Open-closed loop transition method and device for temperature control of wafer rapid heating process

Abstract

The invention discloses an open-loop and closed-loop transition method and device for temperature control of a wafer rapid heating process, and the method comprises the steps: carrying out the initial heating of a wafer in an open-loop mode, and achieving an initial temperature baseline; then a low-temperature closed-loop PID control method is implemented, the temperature rise speed of each temperature measurement point is calculated and compared with a preset target temperature rise speed, and a PID control strategy is designed based on the temperature rise speed difference so that the heating rate can be adjusted, and the temperature rise speed can smoothly reach the target value; designing a PID reference curve to adjust the temperature of the outer ring of the wafer, and correcting the temperature of the outer ring of the wafer; and according to different wafer characteristics and ambient pressure changes, PID reference curves of open-loop and closed-loop transition stages are automatically adjusted. According to the method, the problem that the radiance of the wafer is reduced in the open-loop and closed-loop transition stage in the rapid wafer heating process is solved, the temperature value is corrected, the curve is designed to be smooth, the radiance of the wafer is more stable than that of an original process, and the method has certain universality.

Description

Technical Field

[0001] The present invention relates to the field of rapid wafer heating, and in particular to an open-closed loop transition method and device for temperature control in a rapid wafer heating process. Background Art

[0002] Wafer Rapid Thermal Processing (RTP) is a key device used to rapidly heat wafers in semiconductor manufacturing. Its purpose is to heat wafers to the required high temperature in a short time to meet various process requirements, such as doping, oxidation, and chemical vapor deposition. Compared with traditional furnace heating systems, rapid heating systems can provide higher heating rates and more precise temperature control. It mainly achieves rapid heating through radiation heating or contact heating, and is equipped with temperature sensors and closed-loop control systems to ensure the uniformity and stability of the heating process. The system also includes cooling mechanisms and atmosphere control to ensure that the target temperature is maintained under different environmental conditions. The efficiency and accuracy of the wafer rapid heating system are crucial to the manufacturing quality of semiconductor devices and are indispensable equipment in modern semiconductor production.

[0003] In the wafer rapid heating system, the transition from open-loop control in the low-temperature stage to closed-loop control in the high-temperature stage faces multiple challenges. The main difficulties include: the low-temperature stage under open-loop control may lead to measurement errors and temperature unevenness, while the closed-loop control in the high-temperature stage requires precise real-time feedback and adjustment to maintain a stable temperature. During the transition process, the accuracy of temperature measurement, the smooth transition of the control algorithm, thermal response and dynamic adjustment, and the requirements for temperature uniformity may cause problems. In addition, the system's response speed and thermal stress also require special attention to avoid damage to the wafer material. Effectively addressing these challenges requires the comprehensive application of advanced control technology, precise measurement equipment, and optimized heating strategies. Summary of the invention

[0004] The present invention aims to address the deficiencies of the prior art and to provide an open-closed loop transition method and device for temperature control in a wafer rapid heating process.

[0005] The object of the present invention is achieved through the following technical solution: an open-closed loop transition method for temperature control of a wafer rapid heating process, the method comprising the following steps:

[0006] Step 1: Preliminary heating: Preliminary heating of the wafer in open-loop mode to reach the required initial temperature baseline;

[0007] Step 2: Closed-loop PID control: Implement closed-loop PID control method;

[0008] Step 3: Calculation and adjustment of heating rate: Calculate the heating rate of each temperature measurement point and compare it with the preset target heating rate. Design a PID control strategy based on the heating rate difference to adjust the heating rate so that the heating rate reaches the target value smoothly.

[0009] Step 4: Temperature display correction: Design a PID reference curve to adjust the temperature of the outer ring of the wafer and correct the temperature of the outer ring of the wafer;

[0010] Step 5: Automatically adjust the PID curve: Automatically adjust the PID reference curve of the open-loop and closed-loop transition stages according to different wafer characteristics and changes in ambient pressure.

[0011] Further, in step 1, the wafer is preliminarily heated in an open-loop mode until the temperature indicated by the radiation pyrometer reaches 350°C.

[0012] Furthermore, in step 2, each collected temperature data sample is subjected to median filtering and low-pass filtering to eliminate high-frequency noise and smooth the data stream, thereby obtaining a more accurate and stable temperature reading.

[0013] Furthermore, in step 3, the temperature change is monitored in real time during the control process, and the PID parameters are dynamically adjusted according to the feedback information to adapt to different heat conduction characteristics and radiation characteristics.

[0014] Furthermore, in step 4, different PID control curves are designed considering the gradient difference of the temperature of the outer ring and the inner ring to ensure the temperature uniformity of the entire wafer surface and reduce the thermal stress and potential wafer defects caused by uneven temperature.

[0015] Furthermore, in step 5, the automatic adjustment process is as follows:

[0016] T adjust (t) = T base +f(T actual -T target ,P env )

[0017] According to the actual temperature T actual and target temperature T target The difference between the ambient pressure P env , T base is the initial limit temperature, adjust the temperature T adjust (t) is used as the input to the PID to ensure that the wafer is uniformly heated to approximately 600°C.

[0018] Furthermore, during the heating process, high-precision radiometers and spectrometers are used to monitor the emissivity changes of the wafer in real time to further optimize the heating process and ensure the accuracy of temperature measurement and the efficiency of the heating process.

[0019] In a second aspect, the present invention also provides an open-closed-loop transition device for temperature control of a rapid wafer heating process, comprising a memory and one or more processors, wherein the memory stores executable code, and when the processor executes the executable code, it implements the open-closed-loop transition method for temperature control of a rapid wafer heating process.

[0020] In a third aspect, the present invention further provides a computer-readable storage medium having a program stored thereon, and when the program is executed by a processor, the open-closed loop transition method for temperature control of a wafer rapid heating process is implemented.

[0021] In a fourth aspect, the present invention further provides a computer program product, including a computer program, which, when executed by a processor, implements the open-closed loop transition method for temperature control of a rapid wafer heating process.

[0022] The beneficial effects of the invention: The invention solves the problem of decreased emissivity of most wafers in the open-loop and closed-loop transition stage in the wafer rapid heating process. Based on a large amount of experimental data, the temperature values ​​that need to be corrected for different wafers at different gas pressures in this stage are fitted, and the reference curve is smoothed, so that the emissivity of the wafer in this stage is more stable than the original process and has a certain degree of versatility. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 A flow chart of an open-closed loop transition method for temperature control of a wafer rapid heating process provided by the present invention;

[0025] Figure 2 The effect diagram of the open-closed loop transition method provided by the present invention;

[0026] Figure 3 A structural diagram of an open-closed loop transition device for temperature control in a wafer rapid heating process provided by the present invention. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with the accompanying drawings and implementation examples. It should be understood that the specific implementation examples described herein are only used to explain the present invention and are not used to limit the present invention.

[0028] like Figure 1 and Figure 2 As shown, the present invention provides an open-closed loop transition method for temperature control of a wafer rapid heating process, comprising the following steps:

[0029] Step 1: Preliminary heating: The wafer is preliminarily heated in open-loop mode until the radiation pyrometer shows a temperature of 350°C, providing a stable initial temperature baseline for subsequent closed-loop control.

[0030] Step 2: Low temperature closed-loop PID control: Implement the low temperature closed-loop PID control method, which includes: median filtering and low-pass filtering of the 7-channel temperature data of the wafer, which is performed every 10 milliseconds to eliminate high-frequency noise and smooth the data stream to obtain more accurate and stable temperature readings. This processing step is critical to the subsequent PID control and ensures the effectiveness of the control strategy.

[0031] Step 3: Calculate and adjust the heating rate: Calculate the heating rate V of each temperature measurement point i The preset target heating rate V t By comparison, the difference ΔV is obtained. The PID control strategy for design includes: adjusting the heating rate through the following formula so that the heating rate reaches the target value smoothly and maintains the wafer emissivity stable.

[0032]

[0033] The heating rate is calculated according to the material characteristics of the wafer and the PID control parameters in the steps are adjusted. The temperature changes are monitored in real time during the control process, and the PID parameters are dynamically adjusted according to the feedback information, so that the control system can adapt to different heat conduction characteristics and radiation characteristics to achieve the best heating effect.

[0034] The smoothing calculation process of the PID reference curve is as follows:

[0035] if(systemvalue[0x0051+i]==6000)

[0036] {

[0037] if(PIDtemperatureset[i]<=5000&&PIDtemperatureset[i]>=4000)

[0038] {

[0039] Tsetrate_up=Tsetrate_up+(trans_start_rate / 10)*(trans_start_rate / 10) / (2*(500-400))*0.1;

[0040] }

[0041] else if(PIDtemperatureset[i]>=5000&&PIDtemperatureset[i]<=6000)

[0042] {

[0043] Tsetrate_up=Tsetrate_up-(trans_start_rate / 10)*(trans_start_rate / 10) / (2*(600-500))*0.1;

[0044] }

[0045] Tsetrate_up=tmp rate / 10-0.3;

[0046] if(Tsetrate_up<2&&Tsetrate_up>-2)

[0047] Tsetrate_up = 1;

[0048] }

[0049] else

[0050] {

[0051] Tsetrate_up = Tsetrate;

[0052] }

[0053] Step 4: Temperature display correction: Since the radiation pyrometer may display inaccurately in the low temperature stage, the outer ring temperature of the wafer is corrected in particular, and a specific PID reference curve is designed to adjust the outer ring temperature to ensure the accuracy of the overall temperature. Considering the gradient difference between the outer and inner ring temperatures, different PID control curves are designed to ensure the temperature uniformity of the entire wafer surface. Through special treatment of the outer ring temperature, thermal stress and potential wafer defects caused by uneven temperature can be effectively reduced.

[0054] Step 5: Automatically adjust the PID curve: According to different wafer characteristics and ambient pressure changes, automatically adjust the PID reference curve of the open-loop and closed-loop transition stages. The adjustment process is based on the following formula:

[0055] T adjust (t) = T base +f(T actual -T target ,P env )

[0056] According to the actual temperature T actual and target temperature T target The difference between the ambient pressure P env , T base is the initial limit temperature, adjust the temperature T adjust (t) is used as the input to the PID to ensure that the wafer is uniformly heated to approximately 600°C.

[0057] The system integrates environmental monitoring sensors to collect environmental parameters such as air pressure and humidity in real time, and inputs these data into the control system to adjust the heating strategy. This multi-parameter linkage control method improves the adaptability and response speed of the system and ensures the consistency of heating effects under various environmental conditions.

[0058] High-precision radiometers and spectral analysis instruments are used to monitor the emissivity changes of the wafer in real time, and these data are incorporated into the control system to further optimize the heating process. The accuracy of temperature measurement and the efficiency of the heating process are ensured by real-time adjustment of the emissivity.

[0059] Corresponding to the aforementioned embodiment of an open-closed loop transition method for temperature control in a rapid wafer heating process, the present invention also provides an embodiment of an open-closed loop transition device for temperature control in a rapid wafer heating process.

[0060] See also Figure 3 An open-closed-loop transition device for temperature control of a wafer rapid heating process provided in an embodiment of the present invention includes a memory and one or more processors, wherein the memory stores executable code, and when the processor executes the executable code, it is used to implement an open-closed-loop transition method for temperature control of a wafer rapid heating process in the above embodiment.

[0061] An embodiment of an open-closed loop transition device for temperature control of a wafer rapid heating process provided by the present invention can be applied to any device with data processing capabilities, and the device with data processing capabilities can be a device or apparatus such as a computer. The device embodiment can be implemented through software, or through hardware or a combination of software and hardware. Taking software implementation as an example, as a device in a logical sense, it is formed by the processor of any device with data processing capabilities in which it is located reading the corresponding computer program instructions in the non-volatile memory into the internal memory for execution. From a hardware perspective, if Figure 3 As shown, it is a hardware structure diagram of an open-closed loop transition device for temperature control of a wafer rapid heating process provided by the present invention, in which any device with data processing capability is located, except Figure 3In addition to the processor, memory, network interface, and non-volatile memory shown, any device with data processing capabilities in which the apparatus in the embodiments is located may also include other hardware, generally based on the actual functions of the device with data processing capabilities, which will not be described in detail.

[0062] The implementation process of the functions and effects of each unit in the above-mentioned device is specifically described in the implementation process of the corresponding steps in the above-mentioned method, and will not be repeated here.

[0063] For the device embodiment, since it basically corresponds to the method embodiment, the relevant parts can refer to the partial description of the method embodiment. The device embodiment described above is only schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of the present invention. Ordinary technicians in this field can understand and implement it without paying creative work.

[0064] An embodiment of the present invention further provides a computer-readable storage medium having a program stored thereon. When the program is executed by a processor, an open-closed loop transition method for temperature control of a wafer rapid heating process in the above embodiment is implemented.

[0065] The computer-readable storage medium may be an internal storage unit of any device with data processing capability described in any of the aforementioned embodiments, such as a hard disk or a memory. The computer-readable storage medium may also be an external storage device of any device with data processing capability, such as a plug-in hard disk, a smart media card (SMC), an SD card, a flash card, etc. equipped on the device. Furthermore, the computer-readable storage medium may also include both an internal storage unit and an external storage device of any device with data processing capability. The computer-readable storage medium is used to store the computer program and other programs and data required by any device with data processing capability, and may also be used to temporarily store data that has been output or is to be output.

[0066] The present invention also provides a computer program product, including a computer program, which, when executed by a processor, implements the open-closed loop transition method for temperature control of a wafer rapid heating process.

[0067] The above embodiments are used to illustrate the present invention rather than to limit the present invention. Any modification and change made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

Claims

1. An open-closed loop transition method for temperature control of a wafer rapid heating process, characterized in that: The method comprises the following steps: Step 1: Preliminary heating: Preliminary heating of the wafer in open-loop mode to reach the required initial temperature baseline; Step 2: Closed-loop PID control: Implement closed-loop PID control method; Step 3: Calculation and adjustment of heating rate: Calculate the heating rate of each temperature measurement point and compare it with the preset target heating rate. Design a PID control strategy based on the heating rate difference to adjust the heating rate so that the heating rate reaches the target value smoothly. Step 4: Temperature display correction: Design a PID reference curve to adjust the temperature of the outer ring of the wafer and correct the temperature of the outer ring of the wafer; Step 5: Automatically adjust the PID curve: Automatically adjust the PID reference curve of the open-loop and closed-loop transition stages according to different wafer characteristics and changes in ambient pressure.

2. The open-closed loop transition method for temperature control of a wafer rapid heating process according to claim 1, characterized in that: In step 1, the wafer is initially heated in open-loop mode until the temperature reaches 350°C as indicated by the radiation pyrometer.

3. The open-closed loop transition method for temperature control of a wafer rapid heating process according to claim 1, characterized in that: In step 2, each collected temperature data sample is subjected to median filtering and low-pass filtering to remove high-frequency noise and smooth the data stream, thereby obtaining a more accurate and stable temperature reading.

4. The open-closed loop transition method for temperature control of a wafer rapid heating process according to claim 1, characterized in that: In step 3, the temperature change is monitored in real time during the control process, and the PID parameters are dynamically adjusted according to the feedback information to adapt to different heat conduction characteristics and radiation characteristics.

5. The open-closed loop transition method for temperature control of a wafer rapid heating process according to claim 1, characterized in that: In step 4, different PID control curves are designed considering the gradient difference of the temperature of the outer ring and the inner ring to ensure the temperature uniformity of the entire wafer surface and reduce the thermal stress and potential wafer defects caused by uneven temperature.

6. The open-closed loop transition method for temperature control of a wafer rapid heating process according to claim 1, characterized in that: In step 5, the automatic adjustment process is as follows: T adjust (t)=T base +f(T actual -T target ,P env ) According to the actual temperature T actual and target temperature T target The difference between the ambient pressure P env , T base is the initial limit temperature, adjust the temperature T adjust (t) is used as the input to the PID to ensure that the wafer is uniformly heated to approximately 600°C.

7. The open-closed loop transition method for temperature control of a wafer rapid heating process according to claim 1, characterized in that: During the heating process, high-precision radiometers and spectrometers are used to monitor the emissivity changes of the wafer in real time to further optimize the heating process and ensure the accuracy of temperature measurement and the efficiency of the heating process.

8. An open-closed loop transition device for temperature control of a wafer rapid heating process, comprising a memory and one or more processors, wherein the memory stores executable code, characterized in that: When the processor executes the executable code, an open-closed loop transition method for temperature control of a wafer rapid heating process as described in any one of claims 1 to 7 is implemented.

9. A computer-readable storage medium having a program stored thereon, characterized in that: When the program is executed by a processor, an open-closed loop transition method for temperature control of a wafer rapid heating process as described in any one of claims 1 to 7 is implemented.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, an open-closed loop transition method for temperature control in a wafer rapid heating process as described in any one of claims 1 to 7 is implemented.

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