Spray structure, reaction device, epitaxial wafer, its preparation method and applications

Abstract

This invention provides a spray structure, a reaction device, an epitaxial wafer, its preparation method, and its applications. The spray structure has several strip-shaped nozzles, which are divided into first nozzles and second nozzles with different widths. The first and second nozzles are arranged side by side and alternately. The first and second nozzles spray different reactive gases onto the surface of the epitaxial wafer, respectively. A diameter of the tray parallel to the length direction of the strip-shaped nozzles is designated as a baseline. The centerline of the length direction of the first nozzle and the centerline of the length direction of the adjacent second nozzle are designated as the centerline of the first nozzle and the centerline of the second nozzle, respectively. The baseline is located between the centerlines of the first and second nozzles. Using the spray structure provided by this invention, the gas in the central area of ​​the tray can be rapidly and uniformly mixed, essentially eliminating differences in the flow field and concentration field, and significantly improving the thickness uniformity of the epitaxial wafer.

Description

Technical Field

[0001] This invention belongs to the technical field and relates to a spray structure, a reaction device, an epitaxial wafer, its preparation method, and its uses. Background Technology

[0002] An epitaxial wafer is a single-crystal silicon wafer grown on a substrate using epitaxial growth processes. The epitaxial layer thickness is typically 2-20 micrometers, while the substrate single-crystal silicon wafer is approximately 610 micrometers thick. Epitaxial growth technology developed in the late 1950s and early 1960s. To manufacture high-frequency, high-power devices, it was necessary to reduce the collector series resistance. Various methods exist for growing epitaxial layers, but vapor phase epitaxy is the most common. This often uses a high-frequency induction furnace for heating. The substrate is placed on a high-purity graphite heating element coated with silicon carbide, glassy graphite, or thermally decomposed graphite, and then placed in a quartz reactor. Infrared irradiation heating can also be used. To overcome certain drawbacks of epitaxial processes, many new advancements have been made in epitaxial growth techniques, including depressurized epitaxy, low-temperature epitaxy, selective epitaxy, suppressed epitaxy, and molecular beam epitaxy. Epitaxial growth can be classified in various ways. According to the different chemical compositions of the substrate and epitaxial layer, it can be divided into homoepitaxial growth and heteroepitaxial growth. According to the reaction mechanism, it can be divided into epitaxial growth using chemical reactions and epitaxial growth using physical reactions. According to the phase transition mode during the growth process, it can be divided into gas phase epitaxy, liquid phase epitaxy and solid phase epitaxy, etc.

[0003] Currently, the epitaxial wafers on the LED market are mainly 2-inch and 4-inch, while the epitaxial technology for 6-inch and even larger sizes is not yet mature. One of the main reasons is that large-size epitaxial wafers are prone to cracking and fragmentation during the growth process, and the uniformity of the epitaxial wafers is poor, resulting in low product yield. These are thorny issues in the mass production of large-size epitaxial wafers.

[0004] In traditional semiconductor manufacturing processes, large-size epitaxy is usually carried out in horizontal reaction devices. These horizontal reaction devices have symmetrical spray structures and high reaction chamber heights. By rotating the tray at high speed to create a suction pump effect, the reaction gas sprayed by the spray structure is evenly "pulled" above the tray, thereby forming a uniform flow field and concentration field distribution.

[0005] To date, reports have indicated that gas purging in the central region can be used to regulate the flow field uniformity. However, the gas flow is unstable and highly sensitive, making it difficult to control the reaction gas flow and achieve uniformity between the central region and other regions. This is particularly problematic for HEMT epitaxy, which requires high Al composition uniformity, and Micro-LED epitaxy, which requires high wavelength uniformity. Therefore, it is imperative to redesign the structure of existing epitaxial wafer reaction devices to address these technical issues. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a spray structure, reaction device, epitaxial wafer, preparation method and application thereof, which enables the gas in the central region to be rapidly and uniformly mixed, and the difference between the flow field and concentration field is basically eliminated, thereby greatly improving the thickness uniformity of the epitaxial wafer.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a spray structure for an epitaxial wafer reaction chamber, the spray structure being located above a tray on which an epitaxial wafer is placed, the spray structure having a plurality of strip-shaped nozzles, the strip-shaped nozzles being divided into a first nozzle and a second nozzle with different widths, the first nozzle and the second nozzle being arranged alternately side by side, the first nozzle and the second nozzle respectively spraying different reaction gases onto the surface of the epitaxial wafer;

[0009] The diameter of the tray that is parallel to the length direction of the strip nozzle is designated as the baseline. The centerline of the length direction of the first nozzle and the centerline of the length direction of the adjacent second nozzle are designated as the first nozzle centerline and the second nozzle centerline, respectively. The baseline is located between the first nozzle centerline and the second nozzle centerline, such that the central area of ​​the tray is within the overlapping spray range of the first nozzle and the second nozzle.

[0010] Traditional epitaxial wafer reaction chambers feature strip-shaped nozzles symmetrically distributed around a baseline, aligned with the centerline of either the first or second nozzle. In this spray structure, as the reactive gas is injected downwards, the gas concentration field distribution remains largely unchanged until it reaches the center of the tray. This means the central region contains only a single type of gas with a single diffusion concentration directly opposite the nozzle above. Therefore, when the reactive gas reaches the epitaxial wafer surface, while other areas experience rapid and uniform mixing due to the pumping effect of the tray's high-speed rotation, the central region, with only a single reactive gas, suffers from uneven mixing even with tray rotation, leading to differences in the flow field and concentration field. To address this, this invention abandons the traditional symmetrical spray structure and proposes an asymmetrical spray structure to solve the problem of flow field uniformity in the central region, thus meeting the production requirements of large-size epitaxial wafers. Specifically, by staggering the strip nozzles so that the baseline is between the centerlines of the first and second nozzles, the central area of ​​the tray can be ensured to be within the overlapping spray range of the first and second nozzles. During the downward flow of the reactive gas, the central area can also participate in the mixing process of the concentration field. That is, the central area does not only correspond to the single gas and diffusion concentration of the upper nozzle, but the central area of ​​the tray surface can also cover multiple reactive gases like other areas. By rotating the tray, the gas in the central area is quickly and uniformly mixed, and there is basically no difference between the flow field and the concentration field, which greatly improves the thickness uniformity of the epitaxial wafer.

[0011] It should be noted that the "reference line located between the center line of the first nozzle and the center line of the second nozzle" as defined in this invention means that when the center lines of the first nozzle and the second nozzle are projected onto the tray surface, the reference line is located between the projection of the center line of the first nozzle and the projection of the center line of the second nozzle.

[0012] As a preferred embodiment of the present invention, the width of the first nozzle is greater than the width of the second nozzle, the first nozzle is used to spray group V source reactant gas, and the second nozzle is used to spray group III source reactant gas.

[0013] Preferably, the width of the first nozzle is 5 to 10 mm, for example, it can be 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm, 8 mm, 8.5 mm, 9 mm, 9.5 mm or 10 mm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0014] Preferably, the width of the second nozzle is 0.5 to 5 mm, for example, it can be 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm or 5 mm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0015] In this invention, the first and second nozzles are arranged alternately and densely and uniformly throughout the spray structure to ensure that the group V and group III source reactant gases are fully and uniformly mixed above the epitaxial wafers. Several epitaxial wafers are horizontally placed on the surface of a tray, which rotates along its central axis. A fixed heating element is located beneath the tray. During tray rotation, the heating element remains stationary. The tray rotation improves the heating uniformity between different epitaxial wafers. Simultaneously, the centrifugal force generated during rotation causes gas flow between the reactant gases, further enhancing the mixing degree of the group V and group III source reactant gases.

[0016] As a preferred embodiment of the present invention, the boundary line between the first nozzle and the adjacent second nozzle is aligned with the baseline.

[0017] In this invention, the spray structure is detachably fixed to the top of the inner cavity of the reaction device. The spray structure includes at least a spray disc located above the tray, with a first nozzle and a second nozzle on the side surface of the spray disc near the tray. Reactive gas is injected into the cavity of the reaction device through the spray disc. To prevent excessively fast gas flow from forming turbulence upon entering the inner cavity and affecting the uniformity of deposition, the diameter of the spray disc can be optionally adjusted. By changing the diameter of the spray disc, the flow rate of the reactive gas ejected from the first and second nozzles can be better regulated, thereby adjusting the growth rate and uniformity of the first layer to improve the thickness uniformity of the epitaxial wafer.

[0018] It should be noted that different nozzles can be relatively isolated from each other, that is, the spray plate is equipped with several independent gas delivery channels, each nozzle corresponding to a gas delivery channel. Different reactive gases can be introduced into different gas delivery channels, thereby independently controlling the reactive gas concentration, flow rate and flow rate of each nozzle. It also facilitates the secondary distribution of reactive gases within the spray plate. Finally, the gases are sprayed evenly onto the epitaxial wafer through their respective nozzles, and with the rotation of the epitaxial wafer, they are fully mixed to complete the deposition reaction. This not only effectively improves the uniformity of the deposition thickness, but also controls the consumption of reactive gases and reduces the production cost of the epitaxial wafer.

[0019] Optionally, the present invention may further include several cooling channels within the spray plate, with each gas delivery channel corresponding to a cooling channel. Coolant is introduced into the cooling channels to directly control the temperature of the reaction gas within the gas delivery channels, ensuring a stable temperature of the reaction gas ejected from the nozzle. This guarantees that the reaction gas enters the reaction apparatus cavity at a suitable temperature, preventing undesirable pre-reactions such as decomposition, deposition, and condensation. By combining cooling channels with gas delivery channels, a uniform distribution of the gas concentration and temperature fields in the deposition reaction can be achieved, thereby improving the quality and yield of the epitaxial wafer, reducing reaction gas consumption, and lowering the production cost of the epitaxial wafer, making it suitable for large-scale industrial production.

[0020] Secondly, the present invention provides an epitaxial wafer reaction apparatus, the epitaxial wafer reaction apparatus including a spray chamber and a reaction chamber located below the spray chamber, the diameter of the spray chamber being smaller than the diameter of the reaction chamber, and the spray chamber being connected to the reaction chamber through a curved sidewall.

[0021] The spray chamber is provided with the spray structure described in the first aspect. The reaction chamber is provided with a tray, an extension plate is placed on the tray, a heating element is provided below the tray, a side ring is provided on the outer periphery of the tray, and the outer periphery of the side ring near the tray is an annular arc surface. The annular arc surface corresponds to the position of the curved side wall, and an annular streamlined exhaust channel is formed between the annular arc surface and the curved side wall.

[0022] During the reaction, excess reactant gas is discharged from the outer periphery of the tray, while the reactant gas in the center of the tray has to follow the longest flow path to exit the reaction chamber. However, the internal cavity of currently used reaction devices has multiple angles, which obstructs gas flow. Furthermore, the airflow becomes turbulent as it reaches the area below the tray due to the enlarged flow channel. All these factors affect the rapid and smooth discharge of gas, causing severe stagnation of reactant gas on the tray surface. To solve this technical problem, this invention incorporates a side ring around the outer periphery of the tray. This side ring forms a streamlined exhaust channel between itself and the reaction chamber cavity. The curved flow channel reduces airflow turbulence, helping the gas to exit quickly. Simultaneously, the side ring effectively prevents airflow from entering the area below the tray, preventing gas accumulation and obstruction. Based on this, combined with the spray structure provided by this invention, the gas in the center of the tray is thoroughly mixed and rapidly discharged. The rotation of the tray further enhances the uniformity of the flow field and concentration field between the center and other areas of the tray.

[0023] As a preferred embodiment of the present invention, the curvature of the annular arc surface is the same as the curvature of the sidewall of the curved surface.

[0024] As a preferred embodiment of the present invention, the top end of the side ring is flush with the surface of the tray.

[0025] Furthermore, in this invention, since the outer periphery of the side ring near the tray is an annular arc surface, a gap exists between the side ring and the tray. This gap isolates the temperature difference between the side ring and the tray, preventing heat dissipation from the outer periphery of the tray. Specifically, a heating element is provided below the tray, while the gas in the exhaust channel is unheated. The gap between the side ring and the tray prevents the tray from contacting the exhaust channel during heating, thus avoiding or reducing heat dissipation from the outer periphery of the tray during heating. This reduces or avoids edge effects during epitaxial growth and improves the uniformity of epitaxial growth.

[0026] Thirdly, the present invention provides a method for preparing an epitaxial wafer, wherein the preparation method is carried out in the epitaxial wafer reaction apparatus described in the second aspect, and the preparation method includes:

[0027] The substrate is placed on a tray, and the first and second nozzles spray different reactive gases onto the substrate surface. The tray drives the substrate to rotate so that the reactive gases are evenly distributed on the substrate surface. The substrate is heated by a heating element, and the reactive gases are deposited on the substrate surface to obtain the epitaxial wafer. The undeposited reactive gases are discharged through the exhaust channel.

[0028] It should be noted that, in order to further improve the uniformity of epitaxial wafer thickness, in addition to making improvements to the device structure, process parameters such as gas flow rate during epitaxial layer growth, distance between the tray and the nozzle, and tray rotation speed can also be studied. By adjusting the above process parameters in conjunction with the device structure provided by this invention, the airflow difference of epitaxial wafers in different regions can be further reduced, thereby improving the warpage of epitaxial wafers, reducing the thickness difference between epitaxial wafers at the center and edge positions, and improving inter-wafer uniformity.

[0029] For example, to control the gas mixing effect, the tray rotation speed needs to be strictly controlled. In the reaction apparatus provided by this invention, the preferred tray rotation speed is 5000–1000 r / min. This is because when the tray rotation speed is high enough, the reactant gases gain sufficient kinetic energy and, upon contact with the epitaxial wafer surface, are rapidly spread across the entire surface under centrifugal force, preventing the reactant gases from stagnating in the central area of ​​the tray, where the concentration would be significantly higher than in the peripheral area. A higher tray rotation speed also helps to achieve a more uniform concentration, velocity, and temperature boundary layer on the epitaxial wafer surface. However, the tray rotation speed cannot be too high. Because high-speed tray rotation generates centrifugal force, many unreacted or un-reacted gases will be directly thrown to the outer periphery of the tray and discharged directly through the exhaust channel, leading to increased consumption of reactant gases and significantly increasing the production cost of the epitaxial wafer.

[0030] Fourthly, the present invention provides an epitaxial wafer, which is prepared by the preparation method described in the third aspect, wherein the intra-wafer uniformity of the epitaxial wafer is less than or equal to 3%.

[0031] As a preferred embodiment of the present invention, the diameter of the epitaxial wafer is greater than or equal to 8 inches.

[0032] Fifthly, the present invention provides an application of the epitaxial wafer reaction apparatus described in the second aspect, the epitaxial wafer reaction apparatus being used to prepare large-size epitaxial wafers.

[0033] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] Traditional epitaxial wafer reaction chambers feature strip-shaped nozzles symmetrically distributed around a baseline, aligned with the centerline of either the first or second nozzle. In this spray structure, as the reactive gas is injected downwards, the gas concentration field distribution remains largely unchanged until it reaches the center of the tray. This means the central region contains only a single type of gas with a single diffusion concentration directly opposite the nozzle above. Therefore, when the reactive gas reaches the epitaxial wafer surface, while other areas experience rapid and uniform mixing due to the pumping effect of the tray's high-speed rotation, the central region, with only a single reactive gas, suffers from uneven mixing even with tray rotation, leading to differences in the flow field and concentration field. To address this, this invention abandons the traditional symmetrical spray structure and proposes an asymmetrical spray structure to solve the problem of flow field uniformity in the central region, thus meeting the production requirements of large-size epitaxial wafers. Specifically, by staggering the strip nozzles so that the baseline is between the centerlines of the first and second nozzles, the central area of ​​the tray can be ensured to be within the overlapping spray range of the first and second nozzles. During the downward flow of the reactive gas, the central area can also participate in the mixing process of the concentration field. That is, the central area does not only correspond to the single gas and diffusion concentration of the upper nozzle, but the central area of ​​the tray surface can also cover multiple reactive gases like other areas. By rotating the tray, the gas in the central area is quickly and uniformly mixed, and there is basically no difference between the flow field and the concentration field, which greatly improves the thickness uniformity of the epitaxial wafer. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the epitaxial wafer reaction apparatus provided in an embodiment of the present invention;

[0037] Figure 2 This is a top view of the spray structure provided in an embodiment of the present invention;

[0038] Figure 3 This is a schematic diagram of the epitaxial wafer reaction apparatus provided as a comparative example of the present invention;

[0039] Figure 4 A top view of the spray structure provided as a comparative example of the present invention;

[0040] Figure 5 Thickness characteristic spectrum of an epitaxial wafer provided as a comparative example of the present invention;

[0041] Figure 6 The thickness characteristic spectrum of the epitaxial wafer provided in the embodiments of the present invention;

[0042] Among them, 1-spray chamber; 2-reaction chamber; 3-side ring; 4-exhaust channel; 5-tray; 6-spray structure; 7-second nozzle; 8-first nozzle; 9-baseline. Detailed Implementation

[0043] It should be understood that in the description of this invention, the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0044] It should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0045] Traditionally sized epitaxial wafers can achieve uniform flow field by avoiding the central region. However, as wafer sizes increase dramatically, the central region becomes essential. Traditional epitaxial wafer reactors suffer from insufficient gas mixing and uneven flow field distribution in the central region, leading to differences in flow and concentration fields on the tray surface. Furthermore, because the airflow is spiral-downward, gas in the central region is more difficult to expel than in other areas, inevitably resulting in slower flow and stagnation. Ultimately, this manifests as inconsistent reactant gas concentrations in the central region compared to other areas, affecting the uniformity of the prepared epitaxial wafer thickness. Therefore, current epitaxial wafer reactors are no longer sufficient to meet production requirements.

[0046] To address the aforementioned technical problems, in one specific embodiment of the present invention, a spray structure 6 for an epitaxial wafer reaction chamber is provided, such as... Figure 1 As shown, the spray structure 6 is located above the tray 5, on which an epitaxial sheet is placed. The spray structure 6 has several strip-shaped nozzles, which are divided into a first nozzle 8 and a second nozzle 7 with different widths. The first nozzle 8 and the second nozzle 7 are arranged side by side and alternately. The first nozzle 8 and the second nozzle 7 respectively spray different reactive gases onto the surface of the epitaxial sheet.

[0047] like Figure 2 As shown, the diameter of the tray 5 that is parallel to the length direction of the strip nozzle is denoted as the baseline 9. The length direction centerline of the first nozzle 8 and the length direction centerline of the adjacent second nozzle 7 are respectively denoted as the first nozzle 8 centerline and the second nozzle 7 centerline. The baseline 9 is located between the first nozzle 8 centerline and the second nozzle 7 centerline, so that the central area of ​​the tray 5 is within the overlapping spray range of the first nozzle 8 and the second nozzle 7.

[0048] In traditional epitaxial wafer reaction chambers, the strip nozzles are symmetrically distributed around a reference line 9, meaning the reference line 9 is aligned with the centerline of either the first nozzle 8 or the second nozzle 7. In this spray structure 6, when the reactive gas is injected downwards, the gas concentration field distribution remains essentially unchanged during the downward flow, remaining consistent until it reaches the central region of the tray 5. This means the gas in the central region consists only of a single type of gas and a single diffusion concentration directly opposite the upper nozzle. Therefore, when the reactive gas reaches the epitaxial wafer surface, in other areas, due to the high-speed rotation of the tray 5, the different reactive gases mix rapidly and uniformly under the suction pump effect. However, in the central region, because it only corresponds to a single reactive gas, even with the rotation of the tray 5, the gas mixing is uneven, leading to differences in the flow field and concentration field. Based on this, this invention abandons the traditional symmetrical spray structure 6 and proposes an asymmetrical spray structure 6 to solve the problem of flow field uniformity in the central region, meeting the production requirements of large-size epitaxial wafers. Specifically, by misaligning the strip nozzles, the baseline 9 is positioned between the centerline of the first nozzle 8 and the centerline of the second nozzle 7. This ensures that the central area of ​​the tray 5 is within the overlapping spray range of the first nozzle 8 and the second nozzle 7. During the downward flow of the reactive gas, the central area can also participate in the mixing process of the concentration field. That is, the central area does not only correspond to the single gas and diffusion concentration of the upper nozzle. The central area of ​​the tray 5 surface, like other areas, can cover multiple reactive gases. Furthermore, by rotating the tray 5, the gas in the central area is rapidly and uniformly mixed, and the difference between the flow field and the concentration field is basically eliminated, which greatly improves the thickness uniformity of the epitaxial wafer.

[0049] It should be noted that the "reference line 9 located between the center line of the first nozzle 8 and the center line of the second nozzle 7" as defined in this invention means that when the center line of the first nozzle 8 and the center line of the second nozzle 7 are projected onto the surface of the tray 5, the reference line 9 is located between the projection of the center line of the first nozzle 8 and the projection of the center line of the second nozzle 7.

[0050] Furthermore, the width of the first nozzle 8 is greater than the width of the second nozzle 7. The first nozzle 8 is used to spray group V source reactant gas, and the second nozzle 7 is used to spray group III source reactant gas.

[0051] Furthermore, the width of the first nozzle 8 is 5-10 mm.

[0052] Furthermore, the width of the second nozzle 7 is 0.5 to 5 mm.

[0053] In this invention, the first nozzle 8 and the second nozzle 7 are arranged alternately and densely and uniformly distributed throughout the spray structure 6 so that the group V source reactant gas and the group III source reactant gas are fully and uniformly mixed above the epitaxial wafer.

[0054] Several epitaxial wafers are placed horizontally on the surface of tray 5. Tray 5 rotates along its own central axis. There is a fixed heating element under tray 5. During the rotation of tray 5, the heating element remains stationary. The rotation of tray 5 improves the heating uniformity between different epitaxial wafers. At the same time, the centrifugal force generated during the rotation drives the gas flow between the reaction gases, further improving the mixing degree of group V source reaction gas and group III source reaction gas.

[0055] Furthermore, the boundary line between the first nozzle 8 and the adjacent second nozzle 7 is aligned with the reference line 9.

[0056] In this invention, the spray structure 6 is detachably fixed to the top of the inner cavity of the reaction device. The spray structure 6 includes at least a spray disc located above the tray 5. A first nozzle 8 and a second nozzle 7 are provided on the side surface of the spray disc near the tray 5. The reaction gas is injected into the cavity of the reaction device through the spray disc. In order to prevent the gas flow rate from being too fast and forming turbulence after entering the inner cavity, which would affect the uniformity of deposition, the diameter of the spray disc can be optionally adjusted. By changing the diameter of the spray disc, the flow rate of the reaction gas ejected from the first nozzle 8 and the second nozzle 7 can be better adjusted, thereby adjusting the growth rate and uniformity of the first layer to improve the thickness uniformity of the epitaxial wafer.

[0057] It should be noted that different nozzles can be relatively isolated from each other, that is, the spray plate is equipped with several independent gas delivery channels, each nozzle corresponding to a gas delivery channel. Different reactive gases can be introduced into different gas delivery channels, thereby independently controlling the reactive gas concentration, flow rate and flow rate of each nozzle. It also facilitates the secondary distribution of reactive gases within the spray plate. Finally, the gases are sprayed evenly onto the epitaxial wafer through their respective nozzles, and with the rotation of the epitaxial wafer, they are fully mixed to complete the deposition reaction. This not only effectively improves the uniformity of the deposition thickness, but also controls the consumption of reactive gases and reduces the production cost of the epitaxial wafer.

[0058] Optionally, the present invention may further include several cooling channels within the spray plate, with each gas delivery channel corresponding to a cooling channel. Coolant is introduced into the cooling channels to directly control the temperature of the reaction gas within the gas delivery channels, ensuring a stable temperature of the reaction gas ejected from the nozzle. This guarantees that the reaction gas enters the reaction apparatus cavity at a suitable temperature, preventing undesirable pre-reactions such as decomposition, deposition, and condensation. By combining cooling channels with gas delivery channels, a uniform distribution of the gas concentration and temperature fields in the deposition reaction can be achieved, thereby improving the quality and yield of the epitaxial wafer, reducing reaction gas consumption, and lowering the production cost of the epitaxial wafer, making it suitable for large-scale industrial production.

[0059] In another specific embodiment, the present invention provides an epitaxial wafer reaction apparatus, the epitaxial wafer reaction apparatus including a spray chamber 1 and a reaction chamber 2 located below the spray chamber 1, the diameter of the spray chamber 1 being smaller than the diameter of the reaction chamber 2, and the spray chamber 1 being connected to the reaction chamber 2 through a curved sidewall.

[0060] The spray chamber 1 is provided with the spray structure 6 provided in the above specific embodiment. The reaction chamber 2 is provided with a tray 5, on which an extension sheet is placed. A heating element is provided below the tray 5. A side ring 3 is provided on the outer periphery of the tray 5. The outer periphery of the side ring 3 near the tray 5 is an annular arc surface. The position of the annular arc surface corresponds to that of the curved side wall. An annular streamlined exhaust channel 4 is formed between the annular arc surface and the curved side wall.

[0061] During the reaction, excess reactant gas is discharged from the outer periphery of tray 5, while the reactant gas in the central area of ​​tray 5 must travel the longest flow path to exit the reaction chamber. However, the internal cavity of the currently used reaction device has multiple angular shapes, which obstruct gas flow. Furthermore, when the airflow reaches the area below tray 5, turbulence is created due to the enlarged flow channel. All these factors affect the rapid and smooth discharge of gas, causing severe stagnation of reactant gas on the surface of tray 5. To solve this technical problem, this invention provides a side ring 3 around the outer periphery of tray 5, forming a streamlined exhaust channel 4 between the side ring 3 and the inner cavity of the reaction chamber 2. The curved flow channel reduces airflow turbulence, helping the gas to exit quickly. Simultaneously, the presence of the side ring 3 effectively prevents airflow from entering below tray 5, preventing gas accumulation below tray 5. Based on this, combined with the spray structure 6 provided by this invention, the gas in the center of tray 5 is fully mixed and rapidly discharged. The rotation of tray 5 improves the uniformity of the flow field and concentration field between the central area and other areas of tray 5. Furthermore, the curvature of the annular arc surface is the same as the curvature of the curved sidewall.

[0062] Furthermore, the top of the side ring 3 is flush with the surface of the tray 5.

[0063] Furthermore, in this invention, since the outer periphery of the side ring 3 near the tray 5 is an annular arc surface, there is a gap between the side ring 3 and the tray 5. This gap isolates the temperature difference between the side ring 3 and the tray 5, preventing heat dissipation from the outer periphery of the tray 5. Specifically, a heating element is provided below the tray 5, while the gas in the exhaust channel 4 is unheated. The gap between the side ring 3 and the tray 5 prevents the tray 5 from contacting the exhaust channel 4 during heating, thus avoiding or reducing heat dissipation from the outer periphery of the tray 5 during heating. This reduces or avoids edge effects during epitaxial growth and improves the uniformity of epitaxial growth.

[0064] In another specific embodiment, the present invention provides a method for preparing an epitaxial wafer, the preparation method being carried out in the epitaxial wafer reaction apparatus provided in the above specific embodiment, the preparation method comprising:

[0065] The substrate is placed on the tray 5. The first nozzle 8 and the second nozzle 7 spray different reactive gases onto the substrate surface. The tray 5 drives the substrate to rotate so that the reactive gases are evenly distributed on the substrate surface. The substrate is heated by the heating element, and the reactive gases are deposited on the substrate surface to obtain the epitaxial wafer. The undeposited reactive gases are discharged through the exhaust channel 4.

[0066] It should be noted that, in order to further improve the uniformity of epitaxial wafer thickness, in addition to making improvements to the device structure, process parameters such as gas flow rate during epitaxial layer growth, distance and height between tray 5 and nozzle, and rotation speed of tray 5 can also be studied. By adjusting the above process parameters in conjunction with the device structure provided by this invention, the airflow difference of epitaxial wafers in different regions can be further reduced, thereby improving the warpage of epitaxial wafers, reducing the thickness difference between epitaxial wafers at the center and edge positions, and improving inter-wafer uniformity.

[0067] For example, to control the gas mixing effect, the rotation speed of tray 5 needs to be strictly controlled. In the reaction apparatus provided by this invention, the preferred rotation speed of tray 5 is 5000–1000 r / min. This is because when the rotation speed of tray 5 is sufficiently high, the reactant gas gains sufficient kinetic energy and, upon contact with the epitaxial wafer surface, is rapidly spread across the entire surface under centrifugal force, preventing the reactant gas from stagnating in the central region of tray 5, where the concentration of reactant gas is significantly higher than in the peripheral region. Using a higher tray 5 rotation speed also helps to achieve a more uniform concentration, velocity, and temperature boundary layer on the epitaxial wafer surface. However, the rotation speed of tray 5 cannot be too high. Because the high-speed rotation of tray 5 generates centrifugal force, many unreacted or unreacted gases will be directly thrown to the outer periphery of tray 5 and discharged directly through exhaust channel 4 under the centrifugal force of high-speed rotation, leading to increased consumption of reactant gas and significantly increasing the production cost of the epitaxial wafer.

[0068] In another specific embodiment, the present invention provides an epitaxial wafer, which is prepared by the preparation method provided in the above specific embodiment, wherein the intra-wafer uniformity of the epitaxial wafer is less than or equal to 3%.

[0069] Furthermore, the diameter of the epitaxial wafer is greater than or equal to 8 inches.

[0070] In another specific embodiment, the present invention provides a use of the epitaxial wafer reaction apparatus provided in the above specific embodiments, wherein the epitaxial wafer reaction apparatus is used to prepare large-size epitaxial wafers.

[0071] Example

[0072] This comparative example provides an epitaxial wafer reaction apparatus, such as... Figure 1 As shown, the epitaxial wafer reaction apparatus includes a spray chamber 1 and a reaction chamber 2 located below the spray chamber 1. The diameter of the spray chamber 1 is smaller than the diameter of the reaction chamber 2. The spray chamber 1 is connected to the reaction chamber 2 through a curved sidewall.

[0073] The reaction chamber 2 is provided with a tray 5, on which an epitaxial sheet is placed, and a heating element is provided below the tray 5.

[0074] The spray chamber 1 is equipped with a spray structure 6, which has several strip-shaped nozzles. The first nozzle 8 and the second nozzle 7 are arranged alternately side-by-side. The width of the first nozzle 8 is greater than the width of the second nozzle 7. The first nozzle 8 and the second nozzle 7 respectively spray group V source reactive gas and group III source reactive gas onto the surface of the epitaxial wafer. A diameter of the tray 5 that is parallel to the length direction of the strip-shaped nozzles is designated as a reference line 9. The boundary line between the first nozzle 8 and the adjacent second nozzle 7 is aligned with the reference line 9 (e.g., ...). Figure 2 (As shown).

[0075] Comparative Example

[0076] This comparative example provides an epitaxial wafer reaction apparatus, such as... Figure 3 As shown, the epitaxial wafer reaction device includes a spray chamber 1 and a reaction chamber 2 located below the spray chamber 1. The diameter of the spray chamber 1 is smaller than the diameter of the reaction chamber 2. The spray chamber 1 and the reaction chamber 2 are connected by a connecting section with an inverted frustum structure. The joint between the end of the spray chamber 1 and the end of the connecting section, as well as the joint between the end of the connecting section and the end of the reaction chamber 2, both have sharp edges.

[0077] The reaction chamber 2 is provided with a tray 5, on which an epitaxial sheet is placed, and a heating element is provided below the tray 5.

[0078] The spray chamber 1 is equipped with a spray structure 6, which has several strip-shaped nozzles. The first nozzle 8 and the second nozzle 7 are arranged alternately side-by-side. The width of the first nozzle 8 is greater than the width of the second nozzle 7. The first nozzle 8 and the second nozzle 7 respectively spray group V source reactive gas and group III source reactive gas onto the surface of the epitaxial wafer. A diameter of the tray 5 that is parallel to the length direction of the strip-shaped nozzles is designated as a reference line 9. The centerline of the first nozzle 8 is aligned with the reference line 9 (e.g., ...). Figure 4 (As shown).

[0079] Application examples

[0080] GaN epitaxial layers were deposited on the surface of an 8-inch sapphire substrate using the epitaxial wafer reaction apparatus provided in the examples and comparative examples, respectively. The same epitaxial process conditions were used in the examples and comparative examples, and the thickness uniformity of the prepared epitaxial wafers was tested.

[0081] in, Figure 5 The thickness characteristic spectrum of the epitaxial wafer prepared using the epitaxial wafer reaction apparatus provided in the comparative example is obtained by... Figure 5 It can be seen that the epitaxial wafer prepared in the comparative example has an excessively thick central region, which is caused by the retention of reactive gas in the central region. Furthermore, Figure 5 The overall thickness uniformity of the epitaxial wafers was poor, approximately 5.3%. Figure 6 The thickness characteristic spectrum of the epitaxial wafer prepared by the epitaxial wafer reaction apparatus provided in this embodiment of the invention is obtained by... Figure 6 It can be seen that the overall thickness of the epitaxial wafer is relatively uniform, approximately 2.7%. Therefore, from Figure 5 and Figure 6 The comparison shows that the thickness uniformity of the epitaxial wafer prepared using the reaction apparatus provided by the present invention is significantly improved.

[0082] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A spray structure for an epitaxial wafer reaction chamber, the spray structure being located above a tray on which an epitaxial wafer is placed, characterized in that, The spray structure has several strip-shaped nozzles, which are divided into first nozzles and second nozzles with different widths. The first nozzles and the second nozzles are arranged side by side and alternately. The first nozzles and the second nozzles spray different reactive gases onto the surface of the epitaxial wafer, respectively. The diameter of the tray that is parallel to the length direction of the strip nozzle is designated as the baseline. The centerline of the length direction of the first nozzle and the centerline of the length direction of the adjacent second nozzle are designated as the first nozzle centerline and the second nozzle centerline, respectively. The baseline is located between the centerline of the first nozzle and the centerline of the second nozzle. The boundary line between the first nozzle and the adjacent second nozzle is aligned with the baseline, such that the central area of ​​the tray is within the overlapping spray range of the first nozzle and the second nozzle.

2. The spray structure of the epitaxial wafer reaction chamber according to claim 1, characterized in that, The width of the first nozzle is greater than the width of the second nozzle. The first nozzle is used to spray group V source reactant gas, and the second nozzle is used to spray group III source reactant gas.

3. The spray structure of the epitaxial wafer reaction chamber according to claim 1 or 2, characterized in that, The width of the first nozzle is 5mm to 10mm.

4. The spray structure of the epitaxial wafer reaction chamber according to claim 1 or 2, characterized in that, The width of the second nozzle is 0.5mm to 5mm.

5. An epitaxial wafer reaction apparatus, characterized in that, The epitaxial wafer reaction apparatus includes a spray chamber and a reaction chamber located below the spray chamber. The diameter of the spray chamber is smaller than the diameter of the reaction chamber, and the spray chamber is connected to the reaction chamber through a curved sidewall. The spray chamber is provided with the spray structure according to any one of claims 1-4. The reaction chamber is provided with a tray, an extension plate is placed on the tray, a heating element is provided below the tray, a side ring is provided on the outer periphery of the tray, the outer periphery of the side ring near the tray is an annular arc surface, the position of the annular arc surface corresponds to the curved side wall, and an annular streamlined exhaust channel is formed between the annular arc surface and the curved side wall.

6. The epitaxial wafer reaction apparatus according to claim 5, characterized in that, The curvature of the annular arc surface is the same as the curvature of the sidewall of the surface.

7. The epitaxial wafer reaction apparatus according to claim 5 or 6, characterized in that, The top of the side ring is flush with the surface of the tray.

8. A method for preparing an epitaxial wafer, characterized in that, The preparation method is carried out in the epitaxial wafer reaction apparatus according to any one of claims 5-7, and the preparation method includes: The substrate is placed on a tray, and the first and second nozzles spray different reactive gases onto the substrate surface. The tray drives the substrate to rotate so that the reactive gases are evenly distributed on the substrate surface. The substrate is heated by a heating element, and the reactive gases are deposited on the substrate surface to obtain the epitaxial wafer. The undeposited reactive gases are discharged through the exhaust channel.

9. The use of the epitaxial wafer reaction apparatus according to any one of claims 5-7, characterized in that, The epitaxial wafer reaction apparatus is used to prepare large-sized epitaxial wafers.

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