Wafer heating apparatus and method

Abstract

1. A wafer heating device comprising: a mounting plate having an upper surface on which a wafer is placed; a heater disposed inside the mounting plate; and a temperature measuring element disposed inside the mounting plate, the mounting plate having a plurality of heating zones in a top view, the temperature measuring element including a differential thermocouple that measures a temperature difference ΔT between a first zone and a second zone which are different from each other in the plurality of heating zones.

Description

[Technical field]

[0001] The present disclosure relates to a wafer heating apparatus and a wafer heating method. [Background technology]

[0002] Patent Documents 1 to 3 disclose a wafer heating device that heats a wafer, for example, when forming a coating on the wafer. The wafer heating device includes a mounting plate having an upper surface on which the wafer is placed, and a heater that heats the wafer. The mounting plate has multiple heating zones when viewed from above. The temperature of each of the multiple heating zones is controlled independently.

[0003] In a wafer heating device, it is necessary to control the temperature of each of the multiple heating zones in order to heat the entire wafer uniformly. For this reason, temperature sensors that measure the temperature of each heating zone are placed inside the mounting plate. The temperature of each heating zone is adjusted based on the temperature information from each temperature sensor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 129641 [Patent Document 2] International Publication No. 2020 / 129754 [Patent Document 3] International Publication No. 2020 / 129798 Summary of the Invention

[0005] The wafer heating apparatus of the present disclosure includes a mounting plate having an upper surface on which a wafer is mounted, a heater disposed inside the mounting plate, and a temperature sensor disposed inside the mounting plate. The mounting plate has a plurality of heating zones in a top view. The temperature sensor includes a differential thermocouple that measures a temperature difference ΔT between a first zone and a second zone that are different from each other in the plurality of heating zones. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic configuration diagram of a wafer heating apparatus according to the first embodiment. [Diagram 2] FIG. 2 is a schematic diagram showing the arrangement of temperature measuring elements provided in the wafer heating apparatus shown in FIG. [Diagram 3] FIG. 3 is a schematic side view of the wafer heating apparatus shown in FIG. [Figure 4] FIG. 4 is a flowchart showing an example of temperature control in the wafer heating apparatus according to the first embodiment. [Diagram 5] FIG. 5 is a flowchart showing an example of temperature control in the wafer heating apparatus according to the second embodiment. [Figure 6] FIG. 6 is a schematic diagram showing the arrangement of temperature measuring elements provided in a wafer heating apparatus according to the third embodiment. [Figure 7] FIG. 7 is a schematic diagram illustrating the basic configuration of a differential thermocouple. [Figure 8] FIG. 8 is a schematic diagram illustrating a configuration in which a differential thermocouple includes three or more thermocouples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] [Problem that this disclosure aims to solve] In the conventional wafer heating apparatus, if there is a measurement error between the multiple temperature sensors on the mounting plate, it is difficult to match the temperatures of the multiple heating zones with high accuracy. In addition, the conventional wafer heating apparatus has a problem that the total number of conductors extending from the multiple temperature sensors is large, and the layout of the conductors and the connection to the detectors are complicated.

[0008] An object of the present disclosure is to provide a wafer heating apparatus that has a simple configuration and is capable of matching the temperatures of multiple heating zones with high accuracy.

[0009] [Description of the embodiments of the present disclosure] The embodiments of the present disclosure are listed and described below.

[0010] <1> A wafer heating apparatus according to an embodiment includes a mounting plate having an upper surface on which a wafer is mounted, a heater disposed inside the mounting plate, and a temperature sensor disposed inside the mounting plate. The mounting plate has a plurality of heating zones in a top view. The temperature sensor includes a differential thermocouple that measures a temperature difference ΔT between a first zone and a second zone that are different from each other in the plurality of heating zones.

[0011] In the present disclosure, a "differential thermocouple" refers to a thermocouple configured by connecting a first thermocouple and a second thermocouple arranged at two different locations in series. A method for connecting a differential thermocouple will be described later. With a differential thermocouple, an electromotive force corresponding to a temperature difference between a location where the first thermocouple is arranged and a location where the second thermocouple is arranged is obtained. That is, the wafer heating apparatus according to the embodiment includes a first thermocouple and a second thermocouple arranged in a first zone and a second zone, respectively, and is equipped with a differential thermocouple in which the first thermocouple and the second thermocouple are connected so as to generate an electromotive force corresponding to a temperature difference ΔT between the first zone and the second zone.

[0012] In the wafer heating apparatus according to the embodiment, the differential thermocouple included in the temperature detector has a first measurement unit and a second measurement unit. In the differential thermocouple in which the first measurement unit is arranged in the first zone and the second measurement unit is arranged in the second zone, a potential difference ΔV corresponding to the temperature difference ΔT between the first zone and the second zone is output. The temperature difference ΔT is a function of the potential difference ΔV, and ΔT=f(ΔV) holds. If the temperature difference ΔT is zero, the potential difference ΔV is zero. If g is an inverse function of f, ΔV=g(ΔT) holds. In other words, the temperature difference ΔT can be calculated from the potential difference ΔV, which is the output voltage of the differential thermocouple.

[0013] A typical thermocouple measures the temperature of the temperature measuring part by measuring the thermoelectromotive force generated by the temperature difference between the temperature measuring part and the terminal part of the voltmeter. It is very costly to make a measuring device in which the terminal part of the voltmeter is an ideal cold junction of zero degrees Celsius. In addition, maintaining such a measuring device is cumbersome. Therefore, in a typical thermocouple, the temperature of the terminal part of the voltmeter is accurately measured, and the difference between the temperature of the terminal part and zero degrees Celsius is corrected by a cold junction compensation circuit. In this case, the measurement error of the temperature of the terminal part directly becomes the measurement error of the thermocouple. On the other hand, a differential thermocouple that measures the temperature difference ΔT does not require a cold junction and can measure the temperature difference ΔT of two heating zones. Therefore, the differential thermocouple does not have the problem of the measurement error of each temperature sensor that occurs when the temperatures of the two heating zones are measured by two independent temperature sensors. Therefore, in the above-mentioned wafer heating device, the temperature of the first zone and the temperature of the second zone can be matched with high accuracy by adjusting the temperature of the first zone and the temperature of the second zone based on the temperature difference ΔT obtained by the differential thermocouple.

[0014] In the above-mentioned wafer heating apparatus, the number of conductors extending from the temperature sensors can be reduced. For example, when independent temperature sensors are arranged in the first zone and the second zone, the number of temperature sensors is two, and the total number of conductors extending from the two temperature sensors is four. On the other hand, the total number of conductors extending from the differential thermocouple arranged across the first zone and the second zone is two. As shown in the embodiment described later, when a plurality of differential thermocouples are arranged on the mounting plate, the conductors can be shared between different differential thermocouples. In that case, the total number of conductors extending from the temperature sensors is further reduced, making it easier to arrange the conductors and connect them to the detector.

[0015] <2> the above <1> The wafer heating apparatus described in the above item 1 may further include a temperature sensor disposed in the first zone, and the temperature sensor may be a resistance temperature detector or a thermocouple.

[0016] If a temperature sensor is placed in the first zone, the temperature T1 of the first zone can be measured based on the output voltage from the temperature sensor. The temperature T2 of the second zone can be calculated based on this temperature T1 and the temperature difference ΔT obtained from the differential thermocouple. By calculating the temperature T2, it is easy to match the temperature T1 of the first zone with the temperature T2 of the second zone with high accuracy.

[0017] The resistance thermometer has excellent temperature resolution, so it can accurately measure the temperature T1 of the first zone. The thermocouple has a simple structure, so it is easy to place it inside the mounting plate. In addition, the thermocouple has excellent responsiveness, so it can quickly measure the temperature of the heating zone where the temperature sensor is placed.

[0018] <3> the above <1> or <2> In the wafer heating apparatus described in the above, the support plate has a circular plate shape, and the multiple heating zones consist of a circular central zone and at least one peripheral zone arranged on the periphery of the central zone, and the central zone may be the first zone and the at least one peripheral zone may be the second zone.

[0019] the above <3> In the above configuration, it is easy to make the temperature of the central zone and the temperature of the peripheral zone match with high accuracy. <3> This configuration can uniformly heat the entire surface of the wafer placed on the placement plate.

[0020] <4> the above <3> In the wafer heating apparatus described above, the at least one outer circumferential zone may be composed of a plurality of outer circumferential zones surrounding the central zone, and each of the plurality of outer circumferential zones may be the second zone.

[0021] In the outer peripheral portion of the support plate excluding the central zone, the temperature is likely to vary due to the influence of the external environment of the support plate. <4> In the configuration of (a), the portion of the support plate near the periphery is divided into a plurality of peripheral zones, and therefore, by adjusting the temperature of each of the plurality of peripheral zones, it is easy to make the temperature of the entire portion of the support plate near the periphery uniform.

[0022] the above <4> In the above configuration, each of the multiple outer circumferential zones is the second zone. <4> The configuration has multiple differential thermocouples that measure the temperature difference ΔT between the central zone and each of the peripheral zones. <4> In this configuration, the temperature of each heating zone is adjusted based on the temperature difference ΔT between the central zone and each peripheral zone, making it easy to uniformize the temperature of the entire mounting plate. This type of wafer heating device can heat the entire wafer uniformly.

[0023] <5> the above <1> from <4> In the wafer heating apparatus described in any one of claims 1 to 5, the mounting plate may include, in order from above, a top plate having the upper surface, a sensor plate having the differential thermocouple, and a heater plate having the heater. The top plate, the sensor plate, and the heater plate are joined together, and the differential thermocouple is formed by a metal wire printed on the sensor plate.

[0024] The mounting plate formed by joining the top plate, the sensor plate, and the heater plate is highly productive. In addition, since the differential thermocouple is formed by printing, it is easier to position the first measurement part and the second measurement part of the differential thermocouple at the desired positions than in a configuration in which a differential thermocouple prepared separately from the mounting plate is arranged on the mounting plate.

[0025] <6> the above <1> from <5> In the wafer heating apparatus described in any one of the above, further comprising a control unit that controls the heater, the heater having a plurality of heat generating elements disposed in each of the plurality of heating zones, each of the plurality of heat generating elements being controlled by the control unit.

[0026] the above <6> In the configuration of (a), each heating unit corresponding to each of the multiple heating zones is controlled independently, so that the temperature of each heating zone can be adjusted with high precision.

[0027] <7> the above <6> The wafer heating apparatus described in the above may further include a temperature sensor disposed in the first zone, and the control unit may determine a temperature T2 of the second zone based on a temperature T1 of the first zone obtained by the temperature sensor and the temperature difference ΔT obtained by the differential thermocouple, and control the heater so that the temperature T2 becomes a target temperature.

[0028] the above <7> In the configuration, the temperature T1 of the first zone and the temperature T2 of the second zone are calculated, and then the temperature T2 is controlled to be the same as the target temperature, i.e., the temperature T1. Therefore, in this configuration, it is easy to accurately adjust both the temperatures of the first zone and the second zone to the target temperatures.

[0029] <8> the above <6> In the wafer heating apparatus described in the above, the control unit may determine the temperature difference ΔT based on an output voltage of the differential thermocouple, and control the heater so that the temperature difference ΔT approaches zero.

[0030] the above <8> In this configuration, the heater is controlled so that the temperature difference ΔT between the first zone and the second zone approaches zero, so that the temperature of the first zone and the temperature of the second zone tend to match quickly. In addition, the control of this configuration can be configured by an analog circuit, and the configuration of the control unit can be easily simplified. Of course, the control of this configuration is not limited to being configured by an analog circuit, and may be configured by a digital circuit.

[0031] <9> A first wafer heating method according to an embodiment is a wafer heating method for heating a wafer placed on an upper surface of a mounting plate using a wafer heating device including a mounting plate, a heater disposed inside the mounting plate, and a temperature measuring element disposed inside the mounting plate. The mounting plate has a plurality of heating zones in a top view, and the temperature measuring element includes a differential thermocouple for measuring a temperature difference ΔT between a first zone and a second zone that are independent of each other in the plurality of heating zones. In the first wafer heating method, the heater is controlled so that a temperature T1 of the first zone becomes a target temperature, a temperature T2 of the second zone is calculated based on the temperature T1 and the temperature difference ΔT, and the heater is controlled so that the temperature T2 becomes the target temperature.

[0032] In the first heating method, the temperature T1 of the first zone is controlled, and the temperature T2 of the second zone is calculated based on the temperature T1 and the temperature difference ΔT, and the temperature T2 is controlled to be the same as the temperature T1. Therefore, according to the first heating method, it is easy to accurately adjust both the temperatures of the first zone and the second zone to the target temperatures.

[0033] <10> A second wafer heating method according to the embodiment is a wafer heating method for heating a wafer placed on an upper surface of a mounting plate using a wafer heating device including a mounting plate, a heater disposed inside the mounting plate, and a temperature sensor disposed inside the mounting plate. The mounting plate has a plurality of heating zones in a top view, and the temperature sensor includes a differential thermocouple that measures a temperature difference ΔT between a first zone and a second zone that are independent of each other in the plurality of heating zones. In the second wafer heating method, the heater is controlled so that the temperature difference ΔT approaches zero.

[0034] In the second heating method, the heater is controlled so that the temperature difference ΔT between the first zone and the second zone approaches zero. Therefore, according to the second heating method, it is easy to quickly make the temperature of the first zone and the temperature of the second zone coincide with each other.

[0035] [Details of the embodiment of the present disclosure] Hereinafter, specific examples of wafer heating devices according to embodiments of the present disclosure will be described with reference to the drawings. The same reference numerals in the drawings indicate the same or equivalent parts. The sizes of the members shown in the drawings are expressed for the purpose of clarifying the description and do not necessarily represent the actual dimensions. Note that the present invention is not limited to these examples, but is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0036] <Embodiment 1> <Overall composition> The wafer heating apparatus 1 illustrated in Fig. 1 is used in a film formation process for forming a coating on the surface of a wafer. The wafer heating apparatus 1 of this example includes a mounting plate 2, a heater 3, and a control unit 4. The wafer heating apparatus 1 of this example further includes a temperature detector 5 and a temperature sensor 7. Each component of the wafer heating apparatus 1 will be described in detail below.

[0037] <Placement plate> 1, the mounting plate 2 is shown exploded into a top plate 21, a sensor plate 22, and a heater plate 23. The mounting plate 2 has an upper surface 2U that is disposed facing upward in the wafer heating apparatus 1, and a lower surface 2L that is disposed facing downward. The lower surface 2L is the surface opposite to the upper surface 2U. A wafer is placed on the upper surface 2U of the mounting plate 2 when a coating is formed on the surface of the wafer using the wafer heating apparatus 1 of this embodiment. The wafer is, for example, a silicon wafer.

[0038] The mounting plate 2 in this example is a disk. The diameter of the disk needs to be larger than the wafer to be mounted on the upper surface 2U, for example, 200 mm or more and 500 mm or less. The planar shape of the mounting plate 2 is not limited to a circle, and may be any shape similar to the planar shape of the wafer. For example, the planar shape of the mounting plate 2 may be a polygon such as a rectangle.

[0039] The material of the support plate 2 is, for example, ceramics. The ceramics are, for example, aluminum nitride, aluminum oxide, or silicon carbide (SiC). The material of the support plate 2 may be a composite of the above ceramics and silicon (Si). The composite is, for example, Si-SiC, which is a porous SiC body impregnated with silicon.

[0040] The mounting plate 2 of this example includes, in order from the top, a top plate 21, a sensor plate 22, and a heater plate 23. The top plate 21, the sensor plate 22, and the heater plate 23 are prepared separately. The mounting plate 2 of this example is formed by joining these three plates. The joining of the three plates may be performed by adhesion or by fastening with a fastening member. Unlike this example, the mounting plate 2 may be formed from a single member.

[0041] The top plate 21 has a surface that constitutes the upper surface 2U of the mounting plate 2. The top plate 21 may be provided with a vacuum port for adsorbing a wafer, or may be provided with pin holes in which lift pins for lifting the wafer are disposed.

[0042] The sensor plate 22 includes a temperature detector 5 and a temperature sensor 7, which will be described later. The temperature detector 5 and the temperature sensor 7 measure the temperature at various points on the mounting plate 2. The detailed configurations and arrangements of the temperature detector 5 and the temperature sensor 7 will be described later.

[0043] The heater plate 23 includes a plurality of heat generating parts 3A, 3B, 3C, 3D, and 3E which are part of the heater 3 described later. In FIG. 1, only the area in which the heat generating parts 3A, 3B, 3C, 3D, and 3E are arranged is shown, and the heat generating parts 3A, 3B, 3C, 3D, and 3E themselves are not shown. The plurality of heat generating parts 3A, 3B, 3C, 3D, and 3E are independent of each other. Therefore, the temperature of each of the heat generating parts 3A, 3B, 3C, 3D, and 3E can be changed independently. By making the sensor plate 22 and the heater plate 23 independent members, the temperature measuring element 5 and the temperature sensor 7 do not interfere with the heat generating parts 3A, 3B, 3C, 3D, and 3E. Therefore, there is a high degree of freedom in the arrangement of the temperature measuring element 5, the temperature sensor 7, and the heat generating parts 3A, 3B, 3C, 3D, and 3E.

[0044] The mounting plate 2 has a plurality of heating zones 2A, 2B, 2C, 2D, and 2E heated by a plurality of heat generating parts 3A, 3B, 3C, 3D, and 3E, respectively, when viewed from above. The heating zones 2A, 2B, 2C, 2D, and 2E are virtual regions. In FIG. 1, the heating zones 2A, 2B, 2C, 2D, and 2E, which are partitioned by two-dot chain lines, are shown only on the sensor plate 22. In this example, the circular heating zone 2A including the center of the mounting plate 2 is called the central zone, and the arc-shaped heating zones 2B, 2C, 2D, and 2E surrounding the circular heating zone 2A are called the peripheral zones.

[0045] A coolant flow path (not shown) may be arranged inside the mounting plate 2. A coolant is supplied to the coolant flow path as required. The coolant flow path is configured to quickly cool the mounting plate 2 heated by the heater 3. By quickly cooling the mounting plate 2, the time required to start processing a new wafer can be shortened.

[0046] The mounting plate 2 in this example is supported by a cylindrical support 9. The support 9 supports the lower surface 2L of the mounting plate 2 as shown in FIG. 3. FIG. 3 is a side view of the vicinity of the mounting plate 2 of the wafer heating device 1, and the support 9 is shown in a state cut by a plane along its axis. The shape of the support 9 is not particularly limited. The support 9 in this example is cylindrical. The support 9 is disposed approximately concentrically with the mounting plate 2. In this example, the mounting plate 2 is attached on the support 9 so that the central axis of the cylindrical support 9 and the central axis of the disk-shaped mounting plate 2 are coaxial. Inside the support 9, the conductors 51W, 52W, 53W, 54W, and 55W extending from the temperature measuring element 5, the sensor wire 7W extending from the temperature sensor 7, and the like are disposed. In FIG. 1, only the conductor 51W is shown.

[0047] The material of the support 9 is, for example, ceramics. The material of the support 9 may be the same as the material of the mounting plate 2, or may be different.

[0048] <Heater> As shown in FIG. 1, the heater 3 includes a power source 30 and a plurality of heat generating parts 3A, 3B, 3C, 3D, and 3E that generate heat by power supplied from the power source 30. As described above, the plurality of heat generating parts 3A, 3B, 3C, 3D, and 3E are disposed inside the mounting plate 2. The heat generating parts 3A, 3B, 3C, 3D, and 3E are connected to the power source 30 by power lines 3W that are independent of each other. Only one power line 3W is shown in FIG. 1. The power line 3W is disposed inside the support 9 shown in FIG. 3. The amount of power supplied to each of the heat generating parts 3A, 3B, 3C, 3D, and 3E is adjusted by the control unit 4, which will be described later. The heat generated by the heat generating parts 3A, 3B, 3C, 3D, and 3E is transferred from inside the mounting plate 2 to the upper surface 2U, and heats the wafer.

[0049] The heating parts 3A, 3B, 3C, 3D, and 3E in this example are resistance heating elements. The resistance heating elements in this example are circuit patterns formed by printing on the upper surface of the heater plate 23. In this case, holes are formed in the heater plate 23 that penetrate from the circuit pattern to the lower surface of the heater plate 23. The power lines 3W pass through these holes and are connected to the heating parts 3A, 3B, 3C, 3D, and 3E. The material of the resistance heating elements is, for example, one selected from the group consisting of stainless steel, nickel, nickel alloy, silver, silver alloy, tungsten, tungsten alloy, molybdenum, molybdenum alloy, chromium, and chromium alloy. The nickel alloy is, for example, nichrome.

[0050] Unlike this example, the heat generating portions 3A, 3B, 3C, 3D, and 3E may be configured independent of the heater plate 23. For example, a heater sheet including the heat generating portions 3A, 3B, 3C, 3D, and 3E may be disposed on the upper surface of the heater plate 23. The heater sheet has a configuration in which the heat generating portions 3A, 3B, 3C, 3D, and 3E configured by circuit patterns are sandwiched between two polyimide sheets.

[0051] <Temperature measuring element> The temperature measuring element 5 includes a differential thermocouple 6 that measures a temperature difference ΔT between two different zones. Here, the basic configuration of the differential thermocouple 6 will be described with reference to FIG. 7. The differential thermocouple 6 is configured by connecting a first metal wire 61, a second metal wire 62, and a third metal wire 63 in series. The first metal wire 61 and the third metal wire 63 are connected to a conductor wire 61W and a conductor wire 63W, respectively. The first metal wire 61 and the second metal wire 62 are configured from different metals, and the second metal wire 62 and the third metal wire 63 are configured from different metals. The first metal wire 61 and the third metal wire 63 are made of the same metal, and the conductor wire 61W and the conductor wire 63W are made of the same metal. The joint between the first metal wire 61 and the second metal wire 62 is a first measuring portion 65, and the joint between the second metal wire 62 and the third metal wire 63 is a second measuring portion 66. In the differential thermocouple 6 having such a configuration, a potential difference ΔV is generated between the conductor 61W and the conductor 63W in accordance with the temperature difference ΔT between the first zone Z1 in which the first measuring unit 65 is arranged and the second zone Z2 in which the second measuring unit 66 is arranged. The potential difference ΔV is a function of the temperature difference ΔT, and ΔT=f(ΔV) holds. If g is an inverse function of f, then ΔV=g(ΔT) holds. In other words, the temperature difference ΔT can be calculated from the potential difference ΔV, which is the output voltage of the differential thermocouple.

[0052] The combination of two metal wires to be joined is, for example, a combination of copper and Constantan, a combination of Alumel and Chromel, a combination of tungsten and tungsten-rhenium, or a combination of platinum and rhodium.

[0053] The metals constituting the first metal wire 61 and the conductor 61W may be the same metal or different metals. The third metal wire 63 and the conductor 63W may be the same metal or different metals. When the first metal wire 61 and the conductor 61W are made of different metals, the measurement accuracy is improved by arranging the joint between the first metal wire 61 and the conductor 61W in the first zone Z1. Similarly, when the third metal wire 63 and the conductor 63W are made of different metals, the measurement accuracy is improved by arranging the joint between the third metal wire 63 and the conductor 63W in the second zone Z2.

[0054] In addition, when the temperature difference between the first measuring part 65 and the second measuring part 66 is minute and the potential difference ΔV, which is the output voltage, is small, the differential thermocouple 6, as shown in FIG. four The above thermocouples may be connected in series. The differential thermocouple 6 in FIG. 8 includes, in order from the conductor 61W, a first metal wire 61, a second metal wire 62, a first metal wire 61, a second metal wire 62, First metal wire 61, second metal wire 62, The third metal wires 63 are connected in series. In this case, two first measuring parts 65, 65 and two second measuring parts 66, 66 are formed. The two first measuring parts 65, 65 are arranged in the first zone Z1, and the two second measuring parts 66, 66 are arranged in the second zone Z2. The potential difference ΔV increases according to the number of thermocouples connected in series.

[0055] Based on the basic configuration of the differential thermocouple 6, the configuration of the temperature sensor 5 in this embodiment will be described with reference to Fig. 2. Here, the positions of each part of the temperature sensor 5 will be described by comparing the upper surface of the sensor plate 22 with the face of a clock.

[0056] First, the arrangement of heating zones 2A, 2B, 2C, 2D, and 2E on the sensor plate 22 will be described. Heating zone 2A, which is arranged at the center of the sensor plate 22, is a circular central zone. The four heating zones 2B, 2C, 2D, and 2E, which are arranged to surround the outer periphery of heating zone 2A, are arc-shaped outer periphery zones having width. Heating zone 2B is arranged at the 12 o'clock to 3 o'clock position, heating zone 2C is arranged at the 3 o'clock to 6 o'clock position, heating zone 2D is arranged at the 6 o'clock to 9 o'clock position, and heating zone 2E is arranged at the 9 o'clock to 12 o'clock position.

[0057] The temperature detector 5 includes a plurality of metal wires 5X, 5Y, 5A, 5B, 5C, 5D, and 5E arranged on the upper surface of the sensor plate 22. The metal wire 5X extends from the heating zone 2B through the heating zone 2A to the heating zone 2D. The metal wire 5Y extends from the heating zone 2C through the heating zone 2A to the heating zone 2E. The metal wires 5X and 5Y are electrically connected at an intersection 50. The intersection 50 is arranged in the heating zone 2A. The metal wires 5X and 5Y are made of the same metal.

[0058] The metal wire 5A extends from the intersection 50 to a position near the intersection 50. The metal wire 5B extends from a first end of the metal wire 5X arranged in the heating zone 2B to a position near the intersection 50. The metal wire 5C extends from a first end of the metal wire 5Y arranged in the heating zone 2C to a position near the intersection 50. The metal wire 5D extends from a second end of the metal wire 5X arranged in the heating zone 2D to a position near the intersection 50. The metal wire 5E extends from a second end of the metal wire 5Y arranged in the heating zone 2E to a position near the intersection 50. The ends of the metal wires 5A, 5B, 5C, 5D, and 5E indicated by black circles may be located anywhere within the range of the heating zone 2A. The metal wires 5A, 5B, 5C, 5D, and 5E are made of the same metal. The metal wires 5A, 5B, 5C, 5D, and 5E and the metal wires 5X and 5Y are made of different metals.

[0059] Conductors 51W, 52W, 53W, 54W, and 55W, indicated by dashed lines, are connected to the ends of metal wires 5A, 5B, 5C, 5D, and 5E, indicated by black circles. The conductive wires 51W, 52W, 53W, 54W, and 55W are disposed inside the support 9 as shown in FIG. 3. The ends of the conductive wires 51W, 52W, 53W, 54W, and 55W, indicated by hatched circles, are connected to the detection unit 8 shown in FIG. 1. The detection unit 8 in this example is a voltmeter that can measure the voltage between any two conductive wires. Note that the temperature sensor 5 is simplified in FIG. 3.

[0060] The temperature detector 5 having the above configuration has five measurement parts 51, 52, 53, 54, and 55, indicated by white circles. The measurement part 51 is an intersection 50 which is a joint between the metal wire 5X and the metal wire 5A, and also a joint between the metal wire 5Y and the metal wire 5A. The measurement part 52 is a joint between the metal wire 5X and the metal wire 5B. The measurement part 53 is a joint between the metal wire 5Y and the metal wire 5C. The measurement part 54 is a joint between the metal wire 5X and the metal wire 5D. The measurement part 55 is a joint between the metal wire 5Y and the metal wire 5E. With such a temperature detector 5, the temperature difference ΔT between two different measurement parts can be measured. Specifically, the temperature measuring element 5 of this example can measure four types of temperature differences ΔT: between measuring portion 51 and measuring portion 52, between measuring portion 51 and measuring portion 53, between measuring portion 51 and measuring portion 54, and between measuring portion 51 and measuring portion 55. That is, the temperature measuring element 5 of this example includes four differential thermocouples 6.

[0061] Here, the temperature measuring element 5 having the above configuration can also measure temperature differences ΔT between measuring units 52 and 53, between measuring units 52 and 54, between measuring units 52 and 55, between measuring units 53 and 54, between measuring units 53 and 55, and between measuring units 54 and 55. However, in this example, these temperature differences ΔT are not used to control the heater 3.

[0062] The temperature difference ΔT between two different measurement parts is determined by the potential difference ΔV between the two different measurement parts. For example, to determine the temperature difference ΔT between measurement parts 51 and 52, i.e., the temperature difference ΔT between heating zones 2A and 2B, it is sufficient to measure the potential difference ΔV between conductor 51W and conductor 52W. In this case, heating zone 2A and heating zone 2B correspond to first zone Z1 and second zone Z2 in FIG. 7, respectively.

[0063] The metal wires 5X, 5Y, 5A, 5B, 5C, 5D, and 5E constituting the temperature measuring element 5 are formed, for example, by embedding in the mounting plate 2 or by printing on the sensor plate 22. In the former case, grooves are provided on the surface of the sensor plate 22, and the metal wires 5X, 5Y, 5A, 5B, 5C, 5D, and 5E are arranged therein. Then, the sensor plate 22 is sandwiched between the top plate 21 and the heater plate 23, so that the metal wires 5X, 5Y, 5A, 5B, 5C, 5D, and 5E are embedded in the mounting plate 2. The grooves may be formed on the upper surface or the lower surface of the sensor plate 22. The printing may be, for example, screen printing, flexographic printing, gravure printing, gravure offset printing, dispenser printing, or inkjet printing. In these printing methods, a conductive paste in which metal particles are dispersed in a binder is applied to the upper or lower surface of the sensor plate 22. By hardening or dissipating the binder, the metal wires 5X, 5Y, 5A, 5B, 5C, 5D, and 5E are formed. By forming the temperature sensor 5 by printing, it is easy to arrange the measuring portions 51, 52, 53, 54, and 55 at desired positions.

[0064] When the temperature detector 5 is formed by printing, holes are formed from the ends of the metal wires 5A, 5B, 5C, 5D, and 5E indicated by black circles through to the lower surface 2L of the mounting plate 2. The conductor wires 51W, 52W, 53W, 54W, and 55W pass through these holes and are connected to the ends of the metal wires 5A, 5B, 5C, 5D, and 5E. Since the ends of the metal wires 5A, 5B, 5C, 5D, and 5E are gathered at the center of the mounting plate 2, the conductor wires 51W, 52W, 53W, 54W, and 55W are simply drawn out of the holes and placed inside the support 9 (FIG. 3).

[0065] <Temperature sensor> The wafer heating apparatus 1 of this embodiment further includes a temperature sensor 7 for measuring the temperature of any one of the heating zones 2A, 2B, 2C, 2D, and 2E. The temperature sensor 7 of this embodiment is disposed in the heating zone 2A, which is the central zone. Unlike this embodiment, the temperature sensor 7 may be disposed in the peripheral zone. The temperature sensor 7 is, for example, a resistance temperature detector or a thermocouple. A resistance temperature detector has excellent temperature resolution. A thermocouple has a simple structure and is therefore easy to place inside the mounting plate 2. Furthermore, a thermocouple has excellent responsiveness, so the temperature of the heating zone 2A can be measured quickly.

[0066] The temperature sensor 7 makes it possible to measure the temperature T1 of the heating zone 2A in which it is arranged. The temperature T1 is used as a reference for adjusting the temperatures of the remaining heating zones 2B, 2C, 2D, 2E in which no temperature sensor 7 is arranged.

[0067] 3, a sensor wire 7W connected to the temperature sensor 7 passes through a hole in the mounting plate 2 (not shown) and is led out into the support 9. The sensor wire 7W has a configuration in which two conductor wires are combined into one by an insulating coating.

[0068] <Control Unit> 1 controls the heater 3 based on the measurement results of the differential thermocouple 6 and the temperature sensor 7. Specifically, the control unit 4 controls the power supply 30 to control the power supplied to the heat generating units 3A, 3B, 3C, 3D, and 3E. In addition to controlling the heater 3, the control unit 4 may also control components in the wafer heating apparatus 1 other than the heater 3.

[0069] Each process by the control unit 4 is realized by a processing circuit including at least one processor. The processing circuit may be composed of an integrated circuit in which at least one memory, various analog circuits, and various digital circuits are combined in addition to the at least one processor. The at least one memory stores a program (instruction) that causes the at least one processor to execute each of the above processes. The at least one processor may execute each of the above processes according to the program read from the at least one memory, or may execute each of the above processes according to a logic circuit designed in advance to execute each of the above processes. The processor may be, for example, a CPU or a GPU, or any of various other processors suitable for computer control. Note that the above processes may be executed by multiple physically separated processors working together.

[0070] <Wafer heating method> An example of a wafer heating method for heating a wafer placed on the upper surface of a mounting plate 2 using a wafer heating apparatus 1 according to the first embodiment will be described. In the following description, an example in which a control unit 4 of the wafer heating apparatus 1 controls heating zones 2A and 2B will be described mainly with reference to Figures 1 and 2. In this case, heating zone 2A is a first zone Z1, and heating zone 2B is a second zone Z2.

[0071] In this example, the heater 3 is controlled so that the temperature T1 of the first zone Z1 becomes a target temperature, and the temperature T2 of the second zone Z2 is calculated based on the temperature T1 and the temperature difference ΔT, and the heater 3 is controlled so that the temperature T2 becomes the target temperature.

[0072] First, the control unit 4 supplies power to the heat generating unit 3A to heat the first zone Z1, and supplies power to the heat generating unit 3B to heat the second zone Z2. Furthermore, the control unit 4 adjusts the temperature so that the difference between the temperature T1 and the temperature T2 becomes small. The temperature adjustment is performed, for example, according to the flowchart of FIG.

[0073] The control unit 4 grasps the temperature T1 of the first zone Z1 based on real-time information from the temperature sensor 7 measured by the detection unit 8 (step S1 in FIG. 4). The control unit 4 maintains the temperature T1 at a target temperature by adjusting the amount of power supplied to the heat generating unit 3A. The target temperature is, for example, within a range of 500°C to 600°C. The control unit 4 further grasps the temperature difference ΔT between the temperature T1 of the first zone Z1 and the temperature T2 of the second zone Z2 based on real-time information from the differential thermocouple 6 measured by the detection unit 8 (step S2). Here, the information of the temperature sensor 7 and the differential thermocouple 6 measured by the detection unit 8 is a voltage value. The voltage value information is converted into temperature information by a computer constituting the control unit 4.

[0074] The control unit 4 determines the temperature T2 of the second zone Z2 based on the temperature T1 obtained by the temperature sensor 7 and the temperature difference ΔT obtained from the differential thermocouple 6 (step S3). Specifically, the temperature T1 of the temperature sensor 7 disposed near the measurement unit 51 is regarded as the temperature T1 at the measurement unit 51, and the temperature T2 is determined.

[0075] The control unit 4 determines whether the difference between the temperature T2 and the target temperature exceeds a predetermined value (step S4). The predetermined value may be zero. If the predetermined value is set to a small value, the temperature T1 of the first zone Z1 and the temperature T2 of the second zone Z2 can be made to match with high accuracy. The target temperature of the temperature T2 is the same as the target temperature of the temperature T1. If the difference between the temperature T2 and the target temperature is equal to or less than the predetermined value, the control unit 4 maintains the amount of power supplied to the heater 3 without changing it, and returns to the processing of step S1 again.

[0076] If the difference between temperature T2 and the target temperature exceeds a predetermined value, control unit 4 controls power supply 30 of heater 3 to adjust the amount of power supplied to heat generating unit 3B (step S5). For example, if temperature T2 is higher than temperature T1, the power supplied to heat generating unit 3B is reduced or the power supply to heat generating unit 3B is stopped. If temperature T2 is lower than temperature T1, the power supplied to heat generating unit 3B is increased.

[0077] After controlling the heater 3, the control unit 4 determines whether or not the heating of the wafer has been completed (step S6). The completion of the heating is determined, for example, by the passage of time. When the time from the start of the heat treatment of the wafer reaches or exceeds a predetermined time, it is determined that the processing such as film formation on the wafer has been completed, that is, it is no longer necessary to heat the wafer. If the heating of the wafer has not been completed, the control unit 4 returns to the processing of step S1 again. If the heating of the wafer has been completed, the control unit 4 ends the temperature adjustment.

[0078] The differential thermocouple 6 that measures the temperature difference ΔT does not have the problem of measurement error of each temperature sensor 7 that occurs when the temperature T1 of the first zone Z1 and the temperature T2 of the second zone Z2 are measured by two independent temperature sensors 7. Therefore, in the wafer heating apparatus 1 of this example, the temperature T1 of the first zone Z1 and the temperature T2 of the second zone Z2 can be made to match with high accuracy based on the temperature difference ΔT obtained by the differential thermocouple 6. In particular, in a configuration in which the temperature T1 of the first zone Z1 is controlled and the temperature T2 of the second zone Z2 obtained based on the temperature T1 and the temperature difference ΔT is controlled, both the temperature T1 of the first zone Z1 and the temperature T2 of the second zone Z2 are easily adjusted to the target temperatures accurately.

[0079] By carrying out the above-mentioned temperature adjustment control for all of the outer circumferential zones, it is possible to make the temperature of the entire mounting plate 2 almost uniform. Therefore, the wafer heating apparatus 1 of this embodiment can heat the entire wafer uniformly.

[0080] In this example, the total number of conductors extending from the configuration for measuring the temperatures of the five heating zones is seven. Specifically, the number of conductors 51W, 52W, 53W, 54W, and 55W extending from the temperature measuring element 5 is five, and the number of conductors extending from the temperature sensor 7 is two. If a temperature sensor 7 is provided in each of the five heating zones, the total number of conductors is ten, and the connection of the conductors to the detection unit 8 is complicated.

[0081] <Embodiment 2> In the second embodiment, a wafer heating apparatus 1 will be described in which the temperature sensor 7 is removed from the configuration of the first embodiment. In the description, FIGS.

[0082] The wafer heating apparatus 1 of the second embodiment does not include the temperature sensor 7. Therefore, the wafer heating apparatus 1 of this example does not require the effort of preparing the temperature sensor 7 and the effort of connecting the sensor wire 7W (FIG. 3) extending from the temperature sensor 7 to the detection unit 8.

[0083] Heating zone 2A, which is a central zone located at the center of mounting plate 2, is surrounded by heating zones 2B, 2C, 2D, and 2E, which are peripheral zones. Therefore, the temperature of heating zone 2A is likely to be stable, and the amount of power supplied to heat generating unit 3A that heats heating zone 2A and the temperature of heating zone 2A are likely to correlate. For example, by supplying power to heat generating unit 3A according to a predetermined power supply pattern, the temperature of heating zone 2A is likely to be maintained at a target temperature. Therefore, heating zone 2A can be brought to a target temperature even without a temperature sensor 7 for measuring the temperature of heating zone 2A.

[0084] On the other hand, the temperature of the outer periphery zone is easily affected by the external environment and is easily changed. Therefore, in this example, the heater 3 is controlled based on the temperature difference ΔT between the central zone and each outer periphery zone so that the temperature of the outer periphery zone approaches the temperature of the central zone. An example of a wafer heating method based on such control will be described with reference to the flowchart of FIG. 5. In the following description, an example will be described in which the control unit 4 of the wafer heating apparatus 1 controls the heating zone 2A and the heating zone 2B. In this case, the heating zone 2A is the first zone Z1, and the heating zone 2B is the second zone Z2.

[0085] The control unit 4 determines the temperature difference ΔT between the temperature T1 of the first zone Z1 and the temperature T2 of the second zone Z2 based on real-time information from the differential thermocouple 6 measured by the detection unit 8 (step S1 in FIG. 5).

[0086] The control unit 4 determines whether the temperature difference ΔT exceeds a predetermined value (step S2). The predetermined value may be zero. If the predetermined value is set to a small value, the temperature T1 of the first zone Z1 and the temperature T2 of the second zone Z2 can be made to match with high accuracy. If the temperature difference ΔT is equal to or less than the predetermined value, the control unit 4 maintains the amount of power supplied to the heater 3 without changing it, and returns to the processing of step S1 again.

[0087] If the temperature difference ΔT exceeds a predetermined value, the control unit 4 controls the power supply 30 of the heater 3 so that the temperature difference ΔT approaches 0, and adjusts the amount of power supplied to the heat generating unit 3B (step S3). For example, if the temperature T2 is higher than the temperature T1, the amount of power supplied to the heat generating unit 3B is reduced, or power supply to the heat generating unit 3B is stopped. If the temperature T2 is lower than the temperature T1, the amount of power supplied to the heat generating unit 3B is increased.

[0088] After controlling the heater 3, the control unit 4 judges whether the heating of the wafer is completed or not (step S4). If the heating of the wafer is not completed, the control unit 4 returns to the process of step S1 again. If the heating of the wafer is completed, the control unit 4 ends the temperature adjustment.

[0089] By carrying out the above-mentioned temperature adjustment control for all of the outer circumferential zones, it is possible to make the temperature of the entire mounting plate 2 almost uniform. Therefore, the wafer heating apparatus 1 of this embodiment can heat the entire wafer uniformly.

[0090] <Embodiment 3> In the third embodiment, a wafer heating apparatus 1 having a different configuration of the temperature measuring element 5 from that of the first embodiment will be described with reference to FIG. 6. The way of viewing FIG. 6 is the same as that of FIG. 2. In this example, the differences from the first embodiment will be described, and the description of the same configuration as that of the first embodiment will be omitted. In describing this example, FIG. 1 will be referred to as appropriate.

[0091] The temperature sensor 5 shown in Fig. 6 differs from the temperature sensor 5 of the first embodiment in that it does not have the metal wire 5A and the conductive wire 51W shown in Fig. 2. In this configuration, the temperature difference ΔT between any two of the four measuring parts 52, 53, 54, and 55 is measured. For example, the temperature difference ΔT between the measuring part 52 and the measuring part 53 is measured.

[0092] In the wafer heating apparatus 1 of this embodiment, the temperature of the heating zone 2A, which is the central zone, is managed based on information from a temperature sensor 7. Meanwhile, the temperatures of the heating zones 2B, 2C, 2D, and 2E, which are the peripheral zones, are managed based on information from a differential thermocouple 6 constituting a temperature measuring element 5. As an example of the management of the temperature of the peripheral zones, an example will be described in which the control unit 4 of the wafer heating apparatus 1 controls the heating zones 2B and 2C. In this case, the heating zone 2B is the first zone Z1, and the heating zone 2C is the second zone Z2.

[0093] The control unit 4 supplies power to the heat generating unit 3B to heat the first zone Z1, and supplies power to the heat generating unit 3C to heat the second zone Z2. The correlation between the amount of power supplied to the heat generating unit 3A and the temperature T1 of the first zone Z1, and the correlation between the amount of power supplied to the heat generating unit 3C and the temperature T2 of the second zone Z2 are grasped in advance. The control unit 4 adjusts the amount of power based on these correlations, so that the temperatures T1 and T2 are adjusted to values ​​that are generally close to the target temperatures. Therefore, in this example, the heater 3 is controlled so that the temperatures T1 and T2 are approximately the same. Specifically, the heater 3 is controlled so that the temperature difference ΔT between the first zone Z1 and the second zone Z2 approaches zero according to the flowchart of FIG. 5 described in the second embodiment.

[0094] By carrying out the above-mentioned temperature adjustment control for all the outer circumferential zones, it is possible to make the temperature almost uniform over the entirety of the mounting plate 2. The temperature adjustment control in this example is simple, and it is easy to quickly make the temperature over the entirety of the mounting plate 2 uniform.

[0095] <Other embodiments> The wafer heating apparatus 1 equipped with the temperature measuring element 5 may be used for pre-baking in a photolithography process, or for an inspection process for measuring electrical characteristics of a wafer.

[0096] When the mounting plate 2 is provided with a cooling mechanism, the temperature of the heating zones 2A, 2B, 2C, 2D, and 2E may be adjusted by the cooling mechanism. In this case, the heat generating portion of the heater 3 may be a single heat generating portion disposed on the entire surface of the heater plate 23.

[0097] In addition, in the wafer heating apparatus 1 equipped with the temperature detector 5, the temperatures of the heating zones 2A, 2B, 2C, 2D, and 2E can be controlled to be different from one another by changing the control program by the control unit 4. For example, the temperature of the heating zone 2A, which is the central zone, can be made higher or lower than the temperatures of the other heating zones 2B, 2C, 2D, and 2E. [Explanation of symbols]

[0098] 1 Wafer heating device 2. Placement plate 2A,2B,2C,2D,2E Heating zone 2L bottom 2U top 21 Top Plate 22 Sensor plate 23 Heater Plate 3 Heater 3A,3B,3C,3D,3E Heat generating part 3W Power Line 30 power supply 4. Control Unit 5 Temperature sensor 5A,5B,5C,5D,5E,5X,5Y Metal wire 50 intersection 51,52,53,54,55 Measuring part 51W,52W,53W,54W,55W conductor 6 Differential Thermocouple 61 Daiichi Metal Wire 62 Second metal wire 63 Third metal wire 65 First measurement section 66 Second measuring section 61W,63W conductor 7 Temperature Sensor 7W sensor wire 8. Detection Unit 9 Support Z1 First Zone Z2 Second Zone

Claims

1. a disk-shaped mounting plate having an upper surface on which a wafer is placed; A heater disposed inside the mounting plate; A temperature sensor disposed inside the mounting plate, The mounting plate has a plurality of heating zones in a top view, The temperature measuring element includes a differential thermocouple that measures a temperature difference ΔT between a first zone and a second zone that are different from each other in the plurality of heating zones, The plurality of heating zones include a circular central zone and at least one peripheral zone disposed around the central zone, the central zone is the first zone and the at least one peripheral zone is the second zone; The differential thermocouple is a first metal wire, a second metal wire, and a third metal wire connected in series; a first measurement portion which is a joint between the first metal wire and the second metal wire; a second measurement portion which is a joint between the second metal wire and the third metal wire; a first conductive wire connected to the first metal wire; a second conductive wire connected to the third metal wire; the first measurement unit is disposed in the first zone, and the second measurement unit is disposed in the second zone; a joint between the first metal wire and the first conductive wire is disposed in the first zone; a joint between the third metal wire and the second conductive wire is disposed in the first zone; the first conducting wire and the second conducting wire are each drawn out to the outside of the support plate in the first zone, the first metal wire and the third metal wire are made of the same metal; the first metal wire and the second metal wire are dissimilar metals; the first conductive wire and the second conductive wire are made of the same metal; The first conductive wire and the first metal wire are made of different metals. Wafer heating device.

2. The at least one peripheral zone comprises a plurality of peripheral zones surrounding the central zone, The wafer heating apparatus of claim 1 , wherein each of said plurality of peripheral zones is said second zone.

3. Further comprising a temperature sensor disposed in the first zone, 3. The wafer heating apparatus according to claim 1, wherein the temperature sensor is a resistance temperature detector or a thermocouple.

4. the mounting plate includes, in order from above, a top plate having the upper surface, a sensor plate having the differential thermocouple, and a heater plate having the heater; the top plate, the sensor plate, and the heater plate are joined together; 3. The wafer heating apparatus according to claim 1, wherein the first metal wire, the second metal wire, and the third metal wire are formed by metal wires printed on the sensor plate.

5. Further, a control unit that controls the heater is provided. The heater includes a plurality of heat generating units disposed in the plurality of heating zones, 3. The wafer heating apparatus according to claim 1, wherein each of said plurality of heat generating parts is controlled by said control part.

6. Further comprising a temperature sensor disposed in the first zone, 6. The wafer heating apparatus of claim 5, wherein the control unit determines a temperature T2 of the second zone based on a temperature T1 of the first zone obtained by the temperature sensor and the temperature difference ΔT obtained by the differential thermocouple, and controls the heater so that the temperature T2 becomes a target temperature.

7. 6. The wafer heating apparatus according to claim 5, wherein the control unit determines the temperature difference ΔT based on an output voltage of the differential thermocouple, and controls the heater so that the temperature difference ΔT approaches zero.

8. A wafer heating method using a wafer heating device including a disk-shaped mounting plate, a heater disposed inside the mounting plate, and a temperature measuring element disposed inside the mounting plate, for heating a wafer placed on an upper surface of the mounting plate, comprising: The mounting plate has a plurality of heating zones in a top view, The temperature measuring element includes a differential thermocouple that measures a temperature difference ΔT between a first zone and a second zone that are independent of each other in the plurality of heating zones, The plurality of heating zones include a circular central zone and at least one peripheral zone disposed around the central zone, the central zone is the first zone and the at least one peripheral zone is the second zone; The differential thermocouple is a first metal wire, a second metal wire, and a third metal wire connected in series; a first measurement portion which is a joint between the first metal wire and the second metal wire; a second measurement portion which is a joint between the second metal wire and the third metal wire; a first conductive wire connected to the first metal wire; a second conductive wire connected to the third metal wire; the first measurement unit is disposed in the first zone, and the second measurement unit is disposed in the second zone; a joint between the first metal wire and the first conductive wire is disposed in the first zone; a joint between the third metal wire and the second conductive wire is disposed in the first zone; the first conducting wire and the second conducting wire are each drawn out to the outside of the support plate in the first zone, the first metal wire and the third metal wire are made of the same metal; the first metal wire and the second metal wire are dissimilar metals; the first conductive wire and the second conductive wire are made of the same metal; the first conducting wire and the first metal wire are made of different metals; Controlling the heater so that the temperature T1 of the first zone becomes a target temperature; determining a temperature T2 of the second zone based on the temperature T1 and the temperature difference ΔT, and controlling the heater so that the temperature T2 becomes the target temperature; Wafer heating method.

9. A wafer heating method using a wafer heating device including a disk-shaped mounting plate, a heater disposed inside the mounting plate, and a temperature measuring element disposed inside the mounting plate, for heating a wafer placed on an upper surface of the mounting plate, comprising: The mounting plate has a plurality of heating zones in a top view, The temperature measuring element includes a differential thermocouple that measures a temperature difference ΔT between a first zone and a second zone that are independent of each other in the plurality of heating zones, The plurality of heating zones include a circular central zone and at least one peripheral zone disposed around the central zone, the central zone is the first zone and the at least one peripheral zone is the second zone; The differential thermocouple is a first metal wire, a second metal wire, and a third metal wire connected in series; a first measurement portion which is a joint between the first metal wire and the second metal wire; a second measurement portion which is a joint between the second metal wire and the third metal wire; a first conductive wire connected to the first metal wire; a second conductive wire connected to the third metal wire; the first measurement unit is disposed in the first zone, and the second measurement unit is disposed in the second zone; a joint between the first metal wire and the first conductive wire is disposed in the first zone; a joint between the third metal wire and the second conductive wire is disposed in the first zone; the first conducting wire and the second conducting wire are each drawn out to the outside of the support plate in the first zone, the first metal wire and the third metal wire are made of the same metal; the first metal wire and the second metal wire are dissimilar metals; the first conductive wire and the second conductive wire are made of the same metal; the first conducting wire and the first metal wire are made of different metals; controlling the heater so that the temperature difference ΔT approaches zero; Wafer heating method.

Images