A method and system for coordinated control of temperature and current in vapor phase epitaxial growth

Abstract

This invention belongs to the field of crystal growth control technology, specifically relating to a method and system for coordinated temperature and flow control in vapor phase epitaxial growth. The method includes: real-time acquisition of heating power, real-time temperature, and process gas flow rate in each temperature zone of the reaction chamber; after time alignment and filtering, constructing an equivalent thermal coupling gap factor characterizing the local geometric deformation trend of the wafer based on the heating power and real-time temperature; deriving the mass transfer boundary layer distortion index by combining the equivalent thermal coupling gap factor and the process gas flow rate; calculating the equivalent resistivity temperature compensation command based on its impact on doping mass transfer efficiency; and driving the multi-temperature zone heating system to perform non-uniform coordinated control after safety limiting and smoothing processing. This invention effectively alleviates the problem of uniform temperature but non-uniform resistance, improving the global uniformity of surface resistance and process stability of epitaxial layers on large-size wafers.

Description

Technical Field

[0001] This invention relates to the field of crystal growth control technology. More specifically, this invention relates to a method and system for coordinated temperature and current control in vapor phase epitaxial growth. Background Technology

[0002] Metal-organic chemical vapor deposition (MOCVD) is a core technology for preparing high-performance crystalline materials. Existing equipment has achieved highly uniform global wafer temperature within the reaction chamber through multi-temperature zone independent heating and advanced decoupled control algorithms, providing a reliable thermal environment for high-quality epitaxial growth of crystalline materials.

[0003] However, in the process of industrializing large-size epitaxial wafers, as the wafer size increases and the epitaxial layer thickness increases, the internal stress generated by the difference in thermal expansion coefficients and lattice mismatch between the multilayer materials becomes increasingly significant, leading to non-negligible mechanical warping of the wafer, which becomes a key factor affecting process consistency. Especially during the base region growth stage, in order to achieve high-frequency characteristics, an extremely thin and highly doped structure design is usually adopted, making this region extremely sensitive to growth conditions. At this time, the micro-geometric deformation of the wafer surface will change the cross-sectional distribution of the local airflow channels in the reaction cavity, destroy the ideal laminar flow state, and thus cause spatial non-uniformity of the airflow boundary layer thickness. Since dopant molecules need to cross the boundary layer to participate in the surface reaction, their incorporation efficiency is directly controlled by the mass transfer rate, which is closely related to the boundary layer thickness. Therefore, even if the temperature field is highly uniform, the mass transfer difference caused by warping in each region will still cause the doping concentration to deviate from the expectation, which will eventually manifest as radial non-uniformity of surface resistance. This phenomenon seriously restricts the consistency of device performance and yield improvement on large-size wafers. Traditional temperature control strategies only aim at temperature equalization and cannot compensate for the mass transfer deviation caused by flow field distortion, making it difficult to meet the stringent requirements of high-performance crystal epitaxial layers for electrical uniformity. Summary of the Invention

[0004] To address the technical problem of wafer warping causing airflow boundary layer distortion, resulting in uneven mass transfer and radial differences in surface resistance, the present invention provides solutions in the following aspects.

[0005] In a first aspect, the present invention provides a method for coordinated temperature and current control in vapor phase epitaxial growth, comprising:

[0006] The system collects heating power, real-time temperature, and process gas flow rate in each temperature zone of the reaction chamber in real time, and performs time-series alignment and filtering on the collected data. Based on the heating power and real-time temperature of each temperature zone, an equivalent thermal coupling gap factor is constructed to characterize the local geometric deformation trend of the wafer. Combining the equivalent thermal coupling gap factor and process gas flow rate, a mass transfer boundary layer distortion index characterizing the degree of distortion of the gas flow boundary layer thickness is derived based on fluid dynamics boundary layer theory. According to the influence of the mass transfer boundary layer distortion index on the doping mass transfer efficiency, an equivalent resistivity temperature compensation command is calculated to offset the mass transfer deviation and achieve uniform surface resistance. After safety limiting and smoothing the equivalent resistivity temperature compensation command, it is sent to the multi-temperature zone heating system for non-uniform collaborative control to achieve uniform surface resistance of the wafer.

[0007] This invention effectively eliminates time asynchrony and high-frequency noise interference between multi-source signals by real-time acquisition of heating power, real-time temperature, and process gas flow rate in each temperature zone of the reaction chamber, and performs time alignment and filtering on the acquired data, ensuring the accuracy of the input status. Based on this, an equivalent thermal coupling gap factor is constructed to characterize the local geometric deformation trend of the wafer, based on the heating power and real-time temperature of each temperature zone, enabling online sensing of thermal contact anomalies caused by wafer warpage. Combining this equivalent thermal coupling gap factor and process gas flow rate, a mass transfer boundary layer distortion index is derived, accurately reflecting the spatial differences in dopant mass transfer efficiency caused by changes in the gas flow channel. Based on the influence of this mass transfer boundary layer distortion index on the doping process, an equivalent resistivity temperature compensation command is calculated, enabling temperature control to compensate for mass transfer non-uniformity. After safety limiting and smoothing, the equivalent resistivity temperature compensation command is sent to the multi-temperature zone heating system for non-uniform collaborative control, avoiding control actions exceeding the equipment and process window. Ultimately, under actual growth conditions with wafer warpage, high uniformity of global surface resistance of the wafer is achieved, improving the stability of the epitaxial growth process and the consistency of device performance.

[0008] Preferably, the equivalent thermal coupling gap factor satisfies the following expression: ;in, Indicates the first Equivalent thermal coupling gap factor in the temperature range; Indicates the first Real-time output power in the temperature range; Indicates the first Real-time temperature of the temperature zone; It is the Stefan-Boltzmann constant; For the first Effective heating area of ​​the temperature zone; The surface emissivity of the tray material; The preset reference thermal conductivity; This refers to the ambient temperature of the reaction chamber.

[0009] This invention constructs an equivalent thermal coupling gap factor based on the heating power and real-time temperature of each temperature zone to characterize the local geometric deformation trend of the wafer. It can indirectly invert the contact state difference between the back side of the wafer and the tray by utilizing the change of thermal boundary conditions when the wafer warping state cannot be directly observed during high-temperature growth. This enables non-invasive perception of micro-mechanical deformation and provides a key preliminary basis for subsequent compensation control.

[0010] Preferably, the effective heating area is predetermined based on the physical layout and radiation field distribution of the heaters in each temperature zone of the reaction chamber, through optical simulation or actual measurement calibration, and stored as a system constant in the control parameter library; the surface emissivity of the tray material is obtained by consulting a material database or through a blackbody radiation comparison experiment based on the tray material type and its surface condition, and is updated after each tray replacement or maintenance.

[0011] Preferably, the mass transfer boundary layer distortion index is determined based on the deviation of the equivalent thermal coupling gap factor from the average value of all temperature zones, the sensitivity of the reaction chamber geometry to the gas flow rate, the empirical power-law relationship of the fluid state, and the ratio of the current total process gas flow rate to the baseline process flow rate.

[0012] Preferably, the mass transfer boundary layer distortion index satisfies the expression: ;in, Indicates the first Mass transfer boundary layer distortion index in the temperature range; Indicates the first Equivalent thermal coupling gap factor in the temperature range; This is the average value of the equivalent thermal coupling gap factor across all temperature zones; The geometric fluid sensitivity coefficient; The empirical power-law exponent related to the fluid Reynolds number; This represents the total process gas flow rate entering the reaction chamber at the current moment. This is the baseline process flow rate.

[0013] This invention combines the equivalent thermal coupling gap factor and process gas flow rate to derive the mass transfer boundary layer distortion index, which can transform thermal sensing results into an impact assessment at the fluid dynamics level. This invention fully considers the gas flow channel contraction effect caused by the geometric rise of the wafer surface and the dynamic impact of process gas flow rate fluctuations on the boundary layer thickness, and can more accurately reflect the spatial differences in the ability of dopant molecules to transport to the wafer surface in different regions, thereby improving the accuracy of mass transfer state modeling.

[0014] Preferably, the equivalent resistivity temperature compensation command is obtained by superimposing the dynamic decoupling compensation amount caused by mass transfer boundary layer distortion and the thermal field uniformity correction amount caused by the deviation of the equivalent thermal coupling gap factor on the basis of the reference growth temperature.

[0015] Preferably, the method for obtaining the equivalent resistivity temperature compensation command is as follows: calculate the corrected target set temperature for each temperature zone, and use the corrected target set temperature as the equivalent resistivity temperature compensation command; the corrected target set temperature satisfies the expression: ,in, For the first The target set temperature after temperature range correction; This is the reference growth temperature in the process formulation; Boltzmann's constant; This is the effective activation energy for the dopant incorporation reaction; For gain correction of thermal field uniformity with temperature dimensions; Indicates the first Mass transfer boundary layer distortion index in the temperature range; Indicates the first Equivalent thermal coupling gap factor in the temperature range; This is the average value of the equivalent thermal coupling gap factor for all temperature zones.

[0016] This invention calculates the equivalent resistivity temperature compensation command based on the influence of the mass transfer boundary layer distortion index on the doping mass transfer efficiency. It can actively adjust the local growth temperature for mass transfer-limited regions and use the strong sensitivity of temperature to surface reaction rate to balance the doping deficiency caused by boundary layer thickening. This achieves closed-loop compensation from mass transfer deviation to thermodynamic response, effectively alleviating the on-chip doping concentration gradient caused by non-uniform flow field.

[0017] Preferably, the safety limiting process includes: setting a maximum allowable temperature offset; when the absolute value of the difference between the calculated equivalent resistivity temperature compensation command and the reference growth temperature exceeds the maximum allowable temperature offset, clamping the target set temperature within the range of the reference growth temperature plus or minus the maximum allowable temperature offset.

[0018] This invention performs safety limiting and smoothing processing on the equivalent resistivity temperature compensation command before sending it to the multi-temperature zone heating system for non-uniform collaborative control. This can smoothly introduce the required temperature gradient while ensuring process safety, avoiding equipment overload, material composition deviation or interface morphology deterioration caused by sudden command changes or exceeding limits, and ensuring that the high uniformity of the global surface resistance of the wafer is stably achieved under actual working conditions with wafer warping.

[0019] Preferably, the filtering process employs a moving average filtering algorithm.

[0020] Secondly, the present invention provides a temperature and flow coordinated control system for vapor phase epitaxial growth, including a processor and a memory. The memory stores computer program instructions, and when the computer program instructions are executed by the processor, the above-mentioned temperature and flow coordinated control method for vapor phase epitaxial growth is realized.

[0021] By adopting the above technical solution, a computer program is generated from the above-mentioned method for temperature and flow synergistic control of vapor phase epitaxial growth and stored in a memory so that it can be loaded and executed by a processor. In this way, a terminal device can be made based on the memory and the processor for convenient use.

[0022] The beneficial effects of this invention are as follows: By real-time acquisition of heating power, real-time temperature, and process gas flow rate in each temperature zone of the reaction chamber, and performing time-series alignment and filtering, the invention ensures the synchronization and reliability of the input data. Based on this, an equivalent thermal coupling gap factor is constructed using the heating power and real-time temperature of each temperature zone to characterize the local geometric deformation trend of the wafer. This enables indirect perception of changes in the thermal contact state of the wafer caused by stress warping under high-temperature growth conditions. Furthermore, by combining this equivalent thermal coupling gap factor with the process gas flow rate, the mass transfer boundary layer distortion index is derived, converting geometric deformation information into the airflow boundary layer thickness. The distribution variation accurately reflects the difference in mass transfer efficiency in different regions. Then, based on the influence of the mass transfer boundary layer distortion index on the surface resistance uniformity, the equivalent resistivity temperature compensation command is calculated. The doping deviation caused by the uneven mass transfer is dynamically compensated by the strong control capability of temperature on the doping reaction rate. Finally, the compensation command is subjected to safety limiting and smoothing processing and the multi-temperature zone heating system is driven to perform non-uniform collaborative control, so that the thermal field in the reaction chamber actively adapts to the flow field distortion. Thus, even under the actual working condition of micro-warpage of the wafer, a high degree of uniformity of the global surface resistance of the wafer can still be achieved, which improves the quality consistency and process robustness of the epitaxial layer. Attached Figure Description

[0023] Figure 1 This is a schematic flowchart illustrating a method for coordinated temperature and flow control in vapor phase epitaxial growth according to the present invention;

[0024] Figure 2 A schematic diagram showing the trend of the equivalent thermal coupling gap factor over time in each temperature zone;

[0025] Figure 3 A schematic diagram showing the trend of mass transfer boundary layer distortion index over time in each temperature zone;

[0026] Figure 4 A schematic diagram showing the trend of the offset of the equivalent resistivity temperature compensation command in each temperature zone over time.

[0027] Figure 5 This is a polar coordinate thermogram of the active temperature compensation distribution of the wafer. Detailed Implementation

[0028] 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, not all, of the embodiments of the present invention. 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.

[0029] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0030] This invention discloses a method for coordinated temperature and current control in vapor phase epitaxial growth, referring to... Figure 1 This includes steps S1-S5:

[0031] S1. Real-time acquisition of heating power, real-time temperature, and process gas flow rate in each temperature zone of the reaction chamber, and time-series alignment and filtering of the acquired data.

[0032] Specifically, operating status data of each temperature zone in the reaction chamber are synchronously collected at a preset sampling frequency. This operating status data includes the real-time output power of the heaters in each of the inner, middle, and outer temperature zones of the reaction chamber, the real-time temperature of the thermocouples at the corresponding locations, and the total process gas flow rate entering the reaction chamber at the current moment. In this embodiment, the sampling frequency is set to 10Hz. In other embodiments, the implementer can set the sampling frequency according to the actual implementation situation.

[0033] It should be noted that in metal-organic chemical vapor deposition systems, the heater power supply, thermocouple acquisition module, and gas mass flow controller are often managed by different control modules. Data transmission suffers from varying degrees of time delay, and different sensors respond differently to changes in the physical environment. Directly using the acquired raw data for calculations may lead to asynchronous input variables in the model, failing to accurately reflect the system state at any given moment. Furthermore, the raw data often contains high-frequency electromagnetic noise introduced by the high-power heating power supply. Without processing, this noise will overwhelm the subsequently calculated microscopic warping features, causing severe oscillations in the control output. Therefore, this invention performs filtering and timing alignment on the acquired operating status data.

[0034] Specifically, a moving average filtering algorithm is used to filter out high-frequency noise from the operating status data, and interpolation and alignment of each dimension of the operating status data are performed based on timestamps to ensure that the real-time output power and real-time temperature of each temperature zone strictly correspond to the thermodynamic state at the same physical moment. It should be noted that this invention only uses the moving average filtering algorithm as an example for illustration. Implementers can choose the filtering algorithm according to the actual implementation situation, such as the median filtering algorithm, etc.

[0035] S2. Based on the heating power and real-time temperature of each temperature zone, construct an equivalent thermal coupling gap factor to characterize the local geometric deformation trend of the wafer.

[0036] It should be noted that under existing high-precision temperature control, the distribution of heating power can sensitively reflect changes in ambient thermal resistance. Under ideal planar contact conditions, the heating power required to maintain a specific temperature should follow fixed radiation laws and contact heat conduction laws. When wafer warping occurs, such as edge warping, the physical gap between the wafer backside and the graphite tray changes, leading to a significant change in local contact thermal resistance. This change in thermal resistance directly disrupts the original power-temperature balance; that is, when the temperature remains constant, abnormal fluctuations in power characterize changes in thermal resistance. Therefore, this invention constructs a comprehensive index that reflects changes in thermal boundary conditions in various regions of the wafer by analyzing the ratio of actual power to theoretical reference power, thereby indirectly characterizing the geometric deformation trend caused by warping in that region.

[0037] Specifically, the equivalent thermal coupling gap factor for each temperature zone satisfies the following expression:

[0038]

[0039] in, Indicates the first Equivalent thermal coupling gap factor in the temperature range; Indicates the first Real-time output power in the temperature range; Indicates the first Real-time temperature of the temperature zone; It is the Stefan-Boltzmann constant; For the first Effective heating area of ​​the temperature zone; The surface emissivity of the tray material; The preset reference thermal conductivity represents the system's heat dissipation characteristics under no-warpage conditions; This refers to the ambient temperature of the reaction chamber.

[0040] In the formula, This reflects the temperature maintenance under standard, warp-free conditions. The required theoretical energy flow means that when wafer warping causes poor contact and widens the gap, the heater must output more power to maintain the same temperature. To overcome the increased thermal resistance, resulting in The ratio increases as the energy flow exceeds the theoretical energy flow, thus... The changes show a positive correlation. The larger the value, the larger the gap between the wafer and the tray in that area, and the more severe the warping. This is especially true under ideal, warp-free conditions. Approximately 1. In this embodiment, The effective heating area is obtained by calibration using a standard planar wafer during the baking stage before each epitaxial growth cycle. In other embodiments, it can be obtained by fitting historical data based on actual implementation conditions. Based on the physical layout and radiation field distribution of the heaters in each temperature zone of the reaction chamber, the parameters are predetermined through optical simulation or actual measurement calibration and stored as system constants in the control parameter library; the surface emissivity of the tray material... The data is obtained by consulting a material database or through a blackbody radiation comparison experiment based on the material type and surface condition of the pallet, and is updated after each pallet replacement or maintenance.

[0041] Preferably, the reference thermal conductivity The calibration process is as follows: A warp-free standard planar wafer is loaded into the reaction chamber, the same temperature ramp program as the formal growth is run, and the real-time output power of each temperature zone is recorded after it reaches steady state. With real-time temperature The temperature ramp program refers to the process of uniformly increasing the temperature from room temperature to the reference growth temperature and maintaining it for a sufficient time to achieve thermodynamic steady state; based on the expression Combined with known , and ambient temperature This leads to the derivation of the method that matches the theoretical energy consumption with the measured power. The values ​​are stored in the system parameter library. This calibration method eliminates the interference of wafer warpage on thermal resistance measurement, ensuring accuracy. As a benchmark for the system's heat dissipation characteristics under warp-free conditions, it provides a reliable basis for the accurate calculation of the equivalent thermal coupling gap factor.

[0042] For example, Figure 2 The diagram shows the trend of the equivalent thermal coupling gap factor changing over time in each temperature zone. When the outer wafer warps at the 10th second, the equivalent thermal coupling gap factor in the outer temperature zone increases significantly and deviates from the reference value of 1.0, while the inner zone remains stable. This verifies the ability of the equivalent thermal coupling gap factor to characterize changes in local contact thermal resistance.

[0043] S3. Combining the equivalent thermal coupling gap factor and process gas flow rate, the mass transfer boundary layer distortion index, which characterizes the degree of distortion of the gas flow boundary layer thickness, is derived based on the fluid dynamics boundary layer theory.

[0044] It should be noted that the microscopic warpage of a wafer not only alters thermal resistance but also changes the gas flow boundary conditions on the wafer's upper surface, leading to changes in the flow channel cross-section. For example, when the wafer edge warps upwards, the flow channel above that region narrows. According to Bernoulli's principle, the gas velocity will locally increase. Fluid boundary layer theory states that the boundary layer thickness is inversely proportional to the flow velocity. In epitaxial growth, the mass transfer rate of dopant molecules passing through the boundary layer to reach the wafer surface directly depends on the boundary layer thickness. Therefore, this invention maps the thermal gap factor to boundary layer distortion in the hydrodynamic dimension to accurately assess its impact on surface resistance.

[0045] Specifically, the mass transfer boundary layer distortion index for each temperature zone satisfies the following expression:

[0046]

[0047] in, Indicates the first Mass transfer boundary layer distortion index in the temperature range; Indicates the first Equivalent thermal coupling gap factor in the temperature range; This is the average value of the equivalent thermal coupling gap factor across all temperature zones; This is the geometric fluid sensitivity coefficient, used to characterize the weight of the effect of wafer height variation on gas flow velocity distribution under a specific geometric structure of the reaction chamber; The empirical power-law exponent related to the fluid Reynolds number reflects the influence of the fluid state on the boundary layer thickness. This represents the total process gas flow rate entering the reaction chamber at the current moment. This is the baseline process flow rate.

[0048] In the formula, The term characterizes the local high distortion relative to the average level, when a certain region A larger value indicates that the height of the region has changed due to warping, resulting in a narrower flow channel cross-section and a reduced throughput coefficient. The mapping indicates an increase in airflow velocity at that location, and further, using a nonlinear relationship, it is deduced that the boundary layer thickness is thinner. Decrease; conversely, when An increase in this value indicates a thicker boundary layer. This is due to the equivalent thermal coupling gap factor. The ratio is its mean. The value is close to 1, thus avoiding singularities in mathematical calculations. In this embodiment, The value is set at 1.5. This value is determined based on the flow field sensitivity analysis under the typical aspect ratio of the reaction chamber, and can effectively reflect the amplification effect of geometric lift on airflow acceleration. A value of 0.5 corresponds to the inverse square root relationship between boundary layer thickness and flow velocity in the transitional flow state, which aligns with the actual fluid dynamics characteristics within the main flow channel. In other embodiments, the implementer can set the value according to the geometric aspect ratio of the reaction chamber and the actual fluid conditions. and The value of .

[0049] For example, Figure 3 This diagram illustrates the trend of mass transfer boundary layer distortion index over time in various temperature zones. As the warping increases, the distortion index of the outer mass transfer boundary layer gradually decreases, indicating that the airflow boundary layer in this region is thinner. Figure 3 The fluctuation of the curve at 30 seconds indicates that the mass transfer boundary layer distortion index can sensitively respond to real-time changes in process gas flow rate.

[0050] S4. Based on the influence of the mass transfer boundary layer distortion index on the doping mass transfer efficiency, calculate the equivalent resistivity temperature compensation command used to offset the mass transfer deviation and achieve uniform surface resistance.

[0051] It should be noted that the surface resistivity of the epitaxial layer is mainly determined by the doping concentration, which is jointly controlled by the thermally activated surface reaction rate and the mass transfer rate across the boundary layer. When the mass transfer rate changes due to boundary layer distortion caused by warping, maintaining the original temperature setting will lead to a deviation of the final doping concentration from the target value. Therefore, this invention no longer takes global isothermalization of the wafer as the sole objective. Instead, based on the mass transfer difference, it calculates the amount of temperature compensation required to compensate for this difference. By utilizing the exponential adjustment capability of temperature on the reaction rate, it offsets the doping error caused by the distortion of the mass transfer boundary layer, thereby achieving uniformity in the final physical property, namely, surface resistivity.

[0052] Specifically, the corrected target set temperature for each temperature zone is calculated, and this corrected target set temperature is used as the equivalent resistivity temperature compensation command.

[0053] The corrected target set temperature satisfies the expression:

[0054]

[0055] in, For the first The target set temperature after temperature range correction; This is the reference growth temperature in the process formulation; Boltzmann's constant; This is the effective activation energy for the dopant incorporation reaction; For gain correction of thermal field uniformity with temperature dimensions; Indicates the first Mass transfer boundary layer distortion index in the temperature range; Indicates the first Equivalent thermal coupling gap factor in the temperature range; This is the average value of the equivalent thermal coupling gap factor for all temperature zones.

[0056] In the formula, This is a kinetic decoupling term used to compensate for changes in the mass transfer rate, if An increase in size indicates a thicker boundary layer, slower mass transfer, and consequently, insufficient doping. If the value is negative, the system will automatically lower the target temperature in that region, using the improved doping efficiency at low temperatures to offset the loss due to impeded mass transfer. This is a thermal field correction term used to preserve the linear correction for the difference in basic thermal resistance, where... The unit is Kelvin, ensuring the consistency of the physical dimensions of the superposition terms. In this embodiment, Depending on the specific type of dopant source, for example, when using carbon tetrabromide ( When used as a carbon doping source, its effective activation energy for the incorporation reaction was experimentally determined to be approximately 1.8 eV; The value of K needs to balance the ability to suppress thermal disturbances with the risk of excessive temperature gradient. After multiple batches of process verification, 0.5K was found to achieve the optimal balance between resistivity uniformity and growth morphology stability on this equipment platform. In other embodiments, the implementer can set the K value according to the actual material system and equipment thermal characteristics. and The value of .

[0057] S5. After performing safety limiting and smoothing on the equivalent resistivity temperature compensation command, it is sent to the multi-temperature zone heating system to perform non-uniform collaborative control in order to achieve uniformity of the global surface resistance of the wafer.

[0058] It should be noted that although the theoretical equivalent resistivity temperature compensation command is calculated, in actual growth, each layer of material has strict process window limitations regarding temperature. Excessive temperature offset may lead to compositional deviation or morphological deterioration. Furthermore, the heater's response to control commands exhibits physical inertia, and sudden changes in commands may cause system overload. Therefore, this invention introduces engineered safety constraints before execution to ensure that control commands are executed smoothly within the limits of equipment safety and process allowances.

[0059] Specifically, set the maximum allowable temperature offset. If the calculated Then force Clamping in Within the range, among which, For the first The target set temperature after temperature range correction; This is the baseline growth temperature in the process formulation. Meanwhile, to avoid sudden changes in the temperature setpoint impacting the heater, a first-order low-pass filter is used. After smoothing, the processed instructions are sent to each temperature zone controller. The system will automatically balance under the new set values, thereby achieving uniform surface resistance across the wafer even under warping conditions. In this embodiment... The temperature is set to 5 degrees Celsius. In other embodiments, the implementer can set the temperature according to the specific process requirements for temperature sensitivity. The value of .

[0060] For example, Figure 4 This is a schematic diagram illustrating the trend of the equivalent resistivity temperature compensation command offset in each temperature zone over time. Figure 4 The study demonstrated differentiated temperature control strategies implemented for different temperature zones. The outer zone was subjected to a positive temperature bias, while the inner zone was subjected to a negative temperature bias. At the same time, the control commands were strictly limited to the set safety upper and lower limits, resulting in a smooth change trajectory.

[0061] Figure 5 A polar coordinate thermogram of the active temperature compensation distribution of the wafer, from Figure 5 It can be seen that, in order to offset the mass transfer differences caused by edge warping, the system applies a non-uniform cooperative control distribution by applying heating compensation to the outer region and cooling compensation to the inner region.

[0062] This invention also discloses a temperature and flow coordinated control system for vapor phase epitaxial growth, including a processor and a memory. The memory stores computer program instructions, and when the computer program instructions are executed by the processor, a temperature and flow coordinated control method for vapor phase epitaxial growth according to the present invention is implemented.

[0063] The system also includes other components well known to those skilled in the art, such as communication buses and communication interfaces, the settings and functions of which are known in the art and will not be described in detail here.

Claims

1. A method for coordinated temperature and current control in vapor phase epitaxial growth, characterized in that, include: The system collects heating power, real-time temperature, and process gas flow rate in each temperature zone of the reaction chamber in real time, and performs time-series alignment and filtering on the collected data. Based on the heating power and real-time temperature of each temperature zone, an equivalent thermal coupling gap factor is constructed to characterize the local geometric deformation trend of the wafer. , ; For the first Real-time output power in the temperature range; For the first Real-time temperature of the temperature zone; It is the Stefan-Boltzmann constant; For the first Effective heating area of ​​the temperature zone; The surface emissivity of the tray material; The preset reference thermal conductivity; The ambient temperature of the reaction chamber; Combining the equivalent thermal coupling gap factor and process gas flow rate, the mass transfer boundary layer distortion index, which characterizes the degree of distortion of the gas flow boundary layer thickness, is derived based on the fluid dynamics boundary layer theory. This includes: determining the mass transfer boundary layer distortion index based on the deviation of the equivalent thermal coupling gap factor from the average value of all temperature zones, the sensitivity of the reaction chamber geometry to the gas flow velocity, the empirical power-law relationship of the fluid state, and the ratio of the current total process gas flow rate to the baseline process flow rate. Based on the influence of mass transfer boundary layer distortion index on doping mass transfer efficiency, the equivalent resistivity temperature compensation command for offsetting mass transfer deviation to achieve uniform surface resistance is calculated, including: based on the reference growth temperature, superimposing the dynamic decoupling compensation amount caused by mass transfer boundary layer distortion and the thermal field uniformity correction amount caused by equivalent thermal coupling gap factor deviation to obtain the equivalent resistivity temperature compensation command. After the equivalent resistivity temperature compensation command is subjected to safety limiting and smoothing processing, it is sent to the multi-temperature zone heating system to perform non-uniform collaborative control in order to achieve uniformity of the global surface resistance of the wafer.

2. The method for coordinated temperature and current control in vapor phase epitaxial growth according to claim 1, characterized in that, The effective heating area is predetermined based on the physical layout and radiation field distribution of the heaters in each temperature zone of the reaction chamber, through optical simulation or actual measurement calibration, and is stored as a system constant in the control parameter library; the surface emissivity of the tray material is obtained by consulting the material database or through blackbody radiation comparison experiments based on the tray material type and its surface condition, and is updated after each tray replacement or maintenance.

3. The method for coordinated temperature and current control in vapor phase epitaxial growth according to claim 1, characterized in that, The mass transfer boundary layer distortion index satisfies the expression: ； in, Indicates the first Mass transfer boundary layer distortion index in the temperature range; Indicates the first Equivalent thermal coupling gap factor in the temperature range; This is the average value of the equivalent thermal coupling gap factor across all temperature zones; The geometric fluid sensitivity coefficient; The empirical power-law exponent related to the fluid Reynolds number; This represents the total process gas flow rate entering the reaction chamber at the current moment. This is the baseline process flow rate.

4. The method for coordinated temperature and current control in vapor phase epitaxial growth according to claim 1, characterized in that, The method for obtaining the equivalent resistivity temperature compensation command is as follows: Calculate the corrected target set temperature for each temperature zone, and use this corrected target set temperature as the equivalent resistivity temperature compensation command; the corrected target set temperature satisfies the expression: ,in, For the first The target set temperature after temperature range correction; This is the reference growth temperature in the process formulation; Boltzmann's constant; This is the effective activation energy for the dopant incorporation reaction; For gain correction of thermal field uniformity with temperature dimensions; Indicates the first Mass transfer boundary layer distortion index in the temperature range; Indicates the first Equivalent thermal coupling gap factor in the temperature range; This is the average value of the equivalent thermal coupling gap factor for all temperature zones.

5. The method for coordinated temperature and current control in vapor phase epitaxial growth according to claim 1, characterized in that, The safety limiting process includes: setting a maximum allowable temperature offset; when the absolute value of the difference between the calculated equivalent resistivity temperature compensation command and the reference growth temperature exceeds the maximum allowable temperature offset, clamping the target set temperature within the range of the reference growth temperature plus or minus the maximum allowable temperature offset.

6. The method for coordinated temperature and current control in vapor phase epitaxial growth according to claim 1, characterized in that, The filtering process employs a moving average filtering algorithm.

7. A temperature and current synergistic control system for vapor phase epitaxial growth, characterized in that, include: A processor and a memory, wherein the memory stores computer program instructions that, when executed by the processor, implement a method for coordinated temperature and flow control of vapor phase epitaxial growth according to any one of claims 1-6.

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