Epitaxial wafer, and method and apparatus for manufacturing epitaxial wafer

Abstract

The invention provides an epitaxial wafer and a manufacturing method and device of the epitaxial wafer. The manufacturing method comprises the following steps: providing a substrate wafer and placing the substrate wafer on a base of an epitaxial deposition chamber; in the epitaxial growth process, growth gas is introduced into the epitaxial deposition chamber to grow an epitaxial layer on the surface of the substrate wafer to obtain an epitaxial wafer; wherein at least in the vapor deposition stage in the epitaxial growth process, the flow of main hydrogen in the growth gas is smaller than 70 slm; in the process of cleaning the cavity, the duration of the coating process stage is increased to be longer than 40 seconds.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor manufacturing technology, and in particular to an epitaxial wafer and a method and apparatus for manufacturing an epitaxial wafer. Background Technology

[0002] Epitaxial wafers are obtained by growing an epitaxial layer on, for example, a polished substrate wafer. Compared to substrate wafers, epitaxial wafers have advantages such as fewer surface defects, superior crystallinity, and controllable resistivity, and are widely used in the fabrication of highly integrated integrated circuit (IC) devices and metal-oxide-semiconductor field-effect transistors (MOS).

[0003] With the continuous development of semiconductor technology, the requirements for the flatness of epitaxial wafers are becoming increasingly stringent. Taking the Site Frontsurface Referenced Least Squares / Range (SFQR) as an example, the current requirements for the flatness of epitaxial wafers have increased from SFQR... max Improved to the average SFQR value that can characterize the overall average flatness of the wafer surface (SFQR). mean Or 99% of the overall SFQR. d99 .

[0004] To improve the overall average flatness of the wafer surface, it is necessary to eliminate the undulations in the flatness of the epitaxial wafer surface during the epitaxial layer growth process. Summary of the Invention

[0005] This disclosure provides an epitaxial wafer and a method and apparatus for manufacturing the epitaxial wafer; it can improve the overall average flatness of the surface of the epitaxial wafer.

[0006] The technical solution disclosed herein is implemented as follows: In a first aspect, this disclosure provides a method for manufacturing an epitaxial wafer, the method comprising: A substrate wafer is provided and placed on the base of the epitaxial deposition chamber; During epitaxial growth, a growth gas is introduced into the epitaxial deposition chamber to grow an epitaxial layer on the surface of a substrate wafer to obtain an epitaxial wafer; wherein, at least during the vapor deposition stage of the epitaxial growth process, the flow rate of the main hydrogen gas in the growth gas is reduced to less than 70 standard liters per minute (slm). During the cleaning of the chamber, the duration of the coating process stage is increased to more than 40 seconds.

[0007] In some examples, the flow rate of the main hydrogen gas was reduced to 55 slm to 60 slm, at least during the vapor deposition stage of the epitaxial growth process.

[0008] In some examples, the duration of the coating process stage has increased to 60 to 90 seconds.

[0009] In some examples, after N batches of epitaxial growth of substrate wafers, a coating process stage lasting longer than 40 seconds is performed during the cleaning chamber process; where N ranges from 1 to 5.

[0010] In some examples, the method further includes: The size of the air guide holes distributed within a range of 20 mm to 80 mm from the center of the base surface of the base is reduced, and the density of the air guide holes distributed within a range of 20 mm to 80 mm from the center of the base surface of the base is increased.

[0011] In some examples, the diameter of the air guide holes distributed within a range of 20 mm to 80 mm from the center of the base surface of the base is less than 1 mm, and the density of the air guide holes distributed within a range of 20 mm to 80 mm from the center of the base surface of the base is greater than 0.23 per square millimeter.

[0012] In some examples, the diameter of the air guide holes distributed within a range of 20 mm to 80 mm from the center of the base surface of the base ranges from 0.3 mm to 0.5 mm, and the density of the air guide holes distributed within a range of 20 mm to 80 mm from the center of the base surface of the base ranges from 0.24 per square millimeter to 0.6 per square millimeter.

[0013] In some examples, the method further includes: A raised surface is provided on the upper surface of the base of the pedestal within a range of 20 mm to 80 mm from the center. The height of the raised surface is greater than or equal to 0.1 mm and less than or equal to 0.2 mm.

[0014] Secondly, this disclosure provides an epitaxial wafer manufacturing apparatus, the manufacturing apparatus comprising: Epitaxial deposition chamber; A base for placing the substrate wafer within the epitaxial deposition chamber; In the epitaxial deposition chamber, there is an inlet for introducing growth gas to grow an epitaxial layer on the surface of the substrate wafer to obtain an epitaxial wafer; And, a controller, used at least during the vapor deposition stage of the epitaxial growth process, to control the flow rate of the main hydrogen gas in the growth gas to be reduced to less than 70 slm; and, During the cleaning process of the chamber, the duration of the coating process stage is increased to a duration of more than 40 seconds.

[0015] In some examples, the controller is used to control the main hydrogen flow rate to be reduced to 55 slm to 60 slm.

[0016] In some examples, the controller is used to control the duration of the coating process stage to increase to 60 to 90 seconds.

[0017] In some examples, the controller is used to perform a coating process stage lasting longer than 40 seconds during the cleaning chamber process after N batches of epitaxial growth of substrate wafers; wherein N is in the range of 1 to 5.

[0018] In some examples, the base surface of the base has multiple air vents, wherein the diameter of the air vents distributed in the range of 20 mm to 80 mm from the center of the base surface of the base is less than 1 mm, and the density of the air vents distributed in the range of 20 mm to 80 mm from the center of the base surface of the base is greater than 0.23 per square millimeter.

[0019] In some examples, the diameter of the air guide holes distributed within a range of 20 mm to 80 mm from the center of the base surface of the base ranges from 0.3 mm to 0.5 mm, and the density of the air guide holes distributed within a range of 20 mm to 80 mm from the center of the base surface of the base ranges from 0.24 per square millimeter to 0.6 per square millimeter.

[0020] In some examples, the upper surface of the base has a raised surface ranging from 20 mm to 80 mm from the center, with a height of 0.1 mm to 0.2 mm.

[0021] Thirdly, this disclosure provides an epitaxial wafer manufactured by a method for manufacturing an epitaxial wafer as described in any of the first aspect and its examples, or an apparatus for manufacturing an epitaxial wafer as described in any of the second aspect and its examples, and the epitaxial wafer has an SFQR (Self-Quality Rendering Ratio). mean The range is [6.8nm, 7.6nm].

[0022] This disclosure provides an epitaxial wafer and a method and apparatus for manufacturing the epitaxial wafer. By reducing the flow rate of the growth gas, the obstruction formed by the inlet pipe wall on the introduced growth gas is reduced. In addition, by increasing the duration of the coating process stage, the difference between the thickness of the material layer coated on the annular boss and the thickness of the material layer coated on the annular support stage is increased, resulting in a continuous reduction in the difference between the height of the upper surface of the substrate wafer W supported on the annular support stage and the height of the upper surface of the annular boss. This causes the growth gas accumulated at the edge of the substrate wafer W to gradually decrease. Through the above two means, the overall average flatness index of the epitaxial wafer surface is improved. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the epitaxial growth equipment provided in this disclosure.

[0024] Figure 2 This is a top view of the epitaxial deposition chamber provided in this disclosure.

[0025] Figure 3 This is a schematic diagram of the SFQR distribution on the surface of an epitaxial wafer provided in this disclosure.

[0026] Figure 4 This is a schematic diagram of a method for manufacturing an epitaxial wafer provided in this disclosure.

[0027] Figure 5 This is a schematic diagram of the various stages of the epitaxial growth process provided in this disclosure.

[0028] Figure 6 This is a schematic diagram of the structure of a base provided in this disclosure.

[0029] Figure 7 This is a schematic diagram of another base structure provided in this disclosure.

[0030] Figure 8 This is a schematic diagram of a coated base provided in this disclosure.

[0031] Figure 9 This is a schematic diagram of another SFQR distribution on the surface of an epitaxial wafer provided in this disclosure.

[0032] Figure 10 This is a schematic diagram of another type of SFQR distribution on the surface of an epitaxial wafer provided in this disclosure.

[0033] Figure 11 This is a schematic diagram of another SFQR distribution on the surface of an epitaxial wafer provided in this disclosure.

[0034] Figure 12 This is a schematic diagram of another SFQR distribution on the surface of an epitaxial wafer provided in this disclosure.

[0035] Figure 13 This is a schematic diagram of the thickness distribution curve along the diameter of the epitaxial wafer provided in this disclosure.

[0036] Figure 14 This is a schematic diagram of another type of SFQR distribution on the surface of an epitaxial wafer provided in this disclosure.

[0037] Figure 15 This is a schematic diagram of another SFQR distribution on the surface of an epitaxial wafer provided in this disclosure.

[0038] Figure 16This is a schematic diagram of another SFQR distribution on the surface of an epitaxial wafer provided in this disclosure.

[0039] Figure 17 This is a schematic diagram of another type of SFQR distribution on the surface of an epitaxial wafer provided in this disclosure.

[0040] Figure 18 This is a schematic diagram of another SFQR distribution on the surface of an epitaxial wafer provided in this disclosure.

[0041] Figure 19 This is a schematic diagram of another SFQR distribution on the surface of an epitaxial wafer provided in this disclosure.

[0042] Figure 20 This is a schematic diagram of another type of SFQR distribution on the surface of an epitaxial wafer provided in this disclosure.

[0043] Figure 21 This is a schematic diagram of another SFQR distribution on the surface of an epitaxial wafer provided in this disclosure.

[0044] Figure 22 This is a schematic diagram of another SFQR distribution on the surface of an epitaxial wafer provided in this disclosure.

[0045] Figure 23 This is a schematic diagram of another type of SFQR distribution on the surface of an epitaxial wafer provided in this disclosure.

[0046] Figure 24 This is a schematic diagram of another type of base provided in this disclosure.

[0047] Figure 25 This is a schematic diagram of another type of base provided in this disclosure.

[0048] Figure 26 This is a schematic diagram of another SFQR distribution on the surface of an epitaxial wafer provided in this disclosure.

[0049] Figure 27 This is a schematic diagram of the composition of an epitaxial wafer manufacturing apparatus provided in this disclosure. Detailed Implementation

[0050] The technical solutions in this disclosure will now be clearly and completely described with reference to the accompanying drawings.

[0051] See Figure 1 The diagram illustrates the structure of an epitaxial growth apparatus 1 capable of implementing the technical solutions disclosed herein. The epitaxial growth apparatus 1 may include: A base 10 is used to support the substrate wafer W. A support frame 20 is used to support the base 10 and drive the base 10 to rotate at a certain speed around the central axis X during epitaxial growth. During the rotation of the base 10, the substrate wafer W rotates together with the base 10 around the central axis X, that is, the substrate wafer W remains stationary relative to the base 10.

[0052] A bell jar 30, comprising an upper bell jar 30A and a lower bell jar 30B, together encloses an epitaxial deposition chamber RC that houses the base 10 and the support frame 20. The base 10 divides the epitaxial deposition chamber RC into an upper epitaxial deposition chamber RC1 and a lower epitaxial deposition chamber RC2, with the substrate wafer W placed in the upper epitaxial deposition chamber RC1. In some examples, the upper bell jar 30A and the lower bell jar 30B are made of quartz.

[0053] The inlet 40 is used to supply growth gases, such as silicon source gas (e.g., SiHCl3), hydrogen (H2), and dopant gas (e.g., B2H6 or PH3), into the epitaxial deposition chamber RC1. This facilitates the reaction of the silicon source gas with hydrogen to generate silicon atoms, which are then deposited onto the substrate wafer W to grow an epitaxial layer and prepare the epitaxial wafer. Simultaneously, the dopant gas is used to dope the epitaxial layer to obtain the desired resistivity. The exhaust port 50 is used to discharge reaction waste gases and byproducts from the epitaxial deposition chamber RC.

[0054] Multiple heating elements 60 are disposed around the upper bell jar 30A and the lower bell jar 30B and are used to provide a high-temperature environment for vapor deposition reaction in the epitaxial deposition chamber RC through the upper bell jar 30A and the lower bell jar 30B.

[0055] for Figure 1 The top view of the epitaxial deposition chamber RC shown, especially the upper epitaxial deposition chamber RC1, is as follows: Figure 2 As shown. In Figure 2 In the process, the input pipeline 70 introduces growth gas into the epitaxial deposition chamber RC through the air inlet 40 at the air inlet cover 80. As shown by the dashed arrow, the growth gas flows through the surface of the substrate wafer W supported on the base 10 to perform a vapor phase deposition reaction to generate an epitaxial layer. The reaction waste gas and by-products generated by the vapor phase deposition reaction are discharged from the epitaxial deposition chamber RC through the exhaust port 50.

[0056] See also Figure 2The input line 70 may include a main input line (Depo line) 701 and an auxiliary input line (Vent line) 702. The main input line 701 is used to input growth gas into the epitaxial deposition chamber RC. Additionally, the main input line 701 can also be used to input other gases into the epitaxial deposition chamber RC, such as etching gas and main hydrogen (main H2). The auxiliary input line 702 is used to input growth gas and auxiliary hydrogen (Slit H2) into the epitaxial deposition chamber RC. It should be noted that the main input line 701 and the auxiliary input line 702 are independently controlled.

[0057] for Figure 2 The air inlet 40 shown is divided into three airflow channel regions along the vertical direction, and each airflow channel region has a pipe wall. As the growth gas enters the epitaxial deposition chamber RC through these three airflow channel regions of the air inlet 40, the pipe walls of the airflow channel regions obstruct the incoming growth gas, resulting in a reduced airflow rate at the edge of the substrate wafer W. Furthermore, the higher the growth gas flow rate, the stronger the obstruction formed by the pipe walls of the airflow channel regions. Ultimately, this causes the flatness of the epitaxial wafer surface to fluctuate from the wafer center to the edge, resulting in a poor overall average flatness index for the epitaxial wafer surface. Figure 3 Taking the schematic diagram of SFQR distribution on the surface of the epitaxial wafer shown as an example, from... Figure 3 As can be seen, the SFQR values ​​are larger at the edges and on the surface of the epitaxial wafer, while the SFQR values ​​are smaller in other areas. This results in a "bulge"-like appearance from the center to the edge of the epitaxial wafer, leading to a poor overall average flatness index on the surface of the epitaxial wafer.

[0058] To improve the overall average flatness of the epitaxial wafer surface, this disclosure provides a method for manufacturing an epitaxial wafer, such as... Figure 4 As shown, the manufacturing method may include: S401: Provides a substrate wafer and places it on the base of the epitaxial deposition chamber; S402: During the epitaxial growth process, a growth gas is introduced into the epitaxial deposition chamber to grow an epitaxial layer on the surface of the substrate wafer to obtain an epitaxial wafer; wherein, at least during the vapor deposition stage of the epitaxial growth process, the flow rate of the main hydrogen gas in the growth gas is reduced to less than 70 slm.

[0059] In this disclosure, the complete epitaxial growth process is as follows: Figure 5As shown, the process includes: a substrate loading stage, a ramp-up stage, a bake stage, a vapor deposition stage, a ramp-down stage, and an unloading stage. Specifically, in the substrate loading stage, the substrate wafer W is placed on the base 10 of the epitaxial deposition chamber RC for subsequent epitaxial growth. From this stage onwards, a cleaning gas, such as H2, is introduced into the epitaxial deposition chamber RC through the gas inlet 40 to purge the RC and remove impurity gases from the RC and the substrate wafer W. In the ramp-up stage, the temperature of the epitaxial deposition chamber RC is further increased to a first temperature to remove oxides from the RC and the substrate wafer W. In the bake stage, the epitaxial deposition chamber RC is continuously baked at the first temperature for a certain period to remove residual oxides and organic matter from the surface of the substrate wafer W. In the deposition stage, a growth gas is introduced into the epitaxial deposition chamber RC to form an epitaxial layer on the substrate wafer W through a vapor deposition reaction. During the cooling phase, the growth gas is stopped from entering the epitaxial deposition chamber RC, and the remaining growth gas and byproducts in the epitaxial deposition chamber RC are removed by hydrogen. The temperature of the epitaxial deposition chamber RC is also reduced in preparation for the unloading of the formed epitaxial wafer.

[0060] Combination Figure 3 As shown, during the vapor deposition stage, the pipe walls of the three gas flow channels in the inlet 40 obstruct the incoming growth gas, resulting in poor overall average flatness of the epitaxial wafer surface. This disclosure reduces the flow rate of the growth gas to decrease the obstruction caused by the pipe walls in the gas flow channel region diagram, thereby suppressing the undulations on the epitaxial wafer surface from the wafer center to the edge and improving the overall average flatness of the epitaxial wafer surface.

[0061] S403: During the cleaning of the chamber, increase the duration of the coating process phase to a duration of more than 40 seconds.

[0062] In this disclosure, such as Figure 6The schematic diagram of the base 10 shown illustrates that the base 10 includes a base 110 and an annular support stage 120. The annular support stage 120 surrounds the base 110, and the upper surface of the annular support stage 120 is higher than the upper surface of the base 110. Thus, the annular support stage 120 and the base 110 together form a concave region to support the substrate wafer W on the annular support stage 120. A certain gap exists between the lower surface of the substrate wafer W and the upper surface of the base 110 to provide space for gas flow. Additionally, the base 100 also includes an annular boss 130, which surrounds the outer edge of the annular support stage 120. The upper surface of the annular boss 130 is higher than the upper surface of the annular support stage 120, forming a circumferential constraint on the substrate wafer W and providing a buffering effect for the gas entering the reaction chamber, preventing it from directly blowing into the gap between the substrate wafer W and the annular support stage 120. In some examples, such as... Figure 6 As shown, the upper surface of the base 110 is curved.

[0063] Generally, when the substrate wafer W is supported on the annular support stage 120, the upper surface of the substrate wafer W is higher than the upper surface of the annular boss 130, such as... Figure 7 As shown, when the growth gas supplied by the air inlet 40 is as Figure 7 When the growth gas flows through the substrate wafer W in the direction indicated by the center arrow, the edge of the substrate wafer W is higher than the upper surface of the annular protrusion 130, causing the growth gas to accumulate at the edge of the substrate wafer W, resulting in more growth gas at the edge of the substrate wafer W than in other parts of the substrate wafer W.

[0064] Specifically, in this disclosure, to avoid the accumulation of growth gas at the edge of the substrate wafer W, the height difference between the upper surface of the annular protrusion 130 and the annular support stage 120 is increased during the vapor deposition stage. This ensures that when the annular support stage 120 supports the substrate wafer W, the edge of the substrate wafer W is lower than or flush with the upper surface of the annular protrusion 130, thereby preventing... Figure 7 The diagram shows the accumulation of growth gas at the edge of the substrate wafer W.

[0065] Based on this, this disclosure increases the duration of the coating process stage during the cleaning of the chamber. Specifically, when Figure 1After each period of epitaxial wafer production, the epitaxial growth equipment 1 undergoes a cleaning process in its epitaxial reaction chamber RC. This cleaning process includes an etching and recoating stage (Coat-Etch-Coat), which comprises an etching process and a coating process. Specifically, the etching process removes reaction residues from the surface of the substrate 10 by etching. The coating process, following the etching process, involves depositing a silicon-based material layer onto the surface of the substrate 10 using gas deposition to maintain the consistency of conditions for each substrate wafer W within the epitaxial deposition chamber RC during the vapor deposition stage.

[0066] Because the temperature is high during the coating process, and the annular boss 130 is closer to the air inlet 40 than the annular support platform 120, the thickness of the material layer coated on the annular boss 130 will be higher than the thickness of the material layer coated on the annular support platform 120 as the coating process is carried out. Furthermore, the difference between the thickness of the material layer coated on the annular boss 130 and the thickness of the material layer coated on the annular support platform 120 will also increase as the execution time increases.

[0067] As the difference between the thickness of the material layer coated on the annular protrusion 130 and the thickness of the material layer coated on the annular support stage 120 increases, the difference between the height of the upper surface of the substrate wafer W supported on the annular support stage 120 and the height of the upper surface of the annular protrusion 130 continuously decreases, resulting in a gradual reduction in the growth gas accumulating at the edge of the substrate wafer W. When the difference between the thickness of the material layer coated on the annular protrusion 130 and the thickness of the material layer coated on the annular support stage 120 is such that the upper surface of the substrate wafer W supported on the annular support stage 120 is no longer higher than the upper surface of the annular protrusion 130, the accumulation of growth gas at the edge of the substrate wafer W can be avoided. Figure 8 As shown.

[0068] In current related solutions, the coating process stage typically lasts 40 seconds. When the coating process stage duration is controlled to be greater than 40 seconds, the difference between the material layer thickness coated on the annular boss 130 and the material layer thickness coated on the annular support stage 120 will be larger than in related solutions. This ensures that when the annular support stage 120 supports the substrate wafer W, the edge of the substrate wafer W is lower than or flush with the upper surface of the annular boss 130. This reduces the growth gas accumulation at the edge of the substrate wafer W during the vapor deposition stage, lowers the epitaxial layer growth rate at the edge of the substrate wafer W, and reduces the SFQR value at the edge, thereby improving the overall average flatness of the epitaxial wafer surface.

[0069] Based on this discovery, this disclosure improves the overall average flatness index of the epitaxial wafer surface by reducing the flow rate of the growth gas to reduce the degree of obstruction formed by the tube wall and increasing the duration of the coating process stage to increase the difference between the material layer thickness coated on the annular boss 130 and the material layer thickness coated on the annular support stage 120.

[0070] against Figure 4 In the illustrated technical solution, the main hydrogen gas (main H2), besides being essential for the vapor deposition reaction, also serves as a carrier gas for transporting other growth gases. Therefore, in this disclosure, the flow rate of the main hydrogen gas (main H2) is controlled to correspondingly control the flow rate of the growth gases. Furthermore, in this disclosure, SFQR is used... mean As an example, SFQR is used to evaluate the overall average flatness of an epitaxial wafer surface. mean It refers to the average SFQR of all regions on the surface of the epitaxial wafer.

[0071] In current related schemes, the main hydrogen (main H2) flow rate is typically set to 70 slm during epitaxial growth, especially in the vapor deposition stage. This disclosure uses this related scheme as a comparison and analyzes the impact of reducing the main hydrogen (main H2) flow rate on the average flatness index of the epitaxial wafer through the following embodiments.

[0072] Comparative Example 1 use Figure 1 The epitaxial growth apparatus 1 shown has a vapor deposition stage temperature of 1120 degrees Celsius and a main hydrogen flow rate of 70 slm. A schematic diagram of the SFQR distribution on the surface of the resulting epitaxial wafer is shown below. Figure 3 As shown. The SFQR of this epitaxial wafer. max and SFQR mean The thicknesses are 21.73 nm and 8.54 nm, respectively. The thickness distribution curve of this epitaxial wafer along its diameter is shown in the figure. Figure 13 The solid curve in the figure is shown.

[0073] Example 1A Except for the main hydrogen flow rate being reduced to 65 slm, the other process conditions are the same as those in Comparative Example 1. A schematic diagram of the SFQR distribution on the surface of the grown epitaxial wafer is shown below. Figure 9 As shown. The SFQR of this epitaxial wafer. max and SFQR mean The thicknesses are 20.32 nm and 7.8 nm, respectively. The thickness distribution curve of this epitaxial wafer along its diameter is shown in the figure. Figure 13 The dashed curve in the figure is shown.

[0074] Example 1B Except for the main hydrogen flow rate being reduced to 60 slm, the other process conditions are the same as those in Comparative Example 1. A schematic diagram of the SFQR distribution on the surface of the grown epitaxial wafer is shown below. Figure 10 As shown, the SFQR of this epitaxial wafer max and SFQR mean The thicknesses are 25.63 nm and 7.63 nm, respectively. The thickness distribution curve of this epitaxial wafer along its diameter is shown in the figure. Figure 13 The dotted curve is shown in the figure.

[0075] Example 1C Except for the main hydrogen flow rate being reduced to 55 slm, the other process conditions are the same as those in Comparative Example 1. A schematic diagram of the SFQR distribution on the surface of the grown epitaxial wafer is shown below. Figure 11 As shown, the SFQR of this epitaxial wafer max and SFQR mean The thicknesses are 26.42 nm and 7.71 nm, respectively. The thickness distribution curve of this epitaxial wafer along its diameter is shown in the figure. Figure 13 The triangle point curve is shown in the figure.

[0076] Example 1D Except for the main hydrogen flow rate being reduced to 50 slm, the other process conditions are the same as those in Comparative Example 1. A schematic diagram of the SFQR distribution on the surface of the grown epitaxial wafer is shown below. Figure 12 As shown, the SFQR of this epitaxial wafer max and SFQR mean The thicknesses are 30.43 nm and 8.01 nm, respectively. The thickness distribution curve of this epitaxial wafer along its diameter is shown in the figure. Figure 13 The square point curve is shown in the figure.

[0077] By comparing the above four examples with the comparative examples, it can be seen that when the main hydrogen flow rate decreases from 70 slm, as shown in Examples 1A to 1C, the SFQR value of the central region of the epitaxial wafer surface, excluding the edges, decreases, thereby leading to a decrease in SFQR. mean The overall average flatness of the epitaxial wafer surface also decreases, leading to an improvement in the main hydrogen flow rate. However, as the main hydrogen flow rate decreases, the SFQR value at the edges of the epitaxial wafer surface increases, such as... Figure 13 As shown, this is because reducing the main hydrogen flow rate increases the edge thickness, resulting in edge unevenness. When the main hydrogen flow rate reaches 50 slm, i.e. in Example 1D, the overall average flatness of the epitaxial wafer surface does not improve and deteriorates compared to the previous three examples, also due to the excessively low main hydrogen flow rate.

[0078] Based on the comparison of the above embodiments and comparative examples, in some examples, at least during the vapor deposition stage of the epitaxial growth process, the flow rate of the main hydrogen gas is greater than or equal to 55 slm and less than or equal to 60 slm.

[0079] It should be noted that as the main hydrogen flow rate decreases, the SFQR value at the edge increases. This is because the growth gas accumulates at the edge of the substrate wafer W, resulting in a higher epitaxial layer growth rate at the edge of the substrate wafer W compared to the center. To reduce the SFQR value at the edge and improve the overall average flatness of the epitaxial wafer surface, the accumulation of growth gas at the wafer edge can be avoided during epitaxial growth, thus reducing the epitaxial layer growth rate at the edge of the substrate wafer W to be closer to that at the center.

[0080] against Figure 4 The duration of the coating process stage in the illustrated technical solution affects the difference between the material layer thickness coated on the annular boss 130 and the material layer thickness coated on the annular support stage 120, thereby affecting whether the edge of the substrate wafer W is lower than the upper surface of the annular boss 130 when the substrate wafer is supported on the annular support stage 120. This disclosure compares the coating process stage with related solutions and analyzes the impact of increasing the duration of the coating process stage on the average flatness index of the epitaxial wafer through the following embodiments.

[0081] Comparative Example 2 use Figure 1 The epitaxial growth apparatus 1 shown has a vapor deposition temperature of 1120 degrees Celsius, a main hydrogen flow rate of 60 slm, and a coating process duration of 40 seconds during the cleaning chamber. A schematic diagram of the SFQR distribution on the surface of the grown epitaxial wafer is shown below. Figure 10 As shown, it is the same as in Example 1B above. The SFQR of this epitaxial wafer... max and SFQR mean The wavelengths are 25.63nm and 7.63nm respectively, which are the same as in Example 1B above.

[0082] Example 2A Except for extending the coating process to 50 seconds, the other process conditions are the same as in Comparative Example 2. A schematic diagram of the SFQR distribution on the surface of the grown epitaxial wafer is shown below. Figure 14 As shown. The SFQR of this epitaxial wafer. max and SFQR mean The corresponding wavelengths are 23.5nm and 7.6nm, respectively.

[0083] Example 2B Except for extending the coating process to 60 seconds, the other process conditions are the same as in Comparative Example 2. A schematic diagram of the SFQR distribution on the surface of the grown epitaxial wafer is shown below. Figure 15 As shown. The SFQR of this epitaxial wafer. max and SFQR mean They are 23.6nm and 7.35nm respectively.

[0084] Example 2C Except for extending the coating process to 70 seconds, the other process conditions are the same as in Comparative Example 2. A schematic diagram of the SFQR distribution on the surface of the grown epitaxial wafer is shown below. Figure 16 As shown. The SFQR of this epitaxial wafer. max and SFQR mean The wavelengths are 20.2nm and 7.48nm, respectively.

[0085] Example 2D Except for extending the coating process to 80 seconds, the other process conditions are the same as in Comparative Example 2. A schematic diagram of the SFQR distribution on the surface of the grown epitaxial wafer is shown below. Figure 17 As shown. The SFQR of this epitaxial wafer. max and SFQR mean The wavelengths are 17.25nm and 7.39nm, respectively.

[0086] Example 2E Except for extending the coating process to 90 seconds, the other process conditions are the same as in Comparative Example 2. A schematic diagram of the SFQR distribution on the surface of the grown epitaxial wafer is shown below. Figure 18 As shown. The SFQR of this epitaxial wafer. max and SFQR mean The wavelengths are 18.4 nm and 7.48 nm, respectively.

[0087] Example 2F Except for extending the coating process to 95 seconds, the other process conditions are the same as in Comparative Example 2. A schematic diagram of the SFQR distribution on the surface of the grown epitaxial wafer is shown below. Figure 19 As shown. The SFQR of this epitaxial wafer. max and SFQR mean The wavelengths are 18.32 nm and 7.52 nm, respectively.

[0088] By comparing the above comparative examples with the five embodiments, it can be seen that as the duration of the coating process increases, the SFQR of the epitaxial wafer surface decreases. max and SFQR mean Both are smaller than the comparative SFQR max and SFQR meanHowever, once the coating process duration exceeds 90 seconds, flatness will no longer be further optimized, but the extended coating process duration leads to a decrease in equipment uptime. Based on the comparison between the above embodiments and comparative examples, in order to ensure that the equipment uptime is not reduced, the coating process duration should be greater than or equal to 60 seconds and less than or equal to 90 seconds.

[0089] Combining the two parameters of main hydrogen flow rate and coating process duration involved in the aforementioned technical solution, this disclosure analyzes the synergistic effect between these two parameters through the following embodiments.

[0090] In this disclosure, Figure 1 The epitaxial growth apparatus 1 shown has a vapor deposition stage temperature of 1120 degrees Celsius. The main hydrogen flow rate and coating process duration are described in each embodiment, along with the SFQR of the epitaxial wafer obtained from the deposition. max and SFQR mean As shown in Table 1 below.

[0091] Table 1

[0092] Based on the data in Table 1, comparing Examples 3A and 3C with the main hydrogen flow rate reduced to less than 70 slm (e.g., 60 slm), it can be seen that extending the coating process stage can improve the flatness of the epitaxial wafer. However, in both examples, the SFQR of the epitaxial wafer is lower. mean The differences between them are not significant, both being less than 8nm, while the SFQR of epitaxial wafers... max The improvement is quite significant, decreasing from 25.63nm to 17.25nm. Comparing Examples 3B and 3C with an extended coating process duration of 80 seconds, it is evident that as the main hydrogen flow rate decreases from 70 slm to 60 slm, the SFQR of the epitaxial wafer... mean It also decreased from over 8nm to less than 8nm, and SFQR max A significant improvement was also observed, with the nanometer diameter decreasing from 22.02nm to 17.25nm. The above comparison shows that reducing the main hydrogen flow rate is more effective than extending the coating process duration for SFQR of epitaxial wafers. max and SFQR mean The improvement is more obvious.

[0093] In this disclosure, a chamber cleaning process is performed after each batch of substrate wafers undergoes epitaxial growth. However, implementing a coating process lasting longer than 40 seconds during each chamber cleaning process would affect equipment uptime. Therefore, the coating process lasting longer than 40 seconds is not implemented during each chamber cleaning process, but can be implemented after several epitaxial production processes. The following analysis is based on examples: Example 4A use Figure 1 The epitaxial growth apparatus 1 shown has a vapor deposition stage temperature of 1120 degrees Celsius and a main hydrogen flow rate of 60 slm. After each batch of substrate wafers undergoes epitaxial growth, a chamber cleaning process is performed, with the coating process lasting 70 seconds. In this case, the SFQR distribution diagram of the surface of the last epitaxial wafer grown in each batch is shown below. Figure 20 As shown, the SFQR of this epitaxial wafer max and SFQR mean The wavelengths are 20.2nm and 7.48nm, respectively.

[0094] Example 4B use Figure 1 The epitaxial growth equipment 1 shown has a vapor deposition temperature of 1120 degrees Celsius and a main hydrogen flow rate of 60 slm. After every three batches of substrate wafers undergo epitaxial growth, a chamber cleaning process is performed, with the coating process lasting 70 seconds during the chamber cleaning. In this case, the SFQR distribution diagram of the surface of the last epitaxial wafer grown after every three batches is shown below. Figure 21 As shown, the SFQR of this epitaxial wafer max and SFQR mean The wavelengths are 21.17nm and 7.53nm, respectively.

[0095] Example 4C use Figure 1 The epitaxial growth apparatus 1 shown has a vapor deposition temperature of 1120 degrees Celsius and a main hydrogen flow rate of 60 slm. After every 5 batches of substrate wafers undergo epitaxial growth, a chamber cleaning process is performed, with the coating process lasting 70 seconds during the chamber cleaning. In this case, the SFQR distribution diagram of the surface of the last epitaxial wafer obtained after every 5 batches is shown below. Figure 22 As shown, the SFQR of this epitaxial wafer max and SFQR mean The corresponding wavelengths are 25.23nm and 7.74nm, respectively.

[0096] Example 4D use Figure 1The epitaxial growth apparatus 1 shown has a vapor deposition temperature of 1120 degrees Celsius and a main hydrogen flow rate of 60 slm. After every 6 batches of substrate wafers undergo epitaxial growth, a chamber cleaning process is performed, with the coating process lasting 70 seconds during the chamber cleaning. In this case, the SFQR distribution diagram of the surface of the last epitaxial wafer grown after every 6 batches is shown below. Figure 23 As shown, the SFQR of this epitaxial wafer max and SFQR mean The wavelengths are 28.64nm and 8.23nm, respectively.

[0097] By comparing the above four embodiments, it can be seen that the longer the time interval between coating process stages, the higher the amount of residual impurities in the chamber, and consequently the greater the deterioration of the flatness of the epitaxial wafer. The above embodiments show that after N batches of substrate wafers undergo epitaxial growth, a coating process stage lasting longer than 40 seconds is performed during the chamber cleaning process; where N ranges from 1 to 5.

[0098] Based on the aforementioned technical solution, in addition to controlling the main hydrogen flow rate and the duration of the coating process, improvements can also be made to the epitaxial growth equipment 1, particularly to the substrate 10, to enhance the average flatness of the epitaxial wafer. In some possible implementations, the surface of the substrate 10 of the epitaxial deposition chamber RC has multiple vent holes, wherein the diameter of the vent holes distributed within a range of 20 mm to 80 mm from the center of the base surface of the substrate 10 is greater than or equal to 0.3 mm and less than or equal to 0.5 mm, and the density of these vent holes distributed within a range of 20 mm to 80 mm from the center of the base surface of the substrate is 0.24 to 0.6 per square millimeter.

[0099] Regarding the above implementation method, combined with Figure 1 The base 10 of the epitaxial growth apparatus 1 shown is, specifically, as Figure 24 As shown, a through-hole 140 is formed on the surface of the base 110 of the substrate 10, extending to the back side. During the heating stage of the epitaxial growth process, the through-hole 140 allows the cleaning gas to contact the entire back side of the substrate wafer W, causing the cleaning gas to react and remove the native oxide layer on the back side of the substrate wafer W. The portion of the back side of the substrate wafer W that contacts the annular support stage 120 of the substrate 10 is also substantially etched by the cleaning gas, as the gas seeps between the wafer and the substrate, essentially completely removing the native oxide layer on the back side. During the baking and vapor deposition stages, the through-hole 140 allows dopant atoms diffusing outward from the back side of the substrate wafer W to pass through the hole and be discharged into the purification gas or hydrogen flow, or to exit from the front side of the substrate wafer W and enter the exhaust port 50, thereby significantly reducing self-doping on the front side of the substrate wafer W. Figure 24 The size and density of the vent holes 140 shown will affect the thickness of the epitaxial layer and the flatness of the epitaxial wafer during the vapor deposition stage.

[0100] Combination Figure 10 It can be seen that the thickness curve value is low in the range of 20 mm to 80 mm from the center of the base surface of the base 10. Based on this, the present disclosure improves the size and density of the vent holes in this range, thereby increasing the epitaxial layer thickness in this range to improve the average flatness of the epitaxial wafer.

[0101] In this disclosure, the diameter of the air vent 140 is used as a measure of size, and the disclosure uses "each per square millimeter" (ea / mm) as the unit of measurement. 2 This serves as a measure of the density of the air vents. In the relevant scheme, the diameter of the air vents 140 is 1 mm within a range of 20 mm to 80 mm from the center of the base surface of the base 10, and the arrangement density is 0.23 ea / mm. 2 As the diameter of the air vent 140 is reduced to 0.5 mm and 0.3 mm, and the density of the air vent 140 is increased to 0.243 ea / mm, respectively. 2 0.433ea / mm 2 and 0.568 ea / mm 2 Under otherwise identical conditions, the SFQR of epitaxial wafers mean As shown in Table 2.

[0102] Table 2

[0103] As shown in Table 1, with the reduction in the size of the vent holes and the increase in their density, the thickness of the epitaxial layer in the corresponding area increases, and the overall morphology of the epitaxial layer becomes more uniform. SFQR mean The trend shows a decrease, meaning the overall average flatness of the epitaxial wafer surface gradually improves. However, considering the limitations of machining precision, if the diameter of the vent holes is less than 0.3 mm, it will increase the processing cost of the substrate 10. Therefore, vent holes with a diameter less than 0.3 mm do not need to be considered. Furthermore, as the density of the first vent holes increases, the strength of the substrate itself decreases, increasing the risk of bending deformation or breakage during the epitaxial growth process. Therefore, the technical solution disclosed in this invention also does not consider a vent hole density exceeding 0.6 holes / mm. 2 The situation.

[0104] Based on the above analysis, in this disclosure, the density of air guide holes distributed within a range of 20 mm to 80 mm from the center of the base surface at a distance of 10 is 0.24 to 0.6 per square millimeter.

[0105] Based on the base described in the aforementioned technical solution, in some possible implementations, such as Figure 25 As shown, in Figure 25 The air vent is not shown in the diagram. The upper surface of the base 10 is at a distance from the center (e.g., Figure 25 (As shown by the dashed line) A raised surface is provided in the range of 20 mm to 80 mm, and the height of the raised surface ranges from [0.1 mm, 0.2 mm]. In some examples, the height of the raised surface is 0.15 mm.

[0106] Specifically, regarding the above implementation method, Figure 13 It can be seen that the epitaxial wafer thickness is relatively low in the range of 20 mm to 80 mm from the center of the base surface of the base 10. By setting a raised surface on the upper surface of the base 10 within a range of 60 mm from the center of 20 mm to 80 mm, the epitaxial layer thickness in this range can be increased, thereby improving the average flatness of the epitaxial wafer.

[0107] In this disclosure, Figure 6 The base shown does not have a protrusion and Figure 25 Compared with the base shown, under the same other process conditions, using Figure 6 The schematic diagram shown is of the SFQR distribution of the epitaxial wafer grown on a substrate without protrusions. Figure 3 As shown, and the SFQR of this epitaxial wafer max and SFQR mean The wavelengths are 21.73nm and 8.54nm respectively. Utilizing... Figure 25 The schematic diagram of the SFQR distribution of the epitaxial wafer obtained by substrate growth is shown below. Figure 26 As shown, and the SFQR of this epitaxial wafer max and SFQR mean The wavelengths are 20.82 nm and 7.31 nm, respectively. It can be seen that the average flatness of the epitaxial wafer improved after the raised surface was added.

[0108] Based on the same inventive concept as the aforementioned technical solution, see [link to inventive concept]. Figure 27 This disclosure also provides an epitaxial wafer manufacturing apparatus 270, the manufacturing apparatus 270 comprising: Epitaxial deposition chamber 2701; Inside the epitaxial deposition chamber 2701, there is a base 2702 for placing the substrate wafer W; An inlet 2703 is provided in the epitaxial deposition chamber 2701 for introducing growth gas to grow an epitaxial layer on the surface of the substrate wafer W to obtain an epitaxial wafer. And, controller 2704, for controlling the flow rate of the main hydrogen gas in the growth gas to be less than 70 slm, at least during the vapor deposition stage of the epitaxial growth process; and, During the cleaning process of the chamber, the duration of the coating process stage is increased to a duration of more than 40 seconds.

[0109] for Figure 27 The manufacturing apparatus 270 shown, whose epitaxial deposition chamber 2701 can be exemplary implemented as described above. Figure 1 The epitaxial deposition chamber RC in the epitaxial growth apparatus 1 shown herein, correspondingly, the base 2702 can be exemplarily implemented as the base 10 described in the foregoing technical solution, and the air inlet 2703 can be exemplarily implemented as the air inlet 40 described in the foregoing technical solution. Further details are omitted here. Figure 27 There are other components not shown in the epitaxial deposition chamber 2701. Figure 27 As shown in the figure, see also the relevant section. Figure 1 The relevant descriptions of the epitaxial deposition chamber RC in the epitaxial growth apparatus 1 will not be repeated in this disclosure.

[0110] In some examples, the controller 2704 is used to control the flow rate of the main hydrogen gas to be greater than or equal to 55 slm and less than or equal to 60 slm.

[0111] In some examples, the controller 2704 is used to control the duration of the coating process stage to be greater than or equal to 60 seconds and less than or equal to 90 seconds.

[0112] In some examples, the controller 2704 is configured to perform a coating process stage lasting longer than 40 seconds during the cleaning chamber process after N batches of epitaxial growth of substrate wafers; wherein N is in the range of 1 to 5.

[0113] In some examples, the surface of the base 2702 has a plurality of air vents, wherein the diameter of the air vents distributed in the range of 20 mm to 80 mm from the center of the surface of the base 2702 is less than 1 mm, and the density of the air vents distributed in the range of 20 mm to 80 mm from the center of the base surface of the base is greater than 0.23 per square millimeter.

[0114] In some examples, the diameter of the air vents distributed within a range of 20 mm to 80 mm from the center of the surface of the base 2702 is greater than or equal to 0.3 mm and less than or equal to 0.5 mm.

[0115] In some examples, the density of air vents distributed within a range of 20 mm to 80 mm from the center of the surface of the base 2702 is 0.24 to 0.6 per square millimeter.

[0116] In some examples, the base 2702 has a raised surface ranging from 20 mm to 80 mm from the center, the height of which is greater than or equal to 0.1 mm and less than or equal to 0.2 mm.

[0117] Furthermore, this disclosure also provides an epitaxial wafer, which is manufactured by the epitaxial wafer manufacturing method or the epitaxial wafer manufacturing apparatus described in any of the foregoing technical solutions, and the SFQR of the epitaxial wafer is... mean The range is [6.8nm, 7.6nm].

[0118] Those skilled in the art will recognize that the functions described in this disclosure in one or more of the examples above can be implemented using hardware, software, firmware, or any combination thereof. When implemented in software, these functions can be stored in a computer-readable medium or transmitted as one or more instructions or code on a computer-readable medium. Computer-readable media include computer storage media and communication media, wherein communication media include any medium that facilitates the transfer of a computer program from one place to another. Storage media can be any available medium accessible to a general-purpose or special-purpose computer.

[0119] It should be noted that the technical solutions described in this disclosure can be combined arbitrarily as long as they do not conflict.

[0120] 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 variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included 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 the claims.

Claims

1. A method for manufacturing an epitaxial wafer, characterized in that, The manufacturing method includes: A substrate wafer is provided and placed on the base of the epitaxial deposition chamber; During the epitaxial growth process, a growth gas is introduced into the epitaxial deposition chamber to grow an epitaxial layer on the surface of the substrate wafer to obtain an epitaxial wafer; wherein, at least during the vapor deposition stage of the epitaxial growth process, the flow rate of the main hydrogen gas in the growth gas is reduced to less than 70 slm. During the cleaning of the chamber, the duration of the coating process stage is increased to more than 40 seconds.

2. The manufacturing method according to claim 1, characterized in that, At least during the vapor deposition stage of the epitaxial growth process, the flow rate of the main hydrogen gas is reduced to 55 slm to 60 slm.

3. The manufacturing method according to claim 1, characterized in that, The duration of the coating process stage is increased to 60 to 90 seconds.

4. The manufacturing method according to claim 1, characterized in that, After N batches of substrate wafers undergo epitaxial growth, a coating process lasting longer than 40 seconds is performed during the cleaning chamber process; where N ranges from 1 to 5.

5. The manufacturing method according to any one of claims 1 to 4, characterized in that, The method further includes: The size of the air guide holes distributed within a range of 20 mm to 80 mm from the center of the base surface of the base is reduced, and the density of the air guide holes distributed within a range of 20 mm to 80 mm from the center of the base surface of the base is increased.

6. The manufacturing method according to claim 5, characterized in that, The diameter of the air guide holes distributed within a range of 20 mm to 80 mm from the center of the base surface of the base is less than 1 mm, and the density of the air guide holes distributed within a range of 20 mm to 80 mm from the center of the base surface of the base is greater than 0.23 per square millimeter.

7. The manufacturing method according to claim 6, characterized in that, The diameter of the air guide holes distributed within a range of 20 mm to 80 mm from the center of the base surface of the base is in the range of 0.3 mm to 0.5 mm, and the density of the air guide holes distributed within a range of 20 mm to 80 mm from the center of the base surface of the base is in the range of 0.24 per square millimeter to 0.6 per square millimeter.

8. The manufacturing method according to claim 5, characterized in that, The method further includes: A raised surface is provided on the upper surface of the base of the pedestal within a range of 20 mm to 80 mm from the center, and the height of the raised surface is 0.1 mm to 0.2 mm.

9. An apparatus for manufacturing epitaxial wafers, characterized in that, The manufacturing apparatus includes: Epitaxial deposition chamber; A base for placing the substrate wafer is provided within the epitaxial deposition chamber. In the epitaxial deposition chamber, there is an inlet for introducing growth gas to grow an epitaxial layer on the surface of the substrate wafer to obtain an epitaxial wafer; And, a controller, for controlling the flow rate of the main hydrogen gas in the growth gas to be reduced to less than 70 slm, at least during the vapor deposition stage of the epitaxial growth process; and, During the cleaning process of the chamber, the duration of the coating process stage is increased to a duration of more than 40 seconds.

10. The manufacturing apparatus according to claim 9, characterized in that, The controller is used to reduce the flow rate of the main hydrogen gas to 55 slm~60 slm.

11. The manufacturing apparatus according to claim 9, characterized in that, The controller is used to control the duration of the coating process stage to increase to 60 to 90 seconds.

12. The manufacturing apparatus according to claim 9, characterized in that, The controller is used to perform a coating process stage lasting longer than 40 seconds during the cleaning chamber process after the epitaxial growth process of N batches of substrate wafers; wherein the value of N ranges from 1 to 5.

13. The manufacturing apparatus according to any one of claims 9 to 12, characterized in that, The base surface of the base has multiple air guide holes, wherein the diameter of the air guide holes distributed within a range of 20 mm to 80 mm from the center of the base surface of the base is less than 1 mm, and the density of the air guide holes distributed within a range of 20 mm to 80 mm from the center of the base surface of the base is greater than 0.23 per square millimeter.

14. The manufacturing apparatus according to claim 13, characterized in that, The diameter of the air guide holes distributed within a range of 20 mm to 80 mm from the center of the base surface of the base is in the range of 0.3 mm to 0.5 mm, and the density of the air guide holes distributed within a range of 20 mm to 80 mm from the center of the base surface of the base is in the range of 0.24 per square millimeter to 0.6 per square millimeter.

15. The manufacturing apparatus according to claim 13, characterized in that, The base has a raised surface on its upper surface within a range of 20 mm to 80 mm from the center, and the height of the raised surface is 0.1 mm to 0.2 mm.

16. An epitaxial wafer, characterized in that, The epitaxial wafer is manufactured by the epitaxial wafer manufacturing method according to any one of claims 1 to 8, or by the epitaxial wafer manufacturing apparatus according to any one of claims 9 to 15, and the SFQR of the epitaxial wafer is... mean The range is [6.8nm, 7.6nm].

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