Patent Description:
A test device for testing electrical characteristics of electronic devices by placing a wafer, on which the electronic devices are formed, or a carrier, on which the electronic devices are disposed, on a mounting table and supplying a current to the electronic devices from a tester through probes or the like is known. The temperatures of the electronic devices are controlled by a cooling mechanism or a heating mechanism in the mounting table.

In <CIT>, a prober, which includes a temperature detection unit that detects a temperature of a chip to be tested on the basis of an electrical potential difference between electrode pads corresponding to respective electrodes of an element for temperature measurement by bringing probe needles into contact with the electrode pads connected to the element for temperature measurement in the chip to be tested, is disclosed. <CIT> describes a main chuck, on which a wafer having a number of devices is held, is driven under the control of a computer, and the devices on the wafer are brought into electric contact with the probes arranged on the upper side of the main chuck. On the basis of outputs from the probes, a tester sequentially measures the electric characteristics of the devices. When a heat-generating type device is measured, the inspecting method and apparatus of execute the following steps step of predicting the temperature of the device under measurement on the basis of the amount of heat generated from the device under measurement, step of predicting the temperatures of the devices that surround the device under measurement, step of selecting next-measurement devices (which are suitable for next measurement in light of their temperatures) from among the devices the temperatures of which are predicted in step, and calculating the position coordinates of the next-measurement devices, and a step of repeating the steps with respect to each of the devices, adding the distance between the device under measurement and the next-measurement device to the already-calculated distance, and selecting the shortest measurement route along which all devices are measured. <CIT> describes a prober that has improved positional precision of probing without reducing throughput is disclosed. The prober comprises a probe card having a probe, a wafer stage, a stage temperature adjustment mechanism, a wafer stage movement mechanism, a movement control section, and an alignment mechanism that detects the relative position between an electrode and the probe, wherein the movement control section controls the movement mechanism so as to cause the electrode to come into contact with the probe based on the detected relative position, and the prober further comprises a plurality of temperature sensors that detect the temperatures of a plurality of portions of the prober including the wafer stage and a predicted change amount calculation section that calculates the amount of change in relative position between the electrode and the probe based on a prediction model that uses at least part of the temperatures of the plurality of portions and the temperature difference between the wafer stage and the other sections as a variable. <CIT> describes a prober and a probe contact method for reducing errors in the contact position between a probe and an electrode without lowering throughput when conducting a probing test of a wafer at a high or low temperature have been disclosed. The prober comprises: a wafer chuck that holds a wafer; a movement mechanism that moves the wafer chuck; a temperature adjustment mechanism that adjusts the temperature of the wafer chuck to maintain the wafer at a predetermined temperature; an alignment means for measuring a positional relationship between the electrode of the device of the wafer and the probe; and a movement control section that calculates the amount of movement to touch the electrode to the probe based on the positional relationship between the electrode and the probe measured by the alignment means and controls the movement mechanism based on the calculated amount of movement, wherein: a wafer temperature sensor that detects the temperature of the wafer before it is held on the wafer chuck is further provided; and the movement control section comprises: a temperature change data storage section that stores in advance the wafer temperature changes after the wafers at various temperatures are held on the wafer chuck and the data about the changes in dimension; and a movement amount correction means for predicting the change in temperature after the wafer is held on the wafer chuck from the temperature of the wafer detected by the wafer temperature sensor and the data stored in the temperature change data storage means and corrects the calculated amount of movement in accordance with the predicted change in temperature when making an inspection while maintaining the temperature of the wafer chuck at a low or high set temperature. <CIT> describes a temperature regulation plate <NUM> is divided into at least two areas, a heater <NUM> for applying a temperature load in correspondence with such areas and its control system are divided and controlled independently to set temperatures, and a cooling source is controlled by comparing the measurements from temperature sensors <NUM> arranged in respective areas for controlling the heater <NUM> and switching the measurement for calculating the control output sequentially thus reducing variation in in-plane temperature of a wafer due to heating when an electric load is applied. Since consumption and burning of a probe are prevented, highly reliable wafer level burn-in method and apparatus can be provided. <CIT> describes methods for measuring temperature and a tool for calibrating temperature control of a substrate support in a processing chamber without contact with a surface of the substrate support. In one embodiment, a test fixture with a temperature sensor is removably mounted to an upper surface of a chamber body of the processing chamber such that the temperature sensor has a field of view including an area of the substrate support that is adjacent to a resistive coil disposed in the substrate support. One or more calibration temperature measurements of the area of the substrate support are taken by the temperature sensor and simultaneously one or more calibration resistance measurements of the resistive coil are taken corresponding to each calibration temperature measurement. Temperature control of a heating element disposed in the substrate support is calibrated based on the calibration temperature and calibration resistance measurements. <CIT> describes an inspection device for inspecting an inspection target substrate includes a probe card, a tester, a plurality of conductive lines, and a resistor. The probe card has probes to be in contact with the inspection target substrate. The tester is configured to transmit and receive electric signals for an inspection to and from the inspection target substrate through the probes. The conductive lines electrically connect the probe card with the tester, and at least a part of the conductive lines is electrically connected to the probes. The resistor is formed at the probe card and serves as an electrical resistor. The tester is further configured to measure a resistance of the resistor based on the electric signals transmitted and received through the conductive lines. <CIT> describes a temperature control device for controlling the temperature of an object that is subject to temperature control is provided with: a heating mechanism which has a heat source for heating said object subject to temperature control; a temperature measuring instrument for measuring the peripheral temperature of said object subject to temperature control; a temperature estimation unit for dynamically estimating the temperature of said object subject to temperature control on the basis of power inputted to the heat source, power supplied to said object subject to temperature control, and the peripheral temperature; and a temperature controller for performing control on the temperature of said object subject to temperature control by controlling the power inputted to the heat source on the basis of the estimated temperature of said object subject to temperature control.

However, it is difficult to continuously detect a temperature of an electronic device using an element for temperature measurement in consideration of a trade-off with a test flow. Further, when a heat amount of the electronic device is large, a difference in temperature between the electronic device and a mounting table becomes large, and thus it is difficult to control the temperature of the electronic device with a temperature sensor provided on the mounting table.

In one aspect, the present disclosure is directed to providing a test device control method, in which temperature controllability of an object to be tested is improved, and a test device.

The above problem is solved by the subject matter of the independent claims. Examples and technical descriptions of apparatuses, products and/or methods in the description and/or drawings which are not covered by the claims are presented not as embodiments of the invention but as background art or examples useful for understanding the invention. In accordance with an aspect of example, there is provided a control method of a test device, the test device comprising a chuck on which an object to be tested is mounted, a tester configured to supply electric power to the object to be tested to test the object to be tested, and a controller configured to control a temperature of the chuck. The control method comprises: when an actual temperature of the object to be tested cannot be fed back, estimating a temperature difference between the temperature of the chuck and the temperature of the object to be tested on the basis of a heat amount of the object to be tested; correcting a target temperature of the chuck on the basis of a target temperature of the object to be tested and the temperature difference; and controlling the temperature of the chuck on the basis of the corrected target temperature of the chuck and an actual temperature of the chuck.

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In each drawing, like reference numerals denote like elements and descriptions thereof will not be repeated.

A test device <NUM> according to an embodiment of the present disclosure will be described with reference to <FIG> is an example of a schematic cross-sectional view for describing a configuration of the test device <NUM> according to the embodiment of the present disclosure.

The test device <NUM> is a device for testing electrical characteristics of each of a plurality of electronic devices (i.e., objects to be tested; device under test (DUT)) formed on a wafer (substrate) W. Meanwhile, a substrate having objects to be tested is not limited to the wafer W and includes a carrier on which electronic devices are disposed, a glass substrate, a single chip, or the like. The test device <NUM> includes an accommodation chamber <NUM> that accommodates a chuck <NUM> on which the wafer W is placed, a loader <NUM> disposed adjacent to the accommodation chamber <NUM>, and a tester <NUM> disposed to cover the accommodation chamber <NUM>.

The accommodation chamber <NUM> has a shape of a hollow housing. The chuck <NUM> on which the wafer W is placed and a probe card <NUM> disposed to face the chuck <NUM> are accommodated inside the accommodation chamber <NUM>. The probe card <NUM> has a plurality of needle-shaped probes (contact terminals) <NUM> disposed to correspond to electrode pads or solder bumps which are provided to correspond to electrodes of each electronic device of the wafer W.

The chuck <NUM> has a fixing mechanism (not shown) for fixing the wafer W to the chuck <NUM>. Thereby, the deviation of a relative position of the wafer W with respect to the chuck <NUM> is prevented. Further, a moving mechanism (not shown) for moving the chuck <NUM> in a horizontal direction and a vertical direction is provided in the accommodation chamber <NUM>. Thereby, relative positions of the probe card <NUM> and the wafer W are adjusted so that the electrode pads or solder bumps which are provided to correspond to the electrodes of each electronic device are brought into contact with each probe <NUM> of the probe card <NUM>. Further, the chuck <NUM> includes a temperature sensor 11c. Further, the chuck <NUM> includes a temperature controller 11d such as a heater, a cooler, or the like. Information on a temperature of the chuck <NUM>, which is detected by the temperature sensor 11c, is transmitted to a controller <NUM>. The temperature controller 11d is controlled by the controller <NUM>.

The loader <NUM> withdraws the wafer W, on which the electronic devices are disposed, from a front opening unified pod (FOUP) (not shown) which is a transfer container, places the wafer W on the chuck <NUM> inside the accommodation chamber <NUM>, and removes the tested wafer W from the chuck <NUM> to accommodate it in the FOUP.

The probe card <NUM> is connected to the tester <NUM> through an interface <NUM>, and when each probe <NUM> is brought into contact with the electrode pads or solder bumps which are provided to correspond to electrodes of each electronic device of the wafer W, each probe <NUM> supplies electric power to the electronic device from the tester <NUM> through the interface <NUM> or transmits a signal from the electronic device to the tester <NUM> through the interface <NUM>.

The tester <NUM> has a test board (not shown) for reproducing a part of a circuit configuration of a motherboard on which electronic devices are mounted, and the test board is connected to a tester computer <NUM> for determining whether the electronic device is good or not based on the signal from the electronic device. In the tester <NUM>, by replacing the test board, it is possible to reproduce the circuit configuration of a plurality of types of motherboards.

The tester <NUM> has an electric power supply 14a for supplying electric power to the electronic device through the probe <NUM>. The tester <NUM> transmits information on the electric power supplied to the electronic device to the controller <NUM>.

The tester <NUM> has a temperature detection unit 14b for detecting a temperature of the electronic device. An element 14c for temperature measurement is provided on the wafer W. The element 14c for temperature measurement is, for example, a diode or the like and is an element whose electrical potential difference varies according to a temperature thereof. The temperature detection unit 14b measures an electrical potential difference between both terminals of the element 14c using the probe <NUM> and detects the temperature of the element 14c on the basis of the electrical potential difference. The tester <NUM> transmits information on the temperature of the electronic device detected by using the element 14c to the controller <NUM>.

The controller <NUM> controls the temperature of the chuck <NUM> by controlling the temperature controller 11d of the chuck <NUM>.

Next, the controller <NUM> will be described with reference to <FIG> is an example of a block diagram for describing control of the temperature of the chuck <NUM>.

The controller <NUM> includes a target temperature generation unit <NUM>, a temperature difference estimation unit <NUM>, a dead time compensation unit <NUM>, a selector <NUM>, and a model tracking controller <NUM>. Here, an actual temperature (chuck temperature Tchuck) of the chuck <NUM>, which is detected by the temperature sensor 11c, is input to the controller <NUM>. Further, an actual temperature (DUT temperature TDUT) of an electronic device (i.e., DUT) to be tested, which is detected by the temperature detection unit 14b, is input to the controller <NUM>. However, the DUT temperature TDUT is a temperature that cannot be obtained depending on a test flow. Further, information on the electric power which is supplied to the electronic device to be tested from the electric power supply 14a is input to the controller <NUM>. Here, a heat amount (DUT heat amount HDUT) of the electronic device to be tested may be estimated based on the supplied electric power. In the example of <FIG>, it is assumed that the DUT heat amount HDUT is input to the controller <NUM>.

A set temperature of the electronic device is input to the controller <NUM>. For example, the set temperature is input to the controller <NUM> from the tester computer <NUM>. Further, a switching signal is input to the controller <NUM>. The switching signal is a signal indicating whether a test flow is capable of obtaining the DUT temperature TDUT. For example, the switching signal is input to the controller <NUM> from the tester computer <NUM>.

The target temperature generation unit (device target temperature generation unit) <NUM> generates a target temperature T<NUM> of the electronic device. Specifically, the set temperature of the electronic device is input to the target temperature generation unit <NUM> from the tester computer <NUM>. Further, the target temperature generation unit <NUM> has a reference model in which a change in the set temperature over time is associated with a change in the target temperature T<NUM> over time. The target temperature generation unit <NUM> generates the target temperature T<NUM> of the electronic device on the basis of the input set temperature of the electronic device and the reference model.

The temperature difference estimation unit <NUM> estimates an estimated value (estimated temperature difference value ΔT<NUM>) of a difference in temperature between the electronic device and the chuck <NUM>. Specifically, the temperature difference estimation unit <NUM> estimates the estimated temperature difference value ΔT<NUM> between the electronic device and the chuck <NUM> on the basis of the DUT heat amount HDUT.

<FIG> are examples of a block diagram for describing the temperature difference estimation unit <NUM>. As shown in <FIG>, the temperature difference estimation unit <NUM> may estimate the estimated temperature difference value ΔT<NUM> by multiplying the DUT heat amount HDUT by a parameter (steady gain) K. Further, as shown in <FIG>, the temperature difference estimation unit <NUM> may estimate the estimated temperature difference value ΔT<NUM> using a first order delay function. That is, the parameter specifies a time constant <NUM>/a in addition to the steady gain K. By using the first order delay, control may be performed in consideration of dynamic characteristics of changes in temperature.

<FIG> is an example of a graph for describing a method of adjusting a parameter. Here, the steady gain K depends on a position of the electronic device on the chuck <NUM>. Further, a horizontal axis of <FIG> indicates a distance from the center of the electronic device and a vertical axis indicates the parameter K.

Here, the changes in temperature caused by the heat generated by the electronic device is roughly inversely proportional to the distance from the center of the electronic device. Therefore, the parameter K may be expressed by an equation K=a/r+b, where r denotes a distance between a position of the temperature sensor 11c in the chuck <NUM> and the center of the electronic device to be tested. Further, a and b are device-specific parameters. Further, within a range (r<rc) in which the distance r is small, the parameter K may be expressed by an equation K=a/rc + b.

<FIG> is an example of a diagram for describing a method of adjusting a parameter K. In the method shown in <FIG>, the steady gain K is described as being estimated using the distance r, but as shown in <FIG>, parameters K1, K2, K3,. may be set in advance for position of each electronic device. Thereby, estimation accuracy of the estimated temperature difference value ΔT<NUM> estimated by the temperature difference estimation unit <NUM> may be improved.

Referring to <FIG> again, a subtractor (actual temperature difference calculation unit) <NUM> calculates a difference (actually measured temperature difference value ΔT<NUM>) in temperature between the electronic device and the chuck <NUM>. Specifically, the subtractor <NUM> calculates the actually measured temperature difference value ΔT<NUM> between an actual temperature (DUT temperature TDUT) of the electronic device and an actual temperature (chuck temperature Tchuck) of the chuck <NUM>.

The dead time compensation unit <NUM> estimates a difference (compensated temperature difference value ΔT2a) in temperature between the electronic device and the chuck <NUM> by performing a dead time compensation for the actually measured temperature difference value ΔT<NUM>.

<FIG> is an example of a block diagram for describing the dead time compensation unit <NUM>. The dead time compensation unit <NUM> shown in <FIG> is the same as a general Smith compensator. By performing Smith compensation, a temperature difference ΔT between an input of a disturbance and a response can be compensated using an estimated value.

The dead time compensation unit <NUM> includes a temperature difference estimation unit <NUM>, a delay processing unit <NUM>, a subtractor <NUM>, and an adder <NUM>. The temperature difference estimation unit <NUM> estimates a difference in temperature between the electronic device and the chuck <NUM> on the basis of the DUT heat amount HDUT. The delay processing unit <NUM> outputs the difference in temperature between the electronic device and the chuck <NUM> estimated by the temperature difference estimation unit <NUM> to be delayed by n steps. The subtractor <NUM> calculates a difference between the actually measured temperature difference value ΔT<NUM> and an output value of the delay processing unit <NUM>. The adder <NUM> calculates the sum of an output value of the temperature difference estimation unit <NUM> and an output value of the subtractor <NUM> and outputs the calculated sum as a compensated temperature difference value ΔT2a.

With such a configuration, the actually measured temperature difference value ΔT<NUM> is not changed due to the delay during n steps after power supply to the electronic device is started. For this reason, the dead time compensation unit <NUM> outputs the estimated temperature difference value of the temperature difference estimation unit <NUM> as the compensated temperature difference value ΔT2a. Then, when the temperature of the electronic device enters a steady state, the output value of the delay processing unit <NUM>, which is subtracted by the subtractor <NUM>, and the output value of the temperature difference estimation unit <NUM>, which is added by the adder <NUM>, are canceled. For this reason, the dead time compensation unit <NUM> outputs the actually measured temperature difference value ΔT<NUM> as the compensated temperature difference value ΔT2a.

Referring to <FIG> again, the selector <NUM> receives the estimated temperature difference value ΔT<NUM> of the temperature difference estimation unit <NUM> and the compensated temperature difference value ΔT2a of the dead time compensation unit <NUM> and outputs one of the values. A switching signal is input to the selector <NUM>. When the DUT temperature can be detected by the temperature detection unit 14b, the selector <NUM> outputs the compensated temperature difference value ΔT2a of the dead time compensation unit <NUM>. On the other hand, when the DUT temperature cannot be detected by the temperature detection unit 14b, the selector <NUM> outputs the estimated temperature difference value ΔT<NUM> of the temperature difference estimation unit <NUM>.

Referring to <FIG> again, a subtractor (chuck target temperature generation unit) <NUM> calculates a target temperature of the chuck <NUM> by subtracting the temperature difference (ΔT<NUM> or ΔT2a) between the electronic device and the chuck <NUM> from the target temperature T<NUM> of the electronic device.

The model tracking controller <NUM> controls model tracking of the temperature controller 11d of the chuck <NUM> on the basis of the target temperature (output value of the subtractor <NUM>) of the chuck <NUM> and the actual temperature (chuck temperature Tchuck) of the chuck <NUM>.

Next, control of the temperature of the electronic device using the test device <NUM> according to the embodiment of the present disclosure will be described with reference to <FIG> is an example of a graph showing a change in the DUT temperature TDUT of the electronic device and a change in the temperature Tchuck of the chuck <NUM> over time. Further, in the graph of <FIG>, the DUT temperature TDUT of the electronic device is indicated by a broken line, and the temperature Tchuck of the chuck <NUM> is indicated by a solid line.

First, the temperatures of the chuck <NUM> and the electronic device are raised to a set temperature. Thereafter, electric power is supplied to the electronic device (S101 to S103) so that a test is performed.

Step S101 is a test in which it is difficult (feedback is not possible) to detect the temperature of the electronic device using the element 14c for temperature measurement in consideration of the test flow. In this case, the controller <NUM> estimates the estimated temperature difference value ΔT<NUM> from the DUT heat amount HDUT by the temperature difference estimation unit <NUM> and controls the temperature of the chuck <NUM> using the estimated temperature difference value ΔT<NUM>. Further, a preset value is used as the parameter K. For this reason, a slight difference may occur between the DUT temperature TDUT and the set temperature.

Step S102 is a test in which it is possible (feedback is possible) to detect the temperature of the electronic device using the element 14c for temperature measurement in consideration of the test flow. In this case, the controller <NUM> estimates the compensated temperature difference value ΔT2a by performing the dead time compensation for the actually measured temperature difference value ΔT<NUM> by the dead time compensation unit <NUM> and controls the temperature of the chuck <NUM> using the compensated temperature difference value ΔT2a. Here, since the temperature of the chuck <NUM> is controlled based on the actual temperature (DUT temperature TDUT) of the electronic device, the temperature of the electronic device can be more appropriately controlled.

Further, in step S102, the parameter K is adjusted. <FIG> is an example of a block diagram for describing adjustment of the parameter K. The controller <NUM> further includes a subtractor (actual temperature difference calculation unit) <NUM> and a parameter generation unit <NUM>. The subtractor <NUM> calculates a difference in temperature between the electronic device and the chuck <NUM>. Specifically, the subtractor <NUM> calculates an actually measured temperature difference value ΔT<NUM> between the actual temperature (DUT temperature TDUT) of the electronic device and the actual temperature (chuck temperature Tchuck) of the chuck <NUM>. The parameter generation unit <NUM> calculates (adjusts) the parameter K on the basis of the DUT temperature TDUT and the actually measured temperature difference value ΔT<NUM> which is calculated by the subtractor <NUM>. The parameter K adjusted by the parameter generation unit <NUM> is output to the temperature difference estimation unit <NUM> (see <FIG>). The parameter K of the temperature difference estimation unit <NUM> is updated.

Referring to <FIG> again, step S103 is a test in which it is difficult (feedback is not possible) to detect the temperature of the electronic device using the element 14c for temperature measurement in consideration of the test flow. In this case, the controller <NUM> estimates the estimated temperature difference value ΔT<NUM> from the DUT heat amount HDUT by the temperature difference estimation unit <NUM> and controls the temperature of the chuck <NUM>. Further, the value adjusted by the parameter generation unit <NUM> in step S102 is used as the parameter K. For this reason, the temperature of the electronic device can be more appropriately controlled.

<FIG> are another examples of a graph showing a change in the DUT temperature TDUT of the electronic device and a change in the temperature Tchuck of the chuck <NUM> over time.

<FIG> is a graph showing the DUT temperature TDUT of the electronic device and the temperature Tchuck of the chuck <NUM> in the case in which the temperature of the chuck <NUM> is controlled to be constant. By supplying electric power to the electronic device during a test, the electronic device generates heat and the DUT temperature TDUT of the electronic device rises.

On the other hand, <FIG> is a graph showing the DUT temperature TDUT of the electronic device and the temperature Tchuck of the chuck <NUM> in the case in which the control of the present embodiment is performed. By lowering the temperature of the chuck <NUM> on the basis of the DUT heat amount HDUT of the electronic device, the DUT temperature TDUT of the electronic device can be controlled to be constant.

Claim 1:
A control method of a test device (<NUM>), the test device (<NUM>) comprising a chuck (<NUM>) on which an object to be tested is mounted, a tester (<NUM>) configured to supply electric power to the object to be tested to test the object to be tested, and a controller (<NUM>) configured to control a temperature of the chuck (<NUM>), characterized in that the control method comprising:
when a signal inputted to the controller (<NUM>) indicates that an actual temperature of the object to be tested cannot be fed back, by using the controller (<NUM>),
estimating a heat amount generated by the object to be tested based on information on the electric power supplied to the object to be tested and estimating a temperature difference between the temperature of the chuck (<NUM>) and the temperature of the object to be tested on the basis of the estimated heat amount generated by the object to be tested;
correcting a target temperature of the chuck (<NUM>) on the basis of a target temperature of the object to be tested and the temperature difference; and
controlling the temperature of the chuck (<NUM>) on the basis of the corrected target temperature of the chuck (<NUM>) and an actual temperature of the chuck (<NUM>), and
when a signal inputted to the controller (<NUM>) indicates that the actual temperature of the object to be tested can be fed back, by using the controller (<NUM>),
calculating the temperature difference between the temperature of the chuck (<NUM>) and the temperature of the object to be tested based on the actual temperature of the object to be tested and the actual temperature of the chuck (<NUM>);
correcting the target temperature of the chuck (<NUM>) based on the target temperature of the object to be tested and the temperature difference; and
controlling the temperature of the chuck (<NUM>) based on the corrected target temperature of the chuck (<NUM>) and the actual temperature of the chuck (<NUM>).