KR20210157756A - Method for Enhancement of Charge Mobility by Passivation Using Amorphous Hydrocarbon Thin Films - Google Patents

Abstract

The present invention relates to a method for improving the charge mobility of a charge channel layer in a structure including a charge channel layer through which charges move, such as an electrode or a thin film transistor. More particularly, it relates to a method for improving charge mobility of a charge channel layer that has the feature of performing passivation using an amorphous hydrocarbon thin film on some or all of the surface of the charge channel layer.

Description

Method for Enhancement of Charge Mobility by Passivation Using Amorphous Hydrocarbon Thin Films

The present invention relates to a method for improving the charge mobility of a charge channel layer in a structure including a charge channel layer through which charges move, such as an electrode or a thin film transistor.

Field-effect transistors are being applied to various electronic applications such as memories, sensors, displays, and logic circuits. Advanced electronic materials such as carbon nanotubes and graphene) are attracting attention. The field effect transistor has a problem in that the operation speed is slow and the transmission conductance is low compared to the junction type transistor because the capacitor structure is formed by the insulating layer placed under the gate. However, since the gate current is almost zero, it is suitable for high-density integration compared to the junction type transistor, so it occupies a majority in modern integrated circuits.

The miniaturization and integration of transistors has already reached the limit of size reduction as it has already been researched and developed down to the molecular level. The operating speed of the field effect transistor is determined by the charge mobility of the channel layer. Therefore, in order to realize a fast operation speed, the charge mobility in the channel layer must be high, and it is necessary to develop a field effect transistor with a total mobility much faster than the current level for more calculations, processing, and information transfer. In the conventional transistor, various attempts have been made, such as using various materials or structurally modified to fabricate a new structure in order to increase electron mobility. However, there is a limitation in that it is difficult to actually apply to the existing process line because it hardly utilizes the existing process equipment, the unit cost of the material is high, or the process is relatively complicated, resulting in additional process cost. Accordingly, there is a need for an efficient method capable of increasing the charge mobility in the channel layer of the existing field effect transistor by a simple process using an inexpensive material.

Carbon thin films have attracted a lot of attention in technical and industrial applications due to their excellent electrical and mechanical properties. The carbon-based material constituting the carbon thin film may be classified into diamond, graphene, and amorphous carbon according to bonding.

Research on carbon-based materials is focused on nanostructures with highly ordered structures such as graphene and carbon nanotubes, which have high potential as transparent conductors or next-generation semiconductors due to their high conductivity properties and transparency. On the other hand, amorphous carbon has also not received much attention despite exhibiting various interesting properties. Since amorphous carbon contains a significant proportion of so-called "dangling bonds", which mean fixed free radicals, there is a possibility of developing materials having various properties by processing under appropriate conditions. However, attempts to develop and apply new materials using amorphous carbon have been very limited.

The amorphous hydrocarbon film can be used as an etching mask or used as an etching mask by using the properties that it is easy to form a flat thin film of uniform thickness, has excellent interfacial bonding with organic and inorganic layers, and has low dielectric properties (Patent Publication No. 10-2010-0112070). , Registration Patent No. 10-1837370), used as a protective film of an insulating film (Registration Patent No. 10-1464909), or as a low-k insulator such as an interlayer material of semiconductor metal wiring to prevent thin film defects and increase interlayer adhesion ( Registered Patent No. 10-0850495) has been used. However, there has been no report so far that an amorphous hydrocarbon film is used to improve the mobility of the channel layer.

Patent Publication No. 10-2010-0112070 Registered Patent No. 10-1837370 Registered Patent No. 10-1464909 Registered Patent No. 10-0850495

In order to solve the problems of the prior art, the present invention provides a method for remarkably increasing the charge mobility of the charge channel layer, which is a path through which charges move, simply by forming a passivation layer by a simple process using an inexpensive material. intended to provide

The present invention for achieving the above object relates to a method for improving charge mobility of a charge channel layer, characterized in that a part or the whole of the surface of the charge channel layer is passivated with an amorphous hydrocarbon thin film.

First, throughout this specification, "charge channel layer" refers to a path through which charges move, and may include, but is not limited to, a channel layer in a transistor, an electrode of a solar cell or a light emitting device, and charges in various devices or devices. collectively refers to all the components responsible for the movement path of

When a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated. And when a part of a layer, film, region, plate, etc. is “on” or “on” or “on” another part, this is not only when it is “directly on” another part, but also when there is another part in between. also includes Conversely, when we say that a part is "just above" another part, we mean that there is no other part in the middle. Similarly, the term “under” or “under” or “under” another part of a layer, film, region, plate, etc. includes cases where it is “directly under” another part, as well as with another part in between. do. Conversely, when a part is said to be "just below" another part, it means that there is no other part in the middle. In addition, when a part is said to be formed "whole" on another part, it includes not only what is formed on the whole surface of another part, but also what is not formed on a part of the edge.

In the present invention, "amorphous" means that there is no long-range order with respect to the positions of atoms, and "amorphous hydrocarbon" means that a part of the dangling bond of carbon is terminated by hydrogen as having an amorphous structure. it means.

In addition, in the present specification, "substrate" serves as a substrate for thin film growth, and as well as substrates such as silicon, glass, metal, metal oxide, and plastic used in the production of thin films, an additional active layer is formed thereon. Also includes a board with It goes without saying that the substrate can be appropriately selected according to the type and purpose of the thin film to be grown.

In the drawings of the present invention, for convenience of description, the size, thickness, shape, etc. of some layers and regions may be exaggerated or simplified. This is in order to clearly indicate the various layers and regions, and does not mean a ratio in an actual device.

As can be seen in the following examples, charge mobility was significantly increased by passivating a part or all of the surface of the charge channel layer with an amorphous hydrocarbon thin film. When compared under the same conditions, the charge mobility of the charge channel layer increased more than 300 times compared to before passivation by the amorphous hydrocarbon thin film, and as the conditions were changed, the charge mobility reported in the prior art was greatly exceeded. gave. Although the passivation layer is formed only on the upper surface of the charge channel layer in the following embodiment, it is natural that the passivation layer may be formed only on the lower surface or may be formed simultaneously on the upper surface and the lower surface. Alternatively, the charge channel layer of the present invention may be formed only on a portion of the upper surface and/or the lower surface according to the structure and characteristics of the device to which it is applied. In this case, the passivation layer of the amorphous hydrocarbon may be directly grown on the channel layer or may be formed through a transfer process after growing on the catalyst substrate. When directly grown on the channel layer, there is an advantage in that a uniform and fewer defects can be formed because a transfer process is not performed. On the other hand, growing a hydrocarbon thin film through a transfer process has the advantage that it is not limited by the type of substrate. If the substrate itself or the active layer deposited on the substrate is not stable under the growth conditions of the amorphous hydrocarbon thin film, the transfer process may be more advantageous than the direct growth.

In the present invention, the thickness of the amorphous hydrocarbon thin film constituting the passivation layer is preferably controlled appropriately in the range of a single atomic layer thickness of ~ 1 ㎛, preferably 1 nm ~ 100 nm. The atomic size of carbon is about 0.15 nm, and the thickness of the amorphous hydrocarbon thin film is about 0.2 nm. The size of the amorphous hydrocarbon thin film may be used in an appropriate range as needed in consideration of the type and use of the charge channel layer.

For example, in the present invention, the charge channel layer may be a channel layer of a thin film transistor. More specifically, an insulating layer formed on the substrate; a source electrode and a drain electrode spaced apart from each other on the insulating layer; It may be a channel layer of the thin film transistor including; a channel layer electrically connecting the source electrode and the drain electrode.

Since the present invention is characterized in that charge mobility is improved by passivating the channel layer with an amorphous hydrocarbon thin film, it is not limited by the specific structure of the material or device constituting the channel layer. Therefore, any material constituting the channel layer of the present invention may be used as long as it is used as a channel layer in a device using a conventional semiconductor or conductor. For example, the channel layer may be formed of a semiconductor material such as silicon, a metal oxide semiconductor, or an organic semiconductor, or a conductive material such as graphene. The channel layer may be doped with other elements to improve device characteristics. Since the present invention does not relate to material properties of the channel layer, a detailed description thereof will be omitted, but it will be easy for those skilled in the art to select and use a material having appropriate properties from the prior art.

The source electrode and the drain electrode may be formed of a general electrode material, that is, a metal or a conductive oxide. The source electrode and the drain electrode may be a single layer or a multilayer, and the specific shape and location thereof may be variously designed as long as they can be electrically connected by a channel layer.

In particular, when the transistor is an electric field induction thin film transistor, the passivation layer made of the amorphous hydrocarbon thin film may act as a gate dielectric film. In this case, the field induction thin film transistor may be configured by forming the gate electrode on the gate dielectric layer without forming a separate gate dielectric layer. Alternatively, in the case of a bottom gate structure, the gate electrode may be formed under the channel layer.

When passivation is used as the gate dielectric film, it is more preferable that the amorphous hydrocarbon thin film be a high-k film having a dielectric constant of 10 or more. An amorphous hydrocarbon thin film has been recognized as a low-k material with a low dielectric constant. However, when producing an amorphous hydrocarbon thin film using plasma, it was confirmed that a high-k amorphous hydrocarbon thin film can be grown by adjusting the deposition temperature and pressure, the flow rate of the reaction gas, and plasma power, and the present inventors have a dielectric constant of 10 or more. A patent application for a high-k film made of an amorphous hydrocarbon thin film was filed on June 12, 2020 with Application No. 10-2020-0071703. The high-k film has a dielectric constant of 10 or more, preferably 20 to 200, more preferably 30 to 150, which is significantly higher than the dielectric constant of hafnium (Hf) or zirconium (Zr) oxide known in the prior art as a high-k oxide. characteristics were shown. Moreover, the surface roughness is very low, so defects at the interface are low, the leakage current is 1 A/cm ² or less, the insulation strength is 1 MV/cm or more, preferably the leakage current is 0.5 A/cm ² or less, and the insulation strength was more than 5 MV/cm. In one embodiment, the leakage current was 0.25 A/cm ² at an equivalent oxide film thickness of 0.2 nm, which exhibited very good characteristics compared to that of the Hf- or Zr-based oxide showing a high leakage current (data not shown).

As another example, the charge channel layer may be an electrode. The electrode includes, for example, an electrode applicable to a display, a solar cell, and a light emitting diode, but is not limited thereto. Examples of the electrode material include a semiconductor electrode, a metal electrode, a transparent electrode, and a flexible electrode.

An additional insulating film may be formed on the passivation layer according to the present invention. As the additional insulating layer, a layer made of a high- _{k material such as silicon oxide, silicon nitride, silicon nitride, Ta 2} O ₄ , Al ₂ O ₃ , Hf- or Zr-based oxide may be used, but is not limited thereto.

The amorphous hydrocarbon thin film of the present invention comprises the steps of (A) positioning a substrate in a plasma reactor; (B) injecting a first gas containing hydrocarbon gas and a second gas containing hydrogen gas into the reactor; and (C) generating plasma in the reactor.

In the present invention, when the passivation layer is directly grown on the channel layer, a substrate on which the channel layer is formed is used as the substrate. If the passivation layer is prepared by transfer, since the amorphous hydrocarbon thin film is first prepared and then transferred onto the channel layer, a kind of substrate advantageous for the transfer process after growth of the amorphous hydrocarbon thin film, for example, a substrate on which a catalyst metal layer is formed can be used

In the present invention, the plasma reactor is to induce a reaction of a reaction gas by generating plasma in the reactor, for example, plasma-assisted chemical vapor deposition (PE-CVD), inductively coupled plasma chemical vapor deposition (ICP-CVD), electron cyclotron resonance and a chemical vapor deposition (ECR-CVD) reactor. Plasma generates a large amount of highly reactive radicals from the reaction gas, so that a thin film can be formed even at a low temperature. In the following examples, ICP-CVD has been described as an example, but it is of course not limited thereto.

As the reaction gas, the first gas includes hydrocarbon gas, and any hydrocarbon gas can be used as long as it can form a hydrocarbon thin film by plasma. At least one selected from the group consisting of methane, ethane, propane, ethylene, acetylene, propylene and benzene may be used. The first gas may include an inert gas in addition to the hydrocarbon gas.

The second gas includes hydrogen gas, and may further include an inert gas in addition to hydrogen gas.

In addition to the first gas and the second gas, an inert gas such as argon or helium may be further included as a transport gas.

In the present invention, the deposition temperature of the amorphous hydrocarbon thin film is preferably room temperature ~ 600 ℃. When the deposition temperature was higher than 600 °C, the hydrocarbon thin film began to show crystallinity.

The pressure in the reactor is preferably 0.1 to 10 Torr so that plasma discharge can be smoothly performed. When the pressure is too high, it is difficult to maintain the plasma, so that the hydrocarbon thin film deposition efficiency is lowered, and when the pressure is too low, the process efficiency may be reduced.

In the present invention, a mixture of hydrocarbon gas and hydrogen gas is used as a reaction gas to induce dangling bonds and hydrogen bonds that increase in the thin film as the thin film manufacturing temperature is lowered. In step (B), the volume ratio of the hydrocarbon gas in the first gas and the hydrogen gas in the second gas is preferably about 100:1 to 1:50. If the ratio of hydrogen gas is too low, the surface of the thin film may be roughened and surface properties may be deteriorated. If the ratio of hydrogen gas is too high, the hydrocarbon thin film may not be formed well.

In the present invention, the intensity of plasma also affects the properties of the thin film. The intensity of the plasma can be adjusted in the range of 100 ~ 1,000 W. As the intensity of the plasma increases, the growth rate of the thin film increases and the surface roughness decreases, but the intensity of 1,000 W or more is not excluded. In addition, when the plasma intensity is low, the thickness or surface roughness of the thin film can be adjusted by increasing the deposition time, so less than 100 W is not excluded.

Since the optimum reactor temperature, pressure, flow rate of first gas, flow rate of second gas, and plasma intensity are mutually influencing factors, even if one parameter shows an optimum value at a specific value when other values are fixed, , it is natural that the absolute value may change when other variables are adjusted.

The properties of the amorphous hydrocarbon thin film produced by the above process may be controlled by the deposition temperature, pressure, flow rate of the first gas, flow rate of the second gas, and intensity of plasma. Therefore, it will be possible to optimize the conditions by changing the above conditions to have characteristics such as thickness and surface roughness of the thin film depending on the device to be used.

It was confirmed that it had an amorphous structure in the TEM image and Raman spectrum of the thin film prepared by the above method, and it was confirmed that it was composed of an amorphous hydrocarbon containing ^{sp 3 bond of carbon-hydrogen through XPS, FTIR, and secondary ion mass spectrometry.} . In addition, it was confirmed that the composition of the thin film was uniform because there was no change in the peaks of the XPS spectrum and secondary ion mass spectrometry observed while etching with ^{Ar + plasma.}

Although specific data are not described in the Examples below, among the thin films prepared in Example 1, the thin film deposited on a silicon substrate exhibited a dielectric constant of 10 to 90 when deposited in the range of 200 to 500 ° C, Ag The thin film deposited on the catalyst exhibited a dielectric constant of about 10 to 60 when deposited at a temperature of 300 to 600 °C. However, this is a value when the flow rate and plasma power of the reaction gas are fixed to the conditions of Example 1, and since the ratio, flow rate, and plasma power of the reaction gas also affect the dielectric constant, the dielectric constant under the temperature condition is absolute. is not doing

The present invention also provides a thin film transistor and an electrode in which a part or all of the surface of the charge channel layer is passivated by an amorphous hydrocarbon thin film.

As described above, according to the present invention, the charge mobility can be remarkably increased by just passivating the charge channel layer with an amorphous hydrocarbon thin film that can be grown in a simple process using inexpensive raw materials. It is possible to greatly improve the characteristics of a device including a charge channel layer that is required to move quickly.

1 is a schematic diagram and TEM image of a carbon-based thin film produced according to the deposition temperature.
2 is a Raman spectrum of a carbon-based thin film produced according to a deposition temperature.
3 is an EELS spectrum of the carbon-based thin film produced according to the deposition temperature.
4 is an XPS spectrum and EXAFS spectrum of an amorphous hydrocarbon thin film prepared according to an exemplary embodiment of the present invention.
5 is an FTIR spectrum of an amorphous hydrocarbon thin film prepared according to an exemplary embodiment of the present invention.
6 is a secondary ion mass spectrometry spectrum of an amorphous hydrocarbon thin film prepared according to an exemplary embodiment of the present invention.
7 is a schematic diagram showing a cross section of a field effect transistor according to an embodiment of the present invention.
8 is a graph showing the measurement results of the gate voltage-drain current characteristics of the graphene field effect transistor according to the comparative example of the present invention.
9 is a graph showing electrical characteristics of a field effect transistor including a transferred amorphous hydrocarbon thin film according to an embodiment of the present invention.
10 is a graph showing electrical characteristics of a field effect transistor including a directly deposited amorphous hydrocarbon thin film according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the accompanying examples. However, these embodiments are merely examples for easily explaining the content and scope of the technical idea of the present invention, and thereby the technical scope of the present invention is not limited or changed. It will be natural for those skilled in the art that various modifications and changes can be made within the scope of the technical spirit of the present invention based on these examples.

[Example]

Example 1: Preparation of hydrocarbon thin film according to deposition temperature

Si wafer or Si/SiO ₂ /Ag (200 nm) A hydrocarbon thin film was deposited on the substrate by inductively-coupled plasma chemical vapor deposition (ICP CVD) using _{CH 4} gas and hydrogen gas under the following conditions. Specifically, 1 sccm of CH ₄ gas and 100 sccm of hydrogen and Ar mixed gas (hydrogen 10%) were injected into the reactor, and the pressure was fixed at 1 Torr and the plasma power at 600 W.

A hydrocarbon thin film was prepared by growing the thin film at a deposition temperature of 50° C. to 950° C. for 5 minutes. The thin film deposited at 950° C. was deposited on a copper substrate, which is a catalyst metal for the growth of graphene.

For comparison, graphite was oxidized in a chemical solution using the Hummer method and peeled off to prepare a graphene oxide thin film.

Example 2: Characteristic evaluation of hydrocarbon thin film

1) Transmission electron microscope image and Raman spectrum analysis

The hydrocarbon thin film grown according to the deposition temperature in Example 1 was confirmed with an aberration-corrected transmission electron microscope (Aberration-corrected TEM; Titan G2 Cube 60-300 kV, FEI), and the results are shown in FIG. 1 .

FIG. 1 b is a TEM image of a hydrocarbon thin film deposited at 950° C., showing that carbon atoms have a highly ordered hexagonal arrangement. The inner figure shows a fast Fourier transformed (FFT) digital diffractogram and shows a hexagonal pattern, which is a typical characteristic of high-quality graphene. In the Raman spectrum of FIG. 2, I _2D /I _G showed a high value of about 3, and the maximum half width of the 2D peak ^{was small as 32 cm -1 ,} and it was confirmed that a high-quality graphene thin film was formed in Comparative Example 1.

The thin film with a deposition temperature of 700° C. exhibited a nanographite morphology in which hexagonal lattice nanocrystals were partially present in an amorphous matrix ( FIG. 1 c ). The FFT shows a diffuse ring shape with dark spots (indicated by circles). The spacing between dots is 0.246 nm, which corresponds to carbon allotrope hexagonite.

When the deposition temperature was further lowered to 400 °C or 50 °C, the thin film lost nanocrystallinity, exhibited an amorphous structure, and showed a halo FFT pattern (Fig. 1 d, e).

The hydrocarbon thin film having a deposition temperature of 700° C. or less did not show any significant peak in the region of ^{2000 cm −1 or more in the Raman spectrum shown in FIG. 2 .}

2) EELS spectrum analysis

Using an electron energy-loss spectroscopy (EELS) device (Gatan Quantum 965 dual), the EELS spectrum of each of the thin films prepared in Example 1 was measured. For comparison, the EELS spectrum was also measured for the graphene oxide thin film prepared by oxidizing graphite in a chemical solution using the Hummer method and exfoliating it. 3A and 3B are EELS spectra of a low-loss region and a carbon K-edge region, respectively, and the bonding pattern of the hydrocarbon thin film according to the deposition temperature can be confirmed.

3a, the graphene thin film showed two characteristic peaks, the strong peak of 5 eV is a π plasmon peak related to π→π* transition by ^{sp 2 bond of carbon, and a broad peak near 15.5 eV} is a (π+σ) plasmon peak. The position of the (π+σ) plasmon peak is proportional to the density of valence electrons, that is, the mass density of the carbon thin film. Compared to the graphene thin film grown at 950 ° C, the intensity of the π plasmon peak in the thin film with the deposition temperature lowered to 700 ° C was significantly reduced, and a TEM image showing the presence of nanocrystalline ^{hexagonite having sp 2 bonds in the amorphous matrix.} was consistent with the results of As the deposition temperature was further lowered, only (π+σ) plasmon peaks were observed in the thin films grown at 400°C and 50°C, respectively. In the deposited thin film at a temperature not higher than 700 ℃ (π + σ) energy of the plasmon peak is low, about 5 eV degree than 25.0 eV, 24.5 eV, and a 25.8 eV sp ³ bonded carbon thin film is a large amount, respectively, sp ³ bond suggests that the proportion of The reason that the energy exhibited a relatively large value in the thin film prepared at 700°C is thought to be because a dense crystalline state was contained.

The presence of π bonds in the thin film can also be confirmed in the EELS spectrum of the carbon K-edge region shown in FIG. 3b . The thin films prepared at 50°C and 400°C have the first peak observed at 281 eV, which corresponds to the transition (1s→π*) from the 1s state to the π* state above the Fermi level. From the strong peak observed in the corresponding region, it can be confirmed that a ^{significant amount of sp 2 bonds exists in the amorphous thin film.} The second peak was observed very broadly in the 290-305 eV region, which corresponds to the 1s→σ* transition. When the deposition temperature was increased to 700 °C, the first peak was observed at ~289.5 eV, indicating that the energy band was narrowed by nanocrystallization. This peak was observed more clearly in graphene prepared at 950 °C. According to the EELS spectrum, the thin films prepared at 50°C and 400°C were very similar to the amorphous hydrocarbons reported by J. Fink et al. (Physical Review B, 30, 4713-4718 (1984)). On the other hand, the EELS spectrum of graphene oxide showed a very different aspect from that of hydrocarbons.

3) XPS and EXAFS spectrum analysis

The chemical bonding properties of the hydrocarbon thin film prepared at 400° C. were confirmed by X-ray photoelectron spectroscopy (XPS) and extended X-ray absorption fine structure (EXAFS). 4A is an XPS spectrum measured using MultiLab 2000 (Thermo Fisher Scientific) equipment for a thin film prepared at 400° C. and a thin film etched for 5 to 20 seconds with argon plasma of 1 keV intensity. As can be seen in FIG. 4 a, 285.3 eV corresponding to _{the aliphatic hydrocarbon C x} H _y is observed in the XPS spectrum of the hydrocarbon thin film, and the position of the corresponding peak does not change even after etching using ^{Ar + plasma, so the composition of the hydrocarbon thin film} This uniformity was confirmed. Although not shown separately, in the XPS spectrum of the graphene thin film, the position of the peak shifted from 285.0 eV to 284.4 eV according to the etching of the surface. The graphene surface exposed to air can adsorb various types of hydrocarbons, resulting in a high binding energy of 285.0 eV. When the hydrocarbons on the surface are removed by etching, the binding energy of graphene itself is 284.4 eV.

4B is an EXAFS spectrum at the 1s core level, and c is an EXAFS spectrum near the Fermi level. The strong peak of 285.1 eV in FIG. 4b corresponds to the 285.3 eV peak of the XPS spectrum. In order to confirm that a significant amount of hydrogen is contained in the hydrocarbon thin film, the thin film was prepared and then heat-treated in-situ at 700°C. After the heat treatment, the position of the peak was redshifted to 284.7 eV, indicating that hydrogen was desorbed from _{the aliphatic hydrocarbon C x} H _{y .} As a result, the desorbed sample increased the density of the expanded state, and as can be seen in FIG. 4c , the strength in the region near the Fermi level was increased.

4) Secondary ion mass spectrometry

For the hydrocarbon thin film grown at a deposition temperature of 200°C to 400°C according to the method of Example 1, secondary-ion mass spectrometry (SIMS) equipment (TOF.SIMS M6, IONTOF GmbH) was used. Spectra of 0 to 8 seconds of etching time were obtained while etching under room temperature and high vacuum, and the results are shown in FIG. 5 .

In FIG. 5 , it was confirmed that the relative intensity ratio (H/C) of hydrogen to carbon in the hydrocarbon thin film was 2 to 30. In the SIMS spectrum of the thin film, the H/C intensity was affected by the deposition temperature of the thin film. When the deposition temperature was increased at 200 °C, the H/C intensity increased, showing the highest value at about 250 to 300 °C, and the temperature was further increased. As it increased, it showed a tendency to decrease again. This suggests that the concentration of hydrogen contained in the thin film is determined by the deposition temperature.

The H/C strength of the thin film according to the etching time did not show a significant difference, and it could be confirmed that the composition of the hydrocarbon thin film was uniform like the XPS result.

5) spectroscopic analysis

CH bonding was confirmed through the spectroscopic analysis of the graphene thin film and the hydrocarbon thin film grown at 400 °C. 6 shows the FRIR spectrum of the thin film grown at the deposition temperature of 400° C. of Example 1, and the peak corresponding to the CH stretching of the region of ^{2500-3000 cm -1 that was not observed in graphene and the region of 500-1200 cm -1} A peak corresponding to the CH banding of is observed, confirming once again that the CH bond is formed.

Example 3: Passivation of field effect transistor using amorphous hydrocarbon thin film

A field effect transistor (comparative example) having the structure shown in FIG. 7 a and a channel layer shown in b (preparation example 1) or c (preparation examples 2 to 5) of FIG. 7 in which the channel layer is passivated with an amorphous hydrocarbon thin film After the field effect transistor having the structure was manufactured, the charge mobility of the channel layer was evaluated to evaluate the effect of the passivation layer on the charge mobility of the channel layer. The amorphous hydrocarbon thin film was grown on the catalyst metal and then transferred (Preparation Example 1) or directly grown on the channel layer (Preparation Example 2) to prepare a field effect transistor. A more specific manufacturing process is as follows.

Comparative Example 1: Graphene Field Effect Transistor

Graphene grown by CVD on a copper substrate was transferred onto a _{Si/SiO 2 wafer.} A pattern with a length of 50 μm and a width of 10 μm was formed through an ultraviolet photolithography process, and was etched for 15 minutes with 150 W Ar plasma at 600 mTorr. After etching, the photoresist was removed using acetone.

After the photolithography process, a metal (Au) thin film was deposited using sputtering, and a source electrode and a drain electrode were formed through a lift-off process to fabricate a graphene field effect transistor.

Comparative Examples 2 to 4

The field effect transistors of Comparative Example 1 were heat-treated under vacuum at 100, 150, and 200° C. for 20 minutes, respectively, and used as the field effect transistors of Comparative Examples 2 to 4.

Preparation Example 1: Field effect transistor to which an amorphous hydrocarbon passivation layer is transferred

By the method of Example 1, _{an amorphous hydrocarbon thin film grown at a deposition temperature of 400° C. on a Si/SiO 2} /Ag substrate was transferred onto the channel layer of Comparative Example 1 to prepare a field effect transistor having an amorphous hydrocarbon passivation layer. .

Preparation Example 2: Field Effect Transistor to which an amorphous hydrocarbon passivation layer was transferred

An amorphous hydrocarbon thin film was grown in-situ at room temperature on graphene grown by CVD on a copper substrate for 30 minutes. The deposition pressure was 1 Torr, and the plasma power was 600 W. The thickness of the grown amorphous hydrocarbon thin film was 2-3 nm.

The graphene/amorphous hydrocarbon multilayer thin film prepared above was transferred on _{the Si/SiO 2} wafer on which the source electrode and the drain electrode were formed. A pattern having a length of 50 μm and a width of 10 μm was formed in the same manner as in Comparative Example 1 through an ultraviolet photolithography process, and after etching with 150 W Ar plasma at 600 mTorr for 15 minutes, the photoresist was removed using acetone.

Preparation Example 3: Field effect transistor in which an amorphous hydrocarbon passivation layer is directly grown

A field effect transistor having an amorphous hydrocarbon passivation layer was fabricated in the same manner as in Preparation Example 2, except that the deposition temperature of the amorphous hydrocarbon thin film was set to 100°C.

Preparation Example 4: Field effect transistor in which an amorphous hydrocarbon passivation layer was directly grown

of the amorphous hydrocarbon thin film A field effect transistor having an amorphous hydrocarbon passivation layer was manufactured in the same manner as in Preparation Example 2, except that the deposition temperature was set to 300°C.

Preparation Example 5: Field effect transistor in which an amorphous hydrocarbon passivation layer is directly grown

A field effect transistor having an amorphous hydrocarbon passivation layer was manufactured in the same manner as in Preparation Example 2, except that the deposition temperature of the amorphous hydrocarbon thin film was set to 500°C.

8 is a graph showing the measurement results of the gate voltage-drain current characteristics of the graphene field effect transistors prepared in Comparative Examples 1 to 4 when the drain voltage (V _{DS ) is 0.5 V and 10 V, respectively.} It shows that the Dirac voltage decreases as the heat treatment temperature increases, and it can be seen that the charge mobility of the graphene channel layer increases from the increase of the slope. From the graph of FIG. 8 _{, the charge mobility when V DS} = 0.5 V was calculated and described in Table 1.

9 is a graph showing electrical characteristics of the field effect transistor of Preparation Example 1. Referring to FIG. 9 a) From the drain voltage-drain current graph, it is shown that the field effect transistor corresponds to the ohmic region in both the drain voltage of -2 to +2 V and the gate voltage of -40 to 40 V. Fig. 9b) shows a gate voltage-drain current graph according to the drain voltage, and Fig. 9c) is a graph showing the charge mobility calculated therefrom according to the drain voltage.

When V _DS = 0.5 V, the charge mobility of the channel layer of Preparation Example 1 was 21,913 cm ² /Vs. This is a whopping 332 times higher mobility compared to Comparative Example 1 before passivation with an amorphous hydrocarbon, and it can be confirmed that the charge mobility is remarkably improved compared to Comparative Examples 2 to 4 in which the graphene layer was heat treated. Moreover, when V _DS = 0.1 V, the charge mobility of the channel layer of Preparation Example 1 was 103,304 cm ² /Vs, which greatly exceeded the charge mobility of the graphene field effect transistor reported so far.

10 is a graph showing the measurement results of the gate voltage-drain current characteristics of the field effect transistors of Preparation Examples 2 to 5; Table 2 shows the charge mobility values when _{V DS} = 0.5 V calculated from the graph.

In Table 2, it can be seen that the charge mobility of the field effect transistor increased as the channel layer was passivated with an amorphous hydrocarbon. In particular, in the case of Preparation Example 3, the synergistic effect of charge mobility was most remarkable. The fact that the charge mobility of Preparation Example 2 is lower than that of Preparation Example 1 seems to reflect the difference in the manufacturing process of the field effect transistor.

As such, in the field effect transistor in which the channel layer was passivated by the amorphous hydrocarbon thin film, the mobility of graphene used as the channel layer was significantly improved compared to that in the field effect transistor without the passivation layer. This mobility is a result of greatly exceeding ^{40,000 cm 2} /Vs, which is the current record of the charge mobility of graphene transferred on _{SiO 2 .}

Claims (11)

A method for improving charge mobility of a charge channel layer, characterized in that a part or all of the surface of the charge channel layer is passivated with an amorphous hydrocarbon thin film.
The method of claim 1,
The method for improving charge mobility of the charge channel layer, characterized in that the amorphous hydrocarbon thin film is directly grown on the surface of the channel layer or passivated by transferring the amorphous hydrocarbon thin film to the surface of the channel layer.
3. The method of claim 2,
The thickness of the amorphous hydrocarbon thin film is a single atomic layer thickness ~ 1 ㎛ charge channel layer charge mobility improvement method, characterized in that.
4. The method according to any one of claims 1 to 3,
The charge channel layer is a method for improving charge mobility of the channel layer, characterized in that the charge channel layer of the thin film transistor.
5. The method of claim 4,
The channel layer is a method for improving charge mobility of the charge channel layer, characterized in that at least one selected from the group consisting of silicon, metal oxide semiconductor, organic semiconductor, and graphene.
6. The method according to claim 4 or 5,
The thin film transistor is a field induction thin film transistor,
A method for improving charge mobility of a charge channel layer, characterized in that the passivation layer made of the amorphous hydrocarbon thin film acts as a gate dielectric layer.
7. The method of claim 6,
A method for improving charge mobility of the charge channel layer, characterized in that the dielectric constant of the amorphous hydrocarbon thin film is 10 or more.
4. The method according to any one of claims 1 to 3,
The method for improving charge mobility of the channel layer, characterized in that the charge channel layer is an electrode.
9. The method of claim 8,
The electrode is a semiconductor electrode, a metal electrode, a method for improving the charge mobility of the channel layer, characterized in that a transparent electrode or a flexible electrode.
A thin film transistor, characterized in that part or all of the surface of the charge channel layer is passivated by an amorphous hydrocarbon thin film.
An electrode, characterized in that part or all of the surface of the charge channel layer is passivated by an amorphous hydrocarbon thin film.

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