CN112695302A

CN112695302A - MOCVD reactor

Info

Publication number: CN112695302A
Application number: CN201911006399.3A
Authority: CN
Inventors: 杜志游; 姜勇
Original assignee: Advanced Micro Fabrication Equipment Inc Shanghai
Current assignee: Advanced Micro Fabrication Equipment Inc Shanghai
Priority date: 2019-10-22
Filing date: 2019-10-22
Publication date: 2021-04-23
Anticipated expiration: 2039-10-22
Also published as: CN112695302B

Abstract

The invention provides an MOCVD reaction chamber, wherein the reaction chamber surrounds to form a reaction space; the bottom of the reaction space comprises a rotating base used for supporting and driving a substrate tray arranged on the rotating base to rotate, the top of the reaction cavity comprises an air inlet device, and the air inlet device comprises a gas spraying plate used for introducing a first reaction gas and a second reaction gas downwards; the gas inlet unit still includes the gaseous shower nozzle of a long rod shape, gaseous shower nozzle passes and is located gaseous shower plate center or the regional through-hole downwardly extending of non-center and be less than gaseous shower plate lower surface, gaseous shower nozzle top includes an auxiliary gas input pipeline, through auxiliary gas input pipeline with one of first reaction air supply or second reaction air supply is connected, gaseous shower nozzle bottom is gas nozzle, the regional blowout of a plurality of outlet channels of gas nozzle bottom surface to the substrate tray center of below comes from auxiliary gas input pipeline's gas.

Description

MOCVD reactor

Technical Field

The present invention relates to an MOCVD (metal organic chemical vapor deposition) reactor, and also to a gas supply device applicable to the above device.

Background

Gallium nitride (GaN), one of the III-V thin films, is a material widely used in the manufacture of blue, violet and white light diodes, ultraviolet detectors and high power microwave transistors. Growth of GaN thin films is of great interest due to the practical and potential use of GaN in the fabrication of low energy devices (e.g., LEDs) suitable for a number of applications.

Group III-V films, including GaN films, can be grown in a number of different ways, including Molecular Beam Epitaxy (MBE), Hydride Vapor Phase Epitaxy (HVPE), Metal Organic Chemical Vapor Deposition (MOCVD), and the like. Currently, the MOCVD process is the preferred deposition method for obtaining thin films of sufficient quality for the production of LEDs.

MOCVD is an acronym for Metal-organic Chemical Vapor Deposition (Metal-organic Chemical Vapor Deposition). MOCVD processes are typically carried out in a reaction chamber or chambers in an environment with temperature control. Generally, a first reactive gas containing a group III-V element (e.g., gallium (Ga)) and a second reactive gas containing nitrogen (e.g., ammonia (NH3)) are introduced into a reaction chamber to react to form a GaN film on a substrate. A carrier gas may also be used to assist in transporting the precursor gas over the substrate. These precursor gases mix and react at the heated substrate surface to form a group III-V nitride film (e.g., a GaN film) that is deposited on the substrate surface. Wherein the first reactive gas and the second reactive gas need to be isolated from each other before entering the reaction chamber, thereby avoiding the formation of pollutants due to advanced reaction. But requires rapid mixing upon reaching the reaction chamber and eventually reacts well to form a semiconductor crystal upon reaching the substrate.

The first reaction gas and the second reaction gas are generally injected into the reaction chamber through a gas shower plate, as shown in fig. 1, which is a structure of a MOCVD reactor commonly used in the prior art, the MOCVD reactor includes a cavity 100, and channels for circulating a cooling liquid are further included in walls of the cavity. A rotating shaft 12 is disposed at the inner bottom of the inner space surrounded by the chamber 100, and a substrate tray 10 is disposed at the top of the rotating shaft, and one or more substrates to be processed can be placed on the substrate tray. Also included below the substrate tray is a heater 14 and a thermal isolation plate 13 surrounding the heater 14. The reactor top comprises a top cover, a gas spray plate 20 is arranged at the lower part of the top cover, a first gas diffusion cavity 201 and a second gas diffusion cavity 202 are arranged in the gas spray plate 20, and the two gas diffusion cavities are respectively connected to a first reaction gas source and a second reaction gas source. The first gas diffusion chamber 201 delivers the first reactant gas (g1) downward to the reaction space below through the plurality of first gas inlet passages 211. The second gas diffusion chamber 202 delivers a second reactant gas (g2) to the lower reaction space through a plurality of second gas inlet passages 212. Wherein the first and second

gas inlet passages

211 and 212 are often elongated in parallel with each other so as to be mixed with another reactant gas adjacent thereto during the downward flow. The bottom of the gas spray header 20 further comprises a water cooling channel 25, and the water cooling channel takes away the redundant heat on the gas spray header through water flow to control the gas spray header to be stabilized at a proper temperature. The reaction chamber 100 is kept in vacuum by pumping air from the bottom of the reaction chamber shell through a vacuum pump. The gas shower head 20 is used for injecting a first reactive gas and a second reactive gas into the reaction chamber 100, the first reactive gas and the second reactive gas are kept separated from each other before entering the reaction chamber 100, and after entering the reaction chamber 100, the first reactive gas and the second reactive gas start to be mixed and finally reach the substrate arranged on the upper surface of the substrate tray, so that sufficient reaction occurs, and a required film layer is formed on the surface of the substrate 15.

In the above gas supply structure, the first reactive gas and the second reactive gas output from the gas shower plate are partially mixed during the downward diffusion process, but it is not guaranteed that the first reactive gas and the second reactive gas are sufficiently mixed in a proper ratio when reaching the upper surface of the substrate tray 10. For this purpose, it is necessary to control the rotating shaft 12 below the gas shower plate to drive the substrate tray to rotate at a high speed (600-. However, even with this design, there is a non-uniformity in the rate of gas deposition in different areas of the substrate tray, including both central and edge area processing results and different edge area processing results. Accordingly, it is desirable to provide an apparatus that improves non-uniformity of wafer processing in different areas of a substrate tray.

Disclosure of Invention

The invention provides an MOCVD reactor, which enables the reaction of a central area and a non-central area of a substrate tray and the non-central area at different positions in the MOCVD reactor to be closer to the gas flow and the mixing ratio of the peripheral area, and greatly improves the growth quality of a substrate semiconductor material.

The MOCVD reactor includes:

the reaction cavity surrounds to form a reaction space;

the bottom of the reaction space comprises a rotating base used for supporting and driving a substrate tray arranged on the rotating base to rotate, and the substrate tray is used for fixing one or more substrates to be processed;

the top of the reaction cavity comprises a top cover, the top cover comprises a gas inlet device, and the gas inlet device comprises a gas spray plate positioned at the lower part of the top cover and used for providing at least one reaction gas for the reaction space;

the gas inlet device also comprises a long rod-shaped gas nozzle which penetrates through the gas spraying plate and extends downwards to a position lower than the lower surface of the gas spraying plate, the top of the gas nozzle is connected with an auxiliary gas conveying pipeline, and the other end of the auxiliary gas conveying pipeline is connected with a reaction gas source or an air extraction device;

the gas shower nozzle carries out local regulation to the gas pressure in the reaction space through the auxiliary gas conveying pipeline.

Optionally, the upper end of the gas nozzle is connected with the top cover through an airtight device, and the airtight device is a magnetic fluid sealing device or a corrugated pipe device.

Optionally, the MOCVD reactor further comprises a driving device for driving the gas shower nozzle to move up and down or rotate.

Optionally, the MOCVD reactor is used for growing multiple material layers, wherein the gas nozzles have different heights when used for growing different material layers.

Optionally, the rotation direction of the gas shower head is different from the rotation direction of the substrate tray.

Optionally, the rotation direction of the gas shower head is the same as the rotation direction of the substrate tray.

Optionally, the gas shower head rotates at the same speed as the substrate tray.

Optionally, the gas showerhead includes a plurality of groups of mutually isolated gas delivery channels, a first group of the gas delivery channels is connected to a first reactive gas source, a second group of the gas delivery channels is connected to a second reactive gas source, and the gas output from the first group of the gas delivery channels and the second group of the gas delivery channels flows to a first region and a second region in the central region of the substrate tray.

Optionally, the gas shower is located below the non-central region of the gas shower plate.

Optionally, the bottom of the gas spraying plate includes a plurality of mutually parallel longitudinal gas channels, a first group of gas channels is connected with a first reaction gas source and is used for introducing a first reaction gas, a second group of gas channels is connected with a second reaction gas source and is used for introducing a second reaction gas, and the first group of gas channels and the second group of gas channels are alternately arranged.

Optionally, the gas shower head includes a gas nozzle, and a sidewall of the gas nozzle includes a plurality of openings, and the openings of the sidewall of the gas nozzle enable the jetted first or second reaction gas to flow obliquely downward toward the substrate tray.

Optionally, the gas shower head further includes a cooling liquid channel therein, and the cooling liquid channel is used for communicating with a cooling liquid source outside the reaction chamber to control the temperature of the gas shower head.

Optionally, the cooling liquid channel further includes an isolation pipe, and the cooling liquid flows into the cooling liquid channel through the isolation pipe, and flows out of the cooling liquid channel through a space between an outer wall of the isolation pipe and an inner wall of the cooling liquid channel.

Optionally, the gas shower nozzle includes a plurality of gas supply pipelines arranged around the cooling liquid channel, wherein a first group of gas supply pipelines is communicated with a first reaction gas source, and a second group of gas pipelines is communicated with a second reaction gas source.

Optionally, the first group of air supply ducts and the second group of air supply ducts are arranged alternately.

Optionally, the first group of air supply ducts is located at the periphery of the second group of air supply ducts.

Optionally, still include first gas diffusion ring and second gas diffusion ring in the gas shower nozzle and be used for exporting or extracting reactant gas to gas shower nozzle below or peripheral direction, first gas diffusion ring with first group gas supply line UNICOM, second gas diffusion ring and second group gas supply line UNICOM, and first gas diffusion ring is located second gas diffusion ring top.

Optionally, the auxiliary gas delivery pipeline in the gas nozzle is communicated with the gas pumping device through an auxiliary pumping flow regulating valve so as to reduce the gas pressure around the gas nozzle.

Optionally, the bottom of the reaction space is communicated with the air extractor through a main air extraction flow regulating valve.

Optionally, the reactor further comprises a controller, and the controller controls the main pumping flow regulating valve and the auxiliary pumping flow regulating valve to regulate the gas pressure in the reaction cavity.

The invention has the advantages that: a gas nozzle is arranged in the central area or the non-central area of the gas spraying plate and used for adjusting the gas pressure of the local area of the gas nozzle or supplying or extracting a certain specific reaction gas, so that the substrate processing effects of different areas of the substrate tray can be compensated.

Drawings

FIG. 1 is a schematic diagram of a prior art MOCVD reactor configuration;

FIG. 2 is a top view of a substrate tray;

FIG. 3 is a schematic diagram of the structure of an MOCVD reactor of the present invention;

FIG. 4 is a bottom view of the gas shower plate and gas showerhead in the MOCVD reactor of FIG. 3, taken upward at Z;

FIGS. 5a and 5b are schematic views of the structure of the nozzle in the gas shower head according to the present invention;

FIG. 6 is a schematic view of the direction of air flow of the embodiment of the nozzle shown in FIG. 5;

FIG. 7a is a schematic vertical cross-sectional view of one embodiment of a gas nozzle of the present invention;

FIG. 7b is a schematic horizontal cross-section at X in the gas nozzle of FIG. 7 a;

FIG. 8a is a schematic vertical cross-section of another embodiment of a gas nozzle of the present invention;

FIG. 8b is a schematic view in horizontal section at Y in the gas nozzle of FIG. 8 a;

FIG. 9 is a schematic diagram of the structure of an MOCVD reactor according to another embodiment of the present invention;

FIG. 10 is a flow chart showing the controller adjusting the gas pressure in the reaction chamber

Detailed Description

The technical solution of the present invention will be described in detail with reference to the accompanying drawings, it being emphasized that this is only exemplary and does not exclude other embodiments utilizing the inventive idea.

According to the conventional MOCVD reactor disclosed in the background art and shown in fig. 1, the defect exists in the way that the substrate tray rotates at a high speed to ensure mixing, the linear velocity of the rotation of the central region of the substrate tray relative to the edge region of the tray is very low, and the reaction gases in the central region cannot be sufficiently mixed. As shown in fig. 2, which is a top view of a substrate tray 10, in which a large number of substrates 15 are disposed on the substrate tray 10, wherein the substrates located in the central region 10A have insufficient reaction or an excessive amount of one of the reaction gases due to insufficient gas mixing, and the remaining 10B region enables rapid deposition due to high-speed rotation of the substrate tray. The problem of uneven semiconductor growth in the central area of the substrate tray is not effectively solved by the prior art, so that the central area of the substrate tray is not provided with a substrate.

On the other hand, the inner bottom of the reaction chamber comprises an air pumping hole communicated with a vacuum pump, so that the reaction chamber is maintained at a low pressure close to vacuum in the reaction process. The first and second reactant gases flowing downward from above flow to the outer edges, so that the flow rate of the gas flowing to the central region 10A of the substrate tray 120 is less than that of the gas flowing to the central region 10B, and this difference also results in poor growth effect in the central region, and thus an effective semiconductor structure cannot be grown.

Besides the poor growth effect of the substrate in the central area, the substrate treatment in different edge areas has the problem of non-uniformity due to the influence of factors such as the temperature of air flow in the reaction cavity.

Therefore, the present invention proposes a new MOCVD reactor to further reduce the occurrence of inefficient growth phenomena in different areas of the substrate tray.

As shown in fig. 3, the gas inlet apparatus of the present invention includes a long rod-shaped gas shower 23 in addition to the gas shower 20, and the gas shower 23 vertically penetrates through the central region of the gas shower plate 20 and extends downward below the lower surface of the gas shower plate 20. One end of the gas shower 23 is connected to a reaction gas supply source, and the other end includes a gas nozzle 23a provided with a plurality of gas outlet channels, the plurality of gas outlet channels of the gas nozzle 23a facing the lower substrate tray to spray the reaction gas toward the central region of the lower substrate tray. The gas shower 23 is further connected to a coolant line connected to an external coolant source 26 to control the gas shower 23 to maintain a reasonable temperature, thereby preventing deformation of the gas shower or premature decomposition of the reaction gas inside the gas shower.

In the process of growing the GaN material layer, various structural layers such as a multilayer buffer layer, a quantum well and the like need to be gradually deposited on an alumina or monocrystalline silicon substrate, and each different material layer needs different gas components and flow rates, so that a required gallium nitride layer can be finally obtained through a plurality of deposition and growth steps, and in each step, a material layer with qualified quality can be produced in the peripheral region 10B on the substrate tray by adjusting a plurality of parameters (temperature, reaction gas components and flow rates). The invention can introduce the reaction gas which is lacked in the reaction space above the central reaction area, namely the central area 10A of the substrate tray in the current step in each step because the MOCVD reactor is provided with the spray head 23 for supplying the reaction gas in an auxiliary way. At least one switchable valve is required at the upper end of the showerhead 23 so that the showerhead can be selectively connected to the first and second reaction gas sources or additional other gases (e.g., carrier gas N2/H2) as required. The quality of the material layer formed in the central reaction region 10A above the substrate tray 10 can be greatly improved as long as the reaction speed or the gas component ratio of the central reaction region 10A is close to that of the region 10B, and finally the production efficiency of the MOCVD reactor can be remarkably improved.

The gas shower nozzle of the invention can move up and down in different processing steps, so that the height of the gas nozzle 23a can also be changed in different heights, and the sprayed gas has different distribution to adapt to the special requirements of different process steps. The growth quality of the central region of the substrate tray can be further improved by the gas nozzles 23a moving up and down, so that the substrates in different regions above the substrate tray have a more uniform treatment effect. In order to ensure that the movable gas spray head 23 maintains air tightness with the gas spray head during the treatment process, a magnetic fluid sealing structure 24 is also required to be arranged above the gas spray head 20, and in other embodiments, the magnetic fluid sealing structure can be replaced by a bellows device. The higher the position of the gas nozzle 23a in the process, the longer the distance from the reaction gas flowing downwards to the substrate, the larger the diffusion range of the gas, the weaker the influence degree on the gas distribution in the central area of the lower substrate tray, and the gas component and flow ratio in the central area can be changed in a small degree. The method is suitable for being applied to the process step with smaller difference of growth effect between the central area 10A and the peripheral area 10B, and micro compensation is realized. The lower the position of the gas nozzle 23a, the closer to the underlying substrate tray 10, the greater the magnitude of the change in gas composition and flow rate to the central region of the substrate tray, suitable for use in process steps where there is a large difference in growth effect between the central region 10A and the peripheral region 10B.

The gas shower 23 of the present invention may also be rotated, wherein the direction and speed of rotation may be selected as desired. For example, the rotation direction of the gas nozzle may be opposite to that of the substrate tray below, so that the speed of the substrate tray below when rotating and the rotation speed of the gas nozzle 23 are superposed, so that the complementary reaction gas flowing out of the gas nozzle 23 and the substrate on the upper surface of the substrate tray have higher relative speed, which is beneficial for the complementary reaction gas flowing out of the gas nozzle 23 and the reaction gas flowing out of the gas nozzle 20 to be mixed with each other quickly, and finally, the mixture of the complementary reaction gas and the original reaction gas not only has the same flow rate and components as those of the surrounding 10B, but also is mixed sufficiently.

Fig. 4 shows a bottom view of the gas shower head 20 and the gas shower head 23 as seen upward at Z in fig. 3, when the substrate tray rotates, the linear velocity of the rotation of the central region of the substrate tray is lower than that of the rotation of the edge region, and since the first gas inlet channel 211 and the second gas inlet channel 212 of the present invention are parallel and long strips alternately arranged, two

regions

1011, 1012 with particularly poor gas mixing degree exist in the central reaction space above the central region 10A of the substrate tray, and the two regions correspond to the spaces below and the reaction gases cannot be well mixed. Since the

gas inlet channels

211 and 212 arranged on the bottom surface of the gas shower head 20 are parallel to each other and are elongated, when the lower substrate tray 10 rotates, a part of the gas supply pipes in the central reaction region are perpendicular to the rotation direction of the lower substrate tray, so that two kinds of reaction gases can be well mixed on the substrate tray, but the gas outflow channels in the

gas inlet channels

211 and 212 are close to being parallel to the rotation direction of the substrate tray corresponding to the

regions

1011 and 1012, which causes the gas in the first gas inlet channel 211 in the region 1011 to be displaced only with the reaction gas from the own gas inlet channel 211, but not to be rapidly mixed with the gas ejected from the adjacent gas inlet channel 212. Therefore, the gas mixing degree in the

regions

1011 and 1012 corresponding to the gas shower head is very poor, and the material layer cannot be effectively grown because of the excessive first reactive gas g1 or the excessive second reactive gas g 2.

The present invention can selectively control the reaction gas output through the gas showerhead 23 to specific substrate tray areas such as 1011, 1012 because the gas showerhead 23 can be rotated. For example, the gas shower 23 rotates synchronously with the substrate tray 10, and most of the reaction gases flowing out from the

regions

1011 and 1012 in the gas holes of the bottom surface of the gas nozzle 23a at the bottom of the gas shower 23 are the first reaction gas or the second reaction gas, so that the first reaction gas or the second reaction gas is exactly compensated with the initial gas distribution generated by the gas shower 20, and finally, the good mixing of the gases in the central region of the substrate tray is realized. Further, the gas nozzles 23a may be provided with different gas outlet channels on the bottom surface or the bottom surface and the side walls, and the reaction gases flowing out of the gas outlet channels respectively have different orientations, so as to respectively compensate each of the

regions

1011 and 1012 where the reaction gases are not uniformly mixed. Therefore, the gas nozzle 23 of the present invention can realize effective mixing of the reaction gas in the central area 10A of the substrate tray by selecting different rotation speeds, rotation directions and gas outlet channel orientations of the gas nozzles 23a, so that the central area is no longer an ineffective growth area, and the production efficiency can be greatly improved. The gas shower head 23 of the present invention can rotate in synchronization with the substrate tray below, so that it is possible to improve the gas mixing ratio of 1011 and 1012 in the compensation region and also improve the gas flow rate unevenness occurring at any position in the central region 10A. As long as local uneven mixing is found in the production process, the shape and the position of the through hole of the nozzle can be designed selectively, so that the gas nozzle can directionally spray compensation gas to the area with the uneven mixing problem, and finally, the uniform treatment effect can be achieved on the whole substrate.

The gas nozzle 23 of the present invention may supplement the inflow of the specific reactant gas to the central region, so as to fully mix the reactant gas in the central region, or may extract the gas outwards, for example, for the region with excessive first reactant gas in the 1011 region, a part of the excessive reactant gas may be selectively extracted, and while the excessive first reactant gas is extracted, the surrounding second reactant gas may flow more to the region under the push of the pressure difference, so as to finally improve the non-uniform mixing degree of the reactant gas.

In the invention, the gas nozzle 23 is used for introducing or extracting the reaction gas into or from the MOCVD reactor, which mainly compensates the problem of uneven gas flow distribution in the central area 10A, so that the required gas flow is extremely small, and the gas flow passing through the gas nozzle 23 is usually less than 1/15 of the gas flow passing through the gas nozzle 20, so that the gas flow distribution in the peripheral area 10B is not disturbed, and the material layer growth quality in the central area can be greatly improved while the whole growth effect is kept.

Fig. 5a is a perspective view of a gas nozzle 23a of the present invention, wherein the bottom of the gas nozzle 23a includes a plurality of arc-shaped gas outlet channels arranged along the circumference, and also includes a plurality of elongated gas outlet channels disposed on the side wall of the gas nozzle 23 a.

Fig. 5b is a schematic perspective view of another embodiment of the gas nozzle 23 a' of the present invention, wherein the bottom of the gas nozzle 23a includes a plurality of uniformly distributed circular gas outlet channels, and the sidewall of the gas nozzle 23a is also provided with a plurality of circular gas outlet channels.

FIG. 6 is a schematic flow diagram of the reaction gas flowing out of FIG. 5a or 5b in the present invention, wherein the gas flowing out of the gas outlet channels on the bottom surface of the gas nozzle 23a flows downward to the region below the showerhead, the gas outlet channels on the lower end of the sidewall flow obliquely downward to the region around the showerhead, and the gas holes on the upper end of the sidewall flow outward horizontally and diffuse to the farther peripheral region, or the gas flowing out direction on the sidewall is reversed. The through hole openings can be selected according to requirements, so that the through holes at different positions respectively correspondingly spray the reaction gases to different areas of the substrate tray, and the through holes corresponding to the different areas can spray the reaction gases with the same or different components.

Fig. 7a shows a structural view of the inside of the nozzle 23a, wherein the nozzle includes a centrally located cooling liquid channel surrounded by an inner wall 32 inside the nozzle 23a, and the cooling liquid channel inside the inner wall 32 serves as a cooling liquid flow channel. The coolant circulation pipe also includes a partition pipe 34, which surrounds an inner passage 236a into which the coolant flows. The outer passage 236b between the outer wall of the separation tube 34 and the inner wall 32 serves as a coolant outflow conduit. The inner wall 32 and the outer side wall of the nozzle comprise a plurality of

air supply pipelines

231, 233 and 235 extending downwards until a plurality of diffusion cavities at the bottom of the nozzle, the diffusion cavities are formed by surrounding the inner wall 32, the side wall and the bottom wall of the nozzle 23a, and the flow cross-sectional area of the air flow in the diffusion cavities is generally larger than that of the

air supply pipelines

231 and 233 above, so that the air flow can be better diffused and uniformly sprayed out from a plurality of air outlet channels at the outer side wall and the bottom of the nozzle. FIG. 7B is a schematic cross-sectional view at X in the nozzle block diagram of FIG. 7a, showing the

gas supply lines

231, 233, 235 respectively feeding A, B, C three reactant gases downward, where A and B are the first and second reactant gases, such as TMG and ammonia; c is isolation gas which does not participate in the reaction but can adjust the concentration of effective gas in the gas flow. The three types of adjusting gas can be simultaneously sprayed into the space in the reaction chamber through the gas nozzle 23, or two types of adjusting gas can be conveyed through one or two gas supply pipelines.

Fig. 8a shows a schematic internal view of another embodiment of a nozzle 23a, wherein the nozzle includes a centrally located coolant channel surrounded by an inner wall 32 'inside the nozzle 23a, the inner wall further including a partition conduit 34' that further divides the coolant conduit into a coolant inflow conduit 236a 'and a coolant outflow conduit 236 b'. A plurality of

gas supply pipelines

239 and 237 extending up and down are also arranged in the nozzle around the cooling liquid pipeline, wherein the plurality of gas supply pipelines 237 are close to and evenly distributed around the inner wall 32' and are used for introducing the reaction gas B downwards; a plurality of gas supply ducts 239 are located around the gas supply duct 237 and are evenly arranged around the gas supply duct 237 for feeding the reaction gas a downward. Wherein the gas supply duct 237 extends downward to the bottom of the gas nozzle and communicates with the gas diffusion ring 236, and the gas diffusion ring 236 is provided with a plurality of gas outlet channels for spraying the reaction gas B downward and toward the outer sidewall. The gas supply pipe 239 extends downward to communicate with the gas diffusion ring 238, and the gas diffusion ring 238 is provided with a plurality of gas outlet channels for ejecting the reaction gas a to the outer side wall. Wherein the gas diffusion ring 238 is located above the gas diffusion ring 236, the reactant gas a can be TMG gas, the reactant gas B can be ammonia gas, and the gas diffusion ring 236 is located further below, so that the amount of heat received by the lower radiation is greater, the temperature will be higher than that of the upper gas diffusion ring 238, and the difference in height can make the reactant gas TMG, which is more easily pyrolyzed, not easily pyrolyzed in advance in the gas supply pipe and the gas diffusion ring and form contaminants. As shown in fig. 8b, which is a cross-sectional view at Y of the nozzle 23a shown in fig. 8a, it can be seen that the first and second air supply ducts are arranged in a uniform manner in the horizontal direction with respect to the inner and outer circumferences.

Fig. 9 is a schematic view of an MOCVD reactor according to another embodiment in which a gas shower 123 is connected to a reaction gas source for supplying reaction gas into the reaction space, or connected to a gas exhaust device, such as a vacuum pump, for exhausting gas near the gas nozzle 123a, and extends below the lower surface of the gas shower plate through a non-central region of the gas shower plate. One end of the gas nozzle, which is located outside the reaction chamber, is connected to a switching device (not shown in the figure), and the switching device can select the gas nozzle to be connected to a reaction gas source or to be connected to an air extractor. As in the case of the gas shower head shown in fig. 3, which passes through the central region of the gas shower plate, the gas shower head may move up and down or rotate when the gas shower head is disposed in the non-central region of the gas shower plate, and in this embodiment, a bellows 124 is disposed between the gas shower head and the top of the reaction chamber in order to ensure the gas tightness between the gas shower head and the reaction chamber when the gas shower head moves. In further embodiments, the bellows may also be replaced with a magnetic fluid seal.

When the gas shower 123 is located in the non-central region of the gas shower plate, since the gas shower plate does not rotate with the substrate tray, the opening provided on the bottom surface of the gas nozzle 123a may be only vertically oriented toward the substrate for gas supply or gas extraction, or may be only provided on one side of the gas nozzle for gas supply or gas extraction in one fixed direction, or an independent gas delivery channel may be provided inside the gas shower, and the different gas delivery channels supply or gas extraction in a certain direction according to the needs of different processes.

When the gas nozzle is used for extracting gas in the reaction space, the gas nozzle can be connected with the air extracting device 125 through an auxiliary air extracting flow regulating valve 111, the air extracting device can be simultaneously used as a main air extracting device for discharging byproduct gas in the reaction cavity, the exhaust area at the bottom of the reaction cavity is connected with the air extracting device 125 through a main air extracting flow regulating valve 112, and the air extracting device can realize main regulation and auxiliary regulation on the pressure in the reaction space through the main air extracting flow regulating valve 112 and the auxiliary air extracting flow regulating valve.

FIG. 10 is a flow chart showing the regulation of the gas pressure in the reaction chamber by two flow regulating valves; wherein, a controller 200 connected with the reaction chamber extracts the process parameters in the process from the reaction chamber in real time and monitors the processing condition of the substrate on the substrate tray, the controller 200 calculates the degree of influence of the pressure in the reaction space according to the monitored processing condition of the substrate, and outputs control signals to the main pumping flow regulating valve 112 and the auxiliary pumping flow regulating valve 111 respectively to realize the pressure regulation in the reaction space.

According to the invention, a gas spray head is additionally arranged at the center of the top gas spray head, a small amount of compensation reaction gas is introduced downwards from a nozzle at the bottom of the spray head, or excessive reaction gas is pumped out, so that the substrate on the surface of the substrate tray can be uniformly treated. The gas shower can be moved up and down to accommodate different compensation requirements in different process steps. And the gas nozzle can be driven by an external driver to rotate, and the reaction gas supplemented into the center of the substrate tray and the original reaction gas below can be mutually compensated by selecting the rotating direction and the rotating speed, so that the optimal reaction gas mixing degree is obtained, and the quality of the material layer in the central area of the substrate tray is greatly improved.

While the present invention has been described in detail with reference to the preferred embodiments, it should be understood that the above description should not be taken as limiting the invention. Various modifications and alterations to this invention will become apparent to those skilled in the art upon reading the foregoing description. Accordingly, the scope of the invention should be determined from the following claims.

Claims

1. An MOCVD reactor, comprising:

the reaction cavity surrounds to form a reaction space;

2. The MOCVD reactor according to claim 1, wherein an upper end of said gas shower head is connected to said top cover by a gas-tight means, which is a magnetic fluid sealing means or a bellows means.

3. The MOCVD reactor according to claim 1, wherein said MOCVD reactor further comprises a driving means for driving said gas shower head to be capable of moving up and down or rotating.

4. The MOCVD reactor according to claim 3, wherein said MOCVD reactor is for growing multiple layers of materials, wherein the gas nozzles have different heights for growing different layers of materials.

5. The MOCVD reactor according to claim 3, wherein a rotation direction of said gas shower head is different from a rotation direction of said substrate tray.

6. The MOCVD reactor according to claim 3, wherein a rotation direction of said gas shower head is the same as a rotation direction of said substrate tray.

7. The MOCVD reactor of claim 6, wherein a rotation speed of said gas showerhead is the same as a rotation speed of a substrate tray.

8. The MOCVD reactor of claim 6, wherein said gas showerhead comprises a plurality of sets of mutually isolated gas delivery channels, a first set of said gas delivery channels being coupled to a first reactant gas source and a second set of said gas delivery channels being coupled to a second reactant gas source, said first and second sets of said gas delivery channels outputting gas to flow to first and second regions within a central region of the substrate tray.

9. The MOCVD reactor of claim 1, wherein said gas showerhead is located below a non-central region of said gas shower plate.

10. The MOCVD reactor according to claim 1, wherein the bottom of the gas shower plate comprises a plurality of mutually parallel elongated gas channels, a first group of the gas channels being in communication with a first reactant gas source for introducing a first reactant gas, a second group of the gas channels being in communication with a second reactant gas source for introducing a second reactant gas, wherein the first and second groups of the gas channels are arranged alternately.

11. The MOCVD reactor of claim 1, wherein said gas showerhead comprises a gas nozzle having a sidewall including a plurality of openings, said gas nozzle sidewall openings directing the emitted first or second reactant gases obliquely downward toward the substrate tray.

12. The MOCVD reactor according to claim 1, wherein the gas showerhead further comprises a coolant channel therein, the coolant channel being adapted to communicate with a source of coolant outside the reaction chamber to control the temperature of the gas showerhead.

13. The MOCVD reactor according to claim 12, wherein said coolant channel further comprises an isolation tube therein, said coolant flowing into said coolant channel through the interior of said isolation tube and out of said coolant channel through the space between the outer wall of said isolation tube and the inner wall of said coolant channel.

14. The MOCVD reactor of claim 12, wherein the gas showerhead comprises a plurality of sets of gas supply conduits disposed about the coolant channel, wherein a first set of gas supply conduits is coupled to a first reactant gas source and a second set of gas conduits is coupled to a second reactant gas source.

15. The MOCVD reactor of claim 14, wherein the first set of gas supply conduits alternate with the second set of gas supply conduits.

16. The MOCVD reactor of claim 14, wherein the first set of gas supply conduits is located peripherally to the second set of gas supply conduits.

17. The MOCVD reactor according to claim 14, wherein a first gas diffusion ring and a second gas diffusion ring are further included in the gas showerhead for outputting or extracting reaction gas to a direction below or in a peripheral direction of the gas showerhead, the first gas diffusion ring is communicated with the first group of gas supply lines, the second gas diffusion ring is communicated with the second group of gas supply lines, and the first gas diffusion ring is located above the second gas diffusion ring.

18. The MOCVD reactor according to claim 1, wherein an auxiliary gas delivery pipe in said gas showerhead is communicated with said gas pumping means through an auxiliary pumping flow rate adjusting valve to reduce a gas pressure around the gas showerhead.

19. The MOCVD reactor according to claim 18, wherein a bottom of said reaction space is in communication with said pumping means through a main pumping flow regulating valve.

20. The MOCVD reactor according to claim 18, wherein the reactor further comprises a controller, wherein the controller is used for adjusting the gas pressure in the reaction chamber by controlling the main pumping flow regulating valve and the auxiliary pumping flow regulating valve.