KR102299665B1 - Method for selectively depositing dichalcogenide thin film using atomic layer deposition - Google Patents

Abstract

The present invention relates to a method for selectively depositing a chalcogenide thin film using an atomic layer deposition method, and more particularly, the method comprising the steps of: 1) providing a substrate having a conductive layer and an insulating layer including a metal; 2) supplying a molybdenum precursor and oxygen gas to the substrate to deposit a molybdenum oxide layer on the conductive layer; and 3) adding a chalcogen source and generating a low-temperature plasma to form a chalcogenide thin film It provides a selective deposition method of a chalcogenide thin film using an atomic layer deposition (ALD), comprising the step of, the present invention is to deposit a thin desired metal or metal oxide using the atomic layer deposition (ALD), chalcogen By treating the source, a desired number of layers of a two-dimensional chalcogenide material can be synthesized. The area selective deposition technology based on the atomic layer deposition method has developed enough to be applied to the current semiconductor mass production process, and has the advantage that it can be quickly applied for mass production of two-dimensional chalcogenide materials and use as devices in the future.

Description

Selective deposition method of chalcogenide thin film using atomic layer deposition method

The present invention deals with depositing a two-dimensional chalcogenide-based material that overcomes the fundamental problems of graphene using an atomic layer deposition method, and facilitating control of the number of layers. By utilizing the catalytic properties appearing on the surface of a thin film such as platinum or ruthenium metal to selectively deposit a metal or metal oxide in an area, and then flowing a reactant under heating conditions, it is possible to form a thin film of a two-dimensional material. . In addition, it is possible to secure various electrical, optical and electrochemical properties by implementing the control of the number of layers of a layered two-dimensional material by utilizing the nano-scale thickness controllability, which is an advantage of the atomic layer deposition method.

The selective deposition of oxides based on the existing atomic layer deposition method is a method of selectively adsorbing a polymer material such as self-assembled monolayer (SAM) to a substrate and then selectively depositing it using the property that chemical species do not stick to the SAM material. Most of these However, in the case of region-selective deposition using organic materials, it is possible only at a low process temperature due to the low thermal decomposition temperature of organic materials, and in order to prevent the adsorption of chemical species used in the atomic layer deposition method, it takes several hours for the SAM material to self-align without defects. Because it requires a longer process time, it is inappropriate to be applied to actual mass production technology.

Since the existing two-dimensional chalcogenide material group can be synthesized in a high process temperature range of 300 degrees or more, it is impossible to selectively synthesize it through the use of such an organic material. Therefore, in order to overcome this problem, an attempt has been made for selective synthesis through a low-temperature solution process.

In the prior art, after selectively patterning gold, a solution-based precursor was sprayed on a substrate to proceed with selective deposition utilizing the catalytic properties of gold. However, in the case of such a process, there are problems such as 1) that deposition is carried out on the periphery other than the desired area, 2) the inability to control the thickness uniformity of the synthesized material, and 3) the inability to control the number of layers of the two-dimensional material. As a result, it remains at the technological development level.

Recently, S. Bent group reported for the first time a technique for selectively synthesizing metal oxides on a substrate without the use of such organic materials. In this report, utilizing the catalytic properties of platinum materials, oxygen molecules are decomposed into highly reactive oxygen radicals to induce a substrate-selective reaction with the subsequently injected precursor, enabling deposition only in desired areas. This method has various advantages compared to other area selective deposition processes because it has the advantage of synthesizing the oxide at a low temperature on the patterned platinum structure.

Republic of Korea Patent Publication No. 10-2015-0098904

The present invention provides a method of selectively depositing a chalcogenide-based material on a conductive layer including a metal using a molybdenum precursor using an atomic layer deposition method.

In order to achieve the above object, the present invention comprises the steps of: 1) providing a substrate including a conductive layer and an insulating layer comprising a metal; 2) depositing a molybdenum oxide layer on the conductive layer by supplying a molybdenum precursor and oxygen gas to the substrate; and 3) adding a chalcogen source and generating a low-temperature plasma to form a chalcogenide thin film.

The deposition temperature in step 2) is 50 ~ 150 ℃, preferably 100 ℃. At the temperature condition, dissociative chemisorption occurs between the catalytic metal and oxygen gas constituting the conductive layer, and is catalytically activated on the conductive layer. Therefore, the highly reactive oxygen dissociated on the conductive layer between The species (O ^* ) reacts with the molybdenum precursor to deposit a molybdenum oxide layer on the conductive layer. The molybdenum oxide precursor is a material with relatively weak reactivity _{, and may react with O 2} plasma or ozone (O ₃ ), which is a strong oxidizing agent, to form a molybdenum oxide layer, but as in the present invention, the catalyst metal and oxygen on the conductive layer A molybdenum oxide layer can be deposited on the conductive layer without using _{O 2} plasma or ozone (O ₃ ) by a dissociative chemisorption reaction with a gas.

However, in the case of an insulating layer other than the conductive layer, since a dissociative chemisorption reaction with oxygen gas does not occur, the molybdenum oxide layer is not deposited on the insulating layer, and in this way, it is selectively oxidized only on the conductive layer. A molybdenum layer may be deposited.

Therefore, the step of depositing the molybdenum oxide layer includes forming active oxygen species on the conductive layer through a dissociative chemisorption reaction between oxygen gas and the conductive layer, and reacting the active oxygen species with the molybdenum precursor. It may consist of steps to

The molybdenum precursor is any one of molybdenum hexacarbonyl (Molybdenum Hexacarbonyl), molybdenum pentachloride (Molybdenum Pentachloride), the chalcogen source is S, Se, Te, H ₂ S, H ₂ Se, H ₂ Te, And it is characterized in that it is selected from the group consisting of combinations thereof.

The conductive layer is preferably a metal having a catalytic activity capable of causing a dissociative chemisorption reaction with oxygen gas, more preferably the metal is a noble metal, and most preferably the metal is platinum (Pt); It is characterized in that any one of palladium (Pd) or iridium (Ir), but is not limited thereto.

The insulating layer is characterized in that it is a silicon oxide layer.

In addition, the temperature of the low-temperature plasma in step 3) is characterized in that 350 ~ 450 ℃.

In the present invention, a desired metal or metal oxide is thinly deposited using atomic layer deposition (ALD), and a two-dimensional chalcogenide material with a desired number of layers can be synthesized by treating a chalcogen source. The area selective deposition technology based on the atomic layer deposition method has developed enough to be applied to the current semiconductor mass production process, and has the advantage that it can be quickly applied for mass production of two-dimensional chalcogenide materials and use as devices in the future.

1 is a diagram schematically illustrating a selective deposition method of a chalcogenide thin film of the present invention.
2 is a diagram schematically illustrating the selective deposition of a chalcogenide thin film on a platinum structure having a zero-dimensional nanodot structure.
3 is a graph showing the results of an ellipsometry experiment on a Pt on Si substrate.
4 is a Raman spectra measured after performing the deposition method of the present invention on a Pt on Si/Ru on Si substrate.

Hereinafter, a selective deposition method of a chalcogenide thin film using the atomic layer deposition (ALD) of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily carry out the present invention. .

Referring to Figure 1, the present invention comprises the steps of: 1) providing a substrate including a conductive layer and an insulating layer comprising a metal; 2) depositing a molybdenum oxide layer on the conductive layer by supplying a molybdenum precursor and oxygen gas to the substrate; and 3) adding a chalcogen source and generating a low-temperature plasma to form a chalcogenide thin film.

The chalcogenide specifically refers to TMDC (transition metal dichalcogenide). TMDC can be typically expressed as MX ₂ , M is a transition metal element of Groups 4 to 6, X is Group 6 S, Se, It is a chalcogen element of Te. These transition metal chalcogen compounds have a layered structure in which XMX is a covalent bond, and the interlayers have a weak vander waals bond.

Here, the transition metal is Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb , La, Hf, Ta, W, Re, Os, Ir, Pt, Ag, Hg, Tl, Pb, Bi, Po, and combinations thereof may be selected from the group consisting of. The combination may be in the form of an alloy of these metals, but is not limited thereto.

TMDC is well known as 2D material. Among TMDCs, MoS ₂ and WSe2 are representative materials of n-type and p-type, respectively. MoS ₂ is the most actively studied as a two-dimensional material with abundant reserves and a band gap unlike graphene. _{MoS 2} present in bulk form usually exhibits n-type properties, and when used as a semiconductor channel, the band gap changes according to the number of layers.

The chalcogenide thin film forming step is characterized in that made by atomic layer deposition (ALD).

The atomic layer deposition method is a method of sequentially spraying a gaseous precursor and a reactant to form it on a substrate, and has the advantage of being able to control the thickness of a desired thin film in nano units by repeating the number of processes. Through this, a desired metal or metal oxide is thinly deposited, and a two-dimensional chalcogenide material with a desired number of layers can be synthesized by treating the chalcogen source.

In the present invention, in the substrate having a conductive layer and an insulating layer containing a metal, the conductive layer is preferably a metal having a catalytic activity capable of causing a dissociative chemisorption reaction with oxygen gas, more preferably the metal Silver is a noble metal, and most preferably, the metal is platinum (Pt), palladium (Pd), iridium (Ir) and ruthenium (Ru), but is not limited thereto.

In addition, the insulating layer is a silicon oxide layer, but is not limited thereto.

Depositing the molybdenum oxide layer on the conductive layer may include depositing a molybdenum oxide layer (MoO ₃ ) on the conductive layer by supplying a molybdenum precursor and oxygen gas to the substrate.

The molybdenum precursor is any one of molybdenum hexacarbonyl (Molybdenum Hexacarbonyl), molybdenum pentachloride (Molybdenum Pentachloride), preferably molybdenum hexacarbonyl (Mo (CO) ₆ ).

The deposition temperature in step 2) is 50 ~ 150 ℃, preferably 100 ℃. When the deposition is performed at less than 50 ° C., dissociative chemisorption does not occur properly between the catalytic metal and oxygen gas constituting the conductive layer, so that the molybdenum oxide layer (MoO ₃ ) is not properly deposited, 150 When the temperature exceeds ℃, partial precursor decomposition occurs, and deposition of the conductive layer as well as the insulating layer is made, thereby making selective deposition impossible.

The next step is 3) adding a chalcogen source and generating a low-temperature plasma to form a chalcogenide thin film.

The chalcogen source includes one selected from the group consisting of S, Se, Te, H ₂ S, H ₂ Se, H ₂ Te, and combinations thereof, and preferably H ₂ S is used.

Chalcogen refers to a group 16 (VIA) element in the periodic table, such as sulfur (S), selenium (Se) and tellurium (Te). The chalcogen source is a material that is a source of supplying chalcogen, for example, selected from the group consisting of _{S, Se, Te, H 2} S, H ₂ Se, H _{2 Te, and combinations thereof.} It may include, but is not limited to. The chalcogen source may be supplied in gaseous form, but is not limited thereto.

When plasma is supplied after injecting the chalcogen source, a chalcogenide thin film can be synthesized, and it is generally understood that chalcogenide refers to sulfide, selenide, and telluride. can

It is preferable that the plasma supplied after adding the chalcogen source is a low-temperature plasma. The temperature of the low-temperature plasma is preferably 350 ~ 450 ℃. In this case, when plasma is supplied at a temperature of less than 350 ° C, the chalcogenide thin film is not properly synthesized, and when it exceeds 450 ° C, agglomeration of Pt, which is a lower film, etc. occurs, and the layer structure is collapsed.

In addition, the selective deposition method of the chalcogenide thin film can form various structures in the case of a metal catalyst structure required for region-selective deposition of a two-dimensional chalcogenide material, so that not only the existing semiconductor and display fields, but also high-efficiency catalysts and Can it be used in the energy field? As shown in FIG. 2 , the patterned structure includes one-dimensional nanowires including zero-dimensional nano dots, two-dimensional planar and three-dimensional complex structures, and based on the excellent step coverage, which is an advantage of the atomic layer deposition method, There is an advantage in that it is possible to selectively deposit in a desired area.

Experimental example

One. molybdenum oxide ( MoO ₃ ) deposition

The present inventors _{deposited a molybdenum oxide layer on Si/SiO 2} /Pt on Si/Ru on Si using a Mo(CO) ₆ precursor by an ALD method. The process temperature was 100° C., and oxygen was supplied as the reaction gas. The process cycle consisted of a time of O ₂ gas supply 10 seconds, purge gas supply 10 seconds, Mo(CO) ₆ precursor supply 20 seconds, and purge gas supply 10 seconds, and a total of 300 cycles were performed. As the purge gas, Ar, which is an inert gas, was used.

Then, the deposition of the molybdenum oxide layer was investigated by ellipsometry.

Referring to FIG. 3 , it can be seen that the molybdenum oxide layer is selectively formed on the Pt on Si substrate.

After measuring the sheet resistance ^{(Sheet Resistance, ㏀ / cm 2} ) of Pt on Si / Ru on Si substrates. The results are shown in Table 1 below.

Board Pt Ru MoO ₃ deposition before deposition 7.389 6.408 after deposition 5.238 6.207 difference 2.151 0.201

Both the Pt on Si/Ru on Si substrates showed a decrease in sheet resistance after the deposition process. However, in the Pt on Si substrate, a much greater reduction in sheet resistance was observed compared to that of Ru on Si, which means that the MoO ₃ deposition process according to the present invention is selectively performed on Pt.

2. Low-temperature Plasma Sulfurization

The present inventors supplied plasma at a temperature of 350 to 450° C. together with _{H 2} S gas, respectively, to the Pt on Si/Ru on Si substrates subjected to the molybdenum oxide (MoO _{3 ) deposition process.} After the low-temperature plasma sulfiding process, the Raman spectrum of the substrate was measured and shown as a graph in FIG. 4 .

Referring to FIG. 4 , a Raman peak was not observed in the Ru on Si substrate, but a Raman peak was observed in the Pt on Si substrate. This supports that the chalcogenide thin film was selectively formed only on Pt on Si.

Claims (9)

1) providing a substrate including a conductive layer and an insulating layer including any one of platinum (Pt), palladium (Pd), or iridium (Ir);
2) depositing a molybdenum oxide layer on the conductive layer by supplying a molybdenum precursor and oxygen gas to the substrate; and
3) A selective deposition method of a chalcogenide thin film using an atomic layer deposition (ALD), comprising the step of adding a chalcogen source and generating a low-temperature plasma to form a chalcogenide thin film.
According to claim 1,
The deposition temperature of step 2) is a selective deposition method of a chalcogenide thin film, characterized in that 50 ~ 150 ℃.
According to claim 1,
Step 2) is a step of forming active oxygen species on the conductive layer through a dissociative chemisorption reaction between oxygen gas and the conductive layer; and
Selective deposition method of a chalcogenide thin film, characterized in that consisting of the step of reacting the active oxygen species and the molybdenum precursor.
According to claim 1,
The molybdenum precursor is molybdenum hexacarbonyl (Molybdenum Hexacarbonyl), molybdenum pentachloride (Molybdenum Pentachloride) selective deposition method of a chalcogenide thin film, characterized in that any one.
According to claim 1,
The chalcogen source is S, Se, Te, H ₂ S, H ₂ Se, H ₂ Te, and a selective deposition method of a chalcogenide thin film, characterized in that selected from the group consisting of combinations thereof.
According to claim 1,
The conductive layer is a selective deposition method of a chalcogenide thin film, characterized in that the metal having a catalytic activity capable of causing a dissociative chemisorption reaction with oxygen gas.
delete According to claim 1,
The insulating layer is a selective deposition method of a chalcogenide thin film, characterized in that the silicon oxide layer.
According to claim 1,
The selective deposition method of the chalcogenide thin film, characterized in that the temperature of the low-temperature plasma in step 3) is 350 ~ 450 ℃.

Images