Ceramic heater temperature control method and system based on thermocouple

Abstract

The present invention relates to the field of electric heating control, specifically to a temperature control method and system for a ceramic heater based on thermocouples. The method determines the thermocouple temperature measurement layout according to the layout of the heating elements of the ceramic heater, collects and analyzes the thermocouple temperature measurement data, and obtains the temperature field of the heating zone. This method estimates the heat conduction characteristics between all heating zones, thereby determining the temperature changes of all heating zones and predicting the heat space-time gaps of all heating zones. Based on the heat space-time gaps, the heating elements are subjected to heating control feedback adjustment. Based on the updated and collected thermocouple temperature measurement data during the heating control feedback adjustment process, the heating control signal application mode that matches all heating zones of the ceramic heater when the ceramic heater is in the desired heating state is determined. The present invention can overcome the problem that the heating elements of different heating zones are heated asynchronously and the heat exchange between different heating zones causes the ceramic heater as a whole to be unable to maintain a uniform heating temperature.

Description

Technical Field

[0001] The present invention relates to the field of electric heating control, and in particular to a temperature control method and system for a ceramic heater based on a thermocouple. Background Art

[0002] Ceramic heaters are electric heating devices used in semiconductor device manufacturing, primarily for uniformly heating wafers. In the semiconductor device manufacturing process, the mask pattern needs to be transferred to the wafer's photoresist layer. During the photolithography process, the wafer as a whole needs to be maintained at an appropriate temperature. Excessively high or low temperatures in certain areas of the wafer are detrimental to etching and ion implantation. Wafer surface temperature uniformity is an important technical indicator in semiconductor device manufacturing. If the wafer surface temperature cannot be maintained uniformly, the uniformity of the exposure stripe width will be directly affected.

[0003] Ceramic heaters use internal resistance wires to generate heat, transferring heat from the surface of the ceramic heater to the wafer. Considering that there are multiple independent resistance wires inside the ceramic heater, the heating temperature of the corresponding heating zone on the surface of the ceramic heater may vary after each resistance wire is energized and heated. At the same time, heat transfer will also occur between different heating zones, making it impossible for all heating zones to maintain a uniform heating temperature, affecting the ceramic heater's heating uniformity on the wafer. Therefore, how to address the differences in electric heating temperature rise in different heating zones within the ceramic heater and the possible heat transfer between different heating zones, resulting in the ceramic heater being unable to maintain a uniform heating temperature as a whole, and accordingly correlate temperature control of all heating zones, is of great significance to improving the heating temperature uniformity of the ceramic heater. Summary of the Invention

[0004] In order to address the problem of asynchronous heating of heating elements in different heating zones within a ceramic heater and the possibility of heat exchange between different heating zones, which results in the ceramic heater being unable to maintain a uniform heating temperature as a whole and reduces the heating uniformity and stability of the ceramic heater on the wafer, the present invention provides a ceramic heater temperature control method based on a thermocouple, the method comprising the following steps:

[0005] S100: determining a thermocouple temperature measurement layout for each heating zone according to a layout of heating elements in each heating zone within the ceramic heater; collecting and analyzing thermocouple temperature measurement data during operation of each heating zone to obtain a temperature field of each heating zone;

[0006] S200: estimating heat conduction characteristics between all heating zones based on the temperature fields of all heating zones; determining temperature changes of all heating zones based on the heat conduction characteristics; and predicting spatiotemporal heat gaps of all heating zones based on the temperature changes.

[0007] S300: performing heating control feedback adjustment on the heating elements of all heating zones according to the heat spatiotemporal gap; determining a heating control signal application mode that matches all heating zones of the ceramic heater when the ceramic heater is in a desired heating state according to the updated and collected thermocouple temperature measurement data during the heating control feedback adjustment process.

[0008] Preferably, in S100, the thermocouple temperature measurement layout of all heating zones in the ceramic heater is determined according to the heating element layout of the heating zones, specifically:

[0009] Obtaining layout characteristics of the heating resistor wires of all heating zones within the ceramic heater; wherein the layout characteristics of the heating resistor wires include the physical size, extension path, and spacing of the heating resistor wires within the heating zones;

[0010] According to the layout characteristics of the heating resistance wires, a finite element model analysis is performed on the heating zone to determine the heating rate distribution of the heating resistance wires in the heating zone during operation;

[0011] According to the heating rate distribution, a thermocouple temperature measurement layout for the heating zone is determined; wherein the thermocouple temperature measurement layout includes a thermocouple temperature measurement position layout for the heating zone.

[0012] Preferably, in S100, the thermocouple temperature measurement data during the operation of the heating zone is collected and analyzed to obtain the temperature field of the heating zone, specifically:

[0013] collecting thermocouple temperature measurement data during the operation of the heating zone after the ceramic heater is started, analyzing the time domain changes of the thermocouple temperature measurement data, and determining the time interval when the heating zone is in a relatively stable heating state;

[0014] The temperature measurement sub-data corresponding to the time interval is extracted from the thermocouple temperature measurement data, and the temperature spatial distribution modeling analysis of the heating zone is performed based on the thermocouple temperature measurement layout and the temperature measurement sub-data to obtain the temperature field of the heating zone.

[0015] Preferably, in S200, based on the temperature fields of all heating zones, the heat conduction characteristics between all heating zones are estimated; based on the heat conduction characteristics, the temperature changes of all heating zones are determined; based on the temperature changes, the heat spatiotemporal gaps of all heating zones are predicted, specifically:

[0016] Based on the distribution positions of all heating zones in the ceramic heater, a common boundary between any two adjacent heating zones is determined; based on the temperature field of the common boundary and its corresponding two adjacent heating zones, a heat conduction characteristic between the two adjacent heating zones is estimated; wherein the heat conduction characteristic refers to the heat exchange rate distribution characteristics of the two adjacent heating zones at the common boundary; based on the heat conduction characteristic, the temperature drift change rate of each of the two adjacent heating zones is inversely predicted;

[0017] Based on the temperature drift change rate of each of the two adjacent heating zones and the target temperature that the two adjacent heating zones are expected to maintain, the thermal spatiotemporal gap required for each of the two adjacent heating zones to maintain the target temperature is predicted; wherein, the thermal spatiotemporal gap refers to the thermal compensation value required at different positions inside the two adjacent heating zones at different times when each of the two adjacent heating zones maintains the target temperature.

[0018] Preferably, in S300, heating control feedback adjustment is performed on the heating elements of all heating zones according to the thermal spatiotemporal gap; and a heating control signal application mode matching all heating zones of the ceramic heater in the desired heating state is determined according to the updated and collected thermocouple temperature measurement data during the heating control feedback adjustment process, specifically:

[0019] According to the heat spatiotemporal gap and the spatiotemporal distribution of heat generated by the heating elements in the heating zone, heating control feedback adjustment is performed on the heating elements in the heating zone; wherein the heating control feedback adjustment includes feedback adjustment of the heating control signal amplitude and spatiotemporal ratio;

[0020] The thermocouple temperature measurement data collected and updated periodically during the heating control feedback adjustment process is analyzed to determine whether the ceramic heater is in a uniform heating temperature distribution state; when the ceramic heater is in a uniform heating temperature distribution state, the amplitude and time-space ratio parameters of the heating control signal currently applied to the heating elements of all heating zones are obtained, so as to determine the heating control signal application mode matching all heating zones.

[0021] In another aspect, the present invention provides a ceramic heater temperature control system based on a thermocouple, the system comprising the following modules:

[0022] A temperature measurement layout determination module is used to determine the thermocouple temperature measurement layout of all heating zones in the ceramic heater according to the heating element layout of the heating zones;

[0023] a temperature field determination module, configured to collect and analyze thermocouple temperature measurement data during the operation of the heating zone to obtain the temperature field of the heating zone;

[0024] a temperature change determination module, configured to estimate the heat conduction characteristics between all heating zones based on the temperature fields of all heating zones; and determine the temperature changes of each of the heating zones based on the heat conduction characteristics;

[0025] A heat gap prediction module, configured to predict the temporal and spatial heat gaps of all heating zones according to the temperature changes;

[0026] A feedback adjustment module, configured to perform heating control feedback adjustment on the heating elements of all heating zones according to the thermal spatiotemporal gap;

[0027] The control mode determination module is used to determine the heating control signal application mode that matches all heating zones of the ceramic heater when the ceramic heater is in the desired heating state based on the updated and collected thermocouple temperature measurement data during the heating control feedback adjustment process.

[0028] Preferably, the temperature measurement layout determination module is used to determine the thermocouple temperature measurement layout of the heating zone according to the heating element layout of all heating zones in the ceramic heater, specifically:

[0029] Obtaining layout characteristics of the heating resistor wires of all heating zones within the ceramic heater; wherein the layout characteristics of the heating resistor wires include the physical size, extension path, and spacing of the heating resistor wires within the heating zones;

[0030] Performing a finite element model analysis on the heating zone based on the layout characteristics of the heating resistance wires to determine the heating rate distribution of the heating resistance wires in the heating zone during operation;

[0031] According to the heating rate distribution, a thermocouple temperature measurement layout for the heating zone is determined; wherein the thermocouple temperature measurement layout includes a thermocouple temperature measurement position layout for the heating zone.

[0032] Preferably, the temperature field determination module is used to collect and analyze thermocouple temperature measurement data during the operation of the heating zone to obtain the temperature field of the heating zone, specifically:

[0033] collecting thermocouple temperature measurement data during the operation of the heating zone after the ceramic heater is started, analyzing the time domain changes of the thermocouple temperature measurement data, and determining the time interval when the heating zone is in a relatively stable heating state;

[0034] The temperature measurement sub-data corresponding to the time interval is extracted from the thermocouple temperature measurement data, and the temperature spatial distribution modeling analysis of the heating zone is performed based on the thermocouple temperature measurement layout and the temperature measurement sub-data to obtain the temperature field of the heating zone.

[0035] Preferably, the temperature change determination module is used to estimate the heat conduction characteristics between all heating zones based on the temperature fields of all heating zones; and determine the temperature changes of all heating zones based on the heat conduction characteristics, specifically:

[0036] Based on the distribution positions of all heating zones in the ceramic heater, a common boundary between any two adjacent heating zones is determined; based on the temperature field of the common boundary and its corresponding two adjacent heating zones, a heat conduction characteristic between the two adjacent heating zones is estimated; wherein the heat conduction characteristic refers to the heat exchange rate distribution characteristics of the two adjacent heating zones at the common boundary; based on the heat conduction characteristic, the temperature drift change rate of each of the two adjacent heating zones is inversely predicted;

[0037] The heat gap prediction module is used to predict the heat space-time gap of each heating zone according to the temperature change, specifically:

[0038] Based on the temperature drift change rate of each of the two adjacent heating zones and the target temperature that the two adjacent heating zones are expected to maintain, the thermal spatiotemporal gap required for each of the two adjacent heating zones to maintain the target temperature is predicted; wherein, the thermal spatiotemporal gap refers to the thermal compensation value required at different positions inside the two adjacent heating zones at different times when each of the two adjacent heating zones maintains the target temperature.

[0039] Preferably, the feedback adjustment module is used to perform heating control feedback adjustment on the heating elements of all heating zones according to the thermal spatiotemporal gap, specifically:

[0040] According to the heat spatiotemporal gap and the spatiotemporal distribution of heat generated by the heating elements in the heating zone, heating control feedback adjustment is performed on the heating elements in the heating zone; wherein the heating control feedback adjustment includes feedback adjustment of the heating control signal amplitude and spatiotemporal ratio;

[0041] The control mode determination module is used to determine the heating control signal application mode that matches all heating zones of the ceramic heater in the desired heating state based on the updated and collected thermocouple temperature measurement data during the heating control feedback adjustment process, specifically:

[0042] The thermocouple temperature measurement data collected and updated periodically during the heating control feedback adjustment process is analyzed to determine whether the ceramic heater is in a uniform heating temperature distribution state; when the ceramic heater is in a uniform heating temperature distribution state, the amplitude and time-space ratio parameters of the heating control signal currently applied to the heating elements of all heating zones are obtained, so as to determine the heating control signal application mode matching all heating zones.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] According to the layout of heating elements in all heating zones within the ceramic heater, the thermocouple temperature measurement layout for the heating zone is determined; the thermocouple temperature measurement data during the operation of the heating zone is collected and analyzed to obtain the temperature field of the heating zone. According to the layout characteristics of the heating resistor wire inside the heating zone, the heating zone is subjected to finite element modeling analysis to determine the heating rate distribution of the heating resistor wire inside the heating zone after being energized, and to determine the location points suitable for setting thermocouple sensors for temperature measurement operations, so as to facilitate the subsequent independent setting of thermocouple sensors for temperature measurement operations based on the above-mentioned location points, and ensure that the temperature data of the heating resistor wire inside each heating zone after being energized is accurately collected. The matching temperature measurement sub-data is extracted from the thermocouple temperature measurement data, and then the temperature spatial domain modeling analysis of the heating zone is performed based on the layout position of the thermocouple sensor in the heating zone and its corresponding temperature measurement sub-data to obtain the temperature field of the heating zone and realize the global temperature field distribution of the ceramic heater.

[0045] Based on the temperature fields of all heating zones, the heat conduction characteristics between all heating zones are estimated; based on the heat conduction characteristics, the temperature changes of all heating zones are determined; based on the temperature changes, the spatiotemporal heat gaps of all heating zones are predicted. In this way, based on the temperature drift change rates of two adjacent heating zones and the target temperatures that the two adjacent heating zones are expected to maintain, the heat compensation values ​​required at different locations within the two adjacent heating zones at different times to maintain the target temperatures are predicted. This can provide a control basis for adjusting the heating state of the heating elements within the heating zones to ensure that all heating zones reach the target temperature synchronously, allowing the two adjacent heating zones to heat up synchronously to reach the target temperature.

[0046] Based on the spatiotemporal heat gap, heating control feedback adjustments are performed on the heating elements in all heating zones. Based on the updated and collected thermocouple temperature measurement data during the heating control feedback adjustment process, the heating control signal application pattern that matches all heating zones in the ceramic heater when it is in the desired heating state is determined. This approach allows the heating control feedback adjustment pattern for the heating elements within each heating zone to be determined in the shortest possible time, effectively overcoming the issues of asynchronous heating of heating elements in different heating zones and the inability of the ceramic heater to maintain a uniform heating temperature as a whole due to heat exchange between different heating zones. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without inventive efforts. Among them:

[0048] Figure 1 The present invention provides a flow chart of a ceramic heater temperature control method based on a thermocouple.

[0049] Figure 2 It is a heating resistance wire layout and heating area distribution of ceramic heater.

[0050] Figure 3 It is another heating resistance wire layout of ceramic heater and its heating area distribution.

[0051] Figure 4 It is a thermocouple temperature measurement circuit.

[0052] Figure 5 It is the thermocouple temperature measurement data curve of all heating zones after the ceramic heater is started.

[0053] Figure 6 It is the temperature field distribution diagram of all heating areas of the ceramic heater.

[0054] Figure 7 It is a structural diagram of the thermocouple-based ceramic heater temperature control system provided by the present invention. DETAILED DESCRIPTION

[0055] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. It will be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0056] The terms "comprise," "comprising," and "having," and any variations thereof, as used herein, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements, but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0057] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute a separate or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0058] See also Figure 1 As shown, the present invention provides a ceramic heater temperature control method based on a thermocouple, the method comprising the following steps:

[0059] S100: Determine the layout of thermocouple temperature measurement for the heating zone according to the layout of heating elements in all heating zones in the ceramic heater; collect and analyze the thermocouple temperature measurement data during the operation of the heating zone to obtain the temperature field of the heating zone.

[0060] Furthermore, in S100, the thermocouple temperature measurement layout of the heating zone is determined according to the heating element layout of all heating zones in the ceramic heater, specifically:

[0061] Obtaining layout characteristics of the heating resistor wires of all heating zones within the ceramic heater; wherein the layout characteristics of the heating resistor wires include the physical dimensions, extension paths, and spacing of the heating resistor wires within the heating zones;

[0062] According to the layout characteristics of the heating resistance wire, the finite element model analysis of the heating area is carried out to determine the heating rate distribution of the heating resistance wire in the heating area during operation;

[0063] According to the heating rate distribution, the thermocouple temperature measurement layout of the heating zone is determined; wherein the thermocouple temperature measurement layout includes the thermocouple temperature measurement position layout of the heating zone.

[0064] The ceramic heater includes a ceramic panel and a heating resistor encapsulated inside the ceramic panel. When the heating resistor is energized, it generates heat, which is then transferred to the ceramic panel, causing the panel to heat up. At this point, the wafer in direct contact with the ceramic panel receives the heat and heats up synchronously. The layout of the heating resistor inside the ceramic heater and its heating performance directly affect the uniformity of the heating temperature of the ceramic heater. In order to meet the needs of different wafer heating applications, the layout of the heating resistor inside the ceramic heater mainly includes a square wave layout and a concentric circle layout, as shown below: Figure 2 and 3 shown.

[0065] from Figure 2 As can be seen in (a), the heating resistance wire is packaged inside the ceramic panel in a meandering square wave state. Each square wave heating resistance wire is connected to an external power supply and can be regarded as an independent heating element. By controlling the control electrical signal applied to a square wave heating resistance wire by the external power supply, the heating state of a square wave heating resistance wire can be changed independently. Figure 2 As can be seen from (b), according to the square wave layout of the heating resistance wire inside the ceramic heater and each square wave heating resistance wire as an independent heating element, the projection range of each square wave heating resistance wire on the surface of the ceramic heater can be regarded as a heating zone, thereby dividing the surface of the ceramic heater into several heating zones.

[0066] from Figure 3As can be seen in (a), the heating resistor wires are coiled in a concentric circle state and packaged inside the ceramic panel, wherein each adjacent preset number of concentric circle heating resistor wires are connected in series to form an independent heating element, and each independent heating element is connected to an external power supply. By controlling the control electrical signal applied by the external power supply to an independent heating element, the heating state of an independent heating element can be changed independently. For example, for Figure 3 As for (a), in the order from inside to outside, the first and second concentric circle heating resistance wires are connected in series to form an independent heating element, the third and fourth concentric circle heating resistance wires are connected in series to form an independent heating element, the fifth and sixth concentric circle heating resistance wires are connected in series to form an independent heating element, and so on. Figure 3 As can be seen from (b), according to the concentric circle layout of the heating resistance wires inside the ceramic heater and the fact that every two adjacent concentric circle heating resistance wires are connected in series to form an independent heating element, the projection range of every two adjacent concentric circle heating resistance wires connected in series on the surface of the ceramic heater can be regarded as a heating zone, thereby dividing the surface of the ceramic heater into several heating zones.

[0067] Figure 2 and 3 Only two implementations of the layout of the internal heating resistance wire of the ceramic heater are shown. The layout of the internal heating resistance wire of the ceramic heater is not limited to the above two implementations, and can also be achieved through other implementations.

[0068] from Figure 2 and 3As can be seen, to meet different heating requirements, the heating resistors encapsulated within a ceramic heater can have different layout characteristics. These layout characteristics may include, but are not limited to, the physical dimensions of the heating resistors (e.g., the cross-sectional diameter of the heating resistors), the extension path (e.g., the shape of the extension path of the heating resistors within the ceramic heater), and the spacing (e.g., the spacing between adjacent heating resistors). Accordingly, the layout of the heating resistors within each heating zone within the ceramic heater also varies in terms of the physical dimensions, extension paths, and spacing of the heating resistors. Considering that the heating resistors within each heating zone are independent heating elements that generate heat independently in response to control signals from an external power source, the heat distribution within the heating zone after the heating elements are energized is not only related to the control signals but also to the aforementioned layout characteristics of the heating resistors within the heating zone. Generally speaking, the larger the physical dimensions of the heating resistors, the wider the extension path, and the smaller the spacing, the more heat is distributed within the heating zone after the heating resistors are energized, making it easier to heat the heating zone to the target temperature in a shorter period of time. Taking into account that the layout of the heating resistor wires in the heating zone does not evenly cover the entire heating zone, when the heating resistor wires are energized and heated, it cannot be guaranteed that each position in the heating zone will receive the same amount of heat. The positions adjacent to the heating resistor wires receive more heat per unit time and heat up faster; the positions far away from the heating resistor wires receive less heat per unit time and heat up slower, resulting in the heating and heating progress of different positions in the heating zone being out of sync. In order to comprehensively and accurately detect the temperature at different positions within the heating zone, the heating zone can first be subjected to finite element modeling analysis based on the layout characteristics of the heating resistor wires within the heating zone to determine the heating rate distribution after the heating resistor wires within the heating zone are energized; wherein, the heating rate distribution refers to the spatial distribution of the heat generation rate per unit time within the heating zone after the heating resistor wires are energized. Based on the above heating rate distribution, the position points within the heating zone where the heating rate values ​​meet the preset rate range conditions are determined, and the above position points are determined as the position points where the thermocouple sensors are set for temperature measurement operations (such as Figure 2 and 3 As shown in the figure, the thermocouple temperature measurement layout of each heating zone is determined, which facilitates the subsequent independent setting of thermocouple sensors according to the above-mentioned position points for temperature measurement operations, ensuring accurate collection of temperature data after the heating resistance wire inside each heating zone is energized.

[0069] In addition, in order to improve the temperature detection accuracy of each location point by the thermocouple sensor, the following can be used: Figure 4The thermocouple temperature measurement circuit shown in the figure can use a K-type thermocouple; the hot end of the K-type thermocouple is in contact with the position point, and the cold end is connected to the operational amplifier. The operational amplifier amplifies the thermoelectromotive force output by the K-type thermocouple, and then uses an adder to proportionally sum it with the reference electromotive force. The summation result is output to the temperature sensor, which then outputs the final temperature measurement data.

[0070] Furthermore, in S100, the thermocouple temperature measurement data during the operation of the heating zone is collected and analyzed to obtain the temperature field of the heating zone, specifically:

[0071] Collect thermocouple temperature measurement data during the operation of the heating zone after the ceramic heater is started, analyze the time domain changes of the thermocouple temperature measurement data, and determine the time interval when the heating zone is in a relatively stable heating state;

[0072] The temperature measurement sub-data corresponding to the time interval are extracted from the thermocouple temperature measurement data. According to the thermocouple temperature measurement layout and the temperature measurement sub-data, the temperature spatial distribution modeling and analysis of the heating area are carried out to obtain the temperature field of the heating area.

[0073] After a ceramic heater is activated, the heating elements within each heating zone are energized and heated by a control signal from an external power supply. Given the varying sizes of the heating zones and the varying heating efficiencies of the heating elements within each zone, the heating rate and ultimate temperature attainable within each zone will also vary. If there is a difference in the heating rate and ultimate temperature attainable between adjacent heating zones, heat conduction will inevitably occur between them, transferring heat from the higher-temperature zone to the lower-temperature zone. This heat conduction between adjacent zones can prevent them from maintaining stable temperatures for extended periods, particularly within the area bordering the two zones, which can experience significant temperature fluctuations. To ensure that all heating zones maintain a consistent and stable temperature for extended periods after the ceramic heater is activated, the heating element status within each zone must be adjusted based on the actual temperature distribution within each zone. This prevents variations in the ultimate temperature attainable by each zone under the current heating element status. Therefore, it is necessary to fully determine the actual temperature distribution of each zone under the current heating element status within the zone.

[0074] Considering that after the ceramic heater is started, it takes a certain time for the heating element in each heating zone to heat up and then heat up stably, and it also takes a certain time for the heat generated by the heating element to be evenly transferred to the entire range of the corresponding heating zone. Figure 5 As shown, corresponding to Figure 3 Thermocouple temperature measurement data curve of all heating zones in the ceramic heater. Figure 5It can be seen that the distribution of the thermocouple temperature measurement data curve of each heating zone corresponds to three different time intervals, which include the first time interval, the second time interval, and the third time interval in sequence from the moment the ceramic heater is started. Among them, the first time interval corresponds to the time interval that the heating element needs to go through from the beginning of heating to stable heating. During this period, the heating efficiency of the heating element is high, and the amount of heat transferred to the heating zone per unit time is also large, and the thermocouple temperature measurement result rises rapidly; the second time interval corresponds to the time interval that the heat generated by the heating element after stable heating is evenly transferred to the global range of the corresponding heating zone. During this period, the diffusion rate from the heating element in the heating zone is low, and the thermocouple temperature measurement result rises slowly; the third time interval corresponds to the heat from the heating element has been evenly diffused and transferred to the global range of the corresponding heating zone, and the overall temperature of the heating zone is uniform and stable; however, the areas of different heating zones are different, and the heating efficiencies of the heating elements in different heating zones are also different, so the temperature values ​​that can eventually be reached in each heating zone are also different, which is reflected in Figure 5 The final stable temperature values ​​reached by the three curves in the third time interval are also different. Figure 5 In the figure, the black curve, red curve, and purple curve correspond to Figure 3 The temperature change curves of the innermost heating zone, the middle heating zone and the outermost heating zone of the ceramic heater are shown; accordingly, the temperature values ​​finally stably reached by the innermost heating zone, the middle heating zone and the outermost heating zone of the ceramic heater also decrease in sequence.

[0075] The temperature measurement data generated by the thermocouple temperature measurement operation in the above two time intervals cannot truly reflect the temperature value that the heating zone can ultimately reach. If the thermocouple temperature measurement data in the above two time intervals are used in the process of determining the temperature distribution of the heating zone, the obtained temperature distribution will not correctly reflect the actual temperature distribution of the heating zone when the heating zone and the heating element reach a thermal equilibrium state. Therefore, it is necessary to obtain and use the temperature measurement data of the heating zone during the period when the heating is in a relatively stable heating state to construct the temperature field of the heating zone. Specifically, the thermocouple temperature measurement data of each heating zone during the operation process after the ceramic heater is started is collected, and the thermocouple temperature measurement data is subjected to time domain variation fitting processing to obtain the thermocouple temperature measurement curve corresponding to each heating zone. Then, the heating relative temperature state time interval (i.e., the above third time interval) corresponding to the thermocouple temperature measurement curve is analyzed and determined. Taking the time interval when the heating zone is in a relatively stable heating state as the benchmark, the matching temperature measurement sub-data are extracted from the thermocouple temperature measurement data. Then, according to the layout position of the thermocouple sensor in the heating zone and its corresponding temperature measurement sub-data, the temperature spatial domain modeling analysis of the heating zone is performed to obtain the temperature field of the heating zone. The temperature fields of all heating zones are integrated according to their distribution positions in the ceramic heater to obtain the following: Figure 6 The temperature field distribution diagram is shown.

[0076] S200: Estimate the heat conduction characteristics between all heating zones based on the temperature fields of all heating zones; determine the temperature changes of all heating zones based on the heat conduction characteristics; and predict the spatiotemporal heat gaps of all heating zones based on the temperature changes.

[0077] Furthermore, in S200, based on the temperature fields of all heating zones, the heat conduction characteristics between all heating zones are estimated; based on the heat conduction characteristics, the temperature changes of all heating zones are determined; based on the temperature changes, the spatiotemporal heat gaps of all heating zones are predicted, specifically:

[0078] Based on the distribution of all heating zones within the ceramic heater, the common boundary between any two adjacent heating zones is determined. Based on the temperature field of the common boundary and its corresponding two adjacent heating zones, the heat conduction characteristics between the two adjacent heating zones are estimated. The heat conduction characteristics refer to the distribution characteristics of the heat exchange rate between the two adjacent heating zones at the common boundary. Based on the heat conduction characteristics, the temperature drift change rate of each of the two adjacent heating zones is inversely predicted.

[0079] Based on the temperature drift change rate of each of the two adjacent heating zones and the target temperature that the two adjacent heating zones are expected to maintain, the thermal spatiotemporal gap required for each of the two adjacent heating zones to maintain the target temperature is predicted; wherein, the thermal spatiotemporal gap refers to the thermal compensation value required at different positions within the two adjacent heating zones at different times when each of the two adjacent heating zones maintains the target temperature.

[0080] A ceramic heater includes multiple heating zones, each of which heats up due to its internal heating elements. As can be seen from the above, different heating zones ultimately reach different temperatures. When two adjacent heating zones ultimately reach different temperatures, the higher-temperature zone transfers heat to the lower-temperature zone, a phenomenon known as heat conduction. During heat conduction, the zone that has already reached the target temperature (corresponding to the higher-temperature zone) transfers heat to the lower-temperature zone, causing the lower-temperature zone's actual temperature to drop while the lower-temperature zone's temperature rises. As a result, the actual temperatures of both adjacent zones fail to reach their target temperatures and drift, becoming unstable. This temperature drift is particularly pronounced at the common boundary between the two zones. Therefore, suppressing this temperature drift requires accurate and timely control of the heating elements within the two adjacent zones, altering their heating states so that the two zones heat up synchronously to reach the target temperature.

[0081] In order to suppress the above-mentioned temperature drift changes, it is necessary to accurately and timely control the heating elements inside the two adjacent heating zones to change their own heating state. According to the common boundary between any two adjacent heating zones and the temperature field of the corresponding two adjacent heating zones, the heat exchange rate distribution characteristics of the two adjacent heating zones on the common boundary are estimated, and the temperature drift change rate of each of the two adjacent heating zones is inverted and predicted to accurately characterize the temperature fluctuation change of the two adjacent heating zones. In addition, according to the temperature drift change rate of each of the two adjacent heating zones and the target temperature that the two adjacent heating zones are expected to maintain, the heat compensation values ​​required at different positions inside the two adjacent heating zones at different times when each of the two adjacent heating zones maintains the target temperature are predicted. This can provide a control basis for adjusting the heating state of the heating elements inside the heating zones to ensure that all heating zones reach the target temperature synchronously.

[0082] S300: Based on the thermal spatiotemporal gap, heating control feedback adjustment is performed on the heating elements of all heating zones; based on the updated and collected thermocouple temperature measurement data during the heating control feedback adjustment process, a heating control signal application mode that matches all heating zones when the ceramic heater is in the desired heating state is determined.

[0083] Furthermore, in S300, heating control feedback adjustment is performed on the heating elements of all heating zones according to the thermal spatiotemporal gap; based on the updated and collected thermocouple temperature measurement data during the heating control feedback adjustment process, a heating control signal application mode matching all heating zones of the ceramic heater in the desired heating state is determined, specifically:

[0084] Based on the spatiotemporal heat gap and the spatiotemporal heat distribution of the heating elements in the heating zone, heating control feedback adjustment is performed on the heating elements in the heating zone; wherein the heating control feedback adjustment includes feedback adjustment of the heating control signal amplitude and spatiotemporal ratio;

[0085] The thermocouple temperature measurement data collected and updated periodically during the heating control feedback adjustment process is analyzed to determine whether the ceramic heater is in a uniform heating temperature distribution state; when the ceramic heater is in a uniform heating temperature distribution state, the amplitude and time-space ratio parameters of the heating control signal currently applied to the heating elements of all heating zones are obtained to determine the heating control signal application mode matching all heating zones.

[0086] In order to enable all heating zones to obtain sufficient heat from their internal heating elements in a timely manner and to be heated synchronously to the same target temperature, it is necessary to adaptively adjust the heating state of the heating elements inside each heating zone. Taking into account the different temperature differences between the current actual temperature and the target temperature of different heating zones, the different areas of different heating zones, and the different heating efficiencies of the heating elements inside different heating zones, in order to enable all heating zones to obtain sufficient heat from their internal heating elements in a timely and accurate manner to achieve synchronous heating, the heating control signal amplitude and time-space ratio feedback adjustment are performed on the heating elements in the heating zones according to the time-space gap of the heat in the heating zones and the time-space distribution state of the heating of the heating elements inside the heating zones, and the heating efficiency of the heating elements inside each heating zone is changed to meet the heat requirements for synchronous heating of each heating zone. In addition, during the heating control feedback adjustment process of the heating elements, it is not guaranteed that all heating zones can reach the target temperature synchronously through a single adjustment, but multiple heating control feedback adjustments are required. In order to determine the heating control feedback adjustment mode for the heating elements within each heating zone in the shortest possible time, the thermocouple temperature measurement data collected and updated periodically during the heating control feedback adjustment process is analyzed to determine whether the ceramic heater is in a uniform heating temperature distribution state, that is, to determine whether the global surface of the ceramic heater is in a uniform heating temperature distribution state corresponding to the target temperature. When the ceramic heater is in a uniform heating temperature distribution state, the amplitude and time-space ratio parameters of the heating control signal currently applied to the heating elements in all heating zones are obtained, and based on the amplitude and time-space ratio parameters of the above heating control signal, the PWM form heating control signal application mode matching the heating elements in all heating zones is determined, effectively overcoming the problem of asynchronous heating and temperature rise of the heating elements in different heating zones and the heat exchange between different heating zones, which makes it impossible for the ceramic heater as a whole to maintain a uniform heating temperature.

[0087] See also Figure 7 As shown, the present invention provides a ceramic heater temperature control system based on a thermocouple, which includes the following modules:

[0088] A temperature measurement layout determination module is used to determine the thermocouple temperature measurement layout of the heating zone according to the heating element layout of all heating zones in the ceramic heater;

[0089] The temperature field determination module is used to collect and analyze the thermocouple temperature measurement data during the operation of the heating zone to obtain the temperature field of the heating zone;

[0090] A temperature change determination module is used to estimate the heat conduction characteristics between all heating zones based on the temperature fields of all heating zones; and to determine the temperature changes of all heating zones based on the heat conduction characteristics;

[0091] The heat gap prediction module is used to predict the temporal and spatial heat gaps of all heating zones based on temperature changes;

[0092] A feedback adjustment module is used to perform heating control feedback adjustment on the heating elements of all heating zones according to the thermal spatiotemporal gap;

[0093] The control mode determination module is used to determine the heating control signal application mode that matches all heating zones of the ceramic heater when the ceramic heater is in the desired heating state based on the updated collected thermocouple temperature measurement data during the heating control feedback adjustment process.

[0094] Furthermore, the temperature measurement layout determination module is used to determine the thermocouple temperature measurement layout of the heating zone according to the heating element layout of all heating zones in the ceramic heater, specifically:

[0095] Obtaining layout characteristics of the heating resistor wires of all heating zones within the ceramic heater; wherein the layout characteristics of the heating resistor wires include the physical dimensions, extension paths, and spacing of the heating resistor wires within the heating zones;

[0096] According to the layout characteristics of the heating resistance wire, the finite element model analysis of the heating area is carried out to determine the heating rate distribution of the heating resistance wire in the heating area during operation;

[0097] According to the heating rate distribution, the thermocouple temperature measurement layout of the heating zone is determined; wherein the thermocouple temperature measurement layout includes the thermocouple temperature measurement position layout of the heating zone.

[0098] Furthermore, the temperature field determination module is used to collect and analyze the thermocouple temperature measurement data during the operation of the heating zone to obtain the temperature field of the heating zone, specifically:

[0099] Collect thermocouple temperature measurement data during the operation of the heating zone after the ceramic heater is started, analyze the time domain changes of the thermocouple temperature measurement data, and determine the time interval when the heating zone is in a relatively stable heating state;

[0100] The temperature measurement sub-data corresponding to the time interval are extracted from the thermocouple temperature measurement data. According to the thermocouple temperature measurement layout and the temperature measurement sub-data, the temperature spatial distribution modeling and analysis of the heating area are carried out to obtain the temperature field of the heating area.

[0101] Furthermore, the temperature change determination module is used to estimate the heat conduction characteristics between all heating zones based on the temperature fields of all heating zones; and determine the temperature changes of all heating zones based on the heat conduction characteristics, specifically:

[0102] Based on the distribution of all heating zones within the ceramic heater, the common boundary between any two adjacent heating zones is determined. Based on the temperature field of the common boundary and its corresponding two adjacent heating zones, the heat conduction characteristics between the two adjacent heating zones are estimated. The heat conduction characteristics refer to the distribution characteristics of the heat exchange rate between the two adjacent heating zones at the common boundary. Based on the heat conduction characteristics, the temperature drift change rate of each of the two adjacent heating zones is inversely predicted.

[0103] The heat gap prediction module is used to predict the temporal and spatial heat gaps of all heating zones based on temperature changes. Specifically:

[0104] Based on the temperature drift change rate of each of the two adjacent heating zones and the target temperature that the two adjacent heating zones are expected to maintain, the thermal spatiotemporal gap required for each of the two adjacent heating zones to maintain the target temperature is predicted; wherein, the thermal spatiotemporal gap refers to the thermal compensation value required at different positions within the two adjacent heating zones at different times when each of the two adjacent heating zones maintains the target temperature.

[0105] Furthermore, the feedback adjustment module is used to perform heating control feedback adjustment on the heating elements of all heating zones according to the heat spatiotemporal gap, specifically:

[0106] Based on the spatiotemporal heat gap and the spatiotemporal heat distribution of the heating elements in the heating zone, heating control feedback adjustment is performed on the heating elements in the heating zone; wherein the heating control feedback adjustment includes feedback adjustment of the heating control signal amplitude and spatiotemporal ratio;

[0107] The control mode determination module is used to determine the heating control signal application mode that matches all heating zones of the ceramic heater when the ceramic heater is in the desired heating state based on the updated collected thermocouple temperature measurement data during the heating control feedback adjustment process. Specifically,

[0108] The thermocouple temperature measurement data collected and updated periodically during the heating control feedback adjustment process is analyzed to determine whether the ceramic heater is in a uniform heating temperature distribution state; when the ceramic heater is in a uniform heating temperature distribution state, the amplitude and time-space ratio parameters of the heating control signal currently applied to the heating elements of all heating zones are obtained to determine the heating control signal application mode matching all heating zones.

[0109] The operation and effects of the thermocouple-based ceramic heater temperature control system of the present invention are corresponding to and consistent with the above-mentioned thermocouple-based ceramic heater temperature control method, and the thermocouple-based ceramic heater temperature control system will not be repeated here.

[0110] Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by adding the necessary general-purpose hardware platform, or of course, by combining hardware and software. Based on this understanding, the essence of the above technical solution, or the portion that contributes to the prior art, can be embodied in the form of a computer product. The present invention 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 code.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it, and other embodiments may also be used. Although the present invention has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A temperature control method for a ceramic heater based on a thermocouple, characterized in that: The method comprises the following steps: S100: determining a thermocouple temperature measurement layout for each heating zone according to a layout of heating elements in each heating zone within the ceramic heater; collecting and analyzing thermocouple temperature measurement data during operation of each heating zone to obtain a temperature field of each heating zone; S200: Estimate the heat conduction characteristics between all heating zones based on the temperature fields of all heating zones; determine the temperature changes of all heating zones based on the heat conduction characteristics; and predict the spatiotemporal heat gaps of all heating zones based on the temperature changes, specifically: Based on the distribution positions of all heating zones in the ceramic heater, a common boundary between any two adjacent heating zones is determined; based on the temperature field of the common boundary and its corresponding two adjacent heating zones, a heat conduction characteristic between the two adjacent heating zones is estimated; wherein the heat conduction characteristic refers to the heat exchange rate distribution characteristics of the two adjacent heating zones at the common boundary; based on the heat conduction characteristic, the temperature drift change rate of each of the two adjacent heating zones is inversely predicted; Based on the respective temperature drift change rates of the two adjacent heating zones and the target temperatures that the two adjacent heating zones are expected to maintain, the thermal spatiotemporal gap required for the two adjacent heating zones to each maintain the target temperatures is predicted; wherein the thermal spatiotemporal gap refers to the thermal compensation values ​​required at different locations within the two adjacent heating zones at different times to each maintain the target temperatures; S300: Based on the thermal spatiotemporal gap, heating control feedback adjustment is performed on the heating elements of all heating zones; based on the updated and collected thermocouple temperature measurement data during the heating control feedback adjustment process, a heating control signal application mode matching all heating zones of the ceramic heater in the desired heating state is determined, specifically: According to the heat spatiotemporal gap and the spatiotemporal distribution of heat generated by the heating elements in the heating zone, heating control feedback adjustment is performed on the heating elements in the heating zone; wherein the heating control feedback adjustment includes feedback adjustment of the heating control signal amplitude and spatiotemporal ratio; The thermocouple temperature measurement data collected and updated periodically during the heating control feedback adjustment process is analyzed to determine whether the ceramic heater is in a uniform heating temperature distribution state; when the ceramic heater is in a uniform heating temperature distribution state, the amplitude and time-space ratio parameters of the heating control signal currently applied to the heating elements of all heating zones are obtained, so as to determine the heating control signal application mode matching all heating zones.

2. The method according to claim 1, characterized in that In S100, according to the layout of heating elements in all heating zones in the ceramic heater, the thermocouple temperature measurement layout of the heating zones is determined, specifically: Obtaining layout characteristics of the heating resistor wires of all heating zones within the ceramic heater; wherein the layout characteristics of the heating resistor wires include the physical size, extension path, and spacing of the heating resistor wires within the heating zones; According to the layout characteristics of the heating resistance wires, a finite element model analysis is performed on the heating zone to determine the heating rate distribution of the heating resistance wires in the heating zone during operation; According to the heating rate distribution, a thermocouple temperature measurement layout for the heating zone is determined; wherein the thermocouple temperature measurement layout includes a thermocouple temperature measurement position layout for the heating zone.

3. The method according to claim 2, characterized in that In S100, the thermocouple temperature measurement data during the operation of the heating zone is collected and analyzed to obtain the temperature field of the heating zone, specifically: collecting thermocouple temperature measurement data during the operation of the heating zone after the ceramic heater is started, analyzing the time domain changes of the thermocouple temperature measurement data, and determining the time interval when the heating zone is in a relatively stable heating state; The temperature measurement sub-data corresponding to the time interval is extracted from the thermocouple temperature measurement data, and the temperature spatial distribution modeling analysis of the heating zone is performed based on the thermocouple temperature measurement layout and the temperature measurement sub-data to obtain the temperature field of the heating zone.

4. Thermocouple-based ceramic heater temperature control system, characterized in that: The system includes the following modules: A temperature measurement layout determination module is used to determine the thermocouple temperature measurement layout of all heating zones in the ceramic heater according to the heating element layout of the heating zones; a temperature field determination module, configured to collect and analyze thermocouple temperature measurement data during the operation of the heating zone to obtain the temperature field of the heating zone; The temperature change determination module is used to estimate the heat conduction characteristics between all heating zones based on the temperature fields of all heating zones; and determine the temperature changes of all heating zones based on the heat conduction characteristics, specifically: Based on the distribution positions of all heating zones in the ceramic heater, a common boundary between any two adjacent heating zones is determined; based on the temperature field of the common boundary and its corresponding two adjacent heating zones, a heat conduction characteristic between the two adjacent heating zones is estimated; wherein the heat conduction characteristic refers to the heat exchange rate distribution characteristics of the two adjacent heating zones at the common boundary; based on the heat conduction characteristic, the temperature drift change rate of each of the two adjacent heating zones is inversely predicted; The heat gap prediction module is used to predict the heat space-time gap of each heating zone according to the temperature change, specifically: Based on the respective temperature drift change rates of the two adjacent heating zones and the target temperatures that the two adjacent heating zones are expected to maintain, the thermal spatiotemporal gap required for the two adjacent heating zones to each maintain the target temperatures is predicted; wherein the thermal spatiotemporal gap refers to the thermal compensation values ​​required at different locations within the two adjacent heating zones at different times to each maintain the target temperatures; The feedback adjustment module is used to perform heating control feedback adjustment on the heating elements of all heating zones according to the heat spatiotemporal gap, specifically: According to the heat spatiotemporal gap and the spatiotemporal distribution of heat generated by the heating elements in the heating zone, heating control feedback adjustment is performed on the heating elements in the heating zone; wherein the heating control feedback adjustment includes feedback adjustment of the heating control signal amplitude and spatiotemporal ratio; The control mode determination module is used to determine the heating control signal application mode that matches all heating zones of the ceramic heater in the desired heating state based on the updated and collected thermocouple temperature measurement data during the heating control feedback adjustment process, specifically: The thermocouple temperature measurement data collected and updated periodically during the heating control feedback adjustment process is analyzed to determine whether the ceramic heater is in a uniform heating temperature distribution state; when the ceramic heater is in a uniform heating temperature distribution state, the amplitude and time-space ratio parameters of the heating control signal currently applied to the heating elements of all heating zones are obtained, so as to determine the heating control signal application mode matching all heating zones.

5. The system according to claim 4, characterized in that The temperature measurement layout determination module is used to determine the thermocouple temperature measurement layout of each heating zone according to the heating element layout of all heating zones in the ceramic heater, specifically: Obtaining layout characteristics of the heating resistor wires of all heating zones within the ceramic heater; wherein the layout characteristics of the heating resistor wires include the physical size, extension path, and spacing of the heating resistor wires within the heating zones; According to the layout characteristics of the heating resistance wires, a finite element model analysis is performed on the heating zone to determine the heating rate distribution of the heating resistance wires in the heating zone during operation; According to the heating rate distribution, a thermocouple temperature measurement layout for the heating zone is determined; wherein the thermocouple temperature measurement layout includes a thermocouple temperature measurement position layout for the heating zone.

6. The system according to claim 5, characterized in that The temperature field determination module is used to collect and analyze the thermocouple temperature measurement data during the operation of the heating zone to obtain the temperature field of the heating zone, specifically: collecting thermocouple temperature measurement data during the operation of the heating zone after the ceramic heater is started, analyzing the time domain changes of the thermocouple temperature measurement data, and determining the time interval when the heating zone is in a relatively stable heating state; The temperature measurement sub-data corresponding to the time interval is extracted from the thermocouple temperature measurement data, and the temperature spatial distribution modeling analysis of the heating zone is performed based on the thermocouple temperature measurement layout and the temperature measurement sub-data to obtain the temperature field of the heating zone.

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