Vapor deposition equipment and its wafer temperature control method

Abstract

This invention provides a vapor deposition apparatus and a wafer temperature regulation method thereof, relating to the field of semiconductor equipment technology. The vapor deposition apparatus includes a tray, a chamber top cover, and a flow guide plate. The flow guide plate is disposed between the tray and the chamber top cover and faces the tray. A reaction zone is formed between the flow guide plate and the tray, and a temperature regulation zone is formed between the flow guide plate and the chamber top cover. A control unit adjusts the thermal conductivity of the heat transfer gas injected into the temperature regulation zone based on the radial temperature distribution of the wafer. The wafer includes a central region and an edge region surrounding the central region. The flow guide plate includes an annular central region corresponding to the position of the central region. Before and after adjusting the thermal conductivity of the heat transfer gas, the temperature change amplitude of the annular central region is greater than the temperature change amplitude of other regions of the flow guide plate. This invention can effectively improve the uniformity of wafer surface temperature, ensure that the physical and chemical properties of the thin film grown on the wafer surface meet the process requirements, and greatly improve the wafer processing yield.

Description

Technical Field

[0001] This invention relates to the field of semiconductor equipment technology, and in particular to a vapor deposition apparatus and a method for regulating wafer temperature. Prior Technology

[0002] GaN (Gallium Nitride)-based light-emitting diodes are widely used in semiconductor lighting and new display applications. MOCVD (Metal-Organic Chemical Vapor Deposition) equipment is widely used to produce III-V compound semiconductor materials, including GaN, due to its fast epitaxial growth speed and high material crystal quality.

[0003] The properties of GaN materials are closely related to their epitaxial growth temperature. To improve the uniformity of epitaxially grown GaN materials, precise control of the growth temperature is necessary. During the epitaxial growth of GaN materials, if the temperature within the reaction chamber is uneven, the stress generated by thermal mismatch can easily lead to wafer warping. The deformed wafer is heated unevenly, resulting in inconsistent growth rates of GaN materials on the wafer surface, leading to uneven deposition of GaN materials.

[0004] In existing processes, wafers are heated according to a pre-defined temperature field. If, during epitaxial growth, changes in the cavity environment cause the wafer surface temperature distribution to deviate from the target value, the characteristics of the GaN material on the wafer surface (such as wavelength and thickness) can only be characterized after the current furnace cycle is completed. Based on the characterization results, the process parameters are then corrected in the next growth furnace cycle. However, the uniformity of the GaN material grown in the current furnace cycle will deteriorate, significantly reducing the wafer processing yield. Summary of the Invention

[0005] The purpose of this invention is to provide a vapor deposition apparatus and method. This invention uses a flow guide plate to divide the reaction chamber of the vapor deposition apparatus into a reaction zone and a temperature control zone. During the process, the radial temperature distribution of the wafer is monitored in real time. Based on the monitoring results, the thermal conductivity of the heat transfer gas injected into the temperature control zone is adjusted in real time, achieving regional temperature regulation of the flow guide plate, and thus regional temperature regulation of the wafer. This invention improves the consistency of wafer surface temperature during the process, ensuring that the physical and chemical properties of the thin film grown on the wafer surface meet process requirements, effectively guaranteeing the yield of wafer processing.

[0006] To achieve the above objectives, the present invention provides a vapor deposition apparatus comprising a reaction chamber, wherein a tray for supporting multiple wafers is provided within the reaction chamber, the multiple wafers being arranged at least circumferentially along the tray, and the vapor deposition apparatus comprising:

[0007] A chamber top cover is disposed at the top of the reaction chamber;

[0008] A flow deflector is disposed between the tray and the chamber top cover and opposite to the tray; a reaction zone is formed between the flow deflector and the tray; a temperature regulating zone is formed between the flow deflector and the chamber top cover; a gap is formed between the outer edge of the flow deflector and the sidewall of the vapor deposition apparatus;

[0009] Temperature measuring device used to obtain the radial temperature distribution of the wafer;

[0010] An air inlet device, which passes through the center of the chamber top cover, is used to laterally inject heat transfer gas into the temperature regulation area; the heat transfer gas injected by the air inlet device flows horizontally outward along the radial direction of the guide plate and flows into the reaction chamber through the gap;

[0011] The control unit adjusts the thermal conductivity of the heat transfer gas injected into the temperature regulation region based on the radial temperature distribution results obtained by the temperature measuring device, thereby improving the uniformity of the wafer surface temperature;

[0012] The wafer includes a central region and an edge region surrounding the central region; the guide plate includes an annular central region corresponding to the position of the central region; before and after adjusting the thermal conductivity of the heat transfer gas, the temperature change of the annular central region is greater than the temperature change of other regions of the guide plate.

[0013] Optionally, if the temperature value of the central region is lower than the temperature value of the edge region, the control unit reduces the thermal conductivity of the heat transfer gas; if the temperature value of the central region is higher than the temperature value of the edge region, the control unit increases the thermal conductivity of the heat transfer gas.

[0014] Optionally, the control unit adjusts the thermal conductivity of the heat transfer gas by changing at least one of the components of the heat transfer gas and the volume fraction of each component.

[0015] Optionally, the components include a first heat transfer gas and a second heat transfer gas; the thermal conductivity of the second heat transfer gas is lower than that of the first heat transfer gas; if the temperature value of the central region is lower than that of the edge region, the control unit increases the volume fraction of the second heat transfer gas; if the temperature value of the central region is higher than that of the edge region, the control unit decreases the volume fraction of the second heat transfer gas.

[0016] Optionally, the component further includes a third heat transfer gas, the thermal conductivity of which is higher than that of the first heat transfer gas; if the temperature value of the central region is higher than that of the edge region, the control unit increases the volume fraction of the third heat transfer gas; if the temperature value of the central region is lower than that of the edge region, the control unit decreases the volume fraction of the third heat transfer gas.

[0017] Optionally, the control unit adjusts the thermal conductivity of the heat transfer gas only when the temperature difference between the central region and the edge region is greater than or equal to a set temperature difference threshold.

[0018] Optionally, a heating element is provided below the tray, and the control unit adjusts the heating power of the heating element according to the change in the thermal conductivity of the heat transfer gas.

[0019] Optionally, when the thermal conductivity increases, the heating power of the heating element is increased; when the thermal conductivity decreases, the heating power of the heating element is decreased.

[0020] Optionally, the vapor deposition apparatus further includes a lower temperature sensor located below the tray for measuring the temperature of the tray, and the control unit controls the heating power of the heating element based on the temperature of the tray.

[0021] Optionally, the air intake device is also used to inject process gas laterally into the reaction region.

[0022] Optionally, the vapor deposition apparatus further includes a vacuum pump for controlling the vacuum level of the reaction chamber.

[0023] Optionally, the air intake device is connected to multiple component supply sources through multiple supply pipelines, and each supply pipeline is equipped with a corresponding flow regulating valve; the control unit adjusts the thermal conductivity of the heat transfer gas by adjusting the valve opening of the flow regulating valve.

[0024] Optionally, the surface emissivity of the annular central region is greater than the surface emissivity of other regions of the guide plate; and / or, the gap between the annular central region and the chamber top cover is smaller than the gap between other regions and the chamber top cover.

[0025] Optionally, the top cover of the chamber is provided with a cooling fluid channel.

[0026] Optionally, the temperature measuring device includes a non-contact temperature sensor; the gap between the guide plate and the top cover of the chamber is between 0.1 and 5 mm; and the gap between the guide plate and the tray is between 10 and 30 mm.

[0027] This invention also provides a method for wafer temperature regulation in a vapor deposition apparatus. The vapor deposition apparatus includes a reaction chamber with a tray for holding multiple wafers arranged at least circumferentially along the tray. The vapor deposition apparatus includes: a chamber top cover disposed at the top of the reaction chamber; a flow guide plate disposed between the tray and the chamber top cover and opposite to the tray; a reaction region formed between the flow guide plate and the tray; a temperature regulation region formed between the flow guide plate and the chamber top cover; a gap between the outer edge of the flow guide plate and the side wall of the vapor deposition apparatus; and an inlet device passing through the center of the chamber top cover for laterally injecting heat transfer gas into the temperature regulation region. The heat transfer gas injected by the inlet device flows horizontally outward along the radial direction of the flow guide plate and flows into the reaction chamber through the gap. Each wafer includes a central region and an edge region surrounding the central region. The flow guide plate includes an annular central region corresponding to the position of the central region.

[0028] The wafer temperature control method includes:

[0029] Obtain the radial temperature distribution of the wafer;

[0030] Based on the obtained radial temperature distribution results, the thermal conductivity of the heat transfer gas injected into the temperature regulation region is adjusted to improve the uniformity of the wafer surface temperature; before and after adjusting the thermal conductivity of the heat transfer gas, the temperature change amplitude of the annular central region is greater than the temperature change amplitude of other regions of the guide plate.

[0031] Optionally, if the temperature value of the central region is lower than the temperature value of the edge region, the thermal conductivity of the heat transfer gas is reduced; if the temperature value of the central region is higher than the temperature value of the edge region, the thermal conductivity of the heat transfer gas is increased.

[0032] Optionally, the thermal conductivity of the heat transfer gas can be adjusted by changing at least one of the components of the heat transfer gas and the volume fraction of each component.

[0033] Optionally, the thermal conductivity of the heat transfer gas is adjusted only when the temperature difference between the central region and the edge region is greater than or equal to a set temperature difference threshold.

[0034] Optionally, the wafer temperature control method further includes adjusting the heating power of the heating element located below the tray according to the change in the thermal conductivity of the heat transfer gas.

[0035] Optionally, when the thermal conductivity increases, the heating power of the heating element is increased; when the thermal conductivity decreases, the heating power of the heating element is decreased.

[0036] Compared with prior art, the present invention has the following beneficial effects:

[0037] 1) This invention uses a flow guide plate to divide the reaction chamber of the vapor deposition equipment into a reaction zone and a temperature control zone (located above the reaction zone). During the process, the radial temperature distribution of the wafer is monitored in real time. Based on the monitoring results, the thermal conductivity of the heat transfer gas injected into the temperature control zone is adjusted in real time, achieving regional temperature regulation of the flow guide plate and thus regional temperature regulation of the wafer. This invention effectively improves the uniformity of wafer surface temperature, ensuring that the physical and chemical properties of the thin film grown on the wafer surface meet process requirements, and significantly improving wafer processing yield.

[0038] 2) In this invention, heat transfer gas can be injected laterally into the center of the temperature-regulating region (undivided). The heat transfer gas flows horizontally outward along the radial direction of the guide plate and flows into the reaction chamber from the outer periphery of the guide plate, and finally exits from the reaction chamber into the external space. The temperature-regulating region includes an annular intermediate temperature-regulating zone (corresponding to the annular central region of the guide plate). The flow rate of the heat transfer gas into and out of the temperature-regulating region is faster than the flow rate of the heat transfer gas in the intermediate temperature-regulating zone, thus the residence time of the heat transfer gas in the intermediate temperature-regulating zone is longer. When the thermal conductivity of the heat transfer gas is adjusted, the temperature change amplitude in the annular central region of the guide plate is greater than the temperature change amplitude in other regions of the guide plate, and consequently the temperature change amplitude in the wafer center region is greater than the temperature change amplitude in the wafer edge region. Therefore, when the temperature value in the wafer center region is higher or lower than the temperature value in the wafer edge region, increasing or decreasing the thermal conductivity of the heat transfer gas can ultimately improve the uniformity of the wafer surface temperature.

[0039] 3) When the temperature difference between the center region and the edge region of the wafer is less than the preset temperature difference threshold, the present invention also compensates the temperature of the wafer as a whole based on the measured tray temperature value, so that the temperature value of each region of the wafer falls within the temperature range required by the process, ensuring that the emission wavelength range of the material grown on the wafer surface meets the process requirements.

[0040] 4) In this invention, the gap between the annular middle region and the top cover of the chamber is smaller than the gap between the annular edge region and the annular center region and the top cover of the chamber; the surface emissivity of the annular middle region of the guide plate is greater than the surface emissivity of other regions of the guide plate, so that when the thermal conductivity of the heat transfer gas changes, the annular middle region has a larger temperature change range, which further improves the speed of regional adjustment of wafer temperature.

[0041] 5) In this invention, the heat transfer gas will not affect the airflow direction and distribution of the process gas, thus avoiding crosstalk to the process gas. This is beneficial for maintaining stable growth conditions for the wafer and ensuring controllable process within the reaction chamber. Simple Explanation of the Diagram

[0042] To more clearly illustrate the technical solution of the present invention, the drawings used in the description will be briefly introduced below. Obviously, the drawings described below are one embodiment of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without any further effort. Figure 1 is a schematic diagram of a vapor deposition apparatus; Figure 2 is a schematic diagram showing the wafer warping into a bowl shape; Figure 3 is a schematic diagram of a wafer warping into a dome shape; Figure 4 is a schematic diagram of the vapor deposition apparatus in Embodiment 1 of the present invention; Figure 5 is a schematic diagram of the projection of a single wafer onto the flow guide plate in Embodiment 1 of the present invention; Figure 6 is a schematic diagram illustrating how adjusting the thermal conductivity of the heat transfer gas can improve the uniformity of radial temperature distribution on a wafer when the temperature in the central region is lower than that in the edge region. Figure 7 is a schematic diagram illustrating how adjusting the thermal conductivity of the heat transfer gas can improve the uniformity of radial temperature distribution on a wafer when the temperature in the central region is higher than that in the edge region. Figure 8 is a schematic diagram of the radial temperature distribution of the guide plate before and after adjusting the volume fraction of the first heat transfer gas and the second heat transfer gas in one embodiment; Figure 8A is a schematic diagram showing the emission wavelength range of the thin film on the wafer surface before and after adjusting the volume fraction of the first heat transfer gas and the second heat transfer gas in one embodiment; Figure 9 is a schematic diagram of the radial temperature distribution of the guide plate before and after adjusting the volume fractions of the first and third heat transfer gases in another embodiment; Figure 10 is a flowchart of a wafer temperature control method used in a vapor deposition equipment. Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making progressive efforts are within the scope of protection of the present invention.

[0044] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0045] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0046] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0047] As used in this specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if detected [the described condition or event]" may be interpreted, depending on the context, as "once determined," "in response to determination," "once detected [the described condition or event]," or "in response to detection [the described condition or event]."

[0048] Furthermore, in the description of this application, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0049] Figure 1 is a schematic diagram of a vapor deposition apparatus 1 used for performing the MOCVD (Metal-organic Chemical Vapor Deposition) process. The vapor deposition apparatus 1 includes a reaction chamber 10. The reaction chamber 10 includes a chamber top cover 101, reaction chamber sidewalls 102, and a bottom plate 103. A tray 120 inside the reaction chamber 10 is mounted on a rotatable shaft 107. Along the circumferential direction of the tray 120, a plurality of recesses are provided on the upper surface of the tray 120, and a plurality of wafer carrier disks 121 for placing wafers W are respectively disposed in the plurality of said recesses.

[0050] The tray 120 and the wafer carrier tray 121 are typically sintered from powdered materials (such as graphite) and have good thermal conductivity. A heating device 150 is located below the tray 120, and the tray 120 transfers the heat radiated by the heating device 150 to the wafer carrier tray 121 and the wafer W, so that the wafer surface reaches the temperature required for the process.

[0051] An inlet device 110 penetrates the chamber top cover 101 and is used to laterally inject process gas into the reaction chamber 10. The process gas may include a carrier gas and a reactant gas, which may include Group III and Group V gases. In a typical metal-organic chemical vapor deposition process, the carrier gas may be nitrogen, hydrogen, or a mixture of nitrogen and hydrogen. A vacuum device 105 is located below the reaction chamber 10, through which unreacted process gas and reaction byproducts are discharged from the reaction chamber 10.

[0052] The tray 120 is driven to rotate around its center via shaft 107, which in turn drives the wafer carrier 121 to rotate around the center of the tray 120. In some embodiments, a driving gas channel (not shown in the figure) is also provided in the tray 120. Gas at a certain pressure is introduced between the wafer carrier 121 and the tray 120 through the driving gas channel, so that the wafer carrier 121 can be lifted by the gas and detached from the surface of the tray 120, suspending at a certain height and rotating around its center, so that the different types of process gases reaching the upper surface of the wafer are fully mixed. The process gases react at a specific temperature and deposit on the wafer surface to form a thin film of the desired material (e.g., GaN thin film). Among these, wafer temperature is one of the important factors affecting the deposition rate and uniformity of the material on the wafer surface.

[0053] During the manufacturing process, wafer W is prone to warping, mainly due to the following reasons: ① The high-temperature environment within the reaction chamber 10 affects the stress distribution and crystal structure inside wafer W, leading to warping. ② Heat transfer generated by gas flow within the reaction chamber 10, cooling channels in the reaction chamber sidewall 102 and / or lower base plate 103, the unavoidable presence of "cold spots" in the tray area directly above axis 107, and the wafer transfer port (not shown in the figure) located on the reaction chamber sidewall 102 all contribute to a complex thermodynamic environment within the reaction chamber 10, making wafer W prone to thermal mismatch. The stress generated by thermal mismatch can also cause wafer W to warp. ③ The stress of the material deposited on the wafer surface may also cause wafer W to warp.

[0054] As shown in Figure 1, wafer W includes a disk-shaped central region Wa and an edge region Wb surrounding the central region Wa. In Figure 2, the wafer edge warps upwards significantly, causing wafer W to warp into a bowl shape. The central region Wa is in direct contact with the wafer carrier disk 121 and therefore has a higher temperature, while the edge region Wb is not in direct contact with the wafer carrier disk 121 and therefore has a lower temperature. In Figure 3, when the wafer center warps upwards significantly, wafer W warps into a dome shape. The edge region Wb is in direct contact with the wafer carrier disk 121 and therefore has a higher temperature, while the central region Wa is not in direct contact with the wafer carrier disk 121 and therefore has a lower temperature. The temperature of the wafer surface determines the material deposition rate. When the temperature difference between the central region Wa and the edge region Wb is large, the uniformity of the material grown on the wafer surface will deteriorate.

[0055] The vapor deposition equipment 1 in Figure 1 cannot compensate for the temperature of each region of wafer W in real time and independently. Since the growth process is irreversible, the characteristics of the material grown on the wafer surface (such as wavelength, thickness, etc.) can only be characterized after the current furnace process is completed. Based on the characterization results, the process parameters are corrected in the next growth furnace, while the wafer yield of the current furnace is low.

[0056] This invention provides a vapor deposition apparatus and method. A flow guide plate divides the reaction chamber of the vapor deposition apparatus into a reaction zone and a temperature control zone. During the process, the radial temperature distribution of the wafer W is monitored in real time. Based on the monitoring results, the thermal conductivity of the heat transfer gas injected into the temperature control zone is adjusted in real time, achieving regional temperature regulation of the flow guide plate and thus regional temperature regulation of the wafer W. This invention improves the uniformity of wafer surface temperature, ensures that the physical and chemical properties of the materials grown on the wafer surface meet process requirements, and effectively guarantees the yield of wafer processing.

[0057] Figure 4 is a schematic diagram of the vapor deposition apparatus 2 in this embodiment, which includes a reaction chamber 20. A tray 220 is provided within the reaction chamber 20. Multiple wafer carrier disks 221 for supporting wafers W are placed on the upper surface of the tray 220 along its circumferential direction. By driving the tray 220 to rotate around its central axis and driving the wafer carrier disks 221 to rotate, the airflow environment on the upper surfaces of different wafers W is made more uniform. A heating element 250 (e.g., an induction heating coil or a resistance heater) is provided below the tray 220, and the heat radiated by the heating element 250 is transferred from the tray 220 to the wafer carrier disks 221 and the wafers W.

[0058] As shown in Figure 4, the vapor deposition apparatus 2 also includes: a chamber top cover 201, a baffle plate 280, a temperature measuring device, a control unit 260, and an air inlet device 210.

[0059] As shown in Figure 4, the chamber top cover 201 is located on top of the reaction chamber 20, and the reaction chamber 20 is formed by the chamber top cover 201, the bottom plate 203, and the reaction chamber sidewalls 202. In a preferred embodiment, cooling fluid channels (not shown in the figure) are also provided inside the chamber top cover 201 and the bottom plate 203 to reduce the temperature of the chamber top cover 201 and the bottom plate 203, making it difficult for the process gas on the surface of the chamber top cover 201 and the bottom plate 203 to reach the temperature required for the reaction. This greatly reduces the possibility of process gas deposition on the chamber top cover 201 and the bottom plate 203, and reduces the cleaning frequency of the reaction chamber 20. At the same time, it can also effectively reduce the particulate contamination of the wafer W caused by the detachment of deposits on the chamber top cover 201 and the bottom plate 203, and improve the yield of wafer processing.

[0060] As shown in Figure 4, the guide plate 280 (which has a disc-shaped structure) is disposed between the tray 220 and the chamber top cover 201 and is opposite to the tray 220. A reaction zone 20b is formed between the guide plate 280 and the tray 220, and a temperature regulating zone 20a is formed between the guide plate 280 and the chamber top cover 201. In some embodiments, the gap between the guide plate 280 and the chamber top cover 201 is between 0.1 and 5 mm; the gap between the guide plate 280 and the tray 220 is between 10 and 30 mm.

[0061] As shown in Figure 4, the air intake device 210 injects process gas laterally into the reaction area 20b through the center of the chamber top cover 201. When the process gas flows horizontally along the radial direction of the tray 220 across the upper surface of the wafer W to be processed, it will react at a specific temperature and deposit on the wafer W to form a thin film of the required material. The temperature of the wafer surface determines the rate and uniformity of material deposition.

[0062] As shown in Figure 4, the air intake device 210 also laterally injects heat transfer gas into the temperature control zone 20a to regulate the temperature of the guide plate 280. Heat transfer occurs between the guide plate 280 and the process gas in the reaction chamber 20, and between the process gas and the wafer W. It is worth noting that although in Figure 4, the air intake device 210 for injecting heat transfer gas and process gas is a single component, in other embodiments, the air intake device 210 can be composed of multiple components for injecting heat transfer gas and process gas respectively.

[0063] A gap j1 exists between the outer edge of the guide plate 280 and the side wall 202 of the reaction chamber, allowing the side of the temperature-regulating area away from the inlet device 210 to communicate with the reaction chamber 20. The heat transfer gas injected by the inlet device 210 flows horizontally outward (away from the inlet device 210) along the radial direction of the guide plate 280 and flows into the reaction chamber 20 through the gap j1. A vacuum device 205 is provided below the reaction chamber 20, through which process gases, reaction byproducts, and heat transfer gases that have not yet reacted are discharged from the reaction chamber 20. After entering the reaction chamber 20, the heat transfer gas flows downward along the inner side wall of the reaction chamber 20, without affecting the airflow direction and distribution of the process gases, avoiding crosstalk to the process gases, which is conducive to maintaining stable growth conditions for the wafer W and ensuring process controllability within the reaction chamber 20; it can also form an air curtain on the inner side wall of the reaction chamber 20 to prevent process gases from depositing on the inner side wall.

[0064] The temperature measuring device penetrates the chamber top cover 201 and the guide plate 280 to obtain the radial temperature distribution of wafer W. As shown in Figure 4, wafer W includes a central region Wa and an edge region Wb surrounding the central region Wa. In this embodiment, the temperature measuring device includes two non-contact temperature sensors 270a and 270b, which are used to measure the temperature of the central region Wa and the edge region Wb, respectively. In other embodiments, a thermal imager or a temperature measuring device mounted on the wafer carrier 221 can be used to measure the temperature of the central region Wa and the edge region Wb. Wafers W in the same growth furnace are located in the same thermodynamic environment. By measuring the temperature of the central region Wa and the edge region Wb of a single wafer W, the radial temperature distribution of all wafers W in the same growth furnace can be determined.

[0065] Figure 5 is a schematic diagram of the projection of a single wafer W onto the flow guide plate 280. As shown in Figure 5, along the radial direction of the flow guide plate 280, from the inside out, the flow guide plate 280 includes a concentric annular central region 280c, an annular intermediate region 280a, and an annular edge region 280b. The annular intermediate region 280a corresponds to the central region Wa in position; it can be understood that the projection of the central region Wa onto the flow guide plate 280 falls within the annular intermediate region 280a.

[0066] Optionally, as shown in Figure 4, three non-contact temperature sensors 290a, 290b, and 290c, which pass through the chamber top cover 201, measure the temperature values ​​of the annular intermediate region 280a, the annular edge region 280b, and the annular central region 280c, respectively. The inventors discovered that when the temperature value of the annular intermediate region 280a is higher or lower than the temperature values ​​of the annular central region 280c and the annular edge region 280b, the temperature value of the central region Wa is also higher or lower than the temperature values ​​of the annular central region 280c and the edge region 280b.

[0067] The control unit 260 adjusts the thermal conductivity of the heat transfer gas injected into the temperature-adjusting region based on the radial temperature distribution of the wafer W obtained by the non-contact temperature sensors 270a and 270b. Before and after adjusting the thermal conductivity of the heat transfer gas, the temperature change in the annular central region 280a is greater than the temperature change in other regions of the guide plate 280.

[0068] As shown in Figure 4, the temperature regulation zone 20a includes an annular intermediate temperature regulation zone 20a_1, which corresponds to the annular intermediate zone 280a of the guide plate 280. Due to its proximity to the air inlet device 210 and the air extraction device 205, the flow rate of the heat transfer gas into and out of the temperature regulation zone 20a is faster than that in the intermediate temperature regulation zone 20a_1, resulting in a longer residence time of the heat transfer gas in the intermediate temperature regulation zone 20a_1. Because of the longer residence time of the heat transfer gas in the intermediate temperature regulation zone 20a_1, a better temperature regulation effect can be achieved in the annular intermediate zone 280a. When adjusting the thermal conductivity of the heat transfer gas, the temperature change amplitude of the annular intermediate zone 280a is greater than that of the annular central zone 280c and the annular edge zone 280b. The inventors discovered that, simultaneously, the temperature change amplitude of the central zone Wa is also greater than that of the edge zone Wb. In other words, this invention discovers that by adjusting the thermal conductivity of the heat transfer gas injected into the temperature-regulating region, the temperature of the guide plate 280 can be adjusted in different regions, thereby effectively achieving temperature adjustment of the wafer W in different regions. It should be noted that due to the complex flow and temperature field environment within the chamber, those skilled in the art cannot predict the feasibility of this adjustment method without sufficient experimental testing.

[0069] The longer the residence time of the heat transfer gas in the intermediate temperature control zone 20a_1, the greater the temperature control range that can be achieved in the annular intermediate region 280a. In another embodiment, the gap between the annular intermediate region 280a and the chamber top cover 201 is smaller than the gaps between the annular edge region 280b and the annular center region 280c and the chamber top cover 201. For example, the surface of the chamber top cover 201 opposite to the guide plate 280 is a convex arc surface. When the thermal conductivity of the heat transfer gas is adjusted, the temperature change range of the annular intermediate region 280a is further made greater than the temperature change range of the annular center region 280c and the annular edge region 280b.

[0070] The higher the surface emissivity of the guide plate 280, the better its heat transfer effect. In another embodiment, the surface emissivity of the annular central region 280a is greater than that of other regions of the guide plate 280, further improving the temperature regulation effect on the annular central region 280a. When the thermal conductivity of the heat transfer gas is adjusted, the temperature change range of the annular central region 280a is further made greater than that of the annular central region 280c and the annular edge region 280b.

[0071] Figures 6 and 7 illustrate the radial temperature distribution (from the wafer center to the wafer edge) of wafer W and the radial temperature distribution (from the projection point of the wafer center onto the guide plate 280 to the edge of the guide plate) of the flow guide 280 before and after adjusting the thermal conductivity of the heat transfer gas under two different scenarios. As shown in Figures 6 and 7, let d be the horizontal position of the wafer center, r be the radius of wafer W, and r1 be the radius of the disk-shaped central region Wa. Along the radial direction of the flow guide 280, the distance from the projection point of the wafer center onto the flow guide 280 to the edge of the flow guide 280 is Rd.

[0072] In one scenario, before adjusting the thermal conductivity of the heat transfer gas, refer to the lower short line segment of Figure 6. The temperature value of the central region Wa (only a portion is shown in Figure 6) is lower than the temperature value of the edge region Wb. Refer to the lower long line segment of Figure 6. The temperature value of the annular central region 280a (only a portion is shown in Figure 6) is lower than the temperature values ​​of other regions of the guide vane 280 (only the annular edge region 280b is shown in Figure 6).

[0073] Control unit 260 reduces the thermal conductivity of the heat transfer gas. Referring to the upper long line segment of Figure 6, the overall temperature of the guide plate 280 increases, with the temperature increase in the annular central region 280a exceeding that of other areas of the guide plate 280. After adjusting the thermal conductivity of the heat transfer gas, referring to the uppermost short line segment in Figure 6, the overall temperature of the wafer W also increases, with the temperature increase in the central region Wa exceeding that in the edge region Wb. This reduces the temperature difference between the central region Wa and the edge region Wb, effectively improving the uniformity of the wafer surface temperature and ensuring the growth of a thin film with uniform properties (wavelength, thickness, composition, etc.) on the wafer surface.

[0074] In a preferred embodiment, the control unit 260 adjusts the thermal conductivity of the heat transfer gas only when the temperature difference between the central region Wa and the edge region Wb is greater than or equal to a set temperature difference threshold. The temperature threshold may be, for example, 3°C.

[0075] In another scenario, before adjusting the thermal conductivity of the heat transfer gas, refer to the shortest line segment at the top of Figure 7. The temperature value of the central region Wa (only a portion is shown in Figure 7) is higher than the temperature value of the edge region Wb. Referring to the upper long line segment of the two long lines in Figure 7, the temperature value of the annular central region 280a (only a portion is shown in Figure 7) is higher than the temperature values ​​of other regions of the guide vane 280 (only the annular edge region 280b is shown in Figure 7).

[0076] Control unit 260 increases the thermal conductivity of the heat transfer gas (refer to the long line segment at the bottom of Figure 7), resulting in an overall temperature reduction in the guide plate 280, with a greater temperature reduction in the annular central region 280a than in other areas of the guide plate 280. Referring to the lower short line segment of Figure 7, after adjusting the thermal conductivity of the heat transfer gas, the overall temperature of wafer W also decreases, with a greater temperature reduction in the central region Wa than in the edge region Wb. Therefore, the temperature difference between the central region Wa and the edge region Wb is reduced, effectively improving the uniformity of the wafer surface temperature.

[0077] As shown in Figure 4, the air intake device 210 is connected to multiple component supply sources 230 through multiple supply pipelines, each of which is equipped with a corresponding flow regulating valve 231. The control unit 260 adjusts the opening degree of each flow regulating valve 231 to change at least one of the components of the heat transfer gas and the volume fraction of each component, thereby adjusting the thermal conductivity of the heat transfer gas.

[0078] The components include a first heat transfer gas and a second heat transfer gas, wherein the thermal conductivity of the second heat transfer gas is lower than that of the first heat transfer gas. If the temperature value of the central region Wa is lower than the temperature value of the edge region Wb, the control unit 260 increases the volume fraction of the second heat transfer gas to reduce its thermal conductivity. If the temperature value of the central region Wa is higher than the temperature value of the edge region Wb, the control unit 260 decreases the volume fraction of the second heat transfer gas to increase its thermal conductivity.

[0079] In one embodiment, as shown in Figure 8, nitrogen (N2) is used as the first heat transfer gas and argon (Ar) is used as the second heat transfer gas. The three solid dots in Figure 8 represent three temperature measurement points on the annular central region 280c, the annular middle region 280a, and the annular edge region 280b, respectively.

[0080] Before the control unit 260 adjusts the thermal conductivity of the heat transfer gas, 3L of nitrogen (N2) and 2L of argon (Ar) are introduced into the temperature-controlled zone per minute. As shown by the broken line at the top of Figure 8, the temperature value of the annular middle region 280a is the highest at this time. The temperature difference between the annular middle region 280a and the annular edge region 280b reaches 136.8℃.

[0081] After the control unit 260 adjusts the thermal conductivity of the heat transfer gas, only 5L of nitrogen gas is introduced into the temperature-controlled area per minute. As shown by the broken line at the bottom of Figure 8, the overall temperature of the guide vane 280 decreases, with the largest temperature drop occurring in the annular central region 280a. The temperature difference between the annular central region 280a and the annular edge region 280b is reduced to 108.3℃, effectively altering the radial temperature distribution of the guide vane 280.

[0082] To produce qualified materials on the wafer surface, the emission wavelength range of the thin film on the wafer surface needs to reach 463nm~465nm (also known as the target wavelength range). Before adjusting the thermal conductivity of the heat transfer gas, as shown by the lower curve in Figure 8A, the wavelength range of the thin film on the wafer surface was 459nm~461nm, which not only deviated from the target wavelength range, but also resulted in a 2nm difference in emission wavelength between the edge region Wb surface film and the central region Wa surface film. After adjusting the thermal conductivity of the heat transfer gas, as shown by the upper curve in Figure 8A, the wavelength range of the thin film on the wafer surface was 464nm~465nm, which not only fell within the target wavelength range, but also reduced the wavelength difference between the edge region Wb surface film and the central region Wa surface film to 1nm, greatly improving the yield of wafer W production.

[0083] In another embodiment, the component further includes a third heat transfer gas, the third heat transfer gas having a higher thermal conductivity than the first heat transfer gas. If the temperature value of the central region Wa is higher than the temperature value of the edge region Wb, the control unit 260 increases the volume fraction of the third heat transfer gas; if the temperature value of the central region Wa is lower than the temperature value of the edge region, the control unit 260 decreases the volume fraction of the third heat transfer gas.

[0084] In another embodiment, as shown in Figure 9, nitrogen (N2) is used as the first heat transfer gas and hydrogen (H2) is used as the third heat transfer gas. The three solid dots in Figure 9 represent three temperature measurement points on the annular central region 280c, the annular middle region 280a, and the annular edge region 280b, respectively.

[0085] Before the control unit 260 adjusts the thermal conductivity of the heat transfer gas, only 5L of nitrogen gas is introduced into the temperature-controlled area per minute. As shown by the broken line at the top of Figure 9, at this time, the temperature value of the annular middle region 280a is the highest, and the temperature difference between the annular middle region 280a and the annular edge region 280b reaches 115.5℃.

[0086] After the control unit 260 adjusts the thermal conductivity of the heat transfer gas, it introduces 4.5L of nitrogen (N2) and 0.5L of hydrogen (H2) into the temperature-controlled area per minute. Referring to the middle line of the three broken lines in Figure 9, the overall temperature of the guide vane 280 decreases, with the largest temperature drop in the annular central region 280a. The temperature difference between the annular central region 280a and the annular edge region 280b decreases to 109.1℃.

[0087] The control unit 260 further increases the volume fraction of hydrogen (H2), introducing 4L of nitrogen (N2) and 1L of hydrogen (H2) into the temperature-controlled zone per minute. As shown by the broken line at the bottom of Figure 9, the overall temperature of the guide vane 280 further decreases, and the temperature difference between the annular middle region 280a and the annular edge region 280b further decreases to 84°C, effectively changing the radial temperature distribution of the guide vane 280.

[0088] Only when the temperature of all regions of wafer W falls within the required process temperature range (also known as the target temperature range) can a thin film of the desired quality be obtained on the wafer surface. The radial temperature distribution of the guide plate 280 can be adjusted by regulating the thermal conductivity of the heat transfer gas, thereby improving the uniformity of the radial temperature distribution of wafer W. However, in some cases, increasing / decreasing the thermal conductivity of the heat transfer gas may cause the overall temperature of wafer W to be lower / higher than the lower / upper limit of the target temperature range. Although a thin film of uniform thickness can be grown on the wafer surface, the wavelength range of the film deviates from the target wavelength range.

[0089] In this embodiment, the control unit 260 also adjusts the heating power of the heating element 250 according to the change in the thermal conductivity of the heat transfer gas, thereby compensating for the overall temperature of the wafer W and ultimately ensuring that the wavelength range of the thin film on the wafer surface falls within the target wavelength range. When the thermal conductivity of the heat transfer gas increases, the control unit 260 increases the heating power of the heating element 250 to increase the overall temperature of the wafer W; when the thermal conductivity of the heat transfer gas decreases, the control unit 260 decreases the heating power of the heating element 250 to decrease the overall temperature of the wafer W.

[0090] The vapor deposition apparatus 2 also includes a lower temperature sensor 240, located below the tray 220, for measuring the temperature of the tray 220. The control unit 260 controls the heating power of the heating element 250 based on the temperature of the tray 220 to accurately compensate for the overall temperature of the wafer W.

[0091] In one embodiment, after the thermal conductivity of the heat transfer gas is increased, the temperature difference between the central region Wa and the edge region Wb is less than the set temperature difference threshold, but the measured temperature value of the central region Wa (or the edge region Wb) is 10°C lower than the lower limit of the target temperature range. At this time, the control unit 260 increases the heating power of the heating element 250 until the measured temperature value of the central region Wa (or the edge region Wb) is within the target temperature range.

[0092] In another embodiment, after the thermal conductivity of the heat transfer gas decreases, the temperature difference between the central region Wa and the edge region Wb is less than the set temperature difference threshold, but the measured temperature value of the central region Wa (or the edge region Wb) is 10°C higher than the upper limit of the target temperature range. At this time, the control unit 260 reduces the heating power of the heating element 250 until the measured temperature value of the central region Wa (or the edge region Wb) is within the target temperature range.

[0093]

[0094] This invention also provides a wafer temperature control method for a vapor deposition apparatus, applicable to the vapor deposition apparatus 2 shown in Figure 4. The vapor deposition apparatus 2 includes a reaction chamber 20, within which a tray 220 for supporting a wafer W is provided. A chamber top cover 201 is disposed on top of the reaction chamber 20. A flow guide plate 280 is disposed between the tray 220 and the chamber top cover 201, and opposite to the tray 220. A reaction region 20b is formed between the flow guide plate 280 and the tray 220, and a temperature control region 20a is formed between the flow guide plate 280 and the chamber top cover 201. A gap j1 is formed between the outer edge of the flow guide plate 280 and the side wall of the vapor deposition apparatus 2. The vapor deposition apparatus also includes an inlet device 210, which passes through the center of the chamber top cover 201 and is used to laterally inject heat transfer gas into the temperature-controlled region 20a. The heat transfer gas 20a injected by the inlet device 210 flows horizontally outward along the radial direction of the guide plate 280 and flows into the reaction chamber 20 from the gap j1. The wafer W includes a central region Wa and an edge region Wb surrounding the central region Wa, and the guide plate 280 includes an annular intermediate region 280a corresponding to the position of the central region Wa.

[0095] As shown in Figure 10, the wafer temperature regulation method includes the following steps:

[0096] S100, Obtain the radial temperature distribution of wafer W;

[0097] S200: Based on the obtained radial temperature distribution results, adjust the thermal conductivity of the heat transfer gas injected into the temperature regulation zone 20a; before and after adjusting the thermal conductivity of the heat transfer gas, the temperature change amplitude of the annular middle region 280a is greater than the temperature change amplitude of other regions of the guide plate 280;

[0098] In step S200, adjusting the thermal conductivity of the heat transfer gas injected into the temperature-regulating region 20a based on the acquired radial temperature distribution results specifically includes:

[0099] If the temperature value of the central region Wa is lower than that of the edge region Wb, the thermal conductivity of the heat transfer gas decreases; if the temperature value of the central region Wa is higher than that of the edge region Wb, the thermal conductivity of the heat transfer gas increases.

[0100] The thermal conductivity of the heat transfer gas can be adjusted by changing at least one of the components and the volume fraction of each component. In a preferred embodiment, the thermal conductivity of the heat transfer gas is adjusted only when the temperature difference between the central region Wa and the edge region Wb is greater than or equal to a set temperature difference threshold.

[0101] S300: Adjust the heating power of the heating element 250 located below the tray 220 according to the change in the thermal conductivity of the heat transfer gas.

[0102] In step S300, when the thermal conductivity of the heat transfer gas increases, the heating power of the heating element 250 is increased; when the thermal conductivity of the heat transfer gas decreases, the heating power of the heating element is decreased.

[0103] Steps S100 and S200 are used to improve the uniformity of the surface temperature of wafer W, and step S300 is used to compensate the overall wafer temperature so that the temperature of each region of wafer W falls within the target temperature range.

[0104] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0105] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of protection of the claims.

[0106] 1, 2: Vapor deposition equipment 10, 20: Reaction chamber 20a: Temperature control zone 20a_1: Intermediate Temperature Control Zone 20b: Reaction Zone 101: Chamber top cover 102: Sidewall of the reaction chamber 103: Bottom plate 105: Air extraction device 107: Axis 110: Air intake device 120: Pallet 121: Wafer carrier disk 150: Heating device 201: Chamber top cover 202: Reaction chamber sidewall 203: Base Plate 205: Air extraction device 210: Air intake device 220: Pallet 221: Wafer carrier disk 230: Component supply source 231: Flow regulating valve 240: Lower temperature measuring instrument 250: Heating element 260: Control Unit 270a, 270b: Temperature sensors 280: Deflector 280a: Middle area 280b: Edge region 280c: Central Area 290a, 290b, 290c: Temperature sensors S100, S200, S300: Steps d: Horizontal position j1: gap r, r1: radius W: Wafer Wa: Central Area Wb: Edge region

Claims

1. A vapor deposition apparatus comprising a reaction chamber, wherein a tray for holding a plurality of wafers is provided within the reaction chamber, the plurality of wafers being arranged at least circumferentially along the tray, wherein, The vapor deposition apparatus includes: a chamber top cover disposed on top of the reaction chamber; a flow guide plate disposed between the tray and the chamber top cover and opposite to the tray; a reaction zone is formed between the flow guide plate and the tray; a temperature regulation zone is formed between the flow guide plate and the chamber top cover; a gap exists between the outer edge of the flow guide plate and the sidewall of the vapor deposition apparatus; a temperature measuring device for acquiring the radial temperature distribution of the wafer; an air inlet device passing through the center of the chamber top cover for laterally injecting heat transfer gas into the temperature regulation zone; the heat transfer gas injected by the air inlet device flows horizontally outward along the radial direction of the flow guide plate and flows into the reaction chamber through the gap; and a control unit that adjusts the thermal conductivity of the heat transfer gas injected into the temperature regulation zone based on the radial temperature distribution result acquired by the temperature measuring device, thereby improving the uniformity of the wafer surface temperature. The wafer includes a central region and an edge region surrounding the central region; the guide plate includes an annular central region corresponding to the position of the central region; before and after adjusting the thermal conductivity of the heat transfer gas, the temperature change of the annular central region is greater than the temperature change of other regions of the guide plate.

2. The vapor deposition apparatus as claimed in claim 1, wherein, If the temperature value of the central region is lower than the temperature value of the edge region, the control unit reduces the thermal conductivity of the heat transfer gas; if the temperature value of the central region is higher than the temperature value of the edge region, the control unit increases the thermal conductivity of the heat transfer gas.

3. The vapor deposition apparatus as described in claim 2, wherein, The control unit adjusts the thermal conductivity of the heat transfer gas by changing at least one of the components of the heat transfer gas and the volume fraction of each component.

4. The vapor deposition apparatus as described in claim 3, wherein, The components include a first heat transfer gas and a second heat transfer gas; the thermal conductivity of the second heat transfer gas is lower than that of the first heat transfer gas; if the temperature value of the central region is lower than the temperature value of the edge region, the control unit increases the volume fraction of the second heat transfer gas; if the temperature value of the central region is higher than the temperature value of the edge region, the control unit decreases the volume fraction of the second heat transfer gas.

5. The vapor deposition apparatus as described in claim 4, wherein, The composition also includes a third heat transfer gas, the thermal conductivity of which is higher than that of the first heat transfer gas; if the temperature value of the central region is higher than that of the edge region, the control unit increases the volume fraction of the third heat transfer gas; if the temperature value of the central region is lower than that of the edge region, the control unit decreases the volume fraction of the third heat transfer gas.

6. The vapor deposition apparatus as described in any one of claims 1 to 5, wherein, The control unit adjusts the thermal conductivity of the heat transfer gas only when the temperature difference between the central region and the edge region is greater than or equal to a set temperature difference threshold.

7. The vapor deposition apparatus as described in any one of claims 1 to 5, wherein, A heating element is provided below the tray, and the control unit adjusts the heating power of the heating element according to the change in the thermal conductivity of the heat transfer gas.

8. The vapor deposition apparatus as described in claim 7, wherein, When the thermal conductivity increases, the heating power of the heating element is increased; when the thermal conductivity decreases, the heating power of the heating element is decreased.

9. The vapor deposition apparatus of claim 8 further includes a lower temperature sensor located below the tray for measuring the temperature of the tray, and the control unit controls the heating power of the heating element based on the temperature of the tray.

10. The vapor deposition apparatus as claimed in claim 1, wherein, The air intake device is also used to inject process gas laterally into the reaction zone.

11. The vapor deposition apparatus of claim 10 further includes a vacuum pump for controlling the vacuum level of the reaction chamber.

12. The vapor deposition apparatus as claimed in claim 10, wherein, The air intake device is connected to multiple component supply sources through multiple supply pipelines, and each supply pipeline is equipped with a corresponding flow regulating valve; the control unit adjusts the thermal conductivity of the heat transfer gas by adjusting the valve opening of the flow regulating valve.

13. The vapor deposition apparatus as claimed in claim 1, wherein, The surface emissivity of the annular central region is greater than that of other regions of the guide plate; and / or, the gap between the annular central region and the chamber top cover is smaller than the gap between other regions and the chamber top cover.

14. The vapor deposition apparatus as claimed in claim 1, wherein, The top cover of the chamber is equipped with a cooling fluid channel.

15. The vapor deposition apparatus as claimed in claim 1, wherein, The temperature measuring device includes a non-contact temperature sensor; the gap between the flow guide plate and the top cover of the chamber is between 0.1 and 5 mm; the gap between the flow guide plate and the tray is between 10 and 30 mm.

16. A method for controlling wafer temperature in a vapor deposition apparatus, wherein, The vapor deposition apparatus includes a reaction chamber with a tray for holding multiple wafers arranged at least circumferentially along the tray. The apparatus includes: a chamber top cover disposed at the top of the reaction chamber; a flow guide plate disposed between the tray and the chamber top cover and opposite to the tray; a reaction region formed between the flow guide plate and the tray; a temperature regulation region formed between the flow guide plate and the chamber top cover; a gap between the outer edge of the flow guide plate and the sidewall of the vapor deposition apparatus; and an inlet device penetrating the center of the chamber top cover for laterally injecting heat transfer gas into the temperature regulation region. The heat transfer gas injected by the inlet device flows horizontally outward along the radial direction of the flow guide plate and flows into the reaction chamber through the gap. Each wafer includes a central region and an edge region surrounding the central region. The flow guide plate includes an annular central region corresponding to the position of the central region. The wafer temperature regulation method includes: acquiring the radial temperature distribution of the wafer. Based on the obtained radial temperature distribution results, the thermal conductivity of the heat transfer gas injected into the temperature regulation region is adjusted to improve the uniformity of the wafer surface temperature; before and after adjusting the thermal conductivity of the heat transfer gas, the temperature change amplitude of the annular central region is greater than the temperature change amplitude of other regions of the guide plate.

17. The wafer temperature control method for a vapor deposition apparatus as described in claim 16, wherein, If the temperature value of the central region is lower than that of the edge region, the thermal conductivity of the heat transfer gas is reduced; if the temperature value of the central region is higher than that of the edge region, the thermal conductivity of the heat transfer gas is increased.

18. The wafer temperature control method for a vapor deposition apparatus as described in claim 17, wherein, The thermal conductivity of the heat transfer gas is adjusted by changing at least one of the components and volume fractions of the components.

19. A wafer temperature control method for a vapor deposition apparatus as described in claim 17 or 18, wherein, The thermal conductivity of the heat transfer gas is adjusted only when the temperature difference between the central region and the edge region is greater than or equal to a set temperature difference threshold.

20. A wafer temperature control method for a vapor deposition apparatus as described in any one of claims 16-18, wherein, The wafer temperature control method further includes adjusting the heating power of the heating element located below the tray according to the change in the thermal conductivity of the heat transfer gas.

21. The wafer temperature control method for a vapor deposition apparatus as described in claim 20, wherein, When the thermal conductivity increases, the heating power of the heating element is increased; when the thermal conductivity decreases, the heating power of the heating element is decreased.

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