KR20130079348A - Deposition method - Google Patents

Abstract

A film forming method comprising sputtering a target made of a metal oxide in a gas atmosphere containing a rare gas atom and a water molecule and having a content of the water molecule in a partial pressure ratio of 0.1 to 10% relative to the rare gas atom to form a thin film on the substrate. .

Description

Deposition Method {DEPOSITION METHOD}

The present invention relates to a film forming method.

BACKGROUND Field effect transistors are widely used as unit electronic devices, high frequency signal amplification devices, liquid crystal drive devices, and the like in semiconductor memory integrated circuits, and are currently the most practically used electronic devices. Among them, with the recent development of display devices, not only liquid crystal display devices (LCDs) but also various display devices such as electroluminescent display devices (EL) and field emission displays (FED), driving voltages are applied to display elements. As a switching element for driving a display device, a thin film transistor (TFT) is frequently used.

In the liquid crystal driving transistor of a large liquid crystal display device, an amorphous silicon-based semiconductor thin film is conventionally used. By the way, in recent years, in accordance with the demand of further enlargement and high-definition, since the mobility is lacking in amorphous silicon, image writing has become insufficient. In addition, the enlargement technology is progressing also regarding organic electroluminescent (organic EL) display, and the large, uniform, and high mobility material also has been requested | required so far about the backplane.

Therefore, a large area can be made like an amorphous silicon semiconductor thin film, and a transparent semiconductor thin film made of a metal oxide as a material having high mobility after crystalline silicon, in particular, an oxide semiconductor thin film made of indium oxide, zinc oxide, and gallium oxide is noted. have.

Conventionally, since the oxide semiconductor film used for a TFT active layer controls the electrical property of a film, it is common to form into a film in the atmosphere which introduce | transduced oxygen gas. However, due to slight vibration of the oxygen partial pressure, there is a problem that the carrier concentration in the film is greatly changed, and the semiconductor characteristics are changed.

As a means of solving this problem, it is known to make the oxygen partial pressure dependence of the carrier concentration in a film | membrane moderate by making the power density at the time of sputter film deposition high (patent document 1).

However, when the power density is increased, the deposition rate is increased and the oxygen supply rate is relatively slow, so that the carrier concentration in the film becomes approximately 10 ¹⁸ cm ^-3 or more, and when the TFT is used, good characteristics cannot be obtained. There was a problem of not going.

In order to solve the said problem, it is necessary to make carrier concentration into 10 ¹⁸ cm <^-3> or less, but for that purpose, oxygen partial pressure must be made high. When the oxygen partial pressure is increased, the film formation speed is slowed, and there is another problem that productivity is worsened. Therefore, it was difficult to manufacture a favorable thin film transistor using an oxide semiconductor in a state where the power density at the time of sputter film formation was made high and the film formation speed was increased.

Patent document 2 discloses a top-gate thin film transistor having a thickness of 45 nm of a channel layer using a semiconductor film having an atomic ratio In: Ga: Zn = 0.98: 1.02: 4 formed by introducing a partial pressure of water vapor. do. In addition, Patent Document 3 discloses an amorphous oxide semiconductor containing at least one element of In, Zn, and hydrogen.

However, any of these techniques is applied to targets of 4 inches or less, and there is room for improvement in terms of high-speed film formation considering the actual production.

Non-Patent Literature 3 forms a semiconductor film having an atomic ratio In: Ga: Zn = 1.3: 1.3: 1.0 at a steam partial pressure of 10 ⁻² Pa or more to form a bottom-gate structure having a film thickness of 30 nm. A thin film transistor having a bottom-contact configuration is disclosed.

However, the thin film transistor formed by introducing a vapor partial pressure has a lower electric field mobility than that at the time of oxygen introduction at a level of about 3 cm ² / Vs, and is insufficient for use in a large-area, high-definition display device.

In addition to the above problems, the size of the substrate in the manufacture of flat panel displays such as liquid crystal displays is increasing year by year due to the increase in the size of the display and the competition for severe cost reduction. It is becoming. However, when the substrate size is increased, it is difficult to uniformly form the film thickness and film quality of the channel layer (semiconductor layer), and there is another problem that the gap between the properties resulting from the film thickness and film quality nonuniformity is increased.

For example, if the film thickness of the channel layer is made thick, the film thickness and film quality uniformity are improved, but in the oxide semiconductor represented by IGZO, the threshold voltage in which the mobility decreases as the film thickness becomes thick is decreased in the negative direction. There existed a problem of becoming large (nonpatent literature 1). In particular, when producing a channel-etched transistor having a low manufacturing cost, the channel layer (semiconductor layer) is exposed to the etching solution, so the problem of non-uniformity when the substrate is enlarged is remarkable (Non Patent Literature 2).

Therefore, in the thin film transistor using an oxide semiconductor, the channel layer is usually manufactured with a thin film thickness of 50 nm or less (nonpatent literature 3), and the thick film of a channel layer is thick (for example, 50 nm or more, Furthermore, 60 nm or more) , 70 nm or more), a thin film transistor having excellent characteristics such as mobility, threshold voltage, and the like has been required.

In patent documents 4 and 5, the manufacturing example of large area ITO is disclosed using an AC sputtering apparatus. However, in the case of an oxide semiconductor, control of oxygen vacancies is more important, and it is unclear how the carrier concentration of the semiconductor will affect power and frequency.

International Publication No. 2009/084537 pamphlet Japanese Patent Publication No. 2007-73697 Japanese Patent Publication No. 2010-80936 Japanese Patent Publication No. 2005-290550 Japanese Patent Publication No. 2007-031816

Kyoung-Seok et al., SID 08 DIGEST, p 633 Je-hun Lee et al., SID 08 DIGEST, p 625 Takafumi Aoi et al., Thin Solid Films 518 (2010)

An object of the present invention is to provide a method for forming an oxide semiconductor film which does not lower the film formation speed even when the power density at the time of sputter film formation is high, and suppresses the carrier concentration in the film to 10 ¹⁸ cm ^-3 or less.

Another object of the present invention is to provide a thin film transistor having good transistor characteristics such as mobility, even when the channel layer (semiconductor layer) is thick.

The present inventors have intensively studied a result, by appropriately introducing the water vapor instead of introducing oxygen at the time of sputtering deposition, sputtering in a high power density of state at the time of film formation without decreasing the film forming rate, the carrier concentration of 10 ¹⁸ in the film It was found that it can be less than ^-3 cm.

Moreover, by using the said film-forming method, the manufacturing method of the semiconductor film which was stable without manufacturing time being extended was discovered.

According to this invention, the following film-forming methods etc. are provided.

1. A thin film is formed on a substrate by sputtering a target made of a metal oxide in an atmosphere of a gas containing a rare gas atom and water molecules, wherein the content of the water molecule is 0.1 to 10% in a partial pressure ratio relative to the rare gas atom. The deposition method.

2. The film forming method according to 1, wherein the pressure of the gas is 0.1 to 5.0 Pa.

3. The film forming method according to 1 or 2, wherein the sputtering is a direct current sputter.

4. The film forming method according to 1 or 2, wherein the sputtering is an alternating current sputter.

5. The film forming method according to 3, wherein the DC power density is 1 to 5 W / cm ² .

6. In 4, the substrate is sequentially transported to a position facing the three or more targets placed side by side at a predetermined interval in the vacuum chamber,

A film forming method for forming a thin film on the surface of the substrate by generating a plasma on the target by applying a negative potential and a positive potential alternately from the AC power source to each target,

The film forming method is performed while switching at least one of the outputs from the AC power source while switching a target for applying a potential between two or more targets connected by branching.

7. The film forming method according to 4 or 6, wherein the AC power density is 5 to 20 W / cm ² .

8. The film forming method according to any one of 4, 6 and 7, wherein the frequency of the AC power supply is 10 kHz to 1 MHz.

9. The film forming method according to any one of 1 to 8, wherein the film forming speed in the direction perpendicular to the film forming surface of the substrate is 1 to 100 nm / min.

10. The film forming method according to any one of 1 to 9, wherein the distance between the target and the substrate is 1 to 15 cm in a direction perpendicular to the film forming surface of the substrate.

11. The film forming method according to any one of 1 to 10, wherein the magnetic field strength of the atmosphere is 300 to 1000 gauss.

12. The metal oxide according to any one of 1 to 11, which contains at least one element selected from the group consisting of gallium element (Ga), zinc element (Zn) and tin element (Sn), and indium element (In). and,

The film-forming method in which content of the indium element in a target satisfy | fills the following atomic ratio.

0.2 ≤ [In] / total metal atoms ≤ 0.8

(In the above formula, [In] is the number of atoms of the indium element in the target.

The total metal atom is the number of atoms of all metal atoms included in the target.)

13. The metal oxide according to any one of 1 to 11, wherein the metal oxide contains indium element (In), gallium element (Ga) and zinc element (Zn),

 The film-forming method in which content of an indium element, a gallium element, and a zinc element in a target satisfy | fills the following atomic ratio.

0 <[In] / [Ga] <0.5

0.2 <[In] / ([In] + [Ga] + [Zn]) <0.9

(In the above formula, [In] is the number of atoms of the indium element in the target, [Ga] is the number of atoms of the gallium element in the target, and [Zn] is the number of atoms of the zinc element in the target.)

14. The metal oxide according to any one of 1 to 11, wherein the metal oxide contains indium element (In), tin element (Sn) and zinc element (Zn),

The film-forming method in which content of the indium element, tin element, and zinc element in a target satisfy | fills the following atomic ratio.

0.2 <[In] / ([In] + [Sn] + [Zn]) <0.9

0 <[Sn] / ([In] + [Sn] + [Zn]) <0.5

(In the above formula, [In] is the number of atoms of the indium element in the target, [Sn] is the number of atoms of the tin element in the target, and [Zn] is the number of atoms of the zinc element in the target.)

15. The manufacturing method of the oxide semiconductor thin film which carries out the annealing process of the thin film obtained by the film-forming method in any one of 1-14 at 150-400 degreeC for 5 to 120 minutes.

16. The method for producing an oxide semiconductor thin film according to 16., wherein the annealing treatment is performed in an atmosphere containing at least oxygen.

The field effect type thin film transistor element provided with the oxide semiconductor thin film obtained by the manufacturing method of the thin film of 17.15 or 16.

18. The field effect type thin film transistor device according to 18., wherein the oxide semiconductor thin film is a channel layer.

19. The field effect type thin film transistor element according to 17 or 18, having a mobility of 10 cm ² / Vs or more and a threshold voltage of -5 to 5V.

According to the present invention, there can be provided a method for forming an oxide semiconductor film which does not lower the film formation speed even when the power density at the time of sputter film formation is high and also suppresses the carrier concentration in the film to 10 ¹⁸ cm ^-3 or less.

Moreover, according to this invention, even if the film thickness of a channel layer (semiconductor layer) is thick, a thin film transistor with favorable transistor characteristics, such as mobility, can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the important part of an example of a sputter apparatus.
2 is a schematic cross-sectional view showing an embodiment of a thin film transistor including the oxide semiconductor of the present invention.
3 is a schematic cross-sectional view according to another embodiment of a thin film transistor including an oxide semiconductor of the present invention.
It is a figure which shows the relationship of the carrier concentration of the thin film obtained by oxygen concentration or hydrogen concentration.

According to the film forming method of the present invention, a thin film is formed on a substrate by sputtering a target made of a metal oxide in a gas atmosphere containing rare gas atoms and water molecules, and the content of water molecules is 0.1 to 10% by partial pressure ratio with respect to the rare gas atoms. We form.

On the other hand, is represented by partial _{Sembilan, [H 2 O] / (} [H 2 O] + [ noble gas atoms) for the inert gas atoms of the water molecule, and [H ₂ O] is the partial pressure of the water molecules in the gas atmosphere, [ Rare gas atom] is the partial pressure of the rare gas atom in the gas atmosphere.

Using the film formation method of the present invention, by introducing small amounts of water molecules, OH groups are taken in into the film, and generation of oxygen deficiency (carrier generation) can be more efficiently avoided than when oxygen is introduced and formed into a film. In addition, since the amount of water molecules to be introduced is small, the semiconductor film can be formed, for example, without reducing the sputtering rate.

The gas atmosphere during sputtering contains rare gas atoms and water molecules, and the content of water molecules is 0.1 to 10% in a partial pressure ratio with respect to the rare gas atoms, preferably 0.5 to 7%, more preferably 1.0 to 5%, Especially preferably, it is 1.0 to 3.0%.

As for the partial pressure of water at the time of sputtering, 5x10 <^{-3> -5} * 10 <^-1> Pa is preferable. In the case of less than 5 × 10 ^-3 Pa, since the amount of OH groups taken in in the film decreases, the degree of oxidation of the thin film is insufficient and the carrier concentration tends to increase. When it exceeds 5x10 <^-1> Pa, since a large amount of OH groups are taken in in a film | membrane, oxidation will be accelerated | stimulated and carrier concentration and mobility will become low. Therefore, when using a TFT element, there exists a possibility that the field effect mobility may become lower than a desired value.

The optimum water partial pressure is changed depending on various sputtering conditions such as power density of discharge and TS distance. For example, when the power density of the discharge is 2.5W / cm ² , the water partial pressure is preferably 3 × 10 ⁻³ Pa to 1.5 × 10 ⁻² Pa, and when the power density of the discharge is 5.0W / cm ² The water partial pressure is preferably 1 × 10 ⁻² Pa to 1 × 10 ⁻¹ Pa, and when the power density of the discharge is 7.4 W / cm ² , the water partial pressure is preferably 2.0 × 10 ⁻² Pa to 3.5 It is a range of ^x10-2 Pa. Carrier concentration of the thin film obtained by making water partial pressure into these ranges can be set to 10 <^17> cm <^-3> second half, and when it is set as TFT element, the high field effect mobility of 10 cm <^2> / Vs or more can be obtained.

When the content of water molecules is less than 0.1% in the partial pressure ratio with respect to the rare gas atom, since the OH group is not sufficiently taken in in the membrane, the effect of suppressing the generation of oxygen vacancies is not obtained and there is a possibility that the carrier concentration in the membrane cannot be sufficiently reduced. On the other hand, when the content of the water molecules is more than 10% in the partial pressure ratio with respect to the rare gas atom, the OH group is excessively picked up in the film and excessively oxidized, so that the carrier concentration and the mobility are lowered, and thus the mobility of the TFT device obtained is lowered. There is a concern.

On the other hand, the rare gas atom is not particularly limited, but is preferably an argon atom. In addition to the rare gas atoms and water, oxygen and nitrogen may be included in a range that does not affect the TFT element.

The pressure (sputter pressure) of the gas atmosphere is not particularly limited as long as the plasma can be stably discharged, but is preferably 0.1 to 5.0 Pa.

In addition, sputter | spatter pressure means the voltage in the system at the time of sputter | spatter start after argon, water, oxygen, etc. are introduce | transduced.

The deposition rate of sputtering is usually 1 to 250 nm, preferably 1 to 100 nm / min, more preferably 10 to 80 nm / min, particularly preferably 30 to 60 nm / in the direction perpendicular to the deposition surface of the substrate. min.

If the film formation speed is less than 1 nm / min, the film formation speed is slow, so there is a fear that the productivity is poor. On the other hand, when the film formation rate is more than 250 nm / min, the film formation rate is too fast, the controllability of the film thickness is deteriorated, and there is a possibility that OH groups are not uniformly drawn in the film, thereby deteriorating in-plane uniformity of characteristics. In addition, when the film formation rate is too fast, since OH groups are not sufficiently taken in in the film, there is a possibility that excessive introduction of water molecules is necessary during sputter film formation.

The distance between the target and the substrate is preferably 1 to 15 cm, more preferably 5 to 15 cm, still more preferably 4 to 8 cm in the direction perpendicular to the film formation surface of the substrate.

When this distance is less than 1 cm, the kinetic energy of the particles of the target constituent element that reaches the substrate increases, and there is a fear that good film properties cannot be obtained, and there is a fear that in-plane distribution of film thickness and electrical properties occurs. On the other hand, when the distance between a target and a board | substrate exceeds 15 cm, the kinetic energy of the particle | grains of the target structural element which reaches | attains a board | substrate becomes too small, a dense film | membrane cannot be obtained and a favorable film | membrane characteristic may not be obtained.

It is preferable to sputter under an atmosphere having a magnetic field strength of 300 to 1000 gauss.

If the magnetic field strength is less than 300 gauss, since the plasma density is lowered, there is a fear that sputtering cannot be performed in the case of a high resistance sputtering target. On the other hand, when it exceeds 1000 gauss, there exists a possibility that the controllability of the film thickness and the electrical property in a film may worsen.

The method of sputtering is not specifically limited, Any of DC sputtering with low plasma activity and high frequency sputtering with a frequency of 10 MHz or less may be sufficient. In addition, sputtering may be pulse sputtering.

Here, DC sputtering means the sputtering method (direct current sputtering) performed by applying DC power supply, and high frequency sputtering (RF sputtering) means sputtering performed by applying AC power supply (AC sputtering). In addition, pulse sputtering means sputtering performed by applying a pulse voltage.

Since RF sputtering has a higher plasma density and lower discharge voltage as compared to DC sputtering, lattice disturbance and the like can be reduced, and carrier mobility can be increased. In general, the RF sputtering side tends to obtain a film having good in-plane uniformity.

Therefore, it is anticipated that the film | membrane obtained by RF sputtering will also increase the field effect mobility when it is set as TFT element. However, since RF sputtering is generally slower than DC sputtering, DC sputtering has been employed industrially.

The power density applied to the target at the time of DC sputter film deposition becomes like this. Preferably it is 1-10W / cm <^2> , More preferably, it is 2-5W / cm <^2> . Especially preferably, it is 2.5-5W / cm <^2> .

When the power density is less than 1 W / cm ² , there is a risk that the film formation speed is slowed, resulting in poor productivity, and the discharge may not be stable. On the other hand, when the sputter power density is more than 10 W / cm ² , the film formation speed may be too high, resulting in poor controllability of film thickness and uniformity of properties.

As a preferable alternating current sputtering, there are the following methods.

The substrates are sequentially conveyed at positions facing the three or more targets arranged at predetermined intervals in the vacuum chamber, and negative and positive potentials are alternately applied to the respective targets, thereby generating plasma on the targets. To form a film on the substrate surface.

At this time, film formation is performed while switching at least one of the outputs from the AC power source to which the potential is applied between two or more targets connected by branching. That is, at least one of the outputs from the AC power supply is branched to connect to two or more targets, and film formation is performed while applying different potentials to neighboring targets.

As an apparatus which can be used for this sputtering, AC (AC) sputtering apparatus for large area production of patent document 3 is mentioned, for example. By using this apparatus, it is possible to form a film at higher speed, and the film carrier concentration can be made a predetermined value with good reproducibility.

The said AC sputter apparatus has a vacuum chamber, the board | substrate holder arrange | positioned inside a vacuum chamber specifically, and the sputter source arrange | positioned in the position which opposes this board | substrate holder. The main part of a sputter source is shown in FIG.

The sputter source has a plurality of sputter portions, each has plate-shaped targets 100a to 100f, and if the sputtered surface of each target 100a to 100f is a sputter surface, each target is located on the same plane as the sputter surface. Is placed.

Each target 100a-100f is formed in the elongate rectangular parallelepiped which has a longitudinal direction, and each target is the same shape, and the edge part (side surface) of the longitudinal direction of a sputter | spatter surface is mutually spaced at predetermined intervals, and is arrange | positioned in parallel. Therefore, the side surfaces of the adjacent targets 100a to 100f are parallel.

AC power supplies 300a to 300c are disposed outside the vacuum chamber, and two corresponding electrodes are connected to each of these AC power supplies. Of the two terminals of each of the AC power supplies 300a to 300c, one terminal is connected to one of two adjacent electrodes, and the other terminal is connected to the other electrode.

Two terminals of each of the AC power supplies 300a to 300c output voltages with different polarities of positive and negative, and the targets 100a to 100f are closely attached to the electrodes, so that two adjacent targets 100a to 100f are attached. AC voltages of different polarities are applied from AC power supplies 300a to 300c. Therefore, when one of the targets 100a to 100f adjacent to each other is disposed at the positive potential, the other is arranged to be at the negative potential.

Magnetic field forming means 200a to 200f are disposed on the surface opposite to targets 100a to 100f of the electrode. Each of the magnetic field forming means 200a to 200f has an elongated annular magnet having an outer circumference of approximately the same size as the outer circumference of the targets 100a to 100f, and a rod magnet shorter than the length of the annular magnet.

Each annular magnet is disposed in parallel to the longitudinal direction of the targets 100a to 100f at a position immediately after the corresponding one of the targets 100a to 100f. As described above, since the targets 100a to 100f are arranged in parallel at a predetermined interval, the annular magnets are also arranged at the same interval as the targets 100a to 100f.

In the case of using the above apparatus, the power density is preferably 3 to 20 W / cm ² . If it is less than 3 W / cm ² , the deposition rate is slow and not economically productive. If it exceeds 20 W / cm ² , the target may be broken. Power density, and more preferably from 5 to 20W / cm ^2, more preferably 4 to 10W / cm ^2.

The frequency of the AC sputter is preferably in the range of 10 kHz to 1 MHz. If it is less than 10 kHz, there may be a problem of noise. If it exceeds 1 MHz, the plasma becomes too wide, so that sputtering may be performed outside the desired target position, resulting in a loss of uniformity. More preferred AC sputter frequencies are from 20 kHz to 500 kHz.

In addition, when using said apparatus, film-forming speed becomes like this. Preferably it is 70-250 nm / min, More preferably, it is 100-200 nm / min.

The target used for the film-forming method of this invention will not be specifically limited if it is a target which consists of a metal oxide, Preferably it is the following 1st-3rd target.

The first target which can be suitably used for the film forming method of the present invention is a target made of a metal oxide, wherein the metal oxide is selected from the group consisting of gallium element (Ga), zinc element (Zn) and tin element (Sn). The above element and indium element (In) are contained, and content of the indium element in a target satisfies the following atomic ratio.

0.2 ≤ [In] / total metal atoms ≤ 0.8

(In the above formula, [In] is the number of atoms of the indium element in the target.

The total metal atom is the number of atoms of all metal atoms included in the target.)

The atomic ratio is preferably 0.25 ≦ [In] / total metal atoms ≦ 0.75, more preferably 0.3 ≦ [In] / total metal atoms ≦ 0.7.

When [In] / total metal atoms (atomic ratio) is less than 0.2, the carrier concentration may be lower than that of the semiconductor region. On the other hand, when [In] / total metal atoms (atomic ratios) are more than 0.8, the sputtered thin film tends to crystallize, and when formed into a large area, there is a fear that the in-plane electrical characteristics become uneven.

The 2nd target which can be used suitably for the film-forming method of this invention is a target which consists of metal oxides, The said metal oxide contains an indium element (In), a gallium element (Ga), and a zinc element (Zn), The content of indium element, gallium element and zinc element satisfies the following atomic ratio.

0 <[In] / [Ga] <0.5

0.2 <[In] / ([In] + [Ga] + [Zn]) <0.9

(In the above formula, [In] is the number of atoms of the indium element in the target, [Ga] is the number of atoms of the gallium element in the target, and [Zn] is the number of atoms of the zinc element in the target.)

The metal oxide of the second target preferably satisfies the following atomic ratio.

0 <[In] / [Ga] <0.45

0.3 <[In] / ([In] + [Ga] + [Zn]) <0.9

The metal oxide of the second target more preferably satisfies the following atomic ratio.

0 <[In] / [Ga] <0.35

0.4 <[In] / ([In] + [Ga] + [Zn]) <0.9

The effect of sputtering by introducing water molecules in any composition region with respect to the metal oxide of the second target can be obtained. However, when [In] / [Ga] is 0.5 or more, the oxidation effect is obtained even when the film is formed by introducing oxygen molecules. Because of its large size, the carrier concentration becomes too low, and when the resulting thin film is used for a TFT element, the field effect mobility can only be obtained about ² cm ² / Vs. When [In] / ([In] + [Ga] + [Zn]) is 0.2 or less, since the resistance of the target becomes high, there is a possibility that DC sputtering or AC sputtering cannot be performed. In addition, when [In] / ([In] + [Ga] + [Zn]) is 0.9 or more, the resulting thin film is liable to crystallize, and when formed into a large area, there is a fear that the in-plane electrical characteristics become uneven. have.

In the second target, by reducing the proportion of the gallium element and increasing the proportion of the indium element, the carrier concentration and the carrier mobility can be increased to obtain a high field effect mobility.

If the composition ratio of the second target is, for example, 0 <[In] / [Ga] <0.45 and 0.3 <[In] / ([In] + [Ga] + [Zn]) <0.9, the field effect mobility is 5 to 10 cm. ² / Vs, and 0 <[In] / [Ga] <0.35 and 0.4 <[In] / ([In] + [Ga] + [Zn]) <0.9, the field effect mobility is 10 cm ² / It is preferable because it can be set to Vs or more.

A third target that can be suitably used in the film forming method of the present invention is a target made of a metal oxide, the metal oxide containing indium element (In), tin element (Sn) and zinc element (Zn), and indium in the target. The content of the element, tin element and zinc element satisfies the following atomic ratio.

0.2 <[In] / ([In] + [Sn] + [Zn]) <0.9

0 <[Sn] / ([In] + [Sn] + [Zn]) <0.5

(In the above formula, [In] is the number of atoms of the indium element in the target, [Sn] is the number of atoms of the tin element in the target, and [Zn] is the number of atoms of the zinc element in the target.)

The metal oxide of the third target preferably satisfies the following atomic ratio.

0.2 <[In] / ([In] + [Sn] + [Zn]) <0.9

0 <[Sn] / ([In] + [Sn] + [Zn]) <0.35

The metal oxide of the third target more preferably satisfies the following atomic ratio.

0.3 <[In] / ([In] + [Sn] + [Zn]) <0.9

0 <[Sn] / ([In] + [Sn] + [Zn]) <0.2

In the metal oxide of the third target, when [In] / ([In] + [Ga] + [Zn]) is 0.2 or less, the resistance of the target becomes high, so that DC sputtering or AC sputtering cannot be performed. There is a concern. In addition, when [In] / ([In] + [Ga] + [Zn]) is 0.9 or more, the resulting thin film is liable to crystallize, and when formed into a large area, there is a fear that the in-plane electrical characteristics become uneven. have. In addition, since tin element becomes a carrier scattering source, when [Sn] / ([In] + [Sn] + [Zn]) is 0.5 or more, carrier mobility becomes low and the thin film obtained is used for a TFT element. There is a fear that the field-effect mobility of becomes less than 5 cm ² / Vs.

In the third target, by reducing the proportion of the tin element and increasing the proportion of the indium element, the carrier concentration and the carrier mobility can be controlled to obtain a high field effect mobility.

The composition ratio of the third target is, for example, 0.2 <[In] / ([In] + [Sn] + [Zn]) <0.9 and 0 <[Sn] / ([In] + [Sn] + [Zn]) < At 0.35, the field effect mobility can be 5 to 10 cm ² / Vs, and 0.3 <[In] / ([In] + [Sn] + [Zn]) <0.9 and 0 <[Sn] / ([In ] + [Sn] + [Zn]) <0.2, the field effect mobility can be 10 cm ² / Vs or more.

In Non-Patent Document 3, since the carrier concentration is controlled, the target contains a Ga element, and the atomic number ratio of the target of the Ga element to all the metal elements is 0.33.

However, when content of Ga element exceeds 0.33 by the atomic number ratio with respect to all the metal elements of a target, Ga becomes a scattering source, and there exists a possibility that the mobility of the TFT element whose thin film obtained is a semiconductor layer may fall. On the other hand, if the content of the Ga element is less than 0.33 in the ratio of atoms to all the metal elements of the target, there is an advantage that a small amount of Ga becomes a scattering source, and high mobility can be expected, while the carrier concentration is increased. There was a problem that it became difficult to control to 10 ¹⁸ cm ^-3 or less.

In the film forming method of the present invention, when the content of Ga element is less than 0.5 in the atomic number ratio to the indium element, a suitable TFT device can be obtained even when the film is formed using the second target or the third target containing no Ga element. have. In particular, when the third target is used, since chemical resistance can be improved, it is possible to form the source / drain electrodes by wet etching without forming an etching stopper layer, and a TFT device which operates more suitably can be manufactured. The manufacturing cost can be reduced.

The metal oxide of the first target is preferably an oxide substantially consisting of or consisting solely of an indium element and a zinc element, and the metal oxide of the second target is likewise preferably from an indium element, a gallium element and a zinc element. It is an oxide which consists essentially or consists only of it, and the metal oxide of a 3rd target is an oxide which consists essentially of or consists only of an indium element, a tin element, and a zinc element.

The first to third targets are, for example, Mg, Ca, Sr, Ba, Ti, Zr, Hf, Al, Ge, Cu, Co, Fe, Ni, Mo, and rare earths in a range that does not impair the effects of the present invention. One or more types of elements chosen from an element and a lanthanoid element can be included.

By annealing the thin film obtained by the film forming method of the present invention, the carrier concentration can be reduced by entering the oxygen defect as O by the OH group taken in the thin film. The annealing treatment condition is preferably annealing treatment at 150 to 400 ° C. for 5 to 120 minutes.

If the annealing temperature is less than 150 ° C, the OH group taken up in the film does not sufficiently form an oxygen bond, so it is difficult to obtain an effect of lowering the carrier concentration, and if it is more than 400 ° C, crystallization may proceed. The same applies to the processing time.

The annealing treatment is not particularly limited as long as it is in the temperature range of 150 ° C to 400 ° C, but is preferably performed in an atmosphere containing at least oxygen. By performing it in the atmosphere containing oxygen, the gap of the characteristic at the time of using an annealing thin film as TFT can be suppressed.

The oxide semiconductor obtained by annealing the thin film obtained by the film forming method of the present invention (hereinafter may only be referred to as the oxide semiconductor of the present invention) can be suitably used as a semiconductor thin film of a thin film transistor.

The field effect transistor including the oxide semiconductor of the present invention is a transistor having a high field effect mobility and an on-off ratio, showing normally off and clear pinching off. Moreover, since the field effect transistor containing the oxide semiconductor of this invention can form an oxide semiconductor at low temperature, it can be comprised on the board | substrate which has a limit in heat-resistant temperature, such as an alkali free glass.

The oxide semiconductor of the present invention is usually used in the n-type region, but various semiconductors such as PN junction transistors in combination with various P-type semiconductors such as P-type Si-based semiconductors, P-type oxide semiconductors, and P-type organic semiconductors. It can be used for devices. The TFT can also be applied to various integrated circuits such as logic circuits, memory circuits, and differential amplifier circuits. In addition to the field-effect transistors, the present invention can be adapted to electrostatic-induced transistors, schottky barrier transistors, Schottky diodes, and resistive elements.

As the configuration of the transistor, known configurations such as a bottom gate, a top gate, a bottom contact, and a top contact can be used without limitation. In particular, the bottom gate configuration is advantageous because high performance is obtained as compared with TFTs of amorphous silicon or ZnO. The bottom gate configuration is preferable because it is easy to reduce the number of masks at the time of manufacture, and it is easy to reduce the manufacturing cost for applications such as large displays.

For display of a large area, a thin film transistor having a channel etched bottom gate configuration is particularly preferable. The thin film transistor of the channel etch bottom gate structure can manufacture a display panel at low cost with few photomasks at the time of an optical lithography process. Among them, the thin-film transistor of the channel gate type bottom gate structure top contact structure is particularly preferable because of its good properties such as mobility and easy industrialization.

The field effect transistor including the oxide semiconductor of the present invention can be suitably operated even if the film thickness of the semiconductor film, which is difficult to obtain good characteristics in the past, is 50 nm or more, more preferably 60 nm or more and 70 nm or more. In addition, the field effect transistor including the oxide semiconductor of the present invention has a suitable mobility, on-off ratio and S value.

In addition, the upper limit of the film thickness of a semiconductor film is 100 nm, for example.

The S value of the field effect transistor including the oxide semiconductor of the present invention is preferably 1 V / decade or less, more preferably 0.7 V / decade or less, and particularly preferably 0.5 V / decade or less. When the value of S value exceeds 1V / decade, there exists a possibility that a transistor may not show favorable switching characteristics, such as driving voltage becoming high.

The threshold voltage of the field effect transistor including the oxide semiconductor of the present invention is usually -5.0 to 5.0 V, preferably -1.0 to 2.0 V, more preferably -1.0 to 1.0 V, even more preferably 0 to 1.0V. If it is larger than 5V, there is a concern that the driving voltage becomes large, the power consumption becomes large, and if it is smaller than -5V, the power consumption may increase.

The channel length of the field-effect transistor including the oxide semiconductor of the present invention is not particularly limited as long as it is a range usually used, but is usually 10 to 70 µm, preferably 20 to 50 µm.

The channel width of the field effect transistor including the oxide semiconductor of the present invention is usually 10 to 100 µm, preferably 20 to 70 µm.

For high resolution of the display, the TFT needs to be made small. In that case, in order to obtain a desired on current, high mobility is required for the semiconductor film used for the TFT channel layer.

Since the field effect transistor including the oxide semiconductor of the present invention has high mobility, it can be expected to be suitably used in the region of 1 to 10 탆 and also in the region of 2 to 8 탆. In addition, with respect to the channel width, it can be expected that the field effect transistor including the oxide semiconductor of the present invention is suitably used in the region of 1 to 10 mu m and also in the region of 2 to 8 mu m.

2 is a schematic cross-sectional view showing an embodiment of a thin film transistor including the oxide semiconductor of the present invention.

The thin film transistor 1, which is a field effect transistor, has a bottom gate type, a gate electrode 30 is formed on a glass substrate 60, and a gate insulating film 50 is formed thereon. The oxide semiconductor film 40 is formed on the gate insulating film 50, and further, the drain electrode 10 and the source electrode 20 are formed on the gate insulating film 50.

There is no restriction | limiting in particular in the material which forms each electrode of the drain electrode 10, the source electrode 20, and the gate electrode 30, The material generally used can be arbitrarily selected.

For example, it is possible to use a metal electrode of ITO, IZO, ZnO, SnO _2, etc. of the transparent electrode or, Al, Ag, Cu, Cr, Ni, Mo, Au, Ti, a metal electrode or an alloy including these such as Ta.

Each electrode of the drain electrode 10, the source electrode 20, and the gate electrode 30 may have a multilayer structure in which two or more other conductive layers are stacked. For example, in FIG. And 30 are composed of first conductive layers 31, 21, and 11 and second conductive layers 32, 22, and 12, respectively. In particular, since source / drain electrodes have a strong demand for low-resistance wiring, a good conductor such as Al or Cu may be sandwiched by a metal having excellent adhesion such as Ti or Mo.

There is no restriction | limiting in particular in the material which forms the gate insulating film 50, The material generally used can be arbitrarily selected.

Examples of the material of the gate insulating film 50 include SiO ₂ , SiNx, Al ₂ O ₃ , Ta ₂ O ₅ , TiO ₂ , MgO, ZrO ₂ , CeO ₂ , K ₂ O, Li ₂ O, Na ₂ O, Rb ₂ O, Sc ₂ O ₃ , Y ₂ O ₃ , HfO ₃ , CaHfO ₃ , PbTi ₃ , BaTa ₂ O ₆ , SrTiO ₃ , AlN and the like can be used. Among these, preferably _{SiO 2, SiNx, Al 2 O} 3, Y 2 O 3, HfO 3, CaHfO 3 and, more preferably, _{SiO 2, SiNx, Y 2 O} 3, HfO 3, CaHfO 3.

On the other hand, the oxygen of the oxide, it is not always be consistent with the stoichiometric ratio (for example, SiO ₂ may even even SiOx).

The gate insulating film 50 may have a structure in which two or more different insulating films are stacked. The gate insulating film 50 may be any of crystalline, polycrystalline, and amorphous, but is preferably polycrystalline or amorphous, which is easily industrially manufactured.

The oxide semiconductor film 40 is an oxide semiconductor obtained by the film forming method of the present invention.

The oxide semiconductor film 40 usually has a carrier density of less than 10 ¹⁸ cm ⁻³ , preferably less than 5 × 10 ¹⁷ cm ⁻³ , and more preferably less than 1 × 10 ¹⁷ cm ⁻³ , as determined by hole measurement. to be. If the carrier density is 10 ¹⁸ cm ^-3 or more, the leakage current may be large.

On the other hand, the lower limit of the carrier density also depends on the use of the device having the oxide semiconductor film 40, but is preferably set to 10 ¹⁵ cm ⁻³ or more.

The specific resistance of the oxide semiconductor film 40 is usually 10 ⁻¹ to 10 ⁸ Ωcm, preferably 10 ¹ to 10 ⁷ Ωcm, and more preferably 10 ² to 10 ⁶ Ωcm. .

When the resistivity is less than 10 ⁻¹ Ωcm, electricity easily flows and may not function as a semiconductor thin film. On the other hand, when the specific resistance is more than 10 ⁸ Ωcm, there is a fear that the semiconductor will not function as a semiconductor unless a strong electric field is applied.

As for the film thickness of the oxide semiconductor film 40, an optimal value is appropriately selected according to the specific resistance of the oxide semiconductor 40 itself, and from a viewpoint of uniformity, it is preferable that the film thickness is thick, and the film formation time (cycle time of a process) The thinner the film thickness is preferable from the viewpoint of.

The film thickness of the oxide semiconductor film 40 is usually 20 to 500 nm, preferably 50 to 150 nm, more preferably 60 to 140 nm, particularly preferably 70 to 130 nm, and particularly preferably 70 to 110 nm.

When the film thickness of an oxide semiconductor is less than 20 nm, there exists a possibility that the characteristic of the produced TFT may become nonuniform because of the nonuniformity of the film thickness at the time of forming into a large area. On the other hand, when the film thickness is more than 500 nm, the film formation time becomes long and there is a possibility that it cannot be industrially employed.

The field effect mobility of the thin film transistor 1 is usually 1 cm ² / Vs or more, preferably 5 cm ² / Vs or more, more preferably 10 cm ² / Vs or more, still more preferably 18 cm ² / Vs or more, particularly preferably Preferably at least 30 cm ² / Vs, most preferably at least 50 cm ² / Vs.

If the field effect mobility is less than 1 cm ² / Vs, the switching speed may be slowed. The upper limit of the field effect mobility is, for example, 500 cm ² / Vs.

The on-off ratio of the thin film transistor 1 is usually 10 ³ or more, preferably 10 ⁴ or more, more preferably 10 ⁵ or more, still more preferably 10 ⁶ or more, and particularly preferably 10 ⁷ or more.

In addition, from the viewpoint of low power consumption, the thin film transistor 1 preferably has the threshold voltage Vth turned off normally at +. When the threshold voltage Vth is normally on at-, power consumption may increase.

The manufacturing method of the field effect transistor containing the oxide semiconductor of this invention can be manufactured, for example by the following method.

First, a metal film is formed on an insulating substrate to form a gate electrode. As the metal film, Mo, Al, Cr, and an alloy containing these as a main component are suitably used. You may use the laminated film of these metal films.

On the gate electrode and the insulating substrate, a gate insulating film is formed by plasma CVD. Next, the semiconductor layer used as a channel is formed into a film by sputtering method. Next, through the photolithography process and the etching process, the semiconductor layer of the area | region which becomes TFT is formed in island shape. Subsequently, a second metal film for forming a source electrode and a drain electrode is formed. As the gate electrode, a material such as Al, Cr, Mo, or an alloy containing these can be used for the second metal film. It is also possible to comprise a laminated film.

The transistor is obtained by obtaining the pattern of the source electrode and the drain electrode of a desired shape by the photolithography process and the etching process of the film-formed 2nd metal film.

Example

Examples 1 to 30

A 2-inch target having a target composition shown in Tables 1 to 3 was attached to the magnetron sputtering apparatus, a silicon wafer with a thermal oxide film having a thickness of 100 nm as the substrate A1, and a slide glass as the substrate B1 (# 1737, manufactured by Corning Corporation). Mounted respectively.

After transferring the substrate into the chamber, after a predetermined ultimate pressure, Table 1 to 3, introducing the Ar gas and the H ₂ O gas of partial pressure ratio shown in Table 1 to 3 sputtering conditions as film 50nm amorphous film with a thickness shown in Fig. It formed into a film on the board | substrate A1 and the board | substrate B1, respectively.

The obtained thin film was annealed in an oven under annealing conditions shown in Tables 1 to 3 to obtain an oxide semiconductor obtained by laminating on the substrate A1 and the substrate B1.

The board | substrate B1 provided with the oxide semiconductor after heat processing was cut into 1 cm <^2> , and the Au electrode was stuck to four corners. Carrier density | concentration was evaluated using the Au electrode and copper wire with the silver paste as an element (B1) for hall effect measurement. The results are shown in Tables 1-3.

In addition, the measurement of carrier density was calculated | required by performing Hall effect measurement using ResiTest 8300 type (Toyo Technica make) at room temperature.

The substrate A1 including the oxide semiconductor after the heat treatment was again mounted on the 2-inch cathode magnetron sputtering apparatus, and the Au target was mounted on the cathode, and a dedicated metal mask was used to make W / L = 1000/200 µm. An Au electrode was formed into a film so that TFT element A1 was manufactured.

The obtained TFT element A1 was set in Casery-4200SCS, and transfer characteristics were evaluated under the conditions of drain voltage (Vds) = 10V and gate voltage (Vgs) = -20 to 20V. The results are shown in Tables 1-3.

Comparative Examples 1 to 12 and Reference Examples 1 to 2

Ar gas and H ₂ O gas (Comparative Examples 5 to 6 and Reference Examples 1 to 2) or Ar gas and O ₂ gas having a partial pressure ratio shown in Tables 4 and 5 using a target having a target composition shown in Tables 4 and 5 (Comparative Examples 1 to 4, 7 to 12) were introduced, and an oxide semiconductor was produced in the same manner as in Examples 1 to 30, except that the amorphous film was formed and annealed under the conditions shown in Tables 4 and 5. In the same manner as in the case of 30 to 30, the device for measuring the Hall effect (B1) was manufactured to evaluate the carrier concentration, and the TFT device (A1) was manufactured to evaluate the transfer characteristics. The results are shown in Tables 4 and 5.

Based on the result of an Example and a comparative example, the relationship of oxygen concentration or hydrogen concentration, and the carrier concentration of the thin film obtained is shown in FIG.

Example 31

A field effect transistor having a bottom gate structure top contact structure was fabricated.

An ITZO sputtering target having an atomic ratio In: Sn: Zn = 36: 15: 49 was mounted on a DC magnetron sputtering film deposition apparatus for sputtering, and a semiconductor layer (film thickness of 80 nm) was formed on a silicon substrate with a thermal oxide film (100 nm). .

Sputtering conditions were 2 × 10 ^-4 Pa attained, sputter pressure 0.65 Pa, partial pressure ratio [H ₂ O] / ([H ₂ O] + [Ar]) = 3%, partial pressure ratio [O ₂ ] / ([ O ₂ ] + [Ar]) = 0%, a power density of 5.0 W / cm ² , a TS distance of 5 cm, and a deposition rate of 95 nm / min.

The obtained semiconductor layer was photolithographic, the semiconductor region (so-called island) was comprised, and it heat-processed at 300 degreeC under air for 1 hour. After the photoresist film was formed, a Ti / Au / Ti laminated metal film was formed by DC sputtering and patterned by lift-off to form a source electrode and a drain electrode, respectively. Then, heat processing was performed at 300 degreeC under air | atmosphere for 1 hour.

Next, it formed into a film in order of SiOx and SiNx by plasma CVD, and formed the 1st protective layer and the 2nd protective layer, respectively. Contact holes were formed and connected to external wiring. Thereafter, heat treatment was performed at 300 ° C. for 1 hour in the air to produce a field effect transistor having a bottom gate configuration and a top contact configuration with W = 20 μm and L = 20 μm and using a Si substrate as a gate electrode.

The characteristic evaluation was performed about the obtained field effect transistor.

As a result, the field effect mobility was 21 cm ² / Vs, the on-off ratio was 10 ⁸ or more, the threshold voltage was 0.3 V, and the S value was 0.2 V / decade.

The said evaluation was evaluated using the semiconductor parameter analyzer (Casely-4200) in the dry nitrogen atmosphere of atmospheric pressure, room temperature, and light-shielding environment.

Comparative Example 13

The partial pressure ratio [H ₂ O] / ([H ₂ O] + [Ar]) = 0%, the partial pressure ratio [O ₂ ] / ([O ₂ ] + [Ar A field effect transistor was produced and evaluated in the same manner as in Example 31 except that the ratio was set at 10%).

As a result, the obtained field effect transistor was in a normally on state with a threshold voltage of -20V or less. In oxygen partial pressure control, it was confirmed that it is difficult to manufacture a thin film transistor whose channel layer is 80 nm.

Example 32

By using Mo as the source electrode and the drain electrode, and wet etching the Mo electrode on the channel layer using a phosphate wet etching solution, except that a field effect transistor having a channel etched bottom gate configuration and a top contact configuration was manufactured. As in Example 31, a field-effect transistor was produced and evaluated.

As a result, the obtained field effect transistor had a field effect mobility of 19 cm ² / Vs, an on-off ratio of 10 ⁸ or more, a threshold voltage of 0.3 V, and an S value of 0.2 V / decade.

Example 33

RF sputtering was carried out on the glass substrate at room temperature, and 200 nm of molybdenum metals were laminated | stacked, and it patterned by dry etching, and produced the gate electrode. The gate electrode became a forward taper after etching. The substrate on which the gate electrodes were laminated was formed by a plasma chemical vapor deposition apparatus (PECVD) in the order of SiNx and SiO ₂ , and the laminated film was used as the gate insulating film.

The sputtering target like Example 31 was mounted in the DC magnetron sputtering film-forming apparatus, sputtered on the conditions similar to Example 31, and the semiconductor layer (film thickness 80nm) was formed on the gate insulating film. Then, it heat-processed at 300 degreeC for 1 hour.

SiOx was formed into a film by PECVD, and the SiOx thin film was formed. Subsequently, a resist film was formed into a film and patterned. The thin film was patterned by dry etching (RIE) to form a first protective layer (etching stopper). After applying and forming the photoresist resist film for lift-off, the metal laminated film of Ti / Au / Ti was formed into a film by DC sputtering, lift-off and patterning, and the source electrode and the drain electrode were formed, respectively. Furthermore, SiNx was formed into a film by PECVD (PECVD SiNx: H), and it was set as the 2nd protective layer. Contact holes were formed and connected to external wiring. Then, it heat-processed at 300 degreeC for 1 hour in air | atmosphere, and produced the etching stopper type field effect transistor which is a bottom gate structure of W = 20 micrometers and L = 20 micrometers.

The field effect transistor obtained was evaluated in the same manner as in Example 31.

As a result, the field-effect mobility of 18 cm ² / Vs, the on-off ratio was 10 ⁸ or more, the threshold voltage was 0.3 V, and the S value was 0.2 V / decade.

Example 34

Sputtering was performed on the conditions of Table 6, without heating the glass substrate of width 1100mm, length 1250mm, and thickness 0.7mm using the film-forming apparatus of FIG.

Here, In: Sn: Zn (atomic ratio) = 36: 15: 49, and each target 100a to 100f is formed by using six targets 100a to 100f having a width of 200 mm, a length of 1700 mm, and a thickness of 10 mm. Parallel to the width direction, it arrange | positioned so that the distance between targets might be 2 mm. The width of the magnetic field forming means 200a to 200f was set to 200 nm which is the same as that of the targets 100a to 100f.

In the gas supply system, Ar and H ₂ O, which are sputter gases, were introduced into the system at a flow rate ratio of 99: 1. The film-forming atmosphere at this time became 0.5 Pa. The power of the AC power source was 3 W / cm ² (= 10.2 kW / 3400 cm ² ) and the frequency was 10 kHz.

The film was formed under the above conditions for 8 seconds, and the film thickness of the obtained ITZO was 15 nm. The film formation rate was high at 112.5 nm / min, and the result was suitable for mass production.

Moreover, it put in the glass substrate electric furnace with ITZO obtained in this way, and heat-processed on 400 degreeC 15 minutes conditions in air, cut out into the size of 1 cm <^2> , and measured the hole by the four probe method. As a result, the carrier concentration was 2.5 × 10 ¹⁶ cm ⁻³ , which confirmed that the semiconductor materialization was sufficiently performed.

Examples 35-39

A semiconductor thin film was obtained in the same manner as in Example 34 except that the target composition and the sputtering conditions were changed as in Table 6. In addition, after heat-processing like Example 34, hall measurement was performed and it confirmed that it was all semiconductorized.

Comparative Example 14

A semiconductor thin film was obtained in the same manner as in Example 34 except that the sputtering conditions were changed as shown in Table 6. Argon and oxygen were introduced to form the ITZO without using water for the introduction gas. As a result of the hole measurement, the carrier concentration was 2.5 × 10 ¹⁷ cm ⁻³ and semiconductorized, but the film formation rate was slow at 36 nm / min. This film formation speed is thought to leave a problem in mass production.

Comparative Example 15

In Comparative Example 14, the output power was increased to 20 W / cm ² to form a high speed film. As a result, the film formation speed increased to 90 nm / minute. However, the carrier concentration was 7.5x10 ¹⁸ cm ^-3 and was not semiconducted.

Comparative Example 16

A semiconductor thin film was obtained in the same manner as in Comparative Example 14 except that the sputtering conditions were changed as shown in Table 6. Carrier concentration was 5.5x10 <^19> cm <^-3> and did not semiconductorize.

Examples 40-46

A magnetron sputtering apparatus was mounted with a 2-inch target having a target composition shown in Table 7, and a silicon wafer with a thermal oxide film having a thickness of 100 nm was used as the substrate A1, and a slide glass (C1717 product manufactured by Corning Corporation) as the substrate B1, respectively. Fitted.

After transferring the substrate into the chamber, after a predetermined ultimate pressure, and Table 7 a partial pressure ratio of the Ar gas and the H ₂ O gas, Table 7 substrate sputtering conditions as film 50nm amorphous film with a thickness shown in introducing shown in (A1 Film-forming on the board | substrate B1, respectively.

The obtained thin film was annealed in an oven under annealing conditions shown in Table 7 to obtain an oxide semiconductor obtained by laminating on the substrate A1 and the substrate B1.

The board | substrate B1 provided with the oxide semiconductor after heat processing was cut into 1 cm <^2> , and the Au electrode was stuck to four corners. Carrier density | concentration was evaluated using the Au electrode and copper wire with the silver paste as an element (B1) for hall effect measurement. The results are shown in Table 7.

In addition, the measurement of carrier density was calculated | required by performing Hall effect measurement using ResiTest 8300 type (Toyo Technica make) at room temperature.

The substrate A1 including the oxide semiconductor after the heat treatment was again mounted on the 2-inch cathode magnetron sputtering apparatus, and the Au target was mounted on the cathode, and a dedicated metal mask was used to make W / L = 1000/200 µm. An Au electrode was formed into a film so that TFT element A1 was manufactured.

The obtained TFT element A1 was set in Casery-4200 SCS, and transfer characteristics were evaluated under the conditions of drain voltage (Vds) = 10V and gate voltage (Vgs) = -20 to 20V. The results are shown in Table 7.

Examples 47 to 51

By using a target having the target composition shown in Table 8, other than introducing the Ar gas and the H ₂ O gas of partial pressure ratio shown in Table 8, and it was subjected to an amorphous film formation and annealing under the conditions shown in Table 8. Example 40 An oxide semiconductor was produced in the same manner as in the Examples 46 to 46, and the carrier concentration was evaluated in the same manner as in Examples 40 to 46 to evaluate the carrier concentration, and the TFT element A1 was fabricated to evaluate the transfer characteristics. . The results are shown in Table 8.

The oxide semiconductor obtained by the manufacturing method of the oxide semiconductor of this invention can be used widely as a semiconductor thin film of field effect transistors, such as a thin film transistor.

While the embodiments and / or examples of the present invention have been described in detail above, those skilled in the art have made many changes to these exemplary embodiments and / or examples without departing substantially from the novel teachings and effects of the present invention. It is easy to add. Accordingly, many modifications thereof are within the scope of the present invention.

The contents of the document described in this specification are all incorporated herein by reference.

Claims (19)

A film forming method comprising sputtering a target made of a metal oxide in a gas atmosphere containing a rare gas atom and water molecules and having a content of the water molecule in a partial pressure ratio of 0.1 to 10% relative to the rare gas atom to form a thin film on the substrate. . The method of claim 1,
A film forming method wherein the pressure of the gas is 0.1 to 5.0 Pa. 3. The method according to claim 1 or 2,
The film forming method, wherein the sputtering is a direct current sputter. 3. The method according to claim 1 or 2,
The film formation method, wherein the sputtering is alternating current sputtering. The method of claim 3, wherein
A film forming method having a DC power density of 1 to 5 W / cm ² . The method of claim 4, wherein
The substrates are sequentially conveyed to positions facing the three or more targets arranged in the vacuum chamber at predetermined intervals,
A film forming method for forming a thin film on the surface of the substrate by generating a plasma on the target by applying a negative potential and a positive potential alternately from the AC power source to each target,
The film forming method is performed while switching at least one of the outputs from the AC power source while switching a target for applying a potential between two or more targets connected by branching. The method according to claim 4 or 6,
A film forming method having an alternating current power density of 5 to 20 W / cm ² . The method according to any one of claims 4, 6 and 7,
The film forming method, wherein the frequency of the AC power supply is 10 kHz to 1 MHz. The method according to any one of claims 1 to 8,
A film forming method in which the film forming speed in the direction perpendicular to the film forming surface of the substrate is 1 to 100 nm / min. 10. The method according to any one of claims 1 to 9,
And the distance between the target and the substrate is 1 to 15 cm in a direction perpendicular to the deposition surface of the substrate. 11. The method according to any one of claims 1 to 10,
The film-forming method whose magnetic field intensity of the said atmosphere is 300-1000 gauss. 12. The method according to any one of claims 1 to 11,
The metal oxide contains at least one element selected from the group consisting of gallium element (Ga), zinc element (Zn) and tin element (Sn), and indium element (In),
The film-forming method in which content of the indium element in a target satisfy | fills the following atomic ratio.
0.2 ≤ [In] / total metal atoms ≤ 0.8
(In the above formula, [In] is the number of atoms of the indium element in the target.
The total metal atom is the number of atoms of all metal atoms included in the target.) 12. The method according to any one of claims 1 to 11,
The metal oxide contains indium element (In), gallium element (Ga) and zinc element (Zn),
The film-forming method in which content of an indium element, a gallium element, and a zinc element in a target satisfy | fills the following atomic ratio.
0 <[In] / [Ga] <0.5
0.2 <[In] / ([In] + [Ga] + [Zn]) <0.9
(In the above formula, [In] is the number of atoms of the indium element in the target, [Ga] is the number of atoms of the gallium element in the target, and [Zn] is the number of atoms of the zinc element in the target.) 12. The method according to any one of claims 1 to 11,
The metal oxide contains indium element (In), tin element (Sn) and zinc element (Zn),
The film-forming method in which content of the indium element, tin element, and zinc element in a target satisfy | fills the following atomic ratio.
0.2 <[In] / ([In] + [Sn] + [Zn]) <0.9
0 <[Sn] / ([In] + [Sn] + [Zn]) <0.5
(In the above formula, [In] is the number of atoms of the indium element in the target, [Sn] is the number of atoms of the tin element in the target, and [Zn] is the number of atoms of the zinc element in the target.) The manufacturing method of the oxide semiconductor thin film which carries out the annealing process of the thin film obtained by the film-forming method in any one of Claims 1-14 at 150-400 degreeC for 5 to 120 minutes. The method of claim 15,
The manufacturing method of the oxide semiconductor thin film which performs the said annealing process in the atmosphere containing at least oxygen. The field effect type thin film transistor element provided with the oxide semiconductor thin film obtained by the manufacturing method of the thin film of Claim 15 or 16. The method of claim 17,
And the oxide semiconductor thin film is a channel layer. The method according to claim 17 or 18,
A field effect type thin film transistor element having a mobility of 10 cm ² / Vs or more and a threshold voltage of -5 to 5V.

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