Epitaxial growth method and epitaxial wafer
By performing a second etching process during each epitaxial growth process, the base edge is etched, and the problems of low production efficiency and poor flatness in traditional epitaxial growth methods are solved, achieving more efficient epitaxial sheet production and better flatness.
Patent Information
- Application Number
- CN202411894296.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-20
- Publication Date
- 2025-05-02
AI Technical Summary
In traditional epitaxial growth methods, the production efficiency is low, which makes it difficult to improve the yield and the flatness of the epitaxial sheet is poor.
During each epitaxial growth process, a second etching process is performed first, and the edge part of the base is etched in the etching gas to reduce the edge thickness, thereby improving the gas flow path of the epitaxial reaction gas and improving the flatness of the epitaxial sheet.
By increasing the etching process, the flatness of the epitaxial sheet is improved, the overall quality of the epitaxial sheet is improved, and the production efficiency is increased.
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Abstract
Description
Technical Field
[0001] The present disclosure relates to the field of semiconductor manufacturing technology, and in particular to an epitaxial growth method and an epitaxial wafer. Background Art
[0002] Epitaxial growth is a very important process in semiconductor manufacturing. Through this process, polished wafers can be formed into epitaxial wafers. Epitaxial wafers have the characteristics of few surface defects, excellent crystallinity, and controllable resistivity. They are widely used in integrated circuit components, metal oxide semiconductor processes, optoelectronic devices, etc.
[0003] In the traditional epitaxial growth process, the wafer is placed on a susceptor in the reaction chamber of the epitaxial growth equipment. Through the vapor phase epitaxial reaction, a single crystal thin film is grown on the wafer to form an epitaxial wafer. Subsequently, the formed epitaxial wafer is removed from the reaction chamber to complete the epitaxial growth process. After an epitaxial growth process, the reaction chamber is cleaned by etching to keep the state of the reaction chamber stable.
[0004] However, when the epitaxial growth method is used for production, the production efficiency is low, which is not conducive to the improvement of output. Therefore, the process of multiple epitaxy and one etching is currently used. In this process, the reaction chamber is etched once after each multiple epitaxial growth process, so the production efficiency can be improved. Summary of the invention
[0005] This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
[0006] An object of the present disclosure is to provide an epitaxial growth method capable of improving the flatness of an obtained epitaxial wafer.
[0007] In order to achieve the above object, according to one aspect of the present disclosure, an epitaxial growth method is provided, which includes performing a first etching process on a reaction chamber of an epitaxial growth device after each multiple epitaxial growth processes are performed. In the epitaxial growth process, the wafer is placed on a susceptor in a reaction chamber for epitaxial growth, and is removed from the reaction chamber after the epitaxial growth is completed. And wherein, in each epitaxial growth process, before the epitaxial growth is performed, an etching gas is introduced into the reaction chamber to perform a second etching process.
[0008] In some embodiments, the epitaxial growth process may include a baking process, in which a reaction chamber in which the wafer is placed is baked, and the second etching process is performed after the baking process.
[0009] In some embodiments, the etching gas may include HCl gas.
[0010] In some embodiments, the flow rate of the HCL gas may be greater than or equal to 1000 sccm and less than or equal to 2000 sccm, and the introduction time of the HCL gas into the reaction chamber may be greater than or equal to 20 s and less than or equal to 30 s.
[0011] In some embodiments, during the second etching process, the ratio of the power of the inner lamp group unit to the power of the outer lamp group unit in the upper lamp group unit of the epitaxial growth device can be adjusted to be greater than or equal to 1:3 and less than or equal to 2:3.
[0012] In some embodiments, the flow rate of the HCl gas may be 1500 sccm, and the introduction time of the HCl gas into the reaction chamber may be 30 seconds.
[0013] In some embodiments, during the second etching process, a ratio of the power of the inner lamp group unit to the power of the outer lamp group unit in the upper lamp group unit of the epitaxial growth device may be 3:7.
[0014] In some embodiments, when the thickness of the epitaxial layer of the epitaxial wafer obtained by the epitaxial growth method is 4 um, the multiple epitaxial growth processes may be 3 to 5 epitaxial growth processes.
[0015] According to another aspect of the present disclosure, there is also provided an epitaxial wafer obtained by using the epitaxial growth method according to any of the above embodiments, wherein the SFQR of the epitaxial wafer is greater than or equal to 15 and less than or equal to 22.
[0016] In some embodiments, the average SFQR of the corresponding multiple epitaxial wafers obtained through multiple epitaxial growth processes of the epitaxial growth method can be greater than or equal to 16 and less than or equal to 18, and the difference between the maximum SFQR and the minimum SFQR can be greater than or equal to 2 and less than or equal to 4.
[0017] According to the above technical solution, by adding an etching process before epitaxial growth in each epitaxial growth process, the etching gas can etch the edge of the susceptor, thereby reducing the thickness of the edge. In this way, the adverse effect of the change in the thickness of the edge of the susceptor on the gas flow path of the epitaxial reaction gas can be reduced, thereby improving the surface morphology of the wafer, and thus improving the flatness of the formed epitaxial wafer, so that the overall quality of the epitaxial wafers obtained by the process of multiple epitaxy and one etching is improved. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The features and advantages of the embodiments of the present disclosure will become more easily understood through the following description with reference to the accompanying drawings. The drawings are not drawn to scale and some features may be enlarged or reduced to show details of specific parts. In the drawings: Figure 1 It is a schematic diagram of the structure of an epitaxial growth device in the related art.
[0019] Figure 2 This is a process flow chart for multiple epitaxy and one etching process.
[0020] Figure 3 The diagram schematically shows the change of the edge of the susceptor when multiple epitaxial growth processes are performed using a multiple epitaxial one-etching process.
[0021] Figure 4 To pass Figure 3 SFQR bar graphs of the corresponding multiple epitaxial wafers obtained from the multiple epitaxial growth processes shown in FIG.
[0022] Figure 5 is a flow chart of an epitaxial growth method according to an embodiment of the present disclosure.
[0023] In the drawings, the same or corresponding technical features, parts or components are represented by the same or corresponding reference numerals. DETAILED DESCRIPTION
[0024] The present disclosure is described in detail below with reference to the accompanying drawings by means of exemplary embodiments. It should be noted that the following detailed description of the present disclosure is only for illustrative purposes and is by no means a limitation of the present disclosure.
[0025] 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 structures and parts 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.
[0026] Reference Figure 1 , which shows an epitaxial growth device 1 of the related art. The epitaxial growth device 1 comprises: a base 10, a support frame 20, a bell jar 30, an air inlet 40, an exhaust port 50 and a heating assembly 60.
[0027] The base 10 is used to support the wafer W.
[0028] 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 wafer W rotates around the central axis X together with the susceptor 10 .
[0029] The bell jar 30 includes an upper bell jar 30A and a lower bell jar 30B. The upper bell jar 30A and the lower bell jar 30B together enclose a reaction chamber RC containing the susceptor 10 therein. The susceptor 10 divides the reaction chamber RC into an upper reaction chamber RC1 and a lower reaction chamber RC2. The wafer W is located in the upper reaction chamber RC1. The upper bell jar 30A and the lower bell jar 30B can both be made of quartz.
[0030] The gas inlet 40 is used to deliver epitaxial reaction gas into the upper reaction chamber RC1 , and the epitaxial reaction gas may include a silicon source gas such as SiHCl 3 (TCS), H 2 , and a doping gas such as B 2 H 6 .
[0031] The exhaust port 50 is used to discharge reaction waste gas and by-products out of the reaction chamber RC.
[0032] The heating assembly 60 is disposed at the periphery of the upper bell jar 30A and the lower bell jar 30B and can provide a high temperature environment required for the vapor deposition reaction in the reaction chamber RC through the upper bell jar 30A and the lower bell jar 30B.
[0033] 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 may include an inner lamp assembly unit 6011 and an outer lamp assembly unit 6012 surrounding the outer periphery of the inner lamp assembly unit 6011. Similarly, the lower lamp assembly unit 602 also includes an inner lamp assembly unit 6021 and an outer lamp assembly unit 6022 surrounding the outer periphery of the inner lamp assembly unit 6021.
[0034] based on Figure 1 The epitaxial growth apparatus 1 shown in FIG. Figure 2 The epitaxial growth process generally includes: a wafer loading process G1, a heating process G2, a baking process G3, a vapor deposition process G4, a cooling process G5 and an unloading process G6.
[0035] It should be noted that Figure 2 And subsequent Figure 5 The process gas flows corresponding to the above-mentioned processes shown in are all process gas flows appearing in the epitaxial chamber RC.
[0036] Specifically, in the wafer loading process G1, the wafer W is placed on the base 10 of the reaction chamber RC so that epitaxial growth can be performed thereon later, and from this point on, 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 wafer W; in the heating process G2, the temperature of the reaction chamber RC is further increased to a temperature to remove the oxide on the reaction chamber RC and the wafer W; in the baking process G3, the reaction chamber RC is maintained at the temperature. The baking is continued for a certain period of time to remove the residual oxides and organic matter on the surface of the wafer W; in the vapor deposition process G4, the epitaxial reaction gas is introduced into the reaction chamber RC to form an epitaxial layer on the wafer W through a vapor deposition reaction; in the cooling process G5, the reaction gas is stopped from entering the reaction chamber RC and the residual epitaxial reaction gas and by-products in the reaction chamber RC are removed by H2, and the temperature of the reaction chamber RC is reduced to prepare for the unloading of the formed epitaxial wafer; in the unloading process G6, the formed epitaxial wafer is removed from the reaction chamber.
[0037] As mentioned before, in order to improve production efficiency and increase output, the process of multiple epitaxy and one etching is currently used. Figure 2 As shown in FIG. 1 , in this process, after the epitaxial growth process C1 is performed multiple times, the reaction chamber RC is etched C2 once.
[0038] However, the inventors note that referring to Figure 3 In this process, after a plurality of epitaxial growth processes are performed continuously, an edge portion 110 of the susceptor 10 adjacent to an edge of the wafer W placed thereon becomes thicker. Figure 3 The example shows that when three epitaxial growth processes are performed continuously (where An represents the nth epitaxial growth process, for example, A1 represents the first epitaxial growth process, and so on), the thickness of the edge portion 110 gradually increases. This results in the gas flow path S ( Figure 3 The surface morphology of the wafer W may change, and thus the flatness of the formed epitaxial wafer may become abnormal.
[0039] Reference Figure 4 , shows the flatness of four epitaxial wafers obtained by four consecutive epitaxial growth processes, expressed by the parameter SFQR. It can be clearly observed that as the number of epitaxial growth processes increases, the SFQR becomes larger and larger, that is, the flatness becomes worse and worse.
[0040] In this regard, according to an embodiment of the present disclosure, an epitaxial growth method is proposed. Figure 5 , the epitaxial growth method is described in detail.
[0041] The epitaxial growth method includes performing a first etching process on the reaction chamber RC of the epitaxial growth device 1 after each multiple epitaxial growth process. In other words, the epitaxial growth method is still based on multiple epitaxy and one etching.
[0042] However, according to an embodiment of the present disclosure, in each epitaxial growth process, before the epitaxial growth is performed, an etching gas is introduced into the reaction chamber RC to perform a second etching process G10.
[0043] As discussed above, in the epitaxial growth process, the wafer W is placed on the susceptor 10 of the reaction chamber RC for epitaxial growth, and is removed from the reaction chamber RC after the epitaxial growth is completed. Here, it can be understood that epitaxial growth refers to the process of growing an epitaxial layer through a vapor deposition reaction, that is, the vapor deposition process G4.
[0044] That is, the second etching process G10 occurs in each epitaxial growth process and before the epitaxial growth is performed by vapor deposition reaction, that is, before the vapor deposition process G4 of the epitaxial growth process. It can be understood that in the second etching process G10, the wafer W is already supported on the susceptor 10.
[0045] By setting the second etching process G10, the etching gas can etch the edge portion 110 of the susceptor 10, thereby reducing the thickness of the edge portion 110. In this way, the adverse effect of the change in the thickness of the edge portion 110 of the susceptor 10 on the gas flow path S of the epitaxial reaction gas can be reduced, thereby improving the surface morphology of the wafer W, and thus improving the flatness of the formed epitaxial wafer, so that the overall quality of those epitaxial wafers obtained by the process of multiple epitaxy and one etching is improved.
[0046] It is conceivable that the etching gas used in the second etching process G10 may be HCL gas, but may also be any other suitable type of etching gas.
[0047] In some embodiments, Figure 5 As shown in FIG. 1 , the epitaxial growth process includes a baking process G3 , in which the reaction chamber RC in which the wafer W is placed is baked, and the second etching process G10 may be performed after the baking process G3 .
[0048] The baking process G3 is usually performed under H2 atmosphere, which can not only remove the oxides and organic matter remaining on the surface of the wafer W, but also remove impurities such as oxides on the edge portion 110 of the base 10. By performing the second etching process G10 after the baking process G3, the edge portion 110 of the base 10 can be cleaned by the baking process G3 first, and then the edge portion 110 can be etched. As a result, the etching process can be performed on the surface of the relatively clean edge portion 110 obtained by the baking process G3, so that the influence of impurities on the etching process can be reduced to obtain a better etching effect.
[0049] Referring to Tables 1 and 2 below, Table 1 shows the test results of epitaxial wafers obtained using an epitaxial growth method that does not include the second etching process G10 and an epitaxial growth method that includes the second etching process G10; and Table 2 shows the test results of epitaxial wafers obtained when the HCL flow rate and the introduction time are adjusted in the epitaxial growth method that includes the second etching process.
[0050] The test results in Table 1 are based on Figure 2 and Figure 5 The test results in Table 2 are obtained by the epitaxial growth method shown in for comparison. The test results in Table 2 are obtained under the condition that the ratio of the power of the inner lamp group unit 6011 in the upper lamp group unit 601 to the power of the outer lamp group unit 6012 remains unchanged. The relevant process conditions are: in the heating process G2, the reaction chamber is heated to 1110℃ to 1120℃; in the baking process G3, the temperature is maintained at 1110℃ to 1120℃, and the baking time is 40s to 60s; in the vapor deposition stage G4, the temperature is maintained at 1110℃ to 1120℃, and the TCS flow rate is 6000slm to 8000slm; in the cooling process G5, the power of the heating component is 56KW to 58KW, and the cooling time is 30s. In addition, the thickness of the epitaxial layer of the epitaxial wafer obtained by the above-mentioned epitaxial growth method is 4um, and four epitaxial growth processes are carried out in a multiple epitaxial one-etching cycle.
[0051] Table 1
[0052] Table 2
[0053] It can be clearly observed that, first, as shown in Table 1, the flatness of the epitaxial wafer obtained by the epitaxial growth method including the second etching process G10 is better than that of the epitaxial wafer obtained by the epitaxial growth method not including the second etching process G10. 平均The average SFQR of the corresponding multiple epitaxial wafers obtained through multiple epitaxial growth processes is smaller, and the SFQR 范围 The difference between the maximum SFQR and the minimum SFQR among the SFQRs of the corresponding plurality of epitaxial wafers is also smaller.
[0054] Furthermore, as shown in Table 2, when the flow rate of the HCL gas is greater than or equal to 1000 sccm and less than or equal to 2000 sccm, and the HCL gas is introduced into the reaction chamber RC for a time greater than or equal to 20 s and less than or equal to 30 s, SFQR 平均 Relatively small, and SFQR 范围 In particular, when the flow rate of HCL gas is 1500 sccm and the introduction time of HCL gas in the reaction chamber RC is 30 s, SFQR 平均 and SFQR 范围 It should be noted that, according to the test, the longer the injection time is, the better the test results are usually obtained, but when the injection time is less than or equal to 30s, a higher production capacity can be obtained.
[0055] That is to say, the average flatness of the epitaxial wafers obtained by the epitaxial growth method according to the embodiment of the present disclosure is improved, and the fluctuation of the flatness is reduced. Therefore, the flatness of each epitaxial wafer obtained by the process of multiple epitaxy and one etching is improved, thereby improving the overall quality of these epitaxial wafers. In particular, when the flow rate and the introduction time of the HCL gas are within the above-mentioned numerical range, in particular, when they are 1500 sccm and 30 s respectively, the flatness of the obtained epitaxial wafer can be better improved.
[0056] In addition, the epitaxial growth method can also increase the number of epitaxial growth processes performed in a cycle of multiple epitaxy and one etching.
[0057] For example, when the thickness of the epitaxial layer of the epitaxial wafer obtained by the epitaxial growth method is 4um, the flatness of the obtained epitaxial wafer can still be good when 3 to 5 epitaxial growth processes are performed. For example, the SFQR of the obtained epitaxial wafer is greater than or equal to 15 and less than or equal to 22, and the average SFQR of the corresponding multiple epitaxial wafers obtained through the multiple epitaxial growth processes is greater than or equal to 15 and less than or equal to 19, and the difference between the maximum SFQR and the minimum SFQR is greater than or equal to 2 and less than or equal to 5.
[0058] In some embodiments, the etching effect of the etching gas on the edge portion 110 of the base 10 can be enhanced by additionally adjusting the power ratio of the inner lamp unit 6011 to the outer lamp unit 6012 in the upper lamp unit 601 of the epitaxial growth device 1 .
[0059] Referring to Table 3 below, there are shown test results of epitaxial wafers obtained when the ratio of the power of the inner lamp group unit to the outer lamp group unit is adjusted and when the ratio is not adjusted in the epitaxial growth method including the second etching process.
[0060] In the chart, for each test object, the flow rate of HCL gas is 1500 sccm, and the introduction time of HCL gas in the reaction chamber RC is 30 seconds. In addition, the power ratio of the inner lamp unit 6011 to the outer lamp unit 6012 when not adjusted is 9:11, that is, the power of the inner lamp unit 6011 accounts for 45%.
[0061] Table 3
[0062] It can be clearly observed that, first, compared with the case where the ratio is not adjusted, when the ratio is adjusted to be greater than or equal to 1:3 and less than or equal to 2:3, that is, when the power proportion of the inner lamp unit 6011 is greater than or equal to 25% and less than or equal to 40%, SFQR 平均 Smaller and SFQR 范围 It is also smaller and has no slip lines, which tend to appear when the ratio is less than 1:3.
[0063] Furthermore, when the ratio is 3:7, SFQR 平均 Minimum, that is, greater than or equal to 15 and less than or equal to 18, and SFQR 范围 It is also the smallest, that is, the difference between the maximum SFQR and the minimum SFQR is greater than or equal to 2 and less than or equal to 4.
[0064] That is, by adjusting the power ratio of the inner lamp unit 6011 to the outer lamp unit 6012 in the upper lamp unit 601, the etching effect of the etching gas on the edge portion 110 of the base 10 can be enhanced, so that the average flatness of the epitaxial wafers obtained according to the epitaxial growth method can be further improved, and the fluctuation of the flatness can be further reduced, so that the flatness of each epitaxial wafer obtained by the process of multiple epitaxy and one etching can be further improved. In particular, when the flow rate of the HCL gas is 1500 sccm, the introduction time of the HCL gas in the reaction chamber RC is 30 seconds, and the above ratio is 3:7, the flatness of the obtained epitaxial wafer can be better improved.
[0065] According to another aspect of the present disclosure, an epitaxial wafer is provided. The epitaxial wafer is obtained by multiple epitaxial growth processes of the above-mentioned epitaxial growth method, and the SFQR of the epitaxial wafer is greater than or equal to 15 and less than or equal to 22.
[0066] Furthermore, an average SFQR of the corresponding plurality of epitaxial wafers obtained through the plurality of epitaxial growth processes may be greater than or equal to 15 and less than or equal to 18, and a difference between a maximum SFQR and a minimum SFQR may be greater than or equal to 2 and less than or equal to 4.
[0067] In the present disclosure, although the present disclosure has been described with reference to exemplary embodiments, it should be understood that the present disclosure is not limited to the specific embodiments described and shown in detail herein. Those skilled in the art may make various changes to the exemplary embodiments without departing from the scope defined by the claims of the present disclosure.
[0068] The features mentioned and / or shown in the above description of the exemplary embodiments of the present disclosure may be combined in the same or similar manner into one or more other embodiments, combined with the features in other embodiments or substituted for the corresponding features in other embodiments. The technical solutions obtained by these combinations or substitutions shall also be deemed to be included in the protection scope of the present disclosure.
Claims
1. An epitaxial growth method, characterized in that: The method comprises performing a first etching process on the reaction chamber of the epitaxial growth device after each multiple epitaxial growth processes are performed. Wherein, during the epitaxial growth process, the wafer is placed on the susceptor of the reaction chamber for epitaxial growth, and is removed from the reaction chamber after the epitaxial growth is completed. And wherein, in each epitaxial growth process, before the epitaxial growth is performed, an etching gas is introduced into the reaction chamber to perform a second etching process.
2. The epitaxial growth method according to claim 1, characterized in that: The epitaxial growth process includes a baking process, in which the reaction chamber in which the wafer is placed is baked, and the second etching process is performed after the baking process.
3. The epitaxial growth method according to claim 1 or 2, characterized in that: The etching gas includes HCL gas.
4. The epitaxial growth method according to claim 3, characterized in that: The flow rate of the HCL gas is greater than or equal to 1000 sccm and less than or equal to 2000 sccm, and the introduction time of the HCL gas in the reaction chamber is greater than or equal to 20 s and less than or equal to 30 s.
5. The epitaxial growth method according to claim 1 or 2, characterized in that: In the second etching process, the ratio of the power of the inner lamp group unit to the power of the outer lamp group unit in the upper lamp group unit of the epitaxial growth equipment is adjusted to be greater than or equal to 1:3 and less than or equal to 2:
3.
6. The epitaxial growth method according to claim 3, characterized in that: The flow rate of the HCL gas is 1500 sccm, and the introduction time of the HCL gas in the reaction chamber is 30 s.
7. The epitaxial growth method according to claim 6, characterized in that: In the second etching process, the ratio of the power of the inner lamp group unit to the power of the outer lamp group unit in the upper lamp group unit of the epitaxial growth equipment is 3:
7.
8. The epitaxial growth method according to claim 1 or 2, characterized in that: When the thickness of the epitaxial layer of the epitaxial wafer obtained by the epitaxial growth method is 4 um, the multiple epitaxial growth processes are 3 to 5 epitaxial growth processes.
9. An epitaxial wafer, characterized in that: Obtained by the epitaxial growth method according to any one of claims 1 to 8, the SFQR of the epitaxial wafer is greater than or equal to 15 and less than or equal to 22.
10. The epitaxial wafer according to claim 9, characterized in that: The average SFQR of the corresponding multiple epitaxial wafers obtained through the multiple epitaxial growth processes of the epitaxial growth method is greater than or equal to 15 and less than or equal to 18, and the difference between the maximum SFQR and the minimum SFQR is greater than or equal to 2 and less than or equal to 4.