KR101067763B1 - Method for Preparing Ag Doped Transparent Conductive Tin Oxide - Google Patents

Abstract

The present invention relates to a method for producing a silver-doped transparent tin oxide film. The method of manufacturing a silver-doped transparent tin oxide film according to the present invention may be obtained by simultaneously depositing silver and tin oxide, and then heat treating it. The transparent oxide film prepared as described above has a very low resistance and may be used as a transparent electrode of various electronic devices.

Metal doped, transparent, conductive, oxide

Description

Method for Preparing Transparent Tin Oxide Doped with Silver {Method for Preparing Ag Doped Transparent Conductive Tin Oxide}

The present invention relates to a method for producing a silver-doped transparent tin oxide film. More particularly, the present invention relates to a method of manufacturing a silver oxide doped tin oxide film by simultaneously depositing silver and tin oxide, and thermally treating the tin oxide.

The present invention is derived from a task performed as a part of the IT source project of the Ministry of Knowledge Economy and ICT Research Project [Task No .: 2006-S-079-03, Task name: Smart window using a transparent electronic device].

Generally, transparent electrodes can be classified into four types according to materials.

The first is an ITO-based transparent electrode material. The ITO-based transparent electrode is most commonly manufactured by mixing In ₂ O ₃ and SnO ₂ in a weight ratio of 90:10. In addition, there are derivative techniques for adjusting the work function by adding ZnO to the ITO series or for changing the crystallinity. Recently, many proposals have been made to add a third element to the ITO base. However, due to the high price of In ₂ O ₃ , which is the biggest disadvantage of the ITO transparent electrode, continuous research on the transparent electrode material without using indium is ongoing. It is becoming.

Second is a non-ITO-based transparent electrode material. As the non-ITO-based transparent electrode material, a transparent conductive oxide thin film doped with Al or Ga based on ZnO is generally used. However, it has a disadvantage in that it is inferior to ITO in terms of conductivity. In order to solve the conductivity problem, a study of adding a dopant such as In or B has been attempted, but it is difficult to obtain conductivity of about ITO.

Third is a metal doped transparent conductive oxide material. According to the literature, a transparent conductive film is prepared using In ₂ O ₃ as a basic oxide and doped with various metals such as W, Ti, Zr, Nb, Mo, or Ni using an Al-doped ZnO target. In some cases, a transparent conductive film is manufactured by co-doping the same metal.

The fourth layer is a multilayer transparent electrode in which oxides and metals are laminated with oxides / metals / oxides. In the transparent electrode of this structure, the metal usually has a thickness of about 10nm, Ag, Pt, Au, Al, etc. may be used as the metal. Although the transparent conductive film of such a multilayer film structure can significantly lower the resistance, a problem may occur in the patterning process due to the difference in etching characteristics due to the heterogeneous thin film.

The metal doped transparent electrode systems thus far found are as follows.

Host and Related Dopant Materials in a Typical TCO Thin Film Two-component Dopant resistance toxicity ZnO

CdO
In2O3

Ga2O3
SnO2
TiO2 Al, Ga, B, In, Y, Sc, V, Si, Ge, Ti, Zr, Hf // F
In, Sn
Sn, Ge, Mo, Ti, Zr, Hf, Nb, Ta, W, Te // F
Sn
Sb, As, Nb, Ta // F
Nb, Ta ⊙

⊙
⊙

△
○
△
××
× Samsung Dopant MgIn2O4
GaInO3
(Ga, In) 2O3
CdSb2O6
SrTiO3
Sn, Ge

Y
Nb, La △

△
△
×


× Samsung Multicomponent resistance toxicity Zn2In2O5
(Zn3In2O6)
In4Sn3O12
CdIn2O4
Cd2SnO4
(CdSnO3)
Zn2SnO4
(ZnSnO3) ZnO-In2O3 System

In2O3-SnO2 System
CdO-In2O3 System
CdO-SnO2 System

ZnO-SnO2 System

ZnO-In2O3-SnO2 System
CdO-In2O3-SnO2 System
ZnO-CdO-In2O3-SnO2 System ○

○
○
○

△

○
○
○


×
×




×
×  ⊙: Very good, ○: Excellent, △: Average, ×: Poor, ××: Very bad

Accordingly, the inventors of the present invention conducted a study on a transparent conductive film, using tin oxide as an oxide film, and using silver as a dopant, while forming an oxide film and simultaneously infiltrating a metal into the oxide film, and then heat-treating it. It was found that a low transparent conductive film could be obtained and completed the present invention.

Therefore, the first technical problem of the present invention is to provide a method of manufacturing a silver-doped transparent tin oxide film which can lower the resistance.

The second technical problem of the present invention is to provide a transparent tin oxide film doped with silver.

In order to solve the first technical problem, the present invention provides a method for manufacturing a silver-doped transparent tin oxide film, the step of simultaneously depositing silver and tin oxide so that the metal is doped into the oxide film at the same time as the oxide film formation and the silver-doped tin It provides a method for producing a transparent tin oxide film doped with silver, characterized in that it comprises the step of heat-treating the oxide film.

In the method for producing a silver-doped transparent tin oxide film according to the present invention, the deposition step is preferably performed under an inert environment.

In addition, in the method of manufacturing a silver-doped transparent tin oxide film according to the present invention, the method may further include coating the silver-doped transparent tin oxide film with a metal equal to or different from the doped metal within a thickness range of 1 to 3 nm. , Where the other metals are Mo, Ti, Cu, Sr, Ge, Mg, Y, Zr, B, V, Ta, Ti, Ir, Te, Sb, Cr, Fe, Co, Ru, Au, Pt, Me, Ni It is preferable to select at least one kind from the group consisting of Sn, Bi, Al, Ga and In.

In the method for producing a silver-doped transparent tin oxide film according to the present invention, the content of silver is preferably 0.1 to 15% by weight, and the content of tin oxide is preferably 85 to 99.9% by weight.

In the method for producing a silver-doped transparent tin oxide film according to the present invention, the deposition is preferably performed using a sputter, an evaporator or an ion-gun.

The effects of the present invention are as follows.

First, the transparent oxide film according to the present invention can replace expensive ITO.

Second, the transparent oxide film according to the present invention can lower the resistance, which is suitable for electronic devices.

The method for manufacturing a silver-doped transparent tin oxide film according to the present invention includes simultaneously depositing silver and tin oxide and heat-treating the deposited oxide film, and thus silver penetrates into the oxide film at the same time as the tin oxide film is formed.

In the method of manufacturing a silver-doped transparent tin oxide film according to the present invention, after the step of simultaneously depositing silver and tin oxide, 1 to 3 nm of the same or different type of metal as the doped metal on the silver-doped tin oxide film is obtained. The method may further include coating in a thickness range.

The other metals include Mo, Ti, Cu, Sr, Ge, Mg, Y, Zr, B, V, Ta, Tl, Ir, Te, Sb, Cr, Fe, Co, Ru, Au, Pt, Me, Ni At least one selected from the group consisting of, Sn, Bi, Al, Ga and In is preferable.

Deposition of the silver and tin oxide simultaneously is carried out using a device such as a sputter, evaporator or ion-gun. Here, co-deposition can be deposited on the substrate via a device having Target 1 and Target 2 or Gun 1 and Gun 2 each containing silver and tin oxide, as shown in FIG. 1. Preferably, the metal target (or gun) is DC, and the oxide target (or gun) is RF, but in some cases, both may be DC or RF.

In addition, the deposition may be performed under an oxygen-free atmosphere, that is, under an inert environment, for example, under inert gas such as argon (Ar), helium (He), neon (Ne), and the like.

In addition, in silver and tin oxide which are deposited simultaneously, silver is preferably used in the range of 0.1 to 15% by weight, and tin oxide is preferably used in the range of 85 to 99.9% by weight. When silver is used in excess of 15% by weight, its use may be limited to transparent electrodes because of poor permeability.

In addition, in the method of manufacturing a silver-doped transparent tin oxide film according to the present invention, after the step of simultaneously depositing silver and tin oxide, a step of heat-treating the silver-doped tin oxide film is performed. Here, the heat treatment is performed for 30 minutes to 2 hours at a temperature of 250 to 350 ℃, it is possible to improve the electrical properties through the heat treatment.

The transmittance of the silver-doped transparent tin oxide film thus prepared has 50% to 90%.

The transparent conductive film manufactured by the method of manufacturing the silver-doped transparent tin oxide film according to the present invention can be applied to various electronic devices including thin film transistors.

The thin film transistor may have a structure as shown in FIGS. 2 to 5. 2 to 5 are diagrams showing the structure of a thin film transistor. Referring to FIG. 2, the thin film transistor may include an upper gate inverted nose in which a source / drain electrode 20, a channel layer 30, a gate insulating film 40, and a gate electrode 50 are sequentially formed on a substrate 10. -Planar type structure, Referring to FIG. 3, the upper gate in which the channel layer 30, the source / drain electrode 20, the gate insulating film 40, and the gate electrode 50 are sequentially formed on the substrate 10. FIG. 4, a lower gate in which a gate electrode 50, a gate insulating film 40, a source / drain electrode 20, and a channel layer 30 are sequentially formed on a substrate 10. 5, the gate electrode 50, the gate insulating film 40, the channel layer 30, and the source and drain electrodes 20 are sequentially formed on the substrate 10. It may have a lower gate inverse staggered structure.

For convenience, each layer will be described in detail with reference to the thin film transistor of the upper gate co-planar type structure of FIG. 2.

Glass, silicon and plastic may be used as the substrate 10, but are not limited thereto.

The silver oxide doped tin oxide film described above may be used as the source / drain electrode 20 formed on the substrate 10, and may be patterned after the oxide film is formed.

The channel layer 30 constituting the channel region on the source / drain electrode 20 may be formed using any material known in the art, such as sputtering, evaporating, E-beam, ALD, and laser deposition. The process may be formed to a conventional thickness in the art, and is formed of, for example, ZnO, In—Ga—Zn—O, Zn—Sn—O, In 2 O 3, In—Zn—O, or the like, which are oxide semiconductors.

The gate insulating layer 40 formed on the channel layer 30 may be a transparent oxide or nitride, for example, SiNx, ATO (AlOx + TiOx), TiO ₂ , AlOx, TaOx, HfOx, SiON, SiOx and other high dielectric materials. It can include any one or more of the (high-k) materials. In addition, a thin film using a polymer is possible. In addition, the gate insulating film 40 may be formed by a process such as atomic layer deposition (ALD), PECVD, sputtering, or MOCVD with a conventional thickness in the art.

The gate electrode 50 on the gate insulating film 40 may be formed of a transparent oxide such as ITO, IZO, ZnO: Al (Ga), Mo, Pt, Ti, Ag, Au, Al, Cr, Al / Cr / Al, Ni, or the like. The same low resistance metal or conductive polymer may be used, but is not limited thereto. The gate electrode 50 is formed after patterning by a process such as sputtering, atomic layer deposition (ALD), or chemical vapor deposition (CVD) to a thickness conventional in the art.

All patterning in the formation of the thin film may be performed through a photo-lithography method or a wet etching method.

Hereinafter, one or more configuration and effects of the present invention will be described in detail by way of specific examples, but the following examples are for illustrative purposes and do not limit the scope of the present invention.

Example 1

RF magnetron sputters each equipped with a target of SnO ₂ and Ag were simultaneously operated on the substrate to form an Ag-doped SnO ₂ thin film having a thickness of 100 nm at room temperature. The sputtering was performed in an Ar gas atmosphere by applying a chamber pressure of 3 mTorr and DC power of 1 W, 3 W, and 5 W to the cathode of the Ag target and 250 W to the cathode of the 3 inch SnO ₂ target.

The crystallinity change due to the change in the Ag input amount according to the DC power applied to the cathode of the Ag target is evaluated and the results are shown in FIG. 6.

According to FIG. 6, it can be seen that as the amount of Ag added increases, that is, as the value of applied power increases, the peak increases (200). From the result, the amount of metal penetrated into the oxide film is 0.1 to 15% by weight. It was confirmed that the range was appropriate.

Example 2

RF magnetron sputters each equipped with a target of SnO ₂ and Ag were simultaneously operated on the substrate to form an Ag-doped SnO ₂ thin film having a thickness of 100 nm at room temperature. The sputtering was performed in an Ar atmosphere by applying a DC power of 1W, 2W, 3W, 4W, and 5W to the cathode of the Ag target and 250W to the chamber pressure of 3mTorr and the cathode of the 3 inch SnO ₂ target.

The change in permeability due to the change in the Ag input amount according to the DC power applied to the cathode of the Ag target was evaluated and the results are shown in FIG. 7. As the amount of Ag is increased, the permeability is lowered. From this result, it is confirmed that the amount of metal penetrated into the oxide film is in the range of 0.1 to 15% by weight.

Example 3

RF magnetron sputters each equipped with a target of SnO ₂ and Ag were simultaneously operated on the substrate to form an Ag-doped SnO ₂ thin film having a thickness of 100 nm at room temperature. The sputtering was performed in an Ar atmosphere by applying a chamber pressure of 3 mTorr and a DC power of 250 W to a cathode of a 3 inch SnO ₂ target and ₂ W to a cathode of an Ag target. The thin film was then heat treated at 300 ° C. for 1 hour.

By measuring the change in the specific resistance of the SnO ₂ thin films heat-treated before the Ag-doped SnO ₂ thin film and the heat-treated Ag doping is shown in Figure 8 the results.

According to FIG. 8, it can be seen that the specific resistance is further reduced after the heat treatment.

1 is a schematic diagram showing the simultaneous deposition in the production of silver doped tin oxide film according to an embodiment of the present invention.

2 to 5 are cross-sectional views illustrating a structure of a thin film transistor according to an exemplary embodiment of the present invention.

6 is a peak of crystallinity according to the amount of silver input of the silver-doped transparent tin oxide film according to an embodiment of the present invention.

FIG. 7 is a transmittance curve illustrating a change in transmittance according to silver input amount of a silver-doped transparent tin oxide film according to an embodiment of the present invention.

8 is a curve showing a change in specific resistance before and after heat treatment of a silver-doped transparent tin oxide film according to an embodiment of the present invention.

Claims (7)

In the manufacturing method of the transparent tin oxide film doped with silver, Simultaneously depositing silver and tin oxide such that the metal is doped into the oxide film simultaneously with forming the oxide film, wherein the content of silver is in the range of 0.1 to 15% by weight; Coating a metal film on the silver-doped tin oxide film in a thickness range of 1 to 3 nm with the same or different metal as the doped metal; And The method of manufacturing a silver-doped transparent tin oxide film comprising the step of heat-treating the silver oxide doped tin oxide film. The method of claim 1, The deposition step is a method of manufacturing a silver-doped transparent tin oxide film, characterized in that carried out under an inert environment. delete The method of claim 1, The other metals are Mo, Ti, Cu, Sr, Ge, Mg, Y, Zr, B, V, Ta, Ti, Ir, Te, Sb, Cr, Fe, Co, Ru, Au, Pt, Me, Ni, Method for producing a transparent tin oxide film doped with silver that is at least one selected from the group consisting of Sn, Bi, Al, Ga and In. delete The method of claim 1, And the deposition is performed using a sputter, an evaporator or an ion-gun. Transparent tin oxide film doped with 0.1 to 15% by weight of silver prepared by the method according to claim 1.

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