JP6150752B2 - Oxide-based semiconductor material and semiconductor element - Google Patents

Description

  The present invention relates to an oxide-based semiconductor material and a semiconductor element containing In, Ga, Zn, and O as constituent components.

An oxide semiconductor material containing In, Ga, Zn, and O as constituent components (hereinafter referred to as an In—Ga—Zn—O semiconductor material) has been studied for use as a channel layer of a semiconductor element. Semiconductor elements have been put into practical use (for example, Patent Documents 1 to 4).
The In—Ga—Zn—O-based semiconductor material is manufactured by film formation on a substrate, such as sputtering or vapor deposition, or epitaxial growth on the substrate. An In—Ga—Zn—O-based semiconductor material usually has n-type characteristics, and is used as a semiconductor element using the characteristics. Some of them have p-type characteristics (for example, Patent Documents 1 to 4). In any case, since the semiconductor material has either n-type or p-type characteristics, an n-type or p-type material is selected depending on the purpose.

JP 2004-119525 A JP 2010-205798 A JP 2010-219538 A JP 2011-216574 A

  As described above, it is necessary to design a circuit by preparing semiconductor elements using different semiconductor materials, depending on the purpose. For example, when an attempt is made to configure a CMOS, as shown in FIG. 7, a semiconductor element 30 having an n-type channel layer and a semiconductor element 31 having a p-type channel layer are prepared separately, and wiring (Metal etc.) is prepared. It is necessary to connect at 32. However, such a circuit configuration is a factor that increases the manufacturing cost, and causes various causes such as failure.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a semiconductor material and a semiconductor element having both p-type and n-type characteristics.

That is, of the oxide-based semiconductor material of the present invention, a first aspect of the present invention, there In, Ga, In oxides based semiconductor material consisting of In-Ga-Zn-O-based compound as a constituent component of Zn and O And
An In, Ga, Zn material is disposed on a substrate, and in the presence of oxygen, the In, Ga, Zn material has an energy density of 0.1 J / cm ^{2 to} 10 J / cm ² , a repetition frequency of 1 kHz to 50 kHz, and a pulse width. (Half width) 200-1200 nm pulsed laser light is irradiated and heated to 1200 ° C. or higher to form an In—Ga—Zn—O-based compound that is molecularly bonded to each other on the substrate.
Wherein depending on the direction of the positive and negative electric field applied to the semiconductor material, the addition of negative electric field showed a p-type characteristics, characterized by having a positive characteristic that indicates the n-type characteristics when an electric field is applied.

The semiconductor device of the second present invention, a channel layer made of an oxide-based semiconductor material of the first invention possess, characterized in that it comprises a source and a drain, and a gate.

The semiconductor element of the third aspect of the present invention is characterized in that, in the second aspect of the present invention, a voltage for switching between positive and negative is applied to the gate.

A semiconductor device according to a fourth aspect of the invention is characterized in that, in the third aspect of the invention, the semiconductor element functions as a CMOS by switching between positive and negative voltages applied to the gate.

  As described above, an oxide-based semiconductor material of one embodiment of the present invention has P-type characteristics and n-type characteristics, and can have different characteristics depending on the direction of an electric field. It can be used as a p-type or n-type semiconductor. If such a semiconductor element is used, one type of p-type and n-type transistors can be prepared for circuit design, and the manufacturing process is simplified. The same applies to diodes.

It is a flowchart which shows the manufacturing process of the In-Ga-Zn-O type semiconductor material of one Embodiment of this invention. Similarly, it is a virtual diagram illustrating a crystal structure of an In—Ga—Zn—O-based semiconductor material and a carrier flow. Similarly, it is a figure which shows the voltage-current characteristic in a semiconductor material. Similarly, it is the figure which shows the equivalent circuit schematic and voltage-current characteristic of the semiconductor element by an In-Ga-Zn-O type semiconductor material. It is a figure which shows the voltage-current characteristic of the In-Ga-Zn-O type semiconductor material in the Example of this invention. It is a figure which shows the voltage-current characteristic of the In-Ga-Zn-O type | system | group semiconductor material in another Example. It is a figure which shows the circuit diagram and voltage-current characteristic in the conventional CMOS.

Hereinafter, an embodiment of the present invention will be described.
In-Ga-Zn-O-based semiconductor materials have In, Ga, and Zn materials attached to a substrate, and high-density energy such as laser irradiation is applied to In, Ga, and Zn materials in the presence of oxygen at atmospheric pressure. By giving, it can be produced by molecular bonding on the substrate. An In—Ga—Zn—O-based semiconductor material can be manufactured by the following method, and exhibits both p-type and n-type characteristics.

  The amount ratio of In, Ga, and Zn is not particularly limited in the present invention, and components having various amount ratios including components conventionally used in In—Ga—Zn—O-based semiconductor materials are included. Can be targeted.

For example, Patent Documents 1 and ₃ propose an In—Ga—Zn—O-based semiconductor material (m is an integer of 1 to less than 50) that is InGaO ₃ (ZnO) _m, and Patent Document 2 discloses InGaZnO ₄ and In ₂ O ₃ —Ga ₂ O ₃ —ZnO and the like have been proposed, and in Patent Document 4, a semiconductor material (0 <x <1, m is 1 or more) is (In ₁ − _x Ga _x ) ₂ O ₃ (ZnO) m. Integers less than 50) have been proposed. The present invention is applied to In—Ga—Zn—O-based semiconductor materials having these quantitative ratios and In—Ga—Zn—O-based semiconductor materials of other components.

  The component and structure of the In—Ga—Zn—O-based semiconductor material can be determined by the amount of In, Ga, and Zn components to be deposited on the substrate and the energy to be given. Each of In, Ga, and Zn may be deposited on the substrate, or may be deposited on the substrate in the form of a compound with an oxide or other component.

  The In, Ga, and Zn materials can be deposited on the substrate by adding powder of these materials to a solvent or a binder and then depositing the material on the substrate by a method such as spin coating. However, in the present invention, the attachment method is not particularly limited. Further, the adhesion amount is not particularly limited in the present invention, but the adhesion amount of In, Ga, and Zn materials can be determined according to a desired depth or a depth heated by applying energy. it can. Although the magnitude | size at the time of making the said material into powder is not specifically limited, For example, the magnitude | size of 0.1-10 micrometers can be illustrated by a circle equivalent diameter.

  FIG. 1 shows a manufacturing process of an In—Ga—Zn—O-based semiconductor material. As shown in FIG. 1A, powders of In, Ga, and Zn materials (illustrated by I, Z, and G) are deposited on a substrate 1 together with a solvent on the substrate 1, and the substrate 1 is rotated at a high speed to cause In, Ga, and Zn. The material 2 and the solvent are uniformly applied on the substrate 1.

Note that a conventional In—Ga—Zn—O-based semiconductor material is formed by film formation by sputtering or vapor deposition or epitaxial growth as described above. The film formation layer is annealed as necessary. In the sputtering method, a target is decomposed to a molecular level with Ar ions or the like, and they are deposited on a substrate. In vapor deposition, metal or oxide is evaporated and adhered to the surface of the substrate, and is performed by physical vapor deposition (PVD) or chemical vapor deposition (CVD).
In the sputtering method and vapor deposition method, characteristics such as the film structure are almost determined at the stage of film formation, but a heat treatment furnace (around 300 ° C. is used to eliminate bond defects between molecules and obtain stable characteristics. ), Plasma irradiation, laser annealing and the like are performed. In epitaxial growth, the film characteristics of a semiconductor material are determined by the structure of the substrate on which the growth is based.
As a result, conventional In—Ga—Zn—O-based semiconductor materials have either n-type or p-type characteristics, and none have both n-type and p-type characteristics.

In this embodiment, an In—Ga—Zn—O-based semiconductor having the functions of the present invention is obtained by applying high energy to In, Ga, and Zn materials on a substrate to melt and intermolecularly bond the materials at the same time. A material is made. The heating temperature at the time of melting is desirably 1200 ° C. or higher. In this embodiment, by heating to a high temperature in a short time, molecules having different heat capacities can be melted (decomposed) and recombined.
Specifically, each material (preferably not bonded with different elements) is bonded at a molecular level by applying high energy, and oxygen in the atmosphere is taken in to obtain a multi-component oxide.

  The application of high energy can be preferably performed by beam irradiation of laser light 3 as shown in FIG. 1B. It is desirable that the laser light is formed into an appropriate beam shape such as a line shape or a spot shape, adjusted to an appropriate energy density, and irradiated to the In, Ga and Zn materials. Laser light irradiation can impart high energy to In, Ga and Zn materials without heating the entire substrate and TFT circuit, and the substrate material can be a low heat resistant material such as a resin film. There is an advantage that even fine metal wiring can be prevented from being disconnected by thermal migration.

  In the present invention, the type of the laser beam is not particularly limited, but a laser beam ranging from a green wavelength (450 to 570 nm; optimally 515 nm) to an infrared ray (up to 1100 nm) can be preferably used. A solid laser can be suitably used. In the above wavelength range, these materials can be effectively heated without passing through the In, Ga, and Zn materials. In particular, a laser beam with a green wavelength has a good balance between reflectance and transmittance, and an In—Ga—Zn—O-based semiconductor material having both n-type characteristics and p-type characteristics can be formed favorably.

  The laser light may be either a continuous wave or a pulse wave, but it is desirable to use a pulse wave because it can provide high energy in a short time. The repetition frequency and pulse width (half-value width) of the pulse wave are not particularly limited as the present invention, and examples include a repetition frequency of 1 kHz to 50 kHz and a pulse width (half-value width) of 200 to 1200 nm. .

Moreover, when irradiating a laser beam, it is necessary to determine an energy density appropriately. If the energy density is low, the effect of the present invention cannot be obtained. On the other hand, if the energy density is too high, In, Ga, and Zn are scattered by heat and semiconductor characteristics are deteriorated.
Proper energy density, In in the thickness of the substrate or on the substrate varies depending on the thickness of the Ga and Zn material, for ^example, may indicate a value of ^{0.1J / cm 2 ~10J / cm 2} .

  The In, Ga, and Zn materials 2 irradiated with the laser beam 3 are In-Ga-Zn-O-based semiconductors as multi-element oxides that are fused (decomposed) and recombined to bond In, Ga, and Zn. Material 2A is produced. In—Ga—Zn—O-based semiconductor materials have both p-type and n-type characteristics.

Next, the function of the In—Ga—Zn—O-based semiconductor material of this embodiment will be described below.
FIG. 2 schematically shows a crystal structure 200 of the In—Ga—Zn—O-based semiconductor material 2. In the crystal structure 200, In, Ga, Zn, and O are covalently bonded, and molecules are located in the cage of the crystal lattice.
Among conventional semiconductor materials, those having n-type characteristics are formed by adding an impurity such as As (arsenic) or P (phosphorus) to Si to form an n-type semiconductor. As a result, a current as shown in FIG. Has voltage characteristics. In this case, no current (Id) flows even when a voltage (Vd) is applied in the negative direction.
In addition, in the conventional semiconductor material having p-type characteristics, a p-type semiconductor is formed by adding impurities such as B (boron) to Si, and as a result, current and voltage characteristics as shown in FIG. 3B are obtained. Have. In this case, no current (Id) flows even when a voltage (Vd) is applied in the positive direction.

On the other hand, the In—Ga—Zn—O-based semiconductor material of this embodiment has both p-type and n-type characteristics. That is, when a negative voltage (−V) is applied to an In—Ga—Zn—O-based semiconductor material, as shown in FIG. 3A, semiconductor characteristics are shown in the negative direction (p-type characteristics), and voltage ( When + V) is applied, semiconductor characteristics (n-type characteristics) are shown in the plus direction as shown in FIG. 3B.
In the above example, P-ch and N-ch transistor-like operations are performed by applying a gate voltage in the plus (+) direction or minus (-) direction, as shown in FIG. CMOS operation). At this time, it is possible to operate without causing leakage current at the time of voltage switching.

Considering the above action, Hole moves by the flow 210 or the like using the covalently bonded portion (the cage portion 201) as a carrier, and exhibits p-type characteristics. Further, the molecule 202 restrained in the cage is returned and electrons flow as carriers 220 and move as carriers.
Although the above points do not go beyond estimation, the principle of movement of each carrier can be considered from the current electrical characteristics.

When a transistor is configured using the In—Ga—Zn—O-based semiconductor material of this embodiment as a channel layer, when a voltage applied to the gate is applied in the plus (+) direction, the current (I) is in the plus (+) direction. Increases (shows N-ch characteristics). When the voltage applied to the gate is applied in the minus (−) direction, the current (I) increases in the minus (−) direction (shows P-ch characteristics).
When the transistor is shown in an equivalent circuit, it can be shown in FIG. 4A. By changing the electric field direction, the current direction can be changed as shown in FIG. 4B.

Examples of the present invention will be described below.
As the test material, a commercially available In, Ga, Zn raw material solution for testing was used. In these raw material solutions, the powder size of each component was an equivalent circle diameter of 0.1 to 10 μm.
The raw material solution was applied (spread) onto a P-type silicon substrate with a spin coater, and the dispersion medium was volatilized and dried with a hot plate in the atmosphere. In this case, the coating amount of In, Ga, and Zn was 1: 1: 1 as a molar amount.
In the resistance measurement by the tester at this stage, the range was over (insulator). From this, it was confirmed that no binding occurred at the molecular level.

Next, the dried substrate was irradiated with a green laser (wavelength: 532 nm) using a solid laser to perform ablation. The oscillation frequency of the laser is 10 kHz, the pulse width (half width) was 600 nm, the energy density of the ^{1.0J / cm 2 ~5.0J / cm 2} .

As a result of measuring the resistance value in the plane of the thin film, it was confirmed that the film was electrically connected to 590 kΩ. Further, whether this sample is a semiconductor was evaluated by applying a probe to +-(forward direction) and-+ (reverse direction) on each of an In-Ga-Zn-O-based thin film and a P-type Si substrate. As a result of measuring the resistance value, there was a one-digit difference between the forward direction 820 kΩ and the reverse direction 7,000 kΩ. Since the activated In—Ga—Zn—O-based semiconductor material thin film exhibits n-type semiconductor characteristics, a PN junction (diode) is formed with the p-type silicon substrate if it is a semiconductor. If the sample In—Ga—Zn—O-based semiconductor material thin film + silicon substrate is a simple resistor, the same resistance value is exhibited both in the forward direction and in the reverse direction. However, the resistance value of the test material was different in both the forward and reverse directions, and thus it was confirmed to have semiconductor (diode) characteristics.
From the above results, an In—Ga—Zn—O-based semiconductor material can be manufactured by laser ablation.

(Example 2)
In the same manner as in Example 1, on the Si substrate, In, Ga and Zn materials were applied by spin coating using a commercially available raw material solution, and the dispersion medium was volatilized and dried. In this case, the coating amount of In, Ga, and Zn was 1: 1: 1 as a molar amount, and was applied on the Si substrate in an amount of 2 nm to 200 nm in thickness.
The In, with respect to Ga and Zn material, a green laser of a solid-state laser (wavelength 532 nm, the oscillation frequency 10 kHz, pulse width (half width) 600 ^nm), and energy in the range of 1.0J / cm ² ~4.5J / cm 2 Irradiation was performed while changing the density to obtain a specimen.

A voltage of −12 V to +12 V was applied to the thin film surface of each test material, the current obtained at that time was measured, and the value is shown in FIG. As shown in FIG. 5, when the energy density of the laser beam is low (2.5 J / cm ² , 3.0 J / cm ² ), the current hardly changes. Also, the energy density is too high, the electrical characteristics are worsened ^{(3.5J / cm 2 → 4.0J /} cm 2 → 4.5J / cm 2). In this embodiment, the optimum energy density of the laser beam under these conditions can be said to be 3.5 J / cm ² . When activation is performed using laser light, heat from the laser light becomes the maximum activation factor, and energy density becomes an important factor.
However, other than this, for example, wavelength, pulse width, stability, repeatability, irradiation time, and the like are factors. In addition to this, all factors that generally affect optically and thermally such as other environments such as film thickness and substrate type are factors.

(Example 3)
In the same manner as in Example 1, on the Si substrate, In, Ga and Zn materials were applied by spin coating using a commercially available raw material solution, and the dispersion medium was volatilized and dried. In this case, the coating amount of In, Ga, and Zn was 1: 1: 1 as a molar amount, and was applied on the Si substrate in an amount of 2 nm to 200 nm in thickness.
The In, with respect to Ga and Zn material, an infrared laser according to the solid-state laser (YAG laser) (wavelength 1064 nm, the oscillation frequency 10 kHz, pulse width (half width) 600 nm) ^{and, 1.0J / cm 2 ~4.5J / cm} 2 The sample was obtained by irradiating with changing the energy density in the range of.

The voltage for each specimen and the current obtained at that time were measured, and the values are shown in FIG. As shown in FIG. 6, when the energy density of the laser beam is low (3.0 J / cm ² or less), the current hardly changes. Also, the energy density is too high, the electrical characteristics are worsened ^{(3.5J / cm 2, 4.0J /} cm 2 → 4.5J / cm 2). In this embodiment, the optimum energy density of the laser light under this condition can be said to be 4.0 J / cm ² . When activation is performed using laser light, heat from the laser light becomes the maximum activation factor, and energy density becomes an important factor.

  As described above, the present invention has been described based on the above embodiment, but appropriate modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Substrate 2 In, Ga, and Zn material 2A In-Ga-Zn-O-based semiconductor material 3 Laser light

Claims (4)

In, Ga, an acid compound-based semiconductor material consisting of In-Ga-Zn-O-based compound as a constituent component of Zn and O,
An In, Ga, Zn material is disposed on a substrate, and in the presence of oxygen, the In, Ga, Zn material has an energy density of 0.1 J / cm ^{2 to} 10 J / cm ² , a repetition frequency of 1 kHz to 50 kHz, and a pulse width. (Half width) 200-1200 nm pulsed laser light is irradiated and heated to 1200 ° C. or higher to form an In—Ga—Zn—O-based compound that is molecularly bonded to each other on the substrate.
Wherein depending on the direction of the positive and negative electric field applied to the semiconductor material, the addition of negative electric field showed a p-type characteristics, oxide-based semiconductor material and having a positive characteristic that indicates the n-type characteristics when application of an electric field . Semiconductor devices that have a channel layer made of an oxide-based semiconductor material according to claim 1, a source and a drain, characterized in that it comprises a gate. The semiconductor element according to claim 2 , wherein a voltage for switching between positive and negative is applied to the gate. 4. The semiconductor element according to claim 3 , wherein the semiconductor element functions as a CMOS by switching between positive and negative voltages applied to the gate.

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