CN102583331B - Large-area graphene preparation method based on Ni film-assisted annealing and Cl2 reaction - Google Patents

Abstract

The invention discloses a large-area graphene preparation method based on Ni film assisted annealing and _Cl2 reaction, which mainly solves the problems of small area and uneven layer number of graphene prepared in the prior art. (1) First grow a layer of carbonized layer on a 4-12 inch Si substrate as a transition; (2) Use gas sources C ₃ H ₈ and SiH ₄ to grow 3C-SiC epitaxy at a temperature of 1200°C-1300°C thin film; (3) react 3C-SiC with Cl ₂ at 700-1100°C to form a carbon film; (4) deposit a Ni film with a thickness of 300-500nm on the Si substrate by electron beam; (5) generate a carbon film The carbon surface of the sample is placed on the Ni film, and then they are placed together in Ar gas, and annealed at a temperature of 900-1100°C for 15-30min to form graphene. The graphene produced by the invention has large area, smooth surface, good continuity and low porosity, and can be used for sealing gas and liquid.

Description

Large-area graphene preparation method based on Ni film-assisted annealing and Cl2 reaction

technical field

The invention belongs to the technical field of microelectronics, and relates to a semiconductor film material and a preparation method thereof, in particular to a large-area graphene preparation method based on Ni film assisted annealing and _Cl reaction.

technical background

Graphene appeared in the laboratory in 2004. At that time, two scientists, Andre Gem and Kostya Novoselov, from the University of Manchester in the United Kingdom discovered that they could obtain more and more graphene in a very simple way. thinner and thinner graphite flakes. They peeled off the graphite flakes from the graphite, then glued the two sides of the flakes to a special adhesive tape, and when the tape was torn off, the graphite flakes could be split in two. Repeatedly doing this, the flakes got thinner and thinner, and eventually, they got a flake made of just one layer of carbon atoms, which is graphene. Since then, new methods of preparing graphene have emerged in an endless stream. There are two main methods of preparation:

1. The chemical vapor deposition method provides an effective method for the controllable preparation of graphene. It is to place a flat substrate, such as a metal film, a metal single crystal, etc., into a high-temperature decomposable precursor, such as methane, ethylene, etc. Carbon atoms are deposited on the substrate surface by high-temperature annealing to form graphene, and finally the metal substrate is removed by chemical etching to obtain an independent graphene sheet. The growth of graphene can be controlled by selecting the type of substrate, growth temperature, flow rate of precursor and other parameters, such as growth rate, thickness, area, etc. The biggest disadvantage of this method is that the obtained graphene sheet has a strong interaction with the substrate. , lost many of the properties of single-layer graphene, and the continuity of graphene is not very good.

2. Thermal decomposition SiC method: single crystal SiC is heated to remove Si by decomposing SiC on the surface, and then the remaining carbon forms graphene. However, the single crystal SiC used in the thermal decomposition of SiC is very expensive, and the grown graphene is distributed in an island shape, with uneven layers and small size, making it difficult to manufacture graphene in a large area.

Contents of the invention

The object of the invention is to address the deficiencies in the above-mentioned prior art, propose a kind of large-area graphene preparation method based on Ni film assisted annealing and _Cl reaction, to improve surface smoothness and continuity, reduce porosity, reduce cost, realize Large-area graphene fabrication on 3C-SiC substrates.

To achieve the above object, the preparation method of the present invention comprises the following steps:

(1) Carry out standard cleaning to the Si substrate substrate of 4-12 inches;

(2) Put the cleaned Si substrate into the reaction chamber of the CVD system, and evacuate the reaction chamber to a level of 10 ^-7 mbar;

(3) Gradually raise the temperature to the carbonization temperature of 900°C-1200°C under the protection of H ₂ , feed in C ₃ H ₈ with a flow rate of 30 sccm, carbonize the substrate for 5-10 min, and grow a carbonized layer;

(4) Rapidly raise the temperature to the growth temperature of 1200°C-1300°C, feed C ₃ H ₈ and SiH ₄ to grow the 3C-SiC heteroepitaxial film for _30-60 minutes, and then gradually cool down to At room temperature, complete the growth of 3C-SiC epitaxial film;

(5) Place the grown 3C-SiC sample in a quartz tube and heat to 700-1100°C;

(6) In the quartz tube, pass into the mixed gas of Ar gas and Cl _gas for 3-5min, so that _Cl reacts with 3C-SiC to generate a carbon film;

(7) Electron beam deposition of a 300-500nm thick Ni film on the Si substrate;

(8) Place the carbon surface of the generated carbon film sample on the Ni film, then place them together in Ar gas and anneal for 15-30 minutes at a temperature of 900-1100 ° C, the carbon film is reconstituted into graphene, and then The Ni film was removed from the graphene sample.

Compared with the prior art, the present invention has the following advantages:

1. In the present invention, when growing 3C-SiC, a carbide layer is first grown on the Si substrate as a transition, and then 3C-SiC is grown, so the quality of the grown 3C-SiC is high.

2. In the present invention, since 3C-SiC can be heteroepitaxially grown on Si wafers, and the size of Si wafers can reach 12 inches, large-area graphene can be grown by this method, and the price is cheap.

3. In the present invention, 3C-SiC and Cl ₂ can react at lower temperature and normal pressure, and the reaction rate is fast.

4. Since the present invention utilizes 3C-SiC to react with Cl ₂ gas, the resulting graphene has smooth surface, low porosity, and easy control of thickness, which can be used for sealing gas and liquid.

5. Since the present invention utilizes the annealing on the Ni film, the generated carbon film is more easily reconfigured to form graphene with better continuity.

Description of drawings

Fig. 1 is the device schematic diagram that the present invention prepares graphene;

Fig. 2 is the flowchart of preparing graphene of the present invention.

Detailed ways

Referring to Fig. 1, the preparation equipment of the present invention is mainly made up of quartz tube 1 and resistance furnace 2, wherein quartz tube 1 is provided with air inlet 3 and gas outlet 4, and resistance furnace is 2 ring-shaped hollow structures, and quartz tube 1 is inserted In the resistance furnace 2.

Referring to Fig. 2, the manufacturing method of the present invention provides the following three embodiments.

Example 1

Step 1: Remove sample surface contamination.

Clean the surface of the 4-inch Si substrate, that is, soak the sample with NH ₄ OH+H ₂ O ₂ reagent for 10 minutes, take it out and dry it to remove the organic residue on the surface of the sample; then use HCl+H ₂ Soak the sample in _O2 reagent for 10 minutes, take it out and dry it to remove ionic contaminants.

Step 2: Put the Si substrate into the reaction chamber of the CVD system, and evacuate the reaction chamber to a level of 10 ^-7 mbar.

Step 3: growing the carbonized layer.

Under the protection of H ₂ , the temperature of the reaction chamber was raised to the carbonization temperature of 900° C., and then C ₃ H ₈ with a flow rate of 30 sccm was introduced into the reaction chamber to grow a carbonized layer on the Si substrate for 10 minutes.

Step 4: growing a 3C-SiC epitaxial film on the carbonized layer.

Rapidly raise the temperature of the reaction chamber to the growth temperature of 1200°C, and feed SiH ₄ and C ₃ H ₈ at flow rates of 20sccm and 40sccm, respectively, to grow the 3C-SiC heteroepitaxial film for ₆₀ minutes; Gradually lower the temperature to room temperature to complete the growth of 3C-SiC epitaxial film.

Step 5: Put the 3C-SiC sample into the quartz tube and heat it with exhaust gas.

(5.1) Take out the grown 3C-SiC epitaxial film sample from the CVD system reaction chamber and place it in the quartz tube 5, and place the quartz tube in the resistance furnace 2;

(5.2) Pass into the Ar gas that flow velocity is 80sccm in the quartz tube from inlet 3, the quartz tube is evacuated for 10 minutes, and gas is discharged from gas outlet 4;

(5.3) Turn on the power switch of the resistance furnace, raise the temperature to 700°C, and heat the quartz tube in it to 700°C.

Step 6: Generate carbon film

Flow rates of 98sccm and 2sccm Ar gas and Cl ₂ gas into the quartz tube respectively for 5 minutes to make Cl ₂ react with 3C-SiC to form a carbon film.

Step 7: Take another Si substrate sample and place it on the substrate glass slide in the electron beam evaporation coating machine. The distance from the substrate to the target is 50 cm. Pump the pressure of the reaction chamber to 5×10 ^-4 Pa, and adjust the beam current to 40mA, evaporated for 10min, and deposited a layer of Ni film with a thickness of 300nm on the Si substrate sample.

Step 8: Reconstruct into graphene.

(7.1) The carbon film sample piece that will generate is taken out from the quartz tube, and its carbon surface is placed on the Ni film;

(7.2) Place the carbon film sample and the Ni film as a whole in Ar gas with a flow rate of 90 sccm, anneal for 15 minutes at a temperature of 1100 ° C, and restructure the carbon film into continuous graphene through the catalytic action of metal Ni;

(7.3) Remove the Ni film from the graphene sample.

Example 2

Step 1: Remove sample surface pollutants.

Clean the surface of the 8-inch Si substrate substrate, that is, soak the sample with NH ₄ OH+H ₂ O ₂ reagent for 10 minutes, take it out and dry it to remove the organic residue on the surface of the sample; then use HCl+H ₂ Soak the sample in _O2 reagent for 10 minutes, take it out and dry it to remove ionic contaminants.

Step 2: Put the Si substrate into the reaction chamber of the CVD system, and evacuate the reaction chamber to a level of 10 ^-7 mbar.

Step 3: growing a carbonized layer.

Under the protection of H ₂ , the temperature of the reaction chamber was raised to the carbonization temperature of 1050° C., and then C ₃ H ₈ with a flow rate of 30 sccm was introduced into the reaction chamber to grow a carbonized layer on the Si substrate for 7 minutes.

Step 4: growing a 3C-SiC epitaxial film on the carbonized layer.

Rapidly raise the temperature of the reaction chamber to the growth temperature of 1200°C, and feed SiH ₄ and C ₃ H ₈ at flow rates of 25 sccm and 50 sccm respectively to grow the 3C-SiC heteroepitaxial film for ₄₅ minutes; Gradually lower the temperature to room temperature to complete the growth of 3C-SiC epitaxial film.

Step 5: Put the 3C-SiC sample into the quartz tube, and exhaust and heat it.

The grown 3C-SiC epitaxial film sample is taken out from the CVD system reaction chamber and placed in the quartz tube 5, and the quartz tube is placed in the resistance furnace 2; Gas, the quartz tube is evacuated for 10 minutes, and the gas is discharged from the gas outlet 4; then the power switch of the resistance furnace is turned on, and the temperature is raised to 1000°C, so that the quartz tube inside is also heated to 1000°C.

Step 6: Generate carbon film

Ar gas and Cl ₂ gas with flow rates of 97 sccm and 3 sccm were passed into the quartz tube for 4 minutes, so that Cl ₂ reacted with 3C-SiC to form a carbon film.

Step 7: Take another Si substrate sample and place it on the substrate glass slide in the electron beam evaporation coating machine. The distance from the substrate to the target is 50 cm. The pressure of the reaction chamber is pumped to 5×10 ^-4 Pa, and the beam current is adjusted to 40mA, evaporated for 15min, and deposited a layer of Ni film with a thickness of 400nm on the Si substrate sample.

Step 8: Reconstitute graphene.

The generated carbon film sample is taken out from the quartz tube, and its carbon surface is placed on the Ni film; the carbon film sample and the Ni film are placed in an Ar gas with a flow rate of 55 sccm, and annealed at a temperature of 1000 ° C for 20 minutes. The carbon film is restructured into continuous graphene through the catalysis of metal Ni; the Ni film is removed from the graphene sample.

Example 3

Step A: Clean the surface of the 12-inch Si substrate, that is, soak the sample with NH ₄ OH + H ₂ O ₂ reagent for 10 minutes, take it out and dry it to remove the organic residue on the surface of the sample; then use HCl +H ₂ O ₂ reagent to soak the sample for 10 minutes, take it out and dry it to remove ionic pollutants.

Step B: Put the Si substrate into the reaction chamber of the CVD system, and evacuate the reaction chamber to a level of 10 ^-7 mbar.

Step C: Under the protection of H ₂ , the temperature of the reaction chamber is raised to the carbonization temperature of 1200°C, and then C ₃ H ₈ with a flow rate of 30 sccm is introduced into the reaction chamber for 5 minutes to grow a carbonized layer on the Si substrate .

Step D: Rapidly raise the temperature of the reaction chamber to the growth temperature of 1300°C, feed in SiH ₄ and C ₃ H ₈ with flow rates of 30 sccm and 60 sccm respectively, and grow the 3C-SiC heteroepitaxial film for 30 minutes; then, under the protection of H ₂ Gradually cool down to room temperature.

Step E: Take out the grown 3C-SiC epitaxial film sample from the CVD system reaction chamber and place it in the quartz tube 5, and place the quartz tube in the resistance furnace 2; 80 sccm of Ar gas, the quartz tube is evacuated for 10 minutes, and the gas is discharged from the gas outlet 4; then the power switch of the resistance furnace is turned on, and the temperature is raised to 1100 ° C, so that the quartz tube inside is also heated to 1100 ° C.

Step F: Introduce Ar gas and Cl ₂ gas at flow rates of 95 sccm and 5 sccm respectively into the quartz tube for 3 minutes, so that Cl ₂ reacts with 3C-SiC to form a carbon film.

Step G: Take another Si substrate sample and place it on the substrate glass slide in the electron beam evaporation coating machine. The distance from the substrate to the target is 50 cm. The pressure of the reaction chamber is pumped to 5×10 ^-4 Pa, and the beam current is adjusted to 40mA, evaporated for 20min, and deposited a layer of Ni film with a thickness of 500nm on the Si substrate sample.

Step H: Take out the generated carbon film sample from the quartz tube, place its carbon surface on the Ni film; place the carbon film sample and the Ni film as a whole in Ar gas with a flow rate of 30 sccm, and anneal at a temperature of 900°C In 30 minutes, the carbon film was restructured into continuous graphene through the catalysis of metal Ni; the Ni film was removed from the graphene sample.

Claims (5)

1. A method for preparing large-area graphene based on Ni film assisted annealing and _Cl reaction, characterized in that the preparation method may further comprise the steps: (1) Perform standard cleaning on 4-12 inch Si substrate substrates, that is, first soak the sample with NH ₄ OH+H ₂ O ₂ reagent for 10 minutes, take it out and dry it to remove the organic residue on the surface of the sample; then use Soak the sample in HCl+H ₂ O ₂ reagent for 10 minutes, take it out and dry it to remove ionic pollutants; (2) Put the cleaned Si substrate into the reaction chamber of the CVD system, and evacuate the reaction chamber to a level of 10 ^-7 mbar; (3) Gradually raise the temperature to the carbonization temperature of 900°C-1200°C under the protection of H ₂ , feed in C ₃ H ₈ with a flow rate of 30 sccm, carbonize the substrate for 5-10 min, and grow a layer of carbonization; (4) Rapidly raise the temperature to the growth temperature of 1200°C-1300°C, feed C ₃ H ₈ and SiH ₄ to grow the 3C-SiC heteroepitaxial film for _30-60 minutes, and then gradually cool down to At room temperature, complete the growth of 3C-SiC epitaxial film; (5) Place the grown 3C-SiC sample in a quartz tube and heat it to 700-1100°C; (6) Pass a mixed gas of Ar gas and Cl ₂ gas into the quartz tube for 3-5 minutes to make Cl ₂ react with 3C-SiC to form a carbon film; (7) Electron beam deposition of 300-500nm thick Ni film on the Si substrate; (8) Place the carbon surface of the generated carbon film sample on the Ni film, then place them together in Ar gas and anneal at a temperature of 900-1100°C for 15-30 minutes, the carbon film is reconstituted into graphene, and then The Ni film was removed from the graphene sample. 2. The large-area graphene preparation method based on Ni film assisted annealing and Cl ₂ reaction according to claim 1, characterized in that the flow rates of SiH ₄ and C ₃ H ₈ introduced in step (4) are respectively 20-30sccm and 40-60sccm. 3. The large-area graphene preparation method based on Ni film assisted annealing and _Cl2 reaction according to claim 1, characterized in that the Ar gas and _Cl2 gas introduced in step (6) have a flow rate of 95 -98 sccm and 5-2 sccm. 4. The large-area graphene preparation method based on Ni film-assisted annealing and Cl _reaction according to claim 1, characterized in that the condition of electron beam deposition in the step (7) is that the distance from the substrate to the target is 50cm , the pressure of the reaction chamber is 5×10 ^-4 Pa, the beam current is 40mA, and the evaporation time is 10-20min. 5. The large-area graphene preparation method based on Ni film assisted annealing and Cl ₂ reaction according to claim 1, characterized in that the flow rate of Ar gas during the annealing in the step (8) is 30-90 sccm.

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