Method for manufacturing epitaxial wafer, epitaxial wafer, and epitaxial growth apparatus
By using epitaxial growth equipment to monitor and automatically adjust the placement of polished wafers in real time, the problem of uneven epitaxial growth was solved, and the quality and yield of epitaxial wafers were improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XIAN ESWIN MATERIAL TECHNOLOGY CO LTD
- Filing Date
- 2026-03-10
- Publication Date
- 2026-06-16
AI Technical Summary
In existing epitaxial growth equipment, the placement error of the polished wafers leads to the inability to guarantee the quality of the epitaxial wafers, resulting in uneven growth of the epitaxial layer and affecting product quality and yield.
The epitaxial growth equipment acquires real-time information on the morphological characteristics of the epitaxial wafer, such as thickness and flatness. If the preset conditions are not met, the equipment parameters are adjusted to control the placement of the polished wafer on the substrate, forming an automatic closed-loop feedback system until the preset conditions are met.
It enables real-time monitoring and automated correction of epitaxial growth equipment, ensuring that the thickness uniformity and flatness of epitaxial wafers meet the requirements, thereby improving product yield.
Smart Images
Figure CN122215064A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor technology, and specifically to a method for preparing an epitaxial wafer, the epitaxial wafer itself, and an epitaxial growth apparatus. Background Technology
[0002] Vapor phase epitaxy (VPE) is a common epitaxial growth technique that enables the growth of epitaxial layers on polished substrates with different conductivity types, resistivity, and structures. These layers have controllable thickness and resistivity, meeting diverse requirements and significantly improving the flexibility and performance of device designs. VPE has broad application prospects in various semiconductor functional devices. Specifically, the epitaxial manufacturing process typically utilizes chemical vapor deposition (CVD) to inject silicon source gas into the surface of a polished wafer within a high-temperature, sealed reaction chamber, depositing an epitaxial layer on the wafer's surface to obtain an epitaxial wafer. Compared to polished wafers, epitaxial wafers offer advantages such as fewer surface defects and controllable epitaxial layer thickness and resistivity.
[0003] However, in the actual epitaxial growth process, if there is an error in the placement of the polished wafer on the base of the epitaxial growth equipment, it will cause power fluctuations in the epitaxial growth equipment during the epitaxial layer growth process, which will result in the quality of the produced epitaxial wafers being unreliable. Summary of the Invention
[0004] In view of this, the present invention aims to provide a method for preparing an epitaxial wafer, an epitaxial wafer, and an epitaxial growth apparatus, so as to solve the problem that the quality of epitaxial wafers in the production process cannot be guaranteed in the prior art.
[0005] This invention provides a method for preparing an epitaxial wafer, the method comprising: An epitaxial wafer is obtained by epitaxial growth of a polished wafer loaded with an epitaxial growth device. Obtain the morphological feature information of the epitaxial wafer, wherein the morphological feature information includes thickness information and / or flatness information; If the morphological feature information does not meet the preset conditions, the target equipment parameters of the epitaxial growth equipment are adjusted. The target equipment parameters are used to control the placement position of the loaded polished wafer on the base of the epitaxial growth equipment. Based on the adjusted epitaxial growth equipment, the step of epitaxial growth on the loaded polished wafer using the epitaxial growth equipment is returned to until the morphological feature information meets the preset conditions, so as to complete the adjustment of the epitaxial growth equipment. Epitaxial wafers are prepared using an epitaxial growth device that has been adjusted.
[0006] In one embodiment, obtaining the morphological feature information of the epitaxial wafer includes: The thickness value corresponding to each of the plurality of first stations on the epitaxial wafer is obtained to obtain a plurality of thickness values, wherein the plurality of first stations are set along the diameter direction of the epitaxial wafer; Determine the maximum and minimum thickness values from the plurality of thickness values; The difference between the maximum thickness value and the minimum thickness value is calculated to obtain a first calculated value; The sum of the maximum thickness value and the minimum thickness value is calculated to obtain a second calculated value; The quotient of the first calculated value and the second calculated value is determined as the thickness information.
[0007] In one embodiment, the method further includes: If the thickness information is greater than or equal to a preset threshold, then the morphological feature information is determined not to meet the preset conditions.
[0008] The preset threshold is 2%.
[0009] In one embodiment, the number of the plurality of first stations is 35, wherein the distance between any two adjacent first stations is equal.
[0010] In one embodiment, obtaining the morphological feature information of the epitaxial wafer includes: The ESFQD value corresponding to each of the plurality of second stations on the epitaxial wafer is obtained to obtain a plurality of ESFQD values, wherein the plurality of second stations are set along the edge of the epitaxial wafer; The average value of the multiple ESFQD values is determined as the flatness information.
[0011] In one embodiment, the method further includes: If the average of the multiple ESFQD values is greater than or equal to a first threshold, or if the average of the multiple ESFQD values is less than or equal to a second threshold, then it is determined that the morphological feature information does not meet the preset conditions.
[0012] In one embodiment, the first threshold is 30 and the second threshold is -40.
[0013] In one embodiment, the angle between any two adjacent second stations among the plurality of second stations and the center of the epitaxial wafer is 5 degrees.
[0014] In one embodiment, after adjusting the target equipment parameters of the epitaxial growth equipment if the morphological feature information does not meet the preset conditions, the method further includes: Record the current number of adjustments made to the target device parameters; If the current number of adjustments exceeds the preset number, then the specified equipment parameters of the epitaxial growth equipment are adjusted. The specified equipment parameters are used to control the thermal field distribution in the reaction chamber of the epitaxial growth equipment. If the thermal field distribution in the reaction chamber of the epitaxial growth equipment meets the preset thermal field conditions, then the step of epitaxial growth on the loaded polished wafer through the epitaxial growth equipment is returned to be executed until the morphological feature information meets the preset conditions, so as to complete the adjustment of the epitaxial growth equipment.
[0015] In another aspect, the present invention provides an epitaxial wafer, which is manufactured by the epitaxial wafer preparation method described in the above embodiments.
[0016] In some embodiments, the flatness information of the epitaxial wafer characterizes the frontal quadratic deviation of the effective area of the epitaxial wafer, wherein the value of the frontal quadratic deviation of the effective area of the epitaxial wafer is greater than -40 and less than 30.
[0017] In some embodiments, the thickness information of the epitaxial wafer characterizes the thickness uniformity of the epitaxial wafer, and the thickness uniformity of the epitaxial wafer is less than 2%.
[0018] In some embodiments, the nanomorphological change measured within a 10 μm × 10 μm region around the contact point between the surface of the epitaxial wafer and the support pin is less than or equal to 10 nm.
[0019] In another aspect, the present invention provides an epitaxial growth apparatus, the epitaxial growth apparatus comprising: A controller; and a memory for storing executable instructions of the controller; The controller is used to execute the epitaxial wafer fabrication method described in any of the above embodiments.
[0020] Compared with related technologies, the method for preparing epitaxial wafers provided by this invention has the following advantages: The epitaxial wafer preparation method provided by this invention involves epitaxially growing a polished wafer on an epitaxial growth device to obtain an epitaxial wafer; then acquiring the morphological feature information of the epitaxial wafer, including thickness and / or flatness information; if the morphological feature information does not meet preset conditions, adjusting the target equipment parameters of the epitaxial growth device, which are used to control the placement position of the polished wafer on the base of the epitaxial growth device; then, based on the adjusted epitaxial growth device, returning to the step of epitaxially growing the polished wafer on the epitaxial growth device until the morphological feature information meets the preset conditions, thus completing the adjustment of the epitaxial growth device; finally, the epitaxial wafer is prepared based on the adjusted epitaxial growth device. Since power fluctuations in the epitaxial growth device during epitaxial growth can cause abnormalities in the thickness, flatness, and other morphological feature information of the produced epitaxial wafer, real-time acquisition of the morphological feature information of the epitaxial wafer and comparison with preset conditions enables real-time monitoring of the power fluctuations of the epitaxial growth device, overcoming the subjectivity and lag of manual visual inspection. When an anomaly is detected, the system can automatically adjust the target equipment parameters used to control the placement of the polished wafer, and iteratively execute growth and verification based on the new parameters, forming an automatic closed-loop feedback adjustment system. This effectively solves the problem of uneven epitaxial layer growth caused by power fluctuations in the epitaxial growth equipment due to improper placement of the polished wafer, thereby ensuring the quality of the produced epitaxial wafers and significantly improving the product yield. Attached Figure Description
[0021] Figure 1 The diagram shown is a flowchart illustrating a method for preparing an epitaxial wafer according to an embodiment of the present invention.
[0022] Figure 2 The diagram shown is a schematic diagram of the reaction chamber in an epitaxial growth apparatus provided in an embodiment of the present invention.
[0023] Figure 3 The diagram shown is a structural schematic of an epitaxial growth apparatus provided in an embodiment of the present invention.
[0024] Figure 4 The diagram shown is a schematic representation of the distribution of the first site on the epitaxial wafer according to an embodiment of the present invention.
[0025] Figure 5 The diagram shows the distribution of the second site on the epitaxial wafer according to an embodiment of the present invention.
[0026] Figure 6 The figure shows the standard placement position of the polishing disc on the base according to an embodiment of the present invention.
[0027] Figure 7 The image shows the actual placement of the polishing disc on the base when power fluctuations occur, according to an embodiment of the present invention.
[0028] Figure 8 The figure shows the thickness distribution curves of the epitaxial wafer measured under normal conditions and under power fluctuation conditions, respectively, according to an embodiment of the present invention.
[0029] Figure 9 The figure shows the ESFQD distribution curve of an epitaxial wafer under normal conditions, as provided in an embodiment of the present invention.
[0030] Figure 10 The figure shows the ESFQD distribution curve of the epitaxial wafer under power fluctuation conditions according to an embodiment of the present invention.
[0031] Figure 11 The diagram shown is a schematic flowchart of a controlled epitaxial growth device for epitaxial growth of a polished wafer according to an embodiment of the present invention.
[0032] Figure 12 The diagram shown is a schematic diagram of another control epitaxial growth device provided by an embodiment of the present invention for epitaxial growth of a polished wafer.
[0033] Figure 13 The diagram shown is a schematic block diagram of an epitaxial wafer fabrication apparatus provided in an embodiment of the present invention.
[0034] Figure 14 The diagram shown is a block diagram of an electronic device provided in an embodiment of the present invention. Detailed Implementation
[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0036] In the description of the embodiments of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly specified.
[0037] In the semiconductor manufacturing field, epitaxial growth of polished wafers is one of the key front-end processes. Its purpose is to grow a single-crystal silicon thin film with a complete crystal structure and precisely controllable resistivity and thickness on a polished silicon substrate. The mainstream process at present is chemical vapor deposition (CVD). Typically, in a high-temperature environment (such as 1100-1200℃), a mixture of silicon source gas (such as SiCl4, SiHCl3, etc.) and hydrogen is introduced into a reaction chamber, causing it to react and deposit on the surface of a rotating polished wafer to form an epitaxial layer.
[0038] As the feature size of integrated circuits continues to shrink, the quality requirements for substrates and epitaxial wafers are becoming increasingly stringent. Not only are strict thickness uniformity (THK Unif) required, but extremely high demands are also placed on the local flatness of the surface (typically characterized by parameters such as Effective Site Frontside Quadratic Deviation (ESFQD)). The local flatness of the epitaxial layer directly determines the focusing window of subsequent photolithography processes and is one of the core factors affecting chip yield.
[0039] To achieve high-quality epitaxial growth, it is essential to ensure that the polished wafer is precisely centered on the substrate within the process reaction chamber. This is because the uniformity of the epitaxial growth process is highly dependent on the symmetry and stability of the thermal and gas flow fields within the reaction chamber. Currently, the polished wafer is primarily transported from the front-end loading port to the substrate in the reaction chamber via a transfer unit using an automated robotic arm.
[0040] However, in actual mass production, the repeatability of the robotic arm can drift over time, or due to mechanical vibration, calibration errors, or other reasons, the center of the polished wafer placed on the base may have a micrometer-level lateral offset or angular deflection from the theoretical center of the base. This deviation in placement severely disrupts the symmetrical distribution of the thermal and gas flow fields within the reaction chamber, causing uneven local temperature and reactive gas concentration on the surface of the polished wafer, which in turn leads to spatial differences in the epitaxial growth rate. This process anomaly is often manifested as feedback fluctuations in heating power (i.e., power fluctuations) at the equipment monitoring end, while at the final product end, it manifests as uneven thickness distribution of the epitaxial layer (such as deterioration of thickness uniformity THK Unif) and deterioration of local flatness (such as exceeding ESFQD and the distribution pattern showing asymmetrical tilt).
[0041] Currently, the industry primarily relies on two methods to monitor such process anomalies: First, during the process, operators manually visually inspect the approximate position of the polished wafer within the reaction chamber. This method is inefficient, highly subjective, and unable to identify micron-level deviations, resulting in poor accuracy. Second, after the process, the produced epitaxial wafers are sampled and offline inspected (e.g., measuring thickness or flatness). This method suffers from significant time lag; once an anomaly is detected, a large number of defective products may have already been produced in the same reaction chamber, leading to substantial waste. Regardless of the method used, when an anomaly is detected and adjustments are needed, the normal production process must be interrupted. After shutdown, engineers manually adjust the robotic arm parameters, and multiple trial runs are required for verification. The entire process is time-consuming and labor-intensive, severely impacting the overall efficiency of the epitaxial growth equipment.
[0042] Therefore, how to achieve real-time, online, automated monitoring and rapid closed-loop correction of quality risks caused by improper placement of polishing wafers during epitaxial growth has become a key technical problem that urgently needs to be solved in this field.
[0043] In view of the above problems, one embodiment of the present invention provides a method for preparing epitaxial green wafers. This method can be applied to an epitaxial growth apparatus, wherein the epitaxial growth apparatus includes a reaction chamber, a base disposed within the reaction chamber, and supporting components. The method for preparing the epitaxial green wafers can be executed by a controller integrated into the epitaxial growth apparatus, or by an electronic device (e.g., a server or user terminal) connected to the epitaxial growth apparatus; no limitation is made herein. Figure 1 As shown, the method for preparing the epitaxial wafer may include: 110. The polished wafer is subjected to epitaxial growth treatment using an epitaxial growth device to obtain an epitaxial wafer.
[0044] As an example, such as Figure 2 As shown, the epitaxial growth apparatus may include a reaction chamber, a conveying unit, and a controller. The conveying unit may include a support component and a conveying assembly, wherein the support component can be mounted on the conveying assembly and driven by it. Optionally, the support component may include one or more support pins or lift pins. The conveying assembly may include a conveyor belt, a conveying robot, etc.
[0045] Among them, the reaction chamber in the epitaxial growth equipment can be like Figure 2 As shown, the reaction chamber is used to perform chemical vapor deposition on the main surface of the polished wafer 8 to grow an epitaxial layer. The reaction chamber may include an upper quartz bell jar 1, a lower quartz bell jar 2, and a mounting component 4 arranged opposite each other.
[0046] Optionally, the reaction chamber may also be provided with an air inlet. Figure 2 (not shown in the image) and exhaust port ( Figure 2 (Not shown in the image). Optionally, the reaction chamber may further include a base 6 for placing the polishing disc 8 and a base support rod 7. Optionally, the reaction chamber may further include a heater, which may include an upper heating unit located above the base and / or a lower heating unit located below the base. The upper heating unit may include one or more heating lamps 3 (such as halogen lamps), and the lower heating unit may include one or more heating lamps 3. Figure 2 In this context, the gas flow direction 5 can be used to indicate the flow direction of the etching gas and / or silicon source gas.
[0047] As an example, epitaxial growth equipment can be as follows: Figure 3 As shown, for example, the epitaxial growth apparatus may include a reaction chamber 105 and a transfer unit ( Figure 3 (not shown in the image), controller ( Figure 3 (Not shown in the diagram) includes a transfer chamber 104, a load locking module 103, a front-end module 102, and a loading port 101. In practical applications, the transfer blades in the front-end module 102 transfer the polished wafer from the loading port 101 to the load locking module 103, where the load locking module 103 is evacuated and backfilled with nitrogen. A transfer unit (such as a transfer robot) located in the transfer chamber 104 loads the polished wafer from the load locking module 103 onto a base in the reaction chamber 105 for epitaxial growth. After growth is complete, the polished wafer returns along the original path.
[0048] In some embodiments, the controller can control the conveying unit in the epitaxial growth apparatus to load the polished wafer onto the base in the reaction chamber, supply raw material gas to the main surface of the polished wafer, thereby performing vapor phase growth. After vapor phase growth, the epitaxial wafer obtained through vapor phase growth is output outside the reaction chamber 105. During the growth process, the base support rod 7 serves to fix the base 6 and drive the base 6 to rotate, so that the epitaxial growth can be carried out uniformly on the substrate.
[0049] 120. Obtain the morphological features of the epitaxial wafer, including thickness and / or flatness parameters.
[0050] In some embodiments, the specific implementation of obtaining the morphological feature information of the epitaxial wafer in step 120 may include: Obtain the thickness value corresponding to each of the multiple first stations on the epitaxial wafer, resulting in multiple thickness values. The multiple first stations are set along the diameter direction of the epitaxial wafer.
[0051] Determine the maximum and minimum thickness values from multiple thickness values.
[0052] The difference between the maximum thickness value and the minimum thickness value is calculated to obtain the first calculated value.
[0053] The sum of the maximum and minimum thickness values is calculated to obtain the second calculated value.
[0054] The quotient of the first calculated value and the second calculated value is determined as the thickness information.
[0055] For example, such as Figure 4 As shown, multiple first stations are set on the epitaxial wafer and are arranged along the diameter direction of the epitaxial wafer.
[0056] In some implementations, the epitaxial wafer obtained after epitaxial growth can be transferred to an online thickness measurement system. This system measures the thickness at each first station, thus obtaining the thickness distribution of the epitaxial wafer. It is understood that the online thickness measurement system can be any commercially available equipment used for measuring epitaxial wafer thickness, and therefore will not be elaborated upon here.
[0057] Optionally, the number of multiple first stations is 35, wherein the distance between any two adjacent first stations is equal.
[0058] For example, the online thickness detection system can scan 35 first stations along the diameter direction on the surface of the epitaxial wafer to measure the thickness value of each first station, and then present the test results in the form of a curve showing the relationship between the thickness value and the position on the epitaxial wafer (thickness-position curve), and generate a thickness curve (profile) distribution map.
[0059] Then, the maximum and minimum thickness values are selected from the thickness profile distribution map, and the thickness information is calculated based on the maximum and minimum thickness values.
[0060] For example, the thickness information can be THK Unif, which in this embodiment can be calculated using the following formula: THK Unif = (Maximum thickness value - Minimum thickness value) / (Maximum thickness value + Minimum thickness value); The first calculated value is (maximum thickness - minimum thickness), and the second calculated value is (maximum thickness + minimum thickness).
[0061] In other embodiments, the specific implementation of obtaining the morphological feature information of the epitaxial wafer in step 120 may include: Obtain the ESFQD value corresponding to each of the multiple second stations on the epitaxial wafer, resulting in multiple ESFQD values. The multiple second stations are set along the edge of the epitaxial wafer.
[0062] The average of multiple ESFQD values is used to determine the flatness information.
[0063] For example, the distribution of multiple second sites at the edge of the epitaxial wafer can be as follows: Figure 5 As shown, in Figure 5 In this process, the circular epitaxial wafer can be divided into multiple test angles, and a second station can be set up for each test angle.
[0064] Optionally, the angle between any two adjacent second stations and the center of the epitaxial wafer is 5 degrees.
[0065] Please refer again to the example above. Figure 5 ,exist Figure 5 In this process, each pair of adjacent test angles differs by 5 degrees, thus dividing the 360-degree epitaxial wafer into 72 test angles. A second station is set at each test angle. For example, there is one second station at the 0-degree test angle, one at the 5-degree test angle, one at the 10-degree test angle, and so on, up to one at the 355-degree test angle.
[0066] In some implementations, the epitaxial wafer obtained after epitaxial growth can be transferred to an online flatness inspection system. This system scans the surface of the epitaxial wafer at second stations along the edge direction, measuring the ESFQD value at each station to obtain test results. These results can be presented as an ESFQD-position curve (ESFQD-position curve) showing the relationship between the ESFQD value and the position on the epitaxial wafer, generating an ESFQD profile distribution map. It is understood that the online flatness inspection system can be any commercially available equipment used for inspecting epitaxial wafer flatness, and therefore will not be elaborated upon here.
[0067] Then, based on the ESFQD Profile distribution map, the average value of multiple ESFQD values is calculated, and this average value is determined as flatness information. The average value of multiple ESFQD values can be represented by ESFQD AVERAGE.
[0068] 130. If the morphological feature information does not meet the preset conditions, adjust the target equipment parameters of the epitaxial growth equipment. The target equipment parameters are used to control the placement of the loaded polished wafer on the base of the epitaxial growth equipment.
[0069] In some embodiments, the morphological feature parameters include thickness information, and the method may further include: If the thickness information is greater than or equal to the preset threshold, then the morphological feature information is determined not to meet the preset conditions.
[0070] Optionally, the preset threshold is 2%.
[0071] Using the example above, if the thickness information (i.e., THK Unif) in the topographic feature information is found to satisfy: THKUnif≥2%, then it can be determined that the topographic feature information does not meet the preset condition.
[0072] In some implementations, the topographic feature parameters include flatness information, and the method may further include: If the average of multiple ESFQD values is greater than or equal to the first threshold, or if the average of multiple ESFQD values is less than or equal to the second threshold, then the morphological feature information is determined not to meet the preset conditions.
[0073] Optionally, the first threshold is 30 and the second threshold is -40.
[0074] Using the example above, if the flatness information (i.e., the average of multiple ESFQD values) in the topographic feature information is detected to satisfy: ESFQD AVERAGE ≥ 30, or ESFQD AVERAGE ≤ -40, then it can be determined that the topographic feature information does not meet the preset conditions.
[0075] Following the example above, the target equipment parameters can be control parameters for the conveying unit (such as a robotic arm). If the morphological feature information does not meet the preset conditions as determined by the above detection method, the control parameters of the conveying unit (such as the robotic arm's moving distance and moving angle) can be adjusted to adjust the placement position of the loaded polishing wafer on the base of the epitaxial growth equipment.
[0076] 140. Based on the adjusted epitaxial growth equipment, return to the step of performing epitaxial growth on the loaded polished wafer through the epitaxial growth equipment until the morphological feature information meets the preset conditions, so as to complete the adjustment of the epitaxial growth equipment.
[0077] Following the example above, steps 110 to 130 can be re-executed using the adjusted epitaxial growth equipment. Then, it can be checked whether the morphological characteristics of the epitaxial wafer produced by the equipment meet the preset conditions. If they do, the epitaxial growth equipment can continue to be used for epitaxial wafer production. If not, the target equipment parameters of the epitaxial growth equipment are adjusted, and steps 110 to 130 are executed again until the morphological characteristics of the produced epitaxial wafer meet the preset conditions.
[0078] In some embodiments, after adjusting the target equipment parameters of the epitaxial growth equipment in step 130 if the morphological feature information does not meet the preset conditions, the method may further include: Record the current number of adjustments made to the target device parameters.
[0079] If the current number of adjustments exceeds the preset number, the specified equipment parameters of the epitaxial growth equipment will be adjusted. The specified equipment parameters are used to control the thermal field distribution in the reaction chamber of the epitaxial growth equipment.
[0080] If the thermal field distribution in the reaction chamber of the epitaxial growth equipment meets the preset thermal field conditions, the process returns to the step of epitaxial growth on the loaded polished wafer through the epitaxial growth equipment until the morphological feature information meets the preset conditions, so as to complete the adjustment of the epitaxial growth equipment. Thus, the epitaxial growth equipment after the target equipment parameters are adjusted can be obtained, and the epitaxial growth equipment after adjustment can be identified as the target epitaxial growth equipment.
[0081] 150. Epitaxial wafers are prepared using an epitaxial growth device that has been adjusted.
[0082] For example, a polished wafer that needs to be epitaxially grown can be loaded into an epitaxial growth device after adjustment for epitaxial growth, thereby obtaining an epitaxial wafer.
[0083] Considering that if the morphological characteristics of the polished wafer still fail to meet the preset conditions after multiple adjustments to its placement, the epitaxial growth equipment itself may be malfunctioning. For example, the reaction chamber may experience thermal field center drift due to aging of the quartz components, decreased lamp efficiency, or accumulation of deposits. In this case, no matter how the polished wafer is placed, it cannot achieve uniform heating within the distorted thermal field. Therefore, in this embodiment, the current number of adjustments to the target equipment parameters is recorded. If the current number of adjustments exceeds a preset number, the specified equipment parameters of the epitaxial growth equipment are adjusted. These specified parameters control the thermal field distribution within the reaction chamber of the epitaxial growth equipment. If the thermal field distribution within the reaction chamber meets the preset thermal field conditions, the process returns to the step of epitaxial growth of the loaded polished wafer using the epitaxial growth equipment to obtain an epitaxial wafer, until the morphological characteristics meet the preset conditions, thus obtaining the target epitaxial growth equipment. This allows for the specification of equipment parameters to directly recalibrate or equalize the thermal environment (thermal field) within the reaction chamber, fundamentally repairing the systemic root cause of uneven growth. Optionally, the specified equipment parameters may include, but are not limited to: the power ratio of the upper and lower zone heating lamp groups (for adjusting the axial temperature gradient); the zone power setting of the multi-zone heater (for adjusting the radial temperature distribution); the flow balance of the gas injection port (affecting airflow and temperature distribution); and the base rotation speed (affecting the symmetry of heat and gas).
[0084] For example, in practical applications, the standard position of the loaded polishing disc on the base is as follows: Figure 6 As shown, when power fluctuations occur in the epitaxial growth equipment during the epitaxial growth of a polished wafer, the polished wafer at the base position is as follows: Figure 7 As shown, according to Figure 7It can be seen that the actual position of the polished disc when the power wave occurs has deviated from the standard position on the base.
[0085] Continuing with the above example, when the polished wafer loaded into the epitaxial growth equipment is actually positioned on the substrate as follows: Figure 6 As shown, when there is no power fluctuation during the epitaxial growth process on the polished wafer, the thickness profile distribution obtained by the online thickness detection system is as follows. Figure 8 As shown by the blue curve in the figure, the ESFQD Profile distribution obtained by the online flatness detection system is as follows: Figure 9 As shown. The actual position of the polished wafer loaded into the epitaxial growth equipment on the substrate is as follows. Figure 7 As shown, when power fluctuations occur during the epitaxial growth process on the polished wafer, the thickness profile distribution obtained by the online thickness detection system is as follows: Figure 8 As shown by the orange curve in the figure, the ESFQD Profile distribution obtained by the online flatness detection system is as follows: Figure 10 As shown.
[0086] It can be seen that, according to Figures 8 to 10 It can be seen that when the power of the epitaxial growth equipment fluctuates during the epitaxial growth of the polished wafer, the final epitaxial wafer product will exhibit uneven thickness distribution of the epitaxial layer (such as deterioration of thickness uniformity THK Unif) and local flatness degradation (such as excessive ESFQD and asymmetrical tilting of the distribution pattern).
[0087] Following the example above, for cases where the thickness distribution of the epitaxial layer is uneven, it can be addressed by, for example... Figure 11 The process control epitaxial growth equipment shown performs epitaxial growth on the polished wafer: Step 1: Polished wafer enters the epitaxial furnace reaction chamber to grow a film. The polished wafer enters the epitaxial furnace reaction chamber via an automated transfer unit (such as a robotic arm). The reaction chamber is pre-purged with high-purity hydrogen (H2) to ensure that the chamber is free of oxygen and impurities. Subsequently, silicon source gas (SiCl3) and carrier gas (H2) are mixed in a preset ratio. Under high temperature (usually 1100-1200℃), the silicon source gas undergoes a redox reaction on the surface of the polished wafer.
[0088] Step 2: Testing the THK 35P Profile of the Epitaxial Wafer. After epitaxial growth is completed, the polished wafer is transferred to an online thickness inspection system to detect the thickness distribution of the epitaxial wafer (THK 35P Profile). This test involves scanning 35 test points along the diameter direction on the surface of the polished wafer to obtain the thickness value at each point. The test results are presented in the form of a thickness-position curve, and a thickness profile distribution map is generated.
[0089] Step 3: Calculate the epitaxial wafer THK Unif. If THK Unif < 2%, continue normal production in the chamber; if THK Unif > 2%, adjust the position of the polished wafer entering the chamber. Calculate the epitaxial wafer thickness uniformity (THK Unif) based on the THK 35P Profile test results. The formula for calculating THK Unif is: THK Unif = {maximum thickness value - minimum thickness value} / {maximum thickness value + minimum thickness value}.
[0090] Step 4: If THK Unif < 2%, it indicates that the epitaxial layer thickness distribution is uniform, the polished wafer is correctly positioned on the substrate, there are no power fluctuations during film growth, and the process requirements are met. The chamber can continue normal production. At this point, the system automatically records process parameters (such as gas flow rate, temperature, and polished wafer position) and test data, and generates a production report.
[0091] Step 5: If THK Unif > 2%, the position of the polishing wafer entering the chamber needs to be adjusted. The specific steps are as follows: Analyze the cause of the anomaly: Based on the THK 35P Profile distribution diagram, identify areas of uneven thickness (such as edge thickening or central depression). Adjust the polishing wafer position: Through the Robot operation interface of the epitaxial furnace, modify the initial position parameters of the polishing wafer on the substrate (such as offset or angle) to ensure that the polishing wafer is placed correctly on the substrate. Verify the adjustment effect: Regrow the epitaxial layer and test the THK 35P Profile until THK Unif < 2%. If multiple adjustments still fail to meet the requirements, further check the thermal field distribution in the chamber, and perform maintenance or calibration if necessary.
[0092] The above process allows for real-time monitoring of power fluctuations in the epitaxial growth equipment, ensuring that epitaxial wafers meet quality requirements and improving product yield.
[0093] Following the example above, for cases of localized flatness degradation in the epitaxial layer, it can be addressed by, for example... Figure 12 The process control epitaxial growth equipment shown performs epitaxial growth on the polished wafer: Step 1: The polished wafer enters the epitaxial furnace reaction chamber to grow a film. The polished wafer is introduced into the epitaxial furnace reaction chamber via an automated transfer system (such as a robotic arm). The reaction chamber is pre-purged with high-purity hydrogen (H2) to ensure that it is oxygen-free and free of impurities. Subsequently, the silicon source gas (SiCl3) and the carrier gas (H2) are mixed in a preset ratio. Under a high-temperature environment (typically 1100-1200℃), the silicon source gas undergoes a redox reaction on the surface of the polished wafer.
[0094] Step 2: Testing the ESFQD Profile of the Epitaxial Wafer. After epitaxial growth is completed, the polished wafer is transferred to an online flatness inspection system to obtain the ESFQD of each point by scanning the test points along the edge direction on the surface of the polished wafer. The test results are presented in the form of ESFQD-position curves, and an ESFQD profile distribution map is generated.
[0095] Step 3: Calculate the average value of ESFQD at different test angles of the epitaxial wafer to obtain the ESFQD AVERAGE. If the ESFQD AVERAGE is between (-40, 30), the chamber continues normal production; if the ESFQD AVERAGE exceeds (-40, 30), adjust the position of the polishing wafer entering the chamber.
[0096] Step 4: If the ESFQD AVERAGE is between (-40, 30), it indicates that the polishing wafer is positioned correctly on the substrate, there is no power fluctuation during film growth, and the process requirements are met. The chamber can continue normal production. At this point, the system automatically records process parameters (such as gas flow rate, temperature, and polishing wafer position) and test data, and generates a production report.
[0097] Step 5: If the ESFQD AVERAGE exceeds (-40, 30), the position of the polishing wafer entering the chamber needs to be adjusted. The specific steps are as follows: Adjust the polishing wafer position. Specifically, through the Robot operation interface of the epitaxial furnace, modify the initial position parameters (such as offset or angle) of the polishing wafer on the substrate. Ensure the polishing wafer is positioned correctly on the substrate. Verify the adjustment effect: Specifically, regrow the epitaxial layer and test the ESFQD Profile until the ESFQD is between (-40, 30). If multiple adjustments still do not meet the requirements, further check the thermal field distribution in the chamber, and perform maintenance or calibration if necessary.
[0098] The above process allows for real-time monitoring of power fluctuations in the epitaxial growth equipment, ensuring that epitaxial wafers meet quality requirements and improving product yield.
[0099] As can be seen, in this embodiment, an epitaxial growth device is used to epitaxially grow a polished wafer to obtain an epitaxial wafer. Then, the morphological feature information of the epitaxial wafer is acquired, including thickness and / or flatness information. If the morphological feature information does not meet preset conditions, the target device parameters of the epitaxial growth device are adjusted. These target device parameters control the placement of the polished wafer on the base of the epitaxial growth device. Then, based on the adjusted epitaxial growth device, the step of epitaxially growing the polished wafer using the epitaxial growth device is repeated until the morphological feature information meets the preset conditions, thus completing the adjustment of the epitaxial growth device. Finally, the epitaxial wafer is prepared based on the adjusted epitaxial growth device. Since power fluctuations in the epitaxial growth device during epitaxial growth can cause abnormalities in the thickness, flatness, and other morphological feature information of the produced epitaxial wafer, real-time acquisition of the morphological feature information of the epitaxial wafer and comparison with preset conditions enables real-time monitoring of power fluctuations in the epitaxial growth device, overcoming the subjectivity and lag of manual visual inspection. When an anomaly is detected, the system can automatically adjust the target equipment parameters used to control the placement of the polished wafer, and iteratively execute growth and verification based on the new parameters, forming an automatic closed-loop feedback adjustment system. This effectively solves the problem of uneven epitaxial layer growth caused by power fluctuations in the epitaxial growth equipment due to improper placement of the polished wafer, thereby ensuring the quality of the produced epitaxial wafers and significantly improving the product yield.
[0100] An embodiment of the present invention also provides an epitaxial wafer, which is manufactured by the epitaxial wafer preparation method described in the above embodiment.
[0101] In some implementations, the flatness information of the epitaxial wafer characterizes the frontal quadratic deviation of the effective area of the epitaxial wafer, wherein the value of the frontal quadratic deviation of the effective area of the epitaxial wafer is greater than -40 and less than 30.
[0102] In some implementations, the thickness information of the epitaxial wafer characterizes the thickness uniformity of the epitaxial wafer, and the thickness uniformity of the epitaxial wafer is less than 2%.
[0103] In some embodiments, the change in nanomorphology measured within a 10 μm × 10 μm region around the contact point between the epitaxial wafer surface and the support pin is less than or equal to 10 nm.
[0104] One embodiment of the present invention also provides an epitaxial growth apparatus, the epitaxial growth apparatus comprising: a controller; and a memory for storing controller-executable instructions; The controller is used to execute the method for preparing the epitaxial wafer in any of the above embodiments.
[0105] Figure 13The diagram shown is a block diagram of an apparatus for preparing an epitaxial green wafer according to an embodiment of the present invention. The apparatus 300 for preparing the epitaxial green wafer includes: Epitaxial growth module 310 is used to perform epitaxial growth on a loaded polished wafer using an epitaxial growth device to obtain an epitaxial wafer; The acquisition module 320 is used to acquire the morphological feature information of the epitaxial wafer, including thickness information and / or flatness information; If the morphological feature information does not meet the preset conditions, the adjustment module 330 adjusts the target equipment parameters of the epitaxial growth equipment. The target equipment parameters are used to control the placement position of the loaded polished wafer on the base of the epitaxial growth equipment. The execution module 340 is used to return to the step of epitaxial growth of the loaded polished wafer through the epitaxial growth equipment based on the adjusted epitaxial growth equipment, until the morphological feature information meets the preset conditions, so as to complete the adjustment of the epitaxial growth equipment. The preparation module 350 is used to prepare epitaxial wafers based on the adjusted epitaxial growth equipment.
[0106] In some implementations, the acquisition module 320 is specifically used for: Obtain the thickness value corresponding to each of the multiple first stations on the epitaxial wafer, and obtain multiple thickness values. The multiple first stations are set along the diameter direction of the epitaxial wafer. Determine the maximum and minimum thickness values from multiple thickness values; Calculate the difference between the maximum thickness value and the minimum thickness value to obtain the first calculated value; Calculate the sum of the maximum thickness value and the minimum thickness value to obtain the second calculated value; The quotient of the first calculated value and the second calculated value is determined as the thickness information.
[0107] In some embodiments, the adjustment module 330 is further configured to: If the thickness information is greater than or equal to the preset threshold, then the morphological feature information is determined not to meet the preset conditions.
[0108] In some implementations, the preset threshold is 2%.
[0109] In some implementations, the number of the plurality of first stations is 35, wherein the distance between any two adjacent first stations is equal.
[0110] In some implementations, the acquisition module 320 is specifically used for: Obtain the ESFQD value corresponding to each of the multiple second stations on the epitaxial wafer to obtain multiple ESFQD values. The multiple second stations are set along the edge of the epitaxial wafer. The average of multiple ESFQD values is used to determine the flatness information.
[0111] In some embodiments, the adjustment module 330 is further configured to: If the average of multiple ESFQD values is greater than or equal to the first threshold, or if the average of multiple ESFQD values is less than or equal to the second threshold, then the morphological feature information is determined not to meet the preset conditions.
[0112] In some implementations, the first threshold is 30 and the second threshold is -40.
[0113] In some implementations, the angle between any two adjacent second stations and the center of the epitaxial wafer is 5 degrees.
[0114] In some embodiments, the device 300 further includes: a calibration module, used for: Record the current number of adjustments made to the target device parameters; If the current number of adjustments exceeds the preset number, the specified equipment parameters of the epitaxial growth equipment will be adjusted. The specified equipment parameters are used to control the thermal field distribution in the reaction chamber of the epitaxial growth equipment. If the thermal field distribution in the reaction chamber of the epitaxial growth equipment meets the preset thermal field conditions, the process returns to the step of epitaxial growth of the loaded polished wafer through the epitaxial growth equipment until the morphological feature information meets the preset conditions, thus completing the adjustment of the epitaxial growth equipment.
[0115] The specific implementation process of the functions and roles of each module in the above-mentioned device can be found in the implementation process of the corresponding steps of the epitaxial green sheet preparation method in the above embodiments, and will not be repeated here.
[0116] Figure 14 The diagram shown is a block diagram of an electronic device 500 provided in an embodiment of the present invention.
[0117] Reference Figure 14 The electronic device 500 includes a processing component 510, which further includes one or more processors, and memory resources represented by memory 520 for storing instructions, such as application programs, that can be executed by the processing component 510. The application programs stored in memory 520 may include one or more modules, each corresponding to a set of instructions. Furthermore, the processing component 510 is configured to execute instructions to perform the aforementioned method for fabricating epitaxial wafers.
[0118] Electronic device 500 may also include a power supply component configured to perform power management of electronic device 500, a wired or wireless network interface configured to connect electronic device 500 to a network, and an input / output (I / O) interface. Electronic device 500 may operate on an operating system stored in memory 520, such as Windows Server™, Mac OSX™, Unix™, Linux™, FreeBSD™, or similar.
[0119] A non-transitory computer-readable storage medium, wherein when the instructions in the storage medium are executed by the processor of the aforementioned electronic device 500, the electronic device 500 is able to perform the aforementioned method for preparing an epitaxial wafer.
[0120] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.
[0121] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.
[0122] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.
[0123] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.
[0124] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.
[0125] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program verification codes, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.
[0126] Furthermore, it should be noted that the combination of the various technical features in this case is not limited to the combination methods described in the claims of this case or the combination methods described in the specific embodiments. All technical features described in this case can be freely combined or combined in any way, unless they contradict each other.
[0127] It should be noted that the above examples are merely specific embodiments of the present invention, and the present invention is obviously not limited to the above embodiments, with many similar variations. All modifications that can be directly derived or conceived by those skilled in the art from the content disclosed in this invention should fall within the protection scope of this invention.
[0128] It should be understood that the terms "first," "second," etc., mentioned in the embodiments of the present invention are merely for the purpose of more clearly describing the use of the technical solutions in the embodiments of the present invention, and are not intended to limit the scope of protection of the present invention.
[0129] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing an epitaxial wafer, characterized in that, The method includes: An epitaxial wafer is obtained by epitaxial growth of a polished wafer loaded with an epitaxial growth device. Obtain the morphological feature information of the epitaxial wafer, wherein the morphological feature information includes thickness information and / or flatness information; If the morphological feature information does not meet the preset conditions, the target equipment parameters of the epitaxial growth equipment are adjusted. The target equipment parameters are used to control the placement position of the loaded polished wafer on the base of the epitaxial growth equipment. Based on the adjusted epitaxial growth equipment, the step of epitaxial growth on the loaded polished wafer using the epitaxial growth equipment is returned to until the morphological feature information meets the preset conditions, so as to complete the adjustment of the epitaxial growth equipment. Epitaxial wafers are prepared using an epitaxial growth device that has been adjusted.
2. The method for preparing an epitaxial wafer according to claim 1, characterized in that, The step of obtaining the morphological feature information of the epitaxial wafer includes: The thickness value corresponding to each of the plurality of first stations on the epitaxial wafer is obtained to obtain a plurality of thickness values, wherein the plurality of first stations are set along the diameter direction of the epitaxial wafer; Determine the maximum and minimum thickness values from the plurality of thickness values; The difference between the maximum thickness value and the minimum thickness value is calculated to obtain a first calculated value; The sum of the maximum thickness value and the minimum thickness value is calculated to obtain a second calculated value; The quotient of the first calculated value and the second calculated value is determined as the thickness information.
3. The method for preparing an epitaxial wafer according to claim 2, characterized in that, The method further includes: If the thickness information is greater than or equal to a preset threshold, then the morphological feature information is determined not to meet the preset conditions.
4. The method for preparing an epitaxial wafer according to claim 3, characterized in that, The preset threshold is 2%.
5. The method for preparing an epitaxial wafer according to claim 2, characterized in that, The number of the plurality of first stations is 35, wherein the distance between any two adjacent first stations is equal.
6. The method for preparing an epitaxial wafer according to claim 1, characterized in that, The step of obtaining the morphological feature information of the epitaxial wafer includes: The ESFQD value corresponding to each of the plurality of second stations on the epitaxial wafer is obtained to obtain a plurality of ESFQD values, wherein the plurality of second stations are set along the edge of the epitaxial wafer; The average value of the multiple ESFQD values is determined as the flatness information.
7. The method for preparing an epitaxial wafer according to claim 6, characterized in that, The method further includes: If the average of the multiple ESFQD values is greater than or equal to a first threshold, or if the average of the multiple ESFQD values is less than or equal to a second threshold, then it is determined that the morphological feature information does not meet the preset conditions.
8. The method for preparing an epitaxial wafer according to claim 7, characterized in that, The first threshold is 30, and the second threshold is -40.
9. The method for preparing an epitaxial wafer according to claim 6, characterized in that, The angle between any two adjacent second stations and the center of the epitaxial wafer is 5 degrees.
10. The method for preparing an epitaxial wafer according to any one of claims 1 to 9, characterized in that, After adjusting the target equipment parameters of the epitaxial growth equipment if the morphological feature information does not meet the preset conditions, the method further includes: Record the current number of adjustments made to the target device parameters; If the current number of adjustments exceeds the preset number, then the specified equipment parameters of the epitaxial growth equipment are adjusted. The specified equipment parameters are used to control the thermal field distribution in the reaction chamber of the epitaxial growth equipment. If the thermal field distribution in the reaction chamber of the epitaxial growth equipment meets the preset thermal field conditions, then the step of epitaxial growth on the loaded polished wafer through the epitaxial growth equipment is returned to be executed until the morphological feature information meets the preset conditions, so as to complete the adjustment of the epitaxial growth equipment.
11. An epitaxial wafer, characterized in that, The epitaxial wafer is manufactured by the method for preparing an epitaxial wafer as described in any one of claims 1 to 10. The ESFQD of the epitaxial wafer is greater than -40 and less than 30; The thickness uniformity of the epitaxial wafer is less than 2%; The nanomorphological change measured in the 10μm×10μm region around the contact point between the surface of the epitaxial wafer and the support pin is less than or equal to 10nm.
12. An epitaxial growth apparatus, characterized in that, include: Controller; as well as Memory used to store executable instructions of the controller; The controller is used to execute the method for preparing an epitaxial wafer as described in any one of claims 1 to 10.