TWI772745B - Thermal processing apparatus and thermal processing method - Google Patents

Abstract

In the heat treatment apparatus of the present invention, the substrate is heat-treated by placing the substrate on the heat-treatment plate maintained at a predetermined temperature. The change operation conditions of the heat treatment device when changing the set temperature of the heat treatment plate are stored in the memory in advance. When changing the set temperature, the main heater and the intermediate heater are driven according to the memorized change operation conditions. At this time, the temperature change of the heat treatment plate is detected, and the change operation condition stored in the memory unit is changed so that the detected temperature change is close to a predetermined reference waveform.

Description

Heat treatment device and heat treatment method

The present invention relates to a heat treatment device and a heat treatment method for heat treatment of a substrate.

Conventionally, in order to improve the performance of FPD (Flat Panel Display) substrates, semiconductor substrates, optical disk substrates, magnetic disk substrates, etc. used in liquid crystal display devices and organic EL (Electro Luminescence) display devices, Various substrates such as magneto-optical disk substrates, photomask substrates, ceramic substrates, and solar cell substrates are heat-treated using a heat-treating apparatus.

In the heat treatment apparatus, for example, the heat treatment is performed by holding the substrate on a plate member maintained at a predetermined heat treatment temperature for a predetermined time. In the case of sequentially performing heat treatment on a plurality of substrates, it is not limited to set a common heat treatment temperature for the plurality of substrates. When setting different heat treatment temperatures for two substrates that are sequentially heat treated, the temperature of the plate member must be changed after the heat treatment of one substrate and before the heat treatment of the other substrate.

The temperature of the plate member can be changed by various methods. For example, in the temperature changing system described in Patent Document 1, the temperature of the baking plate portion can be raised or lowered by adjusting the driving state of the heater layer included in the baking plate portion (plate member). Furthermore, at this temperature In the temperature change system, the passive cooling plate cooled by the active cooling plate is brought into contact with the baking plate portion through the heat pad, thereby the temperature of the baking plate portion can be greatly lowered.

[Patent Document 1] Japanese Patent No. 5658083

Generally, in the heat treatment apparatus, the operating conditions for changing the temperature of the plate member are predetermined based on the two temperatures before and after the change. However, depending on the temperature of the space in which the heat treatment device is installed, individual differences in the heat treatment device, etc., even if the heat treatment device is operated under predetermined operating conditions, it may be difficult to accurately change the temperature. In this case, if the fine adjustment is repeatedly performed in order to accurately change the temperature of the plate member, the time required for the temperature change becomes longer, and the heat treatment efficiency decreases.

An object of the present invention is to provide a heat treatment apparatus and a heat treatment method capable of suppressing a decrease in heat treatment efficiency accompanying a change in the heat treatment temperature.

(1) A heat treatment apparatus according to one aspect of the present invention heat-treats a substrate, and includes: a plate member for placing the substrate; a heat treatment section for heat-treating the substrate placed on the plate member through the plate member; and a memory A part, which memorizes the operation conditions of the heat treatment part when the temperature of the plate member is changed from the set first temperature to the set second temperature; an operation control part, which makes the heat treatment part operate according to the operation conditions memorized in the memory part operation; a temperature detector that detects the temperature of the plate member; and a condition changing section that changes memory in such a way that the temperature change detected by the temperature detector approaches a predetermined reference waveform when the heat treatment section operates according to the operating conditions The action condition of memory in the department.

In this heat treatment apparatus, the temperature is adjusted to the first by placing the substrate on On the plate member, heat treatment is performed on the placed substrate. Alternatively, the placed substrate is heat-treated by placing the substrate on the plate member adjusted to the second temperature. By sequentially performing heat treatment on a plurality of substrates, the heat treatment corresponding to the first temperature and the heat treatment corresponding to the second temperature are sequentially performed. In this case, it is necessary to change the temperature of the plate member from the first temperature to the second temperature after the heat treatment corresponding to the first temperature and before the heat treatment corresponding to the second temperature.

When the temperature of the plate member is changed from the first temperature to the second temperature, the heat treatment unit operates according to the operating conditions stored in the memory unit. At this time, the temperature change of the detection plate member is changed, and the operating condition memorized in the memory unit is changed so that the detected temperature change is close to the reference waveform.

When the temperature of the plate member is changed again from the first temperature to the second temperature by sequentially processing the plurality of substrates, the heat treatment unit operates according to the operating conditions changed at the previous temperature change. Thereby, the temperature change from the first temperature to the second temperature of the plate member is closer to the reference waveform than at the time of the previous temperature change.

In this way, by changing the operating conditions every time the temperature of the plate member is changed from the first temperature to the second temperature, the temperature of the plate member when the temperature of the plate member is changed from the first temperature to the second temperature is appropriately corrected successively. Variety. Therefore, the adjustment time of the heat treatment apparatus accompanying the change of the heat treatment temperature of the substrate can be appropriately shortened. As a result, it is possible to suppress a decrease in heat treatment efficiency accompanying a change in the heat treatment temperature.

(2) The operating condition may include the value of one or a plurality of control parameters, and the condition changing unit may change one or at least one of the plurality of control parameters stored in the memory unit so that the detected temperature change is close to the reference waveform. 1 value.

In this case, the temperature change from the first temperature to the second temperature of the plate member can be adjusted by a simple process of changing the value of at least one of the one or more control parameters.

(3) The heat treatment unit may be configured to be switchable between a first state in which the plate member is heated or cooled and a second state in which the plate member is not heated and cooled, and one or a plurality of control parameters may include the heat treatment unit. The switching sequence of the first and second states.

In this case, the temperature change from the first temperature to the second temperature of the plate member can be greatly adjusted by changing the switching timing between the first and second states of the heat treatment section.

(4) The heat treatment unit may be configured to be capable of PID control, and one or a plurality of control parameters may include a proportional parameter, an integral parameter, and a derivative of the PID control for changing the temperature of the plate member from the first temperature to the second temperature at least one of the parameters.

In this case, by changing at least one of the values of the proportional parameter, the integral parameter, and the differential parameter, the temperature change from the first temperature to the second temperature of the plate member can be adjusted.

(5) One or more control parameters may include an upper limit of the output of the heat treatment section.

In this case, by changing the upper limit of the output of the heat treatment section, it is possible to finely adjust the temperature change of the plate member from the first temperature to the second temperature.

(6) The condition changing unit may change the operating conditions by changing the temperature detected by the temperature detector at a specific time point during the period in which the temperature of the plate member changes from the first temperature to the second temperature. The rate of change, which is close to the rate of temperature change of the portion of the reference waveform that corresponds to a specific point in time.

In this case, the temperature change from the first temperature to the second temperature of the plate member can be appropriately adjusted based on the temperature change rate of the plate member.

(7) The condition changing unit may change the operating conditions by changing the temperature value of the temperature detected by the temperature detector at a specific time point during the period in which the temperature of the plate member changes from the first temperature to the second temperature, Close to the temperature of the portion of the reference waveform corresponding to a specific time point value.

In this case, the temperature change from the first temperature to the second temperature of the plate member can be appropriately adjusted based on the value of the temperature of the plate member.

(8) The condition changing unit may change the operating conditions so that the amount of overshoot or undershoot with respect to the second temperature generated in the waveform of the detected temperature becomes smaller.

In this case, the temperature change from the first temperature to the second temperature of the plate member can be appropriately adjusted based on the amount of overshoot or the amount of undershoot with respect to the second temperature.

(9) A heat treatment method of another aspect of the present invention is a heat treatment method for a substrate, and includes the steps of: placing the substrate on a plate member; Heat treatment; the operation conditions of the heat treatment part when the temperature of the plate member is changed from the set first temperature to the set second temperature are stored in the memory part; the heat treatment part is operated according to the operation conditions memorized in the memory part; The temperature of the plate member is detected by the temperature detector, and the operating conditions memorized in the memory portion are changed so that the temperature change detected by the temperature detector approaches a predetermined reference waveform when the heat treatment portion operates according to the operating conditions.

In this heat treatment method, the placed substrate is heat treated by placing the substrate on the plate member adjusted to the first temperature. Alternatively, the placed substrate is heat-treated by placing the substrate on the plate member adjusted to the second temperature. By sequentially performing heat treatment on a plurality of substrates, the heat treatment corresponding to the first temperature and the heat treatment corresponding to the second temperature are sequentially performed. In this case, it is necessary to change the temperature of the plate member from the first temperature to the second temperature after the heat treatment corresponding to the first temperature and before the heat treatment corresponding to the second temperature.

When the temperature of the plate member is changed from the first temperature to the second temperature, the heat treatment part It operates according to the operation conditions memorized in the memory unit. At this time, the temperature change of the detection plate member is changed, and the operating condition memorized in the memory unit is changed so that the detected temperature change is close to the reference waveform.

When the temperature of the plate member is changed again from the first temperature to the second temperature by sequentially processing the plurality of substrates, the heat treatment unit operates according to the operating conditions changed during the previous temperature change. Thereby, the temperature change from the first temperature to the second temperature of the plate member is closer to the reference waveform than at the time of the previous temperature change.

In this way, by changing the operating conditions every time the temperature of the plate member is changed from the first temperature to the second temperature, the temperature of the plate member when the temperature of the plate member is changed from the first temperature to the second temperature is appropriately corrected successively. Variety. Therefore, the adjustment time of the heat treatment apparatus accompanying the change of the heat treatment temperature of the substrate can be appropriately shortened. As a result, it is possible to suppress a decrease in heat treatment efficiency accompanying a change in the heat treatment temperature.

(10) It is also possible that the operating conditions include the values of one or more control parameters, and the step of changing the operating conditions includes: changing one or more of the values stored in the memory unit in such a way that the detected temperature change is close to the reference waveform The value of at least one of the control parameters.

In this case, the temperature change from the first temperature to the second temperature of the plate member can be adjusted by a simple process of changing the value of at least one of the one or more control parameters.

According to the present invention, it is possible to suppress a decrease in heat treatment efficiency accompanying a change in the heat treatment temperature.

10: Heat treatment plate

11: Main heater

12: Intermediate heater

13: Heating drive part

19: Temperature sensor

20: Active Cooling Plate

21: Cooling mechanism

22: Cooling drive part

30: Passive Cooling Plate

40: Lifting device

41: Lifting drive part

50: Control device

51: Memory Department

52: Heat Control Department

53: Cooling Control Department

54: Lifting control part

55: Temperature acquisition section

56: Condition Change Department

100: Heat treatment device

400: Substrate processing device

410: Control Department

420: Coating Processing Department

430: Development processing department

440: Heat Treatment Department

450: Substrate transfer device

500: Exposure device

W: substrate

Fig. 1 is a schematic side view showing the structure of a heat treatment apparatus according to an embodiment of the present invention picture.

FIG. 2 is a diagram showing an example of temperature change of a heat-treated plate when a plurality of substrates are sequentially heat-treated.

FIG. 3 is a diagram showing an example of a change operation condition set for every combination of two set temperatures among a plurality of set temperatures.

FIG. 4 is a diagram for explaining a modification example of a modification operation condition for raising the temperature of the heat treatment plate from a low start temperature to a high target temperature.

FIG. 5 is a diagram for explaining a modification example of a modification operation condition for lowering the temperature of the heat treatment plate from a relatively high start temperature to a relatively low target temperature.

FIG. 6 is a diagram for explaining the experimental results related to the change of the set temperature.

FIG. 7 is a flowchart showing an example of a set temperature change process executed in the control device of FIG. 1 .

FIG. 8 is a schematic block diagram showing an example of a substrate processing apparatus including the thermal processing apparatus of FIG. 1 .

Hereinafter, a heat treatment apparatus and a heat treatment method according to an embodiment of the present invention will be described with reference to the drawings. In the following description, the substrate refers to the FPD (Flat Panel Display) substrate, semiconductor substrate, optical disc substrate, magnetic Disc substrates, magneto-optical disk substrates, photomask substrates, ceramic substrates or solar cell substrates, etc. In the following description, as an example of a heat processing apparatus, the heat processing apparatus which heat-processes a board|substrate is demonstrated.

(1) The structure of the heat treatment device

FIG. 1 is a schematic side view showing the configuration of a heat treatment apparatus according to an embodiment of the present invention. As shown in FIG. 1 , the heat treatment apparatus 100 includes a heat treatment plate 10 , an active cooling plate 20 , a passive cooling plate 30 , a lifting device 40 and a control device 50 .

The heat treatment plate 10 is a metal heat transfer plate having a flat cylindrical shape, and has a flat upper surface and a lower surface. The upper surface of the heat treatment plate 10 has an outer diameter larger than the outer diameter of the substrate W to be heat treated. On the upper surface of the heat treatment plate 10, a plurality of proximity balls and the like on the lower surface of the support substrate W are provided. In FIG. 1, the board|substrate W mounted on the heat-processing board 10 is shown by the single-dot chain line.

The heat treatment plate 10 is provided with a main heater 11 , a booster heater 12 and a temperature sensor 19 . The temperature sensor 19 detects the temperature of the upper surface of the heat treatment plate 10, and outputs a detection signal corresponding to the detected temperature to the temperature acquisition unit 55 described below.

Each of the main heater 11 and the intermediate heater 12 is constituted by, for example, a mica heater, a Peltier element, or the like. A heat generating drive unit 13 is connected to the main heater 11 and the intermediate heater 12 . The heat generating drive unit 13 drives the main heater 11 so as to maintain the temperature of the heat treatment plate 10 at a preset temperature (set temperature), for example. Moreover, the heat generating drive part 13 drives the intermediate heater 12 so that the temperature of the heat processing board 10 may rise in a short time, for example.

The active cooling plate 20 is arranged at a lower position than the heat treatment plate 10 and spaced apart from the lower surface of the heat treatment plate 10 by a predetermined distance. The active cooling plate 20 has an upper surface facing the heat treatment plate 10 . On the upper surface of the active cooling plate 20, a thermally conductive sheet (not shown) with high thermal conductivity is disposed.

A cooling mechanism 21 is provided on the active cooling plate 20 . The cooling mechanism 21 is constituted by, for example, a cooling water passage or a Peltier element formed in the active cooling plate 20 . A cooling drive unit 22 is connected to the cooling mechanism 21 . Cooling the driving part 22 to actively cool the temperature of the upper surface of the plate 20 low The cooling mechanism 21 is driven according to the temperature of the heat treatment plate 10 .

The passive cooling plate 30 is supported by the lifting device 40 in the space between the heat treatment plate 10 and the active cooling plate 20 (refer to the hollow arrow in FIG. 1 ). The passive cooling plate 30 is a metal disk-shaped member, and has an upper surface and a lower surface. The upper surface of the passive cooling plate 30 is opposite to the lower surface of the heat treatment plate 10 , and the lower surface of the passive cooling plate 30 is opposite to the upper surface of the active cooling plate 20 . On the upper surface of the passive cooling plate 30, a thermally conductive sheet (not shown) with high thermal conductivity is disposed.

The elevating device 40 includes, for example, an air cylinder. A lift drive unit 41 is connected to the lift device 40 . The elevating drive unit 41 drives the elevating device 40 , for example, so that the passive cooling plate 30 is in contact with the active cooling plate 20 . In this case, the passive cooling plate 30 is cooled by the active cooling plate 20 . Moreover, the raising/lowering drive part 41 drives the raising/lowering apparatus 40 so that the passive cooling plate 30 may contact the heat processing board 10, for example. In this case, the heat treatment plate 10 is cooled by passive cooling of the plate 30 .

The control device 50 controls the operation of each component of the heat treatment apparatus 100 including the heat generating drive unit 13 , the cooling drive unit 22 , and the lift drive unit 41 . Details of the control device 50 will be described below. Furthermore, in the above-mentioned heat treatment apparatus 100, a handover mechanism (not shown) is further provided, and the handover mechanism is used for handover of the substrate W between the heat treatment plate 10 and an external device (such as a transfer robot) of the heat treatment apparatus 100. .

(2) Heat treatment of a plurality of substrates W in the heat treatment apparatus 100

In the heat treatment apparatus 100 of FIG. 1 , the plurality of substrates W are sequentially subjected to heat treatment at a set temperature corresponding to the content of each heat treatment. FIG. 2 is a diagram showing an example of a temperature change of the heat treatment plate 10 when a plurality of substrates W are sequentially heat treated.

In the graph shown in FIG. 2, the vertical axis represents the temperature of the heat-treated plate 10, and the horizontal axis represents the time. In addition, the temperature change of the heat-treated plate 10 is shown by a thick solid line. In this example, for For 28 substrates W, the content of heat treatment is changed in units of 4 substrates W. Therefore, the set temperature of the heat treatment plate 10 is changed in units of four substrates W. As shown in FIG.

Specifically, during each of the period from time point t1 to t2 , the period from time point t5 to t6 , and the period from time point t13 to t14 , the substrate W was performed in a state in which the temperature of the heat treatment plate 10 was maintained at the set temperature of 90° C. the heat treatment. In addition, during the period of time point t3 to t4, the period of time point t7 to t8, and the period of time point t11 to t12, the heat treatment of the substrate W is performed in a state in which the temperature of the heat treatment plate 10 is maintained at the set temperature of 115°C. . Furthermore, during the period from the time point t9 to t10, the heat treatment of the substrate W is performed in a state in which the temperature of the heat treatment plate 10 is maintained at the set temperature of 140°C.

When the untreated substrate W is placed on the heat-treating plate 10 maintained at a predetermined temperature, the temperature of the heat-treating plate 10 is slightly lowered, for example, as indicated by the hollow arrow in FIG. 2 . After that, the temperature of the heat treatment plate 10 is restored to the set temperature in a relatively short time by continuing to drive the main heater 11 of FIG. 1 .

As surrounded by a single-dotted chain line in FIG. 2 , when the temperature of the heat-treating plate 10 changes greatly with the change of the set temperature, it is difficult to adjust the temperature in a short time only by adjusting the output of the main heater 11 . circumstances of change. Therefore, in this example, when the set temperature rises, the intermediate heater 12 is driven immediately after the change is started. Moreover, based on the detection signal of the temperature sensor 19, PID (proportional-integral-derivative) control with respect to the main heater 11 is performed. Furthermore, the upper limit of the output of the main heater 11 is adjusted. On the other hand, when the set temperature is lowered, the heat treatment plate 10 is cooled by the passive cooling plate 30 immediately after the change is started. Moreover, based on the detection signal of the temperature sensor 19, PID control regarding the main heater 11 is performed.

The operation of the heat treatment apparatus 100 for changing the temperature of the heat treatment plate 10 from one set temperature to another set temperature when there are a plurality of predetermined set temperatures The conditions can be obtained by simulation, experiment, or the like. Therefore, in the heat treatment plate 10, an operation condition (hereinafter, referred to as a change operation condition) when the setting temperature is changed is preset for each combination of two setting temperatures among the plurality of setting temperatures.

FIG. 3 is a diagram showing an example of a change operation condition set for every combination of two set temperatures among a plurality of set temperatures. In the following description, the set temperature before the change is appropriately called the start temperature, and the set temperature after the change is appropriately called the target temperature.

The value of the heating stop parameter is included in the change operation condition. The heating stop parameter is a control parameter of the intermediate heater 12, and indicates the temperature of the heat treatment plate 10 for which heating should be stopped. In other words, the value of the heating stop parameter indicates the timing of switching from the ON state in which the intermediate heater 12 generates heat to the OFF state in which the intermediate heater 12 does not generate heat when the set temperature is changed (increased). In FIG. 3, the heating stop parameter is described as "heating stop". The value of the heating stop parameter in FIG. 3 is expressed as a value obtained by subtracting the temperature at which heating should be stopped from the target temperature.

In addition, the value of the parameter regarding the PID control of the main heater 11 is included in the change operation condition. Moreover, the value of the upper limit parameter which shows the upper limit of the output of the main heater 11 is included in the change operation condition. In FIG. 3, the upper limit parameter is described as "heater upper limit". The value of the upper limit parameter is represented by, for example, a ratio (%) to the upper limit of the output allowed by the rated output of the main heater 11 .

Furthermore, the value of the cooling stop parameter is included in the change operation condition. The cooling stop parameter is a control parameter related to the lifting device 40, and indicates the temperature of the heat treatment plate 10 whose cooling should be stopped. In other words, the value of the cooling stop parameter indicates the timing of switching from the contact state in which the passive cooling plate 30 is in contact with the heat treatment plate 10 to the non-contact state in which the passive cooling plate 30 is separated from the heat treatment plate 10 when the set temperature is changed (when it is lowered). In FIG. 3, the cooling stop parameter is described as "cooling stop". The value of the cooling stop parameter in FIG. 3 is represented as a value obtained by subtracting the target temperature from the temperature of the heat treatment plate 10 whose cooling should be stopped.

According to the example of FIG. 3 , the change operation conditions corresponding to the change from the start temperature of 90°C to the target temperature of 115°C include the heating stop parameter "5", the proportional parameter "0.2", the integral parameter "15", the differential parameter "3" and The upper limit parameter "80" (%). In addition, the change operation conditions corresponding to the change from the start temperature of 115°C to the target temperature of 90°C include the cooling stop parameter "5", the proportional parameter "0.2", the integral parameter "15", the differential parameter "3", and the upper limit parameter "80" ” (%).

However, depending on the temperature of the space in which the heat treatment apparatus 100 is installed, the individual differences of the heat treatment apparatus 100, and the like, the preset change operation conditions are not necessarily suitable. Therefore, in this embodiment, every time the set temperature of the heat treatment plate 10 is changed, the change operation conditions are changed so that the temperature change of the heat treatment plate 10 at the time of the change is close to the ideal reference waveform. The ideal reference waveform is determined based on, for example, the configuration of the heat treatment plate 10 , the heating capacity of the main heater 11 and the intermediate heater 12 , and the cooling capacity of the active cooling plate 20 and the passive cooling plate 30 .

In the example of FIG. 2, for example, when the set temperature is changed during the time point t2 to t3, when the temperature change of the heat treatment plate 10 produces a large overshoot, the overshoot is reduced in a manner to reduce the overshoot. Change the operating conditions to change. After that, when the set temperature is changed during the period from time point t6 to t7, the heat treatment apparatus 100 operates according to the changed operation condition after the change. As a result, the time required for changing the set temperature is shortened compared to when the set temperature is changed during the period from time t2 to t3. Furthermore, when the set temperature is changed during the period from the time points t6 to t7, the change operation conditions are also changed similarly to when the set temperature is changed during the period from the time points t2 to t3. Thereby, when a change from the set temperature of 90° C. to the set temperature of 115° C. occurs at a time point later than the time point t7 , the time required for the change is further shortened.

Furthermore, in the example of FIG. 2 , for example, when the set temperature is changed during the time point t4 to t5, when the temperature change of the heat treatment plate 10 generates a large undershoot, the undershoot can be made smaller. The method will change the operating conditions to change. After that, during the period from time point t12 to t13 When the set temperature inside is changed, the heat treatment apparatus 100 operates according to the changed operation conditions after the change. As a result, the time required for changing the set temperature is shortened compared to the time when the set temperature is changed during the period from time t4 to t5. Furthermore, when the set temperature is changed during the period from time point t12 to t13, the change operation condition is changed similarly to the time point when the set temperature is changed during the period from time point t4 to t5. Thereby, when a change from the start temperature of 115° C. to the target temperature of 90° C. occurs at a time point later than the time point t13 , the time required for the change is further shortened.

As described above, in the heat treatment apparatus 100, every time the set temperature of the heat treatment plate 10 is changed, the operation conditions are changed. Thereby, the time required for changing the set temperature is shortened sequentially. As a result, it is possible to suppress a decrease in heat treatment efficiency accompanying a change in the heat treatment temperature.

(3) Specific example of changing the operating conditions

FIG. 4 is a diagram for explaining a modification example of a modification operation condition for increasing the temperature of the heat treatment plate 10 from a lower start temperature ST to a higher target temperature TT. In the graph in the upper stage of FIG. 4 , the temperature change of the heat treatment plate 10 detected when the set temperature is changed is indicated by a thick solid line. In addition, a reference waveform predetermined in accordance with the set temperature change is indicated by a single-dot chain line. In this example, as shown in the reference waveform, it is desirable to change the set temperature from the time point t20 to the time point t22.

In order to change the change operation conditions, the temperature change of the heat treatment plate 10 at a predetermined specific time point (in this example, an intermediate time point between the time points t20 and t22) t21 during the period from the time point t20 to the time point t22 is obtained. rate (in this case, the rate of rise). The acquired rate of change is compared with the rate of change of the reference waveform at a specific time point t21. In addition, the temperature value of the heat treatment plate 10 at the specific time point t21 is obtained, and the obtained temperature value is compared with the temperature value of the reference waveform at the specific time point t21. Furthermore, the overshoot amount OS of the temperature of the heat-treated plate 10 is obtained.

When the difference between the acquired change rate and the change rate of the reference waveform is outside the allowable range predetermined for the change rate as a result of comparing the change rate, it is desirable to change the change operation condition. Therefore, when the difference in the rate of change is outside the allowable range and the absolute value of the acquired rate of change is lower than the absolute value of the rate of change of the reference waveform, it is necessary to increase the amount of heat supplied to the heat treatment plate 10 Change the change operation condition. On the other hand, when the difference in the rate of change is outside the allowable range and the absolute value of the acquired rate of change is higher than the absolute value of the rate of change of the reference waveform, it is necessary to reduce the amount of heat supplied to the heat treatment plate 10 In this way, the change action conditions are changed.

In addition, when the difference between the acquired temperature value and the temperature value of the reference waveform is outside the predetermined allowable range for the temperature value as a result of comparing the temperature values, it is desirable to change the change operation condition. Therefore, when the difference between the temperature values is outside the allowable range and the acquired temperature value is lower than the temperature value of the reference waveform, it is necessary to change the change operation conditions so as to increase the amount of heat supplied to the heat treatment plate 10 . On the other hand, when the difference between the temperature values is outside the allowable range and the acquired temperature value is higher than the temperature value of the reference waveform, it is necessary to change the operating conditions so as to reduce the amount of heat supplied to the heat treatment plate 10 make changes.

Furthermore, when the acquired overshoot amount OS exceeds a predetermined allowable range for the overshoot amount, it is desirable to change the change operation condition. Therefore, when the overshoot amount OS exceeds the allowable range, it is necessary to change the operation conditions for changing so as to reduce the amount of heat supplied to the heat treatment plate 10 .

In the middle part of FIG. 4, the state of the intermediate heater 12 according to the preset change operation conditions is shown. In this example, the intermediate heater 12 is maintained in the ON state from the time point t20 to the time point t22. In the case of reducing the amount of heat supplied to the heat treatment plate 10, as long as the As indicated by the hollow arrow a11 , the timing for switching the intermediate heater 12 to the off state may be advanced by changing the value of the heating stop parameter. On the other hand, when it is necessary to increase the amount of heat supplied to the heat treatment plate 10, as shown by the hollow arrow a12 in FIG. 4, the intermediate heater 12 is switched off by changing the value of the heating stop parameter. The timing of the state can be delayed.

In the lower part of FIG. 4, the output waveform of the main heater 11 according to the preset change operation condition is shown. In this example, the output of the main heater 11 is increased from the time point t20 in order to increase the temperature of the heat treatment plate 10 . After that, the output is adjusted according to the temperature of the heat treatment plate 10 by PID control according to changing operating conditions. In the case of reducing the amount of heat supplied to the heat treatment plate 10, as shown by the hollow arrow a13 in FIG. 4, for example, by changing the proportional parameter of the PID control to make it larger, the output waveform of the main heater 11 can be made larger as a whole. can be lowered. Alternatively, as shown by the hollow arrow a14 in FIG. 4 , for example, the upper limit of the output of the main heater 11 may be lowered by changing the upper limit parameter to make it smaller.

On the other hand, when it is necessary to increase the amount of heat supplied to the heat treatment plate 10, as shown by the hollow arrow a15 in FIG. The output waveform as a whole can become high. Alternatively, as shown by the hollow arrow a16 in FIG. 4 , for example, the upper limit of the output of the main heater 11 may be increased by changing the upper limit parameter to increase it.

FIG. 5 is a diagram for explaining a modified example of a modified operation condition for lowering the temperature of the heat treatment plate 10 from a relatively high start temperature ST to a relatively low target temperature TT. In the graph of the upper stage of FIG. 5 , similarly to the example of FIG. 4 , the temperature change of the heat treatment plate 10 detected when the set temperature is changed is indicated by a thick solid line. In addition, a reference waveform predetermined in accordance with the set temperature change is indicated by a single-dot chain line. In this example, as shown by the reference waveform, it is desirable to perform the temperature change of the heat-treated plate 10 from the time point t30 to the time point t32.

In order to change the change operation conditions, the temperature change of the heat treatment plate 10 at a predetermined specific time point (in this example, the intermediate time point between time points t30 and t32) t31 during the period from time point t30 to time point t32 is acquired. rate (in this case, the rate of descent). The acquired rate of change is compared with the rate of change of the reference waveform at a specific time point t31. In addition, the temperature value of the heat treatment plate 10 at the specific time point t31 is acquired, and the acquired temperature value is compared with the temperature value of the reference waveform at the specific time point t31. Furthermore, the impulse US under the temperature of the heat-treated plate 10 is obtained.

As a result of the comparison of the rate of change, if the difference of the rate of change is outside the allowable range, and the absolute value of the rate of change obtained is lower than the absolute value of the rate of change of the reference waveform, it is necessary to increase the amount of heat removed from the heat treatment plate 10 , and change the change operation condition. On the other hand, if the difference in the rate of change is outside the allowable range, and the absolute value of the rate of change obtained is higher than the absolute value of the rate of change of the reference waveform, it is necessary to reduce the amount of heat removed from the heat treatment plate 10, Change the change operation condition.

Furthermore, as a result of the comparison of the temperature values, if the difference between the temperature values is outside the allowable range and the acquired temperature value is lower than the temperature value of the reference waveform, the operation must be changed in such a way as to reduce the amount of heat removed from the heat treatment plate 10. conditions are changed. On the other hand, if the difference between the temperature values is outside the allowable range and the acquired temperature value is higher than the temperature value of the reference waveform, it is necessary to change the operating conditions so as to increase the amount of heat removed from the heat treatment plate 10 .

Furthermore, when the acquired undershoot amount US exceeds a predetermined allowable range for the undershoot amount, it is desirable to change the change operation condition. Therefore, when the undershoot US exceeds the allowable range, it is necessary to change the operating conditions so as to reduce the amount of heat removed from the heat treatment plate 10 .

In the middle section of Fig. 5, it shows the passive action according to the preset change action conditions. The state of the cooling plate 30 . In this example, the passive cooling plate 30 is maintained in the contact state from the time point t30 to the time point t32. When it is necessary to reduce the amount of heat removed from the heat treatment plate 10, as shown by the hollow arrow a21 in FIG. 5, by changing the value of the cooling stop parameter, the timing of switching the passive cooling plate 30 to the non-contact state is advanced. That's it. On the other hand, in the case of increasing the amount of heat removed from the heat treatment plate 10, as shown by the hollow arrow a22 in FIG. 5, the passive cooling plate 30 is switched to the non-cooling stop parameter by changing the value of the cooling stop parameter. The timing of the contact state can be delayed.

The lower part of FIG. 5 shows the output waveform of the main heater 11 according to the preset change operation conditions. In this example, the output of the main heater 11 is lowered from the time point t30 in order to lower the temperature of the heat treatment plate 10 . After that, the output is adjusted according to the temperature of the heat treatment plate 10 by PID control according to changing operating conditions. In the case of reducing the amount of heat supplied to the heat treatment plate 10, as shown by the hollow arrow a23 in FIG. 5, for example, by changing the proportional parameter of the PID control to make it larger, the output waveform of the main heater 11 can be made larger as a whole. can be lowered.

On the other hand, when it is necessary to increase the amount of heat supplied to the heat treatment plate 10, as shown by the hollow arrow a24 in FIG. The output waveform as a whole can become high.

FIG. 6 is a diagram for explaining the experimental result regarding the change of the set temperature. The present inventors changed the set temperature of the heat treatment plate 10 from 90° C. to 140° C. by operating the heat treatment apparatus 100 based on the changed operation conditions of FIG. 3 . As a result, as shown by the thick solid line in the upper part of FIG. 6 , the temperature of the heat-treated plate 10 rises at a substantially constant speed during the period from time t40 to time t41 along the reference waveform shown by the single-dot chain line. However, after the time point t41, a relatively large overshoot occurs.

Therefore, as shown in the middle part of FIG. 6 , the inventors changed the value of the heating stop parameter in the change operation condition corresponding to the change from the start temperature of 90° C. to the target temperature of 140° C. in FIG. 3 . Changed from "1" to "5". This change means to advance the timing of switching the intermediate heater 12 to the OFF state after the intermediate heater 12 is turned on in order to increase the temperature of the heat treatment plate 10 .

After that, based on the changed operating conditions after the change, the heat treatment apparatus 100 was operated again, and the set temperature of the heat treatment plate 10 was changed from 90°C to 140°C. As a result, as shown in the lower part of FIG. 6 , the temperature of the heat-treated plate 10 changes along the reference waveform, and the amount of overshoot decreases.

(4) Control device 50

As shown in FIG. 1 , the control device 50 includes a memory unit 51 , a heat generation control unit 52 , a cooling control unit 53 , a lift control unit 54 , a temperature acquisition unit 55 , and a condition change unit 56 as functional units. The control device 50 includes a CPU (Central Processing Unit, central processing unit) (central computing processing device), a RAM (Random Access Memory, random access memory), and a ROM (Read Only Memory, read only memory). Each of the above-mentioned functional parts is realized by the CPU executing the computer program stored in the ROM or other storage medium. Furthermore, a part or all of the functional components of the control device 50 may be realized by hardware such as electronic circuits.

The memory unit 51 stores a plurality of change operation conditions set for every combination of two set temperatures among the plurality of set temperatures. The heat generation control unit 52 controls the heat generation drive unit 13 to operate according to the change operation conditions stored in the memory unit 51 when changing the set temperature of the heat treatment plate 10 to increase. The cooling control unit 53 controls the cooling drive unit 22 so as to cool the active cooling plate 20 while the heat treatment apparatus 100 is powered on. The elevating control unit 54 controls the elevating device 40 so as to operate according to the change operation conditions stored in the memory unit 51 when changing the set temperature of the heat treatment plate 10 to drop.

The temperature acquisition unit 55 acquires the temperature of the heat treatment plate 10 when the set temperature is changed based on the detection signal output from the temperature sensor 19 . More specifically, the temperature acquisition unit 55 acquires the temperature change by sampling the detection signal output from the temperature sensor 19 at a fixed period.

The condition changing unit 56 changes the changing operation condition memorized in the memory unit 51 so that the temperature change detected by the temperature sensor 19 when the set temperature of the heat treatment plate 10 is changed is close to a predetermined reference waveform.

In addition, the heat processing apparatus 100 is provided with the operation part which is not shown in figure. The user can memorize the initial change operation conditions in the memory unit 51 by operating the operation unit. That is, the user can initially change the setting of the operating conditions.

(5) Set temperature change processing

The operation of the heat treatment apparatus 100 accompanying the change of the operation conditions is performed by executing the following set temperature change processing by the control device 50 of FIG. 1 . FIG. 7 is a flowchart showing an example of a set temperature change process executed in the control device 50 of FIG. 1 . In the following description, the overshoot amount and the undershoot amount are collectively referred to as impulse. The set temperature change process is started by turning on the power of the heat treatment apparatus 100 .

First, the heat generation control unit 52 and the lift control unit 54 of FIG. 1 determine whether or not the set temperature of the heat treatment plate 10 should be changed (step S11 ). This determination is performed based on, for example, whether or not any one of the heat generation control unit 52 and the elevation control unit 54 has received a signal instructing a change in the set temperature from outside the heat treatment apparatus 100 .

When the set temperature should not be changed, the heat generation control unit 52 and the lift control unit 54 return to the process of step S11. On the other hand, when the set temperature should be changed, the heat generation control unit 52 or the lift control unit 54 reads the corresponding change of the set temperature from the memory unit 51 in FIG. 1 . to change the operating conditions (step S12).

Next, the heat generation control unit 52 or the lift control unit 54 controls the heat generation drive unit 13 or the lift drive unit 41 based on the changed operating conditions to adjust the temperature of the heat treatment plate 10 (step S13 ). The temperature acquisition unit 55 acquires the temperature change of the heat treatment plate 10 when the set temperature of the heat treatment plate 10 is changed (step S14).

When the set temperature change of the heat treatment plate 10 is completed, the condition changing unit 56 determines whether the temperature change rate at a specific time point during the set temperature change is outside the predetermined allowable range based on the acquired temperature change (step S15).

When the temperature change rate deviates from the allowable range, the condition changing unit 56 calculates the difference between the acquired temperature change rate and the reference waveform change rate at a specific time point based on the acquired temperature change (step S16 ). On the other hand, when the temperature change rate is within the allowable range, the condition changing unit 56 determines, based on the acquired temperature change, whether the temperature value at the specific time point during the change of the set temperature is outside the predetermined allowable range (step S17 ). ).

When the temperature value deviates from the allowable range, the condition changing unit 56 calculates the difference between the acquired temperature value at a specific time point and the temperature value of the reference waveform based on the acquired temperature change (step S18 ). On the other hand, when the temperature value is within the allowable range, the condition changing unit 56 determines whether the impulse generated by the change of the set temperature is outside the predetermined allowable range based on the acquired temperature change (step S19).

When the impulse deviates from the allowable range, the condition changing unit 56 calculates the difference between the acquired impulse and the impulse of the reference waveform based on the acquired temperature change (step S20 ). On the other hand, when the impulse is within the allowable range, the heat generation control unit 52 and the lift control unit 54 return to the process of step S11.

After the processing of the above-mentioned steps S16, S18, and S20, the condition changing unit 56 is based on the The calculated change rate, the temperature value, or the difference of the impulse determines the parameter to be changed in the change operation condition (step S21). For example, the condition changing unit 56 determines the parameter to be changed based on the level of the calculated difference. Specifically, when the level of the difference is high, the condition changing unit 56 determines the heating stop parameter or the cooling stop parameter as the parameter to be changed. In addition, the condition changing unit 56 determines the proportional parameter of the PID control as the parameter to be changed when the level of the difference is moderate. Furthermore, when the level of the difference is low, the condition changing unit 56 determines the upper limit parameter as the parameter to be changed.

Next, the condition changing unit 56 changes the parameter according to a predetermined method with respect to the determined parameter (step S22). For example, the condition changing unit 56 changes the parameter by a predetermined value with respect to the determined parameter. After that, the heat generation control unit 52 and the lift control unit 54 return to the process of step S11.

In the above-mentioned set temperature change processing, a part of the processing in steps S15, S17, and S19 may be omitted. In this case, the calculation processing of the difference accompanying the omitted processing is also omitted.

(6) Effect

As described above, when the heat treatment plate 10 is changed from one set temperature to another set temperature, the heat treatment apparatus 100 operates according to the change operation conditions stored in the memory unit 51 . At this time, the temperature change of the heat treatment plate 10 is detected, and the change operation condition is changed so that the detected temperature change approaches the reference waveform corresponding to the change from the one set temperature to the other set temperature.

Thereby, when the temperature of the heat treatment plate 10 is changed again from one set temperature to another set temperature, the heat treatment apparatus 100 operates according to the changed operation conditions after the change in the previous temperature change. Thereby, the temperature change of the heat-treatment plate 10 is closer to the reference waveform than when the previous set temperature was changed.

In this way, whenever the set temperature of the heat treatment plate 10 is changed, the temperature change of the heat treatment plate 10 at the time of changing the set temperature is appropriately corrected successively. Therefore, the adjustment time of the heat treatment apparatus 100 accompanying the change of the heat treatment temperature of the substrate W can be appropriately shortened. As a result, it is possible to suppress a decrease in heat treatment efficiency accompanying a change in the heat treatment temperature.

(7) A substrate processing apparatus including the thermal processing apparatus 100 of FIG. 1

FIG. 8 is a schematic block diagram showing an example of a substrate processing apparatus including the thermal processing apparatus 100 of FIG. 1 . As shown in FIG. 8 , the substrate processing apparatus 400 is provided adjacent to the exposure apparatus 500 , and includes a control unit 410 , a coating processing unit 420 , a developing processing unit 430 , a heat treatment unit 440 , and a substrate conveying device 450 . The heat treatment unit 440 includes a plurality of heat treatment apparatuses 100 of FIG. 1 for heating the substrate W, and a plurality of cooling plates (not shown) for cooling the substrate W only.

The control unit 410 includes, for example, a CPU, a memory, or a microcomputer, and controls the operations of the coating processing unit 420 , the developing processing unit 430 , the heat treatment unit 440 , and the substrate transfer device 450 .

When the substrate processing apparatus 400 processes the substrate W, the substrate transport apparatus 450 transports the substrate W between the coating processing unit 420 , the developing processing unit 430 , the thermal processing unit 440 , and the exposure apparatus 500 .

The coating processing unit 420 forms a resist film on one surface of the unprocessed substrate W (coating processing). The exposure process is performed in the exposure apparatus 500 with respect to the board|substrate W after the coating process by which the resist film was formed. The development processing unit 430 performs development processing of the substrate W by supplying a developing solution to the substrate W subjected to the exposure processing by the exposure device 500 . The heat treatment part 440 is a coating process performed by the coating process part 420, a development process performed by the development process part 430, and an exposure device. The heat treatment of the substrate W is performed before and after the exposure treatment performed at 500 .

Furthermore, the coating processing part 420 may also form an anti-reflection film on the substrate W. In this case, a processing unit for performing adhesion strengthening treatment may also be provided in the heat treatment section 440 to improve the adhesion between the substrate W and the antireflection film. In addition, the coating processing unit 420 may also form a resist cover film on the substrate W to protect the resist film formed on the substrate W. As shown in FIG.

As described above, in the plurality of heat treatment apparatuses 100 of the heat treatment section 440, the above-described set temperature change process is performed. As a result, when the plurality of substrates W are sequentially heat-treated at different set temperatures, the temperature of the heat-treated plate 10 can be appropriately adjusted in a short time. As a result, the manufacturing efficiency of the board|substrate W improves.

(8) Other Embodiments

(a) In the above-described embodiment, the heat treatment apparatus 100 having a configuration for heating the heat treatment plate 10 and a configuration for cooling the heat treatment plate 10 has been described, but the present invention is not limited to this. The heat treatment apparatus 100 may not have a structure for cooling the heat treatment plate 10 (in the above example, the active cooling plate 20, the passive cooling plate 30, and the lifting device 40). Alternatively, the heat treatment apparatus 100 may not have a configuration for heating the heat treatment plate 10 (in the above example, the main heater 11 and the intermediate heater 12). In this case, the time required for adjustment when raising or lowering the set temperature of the heat treatment apparatus 100 can also be shortened.

(b) In the heat treatment apparatus 100 , the upper surface of the heat treatment plate 10 may be divided into a plurality of regions, respectively, and a configuration for heating the portion may be provided so as to correspond to each region. That is, the main heater 11 , the intermediate heater 12 , and the heat generating drive unit 13 may be provided for each of the plurality of regions of the heat treatment plate 10 . Alternatively, the main heater 11 and the intermediate heater 12 may be provided for each of a plurality of regions of the heat treatment plate 10, and the heat generating drive unit 13 may be configured to It is driven separately from the plurality of main heaters 11 and the intermediate heaters 12 .

In this case, in the memory part 51, the operating conditions may be changed in memory for each of the plurality of regions of the heat treatment plate 10. For example, the condition changing unit 56 may change a plurality of parameters for changing the operating conditions corresponding to all the regions so that the temperature changes of the plurality of regions of the heat treatment plate 10 are close to the reference waveform when the temperature is changed, for example. According to such a configuration, more detailed temperature adjustment can be performed on a plurality of regions on the upper surface of the heat-treated plate 10 . Furthermore, in this example, the temperature change obtained when the set temperature is changed for one of the plurality of regions may be used as the reference waveform.

(c) In the above-described embodiment, the main heater 11 and the intermediate heater 12 are provided in the heat treatment plate 10, but the present invention is not limited to this. When the main heater 11 is configured to be able to raise the temperature of the heat treatment plate 10 in a short time, the intermediate heater 12 may not be provided.

(9) Correspondence between the constituent elements of the technical solution and the elements of the embodiment

Hereinafter, an example of the correspondence between the constituent elements of the technical solution and the elements of the embodiment will be described. In the above embodiment, the heat treatment device 100 is an example of a heat treatment device, the heat treatment plate 10 is an example of a plate member, the main heater 11, the intermediate heater 12, the heat generating drive part 13, the active cooling plate 20, the passive cooling plate 30, and the lift The device 40 is an example of a heat treatment section, the memory section 51 is an example of a memory section, the heat generation control section 52, the cooling control section 53 and the lift control section 54 are examples of an operation control section, and the temperature sensor 19 is an example of a temperature detector. The temperature acquiring unit 55 and the condition changing unit 56 are examples of the condition changing unit.

In addition, in the above-described embodiment, the intermediate heater 12 is in the ON state or the passive cooling plate 30 is in the contact state, which is an example of the heat treatment portion being in the first state. In addition, the intermediate heater 12 is in the OFF state and the passive cooling plate 30 is in the non-contact state, which is an example of the heat treatment part being in the second state.

As each constituent element of the technical solution, various other elements having the structure or function described in the technical solution can also be used.

10: Heat treatment plate

11: Main heater

12: Intermediate heater

13: Heating drive part

19: Temperature sensor

20: Active Cooling Plate

21: Cooling mechanism

22: Cooling drive part

30: Passive Cooling Plate

40: Lifting device

41: Lifting drive part

50: Control device

51: Memory Department

52: Heat Control Department

53: Cooling Control Department

54: Lifting control part

55: Temperature acquisition section

56: Condition Change Department

100: Heat treatment device

W: substrate

Claims (9)

A heat treatment apparatus for heat-treating a substrate, and comprising: a plate member for placing the substrate; a heat treatment unit for heat-treating the substrate placed on the plate member through the plate member; and a memory unit for storing a memory an operation condition of the heat treatment part when the temperature of the plate member is changed from the set first temperature to the set second temperature; an operation control part that makes the heat treatment part operate according to the operation condition memorized in the memory part; a temperature detector for detecting the temperature of the plate member; and a condition changing section for changing the temperature detected by the temperature detector when the heat treatment section operates according to the operating conditions to be close to the change from the first temperature to the second temperature The form of the predetermined reference waveform at 2 temperatures, after changing the temperature of the plate member from the first temperature to the second temperature, and changing the temperature of the plate member from the first temperature to the second temperature again. Before changing the temperature, the operating conditions stored in the memory unit are changed; the condition changing unit performs the changing of the operating conditions in the following manner, that is, during the specified period during which the temperature of the plate member changes from the first temperature to the second temperature The value of the temperature detected by the above-mentioned temperature detector at the time point is close to the value of the temperature of the part corresponding to the above-mentioned specific time point in the above-mentioned reference waveform. The heat treatment device of claim 1, wherein the above-mentioned operating conditions include the value of one or more control parameters, The condition changing unit changes the value of at least one of the one or a plurality of control parameters stored in the memory unit so that the detected temperature change is close to the reference waveform. The heat treatment apparatus according to claim 2, wherein the heat treatment section is configured to be capable of switching between a first state in which the plate member is heated or cooled and a second state in which the plate member is not heated or cooled, and the one or more control parameters The switching sequence of the above-mentioned first and second states of the above-mentioned heat treatment portion is included. The heat treatment apparatus according to claim 2 or 3, wherein the heat treatment section is configured to be capable of PID control, and the one or a plurality of control parameters include the above for changing the temperature of the plate member from the first temperature to the second temperature At least one of proportional parameters, integral parameters and differential parameters of PID control. The heat treatment apparatus of claim 2 or 3, wherein the one or more control parameters include an upper limit of the output of the heat treatment section. The heat treatment apparatus according to any one of claims 1 to 3, wherein the condition changing unit changes the operating conditions in a period during which the temperature of the plate member changes from the first temperature to the second temperature The temperature change rate detected by the temperature detector at the specific time point is close to the temperature change of the part corresponding to the specific time point in the reference waveform Rate. The heat treatment apparatus according to any one of claims 1 to 3, wherein the condition changing unit changes the operating conditions such that the amount of overshoot with respect to the second temperature generated in the waveform of the detected temperature or the undershoot becomes smaller. A heat treatment method, comprising the steps of: placing a substrate on a plate member; subjecting the placed substrate to heat treatment by a heat treatment section through the plate member; When the temperature is changed from the set first temperature to the set second temperature, the operating conditions of the heat treatment part are stored in the memory part; the heat treatment part is operated according to the operating conditions stored in the memory part; by temperature detection The temperature of the plate member is detected by a device; and the temperature change detected by the temperature detector when the heat treatment section operates according to the operating conditions is close to a predetermined reference when the temperature changes from the first temperature to the second temperature. The waveform type is changed by the condition changing unit after changing the temperature of the plate member from the first temperature to the second temperature and before changing the temperature of the plate member from the first temperature to the second temperature again The operating conditions memorized in the memory unit; the condition changing unit changes the operating conditions in the following manner, that is, at a specific time point during the period during which the temperature of the plate member changes from the first temperature to the second temperature The value of the temperature detected by the above-mentioned temperature detector is close to the value of the temperature of the part corresponding to the above-mentioned specific time point in the above-mentioned reference waveform. The heat treatment method according to claim 8, wherein the operating conditions include the values of one or more control parameters, and the step of changing the operating conditions comprises: changing the memory in the memory so that the detected temperature change is close to the reference waveform. The value of at least one of the above-mentioned one or more control parameters.

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