CN207418858U - Chemical vapor depsotition equipment - Google Patents

Abstract

The utility model provides a chemical vapor deposition equipment, the chemical vapor deposition equipment comprises: a reaction chamber; a vacuum supply device, the vacuum supply device provides the vacuum in the reaction chamber; a source supply device, the source supply device supplying a reaction gas into the reaction chamber; a tubular heater within the reaction chamber having open ends and a lumen for accommodating a growth substrate; a catalyst delivery device for the catalyst A transport device is located in the reaction chamber for transporting the catalyst through the lumen.

Description

Chemical Vapor Deposition Equipment

technical field

The utility model relates to the technical field of chemical vapor deposition, in particular to a chemical vapor deposition equipment.

Background technique

CVD technology is the abbreviation of Chemical Vapor Deposition. Chemical vapor deposition is a method of chemical reaction, using various energy sources such as heating, plasma excitation or light radiation, to make chemical substances in gaseous or vapor state chemically react on the gas phase or gas-solid interface to form solid deposits in the reactor. technology.

Graphene and hexagonal boron nitride are currently popular two-dimensional materials. However, none of these alone can maximize their value. Theoretically and experimentally, it is pointed out that the stacked structure of hexagonal boron nitride and graphene can open the energy band gap of graphene, and can greatly improve the electron mobility of graphene.

At present, for the growth of two-dimensional materials, most of the CVD equipment used are hot-wall tube furnaces. The hot-wall tube furnace can prepare thin films that do not require high vacuum for growth, but the repeatability of the experiment is poor. Moreover, in the practice of preparing a two-dimensional hexagonal boron nitride-two-dimensional graphene stack structure, it was found that in low-vacuum equipment, after the first layer of hexagonal boron nitride was grown, boron nitride would be oxidized. In addition, for such a growth process that is strongly dependent on the catalyst, it is not yet possible to grow without the catalyst based on current sources. However, although the MOCVD equipment for preparing III-V heterojunctions meets the requirements, the cost is too expensive.

Utility model content

In view of this, the utility model provides a chemical vapor deposition equipment.

In one aspect, the utility model provides a kind of chemical vapor deposition equipment, and described chemical vapor deposition equipment comprises:

reaction chamber;

a vacuum providing device, the vacuum providing device provides a vacuum in the reaction chamber;

a source supply that supplies a reaction gas into the reaction chamber;

a tubular heater within the reaction chamber, having open ends and a lumen for accommodating a growth substrate;

A catalyst delivery device located in the reaction chamber for delivering catalyst through the lumen.

Preferably, the tubular heater has a rectangular cross section.

Preferably, the tubular heater is arranged horizontally.

Preferably, the chemical vapor deposition equipment further includes a growth substrate position adjustment device.

Preferably, the growth substrate position adjustment device is a heater height adjustment device.

Preferably, the reaction chamber is a cold-wall reaction chamber.

Preferably, the reaction chamber has a double-walled water-cooled shell.

Preferably, said source supply means comprises a reactive source reservoir.

Preferably, the source of the source supply means is a liquid source and/or a gaseous source.

Preferably, the source supply means comprises a reactive source reservoir for the liquid source and a carrier gas bubbler through the reactive source reservoir.

Preferably, the reaction source storage includes a cooler.

Preferably, the cooler is a semiconductor cold trap.

Preferably, the source supply introduces the reactive gas directly into the lumen.

Preferably, said catalyst delivery means is a roll-to-roll conveyor for bringing catalyst into said lumen via one end of said tubular heater and leaving said lumen via the other end of said tubular heater.

Preferably, the cross-section of the tubular heater is rectangular, and the bottom surface is used to place the growth substrate,

The chemical vapor deposition equipment also includes a growth substrate position adjustment device, the growth substrate position adjustment device is a heater height adjustment device,

The reaction chamber has a double-walled water-cooled shell,

The source of said source supply means is a liquid source and a gaseous source,

The source supply means includes a reactive source reservoir for a liquid source and a carrier gas bubbler through the reactive source reservoir, the reactive source reservoir comprising a semiconductor cold trap,

The catalyst delivery device is a roll-to-roll conveyor for bringing catalyst into the lumen via one end of the tubular heater and exiting the lumen via the other end of the tubular heater.

The equipment of the utility model can provide a high-vacuum growth environment, and can continuously provide new catalysts for growing heterojunctions.

Description of drawings

Figure 1 is a schematic diagram of an embodiment of the apparatus of the present invention.

Figure 2 is a schematic diagram of one embodiment of the manner in which a liquid source is sparged in a source supply.

Figure 3 is a schematic diagram of one embodiment of a tubular heater and catalyst delivery device.

Fig. 4 is a schematic diagram of the structure of the preparation process of the example carried out by using the equipment of this embodiment.

Detailed ways

The technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. . Based on the embodiments of the present utility model, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present utility model.

FIG. 1 is a schematic diagram of an embodiment of a chemical vapor deposition apparatus of the present invention. The chemical vapor deposition equipment of the present utility model comprises: a reaction chamber 1; a vacuum supply device 2, which provides the vacuum in the reaction chamber 1; a source supply device 3, which supplies reaction gas into the reaction chamber 1 ; Tubular heater 4, which is in the reaction chamber 1, has open two ends and a lumen 6 for accommodating the growth substrate; Catalyst delivery device 7, which is in the reaction chamber 1, for Catalyst 8 passes through lumen 6 .

The equipment of the utility model is particularly suitable for preparing multilayer two-dimensional material heterojunction.

The reaction chamber 1 of the utility model is a non-thermal wall reaction chamber, which provides a high vacuum environment, but does not play a role of heating itself. Since the reaction chamber is fully metal-sealed and equipped with high-vacuum valves, compared with the hot-wall tube furnace used in the existing CVD, the reaction chamber can achieve a much higher vacuum degree, which is beneficial to the adjustment of the vacuum degree. There are high demands on the conduction of chemical vapor deposition processes. It is more preferable to use a cold-wall reaction chamber, that is, to cool down the chamber wall through a cooling device, so as to greatly reduce dust pollution in the system. As an example, it adopts a cylindrical chamber, and the chamber adopts a double-walled water-cooled structure. The double-layer sandwich wall water-cooling structure includes an inner wall, an outer wall and a water-cooling circuit sandwiched between the inner and outer walls. It is made of all stainless steel, polished internally and externally, requiring an external leakage rate of less than 10 ^-12 mbar·l·s ^-1 and an internal leakage rate of <10 ^-11 mbar·l·s ^-1 . The interface is sealed with a copper ring to ensure the vacuum of the cavity.

The vacuum supply device 2 is connected with the reaction chamber 1 to provide high vacuum to the reaction chamber 1 . In FIG. 1 , the vacuum providing device 2 is schematically illustrated, but it may have a complicated structure in practice. As an example, the vacuum providing device 2 may include a vacuum obtaining system, a vacuum measuring and a vacuum controlling system. The vacuum obtaining system may, for example, use a pump set of a mechanical pump and a molecular pump to realize a high vacuum of the entire system. The target background vacuum of this system design is 10-3 ~ 10 ^-6 Pa. Therefore, when selecting a pump set, a molecular pump with a higher pumping speed is preferred. The vacuum measurement and control system can form a closed-loop feedback through automatic butterfly valves and vacuum measuring instruments to control the air pressure in the reaction chamber, so that the conditions of each experiment can be stable. The vacuum measuring instrument may include, for example, a vacuum gauge and an associated power supply.

The source supply device 3 is connected to the reaction chamber 1 and supplies the reaction gas into the reaction chamber 1 . The source supply device 3 may include a reaction source storage (not shown) for storing reaction sources. Considering the expandability of the materials that can be grown by the equipment of the present invention, preferably, the equipment is equipped with a liquid source supply mode 31 and a gaseous source supply mode 32 at the same time. In this way, when performing multi-layer deposition, even if the types of sources applicable to each layer are different, this equipment can also be competent. Correspondingly, the source supply device comprises a reaction source reservoir and gas inlet means for liquid reaction sources, and a reaction source reservoir and gas inlet means for gaseous reaction sources. It can be understood that although the liquid source 31 and the gaseous source 32 are connected to the reaction chamber 1 separately in FIG. 1 , they can also be combined before entering the reaction chamber, that is, they share the same interface and are connected to the reaction chamber. The utility model is not limited to this.

A reactive source reservoir for a liquid source can be, for example, a closed tank. When the boiling point of the reactant involved in the chemical gas phase reaction is relatively high, it is difficult to directly obtain the vapor of the reactant. In this case, the carrier gas is used to carry the reactants into the reaction chamber. As shown in Fig. 2, the supply of liquid source can adopt the method of bubbling, and the carrier gas is passed into the closed tank of the storage source through the gas mass flow meter. When the carrier gas is bubbled through the liquid reactant source, a portion of the reactant vaporizes into the carrier gas bubbles until it is close to or reaches saturation in the carrier gas. The bubbled carrier gas contains reactant molecules. A carrier gas containing liquid source molecules is delivered into the reaction chamber, thereby carrying gaseous reactants into the reaction chamber. Considering that the liquid source may need to be stored at cryogenic temperatures, the reactive source storage may include a cooler to maintain the liquid source at the desired storage temperature. The cooler can be a semiconductor cold trap.

When feeding the carrier gas, in order to ensure the amount of reactants, a control instrument such as a gas mass flow meter can be used to control the supply of the carrier gas.

The reactive source reservoir for the gaseous source may be a conventional gas cylinder, gas tank, or the like. For the gas supply of gaseous sources, it is likewise possible to use control devices such as gas mass flow meters.

When using more than two reactants, before supplying the reactants to the reaction chamber, the carrier gas and/or reactant gas containing the reactants can be connected to a gas mixing tank for gas buffering to mix the gases Then it is supplied to the reaction chamber.

Preferably, the reaction gas or the reaction mixture gas is directly introduced into the high temperature zone through a special pipeline, such as a gas flow duct (not shown), so that the gas flow can reach the growth substrate surface accurately and stably.

The above-mentioned features of the source supply device can be combined freely, so as to controllably supply gaseous reaction substances to the reaction zone.

The tubular heater 4 is located in the reaction chamber 1 and has two open ends and a tube cavity 6 for accommodating a growth substrate 5 . The tubular heater 4 can be arranged substantially horizontally. In FIG. 1 , the growth substrate 5 is placed directly on the bottom of the tubular heater 4 , but it may also not be in contact with the tubular heater, eg in the lumen 6 via a substrate support. The tubular heater 4 functions to heat the lumen 6 to provide the temperature required for chemical vapor deposition.

Preferably, the tubular heater 4 has a rectangular cross section. In other words, the heater is designed to be closed on all sides, as shown in Figure 3, leaving only two side open ends for sample removal and supplementary catalyst movement. The heater can be heated by tantalum wire or tungsten wire, which can ensure that the temperature reaches the growth temperature of the material. And this four-sided closed heating unit can effectively form a stable temperature field, and the constant temperature zone becomes longer, which is conducive to the uniform growth of materials. Moreover, the use of a heater with a rectangular cross-section is equivalent to growing the material in a rectangular reaction tube, and the reaction tube with a rectangular cross-section has better lateral uniformity than a circular reaction tube.

Catalyst delivery means 7 are also located within the reaction chamber 1 for delivering catalyst 8 through the lumen 6 . As a preferred example, as shown in FIG. 3 , roll-to-roll transmission is realized by two motors respectively placed on both sides of the lumen. Use a tungsten sample holder to hold the suspended catalyst. The transmission device can be equipped with a speed-regulating power supply to realize the functions of inching and interlocking, and can also realize the regulation of speed. The entire transmission distance is designed to be 30cm to 40cm. The transmission motor is placed outside the lumen to prevent the lubricant in the motor from contaminating the lumen under high temperature and high vacuum conditions.

In one embodiment, the chemical vapor deposition equipment further includes a device for adjusting the relative position of the growth substrate. The relative position adjustment device of the growth substrate is used for adjusting the relative position of the growth substrate and the catalyst, so as to promote deposition. Therefore, the growth substrate relative position adjustment means can adjust the position of the growth substrate, or the catalyst, or both. In FIG. 1 , the growth substrate relative position adjustment device 9 is depicted as being connected to the tubular heater 4 , and the growth substrate 5 is driven by adjusting the position of the tubular heater 4 , thereby adjusting the relative position with the catalyst 8 . However, it should be understood that the relative position adjustment device 9 of the growth substrate may also be connected to a suitable position such as the catalyst delivery device 7 or the growth substrate 5 .

Preferably, a heater height adjustment device is attached to the tubular heater as the growth substrate relative position adjustment device 9 . One example of the heater height adjusting device includes a lift motor and a lift motor shaft, which can lift the tubular heater integrally, as shown in FIG. 3 . The relative distance between the growth substrate placed on the bottom surface of the tubular heater and the suspended catalyst can be changed by the overall elevation of the tubular heater.

The various components of the device of the present invention have been described in detail above in conjunction with FIG. 1 , but the present invention is not limited thereto. Those skilled in the art can make modifications to various components without departing from the spirit of the present invention. Features of each component can be combined as required.

In a particularly preferred embodiment,

The tubular heater is placed horizontally, the cross section is rectangular, and the bottom surface is used to place the growth substrate,

The chemical vapor deposition equipment also includes a growth substrate relative position adjustment device, and the growth substrate relative position adjustment device is a heater height adjustment device,

The reaction chamber has a double-walled water-cooled shell,

The source of said source supply means is a liquid source and a gaseous source,

said source supply means comprises a reactive source reservoir for a liquid source and a carrier gas bubbler through said reactive reservoir, said reactive source reservoir comprising a semiconductor cold trap,

The catalyst delivery device is a roll-to-roll conveyor for bringing catalyst into the lumen via one end of the tubular heater and exiting the lumen via the other end of the tubular heater.

The equipment of the utility model can provide high vacuum, and at the same time, can conveniently replenish catalyst to the reaction zone. The utility model is particularly suitable for the CVD process that requires vacuum degree and catalyst replacement, such as the CVD preparation of two-dimensional hexagonal boron nitride-two-dimensional graphene laminated structure.

Therefore, the utility model provides the use of the equipment of the utility model for preparing a two-dimensional hexagonal boron nitride-two-dimensional graphene laminated structure.

The "two-dimensional" mentioned in the present invention includes but not limited to single atomic layer.

The utility model also relates to a chemical vapor deposition method using the equipment, comprising: providing a vacuum in the reaction chamber, wherein a tubular heater is arranged in the reaction chamber, and the tubular heater has open two ends and a lumen for housing a growth substrate, wherein the growth substrate has been disposed in the lumen; introducing a reaction gas into the reaction chamber; delivering a catalyst through the lumen; and heating the lumen with the tubular heater ; causing the reaction gas to react and deposit on the growth substrate under the action of the catalyst.

The chemical vapor deposition method using the equipment of the utility model uses a tubular heater alone to heat the tube cavity in the vacuum cavity for deposit growth, and can replenish the catalyst to the reaction zone at any time, especially suitable for requirements on vacuum degree and catalyst replacement CVD process.

The utility model also relates to the use of the equipment of the utility model for preparing a two-dimensional hexagonal boron nitride-two-dimensional graphene laminated structure.

The preparation process of the two-dimensional hexagonal boron nitride-two-dimensional graphene stack structure will be further described in detail below, so as to facilitate the understanding of the present invention.

Preparation of two-dimensional hexagonal boron nitride-two-dimensional graphene stack structure

Use the equipment of the utility model to prepare. First, a 25-micron-thick copper foil as a growth substrate and a 50-micron-thick copper foil as a catalyst are loaded into the reaction chamber through a trap door on the reaction chamber. A tubular heater with a rectangular cross-section arranged horizontally and a roll-to-roll catalyst delivery device are arranged in the reaction chamber as shown in FIG. 3 . The growth substrate is placed on the bottom surface of the heater, and the catalyst is placed on the tungsten brackets of the catalyst conveyor belt as the suspended catalyst. The tubular heater is connected with the lifting motor. Adjust the distance between the growth substrate and the suspended catalyst to within 1 mm by controlling the lifting motor. Then the reaction chamber is sealed. Turn on the cooling water system of the reaction chamber to keep the chamber shell cool. Turn on the molecular pump group of the vacuum supply device, and wait for the background vacuum in the reaction chamber to reach 10 ^-6 Pa. Turn on the heating device, and perform annealing treatment on the substrate at 1050°C. After the annealing treatment is completed, set the temperature to the target growth temperature of 1000° C., and wait for the temperature to stabilize.

Next, the two-dimensional hexagonal boron nitride layer is grown. For the hexagonal boron nitride layer, a liquid source of borazine was used. The process gas is fed through the source supply. Specifically, in the reaction source reservoir containing liquid borazine, the bubbler valve is opened, and the carrier gas nitrogen with a flow rate of 0.5 sccm is introduced through a gas mass flow meter, and the precursor for growing hexagonal boron nitride is used to grow hexagonal boron nitride from The liquid source is loaded into the carrier gas nitrogen. After the carrier gas reaches the gas mixing tank, it is buffered and then reaches the high-temperature growth area through the gas conduit. The growth air pressure is set to 3Pa, so that the process air pressure in the whole growth process is in a controlled state. During this process, the suspended catalyst does not need to move because the growth substrate copper foil acts as a catalyst to grow hexagonal boron nitride. After a growth time of 20 minutes at 1000° C., the growth of the two-dimensional hexagonal boron nitride layer is completed.

Next, close the inlet valve of the liquid source and the gas mass flowmeter of this path, and open the inert gas flowmeter to purge the system, so that the subsequent growth of graphene will not be affected by the residual gas.

After purging, turn off the inert gas. Use the vacuum supply device again to increase the vacuum of the system until it stabilizes. Subsequently, graphene growth begins. The growth of graphene uses gaseous source methane, through the inlet valve and mass flow meter, through the buffer zone and gas conduit to reach the high temperature growth area. During the growth of graphene, the catalyst delivery device is activated, because after the growth of the hexagonal boron nitride layer, the catalytic effect of the growth substrate is shielded, and new catalyst copper needs to be continuously introduced to grow graphene. The transmission mode can be selected as continuous or inching mode. Generally, inching mode is sufficient, and the distance of each inching is determined according to the size of the substrate and the growth speed. In this embodiment, the distance of each inching is 1 cm. At a temperature of 1000°C, after 30 minutes of growth, the graphene completely covers the hexagonal boron nitride, and a two-dimensional hexagonal boron nitride-two-dimensional graphene stack structure is obtained.

By using the equipment of the utility model, a good two-dimensional hexagonal boron nitride-two-dimensional graphene stack structure can be produced with high repeatability, and the cost is not high.

The equipment of the utility model can not only prepare stacks of two materials by chemical vapor deposition, but also can be used to prepare stacks of more than three materials in terms of scalability, such as hexagonal boron nitride-graphene-hexagonal nitride Boron three-layer heterojunction structures, provided that these materials are suitable for synthesis by CVD methods.

Fig. 4 is a schematic diagram of the structure of an embodiment of the utility model, which schematically illustrates the functional relationship between various parts of the utility model. The system of the present invention can be divided into three parts: source supply system, growth chamber and peripheral system.

The source supply system includes a liquid source and a gas source, each of which has a flow meter to control the gas flow. The reaction gas enters the reaction chamber after being buffered. There are tubular heaters and temperature measuring devices in the reaction chamber, which provide a growth zone with constant high temperature in the middle and open ends. A catalyst delivery system transports catalyst to the growth zone. As a device for adjusting the relative position of the growth substrate, there may be a heater lifting device in the reaction chamber. The reaction chamber also includes a vacuum measuring instrument, which forms a closed-loop feedback vacuum supply device with the peripheral vacuum pump. The reaction chamber also includes a water cooling system to keep the cold wall of the reaction chamber. The peripheral system also includes necessary power supply and control system, which may include, for example, hardware, software, human-computer interaction interface and so on.

The device of the utility model has a simple structure, can maintain a high vacuum environment, can continuously replenish catalysts, can flexibly adjust the positions of catalysts and growth substrates, and is suitable for different types of reactant sources.

The utility model has been described above by accompanying drawings and embodiments. It should be understood that the scope of the present invention is not limited thereto. Those skilled in the art can make modifications and changes to the embodiments herein without departing from the spirit of the present invention.

Claims (15)

1. a kind of chemical vapor depsotition equipment, the chemical vapor depsotition equipment includes：

Reaction cavity；

Vacuum provides device, and the vacuum provides device and provides the in vivo vacuum of reaction chamber；

Reaction gas is supplied in the reaction cavity by source feedway, the source feedway；

Tubular heater, the tubular heater are in the reaction cavity, are had open both ends and are grown for accommodating The tube chamber of substrate；

Catalyst transmission device, the catalyst transmission device are in the reaction cavity, are passed through for catalyst to be transmitted The tube chamber.

2. chemical vapor depsotition equipment according to claim 1, wherein,

The cross section of the tubular heater is rectangle.

3. chemical vapor depsotition equipment according to claim 1, wherein,

The tubular heater horizontal setting.

4. chemical vapor depsotition equipment according to claim 1, the chemical vapor depsotition equipment further includes growth substrate Relative position regulating device.

5. chemical vapor depsotition equipment according to claim 4, wherein,

The growth substrate relative position regulating device is heater height regulating device.

6. chemical vapor depsotition equipment according to claim 1, wherein,

The reaction cavity is cold wall reaction cavity.

7. chemical vapor depsotition equipment according to claim 1, wherein,

The reaction cavity has double-deck double wall water cooled housing.

8. chemical vapor depsotition equipment according to claim 1, wherein,

The source feedway includes reaction source memory.

9. chemical vapor depsotition equipment according to claim 1, wherein,

The source of the source feedway is liquid source and/or gaseous source.

10. chemical vapor depsotition equipment according to claim 1, wherein,

The source feedway includes the reaction source memory for liquid source and the carrier gas bubbler by reacting source memory.

11. chemical vapor depsotition equipment according to claim 10, wherein,

The reaction source memory for liquid source includes cooler.

12. chemical vapor depsotition equipment according to claim 11, wherein,

The cooler is semiconductor cold-trap.

13. chemical vapor depsotition equipment according to claim 1, wherein, the source feedway is direct by reaction gas It is introduced into the tube chamber.

14. chemical vapor depsotition equipment according to claim 1, wherein,

The catalyst transmission device is roll-to-roll conveyer belt, for catalyst to be made to enter via one end of the tubular heater The tube chamber, and leave the tube chamber via the other end of the tubular heater.

15. chemical vapor depsotition equipment according to claim 1, wherein,

The cross section of the tubular heater is rectangle, and bottom surface is used to place growth substrate,

The chemical vapor depsotition equipment further includes growth substrate relative position regulating device, the growth substrate relative position tune Regulating device is heater height regulating device,

The reaction cavity has double-deck double wall water cooled housing,

The source of the source feedway is liquid source and gaseous source,

The source feedway includes rousing for the reaction source memory of liquid source and by the carrier gas of the reaction source memory Bubbler, the reaction source memory include semiconductor cold-trap,

The catalyst transmission device is roll-to-roll conveyer belt, for catalyst to be made to enter via one end of the tubular heater The tube chamber, and leave the tube chamber via the other end of the tubular heater.