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

Abstract

To control a wafer temperature to a target temperature by estimating the wafer temperature with sufficient accuracy in a device controlling the temperature of a wafer by regulating a pressure of a heat transfer gas.SOLUTION: In a wafer temperature control device 100, a wafer W is mounted on a plate 2 of which the temperature is adjusted, and a temperature of the wafer W is controlled by supplying a heat transfer gas between the plate 2 and the wafer W. The wafer temperature control device comprises: a pressure regulator 43 which regulates a pressure of the heat transfer gas; a vicinity temperature sensor 5 which measures a vicinity temperature of the wafer W; a temperature estimation observer 10 which estimates the temperature of the wafer W based on the vicinity temperature measured by the vicinity temperature sensor 5 and a pressure operation amount inputted to the pressure regulator 43 or the pressure regulated by the pressure regulator; and a controller 11 which controls the pressure operation amount based on a preset temperature and the estimation wafer temperature estimated by the temperature estimation observer 10.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a wafer temperature control device, a wafer temperature control method, and a wafer temperature control program. [Background technology]

[0002] In a conventional semiconductor manufacturing process, such as a film deposition process, a wafer to be processed is placed on a plate such as an electrostatic chuck, and the temperature of the plate is adjusted to control the temperature of the wafer to a predetermined target temperature.

[0003] Since the plate on which the wafer is placed is placed in a low-pressure environment such as a vacuum, as shown in Patent Document 1, it has been considered to supply a heat transfer gas such as helium gas between the plate and the wafer in order to promote heat transfer from the temperature-controlled plate to the wafer.

[0004] Here, since the heat transfer coefficient varies depending on the pressure of the heat transfer gas supplied between the plate and the wafer, it is necessary to adjust the pressure of the heat transfer gas.

[0005] However, even if the pressure of the heat transfer gas is adjusted, it is difficult to measure the temperature of the wafer itself placed on the plate due to various technical limitations.

[0006] As shown in Patent Document 2, a temperature control device has been considered in which a temperature sensor is provided in the stage to measure the temperature in the vicinity of the wafer, and an observer estimates the temperature of the electronic device formed on the wafer.

[0007] However, this temperature control device is not designed to supply heat transfer gas between the stage and the wafer, and the observer does not use the pressure of the heat transfer gas as an input variable, so it is difficult to estimate the wafer temperature with sufficient accuracy and control the wafer temperature to a constant target temperature. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 4034344 [Patent Document 2] Patent Publication No. 2021-19066 Summary of the Invention [Problem to be solved by the invention]

[0009] Therefore, the present invention has been made to solve the above-mentioned problems, and has as its object to estimate the wafer temperature with sufficient accuracy and control the wafer temperature to a target temperature in a device that controls the wafer temperature by adjusting the pressure of a heat transfer gas. [Means for solving the problem]

[0010] That is, the wafer temperature control device of the present invention is a wafer temperature control device in which a wafer is placed on a temperature-adjusted plate and a heat transfer gas is supplied between the plate and the wafer to control the temperature of the wafer, and is characterized by comprising: a pressure regulator that adjusts the pressure of the heat transfer gas; a nearby temperature sensor that measures the nearby temperature of the wafer; a temperature estimation observer that estimates the temperature of the wafer based on the nearby temperature measured by the nearby temperature sensor and a pressure manipulation amount input to the pressure regulator or a pressure adjusted by the pressure regulator; and a controller that controls the pressure manipulation amount based on the set temperature of the wafer and an estimated wafer temperature estimated by the temperature estimation observer.

[0011] This wafer temperature control device estimates the wafer temperature using a temperature estimation observer that uses the heat transfer gas pressure as an input variable, so the wafer temperature can be estimated with sufficient accuracy. Furthermore, the pressure manipulation amount input to the pressure regulator that adjusts the heat transfer gas pressure is controlled based on the wafer set temperature and the estimated wafer temperature estimated by the temperature estimation observer, so the wafer temperature can be controlled to the target temperature with high accuracy.

[0012] It is also possible to control the cooling operation amount input to a cooler for adjusting the temperature of the plate or the heating operation amount input to a heater, but this makes it difficult to fine-tune the wafer temperature. Therefore, controlling the pressure operation amount input to a pressure regulator, as in the present invention, makes it easier to fine-tune the wafer temperature.

[0013] Here, the nearby temperature is, for example, the temperature of a member or space within a predetermined distance from the wafer, and includes temperatures for which a temperature model showing the relationship between the wafer temperature and the nearby temperature can be constructed. The nearby temperature also includes the temperature of a member in direct contact with the wafer, the temperature of the space or gas where the interface with the wafer exists, or the temperature of a member present across a gap of several μm from the wafer W. Furthermore, the nearby temperature may also include the temperature of a member to which heat may be conducted or transferred between the wafer and the nearby temperature by at least one of conduction, convection, and radiation.

[0014] Here, in order to estimate the wafer temperature using a simple system, it is conceivable that the temperature estimation observer uses a state space model in which the relationship between the wafer temperature and the pressure of the heat transfer gas is linear. However, in a real environment, there is a nonlinear relationship between the wafer temperature and the pressure of the heat transfer gas, which causes an error between the wafer temperature and the estimated wafer temperature estimated by the temperature estimation observer, making it difficult to accurately control the wafer temperature to the target temperature. To suitably solve this problem, it is desirable that the controller corrects the set temperature using a nonlinear relationship between the wafer temperature and the pressure of the heat transfer gas, which has been acquired in advance, and controls the pressure manipulation variable so that the temperature deviation between the corrected set temperature and the estimated wafer temperature becomes small.

[0015] In a specific embodiment of correcting the set wafer temperature using the nonlinear relationship between the previously acquired wafer temperature and the heat transfer gas pressure, the controller has a relationship data storage unit that stores nonlinear relationship data that indicates the nonlinear relationship between the previously acquired wafer temperature and the heat transfer gas pressure, and linear relationship data that indicates the linear relationship between the wafer temperature and the heat transfer gas pressure used in the state space model of the temperature estimation observer, and a converted pressure that corresponds nonlinearly to the set temperature is calculated from the set temperature and the nonlinear relationship data, and a converted temperature that corresponds linearly to the converted pressure is calculated from the converted pressure and the linear relationship data, and the converted temperature is used as the corrected set temperature.

[0016] In order to correct the estimation error of the estimated wafer temperature due to a deviation in the initial temperature and improve the estimation accuracy of the estimated wafer temperature, it is desirable that the temperature estimation observer comprises a temperature estimation model which is a linear state space model with the wafer temperature and the nearby temperature as output variables, a nearby temperature output unit which outputs the estimated nearby temperature estimated based on the temperature estimation model, a wafer temperature output unit which outputs the estimated wafer temperature estimated based on the temperature estimation model, and an observer gain, and that the deviation between the estimated nearby temperature output from the nearby temperature output unit and the nearby temperature measured by the nearby temperature sensor, or a value calculated from the deviation multiplied by the observer gain, is fed back into the temperature estimation model.

[0017] In addition, in order to improve the estimation accuracy of the estimated wafer temperature by taking into account the nonlinearity of the plate temperature, it is desirable that the temperature estimation observer comprises a temperature estimation model which is a linear state space model with the wafer temperature and the nearby temperature as output variables, a nearby temperature output unit which outputs the estimated nearby temperature estimated based on the temperature estimation model, a nearby temperature correction unit which corrects the estimated nearby temperature output from the nearby temperature output unit taking into account the nonlinear characteristics of the plate temperature, a wafer temperature output unit which outputs the estimated wafer temperature estimated based on the temperature estimation model, and an observer gain, and that the deviation between the corrected estimated nearby temperature output from the nearby temperature correction unit and the nearby temperature measured by the nearby temperature sensor, or a value calculated from the deviation, multiplied by the observer gain, is fed back into the temperature estimation model.

[0018] In order to simplify the control input and easily maintain the wafer temperature at a constant value, it is conceivable to set the cooling operation amount input to a cooler for adjusting the temperature of the plate or the heating operation amount input to a heater to a constant value. In this case, it is desirable that the temperature estimation observer includes the temperature estimation model according to the temperature of the temperature-adjusted plate.

[0019] Furthermore, a wafer temperature control method according to the present invention is a wafer temperature control method in which a wafer is placed on a temperature-adjusted plate and a heat transfer gas is supplied between the plate and the wafer to control the temperature of the wafer, the method comprising the steps of: adjusting the pressure of the heat transfer gas using a pressure regulator; measuring the temperature near the wafer using a proximity temperature sensor; estimating the temperature of the wafer using a temperature estimation observer based on the proximity temperature measured by the proximity temperature sensor and a pressure manipulation variable input to the pressure regulator or a pressure adjusted by the pressure regulator; and controlling the pressure manipulation variable based on the set temperature of the wafer and the estimated wafer temperature estimated by the temperature estimation observer.

[0020] Furthermore, the wafer temperature control program of the present invention is a wafer temperature control program used in a wafer temperature control device in which a wafer is placed on a temperature-adjusted plate and a heat transfer gas is supplied between the plate and the wafer to control the temperature of the wafer, and which is equipped with a pressure regulator that adjusts the pressure of the heat transfer gas and a proximity temperature sensor that measures the temperature in the vicinity of the wafer, and is characterized in that the program has a computer that functions as a temperature estimation observer that estimates the temperature of the wafer based on the proximity temperature measured by the proximity temperature sensor and the pressure manipulation amount input to the pressure regulator or the pressure adjusted by the pressure regulator, and a controller that controls the pressure manipulation amount based on the set temperature of the wafer and the estimated wafer temperature estimated by the temperature estimation observer.

[0021] The wafer temperature control program may be distributed electronically or may be recorded on a program recording medium such as a CD, DVD, or flash memory.

[0022] Although the present invention described above is an aspect in which the wafer set temperature is corrected using a nonlinear relationship between the wafer temperature and the pressure of the heat transfer gas, it may also be an aspect in which the wafer set temperature is corrected using a nonlinear relationship between the wafer temperature and the temperature of a temperature regulator. That is, a wafer temperature control device according to the present invention includes a temperature regulator that adjusts the wafer temperature in accordance with an input temperature manipulation variable, a proximity temperature sensor 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 sensor and the temperature manipulation variable input to the temperature regulator or the temperature of the temperature regulator, and a controller that controls the temperature manipulation variable based on the wafer set temperature and an estimated wafer temperature estimated by the temperature estimation observer, wherein the temperature estimation observer uses a state space model in which the relationship between the wafer temperature and the temperature of the temperature regulator is linear, and the controller corrects the set temperature using the nonlinear relationship between the wafer temperature and the temperature regulator that has been acquired in advance, and controls the temperature manipulation variable so as to reduce the temperature deviation between the corrected set temperature and the estimated wafer temperature. [Effects of the Invention]

[0023] As described above, according to the present invention, in a system that controls the wafer temperature by adjusting the pressure of the heat transfer gas, it is possible to estimate the wafer temperature with sufficient accuracy and control the wafer temperature to a target temperature. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a perspective view schematically showing the configuration of a wafer temperature control device according to an embodiment of the present invention. [Figure 2] 10 is a diagram showing the relationship between the pressure of the heat transfer gas supplied between the wafer and the suction plate and the heat transfer coefficient between the wafer and the suction plate. FIG. [Figure 3] FIG. 2 is a diagram schematically showing a wafer temperature control system in the embodiment. [Figure 4] FIG. 2 is a functional block diagram of a wafer control apparatus according to the embodiment. [Figure 5] FIG. 2 is a schematic diagram showing a state space model of the wafer temperature control device in the same embodiment. [Figure 6] 10 is a graph showing a linear relationship (TW_linear) and a non-linear relationship (TW_curve) between the wafer temperature TW and the heat transfer gas pressure PHG. [Figure 7] 4 is a schematic diagram showing a method of correcting the set temperature of the controller in the embodiment. FIG. [Figure 8] 10 shows experimental results of the wafer temperature control device in the same embodiment when (a) observer control is performed using an uncorrected set temperature TSET, and when (b) observer control is performed using a corrected set temperature TSET'. [Figure 9] FIG. 10 is a functional block diagram of a wafer control apparatus according to a modified embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0025] <One embodiment of the present invention> An embodiment of a wafer temperature control device according to the present invention will be described below with reference to the drawings. Note that, for ease of understanding, all of the drawings shown below are drawn in a schematic manner, with appropriate omissions or exaggerations. Identical components are designated by the same reference numerals, and their descriptions will be omitted where appropriate.

[0026] The wafer temperature control device 100 of this embodiment is used in a semiconductor manufacturing device that performs a semiconductor manufacturing process such as a film formation process, and is configured to electrostatically chuck the back surface of a wafer W in a vacuum chamber, for example.

[0027] Specifically, as shown in FIG. 1, the wafer temperature control device 100 includes a suction plate 2 on the upper surface of which a wafer W is placed, and a temperature regulator 3 that adjusts the temperature of the suction plate 2.

[0028] The suction plate 2 constitutes a so-called electrostatic chuck that holds the wafer W by electrostatic suction force. The suction plate 2 in this embodiment is a ceramic plate having a generally circular shape, and the upper surface thereof serves as an suction surface 2a that suctions the wafer W. An electrostatic electrode (not shown) is provided inside the suction plate 2 to generate an electrostatic force between the suction plate 2 and the wafer W.

[0029] The temperature regulator 3 regulates the temperature of the suction plate 2 to a preset temperature, and includes a heater 31 that heats the suction plate 2 and a cooler 32 that cools the suction plate 2. Note that the temperature regulator 3 may not necessarily include the heater 31.

[0030] The heater 31 is provided inside the suction plate 2 and has a plurality of heater electrodes 31a for heating the suction plate 2. The power supplied to the plurality of heater electrodes 31a is controlled by a heating control unit (not shown) of the control device COM, and each of the heater electrodes 31a is independently controlled according to the amount of heating operation set by the user.

[0031] The cooler 32 is provided in contact with the lower surface of the adsorption plate 2, and includes a substantially disk-shaped base plate 32a and a cooling flow path 32b formed in the base plate 32a.

[0032] The cooling flow path 32b is formed in a spiral shape in a plan view inside the base plate 32a. An inlet flow path 32c and an outlet flow path 32d, which are connected to a cooling source (not shown), such as a chiller, are connected to the cooling flow path 32b. A control valve 32e that controls the flow rate of the refrigerant is provided in the flow path connected to the cooling flow path 32b, and the opening degree of the control valve 32e is controlled by a valve control unit (not shown) of the control device COM.

[0033] The wafer temperature control apparatus 100 of this embodiment also includes a gas supply mechanism 4 that supplies a heat transfer gas, such as helium gas or argon gas, between the suction plate 2 and the wafer W.

[0034] The gas supply mechanism 4 supplies a heat transfer gas at a predetermined pressure between the suction surface 2a of the suction plate 2 and the back surface of the wafer W that is being suctioned.

[0035] Specifically, the gas supply mechanism 4 has gas circulation grooves 41 formed on the suction surface 2a of the suction plate 2, gas supply paths 42 that supply a heat transfer gas to the gas circulation grooves 41, and a pressure regulator 43 that adjusts the pressure of the heat transfer gas supplied to the gas circulation grooves 41. The heat transfer gas supplied to the gas circulation grooves 41 flows from the gas circulation grooves 41 into the gap between the suction surface 2a of the suction plate 2 and the backside of the wafer W that is being sucked.

[0036] The gas circulation grooves 41 include, for example, a plurality of linear grooves formed radially from the central axis of the suction plate 2 and a plurality of circular grooves formed circularly from the central axis of the suction plate 2. In addition, the gas supply path 42 is formed along the central axis of the suction plate 2 and is connected to a heat transfer gas source (not shown).

[0037] Furthermore, the pressure regulator 43 can adjust the pressure of the heat transfer gas to change the heat transfer rate from the suction plate 2 to the wafer W (the heat transfer coefficient between the wafer W and the suction plate 2). Note that FIG. 2 shows the relationship between the pressure of the heat transfer gas supplied between the wafer W and the suction plate 2 and the heat transfer coefficient between the wafer W and the suction plate 2.

[0038] Specifically, the pressure regulator 43 has a pressure sensor and a pressure control valve, and the opening degree of the pressure control valve is controlled by the controller 11 of the control device COM.

[0039] The wafer temperature control device 100 also includes a proximity temperature sensor 5 that measures the temperature in the vicinity of the wafer W. This proximity temperature sensor 5 is provided on the rear surface side of the base plate 32a and measures the temperature of the base plate 32a as the temperature in the vicinity of the wafer W. The proximity temperature sensor 5 in this embodiment is, for example, an infrared temperature sensor. Note that the proximity temperature sensor 5 may also measure the temperature of the suction plate 2 as the temperature in the vicinity of the wafer W.

[0040] <2. Wafer temperature control system> Furthermore, the wafer temperature control apparatus 100 includes a control device COM that controls the operations of at least the temperature regulator 3 and the pressure regulator 43 .

[0041] 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. A wafer temperature control program stored in the memory is executed, and the various devices cooperate to configure a wafer temperature control system as shown in Figures 3 and 4.

[0042] First, the outline of the wafer temperature control system of this embodiment will be described with reference to FIG.

[0043] In this embodiment, the estimated wafer temperature T W_est , and the nearby temperature T measured by the nearby temperature sensor 5 P_meas Regardless of the temperature, a fixed power is supplied to each heater electrode 31a of the heater 31, and the valve opening of the control valve 32e of the cooler 32 is controlled to be constant. That is, the heating operation amount and the cooling operation amount are fixed during operation, and the temperature adjustment amount per unit time by the temperature adjuster 3 is controlled to be constant.

[0044] On the other hand, the pressure regulator 43 is configured to adjust the estimated wafer temperature T W_est , and the nearby temperature T measured by the nearby temperature sensor 5 P_meas The input pressure manipulation amount is successively changed based on the above.

[0045] Specifically, the control device COM uses a temperature estimation observer 10 to estimate the proximity temperature T P_meas The controller COM estimates the temperature of the wafer W based on the estimated wafer temperature T W_est is fed back to estimate the wafer temperature T W_est is the set temperature T SET The pressure regulator 43 is controlled to follow the above.

[0046] More specifically, as shown in FIG. 3, the control device COM includes a temperature estimation observer 10 for estimating the temperature of the wafer W, and a set temperature T SET and the estimated wafer temperature T estimated by the temperature estimation observer 10. W_est and a controller 11 that performs feedback control of the pressure regulator 43 based on the above.

[0047] <2-1. Temperature estimation observer 10> The temperature estimation observer 10 at least simulates the thermal behavior of the system and estimates the temperature of the wafer W, which cannot be measured directly.

[0048] Specifically, the temperature estimation observer 10 estimates the proximity temperature T P_meas and the pressure P output by the pressure regulator 43 OUT Based on this, the temperature T of the wafer W is W The estimated wafer temperature T W_est and the nearby temperature T P The estimated nearby temperature T P_est and

[0049] Specifically, the temperature estimation observer 10 estimates the temperature T W and the nearby temperature T P and a temperature estimation model 10a, which is a linear state space model with the output variable being , and an estimated wafer temperature T estimated based on the temperature estimation model 10a. W_estand a wafer temperature output unit 10b that outputs an estimated vicinity temperature T estimated based on the temperature estimation model 10a. P_est and an observer gain 10d.

[0050] The temperature estimation observer 10 then calculates the estimated nearby temperature T P_est and the nearby temperature T measured by the nearby temperature sensor 5. P_meas The deviation from the temperature is multiplied by an observer gain 10d, and the resulting value is fed back into the temperature estimation model 10a.

[0051] The temperature estimation model 10a is a model of, for example, heat conduction between the suction plate 2 and the wafer W itself, and heat transfer between the suction plate 2 and the wafer W.

[0052] This temperature estimation model 10a is based on at least the temperature T W and the pressure of the heat transfer gas P HG An example of the state space model is shown in FIG. 5. The input variables of the temperature estimation model 10a of this embodiment are the pressure P OUT (p in FIG. 5), as well as the heating amount q by the heater 31 or the cooling amount by the cooler 32 (the temperature T c ) etc.

[0053] Specifically, the temperature estimation model 10a uses the pressure P output from the pressure regulator 43. OUT The input variable vector including the estimated wafer temperature T W_est and estimated nearby temperature T P_est The state variable vector containing

[0054] The wafer temperature output unit 10b calculates the estimated wafer temperature T W_est is extracted and output to the controller 11.

[0055] The nearby temperature output unit 10c calculates the estimated nearby temperature T P_est The output estimated nearby temperature T P_est and the nearby temperature T measured by the nearby temperature sensor 5 P_meas The deviation from this is calculated and input to the observer gain 10d.

[0056] <2-2. Controller 11> The controller 11 sets the set temperature T of the wafer W. SET and the estimated wafer temperature T estimated by the temperature estimation observer 10. W_est and the pressure of the heat transfer gas P HG The pressure regulator 43 controls the pressure.

[0057] In a real environment, as shown in FIG. 6, the temperature T W and the pressure of the heat transfer gas P HG On the other hand, in the temperature estimation observer 10, the output (temperature T of the wafer W) relative to the pressure manipulation amount is W ) is assumed to be linear, and the temperature T W and the pressure of the heat transfer gas P HG It is assumed that there is a linear relationship between

[0058] For this reason, the controller 11 of this embodiment uses the temperature T of the wafer W acquired in advance as shown in FIGS. W and the pressure of the heat transfer gas P HG The set temperature T SET Correct the set temperature T SET ' and estimated wafer temperature T W_est The pressure control amount is controlled so as to reduce the temperature deviation between the pressure control amount and the temperature control amount.

[0059] Specifically, the controller 11 calculates the temperature T of the wafer obtained in advance. W and the pressure of the heat transfer gas P HG and the temperature T of the wafer W used in the state space model of the temperature estimation observer 10. Wand the pressure of the heat transfer gas P HG and linear relational data indicating a linear relation between the two.

[0060] Then, the controller 11 calculates the input set temperature T SET and nonlinear relationship data, the set temperature T SET The converted pressure P corresponds nonlinearly to SET The controller 11 calculates the converted pressure P SET From the linear relationship data, the converted pressure P SET The converted temperature is calculated as a linearly corresponding temperature, and the converted temperature is set to the corrected set temperature T SET 'Let's say.

[0061] Next, the controller 11 calculates the corrected set temperature T SET ' and the estimated wafer temperature T estimated by the temperature estimation observer 10 W_est The temperature deviation between the temperature and the temperature is multiplied by a gain K to perform an integral operation. The controller 11 also calculates the deviation between the calculated integral value and a value obtained by multiplying the state variable vector by a predetermined state feedback gain F, and inputs this deviation to the pressure regulator 43 as the pressure manipulation amount.

[0062] Next, the controller 11 calculates the uncorrected set temperature T SET When observer control is used, and when the corrected set temperature T SET The experimental results when the observer was used are shown in Fig. 8. Fig. 8(a) shows the uncorrected set temperature T SET The results are shown in Fig. 8(b) when observer control is performed using the corrected set temperature T SET This is the result when observer control is performed using the set temperature T SET When using the temperature T W and the wafer temperature T estimated by the temperature estimation observer 10 W_est On the other hand, the corrected set temperature T SET When ' is used, the temperature T of the wafer W W and the wafer temperature T estimated by the temperature estimation observer 10 W_est The error between the two is decreasing.

[0063] <3. Effects of this embodiment> As described above, according to the wafer temperature control apparatus 100 of this embodiment, the pressure P HG The temperature T of the wafer W is calculated using a temperature estimation observer 10 with the following as input variables: W Since the temperature of the wafer W is estimated, W The set temperature T of the wafer W can be estimated with sufficient accuracy. SET and the estimated wafer temperature T estimated by the temperature estimation observer 10. W_est and the pressure of the heat transfer gas P HG Since the pressure control amount input to the pressure regulator 43 that adjusts the pressure is controlled, the wafer temperature can be controlled to the target temperature with high precision.

[0064] It is also possible to control the amount of cooling input to the cooler 32 for adjusting the temperature of the suction plate 2 or the amount of heating input to the heater 31. W Therefore, it is more difficult to finely adjust the temperature T of the wafer W by controlling the pressure control amount input to the pressure regulator 43 as in this embodiment. W This makes it easy to fine-tune the

[0065] In particular, in this embodiment, the controller 11 controls the temperature T W and the pressure of the heat transfer gas P HG The set temperature T SET Correct the set temperature T SET ' and estimated wafer temperature T W_est The pressure control amount is controlled so as to reduce the temperature deviation from the estimated wafer temperature T W_est The estimation error of the temperature T of the wafer W can be reduced. W can be controlled to the target temperature with high precision.

[0066] <4. Other embodiments> As shown in FIG. 9, the temperature estimation observer of the embodiment estimates the estimated nearby temperature T P_estThe proximity temperature correction unit 10e further corrects the estimated proximity temperature T P_est ' and the nearby temperature T measured by the nearby temperature sensor 5 P Alternatively, the deviation from the temperature estimating model 10a or a value calculated from the deviation may be multiplied by the observer gain 10d, and the result may be fed back into the temperature estimating model 10a.

[0067] In the above embodiment, the temperature of the suction plate 2 is adjusted to be constant, but the wafer temperature control device 100 may be configured to change the temperature of the suction plate 2. In this case, the temperature estimation observer 10 may be configured to include a temperature estimation model 10a corresponding to the temperature of the temperature-adjusted suction plate 2.

[0068] The temperature estimation observer 10 calculates the estimated nearby temperature T P_est and the nearby temperature T measured by the nearby temperature sensor 5. P The temperature estimation model 10a may be configured to further include an observer integrator that integrates the deviation from the temperature estimating model 10a, and the integral value output from the observer integrator multiplied by an observer gain 10d may be fed back to the temperature estimation model 10a.

[0069] In this case, the estimated nearby temperature T P_est and the nearby temperature T P It is conceivable to feed back to the temperature estimation model 10a a value obtained by multiplying the deviation from the temperature range by the proportional observer gain, and to feed back to the temperature estimation model 10a a value obtained by multiplying the integral value of the deviation by the integral observer gain. It is also conceivable to feed back to the temperature estimation model 10a only a value obtained by multiplying the integral value of the deviation by the integral observer gain.

[0070] The cooler and heater are controlled to have a constant output, but the amount of cooling operation or the amount of heating operation may also be changed by output feedback control or state feedback control for the heater.

[0071] 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.

[0072] Furthermore, the heater 31 of the above embodiment can form a temperature distribution on the suction plate 2 by using multiple heater electrodes 31a. For example, the heater 31 can vary the amount of heat applied to the central portion and the outer periphery of the suction plate 2, and can also vary the amount of heat applied between a large, roughly C-shaped area on the outer periphery and the remaining small area. That is, three heating areas are set on the suction plate 2, thereby forming a temperature distribution on the suction plate 2. The cooler 32 may also be configured to form three cooling areas on the surface of the base plate 32a corresponding to the three heating areas of the suction plate 2.

[0073] The heating or cooling regions of the wafer W and suction plate 2 are not limited to being divided into three regions, but may be divided into more regions or into two regions. Alternatively, the wafer W or the suction plate 2 as a whole may be treated as a single temperature without setting regions. Furthermore, the suction plate 2 may not have a suction function and may simply be a plate on which the wafer W is placed.

[0074] In the present invention described above, the set temperature of the wafer is corrected using the nonlinear relationship between the wafer temperature and the pressure of the heat transfer gas, but the set temperature of the wafer may also be corrected using the nonlinear relationship between the wafer temperature and the temperature of the temperature regulator. Specifically, the temperature estimation observer 10 estimates the temperature T W The temperature estimation observer 10 uses a state space model in which the relationship between the temperature T of the wafer W and the temperature of the temperature regulator 3 is linear. W The controller 11 uses a state space model in which the relationship between the temperature T of the wafer W and the temperature of the heater 31 and / or the cooler 32 is linear. Wand the temperature of the heater 31 and / or the cooler 32, the set temperature T SET Correct the set temperature T SET ' and estimated wafer temperature T W_est The temperature manipulated variable (heating manipulated variable and / or cooling manipulated variable) may be controlled so as to reduce the temperature deviation from the temperature of the temperature sensor.

[0075] 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.

[0076] The location measured by the proximity temperature sensor is not limited to the location described above, but 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 controller is not limited to an infrared temperature sensor, but may be, for example, a thermocouple provided within the plate.

[0077] 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. [Explanation of symbols]

[0078] 100 Wafer temperature control device 2. Adsorption plate (plate) 3...Temperature regulator 31...heater 32...Cooler 4 Gas supply mechanism 43 Pressure regulator 5. Near-field temperature sensor 10 Temperature estimation observer 10a Temperature estimation model 10b Wafer temperature output section 10c Near-field temperature output section 10d Observer Gain 11 Controller

Claims

1. A wafer temperature control device in which a wafer is placed on a temperature-adjusted plate and a heat transfer gas is supplied between the plate and the wafer to control the temperature of the wafer, a pressure regulator for adjusting the pressure of the heat transfer gas; a proximity temperature sensor for measuring a proximity temperature of the wafer; a temperature estimation observer that estimates the temperature of the wafer based on the nearby temperature measured by the nearby temperature sensor and the pressure manipulation amount input to the pressure regulator or the pressure adjusted by the pressure regulator; a controller that controls the pressure manipulated variable based on the wafer set temperature and the estimated wafer temperature estimated by the temperature estimation observer; the temperature estimation observer uses a state space model in which the relationship between the temperature of the wafer and the pressure of the heat transfer gas is linear; The controller corrects the set temperature using a nonlinear relationship between the wafer temperature and the pressure of the heat transfer gas that has been acquired in advance, and controls the pressure manipulation variable so that the temperature deviation between the corrected set temperature and the estimated wafer temperature becomes small.

2. The controller a relational data storage unit for storing nonlinear relational data indicating a nonlinear relation between the wafer temperature and the heat transfer gas pressure, which has been previously acquired, and linear relational data indicating a linear relation between the wafer temperature and the heat transfer gas pressure, which is used in a state space model of the temperature estimation observer; A converted pressure that nonlinearly corresponds to the set temperature is calculated from the set temperature and the nonlinear relationship data; 2. The wafer temperature control apparatus according to claim 1, wherein a converted temperature that linearly corresponds to the converted pressure is determined from the converted pressure and the linear relationship data, and the converted temperature is set as the corrected set temperature.

3. The temperature estimation observer a temperature estimation model that is a linear state space model with the wafer temperature and the vicinity temperature as output variables; a wafer temperature output unit that outputs the estimated wafer temperature estimated based on the temperature estimation model; a proximity temperature output unit that outputs an estimated proximity temperature estimated based on the temperature estimation model; an observer gain; 3. A wafer temperature control device as described in claim 1 or 2, wherein the deviation between the estimated nearby temperature output from the nearby temperature output unit and the nearby temperature measured by the nearby temperature sensor, or a value calculated from the deviation, multiplied by the observer gain, is fed back into the temperature estimation model.

4. The temperature estimation observer a temperature estimation model that is a linear state space model with the wafer temperature and the vicinity temperature as output variables; a wafer temperature output unit that outputs the estimated wafer temperature estimated based on the temperature estimation model; a proximity temperature output unit that outputs an estimated proximity temperature estimated based on the temperature estimation model; a proximity temperature correction unit that corrects the estimated proximity temperature output from the proximity temperature output unit in consideration of nonlinear characteristics of the temperature of the plate; an observer gain; 3. The wafer temperature control device according to claim 1, wherein the deviation between the corrected estimated nearby temperature output from the nearby temperature correction unit and the nearby temperature measured by the nearby temperature sensor, or a value calculated from the deviation, multiplied by the observer gain, is fed back into the temperature estimation model.

5. The wafer temperature control apparatus according to claim 3 , wherein the temperature estimation observer includes the temperature estimation model that corresponds to the temperature of the temperature-adjusted plate.

6. The wafer temperature control apparatus according to claim 4 , wherein the temperature estimation observer includes the temperature estimation model that corresponds to the temperature of the temperature-adjusted plate.

7. 1. A wafer temperature control method for controlling a temperature of a wafer by placing the wafer on a temperature-adjusted plate and supplying a heat transfer gas between the plate and the wafer, comprising: adjusting the pressure of the heat transfer gas by a pressure regulator; measuring the temperature near the wafer with a proximity temperature sensor; using a temperature estimation observer to estimate the temperature of the wafer based on the nearby temperature measured by the nearby temperature sensor and the pressure manipulated variable input to the pressure regulator or the pressure adjusted by the pressure regulator; a method for controlling the pressure manipulation amount based on a set temperature of the wafer and an estimated wafer temperature estimated by the temperature estimation observer, the temperature estimation observer uses a state space model in which the relationship between the temperature of the wafer and the pressure of the heat transfer gas is linear; a nonlinear relationship between the wafer temperature and the pressure of the heat transfer gas that is previously acquired is used to correct the set temperature, and the pressure manipulated variable is controlled so that a temperature deviation between the corrected set temperature and the estimated wafer temperature becomes small.

8. A wafer temperature control program used in a wafer temperature control device that controls the temperature of a wafer by supplying a heat transfer gas between a temperature-adjusted plate and the plate, the program comprising: a pressure regulator that adjusts the pressure of the heat transfer gas; and a proximity temperature sensor that measures a temperature near the wafer, the program comprising: a function as a temperature estimation observer that estimates the temperature of the wafer based on the nearby temperature measured by the nearby temperature sensor and the pressure manipulation amount input to the pressure regulator or the pressure adjusted by the pressure regulator; a computer is provided with a function as a controller that controls the pressure manipulation amount based on the set temperature of the wafer and the estimated wafer temperature estimated by the temperature estimation observer; the temperature estimation observer uses a state space model in which the relationship between the temperature of the wafer and the pressure of the heat transfer gas is linear; the controller corrects the set temperature using a nonlinear relationship between the wafer temperature and the pressure of the heat transfer gas that has been acquired in advance, and controls the pressure manipulation variable so that a temperature deviation between the corrected set temperature and the estimated wafer temperature becomes small.

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