Apparatus for Manufacturing Thin Film Transistors Using PECVD and Method for Manufacturing Thin Film Transistors Using the Same

Abstract

One embodiment of the present invention provides a two-dimensional semiconductor material layer with minimized damage using a micrometer mesh and a soft plasma PECVD method, and a large-area thin-film transistor manufactured therefrom. According to an embodiment of the present invention, defects in the two-dimensional semiconductor layer caused by plasma ions can be minimized, and thereby, a high-quality semiconductor thin film can be formed that exhibits transistor characteristics beyond the diode characteristics of the two-dimensional semiconductor material.

Description

Technology Field

[0001] The present invention relates to a Plasma Enhanced Chemical Vapor Deposition (PECVD) apparatus and a method for manufacturing a thin-film transistor using a PECVD apparatus. More specifically, the invention relates to a method for manufacturing a large-area thin-film transistor by synthesizing a two-dimensional semiconductor material layer with high quality to obtain transistor characteristics using a PECVD process, and to a PECVD apparatus for manufacturing a thin-film transistor for this purpose.

[0002] The present invention was derived through the following research project.

[0003] [Assignment No.] GRRC Sungkyunkwan 2023-B03

[0004] [Project Management Agency Name] Gyeonggi Regional Cooperation Research Center (GRRC)

[0005] [Research Project Name] Gyeonggi Regional Cooperation Research Center (GRRC) Project

[0006] [Research Project Title] Development of Laser-based Heat Treatment and Etching Process Technology

[0007] [Name of Project Performing Organization] Sungkyunkwan University

[0008] [Project Period] July 1, 2024 – June 30, 2025 Background Technology

[0009] The PECVD process has the advantage of enabling low-temperature processing because synthesis is performed using plasma. However, in the conventional PECVD process, the plasma moves along the electric field and acquires a large amount of energy, which damages the seed layer material during the deposition of plasma ions and degrades the characteristics of the seed layer.

[0010] Conventional technology, Registered Patent No. 10-2364105, provides a method for manufacturing a thin-film transistor by depositing an oxide channel layer using a sputtering process, treating the surface of the oxide channel layer with plasma, and additionally depositing a source electrode and a drain electrode.

[0011] In addition, the literature "Low-Temperature Synthesis of Wafer-Scale MoS2-WS2Vertical Heterostructures by Single-Step Penetrative Plasma Sulfurization" reported in Acs Nano, 15, 1, 707-718 (2021) provides a method for manufacturing diodes with uniform performance by synthesizing two-dimensional thin film materials, MoS2 and WS2, on a large area using PECVD at a low temperature of 300 °C on a 4-inch wafer size.

[0012] However, the methods disclosed in the aforementioned prior art are difficult to use for two-dimensional semiconductor material layers for manufacturing thin-film transistors because the two-dimensional semiconductor material layer exhibits only diode characteristics and it is difficult to exhibit transistor characteristics. This is because the plasma travels along the electric field and acquires a large amount of energy, causing damage to the seed layer when it is deposited on the seed layer.

[0013] Meanwhile, the literature "Unlocking of Schottky Barrier Near the Junction of MoS2 Heterostructure Under Electrochemical Potential," recently reported in Energy & Environmental Materials, 8, 1, e12800 (2025), presented a method for large-area synthesis of two-dimensional thin film materials, MoS2, using Capacitively Coupled Plasma (CCP) PECVD at low temperatures of 150–300°C.

[0014] However, conventional CCP PECVD technology uses direct plasma-substrate interaction in which high-energy atoms and ions diffuse deep into the seed layer while simultaneously sputtering the seed layer, making it difficult to precisely control the growth of atomically thin 2D layers and prone to synthesizing films with poor surface quality. Prior art literature

[0015] Unlocking of Schottky Barrier Near the Junction of MoS2 Heterostructure Under Electrochemical Potential (Energy & Environmental Materials, 8, 1, e12800 (2025)) The problem to be solved

[0016] The present invention aims to provide a PECVD apparatus and method capable of forming a two-dimensional semiconductor material layer that can be used in thin-film transistors at a low temperature with high quality and a large area, as a method to solve the problems of the aforementioned prior art.

[0017] The technical problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art to which the present invention belongs from the description below. means of solving the problem

[0018] To achieve the above technical problem, one embodiment of the present invention provides a method for manufacturing a thin film transistor.

[0019] A method for manufacturing a thin-film transistor according to one embodiment of the present invention comprises: a step of depositing a seed layer on a semiconductor substrate; a step of placing the semiconductor substrate on which the seed layer is deposited at the bottom of a PECVD device; a step of placing a micrometer mesh between the semiconductor substrate and a plasma generating device; a step of creating a vacuum inside the PECVD device and injecting a first gas to activate the surface of the seed layer; a step of generating plasma ions from the second gas by operating a plasma generating unit while injecting a second gas for reaction into the PECVD device; and a step of forming a semiconductor material layer on the semiconductor substrate by reacting the plasma ions with the seed layer.

[0020] In an embodiment of the present invention, the seed layer may be deposited by sputtering.

[0021] In an embodiment of the present invention, in the step of forming the semiconductor material layer on the semiconductor substrate, an electric field may not be directly applied to the semiconductor substrate.

[0022] In an embodiment of the present invention, the first gas may include Ar.

[0023] In an embodiment of the present invention, the seed layer may include Mo.

[0024] In an embodiment of the present invention, the second gas may include H2S.

[0025] In an embodiment of the present invention, the step of etching the semiconductor material layer using a photolithography process and a Reactive Ion Etching (RIE) process may be further included.

[0026] In an embodiment of the present invention, the micrometer mesh may be spaced 1 to 20 mm apart from the seed layer.

[0027] In an embodiment of the present invention, in the step of forming the semiconductor material layer on the semiconductor substrate, the reaction temperature may be 100 ℃ to 400 ℃.

[0028] At this time, it may be preferable that the reaction temperature be 330 ℃ to 360 ℃.

[0029] In an embodiment of the present invention, in the step of forming the semiconductor material layer on the semiconductor substrate, the reaction pressure may be 400 mTorr to 700 mTorr.

[0030] At this time, it may be preferable that the reaction pressure be 550 mTorr to 650 mTorr.

[0031] Another embodiment of the present invention for solving the problems of the aforementioned prior art provides a PECVD device (100) comprising: a reaction chamber (110); a plasma generating unit (120) located at the top of the reaction chamber; a gas inlet (130) connected to the plasma generating unit and injecting gas into the reaction chamber; a semiconductor substrate (140) having a seed layer deposited thereon located at the bottom of the chamber spaced apart from the plasma generating unit; a heater (150) located below the semiconductor substrate; and a micrometer mesh (160) located between the semiconductor substrate and the plasma generating unit. Effects of the invention

[0032] The thin film transistor manufacturing method according to an embodiment of the present invention has excellent compatibility as it can grow high-quality two-dimensional semiconductor thin films by simply modifying the existing PECVD process, and is characterized by the ability to grow two-dimensional semiconductor thin films at low temperature on a wafer scale that is compatible with the backend process.

[0033] In addition, by using only a two-step process involving simple sputtering followed by a PECVD process that does not require complex precursors, specific substrates, or long deposition times, it is possible to grow 2D semiconductor materials, which are in the spotlight in the semiconductor industry, over a large area and at low temperatures, thereby preventing the problem of thin film quality degradation that occurs during the conventional layer transition process.

[0034] The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description of the invention or the claims. Brief explanation of the drawing

[0035] FIG. 1 is a flowchart schematically illustrating a method for manufacturing a thin-film transistor according to an embodiment of the present invention. FIG. 2 is a drawing showing a PECVD device according to one embodiment of the present invention. FIG. 3 is an image of a two-dimensional semiconductor thin film manufactured by a thin film transistor manufacturing method according to one embodiment of the present invention. Figure 4 is a Raman spectrum illustrating the optimization conditions of a two-dimensional semiconductor material layer in a thin-film transistor manufacturing method according to one embodiment of the present invention. Figure 5a is a schematic diagram showing the behavior of Ar+H2S plasma when there is no micrometer mesh. Figure 5b is a schematic diagram showing the behavior of Ar+H2S plasma when a micrometer mesh is present. Figure 6a is a diagram showing a TFT transfer curve representing the change in drain current according to the change in gate voltage. Figure 6b is a diagram showing an output curve representing the output characteristics according to the change in drain voltage. Figure 7a is the Raman spectrum of a MoS2 two-dimensional semiconductor material layer according to the change in distance between the micrometer mesh and the semiconductor substrate. Figure 7b is the PL spectrum of a MoS2 two-dimensional semiconductor material layer according to the change in distance between the micrometer mesh and the semiconductor substrate. FIG. 8a shows different seed layers (Mo, MoO x This is a diagram showing the Raman spectroscopic spectrum of a thin film formed after performing the same plasma treatment process based on MoS2. FIG. 8b shows different seed layers (Mo, MoO x This is a diagram showing the PL (Photoluminescence) spectra comparing the optical properties of thin films formed after performing the same plasma treatment process based on MoS2. Specific details for implementing the invention

[0036] The present invention will be described below with reference to the attached drawings. However, the present invention may be implemented in various different forms and is therefore not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification have been given similar reference numerals.

[0037] Throughout the specification, when it is stated that a part is "connected (connected, in contact, combined)" with another part, this includes not only cases where they are "directly connected," but also cases where they are "indirectly connected" with other members interposed between them. Furthermore, when it is stated that a part "includes" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but rather allows for the inclusion of additional components.

[0038] The terms used herein are merely for describing specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “comprising” or “having” are intended to indicate the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0039] Embodiments of the present invention will be described in detail below with reference to the attached drawings.

[0041] FIG. 1 is a flowchart schematically illustrating a method for manufacturing a thin-film transistor according to an embodiment of the present invention.

[0042] Referring to FIG. 1 above, the method for manufacturing a thin film transistor according to the present invention comprises the steps of: depositing a seed layer on a semiconductor substrate (S100); placing the semiconductor substrate on which the seed layer is deposited at the bottom of a PECVD device (S200); placing a micrometer mesh between the semiconductor substrate and a plasma generating device (S300); creating a vacuum inside the PECVD device and injecting a first gas to activate the surface of the seed layer (S400); operating a plasma generating unit while injecting a second gas for reaction into the PECVD device to generate plasma ions from the second gas (S500); and reacting the plasma ions with the seed layer to form a semiconductor material layer on the semiconductor substrate (S600).

[0043] First, a seed layer is deposited on a semiconductor substrate (S100).

[0044] Before depositing a seed layer (S100) on a semiconductor substrate, the method may further include a cleaning step of cleaning the semiconductor substrate using a solvent such as acetone, IPA (isopropyl alcohol), DI water (deionized water) and ultrasound.

[0045] The above substrate may be a general substrate such as glass, silicon, SiO2, or oxide.

[0046] The seed layer selectively reacts with a reactive gas while exposed to plasma ions in a subsequent step to induce thin film formation. The seed layer may be molybdenum (Mo), tungsten (W), or other transition metal or oxide-based materials, and preferably Mo, or a compound of Mo and O (MoO). x It may include at least one of ), MoS2MoSe2 and MoTe2.

[0047] At this time, it is most preferable that the seed layer be molybdenum (Mo) or tungsten (W). In the experimental example to be described later, in the case of a semiconductor material layer grown with a Mo seed layer, the Raman peak is observed most distinctly compared to a semiconductor material layer with other seed layers applied, and the band gap is clear in the PL spectrum, confirming that a highly crystalline two-dimensional semiconductor can be effectively grown from this.

[0048] The above deposition may utilize sputtering, atomic layer deposition (ALD), chemical vapor deposition (CVD), or vacuum deposition methods, and preferably, sputtering deposition may be used.

[0049] Next, a semiconductor substrate with a seed layer deposited thereon is placed at the bottom of a PECVD device (S200), and a micrometer mesh is placed (S300).

[0050] In the above S200 step, a semiconductor substrate with a seed layer formed thereon is placed on a support or substrate mounting area located at the bottom of the PECVD device. The semiconductor substrate is fixed at a position spaced apart from the plasma generation area and is positioned in a structure to minimize physical damage caused by plasma in subsequent processes.

[0051] The above-described PECVD device is a commonly used PECVD device, having a structure in which a plasma generating unit is placed at the top of the reaction chamber and a semiconductor substrate is placed at the bottom. The specific configuration of the PECVD device will be described later.

[0052] In the above S300 step, a micrometer mesh is placed on the upper surface of the semiconductor substrate at a position spaced apart by a certain distance.

[0053] A micrometer mesh is a mesh structure having an opening structure in the micrometer (μm) range, which corresponds to a major technical feature of the present invention. The micrometer mesh is located between a plasma generation unit and a semiconductor substrate, so that plasma ions generated in the plasma generation unit are filtered by the micrometer mesh and then come into contact with a seed layer.

[0054] In particular, in one embodiment of the present invention, the plasma ions do not move strongly but move smoothly (Soft Plasma PECVD) by not applying an electric field to the substrate side. The ions that move in this way induce a Marangoni Effect within the plasma by a micrometer mesh, thereby reducing electron energy and preventing high-energy plasma ions from being directly implanted into the seed layer (Ion Implantation).

[0055] Accordingly, the possibility of structural defect formation in the seed layer is significantly reduced, and surface damage is effectively suppressed. Consequently, due to the structural differences induced therefrom, the two-dimensional thin-film semiconductor material manufactured according to the manufacturing method of the present invention can exhibit transistor characteristics as an active device, going beyond simple diode characteristics.

[0056] Since the material, aperture size, and position of the above micrometer mesh act as important variables in controlling the energy distribution and density of plasma ions, they can be optimized according to process conditions.

[0057] As an example, the micrometer mesh may be positioned at a distance of 1 mm to 20 mm from the seed layer, preferably at a distance of 3 mm to 12 mm, and most preferably at a distance of 6 mm to 9 mm. In particular, in the embodiments of the present invention described below, it was observed that a two-dimensional semiconductor material layer with the best crystallinity is formed at a micrometer mesh spaced 9 mm apart, and functions as a semiconductor having a band gap. However, the present invention is not limited to the examples described above. If the distance between the mesh and the substrate is too close, ions are hardly affected by the mesh and directly affect the substrate, increasing the likelihood of causing defects in the seed layer and surface damage. Conversely, if the distance is too far, ions passing through the mesh lose a significant amount of energy while moving, making it difficult to retain sufficient energy to synthesize a two-dimensional thin-film semiconductor material, and thus making it difficult to synthesize a high-quality semiconductor material.

[0058] The material of the above micrometer mesh is not particularly limited and may be, for example, plastic, metal, etc., and it would be appropriate to have a material that maintains durability under plasma process temperatures and does not react with H2S.

[0059] As an example, the aperture of the micrometer mesh may be in the range of 1 µm to 1000 µm, and preferably 100 µm. However, it is not limited thereto. If the aperture size of the mesh is too small (1 µm or less), the energy of electrons is excessively reduced, resulting in insufficient energy to synthesize a two-dimensional thin-film semiconductor material, and thus a high-quality semiconductor material is not synthesized. Conversely, if the aperture size of the mesh is too large (1000 µm or more), ions often pass through without being affected by the mesh, increasing the likelihood of causing defects and surface damage in the seed layer.

[0060] Next, the seed layer is activated by injecting the first gas (S400).

[0061] In the above S400 step, the inside of the PECVD device is made into a vacuum, and after injecting the first gas, power is applied to the plasma generation unit to clean and activate the surface of the seed layer.

[0062] Specifically, a vacuum is formed within the chamber of the PECVD device before injecting the first gas. This is intended to remove gaseous impurities (air, residual gas) and initialize the environment. This vacuum is not an absolute vacuum, but refers to a low-pressure state suitable for the purpose of operation, for example, 1×10⁻⁶ -5 Pa ~ 1×10 -2 Pressure may be formed in the Pa range, but is not limited thereto. In one embodiment of the present invention to be described later, 5×10 -6 It formed a pressure of mbar.

[0063] The first gas may be composed of an inert or reactive gas, and may include, for example, argon (Ar), hydrogen (H2), nitrogen (N2), or a mixture thereof, and more preferably, the first gas may be Ar gas.

[0064] At this time, while injecting the first gas, it is preferable to raise the substrate temperature to a range of 100°C or higher and 400°C or lower, preferably 330°C to 360°C, using a heater or the like inside the PECVD chamber.

[0065] In addition, it is preferable to set the pressure inside the chamber where the first gas is injected to 400 mTorr or more and 700 mTorr or less, preferably 600 mTorr.

[0066] The first gas injected in the above S400 step is decomposed or ionized under a low-power plasma environment and acts on the surface of the seed layer, removing foreign substances or residual oxides on the surface and increasing the adsorption sites of reactive gas species.

[0067] In addition, this process can increase the surface energy while maintaining the crystal structure of the seed layer, thereby improving the coupling reactivity with the second gas and plasma reaction species introduced in subsequent steps.

[0068] The above low-power plasma environment may be formed by applying low power, for example, RF power of 100 W to 500 W, to a plasma generation unit. In one embodiment of the present invention to be described later, the surface of the seed layer was activated with Ar plasma for 20 minutes by applying RF power of 300 W.

[0069] Next, a second gas is injected (S500), and power is applied to the plasma generation unit to grow the seed layer into a semiconductor material layer (S600).

[0070] The second gas may be composed of a precursor or reactive gas capable of reacting with a seed layer to form a semiconductor material, and may include, for example, at least one of H2S, H2Se, and H2Te.

[0071] In addition, an inert gas such as the first gas may be additionally injected at the same time as the second gas.

[0072] The second gas injected in step S500 above is decomposed or ionized under a low-power plasma environment to generate plasma ions. At this time, the RF power applied to the plasma generation unit may be in the range of 300 W to 600 W.

[0073] The generated plasma ions move toward the substrate by applying an electric field to the plasma generation unit, and at this time, a separate electric field may not be applied to the lower part where the semiconductor substrate is located. That is, the substrate is maintained in a floating state, and a Soft Plasma PECVD structure in which ion acceleration caused by the electric field is suppressed can be maintained.

[0074] The second gas is a gas capable of forming a semiconductor material by selectively reacting with a seed layer. That is, plasma ions generated by applying power to a plasma generation unit can react with the seed layer to form a semiconductor material layer on the semiconductor substrate. For example, the semiconductor material layer may include at least one of WS2, WSe2, WTe2, MoS2, MoSe2, and MoTe2.

[0075] It is desirable to maintain the temperature and pressure conditions set when the first gas was injected earlier for the reaction conditions in which the semiconductor material layer is formed.

[0076] Specifically, it is preferable to raise the substrate temperature during the reaction in which the semiconductor material layer is formed to a range of 100°C or higher and 400°C or lower, preferably to a range of 330°C to 360°C. In particular, according to the experimental examples of the present invention described below, the most optimized condition for forming the semiconductor material layer was found to be around 350°C.

[0077] In addition, it is preferable to maintain the pressure inside the chamber where the first gas is injected in a range of 400 mTorr or more and 700 mTorr or less, preferably 550 to 650 mTorr, and most preferably set to 600 mTorr. Likewise, in the experimental examples of the present invention described below, the most optimized condition for forming a semiconductor material layer was found to be around 600 mTorr.

[0078] A method for manufacturing a thin film transistor according to one embodiment of the present invention may include an additional etching step (S700) and an electrode formation step (S800).

[0079] Specifically, the semiconductor material layer formed on the semiconductor substrate can be etched by a photolithography process and a Reactive Ion Etching (RIE) process (S700), and a source electrode, a drain electrode, a dielectric layer, and a gate electrode can be deposited on the etched semiconductor material layer by a lift-off process and an E-beam vacuum deposition method (S800) to manufacture a thin-film transistor. However, the etching process and the electrode deposition process are not limited to the examples described above.

[0080] FIG. 2 is a drawing showing a PECVD device according to one embodiment of the present invention.

[0081] As shown in FIG. 2 above, a PECVD apparatus (100) according to one embodiment of the present invention comprises: a reaction chamber (110); a plasma generating unit (120) located at the top of the reaction chamber (110); a gas inlet (130) connected to the plasma generating unit (120) and injecting gas into the reaction chamber (110); a semiconductor substrate (140) having a seed layer deposited thereon located at the bottom of the chamber spaced apart from the plasma generating unit; a heater (150) located below the semiconductor substrate; and a micrometer mesh (160) located between the semiconductor substrate (140) and the plasma generating unit (120).

[0082] The reaction chamber (110) may be in the form of a dome including a plasma generating unit (120), a semiconductor substrate (140), and a heater (150) inside, but is not limited thereto.

[0083] As shown in FIG. 1 above, a plasma generating unit (120) is positioned in the upper region of the reaction chamber (110), and a semiconductor substrate (140) and a heater (150) are positioned in the lower region.

[0084] The semiconductor substrate (140) is located at the bottom of the PECVD chamber (110), and a seed layer for synthesizing a semiconductor material layer is deposited thereon. Since the semiconductor substrate and the seed layer are identical to those described above, redundant descriptions are omitted.

[0085] The plasma generation unit (120) is located at the top of the reaction chamber (110) and is connected to a gas inlet (130). The gas inlet (130) may include, for example, a first gas inlet (130a) and a second gas inlet (130b). The plasma generation unit (120) can generate plasma and ionize reactive gases into plasma through the plasma of inert gas injected by the gas inlet.

[0086] The first gas inlet (140a) and the second gas inlet (140b) can each inject a first gas to remove and activate oxygen on the surface of the seed layer and a second gas for synthesizing a semiconductor material layer inside the reaction chamber (110).

[0087] The PECVD device (100) may further include a device that changes the inside of the PECVD chamber (110) to a high vacuum state before injecting the gas.

[0088] The micrometer mesh (160) is spaced apart from the semiconductor substrate (140) and is located between the semiconductor substrate (140) and the plasma generating unit (120). At this time, the micrometer mesh (160) can be spaced 1 mm to 20 mm apart from the seed layer, as described above.

[0089] A support member capable of supporting the micrometer mesh may be formed on one side of the micrometer mesh (160).

[0090] The heater (150) is located below the semiconductor substrate (140) and can control the substrate temperature to a synthesis temperature suitable for synthesizing plasma ionized gases and a seed layer.

[0092] The present invention will be explained in more detail below through manufacturing examples, comparative examples, and experimental examples. However, the present invention is not limited to the following manufacturing examples and experimental examples.

[0094] <Example> Synthesis of 2D Semiconductor Thin Film Material Using Soft Plasma PECVD

[0095] (Fabrication of 2D semiconductor thin films)

[0096] First, the substrate (SiO2, glass, PI, etc.) was cleaned for 10 minutes each using an ultrasonic cleaning bath in the order of acetone, IPA (isopropyl alcohol), and DI water.

[0097] Next, a seed layer (Mo, MoO) is formed through RF sputtering. x MoS2) was deposited over a large area on a substrate, and after sputtering the substrate was placed in a soft plasma PECVD chamber, a micrometer mesh plate was placed 5 mm above the sample.

[0098] Using a turbomolecular pump, the system 5×10 -6 After establishing a vacuum of mbar, Ar gas was introduced into the chamber. The chamber pressure was set to 600 mTorr using a throttle valve, and the substrate temperature was gradually increased to 350℃ using a substrate heater.

[0099] The surface of the seed layer was cleaned with Ar plasma using 300W RF plasma for 20 minutes, and annealed and activated.

[0100] Finally, the sample was sulfidated for 60 minutes using a plasma composed of H2S and Ar gas while maintaining the RF power at 300W and the pressure at 600mT, and then the sample was naturally cooled at room temperature in the presence of Ar gas.

[0101] FIG. 3 is an image of a two-dimensional semiconductor thin film manufactured by a thin film transistor manufacturing method according to one embodiment of the present invention, and it can be seen that the two-dimensional thin film is uniformly and well deposited on a substrate.

[0103] (Thin-film transistor manufacturing)

[0104] In addition, the fabricated 2D semiconductor material was etched into a desired shape through photolithography and RIE processes, and source and drain electrodes were deposited through a lift-off process and an E-beam evaporator. A dielectric layer (Al2O3, HfO2, etc.) was deposited through an ALD process, and a gate electrode was deposited through a lift-off process and an E-beam evaporator.

[0106] <Experimental Example 1> Optimization Conditions for PECVD Growth Pressure and Temperature

[0107] Figure 4 is a Raman spectrum illustrating the optimization conditions of a two-dimensional semiconductor material layer in a thin-film transistor manufacturing method according to one embodiment of the present invention.

[0108] In Figure 4 above, the results of analyzing the formation of a MoS2 thin film under plasma treatment conditions for 60 minutes using Raman spectroscopy are shown.

[0109] As shown on the left side of Figure 4 above, when pressure conditions were varied from 400 mTorr to 700 mTorr, the peak was most distinctly observed at 600 mTorr, suggesting that MoS2 crystals were best formed under that condition.

[0110] In addition, as shown on the right side of Figure 4 above, as a result of varying the substrate temperature from 100 ℃ to 400 ℃, it can be confirmed that the Raman peak intensity is maximized at 350 ℃, and accordingly, it is determined that securing MoS2 crystallinity and growth efficiency are best at that temperature condition.

[0112] <Experimental Example 2> Adoption of Micrometer Mesh and Soft Plasma PECVD and Prepared MoS 2 Electrical properties of semiconductor material layers

[0113] Figure 5a is a schematic diagram showing the behavior of Ar+H2S plasma when there is no micrometer mesh.

[0114] Figure 5b is a schematic diagram showing the behavior of Ar+H2S plasma when a micrometer mesh is present.

[0115] As shown in FIGS. 5a and 5b above, in the case of a conventional PECVD that does not adopt a micrometer mesh, ions move due to an electric field applied to the substrate side, whereas in the present invention, an electric field is not applied to the substrate side, so the precursor material that has become ions moves smoothly without moving strongly, and the ions that have moved in this way are filtered by a micrometer mesh and then meet the seed layer.

[0116] The micrometer mesh can induce the Marangoni effect to reduce electron energy and prevent ion penetration into the seed layer, thereby lowering the likelihood of defects in the seed layer and preventing surface damage.

[0117] Due to these differences, the two-dimensional semiconductor material produced in the present invention exhibits transistor characteristics beyond those of a diode.

[0119] FIG. 6 is a graph showing the electrical characteristics of a MoS2-based thin-film transistor formed through a thin-film transistor manufacturing method according to one embodiment of the present invention.

[0120] Figure 6a is a diagram showing a TFT transfer curve showing the change in drain current according to the change in gate voltage, and Figure 6b is a diagram showing an output curve showing the output characteristics according to the change in drain voltage.

[0121] According to FIG. 6a above, the MoS2 transistor formed by the process of the present invention exhibits typical n-type characteristics in which the drain current increases exponentially with increasing gate voltage, and the on / off current ratio is approximately 10 5 It can be confirmed that excellent switching performance and low-off current characteristics have been secured through measurements above.

[0122] In addition, as shown in the output curve in Fig. 6b, the linear current response with respect to changes in drain voltage indicates that carrier movement within the channel is smooth, and it can be confirmed that MoS2 formed by a Soft PECVD process including a micrometer mesh operates as a normal field-effect transistor (FET) structure.

[0123] These results suggest that MoS₂ formed by the Soft PECVD method is a low-damage thin film with excellent crystallinity and suppressed surface defects, and that the two-dimensional semiconductor material produced by the process of the present invention exhibits transistor characteristics beyond diodes, proving that it is effective for manufacturing thin-film transistors.

[0125] <Experimental Example 3> Experiment on Deformation of Distance Between Micrometer Mesh and Substrate

[0126] Figure 7 is a diagram showing the change in MoS2 thin film characteristics according to the change in distance between the micrometer mesh and the semiconductor substrate.

[0127] Specifically, FIG. 7a shows the Raman spectrum of a MoS2 two-dimensional semiconductor material layer according to changes in the distance between a micrometer mesh and a semiconductor substrate, and FIG. 7b shows the PL spectrum.

[0128] According to the Raman analysis results shown in Fig. 7a, the peak of MoS2 was observed most strongly when the distance between the mesh and the substrate was 9 mm, indicating that layered MoS2 with the best crystallinity was formed. On the other hand, at a distance of 12 mm, the peak was observed weakly, confirming a decrease in crystallinity.

[0129] In the PL analysis results of Fig. 7b, a strong emission peak (A) appears at approximately 1.9 eV under the 9 mm gap condition, which proves that the formed MoS2 functions as a semiconductor with a band gap.

[0130] In this way, it can be seen that by optimizing the distance conditions between the micromesh and the substrate, the movement of plasma reactive species can be controlled, and the formation of high-quality MoS2 can be induced.

[0132] <Experimental Example 4> MoS₂ based on various seed layers 2 Comparison of formation characteristics

[0133] FIG. 8a shows different seed layers (Mo, MoO x This shows the Raman spectroscopic spectrum of a thin film formed after performing the same plasma treatment process based on MoS2.

[0134] In the case of the Mo seed layer, a very distinct peak is observed in the formed MoS2, which indicates that highly crystalline layered MoS2 has been effectively grown.

[0135] Meanwhile, in the case of the MoS2 seed layer, two Raman peaks are present, but the signal intensity is relatively low, suggesting that only additional growth occurred on the existing MoS2.

[0136] Also MoO x In the seed layer, Raman peaks are observed to be very weak or widely dispersed, indicating that amorphous or incomplete MoS₂ with low crystallinity has been formed.

[0138] FIG. 8b shows different seed layers (Mo, MoO x This shows the PL (Photoluminescence) spectrum comparing the optical properties of thin films formed after performing the same plasma treatment process based on MoS2.

[0139] Mo seed layer-based MoS2 exhibits a strong PL peak around 1.85 eV (A), which indicates characteristics as a two-dimensional semiconductor with a clear band gap.

[0140] In the case of the MoS2 seed layer, a peak is observed at a similar position, but the luminescence intensity is relatively weak, indicating that the crystallinity enhancement effect is limited.

[0141] Meanwhile, MoO xSeed layer-based thin films rarely show photoluminescence signals, which indicates that electron-hole recombination is suppressed due to an unclear band gap or amorphous structure.

[0143] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single unit may be implemented in a distributed manner, and components described as distributed may likewise be implemented in a combined form.

[0144] The scope of the present invention is defined by the claims set forth below, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention. Explanation of the symbols

[0145] 100: PECVD device 110: Reaction chamber 120: Plasma generation unit 130: Gas inlet 130a: First gas inlet 130b: Second gas inlet 140: Semiconductor substrate 150: Heater 160: Micrometer mesh

Claims

Claim 1 A method for manufacturing a thin-film transistor, comprising: a step of depositing a seed layer on a semiconductor substrate; a step of placing the semiconductor substrate on which the seed layer is deposited at the bottom of a PECVD device; a step of placing a micrometer mesh between the semiconductor substrate and a plasma generating device; a step of creating a vacuum inside the PECVD device and injecting a first gas to activate the surface of the seed layer; a step of generating plasma ions from the second gas by operating a plasma generating unit while injecting a second gas for reaction into the PECVD device; and a step of forming a semiconductor material layer on the semiconductor substrate by reacting the plasma ions with the seed layer, wherein in the step of forming the semiconductor material layer on the semiconductor substrate, an electric field is not directly applied to the semiconductor substrate, wherein the seed layer comprises Mo or W, wherein the second gas comprises H2S, and wherein the micrometer mesh is spaced 6 mm to 9 mm apart from the seed layer. Claim 2 A method for manufacturing a thin-film transistor according to claim 1, characterized in that the seed layer is deposited by sputtering. Claim 3 delete Claim 4 A method for manufacturing a thin film transistor according to claim 1, characterized in that the first gas comprises Ar. Claim 5 delete Claim 6 delete Claim 7 A method for manufacturing a thin film transistor according to claim 1, further comprising the steps of etching the semiconductor material layer and depositing an electrode. Claim 8 delete Claim 9 A method for manufacturing a thin-film transistor according to claim 1, characterized in that, in the step of forming the semiconductor material layer on the semiconductor substrate, the reaction temperature is 100 ℃ to 400 ℃. Claim 10 A method for manufacturing a thin-film transistor according to claim 9, characterized in that the reaction temperature is 330 ℃ to 360 ℃. Claim 11 A method for manufacturing a thin-film transistor according to claim 1, characterized in that, in the step of forming the semiconductor material layer on the semiconductor substrate, the reaction pressure is 400 mTorr to 700 mTorr. Claim 12 A method for manufacturing a thin-film transistor according to claim 11, characterized in that the reaction pressure is 550 mTorr to 650 mTorr. Claim 13 A method for manufacturing a thin film transistor according to claim 1, wherein the step of activating the surface of the seed layer; and the step of generating plasma ions from the second gas are each characterized by applying RF power of 100 W to 500 W to the plasma generating part. Claim 14 delete

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