Novel etching electrostatic chuck and temperature self-adaptive control device and method

Abstract

The invention relates to the technical field of semiconductors, solves the technical problems that a traditional electrostatic chuck cannot be suitable for a complex etching process environment and the temperature of each part of the surface of the electrostatic chuck is difficult to accurately control, and particularly relates to a novel etching electrostatic chuck and a temperature self-adaptive control device and method. Comprising the steps of dividing areas, acquiring real-time temperature data, establishing an initial mathematical model, optimizing the initial mathematical model, calculating target flow velocity and circulation time, and feeding back to a cooling system to realize self-adaptive control. The flow velocity of the cooling medium can be more accurately controlled in a complex etching process environment, efficient and stable self-adaptive control of the temperature of the electrostatic chuck is realized, the quality and reliability of a semiconductor etching process are improved, wafer defects caused by temperature fluctuation are reduced, and the production efficiency is improved. And an advanced temperature control technical solution is provided 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] In the document "Study on Wafer Surface Temperature Control in Dry Etching", it is known that in the dry etching process, the wafer temperature will directly affect the etching rate, etching uniformity and etching morphology, thus affecting the final device performance. Through experiments, it is confirmed that the clamping voltage and helium pressure of the electrostatic chuck, the RF source power, the lower electrode temperature and the wafer itself will have a certain impact on the wafer temperature during the etching process. Among them, 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 the lower electrode cooling temperature have basically the same impact on the wafer temperature, with the least impact.

[0003] In the document "Simulation Study on Temperature Control Method of Electrostatic Chuck of Plasma Etcher", it can be known that plasma etching is a key process in modern integrated circuit manufacturing. As the feature size of integrated circuits transitions from 45 to 22nm, the diameter of wafers used to manufacture chips transitions from 300mm to 450mm, and the industry's requirements for plasma etching processes are getting higher and higher. Among them, the etching rate and etching uniformity of the wafer are important indicators for evaluating etching quality, and the uniformity of wafer temperature distribution is an important factor affecting these two indicators. The wafer temperature distribution is mainly affected by the spatial distribution of plasma energy and the electrostatic chuck used to fix the wafer and contact the wafer. Due to the existence of plasma inhomogeneity in the chamber, it is difficult to achieve uniform spatial distribution of ion energy, so the electrostatic chuck plays a key role in controlling the wafer temperature.

[0004] At present, the method of controlling the wafer temperature using an electrostatic chuck is mainly the structural control method. This method designs a series of surface morphology structures on the surface of the electrostatic chuck, such as grooves and bosses, and then passes cooling gas, such as helium, through the gaps in the structure, and then controls the wafer temperature by adjusting the morphology structure parameters and gas pressure. Although the structural control method can improve the uniformity of wafer temperature to a certain extent, since the structural parameters of the electrostatic chuck cannot be changed during etching, and the cooling gas pressure cannot be accurately controlled at various locations on the chuck surface, the structural control method can only handle situations with specific plasma energy spatial distribution. Summary of the invention

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

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a temperature adaptive control method, the method comprising the following steps:

[0007] S1. Divide the base of the electrostatic chuck 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, and arrange independent temperature sensors and cooling pipes in the inner layer area, the middle layer area and the outer layer area respectively;

[0008] S2, obtaining real-time temperature data of the inner layer, middle layer and outer layer, and performing preprocessing to obtain noise-free temperature data;

[0009] S3, establishing an initial mathematical model for reflecting 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 fact that the heat released by the liquid QΔt is equal to the heat removed by convection heat transfer ΔQ in unit time Δt, 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, the target flow rate v' and the circulation time t of the cooling medium circulating in the cooling pipe are calculated according to the temperature data obtained in real time so that the temperature difference ΔT between the inner layer area, the middle layer area and the outer layer area tends to be close;

[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=v 0 e kΔT

[0016] In the formula, v 0 is the initial flow rate 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 that the heat released by the liquid per unit time Δt, QΔt, is equal to the heat removed by convection heat exchange, ΔQ, that is:

[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 taken away by the cooling medium in unit time Δt by convection heat exchange, and the calculation formula is:

[0023]

[0024] In the formula, 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, determining the precise relationship between the cooling medium flow rate v and the temperature difference ΔT during semiconductor etching under laminar flow conditions according to a precise 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 a plurality of temperature sensors and is distributed at different positions of the electrostatic chuck to measure the temperature of the inner layer area, the middle layer area and the outer layer area in real time and convert the temperature change into an electrical signal;

[0031] A data processing and control module, wherein the data processing and control module receives the temperature data from the temperature detection module, and the data processing and control module 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 and the temperature change trend;

[0032] A 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 also includes 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, the inner layer area, the middle layer area and the outer layer area are all provided with cooling pipes with independent liquid inlets and outlets, 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 arranged corresponding to the inner layer area, the middle layer area and the outer layer area respectively.

[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, realize efficient, stable and adaptive control of the temperature of the electrostatic chuck, 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 of the temperature difference between the inner layer, the middle layer and the outer layer, thereby accurately controlling the temperature of various locations on 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, and cooperate with three independent cooling pipes to act on three areas of the electrostatic chuck respectively, so as to better stabilize the temperature during wafer etching, ensure the uniformity of the wafer and the consistency of the process, and at the same time greatly improve the situation of slight warping of the wafer around. 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 A schematic diagram of temperature distribution on the surface of a wafer when a conventional electrostatic chuck is used in the present invention;

[0045] Figure 3 A 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 Embodiment 1 of the present invention;

[0047] Figure 5 This is a schematic diagram of the distribution of cooling pipes in the first embodiment of the present invention;

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

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

[0050] Figure 8 is a graph showing the relationship between the target flow rate of the cooling medium and the cycle time in the third embodiment of the present invention;

[0051] Fig. 9 is a graph showing the relationship between the temperature difference and the cycle time in the third embodiment of the present invention;

[0052] Fig.10 The present invention is a block diagram of the principle of improving the temperature adaptive control method.

[0053] In the figure: 1. base; 2. cooling layer; 3. cooling pipe; 4. heating layer; 5. temperature sensor. DETAILED DESCRIPTION

[0054] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific implementation methods, so that the implementation process of how the present application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0055] Embodiment 1

[0056] like Figure 1As shown in the figure, it is a cross-sectional view of the electrostatic chuck structure currently used. The method of controlling the wafer temperature using the electrostatic chuck is mainly the structural control method. This method designs a series of surface morphology structures (such as grooves and bosses) on the surface of the electrostatic chuck, then passes cooling gas (such as helium) into the gap of the structure, and then controls the wafer temperature by adjusting the morphology structure parameters and gas pressure. Figure 2 As shown, it 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 the outer edge thereof, forming an inner layer area, a middle layer area and an outer layer area of ​​equal area, such as Figure 3 The inner layer, middle layer and outer layer are each provided with a cooling pipe 3 having an independent liquid inlet and liquid outlet, and 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, as shown in FIG. Figure 4 shown.

[0058] The cooling pipe 3 is located in the cooling layer 2. The cooling pipe 3 is a channel, a boss or a pipe structure arranged in the cooling layer 2, and the coolant flows through the cooling pipe 3 in the corresponding area through the inner layer area, the middle layer area or the outer layer area. A plurality of temperature sensors 5 are arranged corresponding to the inner layer area, the middle layer area and the outer layer area respectively. The area shape of the inner layer area, the middle layer area and the outer layer area is annular or rectangular.

[0059] like Figure 5 As shown, the inner layer area, middle layer area and outer layer area are all laid with independent cooling pipes 3, and have independent liquid inlets and liquid outlets. In this embodiment, for example, the base 1 with a diameter of 200 mm is evenly divided into three areas at the bottom, and the inner layer area, middle layer area and outer layer area each occupy 1 / 3 of the total area of ​​the bottom, and the cooling pipe 3 is embedded in the bottom of the base 1, and the surrounding arrangement density of a single cooling pipe 3 needs to occupy 80%-90% of the area of ​​the corresponding area.

[0060] like Figure 6 As shown, in this embodiment, the temperature distribution diagram on the surface of the wafer 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, and cooperate with three independent cooling pipes to act on three areas of the electrostatic chuck respectively, so as to better stabilize the temperature of the wafer during etching, ensure the uniformity of the wafer and the consistency of the process, and at the same time greatly improve the situation of slight warping of the wafer on all sides.

[0062] Embodiment 2

[0063] Based on the novel etching electrostatic chuck proposed in Example 1, this embodiment proposes a temperature adaptive control system applied to the novel etching electrostatic chuck, which aims to cooperate with the electrostatic chuck to achieve a better and faster approach to the temperature difference between the inner layer area, the middle layer area and the outer layer area, so as to accurately control the temperature of each part of the surface of the electrostatic chuck, so as to better stabilize 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 a plurality of temperature sensors, which are distributed at different positions of the electrostatic chuck to measure the temperature of the inner layer, the middle layer and the outer layer in real time, and convert the temperature change into an electrical signal. 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 positions of the electrostatic chuck, and can measure the temperature of the inner layer, the middle layer and the outer layer 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 the temperature data from the temperature detection module. The data processing and control module has a built-in microprocessor or digital signal processor for real-time calculation of the temperature data to determine the deviation between the current temperature of the electrostatic chuck and the target temperature and the temperature change trend. Specifically, the data processing and control module receives the temperature data from the temperature detection module and performs analysis and processing. The module has a built-in advanced microprocessor or digital signal processor, such as the i.MX 6ULL ​​single-core processor sold by NXP Semiconductors Co., Ltd., which has powerful data computing capabilities. It calculates the temperature data in real time according to a preset algorithm to determine key information such as the deviation between the current temperature and the target temperature and the temperature change trend.

[0066] Based on the calculation results, a control signal is generated to control the power of the pump in the cooling system, 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 that 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 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, so as to change the flow rate of the cooling medium. The cooling system also includes a pipeline network, and 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. 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 performance of the chiller is stable, and the output power can be accurately adjusted according to the control signal, thereby changing the flow rate of the cooling medium. In addition, the pipeline network is reasonably designed to ensure that the cooling medium is evenly distributed to various areas of the electrostatic chuck, thereby improving the uniformity of temperature control.

[0068] Embodiment 3

[0069] In a specific etching process, due to the different density distribution of plasma in the chamber, the temperature distribution on the wafer surface is also uneven during bombardment. In addition, the back of the wafer has different degrees of contact with the base, and the temperature distribution of the wafer taken away by the cooling water is also uneven, which leads to wafer warping. This embodiment proposes a temperature adaptive control method in combination with embodiments one and two, which 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 temperature of the electrostatic chuck, 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 comprises the following steps:

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

[0071] S2. Obtain real-time temperature data of the inner zone, middle zone and outer zone, and perform preprocessing to obtain noise-free temperature data, including the temperature difference ΔT between the inner zone, middle zone and outer zone, the cooling medium flow rate v and the cooling medium temperature T 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 the heat transfer, and the flow rate of the cooling medium directly affects the efficiency of the heat transfer. Based on the basic law of thermal convection, an initial mathematical model of the flow rate and the temperature difference is constructed. Therefore, the expression of the initial mathematical model expressing the approximate relationship is:

[0073] v=v 0 e kΔT

[0074] In the formula, v 0 is the initial flow rate when ΔT=0; k is a constant greater than 0, which 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, the temperature difference ΔT is the horizontal axis and the cooling medium flow rate v is the vertical axis. When ΔT = 0, v = v 0 . 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 QΔt per unit time Δt is equal to the heat taken away by convection heat exchange ΔQ. To more accurately calculate the precise relationship between the cooling medium flow rate v and the temperature difference ΔT, it is also necessary to consider the relationship between the heat taken away 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 and turbulent states, so the relationship between the heat taken away 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 = v 0 e kΔT Substituting into h = av 0 e kΔT + b, so Q = (av 0 e kΔT +b)AΔT.

[0078] In turbulent state: According to the principle of Dittus-Boelter formula, assuming h = cv 0.8 +d, c and d are constants, v = v 0 e kΔT Substituting into h = c(v0 e kΔT ) 0.8 + d, so Q = [c(v 0 e kΔT ) 0.8 +d]AΔT.

[0079] Graphical relationships such as Figure 7 As shown, the temperature difference ΔT is the horizontal axis and the cooling medium flow rate v is the vertical axis. When ΔT = 0, v = v 0 . 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 , 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 gives Where T 0 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 and the temperature difference over a period of time. As time goes by, 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 , corresponding to the 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 to ΔT f The cooling pipe with a large initial temperature difference has a fast temperature drop. 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 QΔt is equal to the heat removed by convection heat transfer ΔQ in unit time Δt, 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 that the heat released by the liquid per unit time Δt, QΔt, is equal to the heat removed by convection heat exchange, ΔQ, that is:

[0087] QΔt=ΔQ

[0088] Q=hAΔT

[0089] Where h is the heat transfer coefficient, which is used to reflect 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 taken away by the cooling medium in unit time Δt by convection heat exchange, and the calculation formula is:

[0091]

[0092] In the formula, 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, the heat released by the liquid in unit time Δt 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 = av in laminar flow 0 e kΔT +b Substitute into the exact equation have to If y = ΔT, this is a The differential equation of is solved by separation of variables, namely: Integrate both sides Solving this integral gives the temperature difference ΔT as a function of the cycle time t, and substituting it into v = v 0 e kΔT The accurate 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 in turbulent flow is h = c(v 0 e kΔT ) 0.8 +d Substitute 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=v 0 e kΔT The accurate relationship between the cooling medium flow rate v and the temperature difference ΔT is obtained.

[0101] S5. Under the precise relationship, the target flow rate v' and the cycle time t at which the cooling medium circulates in the cooling pipe so that the temperature difference ΔT between the inner layer, the middle layer and the outer layer tends to be close are calculated according to the temperature data obtained in real time. Through the determined precise relationship, whether in the laminar state or the turbulent state, the target flow rate v' that makes the temperature difference ΔT between the inner layer, the middle layer and the outer layer tend to be close can be calculated according to the temperature data obtained in real time, and the corresponding cycle time t is also obtained when solving the differential equation, and 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 to achieve adaptive control. Since the process conditions are not constant during the etching process, changes in factors such as etching power, gas flow, and wafer size will cause changes in the heat load between the electrostatic chuck and the wafer, thereby causing the temperature difference and the required cooling medium flow rate to change accordingly.

[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. cBased 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 according to the current flow rate, temperature and other data. At the same time, it may fine-tune the correction coefficient value according to 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 time, effectively take away excess heat, and maintain the stability of the electrostatic chuck temperature.

[0104] This embodiment performs simulation verification on 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 Fig. 9 shown. Figure 8 The relationship between the target flow rate v' of the cooling medium and the cycle time t is shown. Fig. 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 unchanged as much as possible.

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

[0109] like Fig.10 As shown, in order to better improve the temperature adaptive control method, the present 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 to work 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 can understand that all or part of the steps in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a program, so the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application can 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 codes.

[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 each other. For the above embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiments.

[0112] The above implementation methods have been described in detail. 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 idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on 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 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, and arrange independent temperature sensors and cooling pipes in the inner layer area, the middle layer area and the outer layer area respectively; S2, obtaining real-time temperature data of the inner layer, middle layer and outer layer, and performing preprocessing to obtain noise-free temperature data; S3, establishing an initial mathematical model for reflecting the approximate relationship between the cooling medium flow rate v and the temperature difference ΔT during the semiconductor etching process; S4. Based on the fact that the heat released by the liquid QΔt is equal to the heat removed by convection heat transfer ΔQ in unit time Δt, 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; S5. Under the precise relationship, the target flow rate v' and the circulation time t of the cooling medium circulating in the cooling pipe are calculated according to the temperature data obtained in real time so that the temperature difference ΔT between the inner layer area, the middle layer area and the outer layer area tends to be close; 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 layer, the middle layer and the outer layer, 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 Wherein, v0 is the initial flow velocity when ΔT=0; k is a constant greater than 0.

4. The temperature adaptive control method according to claim 1, characterized in that: In step S4, the specific process includes the following steps: S41. Establish an initial equation that the heat released by the liquid per unit time Δt, QΔt, is equal to the heat removed by convection heat exchange, ΔQ, that is: QΔt=ΔQ Q=hAΔT Where h is the heat transfer coefficient; A is the heat exchange area between the cooling pipe and the base; S42, calculate the heat ΔQ taken away by the cooling medium in unit time Δt by convection heat exchange, and the calculation formula is: In the formula, 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, determining the precise relationship between the cooling medium flow rate v and the temperature difference ΔT during semiconductor etching under laminar flow conditions according to a precise equation; 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.

5. A device applied to the temperature adaptive control method according to any one of claims 1 to 4, characterized in that: include: A temperature detection module, which is composed of a plurality of temperature sensors and is distributed at different positions of the electrostatic chuck to measure the temperature of the inner layer area, the middle layer area and the outer layer area in real time and convert the temperature change into an electrical signal; A data processing and control module, wherein the data processing and control module receives the temperature data from the temperature detection module, and the data processing and control module 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 and the temperature change trend; A 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.

6. The temperature adaptive control device according to claim 5, characterized in that: The cooling system further comprises a pipeline network, and 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.

7. A novel etching electrostatic chuck applied to the adaptive control method according to any one of claims 1 to 4, 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) having an independent liquid inlet and liquid 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).

8. The novel etching electrostatic chuck according to claim 7, 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), allowing the coolant 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.

9. The novel etching electrostatic chuck according to claim 7, characterized in that: The plurality of temperature sensors (5) are arranged corresponding to the inner layer area, the middle layer area and the outer layer area respectively.

10. The novel etching electrostatic chuck according to claim 7, characterized in that: The inner layer area, the middle layer area and the outer layer area are in the shape of a ring or a rectangle.

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