KR101818847B1 - Method of transition metal chalcogenides by using liquid mixture precursor - Google Patents

Abstract

Disclosed is a method for producing a transition metal chalcogenide compound, which is prepared by dissolving a transition metal precursor present in a solid state at room temperature in an organoalcogenide and an organic solvent to prepare a liquid phase and using the transition metal precursor as a liquid precursor. A transition metal chalcogen compound is deposited on the substrate. By applying the liquid precursor, the process of vaporizing the existing solid state chalcogen compound is not required, and the supply amount can be easily controlled, thereby lowering the process cost. It is also easy to control the deposition thickness.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for preparing a transition metal chalcogenide using a liquid precursor,

The present invention relates to a process for preparing a transition metal chalcogen compound, and more particularly to a process for preparing a transition metal chalcogen compound in a solid state at room temperature as a liquid precursor and using the same to form a transition metal chalcogen compound will be.

Recently, as the integration of electronic devices and the interest in flexible devices have been amplified, two dimensional materials having high charge mobility are attracting attention. These two - dimensional materials have the characteristics of conductor, semiconductor and non - conductor depending on the element constituting the material and its structure.

Transition metal dichalcogenides (TMDs) have electrical characteristics (band gap 1 ~ 2 eV) similar to silicon widely used in conventional electronic materials. In addition, transition metal chalcogen compounds possess high charge mobility, and chalcogen compounds such as transition metal chalcogen compounds have a common crystal structure, and at the same time have high electrical and magnetic and optical anisotropy, Material. Moreover, the transition metal chalcogenide compound has a flexible property and is advantageous for use as a flexible thin film transistor, a channel layer for implementing a flexible display, and the like.

However, the transition metal chalcogen compound is difficult to synthesize by controlling the thickness precisely, and there is a limit in that it can be synthesized on a large area on a substrate while maintaining a uniform thickness.

In order to utilize a semiconductor material as an electronic device, it is preferable to synthesize it in a large area. Therefore, a chemical vapor deposition (CVD) method is widely used as a method for manufacturing a semiconductor material for large area synthesis. In the case of the chemical vapor deposition method, heat and time are consumed to vaporize the transition metal chalcogenide compound in a solid state, and there is a problem that the injection amount must be controlled constantly.

The transition metal precursor is present in a solid state at room temperature and should be vaporized and supplied. In this process, large quantities of precursors are lost and it is difficult to control the amount of feed, and vaporization process equipment is required, which increases the cost of the process.

Therefore, a method for producing a transition metal chalcogenide compound that minimizes the loss of the precursor and can reduce the process cost will be required.

Korean Patent Laid-Open Publication No. 2014-0152288

A problem to be solved by the present invention is to provide a method for producing a transition metal chalcogen compound using a liquid precursor by preparing a solid transition metal carbonyl as a liquid phase.

According to an aspect of the present invention, there is provided a method for forming a chalcogenide compound, comprising: dissolving a transition metal material in a solid state at room temperature to form a transition metal chalcogenide compound; To a transition metal chalcogenide compound.

The transition metal material may include those characterized by being dissolved in the organocarbogenide.

Wherein the organotin compound is a compound selected from the group consisting of dimethyldisulphide and dimethyldicerenanide.

In the step of depositing the liquid precursor on the substrate, the carbon by-product generated in the production of the transition metal chalcogenide compound may include removal by adding water.

And the water is supplied in the form of water vapor through a carrier of argon gas. The present invention also provides a method for producing a transition metal chalcogenide compound.

According to the present invention, the transition metal chalcogenide compound, which is formed through the use of a transition metal and a mixture of organogel coenenide as a precursor, can be uniformly controlled. In addition, the transition metal chalcogen compound formed using the liquid precursor is easy to synthesize large area, and an additional step of phase-changing the solid phase is not necessary, so that the process cost can be lowered.

However, the effects of the present invention are not limited to those mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the following description.

1 is a perspective view illustrating a process of a transition metal chalcogenide compound having a liquid precursor according to an embodiment of the present invention.
FIG. 2 is a graph of mass spectrum measured to confirm that Mo (CO) ₆ is dissolved in CH ₃ SSCH ₃ according to one embodiment of the present invention.
FIG. 3 is a view showing an exposed area ratio of molybdenum disulfide and a substrate synthesized over time according to an embodiment of the present invention. FIG.
4 is a Raman spectrum obtained by measuring the flow rate of water in order to remove carbon byproducts produced during the manufacturing process according to an embodiment of the present invention.
FIG. 5 is a photoluminance spectrum measured after water is injected into amorphous carbon produced during the reaction according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Embodiments of the present invention are also provided to more fully describe the present invention to those skilled in the art. Accordingly, the shapes and sizes of the elements in the drawings may be exaggerated for clarity of description, and the elements denoted by the same reference numerals in the drawings are the same elements.

Example

According to an embodiment of the present invention, there is provided a method for producing a transition metal chalcogenide compound, comprising: a first step of dissolving a solid transition metal material to prepare a liquid transition metal chalcogen compound; and a step of applying a liquid phase transition metal chalcogenide compound as a liquid precursor, The method composed of the second step will be described in detail.

1 is a perspective view illustrating a process of a transition metal chalcogenide compound using a liquid precursor according to an embodiment of the present invention.

Referring to Figure 1, a process for producing a solid transition metal material from a liquid transition metal chalcogenide compound is disclosed.

(1) Method for producing liquid precursor

Examples of the solvent include organo-chalcogenide compounds, which can dissolve transition metals in a solid state, such as dimethyl disulfide, dimethyl diselenide, and organic solvents Or the like.

In one embodiment of the present invention, a transition metal chalcogen compound in a liquid phase is prepared by dissolving a transition metal as an organotin compound. The organotin derivative was synthesized in a weight ratio of 95: 5 by using the solid transition metal material as a solute in the glass bottle. The weight ratio includes those in which the transition metal material does not exceed 5% in the organogoldorganide. In order to completely dissolve the transition metal substance present in a solid state at room temperature in a solvent, an ultrasonic device and a stirrer may be additionally used. Fully dissolved liquid precursors exist as liquid precursors, such as transition metal ions, transition metal compounds, and chalcogen compounds.

(2) Synthesis of transition metal chalcogenide using liquid precursor

The substrate on which the transition metal chalcogenide is to be synthesized is placed in a beaker containing acetone, methanol, and distilled water, and washed sequentially in a water-type ultrasonic machine for 5 minutes each. The solvents remaining on the cleaned substrate are removed using nitrogen and dried. A sufficiently dried substrate is placed on a quartz or alumina plate. The substrate is placed at the center of the quartz tube above the heating furnace. High purity argon is poured at room temperature for more than 10 minutes to exhaust air and impurities through the exhaust pipe.

Argon is continuously supplied as a carrier gas, and the furnace is heated to a synthesis temperature of 550 to 900 DEG C over about 10 minutes. When the synthesis temperature is reached, the argon gas connected to the liquid precursor is injected to cause the liquid precursor molecules to be supplied through the argon gas. At this time, the flow rate of argon gas supplied to the liquid precursor is set to be less than 10 sccm. If the lower limit of the synthesis temperature is exceeded during the synthesis process, the precursor supplied may not be thermally decomposed and the chemical reaction may not occur. In addition, if the upper limit of the synthesis temperature is exceeded, the precursor atoms adsorbed on the substrate or the synthesized transition metal chalcogenide material may easily vaporize, and nothing may be synthesized on the substrate. In addition, when the flow rate of the argon gas supplied to the precursor is out of the range of the upper limit of the flow rate of the argon gas supplied to the precursor, synthesis may not occur in a single layer, a two layer structure and a three layer structure.

FIG. 2 is a graph of mass spectrum measured to confirm that Mo (CO) ₆ is dissolved in CH ₃ SSCH ₃ according to one embodiment of the present invention.

Referring to FIG. 2, a mass spectrum graph is presented to confirm that Mo (CO) ₆ is dissolved in CH ₃ SSCH ₃ . Molybdenum hexacarbonyl (Mo (CO) ₆ ) in solid state is dissolved in dimethyl disulfide (CH ₃ SSCH ₃ ) in liquid state. In order to completely dissolve the transition metal substance present in a solid state at room temperature in a solvent, an ultrasonic device and a stirrer may be additionally used. Fully dissolved liquid precursors exist as liquid precursors, such as transition metal ions, transition metal compounds, and chalcogen compounds.

In FIG. 2, molybdenum hexacarbonyl (Mo (CO)) and dimethyl disulfide (CH ₃ SSCH ₃ ) phases are present dissolved in the dissolved liquid precursor solution.

FIG. 3 is a view showing an exposed area ratio of molybdenum disulfide and a substrate synthesized over time according to an embodiment of the present invention. FIG.

Referring to FIG. 3, the exposed area ratio of molybdenum disulfide and substrate synthesized over time is disclosed. As the supply time of the liquid precursor increases, a uniform amount of continuous supply can be achieved, which is advantageous of the liquid precursor, so that the area of the transition metal chalcogenide thin film on the substrate is widened. When the formation of a single layer of 0.7 nm thickness is complete, the formation of the next layer begins. Precursors that reach the furnace exist in ionized and compound form, and are thermally decomposed by the heat applied in the furnace, resulting in an unstable state. For example, molybdenum hexacarbonyl (Mo (CO)) and dimethyl disulfide (CH ₃ SSCH ₃ ) can form an unstable state according to the following formulas (1) and (2) in a liquid precursor solution.

[Chemical Formula 1]

Mo (CO) x - > Mo + CO or (CO) x

(2)

CH ₃ SSCH ₃ -> CH ₃ S + CH ₃ S

In formula (1), molybdenum hexacarbonyl (Mo (CO) x) can be decomposed into Mo and CO or (CO) x. In Chemical Room 2, dimethyl disulfide (CH ₃ SSCH ₃ ) is decomposed into CH ₃ S and can form an unstable state. Unstable precursors react in the quartz tube to form a transition metal chalcogenide to go to a stable state. For example, the transition metal chalcogenide may be formed according to the following Chemical Formula 3 and Chemical Formula 4.

(3)

_{Mo + CH 3 S + CH 3} S -> MoS 2 + C 2 H 4 + H 2

[Chemical Formula 4]

_{Mo (CO) x + CH 3} S + CH 3 S -> MoS 2 + CH ₄ + H ₂ + (CO) x

In formula (3), molybdenum and sulfide molybdenum react to separate methane thiol and ethylene and hydrogen gas. In the formula (4), cobalt molybdenum and sulfide molybdenum react with each other to form a methine thiol and can be substituted with nitroglycol and methane gas, hydrogen gas and carbon monoxide. This leads to MoS ₂ growth on the substrate.

Therefore, the black and white scanning microscope image of the substrate changed according to the exposure time is compared with the color image for coverage calculation. In the image, yellow and white are silicon oxide (SiO ₂ ) substrates, and substrate changes as the exposure time elapses. Exposure times were 5 minutes, 7.5 minutes 10 minutes, 12.5 minutes and 15 minutes. In the case of the substrate exposed for 5 minutes, the coverage is as low as 37.1, and the portion where the MoS ₂ is not covered is the white SiO ₂ substrate. In the case of the substrate exposed for 15 minutes, the coverage is 99.47, and the SiO ₂ substrate is hardly visible, and the MoS ₂ film is formed as a whole.

Therefore, the optimum exposure time for depositing a transition metal chalcogenide compound as a liquid precursor into a substrate is 15 minutes.

(3) Removal of carbon by-products

Carbon by-products such as amorphous carbon and carbon monoxide are formed on the surface of the substrate or synthesized transition metal chalcogenide due to the high amount of carbon contained in the liquid precursor during the preparation of the transition metal chalcogenide compound. Therefore, if a certain amount of distilled water is supplied together with the liquid precursor in the manufacturing process of FIG. 1, formation of amorphous carbon can be prevented.

For example, when argon gas is injected into distilled water, argon gas is supplied together with water molecules, and amorphous carbon and carbon monoxide are oxidized in the quartz tube to remove carbon byproducts generated during the manufacturing process through the exhaust pipe. Thus, the carbon by-products can be removed according to the following formulas (1) and (2).

[Chemical Formula 5]

C + H ₂ O - > CO + H ₂

[Chemical Formula 6]

CO + H ₂ O - > CO ₂ + H ₂

In formula (5), carbon and water are combined to generate carbon monoxide and hydrogen gas, and can be discharged through the pipe. In the formula (6), carbon and water react with each other to be replaced with carbon dioxide and hydrogen gas and can be discharged through the pipe.

In addition, the hydrogen gas H ₂ generated in the above formula participates in the formation reaction of the transition metal chalcogenide compound according to the following formulas. This is according to the following formulas.

(7)

H ₂ + MoO ₃ -> MoO _{3 -x} + H ₂ O

[Chemical Formula 8]

MoO _{3 - x} + S - > MoS ₂ + SO _x

In formula (7), hydrogen gas and molybdenum may react to form molybdenum oxide and water. In formula (8), it is reacted with sulfur to replace molybdenum disulphide and sulfur gas.

4 is a Raman spectrum obtained by measuring the flow rate of water in order to remove carbon byproducts generated during the manufacturing process according to an embodiment of the present invention.

Referring to FIG. 4, Raman spectra were analyzed to remove carbon byproducts generated during the production process and to confirm that the carbon by-products were removed. Peak (Peak) of the Raman spectra of amorphous carbon is typically between 1,300cm ^-1 to 1,400cm ^-1 D- shaped band (Band Disorder-like) having a frequency (Wavenumber) with a 1,500cm ^-1 to 1,700cm ^-1 A peak of a graphite-like band having a wavenumber is generated.

Shaped amorphous carbon when the peak area of the D-shaped band is larger than the peak area of the G-shaped band and the peak area of the G-shaped band is large.

The method of adding water is applied to remove carbon byproducts. 0 sccm in which no water is added and 1 sccm to 10 sccm in water are added. First, in the case of 0 sccm at which no water is added, D-shaped bands and G-shaped bands appear predominantly in carbon compounds. In addition, when 1 sccm of water was added, the intensity of the D-shaped band and the G-shaped band appearing in the carbon compound was decreased, and when 10 sccm was added at 10 times the amount of water, the D-shaped band and the G- lost. Thus, adding 10 sccm of water can remove all of the carbon by-products generated in the manufacturing process.

FIG. 5 is a photoluminance spectrum measured after water is injected into amorphous carbon produced during the reaction according to an embodiment of the present invention.

Referring to FIG. 5, the result of measurement of the optical luminescence spectrum after adding water to remove carbon compounds generated in the manufacturing process is shown. The electrons in the charge carriers in the material are transferred to the conduction band by the energy of the laser, and the electrons transferred to the conduction band move to the low energy charge and emit energy as much as the band gap of the material. When the surface of the transition metal chalcogenide is carbon, the electrons do not migrate from the conduction band to the electric current but travel to the carbon, and the intensity of the light emitted from the transition metal chalcogenide compound is weakened. The X axis is the energy value of the emitted light and the Y axis is the intensity of the light.

In Fig. 5, the blue line indicates when 10 sccm of water is supplied, the red line indicates 1 sccm of water, and the black line indicates no water. When there is no supply of water, the intensity of light and the energy released are weak, but when the supply is increased to 1 sccm and 10 sccm of water, the Y axis rises. Therefore, it can be confirmed that when 10 sccm of water is supplied, the intensity of light is strengthened and carbon produced during the manufacturing process is removed.

That is, in the process in which a liquid transition metal chalcogen compound is formed into a predetermined thin film by using argon gas as a carrier, water vapor of distilled water is generated by argon gas, and water vapor of distilled water participates in the formation reaction of the transition metal chalcogen compound . As the amount of distilled water supplied increases, the by-products are effectively removed from the formed transition metal chalcogenide compound.

In accordance with the present invention, there is provided a process for preparing a liquid precursor by dissolving a solid transition metal material in an organocarbogenide and an organic solvent, and a process for depositing a transition metal chalcogen compound using the prepared liquid precursor, Can be improved. Further, by providing the transition metal chalcogen compound as a liquid precursor, it is possible to solve the problem of rising the process cost, which is caused to gasify the transition metal chalcogen compound in a solid state at room temperature. Transition metal chalcogen compounds, as liquid precursors, can be widely applied to applications such as display devices, highly integrated memories and non-memory devices, and MEMS as next generation electronic and optical device materials.

It should be noted that the embodiments of the present invention disclosed in the present specification and drawings are only illustrative of specific examples for the purpose of understanding and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

Claims (6)

Dissolving a transition metal material in a solid state at room temperature to form a transition metal chalcogenide compound to form a liquid precursor; And
The transition metal is dissolved in an organoalcogenide,
Depositing a transition metal chalcogenide compound on the substrate using the liquid precursor,
Wherein the step of depositing the liquid precursor on the substrate comprises adding water to remove the carbon byproducts generated during the formation of the transition metal chalcogenide compound. delete 2. The method of claim 1, wherein the organogel co-
≪ / RTI > wherein the transition metal chalcogenide compound is dimethyldisulfide or dimethyldiselenide. delete The method of claim 1, wherein the water is supplied in the form of water vapor through a carrier of argon gas. The method of claim 1, wherein, in depositing the liquid precursor onto a substrate,
Lt; RTI ID = 0.0 > 900 C < / RTI >

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