Temperature control apparatus, temperature control method, device manufacturing apparatus, and article manufacturing method

Abstract

To provide a technique advantageous for reducing peek electric currents generated by a plurality of heaters for secondary temperature control while maintaining a control accuracy of secondary temperature control.SOLUTION: A temperature-regulating apparatus includes: a first control part for controlling a cooler which conducts primary temperature regulating of a temperature regulating medium; and a second control part for controlling electric power supply to a plurality of respective heaters which conduct secondary temperature regulating of the temperature regulating medium by PWM control. The second control part determines timings of time periods while pulses of PWM control of a plurality of respective heaters are on so that a total current value of a plurality of the heaters does not surpass a predetermined limited value, and the first control part determines correction values to the target temperature on the basis of control inputs output from the second control part to a plurality of the respective heaters, and corrects the target temperature using the determined correction values.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a temperature control apparatus, a temperature control method, a device manufacturing apparatus, and an article manufacturing method. [Background technology]

[0002] High throughput is required for device manufacturing equipment such as exposure equipment used in the manufacturing processes of semiconductor devices, display devices, etc., and with this trend toward higher throughput in recent years, the amount of heat generated from driving parts (heat-generating parts) such as linear motors is increasing. Temperature control fluids such as water, antifreeze, and inert liquids are used to cool the heat-generating parts. The temperature control fluid, which has absorbed the heat generated by the heat-generating parts and rises in temperature, undergoes primary temperature control through heat exchange with a refrigerator controlled by inverter or hot bypass gas, or with cold water supplied from the equipment.

[0003] The high-precision temperature control required for device manufacturing equipment is difficult to achieve using only primary temperature control such as the refrigerators and heat exchangers mentioned above. Therefore, secondary temperature control is performed using precision heaters, which have high responsiveness and precision, located near the heat-generating part. One method for adjusting the output of a precision heater is the PWM (Pulse Width Modulation) method, which changes the ratio of the time per unit time that electricity is applied from the power source to the precision heater. The PWM method is widely used as a heater control method because it allows for relatively inexpensive equipment configuration and is easy to control. The power source for the precision heater is the facility power supply of the semiconductor factory where the device manufacturing equipment is installed.

[0004] In order to reduce the current flowing through the precision heater used for secondary temperature control, it is necessary to reduce the rated output value of the precision heater. To achieve this, it is important to reduce the control temperature difference ΔT between the primary and secondary temperature controls. As an example of how to solve this problem, Patent Document 1 discloses a technology for changing the target temperature of primary temperature control in response to a drive command to a drive unit, which is the heat source of the device. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5641709 Summary of the Invention [Problem to be solved by the invention]

[0006] According to the technology of Patent Document 1, when the output of a precision heater is controlled by the PWM method, the average value per unit time of the total current flowing through multiple precision heaters can be reduced. However, since the energization times of multiple precision heaters overlap within the PWM control cycle, the effect of reducing peak current cannot be expected.

[0007] Because the power usage of device manufacturing equipment is determined based on peak current, an increase in peak current can lead to an increase in the power capacity of the factory where the device manufacturing equipment is installed. One possible way to reduce peak current is to lengthen the PWM control period so that the power-on times of multiple precision heaters do not overlap. However, in this case, the longer the PWM control period, the greater the temporal unevenness of the heat generated by the precision heaters, which can lead to problems such as reduced temperature stability in secondary temperature control.

[0008] The present invention provides an advantageous technique for reducing peak currents generated in multiple heaters while maintaining the control accuracy of temperature control. [Means for solving the problem]

[0009] According to one aspect of the present invention, there is provided a system including a cooler that performs primary temperature control by cooling a temperature control medium, a first control unit that controls the cooler based on the deviation between a target temperature and a current temperature, a plurality of heaters that perform secondary temperature control by providing heat generated in response to supplied power to the temperature control medium cooled by the cooler, and a second control unit that controls the power supply to each of the plurality of heaters by PWM control, wherein the second control unit determines the timing of a period during which a pulse in the PWM control of each of the plurality of heaters is ON so that the total current value of the plurality of heaters does not exceed a predetermined limit value, and the first control unit: Using a correction value based on the total period obtained by adding up the periods of each of the plurality of heaters and adjusting the target temperature. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a technique that is advantageous for reducing peak currents generated in a plurality of heaters while maintaining the control accuracy of temperature control. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a device manufacturing apparatus. [Figure 2] FIG. 2 is a diagram showing an example of the configuration of a temperature adjustment device. [Figure 3] Block diagram of the secondary temperature control system. [Figure 4] 4 is a flowchart showing a control process for timing when a pulse is turned ON in PWM control. [Figure 5] FIG. 1 is a diagram illustrating the generation of peak current due to overlapping of pulse ON periods in PWM control. [Figure 6] Block diagram of the primary temperature control system. [Figure 7] FIG. 4 is a diagram illustrating the effect of the first embodiment. [Figure 8] Block diagram of the primary temperature control system. [Figure 9] 10 is a flowchart showing a control process for timing when a pulse is turned ON in PWM control according to a second embodiment. [Figure 10]FIG. 10 is a diagram illustrating the effect of the second embodiment. [Figure 11] 10 is a flowchart of a temperature control method. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0013] First Embodiment FIG. 1 is a diagram schematically illustrating the configuration of a device manufacturing apparatus according to a first embodiment to which a temperature control device of the present invention is applied. Here, an example will be described in which the device manufacturing apparatus is configured as a lithography apparatus that forms a pattern on a substrate. Lithography apparatuses include imprint apparatuses and exposure apparatuses. An imprint apparatus is an apparatus that forms a pattern on a substrate by bringing a mold (master) into contact with an imprint material supplied on the substrate and curing the imprint material. An exposure apparatus is an apparatus that exposes a photoresist supplied on the substrate through a master (reticle) that is an exposure mask, thereby forming a latent image in the photoresist that corresponds to the pattern of the master. To provide a concrete example, an example will be described below in which the lithography apparatus is configured as an exposure apparatus.

[0014] 1, light emitted from a light source (not shown), such as an ArF excimer laser or a KrF excimer laser, is provided to an illumination optical system 2. The illumination optical system 2 uses the light provided by the light source to illuminate a portion of a reticle (master) 1 with slit light (light whose cross-sectional shape is defined by a slit). While the reticle 1 is illuminated by the slit light, the reticle 1 and wafer (substrate) 9 are synchronously scanned by a reticle stage 3 and a wafer stage 10. As a result of this synchronous scanning, the entire pattern of the reticle 1 is transferred onto the wafer 9 via a projection optical system 4 held by a surface plate 5.

[0015] Reticle stage 3 includes a reticle holder that holds reticle 1 and a drive unit (e.g., an actuator such as a linear motor) that drives it, and is configured so that the drive unit drives the reticle holder above surface plate 14. Wafer stage 10 includes a wafer holder that holds wafer 9 and a drive unit (e.g., an actuator such as a linear motor) that drives it, and is configured so that the drive unit drives the wafer holder above surface plate 15.

[0016] The positional relationship between the reticle stage 3 and wafer stage 10 is measured in real time by measuring instruments including a reference mirror 11 and a laser interferometer 12. Based on these measurement values, a stage control device 13 performs positioning and synchronization control of the reticle 1 and wafer 9. During exposure, the wafer stage 10 can be controlled so that the surface of the wafer 9 coincides with the focal plane of the projection optical system 4. Here, the surface position (vertical position and tilt) of the wafer 9 is measured by an optical focus sensor (not shown), and the measurement results are provided to the stage control device 13.

[0017] The main body of the device manufacturing apparatus (exposure apparatus) is installed in an environmental chamber (not shown), and the environment surrounding the main body can be maintained at a predetermined temperature. Air that has been individually temperature-adjusted is blown into the spaces surrounding the reticle stage 3, wafer stage 10, laser interferometer 12, etc., and the space surrounding the projection optical system 4, so that the environmental temperature can be maintained with even greater precision.

[0018] The reticle stage 3 and wafer stage 10 generate a large amount of heat from the driving units when driving the controlled objects. The driving units drive the controlled objects in response to commands from the stage control device 13, and the amount of heat generated by the driving units depends on the driving pattern (control information for controlling the driving units).

[0019] Heat generated by the drive unit causes expansion and distortion of the wafer stage 10 (wafer 9) and reticle stage (reticle 1). Expansion and distortion of the wafer stage 10 and reticle stage cause position fluctuations and tilting of the reference mirror 11, which can cause errors in the measurement results obtained by measuring instruments including the laser interferometer 12. Furthermore, expansion and distortion of the wafer 9 and reticle 1 can cause distortion of the pattern formed on the wafer 9. Furthermore, changes in the temperature of the reticle stage 3 and wafer stage 10 cause changes in the temperature of the air around them. If air with a changed temperature flows within the optical path of the laser interferometer 12, fluctuations due to changes in the refractive index can cause measurement errors. For this reason, heat generated by the drive unit must be quickly recovered.

[0020] To recover heat generated by multiple drive units (multiple heat-generating units) such as the reticle stage 3 and wafer stage 10 and maintain a constant temperature, cooling channels 6a and 6d are disposed inside or around the drive units. To reduce the effects of heat (radiant heat, exposure heat, etc.) that cannot be recovered by the cooling channels 6a and 6d, cooling channels 6b and 6c are disposed inside or around the projection optical system 4 and base 5, respectively. A temperature-controlled temperature-control medium 30 (a fluid such as a liquid or gas) shown in FIG. 2 flows through the cooling channels 6a, 6b, 6c, and 6d. The cooling channels 6a, 6b, 6c, and 6d, together with the pipes 32a, 32b, 32c, and 32d connected thereto, form a circulation path for the temperature-control medium 30. The temperature-control medium 30 is supplied and recovered by the temperature control device 100 via the pipes 32a, 32b, 32c, and 32d. Here, we have described a configuration in which cooling channels are arranged inside or around the reticle stage 3, wafer stage 10, projection optical system 4, and base 5, but cooling channels may also be arranged inside or around other units not shown in Figure 1.

[0021] Next, an example configuration of a temperature adjustment device 100 will be described with reference to Figure 2. The temperature adjustment device 100 includes a heat exchanger 24 as a cooler that performs primary temperature adjustment by cooling a temperature adjustment medium 30, and a primary temperature control unit 21 as a first control unit that controls the heat exchanger 24. The temperature adjustment device 100 further includes multiple heaters that perform secondary temperature adjustment by providing heat generated in response to supplied power to the temperature adjustment medium 30 cooled by the heat exchanger 24, and a second control unit that controls the power supply to each of the multiple heaters using PWM control. In the following embodiment, the second control unit is exemplified as including secondary temperature control units 26a, 26b, 26c, and 26d.

[0022] The temperature control medium 30 temporarily stored in the tank 29 is sent by a pump 31 through a pipe 32 to the heat exchanger 24 (cooler). For example, a plate-type heat exchanger can be used as the heat exchanger 24. In the plate-type heat exchanger, the temperature control medium 30 and the cooling water 27 flow in countercurrent with a plate separating them, thereby exchanging heat between the temperature control medium 30 and the cooling water 27. A temperature sensor 22 (first temperature sensor) arranged in the pipe 32 measures the temperature of the temperature control medium 30 that has passed through the heat exchanger 24, and the measured value is provided to a primary temperature control unit 21 (first control unit) of the temperature control unit 20.

[0023] Furthermore, the primary temperature control unit 21 is provided with manipulated variables from secondary temperature control units 26a, 26b, 26c, and 26d (second control units), which will be described later. The primary temperature control unit 21 adjusts the opening of the control valve 23 based on the manipulated variables from the temperature sensor 22 and the secondary temperature control units 26a to 26d. This adjusts the flow rate of the cooling water 27 supplied to the heat exchanger 24, thereby adjusting the temperature of the temperature control medium 30. The cooling water 27 is typically supplied through a pipeline 25 from factory equipment (not shown). The heat exchanger 24 may be a plate-type heat exchanger as described above, or may be a temperature control unit using a Peltier element, a temperature control unit including a hot gas bypass-type refrigerator with variable cooling capacity, or the like.

[0024] The temperature-adjusting medium 30, whose temperature has been controlled by the primary temperature control unit 21 to match the target temperature, is supplied to the inside or periphery of the cooling targets 40a, 40b, 40c, and 40d via a pipe 32. In this embodiment, the cooling targets 40a to 40d correspond to the reticle stage 3, the projection optical system 4, the surface plate 5, and the wafer stage 10, respectively, but are not limited to this. The number of cooling targets may be increased or decreased, and the related configurations may also be increased or decreased.

[0025] A plurality of heaters, including heaters 28a, 28b, 28c, and 28d, are disposed between the heat exchanger 24 and the objects to be cooled 40a-40d. Temperature sensors 29a, 29b, 29c, and 29d (a plurality of second temperature sensors) are disposed on the pipes 32a, 32b, 32c, and 32d, respectively, so as to measure the temperature of the temperature adjustment medium 30 that has passed through or around the objects to be cooled 40a-40d. The temperature sensors 29a-29d may be disposed at positions where they can measure the object temperatures of specific portions of the objects to be cooled 40a-40d, rather than the temperature of the temperature adjustment medium 30.

[0026] Temperature sensors 29a-29d measure temperatures, and the measured values ​​are provided to secondary temperature control units 26a, 26b, 26c, and 26d of temperature control unit 20. Secondary temperature control units 26a-26d control the output of multiple heaters, including heaters 28a, 28b, 28c, and 28d, via timing control unit 41 and switches 42a, 42b, 42c, and 42d, so that the measured values ​​of temperature sensors 29a-29d are constant. Heaters 28a-28d are connected to power supply 43 via switches 42a-42d. Power supply 43 may be, for example, an AC power supply in a factory facility, or a DC power supply within a device manufacturing apparatus. Solid-state relays (SSRs) may be used for switches 42a-42d. Switches 42a-42d adjust the energization time of heaters 28a-28d based on the manipulated variable of secondary temperature control units 26a-26d converted into a PWM control signal by timing control unit 41. PWM stands for Pulse Width Modulation, and refers to a method of controlling the energized time (ON period) and de-energized time (OFF period) per unit time. By performing PWM control, it is possible to adjust the heat generated by the heaters 28a to 28d per PWM control cycle. This adjusts the temperature of the temperature control medium 30 passing through the heaters 28a to 28d.

[0027] As described above, the temperature adjustment device 100 includes multiple second temperature sensors (temperature sensors 29a-29d) that measure the temperature of the temperature adjustment medium that has passed through different objects. The second control unit, including the secondary temperature control units 26a-26d, includes multiple control systems that perform secondary temperature adjustment for each of the multiple heaters (heaters 28a-28d) assigned to different objects. FIG. 3 is a block diagram of a secondary temperature control system including the secondary temperature control unit 26a. The secondary temperature control unit 26a calculates a deviation Err2a based on equation (1) using the target temperature SP2a stored in memory 53 and the measurement value PV2a measured by the temperature sensor 29a, and supplies the deviation Err2a to the PID compensator 54a.

[0028] Err2a=SP2a-PV2a (1)

[0029] The PID compensator 54a calculates the manipulated variable MV2a based on the deviation Err2a and supplies it to the timing control unit 41. The timing control unit 41 converts the manipulated variable MV2a into a PWM control signal by physical quantity conversion and further controls the PWM pulse ON timing to control the switch 42a. When the switch 42a changes the power supply time to the heater 28a, the heat generated by the heater 28a changes. As the temperature control medium 30 passes through the heater 28a, heat generated by the heater 28a is transferred to the temperature control medium 30, changing the temperature of the temperature control medium 30. After passing through the heater 28a, the temperature control medium 30 further changes its temperature by recovering heat as it passes through the cooling flow path 6a located inside or around the cooling target 40a. Finally, the temperature of the temperature control medium 30 is measured by the temperature sensor 29a, and the measured value is fed back to the secondary temperature control unit 26a.

[0030] The above has described a block diagram of the secondary temperature control system including secondary temperature control unit 26a. Secondary temperature control units 26b to 26d also have the same block diagram as secondary temperature control unit 26a.

[0031] 4 shows a flowchart of the control process for the timing at which the pulse turns ON in PWM control (pulse ON timing). In S101, timing control unit 41 converts the manipulated variables MV2a to MV2d of secondary temperature control units 26a to 26d into physical quantities corresponding to the periods during which the pulse is ON in PWM control (pulse ON periods) based on equation (2).

[0032] Pulse ON period ON_i = MV2i / 100 × PWM_cyc (2) where i is a symbol (a, b, c, or d) that identifies one of secondary temperature control units 26a to 26d. MV2i is the manipulated variable (unit: %) of the secondary temperature control unit identified by i. PWM_cyc is the PWM control cycle (unit: s).

[0033] In S102, the timing control unit 41 determines the order of the pulse ON periods ON_a to ON_d based on either or both of the length of the pulse ON period and the rated output value of the heater. Hereinafter, for ease of explanation, the order of the pulse ON will be explained as the first pulse (time length ON_a), the second pulse (time length ON_b), the third pulse (time length ON_c), and the fourth pulse (time length ON_d).

[0034] In S103, the timing control section 41 calculates the time T1 using equation (3).

[0035] T1=PWM_cyc-(ON_a+ON_b+ON_c+ON_d) ···(3)

[0036] In S104, the timing control unit 41 determines whether the time T1 is equal to or greater than 0. If T1 is equal to or greater than 0, it is determined that the first pulse (ON_a) to the fourth pulse (ON_d) can be turned on sequentially without overlap within the PWM control period. In this case, the process proceeds to S105. In S105, the timing control unit 41 turns on the switches 42a to 42d sequentially in the order determined in S102.

[0037] On the other hand, if T1 is smaller than 0, the first to fourth pulses cannot be turned on successively without overlapping within the PWM control period. In this case, the process proceeds to S106. In S106, the timing control unit 41 calculates the time T2 using equation (4).

[0038] T2=PWM_cyc-(ON_a+ON_b+ON_c) ···(4)

[0039] In S107, the timing control unit 41 determines whether the time T2 is equal to or greater than 0. If T2 is equal to or greater than 0, it is determined that the first pulse (ON_a) and the second pulse (ON_b) can be turned on sequentially without overlapping within the PWM control period. In this case, the process proceeds to S108. In S108, the timing control unit 41 turns on the switches corresponding to the first pulse (ON_a) and the second pulse (ON_b) sequentially in accordance with the order determined in S102. Thereafter, in S109, the timing control unit 41 simultaneously turns on the switches corresponding to the third pulse (ON_c) and the fourth pulse (ON_d) in accordance with the order determined in S102.

[0040] If it is determined in S107 that T2 is smaller than 0, the process proceeds to S110. In S110, the timing control section 41 calculates the time T3 using equation (5).

[0041] T3=PWM_cyc-(ON_a+ON_b) ···(5)

[0042] In S111, the timing control unit 41 determines whether the time T3 is equal to or greater than 0. If T3 is equal to or greater than 0, it is determined that the first pulse (ON_a) can be turned on within the PWM control period. In this case, the process proceeds to S112. In S112, the timing control unit 41 turns on the switches corresponding to the first pulse (ON_a) in accordance with the order determined in S102. After the first pulse falls, in S113, the timing control unit 41 simultaneously turns on the switches corresponding to the second pulse (ON_b) to the fourth pulse (ON_d) based on the order determined in S102.

[0043] If it is determined in S111 that T3 is smaller than 0, the process proceeds to S114. In S114, the timing control unit 41 simultaneously turns on the switches corresponding to the first pulse (ON_a) to the fourth pulse (ON_d), regardless of the order determined in S102.

[0044] As described above, timing control unit 41 controls the energization times of heaters 28a to 28d based on the manipulated variables of secondary temperature control units 26a to 26d.

[0045] Here, we will explain the problems associated with the generation of peak currents. If there are no thermal disturbances other than the heat generated by the heaters 28a-28d during the period from when the temperature control medium 30 is controlled at a constant temperature by the primary temperature control unit 21 until the temperature sensors 29a-29d detect the temperature of the temperature control medium 30, the manipulated variables of the secondary temperature control units 26a-26d will remain constant. In this case, the pulse-ON period of the PWM control does not change, and S105 can always be selected depending on the target temperatures of the primary and secondary temperature control units. However, as is clear from FIGS. 2 and 3, the heat recovered by the temperature control medium 30 from the cooling targets 40a-40d constantly changes depending on the operating status of the device manufacturing equipment, and therefore the manipulated variables of the secondary temperature control units 26a-26d change. Therefore, depending on the operating status of the device manufacturing equipment, a step other than S105 may be performed.

[0046] Next, an example will be described in which S108 to S109 are selected instead of S105. Fig. 5 shows the current temperature PV1 of the temperature adjustment medium 30 whose temperature is controlled by the primary temperature control system, the currents Ia, Ib, Ic, and Id flowing through the heaters 28a, 28b, 28c, and 28d, and their total current Isum. Here, for simplicity of explanation, it is assumed that the rated output values ​​of the heaters 28a to 28d are the same.

[0047] FIG. 5(A) shows the time series change in temperature PV1 of the temperature control medium 30, which is temperature-controlled by the primary temperature control system. In the figure, the horizontal axis represents time and the vertical axis represents temperature. The dashed lines represent the target temperature SP1 of the primary temperature control unit 21 and the target temperatures SP2a-SP2d of the secondary temperature control units 26a-26d. The solid line represents the temperature PV1 measured by the temperature sensor 22. For ease of explanation, the target temperatures SP2a-SP2d of the secondary temperature control units 26a-26d are all assumed to have the same value, SP2. The primary temperature control system controls the temperature PV1 so that it matches the target temperature SP1. ΔT, which is the deviation between the target temperature SP2 and the temperature PV1, is the temperature to be raised by the secondary temperature control system. The temperature control medium 30 is heated by the heat generated by the heaters 28a-28d and the heat recovered from the objects to be cooled 40a-40d, and the temperature rises by ΔT.

[0048] 5(B) shows the time series change of the current Ia flowing to the heater 28a. In the figure, the horizontal axis represents time and the vertical axis represents current. The current Ia flows through the heater 28a during ON_a of the PWM control cycle (PWM_cyc).

[0049] 5C shows the time series change in the current Ib flowing to the heater 28b. After the heater 28a is energized, the current Ib flows through the heater 28b during ON_b.

[0050] 5(D) shows the time series change in the current Ic flowing through the heater 28c. After the heater 28b is energized, the current Ic flows through the heater 28c during ON_c.

[0051] 5(E) shows the time series change in the current Id flowing through the heater 28d. Similar to the heater 28c, the current Id flows through the heater 28d during ON_d after the energization of the heater 28b is completed.

[0052] FIG. 5(F) shows the time series change in the total current Isum of the currents Ia to Id when heaters 28a to 28d are energized. This figure reveals that a peak current occurs when heaters 28c and 28d are energized at the same time. The power supply specifications for device manufacturing equipment must be determined based on this peak current. Therefore, there is a risk that the power supply capacity of the factory where the device manufacturing equipment is installed will need to be increased in order to accommodate such peak currents.

[0053] 6 is a block diagram of a primary temperature control system including a primary temperature control unit 21 in the first embodiment. A physical quantity converter 50 converts the manipulated variable of secondary temperature control units 26a to 26d into a PWM pulse ON period according to equation (1). A calculator 51 calculates Tco, which indicates a correction time, from the pulse ON period obtained from the physical quantity converter 50, according to the following equations (6) to (8). As is clear from equation (6), Tco represents the excess of the total period (total period) of the pulse ON periods when switches 42a to 42d are turned ON sequentially over the PWM control period.

[0054] Tco=(ON_a+ON_b+ON_c+ON_d)-PWM_cyc ···(6) When Tco≦0, Tco=0 (7) When Tco>0, Tco=Tco (8)

[0055] The physical quantity converter 52 converts the pulse ON period into a first-order temperature correction amount PV1co (correction value) by applying the correction time Tco calculated by the calculator 51 to the following equation (9).

[0056] PV1co=A·Tco ···(9) Here, A is a constant that is determined based on at least one of the rated output values ​​of the heaters 28a to 28d and the flow rate of the temperature adjustment medium 30 flowing through the objects to be cooled 40a to 40d.

[0057] In this way, in one example, the correction value is determined by multiplying the value (Tco) indicating the excess of the total pulse-ON period over the PWM control period by the constant (A). In this way, the primary temperature control unit 21 determines the primary temperature correction amount PV1co based on the total pulse-ON period for each heater. The primary temperature control unit 21 applies the temperature PV1 measured by the temperature sensor 22 and the primary temperature correction amount PV1co to equation (10). Thereafter, the primary temperature control unit 21 applies the target temperature SP1 stored in the memory 53 to equation (11). In this way, the primary temperature control unit 21 constantly calculates the deviation Err1' and supplies it to the PID compensator 54.

[0058] PV1' = PV1 - PV1co (10) Err1'=PV1'-SP1 (11)

[0059] The PID compensator 54 calculates an operation amount MV1' for controlling the cooling by the heat exchanger 24 according to the deviation Err1' and outputs the operation amount MV1' to the control valve 23. As shown in equation (10), the corrected temperature PV1' is a temperature equal to or lower than the temperature PV1 measured by the temperature sensor 22. Therefore, the deviation Err1' calculated by equation (11) is a value equal to or lower than the deviation Err1 calculated from the target temperature SP1 and the temperature PV1 measured by the temperature sensor 22 based on equation (12).

[0060] Err1=PV1-SP1 (12)

[0061] The control valve 23 controls the aperture of the valve 56 via the driver 55 in accordance with the deviation Err1'. Because the deviation Err1' is smaller than the deviation Err1, the aperture of the valve 56 decreases, and the flow rate of the cooling water 27 flowing into the heat exchanger 24 decreases. As a result, the amount of heat exchanged between the temperature control medium 30 and the cooling water 27 in the heat exchanger 24 decreases, and the temperature of the temperature control medium 30 that has passed through the heat exchanger 24 becomes higher than the target temperature SP1. The temperature of the temperature control medium 30 is again measured by the temperature sensor 22, and the measured value is fed back to the primary temperature control unit 21. Note that, in the above example, the primary temperature correction amount PV1co is subtracted from the temperature PV1 measured by the temperature sensor 22 (Equation (10)). However, the same effect can be obtained by adding the primary temperature correction amount PV1co to the target temperature SP1 of the primary temperature control unit 21. Specifically, by substituting equation (10) into equation (11), Err1' = PV1 - (SP1 + PV1co) is obtained. Thus, the primary temperature correction amount PV1co is added to the target temperature SP1 of the primary temperature control unit 21, and the result of this addition is subtracted from the temperature PV1 to obtain the deviation Err1'. In this manner, in this embodiment, the primary temperature control unit 21 corrects the target temperature (SP1) using the correction value (PV1co). That is, as can be seen from FIG. 6, the PID compensator 54 outputs the manipulated variable MV1' for controlling the cooling by the heat exchanger 24 in accordance with the deviation Err1' between the temperature measured by the temperature sensor 22 and the target temperature corrected using the primary temperature correction amount PV1co.

[0062] Furthermore, if the primary temperature correction amount PV1co indicates that any of the multiple secondary temperature control units is unable to control the temperature, the primary temperature control unit 21 may supply the deviation Err1 shown in equation (12) to the PID compensator 54 instead of the deviation Err1' shown in equation (11).

[0063] According to this embodiment, the temperature of the temperature control medium 30 is changed by the primary temperature control system so that the total time that the multiple PWM control pulses in the secondary temperature control system are ON is equal to or shorter than the PWM control period. This allows the timing control unit 41 to always select S105, which sequentially turns ON the switches 42a-42d. This effect will be explained with reference to FIG. 7. FIG. 7 shows the temperature PV1 of the temperature control medium 30, which is temperature-controlled by the primary temperature control system, the currents flowing through the heaters 28a-28d, and their total current. As with FIG. 5, for ease of explanation, the rated output values ​​of the heaters 28a-28d are the same, and the target temperatures SP2a-SP2d of the secondary temperature control units 26a-26d are all the same value, SP2.

[0064] FIG. 7(A) shows the time series change in temperature PV1 of temperature control medium 30, which is temperature-controlled by the primary temperature control system. In the figure, the horizontal axis represents time and the vertical axis represents temperature. The dashed lines represent target temperature SP1 of primary temperature control unit 21 and target temperatures SP2a-SP2d of secondary temperature control units 26a-26d. The solid line represents temperature PV1 measured by temperature sensor 22. The thick line represents corrected temperature PV1'. The corrected temperature PV1' is temperature-controlled by the primary temperature control system so that it matches target temperature SP1. However, because the actual temperature PV1 is always higher than corrected temperature PV1' by the primary temperature correction amount PV1co, the temperature difference ΔT' between target temperature SP2 and temperature PV1 is smaller than the temperature difference ΔT in FIG. 5. The temperature difference ΔT' is the temperature to be raised by the secondary temperature control system, and the temperature is raised by ΔT' by the heat generated by heaters 28a-28d and the heat recovered from the objects to be cooled 40a-40d. If the heat collected from the objects to be cooled 40a to 40d is under the same conditions as in Fig. 5, the amount of heat generated by the heaters 28a to 28d will be small, which means that the ON period of the switches will be shorter.

[0065] 7(B) shows the time series change in the current Ia flowing through the heater 28a. In the figure, the horizontal axis represents time T and the vertical axis represents the current A. The current Ia flows through the heater 28a during a time ON_a' in the PWM control cycle (PWM_cyc).

[0066] 7(C) shows the time series change in the current Ib flowing to the heater 28b. After the heater 28a is turned on, the current Ib flows through the heater 28b for a period ON_b'.

[0067] 7(D) shows the time series change in the current Ic flowing through the heater 28c. The current Ic flows through the heater 28c for a period ON_c' after the heater 28b is turned on.

[0068] 7(E) shows the time series change in the current Id flowing through the heater 28d. The current Id flows through the heater 28d for a period ON_d' after the heater 28c is turned on.

[0069] Fig. 7(F) shows the time series change in the total current Isum of the currents Ia to Id when the heaters 28a to 28d are sequentially energized. This figure shows that the energization times of the heaters 28a to 28d do not overlap, so a peak current like that shown in Fig. 5(F) does not occur.

[0070] As described above, according to this embodiment, the pulse-ON timing in the PWM control of each of the multiple heaters is determined so that the total current value of the multiple heaters does not exceed a predetermined limit value. In the above embodiment, the predetermined limit value is the maximum value of the rated current of each of the multiple heaters. In this embodiment, the pulse-ON timing of each heater and the temperature of the temperature control medium 30 in the primary temperature control system are changed so that the total pulse-ON period of the PWM control is equal to or less than the PWM control period, thereby preventing overlapping of the energization periods of the multiple heaters used for secondary temperature control. This makes it possible to suppress the occurrence of excessive peak currents. Furthermore, since overlapping of the energization periods of the multiple heaters can be prevented without extending the PWM control period, a decrease in the controllability of secondary temperature control can be prevented.

[0071] 11 shows a flowchart of a temperature control method according to one embodiment. The temperature control method includes a first step S1 of performing primary temperature control to cool the temperature control medium 30 based on the deviation between the target temperature SP1 and the current temperature PV1. The temperature control method further includes a second step S2 of performing secondary temperature control to heat the temperature control medium 30 cooled by the primary temperature control by PWM controlling the power supply to each of the heaters 28a-28d.

[0072] Here, the second step S2 includes a step S21 of determining the timing of the pulse-ON period in the PWM control of each of the heaters 28a to 28d so that the total current value of the heaters 28a to 28d does not exceed a predetermined limit value. Furthermore, the first step S1 includes a step S11 of correcting the target temperature SP1. In step S11, a correction value for the target temperature SP1 (primary temperature correction amount PV1co) is determined based on the manipulated variables MV2a to MV2d for the heaters 28a to 28d, respectively, output in the secondary temperature adjustment, and the target temperature SP1 is corrected using the determined correction value.

[0073] Second Embodiment FIG. 8 is a block diagram of a primary temperature control system according to the second embodiment. The difference from the block diagram of the primary temperature control system described in FIG. 6 is that a selector 57 is added between the physical quantity converter 50 and the calculator 51. In the first embodiment, the correction time Tco was calculated based on equations (6) to (8) regardless of the rated output values ​​of the heaters 28a to 28d or the lengths of the pulse ON periods ON_a to ON_d. However, in reality, there are more cases where the rated output values ​​of the heaters 28a to 28d differ, and the energizing current differs depending on the difference in the rated output value of each heater. As an example, suppose that the energizing current of heaters 28c and 28d is H, the energizing current of heater 28b is twice H, and the energizing current of heater 28a is four times H. In this case, because the current flowing through heater 28a is at its maximum value, even if heaters 28b, 28c, and 28d are energized simultaneously, the current will not exceed the current of heater 28a. In this embodiment, as in the first embodiment, the pulse-ON timing in the PWM control of each of the multiple heaters is determined so that the total current value of the multiple heaters does not exceed a predetermined limit value. Here, the predetermined limit value refers to the maximum value of the rated current of each of the multiple heaters, and in this case, the predetermined limit value is four times the value of H, the current flowing through heater 28a.

[0074] The selector 57 selects the longest pulse ON period from among ON_b, ON_c, and ON_d, and outputs the time length as ON_cmp to the calculator 51. The calculator 51 calculates the correction time Tco" based on equations (13) to (15).

[0075] Tco”=(ON_a+ON_cmp)-PWM_cyc ···(13) When Tco”≦0, Tco”=0 (14) When Tco”>0, Tco”=Tco” (15)

[0076] The combination of signals input to the selector 57 is not limited to the signals shown in FIG. 8, and may be changed according to the rated output value of the heater.

[0077] FIG. 9 shows a flowchart of the control process for pulse ON timing in PWM control according to the second embodiment. In FIG. 9, in S101, the timing control unit 41 converts the manipulated variables MV2a to MV2d of the secondary temperature control units 26a to 26d into physical quantities based on the above-described equation (2) into pulse ON periods. In S102, the timing control unit 41 determines the order of the pulse ON periods ON_a to ON_d based on the rated output value of the heater. In S103, the timing control unit 41 calculates the time T1 using the above-described equation (3). In S112, the timing control unit 41 turns ON the switches corresponding to the first pulse (ON_a) in accordance with the order determined in S102. After the first pulse falls, in S113, the timing control unit 41 simultaneously turns ON the switches corresponding to the second pulse (ON_b) to the fourth pulse (ON_d) based on the ON order determined in S102. The contents of S102 and S103 may be changed depending on the rated output value of the heater.

[0078] The effect of this embodiment will be described with reference to Fig. 10. Fig. 10 shows the temperature of the temperature adjustment medium 30 controlled by the primary temperature control system, the currents flowing through the heaters 28a to 28d, and the total current thereof.

[0079] FIG. 10(A) shows the time series change in the temperature of the temperature control medium 30, which is temperature-controlled by the primary temperature control system. In the figure, the horizontal axis represents time and the vertical axis represents temperature. The dashed lines represent the target temperature SP1 of the primary temperature control unit 21 and the target temperatures SP2a to SP2d of the secondary temperature control units 26a to 26d. The solid line (thin line) represents the temperature PV1 measured by the temperature sensor 22, and the solid line (thick line) represents the correction temperature PV1″. The correction temperature PV1″ is temperature-controlled by the primary temperature control system so that it matches the target temperature SP1. However, because the actual temperature PV1 is always higher than the correction temperature PV1″ by the primary temperature correction amount PV1co″, the temperature difference ΔT″ between the target temperature SP2 and the temperature PV1 is smaller than the temperature difference ΔT in FIG. 5.

[0080] FIG. 10(B) shows the time series change in the current Ia flowing through the heater 28a. In the figure, the horizontal axis represents time and the vertical axis represents current. A current H×4 flows through the heater 28a during a time ON_a″ of the PWM control cycle (PWM_cyc).

[0081] FIG. 10(C) shows the time series change in the current Ib flowing to the heater 28b. After the heater 28a is completely energized, a current H×2 flows through the heater 28b for a period ON_b″.

[0082] FIG. 10(D) shows the time series change in the current Ic flowing through the heater 28c. Similar to the heater 28b, the heater 28c flows with a current H for a period ON_c'' after the energization of the heater 28a is completed.

[0083] 10(E) shows the time series change in the current Id flowing through the heater 28d. Similar to the heaters 28b and 28c, the heater 28d receives the current H for the period ON_d'' after the power supply to the heater 28a is completed.

[0084] 10(F) shows the time series change in the total current Isum of the currents Ia to Id when the heaters 28a to 28d are energized. As can be seen from this figure, although the energization times of the heaters 28b to 28d overlap, the total current value does not exceed H×4, which is the energization current of the heater 28a, which has the maximum rated output value, so no excessive peak current occurs.

[0085] As described above, in this embodiment, the total duration of the pulse-ON periods of the secondary temperature control is selectively determined based on the multiple pulse-ON periods and the rated output value of the heater. The temperature of the temperature control medium 30 controlled by the primary temperature control system is then changed based on this total duration so that it is equal to or less than the PWM control period. This prevents excessive peak currents from occurring even if the energization times of multiple heaters in the secondary temperature control overlap. Furthermore, compared to the first embodiment, the pulse-ON timing control process by the timing control unit 41 can be simplified.

[0086] <Embodiment of an article manufacturing method> The article manufacturing method according to an embodiment of the present invention is suitable for manufacturing articles such as microdevices, such as semiconductor devices, and elements having microstructures. The article manufacturing method according to this embodiment includes a step of transferring a pattern of an original onto a substrate using the above-described device manufacturing apparatus (such as an exposure apparatus, an imprint apparatus, or a drawing apparatus), and a step of processing the substrate onto which the pattern has been transferred. Furthermore, this manufacturing method includes other well-known steps (such as oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, dicing, bonding, and packaging). The article manufacturing method according to this embodiment is advantageous over conventional methods in at least one of article performance, quality, productivity, and production cost.

[0087] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0088] 20: Temperature control section, 21: Primary temperature control section, 24: Heat exchanger (cooler), 26a, 26b, 26c, 26d: Secondary temperature control section, 28a, 28b, 28c, 28d: Heater, 30: Temperature control medium, 40a, 40b, 40c, 40d: Cooling object, 41: Timing control section, 100: Temperature control device

Claims

1. a cooler that performs primary temperature control by cooling a temperature control medium; a first control unit that controls the cooler based on a deviation between a target temperature and a current temperature; a plurality of heaters that perform secondary temperature control by providing heat generated in response to supplied power to the temperature control medium cooled by the cooler; a second control unit that controls the supply of power to each of the plurality of heaters by PWM control; Equipped with the second control unit determines timing of a period during which a pulse in PWM control of each of the plurality of heaters is ON so that a total current value of the plurality of heaters does not exceed a predetermined limit value; the first control unit adjusts the target temperature using a correction value based on a total period obtained by adding up the periods of the heaters. A temperature control device characterized by:

2. 2. The temperature adjustment device according to claim 1, wherein the predetermined limit value is a maximum value among the rated currents of the plurality of heaters.

3. 2. The temperature adjusting device according to claim 1, wherein the first control unit determines, as the correction value, a value obtained by multiplying a value indicating an excess of the total period relative to the PWM control cycle by a constant.

4. 4. The temperature control device according to claim 3, wherein the constant is a value based on at least one of a rated output value of each of the plurality of heaters and a flow rate of a temperature control medium flowing through an object to be cooled.

5. Further, a first temperature sensor is provided to measure the temperature of the temperature control medium that has passed through the cooler. the first control unit includes a PID compensator that outputs an operation amount for controlling cooling by the cooler in accordance with a deviation between the temperature measured by the first temperature sensor and a target temperature adjusted using a correction value for adjusting the target temperature. The temperature control device according to any one of claims 1 to 4.

6. Further, a plurality of second temperature sensors are provided to measure the temperatures of the temperature control medium that has passed through different objects, The second control unit includes a plurality of control systems that perform secondary temperature control for each of the plurality of heaters assigned to the mutually different targets, and each of the plurality of control systems: a PID compensator that outputs a manipulated variable for controlling heating by the heater in accordance with a deviation between the temperature measured by the second temperature sensor and a target temperature; a timing control unit that converts the manipulated variable output from the PID compensator into a PWM control signal and controls the timing; The temperature control device according to any one of claims 1 to 5, further comprising:

7. a first step of performing primary temperature control by cooling a temperature control medium based on a deviation between a target temperature and a current temperature; a second step of performing a second temperature control by PWM-controlling the power supply to each of the plurality of heaters to heat the temperature control medium cooled by the first temperature control; and the second step includes determining timings of periods during which pulses in PWM control of each of the plurality of heaters are ON so that a total current value of the plurality of heaters does not exceed a predetermined limit value; the first step includes a step of adjusting the target temperature using a correction value based on a total period obtained by adding up the periods of the heaters. A temperature control method characterized by:

8. A device manufacturing apparatus having a plurality of heat generating portions, The temperature control device according to any one of claims 1 to 6, The plurality of heaters are disposed between the cooler and the plurality of heat generating portions. A device manufacturing apparatus characterized by:

9. 9. The device manufacturing apparatus according to claim 8, which is configured as a lithography apparatus for forming a pattern on a substrate.

10. forming a pattern on a substrate using the device manufacturing apparatus according to claim 9; processing the substrate on which the pattern is formed; and manufacturing an article from the processed substrate.

Images