JP4650315B2 - Method for forming In-Ga-Zn-O film - Google Patents

Description

  The present invention relates to a method for forming an In—Ga—Zn—O film stably at high speed.

Oxide semiconductors are indispensable materials for realizing electronic and optical devices with new physical properties. For example, TiO ₂ is an n-type oxide semiconductor, and its thin film and particles are used as an optical film utilizing a photocatalyst and a high refractive index. In recent years, a dye-sensitized solar cell using titanium dioxide has attracted attention as an inexpensive and clean solar cell (for example, JP-A-2003-123853).

  In addition, a transparent oxide semiconductor made of In—Ga—Zn—O is also an indispensable material for electronic and optical devices. Recently, it has been shown that an oxide of In—Ga—Zn—O has a large field effect mobility even in an amorphous state, and a field effect transistor (FET) on PET has been successfully manufactured (Nature 2004, Volume 432). 488 pages).

When forming this In—Ga—Zn—O film, a ceramic target is used, and an RF sputtering method in which film formation is performed using an RF power source, or a reactive sputtering in which a metal target is used for sputtering in an oxygen-containing atmosphere. The method is commonly used. The film can also be formed by pulsed laser deposition.
JP 2003-123853 A Nature 2004 432 pages 488

  The conventional method has a slow film formation rate and poor productivity. In addition, stable composition control is difficult, and it is difficult to maintain characteristics.

  For example, in the reactive sputtering method in which sputtering is performed using a metal target in an oxygen-containing atmosphere, the target is coated with an oxide, so the deposition rate is slow and the productivity is poor. In addition, when a large voltage is applied to the oxide-coated target, an arc is generated and a stable discharge cannot be obtained. On the other hand, when an alloy target is used, since the sputtering rate differs for each metal element, the composition of the target and the composition of the resulting film are shifted, and fine composition control is difficult. It is also difficult to control the amount of oxygen in the film. In addition, when the RF sputtering method using a ceramic target is performed, the film formation rate is slow and the productivity is poor.

  An object of the present invention is to solve the above problems and to provide a method for forming an In—Ga—Zn—O film stably at high speed.

  In the In—Ga—Zn—O film formation method of the present invention (Invention 1), an In—Ga—Zn—O film is formed by sputtering using a target in an atmosphere containing oxygen gas. In this method, a plurality of the targets are provided, each target is a metal, alloy, or oxide made of at least one of In, Ga, and Zn, and each of In, Ga, and Zn is the target. It is contained in at least one, and at least one of the targets has a composition different from that of other targets, and sputtering is performed by alternately applying intermittent voltage to each target. It is.

  The method for forming an In—Ga—Zn—O film according to claim 2 is the method according to claim 1, wherein each of the targets is a metal or oxide made of any one of In, Ga, and Zn. It is what.

  The method for forming an In—Ga—Zn—O film according to claim 3 is characterized in that, in claim 1, the target is an alloy containing In, Ga, and Zn and having a composition different from each other. It is.

  The method for forming an In—Ga—Zn—O film according to claim 4 is the method according to claim 1, wherein at least one of the targets is an alloy or oxide made of In and Ga, and the remainder of the target is made of Zn. It is a metal or an oxide.

  The method for forming an In—Ga—Zn—O film according to claim 5 is the method according to any one of claims 1 to 4, wherein a pulse packet including a plurality of pulse voltages is alternately and intermittently applied to each target. It is characterized by.

  The method for forming an In—Ga—Zn—O film according to claim 6 is the charging of the target according to any one of claims 1 to 5, wherein a positive voltage is intermittently applied to each target. It is characterized by preventing.

  The method for forming an In—Ga—Zn—O film according to claim 7 is the method according to any one of claims 1 to 6, wherein the emission wavelength and emission intensity of discharge of In, Ga and Zn during sputtering are monitored. It is characterized by.

  The method for forming an In—Ga—Zn—O film according to claim 8 is the method according to claim 7, wherein the emission wavelength and emission intensity of discharge of In, Ga, and Zn during sputtering are monitored for each target. It is what.

  The method for forming an In—Ga—Zn—O film according to claim 9 is the method according to claim 7 or 8, wherein the pulse power, the pulse amount, the pulse width, and the pressure during film formation are applied to each target based on the monitoring. In addition, the composition and crystallinity of the film to be formed are controlled by changing at least one of the oxygen supply amount.

  The method for forming an In—Ga—Zn—O film according to claim 10 is the method according to any one of claims 1 to 9, wherein the crystallinity of the film to be formed is adjusted by adjusting the temperature of the substrate during sputtering. It is characterized by controlling.

  An In—Ga—Zn—O film forming method according to an eleventh aspect is the method according to the tenth aspect, wherein the substrate temperature is adjusted to 77K to 300K during sputtering.

  In the method for forming an In—Ga—Zn—O film according to claim 1, a plurality of targets are provided, and an intermittent voltage is alternately applied to each target. Stable high-speed film formation can be performed.

  Moreover, since abnormal discharge can be significantly suppressed by using this method, stable long-time discharge is possible, and a high-quality film with little damage can be produced.

  Note that in the case where an In—Ga—Zn—O film is formed by a reactive sputtering method using a single composition target, since the sputtering rate is usually different for each metal element, the target composition and the obtained film composition And fine composition control is difficult.

  In the method of the present invention, sputtering is performed using a plurality of targets having different compositions. Therefore, by adjusting the sputtering amount of the target of each composition and controlling the sputtering ratio of the metal element, In—Ga—Zn having a desired composition. A -O film can be easily formed.

  In the method of forming an In—Ga—Zn—O film according to claim 2, since the amount of sputtering of each metal can be increased or decreased independently, an In—Ga—Zn—O film with a controlled composition is used. Can be formed more easily.

  The film may be formed using a plurality of targets containing In, Ga and Zn and having different compositions from each other (Claim 3), and a target made of an alloy or oxide of In and Ga. The film may be formed using a metal or oxide target made of Zn and Zn.

  In the method of forming an In—Ga—Zn—O film according to claim 5, since a pulse packet is applied to each target, a larger current flows than when a single pulse is applied to each target. And stable high-speed film formation is possible.

  In the method of forming an In—Ga—Zn—O film according to claim 6, by applying a positive voltage intermittently to the target to prevent the target from being charged, a large current can flow through each target. Stable high-speed film formation becomes possible.

  In the In-Ga-Zn-O film forming method according to claim 7, sputtering of In, Ga, and Zn is performed by monitoring the emission wavelength and emission intensity of discharge of In, Ga, and Zn during sputtering. The amount can always be accurately recognized. Therefore, the In—Ga—Zn—O film can be formed accurately and stably by controlling the film formation conditions based on the monitoring result.

  In the method for forming an In—Ga—Zn—O film according to claim 8, since the emission wavelength and emission intensity of discharge of In, Ga, and Zn are monitored for each target using a monitor, The discharge status can be recognized individually.

  In the method for forming an In—Ga—Zn—O film according to claim 9, based on monitoring, the pulse power applied to each target, the pulse amount, the pulse width, the pressure during film formation, and the oxygen supply amount By changing at least one, the composition and crystallinity to be formed can be precisely controlled.

  In particular, when the supply amount of oxygen becomes excessive, the surface of the target is completely oxidized, and the film formation rate becomes very slow. On the other hand, if the amount of oxygen introduced is too small, the target surface is not oxidized and film formation is performed. As a result, the amount of oxygen during film formation is insufficient. However, as described above, since the oxygen supply amount is controlled based on the monitoring, an appropriate amount of oxygen can be introduced based on the density of In, Ga, and Zn in the plasma. As a result, sputtering can be performed in the “transition region” which is an intermediate region between the two oxygen supply amount regions. As a result, a film containing an appropriate amount of oxygen can be formed at high speed.

  The crystallinity of the In—Ga—Zn—O film can be controlled by adjusting the substrate during sputtering as in the tenth aspect.

  When the temperature of the substrate during sputtering is adjusted to 77K to 300K as in claim 11, the agglomeration energy of sputtered particles reaching the surface of the In-Ga-Zn-O film is reduced, and the uniformity of the film and the film The surface flatness can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic diagram for explaining a method of forming an In—Ga—Zn—O film according to an embodiment by a dual cathode magnetron sputtering method, and FIG. 2 shows an example of a voltage applied to the target electrode of FIG. FIG.

  As shown in FIG. 1, a first sputtering unit is composed of a target electrode 20A provided with a first target 21a on a support 20a and a magnet 22a disposed below the target electrode 20A. In addition, a second sputtering unit is configured by a target electrode 20B provided with a second target 21b on a support 20b and a magnet 22b disposed below the target electrode 20B. The first sputtering unit and the second sputtering unit are installed adjacent to each other, and an AC power supply 25 is connected to these sputtering units via a switching unit 24. In the present embodiment, the first target 21a is made of an In—Ga oxide, and the second target 21b is made of ZnO. In addition, since each target is not completely oxidized, conductivity is sufficiently ensured.

  These target electrodes 20A and 20B are covered with a cover 26. The cover 26 is connected to a pump (not shown) via an exhaust port 28 and is connected to a gas supply source (not shown) via a gas introduction port 27.

  Collimators 30a and 30b are provided in the cover 26, and these collimators 30a and 30b are respectively connected to plasma emission monitors (hereinafter also referred to as PEMs) 31a and 31b through a filter and a photomultiplier tube (not shown). It is connected to the. The collimators 30a and 30b, the filters, the light amplification amplifiers, and the PEMs 31a and 31b constitute first and second monitors.

  The PEM is an apparatus that monitors an electrical signal obtained by condensing plasma emission with a collimator and photoelectrically converting it with a photomultiplier tube (PM). The PEM is set to a certain sensitivity and monitors the emission intensity of the plasma.

  As the filter for the target 21a, a filter capable of selectively passing at least wavelengths of 230.6 nm and 209.1 nm of the emission spectra of In and Ga is used. As the filter for the target 21b, a filter that can selectively pass at least wavelengths 202.5 nm, 213 nm, and 334 nm of the emission spectrum of Zn is used.

  When forming an In—Ga—Zn—O film using the above apparatus, first, the substrate 1 is disposed above the targets 21a and 21b in the cover 26, and the inside of the cover 26 is evacuated by a pump. A mixed gas containing oxygen in an inert gas such as argon is introduced into the cover 26, and the inside of the cover 26 is brought to a predetermined pressure.

  As the substrate 1, for example, glass such as alkali silicate glass, non-alkali glass, and quartz glass can be used. Various plastic substrates such as acrylic can also be used. A polymer film substrate such as PET can also be used. The thickness of the substrate is generally 0.1 to 10 mm, preferably 0.3 to 5 mm. The glass plate is preferably chemically or thermally strengthened.

  Next, for example, as shown in FIG. 2, a pulse packet voltage is alternately applied to the target electrodes 20A and 20B to form a glow discharge. As a result, particles are sputtered from the targets 21a and 21b, and these particles adhere to the substrate 1 above the targets 21a and 21b. At this time, the targets 21a and 21b or the sputtered particles are oxidized by oxygen gas.

  The emission wavelengths and emission intensities of the discharges of In, Ga, and Zn during sputtering of the targets 21a and 21b become electric signals via the collimators 30a and 30b, the filters, and the optical amplification tubes, and are detected by the PEMs 31a and 31b. From these electric signals, the sputtering speed of the first target 21a and the sputtering speed of the second target 21b are calculated. Based on the calculation result, the pulse power applied to each of the targets 21a and 21b, the pulse amount and the pulse width, the oxygen amount introduced into the cover 26, and the pressure in the cover are controlled.

  The pulse power, the pulse amount, and the pulse width vary depending on the volume of the target, the volume in the cover 26, the required film formation speed, and the like. For example, the pulse power is 1 kW to 20 kW, the pulse amount is 5% to 50%, the pulse The width is controlled within a range of 0.1 to 500 msec. If the pulse power is 50 kW or more, abnormal discharge occurs, and an N-doped ZnO film whose composition is precisely controlled cannot be stably formed. On the other hand, if the pulse power is 500 W or less, the film formation speed Becomes slower. When the pulse amount is 90% or more, continuous discharge occurs, whereas when the pulse amount is 1% or less, the film formation rate becomes slow.

  The oxygen supply amount is, for example, about 1 to 50 sccm. If the amount of oxygen introduced is excessive, the surfaces of the targets 21a and 21b are completely oxidized, and the film formation rate becomes very slow. Such a region where the amount of introduced oxygen is excessive is referred to as a “reactive sputtering region”. On the other hand, if the amount of oxygen introduced is too small, the target surface is not oxidized and film formation is performed. As a result, the amount of oxygen during film formation is insufficient. Such a region is referred to as a “metallic sputter region”. In the present embodiment, an appropriate amount of oxygen is introduced based on the density of In, Ga, and Zn in the plasma by the above control.

  The pressure in the cover 26 during the film formation is preferably controlled within a range of 0.01 to 30 Pa, particularly 0.1 to 10 Pa.

  After the In—Ga—Zn—O film formed on the substrate 1 has reached a predetermined thickness, sputtering is terminated, and the substrate is laminated with the In—Ga—Zn—O film at atmospheric pressure in the cover 20. Take 1 out.

  As the thickness of the In—Ga—Zn—O film, for example, a film with a thickness of about 5 μm to 5 μm can be formed.

  In the In—Ga—Zn—O film forming method according to the present embodiment, since intermittent voltages are alternately applied to the targets 21a and 21b, a large current is allowed to flow through the targets and stable high speed is achieved. A film can be formed. As described above, by performing such high-speed film formation, new metal particles can fly and cover the surface before the oxidation reaction takes place preferentially on the sample surface, so that it is adsorbed on the sample surface. Oxygen can be taken into the film, and the In—Ga—Zn—O film can be formed with high speed and reliability. Further, since abnormal discharge can be significantly suppressed by using this method, stable long-time discharge is possible, and a high-quality film with little damage can be produced.

  In addition, a single pulse may be applied to each target 21a, 21b, but as shown in FIG. 2, a single pulse is applied to each target 21a, 21b by applying a pulse packet to each target 21a, 21b. A larger current can be flowed than when the voltage is applied, and stable high-speed film formation is possible.

In this embodiment, by monitoring the emission wavelength and emission intensity of discharge of In, Ga and Zn during sputtering with a monitor, the amount of sputtering of In, Ga and Zn can always be accurately recognized. it can. Therefore, by controlling the deposition conditions based on the monitoring result, an In—Ga—Zn—O film with a controlled composition can be deposited accurately and stably.
In addition, when the ratio of In and Ga in the obtained film was different from the desired one, the composition was controlled by using a suitable InGa content ratio as the first target. An In—Ga—Zn—O film can be formed accurately and stably.

  In the present embodiment, the same number (two) of monitors as the targets 21a and 21b are provided, and monitors corresponding to the emission wavelengths and emission intensities of the discharges of In, Ga and Zn in the targets 21a and 21b are used. Therefore, the discharge status of each target 21a, 21b can be individually recognized.

  In the present embodiment, the composition and crystallinity of the film formed by changing the pulse power, the pulse amount, the pulse width, and the pressure during film formation applied to each target 21a, 21b based on monitoring. Can be precisely controlled.

  In the present embodiment, the oxygen supply amount can be precisely controlled by controlling the oxygen supply amount based on monitoring. Therefore, it is possible to stably supply an In—Ga—Zn—O film whose oxidation number is precisely controlled. Further, by supplying an appropriate amount of oxygen, sputtering in the “transition region” becomes possible, and as a result, a film containing an appropriate amount of oxygen can be formed at a high speed.

  Further, in the case where an In—Ga—Zn—O film is formed by oxygen supply control using a conventional flow meter, it is difficult to stably control the oxidation number of the In—Ga—Zn—O film. This is because, for example, the deposition rate changes as the target wears out, and the sputtering conditions including the oxygen flow rate during deposition change. In the present embodiment, the emission wavelengths and light emission amounts of In, Ga and Zn in the first and second targets 21a and 21b are monitored during film formation, and introduced into the chamber from the densities of In, Ga and Zn in the plasma. Since Plasma Emission Monitor Control (PEM control) for controlling the amount of oxygen to be used is used, an In—Ga—Zn—O film in which the oxidation number is controlled can be stably formed.

  The above embodiment is an example of the present invention, and the present invention is not limited to the above embodiment. For example, a negative voltage is normally applied to the target, but charging of the target may be prevented by applying a positive voltage intermittently to the target. In this case, since the charge accumulated in the target due to the negative voltage is eliminated by the positive voltage, formation of an insulating film such as an oxide on the edge of the target during sputtering can be suppressed. Thereby, a large current can be passed through each target, and stable high-speed film formation is possible.

Further, the crystallinity of the In—Ga—Zn—O film may be controlled by adjusting the temperature of the substrate during sputtering.
In particular, the substrate temperature during sputtering may be adjusted to 77 K to 300 K. In this case, the cohesive energy of sputtered particles reaching the surface of the In—Ga—Zn—O film is reduced, and the film uniformity and film thickness are reduced. The surface flatness of the film can be improved.

  In the above embodiment, the bipolar dual magnetron sputtering method in which the common switching unit 24 is installed in the two sputtering units is used. However, the unipolar dual magnetron sputtering method in which the switching unit is individually installed in each sputtering unit is used. Also good.

  In the above embodiment, the first target made of In—Ga oxide and the second target made of Zn oxide are used. However, the present invention is not limited to this. For example, the first target made of In and A second target made of Ga and a third target made of Zn may be used. In this case, since the sputtering amount of each metal can be individually adjusted by changing any one of the pulse power, the pulse amount, and the pulse width of each target, the composition control of the In—Ga—Zn—O film is controlled. Is easy. Alternatively, a first target made of In oxide, a second target made of Ga oxide, and a third target made of Zn oxide may be used. Also in this case, since the sputtering amount of each metal can be individually adjusted by changing any of the pulse power, the pulse amount, and the pulse width of each target, the composition of the In—Ga—Zn—O film can be adjusted. Easy to control. Furthermore, a first target made of an In—Ga alloy and a second target made of Zn may be used.

  A plurality of In—Ga—Zn oxides having different compositions may be used as a target. For example, an oxide having a larger In content ratio than the content ratio of In, Ga, and Zn in the desired In—Ga—Zn—O film is used as the first target, and the desired In— An oxide having a larger Ga content ratio than the In, Ga, and Zn content ratio in the Ga—Zn—O film is used, and the In, Ga in the desired In—Ga—Zn—O film is used as the third target. Alternatively, an oxide having a larger Zn content ratio than the Zn content ratio may be used. Also in this case, since the sputtering amount of each metal can be adjusted by changing any one of the pulse power, the pulse amount, and the pulse width of each target, the composition of the In—Ga—Zn—O film can be controlled. Easy.

  Further, a plurality of In—Ga—Zn alloys having different compositions may be used as a target. For example, an alloy having a larger In content ratio than the In, Ga, and Zn content ratio in the desired In—Ga—Zn—O film is used as the first target, and the desired In—Ga is used as the second target. An alloy having a larger Ga content ratio than the In, Ga, and Zn content ratio in the —Zn—O film is used, and the In, Ga, and Zn in the desired In—Ga—Zn—O film are used as the third target. An alloy having a large Zn content ratio may be used as compared with the above content ratio. Also in this case, since the sputtering amount of each metal can be adjusted by changing any one of the pulse power, the pulse amount, and the pulse width of each target, the composition of the In—Ga—Zn—O film can be controlled. Easy.

  Hereinafter, although Examples 1-6 and Comparative Examples 1-4 are demonstrated, this invention is not limited to Examples 1-6.

<Example 1>
Film formation was performed using the apparatus of FIG. An In—Ga target (100 mmφ × 5 mm thickness) made of In50 atm% and Ga 50 atm% was used as the first target, and a Zn target (100 mmφ × thickness 5 mm) was used as the second target. Corning 7059 alkali-free glass (length 80 mm × width 25 mm × thickness 1.1 mm) was used for the substrate. In addition, each target is sufficiently cooled by cooling water passed through a chiller.

First, the substrate was introduced into the cover, the inside of the cover was evacuated to 5.0 × 10 ⁻⁴ Pa or less by a pump, and then a mixed gas composed of 80 sccm of argon and 20 sccm of oxygen was introduced into the cover 26. Then, an In—Ga—Zn—O film was formed by alternately applying a pulsed voltage to each target electrode.

  The pulse frequency was 50 Hz, the applied power was about 1 kW × 2 target, and the duty ratio of the pulse was Zn: InGa = 50: 50. The pressure during film formation was 0.7 Pa.

  The thickness of the obtained film was measured using Dektak 6M manufactured by Veeco, and the film formation rate at the time of film formation was calculated to be 62.6 nm / min. Moreover, when XRD crystal structure analysis was performed about the obtained film | membrane, it was confirmed that it is an amorphous state.

Composition analysis by EDX revealed that the obtained film composition was In: Ga: Zn = 1.1: 1.0: 0.9.
When the laxness factor of the surface of the film obtained using Dektak 6M was measured, it was 6.2 nm.

<Example 2>
Based on the result of Example 1, an In—Ga—Zn—O film was prepared in the same manner as in Example 1 except that the pulse duty ratio was changed to Zn: InGa = 53: 47, and composition analysis was performed by EDX. It was. As a result, the obtained film composition was In: Ga: Zn = 1.1: 1.0: 1.0.

<Comparative example 1>
Example 1 except that only one In—Ga—Zn alloy target (composition ratio: In: Ga: Zn = 1: 1: 1 (atm%)) was used and DC 200 W was applied to the target. A sample was prepared, the film thickness was measured in the same manner as in Example 1, and the film formation rate was calculated. As a result, the film formation rate was 8.7 nm / min, which was extremely slow.

<Comparative example 2>
A sample was prepared in the same manner as in Comparative Example 1 except that DC 300 W or more was applied to the target. The state of discharge during film formation became extremely unstable.

<Example 3>
A sample was produced in the same manner as in Example 1 except that the substrate temperature during film formation was adjusted to 223 K (−50 ° C.). It was 65.1 nm / min when the film-forming speed | rate was computed using the film thickness measurement similarly to Example 1. FIG.

  Moreover, when XRD crystal structure analysis was performed about the obtained film | membrane, it was confirmed that it is an amorphous state.

Composition analysis by EDX revealed that the obtained film composition was In: Ga: Zn = 1.1: 1.0: 0.9.
When the laxness factor of the surface of the film obtained by Dektak 6M was measured, it was 5.9 nm.

<Example 4>
Film formation was performed using the apparatus of FIG. An InGaO _3-x (In: Ga: O = 1: 1: 3-x) target (100 mmφ × 5 mm thickness) is used as the _first target, and ZnO _1-X (Zn: O =) is used as the second target. 1: 1-x) A target (100 mmφ × thickness 5 mm) was used. Corning 7059 alkali-free glass (length 80 mm × width 25 mm × thickness 1.1 mm) was used for the substrate.

First, the substrate was introduced into the cover, the inside of the cover was evacuated to 5.0 × 10 ⁻⁴ Pa or less by a pump, and then a mixed gas composed of 80 sccm of argon and 20 sccm of oxygen was introduced into the cover 26. Then, an In—Ga—Zn—O film was formed by alternately applying a pulsed voltage to each target electrode.

  The pulse frequency was 50 Hz, the applied power was about 1 kW × 2 target, and the duty ratio of the pulse was Zn oxide: InGa oxide = 50: 50. The pressure during film formation was 0.7 Pa.

  The thickness of the obtained film was measured using Dektak 6M manufactured by Veeco, and the film formation rate at the time of film formation was calculated to be 25.7 nm / min. Moreover, when XRD crystal structure analysis was performed about the obtained film | membrane, it was confirmed that it is an amorphous state.

Composition analysis by EDX revealed that the obtained film composition was In: Ga: Zn = 1.1: 1.0: 0.9.
When the laxness factor of the surface of the film obtained using Dektak 6M was measured, it was 5.2 nm.

<Example 5>
Based on the result of Example 4, an In—Ga—Zn—O film was prepared in the same manner as in Example 4 except that the duty ratio of the pulse was changed to Zn oxide: InGa oxide = 53: 47. A compositional analysis was performed. As a result, the obtained film composition was In: Ga: Zn = 1.1: 1.0: 1.0.

<Comparative Example 3>
In addition to using only one In—Ga—Zn oxide target (composition ratio: In: Ga: Zn: O = 1: 1: 1: 4-x (atm%)) and applying DC 200 W to the target Prepared a sample in the same manner as in Example 4, measured the film thickness in the same manner as in Example 4, and calculated the deposition rate. As a result, the film formation rate was 3.2 nm / min, which was extremely slow.

<Comparative example 4>
A sample was prepared in the same manner as Comparative Example 3 except that DC 300 W or more was applied to the target. The state of discharge during film formation became extremely unstable.

<Example 6>
A sample was produced in the same manner as in Example 4 except that the substrate temperature during film formation was adjusted to 223 k (−50 ° C.). It was 24.1 nm / min when the film-forming speed | rate was computed using the film thickness measurement similarly to Example 4. FIG.

  Moreover, when XRD crystal structure analysis was performed about the obtained film | membrane, it was confirmed that it is an amorphous state.

Composition analysis by EDX revealed that the obtained film composition was In: Ga: Zn = 1.1: 1.0: 0.9.
When the laxness factor of the surface of the film obtained by Dektak 6M was measured, it was 4.3 nm.

It is the schematic for demonstrating the dual cathode system magnetron sputtering method. It is a figure explaining an example of the voltage applied to the target electrode of FIG.

Explanation of symbols

1 Substrate 20a, 20b Support 20A, 20B Target electrode 21a, 21b Target 22a, 22b Magnet 24 Switching unit 25 AC power supply 26 Cover 27 Gas inlet 28 Exhaust outlet 30a, 30b Collimator 31a, 31b PEM

Claims (11)

In a method for forming an In—Ga—Zn—O film by sputtering using a target in an atmosphere containing oxygen gas,
A plurality of the targets are provided,
Each target is a metal or alloy or oxide composed of at least one of In, Ga and Zn, and each of In, Ga and Zn is contained in at least one of the targets,
At least one of the targets has a composition different from other targets,
A method for forming an In—Ga—Zn—O film, wherein sputtering is performed by alternately applying intermittent voltages to each target.   2. The method for forming an In—Ga—Zn—O film according to claim 1, wherein each of the targets is a metal or an oxide of any one of In, Ga, and Zn.   The method for forming an In—Ga—Zn—O film according to claim 1, wherein the target is an alloy containing In, Ga, and Zn and having different compositions.   2. The In—Ga—Zn—O according to claim 1, wherein at least one of the targets is an alloy or oxide made of In and Ga, and the remainder of the target is a metal or oxide made of Zn. A film forming method.   5. The method for forming an In—Ga—Zn—O film according to claim 1, wherein a pulse packet including a plurality of pulse voltages is alternately and intermittently applied to each target.   6. The formation of an In—Ga—Zn—O film according to claim 1, wherein charging of the target is prevented by intermittently applying a positive voltage to each target. Membrane method.   7. The method for forming an In—Ga—Zn—O film according to claim 1, wherein the emission wavelength and emission intensity of discharge of In, Ga, and Zn during sputtering are monitored.   8. The method of forming an In—Ga—Zn—O film according to claim 7, wherein the emission wavelength and emission intensity of discharge of In, Ga, and Zn during sputtering are monitored for each target.   9. The film is formed by changing at least one of a pulse power, a pulse amount, a pulse width, a pressure during film formation, and an oxygen supply amount applied to each target based on the monitoring according to claim 7 or 8. A method for forming an In—Ga—Zn—O film, wherein the composition and crystallinity of the film are controlled.   10. The film formation of an In—Ga—Zn—O film according to claim 1, wherein the crystallinity of the film to be formed is controlled by adjusting the temperature of the substrate during sputtering. Method.   The method for forming an In—Ga—Zn—O film according to claim 10, wherein the temperature of the substrate is adjusted to 77 K to 300 K during sputtering.

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