Anisotropic device manufacturing method based on laser processing

Abstract

The invention discloses an anisotropic device manufacturing method based on laser processing. Comprising the following steps: step 1, growing a SiO2 oxide layer on the surface of n-type silicon through thermal oxidation, then annealing in an argon environment to prepare a substrate, and then cleaning the substrate; 2, depositing Au and Ni on the substrate as a bottom electrode by using a photoetching method; 3, stripping single-layer MoS2 by using a mechanical stripping method, and transferring the single-layer MoS2 to the center of the bottom electrode prepared in the step 2; and 4, performing gray processing on the single-layer MoS2 by using laser to obtain an anisotropic device finished product. Through a laser processing method, the resistivity of the MoS2 material in each direction is different, so that the MoS2 material has anisotropic properties, and the application field of isotropic materials is widened.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor electronic devices, and in particular to a method for manufacturing an anisotropic device based on laser processing. Background Art

[0002] Anisotropy refers to the fact that all or part of the chemical, physical and other properties of a substance change with the change of direction, showing different properties in different directions. From a microscopic point of view, the anisotropy of crystals is that in the same crystal, due to the different orientations of the crystal faces, the physical and chemical properties of the crystals in different directions are also different. The anisotropy of crystals is specifically manifested in the different elastic modulus, hardness, fracture resistance, yield strength, thermal expansion coefficient, thermal conductivity, resistivity, electric displacement vector, electric polarization, magnetic susceptibility and refractive index in different directions of the crystal. Anisotropy, as an important characteristic of crystals, has very important research value. In recent years, the study of exploring the anisotropy of materials has attracted the attention of scientific researchers.

[0003] Isotropic single-layer MoS2 materials have great potential applications in the fields of electronics and optoelectronics due to their special electrical and optical properties. Currently studied semiconductor electronic devices fully utilize the performance of MoS2 materials in a single dimension, but the development of anisotropy is still insufficient. Summary of the invention

[0004] The purpose of the present invention is to provide a method for manufacturing anisotropic devices based on laser processing. The present invention uses a laser processing method to make the resistivity of MoS2 material different in each direction, so that it has anisotropic properties and broadens the application field of isotropic materials.

[0005] The technical solution of the present invention is as follows: a method for manufacturing an anisotropic device based on laser processing; comprising the following steps:

[0006] Step 1, thermally oxidizing and growing a SiO2 oxide layer on the surface of n-type silicon, then annealing in an argon environment to prepare a substrate, and then cleaning the substrate;

[0007] Step 2: Depositing Au and Ni as bottom electrodes on the substrate using photolithography;

[0008] Step 3: Use mechanical exfoliation to exfoliate the single-layer MoS2 and transfer the single-layer MoS2 to the center of the bottom electrode prepared in step 2;

[0009] Step 4: Use laser to perform grayscale processing on the single layer of MoS2 to obtain a finished anisotropic device.

[0010] In the above-mentioned method for manufacturing anisotropic devices based on laser processing, in step 1, the thickness of the grown SiO2 oxide layer is 300nm.

[0011] In the aforementioned method for manufacturing anisotropic devices based on laser processing, in step 1, the annealing temperature is 550-600°C.

[0012] In the aforementioned method for manufacturing anisotropic devices based on laser processing, in step 1, during cleaning, acetone, anhydrous ethanol, and deionized water are used for ultrasonic cleaning for 5-10 minutes each, with an ultrasonic power of 50-60W, and nitrogen is used to quickly blow dry after cleaning.

[0013] In the aforementioned method for manufacturing anisotropic devices based on laser processing, in step 2, the photolithography parameters of the photolithography method are: laser wavelength 405nm, laser power 10mW, laser pulse width 200ns.

[0014] In the aforementioned method for manufacturing anisotropic devices based on laser processing, in step 2, the photoresist in the photolithography method is AR 3110, the spin coating parameter is 3000r / min; the developer is 0.26mol / L tetramethylammonium hydroxide aqueous solution, and the developing time is 30s.

[0015] In the aforementioned method for manufacturing anisotropic devices based on laser processing, in step 2, the coating parameters of the magnetron sputtering apparatus in the photolithography method are:

[0016] For Au: ignition power 150W, coating power 50W, time 300s, film thickness 50nm;

[0017] For Ni: ignition power 50W, coating power 50W, time 50s, film thickness 5nm.

[0018] In the aforementioned method for manufacturing anisotropic devices based on laser processing, in step 3, the single layer MoS2 is placed in a glove box with argon as the protective gas for transfer, and the water vapor and oxygen concentrations in the glove box are lower than 1 p.pm.

[0019] In the aforementioned method for manufacturing anisotropic devices based on laser processing, in step 4, the laser processing parameters are a laser wavelength of 405 nm, a laser power within 120 mW, and a laser pulse width of 2000 ns; the processing range is a circular area formed with the center point of the single-layer MoS2 as the center of the circle.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention first prepares a bottom electrode composed of Au and Ni on a substrate composed of SiO2 and Si, then uses a mechanical stripping method to obtain a single layer of MoS2 and transfers it to the bottom electrode, and finally uses laser grayscale processing to treat the MoS2 material. As the laser acts on the surface of the single layer of MoS2 material, it will generate a thermal effect, driving away the S atoms or directly sublimating the S atoms, so that MoS2 produces S vacancies to adsorb O in the air. Because the laser acts on the MoS2 material in grayscale, the number of O atoms adsorbed in different directions of the material is different, so that the conductivity of the MoS2 material in different directions is different, thereby making the MoS2 material have anisotropic properties, thereby broadening the application field of isotropic materials.

[0022] 2. The present invention uses Au as the electrode material and Ni as the adhesion layer between Au and the substrate, which can make Au / Ni and SiO2 / Si adhere more firmly without affecting their conductive function, thereby preventing Au / Ni from falling off when the bottom electrode is cleaned with acetone.

[0023] 3. The present invention adopts a laser processing method, which has a simple process, high precision, high flexibility, does not introduce external impurity pollution, and can ensure that the device has high performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A flowchart of an example of the present invention;

[0025] Figure 2 Schematic diagram of grayscale power laser when laser writing material, where the laser pulse width is 2000ns;

[0026] Figure 3 It is a schematic diagram of the structure of a MoS2 semiconductor device;

[0027] Figure 4 IV curves of MoS2 in different directions.

[0028] Reference numerals

[0029] 1. SiO2 oxide layer; 2. Si substrate; 3. Au / Ni electrode; 4. Single layer MoS2. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the present invention. The protection scope of the present invention should include the entire content of the claims, and the following embodiments can enable ordinary technicians in the field to more fully understand the present invention.

[0031] Embodiment: A method for manufacturing anisotropic devices based on laser processing, such as Figure 1 As shown, the following steps are included:

[0032] Step 1, thermally oxidizing and growing a SiO2 oxide layer on the surface of n-type silicon, then annealing in an argon environment to prepare a substrate, and then cleaning the substrate;

[0033] In this step, the thickness of the grown SiO2 oxide layer is 300nm, the annealing temperature is 550-600℃, and after annealing, ultrasonic cleaning is carried out for 5-10 minutes using acetone, alcohol, and deionized water in sequence, with an ultrasonic power of 50-60W. After ultrasonic cleaning, it is quickly dried with nitrogen and placed in a sample box.

[0034] Step 2: Depositing Au and Ni as bottom electrodes on the substrate using photolithography;

[0035] In this step, the substrate is placed on a glue-splitting table and fixed by suction (nitrogen). Under the environmental conditions of yellow light, AR 3110 (positive photoresist) is dripped onto the substrate surface (SiO2) using a 5ml rubber-tipped dropper, and then the glue-splitting table is set at 3000r / min to evenly coat the photoresist on the substrate. The substrate is heated with a 105°C heating plate in a fume hood to cure the photoresist. The sample is exposed using a 405nm wavelength UV lithography machine, with laser parameters of 10mW power and 200ns pulse width. After exposure, the substrate is placed in a 0.26mol / L tetramethylammonium hydroxide (TMAH) developer, developed for 30s, and gently blown dry with nitrogen. A clear electrode pattern can be seen under a light microscope. Next, magnetron sputtering was used for coating. Ni was first plated: ignition power 50W, coating power 50W, time 50s, film thickness about 5nm, and then Au was plated: ignition power 150W, coating power 50W, time 300s, film thickness about 50nm. The substrate was placed in a petri dish filled with acetone, and the unexposed areas on the substrate were slowly blown clean with a needle, leaving only the bottom electrode, and finally dried with nitrogen and placed in a sample box.

[0036] Step 3: Use mechanical exfoliation to exfoliate the single-layer MoS2 and transfer the single-layer MoS2 to the center of the bottom electrode prepared in step 2;

[0037] In this step, the mechanical stripping method uses a sticky tape method. Select a 5-10cm section of 3M Scotch tape, use tweezers to clamp a small piece of MoS2 in the middle of the tape, gently compact it so that the tape can be evenly attached to the surface of MoS2, and slowly tear off the tape. There will be a layer of MoS2 flakes on the surface of the tape. Fold the tape in half 3-5 times along the middle position so that MoS2 can be more evenly distributed on the tape. Take another 10-15cm section of tape, fit it at 90° to the tape with MoS2, gently squeeze it so that the two sections of tape can fit completely, slowly tear it off, and steadily divide the MoS2 flakes into two. Keep the second section of tape and repeat the first section of tape stripping steps 10-15 times until the metallic luster of MoS2 on the tape fades. Place the tape with the MoS2 flakes upside down on the PDMS (already attached to the glass slide), use an elastic ball to gently squeeze out the air between the tape and PDMS, so that the tape and PDMS are completely attached, slowly peel off the tape from the PDMS, repeat several times, and the MoS2 is transferred to the PDMS. Use an optical microscope to screen out the PDMS sample with a single layer of MoS2.

[0038] Transfer in a glove box with argon as the protective gas (water vapor and oxygen concentrations are less than 1p.pm). Fix the PDMS with a single layer of MoS2 on a three-axis translation stage. Through a microscope, adjust the position of the translation stage so that the center of the prepared bottom electrode and the center of the single layer of MoS2 on the glass slide are at the same position in the vertical direction, and slowly lower the glass slide through the three-axis translation stage until the PDMS is bonded to the substrate. After 3 minutes of bonding, slowly raise the glass slide. Since the van der Waals force between MoS2 and the bottom electrode is greater than the adhesion force between MoS2 and PDMS, the single layer of MoS2 will remain on the bottom electrode, thereby transferring the single layer of MoS2 to a specific position on the bottom electrode, and no residual glue will be left on the bottom electrode.

[0039] Step 4: Use laser to perform grayscale processing on the single layer of MoS2 to obtain a finished anisotropic device.

[0040] In this step, the sample is placed at a suitable position on the laser processing platform by using a translation stage and a microscope, and a circular grayscale pattern (such as Figure 3 As shown in the figure, the laser is introduced into the laser writing system and accurately written on the corresponding single layer of MoS2, wherein the laser processing parameters are: laser wavelength 405nm, laser power within 120mW, and laser pulse width 2000ns.

[0041] The final anisotropic device is as follows Figure 3 Using a probe station to test the laser processed single layer MoS2 material, we can get different results for the conductivity in each direction of the single layer MoS2, as shown in the figure. Figure 4As shown, this proves that the single-layer MoS2 material has anisotropic properties.

[0042] In summary, the present invention utilizes laser grayscale processing to process MoS2 material. Since the laser acts on the surface of the monolayer MoS2 material, a thermal effect will be generated, which will drive away the S atoms or directly sublimate the S atoms, so that MoS2 produces S vacancies to adsorb O in the air. Because the laser acts on the MoS2 material in grayscale, the number of O atoms adsorbed in different directions of the material is different, so that the conductivity of the MoS2 material in different directions is different, and then the MoS2 material has anisotropic properties, which broadens the application field of isotropic materials. In addition, the Au used in the present invention is used as the electrode material, and Ni is used as the adhesion layer between Au and the substrate. While not affecting its conductive effect, Au / Ni can be made to adhere to SiO2 / Si more firmly, and Au / Ni can be prevented from falling off when the bottom electrode is cleaned with acetone. The present invention adopts the method of laser processing, which is simple in process, high in accuracy, high in flexibility, does not introduce external impurity pollution, and can ensure that the device has higher performance.

Claims

1. A method for manufacturing anisotropic devices based on laser processing; characterized in that: The steps include: Step 1, thermally oxidizing and growing a SiO2 oxide layer on the surface of n-type silicon, then annealing in an argon environment to prepare a substrate, and then cleaning the substrate; Step 2: Depositing Au and Ni as bottom electrodes on the substrate using photolithography; Step 3: Use mechanical exfoliation to exfoliate the single-layer MoS2 and transfer the single-layer MoS2 to the center of the bottom electrode prepared in step 2; Step 4: Use laser to perform grayscale processing on the single layer of MoS2 to obtain a finished anisotropic device.

2. The method for manufacturing an anisotropic device based on laser processing according to claim 1, characterized in that: In step 1, the thickness of the grown SiO2 oxide layer is 300nm.

3. The method for manufacturing anisotropic devices based on laser processing according to claim 1, characterized in that: In the step 1, the annealing temperature is 550-600°C.

4. The method for manufacturing anisotropic devices based on laser processing according to claim 1, characterized in that: In the step 1, during cleaning, acetone, anhydrous ethanol and deionized water are used for ultrasonic cleaning for 5-10 minutes respectively, and the ultrasonic power is 50-60W. After cleaning, nitrogen is used to quickly blow dry.

5. The method for manufacturing anisotropic devices based on laser processing according to claim 1, characterized in that: In step 2, the photolithography parameters of the photolithography method are: laser wavelength 405nm, laser power 10mW, laser pulse width 200ns.

6. The method for manufacturing an anisotropic device based on laser processing according to claim 5, characterized in that: In the step 2, the photoresist used in the photolithography method is AR 3110, the spin coating parameter is 3000 r / min, the developer is 0.26 mol / L tetramethylammonium hydroxide aqueous solution, and the developing time is 30 s.

7. The method for manufacturing an anisotropic device based on laser processing according to claim 6, characterized in that: In step 2, the coating parameters of the magnetron sputtering apparatus in the photolithography method are: For Au: ignition power 150W, coating power 50W, time 300s, film thickness 50nm; For Ni: ignition power 50W, coating power 50W, time 50s, film thickness 5nm.

8. The method for manufacturing an anisotropic device based on laser processing according to claim 1, characterized in that: In step 3, the single layer MoS2 is placed in a glove box with argon as the protective gas for transfer, and the water vapor and oxygen concentrations in the glove box are lower than 1 ppm.

9. The method for manufacturing anisotropic devices based on laser processing according to claim 1, characterized in that: In step 4, the laser processing parameters are: laser wavelength 405nm, laser power within 120mW, laser pulse width 2000ns; the processing range is a circular area formed with the center point of the single layer MoS2 as the center.

Images