Temperature control method and inspection system

Abstract

Provided are a temperature control method and an inspection system for controlling the junction temperature of an electronic device.　Provided is a temperature control method for an inspection system, the inspection system comprising: a chuck for holding a substrate having an electronic device to be inspected; a chuck temperature detection unit for detecting the temperature of the chuck; a chuck temperature control unit for controlling the temperature of the chuck; a tester for inspecting the electronic device by applying inspection power to the electronic device; and a device temperature detection unit for detecting the temperature of the electronic device. The temperature control method includes: a step for preparing a temperature model having parameters; a step for performing system identification of the parameters of the temperature model using a sequential algorithm; a step for determining a function for transferring the identified parameters from the chuck to the electronic device; a step for estimating a final value of the temperature of the electronic device on the basis of the transfer function; and a step for controlling the temperature of the chuck based on the basis of the final value of the temperature of the electronic device.

Description

Temperature control method and inspection system

[0001] This disclosure relates to a temperature control method and an inspection system.

[0002] Patent Document 1 discloses a control method for an inspection apparatus comprising a chuck on which an object to be inspected is placed, a tester that supplies power to the object to be inspected to inspect the object, and a control unit that controls the temperature of the chuck. The control method includes, in cases where the actual temperature of the object to be inspected cannot be fed back, estimating the temperature difference between the temperature of the chuck and the temperature of the object to be inspected based on the amount of heat generated by the object to be inspected, correcting the target temperature of the chuck based on the target temperature of the object to be inspected and the temperature difference, and controlling the temperature of the chuck based on the corrected target temperature of the chuck and the actual temperature of the chuck.

[0003] Japanese Patent Publication No. 2022-90538

[0004] In one aspect, this disclosure provides a temperature control method and inspection system for controlling the junction temperature of an electronic device.

[0005] To solve the above problems, according to one embodiment, a temperature control method for an inspection system can be provided, comprising: a chuck for holding a substrate having an electronic device to be inspected; a chuck temperature detection unit for detecting the temperature of the chuck; a chuck temperature control unit for controlling the temperature of the chuck; a tester for inspecting the electronic device by applying inspection power to the electronic device; and a device temperature detection unit for detecting the temperature of the electronic device, the method comprising: preparing a temperature model having parameters; performing system identification of the parameters of the temperature model using a sequential algorithm; determining a transfer function from the chuck to the electronic device using the identified parameters; estimating a final value of the temperature of the electronic device based on the transfer function; and controlling the temperature of the chuck based on the final value of the temperature of the electronic device.

[0006] In one aspect, it is possible to provide a temperature control method and inspection system for controlling the junction temperature of an electronic device.

[0007] An example of a perspective view of an inspection system. An example of a configuration diagram of an inspection system. An example of a plan view showing the configuration of a substrate in general. An example of a magnified view of an inspection system showing the area around an electronic device. An example of a diagram showing a temperature model. A diagram showing a model of the stage temperature and the junction temperature of an electronic device. A flowchart explaining an example of a method for controlling the junction temperature of an electronic device. A graph showing an example of a temperature change in the junction temperature. A flowchart explaining an example of a method for controlling the junction temperature of an electronic device. A flowchart explaining an example of a method for controlling the junction temperature of an electronic device. A flowchart explaining an example of a method for controlling the junction temperature of an electronic device.

[0008] Various exemplary embodiments will be described in detail below with reference to the drawings. In each drawing, the same or corresponding parts will be denoted by the same reference numerals.

[0009] An example of an inspection system according to this embodiment, inspection system 1, will be described with reference to Figure 1. Figure 1 is an example of a perspective view of inspection system 1. Figure 2 is an example of a configuration diagram of inspection system 1. In Figure 2, the components built into inspection system 1 are schematically shown as a partially cross-sectional view.

[0010] In the semiconductor manufacturing process, numerous electronic devices D (see Figure 3, described later; also called Dies) with predetermined circuit patterns are formed on a substrate W such as a semiconductor wafer. The formed electronic devices D are inspected for electrical characteristics and other factors, and sorted into good and defective products. The inspection of the electronic devices D is performed, for example, using an inspection system 1 while the substrate W is still in its original state before each electronic device D is separated.

[0011] The inspection system 1 inspects the electrical characteristics of multiple electronic devices D (see Figure 3, described later) formed on the substrate W while controlling the temperature. Specifically, the inspection system 1 supplies inspection power to the electronic devices D when they are above a predetermined inspection temperature, and then inspects their electrical characteristics and other properties.

[0012] The inspection system 1 comprises a storage chamber 2, a loader 3, and a tester 4.

[0013] The housing chamber 2 has a hollow housing 11. Inside the housing chamber 2 is a stage (also called a "chuck") 10 on which the substrate W is placed. The stage 10 has a suction holding part (not shown) that suction-holds the substrate W so that the relative position of the substrate W with respect to the stage 10 does not shift. The housing chamber 2 is also provided with a moving mechanism (not shown) inside the housing 11 that moves the stage 10 in the horizontal and vertical directions. This moving mechanism allows the relative position of the probe card 12 (described later) and the substrate W to be adjusted so that a desired electrode portion E (see Figure 3, described later) on the surface of the substrate W comes into contact with the probe 12a of the probe card 12.

[0014] The housing chamber 2 has a probe card 12 inside the housing 11. The probe card 12 is positioned above the stage 10 and facing the stage 10. The probe card 12 has a plurality of needle-shaped probes 12a that are positioned corresponding to electrode pads or solder bumps provided corresponding to the electrode portions E of each electronic device D on the substrate W. The probe card 12 is connected to the tester 4 via an interface 13. Each probe 12a contacts the electrode portion E of each electronic device D on the substrate W during electrical characteristic testing, supplies power from the tester 4 to the electronic device D via the interface 13, and transmits signals from the electronic device D to the tester 4 via the interface 13.

[0015] Loader 3 has a transport container called FOUP (Front Opening Unify Pod) in which substrates W are placed. Loader 3 also has a transport mechanism (not shown) for transporting substrates W. The transport mechanism takes out the substrates W contained in the FOUP and transports them to the stage 10 in the storage chamber 2. The transport mechanism also receives the substrates W from the stage 10 after the electrical characteristics of the electronic device D have been inspected and places them in the FOUP.

[0016] The tester 4 has a test board (not shown) that reproduces a part of the circuit configuration of the motherboard on which the electronic device D is mounted. The test board of the tester 4 is connected to a tester computer 15 that determines the quality of the electronic device D based on signals from the electronic device D. By changing the test board, the tester 4 can reproduce the circuit configurations of multiple types of motherboards. The probe card 12 has multiple probes 12a, which contact multiple electrode parts E of the electronic device D. The tester 4 also has multiple detection means for detecting the electrical characteristics of the electronic device D. As a result, the tester 4 can detect multiple electrical characteristics of the electronic device D.

[0017] Furthermore, the inspection system 1 includes a user interface unit 16 for displaying information to the user and for the user to input instructions. The user interface unit 16 consists of, for example, an input unit such as a touch panel or keyboard and a display unit such as a liquid crystal display.

[0018] Thus, the inspection system 1 includes a stage 10 as a substrate holding unit for holding the substrate W. The inspection system 1 also includes a probe card 12 having a probe 12a, an interface 13, and a tester 4 as a detection unit for detecting the electrical characteristics of an electronic device D by supplying inspection power to the electrode portion E of the electronic device D provided on the substrate W.

[0019] Furthermore, the loader 3 has a temperature control unit 14. The temperature control unit 14 includes a power supply 25, a chiller 26, a power supply 55, and a control unit 90.

[0020] The stage 10 is provided with a heater 20 (heating section) for heating the stage 10. The power supply 25 supplies power to the heater 20 provided on the stage 10. Inside the stage 10, a refrigerant flow path 10a is formed through which a heat transfer medium (such as antifreeze) flows. The chiller 26 circulates the temperature-controlled heat transfer medium through the refrigerant flow path 10a. Thus, the inspection system 1 comprises the heater 20, power supply 25, refrigerant flow path 10a, and chiller 26 as a holding section temperature adjustment mechanism for adjusting the temperature of the substrate holding section. However, the configuration of the holding section temperature adjustment mechanism is not limited to this. Although the heating section for heating the stage 10 has been described as the heater 20, it is not limited to this. The heating section for heating the stage 10 may be a light source such as an LED that heats the stage 10 by irradiating light onto the stage 10 on which the substrate W is placed.

[0021] Furthermore, the holding section temperature adjustment mechanism includes a temperature detection unit (chuck temperature detection unit) 30 that detects the temperature of the substrate holding section. The temperature detection unit 30 is provided on the stage 10 and detects the temperature of the stage 10 (chuck temperature) Tchuck. The chuck temperature Tchuck of the stage 10 detected by the temperature detection unit 30 is input to the control unit 90. Although the temperature detection unit 30 is described as a single unit in the figures, it is not limited to this, and it is preferable to provide multiple temperature detection units 30 on the stage 10 for electronic devices D that are supplied with power and generate heat. It is also preferable to switch the temperature detection unit 30 that detects the chuck temperature Tchuck when switching the electronic devices D that are supplied with power and generate heat. Furthermore, it is preferable to detect the chuck temperature Tchuck based on a model that includes multiple temperature detection units 30.

[0022] Furthermore, the tester 4 is provided with a temperature control mechanism 50 for adjusting the temperature of the probe card 12. The temperature control mechanism 50 may include a heater (not shown) for heating the probe card 12, a cooling fan (not shown) for air-cooling the probe card 12, etc. The power supply 55 supplies power to the temperature control mechanism 50 provided in the tester 4. Thus, the inspection system 1 includes a temperature control mechanism 50 as a detection unit temperature control mechanism for adjusting the temperature of the detection unit. However, the configuration of the detection unit temperature control mechanism is not limited to this. The detection unit temperature control mechanism may include a configuration that adjusts the temperature of the detection unit by liquid cooling.

[0023] Furthermore, the detection unit temperature adjustment mechanism includes a temperature detection unit 60 that detects the temperature of the detection unit. The temperature detection unit 60 is provided on the probe card 12 and detects the temperature Tprob of the probe card 12. The temperature Tprob of the probe card 12 detected by the temperature detection unit 60 is input to the control unit 90. Although the temperature detection unit 60 has been described as being provided on the probe card 12, it is not limited to this, and may be a temperature detection unit capable of detecting a temperature that can represent the temperature of the probe. For example, the temperature detection unit 60 may be a temperature detection unit that detects the temperature of the probe 12a. Although the temperature detection unit 60 has been described as being a single unit in the figures, it is not limited to this, and it is preferable to provide multiple temperature detection units 60 on the probe card 12 for an electronic device D that is supplied with power and generates heat. Furthermore, when switching the electronic device D that is supplied with power and generates heat, it is preferable to also switch the temperature detection unit 60 that detects the temperature Tprob. Furthermore, it is preferable to detect the temperature Tprob based on a model that includes multiple temperature detection units 60.

[0024] Furthermore, the tester 4 has a power detection unit 41 that detects the test power (current and voltage) supplied from the tester 4 to the electronic device D via the interface 13 and probe card 12. The test power detected by the power detection unit 41 is input to the control unit 90.

[0025] The control unit 90 includes a chuck temperature control unit 91, a detection unit temperature control unit 92, and an analysis unit 93. The control unit 90 controls the holding unit temperature adjustment mechanism so that the junction temperature Tj of the electronic device D (temperature of the substrate W) becomes the inspection temperature (device target temperature Tj_obj). The control unit 90 also controls, for example, the detection unit temperature adjustment mechanism so that the temperature difference between the substrate W and the probe card 12 is within a predetermined threshold.

[0026] The chuck temperature control unit 91 controls the holding unit temperature adjustment mechanism so that the chuck temperature Tchuck of the substrate holding unit detected by the temperature detection unit 30 reaches the target temperature. Although the temperature detection unit 30 is described as a single unit in the illustration, it is not limited to this, and it is preferable to provide multiple temperature detection units 30 on the stage 10 for the electronic device D that is supplied with power and generates heat. Furthermore, when switching the electronic device D that is supplied with power and generates heat, it is preferable to also switch the temperature detection unit 30 that detects the chuck temperature Tchuck. It is also preferable to detect the chuck temperature Tchuck based on a model that includes multiple temperature detection units 30. That is, the chuck temperature control unit 91 controls the amount of heat generated by the heater 20 by controlling the power supply 25, thereby controlling the chuck temperature Tchuck of the stage 10. Alternatively, the chuck temperature control unit 91 may control the temperature of the heat transfer medium supplied by the chiller 26 to the refrigerant flow path 10a by controlling the chiller 26, thereby controlling the chuck temperature Tchuck of the stage 10.

[0027] The detection unit temperature control unit 92 controls the detection unit temperature adjustment mechanism so that the temperature Tprob detected by the temperature detection unit 60 becomes the target temperature. That is, the detection unit temperature control unit 92 controls the temperature adjustment mechanism 50 by controlling the power supply 55 to control the temperature Tprob of the probe card 12. Although the temperature detection unit 60 is described as a single unit in the figures, it is not limited to this, and it is preferable to provide multiple temperature detection units 60 on the probe card 12 for electronic devices D that are supplied with power and generate heat. Furthermore, it is preferable to switch the temperature detection unit 60 that detects the temperature Tprob when switching the electronic devices D that are supplied with power and generate heat. It is also preferable to detect the temperature Tprob based on a model that includes multiple temperature detection units 60.

[0028] The analysis unit 93 estimates the junction temperature Tj (temperature of the substrate W) of the electronic device D based on the temperature model shown in Figure 5, which will be described later. The control unit 90 then adjusts the Chuck Heat Flux (see heat flow Ic, which will be described later using Figure 5) so that the chuck temperature Tchuck reaches the target temperature (target temperature of the holding unit Tchuck_obj). Alternatively, the control unit 90 may be configured to adjust the Chuck Heat Flux (see heat flow Ic, which will be described later using Figure 5) so that the chuck temperature Tchuck reaches the target temperature (target temperature of the holding unit). The chuck temperature control unit 91 controls the holding unit temperature adjustment mechanism based on the target temperature of the holding unit calculated by the analysis unit 93.

[0029] Next, the substrate W to be inspected in the inspection system 1 described above will be explained using Figure 3. Figure 3 is a schematic plan view showing the configuration of the substrate W.

[0030] As shown in Figure 3, multiple electronic devices D are formed on the surface of the substrate W by etching and wiring processes on a roughly disc-shaped silicon substrate, with predetermined spacing between them. Electrode portions E are formed on the surface of each electronic device D, i.e., the substrate W, and these electrode portions E are electrically connected to the circuit elements inside the electronic device D. By applying a voltage to the electrode portions E, current can be supplied to the circuit elements inside each electronic device D.

[0031] FIG. 4 is an example of an enlarged view of the inspection system 1 with the vicinity of the electronic device D enlarged.

[0032] When inspecting the electrical characteristics and the like of the electronic device D, the substrate W is held by the stage 10. That is, the electronic device D is thermally connected to the stage 10. Further, when inspecting the electrical characteristics and the like of the electronic device D, the probe 12a is in contact with the electrode portion E of the electronic device D. That is, the electronic device D is thermally connected to the probe card 12 via the probe 12a. Further, the probe card 12 is in contact with the interface 13, and the interface 13 is in contact with the tester 4. That is, the probe card 12 is thermally connected to the tester 4 via the interface 13, and the tester 4 is thermally connected to the electronic device D via the probe card 12.

[0033] Also, the chuck temperature T chuck of the stage 10 is detected by the temperature detection unit 30. Further, the temperature T prob of the probe card 12 is detected by the temperature detection unit 60.

[0034] Here, the tester 4 can detect the junction temperature T j of the electronic device D from the correlation between the generated electromotive force and the temperature by flowing a current through a PN junction (for example, a transistor or the like) formed in the electronic device D via the probe 12a. That is, the tester 4 also functions as a device temperature detection unit that detects the temperature (junction temperature T j) of the electronic device D. However, when inspecting an electronic device D such as a logic IC, for example, under the condition that a clock is generated, it may not be possible to suitably detect the junction temperature T j due to the influence of noise or the like.

[0035] Furthermore, when inspecting the electronic device D, a temperature difference is generated between the chuck temperature Tchuck of the stage 10 and the junction temperature Tj of the electronic device D due to the thermal resistance between the stage 10 and the substrate W (electronic device D). Therefore, when inspecting the electronic device D by controlling the temperature so that the chuck temperature Tchuck of the stage 10 becomes the inspection temperature, the junction temperature Tj of the electronic device D may become higher than the inspection temperature. In other words, the electronic device D will be inspected at a temperature higher than the inspection temperature, which may reduce the yield of the electronic device D.

[0036] Furthermore, when the temperature of the chuck Tchuck in stage 10 is controlled to become the inspection temperature and the electronic device D is inspected, the heat flow from the electronic device D to the detection unit becomes a disturbance.

[0037] Furthermore, the substrate W is formed mainly of silicon, for example. The probe card 12 is formed mainly of glass epoxy, for example. A temperature difference between the substrate W and the probe card 12 can cause a difference in thermal expansion, which may cause the probe 12a to detach from the electrode portion E.

[0038] Next, we will describe the temperature control of the electronic device D (junction temperature Tj) in the inspection system 1 according to this embodiment. Figure 5 is an example of a diagram showing a temperature model.

[0039] Figure 5 shows the heat flow Id, thermal resistance Rd, heat capacity Cd, and junction temperature Tj of electronic device D. It also shows the heat flow Ic, thermal resistance Rc, heat capacity Cc, chuck temperature Tchuck of stage 10, heat flow Idc from stage 10 to electronic device D, and thermal resistance Rdc from stage 10 to electronic device D. Furthermore, in the temperature model described later, y ｔ This indicates the junction temperature Tj. Also, ut １ This shows the input heat flow from the untested die. Also, ut ２This shows the input heat flow from the chuck (stage 10). In Figure 5, the temperature detection unit 30 (see Figures 2 and 4) for detecting the chuck temperature Tchuck is described as a single unit, but performance can be further improved by arranging and switching between multiple temperature detection units 30, or by detecting the chuck temperature Tchuck based on a model that includes multiple temperature detection units 30.

[0040] Here, the various thermal resistances and heat capacities are predetermined values ​​(obtainable values) based on the configuration of the substrate holder, substrate W, detection unit, etc.

[0041] The heat flow Id of electronic device D corresponds to the heat flow due to the test power detected by the power detection unit 41. The heat flow Ic of stage 10 corresponds to the heat flow in the holding unit temperature control mechanism. In other words, the heat flows Id and Ic are values ​​that the control unit 90 can detect.

[0042] Furthermore, the temperature of the stage 10 (chuck temperature) Tchuck corresponds to the temperature detected by the temperature detection unit 30. In other words, the temperature Tchuck is a value that the control unit 90 can detect.

[0043] On the other hand, the junction temperature Tj of electronic device D is a temperature that the control unit 90 cannot directly measure.

[0044] Next, the models for the chuck temperature Tchuck of stage 10 and the junction temperature Tj of electronic device D will be explained using Figure 6. Figure 6 is a diagram showing the models for the chuck temperature Tchuck of stage 10 and the junction temperature Tj of electronic device D. In Figure 6, the inflow and outflow of heat are shown as the inflow and outflow of fluid.

[0045] Heat tank 601 represents the heat capacity of stage 10. The liquid level in heat tank 601 corresponds to the temperature Tchuck. Heat tank 602 represents the heat capacity of electronic device D. The liquid level in heat tank 602 corresponds to the junction temperature Tj. The heat channel 603 connecting heat tank 601 and heat tank 602 represents the heat transfer between stage 10 and electronic device D. The narrow cross-sectional area of ​​the heat channel 603 corresponds to the thermal resistance Rdc between stage 10 and electronic device D.

[0046] The heat inflow 604 into the heat tank 601 corresponds to the amount of heat generated by the heater 20 (heating unit) that heats the stage 10. The heat inflow 605 into the heat tank 602 corresponds to the amount of heat generated by the test power (test power detected by the power detection unit 41) supplied to the electronic device D. The heat outflow 606 from the heat tank 601 corresponds to the amount of heat radiated from the stage 10 to the atmosphere when the chuck setting temperature is higher than the ambient temperature, and corresponds to heat inflow when it is lower (not shown). The heat outflow 607 from the heat tank 601 corresponds to the amount of heat radiated from the stage 10 to the chiller 26. A high-speed valve 608 that can be opened and closed at high speed is provided between the heat tank 601 and the chiller 609 for the heat outflow 607. The amount of heat radiated from the stage 10 to the chiller 26 is controlled by controlling the high-speed valve 608.

[0047] Here, the inspection system 1 presses the probe 12a against the electrode portion E of the electronic device D to make electrical contact with the tester 4. For this reason, in the inspection system 1 equipped with multiple probes 12a, the stage 10 is thick and heavy in order to withstand the load (for example, 50,000 pins, 10 grams per pin, 500 kg). As a result, the heat capacity (heat tank 601) of the stage 10 is also large. Furthermore, even if a material with high thermal conductivity such as copper is used for the stage 10, the time constant of the stage 10 will be large. The time constant of the stage 10 is on the order of several seconds to tens of seconds, for example, while the time constant of the electronic device D is on the order of tens of milliseconds. Therefore, when heat is transferred from the stage 10 to the electronic device D and the temperature of the electronic device D rises, the decrease in the chuck temperature Tchuck is a temperature change that is negligible for the chuck temperature control unit 91 that controls the chuck temperature Tchuck of the stage 10. Furthermore, the temperature of the electronic device D rises very quickly, while the temperature of the stage 10 cools down slowly.

[0048] Figure 7 is a flowchart illustrating an example of a method for controlling the junction temperature Tj of electronic device D. Here, we will describe a control method where the junction temperature Tj of electronic device D is set to the device target temperature Tj_obj.

[0049] In step S101, a temperature model is prepared. Here, the temperature model is pre-stored in the memory unit (not shown) of the control unit 90. The temperature model has multiple parameters. The temperature model is, for example, the temperature model shown in Figure 5. The temperature model shown in Figure 5 includes parameters such as thermal resistance Rd, heat capacity Cd, thermal resistance Rc, heat capacity Cc, and thermal resistance Rdc.

[0050] In step S102, the chuck temperature Tchuck of the stage 10 is controlled. Here, the chuck temperature control unit 91 controls the holding unit temperature adjustment mechanism to control the temperature so that the chuck temperature Tchuck of the stage 10 becomes a predetermined holding unit target temperature Tchuck_obj. Also, the temperature of the electronic device D placed on the stage 10 (junction temperature Tj) is somewhat lower than the chuck temperature Tchuck before die heating, but becomes significantly different after die heating.

[0051] Before die heating, the temperature of electronic device D (junction temperature Tj) is somewhat lower than the chuck temperature Tchuck. Figure 8 is a graph showing an example of the temperature change of the junction temperature Tj. In Figure 8, the horizontal axis represents time. The left vertical axis represents the junction temperature Tj (shown by the solid line 801) and the chuck temperature Tchuck (shown by the dashed line 802), and the right vertical axis represents the applied power (shown by the double dashed line 803). Stage 10 is controlled by the chuck temperature and is therefore kept almost constant (see dashed line 802), but when power is applied to electronic device D (see double dashed line 803), the temperature of electronic device D (junction temperature Tj) rises (see solid line 801). Then, as time progresses, the temperature of electronic device D (junction temperature Tj) reaches a steady state and the final value (target junction temperature Tjmax). The following processes are performed before the temperature of electronic device D (junction temperature Tj) reaches its final value (Tjmax).

[0052] Returning to Figure 7, in step S103, the chuck temperature Tchuck and the junction temperature Tj are detected. Here, the control unit 90 detects the chuck temperature Tchuck using the temperature detection unit 30. The control unit 90 also detects the junction temperature Tj of the electronic device D from the correlation between the generated electromotive force and temperature by passing current through the PN coupling formed in the electronic device D.

[0053] In step S104, the parameters of the temperature model are identified by a sequential algorithm. Here, the control unit 90 determines the parameters of the temperature model based on the temperature model having multiple parameters, the detected chuck temperature Tchuck, and the detected junction temperature Tj. The control unit 90 then repeats this process sequentially until the estimated junction temperature, inferred from the temperature model using the estimated parameter values, and the detected junction temperature Tj fall within a predetermined range. The numbers on the horizontal axis in Figure 8 indicate the step numbers that are repeated sequentially. This identifies the parameters of the temperature model.

[0054] In step S105, the transfer function between the chuck (stage 10) and the electronic device D is determined from the identified parameters. The control unit 90 determines the transfer function based on the temperature model from step S101 and the parameters from step S104. Here, the temperature model is the heat transfer from the chuck (stage 10) to the electronic device D, and the transfer function is the transfer function from the chuck (stage 10) to the electronic device D.

[0055] In step S106, the final value of the junction temperature Tj of the electronic device D (the target junction temperature Tjmax) is estimated based on the transfer function. Here, the control unit 90 uses the transfer function determined in step S105 to estimate the target junction temperature Tjmax from the final value theorem.

[0056] In step S107, the chuck temperature Tchuck is controlled based on the final value of the estimated junction temperature Tj (the target junction temperature Tjmax). Here, we will explain the case where the junction temperature Tj is controlled to the device target temperature Tj_obj. In this case, the difference between the final value of the junction temperature Tj (the target junction temperature Tjmax) and the device target temperature Tj_obj is taken as the offset temperature, and the holding part target temperature Tchuck_obj is controlled based on the offset temperature (Tjmax - Tj_obj). That is, if the holding part target temperature Tchuck_obj in step S102 is Tchuck_obj102 and the holding part target temperature Tchuck_obj in step S107 is Tchuck_obj107, it can be expressed by the following formula.

[0057] Tchuck_obj107 = Tchuck_obj102-(Tjmax-Tj_obj)

[0058] Therefore, the control unit 90 controls the chuck temperature Tchuck to become the holding unit target temperature Tchuck_obj107. As a result, when the junction temperature Tj reaches its final value, the junction temperature Tj can be set to the device target temperature Tj_obj.

[0059] In other words, the offset temperature (Tjmax - Tj_obj) can be estimated before the junction temperature Tj reaches its final value. This reduces the time it takes for the junction temperature Tj to reach the device target temperature Tj_obj compared to controlling the chuck temperature Tchuck using the offset temperature (Tjmax - Tj_obj) after the junction temperature Tj has reached its final value.

[0060] Furthermore, this control method allows for the control of the junction temperature Tj by controlling the chuck temperature Tchuck without changing the temperature model. Additionally, by offsetting the chuck temperature Tchuck before the junction temperature Tj reaches its final value, the junction temperature Tj can be rapidly controlled to the device target temperature Tj_obj.

[0061] The temperature model prepared in step S101 can be any of the following: a first-order lag model, a second-order lag model, an autoregressive (AR) model, a moving average (MA) model, an autoregressive moving average (ARMA) model, or a transfer function of the form F(s).

[0062] Furthermore, the sequential algorithm used in step S104 can be any of the following: sequential least squares method, Kalman filter, prediction error method, maximum likelihood estimation method, neural network, etc.

[0063] Next, we will explain using the successive least squares method as an example. Figure 9 is a flowchart illustrating an example of a method for controlling the junction temperature Tj of electronic device D.

[0064] Here, the evaluation function used is the following equation (1).

[0065]

[0066] Furthermore, the estimated value is obtained using the following equation (2).

[0067]

[0068] Furthermore, the algorithm uses the following equations (3) and (4). Note that P shown in equation (4) Ｎ This represents the covariance matrix.

[0069]

[0070] Furthermore, the temperature model uses the following equation (5).

[0071]

[0072] Furthermore, the parameter θ is given by equation (4) below. The variable z is given by equation (5) below.

[0073]

[0074] In step S11, initial values ​​are set. Here, counter N = 1. The parameter θ to be estimated is 0 or Tchuck. Covariance matrix P ０ =αI (however, α=10５ Let it be ( ). The forgetting factor ρ (0 < ρ < 1) is set, for example, from 0.95 to 0.999. Let Esp = β corresponding to the difference between the estimated value and the detected value, and Espb = β (β is an arbitrary initial value) be the minimum value of the difference. Let the temporary parameter θ ｔｍｐ = 0.

[0075] In step S12, substitute -y Ｎ taken into Z ｔ , and u ｔ . Here, y ｔ is the detected junction temperature Tj (see S103). u ｔ is the detected chuck temperature Tchuck (see S103).

[0076] In step S13, calculate the parameter θ Ｎ (with a hat symbol on θ) from equation (3). Also, calculate Esp. Note that Esp is a value related to the square of the difference between the estimated value and the detected value.

[0077] In step S14, determine whether Esp is less than or equal to Espb. If Esp is less than or equal to Espb, the processing of the control unit 90 proceeds to step S15. If Esp is not less than or equal to Espb, the processing of the control unit 90 proceeds to step S16.

[0078] In step S15, set the temporary parameter θ ｔｍｐ to the parameter θ Ｎ (with a hat symbol on θ) calculated in step S13. Also, set Espb to the Esp calculated in step S13. Then, the processing of the control unit 90 proceeds to step S16. That is, in the processing of steps S14 and S15, when Esp corresponding to the difference between the estimated value and the detected value becomes smaller than the minimum value Espb of the past difference, update the temporary parameter θ ｔｍｐ and the minimum value Espb of the difference to the values calculated in step S13.

[0079] In step S16, calculate the covariance matrix P Ｎ using equation (4).

[0080] In step S17, it is determined whether Esp is below the acceptable value (threshold). If Esp is not below the acceptable value (S17 NO), the control unit 90 proceeds to step S18. In step S18, Z Ｎ -y ｔ－ｎ u ｔ－ｎ The parameters are shifted one by one. Then, the control unit 90 returns to step S12, and the parameter θ Ｎ Repeat the calculation.

[0081] If Esp is less than or equal to the allowable value (S17, YES), the control unit 90 proceeds to step S19. In step S19, the final value theorem is used to determine the parameter θ ｔｍｐ The arrival junction temperature Tjmax is estimated from this.

[0082] In this way, the parameter θ reduces the difference between the estimated value of the junction temperature Tj by the temperature model and the actual detected value through the processing from step S11 to step S18. ｔｍｐ System identification is performed by determining the parameter θ (see S104). Then, the parameter θ determined by the process in step S19 is used. ｔｍｐ The final value of the junction temperature Tj (the junction temperature Tjmax) is estimated from this (see S105 and S106).

[0083] Furthermore, when performing temperature control of the junction temperature Tj for the same type of electronic device D, the parameter θ in step S11 is used. ｔｍｐ The initial value of the parameter θ was determined in the previous electronic device D. ｔｍｐ This may be used. This will allow the parameter θ to be used. ｔｍｐ This can shorten the processing time until convergence occurs.

[0084] Furthermore, when performing temperature control of the junction temperature Tj for the same type of electronic device D, the parameter θ determined for the previous electronic device D is used. ｔｍｐ It is also acceptable to use this configuration as is.

[0085] Figure 10 is a flowchart illustrating an example of a method for controlling the junction temperature Tj of electronic device D. Here, we will describe a control method where the junction temperature Tj of electronic device D is set to the device target temperature Tj_obj.

[0086] In step S201, a temperature model is prepared, similar to step S101.

[0087] In step S202, the chuck temperature Tchuck of stage 10 is controlled in the same manner as in step S102.

[0088] In step S203, the chuck temperature Tchuck and the junction temperature Tj are detected, similar to step S103.

[0089] In step S204, the parameters of the temperature model are identified by a sequential algorithm. Here, the control unit 90 determines the parameters of the temperature model based on the temperature model having multiple parameters, the detected chuck temperature Tchuck, and the detected junction temperature Tj. This identifies the parameters of the temperature model.

[0090] In step S205, the transfer function between the chuck (stage 10) and the electronic device D is determined from the identified parameters. Here, the control unit 90 determines the transfer function based on the temperature model from step S201 and the parameters from step S204.

[0091] In step S206, the junction temperature Tj of the electronic device D is estimated based on the transfer function. Here, the control unit 90 estimates the junction temperature Tj using the transfer function determined in step S205.

[0092] In step S207, it is determined whether the difference between the estimated value of the estimated junction temperature Tj (see S206) and the detected value of the detected junction temperature Tj (see S203) is less than or equal to a threshold (tolerance value). If the difference is not less than or equal to the threshold (S207 NO), the control unit 90 returns to step S203 and repeats the process from step S203 to step S206. If the difference is less than or equal to the threshold (S207 YES), the control unit 90 proceeds to step S208.

[0093] In step S208, the final value of the junction temperature Tj of the electronic device D (the target junction temperature Tjmax) is estimated based on the transfer function. Here, the control unit 90 uses the transfer function determined in step S205 to estimate the target junction temperature Tjmax from the final value theorem.

[0094] In step S209, the chuck temperature Tchuck is controlled based on the final value of the estimated junction temperature Tj (the target junction temperature Tjmax). Here, we will explain the case where the junction temperature Tj is controlled to the device target temperature Tj_obj. In this case, the difference between the final value of the junction temperature Tj (the target junction temperature Tjmax) and the device target temperature Tj_obj is taken as the offset temperature, and the holding part target temperature Tchuck_obj is controlled based on the offset temperature (Tjmax - Tj_obj). That is, if the holding part target temperature Tchuck_obj in step S202 is Tchuck_obj202 and the holding part target temperature Tchuck_obj in step S207 is Tchuck_obj209, it can be expressed by the following equation.

[0095] Tchuck_obj209 =Tchuck_obj202-(Tjmax-Tj_obj)

[0096] Therefore, the control unit 90 controls the chuck temperature Tchuck to become the holding unit target temperature Tchuck_obj209. As a result, when the junction temperature Tj reaches its final value, the junction temperature Tj can be set to the device target temperature Tj_obj.

[0097] In other words, the offset temperature (Tjmax - Tj_obj) can be estimated before the junction temperature Tj reaches its final value. This reduces the time it takes for the junction temperature Tj to reach the device target temperature Tj_obj compared to controlling the chuck temperature Tchuck using the offset temperature (Tjmax - Tj_obj) after the junction temperature Tj has reached its final value.

[0098] Furthermore, this control method allows for the control of the junction temperature Tj by controlling the chuck temperature Tchuck without changing the temperature model. Additionally, by offsetting the chuck temperature Tchuck before the junction temperature Tj reaches its final value, the junction temperature Tj can be rapidly controlled to the device target temperature Tj_obj.

[0099] Figure 11 is a flowchart illustrating an example of a method for controlling the junction temperature Tj of electronic device D. Here, we will describe a control method where the junction temperature Tj of electronic device D is set to the device target temperature Tj_obj.

[0100] In step S201, a temperature model is prepared, similar to step S201 in Figure 10.

[0101] In step S202, the chuck temperature Tchuck of the stage 10 is controlled in the same manner as in step S202 of Figure 10.

[0102] In step S203, the chuck temperature Tchuck and the junction temperature Tj are detected, similar to step S203 in Figure 10.

[0103] In step S204, similar to step S204 in Figure 10, the parameters of the temperature model are identified by a sequential algorithm. Here, the control unit 90 determines the parameters of the temperature model based on the temperature model having multiple parameters, the detected chuck temperature Tchuck, and the detected junction temperature Tj. This identifies the parameters of the temperature model.

[0104] In step S205, similar to step S205 in Figure 10, the transfer function between the chuck (stage 10) and the electronic device D is determined from the identified parameters. Here, the control unit 90 determines the transfer function based on the temperature model from step S201 and the parameters from step S204.

[0105] In step S206, similar to step S206 in Figure 10, the junction temperature Tj of the electronic device D is estimated based on the transfer function. Here, the control unit 90 estimates the junction temperature Tj using the transfer function determined in step S205.

[0106] In step S207, similar to step S207 in Figure 10, it is determined whether the difference between the estimated value of the estimated junction temperature Tj (see S206) and the detected value of the detected junction temperature Tj (see S203) is less than or equal to a threshold (tolerance value).

[0107] If the difference is not below the threshold (S207, NO), the control unit 90 proceeds to step S210. In step S210, the final value of the junction temperature Tj of the electronic device D (the target junction temperature Tjmax) is estimated based on the transfer function. Here, the control unit 90 uses the transfer function determined in step S205 to estimate the target junction temperature Tjmax from the final value theorem.

[0108] In step S211, the chuck temperature Tchuck is controlled based on the final value of the estimated junction temperature Tj (the target junction temperature Tjmax). Here, we will explain the case where the junction temperature Tj is controlled to the device target temperature Tj_obj. In this case, the difference between the final value of the junction temperature Tj (the target junction temperature Tjmax) and the device target temperature Tj_obj is taken as the offset temperature, and the holding part target temperature Tchuck_obj is controlled based on the offset temperature (Tjmax - Tj_obj). That is, if the holding part target temperature Tchuck_obj in step S202 is Tchuck_obj202 and the holding part target temperature Tchuck_obj in step S207 is Tchuck_obj211, it can be expressed by the following formula.

[0109] Tchuck_obj211 =Tchuck_obj202-(Tjmax-Tj_obj)

[0110] Then, the control unit 90 returns to step S203. As a result, the processing from step S203 onward is performed at the chuck temperature (Tchuck_obj211) corrected in step S211.

[0111] If the difference is less than or equal to the threshold (S207, YES), the control unit 90 proceeds to step S208. In step S208, similar to step S208 in Figure 10, the final value of the junction temperature Tj of the electronic device D (the target junction temperature Tjmax) is estimated based on the transfer function. Here, the control unit 90 uses the transfer function determined in step S205 to estimate the target junction temperature Tjmax from the final value theorem.

[0112] In step S209, similar to step S209 in Figure 10, the chuck temperature Tchuck is controlled based on the final value of the estimated junction temperature Tj (the target junction temperature Tjmax). Here, we will explain the case where the junction temperature Tj is controlled to the device target temperature Tj_obj. In this case, the difference between the final value of the junction temperature Tj (the target junction temperature Tjmax) and the device target temperature Tj_obj is taken as the offset temperature, and the holding part target temperature Tchuck_obj is controlled based on the offset temperature (Tjmax - Tj_obj). That is, if the holding part target temperature in step S202 is Tchuck_obj202 and the holding part target temperature in step S207 is Tchuck_obj207, it can be expressed by the following equation.

[0113] Tchuck_obj207 =Tchuck_obj202-(Tjmax-Tj_obj)

[0114] Therefore, the control unit 90 controls the chuck temperature Tchuck to become the holding unit target temperature Tchuck_obj207. As a result, when the junction temperature Tj reaches its final value, the junction temperature Tj can be set to the device target temperature Tj_obj.

[0115] In other words, the offset temperature (Tjmax - Tj_obj) can be estimated before the junction temperature Tj reaches its final value. This reduces the time it takes for the junction temperature Tj to reach the device target temperature Tj_obj compared to controlling the chuck temperature Tchuck using the offset temperature (Tjmax - Tj_obj) after the junction temperature Tj has reached its final value.

[0116] Furthermore, this control method allows for the control of the junction temperature Tj by controlling the chuck temperature Tchuck without changing the temperature model. Additionally, by offsetting the chuck temperature Tchuck before the junction temperature Tj reaches its final value, the junction temperature Tj can be rapidly controlled to the device target temperature Tj_obj.

[0117] Furthermore, with this control system, the target junction temperature Tjmax is estimated each time the step of calculating the temperature model parameters is performed (S210), and the chuck temperature Tchuck is controlled based on this value (S211). This shortens the time it takes for the junction temperature Tj to reach a steady state.

[0118] In the examples shown in Figures 7, 9, 10, and 11, the temperature model parameters and the target temperature Tchuck_obj of the holding unit are not updated after system identification, but this is not the only option. The temperature model parameters and the target temperature Tchuck_obj of the holding unit may be updated repeatedly until the inspection of electronic device D is completed.

[0119] Here, the control unit 90 takes in the chuck temperature Tchuck and junction temperature Tj (see S103, etc.) and determines the parameters by system identification (see S104, etc.) for a period of time which is defined as the control cycle. The control unit 90 is configured to take a predetermined setting cycle ST (see Figure 8) by the operator (performer). The setting cycle ST is the same as or longer than the control cycle. For example, if the control cycle is 20 [msec], the setting cycle ST may be 20 [msec], or it may be a longer period than 20 [msec] (for example, 100 [msec]). The control unit 90 also sets a section (period, step) SC for each setting cycle ST. In the example in Figure 8, sections SC1 to SC8 are shown. For each of these sections SC, the chuck temperature Tchuck and junction temperature Tj are taken in (see S103, etc.), and the parameters are determined by system identification (see S104, etc.).

[0120] Furthermore, when determining parameters through system identification, the parameters may be determined, the transfer function may be determined, and the target junction temperature (Tjmax) may be estimated based on the chuck temperature Tchuck and junction temperature Tj during the interval (period, step) from the start of the inspection (start of power application to electronic device D) to the present. For example, in the first system identification step, the target junction temperature (Tjmax) is estimated based on the chuck temperature Tchuck and junction temperature Tj inspected in the first step (interval SC1). In the second system identification step, the target junction temperature (Tjmax) is estimated based on the chuck temperature Tchuck and junction temperature Tj inspected in the first and second steps (intervals SC1 to SC2). In the third system identification step, the target junction temperature (Tjmax) is estimated based on the chuck temperature Tchuck and junction temperature Tj inspected from the first to the third step (intervals SC1 to SC3).

[0121] Furthermore, when determining parameters through system identification, the parameters may be determined, the transfer function may be determined, and the target junction temperature (Tjmax) may be estimated based on the chuck temperature Tchuck and junction temperature Tj in a predetermined interval (for example, the most recent three times) prior to the current interval, after the start of the inspection. For example, in the first system identification step, the target junction temperature (Tjmax) is estimated based on the chuck temperature Tchuck and junction temperature Tj inspected in the first inspection (interval SC1). In the second system identification step, the target junction temperature (Tjmax) is estimated based on the chuck temperature Tchuck and junction temperature Tj inspected in the first and second inspections (intervals SC1 to SC2). In the third system identification step, the target junction temperature (Tjmax) is estimated based on the chuck temperature Tchuck and junction temperature Tj inspected in the first to third inspections (intervals SC1 to SC3). Then, in the fourth system identification step, the target junction temperature (Tjmax) is estimated based on the chuck temperature Tchuck and junction temperature Tj inspected in the second to fourth steps (section SC2 to SC4). Subsequently, in the Nth system identification step, the target junction temperature (Tjmax) may be estimated based on the chuck temperature Tchuck and junction temperature Tj inspected in the most recent three steps (from the (N-2)th step and the Nth section SCN-2, SCN-1, SCN).

[0122] The inspection system 1 has been described above, but this disclosure is not limited to the embodiments described above, and various modifications and improvements are possible within the scope of the gist of this disclosure as described in the claims.

[0123] Furthermore, this application claims priority based on Japanese Patent Application No. 2024-167781, filed on 26 September 2024, and the entire contents of these Japanese Patent Applications are incorporated herein by reference.

[0124] W Substrate D Electronic device E Electrode section 1 Inspection system 2 Storage chamber 3 Loader 4 Tester (device temperature detection unit) 10 Stage (chuck) 10a Refrigerant flow path 12 Probe card 12a Probe 13 Interface 14 Temperature control unit 20 Heater 25 Power supply 26 Chiller 30 Temperature detection unit (chuck temperature detection unit) 41 Power detection unit 50 Temperature control mechanism 55 Power supply 90 Control unit 91 Chuck temperature control unit 92 Detection unit temperature control unit 93 Analysis unit 60 Temperature detection unit

Claims

1. A temperature control method for an inspection system comprising: a chuck for holding a substrate having an electronic device to be inspected; a chuck temperature detection unit for detecting the temperature of the chuck; a chuck temperature control unit for controlling the temperature of the chuck; a tester for applying inspection power to the electronic device to inspect the electronic device; and a device temperature detection unit for detecting the temperature of the electronic device, the method comprising: preparing a temperature model having parameters; performing system identification of the parameters of the temperature model using a sequential algorithm; determining a transfer function from the chuck to the electronic device using the identified parameters; estimating a final value of the temperature of the electronic device based on the transfer function; and controlling the temperature of the chuck based on the final value of the temperature of the electronic device.

2. The temperature control method according to claim 1, wherein the step of performing the system identification is to determine the parameters of the temperature model based on the temperature of the chuck detected by the chuck temperature detection unit and the temperature of the electronic device detected by the device temperature detection unit.

3. The temperature control method according to claim 1, wherein the step of performing the system identification is performed using one of the least squares method, Kalman filter, prediction error method, maximum likelihood estimation method, or neural network.

4. The temperature control method according to claim 1, wherein the step of setting intervals at predetermined set intervals and performing the system identification step determines the parameters based on the temperature of the chuck and the temperature of the electronic device in the interval from the start of inspection to the present.

5. The temperature control method according to claim 1, wherein the step of setting intervals at predetermined setting cycles and performing the system identification is performed after the start of inspection, and the parameters are determined based on the temperature of the chuck and the temperature of the electronic device in predetermined intervals preceding the current interval.

6. The temperature control method according to claim 1, wherein after the estimated temperature of the electronic device estimated based on the transfer function and the detected temperature of the electronic device detected by the device temperature detection unit fall within a predetermined range, the temperature of the chuck is controlled based on the final temperature of the electronic device.

7. The temperature control method according to claim 1, comprising repeating the steps of: system identification of the parameters; determining the transfer function; estimating the final temperature of the electronic device; and controlling the temperature of the chuck.

8. The temperature control method according to claim 1, wherein the step of performing system identification using the sequential algorithm uses the parameters determined by the preceding electronic device as initial values.

9. An inspection system comprising: a chuck for holding a substrate having an electronic device to be inspected; a chuck temperature detection unit for detecting the temperature of the chuck; a chuck temperature control unit for controlling the temperature of the chuck; a tester for inspecting the electronic device by applying inspection power to the electronic device; a device temperature detection unit for detecting the temperature of the electronic device; and a control unit, wherein the control unit is configured to perform the steps of: preparing a temperature model having parameters; performing system identification of the parameters of the temperature model using a sequential algorithm; determining a transfer function from the chuck to the electronic device using the identified parameters; estimating a final temperature of the electronic device based on the transfer function; and controlling the temperature of the chuck based on the final temperature of the electronic device.

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