WO2015060636A1 - Complex and asymmetric composite thin film and method for preparing same using atomic layer deposition - Google Patents

Abstract

The present invention relates to a composite thin film, which is provided with a doping region layer and non-doping region layer by means of atomic layer deposition (ALD) and thus is complex and asymmetric in terms of components in the thickness direction, and to a method for preparing same. The composite thin film, according to the present invention, has, on one area of the thin film, a doping region layer comprising a dopant atomic layer, thereby having complex and asymmetric properties in terms of components in the thickness direction of the thin film, and allows the doping region layer and a non-doping region layer to have different band structures, thereby having a different electromagnetic property for each layer region of the thin film. Thus, the composite thin film has improved functionality and may be used in all fields of displays, memories and semiconductors.

Description

Composite and Asymmetric Composite Thin Films Using Monoatomic Vapor Deposition and Its Manufacturing Method

The present invention relates to a manufacturing method using a composite thin film and asymmetric composite thin film and monoatomic vapor deposition in the thickness direction with a doped region layer and a non-doped region layer.

Thin films are uniform two-dimensional structures, typically several micrometers or less thick, and are used throughout the electronics industry, such as displays and memories, due to their variety of functionality. In particular, in recent years, monoatomic deposition is widely used among various vapor phase processes in order to match a thin thickness of several nanometers required for commercially available products.

Unlike the chemical vapor deposition method, the monoatomic deposition method proceeds by using a surface reaction, so that the reaction is saturated by itself and thus the atomic layer deposition is possible (FIGS. 1 and 3). This is one of the biggest advantages of this method, composition control is also possible in atomic layer units. Therefore, this monoatomic deposition method is mainly used to optimize the insulating film used in the memory or transistor because it is possible to make a precise composition control, and to make a thin film having a high density and quality over a large area. In this optimization process, an insulating film is usually manufactured by finding an unified optimal composition and controlling the entire thin film accordingly. In the prior art, for example, a ZnO-Al ₂ O ₃ thin film (Al-doped ZnO thin film) may be produced by monoatomic deposition (Al-doped ZnO transparent conductive film using atomic layer deposition and Characteristics Evaluation, Hyun-Joon Jung, Master Thesis, Chungnam National University 2010). However, this is to produce a whole thin film while performing alternately repeated ZnO ALD cycle and Al ₂ O ₃ ALD cycle, the overall thin film will have a uniform composition. Alternatively, instead of stacking the thin film matrix layer and the dopant layer in separate cycles, the thin film matrix precursor and the dopant precursor are sequentially or simultaneously pulsed in one cycle and the reactants are pulsed to oxidize to produce one doped atomic layer. There is a method of stacking them continuously (Korean Patent Publication No. 10-2013-0049752). Again, the composition of the entire thin film becomes uniform. Therefore, the thin film thus prepared has a uniform composition and thus exhibits a single characteristic.

However, in recent years, as the technology develops, the necessity of a thin film having a complex and interlayer asymmetric property in a thin film is required in various device fields such as a solar cell, a transistor, and a memory. As a representative example, the solar cell industry uses a functional thin film having a multi-bonded laminated structure in order to absorb sunlight having various wavelengths more effectively, because it uses various materials and processes in terms of cost and energy efficiency. You lose money. Therefore, if it is possible to manufacture a thin film having a complex and asymmetrical properties in a single in situ process, this problem can be solved, and furthermore, a solar device having characteristics not previously possible can be made.

However, research on this is very limited.

In the process of manufacturing a thin film by depositing in atomic layer units, the inventors form a doped region layer on a portion of a thin film by laminating an atomic layer with a dopant material, thereby forming a composite on a component in a thin film thickness direction rather than a uniform composition. And it was confirmed that the production of a thin film having asymmetrical properties. The thin film thus prepared exhibits complex electromagnetic properties, and furthermore, it has been confirmed that the thin film has an influence on the independent electromagnetic properties according to the location of the doped region layer and its dopant concentration. The present invention is based on this.

A first aspect of the present invention is a composite thin film having a doped region layer and a non-doped region layer in the thickness direction of the composite and asymmetric, wherein the doped region layer is an atomic layer deposition (ALD) method The present invention provides a composite thin film which is characterized by having at least one dopant atomic layer formed by using a dopant precursor.

A second aspect of the present invention is a method for producing a composite thin film according to the present invention on a substrate using atomic layer deposition (ALD), wherein at least one dopant atomic layer is formed using a dopant precursor. And forming a doped region layer, wherein the forming of the doped region layer comprises: a first layer of laminating the dopant atomic layer by an ALD cycle by pulsing a dopant precursor in a reaction chamber; step; And a second step of depositing a thin film matrix atomic layer by an ALD cycle by pulsing the thin film matrix precursor, wherein the first and second steps may be performed in a reverse order.

A third aspect of the present invention provides an electronic device having the composite thin film of the first aspect.

Hereinafter, the present invention will be described in detail.

Regarding a method of manufacturing a doped thin film by using monoatomic deposition, as described above, ALD cyclo thin film matrix atomic layer (ZnO layer) and dopant atomic layer (Al ₂ O ₃ layer) are repeatedly stacked at regular intervals. To fabricate a ZnO-Al ₂ O ₃ thin film with uniform composition (a preparation and characterization of Al-doped ZnO transparent conductive film by atomic layer deposition method, Hyun-Joon Jung, Master's Thesis, Chungnam National University 2010). Alternatively, instead of laminating the thin film layer and the dopant layer in separate cycles, the thin film matrix precursor and the dopant precursor are sequentially or simultaneously pulsed in one cycle and the reactants are pulsed to oxidize to prepare one doped atomic layer, There is a method of laminating continuously (Korean Patent Publication No. 10-2013-0049752). However, the thin film manufactured by the above methods is uniform in overall composition, and there is no asymmetrical characteristic between layer regions in the thin film.

However, according to the present invention, a doped region layer is formed on a portion of the thin film by laminating a dopant atomic layer with a dopant material during the thin film deposition process using the monoatomic deposition method, and thus, there is a feature that there are complex and asymmetrical characteristics between the layer regions in the thin film. Therefore, the doped region layer and the undoped region layer in the thin film may have different constituent compositions depending on the presence or absence of the dopant atomic layer, and thus the band structure and the crystal structure thereof may be different. Controllable and at the same time complex properties can be exhibited in one thin film.

Partial doped (doped region layer) composite thin film produced by the method according to the present invention can be used throughout the display, memory, semiconductor area is improved in functionality compared to the existing thin films, a separate additional process or a plurality of Since there is no need to manufacture the membrane separately, there is an advantage that there is no difference from the existing in terms of production cost.

The composite thin film according to the present invention includes a doped region layer and an undoped region layer, and has a complex and asymmetrical feature on the components in the thickness direction. That is, the doped region layer is a lamination structure formed by monoatomic deposition, and includes at least one dopant atomic layer formed using a dopant precursor, while the doped region layer does not include a dopant atomic layer, Does not include In the composite thin film of the present invention, since the doped region layer and the undoped region layer are each one or more, and are sequentially stacked, the composite thin film of the present invention exhibits asymmetric and complex composition in the thickness direction of the thin film cross section.

The composite thin film according to the present invention may include one or more doped region layers and one or more non-doped region layers, which may be sequentially stacked alternately.

In the present invention, the doped region layer may further include at least one thin film matrix atomic layer formed using a thin film matrix precursor as well as a dopant atomic layer. However, the dopant atomic layer and the thin film matrix atomic layer are each formed by performing only an ALD cycle by pulsed only a dopant precursor or an ALD cycle by pulsed only a thin film matrix precursor. In one atomic layer, only a dopant material or a thin film is used. It can consist of a single substance alone. Furthermore, in one embodiment of the present invention, it was confirmed that the dopant atomic layer in the doped region layer of the composite thin film according to the present invention forms an independent atomic layer with little diffusion into the thin film. May form regions separated by component phase (Experimental Example 1)

Further, when the dopant atomic layer and the thin film matrix atomic layer are stacked, the dopant atomic layer and the thin film matrix atomic layer may be stacked according to a predetermined ALD cycle circulation rule, or may be stacked without a predetermined rule. For example, when an atomic layer serving as a matrix of a thin film is A and a dopant atomic layer is B, they are A-B-A-B-A-B... It can be stacked in the form of, but if they are stacked in an irregular ALD cycle A-A-B-A-B-B-A-A... It may be stacked in the form of. Furthermore, two or more dopant atomic layers formed using dopant precursors in the doped region layer may be stacked in succession (e.g., B-B ...).

In the doped region layer of the present invention, the dopant atomic layer in the doped region layer is N, the thin film matrix atomic layer is M, the N and M is an integer of 1 or more, N: M is 1: 1 to 1 May be 40. The N and M may be controlled by the number of times the ALD cycle is performed by pulsed dopant precursor and the number of times the ALD cycle is performed by pulse of the thin film matrix precursor, thereby controlling the doping concentration of the thin film. If the N: M exceeds 1: 1 (for example 1: 0.5), the matrix material and the dopant material are inverted. Furthermore, the concentration of the dopant material is excessively increased and diffusion into the thin film is prevented. There may be problems that can occur or disrupt the thin film matrix crystal structure. If the N: M is smaller than 1:30 (for example, 1:50), the concentration of the dopant material may be excessively low, so there may be a problem in that there is little difference between the characteristics of the single thin film and the thin film. However, the above range is applicable only to the material system of the present invention, and is not particularly limited to the above range in other material groups having different characteristics.

In the present invention, the doped region layer does not mean a region consisting only of the dopant atomic layer, but means a region from the point where the dopant atomic layer appears to the point where the dopant atomic layer is present at the bottom of the layer. do. For example, the atomic layer deposition in a thin film is. A-A-B-A-A-A-B-A-A-A-B-A-A... In this case, the "B-A-A-A-B-A-A-A-B" region may be referred to as a doping region layer according to the present invention. However, the meaning of the doped region layer may be expanded to include not only the "B-A-A-A-A-B-A-A-A-B" region but also the front and rear atomic layers thereof according to the setting of the supercycle for forming the doped region layer.

In the present invention, the undoped region layer is a layered structure consisting of only a thin film matrix atomic layer formed by monoatomic deposition without a dopant atomic layer, and located below and / or above the doped region layer. … A-A-A-A-A... It means the same area as.

In the present invention, the dopant atomic layer may be formed by laminating the dopant atomic layer by an ALD cycle by pulsing a dopant precursor in a reaction chamber. The thin film matrix atomic layer may be formed by stacking a thin film matrix atomic layer by an ALD cycle by pulsing a thin film matrix precursor. In this case, the dopant precursor and the thin film matrix precursor are respectively different metal source compounds, and the metal is Ti, Hf, Zr, Si, Al, Ta, Sr, Ba, Sc, Sn, In, Ga, Y, La, It may be any one selected from the group consisting of Eu and Dy. The metal source compound that is the dopant precursor and the thin film matrix precursor is not particularly limited. However, when the dopant material has a high diffusion coefficient in relation to the thin film matrix formed of the thin film matrix precursor, there may be a problem that the dopant material of the dopant atomic layer diffuses into the entire thin film. Therefore, a precursor material (metal source) in which diffusion between the dopant material and the thin film matrix material does not occur significantly even at a temperature of 100 to 200 ° C., which is a temperature of the monoatomic deposition process, and a heat treatment condition at a temperature of 300 ° C. or lower which is usually performed on the thin film. Compound). This may be appropriately selected by those skilled in the art in view of the diffusion coefficient and interaction of dopant materials and thin film matrix materials commonly known in the art. For this purpose, the metal source compound, which is a dopant precursor, and the metal source compound, which is a thin film matrix precursor, are preferably selected as a source material having a similar surface reaction temperature on the same substrate. May be advantageous. Again, those skilled in the art can appropriately select a metal source compound depending on the use of the thin film and the desired properties.

In one embodiment according to the present invention, a non-limiting example of the dopant precursor is trimethyl aluminum (TMA) as an Al source, a non-limiting example of a thin film matrix precursor is a Di as a Zn source Dietyl zinc (DEZ). In particular, since the interdiffusion coefficient is small between the Al dopant atomic layer formed by TMA and DEZ and the ZnO thin film matrix atomic layer, there is an advantage that the interdiffusion can be ignored unless the high temperature condition is at least 400 ° C.

As shown in Figure 1, the specific configuration of the composite thin film according to the present invention will be described as follows. Specifically, the structure of the Al-doped ZnO composite thin film according to an embodiment of the present invention, in which the dopant atomic layer is Al ₂ O ₃ and the thin film matrix atomic layer is ZnO, is illustrated in FIG. 1.

The ZnO thin film according to the present invention may be a doped region layer in which a partial region layer of the cross section of the layer is doped with Al. In FIG. Except for the doped region layer, the remaining regions are non-doped region layers and are composed of only ZnO atomic layers. That is, the illustrated composite thin film includes one doped region layer and one undoped region layer. When the doped region layer is enlarged, it can be seen that the ZnO (thin film) atomic layer and the Al ₂ O ₃ (dopant) atomic layer are sequentially stacked. In this case, the thicknesses of the ZnO atomic layer and the Al ₂ O ₃ atomic layer may vary depending on how many times each monoatomic deposition cycle is performed in succession, and the Al dopant composition of the doped region layer may be adjusted by adjusting the thickness thereof. . Furthermore, the Al ₂ O ₃ atomic layer is composed of Al ₂ O ₃ only, and accordingly the Al doping according to the present invention can be understood as the concept of the insertion of the Al atomic layer. In conclusion, the doped region layer and the undoped region layer have a distinctly different composition due to the presence or absence of the Al dopant atomic layer, and as described above, the composition shows asymmetric and complex composition in the thickness direction of the thin film cross section. . In particular, in the case of a dopant material doped in a thin film, in general, the thin film is diffused into the entire thin film so that the composition becomes uniform throughout. In the composite thin film according to the present invention, the dopant material is not diffused but is an independent dopant atom. With a layer, it is distinguished in the thin film thickness direction and exhibits discontinuous component composition.

In the composite thin film according to the present invention, the characteristics of the thin film may vary depending on the position of the doped region layer in the thin film and the dopant concentration thereof.

First, the position of the doped region layer in the thin film may be determined in consideration of the use and functionality of the specific thin film. That is, as described above, the composite thin film of the present invention has an asymmetric characteristic in composition between the doped region layer and the undoped region layer, and in particular, the doped region layer is provided with a dopant atomic layer unlike the undoped region layer. Exhibit distinct optical and electromagnetic properties. Therefore, in consideration of the characteristics of the doped region layer, the position of the doped region layer can be determined according to the characteristics of the electronic device to be used.

For example, when the composite thin film according to the present invention is used as an insulating film of a DRAM, the electron injection barrier is increased only in the thin film region layer to be bonded to the electrode, that is, the band gap is increased, and the remaining region layer has a high dielectric constant. It is important to do. Therefore, in this case, it is advantageous to use the upper and lower end region layers of the composite thin film as the doping region layer, which is obtained by stacking the dopant atomic layer using the dopant precursor at the beginning and the end of the monoatomic deposition process in manufacturing the composite thin film according to the present invention. By forming the doped region layer, the doped region layer may be formed on both top and bottom regions of the thin film. Furthermore, since the intermediate region layer of the thin film is formed of an undoped region layer, the region may have a high dielectric constant.

In addition, when the composite thin film is used as the operating layer of the thin film transistor according to an embodiment of the present invention, it was confirmed that the effect on the independent transistor characteristics different depending on the position of the doping region layer, in particular (Experimental Examples 3 to 6) . When the doped region layer is located under the thin film, that is, at the interface of the semiconductor / insulating layer, it may have a great influence on the on characteristics (eg, mobility) of the transistor. On the other hand, when the doped region layer is located on the top of the thin film, that is, the surface of the composite thin film, it may have a great influence on the off characteristics (eg, threshold voltage) of the transistor. Therefore, it is advantageous to increase the mobility in order to improve the electrical characteristics of the switched-on state (switch-on), so that the lower region layer (semiconductor / insulation interface) of the composite thin film can be formed as a doped region layer to increase the mobility. have. In this case, the doped region layer may be formed in the lower region layer of the thin film by forming a doped region layer by laminating a dopant atomic layer using a dopant precursor at the beginning of the monoatomic deposition process in manufacturing the composite thin film according to the present invention. . Further, at this time, the non-doped region layer stacked on the doped region layer may have a high dielectric constant to serve as an insulating film. On the other hand, for precise control of the transistor, a doped region layer may be formed on the upper portion (thin film surface) of the composite thin film to easily control the threshold voltage, which may be particularly suitable for a display panel. In this case, when manufacturing the composite thin film according to the present invention, first, only the thin film matrix precursor is pulsed to perform a monoatomic deposition process, and then a dopant precursor is used when the thin film is deposited and reaches the upper region of the thin film. As a result, the doped region layer may be formed on the upper region layer of the thin film.

As described above, the characteristics of the thin film may vary according to which region layer of the composite thin film is determined as the doped region layer, and the characteristics of the entire thin film may also vary according to the ratio of the physical thickness of the doped region layer to the total composite thin film. This can be determined by those skilled in the art as appropriately selected for the application. In an embodiment of the present invention, the thickness of the doped region layer may be 2 nm to 4 nm, but is not particularly limited as described above, and may be appropriately selected by those skilled in the art.

As described above, even if the composite thin film according to the present invention has been described in detail with respect to the position and the formation method of the doped region layer when used as an insulating layer or transistor operating layer of the DRAM, those skilled in the art It is to be understood that the uses and application methods can be applied in various types to other electronic devices that require composite thin films having the doped region layer of the present invention.

Furthermore, in the composite thin film according to the present invention, not only the position of the doped region layer but also the dopant concentration thereof may be an important factor in determining the characteristics of the thin film. When the composite thin film is used as an operating layer of the thin film transistor according to an embodiment of the present invention, when the dopant concentration exceeds a certain level when the doped region layer is located below the thin film, the mobility may be reduced. (Experimental example 6). On the other hand, when the doped region layer is located on top of the thin film, it can be seen that as the dopant concentration increases, the threshold voltage is changed to a greater width (Experimental Example 5).

Therefore, it is necessary to adjust the dopant concentration appropriately for the characteristics of the desired thin film. In the monoatomic deposition process, the ratio of the dopant atomic layer and the thin film matrix atomic layer is controlled by adjusting the ratio of the dopant cycle and the thin film cycle. The dopant concentration (atomic ratio) can be adjusted. More details will be described later.

A second aspect of the present invention is a method for producing a composite thin film according to the present invention on a substrate using atomic layer deposition (ALD), wherein at least one dopant atomic layer is formed using a dopant precursor. And forming a doped region layer, wherein the forming of the doped region layer comprises: a first layer of laminating the dopant atomic layer by an ALD cycle by pulsing a dopant precursor in a reaction chamber; step; And a second step of depositing a thin film matrix atomic layer by an ALD cycle by pulsing the thin film matrix precursor, wherein the first and second steps may be performed in a reverse order.

Specific terms in the manufacturing method according to the second aspect of the present invention, features and basic principles of the invention are as described above in the composite thin film according to the first aspect.

The monoatomic deposition according to the present invention may be performed in a reaction space, that is, in a reaction chamber capable of controlling conditions in a typical monoatomic deposition process. The reaction chamber may be, for example, a reaction chamber of a single-wafer ALD reactor or a reaction chamber of a batch ALD reactor in which deposition on a plurality of substrates is performed simultaneously. Can be. The composite thin film according to the present invention can be prepared by forming a doped region layer and an undoped region layer in situ in the same reaction chamber.

The substrate on which the composite thin film according to the present invention is formed is typically a workpiece on which thin film deposition is required, and non-limiting examples thereof include silicon, silica, coated silicon, Metal, such as copper or aluminum, dielectric materials, nitrides, or a combination thereof.

In the present invention, the step of forming the doped region layer including one or more dopant atomic layers may be performed by depositing the dopant atomic layer by an ALD cycle by specifically pulsing the dopant precursor in the reaction chamber. A first step and a second step of laminating the thin film matrix atomic layer by an ALD cycle by pulsing the thin film matrix precursor, wherein the first step and the second step may be performed sequentially or may be performed in the opposite order, and are particularly limited. It is not. For example, a layer B of a dopant atomic layer may be formed through a first step, and a layer A of a thin film matrix atomic layer may be formed through a second step. If the first step and the second step are performed sequentially, the A layer is stacked next to the B layer (B-A), and if the steps proceed in the opposite order, the B layer is stacked after the A layer (A-B).

In particular, the first and second steps may be performed repeatedly. Further, the first and second steps may be regularly stacked by being repeatedly performed according to a predetermined circulation rule, or may be repeatedly stacked without being carried out without a specific rule to form a doped region layer. When laminating regularly, as described above, for example, A-B-A-B-A-B... In the case of laminating irregularly, as described above, for example, A-A-B-A-B-B-A-A ... It means to laminate in the same form as.

Further, in the formation of the doped region layer according to the present invention, the ALD cycle of the first step is performed n times, the ALD cycle of the second step is performed m times, and the doping concentration is controlled by adjusting the number of n and m. Can be adjusted. For example, as shown in FIG. 3, when the first step is performed once (n = 1) and the second step is performed twice (m = 2), a layer such as B-A-A may be stacked.

In this case, the cycle of stacking up to B-A-A may be referred to as a supercycle. That is, the supercycle means a cycle in which the ALD cycle of the first stage is performed n times and the ALD cycle of the second stage is performed m times when the first stage and the second stage are regularly and repeatedly performed. Therefore, the step of forming the doped region layer according to the present invention may be performed until the desired layer thickness is made by repeatedly performing the supercycle x times. If the supercycle is executed three times in the above example (x = 3), a doped region layer such as B-A-A-B-A-A-B-A-A is formed. In this case, three dopant atomic layers in the doped region layer (N = 3), six thin film matrix atomic layers (M = 6), and n: m = N: M, in this case 1: 2. Can be.

In the forming of the doped region layer according to the present invention, n: m may be 1: 1 to 1:40.

In the present invention, the method of depositing the dopant atomic layer or the thin film matrix atomic layer may be performed by a conventional monoatomic deposition method in the art. This is a process of alternately supplying a metal source compound, which is a dopant precursor or a thin film matrix precursor, and an oxygen source compound, which is a reactant, to form a metal oxide film (oxidized metal atomic layer), while maintaining a constant temperature of the substrate in the reaction chamber. Into the reaction chamber, the precursor metal source compound and the reactant oxygen source compound are alternately supplied to the substrate to adsorb and react, and the reactor is evacuated between these steps, or an inert gas such as argon is sent to the reactor, thereby leaving unreacted residues and by-products. The method of forming an atomic layer and stacking one by one through the process of removing it may be more specifically represented by the following steps a to d. 3 shows a schematic diagram of a monoatomic deposition cycle according to the present invention.

Pulse a dopant precursor or thin film matrix precursor in the reaction chamber; B) removing excess dopant precursor or thin film matrix precursor from the reaction chamber; C) pulsed reactant in the reaction chamber; And d) removing excess reactants and reaction products from the reaction chamber.

Steps a to d are referred to as one cycle, and one atomic layer may be formed through the cycle.

The reactant of step c may be any one or more selected from the group consisting of H ₂ O, O ₂ , O ₃ , O radicals, H ₂ O ₂ and D ₂ O, but is not particularly limited.

A third aspect of the present invention provides an electronic device having the composite thin film of the first aspect. In the present invention, the electronic device may be specifically a transistor or a DRAM, but is not particularly limited.

Specific terms, features and basic principles of the electronic device according to the third aspect of the present invention are as described above in the specific application of the composite thin film according to the first aspect. That is, by controlling the position of the doped region layer and the dopant concentration thereof in the composite thin film according to the present invention, it can be used as an electronic device having the thin film.

The composite thin film according to the present invention has a doped region layer including a dopant atomic layer on a part of the thin film, thereby having a complex and asymmetric characteristic in the component direction in the thickness direction of the thin film, which is between the doped region layer and the non-doped region layer. By changing the band structure, the electromagnetic characteristics of each layer region of the thin film may be changed, and the functionality may be improved, and thus may be used throughout the display, memory, and semiconductor regions.

Furthermore, it affects various electromagnetic properties according to the position of the doped region layer in the composite thin film and its dopant concentration, and thus, the electromagnetic characteristics of the thin film can be easily adjusted according to the purpose by adjusting the position and concentration of the doped region layer.

Since the composite thin film according to the present invention is manufactured by the monoatomic deposition method, the optical and electromagnetic properties of the thin film can be controlled through a simple process, and there is no need to separately prepare additional processes or a plurality of films separately. Is also advantageous.

1 is a schematic diagram showing a structure of a ZnO composite thin film doped with Al locally under a thin film according to an embodiment of the present invention.

2 is a schematic diagram of a reactor for producing a composite thin film according to the present invention.

3 is a schematic diagram of a monoatomic deposition cycle which is a method of manufacturing a composite thin film according to the present invention. A represents a thin film matrix precursor and B represents a dopant precursor.

4 is an electron spectroscopy chemical analysis (XPS) graph according to the concentration of doped Al, performed in one experimental example of the present invention. FIG. 4A shows when the atomic percentage (concentration) of Al is about 7%, FIG. 4B when about 20%, and FIG. 4C when about 50%.

FIG. 5 is a graph showing thin film cross-sectional TEM images and EDX line distribution results of Al-doped ZnO composite thin films and ZnO single thin films according to the present invention, performed in an experimental example of the present invention. FIG. 5A shows a ZnO single thin film, and FIG. 5B shows a ZnO composite thin film doped with Al locally.

6 is a graph showing transistor operating characteristics according to the Al doped region layer position in the composite thin film, which was performed in an experimental example of the present invention. 6A and 6B are graphs illustrating I-V characteristics of a drain current-gate voltage, and FIG. 6C is a graph of saturation mobility-gate voltage.

7 is a graph showing the XPS depth analysis results for the thin film depth of the composite thin film prepared in the embodiment of the present invention. 7A to 7C are graphs of ZnO composite thin films having a doped region layer doped with Al on top of a thin film prepared by the method according to Examples 1 to 3, and FIGS. 7D to 7F are examples 4 to 6 A graph of a ZnO composite thin film having a doped region layer doped with Al under a thin film prepared by the method described above.

FIG. 8 is a graph showing transistor operating characteristics of a ZnO composite thin film prepared in Examples 1 to 3 of the present invention having a doped region layer doped with Al on the thin film. 8A and 8B are IV characteristic graphs for the Drain Current-Gate Voltage, FIG. 8C is a graph for Saturation Mobility-Gate Voltage, FIG. 8D is a threshold voltage graph for each of 6 samples, and FIG. 8E is 6, respectively. Saturation mobility graph for dog samples.

FIG. 9 is a graph showing transistor operating characteristics of a ZnO composite thin film prepared in Examples 4 to 6 of the present invention having a doped region layer doped with Al under a thin film. 9A and 9B are IV characteristic graphs for the Drain Current-Gate Voltage, FIG. 9C is a graph for Saturation Mobility-Gate Voltage, FIG. 9D is a threshold voltage graph for each of 6 samples, and FIG. 9E is 6, respectively. Saturation mobility graph for dog samples.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, these examples are for illustrative purposes only and the scope of the present invention is not limited to these examples.

Referring to Figure 2 will be described a monoatomic deposition reaction apparatus for producing a composite thin film according to the present invention.

The reaction apparatus includes a reaction chamber 1 in which monoatomic deposition is performed, a heater 2 for heating the reaction chamber, a carrier gas inlet part 3 connected to the reaction chamber, and a gas discharged from the reaction chamber. A gas outlet 4, a thin film matrix precursor supply canister 5 connected to the reaction chamber, a dopant precursor supply canister 6 connected to the reaction chamber, and a reactant (oxygen source material) supply canister connected to the reaction chamber. (7), thin film matrix precursor manual valve (8), dopant precursor manual valve (9), reactant manual valve (10), thin film matrix precursor pneumatic valve (11), dopant precursor pneumatic valve (12) and reactant pneumatic valve It consists of (13).

When performing monoatomic deposition through the reactor, the manual valves of the thin film matrix precursor, the dopant precursor, and the reactants are left open, and the pneumatic valve corresponding to the deposition step is supplied to supply an appropriate source material. It is possible to manufacture a composite thin film using magnetic vapor deposition.

More specifically, in the preparation of the composite thin film according to the present invention, the dopant precursor is trimethyl aluminum (TMA), the thin film matrix precursor is diethyl zinc (DEZ), the reactant is water (H ₂ O) and the carrier gas Nitrogen (N ₂ ) was selected. The canisters 5-7 were held during the deposition process at 15 ° C., 15 ° C., and 10 ° C., respectively, in order.

The cycle for forming the ZnO thin film matrix atomic layer was composed of DEZ pulses → purge → H ₂ O pulses → purge step, and the cycles were controlled by controlling the time from 0.5s → 10s → 0.1s → 10s. The cycle for forming the Al ₂ O ₃ dopant atomic layer consists of a TMA pulse → purge → H ₂ O pulse → purge step, the execution time of the detailed step was performed in the same manner as the ZnO thin film matrix atomic layer cycle.

The temperature was maintained at 150 ° C. during the deposition process through the cycle.

Nitrogen, the carrier gas for the purge, was adjusted to 500 sccm during the deposition process.

Thin film samples prepared through monoatomic deposition were heat treated at a temperature of 200 ° C. under vacuum for 1 hour.

Examples 1 to 3: Preparation of Al-doped ZnO Composite Thin Film with Doping Region Layer on Top of Thin Film

The composite thin film according to the present invention was prepared as follows. Specifically, trimethyl aluminum (TMA) is selected as the dopant precursor and diethyl zinc (DEZ) is selected as the thin film matrix precursor, and ZnO doped with Al having a doped region layer having an Al ₂ O ₃ dopant atomic layer. A composite thin film was prepared. In this case, the composite thin film is a transistor operation layer, and a doped region layer is formed on the surface of the composite thin film (upper thin film), which is a bulk region.

Since the composite thin film according to the present embodiment targets a ZnO-based transistor thin film operating layer, a thin film having a total thickness of about 20 nm is suitable. In view of this, the doped region layer having the dopant atomic layer is electron-aggregated. The thickness within 4 nm in which the layer is formed is appropriate, and the remaining about 16 nm is appropriately formed as an undoped region layer.

A silicon substrate on which a silicon oxide film was formed 100 nm was placed in the chamber. In the present embodiment, since the lower portion of the thin film should be made of only the ZnO thin film matrix atomic layer, which is the undoped region layer, only the ethyl dopant precursor diethyl zinc (DEZ) is pulsed to deposit the ZnO thin film matrix atomic layer to form the undoped region layer. Formed. At this time, the number of cycles was adjusted to about 80 times so that the thickness is 16nm.

After forming the undoped region layer, a doped region layer having a dopant atomic layer was formed to a thickness of about 5 nm to prepare a composite thin film having a total thickness of 20 nm. Specifically, the doped region layer was determined to be formed within 20 cycles for the 4nm thickness. When the dopant precursor (TMA) is pulsed and the dopant atomic layer is laminated once, the thin film matrix precursor (DEZ) is pulsed and the thin film matrix atomic layer is laminated 10 times (n: m = 1: 10, Example 1) When the thin film matrix precursor DEZ is pulsed to perform three cycles of laminating a thin film matrix atomic layer (n: m = 1: 3, Example 2) or a thin film matrix In the case where the cycle of stacking the thin film matrix atomic layer by pulsing the precursor DEZ was performed once (n: m = 1: 1, Example 3), deposition was performed. By repeating the above supercycle, when the total cycle is about 20 cycles was stopped to form a thickness of the doped region layer 4nm.

As a result, a ZnO composite thin film in which a portion of the thin film, which is a portion of the thin film, is doped with Al was prepared. The atomic ratio (concentration) of Al in the doped region layer of the thin film according to Example 1 was about 7%, Example 2 was about 20%, and Example 3 was about 50%.

Examples 4 to 6: Preparation of Al-doped ZnO composite thin film having a doped region layer under the thin film

In this embodiment, the composite thin film is a transistor operating layer, and a doped region layer is formed at the semiconductor / insulating film interface (lower thin film). Except that the doped region layer was formed on the bottom of the thin film, the same procedure as in Examples 1 to 3. Specifically, it is as follows.

In order to make the lower region of the thin film a doped region layer, first, a doped region layer was formed on a silicon substrate within 20 cycles (about 4 nm). When the dopant precursor (TMA) is pulsed and the dopant atomic layer is laminated once, the thin film matrix precursor (DEZ) is pulsed and the thin film matrix atomic layer is laminated 10 times (n: m = 1: 10, Example 4) When the thin film matrix precursor DEZ is pulsed to perform three cycles of laminating the thin film matrix atomic layer (n: m = 1: 3, Example 5) or the thin film matrix When the cycle of stacking the thin film matrix atomic layer by pulsing the precursor DEZ was performed once (n: m = 1: 1, Example 6), deposition was performed. By repeating the above supercycle, when the total cycle is about 20 cycles was stopped to form a thickness of the doped region layer 4nm.

Subsequently, only dopant precursor diethyl zinc (DEZ) was pulsed on the doped region layer, thereby depositing a ZnO thin film matrix atomic layer to form an undoped region layer. At this time, the number of cycles was adjusted to about 80 times so that the thickness is 16nm, and as a result, a total thickness of about 20nm, a ZnO composite thin film was doped with Al in the lower portion of the thin film, which is a part of the thin film. The atomic ratio (concentration) of Al in the doped region layer of the thin film according to Example 4 was about 7%, Example 5 was about 20%, and Example 6 was about 50%.

Comparative Example 1: Preparation of ZnO Single Thin Film

The same silicon substrate as in Examples 1 to 6, in which a silicon oxide film was formed at 100 nm, was placed in the chamber. On the substrate, a ZnO single thin film was prepared by laminating a thin film matrix atomic layer using monoatomic deposition. Unlike the above Examples 1 to 6, a ZnO single thin film having a total thickness of 20 nm is repeated by repeating the cycle about 100 times without using a dopant precursor (TMA) and only diethyl zinc (DEZ), which is a thin film matrix precursor. Was prepared.

Experimental Example 1: XPS Analysis

Surface analysis (thin film analysis) was performed on the ZnO composite thin film doped with Al in a portion of the thin film, which is prepared by the method according to Examples 4 to 6, using Al.

After heat-treating the composite thin film prepared by the method according to Examples 4 to 6 at 400 ° C. in air for 1 hour, the Al 2p peak distribution according to the depth of the thin film was examined by XPS analysis. The ion beam output was fixed at 500 eV and spectral capture was performed every 10 seconds. The results are shown in FIG.

Through the XPS analysis result, it can be confirmed that the Al ₂ O ₃ atomic layer is present only in a partial region of the composite thin film (Al doped). Furthermore, even though the concentration of the doped Al is increased (for example, FIG. 4C), the Al peak exists only in a specific region, so that the diffusion of Al, which is a dopant material, hardly occurs even when the thin film is heat-treated at a high temperature. Can be confirmed. As a result, in the composite thin film according to the present invention, it was confirmed that the dopant was present only in the doped region layer without being diffused into the entire thin film, and Al could be locally doped only in a portion of the thin film.

Experimental Example 2: TEM image and EDX analysis

TEM images and EDX analysis were performed on the composite thin film according to the present invention. Composite thin film to be analyzed in Experimental Example 2 was prepared as follows.

It was carried out similarly to Examples 1 to 3 or Examples 4 to 6, except that the doped region layer was formed in the middle of the thin film. Specifically, the thin film matrix is subjected to 45 cycles of laminating the thin film matrix precursor layer DEZ on the silicon substrate, followed by one cycle of laminating the dopant atomic layer thereon. Supercycle (n: m = 1: 1) was performed five times (10 cycles in total) for carrying out one cycle of atomic layer deposition, and then 45 times for laminating thin film matrix atomic layers thereon. (45 cycles of ZnO → 10 cycles of doping → 45 cycles of ZnO).

In the ZnO single thin film prepared in Comparative Example 1 and the composite thin film prepared above, respective thin film cross-sectional TEM images and EDX line distribution results are shown in FIGS. 5A and 5B, respectively, to compare them.

First, comparing the TEM image (FIG. 5A) of the single thin film cross-section TEM image (FIG. 5B) of Comparative Example 1, in the case of the composite thin film according to the present invention, the Al doped region layer and the non-doping inverse layer By having a distinct electron density, it can be seen that the doped region layer is clearly formed in the thin film.

Furthermore, when comparing the EDX line distribution with respect to the arrow direction in the TEM image, in the case of the composite thin film, Al appeared in the middle of the thin film in a similar form to the delta function, so that the presence of a distinctly doped Al layer could be observed. 5b). This is the same result as confirmed in FIG.

Experimental Example 3: Transistor Operational Characteristics According to Doped Region Layer Location (Local Doping Position)

In order to examine the difference in transistor operating characteristics according to the doped region layer position in the composite thin film according to the present invention, the Al dopant concentration is the same, but the transistor operating characteristics are examined by changing the formation position of the doped region layer in the thin film thickness direction. saw.

The doping region layer forming cycle is performed on all the composite thin films by pulsing the dopant precursor layer by laminating the dopant precursor layer (TMA), thereby pulsing the thin film matrix precursor layer (DEZ). The lamination cycle was performed three times (n: m = 1: 3). This supercycle was repeated three times to form a total of 12 cycles to form a doped region layer.

In order to change the position of the doped region layer, first, the ZnO cycle, which is the non-doped region layer, is performed ten times, the doped region layer cycle is performed, and the ZnO cycle is performed 90 times (ZnO 10 cycles → doping 12 cycles → ZnO). 90 cycles) The first composite thin film was prepared (10). The second composite thin film was prepared by performing ZnO 25 cycles → 12 cycles of doping → ZnO 75 cycles (25), and the third composite thin film was prepared by performing ZnO 50 cycles → 12 doping cycles → ZnO 50 cycles (50). The thin film was prepared by performing ZnO 75 cycles → 12 cycles of doping → ZnO 25 cycles (75), and the fifth composite thin film was prepared by performing ZnO 90 cycles → 12 cycles of doping → 10 cycles of ZnO (90). That is, the doped region layer was manufactured by variously distributing a position from the lower side of the thin film close to the semiconductor / insulating film interface to the upper side of the thin film which is the thin film surface.

The composite thin films were compared with the single thin film ref of Comparative Example 1 and the operating characteristics of the thin film transistor including the thin film transistor as the operating layer were examined. 6A to 6C show conduction characteristics of a thin film transistor using a silicon substrate as a gate electrode.

First, when the doped region layer is located close to the semiconductor / insulation layer interface under the thin film (10) it can be seen that the mobility (Mobility) is rapidly reduced to 1/3 level compared to the ZnO single thin film (ref). However, as the doped region layer is farther away from the semiconductor / insulating layer interface (for example, 75 and 90), there is no difference with the mobility of the ZnO single thin film. As a result, the closer the doped region layer is located near the semiconductor / insulating layer interface under the thin film, the more it affects the mobility of the thin film, and the farther it is located above a certain thickness, it is confirmed that the mobility property is hardly affected (FIG. 6C).

Furthermore, when the doped region layer is far away from the semiconductor / insulating layer interface (75 and 90), it can be seen that the I-V characteristic curve has a negative parallel shift (FIGS. 6A and 6B).

From the above results, it can be seen that the independent position of the doped region layer affects the independent characteristics of the thin film. Specifically, the on characteristic is turned off by the doped region layer located under the thin film. ) Is influenced by the doped region layer located on top of the thin film. As a result, it was confirmed that a thin film having complex characteristics could be provided by adjusting the position and number of the doped region layers according to the characteristics of the desired thin film transistor.

Experimental Example 4 XPS Analysis According to Doping Region Layer Location and Al Concentration

In the composite thin film according to the present invention, XPS analysis was performed on the depth of the thin film according to the position of the doped region layer and the concentration of the dopant (Al).

ZnO composite thin film having a doped region layer doped with Al on the thin film prepared by the method according to Examples 1 to 3 and doped with Al under the thin film prepared by the method according to Examples 4 to 6 above XPS analysis was performed on the ZnO composite thin film having the doped region layer and the results are shown in FIGS. 7A to 7F.

7A-7C where the doped region layer is on top of the thin film, in the upper region, the Al thickness increases and the Zn atomic ratio decreases with increasing Al doping concentration, that is, from FIG. 7A to FIG. 7C. It can be seen that there is a doped region layer which is divided in phase in the component direction.

On the other hand, in FIGS. 7D to 7F in which the doped region layer is under the thin film, as the Al doping concentration increases in the thin film lower region (Si semiconductor interface) (from FIG. 7D to FIG. 7F), the Al atomic ratio increases and Zn atoms It can be seen that there is a doped region layer that is componently divided in the thin film thickness direction with a decreasing ratio.

As a result, it was confirmed that the composite thin film according to the present invention can adjust the position and concentration of the doped region layer clearly defined in the thickness direction in the thin film as desired.

Experimental Example 5: Transistor Operational Characteristics of Al-doped ZnO Composite Thin Film with Doping Region Layer on Top of Thin Film

The transistor operating characteristics of the ZnO composite thin film having the doped region layer doped with Al on the surface of the composite thin film (upper thin film) prepared by the method according to Examples 1 to 3 were examined and the results are shown in FIGS. 8A to 8E. Indicated. Furthermore, the ZnO single thin film manufactured by the method according to Comparative Example 1 was also examined for comparison (Ref).

First, as described in Experiment 3, the composite thin films of Examples 1 to 3 having a doped region layer on the thin film were found to have a negative parallel shift in IV characteristic curve compared to Comparative Example 1. 8A and 8B, in particular, as the concentration of the Al dopant increases, a larger equilibrium shift may occur (Example 3). This is because when the doped region layer is formed on the thin film, the off characteristic of the thin film transistor is affected.

For the same purpose, in the case of a threshold voltage (Fig. 8d), it is significantly changed compared to Comparative Example 1, and it can be seen that it changes significantly significantly as the concentration of the Al dopant increases. However, it can be seen that it does not affect saturation mobility.

In conclusion, in the composite thin film according to the present invention, when the doped region layer is provided on the upper portion of the thin film, it is possible to control the threshold voltage, which is an off characteristic, thereby making a thin film transistor capable of precise control in a field such as a display panel. It was confirmed that it can be provided.

Experimental Example 6: Transistor Operational Characteristics of Al-doped ZnO Composite Thin Film with Doping Region Layer Under

The transistor operating characteristics of the ZnO composite thin film having the doped region layer doped with Al in the lower portion of the thin film (semiconductor / insulating film interface) manufactured by the method according to Examples 4 to 6 were examined and the results are illustrated in FIGS. 9A to 9E. Shown in Furthermore, the ZnO single thin film manufactured by the method according to Comparative Example 1 was also examined for comparison (Ref).

First, as described in Experiment 3, it was confirmed that the mobility of the composite thin films of Examples 4 to 6 having the doped region layer under the thin film was significantly changed compared to Comparative Example 1 (FIGS. 9C and 9E). In particular, in contrast to the thin film according to Embodiments 1 to 3, in which the doped region layer is provided on the thin film in Experimental Example 5, in the case of the threshold voltage (FIG. 9D), the saturation mobility is not significantly affected. Mobility) can be seen to have a great effect (FIGS. 9C and 9E). This is because when the doped region layer is formed under the thin film, it affects the on characteristic of the thin film transistor differently from when formed on the top.

Furthermore, in the composite thin films of Examples 4 to 6, it was found that mobility characteristics were changed in accordance with Al concentration. That is, when Al concentration is as low as about 7% as in Example 4, it can be seen that the mobility value is significantly increased compared to Comparative Example 1. However, when the Al concentration is as high as about 20% to about 50% as in Examples 5 and 6, it can be seen that the mobility value is significantly reduced on the contrary. This is thought to be due to the excessively high Al atomic concentration that the crystallized ZnO thin film structure cannot be maintained by Al decomposing the ZnO matrix.

In conclusion, in the composite thin film according to the present invention, when the doped region layer is provided under the thin film (position) and the dopant concentration is adjusted to an appropriate low value (concentration, within about 7%), It was confirmed that the thin film mobility can be improved, thereby providing an excellent thin film for the transistor operating layer.

Claims (21)

1. In a composite thin film having a doped region layer and a non-doped region layer and asymmetric in composition in the thickness direction,

   The doped region layer is a laminate structure formed by atomic layer deposition (ALD), and has a dopant atomic layer formed by using a dopant precursor.
2. The method of claim 1, wherein the doped region layer further comprises at least one thin film matrix atomic layer formed using a thin film matrix precursor,

   A composite thin film characterized in that the lamination of a dopant atomic layer and a thin film matrix atomic layer in accordance with a constant ALD cycle circulation rules, or laminated without a constant rule.
3. 3. The method of claim 2, wherein when there are N dopant atomic layers in the doped region layer and M thin film matrix atomic layers (N and M are integers of 1 or more),

   N: M is a composite thin film, characterized in that 1: 1 to 1:40.
4. The composite thin film according to claim 1, wherein two or more dopant atomic layers formed by using a dopant precursor in the doped region layer are successively stacked.
5. The composite thin film according to claim 1, wherein the composite thin film is formed on a substrate.
6. The composite thin film according to claim 1, wherein the composite thin film is an insulating film of a DRAM, and the doped region layer is formed at a portion to be bonded to an electrode.
7. The composite thin film according to claim 1, wherein the composite thin film is an operating layer of a thin film transistor, and the doped region layer is formed at an interface with a semiconductor.
8. The composite thin film according to claim 1, wherein the composite thin film is an operating layer of a thin film transistor, and the doped region layer is formed on a surface of the composite thin film.
9. The composite thin film of claim 1, wherein the doped region layer is 2 nm to 4 nm.
10. The method of claim 2, wherein the dopant precursor and the thin film matrix precursor are each different metal source compounds, and the metal is Ti, Hf, Zr, Si, Al, Ta, Sr, Ba, Sc, Y, La, Eu, and Composite thin film characterized in that selected from the group consisting of Dy.
11. The method of claim 2, wherein the dopant precursor comprises trimethyl aluminum (TMA),

    The thin film matrix precursor is a composite thin film comprising diethyl zinc (DEZ).
12. As a method of manufacturing the composite thin film according to any one of claims 1 to 11 on a substrate by using an atomic layer deposition (ALD) method,

    Laminating one or more dopant atomic layers using a dopant precursor to form a doped region layer,

    The forming of the doped region layer may include: a first step of depositing the dopant atomic layer by an ALD cycle by pulsing a dopant precursor in a reaction chamber; And

    Pulsed the thin film matrix precursor to deposit a thin film matrix atomic layer by an ALD cycle;

    The first step and the second step is characterized in that the proceeding in the order opposite to each other.
13. The method of claim 12, wherein the ALD cycle,

    Pulse a dopant precursor or thin film matrix precursor in the reaction chamber;

    B) removing excess dopant precursor or thin film matrix precursor from the reaction chamber;

    C) pulsed reactant in the reaction chamber; And

    And d) removing excess reactants and reaction products from the reaction chamber.
14. The method of claim 12, wherein the ALD cycle of the first step is performed n times,

    The ALD cycle of the second step is performed m times,

    Manufacturing method characterized in that the doping concentration can be adjusted by adjusting the number of n and m.
15. The method of claim 14, wherein n: m is 1: 1 to 1:40.
16. The manufacturing method according to claim 14, wherein the first step and the second step are performed repeatedly.
17. The method of claim 12, wherein the dopant precursor and the thin film matrix precursor are each different metal source compounds, and the metal is Ti, Hf, Zr, Si, Al, Ta, Sr, Ba, Sc, Y, La, Eu, and A manufacturing method characterized by being selected from the group consisting of Dy.
18. The method of claim 12, wherein the dopant precursor comprises trimethyl aluminum (TMA),

    And the thin film matrix precursor comprises diethyl zinc (DEZ).
19. The method of claim 13, wherein the reactant of step c is at least one selected from the group consisting of H ₂ O, O ₂ , O ₃ , O radicals, H ₂ O _2, and D ₂ O.
20. An electronic device comprising the composite thin film according to any one of claims 1 to 11.
21. The electronic device of claim 20 which is a transistor or a DRAM.

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