CN111155065B

CN111155065B - Preparation stripping and transferring method of hexagonal boron nitride film

Info

Publication number: CN111155065B
Application number: CN202010060218.1A
Authority: CN
Inventors: 李强; 白云鹤; 张启凡; 秦潇; 云峰
Original assignee: Xian Jiaotong University
Current assignee: Xian Jiaotong University
Priority date: 2020-01-19
Filing date: 2020-01-19
Publication date: 2021-02-02
Anticipated expiration: 2040-01-19
Also published as: CN111155065A

Abstract

The invention discloses a method for preparing, stripping and transferring a hexagonal boron nitride film, which is characterized in that the hexagonal boron nitride film (h-BN film) is prepared in a magnetron sputtering mode, and a physical method of solution soaking is adopted to realize rapid large-area complete stripping. The control of the stripping speed of the h-BN film is realized by different proportions of deionized water or alkaline solution. The h-BN film is prepared by the magnetron sputtering method, the process is simple, large-area uniform preparation can be realized, the industrial production is easy to realize, meanwhile, the stripping method can realize large-area complete nondestructive stripping, the stripping speed is controllable, and important foundations are provided for researching the characteristics of the h-BN film and preparing a vertical-structure high-power deep ultraviolet LED device.

Description

Preparation stripping and transferring method of hexagonal boron nitride film

Technical Field

The invention belongs to the technical field of photoelectric devices and functional films, and particularly relates to a magnetron sputtering method-based h-BN film preparation method and a stripping and transferring method thereof.

Background

The Boron Nitride (BN) film has the characteristics of wide band gap, good thermal stability, good chemical stability and the like. h-BN is a two-dimensional structure material, and the interaction force between layers is Van der Waals force, so that the h-BN can realize the peeling and the transfer by a physical mode. At the present stage, the h-BN film is mainly prepared by a chemical deposition method, and the transfer of the film is realized by a mode that a substrate is corroded by chemical solution. As described in chinese patent applications 201510039073.6 and 201810622263.4, the peeling transfer of the thin film is achieved by a method of preparing an h-BN thin film on a copper (Cu) substrate and then etching away the Cu substrate with an acid solution. The preparation and stripping costs are high, and the nondestructive large-area uniform stripping transfer of the h-BN film is difficult to realize.

Ultraviolet LEDs have played an important role in sterilization, air and water purification, biological detection and other aspects, and high-power deep ultraviolet LEDs are the development direction in the future. One of the key technologies for preparing the vertical ultraviolet LED is the stripping of the substrate, and the technology adopted at the present stage is the stripping by using a laser ablation method. Due to the characteristics of the epitaxial material, when the laser ablation method is used for stripping, the fragmentation of the epitaxial structure is easily caused, and the stripping cost is high. The development of high-power deep ultraviolet LED devices is limited by the current preparation process level, especially the singleness and limitation of a substrate stripping method.

Disclosure of Invention

The invention aims to provide a peeling and transferring method for preparing a hexagonal boron nitride film, which aims to solve the technical problems. The h-BN film is prepared by the magnetron sputtering method, and the complete stripping of the film is realized by adopting the solution soaking method, so that the film can be successfully transferred to other substrates.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation and stripping method of a hexagonal boron nitride film comprises the following steps:

step 1), putting a clean growth substrate into a sputtering chamber, heating to a sputtering temperature, and depositing a first layer of h-BN film (2) on the substrate by magnetron sputtering in a specific atmosphere;

step 2), after the sputtering of the first layer of h-BN film is finished, naturally cooling the growth substrate to room temperature in vacuum; heating the sputtering chamber to the sputtering temperature again, and depositing a second h-BN film on the first h-BN film by magnetron sputtering under the same specific atmosphere;

step 3), after the second layer of h-BN film is sputtered, naturally cooling the growth substrate to room temperature in vacuum and taking out;

and 4) transferring the growth substrate into a container with deionized water or alkaline solution for soaking, and enabling the second layer of h-BN film to fall off from the first layer of h-BN film to obtain a stripped second layer of h-BN film.

Further, the sputtering temperature in the step 1) is 600 ℃; the specific atmosphere is mixed gas of nitrogen and argon filled into the sputtering chamber, and the gas flow ratio of the nitrogen to the argon is 30:10 sccm; the power of the sputtering target material is 250-400W during magnetron sputtering, the sputtering working pressure is 0.5-0.7 Pa, the target spacing is 100-150 mm, and the vacuum degree is 5 multiplied by 10^-4Pa, the sputtering time is more than or equal to 1.5 h; the thickness of the first layer of h-BN film is 150-200 nm.

Further, the same process parameters as those in the step (1) are adopted in the step 2), and the thickness of the second layer of h-BN film is 100-200 nm.

Further, the concentration range of the alkaline solution in the step 4) is 0.05-1 mol/L.

Further, the soaking time in the step 4) is 3-48 hours.

Further, the alkaline solution is a KOH solution.

Further, after the first layer of h-BN film is sputtered, the growth substrate is naturally cooled to room temperature in vacuum, the growth substrate is stood for 12 hours, the temperature of the sputtering chamber is raised to the sputtering temperature again, and a second layer of h-BN film is deposited on the first layer of h-BN film through magnetron sputtering in the same atmosphere.

Further, the area of the peeled second h-BN film is 0.5-2 inches.

A transfer method of a hexagonal boron nitride film comprises the following steps:

cleaning the transfer substrate, and bombarding the surface by using oxygen plasma;

inserting the transfer substrate into the water surface of the container with the second layer of the h-BN film along the direction of 45 degrees at the lower oblique direction; gradually drawing close to a second layer of h-BN film suspended on the water surface, adsorbing the second layer of h-BN film floating on the water surface of the container by the treated hydrophilic transfer substrate when the transfer substrate contacts the second layer of h-BN film, and flatly releasing the transfer substrate from the water surface; obtaining a transfer substrate with an h-BN film;

and drying the transfer substrate with the h-BN film to finish the transfer of the h-BN film.

Compared with the prior art, the invention has the following beneficial effects:

the h-BN film is prepared by the magnetron sputtering method, so that the process is simpler, and large-area uniform preparation can be realized; the method is characterized in that deionized water or alkaline solution with certain concentration is used for soaking, then the stripping transfer of the h-BN film is realized by a physical method, the large-area nondestructive stripping of the film can be realized, and the industrial production is easy to realize.

The invention can control the stripping speed of the film by using the alkaline solutions with different concentrations, and can select the solutions with different concentrations according to different requirements of the sample.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1: schematic diagram of two layers of h-BN films prepared by a magnetron sputtering method;

FIG. 2: schematic diagram of h-BN film peeling process;

FIG. 3: schematic diagram of the h-BN film transfer process.

Wherein: 1-a growth substrate; 2-a first layer of h-BN film; 3-a second layer of h-BN film; 4-liquid; 5-a container; 6-transfer substrate.

Detailed Description

The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

The following detailed description is exemplary in nature and is intended to provide further details of the invention. Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention.

In order to better understand the solution of the invention, the following examples of the best implementation of the preparation process and the stripping effect are described in detail:

example 1:

(1) cleaning three 0.5-inch silicon substrate samples to serve as a growth substrate 1, placing the growth substrate 1 into a sputtering chamber, heating the chamber to 600 ℃, keeping the temperature for 1h, filling mixed gas of nitrogen and argon into the chamber, wherein the gas flow ratio of the nitrogen to the argon is 30:10sccm, and performing high-purity h-BNThe target material (99.99%) is used as a target source, and a first layer of h-BN film 2 is deposited on the substrate. Wherein the power of the sputtering target material is 250W, the sputtering working pressure is 0.6Pa, the target spacing is 150mm, and the vacuum degree is 5 multiplied by 10^-4Pa, sputtering time 2 h. The thickness of the first h-BN film 2 is 150 nm.

(2) After sputtering is finished, naturally cooling the growth substrate 1 to room temperature in vacuum, and waiting for 12 hours; and heating the chamber and the sample to 600 ℃, preserving the heat for 1h, filling mixed gas of nitrogen and argon into the chamber, wherein the gas flow ratio of the nitrogen to the argon is 30:10sccm, and depositing a second h-BN film 3 on the first h-BN film 2. Depositing a second layer of h-BN film 3 on the substrate, sputtering h-BN target with the power of 200W, the sputtering working pressure of 0.6Pa, the target spacing of 150mm and the vacuum degree of 5 multiplied by 10^-4Pa, sputtering time 1.5h, and thickness of the second h-BN film 3 of 100nm, as shown in FIG. 1.

(3) After sputtering is finished, the growth substrate 1 is naturally cooled to room temperature in vacuum and then taken out;

(4) and respectively transferring the three growth substrates 1 into liquids 4 (deionized water, 0.5mol/L KOH solution and 1mol/L KOH solution) in different containers 5, after 2 days (48 hours) of a sample in the deionized water, starting layering between a second layer of h-BN film 3 and a first layer of h-BN film 2, heating the deionized water with the sample for 20 minutes, partially peeling off the second layer of h-BN film 3, clamping the sample by tweezers, and slowly lifting the sample to the water surface along a separation position, wherein the second layer of h-BN film 3 floats to the water surface under the surface tension of water when passing through the water surface to form a layer of h-BN film. After the film is soaked in 0.5mol/L KOH solution for about 4 hours, the h-BN film begins to be layered, and finally the whole piece falls off and is suspended in the solution. After the film is soaked in 1mol/L KOH solution for about 3 hours, the h-BN film begins to be layered, and finally the whole piece falls off and is suspended in the solution. As shown in fig. 2.

Example 2:

(1) cleaning three 2-inch silicon substrate samples to be used as growth substrates 1, putting the growth substrates 1 into a sputtering chamber, heating the chamber to 60 DEGKeeping the temperature at 0 ℃ for 1h, filling mixed gas of nitrogen and argon into the chamber, wherein the gas flow ratio of the nitrogen to the argon is 30:10sccm, and depositing a first layer of h-BN film 2 on the substrate by taking a high-purity h-BN target material (99.99%) as a target source. Wherein the power of the sputtering target material is 400W, the sputtering working pressure is 0.5Pa, the target spacing is 100mm, and the vacuum degree is 5 multiplied by 10^-4Pa, sputtering time 1.5 h. The thickness of the first h-BN film 2 is 200 nm.

(2) After sputtering is finished, naturally cooling the growth substrate 1 to room temperature in vacuum, and waiting for 12 hours; and heating the chamber and the sample to 600 ℃, preserving the heat for 1h, filling mixed gas of nitrogen and argon into the chamber, wherein the gas flow ratio of the nitrogen to the argon is 30:10sccm, and depositing a second h-BN film 3 on the first h-BN film 2. Depositing a second layer of h-BN film 3 on the substrate, sputtering h-BN target with the power of 300W, the sputtering working pressure of 0.7Pa, the target spacing of 150mm and the vacuum degree of 5 multiplied by 10^-4Pa, sputtering time 2h, and the thickness of the second h-BN film 3 is 150nm, as shown in FIG. 1.

(4) and respectively transferring the three growth substrates 1 into liquids 4 (deionized water, 0.05mol/L KOH solution and 1mol/L KOH solution) in different containers 5, after 2 days (48 hours) of a sample in the deionized water, starting layering between a second layer of h-BN film 3 and a first layer of h-BN film 2, heating the deionized water with the sample for 20 minutes, partially peeling off the second layer of h-BN film 3, clamping the sample by tweezers, and slowly lifting the sample to the water surface along a separation position, wherein the second layer of h-BN film 3 floats to the water surface under the surface tension of water when passing through the water surface to form a layer of h-BN film. After the film is soaked in 0.05mol/L KOH solution for about 12 hours, the h-BN film begins to be layered, and finally the whole piece falls off and is suspended in the solution. After the film is soaked in 1mol/L KOH solution for about 3 hours, the h-BN film begins to be layered, and finally the whole piece falls off and is suspended in the solution. As shown in fig. 2.

Example 3:

a peeling and transferring method for preparing a hexagonal boron nitride film comprises the following steps:

(1)、cleaning a 0.5-inch silicon substrate and a 2-inch silicon substrate to form a growth substrate 1, putting the growth substrate 1 into a sputtering chamber, heating the chamber to 600 ℃, keeping the temperature for 1h, filling a mixed gas of nitrogen and argon into the chamber, wherein the gas flow ratio of the nitrogen to the argon is 30:10sccm, and depositing a first layer of h-BN film 2 on the substrate by taking a high-purity h-BN target (99.99%) as a target source. Wherein the power of the sputtering target material is 250W, the sputtering working pressure is 0.6Pa, the target spacing is 150mm, and the vacuum degree is 5 multiplied by 10^-4Pa, sputtering time 2 h. The thickness of the first h-BN film 2 is 150 nm.

(2) After sputtering is finished, naturally cooling the growth substrate 1 to room temperature in vacuum and waiting for 12 hours; and heating the chamber and the sample to 600 ℃, preserving the heat for 1h, filling mixed gas of nitrogen and argon into the chamber, wherein the gas flow ratio of the nitrogen to the argon is 30:10sccm, and depositing a second h-BN film 3 on the first h-BN film 2. The power for sputtering the h-BN target is 200W, the sputtering working pressure is 0.6Pa, the target spacing is 150mm, and the vacuum degree is 5 multiplied by 10^-4Pa, sputtering time 1.5h, and thickness of the second h-BN film 3 of 100nm, as shown in FIG. 1.

(4) and respectively transferring the two growth substrates 1 into a liquid 4(1mol/L KOH solution) in a 2-cup container 5, soaking a 0.5-inch silicon substrate in the 1mol/L KOH solution for about 3 hours, then starting to delaminate between the second layer of h-BN film 3 and the first layer of h-BN film 2, and finally, falling off the whole piece and suspending the whole piece into the solution. After a 2-inch silicon substrate is soaked in 1mol/L KOH solution for about 3.5 hours, the h-BN film begins to delaminate, and finally the whole piece falls off and is suspended in the solution. As shown in fig. 2.

(5) After the sapphire transfer substrate 6 was cleaned, oxygen (O) gas was used₂) The plasma bombards the surface for 120 s.

(6) The sapphire transfer substrate 6 is inserted into the water surface with the h-BN film along the direction of 45 degrees at the lower oblique direction and gradually approaches to the film floating on the water surface, when the sapphire transfer substrate contacts the h-BN film, the processed hydrophilic substrate adsorbs the film floating on the surface of the solution, and then the substrate is flatly placed and slowly separated from the water surface, as shown in figure 3.

(7) The transfer substrate 6 with the h-BN film is dried, and 0.5 inch and 2 inch transfer films can be obtained.

It will be appreciated by those skilled in the art that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The embodiments disclosed above are therefore to be considered in all respects as illustrative and not restrictive. All changes which come within the scope of or equivalence to the invention are intended to be embraced therein.

Claims

1. The preparation and stripping method of the hexagonal boron nitride film is characterized by comprising the following steps:

step 2), after the sputtering is finished to form the first layer of h-BN film (2), naturally cooling the growth substrate (1) to room temperature in vacuum; raising the temperature of the sputtering chamber to the sputtering temperature again, and depositing a second layer of h-BN film (3) on the first layer of h-BN film (2) by magnetron sputtering under a specific atmosphere;

step 3), after the second layer of h-BN film (3) is sputtered, the growth substrate (1) is naturally cooled to room temperature in vacuum and taken out;

step 4), transferring the growth substrate (1) into a container (5) with deionized water or alkaline solution for soaking, and enabling the second layer of h-BN film (3) to fall off from the first layer of h-BN film (2) to obtain a stripped second layer of h-BN film (3);

the specific atmosphere is a mixed gas of nitrogen and argon filled into the sputtering chamber, and the gas flow ratio of the nitrogen to the argon is 30:10 sccm.

2. The method for preparing and peeling the hexagonal boron nitride film according to claim 1, wherein the sputtering temperature in the step 1) is 600 ℃; the power of the sputtering target material is 250-400W during magnetron sputtering, and the sputtering work is carried outThe pressure is 0.5-0.7 Pa, the target spacing is 100-150 mm, and the vacuum degree is 5 × 10^-4Pa, the sputtering time is more than or equal to 1.5 h; the thickness of the first layer of h-BN film (2) is 150-200 nm; the thickness of the second h-BN film (3) is 100-200 nm.

3. The method for preparing and peeling the hexagonal boron nitride film according to claim 1, wherein the concentration of the alkaline solution in the step 4) is in a range of 0.05-1 mol/L.

4. The method for preparing and peeling off the hexagonal boron nitride film according to claim 1, wherein the soaking time in the step 4) is 3-48 hours.

5. The method for preparing and stripping the hexagonal boron nitride film according to claim 1, wherein after the first h-BN film (2) is sputtered, the growth substrate (1) is naturally cooled to room temperature in vacuum, after standing for 12 hours, the sputtering chamber is heated to the sputtering temperature again, and a second h-BN film (3) is deposited on the first h-BN film (2) by magnetron sputtering in a specific atmosphere.

6. The method for preparing and peeling a hexagonal boron nitride film according to claim 1, wherein the area of the peeled second h-BN film (3) is 0.5 to 2 inches.