Epitaxial growth method and epitaxial wafer

Abstract

The embodiment of the invention discloses an epitaxial growth method and an epitaxial wafer. The epitaxial growth method comprises the following steps: placing a substrate on a base of a reaction chamber; auxiliary hydrogen is introduced into the area, located below the base, of the reaction cavity through an auxiliary gas inlet; heating the reaction chamber so as to bake the reaction chamber at a preset first temperature; and introducing a reaction gas into the reaction chamber through a main gas inlet so as to form an epitaxial layer on the substrate through a vapor deposition reaction.

Description

Technical Field

[0001] The disclosed embodiments relate to the field of semiconductor processing technology, and more particularly to an epitaxial growth method and an epitaxial wafer. Background Art

[0002] The epitaxial growth process is to use a polished wafer as a substrate to grow an epitaxial layer with controllable resistivity and thickness, and without crystal native particles (COP) defects and oxygen precipitation on it under certain conditions. The epitaxial growth process mainly includes vacuum epitaxial deposition process, vapor phase epitaxial deposition process and liquid phase epitaxial deposition process. Among them, the vapor phase epitaxial deposition process is to obtain an epitaxial layer by reacting silicon source gas with hydrogen in a high temperature environment to generate silicon atoms and depositing silicon atoms on the surface of the substrate, and at the same time, introducing doping gas to dope the epitaxial layer to obtain the required resistivity. If not otherwise specified, the epitaxial growth mentioned in this disclosure refers to the epitaxial growth completed by the vapor phase epitaxial deposition process. The resistivity uniformity of the epitaxial layer of the epitaxial wafer is one of the important indicators for evaluating the performance of the epitaxial wafer, but the resistivity uniformity of the epitaxial layer of the epitaxial wafer currently manufactured is poor. Summary of the invention

[0003] In view of this, the embodiments of the present disclosure are intended to provide an epitaxial growth method and an epitaxial wafer, which can respectively increase the resistivity of the central region and the edge region of the epitaxial layer of the epitaxial wafer, and improve the resistivity uniformity of the epitaxial layer.

[0004] The technical solution of the embodiment of the present disclosure is implemented as follows: In a first aspect, an embodiment of the present disclosure provides an epitaxial growth method, the epitaxial growth method comprising: placing a substrate on a susceptor in a reaction chamber; introducing auxiliary hydrogen gas into the area of ​​the reaction chamber below the susceptor through the secondary gas inlet; Raising the temperature of the reaction chamber to bake the reaction chamber at a predetermined first temperature; and Introducing a reaction gas into the reaction chamber through a main gas inlet to form an epitaxial layer on the substrate through a vapor deposition reaction; Wherein, during the vapor deposition reaction, the flow rate of the auxiliary hydrogen gas is less than or equal to 12 slm, and the first heating power ratio corresponding to the central area of ​​the substrate is reduced to less than the set first benchmark heating power ratio, and the difference between the first heating power ratio after the reduction and the first benchmark heating power ratio is in the range of 2% to 6%, and the second heating power ratio corresponding to the central area of ​​the substrate is reduced to less than the set second benchmark heating power ratio, and the difference between the second heating power ratio after the reduction and the second benchmark heating power ratio is in the range of 0.5% to 1.5%; wherein, the first heating power ratio is the heating power ratio of the first inner lamp group unit in the upper lamp group unit above the reaction chamber; the second heating power ratio is the heating power ratio of the second inner lamp group unit in the lower lamp group unit below the reaction chamber.

[0005] In some examples, during the vapor deposition reaction, the flow rate of the auxiliary hydrogen gas is 10 slm to 12 slm.

[0006] In some examples, when the temperature of the reaction chamber is increased, the temperature increase rate of the reaction chamber is 2.5° C. / s to 3.5° C. / s.

[0007] In some examples, during the baking, the flow rate of the auxiliary hydrogen gas is 17 slm to 23 slm.

[0008] In some examples, after the reaction chamber is heated to bake the reaction chamber at a predetermined first temperature, an etching gas is introduced into the reaction chamber through the main gas inlet at a predetermined second temperature to etch the surface of the substrate; wherein the second temperature is less than the first temperature.

[0009] In some examples, during the etching, the flow rate of the etching gas is 1.5 slm to 2.5 slm, and the duration of the etching is 10 s to 30 s.

[0010] In some examples, during the etching, the flow rate of the auxiliary hydrogen gas is 17 slm to 23 slm.

[0011] In some examples, during the baking, a doping gas in the reaction gas is introduced into an auxiliary input line to purge the auxiliary input line.

[0012] In some examples, during the vapor deposition reaction, the reaction gas is supplied to a main input pipeline, and the reaction gas is introduced into the reaction chamber through the main gas inlet.

[0013] In a second aspect, an embodiment of the present disclosure provides an epitaxial wafer, wherein the epitaxial wafer is prepared according to the epitaxial growth method according to any one of claims 1 to 10, and the resistivity uniformity of the epitaxial layer of the epitaxial wafer is less than 3.0%.

[0014] The disclosed embodiments provide an epitaxial growth method and an epitaxial wafer; during the vapor deposition reaction, the flow rate of the auxiliary hydrogen gas is controlled to be less than or equal to 12 slm, and the first heating power ratio corresponding to the central area of ​​the substrate is reduced to less than the set first reference heating power ratio, and the difference between the reduced first heating power ratio and the first reference heating power ratio is in the range of 2% to 6%, and the second heating power ratio corresponding to the central area of ​​the substrate is reduced to less than the set second reference heating power ratio, and the difference between the reduced second heating power ratio and the second reference heating power ratio is in the range of 0.5% to 1.5%, so as to increase the resistivity of the epitaxial layer of the epitaxial wafer corresponding to the central area and the edge area respectively, and improve the resistivity uniformity of the epitaxial layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the structure of an epitaxial wafer; Figure 2 It is a structural schematic diagram of an epitaxial growth device in the related art; Figure 3 is another structural schematic diagram of an epitaxial growth device in the related art; Figure 4 It is another structural schematic diagram of an epitaxial growth device in the related art; Figure 5 It is a schematic diagram of the epitaxial growth process in the related art; Figure 6 A schematic diagram of a method for detecting resistivity uniformity of an epitaxial layer provided in an embodiment of the present disclosure; Figure 7 A schematic diagram of a process flow of an epitaxial growth method provided in an embodiment of the present disclosure; Figure 8 A schematic diagram comparing resistivity changes at various points of an epitaxial layer of an epitaxial wafer provided in an embodiment of the present disclosure; Fig. 9 A schematic diagram comparing resistivity changes at various points of an epitaxial layer of an epitaxial wafer provided in yet another embodiment of the present disclosure; Fig.10 A schematic diagram comparing the change in resistivity uniformity of the epitaxial layer of the epitaxial wafer provided in the embodiment of the present disclosure; Fig.11 A schematic diagram of the epitaxial growth process provided for an embodiment of the present disclosure. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure.

[0017] It should be noted that, for the sake of clarity, not all features of a specific implementation are described and illustrated in the specification and drawings. Furthermore, in order to avoid unnecessary details that obscure the technical solution focused on by the present disclosure, only the device structure and method steps closely related to the technical solution of the present disclosure are described and illustrated in the specification and drawings, while other details that are not closely related to the technical content of the present disclosure and are known to those skilled in the art are omitted.

[0018] In addition, unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The words "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, the words "include" or "comprise" and the like mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0019] In this disclosure, Figure 1 As shown, the substrate W for manufacturing epitaxial wafers includes a central region W1 and an edge region W2 located outside the central region W1. Further, the central region W1 is circular in shape, and the edge region W2 is annular in shape, and the central region W1 and the edge region W2 are concentrically arranged.

[0020] See also Figures 2 to 4 , which shows a schematic structural diagram of an epitaxial growth device 1 in the related art. The epitaxial growth device 1 may include: The base 10 is used to support the substrate W.

[0021] The support frame 20 is used to support the susceptor 10 and drive the susceptor 10 to rotate around the central axis X at a certain speed during the epitaxial growth process. During the rotation of the susceptor 10, the substrate W rotates around the central axis X together with the susceptor 10, that is, the substrate W remains stationary relative to the susceptor 10. Therefore, a small gap G is provided between the radial edge of the susceptor 10 and the preheating ring 10A.

[0022] The bell jar 30 includes an upper bell jar 30A and a lower bell jar 30B, and the upper bell jar 30A and the lower bell jar 30B together enclose a reaction chamber RC containing the base 10 and the support frame 20. The base 10 divides the reaction chamber RC into an upper reaction chamber RC1 and a lower reaction chamber RC2, and the substrate W is placed in the upper reaction chamber RC1. Generally, the gas pressure in the upper reaction chamber RC1 is slightly greater than the gas pressure in the lower reaction chamber RC2, so that the gas in the upper reaction chamber RC1 can enter the lower reaction chamber RC2 through the gap G.

[0023] It should be noted that the material of the upper bell jar 30A and the lower bell jar 30B is quartz.

[0024] The gas inlet 40 is used to transport reaction gas, such as silicon source gas such as SiHCl 3 and doping gas such as B 2 H 6 or PH 3 , into the upper reaction chamber RC1 .

[0025] like Figure 3 As shown, the air inlet 40 generally includes at least one main air inlet 401 and at least one auxiliary air inlet 402. Figure 3 , the direction of the main gas inlet 401 is exemplarily shown as being orthogonal to the direction of the auxiliary gas inlet 402. The main gas inlet 401 is used to supply gas to the upper reaction chamber RC1, that is, mainly to supply gas above the substrate W placed on the susceptor 10, and the gas includes hydrogen (i.e., the so-called main hydrogen gas (Main H2)), etching gas, reaction gas, etc. The auxiliary gas inlet 402 mainly supplies gas to the lower reaction chamber RC2, that is, mainly used to supply gas to the area of ​​the reaction chamber RC located below the susceptor 10, and the gas includes hydrogen (i.e., the so-called auxiliary hydrogen gas (Slit H2)). The flow rate of the intake gas of the main gas inlet 401 and the auxiliary gas inlet 402 can be controlled by a valve, for example.

[0026] The exhaust port 50 is used to discharge the reaction waste gas and by-products out of the reaction chamber RC.

[0027] A plurality of heating elements 60 are disposed at the periphery of the upper bell jar 30A and the lower bell jar 30B and are used to provide a high temperature environment for a vapor deposition reaction in the reaction chamber RC through the upper bell jar 30A and the lower bell jar 30B.

[0028] In some examples, the heating assembly 60 includes an upper lamp assembly unit 601 disposed above the reaction chamber RC and a lower lamp assembly unit 602 disposed below the reaction chamber RC. The upper lamp assembly unit 601 includes a first inner lamp assembly unit 6011 and a first outer lamp assembly unit 6012 surrounding the outer periphery of the first inner lamp assembly unit 6011, and the lower lamp assembly unit 602 includes a second inner lamp assembly unit 6021 and a second outer lamp assembly unit 6022 surrounding the outer periphery of the second inner lamp assembly unit 6021. The first inner lamp assembly unit 6011 and the second inner lamp assembly unit 6021 are used to provide heat to the central area W1 of the substrate W, and the first outer lamp assembly unit 6012 and the second outer lamp assembly unit 6022 are used to provide heat to the edge area W2 of the substrate W.

[0029] Input pipeline 70, input pipeline 70 includes a main input pipeline (Depo line) 701 and an auxiliary input pipeline (Ventline) 702, wherein the main input pipeline 701 is used to input reaction gas into the reaction chamber RC, and the main input pipeline 701 can also be used to input other gases into the reaction chamber RC, such as etching gas, main hydrogen, etc. The auxiliary input pipeline 702 is used to input reaction gas and auxiliary hydrogen into the reaction chamber RC. It should be noted that the main input pipeline 901 and the auxiliary input pipeline 902 are independently controlled.

[0030] Understandably, if Figure 4 As shown, during the epitaxial growth process, the reaction gas enters through the air inlet cover 80 under the action of the main hydrogen gas and the auxiliary hydrogen gas, climbs to the preheating ring 10A through the air inlet 40, and flows through the surface of the substrate W supported on the base 10 after being preheated by the preheating ring 10A to perform a vapor deposition reaction. The reaction waste gas and by-products generated by the vapor deposition reaction are discharged from the reaction chamber RC through the exhaust port 50.

[0031] based on Figures 2 to 4 The epitaxial growth device 1 shown in FIG. Figure 5As shown, it may include: a substrate loading stage, a ramp-up stage, a baking stage, a vapor deposition stage, a ramp-down stage, and an unloading stage. Specifically, in the substrate loading stage, the substrate W is placed on the susceptor 10 of the reaction chamber RC so that epitaxial growth can be performed thereon later, and from this stage, H2 is introduced into the reaction chamber RC through the gas inlet 40 to purge the reaction chamber RC, thereby removing the impurity gas on the reaction chamber RC and the substrate W; in the heating stage, the temperature of the reaction chamber RC is further increased to the first temperature to remove the oxides on the reaction chamber RC and the substrate W; in the baking stage, the reaction chamber RC is continuously baked at the first temperature for a certain period of time to remove the oxides and organic matter remaining on the surface of the substrate W; in the deposition stage, the reaction chamber RC is introduced with reaction gas, such as trichlorosilane (TCS), and doping gas, such as B2H6, to form an epitaxial layer on the substrate W through a vapor deposition reaction; in the cooling stage, the reaction gas is stopped from being introduced into the reaction chamber RC and the reaction gas and by-products remaining in the reaction chamber RC are removed by hydrogen, and the temperature of the reaction chamber RC is reduced to prepare for the unloading of the formed epitaxial wafer.

[0032] The inventors found that based on Figure 5 The resistivity uniformity of the epitaxial wafer manufactured by the epitaxial growth process shown is poor, which in turn causes uneven current distribution inside the semiconductor device manufactured by the epitaxial wafer, resulting in local hot spots in the semiconductor device, increasing the power consumption of the semiconductor device, and may cause the semiconductor device to overheat, ultimately having a negative impact on the performance of the semiconductor device. It should be noted that in some examples, when the resistivity uniformity of the epitaxial layer is greater than a set threshold, it can be considered that the resistivity uniformity of the epitaxial layer is poor. The set threshold is, for example, 3.0% or 5.0%, and the inventors also found that when the resistivity at the center position of the epitaxial layer is similar to the resistivity at the edge position but the resistivity uniformity of the epitaxial layer is greater than the set threshold, it is impossible to reduce the resistivity uniformity of the epitaxial layer by adjusting the adjustment method in the related art, such as by adjusting the power ratio corresponding to the center position of the epitaxial layer.

[0033] The resistivity uniformity in the present disclosure refers to the consistency of the resistivity at different locations of the epitaxial layer, which can be measured by a variety of methods, including four-probe testing, Hall effect measurement, etc. In the present disclosure, the resistivity uniformity can be obtained, for example, by the following methods: Figure 6 As shown, first, excluding the area 5 mm from the edge of the epitaxial layer ( Figure 6In the case of the dotted circular area in the figure), resistivity sampling is performed at the point P1 at the center of the epitaxial layer, the four points P2, P3, P4 and P5 at half the radius, and the four points P6, P7, P8 and P9 at the edge. Then, the ratio of the difference between the maximum and minimum values ​​of the resistivity of each sampled point to the sum of the maximum and minimum values ​​is calculated. This ratio is the resistivity uniformity in the present disclosure, which is expressed by the following formula: .

[0034] It can be understood that the above-mentioned edge positions are the positions of the periphery corresponding to the position excluding 5 mm from the edge of the epitaxial layer, that is, the dotted circles where the points P6, P7, P8 and P9 are located.

[0035] Based on this, Figure 7 As shown, the present disclosure provides an epitaxial growth method, which includes: Step S701, placing a substrate on a base in a reaction chamber; Step S702, introducing auxiliary hydrogen gas into the area of ​​the reaction chamber below the susceptor through the auxiliary gas inlet; Step S703, raising the temperature of the reaction chamber to bake the reaction chamber at a predetermined first temperature; and Step S704, introducing a reaction gas into the reaction chamber through the main gas inlet to form an epitaxial layer on the substrate through a vapor deposition reaction; Wherein, during the vapor deposition reaction, the flow rate of the auxiliary hydrogen gas is less than or equal to 12 slm, and the first heating power ratio corresponding to the central area of ​​the substrate is reduced to less than the set first benchmark heating power ratio, and the difference between the reduced first heating power ratio and the first benchmark heating power ratio is in the range of 2% to 6%, and the second heating power ratio corresponding to the central area of ​​the substrate is reduced to less than the set second benchmark heating power ratio, and the difference between the reduced second heating power ratio and the second benchmark heating power ratio is in the range of 0.5% to 1.5%; wherein, the first heating power ratio is the heating power ratio of the first inner lamp group unit in the upper lamp group unit arranged above the reaction chamber; the second heating power ratio is the heating power ratio of the second inner lamp group unit in the lower lamp group unit arranged below the reaction chamber.

[0036] It should be noted that the introduction of auxiliary hydrogen into the reaction chamber 10 will continue until after step S704, for example, until the cooling stage in the aforementioned epitaxial growth process. Here, the auxiliary hydrogen can be used as a purge gas, for example, in step S702 and the cooling stage, and as a carrier gas for the reaction gas, for example, in step S704.

[0037] As mentioned above, when the resistivity at the center of the epitaxial layer is similar to the resistivity at the edge, but the resistivity uniformity of the epitaxial layer is greater than a set threshold, the resistivity uniformity of the epitaxial layer cannot be reduced by the adjustment method in the related art, such as by adjusting the power ratio corresponding to the center of the epitaxial layer. In the present disclosure, during the vapor deposition reaction, the flow rate of the auxiliary hydrogen gas is set to be less than or equal to 12slm, which can slow down the flow rate of the reaction gas in the reaction chamber, thereby reducing the concentration of the reaction gas corresponding to the edge of the epitaxial layer, slowing down the reaction rate of its vapor deposition reaction, and causing the dopant concentration at the edge of the epitaxial layer to decrease, thereby increasing the resistivity corresponding to the edge of the epitaxial layer. Specifically, Figure 8 As shown. Figure 8 In the figure, the dotted lines connect the points indicating the resistivity of each point of the epitaxial layer of the epitaxial wafer when the flow rate of the auxiliary hydrogen is 20 slm, the first heating power ratio is equal to the first reference heating power ratio (78%), and the second heating power ratio is equal to the second reference heating power ratio (19%). The solid lines connect the points indicating the resistivity of each point of the epitaxial layer of the epitaxial wafer when the flow rate of the auxiliary hydrogen is 12 slm, the first heating power ratio is equal to the first reference heating power ratio (78%), and the second heating power ratio is equal to the second reference heating power ratio (19%). Figure 8 It can be seen that when the flow rate of the auxiliary hydrogen gas is 12 slm, the resistivity of points P6, P7, P8 and P9 at the edge of the epitaxial layer increases.

[0038] In addition, during the vapor deposition reaction, the first heating power ratio corresponding to the central area of ​​the substrate is reduced to less than the set first benchmark heating power ratio, and the difference between the reduced first heating power ratio and the first benchmark heating power ratio is in the range of 2% to 6%, and the second heating power ratio corresponding to the central area of ​​the substrate is reduced to less than the set second benchmark heating power ratio, and the difference between the reduced second heating power ratio and the second benchmark heating power ratio is in the range of 0.5% to 1.5%. That is to say, in the specific implementation process, the first heating power ratio corresponding to the first inner lamp group unit 6011 and the second heating power ratio corresponding to the second inner lamp group unit 6021 are both reduced, so that the heat received by the central area of ​​the epitaxial layer is reduced, thereby reducing the temperature distribution in the central area of ​​the epitaxial layer so that the dopant elements are insufficient to excite more carriers, and then the corresponding resistivity of the central area of ​​the epitaxial layer is increased. Fig. 9 As shown. Fig. 9In the figure, the points connected by dotted lines represent the resistivity of each point of the epitaxial layer of the epitaxial wafer when the flow rate of the auxiliary hydrogen is 12 slm, the first heating power ratio is equal to the first reference heating power ratio (78%), and the second heating power ratio is equal to the second reference heating power ratio (19%). The points connected by solid lines represent the resistivity of each point of the epitaxial layer of the epitaxial wafer when the flow rate of the auxiliary hydrogen is 12 slm, the first heating power ratio is 74%, and the second heating power ratio is 18%. Fig. 9 It can be seen that when the flow rate of the auxiliary hydrogen is 12 slm and the proportion of the first heating power decreases relative to the first benchmark heating power proportion, and the proportion of the second heating power decreases relative to the second benchmark heating power proportion, the resistivity of points P1, P2, P3, P4 and P5 in the central area of ​​the epitaxial layer tends to increase.

[0039] Furthermore, if Fig.10 As shown, it shows Figure 8 and Fig. 9 The resistivity uniformity of the epitaxial layer in three cases is shown, where A represents the resistivity uniformity of the epitaxial layer of the epitaxial wafer when the flow rate of the auxiliary hydrogen is 20 slm, the first heating power ratio is equal to the first reference heating power ratio (78%), and the second heating power ratio is equal to the second reference heating power ratio (19%); B represents the resistivity uniformity of the epitaxial layer of the epitaxial wafer when the flow rate of the auxiliary hydrogen is 12 slm, the first heating power ratio is equal to the first reference heating power ratio (78%), and the second heating power ratio is equal to the second reference heating power ratio (19%); C represents the resistivity uniformity of the epitaxial layer of the epitaxial wafer when the flow rate of the auxiliary hydrogen is 12 slm, the first heating power ratio is 74%, and the second heating power ratio is 18%. Fig.10 It can be seen that during the vapor deposition reaction, the flow rate of the auxiliary hydrogen gas is controlled to be less than or equal to 12 slm, and the first heating power ratio corresponding to the central area of ​​the substrate is reduced to less than the set first benchmark heating power ratio, and the difference between the reduced first heating power ratio and the first benchmark heating power ratio is in the range of 2% to 6%, and the second heating power ratio corresponding to the central area of ​​the substrate is reduced to less than the set second benchmark heating power ratio, and the difference between the reduced second heating power ratio and the second benchmark heating power ratio is in the range of 0.5% to 1.5%, which can improve the resistivity uniformity of the epitaxial layer.

[0040] It should be noted that in the present disclosure, the first reference heating power ratio is the ratio of the heating power of the first inner lamp unit 6011 to the heating power of the upper lamp unit 601 in the related art, and the second reference heating power ratio is the ratio of the heating power of the second inner lamp unit 6021 to the heating power of the lower lamp unit 602 in the related art. In the related art, for example, in manufacturing epitaxial wafers with a diameter of 300 mm, the first reference heating power ratio is 78%, and the second reference heating power ratio is 19%.

[0041] For the above technical solution, in some possible implementations, during the vapor deposition reaction, the flow rate of the auxiliary hydrogen gas is 10 slm to 12 slm.

[0042] It can be understood that the reasons for determining the range of the flow rate of the auxiliary hydrogen gas are similar to those discussed previously and will not be elaborated herein.

[0043] For the above technical solution, in some possible implementations, when the temperature of the reaction chamber is increased, the temperature increase rate of the reaction chamber is 2.5° C. / s to 3.5° C. / s.

[0044] It can be understood that after placing the substrate W on the susceptor 10, the reaction chamber RC needs to be heated so that the temperature inside the reaction chamber RC reaches the set first temperature, thereby baking the reaction chamber RC. By controlling the above-mentioned heating rate, it can help to quickly heat up the reaction chamber RC, so as to remove residual oxides and organic matter in the reaction chamber RC and on the surface of the substrate W under high temperature and hydrogen atmosphere.

[0045] It should be noted that the first temperature is 1100° C. to 1150° C. Exemplarily, the first temperature is 1130° C.

[0046] For the above technical solution, in some possible implementations, during baking, the flow rate of the auxiliary hydrogen gas is 17 slm to 23 slm.

[0047] In the present disclosure, the flow rate of auxiliary hydrogen during baking is greater than that during vapor deposition reaction, and the larger flow rate of auxiliary hydrogen can be used to purge the oxides and organics remaining in the reaction chamber RC and on the surface of the substrate W, so that they are discharged from the reaction chamber RC.

[0048] For the above technical solution, in some possible implementations, after the reaction chamber is heated to bake the reaction chamber at a predetermined first temperature, an etching gas is introduced into the reaction chamber through a main gas inlet at a predetermined second temperature to etch the surface of the substrate; wherein the second temperature is lower than the first temperature.

[0049] In some examples, the etching gas is hydrogen chloride (HCl) gas.

[0050] It should be noted that the second temperature may be 1100° C. to 1150° C. Exemplarily, the second temperature is 1125° C.

[0051] It can be understood that after the baking is completed, the etching gas is introduced into the reaction chamber RC, which can remove particles and damaged layers attached to the surface of the substrate W on the one hand, and can improve the flatness of the surface of the substrate W by etching the surface of the substrate W on the other hand. In some examples, during the etching, the flow rate of the etching gas is 1.5 slm to 2.5 slm, and the duration of the etching is 10 s to 30 s.

[0052] Optionally, during etching, the flow rate of the auxiliary hydrogen gas is 17 slm to 23 slm.

[0053] It is understandable that the flow rate of auxiliary hydrogen during etching is greater than the flow rate of auxiliary hydrogen during vapor deposition reaction. A larger flow rate of auxiliary hydrogen can be used to purge the etching products generated after etching, so that they can be discharged from the reaction chamber in time, thereby reducing the impurity content in the epitaxial layer.

[0054] Regarding the above technical solution, in some possible implementations, during baking, the doping gas in the reaction gas is introduced into the auxiliary input pipeline to purge the auxiliary input pipeline.

[0055] During baking, the auxiliary input line 702 is purged by introducing doping gas into the auxiliary input line, and the doping gas introduced during this period will not be delivered to the reaction chamber RC, so as to clear the residual doping gas in the auxiliary input line 702 while ensuring that the doping gas pressure remains stable before entering the reaction chamber RC during the vapor deposition reaction.

[0056] For the above technical solution, in some possible implementations, during the vapor deposition reaction, the reaction gas is supplied to the main input pipeline, and the reaction gas is introduced into the reaction chamber through the main gas inlet.

[0057] It should be noted that after the epitaxial layer is formed, hydrogen is still introduced into the reaction chamber RC to purge the reaction chamber RC so that the reaction gas remaining in the reaction chamber RC is discharged and the manufactured epitaxial wafer is cooled down at the same time.

[0058] Based on the above explanation, see Fig.11, which shows the epitaxial growth process provided by the present disclosure. It may include: substrate loading stage, ramp-up stage, baking stage, etching stage, vapor deposition stage, ramp-down stage and unloading stage.

[0059] Based on the aforementioned technical solution, the present disclosure further provides an epitaxial wafer, which is prepared according to the epitaxial growth method described in the aforementioned technical solution, and the resistivity uniformity of the epitaxial layer of the epitaxial wafer is less than 3.0%.

[0060] According to the epitaxial growth method of the above-mentioned embodiment, epitaxial wafers with a diameter of 300 mm according to Examples 1 to 3 and Comparative Examples 1 to 3 are prepared, and the resistivity uniformity of the epitaxial layer thereof is specifically shown in Table 1. It should be noted that, except for the flow rate of the auxiliary hydrogen gas, the proportion of the first heating power and the proportion of the second heating power, these epitaxial wafers are prepared according to the same process conditions. Specifically, in the baking stage, the temperature in the reaction chamber is maintained at 1130°C, and the baking duration is 30s; in the etching stage, the temperature in the reaction chamber is maintained at 1125°C, the flow rate of the etching gas is 2slm, and the etching duration is 10s to 30s; in the vapor deposition stage, the temperature in the reaction chamber is maintained at 1125°C; and the first reference heating power accounts for 78%, and the second reference heating power accounts for 19%.

[0061]

[0062] Table 1 It should be noted that the technical solutions described in the embodiments of the present disclosure can be combined arbitrarily without conflict.

[0063] The above is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. An epitaxial growth method, characterized in that: The epitaxial growth method comprises: placing a substrate on a susceptor in a reaction chamber; introducing auxiliary hydrogen gas into the area of ​​the reaction chamber below the susceptor through the secondary gas inlet; Raising the temperature of the reaction chamber to bake the reaction chamber at a predetermined first temperature; and Introducing a reaction gas into the reaction chamber through a main gas inlet to form an epitaxial layer on the substrate through a vapor deposition reaction; Wherein, during the vapor deposition reaction, the flow rate of the auxiliary hydrogen gas is less than or equal to 12 slm, and the first heating power ratio corresponding to the central area of ​​the substrate is reduced to less than the set first benchmark heating power ratio, and the difference between the first heating power ratio after the reduction and the first benchmark heating power ratio is in the range of 2% to 6%, and the second heating power ratio corresponding to the central area of ​​the substrate is reduced to less than the set second benchmark heating power ratio, and the difference between the second heating power ratio after the reduction and the second benchmark heating power ratio is in the range of 0.5% to 1.5%; wherein, the first heating power ratio is the heating power ratio of the first inner lamp group unit in the upper lamp group unit above the reaction chamber; the second heating power ratio is the heating power ratio of the second inner lamp group unit in the lower lamp group unit below the reaction chamber.

2. The epitaxial growth method according to claim 1, characterized in that: During the vapor deposition reaction, the flow rate of the auxiliary hydrogen gas is 10 slm to 12 slm.

3. The epitaxial growth method according to claim 1 or 2, characterized in that: When the temperature of the reaction chamber is increased, the temperature increase rate of the reaction chamber is 2.5° C. / s to 3.5° C. / s.

4. The epitaxial growth method according to claim 1, characterized in that: During the baking, the flow rate of the auxiliary hydrogen gas is 17 slm to 23 slm.

5. The epitaxial growth method according to claim 1, characterized in that: After the reaction chamber is heated up to bake the reaction chamber at a predetermined first temperature, an etching gas is introduced into the reaction chamber through the main gas inlet at a predetermined second temperature to etch the surface of the substrate; The second temperature is lower than the first temperature.

6. The epitaxial growth method according to claim 5, characterized in that: During the etching, the flow rate of the etching gas is 1.5 slm to 2.5 slm, and the duration of the etching is 10 s to 30 s.

7. The epitaxial growth method according to claim 5 or 6, characterized in that: During the etching, the flow rate of the auxiliary hydrogen gas is 17 to 23 slm.

8. The epitaxial growth method according to claim 1, characterized in that: During the baking, the doping gas in the reaction gas is introduced into the auxiliary input pipeline to purge the auxiliary input pipeline.

9. The epitaxial growth method according to claim 8, characterized in that: During the vapor deposition reaction, the reaction gas is supplied to the main input pipeline, and the reaction gas is introduced into the reaction chamber through the main gas inlet.

10. An epitaxial wafer, characterized in that: The epitaxial wafer is prepared according to the epitaxial growth method according to any one of claims 1 to 9, and the resistivity uniformity of the epitaxial layer of the epitaxial wafer is less than 3.0%.

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