A novel etching electrostatic chuck, temperature adaptive control device and method

Abstract

The present invention relates to the field of semiconductor technology and addresses the technical issues that conventional electrostatic chucks are unsuitable for use in complex etching process environments and have difficulty accurately controlling the temperature at various locations on the surface of the electrostatic chuck. The invention particularly relates to a novel etching electrostatic chuck, a temperature adaptive control device, and a method thereof, comprising dividing regions, acquiring real-time temperature data, establishing an initial mathematical model, optimizing the initial mathematical model, calculating a target flow rate and cycle time, and providing feedback to a cooling system to achieve adaptive control. The present invention can more accurately control the flow rate of the cooling medium in complex etching process environments, achieving efficient, stable, and adaptive control of the electrostatic chuck temperature, improving the quality and reliability of semiconductor etching processes, and reducing wafer defects caused by temperature fluctuations, thereby providing an advanced temperature control technology solution for the semiconductor manufacturing industry.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a novel etching electrostatic chuck, a temperature adaptive control device and a method. Background Art

[0002] The paper "Research on Wafer Surface Temperature Control in Dry Etching" states that wafer temperature directly affects the etch rate, etch uniformity, and etch morphology during dry etching, thereby affecting the final device performance. Experiments confirmed that the clamping voltage and helium pressure of the electrostatic chuck, the RF source power, the lower electrode temperature, and the wafer itself all have a certain impact on the wafer temperature during the etching process. The clamping voltage and helium pressure of the electrostatic chuck have the greatest impact on the wafer temperature, followed by wafer warpage and lower RF source power. The upper RF source power and lower electrode cooling temperature have roughly the same impact on the wafer temperature, with the least impact.

[0003] The paper "Simulation Study on Temperature Control Methods for Electrostatic Chucks in Plasma Etchers" reveals that plasma etching is a key process in modern integrated circuit manufacturing. As integrated circuit feature sizes transition from 45 to 22 nm and wafer diameters for chip manufacturing shift from 300 mm to 450 mm, the industry's requirements for plasma etching processes are becoming increasingly stringent. Wafer etch rate and uniformity are key indicators for evaluating etch quality, and wafer temperature uniformity is a key factor influencing both of these indicators. Wafer temperature distribution is primarily influenced by the spatial distribution of plasma energy and the electrostatic chuck that secures and contacts the wafer. Due to the non-uniformity of plasma within the chamber, achieving a uniform spatial distribution of ion energy is difficult, making the electrostatic chuck crucial for controlling wafer temperature.

[0004] Currently, the main method for controlling wafer temperature using an electrostatic chuck is the structural control method. This method involves designing a series of surface topography structures, such as grooves and bosses, on the surface of the electrostatic chuck. A cooling gas, such as helium, is then passed through the gaps between these structures. The wafer temperature is then controlled by adjusting the topography parameters and gas pressure. While the structural control method can improve wafer temperature uniformity to a certain extent, since the structural parameters of the electrostatic chuck cannot be changed during etching and the cooling gas pressure cannot be precisely controlled across the chuck surface, the structural control method can only address situations with a specific spatial distribution of plasma energy. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention provides a new etching electrostatic chuck, temperature adaptive control device and method, which solves the technical problems that traditional electrostatic chucks cannot be applied to complex etching process environments and it is difficult to accurately control the temperature of various locations on the surface of the electrostatic chuck.

[0006] To solve the above technical problems, the present invention provides the following technical solution: a temperature adaptive control method, the method comprising the following steps:

[0007] S1. Divide the base of the electrostatic chuck into at least three regions starting from the central axis and extending toward its outer edge, forming an inner region, a middle region, and an outer region of equal area, and deploy independent temperature sensors and cooling pipes in each of the inner region, the middle region, and the outer region;

[0008] S2. Acquire real-time temperature data of the inner, middle, and outer regions, and perform preprocessing to obtain noise-free temperature data;

[0009] S3. Establishing an initial mathematical model to reflect the approximate relationship between the cooling medium flow rate v and the temperature difference ΔT during the semiconductor etching process;

[0010] S4. Based on the assumption that the heat released by the liquid QΔt per unit time Δt is equal to the heat removed by convection ΔQ, the initial mathematical model is optimized to reflect the precise relationship between the cooling medium flow rate v and the temperature difference ΔT during the semiconductor etching process;

[0011] S5. Under the precise relationship, calculate the target flow rate v' and circulation time t for the cooling medium to circulate in the cooling pipe based on the real-time acquired temperature data so that the temperature difference ΔT between the inner layer, the middle layer, and the outer layer approaches;

[0012] S6. Feedback the target flow rate v' and cycle time t to the cooling system for adjusting the output power to achieve adaptive control.

[0013] Furthermore, the temperature data includes the temperature difference ΔT between the inner zone, the middle zone and the outer zone, the cooling medium flow rate v and the cooling medium temperature T c .

[0014] Furthermore, the expression of the initial mathematical model is:

[0015] v=v0e kΔT

[0016] Where v0 is the initial flow velocity when ΔT=0; k is a constant greater than 0.

[0017] Furthermore, in step S4, the specific process includes the following steps:

[0018] S41. Establish an initial equation where the heat released by the liquid per unit time Δt, QΔt, is equal to the heat removed by convection heat transfer, ΔQ, namely:

[0019] QΔt=ΔQ

[0020] Q=hAΔT

[0021] Where h is the heat transfer coefficient; A is the heat exchange area between the cooling pipe and the base;

[0022] S42. Calculate the heat ΔQ removed by the cooling medium through convection heat transfer within unit time Δt. The calculation formula is:

[0023]

[0024] Where c p is the specific heat capacity of the cooling medium; m is the mass of the cooling medium; t is the circulation time of the cooling medium;

[0025] S43. Substitute the heat ΔQ into the initial equation to obtain the exact equation, namely:

[0026]

[0027] S44. Determine the exact relationship between the cooling medium flow rate v and the temperature difference ΔT during semiconductor etching under laminar flow conditions according to an accurate equation;

[0028] S45. Determine the precise relationship between the cooling medium flow rate v and the temperature difference ΔT during semiconductor etching under turbulent conditions based on a precise equation.

[0029] The technical solution also provides a device applied to the above-mentioned temperature adaptive control method, including:

[0030] A temperature detection module, which is composed of multiple temperature sensors distributed at different locations on the electrostatic chuck, and is used to measure the temperatures of the inner, middle, and outer regions in real time and convert temperature changes into electrical signals;

[0031] a data processing and control module, which receives temperature data from the temperature detection module and has a built-in microprocessor or digital signal processor for performing real-time calculations on the temperature data to determine the deviation between the current temperature of the electrostatic chuck and the target temperature, as well as the temperature change trend;

[0032] The cooling system is used to supply cooling medium to the inner layer area, the middle layer area and the outer layer area respectively, and adjust the output power according to the control signal of the data processing and control module to change the flow rate of the cooling medium.

[0033] Furthermore, the cooling system further comprises a pipeline network, and the pipeline network and the cooling pipelines in the inner layer area, the middle layer area and the outer layer area form independent internal and external circulations.

[0034] The technical solution also provides a new type of etching electrostatic chuck applied to the above-mentioned adaptive control method, including a base as the main structure of the electrostatic chuck, and a heating layer and a cooling layer respectively arranged on the upper and lower sides of the base. The bottom of the base is divided into at least three areas from the central axis as the starting point to its outer edge and other areas, forming an inner layer area, a middle layer area and an outer layer area of ​​equal area. Cooling pipes with independent liquid inlets and outlets are provided in the inner layer area, the middle layer area and the outer layer area, and a plurality of temperature sensors for real-time measurement of the temperature of the inner layer area, the middle layer area and the outer layer area are distributed in the heating layer.

[0035] Furthermore, the cooling pipe is located in the cooling layer, and the cooling pipe is a groove, boss or pipe structure arranged in the cooling layer, for the coolant to flow through the inner layer area, middle layer area or outer layer area through the cooling pipe in the corresponding area.

[0036] Furthermore, the plurality of temperature sensors are respectively arranged corresponding to the inner layer area, the middle layer area and the outer layer area.

[0037] Furthermore, the inner layer area, the middle layer area and the outer layer area are in the shape of a ring or a rectangle.

[0038] By means of the above technical solution, the present invention provides a novel etching electrostatic chuck, temperature adaptive control device and method, which have at least the following beneficial effects:

[0039] 1. The present invention can more accurately control the flow rate of the cooling medium in a complex etching process environment, achieve efficient, stable and adaptive control of the electrostatic chuck temperature, improve the quality and reliability of the semiconductor etching process, reduce wafer defects caused by temperature fluctuations, and provide an advanced temperature control technology solution for the semiconductor manufacturing industry.

[0040] 2. The temperature adaptive control device proposed in the present invention can cooperate with the electrostatic chuck to achieve better and faster approach to the temperature difference between the inner layer, middle layer and outer layer, thereby accurately controlling the temperature of various parts of the surface of the electrostatic chuck, thereby better stabilizing the temperature during wafer etching.

[0041] 3. The electrostatic chuck proposed in the present invention can change the temperature distribution of the electrostatic chuck from the traditional approximate distribution to a uniform distribution from high to low during wafer etching. It cooperates with three independent cooling pipes to act on three areas of the electrostatic chuck respectively, thereby better stabilizing the temperature during wafer etching, ensuring the uniformity of the wafer and the consistency of the process, and at the same time greatly improving the situation where the wafer is slightly warped on all sides. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0043] Figure 1 is a cross-sectional view of a conventional electrostatic chuck in the present invention;

[0044] Figure 2 Schematic diagram of temperature distribution on the wafer surface when a conventional electrostatic chuck is used in the present invention;

[0045] Figure 3 Schematic diagram of dividing the electrostatic chuck into regions in the first embodiment of the present invention;

[0046] Figure 4 is a cross-sectional view of an electrostatic chuck in Example 1 of the present invention;

[0047] Figure 5 Schematic diagram of the distribution of cooling pipes in Example 1 of the present invention;

[0048] Figure 6 Schematic diagram of temperature distribution on the wafer surface in Example 1 of the present invention;

[0049] Figure 7 This is an approximate relationship diagram between the cooling medium flow rate and the temperature difference in Example 3 of the present invention;

[0050] Figure 8 Graph showing the relationship between the target flow rate of the cooling medium and the cycle time in Example 3 of the present invention;

[0051] Figure 9 This is a graph showing the relationship between temperature difference and cycle time in Example 3 of the present invention;

[0052] Figure 10 This is a principle block diagram of the temperature adaptive control method improved in the present invention.

[0053] In the figure: 1. Base; 2. Cooling layer; 3. Cooling pipe; 4. Heating layer; 5. Temperature sensor. DETAILED DESCRIPTION

[0054] To make the above-mentioned objectives, features, and advantages of the present invention more clearly understood, the present invention is further described below in detail with reference to the accompanying drawings and specific embodiments. This will enable a full understanding of how this application uses technical means to solve technical problems and achieve technical effects, and to implement the invention accordingly.

[0055] Example 1

[0056] like Figure 1The figure shows a cross-sectional view of the electrostatic chuck structure currently used. The main method of controlling the wafer temperature using an electrostatic chuck is the structural control method. This method designs a series of surface topography structures (such as grooves and bosses) on the surface of the electrostatic chuck, then passes a cooling gas (such as helium) through the gaps in the structure, and then controls the wafer temperature by adjusting the topography parameters and gas pressure. Figure 2 As shown, this is a schematic diagram of the temperature distribution on the wafer surface during the process.

[0057] Please refer to Figure 3-Figure 6 This embodiment proposes a novel etching electrostatic chuck, comprising a base 1 as the main structure of the electrostatic chuck, and a heating layer 4 and a cooling layer 2 respectively arranged on the upper and lower sides of the base 1. The bottom of the base 1 is divided into at least three areas from the central axis to its outer edge, forming an inner layer area, a middle layer area and an outer layer area of ​​equal area, such as Figure 3 As shown. The inner layer, middle layer and outer layer are each provided with a cooling pipe 3 having an independent liquid inlet and outlet. A plurality of temperature sensors 5 for real-time measurement of the temperature of the inner layer, middle layer and outer layer are distributed in the heating layer 4. Figure 4 shown.

[0058] Cooling pipes 3 are located in cooling layer 2. These pipes are channels, bosses, or pipe structures within cooling layer 2, allowing coolant to flow through the inner, middle, or outer regions. Multiple temperature sensors 5 are positioned corresponding to the inner, middle, and outer regions. The inner, middle, and outer regions are circular or rectangular in shape.

[0059] like Figure 5 As shown, independent cooling pipes 3 are laid in the inner, middle, and outer zones, each with its own liquid inlet and outlet. In this embodiment, for example, a base 1 with a diameter of 200 mm is evenly divided into three zones. The inner, middle, and outer zones each occupy one-third of the total bottom area. The cooling pipes 3 are embedded in the base 1's bottom. The surrounding arrangement density of individual cooling pipes 3 must occupy 80%-90% of the corresponding zone area.

[0060] like Figure 6 As shown, in this embodiment, the temperature distribution diagram on the wafer surface is approximately equivalent to the temperature being evenly distributed from high to low. Therefore, the electrostatic chuck structure (ESC) is divided into three areas, and the divided areas are marked with serial numbers. Then, temperature sensors with corresponding labels are placed in each area to reflect the temperature difference between the three areas.

[0061] The electrostatic chuck proposed in this embodiment can change the temperature distribution of the electrostatic chuck from the traditional approximate distribution to a uniform distribution from high to low during wafer etching. In conjunction with three independent cooling pipes that act on three areas of the electrostatic chuck respectively, the temperature during wafer etching can be better stabilized, ensuring the uniformity of the wafer and the consistency of the process. At the same time, it can greatly improve the situation where the wafer is slightly warped on all sides.

[0062] Example 2

[0063] This embodiment, based on the novel electrostatic chuck for etching proposed in Example 1, proposes a temperature adaptive control system for the novel electrostatic chuck. This system aims to achieve a better and faster convergence of the temperature differences between the inner, middle, and outer regions of the electrostatic chuck, thereby precisely controlling the temperature at all locations on the electrostatic chuck surface and thereby further stabilizing the temperature during wafer etching. The system consists of a temperature detection module, a data processing and control module, and a cooling system.

[0064] The temperature detection module is composed of multiple temperature sensors, which are distributed at different locations of the electrostatic chuck to measure the temperature of the inner, middle, and outer areas in real time and convert the temperature changes into electrical signals. Among them, the temperature sensor proposed in this embodiment can adopt the ZTM11F patch platinum resistance temperature sensor sold by Hunan Zetian Sensing Technology Co., Ltd. These temperature sensors are distributed at different locations of the electrostatic chuck and can measure the temperature of the inner, middle, and outer areas in real time and accurately. At the same time, these temperature sensors have high sensitivity and fast response characteristics, and can quickly convert temperature changes into electrical signals for subsequent processing.

[0065] The data processing and control module receives temperature data from the temperature detection module. It incorporates a built-in microprocessor or digital signal processor (DSP), which performs real-time calculations on the temperature data to determine the deviation between the electrostatic chuck's current temperature and the target temperature, as well as the temperature trend. Specifically, the module receives and analyzes the temperature data from the temperature detection module. This module incorporates an advanced microprocessor or digital signal processor, such as the i.MX 6ULL ​​single-core processor sold by NXP Semiconductors, offering powerful data processing capabilities. Based on a pre-set algorithm, it performs real-time calculations on the temperature data, determining key information such as the deviation between the current temperature and the target temperature and the temperature trend.

[0066] Based on the calculation results, a control signal is generated to control the power of the cooling system pump, thereby adjusting the flow rate of the cooling medium (such as coolant) to achieve precise control of the current temperature of the electrostatic chuck. The module also has a data storage function, which can store historical temperature data, control parameters, and related process information to facilitate subsequent process analysis and optimization.

[0067] The cooling system is used to supply cooling medium to the inner, middle, and outer zones respectively, and adjust the output power according to the control signal of the data processing and control module, so as to change the flow rate of the cooling medium. The cooling system also includes a pipeline network, which forms independent internal and external circulations with the cooling pipes in the inner, middle, and outer zones. The cooling system includes multiple high-precision chillers, each of which is responsible for providing cooling medium to a specific area of ​​the electrostatic chuck. The chiller has stable performance and can accurately adjust the output power according to the control signal, thereby changing the flow rate of the cooling medium. In addition, the pipeline network is rationally designed to ensure that the cooling medium is evenly distributed to all areas of the electrostatic chuck, thereby improving the uniformity of temperature control.

[0068] Example 3

[0069] In a specific etching process, due to the different density distribution of plasma in the chamber, the temperature distribution of the wafer surface is also uneven during bombardment. In addition, the degree of contact between the back of the wafer and the base is different, and the temperature distribution of the cooling water taken away from the wafer is also uneven, which leads to wafer warping. This embodiment, in combination with Examples 1 and 2, proposes a temperature adaptive control method that can more accurately control the flow rate of the cooling medium in a complex etching process environment, achieve efficient and stable adaptive control of the electrostatic chuck temperature, improve the quality and reliability of the semiconductor etching process, reduce wafer defects caused by temperature fluctuations, and provide an advanced temperature control technology solution for the semiconductor manufacturing industry. The method includes the following steps:

[0070] S1. Divide the base of the electrostatic chuck into at least three areas starting from the central axis and extending toward its outer edge, forming an inner layer area, a middle layer area, and an outer layer area of ​​equal area, and respectively arrange independent temperature sensors and cooling pipes in the inner layer area, the middle layer area, and the outer layer area.

[0071] S2. Obtain real-time temperature data of the inner, middle, and outer zones, and pre-process to obtain noise-free temperature data, including the temperature difference ΔT, cooling medium flow rate v, and cooling medium temperature T between the inner, middle, and outer zones. c .

[0072] S3. Establish an initial mathematical model to reflect the approximate relationship between the cooling medium flow rate v and the temperature difference ΔT during the semiconductor etching process. This embodiment is based on the principle of heat transfer and in-depth research on the characteristics of the cooling system. During the semiconductor etching process, the temperature difference between the electrostatic chuck and the wafer is the key factor driving heat transfer, and the flow rate of the cooling medium directly affects the efficiency of heat transfer. Based on the basic law of thermal convection, an initial mathematical model of flow rate and temperature difference is constructed. Therefore, the expression of the initial mathematical model expressing the approximate relationship is:

[0073] v=v0e kΔT

[0074] Where v0 is the initial flow velocity when ΔT = 0; k is a constant greater than 0 and is related to the physical properties of the cooling medium and the cooling pipe.

[0075] Specifically, the graphical relationship between the cooling medium flow rate v and the temperature difference ΔT is as follows: Figure 7 As shown in the figure, the temperature difference ΔT is the horizontal axis and the cooling medium flow rate v is the vertical axis. When ΔT = 0, v = v0. As ΔT increases, v increases exponentially.

[0076] However, the actual etching environment is extremely complex, and there are many factors that interfere with the accuracy of the initial mathematical model under the above ideal state. In order to more accurately reflect the actual situation, according to the law of conservation of energy, the heat released by the liquid per unit time Δt, QΔt, is equal to the heat removed by convection heat transfer ΔQ. To more accurately calculate the exact relationship between the cooling medium flow rate v and the temperature difference ΔT, it is also necessary to consider the relationship between the heat removed and the flow rate, as well as the relationship between time and energy. In the actual etching process, the cooling medium can flow in laminar or turbulent conditions, so the relationship between the heat removed and the flow rate includes two situations, namely: laminar state and turbulent state.

[0077] In laminar flow: According to Newton's cooling law Q = hAΔT, assuming laminar flow, the heat transfer coefficient h = av + b, a and b are constants, v = v0e kΔT Substituting into h = av0e kΔT +b, so Q=(av0e kΔT +b)AΔT.

[0078] In turbulent state: According to the principle of Dittus-Boelter formula, assuming h = cv 0.8 +d, c, d are constants, v = v0e kΔT Substituting into h = c(v0e kΔT ) 0.8 +d, so Q=[c(v0e kΔT ) 0.8 +d]AΔT.

[0079] Graphical relationships such as Figure 7 As shown in the figure, the temperature difference ΔT is the horizontal axis and the cooling medium flow rate v is the vertical axis. When ΔT = 0, v = v0. As ΔT increases, v increases exponentially.

[0080] The relationship between time and energy:

[0081] Assume that the specific heat capacity of the cooling medium is c p , the mass is m, according to the heat calculation formula Q = c p mΔT. The heat taken away in unit time Δt is ΔQ, so

[0082] Integrating the cycle time t yields Where T0 is the initial temperature difference, and T is the temperature difference after the cycle time t. This integral can be used to describe the relationship between the total heat removed over a period of time and the change in temperature difference. As time increases, the heat removed increases and the temperature difference gradually decreases.

[0083] In this embodiment, the three independent cooling pipes provided in the electrostatic chuck are as follows:

[0084] Assume that the initial temperature difference of the three cooling pipes is: ΔT 10 , ΔT 20 , ΔT 30 , and ΔT 10 >ΔT 20 >ΔT 30 , the corresponding initial flow rate As time goes by, the temperature difference decreases because the cooling medium takes away the heat, and finally the same is set as ΔT f The temperature difference of the cooling pipe with a large initial temperature difference decreases quickly. The final temperature difference is ΔT f The target flow rate of the three cooling pipes is same.

[0085] S4. Based on the fact that the heat released by the liquid per unit time Δt is equal to the heat removed by convection heat transfer ΔQ, the initial mathematical model is optimized to reflect the precise relationship between the cooling medium flow rate v and the temperature difference ΔT during the semiconductor etching process. In step S4, the specific process includes the following steps:

[0086] S41. Establish an initial equation where the heat released by the liquid per unit time Δt, QΔt, is equal to the heat removed by convection heat transfer, ΔQ, namely:

[0087] QΔt=ΔQ

[0088] Q=hAΔT

[0089] Where h is the heat transfer coefficient, which reflects the relationship between the speed of convective heat transfer and the temperature difference ΔT; A is the heat exchange area between the cooling pipe and the base.

[0090] S42. Calculate the heat ΔQ removed by the cooling medium through convection heat transfer within unit time Δt. The calculation formula is:

[0091]

[0092] Where c p is the specific heat capacity of the cooling medium; m is the mass of the cooling medium; t is the circulation time of the cooling medium;

[0093] S43. Substitute the heat ΔQ into the initial equation to obtain the exact equation, namely:

[0094]

[0095] According to the law of conservation of energy, in unit time Δt, the heat released by the liquid is equal to the heat taken away by convection, that is, ΔQ=QΔt. Substituting Q=hAΔT into ΔQ=(hAΔT)Δt, so

[0096] S44. Determine the precise relationship between the cooling medium flow rate v and the temperature difference ΔT during semiconductor etching under laminar flow conditions based on a precise equation.

[0097] Specifically, the heat transfer coefficient h in laminar flow is h = av0e kΔT +b into the exact equation have to If y = ΔT, this is a The differential equation is solved by separation of variables, namely: Integrate both sides Solving this integral yields the temperature difference ΔT as a function of the cycle time t, and substituting it into v = v0e kΔT The precise relationship between the cooling medium flow rate v and the temperature difference ΔT is obtained.

[0098] In actual engineering applications, the above integral is solved using numerical methods (computer software such as Matlab, Mathematica, etc.) according to specific parameter values ​​and accuracy requirements.

[0099] S45. Determine the precise relationship between the cooling medium flow rate v and the temperature difference ΔT during semiconductor etching under turbulent conditions based on a precise equation.

[0100] Specifically, the heat transfer coefficient h = c(v0e kΔT ) 0.8+d into the exact equation have to This is also a differential equation. Usually it is necessary to use numerical methods to solve it, using computer software (such as Matlab, Mathematica, etc.) to perform numerical integration to obtain the numerical solution of the temperature difference ΔT with respect to the cycle time t, and then substitute it into v=v0e kΔT The precise relationship between the cooling medium flow rate v and the temperature difference ΔT is obtained.

[0101] S5. Based on the precise relationship, the target flow rate v' and cycle time t for the cooling medium to circulate in the cooling pipe to approximate the temperature difference ΔT between the inner, middle, and outer regions are calculated based on the real-time acquired temperature data. Using the established precise relationship, the target flow rate v' to approximate the temperature difference ΔT between the inner, middle, and outer regions can be calculated based on the real-time acquired temperature data, regardless of whether the flow is in a laminar or turbulent state. The corresponding cycle time t is also obtained by solving the differential equation. This embodiment will not be described in detail here.

[0102] S6. Feedback the target flow rate v' and cycle time t to the cooling system to adjust the output power for adaptive control. During the etching process, process conditions vary. Changes in factors such as etching power, gas flow rate, and wafer size can alter the heat load between the electrostatic chuck and the wafer, thereby varying the temperature difference and the required cooling medium flow rate.

[0103] In order to adapt to this dynamic change, this embodiment adopts a real-time monitoring and feedback mechanism. By arranging multiple high-precision sensors in the electrostatic chuck and the cooling system, the temperature difference ΔT, the cooling medium flow rate v, and the cooling medium temperature T are obtained in real time. c Based on these real-time data, the algorithm proposed in this embodiment continuously updates the correction coefficient and re-evaluates the parameters in the initial mathematical model. For example, when the etching power suddenly increases, the temperature difference between the electrostatic chuck and the wafer rises rapidly. After the algorithm detects this change, it adjusts the correction coefficient based on the current flow rate, temperature and other data. At the same time, it may fine-tune the correction coefficient value based on historical data and new heat load conditions to ensure that the calculated target flow rate can keep up with the changes in the heat load in a timely manner, effectively remove excess heat, and maintain the stability of the electrostatic chuck temperature.

[0104] This embodiment simulates and verifies the above method, and the specific process is as follows:

[0105] The cooling medium in the cooling pipe is generally in a turbulent state, so a simulation model is established to obtain the following relationship between the flow velocity and time in the cooling pipe and the relationship between the temperature difference and time, such as Figure 8 and Figure 9 shown. Figure 8The figure shows the relationship between the target flow rate v' of the cooling medium and the cycle time t. Figure 9 The figure shows the relationship between the temperature difference ΔT and the cycle time t. Pipe1, Pipe2 and Pipe3 in the figure represent the temperature changes in the inner layer, middle layer and outer layer respectively.

[0106] By simulating the changes of three cooling pipes over time on the software, the changes in temperature difference and internal liquid flow rate are obtained, and the relationship between flow rate and time and the relationship between temperature difference and time are obtained.

[0107] In the control, this embodiment uses the minimum temperature difference value as the target value to reduce the amount of calculation. At the same time, in order to better and faster control the temperature difference approach, the flow rate of the minimum temperature difference pipeline is kept constant as much as possible.

[0108] From the simulation results, we can see that in this simulation, the temperature difference is very close after the time reaches 10S, and the flow rate change has gradually slowed down, so the best control time for this simulation is about 10S.

[0109] like Figure 10 As shown, in order to better improve the temperature adaptive control method, this embodiment starts with ionization and bombardment of plasma in the chamber, dynamically monitors the temperature difference, and transmits it back to the controller. The controller simulates and runs a curve internally, and uses the point where the temperature difference changes slowly each time (i.e., the concave point -> the point where the second derivative of the function = 0) as the current temperature control time (i.e., the time to control the chiller operation once). After this time, the temperature is detected again and transmitted back to the controller for control, thereby realizing adaptive control.

[0110] Those skilled in the art will appreciate that all or part of the steps in the above-mentioned embodiment methods can be accomplished by instructing the relevant hardware through a program. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0111] Each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to in detail. For the above embodiments, since they are basically similar to the method embodiments, the description is relatively simple. For relevant parts, please refer to the partial description of the method embodiments.

[0112] The above embodiments provide a detailed introduction to the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas. At the same time, for those skilled in the art, according to the ideas of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A temperature adaptive control method, characterized in that: The method comprises the following steps: S1. Divide the base of the electrostatic chuck into at least three regions starting from the central axis and extending toward its outer edge, forming an inner region, a middle region, and an outer region of equal area, and deploy independent temperature sensors and cooling pipes in each of the inner region, the middle region, and the outer region; S2. Acquire real-time temperature data of the inner, middle, and outer regions, and perform preprocessing to obtain noise-free temperature data; S3. Establishing an initial mathematical model to reflect the approximate relationship between the cooling medium flow rate v and the temperature difference ΔT during the semiconductor etching process; S4. Based on the assumption that the heat released by the liquid QΔt per unit time Δt is equal to the heat removed by convection ΔQ, the initial mathematical model is optimized to reflect the precise relationship between the cooling medium flow rate v and the temperature difference ΔT during the semiconductor etching process. The specific process includes the following steps: S41. Establish an initial equation where the heat released by the liquid per unit time Δt, QΔt, is equal to the heat removed by convection heat transfer, ΔQ, namely: QΔt=ΔQ Q=hAΔT Where g is the heat transfer coefficient; A is the heat exchange area between the cooling pipe and the base; S42. Calculate the heat ΔQ removed by the cooling medium through convection heat transfer within unit time Δt. The calculation formula is: Where c p is the specific heat capacity of the cooling medium; m is the mass of the cooling medium; t is the circulation time of the cooling medium; S43. Substitute the heat ΔQ into the initial equation to obtain the exact equation, namely: S44. Determine the exact relationship between the cooling medium flow rate v and the temperature difference ΔT during semiconductor etching under laminar flow conditions according to an accurate equation; S45. Determine the precise relationship between the cooling medium flow rate v and the temperature difference ΔT during semiconductor etching under turbulent conditions according to a precise equation; S5. Under the precise relationship, calculate the target flow rate v' and circulation time t for the cooling medium to circulate in the cooling pipe based on the real-time acquired temperature data so that the temperature difference ΔT between the inner layer, the middle layer, and the outer layer approaches; S6. Feedback the target flow rate v' and cycle time t to the cooling system for adjusting the output power to achieve adaptive control.

2. The temperature adaptive control method according to claim 1, characterized in that: The temperature data includes the temperature difference ΔT between the inner zone, the middle zone and the outer zone, the cooling medium flow rate v and the cooling medium temperature T c .

3. The temperature adaptive control method according to claim 1, characterized in that: The expression of the initial mathematical model is: v=v0e kΔT Where v0 is the initial flow velocity when ΔT=0; k is a constant greater than 0.

4. A temperature adaptive control device using the temperature adaptive control method according to any one of claims 1 to 3, characterized in that: include: A temperature detection module, which is composed of multiple temperature sensors distributed at different locations on the electrostatic chuck, and is used to measure the temperatures of the inner, middle, and outer regions in real time and convert temperature changes into electrical signals; a data processing and control module, which receives temperature data from the temperature detection module and has a built-in microprocessor or digital signal processor for performing real-time calculations on the temperature data to determine the deviation between the current temperature of the electrostatic chuck and the target temperature, as well as the temperature change trend; The cooling system is used to supply cooling medium to the inner layer area, the middle layer area and the outer layer area respectively, and adjust the output power according to the control signal of the data processing and control module to change the flow rate of the cooling medium.

5. The temperature adaptive control device according to claim 4, characterized in that: The cooling system further comprises a pipeline network, wherein the pipeline network and the cooling pipelines where the inner layer area, the middle layer area and the outer layer area are located form independent internal and external circulations.

6. A novel etching electrostatic chuck using the temperature adaptive control method according to any one of claims 1 to 3, comprising a base (1) as the main structure of the electrostatic chuck, and a heating layer (4) and a cooling layer (2) respectively arranged on the upper and lower sides of the base (1), characterized in that: The bottom of the base (1) is divided into at least three areas from the central axis to its outer edge, forming an inner layer area, a middle layer area and an outer layer area of ​​equal area. The inner layer area, the middle layer area and the outer layer area are each provided with a cooling pipe (3) with an independent liquid inlet and outlet. A plurality of temperature sensors (5) for real-time measurement of the temperature of the inner layer area, the middle layer area and the outer layer area are distributed in the heating layer (4).

7. The novel etching electrostatic chuck according to claim 6, characterized in that: The cooling pipe (3) is located in the cooling layer (2), and the cooling pipe (3) is a channel, a boss, or a pipe structure arranged in the cooling layer (2), for the cooling medium to flow through the inner layer area, the middle layer area, or the outer layer area through the cooling pipe (3) located in the corresponding area.

8. The novel etching electrostatic chuck according to claim 6, characterized in that: The plurality of temperature sensors (5) are respectively arranged corresponding to the inner layer area, the middle layer area and the outer layer area.

9. The novel etching electrostatic chuck according to claim 6, characterized in that: The inner layer region, the middle layer region and the outer layer region are in the shape of a ring or a rectangle.

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