A temperature difference control method based on power compensation

Abstract

The application discloses a temperature difference control method based on power compensation, comprising: in the process of wafer heating, real-time power compensation is carried out on the lower heating assembly or the upper heating assembly by using a variable power compensation factor; the change of the power compensation factor comprises: dividing a temperature difference increasing stage into a plurality of first-type continuous subintervals, the power compensation factors corresponding to the first-type continuous subintervals are increased gradually from 0 to a preset maximum power compensation factor; and dividing a temperature difference decreasing stage into a plurality of second-type continuous subintervals, the power compensation factors corresponding to the second-type continuous subintervals are decreased gradually from the maximum power compensation factor to 0. The application controls the temperature difference between the upper surface of the wafer and the lower surface of the base in the heating process by power compensation, so that the wafer is heated more uniformly.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing, and in particular to a temperature difference control method based on power compensation. Background Technology

[0002] Semiconductor equipment typically uses upper and lower heating components to heat the upper surface of the wafer and the lower surface of the substrate, respectively. However, during the heating process, due to differences in the arrangement of the upper and lower heat sources and the thermal capacity characteristics of the wafer and substrate, the temperature responses of the upper surface of the wafer and the lower surface of the substrate exhibit significant asynchronous characteristics. Specifically, the actual heating rate of the upper surface of the wafer, measured by the top pyrometer, shows a trend of slow initial heating followed by faster heating, while the actual heating rate of the lower surface of the substrate, measured by the bottom pyrometer, shows a trend of fast initial heating followed by slower heating. This asymmetrical heating rate causes the absolute value of the temperature difference between the two to gradually increase in the initial stage of heating, reach its maximum value, and then gradually decrease as the heating process continues.

[0003] During heat treatment, the temperature difference between the upper surface of the wafer and the lower surface of the substrate can lead to uneven heating of the wafer's upper and lower surfaces, resulting in defects such as wafer warpage and slip lines. These defects will reduce the final chip production yield and seriously affect the electrical performance and long-term reliability of the device. Therefore, there is an urgent need for a method to control the temperature difference between the upper and lower surfaces of the wafer during the heating process in semiconductor equipment in order to improve the heating uniformity of the wafer.

[0004] The statements herein provide only background information in relation to the present invention and do not necessarily constitute prior art. Summary of the Invention

[0005] The purpose of this invention is to provide a temperature difference control method based on power compensation, which enables synchronous heating of the upper and lower surfaces of a wafer in a semiconductor device, resulting in more uniform heating of the wafer.

[0006] To achieve the above objectives, the present invention provides a temperature difference control method based on power compensation, comprising: The first theoretical heating curve of the upper surface of the wafer and the second theoretical heating curve of the lower surface of the substrate are obtained in advance, corresponding to the heating from the starting temperature to the target temperature at a predetermined heating rate. A theoretical temperature difference curve is constructed based on the first and second theoretical temperature rise curves to determine the maximum temperature difference. ; with the maximum temperature difference Using the time point as the boundary, the heating process is divided into a stage of increasing temperature difference and a stage of decreasing temperature difference; The wafer is heated from the starting temperature to the target temperature at the predetermined heating rate, and a varying power compensation factor is used during the heating process. Real-time power compensation is performed on the lower heating assembly located below the base or the upper heating assembly located above the wafer; In the process of real-time power compensation, the power compensation factor The changes include: The stage of increasing temperature difference is divided into: The first type of continuous subintervals, the Power compensation factor corresponding to each type of continuous sub-interval Incrementing gradually from 0 to the preset maximum power compensation factor. ; The temperature difference reduction stage is divided into: The second type of continuous sub-intervals, the Power compensation factor corresponding to each second type of continuous sub-interval Decreasing, due to the maximum power compensation factor Gradually reduce to 0.

[0007] Optionally, the maximum power compensation factor The calculation formula is: In the formula, This is the proportional gain coefficient, and its value ranges from 0.5 to 0.8 °C. -1 .

[0008] Optionally, the proportional gain coefficient The value is 0.65.

[0009] Optionally, a preset temperature control cycle for power compensation is established, and power compensation is performed on the lower heating component or the upper heating component once every temperature control cycle. The sum of the number of first-type and second-type continuous sub-intervals is calculated based on the starting temperature, the target temperature, the predetermined heating rate, and the temperature control cycle, using the following formula: In the formula, It is the sum of the number of intervals in the first type of continuous subintervals and the number of intervals in the second type of continuous subintervals. This represents the number of intervals in the first type of continuous subintervals. This represents the number of intervals in the second type of continuous subintervals. The starting temperature, For the target temperature, To achieve the predetermined heating rate, This is the temperature control cycle.

[0010] Optionally, the duration of the temperature difference increase phase is obtained, and the number of intervals of the first type of continuous sub-intervals is calculated based on the duration of the temperature difference increase phase and the temperature control cycle. The calculation formula is as follows: in, The duration of the temperature difference increase phase; Calculate the sum of the number of consecutive subintervals of the first type and the number of consecutive subintervals of the second type. Number of intervals with the first type of continuous subintervals The difference between them yields the number of intervals in the second type of continuous subintervals. The calculation formula is as follows: .

[0011] Optionally, the duration of the temperature difference increase phase is obtained, and the number of intervals of the first type of continuous sub-intervals is calculated based on the duration of the temperature difference increase phase and the temperature control cycle. The calculation formula is as follows: In the formula, The correction factor, ranging from 0.2 to 0.5, is used to correct the time shift of the actual temperature difference curve relative to the theoretical temperature difference curve during the increasing temperature difference phase caused by power compensation. The calculation result of the above formula is rounded down, and the integer value is used as the... ; Calculate the sum of the number of consecutive subintervals of the first type and the number of consecutive subintervals of the second type. Number of intervals with the first type of continuous subintervals The difference between them yields the number of intervals in the second type of continuous subintervals. The calculation formula is as follows: .

[0012] Optionally, power compensation factor The calculation formula is: Among them, a first-type continuous subinterval and The second type of continuous sub-intervals are arranged sequentially to form One power compensation range, It is the interval counting index, that is The power compensation interval in the th A range; This represents the number of intervals in the first type of continuous subintervals. This represents the number of intervals in the second type of continuous subintervals. This is the maximum power compensation factor.

[0013] Optionally, a preset temperature control cycle for power compensation is established, and power compensation is performed on the lower or upper heating component once every temperature control cycle; the actual heating time elapsed since the start of heating is obtained, and an interval counting sequence number is calculated based on the actual heating time and the temperature control cycle. The calculation formula is: in, This refers to the actual heating time that has elapsed since the start of the heating process. For temperature control cycle; The interval counting sequence number for and If the ratio is not an integer, then the smallest integer greater than that ratio is taken as the integer value. .

[0014] Optionally, the theoretical temperature difference curve is calculated by subtracting the temperature value of the second theoretical temperature rise curve at the corresponding time from the temperature value of the first theoretical temperature rise curve at each time. On the theoretical temperature difference curve, the absolute value of its valley is determined as the maximum temperature difference. And record the maximum temperature difference. Current time; On the theoretical temperature difference curve, determine the temperature difference from the initial moment to the maximum temperature difference. The time interval at any given moment is used as the duration of the phase of increasing temperature difference. .

[0015] Optionally, a top pyrometer is used to measure the temperature of the upper surface of the wafer; a bottom pyrometer is used to measure the temperature of the lower surface of the base.

[0016] Optionally, in the top temperature control mode, the base power value allocated to the lower heating component is adjusted based on the comparison between the actual temperature measured by the top high-temperature gauge at the current moment and the target temperature at the corresponding moment in the preset target temperature rise curve; and the power compensation factor corresponding to the current moment is utilized. Power compensation is performed on the base power value to obtain the actual power value of the lower heating component at the current moment; Alternatively, in bottom temperature control mode, the reference power value allocated to the upper heating component is adjusted based on the comparison between the actual temperature measured by the bottom high-temperature gauge at the current moment and the target temperature at the corresponding moment in the preset target temperature rise curve; and the power compensation factor corresponding to the current moment is utilized. Power compensation is performed on the reference power value to obtain the actual power value of the upper heating component at the current moment.

[0017] Optionally, in the top temperature control mode, after power compensation for the lower heating element, the formula for calculating the actual power value of the lower heating element is: In the formula, This is the actual power value of the lower heating element. The base power value is assigned to the lower heating component based on the real-time temperature of the upper surface of the wafer.

[0018] Optionally, in the bottom temperature control mode, after power compensation of the upper heating element, the formula for calculating the actual power value of the upper heating element is as follows: In the formula, This is the actual power value of the upper heating element. The reference power value is assigned to the upper heating component based on the real-time temperature of the lower surface of the base.

[0019] Based on the temperature rise curve characteristics of the upper surface of the wafer and the lower surface of the substrate, this invention controls the temperature difference between the upper surface of the wafer and the lower surface of the substrate in real time during the heating process through power compensation, thereby reducing the temperature difference between the upper and lower surfaces of the wafer during the heating process, making the wafer heat more uniform, and helping to reduce defects such as wafer warping and slip lines caused by uneven heat distribution between the upper and lower surfaces of the wafer. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the semiconductor device in an embodiment of the present invention; Figure 2A This is a schematic diagram illustrating the principle of measuring the temperature of the upper surface of a wafer using a top pyrometer in an embodiment of the present invention. Figure 2B This is a schematic diagram illustrating the principle of the bottom pyrometer measuring the temperature of the lower surface of the base in an embodiment of the present invention; Figure 3 This is a system block diagram of the temperature control system of the semiconductor device in an embodiment of the present invention; Figure 4A This is a schematic diagram comparing the measured temperature rise curves of the upper surface of the wafer and the lower surface of the substrate when the power compensation method of the present invention is not used. Figure 4B Based on Figure 4A The diagram shows the theoretical temperature difference between the upper surface of the wafer and the lower surface of the substrate, calculated from the heating curve shown. Figure 5A This is a schematic diagram of the temperature setting curve and the corresponding power compensation factor changing over time in an embodiment of the present invention. Figure 5B This is a schematic diagram comparing the measured temperature rise curves of the upper surface of the wafer and the lower surface of the substrate after applying the power compensation method of the present invention. Figure 5C This is a schematic diagram showing the actual temperature difference between the upper surface of the wafer and the lower surface of the substrate after applying the power compensation method of the present invention. Figure 6 A flowchart of a temperature difference control method based on power compensation provided in an embodiment of the present invention. Detailed Implementation

[0021] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, further illustrates the power-compensated temperature difference control method proposed in this invention. The advantages and features of this invention will become clearer from the following description. It should be noted that the accompanying drawings are in a very simplified form and use non-precise proportions, intended only to facilitate and clearly illustrate the embodiments of this invention. Please refer to the accompanying drawings to make the objectives, features, and advantages of this invention more apparent and understandable. It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only for illustrative purposes to aid those skilled in the art and are not intended to limit the implementation conditions of this invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by this invention, should still fall within the scope of the technical content disclosed in this invention.

[0022] The power-compensated temperature difference control method provided by this invention is applied to semiconductor devices with upper and lower heating components. To facilitate understanding and implementation of the temperature difference control method described in this invention, the structure of the semiconductor device implementing this method is illustrated below with reference to the accompanying drawings. It should be understood that the structure of the semiconductor device is not limited to the form shown in the drawings.

[0023] like Figure 1 As shown, in one embodiment, the semiconductor device may be a semiconductor epitaxy device; the semiconductor epitaxy device includes a reaction chamber for processing wafer 5, including depositing material on the upper surface of wafer 5. The reaction chamber has an upper cavity wall 11 at the top, a lower cavity wall 12 at the bottom, and sidewalls extending between the upper cavity wall 11 and the lower cavity wall 12. Optionally, the upper cavity wall 11 and the lower cavity wall 12 are made of an optically transparent or semi-transparent material that is transparent to thermal energy (such as quartz material that is transparent to a specific infrared band).

[0024] The reaction chamber includes an inlet opening at one end and an outlet opening at the other end. The interior of the reaction chamber includes an inlet region corresponding to the inlet opening, an outlet region corresponding to the outlet opening, and a reaction region located between the inlet region and the outlet region. The wafer 5 is located within the reaction region. The reaction gas used for deposition flows into the interior space of the chamber from the inlet opening, performs a chemical vapor deposition process in the reaction region, and exits the chamber from the outlet opening.

[0025] Please continue reading. Figure 1 The lower cavity wall 12 is provided with a downwardly extending extension tube, which accommodates the rotating shaft 9 extending into the internal space of the reaction chamber. The top of the rotating shaft 9 includes multiple support arms 8 for supporting the base 6 and the wafer 5 on the base 6, thereby driving the base 6 and the wafer 5 carried by the base 6 to rotate in the reaction region, thus ensuring the uniformity of thin film deposition on the wafer 5. The semiconductor device also includes a driver (not shown in the figure), which is connected to the rotating shaft 9 and configured to drive the rotating shaft 9 to rotate. The two ends of the support arms 8 are respectively connected to the base 6 and the rotating shaft 9, so that the rotating shaft 9 can drive the base 6 to rotate through the support arms 8. Optionally, the rotating shaft 9 may be made of quartz to reduce the risk of particle contamination.

[0026] Furthermore, the semiconductor device also includes multiple heating components that provide thermal radiation to the reaction chamber and wafer 5. Each heating component is disposed outside the reaction chamber to heat the reaction chamber and the wafer 5 inside. To facilitate understanding of temperature changes within the reaction chamber, the semiconductor device also includes several thermometers. These thermometers are disposed at the top and bottom of the reaction chamber; the thermometer at the top of the reaction chamber is a top thermometer 1, used to measure the top surface temperature of the substrate or wafer; the thermometer at the bottom of the reaction chamber is a bottom thermometer 2, used to measure the bottom surface temperature of the substrate. The multiple heating components include an upper heating component 3 and a lower heating component 4, respectively disposed at the top and bottom of the reaction chamber. The upper heating component 3 at the top heats the wafer supported on the front side of the substrate 6, and the lower heating component 4 at the bottom heats the back side of the substrate 6.

[0027] Specifically, heating components are provided above and below the reaction chamber. These components provide thermal radiation to the reaction chamber and its wafer 5, raising the required process temperature for the semiconductor device. This allows the reactive gases in the reaction chamber to undergo thermal decomposition, resulting in the deposition of a thin film material on the upper surface of the wafer 5. A thermometer is used to measure the temperature within the reaction chamber in real time to control the process. Optionally, the thin film material deposited on the upper surface of the wafer 5 is a semiconductor material such as silicon-germanium or silicon-phosphorus. Further, the heating components are high-intensity tungsten filament lamps with transparent quartz shells and containing halogen gases such as iodine. Only a small portion of the radiant heat generated by this high-intensity tungsten filament lamp is absorbed by the upper and lower walls 11 and 12 of the reaction chamber, ensuring that the heat generated by each heating component is maximized for transfer to the wafer 5 and the reactive gases within the reaction chamber. Of course, the heating components can also be other devices capable of thermal radiation; this invention does not limit the application of these devices.

[0028] like Figure 2A As shown, the top pyrometer 1 is installed above the reaction chamber, with its optical path aligned with the upper surface of the wafer 5; the top pyrometer 1 is configured to receive the infrared radiation energy Q emitted from the upper surface of the wafer 5, and calculate the temperature of the upper surface of the wafer 5 based on the infrared radiation energy Q of the upper surface of the wafer 5.

[0029] like Figure 2B As shown, the bottom pyrometer 2 is installed below the reaction chamber, with its optical path aligned with the lower surface (back side) of the base 6; the bottom pyrometer 2 is configured to receive the infrared radiation energy Q emitted from the lower surface of the base 6, and calculate the temperature of the lower surface of the base 6 based on the infrared radiation energy Q of the lower surface of the base 6.

[0030] Furthermore, such as Figure 3 As shown, the temperature control of the reaction chamber is accomplished through a temperature control system, which includes a programmable logic controller (PLC) 10 and a silicon controlled rectifier (SCR) 7. When executing the process recipe, the target temperature and heating rate are sent to the PLC 10 of the temperature control system. The PLC 10 is connected to the top pyrometer 1 and the bottom pyrometer 2 to obtain real-time temperature readings. Based on the difference between the current reading of the top pyrometer 1 or the bottom pyrometer 2 and the real-time temperature setpoint, the real-time power output is calculated and a control command is generated. The SCR 7 is connected to the PLC 10, and also to the upper heating assembly 3 and the lower heating assembly 4. It is configured to receive the control command and adjust the energizing time of the upper heating assembly 3 and the lower heating assembly 4 by calculating the conduction angle or control angle, so that the temperature of the reaction chamber reaches the requirements set by the process recipe.

[0031] Since the upper surface of the base supports the wafer 5, and pure silicon absorbs radiation in the range of approximately 0.4~1.1 μm, most of the infrared radiation energy from the upper heating component 3 is directly absorbed by the wafer 5. However, only a small portion of the infrared radiation energy from the lower heating component 4 is reflected away by quartz components such as the support arm 8 on the lower surface of the base. The vast majority of the infrared radiation energy from the lower heating component 4 is directly absorbed by the base 6 and then transferred to the lower surface of the wafer through heat conduction. Because heat conduction is a highly efficient heat transfer method, the lower surface of the wafer quickly receives heat from the base 6. Therefore, during the heating process, the temperature of the lower surface of the wafer is essentially the same as the temperature of the lower surface of the base.

[0032] The upper surface of the wafer primarily absorbs infrared radiation energy directly from the upper heating component 3; the lower surface of the wafer primarily absorbs heat from the base 6 through thermal conduction. Due to its extremely high thermal conduction efficiency, the lower surface of the wafer rapidly gains a large amount of heat from the high-temperature base 6. When the power ratio of the upper and lower heating components is the same, the heating rate of the upper surface of the wafer is slower than that of the lower surface of the base because the radiation absorptivity of silicon, the wafer material, is lower than that of graphite, the base material.

[0033] This invention provides a temperature difference control method based on power compensation, such as... Figure 6 As shown, it includes the following steps: S1. Pre-obtain the temperature difference curves between the upper surface of the wafer and the lower surface of the substrate during the wafer heating process without power compensation, to provide a calculation basis for subsequent power compensation. This includes the following steps: S1.1. Pre-obtain the first theoretical heating curve of the upper surface of the wafer and the second theoretical heating curve of the lower surface of the substrate, corresponding to the heating from the starting temperature to the target temperature at a predetermined heating rate.

[0034] Specifically, during the heating process from the initial temperature to the target temperature at a predetermined heating rate, a top pyrometer is used to measure the temperature of the upper surface of the wafer to obtain the heating curve of the upper surface of the wafer, which serves as the first theoretical heating curve; a bottom pyrometer is used to measure the temperature of the lower surface of the base to obtain the heating curve of the lower surface of the base, which serves as the second theoretical heating curve.

[0035] Furthermore, the top pyrometer measures the temperature of the central region of the upper surface of the wafer; the bottom pyrometer measures the temperature of the central region of the lower surface of the base.

[0036] The first theoretical temperature rise curve measured by the top pyrometer and the second theoretical temperature rise curve measured by the bottom pyrometer are as follows: Figure 4A As shown, before reaching the target temperature, the actual temperature rise of the lower surface of the base measured by the bottom pyrometer is fast at first and then slows down. In contrast, the actual temperature rise of the upper surface of the wafer measured by the top pyrometer is slow at first and then fast. The lower surface of the base and the upper surface of the wafer are not heated synchronously.

[0037] S1.2. Construct a theoretical temperature difference curve based on the first theoretical heating curve and the second theoretical heating curve, thereby determining the maximum temperature difference. ; with the maximum temperature difference Using the time point as the boundary, the heating process is divided into a stage of increasing temperature difference and a stage of decreasing temperature difference.

[0038] Specifically, the theoretical temperature difference curve is calculated by subtracting the temperature value of the second theoretical temperature rise curve at the corresponding time from the temperature value of the first theoretical temperature rise curve at each time, as shown below. Figure 4B As shown, during the heating phase, the theoretical temperature difference curve exhibits a trend of first decreasing and then increasing. That is, the absolute value of the temperature difference between the measured upper surface of the wafer and the lower surface of the substrate increases rapidly at first and then decreases slowly. The maximum value of the absolute value of the temperature difference between the two is approximately 40°C to 60°C.

[0039] On the theoretical temperature difference curve, the absolute value of its valley is determined as the maximum temperature difference. And record the maximum temperature difference. At what time. Based on the stated maximum temperature difference. Using the current time as the boundary, determine the time from the start time to the maximum temperature difference. The current time corresponds to a stage of increasing temperature difference, which determines the starting point of the maximum temperature difference. The heating phase from the current moment to the end moment is the phase of decreasing temperature difference.

[0040] Furthermore, on the theoretical temperature difference curve, the time from the initial moment to the maximum temperature difference is determined. The time interval at any given moment is used as the duration of the phase of increasing temperature difference. .

[0041] S2. The wafer is heated from the starting temperature to the target temperature at the predetermined heating rate, and a varying power compensation factor is used during the heating process. Real-time power compensation is performed on the lower heating assembly located below the base or the upper heating assembly located above the wafer.

[0042] In existing technologies, temperature control systems include top-temperature control mode and bottom-temperature control mode. In top-temperature control mode, the process recipe sets a target temperature rise curve. The temperature control system uses the real-time measurement value of the top pyrometer as a feedback signal, compares it with the target temperature at the corresponding moment in the set target temperature rise curve, adjusts the reference power value of the upper heating element based on the comparison result, and simultaneously determines the base power value of the lower heating element according to a preset power ratio, controlling the real-time measurement value of the top pyrometer to reach the real-time target temperature. The bottom-temperature control mode is similar in principle to the top-temperature control mode, except that it uses the real-time measurement value of the bottom pyrometer as a feedback signal. It compares the real-time measurement value of the bottom pyrometer with the target temperature at the corresponding moment in the set target temperature rise curve, adjusts the base power value of the lower heating element based on the comparison result, and simultaneously determines the reference power value of the upper heating element according to a preset power ratio, controlling the real-time measurement value of the bottom pyrometer to reach the real-time target temperature. The specific method for adjusting the reference power value of the upper heating element and the basic power value of the lower heating element in the top temperature control mode is as follows: A temperature control cycle is preset. The measured value of the top pyrometer at each node of the temperature control cycle is compared with the target temperature at the corresponding moment of the set target temperature rise curve. If the measured value at that moment is higher than the real-time target temperature, the reference power value is reduced, and the basic power value of the lower heating element is reduced accordingly. If the measured value at that moment is lower than the real-time target temperature, the reference power value is increased, and the basic power value of the lower heating element is increased accordingly. The reference power value is adjusted once every temperature control cycle, and the basic power value is adjusted accordingly, so that the actual temperature rise curve measured by the top pyrometer approaches the target temperature rise curve. The specific method for adjusting the base power value of the lower heating element and the reference power value of the upper heating element in the bottom temperature control mode is as follows: A temperature control cycle is preset. The measured value of the bottom high-temperature gauge at each node of the temperature control cycle is compared with the target temperature at the corresponding moment of the set target temperature rise curve. If the measured value at that moment is higher than the real-time target temperature, the base power value is reduced, and the reference power value of the upper heating element is reduced accordingly. If the measured value at that moment is lower than the real-time target temperature, the base power value is increased, and the reference power value of the upper heating element is increased accordingly. The base power value is adjusted once every temperature control cycle, and the reference power value is adjusted accordingly, so that the actual temperature rise curve measured by the bottom high-temperature gauge approaches the target temperature rise curve.

[0043] To control the temperature difference between the upper surface of the wafer and the lower surface of the substrate during the heating process, this invention uses a varying power compensation factor. Real-time power compensation is performed on the lower or upper heating element, specifically as follows: Preset power compensation temperature control cycle Every time a temperature control cycle Perform a power compensation; The power compensation is applied to: In top temperature control mode, based on the comparison between the actual temperature measured by the top high-temperature gauge at the current moment and the target temperature at the corresponding moment in the preset target temperature rise curve, the reference power value of the upper heating component and the basic power value of the lower heating component are obtained; using the power compensation factor corresponding to the current moment... The base power value of the lower heating element is compensated to obtain the actual power value of the lower heating element at the current moment. Alternatively, in bottom temperature control mode, based on the comparison between the actual temperature measured by the bottom high-temperature gauge at the current moment and the target temperature at the corresponding moment in the preset target temperature rise curve, the base power value of the lower heating component and the reference power value of the upper heating component are obtained; using the power compensation factor corresponding to the current moment... Power compensation is performed on the reference power value of the upper heating component to obtain the actual power value of the upper heating component at the current moment.

[0044] In the above real-time power compensation process, the power compensation factor The changes include: The stage of increasing temperature difference is divided into: The first type of continuous subintervals, the Power compensation factor corresponding to each type of continuous sub-interval Incrementing gradually from 0 to the preset maximum power compensation factor. ; The temperature difference reduction stage is divided into: The second type of continuous sub-intervals, the Power compensation factor corresponding to each second type of continuous sub-interval Decreasing, due to the maximum power compensation factor Gradually reduce to 0.

[0045] The power compensation factor The specific calculation formula is as follows: In the formula, This represents the number of intervals in the first type of continuous subintervals. This represents the number of intervals in the second type of continuous subintervals. The maximum power compensation factor; a first-type continuous subinterval and The second type of continuous sub-intervals are arranged sequentially to form One power compensation range, It is the interval counting index, that is The power compensation interval in the th A range.

[0046] Wherein, the maximum power compensation factor The calculation formula is: In the formula, The maximum temperature difference obtained in step S1; This is the proportional gain coefficient, and its value ranges from 0.5 to 0.8 °C. -1 The proportional gain coefficient The preferred value is 0.65.

[0047] Among them, the starting temperature, the target temperature, the predetermined heating rate, and the temperature control cycle are all based on the starting temperature, the target temperature, the predetermined heating rate, and the temperature control cycle. The sum of the number of first-type and second-type continuous subintervals is calculated using the following formula: In the formula, It is the sum of the number of the first type of continuous sub-intervals and the second type of continuous sub-intervals, which is the total number of power compensation intervals; The starting temperature, For the target temperature, This is the predetermined heating rate.

[0048] Furthermore, the number of intervals of the first type of continuous sub-intervals is calculated based on the duration of the temperature difference increase phase and the temperature control cycle. The calculation formula is as follows: In the formula, The duration of the temperature difference increase phase.

[0049] Alternatively, considering that during the real-time power compensation heating process, the actual temperature difference decreases relative to the theoretical temperature difference, causing a time shift in the temperature difference increase phase of the actual temperature difference curve relative to the theoretical temperature difference curve, the duration of the temperature difference increase phase can be corrected. In this case, the number of intervals in the first type of continuous sub-intervals... The calculation formula is as follows: In the formula, The correction factor, ranging from 0.2 to 0.5, is used to correct the time shift of the actual temperature difference curve relative to the theoretical temperature difference curve during the increasing temperature difference phase caused by power compensation. The calculation result of the above formula is rounded down, and the integer value is used as the... .

[0050] Furthermore, calculate the sum of the number of intervals for the first type of continuous subintervals and the second type of continuous subintervals. Number of intervals with the first type of continuous subintervals The difference between them yields the number of intervals in the second type of continuous subintervals. The calculation formula is as follows: .

[0051] Specifically, the actual heating time from the start of heating is obtained, and the interval count number is calculated based on the actual heating time and the temperature control cycle. The calculation formula is: In the formula, This refers to the actual heating time that has elapsed since the start of the heating process. For temperature control cycle; The interval counting sequence number for and If the ratio is not an integer, then the smallest integer greater than that ratio is taken as the integer value. .

[0052] Furthermore, in the top temperature control mode, after power compensation for the lower heating element, the formula for calculating the actual power value of the lower heating element is as follows: In the formula, This is the actual power value of the lower heating element. The base power value is assigned to the lower heating component based on the real-time temperature of the upper surface of the wafer.

[0053] In bottom temperature control mode, after power compensation of the upper heating element, the formula for calculating the actual power value of the upper heating element is as follows: In the formula, This is the actual power value of the upper heating element. The reference power value is assigned to the upper heating component based on the real-time temperature of the lower surface of the base.

[0054] In one specific embodiment, a top-temperature control mode is adopted, in which the wafer is heated from 600°C to the target temperature of 1150°C at a heating rate of 5°C / s, and the temperature control cycle is [not specified]. = 0.2 s, therefore the sum of the number of intervals in the first type of continuous sub-interval and the second type of continuous sub-interval is 550. Based on the temperature difference curve without power compensation, the maximum temperature difference and the duration of the temperature difference increase phase are obtained, and then the maximum power compensation factor is determined. =0.4, = 75, = 475.

[0055] Further calculation of the real-time changing power compensation factor The resulting curve is shown below. Figure 5A As shown.

[0056] Use power compensation factor Real-time power compensation was performed on the lower heating element, and the temperature rise curves of the upper surface of the wafer and the lower surface of the substrate after power compensation were obtained, as shown in the figure. Figure 5B As shown, the temperature difference curves of the two are as follows: Figure 5C As shown. In Figure 5C Initially, the temperature of the upper surface of the wafer is higher than that of the lower surface of the substrate; at this point, the wafer is in the pre-heating stage (Active Idle). Subsequently, it enters the heating up stage, where the maximum temperature difference remains around 2.5℃. Compared to the maximum temperature difference of 40℃ without power compensation, the temperature difference between the upper and lower surfaces of the wafer is significantly smaller, resulting in more uniform heating. This helps reduce defects such as wafer warpage and slip lines caused by uneven heating.

[0057] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0058] In the description of this invention, it should be understood that the terms "center," "height," "thickness," "upper," "lower," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0059] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0060] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0061] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A temperature difference control method based on power compensation, characterized in that, include: The first theoretical heating curve of the upper surface of the wafer and the second theoretical heating curve of the lower surface of the substrate are obtained in advance, corresponding to the heating from the starting temperature to the target temperature at a predetermined heating rate. A theoretical temperature difference curve is constructed based on the first and second theoretical temperature rise curves to determine the maximum temperature difference. ; with the maximum temperature difference Using the time point as the boundary, the heating process is divided into a stage of increasing temperature difference and a stage of decreasing temperature difference; The wafer is heated from the starting temperature to the target temperature at the predetermined heating rate, and a varying power compensation factor is used during the heating process. Real-time power compensation is performed on the lower heating assembly located below the base or the upper heating assembly located above the wafer; In the process of real-time power compensation, the power compensation factor The changes include: The stage of increasing temperature difference is divided into: The first type of continuous subintervals, the Power compensation factor corresponding to each type of continuous sub-interval Incrementing gradually from 0 to the preset maximum power compensation factor. ; The temperature difference reduction stage is divided into: The second type of continuous sub-intervals, the Power compensation factor corresponding to each second type of continuous sub-interval Decreasing, due to the maximum power compensation factor Gradually reduce to 0.

2. The temperature difference control method as described in claim 1, characterized in that, The maximum power compensation factor The calculation formula is: In the formula, This is the proportional gain coefficient, and its value ranges from 0.5 to 0.8 °C. -1 .

3. The temperature difference control method as described in claim 2, characterized in that, The proportional gain coefficient The value is 0.

65.

4. The temperature difference control method as described in claim 1, characterized in that, A preset temperature control cycle for power compensation is established, and power compensation is performed on the lower or upper heating component once every temperature control cycle. Based on the initial temperature, the target temperature, the predetermined heating rate, and the temperature control cycle, the sum of the number of first-type and second-type continuous sub-intervals is calculated using the following formula: In the formula, It is the sum of the number of intervals in the first type of continuous subintervals and the number of intervals in the second type of continuous subintervals. This represents the number of intervals in the first type of continuous subintervals. This represents the number of intervals in the second type of continuous subintervals. The starting temperature, For the target temperature, To achieve the predetermined heating rate, This is the temperature control cycle.

5. The temperature difference control method as described in claim 4, characterized in that, The duration of the temperature difference increase phase is obtained, and the number of intervals of the first type of continuous sub-intervals is calculated based on the duration of the temperature difference increase phase and the temperature control cycle. The calculation formula is as follows: in, The duration of the temperature difference increase phase; Calculate the sum of the number of consecutive subintervals of the first type and the number of consecutive subintervals of the second type. Number of intervals with the first type of continuous subintervals The difference between them yields the number of intervals in the second type of continuous subintervals. The calculation formula is as follows: 。 6. The temperature difference control method as described in claim 4, characterized in that, The duration of the temperature difference increase phase is obtained, and the number of intervals of the first type of continuous sub-intervals is calculated based on the duration of the temperature difference increase phase and the temperature control cycle. The calculation formula is as follows: In the formula, The correction factor, ranging from 0.2 to 0.5, is used to correct the time shift of the actual temperature difference curve relative to the theoretical temperature difference curve during the increasing temperature difference phase caused by power compensation. The calculation result of the above formula is rounded down, and the integer value is used as the... ; Calculate the sum of the number of consecutive subintervals of the first type and the number of consecutive subintervals of the second type. Number of intervals with the first type of continuous subintervals The difference between them yields the number of intervals in the second type of continuous subintervals. The calculation formula is as follows: 。 7. The temperature difference control method as described in claim 1, characterized in that, Power compensation factor The calculation formula is: Among them, a first-type continuous subinterval and The second type of continuous sub-intervals are arranged sequentially to form One power compensation range, It is the interval counting index, that is The power compensation interval in the th A range; This represents the number of intervals in the first type of continuous subintervals. This represents the number of intervals in the second type of continuous subintervals. This is the maximum power compensation factor.

8. The temperature difference control method as described in claim 7, characterized in that, A preset temperature control cycle for power compensation is established, and power compensation is performed on either the lower or upper heating component every one temperature control cycle. The actual heating time elapsed since the start of heating is obtained, and an interval count number is calculated based on the actual heating time and the temperature control cycle. The calculation formula is: in, This refers to the actual heating time that has elapsed since the start of the heating process. For temperature control cycle; The interval counting sequence number for and If the ratio is not an integer, then the smallest integer greater than that ratio is taken as the integer value. .

9. The temperature difference control method as described in claim 1, characterized in that, The theoretical temperature difference curve is calculated by subtracting the temperature value of the second theoretical temperature rise curve at the corresponding time from the temperature value of the first theoretical temperature rise curve at each time. On the theoretical temperature difference curve, the absolute value of its valley is determined as the maximum temperature difference. And record the maximum temperature difference. Current time; On the theoretical temperature difference curve, determine the temperature difference from the initial moment to the maximum temperature difference. The time interval at any given moment is used as the duration of the phase of increasing temperature difference. .

10. The temperature difference control method as described in claim 9, characterized in that, The temperature of the upper surface of the wafer was measured using a top pyrometer; The temperature of the lower surface of the base was measured using a bottom pyrometer.

11. The temperature difference control method as described in claim 10, characterized in that, In top temperature control mode, the base power value allocated to the lower heating component is adjusted based on the comparison between the actual temperature measured by the top high-temperature gauge at the current moment and the target temperature at the corresponding moment in the preset target temperature rise curve; and the power compensation factor corresponding to the current moment is used. Power compensation is performed on the base power value to obtain the actual power value of the lower heating component at the current moment; or, In bottom temperature control mode, the reference power value allocated to the upper heating component is adjusted based on the comparison between the actual temperature measured by the bottom high-temperature gauge at the current moment and the target temperature at the corresponding moment in the preset target temperature rise curve; and the power compensation factor corresponding to the current moment is used. Power compensation is performed on the reference power value to obtain the actual power value of the upper heating component at the current moment.

12. The temperature difference control method as described in claim 11, characterized in that, In top temperature control mode, after power compensation for the lower heating element, the formula for calculating the actual power value of the lower heating element is as follows: In the formula, This is the actual power value of the lower heating element. The base power value is assigned to the lower heating component based on the real-time temperature of the upper surface of the wafer.

13. The temperature difference control method as described in claim 11, characterized in that, In bottom temperature control mode, after power compensation of the upper heating element, the formula for calculating the actual power value of the upper heating element is as follows: In the formula, This is the actual power value of the upper heating element. The reference power value is assigned to the upper heating component based on the real-time temperature of the lower surface of the base.

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