Wafer chuck, temperature control system, and temperature control method

Abstract

The present application provides a wafer chuck capable of measuring temperature without increasing the number of temperature sensors provided, and a temperature control system and a temperature control method capable of appropriately controlling the temperature of the wafer chuck. The present application is provided with: a heating and cooling section (40) that heats or cools a wafer chuck (18); at least one temperature sensor (52) disposed on the wafer chuck (18); and a heat flow sensor (54) disposed on the wafer chuck (18), a plurality of thermocouples (56) connected in series, and the connection portions of the thermocouples (56) adjacent to each other alternately disposed at a first depth position from a holding surface (18A) and a second depth position deeper than the first depth position, the heat flow sensor (54) having a plurality of temperature measurement points (60) provided corresponding to each thermocouple (56), the plurality of temperature measurement points (60) disposed in the range of the entire wafer chuck (18) when the wafer chuck (18) is viewed from above.

Description

Technical Field

[0001] This invention relates to a wafer chuck, a temperature control system, and a temperature control method. Background Technology

[0002] In semiconductor manufacturing, semiconductor wafers undergo various processes to form multiple chips (bare dies), each containing semiconductor devices. The electrical characteristics of each chip are inspected, and after being cut by a dicing machine, they are fixed to lead frames and assembled. Electrical characteristic checks are performed using a wafer testing system consisting of detectors and measuring instruments. The detector holds the wafer in a wafer chuck and brings probes into contact with the electrode pads of each chip. The measuring instrument supplies power and various test signals from terminals connected to the probes, analyzes the signals output to the chip's electrodes, and confirms whether the semiconductor devices of the chip under inspection are functioning correctly.

[0003] In the detector, the temperature during the inspection of electrical characteristics needs to be set and maintained constant. Therefore, in order to detect the heat generated by the semiconductor device (DUT) of the chip being inspected, the wafer chuck is equipped with temperature sensors such as resistive temperature sensors and thermocouple temperature sensors, and the temperature of the wafer chuck is controlled based on the detection results of the temperature sensors.

[0004] For example, the detector disclosed in Patent Document 1 is equipped with multiple temperature sensors on the wafer chuck (detector chuck), and the temperature control of the wafer chuck is based on the detection result of the temperature sensor that is closest to the device under test that is being inspected among the multiple temperature sensors.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2006-294873 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] However, in the detector disclosed in Patent Document 1, in order to accurately measure the temperature of the wafer chuck corresponding to the heat-generating part of the device under test, it is necessary to increase the number of temperature sensors installed on the wafer chuck. However, due to the limitations of the internal structure of the wafer chuck, there are limitations on the number and location of these sensors, making it difficult to assemble multiple temperature sensors in ideal positions. In addition, when multiple temperature sensors are installed, the number of signal lines required for each temperature sensor corresponds to the number of temperature sensors, making wiring very difficult.

[0010] In particular, when the device under test is a SoC (System on Chip) device such as a CPU (Central Processing Unit), GPU (Graphics Processing Unit), or APU (Accelerated Processing Unit), it generates significantly more localized heat compared to memory devices. Therefore, when it is not possible to place multiple temperature sensors on the wafer chuck, it is difficult to properly control the temperature of the wafer chuck in response to the heat generated by the device under test.

[0011] The present invention was made in view of the following circumstances, and its object is to provide a wafer chuck that can measure the temperature of the wafer chuck corresponding to the heat-generating part of the wafer without increasing the number of temperature sensors installed, a temperature control system that can appropriately control the temperature of the wafer chuck, and a temperature control method.

[0012] Solution for solving the problem

[0013] A wafer chuck for achieving the purpose of the present invention has a holding surface for holding wafers. The wafer chuck includes: a heating and cooling section for heating or cooling the wafer chuck; at least one temperature sensor disposed on the wafer chuck; and a heat flow sensor disposed on the wafer chuck. A plurality of thermocouples are connected in series, and the connection portions of adjacent thermocouples are alternately disposed at a first depth position from the holding surface and a second depth position deeper than the first depth position. The heat flow sensor has a plurality of temperature measuring points disposed corresponding to each thermocouple. When viewed from above, the plurality of temperature measuring points are disposed over the entire area of ​​the wafer chuck.

[0014] Based on this wafer chuck, the temperature of the wafer chuck corresponding to the heat-generating part of the wafer can be measured without increasing the number of temperature sensors installed.

[0015] In other embodiments of the present invention, a plurality of temperature sensors are distributed in the wafer chuck. Thus, when the device under test (DUT) in the wafer being inspected heats up, the temperature of the wafer chuck in a portion unaffected by this heat can be detected using at least one of the plurality of temperature sensors.

[0016] The temperature control system for achieving the purpose of the present invention includes the above-described thermal conductivity wafer chuck and a temperature control unit that calculates the control temperature based on the detection results of the temperature sensor and the detection results of the heat flow sensor.

[0017] According to this temperature control system, the temperature of the wafer chuck can be properly controlled without increasing the number of temperature sensors installed on the wafer chuck.

[0018] In another aspect of the temperature control system of the present invention, the temperature control unit performs the following processing: when the portion of the wafer chuck corresponding to the heat-generating portion of the wafer is taken as the corresponding portion, the temperature at a second depth position, i.e., the reference temperature, at the corresponding portion is detected based on the detection results of the temperature sensor; the temperature difference between the first depth position and the second depth position at the corresponding portion is calculated based on the detection results of the heat flow sensor; and the temperature of the corresponding portion, i.e., the temperature of the heat-generating portion's measuring point, is calculated based on the reference temperature and the temperature difference as the control temperature. Thus, the temperature of the wafer chuck can be appropriately controlled without increasing the number of temperature sensors provided on the wafer chuck.

[0019] In another aspect of the temperature control system of the present invention, the temperature control unit performs the following processing: when the portion of the wafer chuck corresponding to the heat-generating portion of the wafer is taken as the corresponding portion, the temperature at a second depth position, i.e., the reference temperature, at the corresponding portion is detected based on the detection results of the temperature sensor; the temperature difference between the first depth position and the second depth position at the corresponding portion is calculated based on the detection results of the heat flow sensor; and the temperature of the heat-generating portion of the wafer, i.e., the device temperature, is calculated as the control temperature based on the reference temperature, the temperature difference, and data including the physical properties and dimensions of the wafer and the wafer chuck. Thus, the temperature of the wafer chuck can be appropriately controlled without increasing the number of temperature sensors provided on the wafer chuck.

[0020] In other aspects of the temperature control system of the present invention, multiple temperature sensors are distributed in a dispersed manner on the wafer chuck, and the temperature control unit detects the lowest temperature, average value or central value from the temperatures detected by the multiple temperature sensors as a reference temperature.

[0021] In other aspects of the temperature control system of the present invention, the temperature control unit controls the heating and cooling unit in such a way that the control temperature becomes a preset target temperature.

[0022] The temperature control method for achieving the purpose of the present invention, based on the temperature control method for controlling the temperature of the wafer chuck described above, includes: a reference temperature detection step, wherein at least one temperature sensor detects a reference temperature of the wafer chuck; a heat flow detection step, wherein a heat flow sensor detects the heat flow generated due to localized heating of the wafer held on the holding surface; and a temperature control step, wherein a control temperature is calculated based on the detection results of the temperature sensor and the detection results of the heat flow sensor.

[0023] In other aspects of the temperature control method of the present invention, in the reference temperature detection step, the temperature at the second depth position of the corresponding part in the wafer chuck corresponding to the heat-generating part of the wafer is detected as the reference temperature. The temperature control step includes the following processing: calculating the upper and lower temperature difference between the first depth position and the second depth position of the corresponding part based on the detection result of the heat flow detection step; and calculating the temperature of the corresponding part, i.e., the temperature of the temperature measuring point of the heat-generating part, based on the reference temperature and the upper and lower temperature difference as the control temperature.

[0024] In other aspects of the temperature control method of the present invention, in the reference temperature detection step, the temperature at the second depth position of the corresponding portion of the wafer chuck corresponding to the heat-generating portion of the wafer is detected as the reference temperature. The temperature control step includes the following processing: calculating the upper and lower temperature difference between the first depth position and the second depth position of the corresponding portion based on the detection result of the heat flow detection step; and calculating the control temperature based on the reference temperature, the upper and lower temperature difference, and data including the physical properties and dimensions of the wafer and the wafer chuck, i.e., the device temperature, of the heat-generating portion of the wafer.

[0025] In other aspects of the temperature control method of the present invention, the temperature control step includes the following process: heating or cooling the wafer chuck in a manner that makes the control temperature a preset target temperature.

[0026] Invention Effects

[0027] According to the present invention, the temperature of the wafer chuck corresponding to the heat-generating portion of the wafer can be measured without increasing the number of temperature sensors installed. Furthermore, the temperature of the wafer chuck can be appropriately controlled. Attached Figure Description

[0028] Figure 1 This is a schematic diagram showing the overall structure of the wafer testing system.

[0029] Figure 2 This is a schematic diagram of the temperature control system according to the first embodiment.

[0030] Figure 3 It shows a top view and an enlarged cross-sectional view of the internal structure of the wafer chuck.

[0031] Figure 4 This is a functional block diagram showing the structure of the temperature control device in the first embodiment.

[0032] Figure 5 This is a conceptual diagram of a calculation example based on the area of ​​the heat-generating part obtained from a heat flow sensor.

[0033] Figure 6This is a flowchart illustrating an example of a temperature control method in a temperature control system according to the first embodiment.

[0034] Figure 7 This is a diagram showing a structural example of a heat flow sensor consisting of two sensor bodies.

[0035] Figure 8 This is a schematic diagram of the temperature control system involved in the first variation.

[0036] Figure 9 This is a schematic diagram of the temperature control system involved in the second variation.

[0037] Figure 10 This is a functional block diagram showing the structure of the temperature control device in the second embodiment.

[0038] Figure 11 This is an explanatory diagram used to illustrate the method for calculating device temperature. Detailed Implementation

[0039] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[0040] <Chip Testing System>

[0041] Figure 1 This is a schematic diagram showing the overall structure of the wafer testing system 1. It should be noted that the following explanation uses an XYZ orthogonal coordinate system with the plane parallel to the wafer chuck 18 as the XY plane.

[0042] Figure 1 The wafer testing system 1 shown includes: a detector 10 that contacts the electrodes of each chip on the wafer W with a probe 25, and a measuring device 30 that is electrically connected to the probe 25 and applies current and voltage to each chip and measures its characteristics for electrical inspection.

[0043] The detector 10 includes: a base 11, a movable base 12 disposed on the base 11, a Y-axis movable stage 13, an X-axis movable stage 14, a Z-axis movable rotating part 15, a wafer chuck 18, a wafer alignment camera 19, pillars 20 and 21, a head stage 22, and a probe card 24 mounted on the head stage 22.

[0044] Probe 25 is provided on probe card 24. It should be noted that although a positioning camera for detecting the position of probe 25 and a cleaning mechanism for cleaning probe are provided, they are omitted here.

[0045] The movable base 12, the Y-axis movable stage 13, the X-axis movable stage 14, and the Z-axis movable rotating part 15 constitute a moving and rotating mechanism that moves the wafer chuck 18 along the three axes and rotates it about the Z-axis. Since the moving and rotating mechanism is well known, its description is omitted here.

[0046] The wafer chuck 18 holds a wafer W with multiple chips formed on it by vacuum adsorption. A holding surface 18A for holding the wafer W is provided on the upper surface of the wafer chuck 18.

[0047] A heating and cooling section 40, serving as a heating and cooling source, is provided inside the wafer chuck 18 to enable electrical characteristic checks of the chip at high temperatures (e.g., up to 150°C) or low temperatures (e.g., down to -40°C). The heating and cooling section 40 heats or cools the wafer chuck 18. Suitable heaters and / or coolers can be used as the heating and cooling section 40. Various components can be used as the heating and cooling section 40, such as components combining heaters and cooling plates, components combining Peltier elements and cooling plates, double-layer structures employing a heating layer with a surface heater and a cooling layer with a cooling fluid passage, and single-layer structures with a heater wound in a heat conductor and a cooling pipe embedded within it. The heating and cooling section 40 is an example of the heating and cooling section of the present invention.

[0048] The wafer chuck 18 is mounted on the Z-axis moving and rotating part 15. The wafer chuck 18 can move along three axes (X-axis, Y-axis, and Z-axis) by means of the moving and rotating mechanism described above, and can rotate in the rotation direction (θ direction) about the Z-axis.

[0049] A probe card 24 is disposed above the wafer chuck 18 that holds the wafer W. The probe card 24 is mounted in a detachable manner to the opening (probe card mounting part) of the head platform 22 of the top plate that constitutes the housing of the detector 10.

[0050] The probe card 24 has probes 25 configured according to the electrode configuration of the chip being inspected, and is replaced according to the chip being inspected.

[0051] The measuring device 30 includes a measuring device body 31 and a contact ring 32 disposed on the measuring device body 31. Electrodes connected to each probe 25 are disposed on the probe holder 24. The contact ring 32 has a spring probe configured to contact the electrode. The measuring device body 31 is held on the detector 10 by a support mechanism (not shown).

[0052] The control device 90 functions by executing a control program to control the overall movement of the detector 10. For example, the control device 90 controls the movement of the aforementioned moving and rotating mechanisms (moving base 12, Y-axis moving stage 13, X-axis moving stage 14, and Z-axis moving and rotating part 15). Additionally, the control device 90 controls the movement of the measuring instrument 30 and the heating and cooling unit 40. It should be noted that the control device 90 includes the temperature control device 100 described later (see [reference]). Figure 2 ).

[0053] <Temperature Control System>

[0054] Next, the temperature control system of the detector 10 assembled in this embodiment will be described. It should be noted that the temperature control system is an example of the temperature control system in this invention.

[0055] (First Implementation)

[0056] Figure 2 This is a schematic diagram of the temperature control system 50 according to the first embodiment. Figure 3 This is a top view showing the outline of the internal structure of the chip chuck 18.

[0057] like Figure 2 As shown, the temperature control system 50 of the first embodiment includes a wafer chuck 18, a temperature control device 100, a plurality of temperature sensors 52, a heat flow sensor 54, a cooling plate 42, and a heater 44. The cooling plate 42 and the heater 44 are constituent elements of the heating and cooling section 40 described above.

[0058] The wafer chuck 18 includes a chuck top suction plate 28. The chuck top suction plate 28 forms part of the upper side (the side where the wafer W is disposed) of the wafer chuck 18. The chuck top suction plate 28 has a chuck top surface 28A corresponding to the holding surface 18A of the wafer chuck 18, and a chuck top back surface 28B opposite to the chuck top surface 28A (holding surface 18A). A cooling plate 42 is disposed inside the chuck top suction plate 28. A heater 44 is disposed on the lower side of the chuck top suction plate 28 (opposite to the side where the wafer W is disposed) at a position in contact with the chuck top back surface 28B.

[0059] A cooling device 92 is connected to the cooling plate 42, and coolant is supplied to the cooling plate 42 from the cooling device 92 under the control of the temperature control device 100. A heater power supply 94 is connected to the heater 44, and heater power is supplied to the heater 44 from the heater power supply 94 under the control of the temperature control device 100.

[0060] Multiple temperature sensors 52 are disposed inside the wafer chuck 18 (chuck top suction plate 28). Each temperature sensor 52 is composed of, for example, a resistance temperature detector (RTD) or a thermocouple (TC).

[0061] Multiple temperature sensors 52 are uniformly distributed in a top view (view along the Z direction) of the wafer chuck 18 (chuck top suction plate 28) (see reference). Figure 3 This is used to detect the reference temperature Tref of the wafer chuck 18, which will be described later. In this embodiment, as an example, such as Figure 3 As shown, five temperature sensors 52 are disposed inside the suction plate 28 at the top of the chuck. Specifically, of the five temperature sensors 52, one temperature sensor 52 is disposed at the center of the wafer chuck 18, and the remaining four temperature sensors 52 are evenly distributed circumferentially on the outer periphery of the wafer chuck 18. Each temperature sensor 52 can be unevenly distributed when viewed from above, as long as it can detect the reference temperature Tref of the wafer chuck 18.

[0062] It should be noted that the term "distributed configuration" refers to the arrangement of multiple temperature sensors 52 at predetermined intervals. This configuration ensures that, when the device under test (DUT) in the wafer W being inspected heats up, at least one of the multiple temperature sensors 52 can detect the temperature of the wafer chuck 18 (equivalent to the aforementioned reference temperature Tref) in a portion unaffected by the heat. In other words, it refers to a configuration where the multiple temperature sensors 52 are not arranged close to each DUT according to the number of DUTs in the wafer W, but rather arranged at a distance from each other so that at least one temperature sensor 52 can detect the reference temperature Tref of the wafer chuck 18.

[0063] The heat flow sensor 54, together with the temperature sensor 52, is disposed inside the wafer chuck 18 (chuck top suction plate 28). The heat flow sensor 54 is used to detect the heat generated by the device under test as heat flow (heat flux: the amount of heat flowing through a unit area per unit time). It should be noted that the "heat flow sensor" is also called the "heat flux sensor".

[0064] like Figure 2 as well as Figure 3As shown, the heat flux sensor 54 is constructed by connecting multiple thermocouples 56 (at several temperature measurement points) in series. At both ends of the heat flux sensor 54, there are output wiring sections 80 for outputting an output signal (voltage signal) (hereinafter referred to as "sensor signal") representing the heat flux (heat transfer rate) detected by the heat flux sensor 54. The output wiring sections 80 are connected to the temperature control device 100 and are configured to input the sensor signal output from the heat flux sensor 54 to the temperature control device 100.

[0065] Each thermocouple 56 is constructed by joining different types of metals 56A and 56B, and has a temperature measuring point 60 that forms the connection between metals 56A and 56B. That is, the heat flow sensor 54 has a temperature measuring point 60 in each thermocouple 56. Each temperature measuring point 60 is disposed in an upper position (on the side of the top surface 28A of the chuck) inside the top adsorption plate 28 of the chuck, and is closely arranged throughout the entire wafer chuck 18 when viewed from above (along the Z direction). It should be noted that "closely arranged" means that, when viewed from above the wafer chuck 18, the arrangement is such that the heat generated by the device under test locally in the wafer W can be detected, and the arrangement density of the multiple temperature measuring points 60 is at least higher than the arrangement density of the multiple temperature sensors 52. In addition, from the viewpoint of detecting the heat generated locally in the device under test in the wafer W, the multiple temperature measuring points 60 are preferably arranged uniformly and closely within the entire wafer chuck 18 when viewed from above, but are not limited thereto, the multiple temperature measuring points 60 may also be arranged non-uniformly.

[0066] Furthermore, the heat flow sensor 54 has reference contacts 62 that form the connection portions of adjacent thermocouples 56 connected in series (i.e., the connection portion of metal 56A of one thermocouple 56 to metal 56B of another thermocouple 56). That is, the heat flow sensor 54 has multiple reference contacts 62. Each reference contact 62 is disposed at a predetermined position on the back surface 28B of the chuck top, which is below the chuck top suction plate 28. It should be noted that, in this embodiment, as an example, each reference contact 62 is disposed at the midpoint between the adjacent thermocouples 56 connected in series when viewed from above (along the Z direction) from the wafer chuck 18.

[0067] Here, an example of a specific mounting method of the heat flow sensor 54 relative to the chip chuck 18 will be described. For example... Figure 3As shown in the enlarged view, thermocouple receiving slots 34 are provided on the chuck top adsorption plate 28 constituting the wafer chuck 18 at positions corresponding to each temperature measuring point 60. Each thermocouple receiving slot 34 is a bottomed, elongated groove formed on the back surface 28B of the chuck top adsorption plate 28. Each thermocouple receiving slot 34 houses the front end portions (temperature measuring point 60 side portions) of the metals 56A and 56B constituting the thermocouple 56. Furthermore, at the bottom of each thermocouple receiving slot 34 (on the chuck top surface 28A side); Figure 3 The temperature measuring point 60 is formed by connecting the front end portions of metals 56A and 56B, which correspond to and constitute thermocouple 56 respectively, on the upper side (middle).

[0068] In addition, the base end portions of the metals 56A and 56B constituting the thermocouple 56 are arranged along the outside of each thermocouple receiving groove 34, i.e., the back surface 28B of the chuck top, and respectively form a reference contact 62 by connecting with the base end portions of the metals 56A or 56B of other adjacent thermocouples 56 connected in series.

[0069] By providing multiple thermocouple receiving slots 34 relative to the wafer chuck 18 (chuck top suction plate 28) in this manner, multiple thermocouples 56 connected in series can be efficiently and easily assembled onto the wafer chuck 18. It should be noted that, in this embodiment, as a preferred embodiment, a configuration of multiple thermocouple receiving slots 34 relative to the wafer chuck 18 is shown. However, as long as multiple temperature measuring points 60 of the heat flow sensor 54 can be closely arranged within the entire area of ​​the wafer chuck 18 when viewed from above, the mounting method of the heat flow sensor 54 relative to the wafer chuck 18 is not particularly limited.

[0070] Figure 4 This is a functional block diagram illustrating the structure of the temperature control device 100. The temperature control device 100 includes arithmetic circuits composed of various processors and memory. These processors include CPUs (Central Processing Units), GPUs (Graphics Processing Units), ASICs (Application Specific Integrated Circuits), and programmable logic devices (such as SPLDs (Simple Programmable Logic Devices), CPLDs (Complex Programmable Logic Devices), and FPGAs (Field Programmable Gate Arrays)). It should be noted that the various functions of the temperature control device 100 can be implemented by a single processor or by multiple processors of the same or different types.

[0071] The temperature control device 100 functions as a reference temperature detection unit 102, a temperature difference detection unit 104, and a temperature control unit 106 by executing a control program (not shown).

[0072] The reference temperature detection unit 102 is connected to a plurality of temperature sensors 52 to obtain the temperature of the wafer chuck 18 detected by each temperature sensor 52. The reference temperature detection unit 102 detects (selects) the lowest temperature, average value, or median value from the temperatures detected by each temperature sensor 52 as the reference temperature Tref of the wafer chuck 18. Furthermore, the reference temperature Tref detected by the reference temperature detection unit 102 is input to the temperature control unit 106. The reference temperature detection unit 102 is an example of the reference temperature detection unit of the present invention.

[0073] It should be noted that the so-called "reference temperature Tref" refers to the temperature of the wafer chuck 18 at the portion of the wafer W that is unaffected by the heating of the device under test (DUT) in the wafer W being inspected. In this embodiment, among the multiple temperature sensors 52, the temperature sensor 52 located furthest from the DUT that is locally heating in the wafer W detects the temperature with the least and lowest impact from the heating of the DUT. Therefore, the lowest temperature is selected as the reference temperature Tref from the temperatures detected by each temperature sensor 52. However, sometimes when the temperature of the wafer chuck 18 is detected to rise due to the heating of the device, the wafer chuck 18 has excellent temperature tracking performance for temperature control. Therefore, there is also a method of using the average or median value of the temperatures detected by each temperature sensor 52 as the reference temperature Tref of the wafer chuck 18.

[0074] Furthermore, the reference temperature Tref detected by the reference temperature detection unit 102 can be considered to be substantially equal to the temperature of the portion of the wafer chuck 18 that is not easily affected by the heat generated by the device under test, namely the back surface 28B of the chuck top adsorption plate 28 (i.e., the location in the heat flow sensor 54 where multiple reference contacts 62 are arranged). Therefore, it is used as the reference temperature for determining the temperature T of the heat-generating part temperature measuring point based on the temperature difference ΔTd between the upper and lower temperature points of the heat-generating part temperature measuring point, as described later. It should be noted that the so-called "heat-generating part temperature measuring point" refers to the temperature measuring point 60 at the position corresponding to the heat-generating part of the wafer W among the multiple temperature measuring points 60 constituting the heat flow sensor 54.

[0075] The temperature difference detection unit 104 is connected to the heat flow sensor 54 and obtains the sensor signal output by the heat flow sensor 54. The temperature difference detection unit 104 extracts the electromotive force (thermoelectric potential) from the sensor signal output by the heat flow sensor 54, and calculates the temperature difference ΔTd between the upper and lower temperature points of the heating element based on the electromotive force.

[0076] The temperature control unit 106 obtains a reference temperature Tref from the reference temperature detection unit 102 and a temperature difference ΔTd between the upper and lower temperature points of the heating element and the temperature measuring point of the heating element from the temperature difference detection unit 104. Then, the temperature control unit 106 calculates the temperature T of the heating element measuring point based on the reference temperature Tref and the temperature difference ΔTd. Furthermore, the temperature control unit 106 uses the calculated temperature T of the heating element measuring point as a control temperature (PV value) and controls the heating and cooling unit 40 in a manner that makes this control temperature a preset target temperature (e.g., a check temperature). The temperature control unit 106 is an example of the temperature control unit of the present invention.

[0077] <On the principles of temperature control>

[0078] Next, the principle of temperature control in this embodiment will be explained in detail.

[0079] In the heat flow sensor 54 of this embodiment, when heat flow occurs in the thickness direction (Z direction) of the wafer chuck 18 relative to the heat flow sensor 54 due to the heating of the device under test in the wafer W, a temperature difference is generated between the front and back sides of the heat flow sensor 54. That is, when heat flow occurs in the thickness direction of the wafer chuck 18 relative to the heat flow sensor 54, a temperature difference is generated between one side (chuck top surface 28A side) and the other side (chuck top back surface 28B side) of the wafer chuck 18. As a result, an electromotive force is generated between one side and the other side of the wafer chuck 18 due to the Seebeck effect. Furthermore, in the heat flow sensor 54, the electromotive force (thermoelectric potential) generated based on the heat flow flowing in the front and back parts of the heat flow sensor 54 is output as a sensor signal.

[0080] In this embodiment, the heat flow sensor 54 adopts the structure described above, so the temperature difference between the front and back sides of the heat flow sensor 54 can be calculated based on the sensor signal output by the heat flow sensor 54, i.e., the electromotive force of the heat flow sensor 54.

[0081] It should be noted that when the electromotive force (EMF) of the heat flux sensor 54 is set to V, and the heat flux passing through the heat flux sensor 54 is set to q, the relationship q = α·V (where α is a sensor constant) exists. Furthermore, when the temperature difference between the surface and back sides of the heat flux sensor 54 is set to ΔT, the heat flux q passing through the heat flux sensor 54 is proportional to the temperature difference ΔT. Therefore, a correlation exists between the EMF V of the heat flux sensor 54 and the temperature difference ΔT. Thus, by experimentally or intentionally obtaining data representing this relationship (EMF-temperature difference conversion data), the temperature difference ΔT can be calculated from the EMF of the heat flux sensor 54.

[0082] Here, the temperature difference calculated from the electromotive force of the heat flow sensor 54 is denoted as ΔT [°C], the heat passing through the heat flow sensor 54 is denoted as Q [W], and the area of ​​the heat flow sensor 54 is denoted as S [m²]. 2 When the heat flow distance (the distance between the front and back sides of the heat flow sensor 54) of the heat flow sensor 54 is set to Lj [m] and the thermal conductivity of the material in which the heat flow sensor 54 is embedded is set to k [W / mK], the heat Q passing through the heat flow sensor 54 is calculated according to the following formula (1).

[0083]

Mathematical Formula 1

[0084]

[0085] Furthermore, the heat output of the heating element is set as Qd [W], and the area of ​​the heating element is set as Sd [m]. 2 In the case of ], the heat Qd of the heating element is as shown in the following formula (2).

[0086]

Mathematical Formula 2

[0087]

[0088] That is, the heat Qd of the heating element is the value obtained by multiplying the heat Q passing through the heat flow sensor 54 by the area ratio (Sd / S) of the area Sd of the heating element relative to the area S of the heat flow sensor 54. Furthermore, if the heat Q passing through the heat flow sensor 54 is replaced using the relationship described in equation (1), the heat Qd of the heating element can be represented by the temperature difference ΔT obtained from the electromotive force of the heat flow sensor 54.

[0089] Furthermore, when the temperature difference between the upper and lower parts of the heating element is set as ΔTd [°C], the temperature difference between the upper and lower parts of the heating element is as shown in the following formula (3).

[0090]

Mathematical Expression 3

[0091]

[0092] That is, the temperature difference ΔTd between the upper and lower points of the heating element is proportional to the heat Qd and the heat flow distance Lj of the heating element, and inversely proportional to the area Sd of the heating element. Furthermore, if the heat Qd of the heating element is replaced using the relationship shown in equation (2), the temperature difference ΔTd between the upper and lower points of the heating element is the value obtained by multiplying the temperature difference ΔT obtained from the electromotive force of the heat flow sensor 54 by the inverse ratio of the above area ratio (that is, the area ratio of the area S of the heat flow sensor 54 to the area Sd of the heating element).

[0093] In this way, the temperature difference ΔTd between the upper and lower parts of the heating element temperature measuring point becomes the temperature difference obtained by converting the temperature difference ΔT obtained from the electromotive force of the heat flow sensor 54 to the area Sd of the heating element. Therefore, when the temperature of the heating element temperature measuring point is set to T [°C], as shown in the following formula (4), the temperature T of the heating element temperature measuring point is the value obtained by adding the temperature difference ΔTd between the upper and lower parts of the heating element temperature measuring point to the reference temperature Tref (the lowest temperature among the temperatures detected by the multiple temperature sensors 52).

[0094]

Mathematical Expression 4

[0095]

[0096] It should be noted that the reference temperature Tref is the reference temperature at the part (i.e., the back side (chuck top back side 28B) of the heat flow sensor 54) that serves as the reference for the temperature difference ΔTd between the upper and lower parts of the heating element's temperature measurement point. Since the temperature sensor 52, located at the position furthest from the device under test that is locally heated in the wafer W, detects the lowest temperature, the temperature detected by this temperature sensor 52 can be considered to be substantially equal to the temperature at the back side (chuck top back side 28B) of the heat flow sensor 54. Therefore, as shown in equation (4) above, the temperature T of the heating element's temperature measurement point can be obtained by adding the temperature difference ΔTd between the upper and lower parts of the heating element's temperature measurement point to the reference temperature Tref detected by the reference temperature detection unit 102.

[0097] <Concept of Calculation Examples Regarding the Temperature of Heating Components>

[0098] Figure 5 This is a conceptual diagram of a calculation example based on the area of ​​the heat-generating part obtained from the heat flow sensor 54. It should be noted that the calculation example described below is based on the conditions shown below.

[0099] • Heat flow distance of heat flow sensor 54: Lj = 0.01 [m]

[0100] Thermal conductivity of the material in which the heat flow sensor 54 is embedded: k = 180 [W / mK]

[0101] [The heating element is a single part]

[0102] Figure 5 Figure 5A shows an example of the temperature difference ΔT calculated from the electromotive force of the heat flow sensor 54 when the heat-generating part HP in the wafer W is a single location. It should be noted that the heat of the heat-generating part HP is set to Qd = 100 [W], and the area of ​​the heat-generating part is set to Sd = 0.000625 [m²]. 2 (25mm×25mm).

[0103] exist Figure 5In the example shown in 5A, the electromotive force of the heat flow sensor 54 is 0.353 [mV], and the temperature difference calculated from this electromotive force is ΔT = 8.89 [℃].

[0104] On the other hand, if the actual temperature difference ΔTd between the upper and lower parts is calculated based on the heat Qd of the heating part HP using the leftmost relation in equation (3), it is as shown in equation (5) below. It should be noted that the sign of the temperature difference ΔTd between the upper and lower parts at the temperature measuring point of the heating part in this case depends on the direction of the heat flow through the heat flow sensor 54.

[0105]

Mathematical Expression 5

[0106]

[0107] exist Figure 5 In the example shown in 5A, the temperature difference ΔT obtained from the electromotive force of the heat flow sensor 54 is equal to the absolute value of the temperature difference ΔTd between the upper and lower parts obtained from the heat Qd of the heat-generating part HP (i.e., ΔT = |ΔTd|).

[0108] [The heating element is located in two parts]

[0109] Figure 5 Figure 5B shows the case where the heat-generating portion HP in the wafer W is divided into two parts (relative to the case of the heat-generating portion HP). Figure 5 This is an example of the temperature difference ΔT calculated from the electromotive force of the heat flow sensor 54 when the heating area of ​​the heating part HP is twice that of the 5A heating element. It should be noted that the heat of the heating part HP is set as Qd = 200 [W], and the area of ​​the heating part is set as Sd = 0.00125 [m²]. 2 (25mm×50mm).

[0110] exist Figure 5 In the example shown in 5B, the electromotive force of the heat flow sensor 54 is 0.706 [mV], and the temperature difference calculated from this electromotive force V is ΔT = 17.78 [℃].

[0111] On the other hand, if the leftmost relation in equation (3) is used to calculate the temperature difference ΔTd between the upper and lower points of the heating element's measuring point based on the heat Qd of the heating element HP, then the result is as shown in equation (6) below. It should be noted that the sign of the temperature difference ΔTd between the upper and lower points of the heating element's measuring point in this case depends on the direction of the heat flow through the heat flow sensor 54.

[0112]

Mathematical Expression 6

[0113]

[0114] exist Figure 5In the example shown in 5B, the heating area of ​​the heat-generating part HP in the wafer W is... Figure 5 Compared to the example shown in 5A, the value is doubled, therefore the electromotive force of the heat flow sensor 54 also increases by a factor of two, proportional to the heating area of ​​the heating part HP. Therefore, in the comparison of the absolute value of the temperature difference, the temperature difference ΔT calculated from the electromotive force of the heat flow sensor 54 is twice the temperature difference ΔTd between the upper and lower temperature points of the heating part calculated from the heat Qd of the heating part HP.

[0115] In this way, the electromotive force of the heat flow sensor 54 changes according to the change in the area of ​​the heating portion HP in the chip W, and the temperature difference ΔT calculated from the electromotive force also changes according to this change. That is, the temperature difference ΔT calculated from the electromotive force of the heat flow sensor 54 is an apparent temperature difference that changes according to the change in the area of ​​the heating portion HP, which deviates from the actual temperature difference. Therefore, in this embodiment, by setting the temperature difference ΔTd between the upper and lower temperature points of the heating portion as a value obtained by converting the temperature difference ΔT calculated from the electromotive force of the heat flow sensor 54 to the area Sd of the heating portion, a temperature difference that is approximately equal to the actual temperature difference at the heating portion temperature point is obtained.

[0116] <Methods for determining actual control temperature>

[0117] Next, the method for obtaining the actual control temperature (temperature difference ΔTd between the upper and lower parts of the heating measurement point) in the temperature control device 100 of this embodiment will be explained.

[0118] The principle of temperature control in this embodiment is as described above, but the actual output value (electromotive force) of the heat flow sensor 54 is determined by the number of thermocouples 56 constituting the heat flow sensor 54 and their installation density (i.e., the area of ​​each pair of thermocouples 56). Therefore, in this embodiment, in the above equations (1) to (3), the area S of the heat flow sensor 54 embedded is calculated as the area Ss of each pair of thermocouples 56, thereby obtaining the temperature difference ΔTd between the upper and lower temperature points of the heating element. It should be noted that the calculation example of the temperature difference ΔTd between the upper and lower temperature points of the heating element described below is based on the following conditions.

[0119] • Area where the heat flow sensor is embedded (φ300mm): Sd=0.070875[m] 2 ]

[0120] • Number of temperature measurement points for the heat flux sensor: Ns = 114 [points]

[0121] • The area of ​​each thermocouple pair: Ss = SD ÷ Ns = 0.070875 ÷ 114 = 0.000622 [m²] 2 ]=S

[0122] [When the fever is located in only one area]

[0123] exist Figure 5 In the example shown in 5A, the area of ​​the heating element is set to Sd = 0.000625 [m]. 2 In the case of (25mm×25mm), the electromotive force of the heat flow sensor 54 is 0.353 [mV], and the temperature difference calculated from this electromotive force is ΔT=8.89 [℃]. Furthermore, the temperature difference ΔTd between the upper and lower temperature measurement points of the heating part is calculated by converting the temperature difference ΔT obtained from the electromotive force of the heat flow sensor 54 to the area Sd of the heating part, as shown in the following formula (7).

[0124]

Mathematical Expression 7

[0125]

[0126] [Cases where there are two sites of fever]

[0127] exist Figure 5 In the example shown in 5B, the area of ​​the heating element is set to Sd = 0.00125 [m²]. 2 In the case of (25mm×50mm), the electromotive force of the heat flow sensor 54 is 0.706 [mV], and the temperature difference calculated from this electromotive force is ΔT=17.78 [℃]. Furthermore, the temperature difference ΔTd between the upper and lower temperature points of the heating element is calculated by converting the temperature difference ΔT obtained from the electromotive force of the heat flow sensor 54 to the area Sd of the heating element, as shown in the following equation (8).

[0128]

Mathematical Expression 8

[0129]

[0130] In this way, in the temperature control device 100 of this embodiment, even if the area of ​​the heating part HP changes, the upper and lower temperature difference ΔTd (actual temperature difference) of the heating part temperature measuring point can be calculated based on the temperature difference ΔT (apparent temperature difference) obtained from the electromotive force of the heat flow sensor 54. Furthermore, by adding the upper and lower temperature difference ΔTd of the heating part temperature measuring point to the reference temperature Tref (which is substantially equivalent to the temperature on the back side of the heat flow sensor 54) detected by the reference temperature detection unit 102, the temperature T of the heating part temperature measuring point is obtained, and this temperature T is used as the control temperature (PV value) to control the heating and cooling unit 40. The temperature of the wafer chuck 18 can be appropriately controlled according to the heating state of the device under test in the wafer W.

[0131] <Temperature Control Methods>

[0132] Next, the temperature control method in the temperature control system 50 of the first embodiment will be described. Figure 6 This is a flowchart illustrating an example of a temperature control method in the temperature control system 50 of the first embodiment.

[0133] First, after holding the wafer W in the wafer chuck 18 and aligning the wafer W with the probe card 24, an electrical characteristic check of the wafer W begins. Furthermore, during the period from the start to the end of the electrical characteristic check of the wafer W, the following steps are performed: Figure 6 The flowchart shown.

[0134] When it begins Figure 6 In the flowchart shown, the first step is to determine the set temperature (step S10). In this step, the temperature control unit 106 determines the set temperature of the wafer chuck 18. The set temperature of the wafer chuck 18 is the target temperature (e.g., the check temperature) when the temperature control unit 106 performs temperature control on the wafer chuck 18. It should be noted that the set temperature of the wafer chuck 18 does not necessarily have to be the check temperature; for example, it can be a temperature set based on the check temperature.

[0135] After the set temperature determination step, the reference temperature detection step (step S12) and the upper and lower temperature difference detection step (step S14) are performed in parallel. The reference temperature detection step and the upper and lower temperature difference detection step do not necessarily need to be executed at the same time, but in the subsequent control temperature determination step (step S16), the control temperature is determined based on the detection results of both steps. Therefore, it is preferable that the reference temperature detection step and the upper and lower temperature difference detection step are executed at the same time.

[0136] In the reference temperature detection step (step S12), the temperatures detected by the multiple temperature sensors 52 are respectively input to the reference temperature detection unit 102. The reference temperature detection unit 102 detects (selects) the lowest temperature from the temperatures detected by each temperature sensor 52 as the reference temperature Tref of the wafer chuck 18. The reference temperature Tref of the wafer chuck 18 is the temperature at which the temperature T of the heating element measuring point is calculated based on the temperature difference ΔTd between the upper and lower temperature points of the heating element measuring point (described later), and is considered to be substantially equal to the temperature at the back side of the heat flow sensor 54 (the back side 28B of the chuck top adsorption plate 28). The reference temperature Tref detected in the reference temperature detection step is input to the temperature control unit 106.

[0137] In the temperature difference detection step (step S14), the heat flow generated by the localized heating of the wafer W held in the wafer chuck 18 is detected by the heat flow sensor 54. The sensor signal (electromotive force) output from the heat flow sensor 54 is input to the temperature difference detection unit 104. The temperature difference detection unit 104 calculates the temperature difference ΔT between the front and back sides of the heat flow sensor 54 based on the electromotive force of the heat flow sensor 54. Furthermore, the temperature difference detection unit 104 calculates the value obtained by converting the temperature difference ΔT calculated based on the electromotive force of the heat flow sensor 54 to the area Sd of the heating part as the temperature difference ΔTd between the heating part and the measuring point. It should be noted that the area Sd of the heating part is obtained by referring to the inspection information (including the area of ​​the device under test) stored in the memory unit (not shown). In addition, the method for calculating the temperature difference ΔTd between the heating part and the measuring point is as described above, so detailed explanation is omitted here.

[0138] After performing the reference temperature detection step and the upper / lower temperature difference detection step, a temperature control step is performed (step S16). In the temperature control step, the temperature control unit 106 calculates the temperature T of the heating element's measuring point based on the reference temperature Tref input from the reference temperature detection unit 102 and the upper / lower temperature difference ΔTd input from the temperature difference detection unit 104. Specifically, the temperature T of the heating element's measuring point is obtained by adding the upper / lower temperature difference ΔTd to the reference temperature Tref (i.e., T = Tref + ΔTd).

[0139] The temperature control unit 106 uses the temperature T of the heating element measuring point, calculated in this way, as the control temperature (PV value) to control the heating and cooling unit 40 so that the temperature T of the heating element measuring point, which serves as the control temperature, is close to the set temperature of the wafer chuck 18 determined in the set temperature determination step. For example, if the temperature T of the heating element measuring point is lower than the set temperature, the temperature control unit 106 supplies heater power from the heater power supply 94 to the heater 44, and the heater 44 heats the wafer chuck 18. Conversely, if the temperature T of the heating element measuring point is higher than the set temperature, the temperature control unit 106 supplies coolant from the cooling device 92 to the cooling plate 42, and the cooling plate 42 cools the wafer chuck 18. Thus, the temperature of the wafer chuck 18 (the temperature T of the heating element measuring point) is controlled to be close to the set temperature based on the heating state of the device under test, the wafer W.

[0140] After performing the temperature control steps as described above, a determination step (step S18) is performed. In the determination step, the temperature control unit 106 determines whether the electrical characteristic check of the wafer W has ended. In the determination step, if the temperature control unit 106 determines that the electrical characteristic check of the wafer W has not ended (if the determination is not made), the processing of steps S12 to S18 is repeated. On the other hand, if the temperature control unit 106 determines that the electrical characteristic check of the wafer W has ended (if the determination is made), the control based on the temperature control unit 106 ends. This flowchart concludes here.

[0141] In this embodiment, the temperature control system 50 assembles both a plurality of temperature sensors 52 and a heat flow sensor 54, which consists of a plurality of thermocouples 56 connected in series (with a plurality of temperature measuring points 60 closely arranged throughout the entire wafer chuck 18), inside the wafer chuck 18. Based on the detection results of the plurality of temperature sensors 52 and the heat flow sensor 54, the system calculates the temperature T (the temperature of the wafer chuck 18 corresponding to the heat-generating portion of the wafer W) at the heat-generating measuring point, and controls the temperature of the wafer chuck 18 (heating and cooling control) by setting this temperature T to a preset set temperature. Thus, the temperature of the wafer chuck 18 can be appropriately controlled without increasing the number of temperature sensors 52 installed on the wafer chuck 18.

[0142] It should be noted that, in this embodiment, as a preferred embodiment, five temperature sensors 52 are shown arranged on the wafer chuck 18 (chuck top suction plate 28). The number of temperature sensors 52 arranged on the wafer chuck 18 is not particularly limited, as long as it is sufficiently small compared to the number of devices under test in the wafer W and is sufficient to detect the reference temperature Tref of the wafer chuck 18. Arranging 2 to 4 temperature sensors 52, or even 6 or more temperature sensors 52, is also possible. Alternatively, if the reference temperature Tref of the wafer chuck 18 can be detected, only one temperature sensor 52 may be used. That is, at least one temperature sensor 52 can be arranged on the wafer chuck 18 to detect the reference temperature Tref of the wafer chuck 18.

[0143] In addition, in this embodiment, as a preferred embodiment, the heat flow sensor 54 is shown to be composed of a single sensor body (an integral piece formed by connecting multiple thermocouples 56 in series), but it is not limited to this and the heat flow sensor 54 may also be composed of multiple sensor bodies.

[0144] Figure 7 This is a diagram showing a structural example of the heat flow sensor 54 consisting of two sensor bodies, and a schematic top view showing the internal structure of the wafer chuck 18. It should be noted that... Figure 7 As an example, the structure of the heat flow sensor 54 is shown in the case where it consists of two sensor bodies, but it is self-evident that it can also consist of more than three sensor bodies.

[0145] exist Figure 7 In the structural example shown, the heat flow sensor 54 consists of two sensor bodies 54A and 54B. Specifically, in a top view of the wafer chuck 18 (viewed along the Z direction), on one side of the wafer chuck 18 ( Figure 7 The sensor body 54A is configured in the area on the left side of the chip chuck 18, and on the other side of the chip chuck 18 ( Figure 7 The sensor body 54B is configured in the area on the right side.

[0146] The two sensor bodies 54A and 54B have a structure that is basically the same as that of the heat flow sensor 54 in this embodiment described above. They are formed by connecting multiple thermocouples 56 in series, and the multiple temperature measuring points 60 are closely arranged within the overall range of their respective configuration areas.

[0147] In addition, output wiring portions 80A and 80B are provided at both ends of the two sensor bodies 54A and 54B for outputting their respective sensor signals to the temperature control device 100. Each output wiring portion 80A and 80B is connected to the temperature control device 100, so that the sensor signals output from each sensor body 54A and 54B are input into the temperature control device 100.

[0148] The temperature control device 100 calculates the temperature difference ΔTd between the upper and lower temperature points of the heating element based on the sensor signals (electromotive force) output from the sensor bodies 54A and 54B located in the area where the device under test is located. It should be noted that the method for calculating the temperature difference ΔTd between the upper and lower temperature points of the heating element is basically the same as in this embodiment, so detailed description is omitted.

[0149] In addition, in this embodiment, the heating and cooling unit 40 is shown with a structure in which a cooling plate 42 is disposed inside the chuck top adsorption plate 28 and a heater 44 is disposed on the lower side of the chuck top adsorption plate 28 (opposite to the side where the wafer W is disposed), but it is not limited to this, and other structural examples described later can also be used.

[0150] Figure 8 This is a schematic structural diagram of the temperature control system 50A involved in the first modified example. It should be noted that the same reference numerals are used for parts that are common to the first embodiment described above, and their descriptions are omitted.

[0151] like Figure 8As shown, the temperature control system 50A according to the first modification includes a cooling plate 42 and a Peltier element 46. The cooling plate 42 and the Peltier element 46 are components of the heating and cooling section 40 and are disposed inside the wafer chuck 18. Specifically, the Peltier element 46 is disposed in contact with the back side (chuck top back side 28B) of the chuck top suction plate 28. The cooling plate 42 is disposed on the opposite side of the chuck top suction plate 28, with the Peltier element 46 passing through it. In other words, the Peltier element 46 is disposed between the chuck top suction plate 28 and the cooling plate 42.

[0152] A Peltier power supply 96 is connected to the Peltier element 46, and Peltier power is supplied to the Peltier element 46 from the Peltier power supply 96 under the control of the temperature control device 100. In addition, a cooling device 92 is connected to the cooling plate 42, and coolant is supplied to the cooling plate 42 from the cooling device 92 under the control of the temperature control device 100.

[0153] According to the first variation, by combining heating using the Peltier element 46 and cooling using the cooling plate 42, temperature control of the wafer chuck 18 can be performed in the same manner as in the first embodiment. It should be noted that cooling using the Peltier element 46 can also be further combined in the above structure for control.

[0154] Figure 9 This is a schematic structural diagram of the temperature control system 50B involved in the second modification. It should be noted that the same reference numerals are used for parts common to the first embodiment described above, and their descriptions are omitted.

[0155] like Figure 9 As shown, the temperature control system 50B of the second variation is similar to the first embodiment in that it includes a cooling plate 42 and a heater 44 inside the wafer chuck 18, but the arrangement of the cooling plate 42 and the heater 44 differs from that of the first embodiment. Specifically, the heater 44 is arranged in contact with the back side (back side 28B of the chuck top suction plate 28). The cooling plate 42 is arranged on the opposite side of the chuck top suction plate 28, with the heater 44 in between.

[0156] In the second variation, by combining heating using heater 44 and cooling using cooling plate 42, temperature control of the wafer chuck 18 can be performed in the same manner as in the first embodiment.

[0157] (Second Implementation)

[0158] Next, the temperature control system 50 of the second embodiment will be described. In the first embodiment described above, the temperature T (the temperature of the wafer chuck 18 corresponding to the heating portion of the wafer W) at the heating element temperature measurement point is calculated based on the detection results of the multiple temperature sensors 52 and the heat flow sensor 54, and the temperature of the wafer chuck 18 is controlled based on the calculated temperature T at the heating element temperature measurement point. In contrast, in the second embodiment, the device temperature corresponding to the temperature of the heating portion of the wafer W is calculated based on the detection results of the multiple temperature sensors 52, the detection results of the heat flow sensor 54, and information such as the physical property values ​​and / or dimensions from the heating element temperature measurement point to the heating portion, and the temperature of the wafer chuck 18 is controlled based on the calculated device temperature.

[0159] It should be noted that, for the second embodiment, except that the control temperature for temperature control of the wafer chuck 18 is the device temperature, the structure is basically the same as that of the first embodiment described above. Hereinafter, the same reference numerals will be used for the parts common to the first embodiment described above, and their descriptions will be omitted.

[0160] Figure 10 This is a block diagram of the temperature control device 100A according to the second embodiment. Figure 10 As shown, the temperature control device 100A of the second embodiment includes a temperature control unit 106A that has a device temperature calculation function.

[0161] Similar to the first embodiment described above, the reference temperature Tref detected by the reference temperature detection unit 102 and the temperature difference ΔTd between the upper and lower parts of the heating element temperature measurement point detected by the temperature difference detection unit 104 are respectively input to the temperature control unit 106A. In addition, information such as physical property values ​​and dimensions of the heating element temperature measurement point to the heating part (i.e., the wafer chuck 18 and the wafer W) are pre-registered in the memory unit (not shown) as device temperature calculation condition data for calculating the device temperature, and the temperature control unit 106A can obtain the device temperature calculation condition data from the memory unit.

[0162] The temperature control unit 106A calculates the temperature of the heat-generating portion of the wafer W (device temperature) based on the reference temperature Tref obtained from the reference temperature detection unit 102, the temperature difference ΔTd between the upper and lower parts of the heat-generating part and the temperature of the measuring point obtained from the temperature difference detection unit 104, and the device temperature obtained from the memory unit. Then, the temperature control unit 106A uses this device temperature as the control temperature to perform temperature control (heating and cooling control) on the wafer chuck 18 in a manner that brings the device temperature close to a preset set temperature (e.g., a check temperature).

[0163] Here, the method for calculating the device temperature in the second embodiment will be described. Figure 11This is an explanatory diagram illustrating the method for calculating device temperature. It should be noted that the thermal conductivity Kw of the wafer W, the thermal conductivity Kj of the material in which the heat flow sensor 54 is embedded, the distance Lc between the temperature measuring point 60 of the heat flow sensor 54 and the holding surface 18A of the wafer chuck 18, and the distance Lw between the back surface of the wafer W and the heat-generating portion HP are pre-registered in the memory section as data for calculating the device temperature.

[0164] like Figure 11 As shown, when the temperature difference between the temperature measuring point 60 of the heat flow sensor 54 and the holding surface 18A of the wafer chuck 18 is set as ΔTc, the temperature difference between the back side of the wafer W and the heat-generating part HP is set as ΔTw, and the temperature of the heat-generating part HP of the wafer W (device temperature) is set as Tw, the device temperature Tw can be calculated as shown in the following formula (9).

[0165]

Mathematical Expression 9

[0166]

[0167] It should be noted that the reference temperature Tref and the temperature difference ΔTd between the upper and lower points of the heating element are detected in the reference temperature detection unit 102 and the temperature difference detection unit 104 in the same way as in the first embodiment.

[0168] With the heat of the heating part HP set as Qd [W], the temperature difference ΔTc between the temperature measuring point 60 of the heat flow sensor 54 and the holding surface 18A of the wafer chuck 18, and the temperature difference ΔTw between the back side of the wafer W and the heating part HP are respectively calculated by the following equations (10) and (11). It should be noted that Sd is the area of ​​the heating part HP of the wafer W (heating area).

[0169]

Mathematical Formula 10

[0170]

[0171]

Mathematical Expression 11

[0172]

[0173] The heat Qd of the heating part HP can be obtained using the leftmost relationship in the above equation (3). That is, the heat Qd of the heating part HP can be obtained using the temperature difference ΔTd between the upper and lower temperature points of the heating part (i.e., the value obtained by converting the temperature difference ΔT obtained from the electromotive force of the heat flow sensor 54 to the area Sd of the heating part) as shown in the following equation (12). It should be noted that Lj is the heat flow distance of the heat flow sensor 54 (the distance between the front and back sides of the heat flow sensor 54).

[0174]

Mathematical Expression 12

[0175]

[0176] Therefore, the device temperature Tw can be calculated using equations (9) to (12).

[0177] (Example of device temperature calculation)

[0178] Next, an example of calculating the device temperature Tw will be explained. It should be noted that the example of calculating the device temperature Tw explained here is based on the following conditions.

[0179] • Reference temperature of wafer chuck 18: Tref = 100 °C

[0180] • Heat flow distance of heat flow sensor 54: Lj = 0.01 [m]

[0181] • The distance between the temperature measuring point 60 of the heat flow sensor 54 and the holding surface 18A of the chip chuck 18: Lc = 0.005 [m]

[0182] • Distance between the back surface of chip W and the heat-generating part HP: Lw = 0.0005 [m]

[0183] The thermal conductivity of the material in which the heat flow sensor 54 is embedded is Kj = 180 [W / mK].

[0184] Thermal conductivity of the material in wafer W: Kw = 160 [W / mK]

[0185] • Heating element area: Sd = 0.000625 [m²] 2 ]

[0186] The temperature difference calculated from the electromotive force V of the heat flow sensor 54 is: ΔT = 8.89 °C.

[0187] • Number of temperature measurement points for the heat flux sensor: Ns = 114 [points]

[0188] • The area of ​​each thermocouple pair: Ss = SD ÷ Ns = 0.070875 ÷ 114 = 0.000622 [m²] 2 ]=S

[0189] It should be noted that the heating element area Sd, the temperature difference ΔT calculated from the electromotive force V of the heat flow sensor 54, the number of temperature measurement points Ns of the heat flow sensor 54, and the area Ss of each thermocouple pair are the same as those in the calculation example shown in the first embodiment.

[0190] The temperature differences used to calculate the device temperature Tw are calculated as follows. First, similar to the calculation example of the first embodiment, the temperature difference ΔTd between the upper and lower temperature points of the heating element is 8.847 °C, as shown in the following formula (13).

[0191]

Mathematical Expression 13

[0192]

[0193] In addition, the temperature difference ΔTc between the temperature measuring point 60 of the heat flow sensor 54 and the holding surface 18A of the chip chuck 18 is 4.42 [°C], as shown in the following formula (14).

[0194]

Mathematical Expression 14

[0195]

[0196] In addition, the temperature difference ΔTw between the back side of the wafer W and the heat-generating part HP is 0.50 [℃], as shown in the following formula (15).

[0197]

Mathematical Expression 15

[0198]

[0199] Therefore, the device temperature Tw is 113.77 °C, as shown in Equation (16) below.

[0200]

Mathematical Expression 16

[0201]

[0202] In the second embodiment, the temperature control unit 106A calculates the device temperature Tw according to the device temperature calculation method described above. Then, the temperature control unit 106A uses the calculated device temperature as the control temperature to perform temperature control on the wafer chuck 18 in a manner that brings the device temperature close to a preset set temperature (e.g., a check temperature).

[0203] Therefore, according to the temperature control system 50 of the second embodiment, based on the detection results of multiple temperature sensors 52, the detection results of heat flow sensor 54, and device temperature calculation condition data (information on the physical property values, dimensions, etc. of the heating part from the temperature measurement point of the heating part), the device temperature of the heating part of the wafer W is calculated, and the temperature of the wafer chuck 18 is controlled based on the calculated device temperature. Therefore, the electrical characteristics of the device under test can be checked with higher accuracy at the desired inspection temperature.

[0204] The temperature control system and temperature control method involved in the present invention have been described in detail above. However, the present invention can of course be modified or modified in various ways without departing from the spirit of the present invention.

[0205] Explanation of reference numerals in the attached figures

[0206] 1…Wafer testing system; 10…Detector; 18…Wafer chuck; 24…Probe card; 25…Probe; 28…Chuck top suction plate; 34…Thermocouple housing; 40…Heating and cooling section; 42…Cooling plate; 44…Heater; 46…Peltier element; 50, 50A, 50B…Temperature control system; 52…Temperature sensor; 54…Heat flow sensor; 56…Thermocouple; 60…Temperature measuring point; 62…Reference contact; 90…Control device; 92…Cooling device; 94…Heater power supply; 96…Peltier power supply; 100…Temperature control device; 100A…Temperature control device; 102…Reference temperature detection section; 104…Temperature difference detection section; 106…Temperature control section; 106A…Temperature control section; HP…Heating part; W…Wafer.

Claims

1. A wafer chuck having a holding surface that holds a wafer, wherein the wafer chuck is provided with: a heating and cooling section that heats or cools the wafer chuck; at least one temperature sensor that is disposed on the wafer chuck; and a heat flow sensor that is disposed on the wafer chuck, connects a plurality of thermocouples in series, and alternately arranges connection portions of the thermocouples that are adjacent to each other at a first depth position from the holding surface and a second depth position that is deeper than the first depth position, in a case where a portion of the wafer chuck that corresponds to a heat generating portion of the wafer is regarded as a corresponding portion, the temperature sensor is configured to detect a reference temperature that is a temperature at the second depth position at the corresponding portion, the heat flow sensor has a plurality of temperature measurement points that are provided corresponding to the respective thermocouples, and the plurality of temperature measurement points are arranged in a range of the entire wafer chuck in a case where the wafer chuck is viewed from above, and the heat flow sensor is configured to detect an up-down temperature difference between the first depth position and the second depth position at the corresponding portion.

2. The wafer chuck according to claim 1, wherein a plurality of the temperature sensors are arranged dispersedly.

3. A temperature control system, wherein the temperature control system is provided with: the wafer chuck according to claim 1; and a temperature control section that calculates a temperature of the corresponding portion or the heat generating portion as a control temperature based on a detection result of the temperature sensor and a detection result of the heat flow sensor.

4. The temperature control system according to claim 3, wherein the temperature control section performs the following processing: detects the reference temperature based on the detection result of the temperature sensor; calculates the up-down temperature difference based on the detection result of the heat flow sensor; and calculates a temperature of the corresponding portion, that is, a heat generating portion temperature measurement point, as the control temperature based on the reference temperature and the up-down temperature difference.

5. The temperature control system according to claim 3, wherein the temperature control section performs the following processing: detects the reference temperature based on the detection result of the temperature sensor; calculates the up-down temperature difference based on the detection result of the heat flow sensor; and calculates a temperature of the heat generating portion, that is, a device temperature, as the control temperature based on the reference temperature, the up-down temperature difference, and data including physical property values and dimensions of the wafer and the wafer chuck.

6. The temperature control system according to claim 4 or 5, wherein a plurality of the temperature sensors are arranged dispersedly on the wafer chuck, the temperature control section detects a lowest temperature, an average value, or a central value from temperatures detected by the plurality of temperature sensors as the reference temperature.

7. The temperature control system according to any one of claims 3 to 5, wherein the temperature control section controls the heating and cooling section so that the control temperature becomes a target temperature that is set in advance.

8. A temperature control method that controls a temperature of the wafer chuck according to claim 1, wherein the temperature control method includes: ​ a reference temperature detecting step of causing at least one of the temperature sensors to detect the reference temperature of the wafer chuck; a heat flow detecting step of causing the heat flow sensor to detect a heat flow generated due to heat generation of a local portion of the wafer held to the holding surface; and a temperature control step of calculating the temperature difference between the upper and lower portions based on the detection result of the heat flow detecting step, and calculating the temperature of the corresponding portion or the heat generating portion as a control temperature based on the reference temperature detected in the reference temperature detecting step and the temperature difference between the upper and lower portions.

9. The temperature control method according to claim 8, wherein the temperature control step includes a process of: calculating the temperature of the corresponding portion, i.e., the temperature of the heat generation portion, as the control temperature based on the reference temperature and the temperature difference between the upper and lower portions.

10. The temperature control method according to claim 8, wherein the temperature control step includes a process of: calculating the temperature of the heat generating portion, i.e., the device temperature, as the control temperature based on the reference temperature, the temperature difference between the upper and lower portions, and data including physical properties and dimensions of the wafer and the wafer chuck.

11. The temperature control method according to any one of claims 8 to 10, wherein the temperature control step includes a process of: heating or cooling the wafer chuck in such a manner that the control temperature becomes a target temperature set in advance.

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