CN113122818B - Method for preparing wafer-level single-layer molybdenum disulfide film - Google Patents

Abstract

The invention discloses a method for preparing a wafer-level monolayer molybdenum disulfide thin film. The method is based on chemical vapor deposition technology and adopts the "face-to-face" method of providing molybdenum source, which can grow a continuous and uniform single-layer molybdenum disulfide film on a sapphire wafer substrate. In the method, a silica gel plate or an alumina plate is used as a molybdenum source carrier, and a molybdenum source precursor is dispersed on the silica gel plate or the alumina plate in the form of a solution. In the dual temperature zone chemical vapor deposition system, the sulfur powder is placed in the left temperature zone, and the sapphire substrate and molybdenum source carrier are placed "face to face" in the right temperature zone. At high temperature, sulfur vapor reacts chemically with molybdenum source, uniformly deposited on the sapphire substrate, and a large-area single-layer molybdenum disulfide film is obtained. The method is simple to operate, and the repeatability of the experimental results is good, which is of great significance to the continuous production of large-area single-layer molybdenum disulfide thin films and the application of electronic devices.

Description

A method for preparing wafer-level single-layer molybdenum disulfide film

technical field

The invention relates to the field of nanometer materials, in particular to a method for preparing a wafer-level monolayer molybdenum disulfide thin film.

Background technique

Monolayer molybdenum disulfide is a two-dimensional semiconductor material with atomic thickness, which has broad application prospects in the fields of electronic devices, optoelectronic devices and sensors. The single-layer molybdenum disulfide has a suitable band gap and high carrier mobility, and the field-effect transistor using the single-layer molybdenum disulfide as the channel material shows excellent performance, and the single-layer molybdenum disulfide has a good effect on the short channel Dow effect is immune. Therefore, monolayer molybdenum disulfide is expected to be applied in a new generation of nanoelectronic devices.

In recent years, the methods for synthesizing monolayer molybdenum disulfide mainly include mechanical exfoliation, liquid phase exfoliation, and chemical vapor deposition. The molybdenum disulfide obtained by the mechanical exfoliation method and the liquid phase exfoliation method is usually in the micron scale or smaller, and it is difficult to obtain a large-area molybdenum disulfide thin film. Most of the traditional chemical vapor deposition methods use solid molybdenum sources (such as molybdenum oxide) as precursors. The solid molybdenum sources gather together during the reaction, which is not conducive to uniform deposition of molybdenum disulfide thin films on large-area substrates. Obtaining large-area, uniform, and high-quality single-layer molybdenum disulfide films is an important prerequisite for their electronic device applications. Therefore, it is of great significance to develop a method for the controllable preparation of wafer-level single-layer molybdenum disulfide thin films to meet the practical application of molybdenum disulfide in electronic devices.

Contents of the invention

The purpose of the present invention is to provide a method for preparing wafer-level single-layer molybdenum disulfide film. The method adopts chemical vapor deposition technology to uniformly deposit a single-layer molybdenum disulfide film on the surface of a substrate by providing a molybdenum source "face-to-face". The film has a large area and good uniformity and can be applied to electronic devices.

The invention provides a method for preparing a wafer-level single-layer molybdenum disulfide film, the method comprising:

The sulfur powder is placed on the upstream of the gas path, the substrate and the molybdenum source carrier are placed face to face on the downstream of the gas path, and chemical vapor deposition is performed, and the wafer-level single-layer molybdenum disulfide thin film is obtained after deposition.

In the above method, the molybdenum source contains a molybdenum-containing compound;

The molybdenum-containing compound is specifically selected from at least one of ammonium molybdate, sodium molybdate and phosphomolybdic acid;

The molybdenum source is specifically a mixed solution obtained by dissolving molybdenum-containing compounds and sodium chloride in water and ammonia; in the mixed solution, the mass ratio of the molybdenum compound to sodium chloride is 0.6g:0.24g-0.3g:0.12 g;

The dosage ratio of the molybdenum compound to water and ammonia is 0.3g: 0.5ml: 0.5ml-0.6g:: 1ml: 1ml;

The mass ratio of the molybdenum-containing compound to the sulfur powder is 0.6g:0.6g-1g.

In the molybdenum source carrier, the carrier is a silica gel plate or an alumina plate.

The preparation of the molybdenum source carrier includes: placing the molybdenum source on the carrier. Specifically, the molybdenum source can be placed on the carrier by dropping. The dropping rate is not particularly limited.

In the chemical vapor deposition step, the area where the sulfur powder is located is a low temperature area; the temperature in the low temperature area is specifically 240-260°C;

The region where the substrate and the molybdenum source carrier are located is a high temperature zone; the temperature in the high temperature zone is specifically 600-700°C; specifically 650-680°C.

The chemical vapor deposition includes:

1) The low temperature zone keeps room temperature constant, and the high temperature zone heats up from room temperature to 120° C. over 5 minutes, and then keeps;

2) The low temperature zone is heated to 240-260°C in 22 minutes; the high temperature zone is heated to 480°C in 12 minutes, and then heated to 650-680°C in 10 minutes;

3) The low temperature zone is kept at a constant temperature of 240-260°C for 15min or 16min, and the high temperature zone is kept at a constant temperature of 650-680°C for 12-20min or 15min or 16min, and the temperature is naturally lowered.

The carrier gas used in the chemical vapor deposition is argon;

The flow rate of the carrier is 90-120 sccm; specifically, 90-100 sccm.

The substrate is a sapphire substrate.

The distance between the substrate and the molybdenum source carrier is 5-7mm; specifically, 5mm.

In addition, the wafer-level single-layer molybdenum disulfide thin film prepared according to the above method also belongs to the protection scope of the present invention.

Specifically, the wafer-level single-layer molybdenum disulfide film is a continuous film covering the substrate.

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

1. By using the atmospheric pressure chemical vapor deposition method, a wafer-level continuous single-layer molybdenum disulfide film can be obtained.

2. Using the "face-to-face" raw material supply method, molybdenum disulfide is uniformly deposited on the surface of the sapphire substrate, and the grown film is very uniform.

3. The method has good repeatability, is a simple and ideal method for synthesizing molybdenum disulfide monolayer film, and is expected to be applied to continuous mass production.

Description of drawings

Fig. 1 is the schematic diagram of the experimental setup of monolayer molybdenum disulfide film prepared by chemical vapor deposition;

Fig. 2 is the scanning electron microscope image of the molybdenum disulfide grown on the sapphire substrate;

Fig. 3 is the physical photo of the molybdenum disulfide grown on the 2-inch sapphire wafer substrate;

Fig. 4 is the Raman spectrogram of monolayer molybdenum disulfide;

Figure 5 is an atomic force microscope image of a single layer of molybdenum disulfide.

Detailed ways

The present invention will be further described below in conjunction with specific examples, but the present invention is not limited to the following examples. The methods are conventional methods unless otherwise specified. The raw materials can be obtained from open commercial channels unless otherwise specified.

Embodiment 1,

A method for preparing large-area single-layer molybdenum disulfide, comprising the steps of:

Atmospheric pressure chemical vapor deposition was used.

To prepare the silica gel plate, first dissolve 0.6 g of ammonium molybdate in a mixed solution of 1 ml of water and 1 ml of ammonia, dissolve 0.24 g of sodium chloride in water, mix the two solutions, and drop them on the silica gel plate to obtain a molybdenum source carrier.

Weigh 0.6g of sulfur powder and place it in the quartz boat in the temperature zone on the left side of the tube furnace, place the molybdenum source carrier in the temperature zone on the right side of the quartz tube of the tube furnace; place the cleaned sapphire substrate face down on the molybdenum source 5mm above the carrier.

Before heating, vacuumize first to discharge the air in the tube furnace, and then introduce argon with a flow rate of 100 sccm as the carrier gas.

Specific heating steps:

In the first heating stage, the left temperature zone kept the room temperature constant, and the right temperature zone was heated from room temperature to 120° C. over 5 minutes, and then maintained.

In the second heating stage, the temperature of the left temperature zone is raised to 260°C in 22 minutes, the temperature of the right temperature zone is raised to 480°C in 12 minutes, and the temperature is raised to 680°C in 10 minutes;

In the third heating stage, the left temperature zone is kept at 260°C for 15 minutes, and the right temperature zone is kept at 680°C for 12 minutes.

Cool down naturally.

Figure 2 is a scanning electron microscope image of molybdenum disulfide grown on a sapphire substrate, showing that the basic morphology of the sample is a large-area continuous molybdenum disulfide film;

Fig. 3 is the physical photo of the molybdenum disulfide grown on the 2-inch sapphire wafer substrate;

Fig. 4 is the Raman spectrogram of monolayer molybdenum disulfide, as can be seen from the figure, the shift difference of two characteristic peaks of molybdenum disulfide obtained in this embodiment is 20.4cm- ¹ , shows that prepared molybdenum disulfide is a monolayer film;

Fig. 5 is an atomic force microscope image of a single-layer molybdenum disulfide, and the thickness of the film is 0.8nm, which further proves that the molybdenum disulfide obtained in this embodiment is a single-layer film.

Embodiment 2,

A method for preparing large-area single-layer molybdenum disulfide, comprising the steps of:

Atmospheric pressure chemical vapor deposition was used.

To prepare the silica gel plate, first dissolve 0.6g of ammonium molybdate in a mixed solution of 1ml of water and 1ml of ammonia, dissolve 0.24g of sodium chloride in water, mix the two solutions, and add them dropwise to the silica gel plate.

Weigh 0.6g of sulfur powder and place it in the quartz boat in the temperature zone on the left side of the tube furnace, place the silica gel plate in the temperature zone on the right side of the quartz tube of the tube furnace; place the cleaned sapphire substrate face down on the silica gel plate. 5mm above.

Before heating, vacuumize first to discharge the air in the tube furnace, and then introduce argon with a flow rate of 100 sccm as the carrier gas.

Specific heating steps:

In the first heating stage, the temperature zone on the left side kept the room temperature constant, and the temperature zone on the right side increased from room temperature to 120°C over 5 minutes, and then kept it.

In the second heating stage, the temperature of the left temperature zone is raised to 260°C in 22 minutes, the temperature of the right temperature zone is raised to 480°C in 12 minutes, and the temperature is raised to 650°C in 10 minutes;

In the third heating stage, the left temperature zone is kept at 260°C for 15 minutes, and the right temperature zone is kept at 650°C for 20 minutes.

Cool down naturally.

Example 3

A method for preparing large-area single-layer molybdenum disulfide, comprising the steps of:

Atmospheric pressure chemical vapor deposition was used.

To prepare the silica gel plate, first dissolve 0.6g of ammonium molybdate in a mixed solution of 1ml of water and 1ml of ammonia, dissolve 0.24g of sodium chloride in water, mix the two solutions, and add them dropwise to the silica gel plate.

Weigh 0.6g of sulfur powder and place it in a quartz boat in the temperature zone on the left side of the tube furnace, place the silica gel plate in the temperature zone on the right side of the quartz tube of the tube furnace; place the cleaned sapphire substrate face down on the silica gel plate. 5mm above.

Before heating, vacuumize first to discharge the air in the tube furnace, and then introduce argon with a flow rate of 120 sccm as the carrier gas.

Specific heating steps:

In the first heating stage, the temperature zone on the left side kept the room temperature constant, and the temperature zone on the right side increased from room temperature to 120°C over 5 minutes, and then kept it.

In the second heating stage, the left temperature zone is heated to 260°C in 22 minutes, the right temperature zone is heated to 480°C in 12 minutes, and then heated to 680°C in 10 minutes; in the third heating stage, the temperature in the left temperature zone is kept at 260°C. Keep it for 15 minutes, and keep it at 680°C for 15 minutes in the right temperature zone.

Cool down naturally.

Example 4

A method for preparing large-area single-layer molybdenum disulfide, comprising the steps of:

Atmospheric pressure chemical vapor deposition was used.

To prepare the silica gel plate, first dissolve 0.6g of ammonium molybdate in a mixed solution of 1ml of water and 1ml of ammonia, dissolve 0.24g of sodium chloride in water, mix the two solutions, and add them dropwise to the silica gel plate.

Weigh 0.6g of sulfur powder and place it in a quartz boat in the temperature zone on the left side of the tube furnace, place the silica gel plate in the temperature zone on the right side of the quartz tube of the tube furnace; place the cleaned sapphire substrate face down on the silica gel plate. 5mm above.

Before heating, vacuumize first to discharge the air in the tube furnace, and then introduce argon with a flow rate of 100 sccm as the carrier gas.

Specific heating steps:

In the first heating stage, the left temperature zone kept the room temperature constant, and the right temperature zone was heated from room temperature to 120° C. over 5 minutes, and then maintained.

In the second heating stage, the temperature of the left temperature zone is raised to 240°C in 22 minutes, the temperature of the right temperature zone is raised to 480°C in 12 minutes, and the temperature is raised to 650°C in 10 minutes;

In the third heating stage, the left temperature zone is kept at 240°C for 16 minutes, and the right temperature zone is kept at 650°C for 16 minutes.

Cool down naturally.

Claims (7)

1. A method of preparing a wafer-level monolayer molybdenum disulfide film, comprising:

placing sulfur powder at the upstream of a gas path, placing a substrate and a molybdenum source carrier at the downstream of the gas path in a face-to-face manner, and carrying out chemical vapor deposition to obtain the wafer-level single-layer molybdenum disulfide film after the deposition is finished;

the molybdenum source is a mixed solution obtained by dissolving a molybdenum-containing compound and sodium chloride in water and ammonia water; in the mixed solution, the mass ratio of the molybdenum-containing compound to the sodium chloride is 0.3g and 0.12g;

the dosage ratio of the molybdenum compound to the water and the ammonia is 0.3g:0.5mL:0.5mL;

the molybdenum-containing compound is ammonium molybdate;

in the molybdenum source carrier, the carrier is a silica gel plate;

in the chemical vapor deposition step, the area where the sulfur powder is located is a low-temperature area; the temperature of the low-temperature zone is 240-260 ℃;

the area where the substrate and the molybdenum source carrier are located is a high-temperature area; the temperature of the high-temperature area is 650-680 ℃.

2. The method of claim 1, wherein: the mass ratio of the molybdenum-containing compound to the sulfur powder is 0.6g-1g.

3. The method of claim 1, wherein: the chemical vapor deposition comprises:

1) The low-temperature area keeps the room temperature unchanged, the high-temperature area is heated from the room temperature to 120 ℃ after 5 minutes, and then the temperature is kept for 8 minutes;

2) The low temperature zone is heated to 240-260 ℃ after 22 minutes; the temperature of the high-temperature zone is raised to 480 ℃ after 12min, and then raised to 650-680 ℃ after 10 min;

3) Keeping the constant temperature of the low-temperature area at 240-260 ℃ for 15min or 16min, keeping the constant temperature of the high-temperature area at 650-680 ℃ for 12-20min, and naturally cooling.

4. The method according to claim 1 or 2, characterized in that: the carrier gas used for the chemical vapor deposition is argon;

the flow rate of the carrier is 90-120sccm.

5. The method of claim 4, wherein: the flow rate of the carrier is 90-100sccm.

6. The method according to claim 1 or 2, characterized in that: the substrate is a sapphire substrate.

7. The method according to claim 1 or 2, characterized in that: the distance between the substrate and the molybdenum source carrier is 5-7mm.

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