KR101937293B1 - Method of manufacturing for two-dimensional tin disulfide thin film - Google Patents

Abstract

The present invention relates to a method for forming a tin disulfide thin film comprising the steps of forming a tin oxide thin film on a substrate and sulfiding the tin oxide thin film.

Description

METHOD OF MANUFACTURING FOR TWO-DIMENSIONAL TIN DISLFIDE THIN FILM [0002]

The present invention relates to a method of forming a _two- dimensional tin disulfide (SnS ₂ ) thin film, and more particularly, to a tin oxide thin film formed by atomic layer deposition using a H ₂ S gas, To a method for forming the same.

The tin disulfide thin film is an n-type two-dimensional material having a layered structure. Due to its high electron mobility, flicker ratio and low cost, it is attracting attention as a channel material in a thin film transistor as a switching device. .

In general, as scale reduction in a switching device is accelerated, much research is under way to overcome the limitations of the existing Si channel, such as degradation of a switching device due to a short channel effect. Accordingly, it is required to synthesize a two-dimensional material channel material having high electron mobility with little deterioration in device performance within a limited length and thickness of the channel.

Atomic layer deposition (ALD) is widely used as a deposition method for growing a thin film of a two-dimensional material. Unlike the conventional transfer method or chemical vapor deposition method, the atomic layer deposition method has a thickness determined according to the number of cycles, and the uniformity of the thin film is very excellent. Therefore, the deposition method which is very effective for forming a continuous thin film of two- to be.

However, due to the weak van der Waals bond between the layer and the layer of the two-dimensional material, atomic layer deposition, which forms a thin film by chemical reaction between the reaction materials of the vapor phase, forms a continuous uniform thin film And it is difficult to control the thickness.

In addition, at the time of thin film deposition using the atomic layer deposition method, the deposition temperature is almost determined by the reaction material. Since thermal decomposition of the reaction material occurs at the time of high-temperature deposition, post-heat treatment is required for crystallization of the thin film. This crystallization method through post-heat treatment causes problems such as formation of discontinuous thin films when the thin film is damaged due to the heat treatment temperature or when the surface energy difference between the thin film and the substrate is large.

Korean Patent Publication No. 1512749 Japanese Patent Application Laid-Open No. 1995-061818

Accordingly, it is an object of the present invention to provide a method for forming a thin film of tin disulfide capable of synthesizing a thin film of a two-dimensional material by an atomic layer deposition method and controlling the thickness thereof.

It is another object of the present invention to provide a method for forming a continuous and uniform tin disulfide thin film having a large area on which crystallization proceeds without causing damage to the tin disulfide thin film.

According to an aspect of the present invention, there is provided a method of manufacturing a semiconductor device, including: forming a tin oxide thin film on a substrate; And a step of sulfiding the tin oxide thin film.

The tin oxide thin film of the present invention can be formed by an atomic layer deposition method, and the sulfidation treatment can provide a method of forming a tin disulfide thin film by heat treatment with a hydrogen sulfide gas.

In addition, the atomic layer deposition method of the present invention includes the steps of: supplying a tin material on a substrate; Purging the tin material; Supplying an oxygen source; And purifying the oxygen source.

In addition, the atomic layer deposition method of the present invention can be performed at a temperature ranging from room temperature to 300 ° C, and the sulphiding treatment can be performed at a temperature ranging from 300 ° C to 400 ° C.

The thickness of the tin oxide thin film of the present invention is determined by the number of cycles of the atomic layer deposition method, and the thickness of the tin disulfide thin film can be determined by the thickness of the tin oxide thin film.

Further, the substrate of the present invention is made of a material having a surface energy higher than that of the tin disulfide thin film to be formed, and may include at least one oxide selected from aluminum oxide, titanium dioxide, zirconium oxide, and hafnium oxide.

Further, the tin raw material of the present invention can be obtained by reacting a tin compound such as tin dichloride, tin tetrachloride, tetrakis-dimethylamino tin, tetrakis-diethylamino tin, tetrakis-ethylmethylamino tin, bis- Methyl-2-propoxy-tin (II), acetylacetone tin, and the like.

The oxygen source of the present invention may include at least one selected from water, oxygen gas, air, a mixed gas of nitrogen and oxygen, methanol, ethanol, isopropanol, ozone, hydrogen peroxide and oxygen plasma.

The present invention can control the number and the thickness of the tin sulfide thin film, and can form a highly pure tin disulfide thin film uniform in a large area.

Further, the present invention can form a tin disulfide thin film having a thickness of a sub-nanometer level.

1 is a schematic flow chart of a method of forming a tin disulfide thin film according to an embodiment of the present invention.
2 is a schematic diagram of a method of forming a tin disulfide thin film according to an embodiment of the present invention.
FIGS. 3A and 3B are graphs showing a change in the thickness of the tin oxide thin film and a change in the thickness of the tin disulfide thin film according to the number of cycles in the atomic layer deposition method according to an embodiment of the present invention. FIG.
4 is a photograph of a tin disulfide surface formed in accordance with one embodiment of the present invention.
5 is a graph showing the chemical bonding of tin disulphide formed according to one embodiment of the present invention.
6 is a graph showing the chemical bonding of tin disulfide formed according to another embodiment of the present invention.
7 is a graph showing a phase change and a degree of crystallization of a tin disulfide thin film formed according to another embodiment of the present invention.
8 is a graph showing a phase change and a crystallization degree of a tin disulfide thin film formed in accordance with another embodiment of the present invention, a photograph of the surface, and chemical bonding.

Hereinafter, a method of forming a tin disulfide thin film according to the present invention will be described with reference to the accompanying drawings.

Prior to explanation, elements having the same configuration are denoted by the same reference numerals in different embodiments, and only other elements will be described in the other embodiments.

1 is a schematic flow chart of a method of forming a tin disulfide thin film according to an embodiment of the present invention. Referring to FIG. 1, a step (S1) of forming a tin oxide thin film on a substrate and a step (S2) of forming a tin oxide thin film to form tin disulphide can be performed.

2 is a schematic diagram of a method of forming a tin disulfide thin film according to an embodiment of the present invention. 2, when the tin oxide 20 deposited on the substrate 10 is subjected to heat treatment with H2S gas, the tin oxide 20 is converted into tin sulfide 30. At this time, depending on the thickness of the tin oxide 20, which is a raw material, tin sulfide 30 as a two-dimensional material can be controlled in a plurality of layers in a nanometer scale, and a uniform thin film of tin (30) have.

Specifically, to form a tin oxide (20) film is SiO ₂ A thin film of tin sulfide (30) can be performed on the substrate and the Al ₂ O ₃ substrate surface by atomic layer deposition (ALD). Atomic layer deposition methods can be implemented through known ALD equipment.

In one embodiment of the present invention, the substrate 10 include one or more oxide selected from aluminum oxide (Al ₂ O _3), titanium dioxide (TiO _2), zirconium oxide (ZrO _2), hafnium oxide (HfO ₂₎ .

Further, in one embodiment of the present invention, the tin oxide 20 may include at least one selected from among tin monoxide (SnO), tin dioxide (SnO ₂ ), and tin (Sn ₂ O ₃ ) It is not.

In addition, in one embodiment of the present invention, the step S1 of forming a thin film of tin oxide 20 on the substrate 10 includes the steps of injecting a tin material on the substrate 10, purifying the tin material , Injecting the oxygen source, and purifying the oxygen source.

On the other hand, in one embodiment of the present invention, as a tin raw material, tin dichloride (SnCl ₂ ), tin tetrachloride (SnCl ₄ ), tetrakis (Dimethylamino) tin, tetrakis-diethylamino tin Tetrakis (ethylmethylamino) tin, Bis (bis (trimethylsilyl) amino] tin, Tetramethyltin, Tetraethyltin, trimethyl (phenyl) tin, dimethylamino-2-methyl-2-propoxy-tin (II) ), And acetylacetone tin (Sn (acac) 2).

In one embodiment of the present invention, the oxygen raw material may include at least one selected from water, oxygen gas, air, a mixed gas of nitrogen and oxygen, methanol, ethanol, isopropanol, ozone, hydrogen peroxide and oxygen plasma.

In one embodiment of the present invention, the step (S1) of forming the tin oxide (20) thin film can be performed at a temperature of from room temperature to 300 캜, but the present invention is not necessarily limited thereto.

Further, in one embodiment of the present invention, the substrate 10 may be SiO ₂ or Al ₂ O _3. For example, an Al ₂ O ₃ substrate may be formed by forming an Al ₂ O ₃ thin film on an SiO ₂ substrate by ALD Or the like.

In one embodiment of the present invention, the Al ₂ O ₃ thin film was formed on the SiO ₂ substrate using ALD method to form a thin film having a thickness of 4 nm at a deposition temperature of 350 ° C., and the temperature and thickness of the substrate 10 of the present invention But is not necessarily limited to.

In one embodiment of the present invention, the reason why the SiO ₂ thin film and the Al ₂ O ₃ thin film are selected is due to the surface energy of the thin film. Specifically, since the surface energy of the SiO ₂ thin film is smaller than that of the tin disulfide thin film and the surface energy of the Al ₂ O ₃ thin film is larger than that of the tin sulphide thin film, the phase transition of the tin- .

In the embodiment of the present invention, the step of sulfiding the tin oxide (20) thin film by using the H ₂ S gas in the tin sulfide (30) thin film forming method is performed in a rapid thermal annealing equipment However, the present invention is not limited thereto.

In one embodiment of the present invention, H ₂ S gas method comprising sulfiding the tin oxide (20) thin film by using the H ₂ S gas mixture (3.5%), and Ar at 100 mtorr pressure for 5 minutes and 300 ℃ Lt; 0 > C to 400 < 0 > C.

FIGS. 3A and 3B are graphs showing changes in the thickness of the tin oxide (20) thin film according to the number of cycles and the thickness variation of the tin sulfide (30) thin film produced through sulfidation using H ₂ S gas using atomic layer deposition Graph.

3A and 3B, the abscissa represents the number of cycles of the tin oxide atomic layer deposition process, and the ordinate represents the thickness of the deposited tin monoxide and tin dioxide (FIG. 3A) and the H ₂ S gas on the tin oxide thin film (Fig. 3B) of the tin sulfide formed by sulfiding treatment.

When the tin monoxide and tin dioxide thin films are formed by the atomic layer deposition method, the thickness of the thin film is proportional to the number of cycles of the atomic layer deposition method as shown in FIG. 2A. Further, as shown in FIG. 3B, when the H ₂ S gas is sulfided to the tin monoxide film and the tin dioxide film, the film thickness of the tin oxide film is also increased as the thickness of the tin monoxide film and the tin dioxide film is increased , Which means that the thickness of the tin disulfide can be controlled by changing the thickness of the tin oxide thin film.

4 is a photograph of a tin disulfide surface formed in accordance with one embodiment of the present invention.

Specifically, Figure 4 is a SiO ₂ substrate (Fig. 4a and 4b) and Al ₂ O ₃ substrate (Figure 4c through 4e) in monoxide tin (SnO) thin film deposited on each of the sulfiding 300 ℃, 400 ℃ , And the surface of tin disulfide synthesized at 450 ° C. On the other hand, in the embodiment of the present invention, the thickness of the tin monoxide film was fixed at 15 nm.

As shown in FIG. 4A, when a thin film of tin monoxide deposited on a SiO ₂ substrate was subjected to sulfiding treatment at 300 ° C, it was observed that a thin and uniform thin film was formed without a rough surface. On the other hand, as shown in FIG. 4B, when the sulfidation treatment was carried out at 400 ° C, the surface of the thin film was roughened, and a non-uniform thin film was formed.

This is because the thin film is formed in the island shape rather than the continuous thin film because the thin film is formed in a direction to lower the total energy due to the surface energy of the tin sulfide relatively higher than the SiO ₂ substrate .

However, as shown in FIGS. 4C and 4D, when the tin monoxide deposited on the Al ₂ O ₃ substrate is subjected to sulphidation at 300 ° C. and 400 ° C., the surface of the thin film is not rough, The formation of the thin film was observed.

The reason for this is due to the surface energy of tin disulphide, which is relatively lower than the surface energy of the Al ₂ O ₃ substrate. However, as shown in FIG. 4E, when the sulfidation treatment was performed at 450 ° C, it was found that the thin film was rough and damaged. Therefore, the temperature of the sulfidation treatment is preferably set in the range of 300 ° C to 400 ° C.

FIG. 5 is a graph showing the relationship between Sn (FIG. 5A) and S (FIG. 5B) of the synthesized tin sulfide when the thin film of tin monoxide deposited on the SiO ₂ substrate according to the embodiment of the present invention is subjected to sulfiding treatment at 300 ° C. to 400 ° C., And O (Figure 5c).

More specifically, as shown in FIGS. 5A to 5C, when the tin monoxide deposited on the SiO ₂ substrate was subjected to sulfiding treatment at 300 ° C, 350 ° C, and 400 ° C, X-ray photoelectron spectroscopy ) Analysis shows that the spectrum of Sn (FIG. 5A) and S (FIG. 5B) is not seen as a single chemical bond and that various harmonic bonds are mixed. As a result, it can be seen that the tin monoxide formed on the SiO ₂ substrate was formed as a mixture of tin disulphide and tin disulphide, which is not a single film of tin disulphide after the sulfiding treatment.

Also, referring to FIG. 5A, it can be seen that when the sulfuration treatment is performed at a temperature of 400 ° C or higher, a mixed phase containing Sn components is produced. That is, it is difficult to grow a uniform and continuous tin sulphide thin film on a SiO ₂ substrate having a relatively low surface energy because Sn grows mainly in island form rather than forming a continuous thin film due to high surface energy. have.

In addition, referring to FIG. 5C, in the graph showing the bond of O when the sulfide treatment of the tin monoxide deposited on the SiO ₂ substrate is proceeded, the binding peak of Sn and O is observed, It can be seen that the tin sulfide growth was not completely performed.

In addition, referring to FIG. 5C, in the graph showing the bond of O when selenization of tin monoxide deposited on a SiO ₂ substrate at 400 ° C with H ₂ S gas is observed, bonding of Si and O to the substrate is observed . This means that X-ray photoelectron spectroscopy detects signals only in very thin regions near the surface, so that the observation of Si signals means that some of the substrate is exposed to the surface due to non-continuous film formation. This can be seen as a result of observing the above-described surface profile of FIG. 4B.

FIG. 6 is a graph showing the relationship between Sn (Fig. 6A) and S (tantalum disulfide) synthesized in the sulfide treatment of a tin monoxide thin film deposited on an Al ₂ O ₃ substrate at 300 ° C to 400 ° C according to another embodiment of the present invention. Fig. 6B) and O (Fig. 6C).

As shown in FIGS. 6A to 6C, when the tin monoxide deposited on the Al ₂ O ₃ substrate was subjected to sulphation treatment at 300 ° C, 350 ° C, and 400 ° C, respectively, the synthesized thin film had a chemical composition of tin disulphide Linkage. ≪ / RTI >

Specifically, it can be confirmed that the binding peaks of Sn (FIG. 6A) and S (FIG. 6B) have binding energy values of tin disulfide irrespective of the sulfurization treatment temperature.

In addition, when the tin monoxide deposited on the Al ₂ O ₃ substrate was subjected to the sulfidation treatment at 400 ° C, the bonding peak of Al and O was not observed in the graph showing the bond of O (FIG. 6c) As no binding peak was observed, it was confirmed that a single thin film of disulfide disulfide was produced by sulfiding treatment.

7 is a graph showing a phase change and crystallinity of a tin disulfide thin film formed according to an embodiment of the present invention. Specifically, FIG. 7A is an X-ray diffraction (XRD) graph showing the phase change crystallinity of the tin sulfide thin film synthesized by the sulfidation treatment temperatures of 300 ° C., 350 ° C. and 400 ° C., respectively, on the SiO ₂ substrate, 7b is an XRD graph showing the phase change crystallinity of a tin sulfide thin film synthesized by a sulphidation treatment temperature of 300 ° C, 350 ° C and 400 ° C, respectively, on a monooxide thin film deposited on an Al ₂ O ₃ substrate.

Referring to FIG. 7A, it is observed that the tin sulfide thin film formed on the SiO ₂ substrate is not formed in a single chemical form but has a mixed phase of two materials having a crystal structure of tin disulfide and tin sulfide. However, referring to FIG. 7B, it was confirmed that the tin sulfide thin film formed on the Al ₂ O ₃ substrate formed a single phase of tin disulfide regardless of the sulphiding temperature.

Therefore, when a tin monoxide thin film is subjected to sulfidation with H ₂ S gas to form a tin sulfide thin film, synthesis on a substrate having a surface energy larger than that of a tin sulfide thin film is more advantageous than synthesis on a substrate having a small surface energy.

In addition, when the sulfide treatment is performed on tin monoxide using H ₂ S gas, the sulphidation temperature does not affect the phase change. However, as the sulphidation temperature increases, the XRD peak becomes larger and the half- It was confirmed that the crystallinity of tin sulfide increased with increasing sulphide treatment temperature.

8 is a graph showing a phase change and crystallization degree of a tin disulfide thin film formed according to another embodiment of the present invention, a photograph of a surface shape, and chemical bonding. Specifically, FIG. 8A is a graph showing the phase change and the degree of crystallization of a tin oxide thin film (SnO ₂ ) deposited on an Al ₂ O ₃ substrate, respectively, at a temperature of 300 ° C., 350 ° C., and 400 ° C., respectively . 8B is a photograph of the surface of tin sulfide synthesized by subjecting a tin dioxide film deposited on an Al ₂ O ₃ substrate to a sulfidation treatment at 400 ° C, and FIG. 8C is a photograph of the surface of a tin sulfide film grown on an Al ₂ O ₃ substrate, ≪ / RTI >

Referring to FIG. 8A, a tin sulfide thin film synthesized by sulfiding a tin dioxide thin film can be confirmed as a fact that the peak of the XRD graph can not be observed when no crystallization occurs.

In addition, referring to FIG. 7B, it can be seen that damage is applied to the thin film during the sulfidation treatment, as a result of the existence of the tablets at many points in the middle portion, whereby the sulfidation treatment is performed at a temperature higher than 400 ° C It can be seen that it is difficult. It can also be seen that the crystallization of the material is difficult due to the high dependence of the heat treatment temperature on crystallization of the tin sulfide.

Referring to FIG. 8C, Sn and O element binding peaks exist at 300 ° C and 350 ° C, indicating that the sulphide treatment is not proceeding properly. It can be seen that the binding energy of Sn and O in the tin dioxide thin film is stronger than the binding energy of Sn and O elements in the tin monoxide, so that the sulphide treatment is required at a higher temperature. However, when the sulphide treatment is performed at 400 ° C, it can be seen that a thin film mixed with tin sulphide, tin disulfide and tin, which is not a single film, is produced.

Therefore, it is more advantageous to sinter a tin monoxide thin film having a weak binding force between Sn and O than a tin dioxide thin film having a strong binding force between Sn and O when forming a tin sulphide thin film by sulfiding a tin oxide thin film .

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof.

It is therefore to be understood that the above-described embodiments are illustrative in all aspects and are not intended to limit the invention to the embodiments, and the scope of the present invention is not limited by the above- And all changes or modifications that come within the meaning and range of equivalency of the claims and the equivalents shall be construed as being included within the scope of the present invention.

10 substrate
20 tin oxide
30 Tin Sulfide

Claims (11)

Forming a tin monoxide thin film on an aluminum oxide substrate;
Sulfiding the tin monoxide thin film; And
Wherein the sulfiding treatment comprises a step of forming a single phase tin disulfide thin film by heat treatment in a range of 300 ° C to 400 ° C with a hydrogen sulfide gas,
Wherein the surface energy of the aluminum oxide substrate is greater than the surface energy of the tin disulfide thin film to be formed.
The method according to claim 1,
Wherein the tin monoxide thin film is formed by atomic layer deposition.
delete 3. The method of claim 2,
In the atomic layer deposition method,
Supplying a tin material on the substrate;
Purging the tin material;
Supplying an oxygen source; And
And purging the oxygen source to form a single phase tin disulfide thin film.
5. The method of claim 4,
Wherein the atomic layer deposition method is performed at a temperature ranging from room temperature to 300 占 폚.
delete 6. The method of claim 5,
Wherein the thickness of the tin monoxide thin film is determined according to the number of cycles of the atomic layer deposition method and the thickness of the tin disulfide thin film is determined by the thickness of the tin monoxide thin film.
delete delete 5. The method of claim 4,
The tin material may be at least one selected from the group consisting of tin dichloride, tin tetrachloride, tetrakis-dimethylamino tin, tetrakis-diethylaminotin, tetrakis-ethylmethylaminotin, bis-bis-trimethylsilyl- A method for forming a single-phase tin disulfide thin film characterized by comprising at least one selected from ethyl tin, trimethyl-phenyl tin, dimethylamino-2-methyl-2-propoxy-tin (II acetyl acetone tin.
5. The method of claim 4,
Wherein the oxygen raw material comprises at least one selected from the group consisting of water, oxygen gas, air, a mixed gas of nitrogen and oxygen, methanol, ethanol, isopropanol, ozone, hydrogen peroxide and oxygen plasma .

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