Preparation method of two-dimensional material field effect transistor based on NaCl thin film auxiliary stripping

Abstract

The invention relates to the technical field of semiconductor devices, and provides a preparation method of a two-dimensional material field effect transistor based on NaCl thin film auxiliary stripping in order to solve the problems that an existing two-dimensional nano material stripping process is large in difficulty and low in efficiency and improve the performance and yield of devices. Comprising the following steps that S1, a NaCl thin film layer with the thickness of about 100 nm is evaporated on the surface of a material, and a large-area and high-quality two-dimensional nano material can be obtained in combination with a heat release adhesive tape technology; and S2, transferring to a solid lithium ion conductor of which an electrode is evaporated by a mask plate technology in advance, so as to realize the preparation of the solid lithium ion conductor device. The preparation method is simple in process flow, can realize rapid, efficient, low-cost, large-batch and high-quality production of various two-dimensional nano materials, and is beneficial to improving the performance and the yield of the device.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and particularly to a preparation method of a two-dimensional material field effect transistor based on NaCl film-assisted exfoliation. Background Art

[0002] Since the discovery of graphene, two-dimensional nanomaterials have attracted extensive attention from researchers due to their unique physical properties and application values. When a two-dimensional material is stretched or compressed, the distance between its atoms changes, and the energy band structure and electronic properties change accordingly. Compared with other semiconductor materials, the geometric morphology of two-dimensional materials is more operable. In particular, a field effect transistor prepared by using the changes in the energy band structure and electronic properties caused by the strain of two-dimensional materials is expected to break Moore's law, achieve higher integration, and improve the performance of field effect transistor devices.

[0003] The preparation of a two-dimensional nanomaterial field effect transistor first requires the preparation of a two-dimensional nanomaterial with a nanoscale thickness. Usually, the methods for obtaining a two-dimensional nanomaterial with a nanoscale thickness include vapor growth method and mechanical exfoliation method. The vapor growth method has a low cost, but a long development cycle, and has certain limitations for materials. Moreover, the more elements the material itself has, the more difficult it is to develop. Mechanical exfoliation usually uses mechanical force to exfoliate the nanomaterial from its substrate. This process is time-consuming and laborious, and the yield is relatively low. The thickness of the obtained nanomaterial is uneven. Chinese Patent No. 201610312907.0 discloses a two-dimensional material field effect transistor and a preparation method. The preparation method of the present invention first transfers the two-dimensional material to an insulating dielectric layer by mechanical exfoliation. This exfoliation technology has incomplete exfoliation, low yield, and it is difficult to obtain a large-size two-dimensional nanomaterial, thus limiting its further preparation into a two-dimensional nanomaterial field effect transistor. Summary of the Invention

[0004] In order to achieve the above object, the present invention adopts the following technical solutions: A preparation method of a two-dimensional material field effect transistor based on NaCl film-assisted exfoliation, comprising the following steps:

[0005] S1: First, attach the material sample to the tape, then take a new tape and paste it with the previous one, tear the tape, and the sample on the tape is divided into two, and a fresh exfoliation surface is exposed.

[0006] S2: Place the tape with the sample in a thermal evaporation coating machine. After evacuating to a certain value, set the evaporation current to increase, perform thermal evaporation to deposit the NaCl film, and control the coating rate and the final coating thickness.

[0007] S3: After evaporating the NaCl thin film, use a thermal release tape to closely adhere to the surface of the sample with the evaporated NaCl thin film, gently press to expel the air between the two, and then tear off the tape. At this time, the thin film together with the two-dimensional nanomaterial with a very thin thickness will be adhered by the thermal release tape.

[0008] S4: Paste the PDMS film on the thermal release tape and place it on a heating stage to heat to the temperature at which the thermal release tape loses its adhesiveness. In this way, the two-dimensional nanomaterial will be released and transferred to the PDMS film.

[0009] S5: Use a transfer platform to transfer the sample on the PDMS film to a PDMS film with stronger adhesiveness.

[0010] S6: Paste the PDMS film and the two-dimensional nanomaterial sample on it onto a lithium-ion conductor ceramic glass substrate with pre-lithographed and evaporated electrodes, and evaporate the electrodes through a mask technology to realize the preparation of a solid lithium-ion conductor device.

[0011] S7: Place the device obtained in S6 in deionized water for a certain period of time, and the NaCl layer covering the surface of the two-dimensional material can be easily washed away.

[0012] Further, the vacuum degree of the thermal evaporation coating machine is 10 -4 , and the rate is controlled at 0.2 A / S to 10 A / S to achieve a final coating thickness of 80 to 100 nm.

[0013] Further, the heating temperature of the heating stage is 100 - 120 °C, and at this temperature, the thermal release tape loses its adhesiveness.

[0014] Further, the material of the two-dimensional material layer is a van der Waals material such as a carbon nanotube layer, graphene, or molybdenum disulfide.

[0015] Further, the time for placing the device in deionized water is 10 - 30 S.

[0016] The beneficial effects of the present invention include:

[0017] 1. The present invention adopts the NaCl thin film-assisted peeling method, with fewer transfer steps, avoiding material loss during repeated transfer processes, greatly improving the cleavage efficiency and yield of two-dimensional materials, and large-area high-quality two-dimensional nanomaterials can be obtained.

[0018] 2. The thin-layer material prepared by the present invention does not contact any liquid organic substances, which can ensure that the surface of the obtained two-dimensional material is cleaner and is beneficial to improving the device performance.

[0019] 3. In a solid lithium-ion device, the voltage has a strong regulatory ability and reversibility for the resistance of two-dimensional materials.

[0020] 4. The preparation process flow of the present invention is simple, and it can realize the production of various two-dimensional layered nanomaterials quickly, efficiently, at low cost, in large quantities and with high quality, which is beneficial to improving the performance and yield of devices. Description of the Drawings

[0021] The present invention will be further described below in conjunction with the drawings.

[0022] Figure 1 is an image of the NaCl-assisted exfoliated Cr2Ge2Te6 sample under a microscope;

[0023] Figure 2 is an image of the solid ion device of Cr2Ge2Te6 exfoliated by NaCl;

[0024] Figure 3 The thickness of the NaCl-assisted exfoliated Cr2Ge2Te6 nanomaterial measured by atomic force microscopy;

[0025] Figure 4 Applying a gate voltage to regulate the resistivity of the nanoscale Cr2Ge2Te6 sample;

[0026] Figure 5 An image of the NaCl-assisted exfoliated CsVSb sample under a microscope; Detailed Embodiments

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0028] Embodiment 1

[0029] The field effect transistor prepared by using the NaCl thin film-assisted exfoliation of the two-dimensional nanomagnetic Cr2Ge2Te6 material provided by the embodiment of the present application includes the following steps:

[0030] S1: Attach the Cr2Ge2Te6 single crystal material sample to the tape, then take a new piece of tape and paste it with it, tear the tape, and the sample on the tape is divided into two, and a fresh Cr2Ge2Te6 exfoliation surface is exposed. If a fresh exfoliation surface cannot be obtained by one-time tearing, multiple tearing operations can be performed to obtain a fresh exfoliation surface. Since the fresh exfoliation surface is very smooth and has the characteristic of reflecting light, this characteristic can be used as an aid for judgment.

[0031] S2: Place the tape together with the sample in a thermal evaporation coating machine. Add an appropriate amount of NaCl particles onto the tungsten boat of the evaporation heating source of the coating equipment, and evacuate the equipment to a vacuum of 1x10-4. Observe the melting situation of the NaCl particles on the tungsten boat through the transparent window. Stop increasing the current when they start to melt, and use a film thickness gauge to monitor the coating rate. Control the coating rate between 0.2 A / S and 10 A / S to achieve a final coating thickness of 100 nm.

[0032] S3: After evaporating the NaCl thin film, use a thermal release tape to closely adhere to the surface of the Cr2Ge2Te6 sample coated with the NaCl thin film. Gently press to expel the air between the two, and then tear off the tape. At this time, the germanium thin film together with the two-dimensional nanomaterial with a very thin thickness will be pasted by the thermal release tape. Observe the light transmittance of the sample under a microscope to judge the thickness of the obtained sample. If the sample thickness is relatively thick at this time, the sample can be continuously pasted and torn off with the tape multiple times until a two-dimensional nano Cr2Ge2Te6 sample with the required thinner thickness is obtained.

[0033] S4: Paste the thermal release tape with the thin-layer two-dimensional nano Cr2Ge2Te6 sample on the PDMS film and place it on a heating stage heated to 120 °C. At this temperature, the thermal release tape loses its adhesiveness, and the two-dimensional nanomaterial will be released and transferred to the PDMS film. Since the PDMS film is transparent, the sample can be observed under a microscope and the thickness and size of the sample can be confirmed using optical effects. As follows Figure 1 The following shows the image of a sample with a length greater than 50 um and a nm-level thickness under a microscope

[0034] S5: Use a transfer platform to transfer the sample on the PDMS film to a PDMS film with stronger adhesiveness.

[0035] S6: Paste and transfer the PDMS film and the two-dimensional nano Cr2Ge2Te6 sample on it to the electrode on a pre-coated lithium-ion conductor substrate.

[0036] S7: Immerse the device in deionized water for 20 S to remove the NaCl layer covering the surface, and complete the fabrication of the solid lithium-ion device based on two-dimensional nano Cr2Ge2Te6.

[0037] Example 2

[0038] The steps for preparing a nano-superconducting material CsV3Sb5 solid ion device by NaCl thin film-assisted exfoliation provided in the embodiment of the present application are as follows:

[0039] S1: Stick the CsV3Sb5 single crystal material sample on the tape, then take a new piece of tape and stick it to the sample. Tear the tape, and the sample on the tape is divided into two parts, exposing a fresh exfoliation surface of CsV3Sb5. Due to the strong van der Waals force between the CsV3Sb5 single crystal layers, usually a single tear cannot obtain a fresh exfoliation surface, and it is necessary to tear more than 3 times to obtain a fresh exfoliation surface.

[0040] S2: Place the tape with the sample in a thermal evaporation coater. Add an appropriate amount of NaCl particles on the tungsten boat of the evaporation heating source of the coating equipment. Pump the vacuum of the equipment to 2x10-4. Set the evaporation current to increase. Observe the melting situation of the NaCl particles on the tungsten boat through the transparent window. Stop increasing the current when they start to melt, and use a film thickness gauge to monitor the coating rate. Control the coating rate between 0.2A / S and 5A / S to achieve a final coating thickness of 80nm.

[0041] S3: After evaporating the NaCl thin film, use a thermal release tape to closely adhere to the surface of the CsV3Sb5 sample coated with the NaCl thin film. Gently press to expel the air between the two, and then tear the tape. At this time, the germanium thin film and the two-dimensional nanomaterial with a very thin thickness will be adhered by the thermal release tape. Observe the light transmittance of the sample under the microscope to judge the thickness of the obtained sample. If the sample thickness is relatively thick at this time, the sample can be repeatedly pasted and torn with the tape until a two-dimensional nanoscale CsV3Sb5 sample with the required thinner thickness is obtained.

[0042] S4: Stick the thermal release tape with the thin-layer two-dimensional nanoscale CsV3Sb5 sample on the PDMS membrane and place it on a heating stage heated to 120°C. At this temperature, the thermal release tape loses its adhesiveness, and the two-dimensional nanomaterial will be released and transferred to the PDMS membrane. Since the PDMS membrane is transparent, the sample can be observed under the microscope and the thickness and size of the sample can be confirmed using optical effects. As follows Figure 5 The image of the CsV3Sb5 sample with a thickness of the nm level under the microscope is shown.

[0043] S5: The subsequent steps are the same as those in Example 1, and a corresponding nanomaterial CsV3Sb5 solid ion device can be fabricated.

Claims

1. A method for preparing a two-dimensional material field effect transistor based on NaCl film assisted peeling, characterized in that: The following steps are involved: S1: First, stick the material sample on the tape, then take a new piece of tape and stick it to each other, tear off the tape, the sample on the tape is divided into two, and the fresh peeling surface is exposed. S2: Place the tape and the sample in a thermal evaporation coating machine, evacuate the vacuum to a certain value, and then perform thermal evaporation to deposit a NaCl film to control the coating rate and the final coating thickness. S3: After the NaCl film is evaporated, use thermal release tape to tightly adhere to the surface of the sample with the NaCl film evaporated, gently press to expel the air between the two, and tear off the tape. At this time, the film and the very thin two-dimensional nanomaterial will be stuck together by the thermal release tape. S4: Stick the PDMS film on the thermal release tape, place it on a heating table and heat it to a temperature at which the thermal release tape loses its stickiness, so that the two-dimensional nanomaterial will be released and transferred to the PDMS film. S5: Use the transfer platform to transfer the sample on the PDMS membrane to a PDMS membrane with stronger adhesion. S6: Paste the PDMS film and the two-dimensional nanomaterial sample on it to the lithium ion conductor ceramic glass substrate on which the electrode has been previously photolithographically evaporated, and evaporate the electrode through the mask template technology to realize the preparation of the solid lithium ion conductor device. S7: Place the device obtained in S6 in deionized water to easily wash away the NaCl layer covering the surface of the two-dimensional material.

2. The method for preparing a two-dimensional material field effect transistor based on NaCl film assisted exfoliation according to claim 1, characterized in that: Vacuum degree of thermal evaporation coating machine 10 -4 The rate is controlled at 0.2A / S~10A / S, and the final coating thickness is 80~100nm.

3. The method for preparing a two-dimensional material field effect transistor based on NaCl film assisted exfoliation according to claim 1, characterized in that: The heating temperature of the heating stage is 120° C., at which temperature the thermal release tape loses its stickiness.

4. The method for preparing a two-dimensional material field effect transistor based on NaCl film assisted exfoliation according to claim 1, characterized in that: The material of the two-dimensional material layer is a van der Waals material such as graphene and molybdenum dioxide.

5. The method for preparing a two-dimensional material field effect transistor based on NaCl film assisted exfoliation according to claim 1, characterized in that: The device is placed in deionized water for 10 to 30 seconds.

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