Method for controllable growth of upright graphene
By performing plasma etching and RF-PECVD treatment on nickel-plated silicon wafers and controlling the gas pressure and flow rate in stages, controllable growth of upright graphene was achieved, solving the problems of long growth time and large defects in existing technologies, and improving growth efficiency and uniformity.
Patent Information
- Application Number
- CN202511149093.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-15
- Publication Date
- 2025-11-21
AI Technical Summary
Existing vertical graphene growth processes are time-consuming, have low nucleation and carbon diffusion efficiency, and are prone to oxidation of the substrate surface, resulting in significant product defects and difficulty in controlling structural uniformity.
By plasma etching a nickel-plated silicon wafer to form uniformly distributed nano-pits and protrusions, combined with gradient heating and bias application of the RF-PECVD device, the chamber gas pressure and carbon source gas flow rate are controlled to achieve high-speed nucleation, high-speed growth and stable growth in stages, thereby optimizing carbon source adsorption and electric field distribution.
It significantly improved the growth efficiency of upright graphene, reduced the defect rate, shortened the growth time, and improved the uniformity of the structure.
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Figure CN120987306A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of graphene preparation, and particularly relates to a method for controllable growth of vertical graphene. BACKGROUND
[0002] Graphene has a wide range of applications in biomedical, energy storage, electronic devices and many other fields due to its excellent mechanical properties, thermal and electrical conductivity and large specific surface area. Vertical graphene is a three-dimensional graphene structure grown vertically on a substrate, and has a specific surface area of 2600 m 2 / g, which is more than 5 times that of planar graphene, and a vertical electrical conductivity of 10 4 S / m, which is 10 times that of planar graphene. The vertical structure exposes a large number of sheet edges, so the catalytic activity of vertical graphene is 5-10 times that of planar graphene. Therefore, the application prospect of vertical graphene is more extensive than that of planar graphene.
[0003] At present, vertical graphene is usually grown by plasma-enhanced chemical vapor deposition, and the commonly used substrates include nickel, titanium and quartz. The conventional growth process is time-consuming. Meanwhile, the nucleation efficiency and carbon diffusion efficiency of these substrates are low. In addition, oxidation films are easily formed on the surfaces of nickel and titanium substrates, resulting in passivation effect. The existing process for growing vertical graphene is time-consuming (for example, it takes 2 hours to grow a four-inch 3-micron-thick vertical graphene wafer), and the product has many defects and the structure uniformity is difficult to control. Therefore, there is an urgent need to provide a process for controllable growth of vertical graphene and shortening the growth time of vertical graphene. SUMMARY
[0004] The main purpose of the present application is to provide a method for controllable growth of vertical graphene to overcome the shortcomings of the prior art.
[0005] To achieve the above-mentioned purposes, the technical solutions adopted by the present application include:
[0006] The present application provides a method for controllable growth of vertical graphene, which comprises:
[0007] The nickel-plated silicon wafer is subjected to plasma etching treatment to form uniformly distributed nano-pits and nano-bumps on the surface of the nickel-plated silicon wafer, thereby obtaining a pretreated nickel-plated silicon wafer;
[0008] The pretreated nickel-plated silicon wafer is placed in an RF-PECVD device and heated to 580-620℃ by gradient heating, and then a bias voltage is applied to the pretreated nickel-plated silicon wafer. Subsequently, the first stage of high-speed nucleation, the second stage of graphene high-speed growth and the third stage of stable growth are carried out in sequence by controlling the cavity pressure and the flow rates of carbon source gas and hydrogen, thereby realizing the controllable growth of vertical graphene.
[0009] Compared with the prior art, the present application has the advantages of:
[0010] (1) The process for controllable growth of vertical graphene provided by the present application can greatly improve the growth efficiency of vertical graphene, and the growth time of a 4-inch vertical graphene wafer is reduced from 2h to 1h.
[0011] (2) The process for controllable growth of vertical graphene provided by the present application greatly reduces the defect rate of vertical graphene. BRIEF DESCRIPTION OF DRAWINGS
[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative labor.
[0013] Figure 1 is a scanning electron microscope picture of vertical graphene prepared in a typical embodiment of the present application;
[0014] Figure 2 is a Raman spectrum of vertical graphene prepared in Example 1 and Comparative Example 1 of the present application;
[0015] Figure 3 is an AFM test data graph of the surface of a nickel-plated silicon wafer before growing graphene in Example 1 and Comparative Example 2 of the present application. DETAILED DESCRIPTION
[0016] In view of the defects of the prior art, the present inventors have obtained the technical solutions of the present application through long-term research and a large number of practices. The technical solutions of the present application will be described clearly and completely below. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.
[0017] Specifically, as one aspect of the technical solutions of the present application, a method for controllable growth of vertical graphene comprises:
[0018] The nickel-plated silicon wafer is subjected to plasma etching treatment, so that at least a uniform distribution of nano-pits and nano-bumps is formed on the surface of the nickel-plated silicon wafer, and a pretreated nickel-plated silicon wafer is obtained;
[0019] And, the pretreated nickel-plated silicon wafer is placed in an RF-PECVD device and heated to 580-620 DEG C at a gradient, then a bias voltage is applied to the pretreated nickel-plated silicon wafer, and then the first stage high-speed nucleation, the second stage high-speed growth of graphene and the third stage stable growth are sequentially performed by controlling the cavity gas pressure and the flow rates of carbon source gas and hydrogen, so that the controllable growth of upright graphene is realized.
[0020] In some preferred embodiments, the method specifically comprises: placing the nickel-plated silicon wafer in a plasma etching device for plasma etching treatment; wherein the vacuum pressure in the cavity of the plasma etching device is 1-10 Pa, the argon flow rate is 20-50 sccm, the radio frequency power is 150-200 W, the substrate temperature is 40-60 DEG C, and the etching time is 10-15 min.
[0021] Further, the purity of the argon is ≥ 99.999 %.
[0022] The present application forms uniform distribution of nano pits on the nickel surface by substrate pretreatment and ion beam etching, and reduces the carbon atom diffusion barrier at the step of the pit edge. In addition, the surface roughness is improved, the specific surface area is expanded by 10-20 times, the carbon source adsorption capacity is enhanced, the nano convex tip will gather the electric field, and the vertical electrostatic force is strengthened. The ion etching removes 2-3 nm NiO on the surface of Ni, and the carbon atoms directly contact the high-activity nickel surface. The nano pits can optimize the carbon dissolution-precipitation path, reduce the carbon penetration depth, and accelerate the precipitation rate.
[0023] In some preferred embodiments, the method specifically comprises: placing the pretreated nickel-plated silicon wafer in an RF-PECVD device and setting the vacuum degree in the cavity to 10 -1 -10 -2 Pa, first heating to 280-320 DEG C at a heating rate of 20-25 DEG C / min, and then heating to 580-620 DEG C at a heating rate of 10-15 DEG C.
[0024] In some preferred embodiments, the method specifically comprises: after the end of heating, applying a bias voltage of -100 V to -150 V to the pretreated nickel-plated silicon wafer. The present application uses an adjustable bias voltage device to increase the driving force for vertical growth of graphene by applying a bias voltage to the substrate.
[0025] In some preferred embodiments, the process parameters used in the first stage high-speed nucleation include: the pressure in the cavity of the RF-PECVD device is 1-10 Pa, the flow rate of the carbon source gas is 20-29 sccm, the flow rate of hydrogen is 60-90 sccm, the radio frequency power is 450-500 W, and the time duration is 100-120 s.
[0026] In some preferred embodiments, the process parameters used in the second stage of high-speed growth of graphene include: a pressure of 0.1-0.5 Pa in the chamber of the RF-PECVD device, a flow rate of the carbon source gas of 30-40 sccm, a flow rate of hydrogen of 120-160 sccm, a radio frequency power of 900-1100 W, and a time duration of 18-22 min.
[0027] In some preferred embodiments, the process parameters used in the third stage of stable growth of graphene include: a pressure of 10 -2 -10 -1 Pa in the chamber of the RF-PECVD device, a flow rate of the carbon source gas of 5-10 sccm, a flow rate of hydrogen of 5-10 sccm, a radio frequency power of 900-1100 W, and a time duration of 100-120 s.
[0028] The present application can meet the optimal requirements of the flow rate in different stages of the growth of the upright graphene by automatically regulating the flow rate and dynamically controlling the flow rate in different stages of the growth, improve the nucleation efficiency, and can ensure high-speed nucleation in the early stage, high-speed growth in the middle stage, and reduction of defects in the later stage.
[0029] In some preferred embodiments, the carbon source gas includes any one or a combination of more than one of methane, ethylene, and argon-ethanol vapor mixed gas, and is not limited thereto.
[0030] In some preferred embodiments, the method further includes: cleaning the silicon wafer with water first, and then performing ultrasonic cleaning with alcohol, and drying treatment; wherein the power used in the ultrasonic cleaning is 300-500 W, and the time is 20-25 min.
[0031] In some preferred embodiments, the method further includes: forming a nickel-plated silicon wafer by plating nickel on the surface of the silicon wafer using a radio frequency physical vapor deposition technique, and then performing acid soaking and water washing treatment on the nickel-plated silicon wafer; wherein the radio frequency power used in the radio frequency physical vapor deposition technique is 300-500 W, and the nickel plating time is 15-20 min.
[0032] In some more specific embodiments, the method for controllably growing upright graphene includes the following steps:
[0033] 1. Clean a 4-inch silicon wafer with a 111 crystal lattice with pure water, and then perform ultrasonic cleaning with alcohol, with a power of 300-500 W, for 20-25 min, and finally dry.
[0034] 2. Then, plate a 1 μm-thick Ni layer on the surface of the silicon wafer using a radio frequency physical vapor deposition technique, with a radio frequency power of 300-500 W, and a plating time of 15-20 min.
[0035] 3. The nickel-plated silicon wafer is immersed in 10% hydrochloric acid for 5-10 minutes to remove the surface NiO, and then washed with pure water for 5-10 minutes.
[0036] 4. The cleaned nickel-plated silicon wafer is placed in a plasma etching machine, with a vacuum pressure of 1-10 Pa, argon purity of 99.999%, argon flow rate of 20-50 sccm, radio frequency power of 150-200 W, substrate temperature set to 40-60°C, and etching time of 10-15 minutes.
[0037] 5. The growth of vertical graphene on the nickel-plated silicon wafer is carried out using RF-PECVD, with a vacuum degree of 10 -1 -10 - 2 Pa, using gradient heating, first heating at a rate of 20-25°C / min to 300°C within 12-15 minutes, and then heating at a rate of 10-15°C / min to 600°C within 20-30 minutes.
[0038] 6. After the temperature is raised, the bottom bias is set to -100V-150V.
[0039] 7. The growth of vertical graphene uses dynamic pressure and flow control, the first stage controls the pressure in the chamber to be 1-10 Pa, the methane flow rate is 20-30 sccm, the hydrogen flow rate is 60-90 sccm, the ratio of methane and hydrogen flow is maintained at 1:3, the radio frequency power is 500 W, and the time lasts for 2 minutes, the second stage controls the pressure to be between 0.1-0.5 Pa, the radio frequency power is 1 kW, the methane flow rate is 30-40 sccm, the hydrogen flow rate is 120-160 sccm, the ratio of methane and hydrogen flow is maintained at 1:4, and the time lasts for 20 minutes, the third stage controls the pressure to be 10 -2 -10 -1 Pa, the methane flow rate is 5-10 sccm, the hydrogen flow rate is 5-10 sccm, the ratio of methane and hydrogen flow is maintained at 1:1, and the time lasts for 2 minutes.
[0040] The technical solutions of the present application will be further described in detail below in conjunction with several preferred embodiments and the accompanying drawings. The present embodiments are implemented on the premise of the technical solutions of the present application, and detailed implementation methods and specific operation processes are given, but the protection scope of the present application is not limited to the following embodiments.
[0041] The experimental materials used in the following examples are commercially available from conventional biochemical reagent companies unless otherwise specified.
[0042] Example 1
[0043] 1. First, clean the 4-inch lattice 111 silicon wafer with pure water, then perform ultrasonic cleaning with alcohol, power 300W, clean for 20min, and finally dry;
[0044] 2. Then, deposit a 1 μm thick nickel layer on the surface of the silicon wafer to form a nickel-plated silicon wafer, wherein radio frequency physical vapor deposition is used, the radio frequency power is 300W, and the film deposition time is 15min;
[0045] 3. Soak the nickel-plated silicon wafer in 10% hydrochloric acid for 5min to remove the surface NiO, and then rinse with pure water for 5min;
[0046] 4. Put the cleaned nickel-plated silicon wafer into a plasma etching machine, the vacuum pressure is 1Pa, the argon purity is 99.999%, the argon flow is 20sccm, the radio frequency power is 150W, the substrate temperature is set to 40℃, and the etching time is 10min;
[0047] 5. Use RF-PECVD to grow vertical graphene on the nickel-plated silicon wafer, and use gradient heating, first heat at a rate of 20℃ / min to 300℃, then heat at a rate of 10℃ to 600℃;
[0048] 6. After the temperature rises, set the bottom bias to -100V;
[0049] 7. The vertical graphene growth process uses dynamic pressure and flow control, the first stage controls the pressure in the chamber to be 1Pa, the methane flow rate is 20sccm, the hydrogen flow rate is 60sccm, the radio frequency power is 500W, and the time lasts for 2min, the second stage controls the pressure to be between 0.1Pa, the radio frequency power is 1kW, the methane flow rate is 30sccm, the hydrogen flow rate is 120sccm, and the time lasts for 20min, the third stage controls the pressure to be 10 -2 Pa, methane flow rate 5sccm, hydrogen flow rate 5sccm, time lasts for 2min.
[0050] Example 2
[0051] 1. First, clean the 4-inch lattice 111 silicon wafer with pure water, then perform ultrasonic cleaning with alcohol, power 500W, clean for 25min, and finally dry;
[0052] 2. Then, deposit a 1 μm thick nickel layer on the surface of the silicon wafer to form a nickel-plated silicon wafer, wherein radio frequency physical vapor deposition is used, the radio frequency power is 500W, and the film deposition time is 20min;
[0053] 3. Soak the nickel-plated silicon wafer in 10% hydrochloric acid for 10min to remove the surface NiO, and then rinse with pure water for 10min;
[0054] 4. The cleaned nickel-plated silicon wafer is placed in a plasma etching machine with a vacuum pressure of 10 Pa, argon purity of 99.999%, argon flow rate of 50 sccm, radio frequency power of 200 W, and a substrate temperature setting of 60°C, and etching is performed for 15 min;
[0055] 5. The growth of vertical graphene on the nickel-plated silicon wafer is performed using RF-PECVD with gradient heating, first heating at a rate of 25°C / min to 320°C, and then heating at a rate of 15°C / min to 620°C;
[0056] 6. After the heating is completed, a bottom bias of -150 V is set;
[0057] 7. The growth of vertical graphene is performed using dynamic pressure and flow control, the first stage controls the pressure in the chamber to be 10 Pa, the methane flow rate is 29 sccm, the hydrogen flow rate is 87 sccm, the radio frequency power is 500 W, and the time lasts for 2 min, the second stage controls the pressure to be between 0.5 Pa, the radio frequency power is 1 kW, the methane flow rate is 40 sccm, the hydrogen flow rate is 160 sccm, and the time lasts for 20 min, the third stage controls the pressure to be 10 -1 Pa, the methane flow rate is 10 sccm, the hydrogen flow rate is 10 sccm, and the time lasts for 2 min.
[0058] Example 3
[0059] 1. The 4-inch silicon wafer with a 111 crystal lattice is first cleaned with pure water, and then ultrasonic cleaning is performed with alcohol, the power is 400 W, the cleaning time is 23 min, and finally drying is performed;
[0060] 2. Then a layer of 1 μm thick nickel layer is plated on the surface of the silicon wafer to form a nickel-plated silicon wafer, wherein radio frequency physical vapor deposition is used, the radio frequency power is 400 W, and the plating time is 18 min;
[0061] 3. The nickel-plated silicon wafer is immersed in 10% hydrochloric acid for 10 min to remove the surface NiO, and then washed with pure water for 10 min;
[0062] 4. The cleaned nickel-plated silicon wafer is placed in a plasma etching machine with a vacuum pressure of 5 Pa, argon purity of 99.999%, argon flow rate of 30 sccm, radio frequency power of 180 W, and a substrate temperature setting of 50°C, and etching is performed for 13 min;
[0063] 5. The growth of vertical graphene on the nickel-plated silicon wafer is performed using RF-PECVD with gradient heating, first heating at a rate of 22°C / min to 280°C, and then heating at a rate of 12°C / min to 580°C;
[0064] 6. After the temperature is raised, the bottom bias is set to -130V;
[0065] 7. The vertical graphene growth process adopts dynamic pressure and flow control. In the first stage, the pressure in the chamber is controlled to be 5 Pa, the methane flow rate is 25 sccm, the hydrogen flow rate is 75 sccm, the radio frequency power is 480 W, and the time duration is 110 s. In the second stage, the pressure is controlled to be between 0.3 Pa, the radio frequency power is 1.1 kW, the methane flow rate is 35 sccm, the hydrogen flow rate is 140 sccm, and the time duration is 22 min. In the third stage, the pressure is controlled to be 5*10 -1 Pa, the methane flow rate is 8 sccm, the hydrogen flow rate is 8 sccm, and the time duration is 110 s.
[0066] Comparative Example 1
[0067] The method is the same as that in Example 1, except that the pressure during the whole graphene growth process is 10 -1 Pa, and the temperature is raised to 600°C at a rate of 25°C / min in step 5.
[0068] Figure 2 Raman spectra of the graphene prepared in Example 1 and Comparative Example 1, wherein a is the Raman spectrum of the graphene prepared in Example 1, and b is the Raman spectrum of the graphene prepared in Comparative Example 1. It can be seen that the Raman G / D in Example 1 is 1.59, and the Raman G / D in Comparative Example 1 is 1.04, indicating that the flow control and gradient temperature rise significantly increase the G / D ratio of the graphene, and the defects are significantly reduced.
[0069] Comparative Example 2
[0070] The method is the same as that in Example 1, except that the plasma treatment is absent.
[0071] The nickel-plated silicon wafer before graphene growth in Example 1 and Comparative Example 1 was subjected to AFM testing, as shown in FIG. 2, wherein a is the AFM testing data of the nickel-plated silicon wafer after plasma etching in Example 1, and b is the AFM testing data of the nickel-plated silicon wafer without plasma etching in Comparative Example 2, indicating that after plasma etching, the surface roughness of the nickel-plated silicon wafer is significantly increased, and a large number of nano pits are formed. Figure 3
[0072] In addition, the inventors of the present case also refer to the foregoing examples, and conduct tests with other raw materials, process operations, and process conditions described in the specification, and all obtain relatively ideal results.
[0073] It should be understood that the technical solutions of the present application are not limited to the specific implementation cases described above, and any technical modification made according to the technical solutions of the present application without departing from the purpose of the present application and the scope protected by the claims falls within the protection scope of the present application.
Claims
1. A method for controllable growth of upright graphene, characterized in that, include: The nickel-plated silicon wafer is subjected to plasma etching treatment to form at least uniformly distributed nano-pits and nano-protrusions on the surface of the nickel-plated silicon wafer, thereby obtaining a pretreated nickel-plated silicon wafer. Furthermore, the pretreated nickel-plated silicon wafer is placed in an RF-PECVD device and heated to 580-620°C using a gradient temperature rise. Then, a bias voltage is applied to the pretreated nickel-plated silicon wafer, and the first stage of high-speed nucleation, the second stage of high-speed graphene growth, and the third stage of stable growth are carried out by controlling the chamber gas pressure, carbon source gas flow rate, and hydrogen flow rate in sequence, thereby achieving the controllable growth of upright graphene.
2. The method according to claim 1, characterized in that, Specifically, it includes: The nickel-plated silicon wafer is placed in a plasma etching apparatus for plasma etching treatment; wherein the vacuum pressure in the plasma etching apparatus chamber is 1-10 Pa, the argon flow rate is 20-50 sccm, the radio frequency power is 150-200 W, the substrate temperature is 40-60℃, and the etching time is 10-15 min.
3. The method according to claim 1, characterized in that, Specifically, it includes: The pretreated nickel-plated silicon wafer was placed in an RF-PECVD apparatus and the vacuum level in the chamber was set to 10. 1- 10 -2 Pa, first heat to 280-320℃ at a heating rate of 20-25℃ / min, then heat to 580-620℃ at a heating rate of 10-15℃.
4. The method according to claim 1, characterized in that, Specifically, it includes: After the heating is complete, a bias voltage of -100V to -150V is applied to the pretreated nickel-plated silicon wafer.
5. The method according to claim 1, characterized in that, The process parameters used in the first stage of high-speed nucleation include: a chamber pressure of 1-10 Pa in the RF-PECVD device, a carbon source gas flow rate of 20-29 sccm, a hydrogen flow rate of 60-90 sccm, a radio frequency power of 450-500 W, and a duration of 100-120 s.
6. The method according to claim 5, characterized in that, The process parameters used in the second stage of high-speed graphene growth include: a chamber pressure of 0.1-0.5 Pa in the RF-PECVD device, a carbon source gas flow rate of 30-40 sccm, a hydrogen flow rate of 120-160 sccm, an RF power of 900-1100 W, and a duration of 18-22 min.
7. The method according to claim 6, characterized in that, The process parameters used during the third stage of stable growth include: a chamber pressure of 10 kJ / m² in the RF-PECVD device. -2 -10 -1 Pa, carbon source gas flow rate of 5-10 sccm, hydrogen flow rate of 5-10 sccm, radio frequency power of 900-1100W, duration of 100-120s.
8. The method according to claim 1, characterized in that: The carbon source gas includes any one or more combinations of methane, ethylene, and argon-ethanol vapor mixture.
9. The method according to any one of claims 1-8, characterized in that, Also includes: First, the silicon wafer is cleaned with water, and then ultrasonically cleaned and dried with alcohol; wherein the ultrasonic cleaning uses a power of 300-500W and a time of 20-25min.
10. The method according to claim 9, characterized in that, Also includes: Nickel-plated silicon wafers are formed by plating nickel on the surface of silicon wafers using radio frequency physical vapor deposition (RF Physical Vapor Deposition) technology. The nickel-plated silicon wafers are then subjected to acid immersion and water washing treatment. The RF power used in the RF Physical Vapor Deposition technology is 300-500W, and the nickel plating time is 15-20 minutes.