KR101809251B1 - Preparation method of transition metal chalcogenide layer - Google Patents

Abstract

The present invention relates to a method of producing a transmission metal chalcogenide layer capable of directly synthesizing a high-quality transition metal chalcogenide layer on a variety of substrates and continuously synthesizing a large-area transition metal chalcogenide layer in large quantities. To this end, the present invention includes a step of coating a substrate with a precursor solution and a step of heat-treating a precursor coating layer formed on the substrate at a temperature of 200 to 600C.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for producing a transition metal chalcogenide layer,

The present invention relates to a process for producing a transition metal chalcogenide layer capable of directly synthesizing a high-quality transition metal chalcogenide layer on various substrates and continuously synthesizing a large-scale transition metal chalcogenide layer .

Recently, molybdenum disulfide has attracted attention as a two-dimensional structure semiconductor in order to overcome the problem of excessive power consumption, which is a fundamental problem of a silicon-based electronic device along with miniaturization of electronic devices.

As a method of obtaining molybdenum disulfide having a two-dimensional structure, a chemical or physical stripping method has been introduced. However, the chemical or physical peeling method has an inherent problem that it is difficult to obtain a uniform thin film having a large area.

As another method of obtaining molybdenum disulfide having a two-dimensional structure, a method using chemical vapor deposition (CVD) has been introduced. Using chemical vapor deposition, a vaporized molybdenum metal radical is reacted with a sulfur-containing gas to form a molybdenum disulfide layer on the metal substrate. However, such a method is not suitable for forming a molybdenum disulfide layer directly on a flexible substrate which deforms in the temperature range like a plastic substrate because a thin film is usually deposited at 650 ° C to 1000 ° C, There is a problem in that molybdenum disulfide is molybdenum disulfide in which the ratio of molybdenum and sulfur is not 1: 2. Therefore, when a flexible substrate such as a plastic substrate is required to provide a flexible electronic device, a process of forming a molybdenum disulfide layer on a metal substrate and then transferring the molybdenum disulfide layer to a plastic substrate or the like must be essentially involved. However, physical defects are generated in the molybdenum disulfide layer during the transfer process, and electrical properties are deteriorated.

The present invention provides a method for producing a transition metal chalcogenide layer capable of directly synthesizing a high-quality transition metal chalcogenide layer on various substrates and continuously mass-synthesizing a large-area transition metal chalcogenide layer.

Hereinafter, a method for preparing a transition metal chalcogenide layer according to a specific embodiment of the present invention, a transition metal chalcogenide layer prepared from the transition metal chalcogenide layer, and uses thereof will be described.

According to an embodiment of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: coating a precursor solution on a substrate (hereinafter, simply referred to as a " solution process "); And a step of heat-treating the precursor coating film formed on the substrate at 200 to 600 ° C (hereinafter simply referred to as "pyrolysis step").

In the method of manufacturing the MoS ₂ layer using the conventional chemical vapor deposition method, a thin film was deposited at 650 ° C. to 1000 ° C., and a plastic substrate having a melting point or a deformation temperature lower than the deposition temperature could not be used. Accordingly, in order to apply a flexible electronic device, but the MoS ₂ layer deposited on the metal substrate, transferring the MoS ₂ layer on a plastic substrate, can not be avoided the problem that the generated defective MoS ₂ layer in this transfer process. In addition, in the method using the conventional chemical vapor deposition method, the metal substrate was corroded by the sulfur-containing gas, and a protective layer for protecting the metal substrate from the sulfur-containing gas had to be separately formed.

However, since the manufacturing method according to one embodiment of the present invention synthesizes a transition metal chalcogenide layer such as MoS ₂ layer at a relatively low temperature as compared with the conventional chemical vapor deposition method, a plastic substrate as well as a metal substrate can be used. A transition metal chalcogenide layer is synthesized by pyrolyzing the precursor coating layer through a process, so that a direct transition metal chalcogenide layer can be formed without forming a separate protective layer on various substrates.

In addition, a roll-to-roll process can be adopted to continuously mass-synthesize a large-area transition metal chalcogenide layer. Particularly, the production method of this embodiment is a process for producing a chalcogenide transition metal layer which is capable of easily synthesizing a transition metal chalcogenide layer under mild conditions, A transition metal chalcogenide layer can be provided.

The transition metal chalcogenide that can be synthesized according to the production method of one embodiment may include a transition metal of group 6 of the periodic table and a chalcogen of group 16. Specifically, the transition metal chalcogenide may be MoS ₂ , MoSe ₂ , MoTe ₂ , WS ₂ , WSe ₂ or WTe ₂ .

The high-quality transition metal chalcogenide layer obtained by the manufacturing method according to one embodiment can be used to provide various electronic devices, and it is expected to provide a miniaturized electronic device with very low power consumption.

Hereinafter, a manufacturing method according to one embodiment will be described in detail.

In the manufacturing method according to this embodiment, a roll-to-roll process can be adopted to continuously mass-synthesize a large-area transition metal chalcogenide layer.

Specifically, as shown in FIG. 1, a transition metal chalcogenide layer can be continuously synthesized by performing a solution process and a heat treatment process while transferring a substrate by a plurality of rollers. However, if necessary, the solution process can be performed without using the roll-to-roll method.

In the solution process, the precursor solution may be coated on the substrate to form a precursor coating layer.

As described above, the manufacturing method according to this embodiment can synthesize a high-quality transition metal chalcogenide layer directly on various substrates by synthesizing a transition metal chalcogenide layer at a relatively low temperature. Therefore, the type of the substrate to be used is not particularly limited. As a non-limiting example, the substrate may be a glass substrate, a metal substrate, a silicon substrate, a plastic substrate, or the like.

The precursor solution includes a precursor and a solvent capable of synthesizing a transition metal chalcogenide. (NH ₄ ) ₂ MoS ₄ , (NH ₄ ) ₂ MoSe ₄ , (NH ₄ ) ₂ MoTe ₄ , and (NH ₄ ) ₂ MoSe ₄ as precursors to produce high quality transition metal chalcogenide layers that meet the stoichiometric coefficients, (NH ₄ ) ₂ WS ₄ , (NH ₄ ) ₂ WSe ₄ , (NH ₄ ) ₂ WTe ₄ , compounds wherein at least one H of NH ₄ of the compound is substituted with an alkyl group having 1 to 4 carbon atoms, .

The compound in which at least one H of NH ₄ of the compound is substituted with an alkyl group having 1 to 4 carbon atoms may be a compound in which at least one H in NH ₄ is substituted with a methyl group, an ethyl group, a propyl group or a butyl group. Specifically, the compound wherein at least one H of the NH ₄ of the compound is substituted with an alkyl group having 1 to 4 carbon atoms is (N (CH ₃ ) ₄ ) ₂ MoS ₄ , (N (CH ₃ ) ₄ ) ₂ MoSe ₄ , _{(CH 3) 4) 2 MoTe} 4, (N (CH ₃ ) ₄ ) ₂ WS ₄ , (N (CH ₃ ) ₄ ) ₂ WSe ₄ or (N (CH ₃ ) ₄ ) ₂ WTe ₄ .

Examples of the solvent include alkylene glycols such as ethylene glycol and propylene glycol; Dialkylene glycols such as diethylene glycol, propylene glycol or hydroxyethoxypropanol; Polyalkylene glycols such as polyethylene glycol, polypropylene glycol, hydroxyethoxyethoxypropanol, and hydroxyethoxypropoxypropanol; Or a mixture thereof.

The present inventors have found that when N, N-dimethylformamide is used as a solvent, the synthesis yield and quality of the transition metal chalcogenide layer are lowered compared with the case where ethylene glycol is used.

The concentration of the precursor in the precursor solution can be controlled according to the coating conditions and the thickness of the transition metal chalcogenide layer to be synthesized. In one example, the concentration of the precursor in the precursor solution may be adjusted to 0.5 to 5 wt%, to form a transition metal chalcogenide layer having a large area and a uniform thickness.

In the solution process, the precursor solution may be coated on the substrate through various methods known to those skilled in the art.

For example, if the solution process is performed by a roll-to-roll process, a dip coating method, a slot die coating method, a bar coating method, a gravure coating method, an inkjet printing method, or the like may be employed as the coating method. In another example, if the solution process is performed without using a roll-to-roll process, a spin coating method or the like may be employed as the coating method. Among them, the use of the dip-coating method is advantageous in that a large-area transition metal chalcogenide layer having a uniform thickness can be continuously synthesized.

In the solution process, after the precursor solution is coated on the substrate, the solvent remaining in the coating film of the precursor solution formed on the substrate may be removed. Specifically, the coating film of the precursor solution formed on the substrate may be thermally treated at about 50 to 150 ° C. At this time, the heat treatment time can be adjusted to about 30 seconds to 5 minutes to a level at which the solvent remaining in the coating film of the precursor solution can be removed.

The precursor coating film obtained through the solution process is pyrolyzed in the pyrolysis process to produce a transition metal chalcogenide layer. The precursor coating layer formed on the substrate may be transferred to an apparatus in which a pyrolysis process is performed by a plurality of rollers as shown in FIG. 1, since the manufacturing method according to one embodiment of the present invention employs a roll-to-roll method.

In the pyrolysis step, a transition metal chalcogenide layer can be synthesized through first or more heat treatment. For example, when (NH ₄ ) ₂ MoS ₄ is used as the precursor, the precursor coating film may be thermally treated at 200 to 350 ° C., 250 to 300 ° C., or about 280 ° C. to form an MoS ₃ layer as shown in the following reaction formula 1.

[Reaction Scheme 1]

(NH ₄ ) ₂ MoS ₄ → MoS ₃ + 2NH ₃ + H ₂ S

Thereafter, the MoS ₃ layer is heat-treated at 360 to 600 ° C, 400 to 500 ° C, or about 450 ° C to form an MoS ₂ layer as shown in the following reaction formula (2).

MoS ₃ + H ₂ ? MoS ₂ + H ₂ S

The conditions for the pyrolysis process are not limited to the case of forming the MoS ₂ layer but can also be applied to the synthesis of other transition metal chalcogenide layers. The pyrolysis process is not limited to the above-described first and second pyrolysis processes but may be performed by other methods such as heat treatment of the precursor coating film at 200 to 600 ° C, 400 to 600 ° C or 500 to 600 ° C once .

The pyrolysis process may be conducted at a pressure of about 0.1 to 20 Torr, about 1 to 10 Torr, or about 1 to 5 Torr. The pyrolysis step may be carried out in an inert gas atmosphere such as nitrogen or argon. A high-quality transition metal chalcogenide layer can be formed while effectively preventing metal oxides from being produced under such conditions.

Through this pyrolysis process, a high quality transition metal chalcogenide layer that meets the stoichiometric coefficient can be synthesized. Referring to Experimental Examples to be described later, it is confirmed that a multilayered, uniform two-dimensional transition metal chalcogenide is synthesized according to the production method of one embodiment. Further, according to the production method of this embodiment, it is confirmed that a highly transparent transition metal chalcogenide layer is synthesized.

According to the method for producing a transition metal chalcogenide layer of the present invention, a high quality uniform transition metal chalcogenide layer can be easily formed directly on various substrates. Also, in the above-described production method, a large-area transition metal chalcogenide layer can be continuously mass-synthesized by employing a roll-to-roll method.

FIG. 1 is a diagram schematically showing a solution process and a pyrolysis process performed by a roll-to-roll process according to an embodiment.
2 (a) is the Mo 3d core level spectrum of the MoS ₂ layer synthesized in Example 1, and b is the S 2p core level spectrum.
3 is a Raman spectrum of the MoS ₂ layer synthesized in Example 1. Fig.
4 is a photograph of the substrate before the CVD reaction and the substrate after the CVD reaction, which are used in Comparative Examples 1 and 2, arranged side by side.
5 is a photograph of a specimen in which an MoS ₂ layer is formed on a glass substrate according to Example 3. Fig.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. However, this is provided as an example of the invention, and the scope of the invention is not limited thereto in any sense.

Example  1: Transition metal through solution process and pyrolysis process Chalcogenide  Synthesis of layers

(NH ₄ ) ₂ MoS ₄ was added to ethylene glycol in an amount of 1.25 wt%, and the mixture was stirred at room temperature for 60 minutes. Then, the precursor solution was dip-coated on the nickel substrate by placing the nickel substrate in a container provided with a roller as shown in Fig. 1, and transferring the nickel substrate through the roller. Subsequently, the coating film of the precursor solution formed on the nickel substrate was subjected to heat treatment at 100 ° C for 1 minute to remove the solvent remaining in the coating film to obtain a (NH ₄ ) ₂ MoS ₄ thin film.

Then, the (NH ₄ ) ₂ MoS ₄ thin film formed on the substrate under the pressure of 1.8 Torr was thermally treated at 280 ° C. for 30 minutes while injecting nitrogen. Subsequently, the heat-treated thin film was heat-treated at 450 캜 for 30 minutes under a pressure of 1.8 Torr and a flow rate of 100 sccm of H ₂ and N ₂ gas to synthesize an MoS ₂ layer.

Example  2: Transition metal through solution process and pyrolysis process Chalcogenide  Synthesis of layers

An MoS ₂ layer was synthesized in the same manner as in Example 1 except that a polyimide substrate was used in place of the nickel substrate in Example 1.

Example  3: Transition metal through solution process and pyrolysis process Chalcogenide  Synthesis of layers

An MoS ₂ layer was synthesized in the same manner as in Example 1, except that a glass substrate was used instead of the nickel substrate in Example 1.

Comparative Example  One: Chemical vapor deposition  Transition metal Chalcogenide  Synthesis of layers

In order to synthesize the MoS ₂ layer on the nickel substrate through chemical vapor deposition while transferring the nickel substrate by the roll-to-roll method, the following experiment was conducted.

Specifically, MoO ₃ and H ₂ S gases were injected into the chamber through which the nickel substrate could pass by the roll-to-roll method as a transition metal precursor, and the temperature of the chamber was set at 800 ° C. so that MoO ₃ could be vaporized. Then, the nickel substrate was transferred by a roll-to-roll method so as to pass through the chamber. It was expected that a thin film would be formed on the nickel substrate by the reaction of vaporized MoO ₃ and H ₂ S while passing through the chamber, but the nickel substrate was corroded by H ₂ S gas to not synthesize the desired MoS ₂ layer Respectively.

Comparative Example  2: Chemical vapor deposition  Transition metal Chalcogenide  Synthesis of layers

Experiments were carried out in the same manner as in Comparative Example 1 except that a copper substrate was used in place of the nickel substrate in Comparative Example 1. However, the copper substrate was also corroded by the H ₂ S gas and the desired MoS ₂ layer could not be synthesized.

Experimental Example : Transition metal Chalcogenide  Evaluation of the floor

≪ Identification of molybdenum disulfide layer >

(1) X-ray photoelectron spectroscopy (XPS)

FIG. 2 (a) is the Mo 3d core level spectrum of the MoS ₂ layer synthesized in Example 1, and FIG. 2 (b) is the S 2p core level spectrum. Even without a molybdenum oxide substantially present in the MoS ₂ layer over a spectrum of 2, the mole ratio of Mo and S between about 1: is viewed MoS ₂ was the synthesis to meet the stoichiometric coefficient a 2.

The MoS ₂ layer synthesized in Examples 2 and 3 was confirmed to have the same results through XPS.

(2) Raman spectrum

The MoS ₂ layer synthesized in Example 1 was cut to a length of 50 cm to prepare a specimen. 3 is a Raman spectrum for the specimen. Referring to Figure 3, viewed as being a vibration mode of the E _2g mode A _1g of MoS _2, and MoS ₂ is observed is viewed under synthesis, A and E _1g multilayer viewed as being a difference of about 24 cm ^-1 mode _2g Of MoS ₂ were synthesized. Analysis of MoS ₂ layer with a total length of 50 cm at an interval of 1 cm confirmed that MoS ₂ layer of uniform thickness was synthesized in the entire region of the MoS ₂ layer.

The same results were confirmed for the MoS ₂ layers synthesized in Examples 2 and 3 through Raman spectroscopy.

≪ Comparison of Examples and Comparative Examples >

Fig. 4 shows photographs in which the substrate before the CVD reaction and the substrate after the CVD reaction used in Comparative Examples 1 and 2 are arranged side by side.

In the Examples 1 to 3 using the method of manufacturing the same according to one embodiment of the invention can be easily formed directly MoS ₂ layer on a variety of substrates, the composite MoS ₂ layer is about 1 molar ratio of the Mo and S: 2 It is possible to satisfy a stoichiometric coefficient and to exhibit a uniform thickness. However, in Comparative Examples 1 and 2 using the chemical vapor deposition method, only the metal substrate can be used in a limited manner due to the high temperature deposition temperature, and the MoS ₂ layer can not be formed due to the corrosion of the metal substrate due to the sulfur-containing gas.

In addition, the specimen in which the MoS ₂ layer was formed on the glass substrate according to Example 3 had a light transmittance of 90.8% ± 0.6% at a wavelength of 550 nm. FIG. 5 shows photographs of specimens having a MoS ₂ layer formed on a glass substrate according to Example 3. FIG. From this, it is confirmed that the MoS ₂ layer produced by the manufacturing method of one embodiment of the present invention shows high transparency, unlike the case where the MoS ₂ layer produced by the existing chemical vapor deposition method is known to be opaque.

Thus, it has been confirmed that a high quality uniform transition metal chalcogenide layer can be easily formed directly on various substrates according to the manufacturing method of the embodiment of the present invention.

Claims (8)

Roll-to-roll method,
Coating a precursor solution on the substrate; And
Treating the precursor coating film formed on the substrate at a temperature of 200 to 600 DEG C,
The precursor solution,
(NH ₄ ) ₂ MoS ₄ , (NH ₄ ) ₂ MoSe ₄ , (NH ₄ ) ₂ MoTe ₄ , At least one compound selected from the group consisting of (NH ₄ ) ₂ WS ₄ , (NH ₄ ) ₂ WSe ₄ and (NH ₄ ) ₂ WTe ₄ ; One or more compounds selected from the group of compounds wherein at least one H of NH ₄ of the compound selected in these groups is substituted with an alkyl group having 1 to 4 carbon atoms; Or a combination thereof as a precursor,
Alkylene glycol, dialkylene glycol, polyalkylene glycol or a mixture thereof as a solvent.
The method of claim 1, wherein the substrate is a glass substrate, a metal substrate, a silicon substrate, or a plastic substrate.
delete delete The method of claim 1, wherein in the coating step, a precursor solution is coated on a substrate, and a coating film of the precursor solution formed on the substrate is heat-treated at 50 to 150 ° C.
The method of claim 1, wherein the precursor coating layer is heat-treated at a temperature of 200 to 350 占 폚 and then heat-treated at a temperature of 360 to 600 占 폚.
2. The method of claim 1, wherein the heat treatment is performed at a pressure of 0.1 to 20 Torr.
The method of claim 1, wherein the transition metal chalcogenide layer is MoS ₂ , MoSe ₂ , MoTe ₂ , WS ₂ , WSe ₂ or WTe ₂ .

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