CN102212794A - Copper plating substrate-based method for preparing large-area graphene film - Google Patents

Abstract

The invention relates to a method for preparing graphene on a copper plating substrate. The method is characterized by comprising the following steps of: preparing the graphical copper plating substrate on a silicon chip; and growing the graphene on the copper plating substrate for 2 to 5 minutes at the temperature of between 800 and 1,000 DEG C by using a normal pressure chemical vapor deposition method, using methane as a carbon source and using argon and hydrogen as carrier gases. A graphical graphene film can be directly prepared by the method, and the substrate can be compatible with an integrated circuit (IC) process; and the manufacturing method is simple and low in cost, and can be used for large-scale manufacture.

Description

A method for preparing large-area graphene films based on electroplated copper substrates

technical field

The invention relates to a method capable of producing graphene films on a large scale, more specifically to a method for preparing large-area graphene films based on an electroplated copper substrate, and belongs to the field of graphene film preparation.

Background technique

Graphene, that is, single-layer graphite, is a substance in which carbon atoms are arranged in a honeycomb structure on a plane. It was once considered a purely theoretical material because it was believed to be unstable. However, in 2004, after Geim et al. discovered the independent graphene, some experimental work successively verified that the carriers in graphene are Dirac fermions without static mass. Since then, graphene research boom has begun.

At present, graphene has been proven to have good application prospects in nanoelectronic devices, single-electron transistors, thermoelectric aspects, and conductive films. However, how to prepare high-quality and large-area graphene films on a large scale is still a difficult problem. At present, the methods for growing graphene mainly include: mechanical exfoliation method, the obtained graphene is of high quality but the area is small, and the efficiency is also very low; redox method, the operation is simple and the cost is low, but graphene will cause the loss of some physical and chemical properties during the redox process, and the obtained graphene area is also small; the silicon carbide cracking method can obtain large-area graphene, but graphite The quality of graphene is greatly affected by the substrate, and the growth cost is also high, requiring a high-temperature vacuum environment; chemical vapor deposition is suitable for large-scale preparation of graphene, but it is relatively constrained by the metal substrate.

At present, the metal substrates commonly used in chemical vapor deposition methods include Cu, Ni, Ru, etc. For Cu substrates, there are mainly two types of sputtered copper or copper foil on silicon wafers, but these two Cu substrates are in There are certain defects in the preparation process: the sputtered copper is easy to condense into island-shaped particles at high temperature, and the area of the prepared graphene is too small; the copper foil is easy to bend and wrinkle during the operation process, which affects the quality of the substrate. Flatness.

The present invention intends to propose a graphene growth method based on an electroplated copper substrate, which is compatible with the IC process and has high preparation efficiency, which solves the problems of difficulty in patterning, fragile substrates, and small area in the previous graphene preparation process.

Contents of the invention

The invention relates to a method for preparing large-area graphene based on an electroplated copper substrate. The provided method first includes a patterned electroplating fabrication that can be used to grow graphene. Specifically, the method for preparing large-area graphene based on an electroplated copper substrate provided by the present invention includes the following two methods:

Method A: The steps are

1. Preparation of electroplating copper seed layer: sputter 50-250nm metal seed layer on _SiO2 substrate or directly on silicon substrate, the material of seed layer can be Cu, Ni/Cu, Au, Cr/Au, TiW/Cu wait;

2. Imaging of the seed layer: according to the thickness of the required copper plating, the seed layer is coated with thick glue, the thickness of which is 4-12 μm, and then photolithographically etched into the pattern required for the subsequent growth of graphene;

3. Electroplating copper: according to the thickness of electroplating copper (2-10μm), choose different electroplating current (0.5-2.5A) and electroplating time (10-100min);

4. Degumming, corrosion, scribing: remove the photoresist from the _SiO2 substrate or silicon substrate electroplated with copper in step 3, and then corrode the seed layer, leaving the electroplated copper pattern required for growing graphene, and then It is divided into a suitable size as a substrate;

5. Preparation of graphene: use the normal pressure CVD method to load the substrate described in the above step 4 with a quartz boat and put it into a constant temperature zone of a quartz tube with a diameter of 60 mm; heat it to 800-1000 ° C under normal pressure under an argon atmosphere , the argon flow rate is 50-500sccm (mL/min); when the target temperature is reached in the tube, the carbon source gas methane and the mixed gas of argon and hydrogen with a volume ratio of 10:1-1:4 are introduced; after growing for 3-15min, Turn off the heating, methane and argon, and cool with the furnace under the argon atmosphere, and the argon flow rate is 50-500 sccm.

Method B: just omit the step 2 sublayer graphics, the rest is the same as method A.

The advantages of the present invention are as follows:

1. The present invention can electroplate the corresponding copper substrate pattern according to the desired graphene pattern, and then directly grow graphene on it. Compared with the imaging method after film formation, the method provided by the present invention is simpler and more convenient;

2. Compared with growing graphene on copper foil in the present invention, this method is not affected by external forces. Electroplated copper is attached to _SiO2 substrate or single crystal silicon substrate, and the substrate will not be taken during the whole process. Affect the quality of electroplated copper, and copper foil is easily damaged;

3. Compared with growing graphene on sputtered copper, the present invention avoids the problem that sputtered copper film can condense into islands in the high-temperature annealing process, and the graphene grown by the method of the present invention has high surface smoothness and larger area;

4. In process realization, compared with sputtering thick copper film, electroplating copper has low cost and high feasibility.

5. The present invention can directly prepare a patterned graphene film, and the substrate is compatible with the IC process, and has the characteristics of simple method, low cost, and large-scale preparation.

Description of drawings

Fig. 1 (a) is the optical diagram after graphene is grown by electroplating Cu in embodiment 1; (b) is the Raman spectrogram of the graphene grown in embodiment 1.

Fig. 2 (a) is the optical diagram of embodiment 2 electroplating Cu after growing graphene; (b) is the Raman spectrogram of the graphene grown in embodiment 2.

Figure 3 (a) is the photoresist area and stripe area of Example 3; (b) is a schematic diagram of the substrate in which the image shown in Example 3 is divided into corresponding sizes.

In the picture:

Detailed ways

Example 1: Preparation of large-area graphene film based on electroplated copper substrate

The production process is as follows:

1. Oxidize a 200nm _SiO2 oxide layer on single crystal silicon, and then sputter a 50nmNi/200nmCu seed layer on the oxide layer;

2. Electroplate copper with a thickness of 4 μm on the seed layer of the above silicon wafer, the electroplating current is 2A, and the electroplating time is 18 minutes;

3. Divide the silicon wafer into the size of the required substrate, load it into a quartz boat, put it into the constant temperature zone of the quartz tube, and raise the temperature to 1000°C in an atmosphere of 300 sccm argon;

4. When the target temperature is 1000°C, feed 10sccm methane, 200sccm hydrogen and 800sccm argon, grow for 3 minutes, and then anneal with the furnace in an atmosphere of 200sccm argon to produce a large-area graphene film. The experimental results are shown in the figure below: Figure 1(a) is the optical image after growth; Figure 1(b) is the Raman spectrum. The Raman spectrum clearly shows that graphene is a single layer.

Embodiment 2: Prepare multilayer graphene film based on electroplated copper substrate

Steps 1, 2, and 3 are the same as Steps 1, 2, and 3 of Example 1, and the temperature is raised to 800° C.;

4. When the target temperature is 800°C, feed 15sccm methane, 100sccm hydrogen and 400sccm argon, grow for 5 minutes, and then anneal in the furnace under the atmosphere of 200sccm argon to produce multilayer graphene. The experimental results are shown in the following figures: Figure 2(a) is the optical image after growth; Figure 2(b) is the Raman spectrum, which shows that graphene is multilayered.

Example 3: Preparation of highly striped graphene film based on electroplated copper substrate

Step 1 is identical with embodiment 1 step 1;

2. Seed layer patterning: The photolithography plate is shown in Figure 1 below. The striped area is the electroplated copper area (2μm×10μm). After coating a 5μm thick glue, photolithography and development;

3. Electroplating copper: electroplating current 1.8A, electroplating time 15min, electroplating copper thickness 3.5um;

4. Remove the photoresist after electroplating, then soak in the mixed solution of dilute sulfuric acid and hydrogen peroxide for tens of seconds after cleaning, remove the seed layer Ni/Cu, and divide it into substrates of corresponding sizes according to the image after cleaning (the substrate structure is shown in the figure below 5);

Example 3: Preparation of highly striped graphene film based on electroplated copper substrate

Step 1 is identical with embodiment 1 step 1;

2. Seed layer patterning: The photolithography plate is shown in Figure 3(a) below, the striped area is the area of electroplated copper (2μm×10μm), after coating a 5μm thick glue, photolithography and development;

3. Electroplating copper: electroplating current 1.8A, electroplating time 15min, electroplating copper thickness 3.5um;

4. Remove the photoresist after electroplating, then soak in the mixed solution of dilute sulfuric acid and hydrogen peroxide for tens of seconds after cleaning, remove the seed layer Ni/Cu, and divide it into substrates of corresponding sizes according to the image after cleaning (the substrate structure is shown in the figure below 5);

5. Put the loaded quartz boat into the constant temperature zone of the quartz tube, and raise the temperature to 1000°C in an atmosphere of 300sccm argon. When the target temperature is 1000°C, feed 10sccm methane, 200sccm hydrogen and 600sccm argon to grow After 3 minutes, under the atmosphere of 200 sccm argon gas, it is annealed with the furnace, and the striped graphene film can be prepared.

Claims (4)

1. method based on electro-coppering substrate preparation big area Graphene is characterized in that adopting in two kinds of methods of A or B any:

Method A:

(a) electro-coppering Seed Layer is at SiO ₂Splash-proofing sputtering metal Seed Layer on substrate or the silicon base, seed layer materials are Cu, Ni/Cu, Au, Cr/An or TiW/Cu;

(b) copper electroplating layer on Seed Layer selects the electroplating current of 0.5-2.5A and the electroplating time of 10-100min to electroplate copper electroplating layer, and the thickness of copper electroplating layer is 2-10 μ m;

(c) substrate that remove photoresist, burn into is diced into suitable size is written into quartz boat, under nitrogen atmosphere, adopt the atmospheric pressure cvd method, be heated to 800-1000 ℃, after after reaching target temperature, feeding the mixed gas growth 3-15min of carbon-source gas methane and Ar gas and hydrogen, stop heating and close methane and hydrogen;

(d) furnace cooling under argon atmospher;

Method B:

(a) electro-coppering Seed Layer is at SiO ₂Splash-proofing sputtering metal Seed Layer on substrate or the silicon base, seed layer materials are Cu, Ni/Cu, Au, Cr/An or TiW/Cu;

(b) Seed Layer image conversion: the thickness according to required electro-coppering is coated with one deck photoresist material with Seed Layer, and the thickness of photoresist material is 4-12 μ m, and then it is photo-etched into the required figure of subsequent growth Graphene;

(c) copper electroplating layer on Seed Layer selects the electroplating current of 0.5-2.5A and the electroplating time of 10-100min to electroplate copper electroplating layer, and the thickness of copper electroplating layer is 2-10 μ m;

(d) substrate that remove photoresist, burn into is diced into suitable size is written into quartz boat, under nitrogen atmosphere, adopt the atmospheric pressure cvd method, be heated to 800-1000 ℃, after reaching the mixed gas growth 3-15min that feeds carbon-source gas methane and Ar gas and hydrogen under the target temperature, stop heating and close methane and hydrogen;

(e) furnace cooling under argon atmospher;

Wherein, the carbon-source gas that feeds when reaching 800-1000 ℃ of target temperature is a methane, and the flow of methane is 5-20ml/min; The Ar and the H that feed when reaching 800-1000 ℃ of target temperature ₂The volume ratio of mixed gas is 10: 1-1: 4.

2. by the described method of claim 1, it is characterized in that:

(1) the seed metallization layer thickness of step (a) sputter is 50-250nm among method A and the B;

(2) among the method A among step c and the method B flow of steps d hydrogen when reaching target temperature be 50-500ml/min;

(3) flow of argon gas is 50-500ml/min during the described furnace cooling of method A steps d and method B step e.

3. by claim 1 or 2 described methods, it is characterized in that the graphene film for preparing is a single or multiple lift.

4. by claim 1 or 2 described methods, it is characterized in that the graphene film for preparing is a striated.

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