CN114855270B - Molecular beam-like epitaxy equipment and film preparation method - Google Patents

Abstract

The invention is a molecular beam epitaxy apparatus of the kind comprising: the device comprises a reaction cavity, a beam source furnace, a heating device, a gas ionization device, a sample table device and a vacuum system; wherein the gas ionization device is a capacitively coupled plasma source; the gas ionization device comprises an upper polar plate and a lower polar plate, wherein one polar plate is connected with an external radio frequency source, and the other polar plate is grounded; the beam source furnace is provided with a metal evaporation area; a plasma generation area is arranged between the upper polar plate and the lower polar plate; the metal evaporation zone is spatially separated from the plasma generation zone.

Description

A kind of molecular beam epitaxy equipment and film preparation method

technical field

The invention relates to the technical field of semiconductor thin film epitaxial growth, in particular to a molecular beam epitaxy-like device and a thin film preparation method.

Background technique

Nitride materials are widely used in semiconductor light-emitting devices, photodetectors, solar cells and other fields due to their excellent properties. However, in the commonly used thin film growth methods at present: metal organic chemical vapor deposition (MOCVD), the source material ammonia must be cracked at high temperature, but InN material has low thermal stability and is easy to decompose at high temperature, making it difficult to prepare high-quality InN and InGaN materials with high In composition; the growth rate of the sputtering deposition method is fast, but the energy of the sputtered particles is difficult to control accurately, which will cause some particles to etch the deposited thin film material and reduce the crystal quality of the material; the atomic layer deposition method ( Although ALD) has high crystal quality, the growth rate is slow and cannot meet the needs of industry; the growth rate of hydride vapor phase epitaxy (HVPE) is fast, but the background carrier concentration of the grown material is very high, and it is difficult to achieve P-type doping. complex, which limits its industrial application.

Molecular beam epitaxy (MBE) is currently the best way to grow nitride films with high In composition. Due to the contradiction between the high-temperature decomposition of InN grown in the nitride material growth process and the low-temperature cracking of nitrogen-containing gas, plasma-assisted molecular beam is usually used. The epitaxy method for film growth mainly includes radio frequency plasma assisted molecular beam epitaxy (RF-MBE) and electron cyclotron resonance assisted molecular beam epitaxy (ECR-MBE). Among them, ECR-MBE technology is still under development, and there is no mature industrialized equipment for production and sales. Most high-quality nitride materials, especially indium nitride materials, use RF-MBE equipment. The main suppliers of MBE equipment in the world include Vecco of the United States, Riber of France, DCA of the Netherlands, SVTA of the United States, and other suppliers of scientific research and development MBE equipment and MBE source furnace and other accessories. The largest MBE equipment that can be purchased in the market, which can be used for nitride material systems and load ion generators, is 4×4 inch equipment, and the remaining 4×6 inch or 7×6 inch MBE systems are mainly used for solid evaporation reactions equipment. And as the size of the sample stage of MBE equipment increases, the size of the entire equipment cavity and each component increases, the energy consumed in heating and cavity cooling during the working process increases, and the cost of material production and equipment maintenance increases. It is difficult to realize large-scale production and application. Optimizing the configuration of the MBE system, reducing the size of the cavity, increasing production capacity, and reducing production costs are the main directions for equipment transformation and equipment research and development.

CN107675141A discloses a device for preparing nitride materials, which can hold six 6-inch samples at the same time. The device uses a high-frequency radio frequency (13.56MHz) ion gun as an ionization source, and emits a high-activity plasma beam through the ion gun . However, the device has a large chamber space, and the substrate is in a revolving state during the working process. The range of the plasma beam emitted by the ion gun is limited, so that the actual plasma flux of each single substrate is greatly reduced during the rotation of the substrate, which affects the Thin film deposition rate and material properties. It is possible to increase the plasma ionization rate by increasing the RF power or increase the number of ion sources to increase the plasma flux, but increasing the RF power while increasing the plasma energy may cause etching on the substrate, which is not conducive to material growth, and the RF ion source The price is expensive, the operation is more complicated, and increasing the number of ion sources will increase the production cost. In CN108060458A disclosed a kind of preparation device of nonpolar indium nitride nanocrystalline film, provide a kind of utilization low temperature plasma assisted thermal evaporation method to directly prepare nonpolar InN nanocrystalline film on silicon and quartz substrate, wherein metal evaporation The area completely overlaps with the plasma generation area. In this overlapping space, In and N plasmas are more likely to undergo pre-reaction. The material deposited on the substrate surface can only be fused into a single crystal film after recrystallization, and the quality of the grown crystal is poor. It is necessary to find a more suitable plasma supply method to meet the material growth requirements of multi-substrate and large cavity.

At the same time, during the growth of multiple compound materials, especially the growth of InGaN materials, component segregation is prone to occur. Most researchers increase the V/III ratio by pulsed metal-organic chemical vapor deposition or metal-modulated epitaxy (MME) to avoid the formation of Metal droplets, inhibiting the generation of a large number of N vacancies. Among them, the pulse technology may affect the gas flow in the cavity, which is not conducive to material growth. The operation of MME technology is complicated, and new methods need to be found to widen the process window.

The growth equipment and process limit the development and application of nitrides, especially InN and high In composition InGaN materials. To solve the above problems, a mass-production high-vacuum film deposition equipment is designed to grow InN and high In content It is very necessary to compose InGaN materials and realize industrial mass production.

Contents of the invention

The purpose of the present invention is to provide a kind of molecular beam epitaxy equipment and thin film preparation method, using the self-designed capacitively coupled plasma device to provide high-density plasma covering a wide range, and evaporating metal molecules in the space between the upper and lower plates of the ion source and the beam source furnace Beam path separation, in the process environment of high vacuum, low temperature atmosphere, and low RF power, through the revolution system of the sample stage, the metal source and plasma are alternately supplied to the substrate in partitions, reducing the probability of pre-reaction, and solving the problem of low Production capacity, insufficient plasma supply, high-temperature InN easy to decompose and difficult to grow, etc.

The purpose of the present invention is achieved like this:

In one aspect of the present disclosure, a molecular beam epitaxy-like device is disclosed, including: a reaction chamber, a beam source furnace, a heating device, a gas ionization device, a sample stage device, and a vacuum system;

Wherein, the gas ionization device is a capacitively coupled plasma source;

The gas ionization device includes an upper pole plate and a lower pole plate;

One of the plates is connected to an external radio frequency source, and the other plate is grounded;

The beam source furnace has a metal evaporation zone;

There is a plasma generation area between the upper plate and the lower plate;

The metal evaporation area is spatially separated from the plasma generation area.

Further, the gas ionization device is provided with a first shield, and the first shield is arranged on the periphery of the upper plate and the lower plate to reduce the plasma from escaping outward;

A second shield is provided on the periphery of the beam source furnace to reduce outward evaporation of metal molecules.

Further, the sample stage device is provided with multiple sets of slide racks and rotating devices;

The rotating device is adapted to connect with the slide rack, and the rotating device revolves on the sample stage device along a circular track and drives the slide rack to rotate.

Further, the rotation system of the sample stage device drives the slide holder to move between the upper and lower parallel electrode plates of the capacitively coupled plasma source.

The upper pole plate and the lower pole plate are arranged in parallel;

The slide holder is located between the upper pole plate and the lower pole plate.

Further, the beam source furnace is located below the circular arc trajectory formed by the rotation of the carrier, and the beam source furnace is placed vertically perpendicular to the plane of the circular arc trajectory formed by the rotation of the carrier.

Further, the ratio of the path length passing through the region of the capacitively coupled plasma source plate to the path length passing through the evaporation region of the beam source furnace during the revolution of the carrier can be determined by comparing the size of the installed electrode plate with the shielding cover of the beam source furnace Diameter control, realize regulation from 1:1 to 10:1.

A film preparation method, comprising the following steps:

(1) Prepare before the experiment, place the substrate, check and adjust the working status of the equipment;

(2) Substrate treatment, using plasma to clean the substrate online;

(3) Material growth, when the substrate temperature and beam source furnace temperature reach the process temperature, turn on the rotation system;

a. The air pressure is less than 10 ^-3 Pa, open the baffle plate of the beam source furnace to evaporate the solid source, and deposit about 1 layer of metal atoms on the substrate;

b. Introduce nitrogen gas, the pressure is ≥ 1Pa, turn on the ion source to generate plasma for nitriding;

Taking steps a and b as a cycle, repeating the operations in a cycle, and growing the thin film in the cycle.

(4) Post-processing, after the reaction is completed, turn off each reaction source, heating source, rotation and process gas, and wait for the sample to be cooled and taken out.

The beneficial effects of the present invention are:

The molecular beam epitaxy equipment provided by the present invention can generate a large amount of active plasma between the upper and lower plates of the ion source by installing a capacitively coupled plasma source inside the cavity, and maintain sufficient plasma supply. Combined with the sample stage device, each The substrates contained in the slide rack can fully and uniformly react with the plasma. At the same time, the space between the upper and lower plates of the ion source is separated from the path of the metal molecular beam evaporated by the beam source furnace. Growth film material.

It can provide large-area plasma at low temperature and relatively high vacuum atmosphere to grow nitride and high-In composition InGaN thin film materials, which is beneficial to avoid material growth quality problems caused by impurity elements such as C, H, and O. The number of placed substrates is large, and the output is large;

Through the external heating device, the substrate temperature can be increased while increasing the activity of the reaction atoms in the reaction area.

Description of drawings

Fig. 1 is the structural schematic diagram of similar molecular beam epitaxy equipment;

Fig. 2 is a schematic diagram of the working state of the gas ionization device and the beam source furnace device.

Fig. 3 is the XRD spectrum of the InN film prepared on the AlN/Si substrate;

Fig. 4 is InN (002) characteristic peak diagram;

Figure 5 is a SEM test image of the surface morphology of grown InN samples;

Fig. 6 is the indium nitride film thickness figure that forms;

7 is a schematic structural diagram of a molecular beam epitaxy-like device in another embodiment;

Fig. 8 is a schematic diagram of the working state of the volume ionization device and the beam source furnace device in another embodiment.

1. Reaction chamber; 2. Beam source furnace; 3. Heating device; 5. Sample stage device; 21. Second shielding cover; 22. Metal evaporation area; 23. Gallium beam source furnace; 24. Indium beam source furnace; 41, lower pole plate; 42, upper pole plate; 43, plasma generation area; 44, first barrier cover; 421, upper pole plate outer ring; 422, upper pole plate inner ring; 51, rotating device; 52, carrier 61. Molecular pump; 62. Mechanical pump; 63. Cryogenic pump.

Detailed ways

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" etc. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, or in a specific orientation. construction and operation, therefore, should not be construed as limiting the invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and should not be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that unless otherwise specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. Connected, or integrally connected; it can be mechanically connected or electrically connected; it can be directly connected or indirectly connected through an intermediary, and it can be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention in specific situations.

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in combination with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are exemplary only, and are not intended to limit the scope of the present invention. Also, in the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily obscuring the concept of the present invention.

As shown in Figure 1-8, a type of molecular beam epitaxy equipment includes: a reaction chamber 1, a beam source furnace 2, a heating device 3, a gas ionization device, a sample stage device, and a vacuum system 6;

Wherein, the gas ionization device is a capacitively coupled plasma source;

The gas ionization device includes an upper pole plate 42 and a lower pole plate 41,

One of the plates is connected to an external radio frequency source, and the other plate is grounded;

The beam source furnace 2 has a metal evaporation zone 22;

There is a plasma generation area 43 between the upper plate 42 and the lower plate 41;

The metal evaporation region 22 is spatially separated from the plasma generation region 43 .

In some embodiments, the gas ionization device is provided with a first shield 44, and the first shield 44 is arranged on the periphery of the upper pole plate 42 and the lower pole plate 41 to reduce the plasma from escaping outward;

A second shield 21 is provided on the periphery of the beam source furnace 2 to reduce outward evaporation of metal molecules.

Through the spatial separation of the area between the upper and lower plates of the capacitively coupled ion source and the evaporation area of the beam source furnace and the design of the shield, the "alternating mode" growth process adjustment can be realized, reducing pre-reactions, widening the process window, and improving material quality.

In some embodiments, the sample stage device is provided with multiple sets of slide racks 52 and rotating devices 51;

The rotating device 51 is adapted to connect with the slide rack 52 , and the rotating device 51 revolves along the circular track 53 on the sample stage device and drives the slide rack 52 to rotate.

In some embodiments, the rotation system of the sample stage device drives the slide holder 52 to move between the upper and lower parallel electrode plates of the capacitively coupled plasma source.

The upper pole plate 42 and the lower pole plate 41 are arranged in parallel;

The slide rack 52 is located between the upper pole plate 42 and the lower pole plate 41 .

In some embodiments, the beam source furnace 2 is located below the arc track formed by the rotation of the carrier 52 , and the beam source furnace 2 is placed vertically perpendicular to the plane of the arc track formed by the rotation of the carrier 52 .

The capacitively coupled plasma source can generate a large amount of active plasma between the upper and lower plates of the ion source, and maintain sufficient plasma supply. Combined with the sample stage device that rotates and revolves, it can ensure that each carrier 52 can hold the substrate. Fully and uniformly react with the plasma, and at the same time separate the upper and lower plate space of the ion source from the path of the metal molecular beam evaporated by the beam source furnace, supply the plasma and the metal source in partitions, and finally grow thin film materials under high vacuum conditions.

In some embodiments, the ratio of the path length passing through the capacitively coupled plasma source plate region to the path length passing through the beam source furnace 2 evaporation region during the revolution of the carrier 52 can be determined by comparing the size of the installed electrode plate with the beam source furnace 2 The diameter of the second shielding case 21 is controlled to realize regulation from 1:1 to 10:1.

Through the control of the plate size of the capacitively coupled plasma source and the diameter of the shielding cover of the beam source furnace, the plasma flux and the metal flux during the revolution of the cutting frame are controlled, and the V/III ratio regulation method is added to improve the utilization rate of raw materials and the thin film deposition rate.

A method for preparing a nitride film, including but not limited to the following steps:

(1) Prepare before the experiment, place the substrate, check and adjust the working status of the equipment;

(2) Substrate treatment, using plasma to clean the substrate online;

(3) Material growth, when the substrate temperature and beam source furnace temperature reach the process temperature, turn on the rotation system;

a. The air pressure is less than 10 ^-3 Pa, open the baffle plate of the beam source furnace to evaporate the solid source, and deposit about 1 layer of metal atoms on the substrate;

b. Introduce nitrogen gas, the pressure is ≥ 1Pa, turn on the ion source to generate plasma for nitriding;

Taking steps a and b as a cycle, repeating the operations in a cycle, and growing the thin film in the cycle.

(4) Post-processing, after the reaction is completed, turn off each reaction source, heating source, rotation and process gas, and wait for the sample to be cooled and taken out.

It should be noted that when the material growth is carried out under the cavity pressure ≥ 1Pa, the average molecular free path of metal molecules evaporated by the beam source furnace is less affected by the cavity pressure, and it is difficult for the metal to evaporate to the substrate by thermal motion, but It produces a high concentration of N plasma, so the following growth methods can be used for material growth:

(1) Prepare before the experiment, place the substrate, check and adjust the working status of the equipment;

(2) Substrate treatment, using plasma to clean the substrate online;

(3) Material growth, when the substrate temperature and beam source furnace temperature reach the process temperature, turn on the rotation system;

a. The air pressure is less than 10 ^-3 Pa, open the baffle plate of the beam source furnace to evaporate the solid source, and deposit about 1 layer of metal atoms on the substrate;

b. Introduce nitrogen gas, the pressure is ≥ 1Pa, turn on the ion source to generate plasma for nitriding;

Taking steps a and b as a cycle, repeating the operations in a cycle, and growing the thin film in the cycle. (4) Post-processing, after the reaction is completed, turn off each reaction source, heating source, rotation and process gas, and wait for the sample to be cooled and taken out.

When the pressure in the material growth chamber is less than 1Pa, the plasma evaporation metal source can be supplied at the same time, and the following growth methods are used for material growth:

(1) Prepare before the experiment, place the substrate, check and adjust the working status of the equipment;

(2) Substrate treatment, using plasma to clean the substrate online;

(3) Material growth, when the substrate temperature and the beam source furnace temperature reach the process temperature, and the chamber pressure is <1Pa, simultaneously turn on the ion source to generate plasma, open the beam source furnace baffle to evaporate the solid source, and turn on the rotary system for deposition reaction ;

(4) Post-processing, after the reaction is completed, turn off each reaction source, heating source, rotation and process gas, and wait for the sample to be cooled and taken out.

Specifically, a sample stage device is provided on the top of the reaction chamber 1. The sample stage device includes a sample stage rotating device 51 and a slide rack 52. The slide rack 52 is used to hold the substrate, and the sample stage rotating device 51 drives Carrier 52 rotates and revolves, and can place multiple pieces of substrate materials at the same time to make the film grow uniformly;

The gas ionization device is a capacitively coupled plasma source, which mainly includes a radio frequency source installed outside the cavity, and arc plate electrode plates placed parallel to the upper and lower surfaces of the carrier 52, wherein the upper plate 42 is grounded by two concentric arcs. Plates, two arc plates form the orbit of the carrier 52 revolution, the lower plate 41 is located below the arc track formed by the rotation of the carrier 52, and is connected to the external radio frequency source through the electrode rod at the bottom of the cavity. A large amount of active plasma is generated between the upper and lower plates, and the plasma covers a wider area; the substrate loaded on the carrier 52 reacts with a large amount of plasma when the substrate is revolving and rotating between the upper and lower plates, and is suitable for placing multiple substrate processing and film material growth;

Several beam source furnaces 2 are located below the circular arc trajectory formed by the rotation of the carrier 52, and are vertically placed on the bottom plate of the reaction chamber 1 perpendicular to the circular arc trajectory formed by the rotation of the carrier 52. The metal in the beam source furnace 2 When heat continues to evaporate metal molecules to the substrate, the metal molecules evaporate outward at a certain divergence angle, and the space in which the evaporated metal moves to the substrate is called the beam source furnace evaporation area, in which the area between the upper and lower plates of the capacitively coupled ion source and the beam The evaporation area of source furnace 2 is separated in space, which can greatly reduce the probability of pre-reaction between raw materials;

When the substrate is in the process of revolution, metal simple substances are layered in the metal evaporation area 22 of the beam source furnace 2, and then deposited in the plasma generation area 43 to react with metal elements, which alternately deposits anions and cations on the substrate layer by layer. The growth mode is called "alternating mode", which reduces the probability of pre-reaction before the raw material is deposited on the substrate surface;

The beam source furnace 2 has a first shielding cover 22 that can move up and down, which concentrates the evaporation area of the beam source furnace 2 for evaporating metal molecules in the shielding cover, preventing the metal molecules from moving to other areas of the cavity and contaminating the cavity; capacitively coupled plasma The source has an independent second shield 21, and the shield can move vertically up and down to reduce the outward diffusion of the plasma; by rising the shield, the interdiffusion and pre-reaction probability between metal molecules and plasma can be further reduced.

The track length of the carrier 52 revolution is defined as L, during the revolution process of the carrier 52, the track length passing through the pole plate area is defined as L1, and the path length passing through the evaporation area of the beam source furnace 2 is defined as L2, wherein L1 and the pole plate are defined as L1. The plate is parallel to the arc length of the coincident part of the orbit of the carrier 52, i.e. the size of the pole plate, and L2 is related to the length of the overlapping portion of the plane parallel to the carrier 52 and the overlap of the revolution track in the metal evaporation area 22 of the beam source furnace 2 (when When the beam source furnace 2 adds a shield and the shield rises, the length is related to the diameter of the outlet on the upper surface of the shield), L1+L2≤L. By controlling the plate size of the capacitively coupled plasma source and the diameter of the shield of the beam source furnace, the plasma flux and the metal flux during the revolution can be controlled, and the V/III ratio regulation method can be added. The ratio of L1:L2 can be adjusted from 1:1 to 10:1.

There is a heating device 3 above the middle of the bottom plate of the reaction chamber 1, which is located between the beam source furnaces 2. The chamber heating device 3 is heated by the thermal radiation method, which can heat the substrate and the reaction area around the substrate to increase the reaction area. Participate in reactive atomic activity.

The vacuum system in the reaction chamber 1 includes three sets of pumps: a mechanical pump 61, a molecular pump 62 and a cryopump 63, wherein: the molecular pump 61 is arranged outside the reaction chamber 1, and the input end of the molecular pump 62 is arranged in the middle of the reaction chamber 1 On the left side wall, to communicate with the reaction chamber 1, the mechanical pump 62 is used as the backing pump of the molecular pump 61, and the input end of the mechanical pump 62 is connected to the output end of the molecular pump 61; the cryopump 63 is arranged outside the reaction chamber 1, and the low temperature The input end of the pump 63 is arranged on the top outside the reaction chamber 1, and communicates with the reaction chamber 1; the vacuum system cooperates with the chamber baking effect of the chamber heating device 3 to achieve a higher background vacuum;

The number of slide racks 52 is 1 to 10. A single slide rack 52 can carry a 6-inch substrate sample or seven 2-inch samples. The placement positions of the slide racks 52 are all located on the arc of a concentric circle, and When rotating, it also revolves along this arc.

The number of beam source furnaces 2 is 1-10, which are used to provide various cations required for growth.

The number of capacitively coupled plasma sources is 1 to 10 groups, which are used to provide various anions required for growth.

The distance between the upper and lower plates of the capacitively coupled plasma source can be adjusted within 20cm.

Cooperating with the baking function of the reaction chamber of the chamber heating device 3, the vacuum system can draw the background vacuum to below 1×10 ⁻⁶ Pa.

Example 1

A kind of molecular beam epitaxy equipment of indium nitride thin film, its structural diagram is shown in Fig. 1,

The reaction chamber 1 is an airtight chamber, and the sample stage device 5 is arranged on the top of the reaction chamber 1. The sample stage device 5 includes a sample stage rotating device 51 and a slide rack 52, and the slide rack 52 is provided with hollowed-out recesses. The groove is used to hold the substrate. The carrier 52 is fixed on the bracket at the lower end of the sample stage rotating device 51 through a fitting structure. One end of the magnetically coupled rotor rotates under the action of the gear, and drives the carrier 52 to rotate together.

Both the beam source furnace 2 and the gas ionizer 4 are located directly below the circular arc formed by the rotation of the carrier 52, the gas ionizer 4 is adjacent to the beam source furnace 2, and the space between the upper and lower plates of the ion source is adjacent to the beam source furnace. Evaporated metal molecular beam path separation.

The grounding end 42 of the upper plate of the gas ionizer is composed of two concentric circular arc plates, and the revolution track of the carrier is formed between the two circular arc plates; the distance between the upper and lower plates is 10 cm.

The number of substrates that can be accommodated in the carrier 52 is 1-7, and the placement positions of the carrier 52 are all located on the arc line of a concentric circle, and also revolve along this arc line when rotating.

The vacuum system 6 for evacuating the reaction chamber 1 includes three groups of pumps: a molecular pump 61, a mechanical pump 62 and a cryopump 63, wherein: the molecular pump 61 is arranged outside the reaction chamber 1, and the input end of the molecular pump 61 is arranged at the reaction chamber. On the right side wall of the middle part of the cavity 1, to communicate with the reaction cavity 1; the mechanical pump 62 is used as the backing pump of the molecular pump 61, and the input end of the mechanical pump 62 is connected to the output end of the molecular pump 61; the cryopump 63 is located in the reaction cavity Outside the body 1, and the input end of the cryopump 63 is set on the top outside the reaction chamber 1 and communicated with the reaction chamber 1; when the whole vacuum system is working, the background vacuum can be pumped down to below 1×10 ^-6 Pa.

The heating device 3 is evenly arranged on the bottom plate of the reaction chamber, and the whole reaction chamber 1 before the reaction is baked and heated by the heat radiation method, and the gas adsorbed on the inner wall of the reaction chamber 1 can be removed more effectively with the vacuum system 6, Increase the background vacuum of the reaction chamber 1.

The relative positional relationship between the slide rack 52 and the beam source furnace 2 is: the vertical distance between the slide rack and the beam source furnace is about 25 cm, and the beam source furnace 2 has a shield to prevent mutual diffusion of metal and plasma.

The preparation device of indium nitride film, the beam source furnace 2 includes a crucible, a metal baffle, a metal shield, a screw that can move up and down and a heating wire, wherein the material of the crucible is boron nitride.

A method for preparing an indium nitride film, using the above-mentioned device, comprising the following steps:

Step 1, experimental device preparation

(1) fixing the processed substrate substrate on the substrate sample stage;

(2) Put high-purity metal indium (99.999999%) particles into the crucible of the beam source furnace;

(3) Adjust the height of the beam source furnace and the vertical distance between the upper and lower plates of the gas ionizer;

(4) close the reaction chamber, and the device is sealed;

(4) Use a mechanical pump and a molecular pump to evacuate the reaction device, turn on the cavity heating device to heat the cavity to above 100°C, and bake the cavity for 1 hour;

Step 2, Preparation

(1) After the chamber temperature is cooled to room temperature and the pressure is about 10 ^-6 Pa, turn on the heating device to heat the substrate sample, and turn on the substrate rotation device to rotate the sample stage;

(2) Turn off the molecular pump, continuously feed the flow rate of 20sccm hydrogen and 1sccm argon, start the mechanical pump, and control the pressure of the reaction chamber to stabilize at 5Pa;

(3) Turn on the RF source, set the RF power of the RF electrode to 110W, and use plasma to clean the substrate for 15 minutes;

(4) Turn off the hydrogen, argon, and mechanical pumps, turn on the molecular pump, feed in a flow rate of 10 sccm nitrogen, and clean the cavity;

(5) Keep the nitrogen flow rate constant, turn on the radio frequency source to ignite the nitrogen, and keep the chamber reaction pressure <0.05Pa;

(4) Start the beam source furnace, heat it to 775°C, and raise the substrate temperature to 240°C, open the metal baffle of the beam source furnace, and keep the nitrogen flow rate, the nitrogen pressure in the reaction chamber and the radio frequency power constant, The reaction time is 3h;

Step 3, Postprocessing

After the reaction is completed, turn off the beam source furnace of the device, heat the power supply, turn off the radio frequency power supply, turn off the rotation, and turn off the nitrogen gas. After the sample is cooled, take it out to obtain an indium nitride film deposited on the substrate.

In this embodiment, during the material growth process, the schematic diagram of the working state of the gas ionization device and the beam source furnace device is shown in Figure 2:

In the working state, the metal evaporation area is mainly concentrated in the shielding cover of the beam source furnace, and the shielding cover can reduce the diffusion of plasma to the evaporation area. At this time, the ratio of the path length passing through the capacitively coupled plasma source plate region to the path length passing through the beam source furnace evaporation region during the revolution of the carrier is about 1:1.

The XRD spectrum of the InN thin film prepared on the AlN/Si substrate in this embodiment is shown in Figure 3. From the XRD analysis in Figure 3, an obvious InN (002) characteristic peak can be seen, and its (002) FWHM=2300arcsec is measured as shown in Figure 3. 4. The SEM of the film surface test is shown in Figure 5. It can be seen from Figure 5 that the prepared InN film has uniform morphology and size, is closely arranged, and the crystal grains are in an obvious hexagonal shape. Wherein, the thickness of the formed indium nitride thin film is about 180 nm, as shown in FIG. 6 .

Example 2

A kind of molecular beam epitaxy equipment of indium nitride thin film, same as embodiment 1.

A method for preparing an indium nitride film, using the above-mentioned device, comprising the following steps:

Step 1, experimental device preparation

(1) fixing the processed substrate substrate on the substrate sample stage;

(2) Put high-purity metal indium (99.999999%) particles into the crucible of the indium beam source furnace, and put high-purity metal gallium particles into the crucible of the gallium beam source furnace;

(3) Adjust the height of the beam source furnace and the vertical distance between the upper and lower plates of the gas ionizer;

(4) close the reaction chamber, and the device is sealed;

(4) Use a mechanical pump and a molecular pump to evacuate the reaction device, turn on the cavity heating device to heat the cavity to above 100°C, and bake the cavity for 1 hour;

Step 2, Preparation

(1) After the chamber temperature is cooled to room temperature and the pressure is about 10 ^-6 Pa, turn on the heating device to heat the substrate sample, and turn on the substrate rotation device to rotate the sample stage;

(2) Turn off the molecular pump, continuously feed the flow rate of 20sccm hydrogen and 1sccm argon, start the mechanical pump, and control the pressure of the reaction chamber to stabilize at 5Pa;

(3) Turn on the radio frequency source, set the radio frequency power of the radio frequency electrode as 110W, use plasma to clean the substrate,

The cleaning time is 15 minutes;

(4) Turn off the hydrogen, argon, and mechanical pumps, turn on the molecular pump, feed in a flow rate of 10 sccm nitrogen, and clean the cavity;

(5) Turn off the nitrogen gas, start the indium beam source furnace, heat to a temperature of 670°C, and raise the substrate temperature to 240°C;

(6) When the pressure in the reaction chamber is <10 ^-3 Pa, open the metal baffle of the beam source furnace, evaporate metal indium for 2 minutes, and close the beam source furnace baffle.

(7) Continuously feed the flow rate of 20sccm nitrogen, control the pressure of the reaction chamber to be stable at 5Pa, turn on the radio frequency source, set the radio frequency power of the radio frequency electrode to 110W, use plasma to nitrate the substrate for depositing metal indium for 2min, and turn off the radio frequency source, nitrogen.

(8) Taking steps 6 and 7 as one cycle, 60 cycles of cycle operation are performed, and thin film growth is performed during the cycle.

Step 3, Postprocessing

After the reaction is completed, turn off the beam source furnace of the device, heat the power supply, turn off the radio frequency power supply, turn off the rotation, and turn off the nitrogen gas. After the sample is cooled, take it out to obtain an indium nitride film deposited on the substrate.

Example 3

A molecular beam epitaxy-like equipment for InGaN thin films, the schematic diagram of which is shown in FIG. 7 .

The difference between the equipment in this embodiment and the equipment in Embodiment 1 is that the number of beam source furnaces is increased, wherein the gallium beam source furnace 23 is adjacent to the gas ionization device 4, the indium beam source furnace 24 is adjacent to the gallium beam source furnace 23, and Both the gallium beam source furnace 23 and the indium beam source furnace 24 are equipped with shielding covers (the shielding covers are not shown in the structural diagram).

A method for preparing an indium gallium nitride thin film, using the above-mentioned device, comprising the following steps:

Step 1, experimental device preparation

(1) fixing the processed substrate substrate on the substrate sample stage;

(2) Put high-purity metal indium (99.999999%) particles into the crucible of the indium beam source furnace, and put high-purity metal gallium particles into the crucible of the gallium beam source furnace;

(3) Adjust the height of the beam source furnace and the vertical distance between the upper and lower plates of the gas ionizer;

(4) close the reaction chamber, and the device is sealed;

(4) Use a mechanical pump and a molecular pump to evacuate the reaction device, turn on the cavity heating device to heat the cavity to above 100°C, and bake the cavity for 1 hour;

Step 2, Preparation

(1) After the chamber temperature is cooled to room temperature and the pressure is about 10 ^-6 Pa, turn on the heating device to heat the substrate sample, and turn on the substrate rotation device to rotate the sample stage;

(2) Turn off the molecular pump, continuously feed the flow rate of 20sccm hydrogen and 1sccm argon, start the mechanical pump, and control the pressure of the reaction chamber to stabilize at 5Pa;

(3) Turn on the radio frequency source, set the radio frequency power of the radio frequency electrode to 110W, and use plasma to clean the substrate for 15 minutes;

(4) Turn off the hydrogen, argon, and mechanical pumps, turn on the molecular pump, feed in a flow rate of 10 sccm nitrogen, and clean the cavity;

(5) Keep the nitrogen flow rate constant, turn on the radio frequency source to ignite the nitrogen, and keep the chamber reaction pressure <0.05Pa;

(4) Start the gallium beam source furnace, heat it to a temperature of 800°C, start the indium beam source furnace, heat it to a temperature of 690°C, and raise the substrate temperature to 240°C, open the metal baffle of the beam source furnace to maintain the flow rate of nitrogen and the reaction Under the condition of constant nitrogen pressure and radio frequency power in the cavity, the reaction time is 3h;

Step 3, Postprocessing

After the reaction is completed, turn off the beam source furnace of the device, heat the power supply, turn off the radio frequency power supply, turn off the rotation, and turn off the nitrogen gas. After the sample is cooled, take it out to obtain an indium gallium nitrogen film deposited on the substrate.

Example 4

A kind of molecular beam epitaxy equipment for multi-element compound thin film, its overall structure schematic diagram is similar to Fig. 1,

The difference between the equipment of this embodiment and the equipment of Embodiment 1 is that a second shield 44 is installed on the gas ionizer device to prevent most of the plasma from diffusing out of the ionization area, and at the same time it does not hinder the normal rotation of the slide holder 52, which can be further improved. Reduce chance of pre-reaction.

The schematic diagrams of the gas ionization device, the beam source furnace, and the slide rack in this embodiment are shown in FIG. 8 .

It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principle of the present invention, and not to limit the present invention. Therefore, any modification, equivalent replacement, improvement, etc. made without departing from the spirit and scope of the present invention shall fall within the protection scope of the present invention. Furthermore, it is intended that the appended claims of the present invention embrace all changes and modifications that come within the scope and metesques of the appended claims, or equivalents of such scope and metes and bounds.

Claims (3)

1. A kind of molecular beam epitaxy equipment, is characterized in that, comprises: Reaction chamber, beam source furnace, heating device, gas ionization device, sample stage device, vacuum system; Wherein, the gas ionization device is a capacitively coupled plasma source; The gas ionization device includes an upper pole plate and a lower pole plate; One of the plates is connected to an external radio frequency source, and the other plate is grounded; The beam source furnace has a metal evaporation zone; There is a plasma generation area between the upper plate and the lower plate; The metal evaporation zone is spatially separated from the plasma generation zone; The gas ionization device is provided with a first shield, and the first shield is arranged on the periphery of the upper plate and the lower plate to reduce the plasma from escaping outward; A second shield is provided on the periphery of the beam source furnace to reduce the outward evaporation of metal molecules; The sample stage device is provided with multiple sets of slide racks and rotating devices; The rotating device is adapted to connect with the slide rack, and the rotating device revolves along the circular track in the sample stage device and drives the slide rack to rotate; The rotation system of the sample stage device drives the carrier to move between the upper and lower parallel electrode plates of the capacitively coupled plasma source; The upper pole plate and the lower pole plate are arranged in parallel; The slide holder is between the upper pole plate and the lower pole plate; The beam source furnace is located below the arc track formed by the rotation of the carrier, and the beam source furnace is vertically placed perpendicular to the plane of the arc track formed by the rotation of the carrier. 2. The molecular beam epitaxy device according to claim 1, characterized in that: The ratio of the path length passing through the capacitively coupled plasma source plate region to the path length passing through the beam source furnace evaporation region during the revolution of the carrier can be controlled by the size of the installed electrode plate and the diameter of the beam source furnace shield, Realize regulation from 1:1 to 10:1. 3. A film preparation method, characterized in that: using the molecular beam epitaxy-like equipment according to any one of claims 1 to 2, comprising the following steps: (1) Prepare before the experiment, place the substrate, check and adjust the working status of the equipment; (2) Substrate treatment, using plasma to clean the substrate online; (3) Material growth, when the substrate temperature and beam source furnace temperature reach the process temperature, turn on the rotation system; a. The air pressure is less than 10 ^-3 Pa, open the baffle plate of the beam source furnace to evaporate the solid source, and deposit about 1 layer of metal atoms on the substrate; b. Introduce nitrogen gas, the pressure is ≥ 1Pa, turn on the ion source to generate plasma for nitriding; Taking steps a and b as a cycle, repeating the operation in a cycle, and growing the film in the cycle; (4) Post-processing, after the reaction is completed, turn off each reaction source, heating source, rotation and process gas, and wait for the sample to be cooled and taken out.