Method and apparatus for etching 2d material

Abstract

The present invention relates to a method and an apparatus for etching a 2D material by irradiating the 2D material with electrons in plasma. The method for etching a 2D material comprises: a first step of generating plasma in a chamber while a 2D material is placed on a substrate; and a second step of applying a pulsed positive voltage to the substrate. The method and the apparatus for etching a 2D material of the present invention enable layer-by-layer etching of the 2D material without damage by using He plasma free of negative ions, thereby minimizing surface defects of the 2D material and enabling precise thickness control at the nanoscale.

Description

2D material etching method and apparatus

[0001] The present invention relates to a method and apparatus for etching 2D materials, and more specifically, to a method and apparatus for performing layer-by-layer etching of 2D materials by irradiating electrons in a plasma onto 2D materials.

[0002] Conventional 2D material etching techniques are primarily performed using traditional chemical or physical methods. However, these methods often result in non-uniform etching or cause problems such as the formation of defects on the surface of the material. In particular, when using plasmas containing negative ions, such as hydrogen plasma, there is a risk that hydrogen ions will penetrate into the material, causing bubble formation and physical damage. These issues create limitations in increasing etching precision depending on the characteristics of the 2D material.

[0003] The present invention proposes a method for uniformly etching the surface of 2D materials using anion-free He plasma and pulsed positive voltage. This solves problems such as surface defects and bubble formation that occur in conventional chemical etching methods or plasma methods containing anions, and enables more precise nanoscale layer-by-layer etching. In addition, by designing it to enable large-area etching, it overcomes the limitations of conventional electron beam methods that can only target small regions.

[0004] In one aspect, the present invention provides a 2D material etching method comprising a first step of generating plasma while a 2D material is placed on a substrate in a chamber, and a second step of applying a pulsed positive voltage to the substrate.

[0005] The plasma of the present invention is characterized as being a He plasma without negative ions. In the case of other plasmas, there is a problem in that negative ions are deposited on the substrate, and in particular, in the case of hydrogen plasma, if hydrogen ions penetrate into the material and accumulate, bubble formation and physical damage may occur.

[0006] When electrons within a plasma are irradiated onto a substrate, the extreme surface of the 2D material on the substrate is heated. During this process, heat is primarily transferred toward the top surface of the 2D material, weakening the bonds between atoms in the top layer and causing etching starting from the top layer through collisions with electrons within the plasma. This enables uniform surface etching and nanoscale layer-by-layer etching.

[0007] The 2D material of the present invention is characterized by being one or more selected from the group comprising graphene, hBN (hexagonal boron nitride), MoS2, and TMDC (Transition Metal Dichalcogenides). Etching of the 2D material is possible depending on electron acceleration and plasma conditions. In addition, the etching rate can be controlled by varying the applied voltage and time depending on the type.

[0008] The pulsed positive voltage applied to the substrate of the present invention is characterized by being 100 to 1500 V and 1 to 1000 KHz. The pulsed positive voltage applied to the substrate of the present invention is characterized by being 300 to 600 V and 1 to 100 KHz.

[0009] The duty ratio of the present invention is characterized as being 1 to 99%. The duty ratio of the present invention is characterized as being 20 to 80%. The duty ratio is the ratio of the time occupied by the on state in a periodic signal, expressed as a percentage of the time when current or voltage flows and the time when it does not flow. A higher duty ratio indicates that more electrons are used during the process time, and if it exceeds 80%, there is a problem that the plasma becomes unstable.

[0010] The 2D material etching method of the present invention is characterized by the fact that electrons having energy are irradiated onto a 2D material on a substrate.

[0011] The 2D material etching method of the present invention is characterized by the ability to perform layer-by-layer etching from the top surface of the 2D material.

[0012] The 2D material etching method of the present invention is characterized by the ability to perform large-area etching of the 2D material. In the case of using an electron beam in a 2D material etching method, targets in the millimeter range are possible, but the method of the present invention has the advantage of enabling large-area etching.

[0013] In another aspect, the present invention provides a 2D material etching apparatus comprising: a chamber; a plasma generating means capable of generating plasma in the upper part of the chamber; a substrate located at the bottom of the chamber and capable of placing a 2D material; and a power supply means configured to apply a pulsed positive voltage to one surface of the substrate.

[0014] The 2D material etching method of the present invention can etch 2D materials layer by layer without damage by using anion-free He plasma. In addition, by applying a pulsed positive voltage to the substrate, the interatomic bonds of the top layer are weakened, and collisions with electrons in the plasma are induced, thereby enabling more uniform etching. This minimizes surface defects in 2D materials such as graphene, BN, and MoS₂, and enables precise thickness control at the nanoscale. Furthermore, since large-area etching is possible, high efficiency can be expected in various industrial applications.

[0015] FIG. 1 is a schematic diagram of a 2D material etching method and apparatus according to one embodiment of the present invention.

[0016] FIG. 2 shows (a,b) OM images, AFM images and analysis results and (c) Raman analysis results of graphene according to one embodiment of the present invention.

[0017] FIG. 3 shows (a,b) OM images, AFM images and analysis results and (c) Raman analysis results of BN according to one embodiment of the present invention.

[0018] FIG. 4 shows (a,b) OM images, AFM images and analysis results and (c) Raman analysis results of MoS2 according to one embodiment of the present invention.

[0019] FIG. 5 is a schematic diagram illustrating the process of layer-by-layer etching of a 2D material according to one embodiment of the present invention.

[0020] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. Since the present invention is susceptible to various modifications and may take various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed forms, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the present invention. Similar reference numerals have been used for similar components in the description of each drawing. In the attached drawings, the dimensions of the structures are shown enlarged compared to the actual dimensions for the clarity of the present invention.

[0021] In addition, the description of one aspect of the present invention may be applied identically or similarly to the description of other aspects for identical or similar configurations or terms.

[0022] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0023] The embodiments of the present invention are described below. However, the embodiments described below are merely partial embodiments of the present invention, and the scope of the present invention is not limited to the following embodiments.

[0024] Example 1

[0025] Graphene is placed on a substrate inside the chamber. Plasma was generated using an ICP source under conditions of 200W RF power, He, and 3.5 mTorr. The plasma generated at this time is a He plasma without negative ions.

[0026] Subsequently, a pulsed positive voltage was applied to the substrate. The positive voltage range used at this time was 300 to 600 V, the pulse was performed at a frequency of 10 KHz, and the duty ratio (on / off ratio) was 20 to 80%. FIG. 1 is a schematic diagram of a 2D material etching method and apparatus according to an embodiment of the present invention.

[0027] Example 2

[0028] BN is placed on a substrate inside the chamber. Other conditions are the same as in Example 1.

[0029] Example 3

[0030] MoS2 is placed on a substrate inside the chamber. Other conditions are the same as in Example 1.

[0031] Etching verification and performance verification methods

[0032] To verify the layer-by-layer etching of the 2D material according to the above example, an optical microscope (OM), an atomic force microscope (AFM), and Raman spectroscopy were used.

[0033] The presence or absence of etching in 2D materials was confirmed using optical microscope (OM) images. Two-dimensional materials exhibit color variations depending on their thickness, and changes in thickness after etching can be primarily confirmed through optical microscope observation. While this allows for the detection of thickness changes, it does not reveal exactly how much thickness was etched. In other words, only the presence or absence of thickness changes can be easily verified. Additionally, it may be possible to detect the formation of surface defects, as well as the cleanliness and flatness of the surface resulting from the etching.

[0034] FIGS. 2a to 4a show optical microscope images according to embodiments of the present invention (graphene, BN, MoS2). By comparing the OM images before and after plasma electron-enhanced etching (PE) in FIGS. 2a to 4a, it can be confirmed that etching was performed in each embodiment.

[0035] Atomic force microscopy (AFM) was used to verify the etching thickness of 2D materials. By scanning the surface with a nanoscale tip, it is possible to accurately measure the thickness of the material. Using AFM, the change in thickness after etching of two-dimensional materials was precisely measured, and it is possible to precisely measure not only the thickness but also the formation of defects on the surface or changes in surface flatness information.

[0036] FIGS. 2a,b to 4a,b show atomic force microscope images according to embodiments of the present invention (graphene, BN, MoS2). Comparing the AFM images before and after plasma electron-enhanced etching (PE) in FIGS. 2a,b, it can be seen that the thickness of graphene, which was initially 112 nm, was reduced to 90 nm after the process, indicating that 22 nm was etched. Referring to FIGS. 3a,b, it can be seen that the thickness of BN was reduced from 136 nm to 107 nm, indicating 29 nm was etched, and referring to FIGS. 4a,b, it can be seen that the thickness of MoS2 was reduced from 162 nm to 149 nm, indicating 13 nm was etched.

[0037] It was confirmed through Raman analysis that there was no surface damage after etching the 2D material. Referring to Figures 2c to 4c, if there is damage after the process, a peak appears in the area marked "No D-Peak," confirming that there is no damage after the etching method of the present invention.

[0038] FIG. 5 is a schematic diagram illustrating the process of layer-by-layer etching of a 2D material according to one embodiment of the present invention.

[0039] Although the present invention has been described above with reference to preferred embodiments, those skilled in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and scope of the invention as set forth in the following claims.

Claims

1. A first step of generating plasma while a 2D material in the chamber is placed on a substrate, and A second step of applying a pulsed positive voltage to the above substrate, 2D material etching method.

2. In Paragraph 1, The above plasma is characterized as being a He plasma without negative ions, 2D material etching method.

3. In Paragraph 1, The above 2D material is characterized by being one or more selected from the group comprising graphene, hBN (hexagonal boron nitride), MoS2, and TMDC (Transition Metal Dichalcogenides). 2D material etching method.

4. In Paragraph 1, Characterized by the pulsed positive voltage applied to the substrate being 100 to 1500 V and 1 to 1000 KHz, 2D material etching method.

5. In Paragraph 4, Characterized by the pulsed positive voltage applied to the substrate being 300 to 600 V and 1 to 100 KHz, 2D material etching method.

6. In Paragraph 1, Characterized by a duty ratio of 1 to 99%, 2D material etching method.

7. In Paragraph 6, Characterized by a duty ratio of 20 to 80%, 2D material etching method.

8. In Paragraph 1, Characterized by irradiating a 2D material on a substrate with energy electrons. 2D material etching method.

9. In Paragraph 1, Characterized by the ability to perform layer-by-layer etching from the top surface of a 2D material, 2D material etching method.

10. In Paragraph 9, The above etching method is characterized by enabling large-area etching of the 2D material. 2D material etching method.

11. Chamber; A plasma generating means capable of generating plasma in the upper part of the above chamber; A substrate located at the bottom of the chamber and capable of placing a 2D material; and A power supply means configured to apply a pulsed positive voltage to one surface of the above substrate, 2D material etching device.

Images