Wafer temperature control device, control method for wafer temperature control device, and program for wafer temperature control device

Abstract

In order to provide a wafer temperature control device which can estimate, with sufficient accuracy, a wafer temperature even when a cooling operation amount input to a cooler is changed, and which can control the wafer temperature at a target temperature, this wafer temperature control device comprises: a heater 1 which heats a wafer W according to an input heating operation amount; a cooler 2 which cools the wafer W according to an input cooling operation amount; a vicinity temperature measurer 3 which measures the vicinity temperature of the wafer W; a temperature estimation observer 4 which estimates the wafer temperature on the basis of the vicinity temperature measured by the vicinity temperature measurer 3 and a cooling operation amount input to the cooler 2 or a cooling amount output by the cooler 2; and a temperature controller 5 which controls the cooling operation amount so that the temperature deviation between a setting temperature and the estimated wafer temperature becomes small.

Description

Wafer temperature control device, control method for wafer temperature control device, and program for wafer temperature control device

[0001] The present invention relates to a wafer temperature control device for controlling the temperature of a wafer.

[0002] In a semiconductor manufacturing process, among various processes performed on a wafer housed in a chamber, there is a process that controls the temperature of the wafer to a predetermined target temperature.

[0003] For example, a wafer temperature control device described in Patent Document 1 includes a stage equipped with a cooling mechanism for cooling a wafer placed in a chamber and a heating mechanism for heating the wafer. The stage is made of a light-transmitting material and has a coolant flow path formed therein through which a coolant flows.

[0004] The cooling mechanism includes a chiller connected to a refrigerant flow path inside the stage and outside the stage, and the supply of refrigerant is switched by controlling, for example, an on / off valve. Meanwhile, the heating mechanism includes multiple LEDs mounted on the side of the stage opposite the wafer-mounting surface. Light emitted from each LED is configured to pass through the stage before irradiating the backside of the wafer. The amount of light emitted from each LED is controlled so that the wafer temperature reaches a target temperature.

[0005] Furthermore, due to various technical constraints, it is difficult to actually measure the temperature of the wafer itself housed in the chamber. For this reason, in Patent Document 1, a temperature sensor is installed in the stage to measure the temperature near the wafer, and an observer estimates the temperature of the electronic device formed on the wafer. Then, a current value corresponding to the temperature of the electronic device estimated by the observer is supplied to the LED, thereby controlling the amount of heat.

[0006] In processes using plasma, the wafer temperature rises because gas molecules ionized by the plasma collide with the wafer. For this reason, a method is used to cool the wafer by supplying gas such as He directly to the backside of the wafer. There are also processes that only cool the wafer without heating.

[0007] However, in such applications, the observer shown in Patent Document 1 does not use the cooling amount or the cooling operation amount as input parameters, and therefore it is difficult to estimate the wafer temperature with sufficient accuracy and control the wafer temperature to a constant target temperature.

[0008] Japanese Patent Application Laid-Open No. 2021-19066

[0009] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a wafer temperature control device that can estimate the wafer temperature with sufficient accuracy and control the wafer temperature to a target temperature even when the cooling operation amount input to the cooler is changed.

[0010] That is, the wafer temperature control device according to the present invention is characterized by comprising a heater that heats a wafer in accordance with an input heating operation amount, a cooler that cools the wafer in accordance with an input cooling operation amount, a proximity temperature measuring device that measures the temperature in the vicinity of the wafer, a temperature estimation observer that estimates the wafer temperature based on the proximity temperature measured by the proximity temperature measuring device and the cooling operation amount input to the cooler or the cooling amount output by the cooler, and a temperature controller that controls the cooling operation amount so that the temperature deviation between a set temperature and the estimated wafer temperature is small.

[0011] Furthermore, a wafer temperature control method according to the present invention is a control method for a wafer temperature control device equipped with a heater that heats a wafer in accordance with an input heating operation amount and a cooler that cools the wafer in accordance with an input cooling operation amount, and is characterized by comprising the steps of measuring a temperature in the vicinity of the wafer, estimating a wafer temperature based on the vicinity temperature measured by the proximity temperature measuring device and the cooling operation amount input to the cooler or the cooling amount output by the cooler, and controlling the cooling operation amount so as to reduce the temperature deviation between a set temperature and the estimated wafer temperature.

[0012] With this arrangement, even when the cooling operation amount is changed, the wafer temperature can be accurately estimated based on the nearby temperature, and as a result, even if the wafer temperature cannot be actually measured, the wafer temperature can be maintained at the set temperature.

[0013] In order to correct the estimation error of the wafer temperature due to a deviation in the initial temperature and improve the estimation accuracy of the wafer temperature, the temperature estimation observer may include a temperature estimation model which is a state space model with the wafer temperature and the nearby temperature as output variables, a nearby temperature output unit which outputs the nearby temperature estimated based on the temperature estimation model, a wafer temperature output unit which outputs the wafer temperature estimated based on the temperature estimation model, and an observer gain, and may be configured so that the value obtained by multiplying the deviation between the estimated value of the nearby temperature output from the nearby temperature output unit and the measured value of the nearby temperature output from the nearby temperature measuring device by the observer gain is fed back into the temperature estimation model.

[0014] For example, even if a disturbance is input into the wafer temperature control device, in order to be able to correct the influence of the disturbance that causes the estimated wafer temperature to remain deviated from the actual temperature and to further increase the robustness of the control system, the temperature estimation observer may further include an observer integrator that integrates the deviation between the estimated value of the nearby temperature output from the nearby temperature output unit and the measured value of the nearby temperature output from the nearby temperature measuring device, and the value obtained by multiplying the integrated value output from the observer integrator by the observer gain may be fed back into the temperature estimation model.

[0015] For example, a suitable configuration for heating or cooling the wafer contained in the chamber is one that further includes a plate on which the wafer is placed, the heater configured to heat the plate, and the cooler configured to cool the plate.

[0016] A specific embodiment of the cooler includes a coolant flow path and a coolant control unit that controls the flow of coolant circulating within the coolant flow path, and the cooling operation amount is the cooling amount of the wafer or a target coolant flow rate.

[0017] In order to accurately simulate the amount of cooling of the wafer by the cooler and improve the accuracy of estimating the final wafer temperature, the temperature estimation model should be a state space model with the amount of heating by the heater and the amount of cooling by the cooler as input variables, and the wafer temperature and the nearby temperature as state variables, and the cooling amount should be calculated based on the difference between the wafer temperature and the nearby temperature and the heat transfer coefficient between the wafer and the plate.

[0018] To accurately simulate the transfer of heat from the wafer to the plate, a heat transfer gas is supplied between the wafer and the plate at a predetermined pressure, and the heat transfer coefficient is set based on the pressure of the heat transfer gas.

[0019] In order to simplify the control input and, for example, to easily maintain the temperature of the wafer at a constant high value, the heating operation amount may be set to a constant value.

[0020] In order to control not only the wafer temperature, which is the final control target, but also each state variable to an appropriate value so that the wafer temperature continues to match the set temperature at each time, the temperature controller should be configured to feed back the state variable vector estimated by the temperature estimation observer.

[0021] For example, in order to enable the temperature estimation observer to estimate the wafer temperature taking into account the effects of heating of the wafer by gas present in the chamber or heat radiation from the wafer, and to further improve the estimation accuracy, it is sufficient to further include a gas temperature measuring device that measures the temperature of the gas present in the vicinity above the wafer, and to configure the temperature estimation observer to estimate the wafer temperature based on the vicinity temperature measured by the vicinity temperature measuring device, the cooling operation amount input to the cooler or the cooling amount output by the cooler, and the gas temperature measured by the gas temperature measuring device.

[0022] In order to achieve temperature control performance equivalent to that of the wafer temperature control device of the present invention by updating a program in an existing wafer temperature control device, it is sufficient to use a program used in a wafer temperature control device equipped with a heater that heats the wafer in accordance with an input heating operation amount and a cooler that cools the wafer in accordance with an input cooling operation amount, the program for a wafer temperature control device being characterized in that it causes a computer to perform the functions of: a proximity temperature measuring device that measures the temperature in the vicinity of the wafer; a temperature estimation observer that estimates the wafer temperature based on the proximity temperature measured by the proximity temperature measuring device and the cooling operation amount input to the cooler or the cooling amount output by the cooler; and a temperature controller that controls the cooling operation amount so as to reduce the temperature deviation between the set temperature and the estimated wafer temperature.

[0023] The program for the wafer temperature control device may be distributed electronically or may be recorded on a program recording medium such as a CD, DVD, or flash memory.

[0024] In this way, the wafer temperature control device according to the present invention can accurately estimate the wafer temperature, which is difficult to measure directly, even when the cooling operation amount is changed. Furthermore, since the cooling operation amount is controlled based on the temperature deviation between the accurately estimated wafer temperature and the set temperature, it is possible to improve the control accuracy of the wafer temperature, for example, compared to conventional methods.

[0025] 1 is a schematic perspective view of a wafer temperature control device according to a first embodiment of the present invention; FIG. 2 is a schematic configuration diagram of a wafer temperature control device according to the first embodiment; FIG. 3 is a schematic diagram of a wafer temperature control device according to the first embodiment expressed by a state equation; FIG. 4 is a functional block diagram of a wafer temperature control device according to the first embodiment; FIG. 5 is a graph showing the relationship between the pressure of a heat transfer gas supplied between a wafer and a plate and the heat transfer coefficient between the wafer and the plate according to the first embodiment; FIG. 6 is a schematic diagram explaining modeling of a wafer temperature control device according to the first embodiment; FIG. 7 is a simulation result of the operation of a wafer temperature control device according to the first embodiment; FIG. 8 is a schematic diagram of a wafer temperature control device according to a second embodiment of the present invention expressed by a state equation; FIG. 9 is a simulation result of the wafer temperature output from the temperature estimation observer according to the second embodiment when a disturbance is input; FIG. 10 is a schematic configuration diagram of a wafer temperature control device according to a third embodiment of the present invention.

[0026] A wafer temperature control apparatus 100 according to a first embodiment of the present invention will be described with reference to FIGS.

[0027] The wafer temperature control device 100 of this embodiment is configured to electrostatically chuck the backside of a wafer W in, for example, a vacuum chamber. As shown in Fig. 1, the wafer temperature control device 100 includes a substantially disk-shaped suction plate AP on whose upper surface the wafer W is placed, and a cooler 2 provided in contact with the lower surface of the suction plate AP.

[0028] The suction plate AP has a suction surface on its front surface, and a gas flow groove AP1 is formed on this suction surface to supply a heat transfer gas between the suction plate AP and the backside of the wafer W. Helium gas, for example, is supplied at a predetermined pressure to the gas flow groove AP1 through vertical through-holes AP2 formed along the central axes of the suction plate AP and the cooler 2. An electrostatic electrode (not shown) is embedded within the suction plate AP to generate an electrostatic force between the suction plate AP and the wafer W. A plurality of heater electrodes (not shown) are embedded within the suction plate AP to heat the suction plate AP, and these heaters constitute the heater 1. In this embodiment, heating amounts corresponding to heating operation amounts set by the user are independently output to heating control units (not shown) connected to each heater electrode. In this embodiment, the heating amounts can be made different between the central and peripheral portions of the suction plate AP. Furthermore, the heating amounts can also be made different between a large, roughly C-shaped region on the periphery and the remaining small region. In other words, three heating regions are defined on the suction plate AP.

[0029] The cooler 2 includes a generally circular base plate BP in contact with the underside of the suction plate AP, a coolant flow path 21 formed within the base plate BP, and a coolant control unit that controls the flow of coolant through the coolant flow path 21. The coolant flow path 21 is spiral-shaped within the base plate BP, forming three cooling regions on the surface of the base plate BP corresponding to the three heating regions of the suction plate AP. The coolant flows into and out of the coolant flow path 21 within the base plate BP via a coolant inlet flow path 22 or a coolant outlet flow path 23 formed along the axial direction around the vertical through-hole AP2 through which helium gas flows. The coolant, which flows through the base plate BP to cool the base plate BP, suction plate AP, and wafer W and whose temperature rises, is re-cooled by a chiller (not shown) provided outside the base plate BP and circulates through both. The coolant control unit controls the flow of coolant through the coolant flow path 21 in response to an input cooling control amount. In this embodiment, the cooling operation amount is a target cooling amount, which is set as a heat amount, and the refrigerant control unit changes the opening of a control valve (not shown) that controls the refrigerant flow rate so as to achieve the target cooling amount.

[0030] In addition, the temperature is measured on the back side of the base plate BP by an infrared temperature sensor, which is a proximity temperature measuring device 3 for measuring the temperature near the wafer W. Here, the temperature measured by the infrared temperature sensor is the temperature of the base plate BP, not the temperature of the wafer W itself. Furthermore, since it is undesirable for components other than the wafer W to be placed in the vacuum atmosphere inside the vacuum chamber during various processes, the temperature of the wafer W inside the vacuum chamber is not measured directly. In this specification, proximity temperature refers to, for example, the temperature of a component or space within a predetermined distance from the wafer W, and includes temperatures for which a temperature model showing the relationship between the wafer temperature and proximity temperature can be constructed. Alternatively, proximity temperature may include the temperature of a component to which heat may be conducted or transferred between the wafer W and the component by at least one of conduction, convection, and radiation. More precisely, proximity temperature can also be defined as the temperature of a component in direct contact with the wafer W, the space or gas at the interface with the wafer W, or a component present across a gap of several microns from the wafer W.

[0031] Furthermore, the wafer temperature control device 100 further includes a control device COM, located, for example, outside the vacuum chamber, that controls the operation of at least the heater 1 and the cooler 2. The control device COM is a so-called computer equipped with a CPU, memory, A / D converter, D / A converter, and various input / output devices. The wafer temperature control device program stored in the memory is executed, and the various devices cooperate to form a wafer temperature control system as shown in FIGS. 2 to 4.

[0032] First, the wafer temperature control system of this embodiment will be outlined with reference to FIG.

[0033] In this embodiment, a fixed power is supplied to each heater electrode constituting the heater 1 regardless of the estimated wafer temperature or nearby temperature. That is, the heating operation amount is fixed during operation, and the heating amount per unit time is controlled to be constant. In contrast, the cooling operation amount input to the cooler 2 is successively changed based on the estimated wafer temperature or the actually measured nearby temperature. More specifically, the temperature estimation observer 4 is used to estimate the wafer temperature, which cannot be measured directly, based on the nearby temperature measured by the infrared temperature sensor. Furthermore, the estimated wafer temperature and each state variable are fed back, and the cooler 2 is controlled so that the wafer temperature follows the set temperature.

[0034] A block diagram of a state space representation of the wafer temperature control system shown in Figure 2 is shown in Figure 3. Figure 4 is a functional block diagram detailing the components for realizing each function. That is, the controlled object in this embodiment is a heat conduction and heat transfer system consisting of the wafer W and the suction plate AP. The wafer temperature control device 100 functions as at least a temperature estimation observer 4 that simulates the thermal behavior of the system and estimates the temperature of the wafer W, which cannot be directly measured, and a temperature controller 5 that feedback-controls the cooler 2 based on the estimated wafer temperature and various state variables calculated by the temperature estimation observer 4.

[0035] 3 , the temperature estimation observer 4 is configured to simulate the characteristics of the controlled object and output estimated values ​​of the wafer temperature and the nearby temperature based on the nearby temperature measured by the nearby temperature measuring device 3 and the cooling amount output by the cooler 2. More specifically, the temperature estimation observer 4 includes a temperature estimation model 41, which is a state space model with the wafer temperature and the nearby temperature as output variables, a nearby temperature output unit 43 that outputs the nearby temperature estimated based on the temperature estimation model 41, a wafer temperature output unit 42 that outputs the wafer temperature estimated based on the temperature estimation model 41, and an observer gain 44. The temperature estimation observer 4 is also configured so that a value obtained by multiplying the deviation between the nearby temperature estimate output from the nearby temperature output unit 43 and the nearby temperature measurement output from the nearby temperature measuring device 3 by the observer gain 44 is fed back into the temperature estimation model 41.

[0036] The temperature estimation model 41 is a model of, for example, heat conduction relating to the suction plate AP and wafer W themselves, and heat transfer between the suction plate AP and wafer W. As shown in Figures 2, 3, and 4, the controlled object can only measure the temperature of the suction plate AP, i.e., the vicinity temperature, and therefore the controlled object cannot output the wafer temperature into the control loop. In contrast, the temperature estimation observer 4 can estimate the wafer temperature by calculation based on the temperature estimation model 41 and output it into the control loop. The input variable vector u(t) of the temperature estimation model 41 in this embodiment is the cooling amount -q, which is the amount of heat removed from the wafer W and output from the cooler 2. ｇｉ The subscript i indicates whether the parameter belongs to the region set on the suction plate AP or the wafer W, and this also applies to the following explanation. In this system, the amount of heat q output from the heater 1 and applied to the wafer W is ｚｉ and are input as the input variable vector uheat. ｚｉ In this embodiment, the heating operation amount is fixed, so it is treated as a fixed value. ｇｉis calculated sequentially by the cooling amount calculation unit 6. Specifically, the cooling amount calculation unit 6 determines the heat transfer coefficient h between the wafer W and the suction plate AP based on a model of the heat transfer coefficient h, which has variables such as the pressure p of the helium gas and the distance d between the wafer W and the suction plate AP, as shown in the graph of FIG. 5. Furthermore, the cooling amount calculation unit 6 of this embodiment calculates the cooling amount -q by multiplying the difference between the set temperature and the temperature in the vicinity of the wafer W by the calculated heat transfer coefficient h. ｇｉ Here, the cooling amount −q ｇｉ is dependent on the pressure and flow rate of the helium gas, and the temperature difference between the gas and the wafer, and has complex characteristics that include interactions and nonlinearity due to temperature changes. In this embodiment, rather than modeling such complex phenomena as they are, a fixed value is derived for the temperature of the wafer W used in the cooling amount calculation unit 6 at the set temperature, and an approximate function is derived near that temperature, and the cooling amount -q ｇｉ In this way, the control system is simplified to reduce the calculation load, and the wafer temperature can be controlled with the required accuracy. ｇｉ is a function of the pressure p of helium gas -q ｇｉ For example, if there is sufficient computing power, the difference Δt between the wafer temperature and the temperature (nearby temperature) of the suction plate AP is calculated from the output of the temperature controller 5, and the cooling amount −q is calculated by multiplying Δt by the determined heat transfer coefficient h. ｇｉ may be configured to calculate

[0037] 3 and 4, the output variable vector y(t) is the wafer temperature T ｗｉ and the nearby temperature T ｐｉ The state variable vector x(t) includes the wafer temperature T ｗｉ , the temperature of the adsorption plate AP, which is the nearby temperature T ｐｉ and as state variables.

[0038] Then, when the state matrix is ​​A, the input matrices are B and B2, and the output matrices are Cr and C, the temperature estimation model 41 is defined by a state equation d / dt(x(t))=Ax+Bu+B2uheat and an output equation y=Crx, w=Cx as shown in Fig. 6. Here, A, B, B2, Cr, and C may be determined based on a heat conduction equation or a relational expression for heat transfer, or each element of each matrix may be determined based on an experiment or the like. 6 shows the correspondence between each row of the state matrix A and the actual system when a peripheral C-shaped region W1, a central region W2, and a peripheral fan-shaped region W3 are set on the wafer W, and a contact C-shaped region P1 in contact with the peripheral C-shaped region W1 of the wafer W, a contact central region P2 in contact with the central region W2 of the wafer W, a contact fan-shaped region P3 in contact with the peripheral fan-shaped region W3 of the wafer W, a non-contact C-shaped region P4 outside the wafer W and not in contact with the wafer W, a non-contact fan-shaped region P5 outside the wafer W and not in contact with the wafer W, and a protruding region P6 protruding further outward from the non-contact fan-shaped region P5. The elements of each row of the state matrix A are set to values ​​calculated based on, for example, a thermal conductivity coefficient that determines the heat transfer characteristics between the wafer W and the suction plate AP.

[0039] Furthermore, the input matrix B defines the cooling characteristics of each region of the wafer W by the helium gas described above. The input matrix B2 defines the heating characteristics by the heater electrodes. In this embodiment, a portion of the state variable vector x(t) is extracted as the output variable vector, so the output matrices Cr and C are defined by only a zero matrix and a unit matrix. Furthermore, the state variable vector x(t) is fed back to the temperature controller 5.

[0040] The wafer temperature output unit 42 extracts only the elements corresponding to the wafer temperature from the output of the temperature estimation model 41 and outputs them to the temperature controller 5. For example, the wafer temperature output unit 42 corresponds to an output matrix C.

[0041] The neighborhood temperature output unit 43 extracts and outputs only the elements corresponding to the neighborhood temperature from the output of the temperature estimation model 41. The deviation between the output estimated value of the neighborhood temperature and the actual measured value of the neighborhood temperature output from the neighborhood temperature measuring device 3 is calculated and input to the observer gain 44. In this embodiment, the neighborhood temperature output unit 43 corresponds to the output matrix Cr.

[0042] The temperature controller 5 performs an integral operation by multiplying the temperature deviation between the wafer temperature estimated by the temperature estimation observer 4 and the set temperature by a gain K. The temperature controller 5 also calculates the deviation between the calculated integral value and a value obtained by multiplying the state variable vector x(t) by a predetermined state feedback gain F, and inputs this deviation to the cooler 2 as the cooling operation amount.

[0043] 7 shows the results of a simulation of the operation of the wafer temperature control device 100 configured as above, when the set temperature is set to 100° C. It can be seen that the wafer temperature control device 100 of this embodiment can control the temperatures of each region of the wafer W to the set temperature of 100° C. with approximately the same first-order lag characteristics, based on the wafer temperature estimated by the temperature estimation observer 4.

[0044] In this way, according to the wafer temperature control device 100 of this embodiment, the wafer temperature, which cannot be actually measured, is estimated by the temperature estimation observer 4, and by feeding back the estimated value of the wafer temperature and other state variables, it is possible to maintain the wafer temperature, which cannot be actually measured, at a set temperature.

[0045] Furthermore, since the output of the heater 1 is kept constant and the output of the cooler 2 is controlled by temperature feedback control and state feedback control, even when it is desired to maintain the wafer temperature at a high temperature such as 100°C, high-precision control can be achieved with almost no overshooting or the like.

[0046] Next, a wafer temperature control apparatus 100 according to a second embodiment of the present invention will be described with reference to Fig. 8. Note that parts corresponding to those described in the first embodiment will be denoted by the same reference numerals.

[0047] The wafer temperature control device 100 of the second embodiment takes into consideration the influence on the temperature estimation observer 4 when a disturbance d is input to the system. The temperature estimation observer 4 of the wafer temperature control device 100 of the second embodiment differs from that of the first embodiment in that it includes an observer integrator 45. More specifically, the temperature estimation observer 4 is configured so that the deviation between the estimated value of the nearby temperature and the measured value of the nearby temperature measuring device 3 is fed back to the temperature estimation model 41, and in parallel, the integral value of the deviation is also fed back to the temperature estimation model 41.

[0048] That is, the temperature estimation observer 4 includes a first feedback loop that feeds back to the temperature estimation model 41 a value obtained by multiplying the deviation between the estimated value and the measured value of the neighboring temperature by a proportional observer gain 441, and a second feedback loop that integrates the deviation between the estimated value and the measured value of the neighboring temperature in an observer integrator 45, multiplies the integrated value by an integral observer gain 442, and feeds back to the temperature estimation model 41. Here, the proportional observer gain 441 and the integral observer gain 442 correspond to the observer gain 44 in the first embodiment.

[0049] Next, FIG. 9B shows the results of a simulation of the wafer temperature estimation by the temperature estimation observer 4 of the second embodiment when a periodic disturbance d occurs as shown in FIG. 9A. Even when a periodic disturbance is input while the wafer temperature is being changed from 25° C. to 100° C. and maintained at 100° C., the estimated value and control result of the wafer temperature can be converged to the set temperature so as to cancel out the disturbance. In other words, without the observer integrator 45, when a disturbance occurs, the wafer temperature estimated by the temperature estimation observer 4 may continue to deviate by a certain amount from the actual wafer temperature. However, the second embodiment can eliminate such estimation errors, making it possible to ultimately estimate the actual wafer temperature even when the disturbance d is input.

[0050] Next, a wafer temperature control apparatus 100 according to a third embodiment of the present invention will be described with reference to Fig. 10. Note that parts corresponding to those described in the first embodiment will be denoted by the same reference numerals.

[0051] The wafer temperature control device 100 of the third embodiment further includes a gas temperature measuring device GT that measures the temperature of the gas present in the vicinity above the wafer W in the chamber, and the temperature estimation observer is configured to estimate the wafer temperature using not only the vicinity temperature measured by the radiation thermometer at the suction plate AP as an actual measurement value, but also the gas temperature measured by the gas temperature measuring device GT. Here, the gas temperature measuring device GT is, for example, an absorption spectrometer configured to measure the gas temperature based on the absorbance of laser light passing directly above the wafer W in the faceplate direction.

[0052] In the wafer temperature control device 100 of the third embodiment, the state vector x used in the temperature estimation model can include not only the wafer temperature and the temperature in the vicinity of the wafer, but also the gas temperature. Furthermore, the state vector x of the state equation described in the first embodiment only includes the gas temperature as a component, and other matrices and vectors can be treated in the same manner. The wafer temperature estimated based on such a state equation can be estimated with improved accuracy by the amount of information on the actually measured temperatures, thereby further improving the accuracy of wafer temperature control.

[0053] Other embodiments will be described.

[0054] The heater is controlled to have a constant output, but the heating operation amount of the heater may also be changed by output feedback control or state feedback control.

[0055] The temperature estimation observer may be configured as a Kalman filter in consideration of the influence of disturbances. Note that various existing methods may be used to set a Kalman gain instead of the observer gain.

[0056] The method for calculating the cooling amount used as an input variable is not limited to the modeling method described above. For example, the calculation may be performed as an approximate value assuming that the temperature difference between the wafer and the suction plate is a constant value.

[0057] The configuration of the cooler or heater is not limited to those described above. For example, the cooler may be configured using a Peltier element, and the heater is not limited to a heater electrode but may be configured to heat the wafer by irradiating it with light.

[0058] The heating or cooling regions of the wafer and suction plate are not limited to three separate regions, but may be divided into more regions or into two regions. Alternatively, the wafer or suction plate as a whole may be treated as a single temperature without any regions. Furthermore, the suction plate may simply be a plate on which the wafer is placed, without any suction function.

[0059] The locations measured by the proximity temperature measuring device are not limited to the locations described above, and may be other locations. In other words, any temperature that appears to have some correlation or relationship with the wafer temperature may be measured as the proximity temperature. Furthermore, the temperature controller is not limited to an infrared temperature sensor, and may be, for example, a thermocouple or the like provided within the plate.

[0060] In the second embodiment, the deviation between the measured and estimated values ​​of the nearby temperature was fed back to the temperature estimation model along with the integral value of the deviation, but for example, only the integral value of the deviation may be fed back to the temperature estimation model.

[0061] In addition, various modifications and combinations of the embodiments may be made as long as they do not go against the spirit of the present invention.

[0062] According to the present invention, it is possible to provide a wafer temperature control device that can accurately estimate the wafer temperature, which is difficult to measure directly, even when the cooling operation amount is changed, and that can improve the control accuracy of the wafer temperature compared to conventional devices.

[0063] 100: Wafer temperature control device 1: Heater 2: Cooler 21: Coolant flow path 3: Proximal temperature measuring device 4: Temperature estimation observer 5: Temperature controller 41: Temperature estimation model 42: Wafer temperature output section 43: Proximal temperature output section 44: Observer gain AP: Adsorption plate BP: Base plate

Claims

1. a heater for heating the wafer in accordance with an input heating operation amount; a cooler that cools the wafer in accordance with an input cooling operation amount; a proximity temperature measuring device for measuring a proximity temperature of the wafer; a temperature estimation observer that estimates a wafer temperature based on the vicinity temperature measured by the vicinity temperature measuring device and a cooling operation amount input to the cooler or a cooling amount output by the cooler; a temperature controller that controls the cooling operation amount so as to reduce a temperature deviation between a set temperature and the estimated wafer temperature.

2. The temperature estimation observer a temperature estimation model which is a state space model having the wafer temperature and the vicinity temperature as output variables; a vicinity temperature output unit that outputs the vicinity temperature estimated based on the temperature estimation model; a wafer temperature output unit that outputs the wafer temperature estimated based on the temperature estimation model; an observer gain; 2. A wafer temperature control device as described in claim 1, configured so that the deviation between the estimated value of the nearby temperature output from the nearby temperature output unit and the measured value of the nearby temperature output from the nearby temperature measuring device, or a value calculated from the deviation, multiplied by the observer gain, is fed back into the temperature estimation model.

3. The temperature estimation observer The method further includes an observer integrator that integrates a deviation between the estimated value of the neighborhood temperature output from the neighborhood temperature output unit and the measured value of the neighborhood temperature output from the neighborhood temperature measuring device, 3. The wafer temperature control apparatus according to claim 2, wherein a value obtained by multiplying an integral value output from said observer integrator by said observer gain is fed back to said temperature estimation model.

4. Further comprising a plate on which the wafer is placed, the heater is configured to heat the plate; The apparatus of claim 2 , wherein the cooler is configured to cool the plate.

5. The cooler is A refrigerant flow path; a refrigerant control unit that controls a flow of the refrigerant circulating through the refrigerant flow path, 5. The wafer temperature control apparatus according to claim 4, wherein the cooling operation amount is a cooling amount of the wafer or a target coolant flow rate.

6. the temperature estimation model is a state space model having an amount of heating by the heater and an amount of cooling by the cooler as input variables, and having the wafer temperature and the vicinity temperature as state variables, 5. The wafer temperature control apparatus according to claim 4, wherein the cooling amount is calculated based on a difference between the wafer temperature and the vicinity temperature and a heat transfer coefficient between the wafer and the plate.

7. A heat transfer gas is supplied between the wafer and the plate at a predetermined pressure; 7. The apparatus of claim 6, wherein the heat transfer coefficient is calculated based on a pressure of the heat transfer gas.

8. 4. The wafer temperature control apparatus according to claim 1, wherein the heating operation amount is set to a constant value.

9. 4. The wafer temperature control apparatus according to claim 1, wherein the temperature controller is configured so that a state variable vector estimated by the temperature estimation observer is fed back.

10. a gas temperature measuring device for measuring a temperature of a gas present in the vicinity above the wafer; 4. A wafer temperature control device as described in any one of claims 1 to 3, wherein the temperature estimation observer is configured to estimate the wafer temperature based on the nearby temperature measured by the nearby temperature measuring device, the cooling operation amount input to the cooler or the cooling amount output by the cooler, and the gas temperature measured by the gas temperature measuring device.

11. A method for controlling a wafer temperature control device including a heater for heating a wafer in accordance with an input heating operation amount and a cooler for cooling the wafer in accordance with an input cooling operation amount, comprising the steps of: Measuring a temperature adjacent the wafer; estimating a wafer temperature based on the vicinity temperature and a cooling operation amount input to the cooler or a cooling amount output by the cooler; and controlling the cooling operation amount so that a temperature deviation between a set temperature and the estimated wafer temperature becomes small.

12. A program used in a wafer temperature control device including a heater for heating a wafer in accordance with an input heating operation amount and a cooler for cooling the wafer in accordance with an input cooling operation amount, a proximity temperature measuring device for measuring a proximity temperature of the wafer; a temperature estimation observer that estimates a wafer temperature based on the vicinity temperature measured by the vicinity temperature measuring device and a cooling operation amount input to the cooler or a cooling amount output by the cooler; A wafer temperature control device comprising: a temperature controller that controls the amount of cooling operation so as to reduce the temperature deviation between a set temperature and the estimated wafer temperature; and a program for causing a computer to function as such a temperature controller.