A method for patterning two-dimensional semi-metallic thin film and its application

Abstract

The present invention relates to a method for patterning a two-dimensional semi-metallic thin film and its application, which comprises the following steps: heating a photoresist layer after spin coating it on a substrate; exposing and developing to form a patterned photoresist layer; depositing a Pt layer of a predetermined thickness on the patterned photoresist layer; placing the substrate with the Pt layer deposited in a first anhydrous ethanol to remove the photoresist layer, and then placing the substrate in a second anhydrous ethanol to ultrasonically treat it for a predetermined time to form a patterned Pt layer, wherein the energy density of the ultrasonic wave is 42-54 W / cm 3 A chemical vapor deposition process is used to form a patterned two-dimensional semi-metal dichalcogenide PtR2 layer on a substrate. The two-dimensional semi-metal PtR2 pattern obtained by this method has a high success rate, and its pattern surface is flat, the thickness is uniform, and the edges are very neat and clear without residue.

Description

Technical Field

[0001] The present invention relates to the field of two-dimensional material preparation, and in particular to a method for patterning a two-dimensional semi-metallic film and its application. Background Art

[0002] Due to the thin thickness of the semi-metallic two-dimensional material layer, the preparation of a large area of ​​specific pattern is usually a probabilistic process, which often has problems such as high failure rate and imperfection rate. The prepared semi-metallic two-dimensional material thin layer of specific shape is of poor quality, the Raman peak is not obvious, the pattern edge is not neat, and the final pattern is far from the pattern obtained by photolithography.

[0003] In the existing preparation process, metal Pt material is commonly used in patterning process. However, due to the sufficient van der Waals force between Pt atoms and SiO2 layer, once the Pt thin layer is attached to the SiO2 layer, it is very difficult to separate again. After multiple high-intensity ultrasound, it is not only impossible to remove but also seriously damages the pattern. On the other hand, acetone is used to remove the photoresist in the traditional process. However, the inventor of the present application found that in the process of using acetone to remove the photoresist in the traditional process, the use of acetone can cause the Pt thin layer to crack and peel off over a large area, and the degree of its destruction of the Pt thin layer increases with the increase of the number of times acetone is used. The above problems have led to the high failure rate of preparing PtSe2 thin layer patterns by the traditional process. According to the statistics of the number of pieces made by the inventor in half a year: the failure rate is 100% when removing the photoresist of large-area Pt patterns according to the traditional method.

[0004] In addition, the inventors of the present application have also found that in the preparation of smaller areas (for example, areas less than 100 μm 2 ) When a Pt thin layer is formed, the phenomenon of cracking and peeling of the Pt thin layer caused by acetone in the traditional process is not obvious, but the imperfect rate of the pattern (unclear edge lines and extra debris) produced by the traditional process reaches 70%-80%. Summary of the invention

[0005] In view of the technical problems existing in the prior art, the primary purpose of the present invention is to provide a method for patterning a two-dimensional semi-metallic film and its application. 2 When preparing a two-dimensional semi-metal film (the above), anhydrous ethanol is used to remove the photoresist layer, thereby avoiding the damage to the Pt thin layer caused by using acetone to remove the photoresist, and ensuring the integrity of the Pt thin layer pattern; then the substrate is placed in anhydrous ethanol, and the ultrasound at a specific energy density and time is set to remove the residue at the edge of the Pt thin layer pattern, thereby ensuring the clarity of the pattern edge lines and improving the perfection rate of the pattern. The prepared two-dimensional semi-metal disulfide PtR2 layer pattern has a high success rate, and its pattern surface is flat, the thickness is uniform, and the edges are very neat and clear without any residue.

[0006] In order to achieve the above object, the present invention adopts at least the following technical solutions:

[0007] In one aspect, the present invention provides a method for patterning a two-dimensional semi-metallic thin film, comprising the following steps:

[0008] Spin coating a photoresist layer on a substrate and then heating the photoresist layer;

[0009] exposing and developing to form a patterned photoresist layer;

[0010] Depositing a Pt thin layer of predetermined thickness on the patterned photoresist layer;

[0011] The substrate with the Pt thin layer deposited thereon is placed in a first anhydrous ethanol to remove the photoresist layer, and then the substrate is placed in a second anhydrous ethanol and ultrasonicated for a predetermined time to form a patterned Pt thin layer, wherein the energy density of the ultrasonication is 42-54 W / cm 3 ;

[0012] A patterned two-dimensional semi-metal dichalcogenide PtR2 layer is formed on the substrate using a chemical vapor deposition process.

[0013] Furthermore, the disulfide PtR2 is selected from PtSe2, PtTe2 or PtS2.

[0014] Furthermore, the predetermined time of ultrasound is selected to be 60 to 90 seconds.

[0015] Furthermore, the predetermined time of ultrasound is selected to be 60 seconds.

[0016] Furthermore, the thickness of the Pt thin layer is selected to be less than 10 nm, and the area thereof is selected to be 100 μm 2 above.

[0017] Furthermore, the thickness of the Pt thin layer is preferably less than 7 nm.

[0018] Furthermore, the step of placing the substrate with the Pt thin layer deposited thereon in a first anhydrous ethanol to remove the photoresist layer includes immersing the substrate with the Pt thin layer deposited thereon in the first anhydrous ethanol until the color of the substrate changes back to the original color of the substrate, and then allowing the first anhydrous ethanol to flow until the Pt thin layer on the photoresist layer is peeled off.

[0019] Furthermore, the two-dimensional semi-metal PtR2 layer is preferably PtSe2; and the substrate is a SiO2 / Si substrate.

[0020] Another aspect of the present invention provides a patterned two-dimensional semi-metal film, and the patterned two-dimensional semi-metal film is obtained by the above method.

[0021] Furthermore, the two-dimensional semi-metallic film is used in the field of optoelectronic devices.

[0022] Compared with the prior art, the present invention has at least the following advantages:

[0023] The method for patterning a two-dimensional semi-metallic thin film provided by the present invention has a high success rate in obtaining a two-dimensional semi-metallic dichalcogenide PtR2 layer pattern, and the pattern surface is flat, the thickness is uniform, and the edges are very neat and clear without residue. Compared with the traditional process, the method of the present invention is more convenient in preparing large-area (e.g., an area of ​​100 μm 2 When preparing two-dimensional semi-metallic films (areas less than 100 μm), the success rate and pattern perfection rate are above 70%, which is much higher than the traditional process; when preparing small areas (areas less than 100 μm 2 ) of a two-dimensional semi-metal film, the pattern perfection rate of the method of the present invention is about 95% or more, which is much higher than the traditional process. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 These are microscope images of different patterns of a 5 nm thick PtSe2 material prepared in one embodiment of the present invention.

[0025] Figure 2 This is a microscope image of a single PtSe2 pattern with a thickness of 5 nm prepared according to an embodiment of the present invention.

[0026] Figure 3 This is a Raman peak diagram of a 5 nm thick PtSe2 pattern prepared according to an embodiment of the present invention.

[0027] Figure 4 This is a set of optical microscope images and Raman peak images of 5 nm thick PtSe2 patterns with different patterns prepared according to an embodiment of the present invention, wherein a1 is the Raman peak image corresponding to image b1, and a2 is the Raman peak image corresponding to image b2.

[0028] Figure 5 This is a set of AFM images of 5 nm thick PtSe2 patterns with different patterns prepared according to an embodiment of the present invention, wherein b1 is the thickness image corresponding to image a1, and b2 is the thickness image corresponding to image a2.

[0029] Figure 6 The present invention discloses an application of a PtSe2 thin film pattern prepared in an embodiment of the present invention in a heterojunction photodetector. DETAILED DESCRIPTION

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings of the present invention. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, other embodiments obtained by ordinary technicians in this field without creative work are all within the scope of protection of the present invention. The experimental methods described in the following embodiments are all conventional methods unless otherwise specified; the reagents and materials, unless otherwise specified, can be obtained from public commercial channels.

[0031] Spatially relative terms such as "below," "beneath," "below," "above," "upper," etc. are used in this specification to explain the positioning of one element relative to a second element. These terms are intended to encompass different orientations of the device in addition to different orientations than those depicted in the figures.

[0032] In addition, the use of terms such as "first", "second", etc. to describe various elements, layers, regions, sections, etc. is not intended to be limiting. The use of "having", "containing", "including", "comprising", etc. is open-ended, indicating the presence of the stated elements or features, but does not exclude additional elements or features. Unless the context clearly states otherwise.

[0033] An embodiment of the present invention provides a method for patterning a two-dimensional semi-metallic thin film. The method for patterning a two-dimensional semi-metallic thin film of the present invention is described below by taking the preparation of a two-dimensional semi-metallic dichalcogenide PtSe2 as an example.

[0034] First, select SiO2 / Si substrate, and soak the silicon wafer in acetone solution, isopropanol solution, and deionized water in turn. Ultrasonicate for 5 minutes after each soaking. After the ultrasonication, use a nitrogen gun to blow clean the surface of the silicon wafer.

[0035] Next, spin-coat the photoresist on the SiO2 / Si substrate. Use the EZ4 SPINCOATER photolithography machine, place the silicon wafer on the coating machine, set the speed to about 5000r / min, absorb a small amount of positive photoresist, and drop it on the silicon wafer for coating. Then place the silicon wafer after coating on a heating table at 100 degrees for 4 minutes, and cover it with a cover during heating to avoid being affected by external light.

[0036] Then, the silicon wafer after coating was placed in the photolithography machine, the photolithography time was set to 1250ms, and after focusing, the photolithography was performed and developed to form a patterned photoresist layer. The developer was C4H 13 NO:H2O=33:1. After patterning the photoresist layer, the exposed substrate area between adjacent photoresist patterns is 100μm 2 above.

[0037] Next, a Pt layer is deposited on the developed silicon wafer. The electron beam evaporation process is preferably performed, and the electron beam flow rate is set to , a Pt thin layer with a thickness of 5 nm was evaporated on the silicon wafer.

[0038] After the evaporation is completed, the silicon wafer deposited with the Pt thin layer is placed in anhydrous ethanol to remove the photoresist layer, and then the silicon wafer is transferred to anhydrous ethanol for ultrasonic predetermined time to form a patterned Pt layer. Specifically, the silicon wafer is first soaked in anhydrous ethanol until the silicon wafer turns white and then turns back to the true color of the silicon wafer (at this time, the photoresist is dissolved in large quantities), and the anhydrous ethanol is made to flow, and the flowing anhydrous ethanol peels off the residual Pt film and takes it away. Then the silicon wafer is quickly transferred to an ultrasonic cleaning machine containing anhydrous ethanol, and the ultrasonic power and ultrasonic cleaning time are set. During the transfer process, it is ensured that the surface of the silicon wafer is wetted with droplets. The ultrasonic cleaning step can remove the residues on the edge of the Pt layer pattern, ensure that the pattern edge is clear and neat, and improve the perfect rate of the pattern. In this preferred embodiment, the multifunctional ultrasonic cleaning machine of Shenzhen Songneng Cleaning Equipment Co., Ltd. model GS-010 is selected, and the ultrasonic power is set to 70W, and the ultrasonic time is 1 minute. At this time, the energy density of the ultrasound is about 53.8W / cm 3 After the ultrasound is completed, use a nitrogen gun to blow away the anhydrous ethanol on the surface of the silicon wafer, and then place it under a microscope for observation.

[0039] Next, the SiO2 / Si wafer with the patterned Pt layer is placed in a CVD tube furnace and sintered with nitrogen to form a PtSe2 layer. First, the silicon substrate and selenium powder are placed in a tube furnace, nitrogen is introduced for 20 minutes, and then the temperature is raised to 400°C within 30 minutes, and the temperature is maintained at 400°C for 30 minutes, and then cooled naturally.

[0040] like Figures 1 to 5 Show, Figure 1 and Figure 2 The different patterns of the semi-metallic two-dimensional material PtSe2 prepared in the above preferred embodiment are shown. The area of ​​each single pattern in the figure is relatively large. It can be seen that Figure 1 The pattern of the words "Guangdong University of Technology" and the graphic array pattern have good integrity, and the edges of the patterns are clear and complete. Figure 2 It is a single long strip pattern with a certain angle, the pattern has good integrity, and the edges are clear and complete. It can be seen that the PtSe2 pattern prepared by the method of the present invention has a high success rate, the silicon wafer surface is clean, almost free of impurities, the pattern is clear, and the edges are neat. Figure 3 and Figure 4 It can be seen from the Raman test of different patterns in the figure that the method of the present invention can completely Se-conduce the Pt thin layer and obtain a good quality material layer. Figure 5From the AFM test results, it can be seen that the surfaces of two-dimensional material PtSe2 patterns of different shapes are flat, all 5nm thick, and the edges are very neat and clear without any residue. Figure 6 It is a diagram of a PtSe2 pattern obtained by the method of the present invention applied to a heterojunction photoelectric device, wherein Figure a1 is a PtSe2-MoS2 heterojunction photoelectric device, and Figure a2 is a PtSe2-WSe2 heterojunction photoelectric device.

[0041] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for patterning a two-dimensional semi-metallic thin film, characterized in that: The following steps are involved: Spin coating a photoresist layer on a SiO2 / Si substrate and then heating the photoresist layer; exposing and developing to form a patterned photoresist layer; Depositing a Pt thin layer less than 10 nm on the patterned photoresist layer; The substrate with the Pt thin layer deposited thereon is placed in a first anhydrous ethanol to remove the photoresist layer, and then the substrate is placed in a second anhydrous ethanol and ultrasonicated for 60 to 90 seconds to form a patterned Pt thin layer, wherein the energy density of the ultrasonication is 42 to 54 W / cm 3 ; A patterned two-dimensional semi-metal dichalcogenide layer of PtSe2, PtTe2 or PtS2 is formed on the substrate using a chemical vapor deposition process in a tube furnace.

2. The method for patterning a two-dimensional semi-metallic thin film according to claim 1, characterized in that: The predetermined time of ultrasound is selected to be 60 seconds.

3. The method for patterning a two-dimensional semi-metallic thin film according to claim 1 or 2, characterized in that: The area of ​​the Pt thin layer is 100 μm 2 above.

4. The method for patterning a two-dimensional semi-metallic thin film according to claim 3, characterized in that: The thickness of the Pt thin layer is less than 7 nm.

5. The method for patterning a two-dimensional semi-metallic thin film according to any one of claims 1, 2 and 4, characterized in that: The step of placing the substrate with the Pt thin layer deposited thereon in a first anhydrous ethanol to remove the photoresist layer includes immersing the substrate with the Pt thin layer deposited thereon in the first anhydrous ethanol until the color of the substrate changes back to the original color of the substrate, and then allowing the first anhydrous ethanol to flow to the Pt thin layer on the photoresist layer to be peeled off.

6. A patterned two-dimensional semi-metal film, characterized in that: The patterned two-dimensional semi-metallic film is obtained by the method according to any one of claims 1 to 5.

7. The two-dimensional semi-metal film according to claim 6, characterized in that: Application of the two-dimensional semi-metallic film in the field of optoelectronic devices.

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