JP2011058012A - Semi-conductor oxide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semi-conductor oxide capable of suppressing occurrence of nodule, and enhancing its characteristic. <P>SOLUTION: The conductive oxide is a non-crystalline conductive oxide, and contains indium, gallium, zinc, oxygen and nitrogen while the concentration of nitrogen is ≥1×10<SP>20</SP>(atom/cc) and ≤1×10<SP>22</SP>atom/cc. The ratio of the concentration of In to the total concentration of the concentration of In, the concentration of Ga and the concentration of Zn is ≥0.30 and ≤0.66. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a semiconductor oxide.

  In liquid crystal display devices, thin film electroluminescence, organic EL display devices, and the like, amorphous silicon films have been mainly used as a thin film transistor (TFT) channel layer and a transparent thin film for transparent electrodes.

  However, in recent years, as this transparent thin film, an amorphous semiconductor film (IGZO film) mainly composed of an In—Ga—Zn-based composite oxide (IGZO) has a carrier mobility higher than that of an amorphous silicon film. It attracts attention from the advantage of being large (for example, Patent Document 1).

JP 2008-199005 A

  In the semiconductor oxide such as the IGZO film disclosed in Patent Document 1, it is desired to suppress nodules generated on the target surface and improve the characteristics of the semiconductor oxide.

  Therefore, the present invention is to provide a semiconductor oxide that suppresses the generation of nodules and improves the characteristics.

The semiconductor oxide of the present invention is an amorphous semiconductor oxide and contains indium (In), gallium (Ga), zinc (Zn), oxygen (O), and nitrogen (N), and the concentration of N is 1 × 10 ²⁰ atoms / cc or more and 1 × 10 ²² atoms / cc or less, and the ratio of In concentration to the total concentration of In concentration, Ga concentration, and Zn concentration is 0.30 or more and 0.66 It is characterized by the following.

As a result of intensive studies to suppress nodules generated on the target surface, the present inventor has found that generation of nodules can be suppressed by increasing the In concentration so that the ratio is 0.3 or more. However, when the In concentration is increased, there is an effect in suppressing nodules, but the carrier concentration is increased and a desired on / off ratio may not be achieved. Accordingly, as a result of intensive studies to suppress the increase in carrier concentration due to In, the present inventor has further found that the increase in carrier concentration due to In can be further suppressed by trapping carrier electrons with N. By setting the above ratio to 0.66 or less, the In carrier concentration does not become too high, and the N concentration is set to 1 × 10 ²⁰ atom / cc or more and 1 × 10 ²² atom / cc or less, so By trapping electrons, an increase in carrier concentration due to In can be suppressed. Therefore, characteristics such as on / off ratio can be improved. As described above, a semiconductor oxide that suppresses generation of nodules and improves characteristics can be realized.

  As described above, according to the semiconductor oxide of the present invention, generation of nodules can be suppressed and characteristics can be improved.

Hereinafter, embodiments of the present invention will be described in detail.
(Embodiment 1)
The semiconductor oxide in this embodiment contains In, Ga, Zn, O, and N. The semiconductor oxide is preferably composed mainly of In, Ga, Zn, O and N, with the remainder being inevitable impurities.

  In a semiconductor oxide, the ratio of In concentration to the total concentration of In, Ga, and Zn (In concentration / (In concentration + Ga concentration + Zn concentration)) is 0.30 or more and 0 .66 or less, more preferably 0.36 or more and 0.55 or less. When the ratio is 0.30 or more, nodules can be suppressed. When the ratio is 0.36 or more, nodules can be further suppressed. When the ratio is 0.66 or less, the carrier concentration does not become too high, so that the on / off ratio can be improved when used in a TFT or the like. In other words, since it can be turned off even when the gate voltage is low, it can be suitably used for a TFT. When the ratio is 0.55 or less, the on / off ratio can be further improved.

  Here, the In concentration, the Ga concentration, and the Zn concentration are values (unit: atom%) measured by RBS (Rutherford backscattering spectroscopy). The above ratio is a value calculated from each measured concentration value.

The N concentration of the semiconductor oxide is 1 × 10 ²⁰ atoms / cc to 1 × 10 ²² atoms / cc. In the case of 1 × 10 ²⁰ atoms / cc or more, since carrier electrons can be trapped, it can be suppressed that the carrier concentration due to In becomes too high. Further, the present inventor has also found that nodules can be further suppressed by containing N, and that nodules can be effectively suppressed particularly when the N concentration is 1 × 10 ²⁰ atoms / cc or more. For this reason, while suppressing the carrier concentration by In becoming too high, generation | occurrence | production of a nodule can further be suppressed by N. If it is possible to suppress the carrier concentration from becoming too high, it is possible to suppress a decrease in the on / off ratio and the like, and thus it is possible to suppress deterioration of characteristics as a TFT. On the other hand, when the concentration of N is 1 × 10 ²² atoms / cc or less, nodules can be suppressed and trapping of carrier electrons due to N can be suppressed too much, so that the carrier concentration becomes too low or becomes insulating. Can be suppressed. If it is possible to suppress the carrier concentration from becoming too low and insulation, it is possible to suppress a decrease in electron mobility and the like, and thus it is possible to suppress deterioration of characteristics as a TFT.

  Here, the concentration of N is a value measured by SIMS, and means the number of atoms per unit volume.

  Further, the semiconductor oxide is amorphous. Furthermore, since it has the said characteristic, it is preferable to use a semiconductor oxide for the channel layer of TFT, the transparent thin film for transparent electrodes, etc.

Then, the manufacturing method of the semiconductor oxide in this Embodiment is demonstrated. In this embodiment, it is a crystalline semiconductor oxide, and includes In, Ga, Zn, O, and N. For example, N having a concentration of 1 × 10 ²⁰ atoms / cc or more and 1 × 10 ²³ atoms / cc is present. In addition, a semiconductor oxide is manufactured by a sputtering method using a target in which the ratio of the In concentration to the total concentration of In, Ga, and Zn is, for example, 0.28 or more and 0.60 or less. ing.

First, the target is prepared. The concentration of N in preparation for the target is, for example, 1 × 10 ²⁰ atom / cc or more 1 × 10 ²³ atom / cc, preferably not more than 3 × 10 ²⁰ atom / cc or 8 × 10 ²² atom / cc. The ratio of the In concentration to the total concentration of the In concentration, Ga concentration, and Zn concentration of the target to be prepared is, for example, 0.20 or more and 0.65 or less, preferably 0.28 or more and 0.00. 60 or less. Such a target can be obtained, for example, by manufacturing as follows.

Specifically, first, target raw materials are prepared. As the raw material powder, indium oxide (In ₂ O ₃ ), gallium oxide (Ga ₂ O ₃ ), zinc oxide (ZnO), gallium nitride (GaN), indium nitride (InN), or the like can be used. The purity of the raw material powder is preferably a high purity of 99.99% or more.

  Next, the raw material powder is mixed. Either the dry method or the wet method may be used for mixing the raw material powder. Specifically, mixing is performed using a normal ball mill or a planetary ball mill. In addition, a drying method such as natural drying or a spray dryer is preferably used for drying when mixing is performed by a wet mixing method.

  Next, the mixed raw material powder is fired (calcined). When the raw material powder contains GaN or InN, the firing temperature is, for example, 500 ° C. or more and 700 ° C. or less, and when it does not contain GaN or InN, it is, for example, 1000 ° C. or more and 1200 ° C. or less.

Next, the calcined calcined powder is sintered. As the sintering atmosphere, an air atmosphere, an atmosphere containing nitrogen, an atmosphere containing ammonia (NH ₃ ) and / or argon (Ar), or the like is preferably used. The sintering temperature is, for example, 1500 ° C. or more and 1700 ° C. or less. Moreover, in order to suppress evaporation of ZnO during sintering, sintering in a pressurized gas, hot press sintering, HIP (hot isostatic pressing) sintering, CIP (cold isostatic pressing) sintering, etc. are used. May be. Note that if the sintering is performed in an atmosphere containing excess oxygen (O), the target may not have sufficient conductivity.

By performing the above steps, a target that is a conductive oxide having the above-described N concentration and In ratio can be manufactured. In such a target manufacturing method, N may be introduced by increasing the amount of GaN in the raw material powder, increasing the sintering atmosphere pressure, N ₂ or NH ₃ and / or Ar as the atmosphere gas. For example, an atmosphere. In particular, when the semiconductor oxide is manufactured by introducing a large amount of nitrogen, it is effective to use NH ₃ and Ar atmosphere gases.

  Next, film formation is performed. In the film forming process, a semiconductor oxide is formed by, for example, a sputtering method using the prepared target. Specifically, first, a substrate is placed on a substrate holder having a coolant. A target prepared to face the substrate is placed.

  Thereafter, vacuuming is performed and pre-sputtering is performed. In pre-sputtering, sputtering discharge is generated in a state where a shutter is put between the substrate and the target, and the target surface is cleaned.

Next, Ar gas and / or N ₂ gas is introduced to a pressure of 0.1 Pa to 10 Pa, for example. Sputtering is performed in this state to form a semiconductor oxide on the substrate.

  By performing the above steps, the semiconductor oxide in this embodiment can be manufactured.

As described above, the semiconductor oxide in this embodiment is an amorphous semiconductor oxide and includes In, Ga, Zn, O, and N, and the concentration of N is 1 × 10 ²⁰ atoms / cc is 1 × 10 ²² atoms / cc or less, and the ratio of the In concentration to the total concentration of In, Ga, and Zn is 0.30 or more and 0.66 or less. To do.

  As a result of intensive studies to suppress nodules generated on the target surface, the present inventor has found that generation of nodules can be suppressed by increasing the In concentration so that the ratio is 0.30 or more. Nodules cause abnormal discharge, and when abnormal discharge occurs, coarse particles are mixed in the semiconductor oxide, and electron mobility is deteriorated. In addition, when a semiconductor oxide film is formed by DC sputtering using a target, it is difficult for electricity to flow during the film formation, and the semiconductor oxide cannot be realized in the first place. However, since the semiconductor oxide of this embodiment contains In at a high concentration so as to have the above ratio, nodules can be suppressed. For this reason, since abnormal discharge can be suppressed, the characteristics of the semiconductor oxide can be improved, for example, the electron mobility can be improved.

Increasing the concentration of In is effective in suppressing nodules, but the carrier concentration increases and a desired on / off ratio may not be achieved. Accordingly, as a result of intensive studies to suppress the increase in carrier concentration due to In, the present inventor has further found that the increase in carrier concentration due to In can be further suppressed by trapping carrier electrons with N. By setting the above ratio to 0.66 or less, the In carrier concentration does not become too high, and the N concentration is set to 1 × 10 ²⁰ atom / cc or more and 1 × 10 ²² atom / cc or less, so By trapping electrons, an increase in carrier concentration due to In can be suppressed. Therefore, characteristics such as on / off ratio can be improved. Furthermore, by setting the concentration of N to 1 × 10 ²² atoms / cc or less, it is possible to suppress the carrier concentration from becoming too low and maintain the semiconductor. As described above, a semiconductor oxide that suppresses generation of nodules and improves characteristics can be realized.

(Embodiment 2)
Since the semiconductor oxide in this embodiment is similar to the semiconductor oxide in Embodiment 1, description thereof will not be repeated.

  The method for manufacturing a semiconductor oxide in this embodiment has basically the same structure as the method for manufacturing a semiconductor oxide in Embodiment 1, but a target that does not contain N is used to form a semiconductor oxide. The difference is that nitrogen gas of a predetermined pressure is introduced at the time of formation (film formation).

  Specifically, in the step of preparing the target, for example, a raw material powder not containing N is prepared, and a gas (for example, a gas containing oxygen such as the atmosphere) that hardly takes N into the atmospheric gas is used.

The semiconductor oxide formation (film formation) step is the same as that in Embodiment 1 up to the pre-sputtering step. The subsequent steps will be described below. After pre-sputtering, a gas containing N is introduced. This gas may be N ₂ alone or may further contain Ar or the like. When N ₂ and Ar are included, the amount of nitrogen (that is, N ₂ flow rate / (Ar flow rate + N ₂ flow rate)) is, for example, 5% to 15% and the pressure is 0.05 Pa to 10 Pa, preferably Is set to 0.08 Pa or more and 8 Pa or less. Under such conditions, a semiconductor oxide is formed to have a predetermined thickness.

  By performing the above steps, the semiconductor oxide in this embodiment can be manufactured. The method for introducing N in the method for manufacturing a semiconductor oxide in this embodiment can be adjusted by changing the deposition pressure. In particular, when the semiconductor oxide contains a large amount of nitrogen, it is effective to increase the film forming pressure to 3 Pa or more, for example.

  Note that although a method for manufacturing using a target that does not include N has been described in this embodiment mode, the manufacturing method may be performed using a target including N.

  Moreover, in the manufacturing method of the semiconductor oxide in Embodiments 1 and 2, it has been described that the target is manufactured. However, the semiconductor oxide can be adjusted by adjusting the film forming conditions in the film forming process using an available target. May be manufactured.

  In Embodiments 1 and 2, the semiconductor oxide is manufactured by a sputtering method, but the present invention is not particularly limited thereto, and may be manufactured by another method.

  In this example, various IGZO films as semiconductor oxides were manufactured, and the characteristics of the IZGO film were examined.

Example 1
1. Grinding and mixing of material powders In ₂ O ₃ (purity 99.99%, BET specific surface area 5 m ² / g), Ga ₂ O ₃ (purity 99.99%, BET specific surface area 11 m ² / g), and ZnO (purity 99 Each powder having a BET specific surface area of 4 m ² / g) was pulverized and mixed for 3 hours using a ball mill apparatus. Water was used as the dispersion medium. After pulverization and mixing, the mixture was dried with a spray dryer.

2. Firing (calcination)
Next, the obtained mixed powder was put into an alumina crucible and calcined at 1100 ° C. for 5 hours in an air atmosphere to obtain a calcined powder.

3. Molding and Sintering Next, the obtained calcined powder was pressure-molded by CIP to obtain a disk-shaped molded body having a diameter of 100 mm and a thickness of about 9 mm. The obtained molded body was sintered at 1550 ° C. for 12 hours in an N ₂ atmosphere of 1 atm to obtain a sintered body. The obtained sintered body contracted to a diameter of 80 mm (thickness was about 7 mm).

4). Preparation of Target Next, the obtained sintered body was processed into a diameter of 76.2 mm and a thickness of 5.0 mm to obtain a target of Example 1.

5. Formation of IGZO Film Next, using the target of Example 1, a film was formed as follows. For the film formation, a DC magnetron sputtering method was used. DC was used as the sputtering power source. The target size was 76.2 mm in diameter and 5 mm in thickness, and a plane having a diameter of 3 inches was the sputtering surface.

First, a synthetic quartz glass of 25 mm × 25 mm × 0.6 mm was set on a water-cooled substrate holder. The target of Example 1 was set so as to face the substrate. The distance between the substrate and the target was 40 mm. After completing the setting, vacuuming was performed to about 1 × 10 ⁻⁴ Pa. Next, the target was pre-sputtered. With the shutter placed between the substrate and the target, Ar gas was introduced up to 1 Pa and DC power of 30 W was applied to cause sputtering discharge, and the target surface was cleaned (pre-sputtering) for 10 minutes. .

  Next, Ar gas was introduced up to 0.4 Pa as the sputtering pressure. Film formation was continued until the sputtering power was 50 W and the film thickness of IGZO reached 200 nm. No particular bias voltage was applied to the substrate holder, and it was only water-cooled. Thus, the IGZO film of Example 1 was manufactured.

(Example 2)
The IGZO film of Example 2 was basically manufactured in the same manner as the IGZO film of Example 1, but differed in the prepared target. For the target material powder, the molar ratio of the prepared material powder was changed, and each material powder was prepared so that the composition of the target was as described in Table 1 below. As for the sintered targets were sintered obtained molded body in NH ₃ and Ar atmosphere at 2 atm.

(Example 3)
The IGZO film of Example 3 was basically manufactured in the same manner as the IGZO film of Example 1, but differed in the prepared target. For the target material powder, the molar ratio of the prepared material powder was changed, and each material powder was prepared so that the composition of the target was as described in Table 1 below.

Example 4
The IGZO film of Example 4 was basically manufactured in the same manner as the IGZO film of Example 1, but differed in the prepared target. For the target material powder, the molar ratio of the prepared material powder was changed, and each material powder was prepared so that the composition of the target was as described in Table 1 below. Moreover, about sintering of the target, the obtained molded object was sintered in 2 atmosphere atmosphere.

(Example 5)
The IGZO film of Example 5 was basically manufactured in the same manner as the IGZO film of Example 1, but differed in the formation of the prepared target and the IGZO film. Specifically, it is as follows.

  The target of Example 5 was basically manufactured in the same manner as in Example 1. However, the molar ratio of the prepared material powder was changed so that the composition of the target was as described in Table 1 below. And the point that the compact was sintered in an atmosphere of 1 atm. In the production of the target of Example 5, the material powder containing N was not used, and the gas capable of incorporating N at the time of sintering was not supplied. Therefore, the target of Example 5 did not contain N.

The film forming method of Example 5 was the same as that of Example 1 up to the pre-sputtering process. The subsequent steps will be described below. N ₂ and Ar were introduced after the pre-sputtering. The amount of nitrogen (= N ₂ flow rate / (Ar flow rate + N ₂ flow rate)) was 10%, and the pressure was 0.08 Pa. Thereafter, the deposition was continued until the sputtering power was 50 W and the film thickness of the IGZO film reached 200 nm. No particular bias voltage was applied to the substrate holder, and it was only water-cooled.

(Example 6)
The IGZO film of Example 6 was basically manufactured in the same manner as the IGZO film of Example 5, but differed in the formation of the prepared target and the IGZO film. For the target material powder, the molar ratio of the prepared material powder was changed, and each material powder was prepared so that the composition of the target was as described in Table 1 below. For film formation, the sputtering pressure was 0.4 Pa.

(Example 7)
The IGZO film of Example 7 was basically manufactured in the same manner as the IGZO film of Example 5, but differed in the formation of the prepared target and the IGZO film. For the target material powder, the molar ratio of the prepared material powder was changed, and each material powder was prepared so that the composition of the target was as described in Table 1 below. For film formation, the sputtering pressure was 3 Pa.

(Example 8)
The IGZO film of Example 8 was basically manufactured in the same manner as the IGZO film of Example 5, but differed in the formation of the prepared target and the IGZO film. For the target material powder, the molar ratio of the prepared material powder was changed, and each material powder was prepared so that the composition of the target was as described in Table 1 below. For film formation, the sputtering pressure was 8 Pa.

(Comparative Example 1)
The IGZO film of Comparative Example 1 was basically produced in the same manner as in Example 1, but differed in that a target obtained by sintering the compact in the atmosphere at 1 atm was used. In Comparative Example 1, since the IGZO film was formed in an atmosphere in which N cannot be taken in using a target that does not contain N, N was not contained in the IGZO film of Comparative Example 1.

(Comparative Example 2)
The IGZO film of Comparative Example 2 was basically manufactured in the same manner as in Example 1, but differed in the prepared target. Specifically, it is as follows.

1. Grinding and mixing of material powders In ₂ O ₃ (purity 99.99%, BET specific surface area 5 m ² / g), Ga ₂ O ₃ (purity 99.99%, BET specific surface area 11 m ² / g), ZnO (purity 99.99%). Each powder of 99%, BET specific surface area 4 m ² / g) and GaN (purity 99.99%, BET specific surface area 2 m ² / g) was pulverized and mixed for 3 hours using a ball mill apparatus. Water was used as the dispersion medium. After pulverization and mixing, the mixture was dried with a spray dryer.

2. Firing (calcination)
Next, the obtained mixed powder was put into an alumina crucible and calcined at 600 ° C. for 5 hours in an air atmosphere to obtain a calcined powder.

3. Molding and Sintering Next, the obtained calcined powder was pressure-molded by uniaxial pressure molding to obtain a disk-shaped molded body having a diameter of 100 mm and a thickness of about 9 mm. The obtained molded body was sintered at 1550 ° C. for 12 hours in an Ar atmosphere of 1 atm to obtain a sintered body. The obtained sintered body contracted to a diameter of 80 mm (thickness was about 7 mm).

4). Preparation of target Next, the obtained sintered body was processed into a diameter of 76.2 mm and a thickness of 5.0 mm to obtain a target of Comparative Example 2.

(Comparative Example 3)
The IGZO film of Comparative Example 3 was basically manufactured in the same manner as Comparative Example 2, but differed in the prepared target. For the target material powder, in order to further mix InN, the molar ratio of the prepared material powder was changed, and each material powder was prepared so that the composition of the target was as described in Table 1 below. As for the sintered and sintered resulting molded body in a N ₂ atmosphere at 6 atm.

(Comparative Example 4)
The IGZO film of Comparative Example 4 was basically manufactured in the same manner as Comparative Example 2, but differed in the prepared target. For the target material powder, the molar ratio of the prepared material powder was changed, and each material powder was prepared so that the composition of the target was as described in Table 1 below. As for the sintered and sintered and the resulting molded body in a N ₂ atmosphere at 1 atm.

(Comparative Example 5)
The IGZO film of Comparative Example 5 was basically manufactured in the same manner as the IGZO film of Comparative Example 2, but differed in the prepared target. For the target material powder, the molar ratio of the prepared material powder was changed, and each material powder was prepared so that the composition of the target was as described in Table 1 below. As for the sintered and sintered and the resulting molded body in NH ₃ and Ar atmosphere of 1 atm.

(Measuring method)
For the sintered bodies and IGZO films of the targets of Examples 1 to 8 and Comparative Examples 1 to 5, X-ray diffraction measurement, composition analysis of In, Ga, and Zn by RBS under the following conditions, and determination of N by SIMS Measurements were performed. The results are shown in Table 1 below.

The RBS conditions are: MCA resolution 2.4 kev / ch, energy resolution 23 keV, incident ion 4 He ⁺⁺ , incident energy 2.3 MeV, incident angle 0 °, sample current 2 nA, incident beam diameter 2 mm, sample rotation 0 °, irradiation dose The measurement was performed at 60 μ / C, chamber vacuum furnace 6.7 × 10 ⁻⁵ , detector scattering angle 160 deg, and aperture diameter 8 mm. SIMS quantified N using a standard piece in which N was ion-implanted into ZnO.

  Moreover, about the IGZO film | membrane of Examples 1-8 and Comparative Examples 1-5, the nodule number was measured with the following method. After the film formation for 60 hours, the target surfaces of Examples 1 to 8 and Comparative Examples 1 to 5 were visually observed using a 5 times magnifier. And the amount of nodules in the 5 cm × 5 cm range was measured, and the number per unit area was converted. The results are shown in Table 1 below.

  Further, the carrier concentration and the electron mobility of the IGZO films of Examples 1 to 8 and Comparative Examples 1 to 5 were measured by the Van der Pau method using a Hall effect measuring machine. The temperature was room temperature, the magnetic field strength was 0.5 T, and the applied voltage was 20 mV. The results are shown in Table 1.

Note that the target of the raw materials in Table 1, describes a material obtained by adding _{In 2 O 3, Ga 2 O} 3, and in addition to ZnO. That is, the target raw materials of Examples 1 to 8 and Comparative Examples 1 to 5 contained In ₂ O ₃ , Ga ₂ O ₃ , and ZnO.

(Measurement result)
As a result of X-ray diffraction measurement, the IGZO films of Examples 1 to 8 and Comparative Examples 1 to 5 were found to be amorphous. For this reason, it turned out that it can be used for the channel layer of TFT, the transparent thin film for transparent electrodes, etc. Moreover, it turned out that the sintered compact of the target of Examples 1-8 and Comparative Examples 1-5 is crystalline.

As shown in Table 1, in the IGZO films of Examples 1 to 8, the nodule generation amount is 4 pieces / cm ² or less, the nodule generation amount can be reduced, and the carrier concentration is 7 × 10 ¹⁵ pieces / cm ² or more. It was 8 × 10 ¹⁸ pieces / cm ² or less. For this reason, it was not insulative and the electron mobility could be improved.

  On the other hand, Comparative Example 1, which had a low In concentration and contained no N, had a large amount of nodule generation and a low electron mobility.

In Comparative Example 2 in which the N concentration was less than 1 × 10 ²⁰ atoms / cc, the amount of nodule generation was suppressed, but the carrier concentration by N was small, so the carrier concentration was too high. The inventor has found that the on / off ratio decreases when the carrier concentration is 8 × 10 ¹⁹ atoms / cm ² or more. For this reason, in Comparative Example 2, the characteristics of the IGZO film deteriorate.

In Comparative Example 3 in which the N concentration exceeded 1 × 10 ²² atoms / cc, although the generation amount of nodules could be suppressed, the carrier concentration was extremely low because the number of trapped carrier electrons by N was too large, and the electron mobility was also extremely low. Judged as an insulator.

  In Comparative Example 4 where the In concentration was low (the ratio was less than 0.30), the amount of nodules generated was large and the carrier concentration was low. For this reason, the electron mobility was low.

  In Comparative Example 5 in which the In concentration was high (the ratio exceeded 0.66), the amount of nodules could be suppressed, but the carrier concentration by N was insufficient and the carrier concentration was high. For this reason, as in Comparative Example 2, the characteristics of the IGZO film of Comparative Example 5 deteriorate.

As described above, according to the present embodiment, the N concentration is 1 × 10 ²⁰ atom / cc or more and 1 × 10 ²² atom / cc or less, and the total concentration of the In concentration, the Ga concentration, and the Zn concentration is It was confirmed that when the In concentration ratio is 0.30 or more and 0.66 or less, the nodules of the semiconductor oxide can be effectively reduced and the characteristics are improved.

  Although the embodiments and examples of the present invention have been described above, it is also planned from the beginning to appropriately combine the features of the embodiments and examples. The embodiments and examples disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above-described embodiment but by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

Claims (1)

An amorphous semiconductor oxide,
Contains indium, gallium, zinc, oxygen and nitrogen,
The concentration of nitrogen is 1 × 10 ²⁰ atoms / cc to 1 × 10 ²² atoms / cc,
A semiconductor oxide, wherein a ratio of the indium concentration to the total concentration of the indium concentration, the gallium concentration, and the zinc concentration is 0.30 or more and 0.66 or less.