KR20230124728A - heater control unit - Google Patents

Abstract

The heater control device includes a disk-shaped substrate, a tubular support attached to the substrate, a first heating element disposed on the substrate, at least one second heating element disposed concentrically with the first heating element, and a first heating element. A temperature sensor measuring a first temperature, at least one current sensor measuring a current supplied to at least one second heating element, and a first temperature controller outputting a first control signal so that the first temperature approaches a target temperature. And, a first power controller for controlling the first power supplied to the first heating element according to the first control signal, a second power controller for controlling the second power supplied to the second heating element, and the temperature of the second heating element Equipped with an calculating machine. The second power controller controls the second power by a phase control method so as to have a preset ratio with respect to the first power, and the calculator calculates the temperature of the second heating element based on the measured value of at least one current sensor.

Description

heater control unit

The present disclosure relates to a heater control device.

This application claims priority based on Japanese Patent Application No. 2021-12977 of the Japanese application dated January 29, 2021, and uses all the description contents described in the above Japanese application.

Patent Literature 1 discloses a film forming apparatus for providing a metal thin film on a semiconductor wafer. This film forming apparatus includes a heating means provided on a pedestal, a temperature detector for detecting the temperature of a semiconductor wafer placed on the pedestal, a control means for controlling the amount of heat generated by the heating means, and a supporting member supporting the lower portion of the pedestal. . The heating means includes a first heater and a second heater for respectively heating the central portion and the peripheral portion of the semiconductor wafer. The control unit controls power supplied to the first heater based on the detected temperature value of the central portion of the mounting table. Further, the control means is configured to supply the second heater with electric power at a predetermined ratio with respect to the supplied electric power of the first heater.

Patent Document 1: Japanese Unexamined Patent Publication No. 2009-74148

A heater control device of the present disclosure includes a base material having a disk shape, a cylindrical support body coaxially attached to the base material, a first heating element disposed in a region including the center of the base material, and the first heating element. At least one second heating element concentrically disposed with, a temperature sensor for measuring a first temperature of the first heating element, and at least one current sensor for measuring a current supplied to the at least one second heating element, A first temperature controller outputting a first control signal so that the first temperature approaches a target temperature; a first power controller controlling first power supplied to the first heating element according to the first control signal; A second power controller controlling the second power supplied to the second heating element and a calculator calculating the temperature of the second heating element are provided. The substrate has a first surface on which a heating target is disposed, and a second surface facing the first surface. The cylindrical support is attached to the second surface. The temperature sensor is disposed inside the tubular support. The second power controller controls the second power to a predetermined ratio with respect to the first power by a phase control method. The calculator calculates the temperature of the second heating element based on the measured value of the at least one current sensor.

1 is a functional block diagram of a heater control device according to a first embodiment.
Fig. 2 is a plan view of a base material showing an arrangement area of a heating element.
Fig. 3 is a longitudinal cross-sectional view showing the arrangement of a heating element in a base material.
4 is an explanatory diagram of a phase control method.
5 is a flowchart showing the processing sequence up to outputting the second electric power in the first embodiment.
Fig. 6 is a flowchart showing the processing sequence up to outputting the second temperature in Embodiment 1;
7 is a graph showing an example of the temperature profile of the heating element in Embodiment 1.
8 is a graph showing an example of the temperature profile of the heating element during temperature maintenance.
FIG. 9 is a graph showing an example of a temperature profile in a processing state in FIG. 8 in an enlarged manner.
10 is a functional block diagram of a heater control device according to Embodiment 2;
Fig. 11 is a flowchart showing the processing sequence up to outputting the second electric power in Embodiment 2;
Fig. 12 is a plan view of a base material showing a region for disposing a heating element in Modification Example 1;
Fig. 13 is a longitudinal cross-sectional view of a base material showing a region where a heating element is disposed in Modification Example 1;
14 is a functional block diagram of a heater control device according to a second modification.
15 is a functional block diagram of a heater control device according to a third modification.

[Problems to be solved by the present disclosure]

In a multi-zone heater having a plurality of heating elements, further improvement of cracking properties within the wafer surface is required.

In the film forming apparatus described in Patent Literature 1, power supplied to the first heater is controlled based on the detected value of the temperature detector. In contrast, the second heater is supplied with electric power at a predetermined ratio to the supplied electric power of the first heater, but there is no temperature detector for detecting the temperature of the peripheral portion of the wafer. Therefore, it is desired to improve the cracking property by grasping the temperature of the second heater.

On the other hand, in a multi-zone heater, it is difficult to provide temperature sensors for each heating element and control each heater based on the detection values of these sensors. In the film forming apparatus, corrosive gas may be handled. Since metals used for heating elements, electrodes, temperature sensors, etc. are weak against corrosive gases, they need to be protected with ceramic materials having high corrosion resistance. In the film forming apparatus described in Patent Literature 1, electrodes and temperature sensors are collectively disposed inside a tubular support member made of a ceramic material. For this reason, it is difficult to arrange a plurality of temperature sensors in a support member with size limitations. This difficulty becomes even more remarkable because as the number of heating elements increases, the number of electrodes and temperature sensors also increases.

One object of the present disclosure is to provide a multi-zone heater control device capable of grasping the temperature of a zone corresponding to each heating element without providing a temperature sensor for each heating element.

Another object of the present disclosure is to provide a heater control device capable of controlling the temperature of a zone corresponding to each heating element without providing a temperature sensor for each heating element in a multi-zone heater control device. .

[Effect of the present disclosure]

According to the above heater control device, the temperature of the zone corresponding to each heating element can be grasped without providing a temperature sensor for each heating element.

[Description of Embodiments of the Present Disclosure]

Hereinafter, embodiments of the present disclosure are listed and described.

(1) A heater control device according to one embodiment of the present disclosure includes a base material having a disk shape, a tubular support body coaxially attached to the base material, and a second plate disposed in a region including the center of the base material. A first heating element, at least one second heating element disposed concentrically with the first heating element, a temperature sensor for measuring a first temperature of the first heating element, and measuring a current supplied to the at least one second heating element a first temperature controller that outputs a first control signal so that the first temperature approaches a target temperature; and controls the first power supplied to the first heating element according to the first control signal. a first power controller that controls the second power supplied to the second heating element, a second power controller that controls the second power supplied to the second heating element, and an calculator that obtains the temperature of the second heating element; a surface and a second surface facing the first surface, wherein the tubular support is attached to the second surface, the temperature sensor is disposed inside the tubular support, and the second power controller Controls the second power by a phase control method so as to have a preset ratio with respect to the first power, and the calculator calculates the temperature of the second heating element based on the measured value of the at least one current sensor. .

According to the heater control device, the first temperature of the first heating element is detected by a temperature sensor. The first electric power supplied to the first heating element is controlled based on the temperature detected by the temperature sensor. On the other hand, the temperature of the second heating element is obtained by a calculator based on the measured value of the current sensor. Therefore, the temperature of the second heating element can be grasped even without a temperature sensor for detecting the temperature of the second heating element or the temperature of the zone where the second heating element is disposed. The second electric power supplied to the second heating element is controlled to be at a preset ratio with respect to the first electric power. Since the second power is controlled by the phase control method, it can be controlled with high precision. As a result, the temperature of the second heating element can also be grasped with high accuracy.

(2) As one aspect of the heater control device, the calculator calculates the temperature of the second heating element using the first temperature, the second voltage of the second heating element, and a predetermined coefficient, and the coefficient is , may be a coefficient representing the relationship between the resistance of the second heating element and the temperature of the second heating element.

In this embodiment, the resistance of the second heating element can be obtained using the current and the second voltage supplied to the second heating element. In addition, the temperature of the second heating element can be obtained by using a coefficient representing the relationship between the resistance of the second heating element and the temperature of the second heating element.

(3) As one aspect of the heater control device that calculates the temperature of the second heating element using a predetermined coefficient, the coefficient may be a coefficient selected according to the first temperature from a plurality of predetermined coefficients.

In the above embodiment, the temperature of the second heating element can be obtained more accurately by using a different coefficient according to the measurement result of the temperature sensor, that is, the first temperature of the first heating element. The second heating element is supplied with power having a predetermined ratio with the power supplied to the first heating element. That is, the temperature of the second heating element is related to the temperature of the first heating element. On the other hand, as for the relationship between the temperature and resistance of the second heating element, it is difficult to accurately obtain the temperature of the second heating element according to the temperature range with the coefficient obtained only from the relationship between the resistance at room temperature and the resistance at the maximum temperature. Therefore, the temperature of the second heating element can be calculated more accurately by using a different coefficient according to the temperature of the first heating element.

(4) As one aspect of the heater control device that calculates the temperature of the second heating element using a predetermined coefficient, the plurality of coefficients are used when the temperature of the first heating element and the second heating element is raised, while the temperature is maintained, And it may be different at the time of temperature fall.

In this embodiment, the temperature of the second heating element can be obtained more accurately than when the same coefficient is used in each step of heating, maintaining, and decreasing the temperature of the second heating element. The temperature histories differ greatly in each of the above steps. Therefore, it is difficult to accurately obtain the temperature of the second heating element by using a coefficient common to each of these steps. In particular, during temperature maintenance, the amount of temperature change per unit time is small compared to the time of temperature increase and temperature decrease. Therefore, the temperature of the second heating element can be obtained more accurately by using different coefficients according to different steps in the process from temperature rise to temperature decrease.

(5) As one aspect of the heater control device that calculates the temperature of the second heating element using a predetermined coefficient, the coefficient is a state in which the heating target is not disposed on the first surface when the temperature is maintained. may be obtained based on the first temperature measured in

In the above configuration, the coefficient can be obtained without carrying out a preliminary test by placing the object to be heated on the first surface. Therefore, there is no need to prepare a heating object in the preliminary test. The preliminary test is a test in which the relationship between the temperature and the resistance of the second heating element is investigated by heating the first heating element to a target temperature during temperature holding in order to obtain the coefficient. If the accuracy of the obtained temperature of the second heating element is emphasized, the heating object must be prepared in order to carry out a preliminary test by placing the heating object on the first surface of the base material. On the other hand, if the preliminary test is conducted in a state where the object to be heated is not placed on the first surface, the coefficient can be obtained even without using the object to be heated.

(6) One aspect of the heater control device includes an external output unit that displays or transmits at least one of the temperature of the second heating element and a result of determining whether or not the temperature of the second heating element is within an appropriate range to an external device. You can do it.

In the above configuration, the user can be notified of the second temperature, which is the temperature of the second heating element, or the determination result, by including an external output unit. Specific examples of the external output unit include a second temperature indicator, an alarm device output when the second temperature is out of a predetermined range, or a data output interface that communicates with other external devices.

(7) One embodiment of the heater control device further includes a second temperature controller, and the second temperature controller includes a second control signal for adjusting the ratio so that the temperature of the second heating element approaches a target temperature. and the second power controller may control the second power according to the ratio adjusted by the second control signal.

In the above aspect, by providing the second temperature controller, the ratio can be adjusted to control the temperature of the second heating element with high precision.

(8) One aspect of the heater control device further includes a third temperature controller, wherein a difference between the temperature of the second heating element and the first temperature is a difference between the temperature of the second heating element and the first temperature controller. outputs a third control signal for adjusting the ratio so that the difference between each target temperature of the temperature is adjusted, and the second power controller controls the second power according to the ratio adjusted by the third control signal, also good

In the above aspect, the temperature of the second heating element can be controlled with high precision by adjusting the ratio by providing the third temperature controller.

[Details of Embodiments of the Present Disclosure]

A heater control device according to an embodiment of the present disclosure will be described based on the drawings. The same reference numerals in the drawings indicate the same designations. The sizes, positional relationships, etc. of the members shown in each drawing are expressed for the purpose of clarifying the description, and do not necessarily represent actual dimensional relationships or the like.

[Embodiment 1]

A heater control device 1 according to Embodiment 1 will be described with reference to FIGS. 1 to 4 . This heater control device 1 can be used for a film forming device that forms a thin film on the surface of a wafer. A film forming apparatus includes a substrate 10 and a support 20 in a chamber capable of controlling atmospheric gas. The illustration of the chamber is omitted. In FIG. 1 , each heat generating element 30 has a portion where it is not disposed in a part of the circumferential direction of the substrate 10, but in an actual device, the heat generating element 30 is disposed throughout the entire substrate 10 without gaps.

<Entire configuration>

As shown in FIG. 1 , the heater control device 1 includes a substrate 10, a support 20, a plurality of heating elements 30, a temperature sensor 40, a current sensor 50, and a controller. (60) is provided. The substrate 10 includes a first surface 10a on which the heating target W shown in FIG. 3 is disposed, and a second surface 10b facing the first surface 10a. In the following description, the side of the first surface 10a of the substrate 10 is referred to as "upper" and the side of the second surface 10b is referred to as "lower" in some cases. The support 20 is attached below the substrate 10 . As shown in FIGS. 1 and 3 , the plurality of heating elements 30 are arranged inside the substrate 10 . The plurality of heating elements 30 includes a first heating element 31 and one or more second heating elements 32 . In this example, for convenience of explanation, a case in which one second heating element 32 is provided will be described as an example. The temperature sensor 40 detects the temperature of the first heating element 31 . The current sensor 50 includes a first current sensor 51 for measuring a first current flowing through the first heating element 31 and a second current sensor 52 measuring a second current flowing through the second heating element 32. ) is provided. The controller 60 mainly controls power supplied to the first heating element 31 and the second heating element 32 . One of the characteristics of Embodiment 1 is that the temperature sensor 40 is provided only in the first heating element 31 without providing the temperature sensor in the second heating element 32, so that the temperature of the second heating element 32 can be grasped. It is configured so that Hereinafter, each configuration will be described in detail.

<Description>

The substrate 10 has a disk-like shape. The substrate 10 has a first surface 10a and a second surface 10b. The first surface 10a and the second surface 10b face each other. On the first surface 10a, a heating target W shown in FIG. 3 is disposed. The heating object W is, for example, a wafer of silicon or compound semiconductor. A support body 20 described later is attached to the second surface 10b. A plurality of holes into which a plurality of terminals 30t shown in FIG. 3 are inserted are provided in the second surface 10b.

As shown in FIG. 2 , the substrate 10 is concentrically divided into a plurality of regions. The substrate 10 of this example is partitioned into an inner region 10i and an outer region 10e. The inner region 10i is a circular region centered on the center of the substrate 10 . The center of the base material 10 refers to the center of a circle constituted by the outline of the base material 10 seen in a plane. The diameter of the inner region 10i is 80% or less of the diameter of the substrate 10 . When the diameter of the inner region 10i is 80% or less of the diameter of the substrate 10, an area in which one or more second heating elements 32 can be disposed outside the first heating element 31 can be secured. The diameter of the inner region 10i may be 50% or less of the diameter of the substrate 10. The diameter of the inner region 10i may be 10% or more of the diameter of the substrate 10 . When the diameter of the first heating element 31 is 10% or more of the diameter of the substrate 10, an area in which the first heating element 31 can be disposed in the center of the substrate 10 can be secured. The outer region 10e is an annular region located outside the inner region 10i. Corresponding to the plurality of regions, a plurality of heat generating elements 30 described later are disposed.

As for the material of the base material 10, well-known ceramics are mentioned. As ceramics, aluminum nitride, aluminum oxide, silicon carbide, etc. are mentioned, for example. The material of the substrate 10 may be composed of a composite material of the above ceramics and metal. As a metal, aluminum, an aluminum alloy, copper, a copper alloy etc. are mentioned, for example. The material of the base material 10 of this example is ceramics.

<support>

As shown in FIGS. 1 and 3 , the support 20 supports the substrate 10 from the second surface 10b side. The support body 20 is attached to the second surface 10b so as to surround the plurality of terminals 30t when the heater control device 1 is viewed in plan from the first surface 10a side. The shape of the support body 20 is not particularly limited. The support body 20 of this example is a cylindrical member. The support 20 is disposed concentrically with the substrate 10 . In this example, the substrate 10 and the support 20 are connected so that the center of the cylindrical support 20 and the center of the disk-shaped substrate 10 are coaxial.

Both ends of the support body 20 have flange portions 21 bent outward. Between the flange part 21 of the upper end part and the 2nd surface 10b, the sealing member not shown is arrange|positioned. The inside of the support body 20 is sealed by the sealing member. As another aspect, the second surface 10b and the flange portion 21 may be bonded together in order to maintain airtightness without using a sealing member. The chamber in which the substrate 10 and the support 20 are disposed is typically filled with a corrosive gas. By maintaining the airtightness of the inside of the support body 20, the plurality of terminals 30t, the plurality of power lines 30c, and the like accommodated inside the support body 20 can be isolated from the corrosive gas.

As for the material of the support body 20, well-known ceramics are mentioned similarly to the material of the base material 10. The material of the support 20 and the material of the substrate 10 may be the same or different.

<First heating element and second heating element>

Each of the plurality of heating elements 30 is a heat source that heats the heating target W through the substrate 10 . As shown in FIGS. 1 and 3 , the first heating element 31 is disposed in a circular area including the center of the substrate 10, that is, in an inner area 10i. One or more second heating elements 32 are disposed concentrically with the substrate 10 and the first heating element 31 . One or more second heating elements 32 are disposed in an annular region concentric with the center of the substrate 10, that is, in an outer region 10e. The first heating element 31 and one or more second heating elements 32 are disposed at intervals in the thickness direction of the substrate 10 . Each of the first heating element 31 and the second heating element 32 is connected to the power line 30c via a terminal 30t shown in FIG. 3 . Power is supplied from a power source (not shown) to each heat generating element 30 via this power line 30c.

The shapes of the first heating element 31 and the second heating element 32 are not particularly limited. When the base material 10 is viewed in plan from the first surface 10a side, the shape of the outer circumferential outlines of the first heat generating element 31 and the second heat generating element 32 is generally circular. The plurality of heating elements 30 are arranged concentrically with the substrate 10 and the support 20 . Accordingly, the plurality of heating elements 30 are also arranged concentrically. The concentric type here means that when the heater control device 1 is viewed in a plan view from the first surface 10a side, the envelopes of the heating elements 30 have a common center and the diameters of the envelopes are different. say The center of this envelope coincides with the center of the substrate 10 . In FIG. 1 and FIG. 3, although the 1st heat generating element 31 and the 2nd heat generating element 32 are shown simplified, these several heat generating elements 30 are arrange|positioned concentrically. In this specification, the center side refers to the center side of the envelope circle, and the outer side refers to the side away from the center in the radial direction of the envelope circle.

As shown in FIGS. 1 and 3 , the plurality of heating elements 30 include one first heating element 31 and one or more second heating elements 32 . In this example, the second heating element 32 is one. As shown in Modification 1 described later, a plurality of second heating elements 32 may be provided. The diameter of the envelope circle of the at least one second heating element 32 is larger than the diameter of the envelope circle of the first heating element 31 . When the base material 10 is viewed in a plan view from the first surface 10a side, each heating element 30 may be disposed partially overlapping in the radial direction of each envelope circle, or disposed at intervals without overlapping. It may be.

Each heating element 30 is disposed inside the substrate 10 as shown in FIGS. 1 and 3 . Each heat generating element 30 is arranged in a layered manner at intervals in the thickness direction of the substrate 10 . Each heat generating element 30 in this example is arranged on a layer parallel to the first surface 10a. The first heat generating element 31 is disposed on the first layer positioned furthest on the first surface 10a side in the thickness direction of the substrate 10 . Since the first heating element 31 is disposed on the first layer, a long distance between the first heating element 31 and the second surface 10b can be secured. In addition, since the first heating element 31 is disposed on the first layer, the degree of freedom of the circuit pattern is higher than when the first heating element 31 is disposed on a layer other than the first layer. This is because the first heat generating element 31 disposed on the first layer does not need to be disposed avoiding the terminal 30t connected to the second heat generating element 32 . The second heat generating element 32 is disposed closer to the second surface 10b than the first heat generating element 31 . When a plurality of second heat generating elements 32 are provided, the individual second heat generating elements 32 are also arranged in a layered manner at intervals in the thickness direction of the substrate 10 .

The material of each heating element 30 is not particularly limited as long as it is a material capable of heating the heating target W to a desired temperature. As for the material of each heating element 30, a well-known metal suitable for resistance heating is mentioned. Examples of the metal include one selected from the group consisting of stainless steel, nickel, nickel alloys, silver, silver alloys, tungsten, tungsten alloys, molybdenum, molybdenum alloys, chromium, and chromium alloys. As a nickel alloy, nichrome is mentioned, for example.

Each heating element 30 can be manufactured by combining a screen printing method and a hot press joining method, for example. In the case of this example, it can manufacture in the following procedure. Three ceramic substrates and a screen mask capable of transferring each heating element 30 are prepared. As the screen mask, one capable of producing each circuit pattern of the first heating element 31 and the second heating element 32 is used. A screen mask of a circuit pattern to be produced is placed on each of the two ceramic substrates. The paste to be the heating element 30 is applied to the ceramic substrate on which the screen mask is mounted. The heating element 30 is transferred to the ceramic substrate using a squeegee. After transferring the heating element 30, the screen mask is removed. As a result of the above, the first substrate onto which the first heating element 31 is transferred and the second substrate onto which the second heating element 32 is transferred are obtained. The first substrate, the second substrate, and the ceramic substrate on which the heating element is not transferred are sequentially bonded together and bonded by hot press. By this bonding, each heating element 30 is arranged inside the base material 10 .

<Temperature sensor>

The temperature sensor 40 is a sensor that measures the first temperature of the first heating element 31 . As the temperature sensor 40, a commercially available thermocouple or resistance thermometer can be suitably used. Examples of the RTD include PT100, which is a platinum RTD.

The location where the temperature sensor 40 is placed is inside the substrate 10 . In this example, the temperature sensor 40 is arrange|positioned in the area|region inside the inside of the base material 10 from the inner peripheral surface of the support body 20 when the base material 10 is viewed planarly. That is, "the temperature sensor is disposed inside the tubular support" in the claims means that the temperature sensor 40 is located inside the contour of the inner circumferential surface of the support 20 when the support 20 is viewed in the axial direction. say to do In particular, it is preferable that the temperature sensor 40 is disposed near the first heating element 31 . The temperature measured by the temperature sensor 40 provided near the first heating element 31 is not the temperature of the first heating element 31 itself, but the inner region of the substrate 10 on which the first heating element 31 is disposed ( 10i) is the temperature. However, the temperature of this inner region 10i is also regarded as the first temperature of the first heating element 31 .

<current sensor>

The current sensor 50 is a sensor that detects a current flowing through the heating element 30 . In this example, a first current sensor 51 for detecting a first current flowing through the first heating element 31 and a second current sensor 52 detecting a second current flowing through the second heating element 32 are provided. do. The second current sensor 52 corresponds to the current sensor according to claim 1. When there are a plurality of second heating elements 32 , the second current sensor 52 is provided in each second heating element 32 . The first current sensor 51 is provided on the power line 30c leading to the first heating element 31, and the second current sensor 52 is provided on the power line 30c leading to the second heating element 32, respectively. As the current sensor 50, a sensor typified by a commercially available CT (Current Transmitter) can be used. In this example, the first current or the second current is a value obtained by averaging the effective values of the currents flowing through the first heating element 31 or the second heating element 32 within a predetermined period of time to remove electrical noise.

<controller>

The controller 60 controls each part necessary for the operation of the heater control device 1 . More specifically, the controller 60 includes a first temperature controller 61 , a first power controller 63 , a second power controller 64 , an arithmetic unit 65 and a memory 66 . The controller 60 is typically realized by a processor including a central processor unit (CPU) or digital signal processing (DSP). Typically, a processor includes a bus, a CPU connected to the bus, a read-only memory (ROM), a random access memory (RAM), an input/output interface (I/F), and the like. As for the number of processors, the controller 60 may be provided with one or more, and may be provided with a plurality of processors. The first temperature controller 61, the first power controller 63, the second power controller 64, the calculator 65, and the memory 66 may be configured as separate hardware, and may be configured as one controller 60. It may be constituted as a part of the constituent elements. The memory 66 stores a program for causing the processor to execute a control procedure described later. The processor reads and executes the program stored in the memory 66. The program includes program codes related to processing in the first temperature controller 61, the first power controller 63, the second power controller 64, and the arithmetic unit 65.

・First temperature controller

The first temperature controller 61 outputs a first control signal so that the first temperature approaches the target temperature. Control in this 1st temperature controller 61 can use PID control. PID control is a type of feedback control, and is a control method in which control of an input value is performed by three operations: a deviation (P) of an output value and a target value, an integral (I), and a differential (D) of the output value. Smooth temperature control with little hunting can be performed by the proportional operation that outputs the manipulated variable according to the deviation. Integral operation can automatically correct the offset. It is possible to quickly respond to disturbances by differential operation.

The target temperature is a temperature set by the user. The first temperature controller 61 performs a PID operation based on the target temperature and the current temperature of the first heating element 31, that is, the first temperature, and outputs a first control signal to the first power controller 63.

·First power controller

The first power controller 63 controls the first power supplied to the first heating element 31 according to the first control signal. The first power controller 63 to which the first control signal is input supplies the first power corresponding to the first control signal to the first heating element 31 . The first power is calculated by multiplying the first current and the first voltage. The first current is a measured value of the first current sensor 51 as described above. The first voltage is a voltage applied to the first heating element 31 . This first voltage is obtained by calculation as will be described later.

Control of the first power is performed by a phase control method. The phase control method is a method of controlling the voltage applied to the load in the range of 0% to 100% by controlling the firing phase angle for each half cycle of the power supply frequency. For the first power controller 63, a switching element is suitably used. A triac is mentioned as a specific example of a switching element. A triac is an element that can control current in both directions by opening and closing one gate by connecting two thyristors in antiparallel.

An overview of the phase control method will be described based on FIG. 4 . 4 shows the current waveform of the supply current from the power supply as a sine wave. When a gate signal is input to the gate of the triac, the triac is turned on by opening the gate, and current flows. Of the sinusoidal waves in FIG. 4 , currents in hatched regions are output. In this example, the gate signal is a pulse signal with a constant width (w). When the gate signal is lost, the triac remains on and current continues to flow. When the current flowing through the triac becomes zero, the triac is automatically turned off and no current flows. Depending on the timing of applying the gate signal, the triac can output the first current as a desired current in the range of 0% to 100%. The output mode at the time of phase control in this example is voltage proportional square control. The voltage proportional square control is a mode in which the square of the effective value Vrms of the output voltage is proportional to the manipulated variable MV corresponding to the gate open state. The manipulated variable MV and the manipulated phase angle θ of FIG. 4 have a relationship of MV=θ−(1/2π)sin(2θπ).

On the other hand, the supply voltage from the power source is also represented by a sine wave. Since the supply voltage from the power supply is known, the first voltage can also be grasped by calculation based on the timing at which the gate signal is input to the current waveform from the power supply, in other words, the open state of the gate, as described above. Calculation of the first voltage and calculation of the first electric power are performed by an arithmetic unit 65 described later.

·Second power controller

The second power controller 64 controls the second power supplied to the second heating element 32 . More specifically, the second power controller 64 controls the second power to be a preset ratio with respect to the first power. This ratio is a ratio preset by the user. For example, the ratio of the first power to the second power is set to 1.0:0.8. When there are a plurality of second heating elements 32, the second power of each heating element 30 is also controlled to be a preset ratio with respect to the first power. For example, when there are two second heating elements 32, first power:second power A:second power B = 1.0:0.8:0.6. The second electric power A is the second electric power of one of the two second heating elements 32 . The second power B is the second power of the other of the two second heating elements 32 .

Different ratios can be set in a series of temperature profiles of heating, maintaining, and decreasing the temperature of the heating element 30 . Usually, this ratio is different in each step at the time of temperature increase, the time of temperature maintenance, and the time of temperature decrease. At the time of temperature increase and temperature decrease, between the start and end of each step, the ratio may differ depending on the temperature range. For example, from room temperature to 400°C, the first power:second power is 1.0:0.8, and from 400°C to 450°C, the first power:second power is 1.0:0.9. When the temperature rises at the same power rate and becomes high, the heat generating element 30 becomes excessively hot at the center, and there is a possibility that it is damaged due to thermal stress due to the difference between the inside and outside of its own in-plane temperature distribution. Therefore, it is preferable to increase the ratio of the second power at high temperatures.

The control of the second power is also performed by the phase control method similarly to the control of the first power. The second power is obtained by multiplying the second current and the second voltage. The second current is a measured value of the second current sensor 52 . Like the first voltage, the second voltage can be calculated based on the open state of the gate. Calculation of these second voltages and calculations of the second power are also performed by an arithmetic unit 65 described later.

・Computer

The calculator 65 performs various calculations required by the controller 60. As described above, calculations of the first voltage, first power, second voltage, and second power are all performed by the calculator 65. In addition, the calculator 65 also calculates the second temperature, which is the temperature of the second heating element 32 .

The second temperature of the second heating element 32 is obtained using a coefficient representing the relationship between the resistance of the second heating element 32 and the resistance of the second heating element 32 and the temperature obtained in advance. That is, the second temperature is not a value measured using a temperature sensor, but a value calculated based on the power supplied to the first heating element 31 . The resistance of the second heating element 32 is obtained by dividing the second voltage of the second heating element 32 described above by the second current flowing through the second heating element 32 . The coefficient is determined in advance by a preliminary test described later. This coefficient also includes a relational expression representing the relationship between the resistance of the second heating element 32 and the temperature. Coefficients are stored in the memory 66. If the relationship between the resistance and the temperature of the second heating element 32 is known in advance, when the resistance of the second heating element 32 is found, the second temperature of the second heating element 32 is calculated by referring the resistance to the above relationship. can be saved by

·Memory

The memory 66 is a memory for storing programs, and various nonvolatile memories can be suitably used. The memory 66 may also include a volatile memory for temporarily storing values required for a series of calculations.

<Other components>

The heater control device 1 may include an external output unit 70 and a transformer 80 .

The external output unit 70 is a device that displays or transmits at least one of the second temperature of the second heating element 32 obtained as described above and the result of determination of whether or not the second temperature is in an appropriate range to an external device. . For example, as the external output unit 70, a display for displaying the second temperature in characters or displaying a change in the second temperature over time as a graph may be used. The other external output unit 70 may be a device that outputs a process result obtained by performing a predetermined process at the second temperature. An alarm device is exemplified as a device that displays the processing result. The alarm device is a device that issues an alarm when, for example, the second temperature deviates from a predetermined appropriate range. The warning is not particularly limited as long as it can inform the user of the abnormality of the second temperature. For example, examples of specific types of warnings include display of characters on a display, lighting of a lamp, sounding of a buzzer, and the like. As another external output unit 70, a communication device not shown is exemplified. This communication device communicates with an external device possessed by a remote user. For example, information of the second temperature may be transmitted to an external device through a communication device, or the alert may be transmitted to an external device as a state change of a flag through a communication device. By transmitting this information, a remote user can recognize a second temperature or an alarm.

The transformer 80 is a member for electromagnetically coupling a power source (not shown) and the controller 60 to supply power to the first heating element 31 and the second heating element 32 . The primary side of the transformer 80, that is, the power supply side, and the secondary side of the transformer 80, that is, the controller 60 side, are insulated from each other so that they are not electrically connected. Since the power source and the controller 60 are insulated from each other, it is easy to control the power to each heating element 30 . In this example, power is supplied to each of the heating elements 30 by branching the secondary power line 30c to each of the first heating element 31 and the second heating element 32 . That is, the first heating element 31 and the second heating element 32 are not electrically insulated from each other. Since the first heating element 31 and the second heating element 32 are not insulated, the number of transformers 80 can be reduced compared to the case where both heating elements 30 are insulated.

In addition, the heater control device 1 may be provided with an input unit not shown. The input unit is a device for inputting various conditions set by the user. Various conditions include a preset ratio with respect to the first power to define the second power. For the input unit, known input devices such as a ten key, a keyboard, and a touch panel can be used. Various conditions input from the input unit are stored in the memory 66 .

<processing order>

Based on FIGS. 5 and 6 , the processing procedure of the heater control device 1 will be described. 1 is referred to for each constituent member.

First, based on FIG. 5 , the processing sequence until output of the first electric power and the second electric power to each heating element 30 will be described. In step S1, a 1st temperature is acquired from the temperature sensor 40, and a 1st current is acquired from the 1st current sensor 51. In step S2, the first temperature controller 61 outputs a first control signal so that the first temperature approaches the target temperature. In step S3, the first power controller 63 outputs the first power corresponding to the first control signal to the first heating element 31. Then, in step S4, the calculator 65 calculates the second power, and the second power is output from the second power controller 64 to the second heating element 32. This series of processes of step S1 to step S4 is repeatedly performed while the heater control device 1 is being driven.

Next, based on FIG. 6, the processing procedure until a 2nd temperature is calculated|required and output is demonstrated. In step S11, a second current is acquired by the second current sensor 52. In step S12, the second resistance, which is the resistance of the second heating element 32, is calculated by the calculator 65 from the second current and the second voltage. In step S13, the second temperature is calculated by the calculator 65 using the calculated second resistance and the coefficient representing the relationship between the resistance of the second heating element 32 and the temperature obtained in advance. In step S14, the calculated second temperature is output to the external output unit 70.

<Preliminary Exam>

The preliminary test is a test for obtaining in advance a coefficient representing the relationship between the resistance of the second heating element 32 and the temperature. It is suitable that the preliminary test is performed by a different method during temperature rise and temperature decrease, and during temperature maintenance. That is, it is suitable to use different coefficients at the time of temperature rise and temperature decrease, and at the time of temperature maintenance.

Before explaining the method for obtaining this coefficient, a temperature profile from temperature rise to temperature decrease will be described based on FIG. 7 . Fig. 7 is a graph showing the change with time of the temperature of the first heating element 31 in the heater control device 1 of the present example.

First, in the temperature raising process, the temperature of the heating element 30 rises at a substantially constant rate from room temperature to a predetermined holding temperature. A rate at which the heat generating element 30 is not damaged is selected as the rate of temperature increase in this temperature increase process.

In the temperature maintenance process, the temperature of the heating element 30 is maintained at a substantially constant temperature. The temperature maintenance process includes an idle state in which a wafer is not placed on the substrate 10 and a processing state in which a wafer is placed on the substrate 10 and a film is formed on the wafer. In the idle state, extremely minute temperature fluctuations occur due to the supply and exit of gas in the film forming apparatus and the control of electric power supplied to each heat generating element 30 described above. In the graph of Fig. 7, the idle state is indicated by a straight line extending horizontally, but in reality, as will be described later, very little temperature fluctuation occurs. On the other hand, in the processing state, since wafers are deposited and loaded onto the substrate 10 and film formation is sequentially performed on a plurality of wafers, a larger temperature fluctuation occurs than in the idle state. The temperature change in the treatment state is indicated by a broken line following the straight line in the idle state in FIG. 7 .

In the temperature-falling process, the temperature of the heating element 30 decreases at a substantially constant rate from the holding temperature to the room temperature. The rate at which the heating element 30 is not damaged is selected as the rate of temperature decrease in this temperature decrease process.

In the above temperature profile, the method of obtaining the coefficient at the time of temperature increase and the time of temperature decrease will be explained first, and then the method for obtaining the coefficient at the time of temperature maintenance will be explained.

・In case of temperature rise and fall

At the time of temperature rise and the time of temperature decrease, the amount of temperature change per unit time is large compared with the time of temperature hold|maintenance. When the temperature rises and falls, no film forming process is performed on the wafer. In this case, the temperature range from the room temperature to the maintenance temperature or the temperature range from the maintenance temperature to the room temperature is divided into narrower temperature regions, and the relationship between the resistance and temperature of the second heating element 32 is obtained for each divided temperature region. For example, a relationship between resistance and temperature of each of the first heating element 31 and the second heating element 32 is obtained for each partitioned temperature region having a range of 50°C to 100°C. More specifically, when the temperature rises, a first temperature range of 50°C or more and 100°C or less, a second temperature range of 100°C or more and 200°C or less, a third temperature range of 200°C or more and 300°C or less, 300°C or more and 400°C The relationship between the resistance and the temperature of the second heating element 32 is obtained for each of the following fourth temperature range and the fifth temperature range of 400° C. or higher and lower than the holding temperature. An example of the holding temperature is 450°C. For example, in the first temperature range, the relationship between resistance and temperature at two points of 50°C and 100°C is obtained. Here, two measuring points, that is, the temperature T1 of the second heating element 32 at the low-temperature resistance R(T1) and the second heating element at the high-temperature resistance R(T2) The temperature T2 of (32) is represented by a proportional relational expression. Using this relational expression, the temperature T of the second heating element 32 of resistance R is obtained by the following equation.

T={(T2-T1)/(R(T2)-R(T1))}×(R-R(T1))+T1

However, T1≤T≤T2, R(T1)≤R≤R(T2).

What is necessary is just to obtain the relationship between the resistance of the 2nd heating element 32 and temperature by the same way of thinking as at the time of temperature-falling and temperature-rising. In this way, by obtaining the relationship between the resistance and the temperature of the second heating element 32 for each narrow temperature range partitioned, a different coefficient can be used for each partitioned temperature range. The temperature of the second heating element 32 can be obtained with high accuracy by using a different coefficient for each partitioned temperature region.

In contrast, for example, the temperature of the second heating element 32 at the resistance R(Tr), that is, room temperature Tr, and the holding temperature of the second heating element 32 at the resistance R(Tk). (Tk) is also represented by a proportional relational expression. Using this relational expression, the temperature T of the second heating element of the resistance R is obtained by the following equation.

T={(Tk-Tr)/(R(Tk)-R(Tr))}×(R-R(Tr))+Tr

However, Tr≤T≤Tk and R(Tr)≤R≤R(Tk).

In this case, in the relational expression between the resistance and temperature of the second heating element 32 obtained from two points, room temperature and holding temperature, the resistance value at the intermediate temperature cannot be expressed by linear interpolation between the two points, so accuracy It is difficult to obtain a good temperature of the second heating element.

·When maintaining temperature

During temperature maintenance, the rate of temperature change per unit time is extremely small compared to the time of temperature increase or temperature decrease. Therefore, when maintaining the temperature, it is desirable to obtain a relationship between the resistance of the second heating element 32 and the temperature in a narrower temperature range than when the temperature is raised or when the temperature is decreased. More specifically, the temperature of the second heating element 32 can be accurately obtained by using a coefficient corresponding to a fine temperature range, which is the difference between the maximum temperature and the minimum temperature during temperature holding. As described above, the temperature maintaining process includes two temperature profiles of an idle state without a heating target W and a processing state with a heating target W. This temperature profile is demonstrated based on FIG. 8 is a graph showing changes in the temperature of the first heating element and the temperature of the second heating element over time. The temperature of the first heating element 31 is a temperature determined based on the resistance of the first heating element 31 determined from the first current and the first voltage and the above coefficient. The temperature of the second heating element 32 is a temperature determined based on the coefficient and the resistance of the second heating element 32 determined from the second current and the second voltage. In this graph, the change over time of the measured value of the temperature sensor 40 is also shown together. All graphs have overlapping lines. In this graph, the process in the idle state is referred to as Case 1, and the process in the processing state is referred to as Case 2. As shown in this graph, in the idle state, gas flows in and out of the chamber of the film forming apparatus, and as a result of temperature control by the first temperature controller 61, very little temperature movement is recognized. On the other hand, in the processing state, in order to load and unload the wafer into the chamber, a higher temperature movement is permitted than in the idle state. Since a plurality of lines are overlapped in the graph of FIG. 8 , for example, the fluctuation range of temperature in an idle state in which a plurality of lines are overlapped appears large. However, the fluctuation range of the line of each graph is smaller. In particular, the fluctuation range of each graph is clearly smaller in the idle state than in the processing state. In this temperature maintenance process, there are a method of obtaining a coefficient based on a temperature profile in a processing state and a method of obtaining a coefficient based on a temperature profile in an idle state. Hereinafter, each is explained in order.

Method A (Processing state: with heating target)

First, from the change over time of the measured value of the temperature sensor 40 within a predetermined time in the processing state, the resistance value (Rmax) of each heating element 30 at the time of the maximum temperature (Tmax), and the minimum temperature (Tmin) ) The resistance value Rmin of each heating element 30 at the time point is confirmed. The predetermined time is selected from the range of about 500 seconds to about 1000 seconds. The predetermined time in this example is 600 seconds. Within this predetermined time, film formation is performed on one wafer. FIG. 9 is an enlarged view of a part of the temperature change in the processing state of FIG. 8 . The minimum temperature (Tmin) is a valley temperature from when a wafer that has undergone a film formation process is taken out until a current wafer to be subjected to a film formation process is placed on the substrate 10. The maximum temperature Tmax is the peak temperature while the film forming process is being performed on the current wafer. 9 shows that the minimum temperature Tmin is 449.4°C and the maximum temperature Tmax is 450.3°C. The resistance value (Rmax) and the resistance value (Rmin) of each heating element 30 are the value obtained by dividing the first voltage at each point in time by the first current, or the second voltage at each point in time as the second current is the value divided by A relational expression between the temperature and resistance value of each heating element 30 is obtained using these maximum temperature (Tmax), resistance value (Rmax), minimum temperature (Tmin), and resistance value (Rmin). This relational expression is obtained by the same way of thinking as the relational expression shown at the time of temperature rise and temperature decrease.

Since the above method obtains a relational expression based on the resistance value Rmax, the maximum temperature Tmax, the minimum temperature Tmin, and the resistance value Rmin in the processing state of the wafer, the second obtained using the relational expression The temperature of the heating element 32 can be grasped with high precision.

When a preliminary test is conducted by the method A described above and the relationship between resistance and temperature of the heating element 30 is obtained, the relationship between resistance and temperature is obtained based on a temperature profile simulating actual film formation. In this way, the temperature of the second heating element 32 can be grasped with high precision.

Method B (processing state: with heating target)

First, the average resistance (Rave) within a predetermined period of time is obtained from the change over time in the resistance value of each heating element 30 within a predetermined period of time in a processing state. The predetermined time is appropriately selected from, for example, a range of about 5000 seconds to about 10000 seconds. In this example, the predetermined time is 8000 seconds. Within this predetermined time, film formation is performed on 10 or more wafers. Next, the change rate (ΔR/R) of the resistance of each heating element 30 within a predetermined period of time is set in advance. First, the maximum resistance (Rmax) and minimum resistance (Rmin) within a predetermined time are obtained, and further, the difference (ΔR) between the maximum resistance (Rmax) and the minimum resistance (Rmin) and the average resistance (Rave) of the difference (ΔR) are calculated. Calculate the ratio (ΔR/Rave) for Let this ratio (ΔR/Rave) be the rate of change (ΔR/R). For example, here, the rate of change (ΔR/R) is set to 0.02. On the other hand, the average temperature (Tave) within a predetermined time is obtained in the same way for the measured value of the temperature sensor 40 . In addition, the temperature change amount (ΔT) within a predetermined time is set in advance. As for the temperature change amount (ΔT), the difference between the maximum temperature (Tmax) and the minimum temperature (Tmin) within a predetermined time is first obtained as the temperature change amount (ΔT). For example, here, the temperature variation (ΔT) is 0.88°C. It is considered that the ratio (ΔR/R) and the amount of change in temperature (ΔT) are substantially constant for each heating element 30 unless the holding temperature changes greatly. The fact that the holding temperature does not change significantly means, for example, that the amount of change in the holding temperature is 100°C or less.

In the subsequent film formation, the average resistance (Rave) and the average temperature (Tave) of each heating element 30 may be obtained. That is, the maximum resistance (Rmax), minimum resistance (Rmin), maximum temperature (Tmax), and minimum temperature (Tmin) in the next and subsequent times are obtained as follows.

ΔR=Rave×0.02

Maximum resistance (Rmax)=Rave+ΔR/2

Minimum Resistance (Rmin)=Rave-ΔR/2

Maximum temperature (Tmax)=Tave+ΔT/2

Minimum temperature (Tmin)=Tave-ΔT/2

In this way, before the first film formation, it is necessary to obtain the maximum resistance (Rmax), minimum resistance (Rmin), maximum temperature (Tmax), and minimum temperature (Tmin) in advance. However, during the second and subsequent film formation, the maximum resistance (Rmax), the minimum resistance (Rmin), the maximum temperature (Tmax), and the minimum temperature (Tmin) are used by using the known resistance change rate (ΔR/R) and temperature change amount (ΔT). ) can be obtained. When each of these parameters is obtained, the correlation between the resistance and temperature of the heating element 30 can be obtained.

If a preliminary test is conducted by the above method B and the relationship between the resistance and the temperature of the heating element 30 is obtained, the actual maximum resistance (Rmax), minimum resistance (Rmin), There is no need to measure the maximum temperature (Tmax) or minimum temperature (Tmin). Therefore, the temperature of the 2nd heating element 32 can be calculated|required more simply.

Method C (idle state: no heating object)

First, the average resistance (Rave) within a predetermined period of time is obtained from the change over time in the resistance value of each heating element 30 within a predetermined period of time in an idle state. The predetermined time is appropriately selected from a range of, for example, 5000 seconds to about 10000 seconds. In this example, the predetermined time is 10000 seconds. Next, the change rate (ΔR/R) of the resistance of each heating element 30 within a predetermined period of time is set in advance. First, the maximum resistance (Rmax) and minimum resistance (Rmin) within a predetermined time are obtained, and further, the difference (ΔR) between the maximum resistance (Rmax) and the minimum resistance (Rmin) and the average resistance (Rave) of the difference (ΔR) are calculated. Calculate the ratio (ΔR/Rave) for Let this ΔR/Rave be the resistance change rate (ΔR/R). For example, here, the rate of change (ΔR/R) is set to 0.02. On the other hand, the average temperature (Tave) within a predetermined time is obtained in the same way for the measured value of the temperature sensor 40 . In addition, the temperature change amount (ΔT) within a predetermined time is set in advance. As for the temperature change amount (ΔT), the difference between the maximum temperature (Tmax) and the minimum temperature (Tmin) within a predetermined time is first obtained as the temperature change amount (ΔT). For example, here, the temperature variation (ΔT) is 0.88°C. It is considered that the ratio (ΔR/R) and the amount of change in temperature (ΔT) are substantially constant for each heating element 30 unless the holding temperature changes greatly. The fact that the holding temperature does not change significantly means, for example, that the amount of change in the holding temperature is 100°C or less.

In the subsequent film formation, the average resistance (Rave) and the average temperature (Tave) of each heating element 30 may be obtained. That is, the maximum resistance (Rmax), minimum resistance (Rmin), maximum temperature (Tmax), and minimum temperature (Tmin) in the next and subsequent times are obtained as follows.

ΔR=Rave×0.02

Maximum resistance (Rmax)=Rave+ΔR/2

Minimum Resistance (Rmin)=Rave-ΔR/2

Maximum temperature (Tmax)=Tave+ΔT/2

Minimum temperature (Tmin)=Tave-ΔT/2

In this way, before the first film formation, it is necessary to obtain the maximum resistance (Rmax), minimum resistance (Rmin), maximum temperature (Tmax), and minimum temperature (Tmin) in advance. However, during the second and subsequent film formation, the maximum resistance (Rmax), the minimum resistance (Rmin), the maximum temperature (Tmax), and the minimum temperature (Tmin) are used by using the known resistance change rate (ΔR/R) and temperature change amount (ΔT). ) can be obtained. Moreover, since the temperature of the second heating element 32 is obtained based on the acquired coefficient in the case where there is no object W to be heated in the idle state, there is no need to prepare a wafer to obtain the coefficient. Further, in the preliminary test, the waste of the wafer can be reduced compared to the case where the wafer is formed into a film and the coefficient is obtained. When each of these parameters is obtained, the correlation between the resistance and temperature of the heating element 30 can be obtained.

If a preliminary test is conducted by the above method C and the relationship between the resistance and the temperature of the heating element 30 is obtained, the actual maximum resistance Rmax, minimum resistance Rmin, There is no need to measure the maximum temperature (Tmax) or minimum temperature (Tmin). Therefore, the temperature of the 2nd heating element 32 can be calculated|required more simply.

The heater control device can grasp the temperature of the zone corresponding to the second heating element 32 without providing the temperature sensor 40 to the second heating element 32 . The temperature of the first heating element 31 is detected by the temperature sensor 40 . The first power supplied to the first heating element 31 is controlled based on the temperature detected by the temperature sensor 40 . On the other hand, the second electric power supplied to the second heating element 32 is controlled to be a preset ratio with respect to the first electric power. Further, the temperature of the second heating element 32 is obtained by the calculator 65 based on the measured value of the second current sensor 52 . Therefore, even if there is no temperature sensor for detecting the temperature of the second heating element 32, the temperature of the second heating element 32 can be grasped.

Since the second power is controlled by the phase control method, it can be controlled with high precision. As a result, the temperature of the second heating element 32 can also be grasped with high accuracy.

The first heating element 31 and the second heating element 32 are controlled by the first power and the second power. Control by the power ratio is less affected by a change in resistance value due to self-heating of each heating element 30 than control by the current ratio. Also in this respect, the temperature of the second heating element 32 can be grasped accurately.

[Embodiment 2]

Next, Embodiment 2 will be described based on FIG. 10 . In Embodiment 1, it is possible to grasp the second temperature, which is the temperature of the second heating element 32, or to monitor whether the second temperature becomes an abnormal temperature. In contrast, in Embodiment 2, the temperature of the second heating element 32 can be controlled by controlling the second electric power by changing the ratio described above. Hereinafter, a description will mainly be given of differences from Embodiment 1, and descriptions of common points with Embodiment 1 will be omitted.

In Embodiment 2, in addition to the structure of Embodiment 1, the 2nd temperature controller 62 is further provided. The second temperature controller 62 outputs a second control signal for adjusting the ratio so that the second temperature approaches the target temperature. Control for adjusting this ratio can also use PID control. According to the second control signal, the second power controller 64 adjusts the ratio for obtaining the second power. Although the ratio is first power : second power = 1.0 : 0.8, when the second temperature is lower than the target temperature, it is necessary to increase the second power. In this case, for example, first power:second power = 1.0:0.81. Conversely, when the second temperature is higher than the target temperature, it is necessary to lower the second power. In this case, for example, first power:second power = 1.0:0.79. The fluctuation range of this ratio can be set appropriately, but it is preferable to set it to within 5% of the ratio of the second power before the change. In the above example, since the ratio of the second power before the change is 0.8, the ratio of the second power after the change is changed between 0.76 and 0.84. When power fluctuations that deviate from the fluctuation range of this ratio occur, a warning device (not shown) issues a warning to the user. With this warning, the user can detect an abnormality and deal with it appropriately.

The process procedure in Embodiment 2 is demonstrated based on FIG. This processing sequence is performed subsequent to step S3 in FIG. 5 . In step S21, the second control signal for adjusting the ratio is output by the second temperature controller 62 so that the second temperature approaches the target temperature. In step S22, the calculator 65 calculates the second power according to the adjusted ratio. Then, the second power is output to the second heating element 32 rather than the second power controller 64 .

According to the heater control device 1 of Embodiment 2, the second temperature of the second heating element 32 can be not only displayed on the external output unit 70, but also the temperature of the second heating element 32 can be controlled. .

[Embodiment 3]

Next, Embodiment 3 will be described. In Embodiment 3, the ratio for obtaining the second power is controlled so that the difference between the second temperature and the first temperature becomes zero as much as possible. The device configuration of Embodiment 3 is almost the same as that of Embodiment 2 described in FIG. 10 . In Embodiment 3, the 3rd temperature controller 62a is provided instead of the 2nd temperature controller 62. In Embodiment 2, the temperature Ts measured by the temperature sensor 40 is regarded as the temperature Th of the first heating element 31 itself, and is set as the first temperature. That is, strictly speaking, the temperature Th of the first heating element 31 is different from the temperature Ts measured by the temperature sensor 40 . This is because the temperature Ts transiently includes a temperature increase due to heat generation of the first heating element 31 itself.

In order to more accurately control the temperature distribution of each heating element 30, it is necessary to consider that the first temperature and the second temperature include a minute temperature increase due to self-heating of the heating element 30. Therefore, the difference between the second temperature and the first temperature is regarded as a difference in temperature distribution within the first surface 10a. Further, strictly speaking, the first temperature and the second temperature have different target temperatures. The third temperature controller 62a outputs a third control signal for adjusting the ratio so that the difference in the temperature distribution is the difference between the respective target temperatures of the second temperature and the first temperature. The second power controller 64 controls the second power according to the ratio adjusted by the third control signal. By controlling the second electric power, more precise temperature control of each heating element 30 becomes possible. As in Embodiment 2, when a change in power that deviates from the fluctuation range of this ratio occurs, an alarm device (not shown) issues a warning to the user. With this alert, the user can detect an abnormality and deal with it appropriately.

[Modification 1]

Modification 1 will be described based on FIGS. 12 and 13 . Modification 1 is a configuration applicable to any of Embodiments 1 to 3. In the modified example 1, there are six zones independently temperature-controlled in the base material 10 . That is, in the substrate 10, a circular inner region 10i located at the center of the substrate 10, a middle region 10m located outside the inner region 10i, and a position outside the middle region 10m An outer region 10e is provided. In Modification 1, the outer region 10e is divided in the circumferential direction of the substrate 10 . The number of second heating elements 32 provided in the divided outer region 10e may be plural. The number of divisions in this example is four. Each zone of the outer region 10e is a fan-shaped zone obtained by dividing an annular region into quarters. Second heating elements 32 are disposed in each zone of the outer region 10e divided into quarters. That is, the first heating element 31 is provided in the inner region 10i, one second heating element 32 is provided in the middle region 10m, and four second heating elements 32 are provided in the outer region 10e. Each heating element 30 can independently control the supplied power. A current sensor (not shown) is provided on each power line 30c connected to each heating element 30 .

According to the heater control device 1 of Modification Example 1, by using the second power controller 64, it is possible to realize cracking of the substrate 10 by using more heating elements 30 than in the first or second embodiments. there is.

[Modification 2]

Modification 2 will be described based on FIG. 14 . Modification 2 is a modification of Embodiment 1, and has a configuration in which the first heating element 31 and the second heating element 32 are insulated.

As shown in Fig. 14, in Modification 2, a first transformer 81 and a second transformer 82 are provided between the first heating element 31 and the power supply and between the second heating element 32 and the power supply, respectively. That is, the primary sides of the first transformer 81 and the second transformer 82 are connected to a power line branched off from the power supply. On the other hand, the secondary sides of the first transformer 81 and the second transformer 82 are connected to each other by independent power lines 30c. Therefore, the first heating element 31 and the second heating element 32 are insulated from each other.

According to Modification Example 2, in addition to the same effects as in Embodiment 1, the first heating element 31 and the second heating element 32 can be insulated more reliably.

[Modification 3]

Modification 3 will be described based on FIG. 15 . Modification 3 is a modification of Embodiment 2 or 3, and has a structure in which the first heating element 31 and the second heating element 32 are insulated.

As shown in Fig. 15, in Modification 3, a first transformer 81 and a second transformer 82 are provided between the first heating element 31 and the power supply and between the second heating element 32 and the power supply, respectively. That is, the primary sides of the first transformer 81 and the second transformer 82 are connected to a power line branched off from the power supply. On the other hand, the secondary sides of the first transformer 81 and the second transformer 82 are connected to each other by independent power lines 30c. Therefore, the first heating element 31 and the second heating element 32 are insulated from each other.

According to the modified example 3, in addition to the same effect as the second or third embodiment, the first heat generating element 31 and the second heat generating element 32 can be insulated more reliably.

In addition, it should be thought that embodiment disclosed this time is an illustration in all respects, and is not restrictive. This invention is not limited to these examples, It is shown by the claim, and it is intended that the meaning of a claim and equality, and all the changes within the range are included.

1 Heater control unit
10 description
10a first side
10b 2nd side
10i inner region
10 m middle zone
10e outer region
20 supports
21 Flange
30 heating element
31 first heating element
32 Second heating element
30t terminal
30c power line
40 temperature sensor
50 current sensor
51 first current sensor
52 second current sensor
60 controller
61 first temperature controller
62 second thermostat
62a third thermostat
63 first power controller
64 second power controller
65 arithmetic
66 memory
70 external output
80 trans
81 first trance
82 second trance
W heating target
w width
θ operating phase angle

Claims (8)

In the heater control device,
A substrate having a disk-shaped shape;
A tubular support coaxially attached to the substrate;
A first heating element disposed in a region including the center of the substrate;
At least one second heating element disposed concentrically with the first heating element;
A temperature sensor for measuring a first temperature of the first heating element;
at least one current sensor for measuring a current supplied to the at least one second heating element;
A first temperature controller outputting a first control signal so that the first temperature approaches a target temperature;
A first power controller controlling first power supplied to the first heating element according to the first control signal;
A second power controller controlling second power supplied to the second heating element;
Equipped with an operator for obtaining the temperature of the second heating element,
The substrate has a first surface on which a heating target is disposed, and a second surface facing the first surface,
The tubular support is attached to the second surface,
The temperature sensor is disposed inside the tubular support,
The second power controller controls the second power by a phase control method to have a preset ratio with respect to the first power,
The heater control device, wherein the calculator calculates the temperature of the second heating element based on the measured value of the at least one current sensor. According to claim 1,
The calculator calculates the temperature of the second heating element using the first temperature, the second voltage of the second heating element, and a predetermined coefficient;
The heater control device, wherein the coefficient is a coefficient representing a relationship between a resistance of the second heating element and a temperature of the second heating element. According to claim 2,
The heater control device, wherein the coefficient is a coefficient selected according to the first temperature from a plurality of predetermined coefficients. According to claim 3,
The plurality of coefficients are different when the temperature of the first heating element and the second heating element is increased, when the temperature is maintained, and when the temperature is decreased. According to claim 4,
The heater control device, wherein the coefficient is obtained based on the first temperature measured in a state in which the heating target is not disposed on the first surface during the temperature maintenance. According to any one of claims 1 to 5,
and an external output unit configured to display or transmit at least one of a temperature of the second heating element and a result of determining whether or not the temperature of the second heating element is within an appropriate range to an external device. According to any one of claims 1 to 6,
A second temperature controller is further provided;
The second temperature controller outputs a second control signal for adjusting the ratio so that the temperature of the second heating element approaches a target temperature;
The second power controller controls the second power according to the ratio adjusted by the second control signal. According to any one of claims 1 to 6,
Further comprising a third temperature controller,
The third temperature controller outputs a third control signal for adjusting the ratio so that the difference between the temperature of the second heating element and the first temperature is the difference between the target temperature of the second heating element and the first temperature. do,
Wherein the second power controller controls the second power according to the ratio adjusted by the third control signal.

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