was not formed (step S500). Thereafter, the resist on the oxide semiconductor film was peeled off. Thus, a TFT including the oxide semiconductor film as a channel layer was obtained.

11. Heat treatment The TFT was heat-treated at 300 ° C. for 1 hour in a nitrogen atmosphere.

<Evaluation of TFT characteristics>
The TFT characteristics were evaluated by measuring the field effect mobility μ _fe , the OFF current, and the Von value. These measurement results are shown in Table 5. The specific measurement procedure is as follows.

Using a conductive Si wafer as a gate electrode, a measuring needle was brought into contact with the source electrode and the drain electrode. Next, the voltage (V _gs ) applied between the source electrode and the gate electrode is changed from −10 V to 25 V with a voltage (V _ds ) of 0.1 V applied between the source electrode and the drain electrode. The drain current (I _ds ) was measured. The measurement results were plotted on two-dimensional coordinates with V _gs as the X axis and I _ds as the Y axis, and a graph showing TFT characteristics was obtained. From this graph, V _gs at I _ds = 7 × 10 ⁻¹² A was taken as the Von value.

Further, as shown in the following formula (6), g _m was derived by differentiating I _ds with respect to V _gs . Then, using the value of g _m at V _gs = 8.0 V, the field effect mobility μ _fe was calculated from the following equation (7).
g _m = dI _ds / dV _gs (6)
μ _fe = g _m · L / (W · C _i · V _ds ) (7)
In calculating μ _fe , L (channel length) in equation (7) was 20 μm and W (channel width) was 30 μm. C _i (capacitance of the gate insulating film) was 3.4 × 10 ⁻⁸ F / cm ² and the source-drain voltage (V _ds ) was 1.0 V.

For the OFF current, the value of I _ds when V _gs = −1.0 V and V _ds = 5.0 V was adopted. It can be said that the smaller the OFF current, the better the TFT characteristics.

<Sample No. 2-No. 11>
As shown in Table 1, the sample No. was changed except that the production conditions such as the molar mixing ratio of the raw material powder were changed. In the same manner as in Example 1, oxide sintered bodies (samples No. 2 to No. 11) according to the examples were obtained, and TFTs were manufactured by sputtering using this as a target. And sample no. In the same manner as in Example 1, the oxide sintered body and the TFT characteristics were evaluated. The results are shown in Tables 2-5.

<Sample No. 12-No. 16>
Sample No. 12-No. In No. 16, when the second mixture was obtained, a different oxide powder (TiO ₂ powder, WO ₃ powder, HfO ₂ powder, ZrO ₂ powder or SiO ₂ powder) was added and pulverized and mixed. At this time, the molar mixing ratio with respect to In ₂ O ₃ powder was set to the values shown in Table 1.

  And about other conditions, as shown in Table 1, the oxide sintered compact (sample No. 12-sample No. 16) which concerns on an Example was obtained. The content of the additive element in the oxide sintered body was measured using an ICP emission analyzer in the same manner as In, Ga, Zn, and Sn. The results are shown in Table 3. Further, a TFT was manufactured by sputtering. In the same manner as in Example 1, the oxide sintered body and the TFT characteristics were evaluated. The results are shown in Tables 2-5.

<Sample No. 17 and no. 18>
Sample No. 17 and no. No. 18 was prepared assuming a conventional oxide sintered body. That is, Ga ₂ O ₃ powder, ZnO powder, SnO ₂ powder and In ₂ O ₃ powder are pulverized and mixed together to obtain a mixture, which is further calcined, molded and sintered under the conditions shown in Table 1. An oxide sintered body was obtained.

The X-ray diffraction measurement of the oxide sintered body according to the comparative example (sample No. 17 and sample No. 18) was performed similarly to the examples (sample No. 1 to No. 16). Thus, it was confirmed that a SnO ₂ crystal phase was present inside these oxide sintered bodies.

  In addition, as in the example, film formation by sputtering was attempted using the oxide sintered body according to the comparative example as a target. However, as shown in Table 4, sputtering discharge could not be sustained and film formation was difficult. .

<Results and discussion>
1. In ₆ Ga ₂ Sn ₂ O ₁₆ crystal phase and In ₂ Ga ₂ ZnO ₇ crystal phase From the results of X diffraction measurement shown in Table 2, in the oxide sintered bodies (samples No. 1 to No. ₁₆ ) according to the examples. The presence of at least one of the In ₆ Ga ₂ Sn ₂ O ₁₆ crystal phase and the In ₂ Ga ₂ ZnO ₇ crystal phase was confirmed. On the other hand, in the oxide sintered bodies according to the comparative examples (samples No. 17 and No. 18), the presence of these crystal phases was not confirmed, and the presence of the SnO ₂ crystal phase was confirmed as described above. .

And as shown in Table 4, in the behavior at the time of sputtering, a clear difference appeared between the example and the comparative example. That is, when the oxide sintered body of the example was used as the target, the sputtering discharge could be continued, whereas when the oxide sintered body of the comparative example was used as the target, the discharge could not be sustained. . Therefore, from these results, even if it is an oxide sintered body containing Sn element, it contains at least one of In ₆ Ga ₂ Sn ₂ O ₁₆ crystal phase and In ₂ Ga ₂ ZnO ₇ crystal phase. It can be said that the sputtering discharge can be continued.

2. Diffraction intensity ratio Ib / Ia
From Table 2 and Table 4, Sample No. whose diffraction intensity ratio Ib / Ia is 0.02 or more and 0.1 or less. 2-No. Sample No. 4 which does not satisfy such conditions. 1 and no. Compared with 5, sputtering discharge could be stably maintained.

3. Elemental Composition of Oxide Sintered Body As shown in Table 3, the oxide sintered body of the example satisfies at least one of the above formulas (1) to (5). Furthermore, sample No. 1 satisfying all of the above formulas (1) to (5). 4 and no. At 8 mag, it was confirmed that the Von value showed a positive value and the field effect mobility was high.

4). In ₂ O ₃ crystal phase and In ₂ O ₃ (ZnO) _m crystal phase As shown in Table 2, the oxide sintered bodies of the comparative examples (samples No. 17 and No. 18) are SnO having a rutile crystal structure. _In addition to the _two crystal phases, an In ₂ O ₃ crystal phase and an In ₂ O ₃ (ZnO) _m crystal phase having a bixbite type crystal structure were included. And as shown in Table 4, the oxide sintered compact of the comparative example resulted in a high electrical resistivity. Therefore, it is considered that the presence of these crystal phases increases the electrical resistivity of the oxide sintered body and inhibits the sustaining of the sputtering discharge.

5. Additive elements As shown in Tables 3 and 5, Ti, W, Hf, Zr or Si was added at 1 at. % Or more and 10 at. % Of sample No. 12-No. It was confirmed that the TFT manufactured using 16 has a high field effect mobility.

  Although the present embodiment and examples have been described above, it is also planned from the beginning to appropriately combine the configurations of the embodiments and examples disclosed this time.

  The embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 10 Semiconductor device 11 Substrate 12 Gate electrode 13 Gate insulating film 14 Channel layer 15 Source electrode 16 Drain electrode L Channel length W Channel width

Claims (11)

Containing In, Ga, Zn and Sn;
Including at least one of an In ₆ Ga ₂ Sn ₂ O ₁₆ crystal phase and an In ₂ Ga ₂ ZnO ₇ crystal phase,
An oxide sintered body further comprising at least one of a ZnGa ₂ O ₄ crystal phase in which Sn is dissolved and a Zn ₂ SnO ₄ crystal phase in which Ga is dissolved. The oxide sintered body according to claim 1, further comprising an InGaZnO ₄ crystal phase in which Sn is dissolved. In the diffraction pattern by the powder X-ray diffraction method, a peak having a diffraction angle 2θ of greater than 30.81 ° and less than or equal to 30.90 ° is defined as a peak, and the diffraction angle 2θ is 38.00 ° or more and 38.15 ° or less. When one peak in the range is b peak,
The diffraction intensity ratio Ib / Ia of the b peak to a peak, is 0.02 to 0.1, the oxide sintered body according to claim 2. The elemental composition of the oxide sintered body is represented by the following formula (1) to the following formula (5):
0.4 <In / (In + Ga + Zn) ≦ 0.65 (1)
0.3 <In / (In + Ga + Zn + Sn) ≦ 0.50 (2)
0.20 ≦ Sn / (Sn + Zn) <0.33 (3)
0.05 <Sn / (In + Ga + Sn + Zn) <0.2 (4)
0.41 ≦ In / (In + Zn + Sn) ≦ 0.6 (5)
The oxide sintered body according to any one of claims 1 to 3, which satisfies all of the above.   The oxide according to any one of claims 1 to 4, wherein a peak is not observed within a diffraction angle 2θ of 30.55 ° or more and 30.80 ° or less in a diffraction pattern by a powder X-ray diffraction method. Sintered body. The oxide sintered body according to any one of claims 1 to 5, which does not include an In ₂ O ₃ crystal phase having a bixbite type crystal structure.   The oxide according to any one of claims 1 to 6, wherein no peak is observed within a diffraction angle 2θ of 34.30 ° or more and 34.50 ° or less in a diffraction pattern by a powder X-ray diffraction method. Sintered body. The oxide sintered body according to any one of claims 1 to 7, which does not include a SnO ₂ crystal phase having a rutile crystal structure. The oxide sintered body according to any one of claims 1 to 8, which does not include a crystal phase of In ₂ O ₃ (ZnO) _m (wherein m is a natural number).   Ti, W, Hf, Zr or Si is added at 1 at. % Or more and 10 at. The oxide sintered body according to any one of claims 1 to 9, which is contained in a range of not more than%. Preparing the oxide sintered body according to any one of claims 1 to 10, and
Using the oxide sintered body as a target, and forming an oxide semiconductor film by sputtering,
The method for manufacturing a semiconductor device, wherein the oxide semiconductor film is a channel layer.

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