Temperature Control Method

Abstract

The present application discloses an electrostatic chuck device and a temperature control method thereof. The electrostatic chuck device includes an apparatus base, a heating layer, and an insulating adsorption layer for mounting a wafer, which are arranged in this order from bottom to top, an adsorption electrode for adsorbing the wafer is provided in the insulating adsorption layer, at least two main heaters for heating the wafer mounted on the insulating adsorption layer are provided in the heating layer, and an adsorption electrode for adsorbing the wafer is provided in the insulating adsorption layer, the electrostatic chuck device further includes a controller, and a plurality of compensation heaters are further provided in the insulating adsorption layer, each of the compensation heaters is insulated from the adsorption electrode, each of the compensation heaters is electrically connected to the controller, and the controller is used to control the on / off of each compensation heater and the power of each compensation heater.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION This application relates to the technical field of semiconductor processing, and more particularly to electrostatic chucking devices and temperature control methods. [Background technology]

[0002] In the processing of semiconductor workpieces (e.g., wafers) such as wafers, the workpieces are typically heated using a heater such as an electrostatic chuck to increase the temperature of the entire workpiece in order to improve process efficiency and / or process effect, etc. However, in actual processing, for various reasons, temperature variations can occur at different positions on the workpiece supported by the same heater, resulting in low process uniformity of the workpiece. Summary of the Invention [Problem to be solved by the invention]

[0003] The present application discloses an electrostatic chuck apparatus and a temperature control method that can solve the current problem of low process uniformity on a workpiece due to possible temperature variations at different locations on the workpiece. [Means for solving the problem]

[0004] To solve the above problem, the embodiment of the present application is realized as follows.

[0005] In a first aspect, an embodiment of the present application provides an electrostatic chuck device for semiconductor equipment, comprising, in order from bottom to top, a device base, a heating layer, and an insulating adsorption layer on which a wafer is mounted, an adsorption electrode for adsorbing the wafer is provided within the insulating adsorption layer, at least two main heaters for heating the wafer mounted on the insulating adsorption layer are provided within the heating layer, an adsorption electrode for adsorbing the wafer is provided within the insulating adsorption layer, and the electrostatic chuck device further comprises a controller, wherein a plurality of compensation heaters are further provided within the insulating adsorption layer, each of the plurality of compensation heaters is provided insulated from the adsorption electrode and each of the plurality of compensation heaters is electrically connected to the controller, and the controller is used to control on / off of each of the compensation heaters and to control power for each of the compensation heaters.

[0006] In a second aspect, an embodiment of the present application is a temperature control method applied to the electrostatic chuck apparatus for mounting and heating a wafer, comprising: Step S1: establishing a correspondence between process steps and target compensation heaters, wherein the target compensation heaters are the remaining compensation heaters other than the compensation heaters corresponding to positions of extreme values ​​of multiple original process results among the multiple compensation heaters when performing each of the process steps, the original process results are process results at positions corresponding to the multiple compensation heaters on the wafer when each of the process steps is performed in a state where the at least two main heaters in the heating layer are kept on and each of the compensation heaters is kept off, and the extreme value is a maximum value when the process result shows a positive correlation with the temperature of the corresponding position on the wafer, and the extreme value is a minimum value when the process result shows a negative correlation with the temperature of the corresponding position on the wafer; and step S2 of acquiring a process step immediately before execution, controlling each of the main heaters in the heating layer to be turned on, and controlling each of the target compensation heaters corresponding to the process step immediately before execution to be turned on according to the correspondence relationship.

[0007] An embodiment of the present application discloses an electrostatic chuck device applicable to semiconductor equipment. The electrostatic chuck device includes an insulating adsorption layer disposed on a heating layer, the heating layer disposed on an apparatus substrate, at least two main heaters in the heating layer capable of heating a wafer placed on the insulating adsorption layer, and an adsorption electrode in the insulating adsorption layer capable of adsorbing an electrode, thereby ensuring stable support of the wafer on the insulating adsorption layer. The electrostatic chuck device also includes a controller, and a plurality of compensation heaters are further disposed in the insulating adsorption layer, all electrically connected to the controller, which can control the on / off and power of each compensation heater. Subsequently, by detecting process results such as the etching rate at different positions on the wafer, the temperature status at the corresponding positions on the wafer can be indirectly obtained from the process results. Therefore, if the wafer is heated only by the main heater in the heating layer during some processes, resulting in inconsistent temperatures at different positions on the wafer, the main heater can be used to heat the wafer during the processes. Then, the controller can turn on at least one corresponding compensation heater of the electrostatic chuck device and control the power of the compensation heater that is turned on, so that the compensation heater can heat the corresponding position on the wafer, raising the temperature at that position to the maximum temperature value of the wafer (i.e., the maximum or minimum value of the wafer process result), thereby ensuring relatively high process uniformity for the wafer. Furthermore, because the power of the compensation heater is smaller than that of the main heater, by placing the compensation heater on an insulating adsorption layer at a small distance from the wafer, the heat from the compensation heater can be transferred more quickly and accurately to the region of the wafer corresponding to the compensation heater, thereby providing thermal compensation to the corresponding position on the wafer and improving response speed.

[0008] The drawings described herein are used to provide a further understanding of the present application, constitute a part of the present application, and the exemplary embodiments and descriptions thereof are used to interpret the present application and are not to be construed as unduly limiting the present application. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a structural schematic diagram of an electrostatic chuck device according to an embodiment of the present application. [Figure 2] 1 is a structural schematic diagram of an insulating attraction portion of an electrostatic chuck device according to an embodiment of the present application. FIG. [Figure 3] FIG. 2 is a schematic diagram illustrating the distribution of a plurality of compensation heating units of an electrostatic chuck device according to an embodiment of the present application. [Figure 4] 1 is a structural schematic diagram of an attraction electrode of an electrostatic chuck device according to an embodiment of the present application; [Figure 5] 1 is a schematic diagram illustrating the electrical principle of an electrostatic chuck device according to an embodiment of the present application. [Figure 6] 1 is a schematic diagram illustrating the electrical principle of a partial structure of an electrostatic chuck device according to an embodiment of the present application. [Figure 7] 1 is a flowchart of a temperature control method according to an embodiment of the present application. [Figure 8] 3 is a schematic diagram showing the position distribution of a plurality of temperature measurement points on a wafer in a temperature control method according to an embodiment of the present application. [Figure 9] 3 is a schematic diagram showing the relative positions of a plurality of temperature measurement points on a wafer and one compensation heater in a temperature control method according to an embodiment of the present application. FIG. [Figure 10] 10A and 10B are schematic diagrams illustrating temperature comparisons of a plurality of temperature measurement points on a wafer when a compensation heater is in an on and off state in a temperature control method according to an embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0010] In order to clarify the objectives, technical solutions and advantages of the present application, the technical solutions of the present application will be described below clearly and completely with reference to specific embodiments of the present application and corresponding drawings. It is obvious that the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. Based on the embodiments of the present application, all other embodiments that a person skilled in the art can obtain without creative work fall within the scope of protection of the present application.

[0011] Hereinafter, the technical solutions according to the embodiments of the present application will be described in detail with reference to the accompanying drawings.

[0012] As shown in Figures 1 to 5, the present application discloses an electrostatic chuck device applicable to semiconductor equipment. The electrostatic chuck device is used to mount a workpiece such as a wafer and change the temperature of the workpiece, thereby improving process efficiency and the quality of the process results. The electrostatic chuck device includes a device base 400, a heating layer 300, and an insulating adsorption layer 500, which are arranged in this order from bottom to top. Note that the vertical direction is the vertical direction during normal operation of the electrostatic chuck device, which may more intuitively be direction A in Figure 1.

[0013] The insulating adsorption layer 500 is used to support a wafer, and at least two main heaters are provided within the heating layer 300. The main heaters heat the wafer placed on the insulating adsorption layer 500 to increase the wafer temperature and improve the wafer processing efficiency and effectiveness. Specifically, the main heaters may include a heating device such as a resistance wire, thereby ensuring the main heaters have heating capacity. The number of main heaters may be two, three, or more. The number of main heaters can be determined according to parameters such as the size and shape of each main heater, and is not limited herein. The shape of multiple main heaters may be fan-shaped, and together they form a complete heating area of ​​the heating layer 300. In another embodiment of the present application, one of the main heaters has a circular structure and the rest have an annular structure. The multiple main heaters are assembled in a nested manner to form the heating area of ​​the heating layer 300. This distribution of the main heaters allows the size of the heating area to be controlled according to the diameter of the workpiece, such as a wafer, with relatively high control accuracy. Of course, in addition to the main heater, the heating layer 300 may further include a structure for fixing the main heater, which may be made of a molding material such as quartz or ceramic, and multiple main heaters are embedded in the molding material such as quartz or ceramic to form a heating layer 300 with a stable structure.

[0014] An adsorption electrode is provided within the insulating adsorption layer 500, and the adsorption electrode can adsorb a wafer, thereby stably placing and fixing the wafer on the electrostatic chuck device. The adsorption electrode may be formed by printing, and its specific shape and structure can be determined according to actual conditions. As shown in FIG. 4, the adsorption electrode may be divided into two regions, DC+ and DC-. The entire adsorption electrode may have a ring structure, or may be formed by winding a metal wire multiple times. An insulating layer may also be formed by forming the adsorption electrode within a molding material such as quartz or ceramic. This not only serves to secure the adsorption electrode but also provides insulation to the insulating adsorption layer 500, preventing adverse effects on the normal operation of the compensation heater 100 provided within the adsorption insulating layer (described below).

[0015] The electrostatic chuck device according to the embodiment of the present application further includes a controller. A plurality of compensation heaters 100 are further provided within the insulating adsorption layer 500. Each compensation heater 100 can heat the insulating adsorption layer 500 during operation, thereby compensating for and increasing the temperature of the region where each compensation heater 100 is located. Each compensation heater 100 is provided insulated from the adsorption electrode.

[0016] Specifically, each compensation heater 100 may include a heating device such as a resistance wire. Its specific shape, dimensions, and other parameters can be determined based on actual needs and are not limited herein. The number of compensation heaters 100 can be determined based on actual parameters such as the dimensions and shapes of the compensation heaters 100 and the insulating adsorption layer 500 and is not limited herein. More specifically, the heating power of each compensation heater 100 may be essentially the same, thereby reducing the difficulty of controlling multiple compensation heaters 100 and improving the temperature control accuracy of the electrostatic chuck apparatus. Furthermore, the compensation heaters 100 may be formed within a molding material, such as quartz or ceramic, of the insulating adsorption layer 500. The compensation heaters 100 and the adsorption electrode are spaced apart in the thickness direction of the insulating adsorption layer 500, ensuring that each compensation heater 100 is insulated from the adsorption electrode.

[0017] In one specific embodiment, the positions of the multiple compensation heaters 100 in the insulating adsorption layer 500 may be the same in the thickness direction of the insulating adsorption layer 500, or the multiple compensation heaters 100 may be uniformly distributed so that each compensation heater 100 corresponds to a different region of the insulating adsorption layer 500, and the regions corresponding to the multiple compensation heaters 100 together form the entire surface of the insulating adsorption layer 500. As shown in Figure 3, the compensation heaters 100 may be distributed in an annular structure, with the compensation heaters 100 in any one annular structure being distributed in the circumferential direction, and the structure and dimensions of the compensation heaters 100 included in each annular structure may be determined according to actual circumstances and are not limited herein.

[0018] Furthermore, the size of each compensation heater 100 may be relatively small, and in the process of arranging the compensation heaters 100, the distribution of the compensation heaters 100 may be as even as possible, thereby improving the temperature compensation capability of the compensation heaters 100 for the electrostatic chuck device and making it more comprehensive.

[0019] As described above, the electrostatic chuck apparatus according to the embodiment of the present application includes a controller, and the multiple compensation heaters 100 may all be electrically connected to the controller, thereby controlling the on / off of each compensation heater 100 and the power of each compensation heater 100. During the operation of the electrostatic chuck apparatus, a control rule corresponding to the controller may be preset, and the controller may control the compensation heater 100 corresponding to the process step immediately before execution based on the control rule input in advance, according to the specific circumstances of the process step to be executed.

[0020] More specifically, before the electrostatic chuck device is put into mass production, the heating conditions of the electrostatic chuck device can be tested in advance. During the test, all main heaters in the heating layer 300 are turned on, and all of the compensation heaters 100 are controlled to be off. The temperatures of multiple measurement positions on the electrostatic chuck device can be measured, and the measurement positions correspond one-to-one to the positions of the compensation heaters 100, thereby obtaining multiple basic data.

[0021] Of course, since measuring temperature data is relatively difficult during the measurement process, parameters such as the etching rate at different positions on a workpiece such as a wafer can be measured to determine the specific temperature situation of that position on the wafer using a parameter such as the etching rate that is directly related to temperature. That is, the basic data can specifically be the etching rate. Furthermore, parameters such as the etching rate can be either directly proportional to temperature or inversely proportional to temperature. For the sake of convenience, the following description will be based on the example in which the etching rate of the wafer is directly proportional to temperature. The multiple measurement positions can specifically be the structural centers of each compensation heater 100, or of course, the measurement positions can also be the edges of each compensation heater 100, as long as the measurement positions of each compensation heater 100 correspond to each other.

[0022] The magnitudes of the basic data may differ due to various factors, such as differences in heat conduction conditions at different positions on the electrostatic chuck device. Based on this, the compensation heater 100 corresponding to the basic data is turned on and used to heat that position, thereby increasing the temperature of the area where the compensation heater 100 is located. This can achieve the goal of reducing or even eliminating the difference between the basic data with the largest value among the basic data and that basic data, thereby making the differences between the basic data relatively small or making all of the differences between the basic data zero.

[0023] During the above test process, the controller can control the on / off of each compensation heater 100, i.e., the compensation heater 100 corresponding to the maximum etching rate of the wafer is turned off, and the compensation heaters 100 corresponding to other positions where the etching rate of the wafer is lower than the maximum etching rate are turned on, and these on-state compensation heaters 100 are used to perform temperature compensation for each position, thereby increasing the temperature of the areas of the wafer corresponding to the multiple on-state compensation heaters 100, and further increasing the etching rate.

[0024] When the compensation heater 100 corresponding to a position on the wafer where the etching rate is relatively low is turned on, the etching rate of that position can be increased, but the compensation heater 100 in the on state may increase the temperature of that position more than the temperature of the highest temperature position on the wafer, so that the etching rate of that position becomes the new maximum etching rate position, and the difference in etching rate between different positions on the wafer may still be large. Based on this, the controller may further control multiple compensation heaters 100 to operate with different powers, so that the compensation heaters 100 in the on state can compensate the temperature of their corresponding regions to be close to, and even the same as, the highest temperature of the wafer, ensuring a relatively high consistency of the etching rates between different positions on the wafer.

[0025] The on-power of multiple compensation heaters 100 may be obtained by prior testing. Specifically, according to the specific process to be performed, compensation heaters 100 corresponding to regions of the wafer where the etching rate is less than the maximum value may be turned on with different powers, and the power value closest to the maximum etching rate may be recorded. During mass production, as long as the process is performed, the controller can control the compensation heaters 100 to be turned on with the power value obtained by the testing, so that the temperature and etching rate of the regions of the wafer corresponding to the compensation heaters 100 can correspond to the maximum wafer temperature and etching rate, ensuring high process uniformity across the wafer.

[0026] The present embodiment discloses an electrostatic chuck device applicable to semiconductor equipment. In the electrostatic chuck device, an insulating adsorption layer 500 is disposed on a heating layer 300, which is disposed on an apparatus substrate 400. At least two main heaters in the heating layer 300 heat a wafer placed on the insulating adsorption layer 500, and an adsorption electrode in the insulating adsorption layer 500 can adsorb electrodes, thereby ensuring stable support of the wafer on the electrostatic chuck device. The electrostatic chuck device also includes a controller. A plurality of compensation heaters 100 are further disposed in the insulating adsorption layer 500, and the plurality of compensation heaters 100 are electrically connected to the controller. The controller can control the on / off and power of each compensation heater 100. Subsequently, by detecting process results such as the etch rate at different locations on the wafer, the temperature status at the corresponding locations on the wafer can be indirectly obtained from the process results. Therefore, if the wafer temperature at different locations on the wafer is inconsistent when only the main heater in the heating layer 300 is used to heat the wafer during some processes, the controller can first turn on at least one corresponding compensation heater 100 in the electrostatic chuck device and control the operating power of the compensation heater 100 that is turned on. The compensation heater 100 can then heat the corresponding location on the wafer, raising the temperature at that location to the maximum temperature value of the wafer (i.e., the maximum or minimum value of the wafer process result), thereby ensuring relatively high process uniformity for the wafer. Furthermore, because the power of the compensation heater 100 is lower than that of the main heater, by positioning the compensation heater 100 on the insulating adsorption layer 500 at a closer distance to the wafer, the heat from the compensation heater 100 can be transferred more quickly and accurately to the region of the wafer corresponding to the compensation heater 100, thereby providing thermal compensation to the corresponding location on the wafer and achieving a fast response time.

[0027] As described above, the insulating adsorption layer 500 including the compensation heater 100 and the adsorption electrode can be formed by integral molding or the like. Specifically, ceramic material is provided between the compensation heater 100 and the adsorption electrode and on the outside of both by integral sintering, and the compensation heater 100 and the adsorption electrode are fixed within the ceramic material by sintering, thereby forming the insulating adsorption layer 500.

[0028] 2, the insulating adhesive layer 500 may include a first insulating sublayer 530, a second insulating sublayer 520, and a third insulating sublayer 510, which are arranged in this order from bottom to top. The first insulating sublayer 530, the second insulating sublayer 520, and the third insulating sublayer 510 are all insulating structures, i.e., they are all made of insulating materials such as ceramics, and they are all plate-like or layer-like structures, thereby ensuring that devices on opposite sides of any one of the three can be insulated from each other.

[0029] The adsorption electrode is disposed between the third insulating sub-layer 510 and the second insulating sub-layer 520 to form an adsorption sub-layer 540, and the compensation heaters 100 are all disposed between the second insulating sub-layer 520 and the first insulating sub-layer 530 to form a compensation heating layer 550. That is, in this embodiment, the chucking electrode and the compensation heater 100 are insulated from each other by a molded structure such as the second insulating sub-layer 520. Furthermore, the formed insulating chucking layer 500 provides a relatively reliable insulation effect between the chucking electrode and the compensation heater 100. Furthermore, the pre-fabrication of the first insulating sub-layer 530, the second insulating sub-layer 520, and the third insulating sub-layer 510 not only provides a fixing base for the chucking electrode and the compensation heater 100, but also increases the stability of the relative positions of the chucking electrode and the compensation heater 100. This prevents the chucking electrode and / or the compensation heater from shifting from their original positions during the integral molding process of the chucking electrode, the compensation heater 100, and the insulating material. This ensures that the chucking electrode, particularly the multiple compensation heaters 100, are maintained in their predetermined positions, thereby improving the heating uniformity of the entire electrostatic chuck.

[0030] Specifically, the first insulating sub-layer 530, the second insulating sub-layer 520, and the third insulating sub-layer 510 are all sheet-like structures formed by mixing ceramic particles and adhesive. Then, multiple compensation heaters 100 may be provided on the first insulating sub-layer 530. Each compensation heater 100 may be an independent electric heating device. The specific positions of the compensation heaters 100 can be determined in advance through a heating test of the heating layer 300, and the compensation heaters 100 are positioned as close as possible to the positions of the heating layer 300 where the wafer heating temperature is relatively low. Of course, the compensation heaters 100 may be evenly distributed on the first insulating sub-layer 530. The compensation heaters 100 that need to be turned on during the process are determined according to the specific process type. Then, the second insulating sub-layer 520 is pressed onto the side of the compensation heating layer 550 away from the first insulating sub-layer 530 to cover it, and then an adsorption electrode is formed on the second insulating sub-layer 520 by printing or the like, and then the third insulating sub-layer 510 is pressed onto the adsorption layer to cover it, thereby forming the entire structure of the insulating adsorption layer 500. Finally, the adsorption electrode and the compensation heater 100 are securely fixed within the first insulating sub-layer 530, the second insulating sub-layer 520, and the third insulating sub-layer 510 by integral sintering, thereby forming the insulating adsorption layer 500 with a stable structure.

[0031] Optionally, the compensation heater 100 comprises a metal resistance heater formed by screen printing, thereby reducing the difficulty of processing multiple compensation heaters. The cables of the compensation heater 100 are routed through the device base 400 and the heating layer 300 to the outside of the device base 400, thereby protecting the cables of the compensation heater 100 using the device base 400 and the heating layer 300 and bundling the cables of the multiple compensation heaters 100 together, reducing the difficulty of organizing the cables of each compensation heater 100. Optionally, the number of compensation heaters 100 may be between 10 and 100, thereby ensuring that the difficulty of assembling and connecting the multiple compensation heaters 100 is controllable and providing the heating layer 300 with the most accurate and stable compensation effect possible.

[0032] As described above, the compensation heaters 100 may be uniformly distributed within the insulating adsorption layer 500. Alternatively, the compensation heaters 100 may form a central compensation region and a plurality of annular compensation regions that are concentrically distributed, i.e., the central compensation region has a circular structure and the annular compensation regions have annular structures, with one of the annular compensation regions disposed around the outside of the central compensation region and the remaining annular compensation regions disposed in sequence around the annular compensation region, i.e., the annular compensation regions are all positioned around the center of the central compensation region, with the center of the central compensation region as their center. The compensation heaters 100 form a wafer-matching structure, which can prevent heat waste during the process of providing thermal compensation to the wafer and improve the accuracy of wafer temperature compensation to a certain extent.

[0033] Each annular compensation region may include a plurality of compensation heaters 100, thereby further reducing the size of each compensation heater 100 and improving the accuracy of temperature compensation. In addition, in the process of arranging the plurality of compensation heaters 100 in each annular compensation region, the plurality of compensation heaters 100 in each annular compensation region may include two compensation heaters 100 arranged symmetrically in a pair, or may be centrally symmetrical as shown in FIG. 3, thereby facilitating the compensation calculation process for the plurality of compensation heaters 100. Furthermore, the central compensation region includes one compensation heater.

[0034] Optionally, the controller may include a control unit 210 and multiple execution units 220. Specifically, the control unit 210 may be a PLC (Programmable Logic Controller) or an FPGA (Field Programmable Gate Array). The multiple compensation heaters 100 are provided in one-to-one correspondence with the multiple execution units 220, and each compensation heater 100 is connected to each execution unit 220 in one-to-one correspondence, thereby transmitting execution commands to the multiple compensation heaters 100 via the multiple execution units 220. Optionally, the execution unit 220 may include a PWM (Pulse Width Modulation) actuator, which is relatively low cost and has excellent noise resistance. More specifically, the PWM actuator may be a relay, and the execution unit 220 receives a PWM signal sent from the control unit 210 and controls the on-power of the corresponding compensation heater 100 by controlling its on-ratio. The control unit 210 then controls the corresponding compensation heaters 100 via the multiple execution units 220 to output the target power, thereby reducing the number of control units 210 to be installed, which on the one hand further reduces the overall cost of the electrostatic chuck apparatus and on the other hand reduces the difficulty of assembling the controller.

[0035] 5 , the electrostatic chuck apparatus according to the embodiment of the present disclosure may further include a filter 610 connected between each compensation heater 100 and the corresponding performance unit 220. The filter 610 is used to filter the RF environment between the electrostatic chuck apparatus and an external circuit to prevent adverse effects on the external circuit. The external circuit includes a power supply positive electrode and a power supply negative electrode, both of which are connected to the circuit of the electrostatic chuck apparatus to supply power to each compensation heater 100. Of course, the chucking electrode is also connected to the external circuit, and a power supply filtering box 620 is provided between the external power supply and the chucking electrode to provide filtering.

[0036] Based on any one of the electrostatic chuck devices according to the above embodiments, as shown in FIG. 7 , an embodiment of the present application further discloses a temperature control method that can be applied to any one of the electrostatic chuck devices according to the above embodiments, and controls the operating state of the electrostatic chuck device to match the temperatures at different positions on a wafer placed on the electrostatic chuck device and improve the process uniformity of the wafer.

[0037] The temperature control method includes a step S1 of establishing a correspondence between process steps and target compensation heaters, where the target compensation heaters are compensation heaters other than the compensation heaters corresponding to the positions of the extreme values ​​of the original process results among the plurality of compensation heaters when each process step is performed. The original process results are process results at positions corresponding to the plurality of compensation heaters on a wafer when each process step is performed while maintaining the heating layer and keeping each compensation heater off. Furthermore, for the extreme values, if the process results show a positive correlation with the temperature of the corresponding position on the wafer, the extreme value is a maximum value. Correspondingly, if the process results show a negative correlation with the temperature of the corresponding position on the wafer, the extreme value is a minimum value.

[0038] Specifically, during wafer processing, at least one process step must be performed on the wafer, and in any one process step, the process result of the wafer is correlated with the wafer temperature, and the process result may be positively or negatively correlated with the temperature. However, in any case, the temperature at any position on the wafer is necessarily correlated with the process result at that position. Therefore, by detecting the process results at multiple positions on the wafer, the temperature status of the corresponding position on the wafer can be obtained. The process result may be the etching rate of the wafer, etc., and of course, the process result may also be the deposition rate, etc., but is not limited thereto.

[0039] As described above, when a wafer is heated only by a heating layer, theoretically, the heating efficiency of the heating layer is the same for different positions on the wafer. However, due to various factors, there will still be positions on the wafer where the temperature varies. Furthermore, there will be at least one hottest position on the wafer, and this at least one position may correspond to and overlap with at least one of the compensation heaters in the electrostatic chuck device. That is, a compensation heater may be installed directly below the hottest position of a wafer placed on the electrostatic chuck device, or a compensation heater may not be installed at the position of the electrostatic chuck device corresponding to the hottest position of the wafer. Therefore, in the process of acquiring the wafer temperature (i.e., the process result), temperatures (or process results) at multiple positions on the wafer corresponding to the multiple compensation heaters can be measured. In this case, the temperature (or process result) of any one of the compensation heaters corresponding to the wafer position can be more intuitively acquired.

[0040] Of course, in the process of measuring the temperatures (or process results) at multiple positions on the wafer corresponding to the multiple compensation heaters, the heating layer needs to be kept on and each compensation heater needs to be kept off, thereby obtaining the original value of the process result when the wafer is subjected to the process step, i.e., obtaining multiple original process results that correspond one-to-one to the positions of the multiple compensation heaters.

[0041] During wafer processing, the temperatures at different positions on the wafer must be consistent to ensure high uniformity in the wafer process results. Because the compensation heater only increases the temperature at the corresponding position on the wafer, when the compensation heater is used to compensate for the wafer temperature, it can only operate the compensation heater at a relatively low temperature position to compensate for the temperature at that low temperature position.

[0042] As described above, the above-mentioned multiple original process results must have at least one extreme value, and the process results have a positive correlation with temperature. Take the example of a case where the above-mentioned multiple original process results have at least one maximum value. For example, there are six original process results and one maximum value. It is clear that when performing this process step, compensation heaters other than the compensation heater corresponding to the maximum value can be turned on, so that the temperature of the five positions on the wafer with low temperatures can be increased within a certain range through the action of the compensation heaters, and the difference between the temperatures of the five positions and the position corresponding to the maximum value can be reduced, thereby improving the process uniformity of the wafer.

[0043] In addition, to prevent the temperatures at the five positions from exceeding or significantly exceeding the temperature at the position corresponding to the maximum value due to the strong temperature compensation effect of the compensation heater, the heating power of the compensation heater can be relatively small. Furthermore, the heating power of the compensation heater can be appropriately determined according to information such as the difference in the process results of the wafer in the process step, thereby preventing the compensation temperature of the compensation heater from significantly exceeding the temperature at the position corresponding to the maximum value as much as possible and ensuring relatively high uniformity of the process results of the wafer.

[0044] Of course, if there are multiple process steps, the above process is performed for each process step to obtain the position of the compensation heater that needs to be turned on corresponding to the process step, and mark it as the target compensation heater corresponding to the process step, thereby forming a correspondence relationship between the process step and the target compensation heater.

[0045] Based on the above step S1, the temperature control method according to the embodiment of the present application further includes step S2 of obtaining the process step immediately before execution, controlling each main heater in the heating layer to be on, and controlling each target compensation heater corresponding to the process step immediately before execution to be on according to the correspondence relationship obtained in the above step.

[0046] As described above, a set of data having a corresponding relationship can be obtained in advance, and the relationship between any one of the process steps and the target compensation heater can be obtained based on the data, so that once the process step to be performed is determined, any one of the multiple compensation heaters can be selected as the target compensation heater based on the corresponding relationship. Based on this, when performing a process step, all main heaters in the heating layer and the target compensation heater corresponding to the process step immediately before the process step can be turned on to ensure that the process effect at any position on the wafer is relatively good, so that the temperature at any position on the wafer can be made as consistent as possible under the cooperation of the heating layer and the target compensation heater, thereby improving the uniformity of the wafer process results.

[0047] In the temperature control method according to the above embodiment, during a process step, unless the process result of the area of ​​the wafer corresponding to at least one compensation heater is an extreme value of the multiple original process results, the at least one compensation heater is controlled to be turned on when the process step is performed later. Therefore, when the process step is performed later, turning on the at least one compensation heater will cause the temperature of the area of ​​the wafer corresponding to a compensation heater to exceed the extreme value of the multiple original process results, resulting in poor wafer process uniformity.

[0048] Based on this, the above step S2 may include the steps of obtaining the process step immediately before execution, controlling each main heater in the heating layer to be turned on, and controlling each target compensation heater corresponding to the process step immediately before execution to be turned on at the target power according to the correspondence and the on-ratio. That is, in this embodiment, when a certain process step is performed, not only is the target compensation heater corresponding to the process step to be executed controlled based on the correspondence, but also the target compensation heater that needs to be turned on according to the on-ratio can be turned on at the target power, thereby further improving the control accuracy of each target compensation heater.

[0049] The on-ratio may be a value such as 0.1, 0.2, or 1.1, and can be selected according to actual circumstances, such as the correspondence between the temperature difference and the on-power, and is not limited thereto. The target power is correlated with the on-ratio and also with the compensation value. Specifically, the target power is the product of the on-ratio and the compensation value. The compensation value is the difference between the extreme value of the multiple original process results and the original process result corresponding to the target compensation heater. That is, the target power of the target compensation heater is directly correlated with the process result of the corresponding region of the wafer. In this case, the cooperation of the multiple target compensation heaters can bring the temperature of the region of the wafer that is smaller than the original maximum temperature closer to the maximum temperature. Even if the temperature of a certain position exceeds the original maximum temperature due to heating by the target compensation heater, because the target power of the target compensation heater is closely correlated with the original process result of the region corresponding to the target compensation heater and the original process result is directly correlated with the temperature, the temperature of the position will not significantly exceed the original maximum temperature after thermal compensation by the target compensation heater. This further ensures better temperature uniformity at each position on the wafer, thereby improving the uniformity of the wafer process result.

[0050] Considering that the wafer temperature is affected by various factors, in order to further improve the compensation accuracy of the compensation heater for the temperature of the corresponding position on the wafer, in another embodiment of the present application, optionally, the above step S2 obtains the process step just before execution, controls each main heater in the heating layer to be turned on, and controls each target compensation heater corresponding to the just before execution process step to be turned on with a target power according to the correspondence relationship, the compensation target value, and the influence function. That is, in the present application, the target power of each target compensation heater that needs to be turned on further is controlled with higher precision based on the influence function and the compensation target value, and the target compensation heater is operated with the target power to compensate the process result of the corresponding position until it corresponds to or is equal to the extreme value of the multiple original process results, thereby further improving the process uniformity of the wafer.

[0051] Of course, to achieve the above objective, the reliability of the influence function must be relatively high. Furthermore, the target compensation heaters are operated at multiple different on-powers, and the process results at the corresponding positions on the wafer when the target compensation heaters are operated at the corresponding on-powers are recorded. Each set of data includes the process results and the on-power. With the support of the multiple sets of data, a functional relationship, which is the influence function, can be obtained. The series of the influence function correlates with the number of data sets. Furthermore, at least two tests can be performed for each target compensation heater, so that the influence function of any one target compensation heater is at least a quadratic function, and the target power obtained based on the influence function is highly accurate. Specifically, the power of any one target compensation heater can be set to 10%, 50%, and 90%, and the process results Tn1, Tn2, and Tn3 at the positions corresponding to the target compensation heater are obtained, respectively, by quadratic function fitting. The influence function Pn=k1×T between the output power of the target compensation heater and the process results can be calculated. 2 +k2×T+k3 can be obtained. Then, when performing a corresponding process step, the target power of the target compensation heater that needs to be turned on can be obtained according to the compensation target value of the process result at the position corresponding to the target compensation heater.

[0052] As described above, during the process of performing a process step in the above temperature control method, when the corresponding target compensation heater is controlled to be on based on the correspondence relationship established in step S1, the process results at the positions corresponding to one or more target compensation heaters may exceed the extreme values ​​of the multiple original process results (specifically, be larger or smaller than the extreme values), resulting in new extreme values ​​appearing in the compensated process results and preventing the wafer process uniformity from being met. Based on this, before controlling the operation of the target compensation heater using the correspondence relationship established in step S1, the established correspondence relationship can be verified, and only if the verification result meets the requirements, the corresponding target compensation heater is controlled to be on based on the correspondence relationship according to the process step to be performed.

[0053] In detail, the above step S2 includes the steps of: before performing the process step immediately before execution, turning on each main heater in the heating layer, and turning on the corresponding target compensation heater based on the above correspondence; and, when the difference between any two of the process results at positions on the wafer corresponding to the multiple compensation heaters is smaller than a predetermined value, obtaining the process step immediately before execution, controlling to turn on each main heater in the heating layer, and controlling to turn on the target compensation heater corresponding to the process step immediately before execution according to the above correspondence.

[0054] When the above technical solution is adopted, when a process step is performed, the corresponding target compensation heater is turned on according to the correspondence, and the process results obtained at positions on the wafer corresponding to the multiple compensation heaters are verified in advance. Only when the uniformity of the multiple process results meets the requirements, when the corresponding process step is performed later, the corresponding target compensation heater is controlled to be turned on according to the above correspondence, and works in cooperation with the heating layer to provide a heating effect to the wafer placed on the electrostatic chuck device, making the temperature of any position on the wafer the same or approximately the same.

[0055] Correspondingly, when performing a process step, each main heater in the heating layer is turned on, and the corresponding target compensation heater is turned on based on the correspondence relationship. If the difference between any two of the process results at the positions on the wafer corresponding to the multiple compensation heaters is greater than a predetermined value, the above correspondence relationship may be inaccurate.

[0056] To solve the above situation, the target compensation heaters for which the difference between the compensated process result and the extreme value of the plurality of original process results is equal to or greater than the predetermined value may be controlled to be in an off state during the corresponding process step, thereby making the process result at that position smaller than the extreme value of the plurality of original process results, but improving the process uniformity of the wafer to a certain extent.

[0057] Alternatively, in the above embodiment, the on-power of the compensation heater may be proportionally controlled based on the extreme value and the compensation target value of the process result at the position corresponding to the compensation heater. Furthermore, in the above embodiment, the on-power of the compensation heater may be correspondingly controlled based on the influence function and the compensation target value of the process result at the position corresponding to the extreme value and the compensation heater. Of course, in the process of adopting these two alternative methods, when the target compensation heater is turned on with the corresponding target power, the difference between the process result at the position corresponding to one or more target compensation heaters and the extreme values ​​of the multiple original process results may be greater than the predetermined value. Based on this, various coefficients in the proportionality coefficients or influence functions in the above two alternative methods can be adjusted to obtain new proportionality coefficients or influence functions, thereby improving the accuracy of the above two alternative methods.

[0058] In any one of the above embodiments, a sampling operation for the process results at positions on the wafer corresponding to the multiple compensation heaters is involved. As shown in Figures 8 and 3, in actual application, the sampling points (i.e., temperature measurement points) of the sampling device for providing the sampling function may not correspond one-to-one to the positions of the multiple compensation heaters in the molded electrostatic chuck device. In order to ensure that the temperature compensation capability of the electrostatic chuck device is relatively strong, it is usually necessary to distribute the multiple compensation heaters as evenly as possible.

[0059] Based on this, in the process of acquiring the process result at a position corresponding to any one compensation heater on the wafer, if a sampling point in the sampling device exactly corresponds to that position, the sampling point can be used to perform sampling at that position. If none of the sampling points in the sampling device correspond to a position corresponding to a compensation heater, the process results of multiple positions around the position corresponding to the compensation heater can be collected and the process result at the position corresponding to the compensation heater can be calculated by interpolation, thereby reducing the difficulty of sampling.

[0060] Specifically, the process result at a location on the wafer corresponding to at least one compensation heater is an average of the process results at multiple other locations around the location on the wafer, the process result at the location on the wafer corresponding to the compensation heater is the process result to be detected, where the process result to be detected cannot be obtained by direct measurement, and the process results at the multiple other locations around the location are known process results, where the known process result can be obtained by direct measurement.

[0061] More specifically, as shown in FIG. 6 , six compensation heaters are installed in an electrostatic chuck apparatus. The center of the wafer is defined as the zero point of the X and Y axes. The coordinates of the compensation heater centers are (X1, Y1), (X2, Y2), ... (X6, Y6), respectively. In the process step, the process results of ten points are examined, with the coordinates of these ten points being (A1, B1), (A2, B2), ... (A10, B10), respectively. In this case, according to the above temperature control method, the original process results (C1, C2, ..., C10) of these ten process points when all the compensation heaters are off are first tested. Then, the process results of the ten points are linearly interpolated to calculate the process results of the wafer at the positions corresponding to the centers of the six compensation heaters. More specifically, the calculation steps are described below using the point (X1, Y1) indicated by the white circle in FIG. 9 as an example. The abscissas of the ten process points are A1-A10, respectively. X1 is between two of them, for example, between A2 and A3. The ordinates of the ten process points are B1-B10, respectively. Y1 is between two of them, for example, between B3 and B4. In this case, the results at X1 and Y1 are shown in FIG. 9. In FIG. 9, C1-C5 are known measured process result data, and the surroundings corresponding to (X1, Y1) are shown. The coordinates of the remaining three points other than (A3,B3) are (A2,B3), (A2,B4), and (A3,B4), respectively, and the process data of these three points are P1, P2, and P3, respectively. In this case, the calculations are P1=(C2+C3) / 2, P2=(P1+P3) / 2, and P3=(C3+C4) / 2, and the process data at (X1,Y1) is P=(P1+P2+P3+C3) / 4=(3×C2+22×C3+3×C4) / 16.

[0062] Then, find the extreme value of the process result from the above six process results (the extreme value is the value of the process result corresponding to the highest temperature position, not necessarily the maximum value of the actual value, because in some processes, the higher the temperature, the smaller the process result) and assume that the extreme value appears at the position corresponding to the first compensation heater. Calculate the differences between the process results and the extreme value at the positions corresponding to the remaining five compensation heaters, and denote them as PE1, PE2, ..., PE5. Since the compensation heaters can only perform temperature compensation, in the subsequent compensation, the first compensation heater is kept off, and the remaining five compensation heaters are turned on to perform temperature compensation for the corresponding positions. In the temperature control process, PE1-PE5 are used to calculate the influence function relationship Pn=k1×T for each of the above five compensation heaters. 2 +k2×T+k3 to obtain the output power T1-T5 of each of the remaining five compensation heaters, and send the power data to the control unit, which controls the PWM actuator to operate the corresponding compensation heater with the output power.

[0063] Then, the process results of the wafer are collected again to determine whether the above control method can meet the wafer uniformity. If the answer is YES, the electrostatic chuck device can be controlled by the above control method in the mass production process. If the answer is NO, a new influence function is obtained by taking the value again.

[0064] As shown in FIG. 10, the temperatures at multiple positions on the wafer (i.e., the positions of the temperature measurement points) were measured. After controlling the heating process of the electrostatic chuck device using the above control method, the temperature difference between different positions on the wafer (i.e., the temperatures at the temperature measurement points) was significantly reduced, indicating that the temperature uniformity of the wafer was significantly improved, and further ensuring that the process uniformity of the wafer was significantly improved.

[0065] In the above embodiments of the present application, the description focuses on the differences between each embodiment, and the different optimization features between each embodiment can be combined to form a more preferred embodiment, unless they are contradictory, and detailed descriptions are omitted here for the sake of brevity.

[0066] The above is merely an example of the present application and is not intended to limit the present application. Those skilled in the art can make various modifications and variations to the present application. Any modifications, equivalent replacements, improvements, etc. made without departing from the spirit and principles of the present application should be included in the scope of the claims of the present application.

Claims

1. A temperature control method applied to an electrostatic chuck device for mounting and heating a wafer, comprising: the insulating adsorption layer is provided with an adsorption electrode for adsorbing the wafer; the heating layer is provided with at least two main heaters for heating the wafer placed on the insulating adsorption layer; and the electrostatic chuck device further includes a controller, wherein the insulating adsorption layer is further provided with a plurality of compensation heaters, each of which is insulated from the adsorption electrode and electrically connected to the controller, and the controller is used to control on / off of each of the compensation heaters and to control power for each of the compensation heaters, Step S1: establishing a correspondence between process steps and target compensation heaters, wherein the target compensation heaters are the remaining compensation heaters other than the compensation heaters corresponding to positions of extreme values ​​of a plurality of original process results among the plurality of compensation heaters when each of the process steps is performed, the original process results are process results at positions corresponding to the plurality of compensation heaters on the wafer when each of the process steps is performed in a state where the at least two main heaters in the heating layer are kept on and each of the compensation heaters is kept off, and the extreme value is a maximum value when the process result shows a positive correlation with the temperature of the corresponding position on the wafer, and the extreme value is a minimum value when the process result shows a negative correlation with the temperature of the corresponding position on the wafer; and step S2 of acquiring a process step immediately before execution, controlling each of the main heaters in the heating layer to be on, and controlling each of the target compensation heaters corresponding to the process step immediately before execution to be on according to the correspondence relationship.

2. 2. The temperature control method of claim 1, wherein the insulating adsorption layer includes a first insulating sub-layer, a second insulating sub-layer, and a third insulating sub-layer arranged in this order from bottom to top, the adsorption electrode is arranged between the third insulating sub-layer and the second insulating sub-layer to form an adsorption sub-layer, and the compensation heaters are all arranged between the second insulating sub-layer and the first insulating sub-layer to form a compensation heating layer.

3. 3. The temperature control method according to claim 2, wherein the compensation heater includes a metal resistance heater formed by screen printing, and a cable of the compensation heater passes through the device base and the heating layer and is drawn out of the device base.

4. 2. The temperature control method according to claim 1, wherein the number of the compensation heaters is 10 or more and 100 or less.

5. 4. The temperature control method of claim 3, wherein the compensation heaters form a central compensation area and a plurality of annular compensation areas, the annular compensation areas being concentrically distributed and all positioned around the central compensation area with the center of the central compensation area as their center, and each annular compensation area includes a plurality of the compensation heaters, and the central compensation area includes one of the compensation heaters.

6. 2. The temperature control method according to claim 1, wherein the controller includes a control unit and a plurality of execution units connected to each other, each of the compensation heaters is connected to each of the execution units in a one-to-one correspondence, and the control unit controls the corresponding compensation heater to output a target power through the execution unit.

7. The temperature control method of claim 6 , wherein the effector includes a pulse width modulated actuator.

8. 7. The temperature control method according to claim 6, wherein the electrostatic chuck device further includes a filter, the filter being connected between each of the compensation heaters and the corresponding one of the performance portions.

9. The S2 is 9. The temperature control method according to claim 1, further comprising the steps of: acquiring a process step immediately before execution; controlling each of the main heaters in the heating layer to be on; and controlling each of the target compensation heaters corresponding to the process step immediately before execution to be on with a target power according to the correspondence and the on-ratio; wherein differences between the extreme values ​​of the plurality of original process results and the original process results corresponding to each of the target compensation heaters are all compensation target values, and the target power is the product of the on-ratio and the compensation target value.

10. The S2 is 9. The temperature control method of claim 1, further comprising the steps of: acquiring a process step immediately before execution; controlling each of the main heaters in the heating layer to be on; and controlling each of the target compensation heaters corresponding to the process step immediately before execution to be on at a target power according to the correspondence relationship, a compensation object value, and an influence function, wherein the compensation object value is a difference between the extreme value of a plurality of the original process results and the original process result corresponding to each of the target compensation heaters; and the influence function is a functional relationship formed between the on-power and the process result at a position on the wafer corresponding to the target compensation heater when each of the target compensation heaters operates at a plurality of different on-powers.

11. The S2 is before performing a process step immediately before execution, turning on each of the main heaters in the heating layer and turning on a corresponding target compensation heater based on the correspondence; and when a difference between any two of the process results at positions on the wafer corresponding to the compensation heaters is smaller than a predetermined value, acquiring a process step immediately before execution, controlling each of the main heaters in the heating layer to be on, and controlling each of the target compensation heaters corresponding to the process step immediately before execution to be on in accordance with the correspondence.

12. A temperature control method according to any one of claims 1 to 8, characterized in that the process result at a position on the wafer corresponding to at least one of the compensation heaters is an average value of the process results at multiple other positions around the position on the wafer.

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