KR101500175B1 - High density oxide sintered body and novel thin film transistor comprising the same - Google Patents

Abstract

The objective of the present invention is to provide two kinds of oxide pellets having a composition similar to high density, a novel thin film transistor which is formed from the oxide pellet to minimize damage to an oxide semiconductor layer and has excellent device properties and stability, and a method for manufacturing the same. To achieve the objective, a ZnO-based thin film is deposited on an oxide semiconductor to have a double layer structure, thereby minimizing damage to an oxide semiconductor layer in a bottom gate structure, providing an amorphous oxide having a high electron carrier concentration, and providing a thin film transistor having excellent device properties by using the amorphous oxide as a channel layer.

Description

TECHNICAL FIELD [0001] The present invention relates to a high-density oxide sintered body and a novel thin-film transistor element including the same. BACKGROUND OF THE INVENTION [0002]

The present invention relates to a novel thin film transistor having two kinds of oxide sintered bodies having a composition similar to high density and a sintered body formed of the sintered body so as to minimize the damage of the oxide semiconductor layer and realize excellent characteristics and stability of the element.

Among the elements of a liquid crystal-based display, thin film transistors which drive a device by displaying a driving voltage are widely used. The thin film transistor is composed of a gate electrode, an insulating film, a semiconductor layer, and a source / drain electrode. The semiconductor layer must be electrically stable and excellent in etching property. The silicon-based material has an advantage of excellent electrical stability and processability, but has a disadvantage in that it may cause malfunction of the thin film transistor due to generation of carriers due to light incidence due to absorption of a visible light region. Further, in the case of a silicon-based material, since a high-temperature process of about 200 ° C or more is required in forming amorphous silicon, the production cost is increased and deposition on a polymer substrate is difficult.

Accordingly, thin film transistors using transparent oxide semiconductors instead of the silicon-based materials have been actively developed. Transparent oxide semiconductors can be formed on a substrate without heating, exhibit a mobility of about 10 cm ² / Vs or more, and the structure of the thin film transistor can be simply changed compared to the case of using a conventional silicon-based material. As a material of the transparent oxide semiconductor, an InGaZnO-based material containing indium, gallium, zinc, and oxygen as a constituent element is typical. InGaZnO can be formed by a vapor phase method such as a sputtering method, a pulsed laser deposition method, and an electron beam evaporation method by forming a polycrystalline sintered body of InGaO ₃ (ZnO) _x as a target, and the sputtering method is most suitable for mass production.

In the conventional thin film transistor using the above-mentioned transparent oxide, the oxide semiconductor layer is deposited and then chemically etched. In the chemical etching, the oxide semiconductor layer is damaged by the etching solution, and the device characteristics are degraded. Particularly, in the bottom gate structure, because the Mo-based material is used as the material of the source electrode and the drain electrode, it is necessary to etch the oxide semiconductor layer with a strong acid, thereby easily damaging the oxide semiconductor layer. Accordingly, there is a need for a novel technique capable of minimizing damage to the oxide semiconductor layer and realizing excellent characteristics of the device.

SUMMARY OF THE INVENTION The present invention has been conceived in order to solve the above-mentioned problems, and it is an object of the present invention to provide a method of manufacturing a semiconductor device, which comprises depositing an oxide semiconductor layer of a thin film transistor and then depositing a thin film sacrifice layer of ZnO- The damage of the oxide semiconductor layer by chemical etching is minimized and the characteristics of the device can be excellently realized.

Accordingly, it is an object of the present invention to provide two types of oxide sintered bodies having similar components that can be used as the above-described oxide semiconductor layer and thin film sacrificial layer.

Further, the oxide semiconductor layer and the thin film sacrifice layer having the same composition as the oxide semiconductor layer are deposited in a double layer structure in the thin film transistor using the two types of oxide sintered bodies described above, so that the damage of the oxide semiconductor layer can be minimized It is another object of the present invention to provide a method for manufacturing a thin film transistor and a bottom gate type thin film transistor manufactured by the method.

(M1 + Zn) / (M1 + In + Sn) atoms constituted of an oxide containing indium oxide, tin oxide and a metal ion M1 (Hf, V, Al) And 0.05 to 40 atomic%, based on the total volume of the oxide sintered body.

Further, the present invention is characterized in that it is composed of an amorphous oxide containing zinc oxide and a metal ion M2 (In, Ga, Al), and the ratio of the number of (M2) / (M2 + Zn) atoms is 0.01 to 10 atomic% The oxide sintered body for forming the thin film transistor sacrificial layer.

According to another aspect of the present invention, there is provided a semiconductor device comprising at least a gate electrode, an insulating film, a channel layer made of an oxide semiconductor, a sacrificial layer, a source electrode, and a drain electrode on a substrate, wherein a sacrificial layer is formed on the channel layer, Wherein the sacrificial layer is formed from the oxide sintered body for sacrificial layer formation and the channel layer is formed from an oxide sintered body for forming a channel layer.

Here, the channel layer and the sacrificial layer are preferably made of an amorphous oxide having the same composition. The thickness of the sacrificial layer is preferably in the range of 50 to 1000 angstroms.

In the present invention, it is preferable that the source electrode and the drain electrode are made of molybdenum or a molybdenum alloy.

According to another preferred embodiment of the present invention, the gate electrode is provided under the channel layer, and the source electrode and the drain electrode are formed on the sacrificial layer in such a manner as to be in contact with both ends of the channel layer. .

In addition, the present invention provides a method of manufacturing the above-described thin film transistor.

As a preferable example of the above-described manufacturing method, there are a step of forming a gate electrode on a substrate; Forming an insulating layer on the gate electrode; Forming a channel layer made of an oxide semiconductor on the gate insulating layer; A sacrificial layer made of amorphous oxide containing zinc oxide and metal ions M2 (In, Ga, Al) and containing 0.01 to 10 atomic% of (M2) / (M2 + Zn) Forming a layer; Forming a drain electrode and a source electrode on the sacrificial layer; And a step of removing the sacrificial layer exposed between the drain electrode and the source electrode by wet etching.

Furthermore, the present invention provides a flat panel display device including the thin film transistor described above. Here, the flat panel display device may be a liquid crystal display device or an organic light emitting display device.

In the present invention, a sacrificial layer having a composition similar to that of the oxide semiconductor is deposited on the oxide semiconductor layer in a double layer structure to minimize the damage of the oxide semiconductor layer during the chemical etching process, .

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram showing mobility characteristics of a transistor manufactured in Examples 1 to 3 and Comparative Example 1. FIG.
2 is a diagram showing mobility characteristics of a transistor manufactured according to the second embodiment.
3 is a graph showing mobility characteristics of the transistor manufactured in Comparative Example 1. FIG.

Hereinafter, the present invention will be described in detail.

In a conventional thin film transistor using a transparent oxide, the oxide semiconductor layer is deposited and then chemically etched. However, the oxide semiconductor layer undergoes damage during the etching, resulting in degradation of device characteristics. Particularly, in a bottom gate structure using a Mo-based material as a material of a source electrode and a drain electrode, it is necessary to etch the gate electrode with a strong acid, which degrades the characteristics of the device by chemical etching.

In order to solve the above-described problems, the present invention provides a novel thin film transistor formed by depositing a thin film sacrifice layer having a ZnO-based composition similar to that of the semiconductor layer on an oxide semiconductor layer of a thin film transistor to form a double layer structure, The method comprising the steps of:

That is, when the components of the oxide semiconductor layer (channel layer) and the sacrifice layer are similar to each other, the channel layer can be protected by the presence of the sacrificial layer because the etch rates are similar during chemical etching.

In the present invention, since the ZnO-based thin film deposited as the sacrificial layer is a thin oxide film of the same ceramic type as the oxide semiconductor used as the channel layer, for example, InSnZnO, if the semiconductor layer having the similar composition and the sacrifice layer are formed as a double layer, There is no diffusion between these compositions at the time of etching and the oxide semiconductor composition is not affected.

In addition, when the oxide semiconductor and the sacrificial layer are formed in a double layer structure, the damage to the semiconductor layer can be minimized in a bottom gate structure, and an amorphous oxide having a high electron carrier concentration can be provided. It is possible to stably realize the characteristics of an excellent thin film transistor device using as a channel layer.

≪ Sintered body for oxide semiconductor film formation &

The oxide semiconductor layer used as the channel layer of the thin film transistor according to the present invention can be formed by forming an oxide sintered body as a sputtering target.

In the present invention, the oxide sintered body for oxide semiconductor film formation is composed of an oxide containing indium oxide, tin oxide and metal ion M1 (Hf, V, Al), and (M1 + Zn) / (M1 + And may be contained in an amount of 0.05 to 40 atomic% in atomic ratio.

For example, oxides specified by the metal ion M1 (Hf, V, Al) are added to the indium oxide powder and the tin oxide powder in the range of 0.05 to 40 atomic% in terms of the number of (M1 + Zn) / (M1 + May be used.

The oxide-sintered body has the above-described composition and has a relative density of 95% or more and a specific resistance of 1 x 10 < ^-2 > At this time, when the relative density of the oxide-sintered body is less than 95%, there is a high possibility that an abnormal discharge occurs due to generation of nodules when the film is used as a sputtering target.

Here, the relative density is a value calculated by (actual density / theoretical density) x 100 of the sintered body. For the actual density, the density is calculated by measuring the sintered body at 1 atm and 4 ° C water.

In the case where the oxide-sintered body has a composition of (M1 + Zn) / (M1 + In + Sn) atomic ratio of 0.05 to 40 atomic%, the metal ion M1 (Hf, V, Al) Oxygen in the sintered body is adsorbed to exhibit a slight decrease in mobility, which is an element characteristic of the transistor, but excellent characteristics can be observed from the viewpoint of light reliability. However, when the atomic ratio of (M + Zn) / (M + In + Sn) is less than 0.05 atomic%, the influence of the added element is small and the improvement of device characteristics is insufficient.

In the present invention, an oxide-sintered body can be produced by a conventional method known in the art, except that the metal oxide of the above-mentioned composition is used. In one preferred embodiment of the method, a slurry is prepared by mixing indium oxide powder, tin oxide powder, and an oxide including the above metal ion M1 (Hf, V, Al), followed by milling, drying and pulverizing, A step of molding water, and a step of sintering the molded article.

The indium oxide or tin oxide may be used without limitation in the conventional components known in the art. For example, they may be In ₂ O ₃ or SnO < ₂ >.

When mixing the above-mentioned powders, additives such as binders, dispersants, defoamers, etc., which are known in the art, may be added as needed.

The dispersant is added in order to satisfy the purpose of finely pulverizing the particles while maintaining a stable dispersion evenly in the solution for a long time in the pulverized raw material particles. Nonlimiting examples of usable dispersing agents include organic acid-based ones having a carboxyl group such as citric acid, polyacrylic acid (PAA) or a salt thereof, a copolymer, or a combination thereof. The dispersant may be used in an amount of 0.5 to 3% by weight based on the weight of the powder in the slurry.

The binder is added in order to maintain the molding strength of the formed body in the process of drying the slurry after the powder is dried. Non-limiting examples thereof include polymers such as polyvinyl alcohol and polyethylene glycol. The amount of the binder used may be in the range of 0.01 to 5% by weight based on the powder in the slurry.

The antifoaming agent is used for removing bubbles in the slurry, and silicone oil, octyl alcohol, boric acid and the like can be usually used. The amount of the antifoaming agent used may be in the range of 0.001 to 0.01% by weight relative to the powder in the slurry.

The slurry prepared by mixing indium oxide powder, tin oxide powder, metal oxide containing metal ions, water and additives is milled and dried to prepare a dry powder.

The milling may be carried out using a conventional ball mill, bead mill or the like known in the art. The viscosity of the slurry obtained through milling is preferably adjusted to 100 cps or less.

The milled slurry is spray-dried using a spray dryer or the like to obtain a dry powder.

Thereafter, the dried powder is subjected to a molding step of producing a molded body having a predetermined shape. It is preferable to use a cold isostatic press (CIP) in consideration of the convenience of the process at the time of manufacturing the molded article.

After the above-described molding step, an oxide sintered body for forming an oxide semiconductor film is produced through a sintering step. The sintering step may be performed in an oxygen gas atmosphere, an inert gas atmosphere, or an oxygen-inert gas mixed atmosphere. The sintering step may be carried out at a temperature in the range of 1000 to 1650 ° C under an atmosphere of oxygen gas or inert gas, or by sintering the shaped body at 900 to 1600 ° C under a pressurized condition of an oxygen or inert gas atmosphere. The pressure conditions may be using the CIP 2 to 3 ton / cm ² range.

In the present invention, a sintered body for forming an oxide semiconductor film having the above-described composition and physical properties is formed on a substrate by a sputtering method, and the formed amorphous oxide thin film is used as a channel layer of the thin film transistor. For example, the manufactured sintered body is processed into a predetermined size and shape and attached to a cooling metal plate or a backing plate to be used as a sputtering target. In this case, an oxide semiconductor thin film used as a channel layer of the thin film transistor can be manufactured by supplying argon gas mixed with oxygen gas in the range of 0 to 1% in a vacuum tank at a rate of 80 sccm.

≪ Sintered oxide for sacrificial layer deposition >

In the thin film transistor according to the present invention, a sacrifice layer having the same or similar composition is formed as a double layer on the oxide semiconductor layer used as the channel layer.

This sacrificial layer can be formed by depositing a sintered oxide for sacrificial layer formation as a sputtering target.

In the present invention, the oxide sintered body for sacrificial layer formation may be an amorphous oxide having the same or similar composition as the oxide sintered body constituting the above-described oxide semiconductor. If the composition of the channel layer and the sacrifice layer are close to each other, the channel layer is not damaged and the resistance is not reduced. In addition, since the channel layer is not damaged during chemical etching, a thin film field effect transistor having good TFT characteristics and high reliability can be obtained.

At this time, the oxide sintered body constituting the sacrificial layer is composed of an amorphous oxide containing zinc oxide and metal ions M2 (In, Ga, Al), and the ratio of (M2) / (M2 + Zn) %. ≪ / RTI >

In the present invention, the metal ion M2 (In, Ga, Al) is dissolved in the zinc oxide target when the sacrificial layer has a (M2) / (M2 + Zn) atomic ratio of 0.01 to 10 at% The etch rate is reduced to minimize the damage of the oxide semiconductor layer.

In the present invention, an oxide sintered body for sacrificial layer formation can be produced by a conventional method known in the art, except that the metal oxide of the above-mentioned composition is used. Can be carried out in the same manner as the above-mentioned production method of a sintered body for oxide semiconductor film formation.

An oxide sintered body for forming an oxide sacrificial layer having the above composition and physical properties is formed on a channel layer by a sputtering method, and the formed amorphous oxide thin film is used as a sacrificial layer of a thin film transistor.

The thickness of the sacrificial layer formed by the deposition is preferably in the range of 50 to 1000 angstroms, but is not particularly limited thereto and can be appropriately adjusted within the range known in the art.

<Thin Film Transistor>

A thin film transistor (TFT) according to the present invention includes at least a gate electrode, an insulating film, a channel layer made of an oxide semiconductor, a sacrificial layer, a source electrode, and a drain electrode on a substrate.

Such a thin film transistor is an active element having a function of applying a voltage to a gate electrode, controlling a current flowing to a channel layer, and switching a current between a source electrode and a drain electrode.

 In the thin film transistor of the present invention, a sacrifice layer is formed on the channel layer, and a source electrode and a drain electrode may be formed on the sacrifice layer. Preferably, the gate electrode is provided under the channel layer, and the source electrode and the drain electrode are bottom gate type provided to contact the both ends of the channel layer on the sacrificial layer.

The substrate can be any material used for a substrate of a conventional semiconductor device. For example, silicon (Si), glass, inorganic materials, organic materials or metals may be used without limitation.

In this case, the thickness of the substrate is not particularly limited, and when the flexible substrate is used, the thickness is preferably in the range of 50 to 500 mu m. If the thickness of the flexible substrate is less than 50 mu m, it is difficult to maintain sufficient flatness of the substrate itself. If the thickness of the flexible substrate exceeds 500 mu m, flexibility of the substrate itself becomes insufficient and it is difficult to bend the substrate itself It is because.

The substrate may have a moisture barrier layer (gas barrier layer) formed on its surface or back surface to prevent permeation of water vapor and oxygen. As the material of the moisture permeation preventing layer (gas barrier layer), an inorganic material such as silicon nitride and silicon oxide is suitably used. The moisture barrier layer (gas barrier layer) can be formed by, for example, high-frequency sputtering. When a thermoplastic substrate is used, a hard coat layer, an undercoat layer, or the like may be further formed as necessary.

The gate electrode is for applying a voltage to turn on / off the thin film transistor. The gate electrode may be formed using a conductive material such as a metal or a metal oxide. For example, the gate electrode may be formed of a metal such as Pt, Ru, Au, Ag, Mo, Al, W, or Cu or an alloy thereof, IZO (InZnO) A metal such as AZO (AlZnO) or a conductive oxide may be used, or an organic conductive compound such as polyaniline, polythiophene, and polypyrrole, or a mixture thereof may be used.

As the gate electrode, it is preferable to use Mo, Mo alloy or Cr from the viewpoint of reliability of TFT characteristics. The thickness of the gate electrode may be in the range of, for example, 10 nm to 1000 nm.

The method of forming the gate electrode is not particularly limited. For example, the gate electrode is formed by a physical method such as a wet method such as a printing method or a coating method, a vacuum evaporation method, a sputtering method, and an ion plating method, or a chemical method such as CVD or plasma CVD. Of these, the formation method can be appropriately selected in consideration of suitability with the material constituting the gate electrode. For example, when a gate electrode is formed using Mo or Mo alloy, a DC sputtering method is used. When an organic conductive compound is used for the gate electrode, a wet film-forming method may be used.

The gate insulating film can be formed using an insulating material used in a typical semiconductor device, and silicon oxide or nitride can be used. For example, HfO ₂ , Al ₂ O ₃ , Si ₃ N ₄ , SiNx, YsO ₃ , Ta ₂ O ₅ , or a mixture thereof can be used as the high-K material having a dielectric constant higher than that of SiO ₂ or SiO ₂ . Or a double layer film made of these materials, or a polymer insulator such as polyimide may also be used.

The thickness of the gate insulating film is not particularly limited, and is preferably in the range of 10 nm to 10 mu m. The gate insulating film needs to have a certain thickness to some extent in order to increase the voltage resistance in order to reduce the leakage current. However, if the film thickness of the gate insulating film is increased, the driving voltage of the TFT is increased. Therefore, the thickness of the gate insulating film is more preferably 50 nm to 1000 nm in the case of the inorganic insulator, and more preferably 0.5 to 5 mu m in the case of the polymer insulator.

In addition, when a high dielectric constant insulator such as HfO ₂ is used for the gate insulating film, it is preferable to use a high dielectric constant insulator for the gate insulating film because the transistor can be driven at a low voltage even if the film thickness is increased.

In the present invention, the oxide semiconductor layer constituting the channel layer and the sacrifice layer formed on the channel layer may be composed of an oxide semiconductor thin film having the same or similar composition.

Since the oxide semiconductor layer and the sacrificial layer are produced by sputtering using the sintered body for oxide semiconductor film formation and the sintered body for sacrificial layer forming described above as sputtering targets although the difference in composition may occur depending on the deposition atmosphere, Are almost the same. Therefore, a metal oxide thin film having substantially the same composition as the above-described sintered body can be formed.

Here, the oxide semiconductor layer is composed of an oxide including indium oxide, tin oxide and metal ions M1 (Hf, V, Al) and has a ratio of (M1 + Zn) / (M1 + It is preferable that it is contained in atomic%. The sacrificial layer is made of an amorphous oxide containing zinc oxide and metal ions M2 (In, Ga, Al), and the ratio of (M2) / (M2 + Zn) desirable.

The source electrode and the drain electrode may be formed using a conductive material. For example, a metal such as Pt, Ru, Au, Ag, Mo, Al, W, or Cu, or a metal such as IZO (InZnO) or AZO The same metal or conductive oxide may be used. Preferably, it is made of molybdenum (Mo) or molybdenum alloy.

The source electrode and the drain electrode may be formed of a metal such as Al, Mo, Cr, Ta, Ti, Au or Ag or an alloy thereof, an alloy such as Al-Nd or APC, tin oxide, zinc oxide, A metal oxide conductive material such as indium tin oxide (ITO), indium zinc oxide (IZO), or the like. From the viewpoints of the reliability of the TFT characteristics and the etching rate with respect to the sacrificial layer, it is preferable to use an Mo or Mo alloy for the source electrode and the drain electrode. The thickness of the source electrode and the drain electrode may be, for example, in the range of 10 nm to 1000 nm.

The source electrode and the drain electrode may be formed according to a conventional method known in the art. For example, the source electrode and the drain electrode are formed by forming a film, forming a resist pattern on the film by photolithography, and etching the film.

The method of forming the film constituted by the source electrode and the drain electrode is not particularly limited. For example, a physical method such as a wet method such as a printing method or a coating method, a vacuum evaporation method, a sputtering method, an ion plating method, A chemical method such as a plasma CVD method, or the like.

In the present invention, when the source electrode and the drain electrode are formed of Mo or a Mo alloy, for example, a Mo film or an Mo alloy film is formed using DC sputtering, and then a Mo film or a Mo alloy film is coated with a resist pattern And the Mo film or the Mo alloy film is etched by the etching solution to form the source electrode and the drain electrode.

In addition to the above-described configuration, the present invention includes a protection layer for protecting a channel layer, a sacrificial layer, a source electrode, and a drain electrode, and insulating the electronic device manufactured on the transistor.

The protective layer may be formed by curing a conventional photosensitive or thermosetting resin composition known in the art or a resin composition containing a metal oxide, a metal nitride, a metal fluoride, or the like.

The method of forming the protective layer is not particularly limited and examples of the protective layer include vacuum vapor deposition, sputtering, reactive sputtering, MBE (molecular beam epitaxy), cluster ion beam, ion plating, plasma polymerization (high frequency excitation ion plating) , A plasma CVD method, a laser CVD method, a thermal CVD method, a gas source CVD method, a coating method, a printing method, or a transfer method.

<Thin Film Transistor Manufacturing Method>

Hereinafter, a method of manufacturing a thin film transistor according to the present invention will be described. However, the present invention is not limited to the following production methods, and the steps of each process may be modified or selectively mixed if necessary.

The thin film transistor of the present invention can be manufactured by a conventional method known in the art. According to a preferred embodiment thereof, there is provided a method of manufacturing a semiconductor device, comprising: forming a gate electrode on a substrate; Forming an insulating layer on the gate electrode; Forming a channel layer made of an oxide semiconductor on the gate insulating layer; A sacrificial layer made of amorphous oxide containing zinc oxide and metal ions M2 (In, Ga, Al) and containing 0.01 to 10 atomic% of (M2) / (M2 + Zn) Forming a layer; Forming a drain electrode and a source electrode on the sacrificial layer; And a step of removing the sacrificial layer exposed between the drain electrode and the source electrode by wet etching.

First, a substrate is prepared, and then a gate electrode is formed on the substrate.

As the substrate, a silicon substrate is generally used, but in addition, a glass substrate, a metal substrate, or a plastic substrate can be used.

The gate electrode may be formed by depositing a metal material on the substrate and patterning the metal material.

Next, a gate insulator is formed on the substrate so as to cover the gate electrode. Here, the gate insulating layer may be made of, for example, silicon oxide or silicon nitride.

Thereafter, a sacrifice layer similar in composition to the channel layer made of an oxide semiconductor is formed on the gate insulating layer.

At this time, the channel layer is composed of an oxide containing metal ions M1 (Hf, V, Al) in indium oxide powder and tin oxide powder, and has an atomic ratio of (M1 + Zn) / (M1 + In + Sn) % Of the oxide semiconductor sintered body is formed by the sputtering method, whereby the amorphous oxide thin film can be formed. Here, after performing the channel layer formed on the substrate, it is preferable that the proportion of additional _{O 2 / (Ar + O 2} ) to heat treatment at 100 ~ 400 ℃ in an atmosphere containing oxygen of 0.2 to 1.

The sacrificial layer is composed of an oxide sintered body having a composition similar to that of the oxide sintered body constituting the channel layer, that is, an amorphous oxide containing metal ions M2 (In, Ga, Al) M2 + Zn) atomic ratio of 0.01 to 10 atomic% is deposited by the sputtering method, whereby an amorphous oxide thin film can be formed. At this time, the thickness of the sacrificial layer is preferably adjusted to a range of 50 to 1000 angstroms.

Then, a drain electrode and a source electrode are formed on the sacrificial layer so as to be in contact with both ends of the channel layer on the sacrificial layer according to a conventional method known in the art. As an example, a molybdenum film can be prepared using a DC sputtering method to a thickness of 100 nm.

Thereafter, a resist film is formed on the molybdenum film, and a resist pattern is formed by photolithography. After the molybdenum film is etched with the wet etching solution, the resist film is peeled off. As a result, a source electrode and a drain electrode formed so as to cover the surface of the sacrificial layer and a part of the surface of the channel layer are obtained. The sacrificial layer exposed between the drain electrode and the source electrode is removed by wet etching so that the sacrificial layer is removed and the channel layer remains.

In the wet etching step, the etching rate of the sacrificial layer is not particularly limited, and is preferably in the range of 1 to 10 Å / sec. The etchant used for the wet etching may be any conventional etchant known in the art.

Then, a protective layer covering the channel layer, the sacrifice layer, the source electrode, and the drain electrode is formed, thereby completing the fabrication of the thin film transistor according to the present invention.

The thin film transistor according to the present invention can be applied as a switching device or a driving device to a flat panel display device such as a liquid crystal display device and an organic light emitting display device.

As described above, since the transistor according to the present invention has a mobility of 10 cm ² / vs or more, and is stable and has little change in characteristics due to light, when applied to a flat panel display device, reliability of the flat panel display device can be improved have. A liquid crystal display device, and an organic light emitting display device are well known, and a detailed description thereof will be omitted. The transistor according to the present invention can be applied to various fields of electronic devices such as a memory device and a logic device as well as a flat panel display device.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following Examples and Experimental Examples are merely illustrative of the present invention, and the scope of the present invention is not limited by the following Examples and Experimental Examples.

[Example 1]

1-1. Manufacture of transparent oxide sintered body

Indium oxide (In ₂ O ₃ ) having an average particle size of 1.0 탆, tin oxide (SnO ₂ ) having a particle size of 1.5 탆 and each oxide powder of metal ion M 1 were mixed with 44 atomic% indium, 12 atomic tin , 44 atomic% of zinc and 0.32 atomic% of additive compound M1 (Hf, V, Al), and the mixture was mixed to disperse the wet mixed slurry having the concentration of 55% with zirconia beads of 0.1 mm in a beads mill. The dispersed slurry was spray-dried, and the obtained granulated powder was pressure-molded and sintered at a flow rate of 25 L / min at 1100 to 1500 ° C for 10 hours. The oxide semiconductor target thus obtained had a relative density of 98% and a specific resistance of 3 x 10 &lt; ^-3 &gt; [Omega] cm. The sintered body was used as an oxide layer.

1-2. Sacrificial layer target  Produce

In the sacrificial layer target, zinc oxide (ZnO) having an average particle size of 1.0 占 퐉 of powder was mixed with respective oxidized powders of metal ions M2 at a ratio of 0.5 atomic% of indium, 0.3 atomic% of gallium, and 0.1 atomic% Weighed and then mixed to disperse the wet mixed slurry having a concentration of 55% with zirconia beads of 0.1 mm in a bead mill medium. The dispersed slurry was spray-dried, and the obtained granulated powder was pressure-molded and sintered at a flow rate of 25 L / min at 1100 to 1500 ° C for 10 hours. The relative density of the sacrificial layer target thus obtained was 99%, and the resistivity was measured to be 5 10 ^-3 ? Cm.

1-3. Thin Film Transistor Manufacturing

The thin film transistor may have a gate electrode G1 formed on a substrate (glass) B. The substrate B is any of various substrates that can be used in a general semiconductor device process such as a glass substrate, a metal substrate, a plastic substrate, and a plastic film. The gate electrode G1 may be generally formed of an electrode material. A gate insulating layer GI1 may be formed on the substrate B so as to cover the gate electrode G1.

The gate insulating layer GI1 may be a silicon oxide layer or a silicon nitride layer. In the bottom gate structure, the gate electrode G1 is provided under the channel layer A1, and the source electrode S1 and the drain electrode D1 are in contact with the upper surface of the channel layer A1. The power density was 0.5 to 3.6 W / cm ² using a high frequency (RF) sputter during the formation of the channel layer (A1) using a mixed gas of argon and oxygen. After forming the channel layer A1, a sacrificial layer (A2) was deposited, a pattern was formed, and then chemical etching was performed. Thereafter, a source electrode (S1) and a drain electrode (D1) were deposited and a pattern was formed. Then, the source electrode and the drain electrode were separated through chemical etching. At the time of chemical etching, the sacrificial layer on the channel layer is removed and only the channel layer is finally left.

After the heat treatment temperature in the further after the sputter film formation on the substrate (B), O ₂ / atmosphere containing oxygen in a 0.2 to 1 ratio of the (Ar + O ₂₎ was carried out at 100 ~ 400 ℃.

As a method of measuring the device characteristics, a voltage of 0.1 V and 10 V was applied to the drain electrode D 1 and the source electrode S 1 of the transistor to observe a change in the characteristics of the transistor . As a result of measuring the characteristics of the transistor, the results shown in Fig. 1 were obtained.

[Example 2]

An oxide-sintered body was produced in the same manner as in Example 1.

The sacrificial layer target was prepared by adding each oxide powder of metal ion M2 to zinc oxide (ZnO) having an average particle size of powder of 1.0 占 퐉 in a proportion of 0.5 atomic% of indium, 0.5 atomic% of gallium, 0.5 atomic% Were weighed and mixed, and the wet mixed slurry having a concentration of 55% was dispersed in zirconia beads of 0.1 mm in a bead mill medium. The dispersed slurry was spray-dried, and the obtained granulated powder was press-molded and sintered at a flow rate of 25 L / min at 1100 to 1500 ° C for 10 hours. The relative density of the thus-obtained sacrificial layer target was 99%, and the specific resistance was measured to be 3 x 10 &lt; ^-3 &gt;

The sintered body was used to fabricate a transistor as in Example 1, and the device was measured. As a result, excellent device characteristics as shown in FIGS. 1 and 2 were realized.

[Example 3]

An oxide-sintered body was produced in the same manner as in Example 1.

In the sacrificial layer target, zinc oxide (ZnO) having an average particle size of powder of 1.0 占 퐉 was coated with each oxide powder of metal ion M2 in an amount of 1.0 atomic% of indium, 1.0 atomic% of gallium and 1.5 atomic% Weighed and then mixed to disperse the wet mixed slurry having a concentration of 55% with zirconia beads of 0.1 mm in a bead mill medium. The dispersed slurry was spray-dried, and the obtained granulated powder was pressure-molded and sintered at a flow rate of 25 L / min at 1100 to 1500 ° C for 10 hours. The relative density of the sacrificial layer target thus obtained was 99%, and the specific resistance was measured to be 4 x 10 &lt; ^-3 &gt;

Using the sintered body, a transistor was fabricated as in Example 1 and the device was measured. As a result, the same result as in FIG. 1 was obtained.

[Comparative Example 1]

An oxide-sintered body was produced in the same manner as in Example 1.

The sacrificial layer target was prepared by dispersing a zinc oxide (ZnO) powder having an average particle size of 1.0 탆 in powder with a wet mixed slurry having a concentration of 55% in 0.1 mm zirconia beads mill media. The dispersed slurry was spray-dried, and the obtained granulated powder was press-molded and sintered at a flow rate of 25 L / min at 1100 to 1500 ° C for 10 hours. The relative density of the oxide semiconductor target thus obtained was 99%, and the specific resistance was measured to be 5 x 10 &lt; ^-1 &gt;

Using the sintered body, a transistor was fabricated as in Example 1, and the device was measured. As a result, the results shown in Fig. 3 were obtained.

Claims (12)

(M1 + Zn) / (M1 + In + Sn) atoms in an amount of 0.05 to 40 atomic% based on the total of the indium oxide, tin oxide and the metal ion M1 (Hf, V, Wherein the oxide sintered body for forming a thin-film transistor channel layer is formed on the substrate. (M2) / (M2 + Zn) atoms is contained in an amount of 0.01 to 10 atomic%, the amorphous oxide comprising zinc oxide and an amorphous oxide containing metal ions M2 (In, Ga, Al) Oxide sintered body for forming a sacrificial layer. A semiconductor device comprising at least a gate electrode, an insulating film, a channel layer made of an oxide semiconductor, a sacrificial layer, a source electrode and a drain electrode on a substrate,
A sacrificial layer is formed on the channel layer, and a source electrode and a drain electrode are formed on the sacrificial layer,
Wherein the sacrificial layer is formed from the oxide sintered body of claim 2, and the channel layer is formed from the sintered body of claim 1. The thin film transistor according to claim 3, wherein the thickness of the sacrificial layer is in the range of 50 to 1000 angstroms. delete The thin film transistor according to claim 3, wherein the source electrode and the drain electrode are made of molybdenum or a molybdenum alloy. The thin film transistor according to claim 3, wherein the substrate is selected from the group consisting of a glass substrate, a plastic substrate, and a metal substrate. The semiconductor device according to claim 3, wherein the gate electrode is provided under the channel layer,
Wherein the source electrode and the drain electrode are bottom gates provided on both sides of the channel layer on the sacrificial layer. A flat panel display comprising the thin film transistor according to claim 3. Forming a gate electrode on a substrate;
Forming an insulating layer on the gate electrode;
(M1 + Zn) / (M1 + In + Sn) atomic ratio in the range of 0.05 to 40 atoms, which is composed of an oxide containing indium oxide, tin oxide and metal ions M1 (Hf, V, % To form a channel layer from the oxide semiconductor sintered body;
Wherein an oxide of an amorphous oxide containing zinc oxide and metal ions M2 (In, Ga, Al) and containing an atomic ratio of (M2) / (M2 + Zn) in an amount of 0.01 to 10 atomic% Forming a sacrificial layer from the sintered body;
Forming a drain electrode and a source electrode on the sacrificial layer; And
Removing the sacrificial layer exposed between the drain electrode and the source electrode by wet etching;
Wherein the thin film transistor is formed on the substrate. The method of claim 10, wherein the sacrificial layer has an etching rate in the range of 1 to 10 Å / sec. The method according to claim 10, wherein the channel layer is formed by sputtering on the substrate and further heat-treated at 100 to 400 ° C in an atmosphere containing 0.2 to 1 O ₂ / (Ar + O ₂ ) Wherein the thin film transistor is formed on a substrate.

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