Prober and control method therefor

Abstract

Provided are a prober and a control method therefor, said prober being capable of accurate temperature control in a wide temperature range. This prober inspects the electrical characteristics of an object under inspection, and comprises: a chuck unit that chucks the object under inspection; and a cooling liquid flow passage that is configured so as to be able to control the temperature of a surface of the chuck unit, and so as to be able to circulate and supply the cooling liquid in a boiling state at least at a heat transfer surface of the chuck unit. By circulating the cooling liquid in the boiling state, cooling can be performed using the phase change energy of the boiling state, and thus accurate temperature control is possible in a wide temperature range.

Description

Prober and its control method

[0001] The present invention relates to a prober for inspecting electrical characteristics of an object to be inspected, such as a semiconductor wafer, and a method for controlling the prober.

[0002] In the semiconductor manufacturing process, a prober is used to inspect the electrical characteristics of semiconductor chips formed on a semiconductor wafer. The prober is configured to inspect the electrical characteristics of the semiconductor chip by outputting a test signal from a tester to the semiconductor chip via a probe card. The prober is provided with a chuck for suction-holding the semiconductor wafer.

[0003] Some semiconductor chips are used in low-temperature environments such as -60°C, while others are used in high-temperature environments such as 200°C. Inspections using a prober must be performed in accordance with the temperature of the semiconductor chip's operating environment to confirm operational reliability. It is also necessary to set the temperature of the prober's chuck over a wide range to accommodate various semiconductor chips. Therefore, probers are provided with temperature adjustment mechanisms, such as a heater (heating mechanism) and a cooling mechanism, inside the chuck (see, for example, Patent Document 1).

[0004] Patent No. 5121322

[0005] In conventional probers, it has been difficult to accurately control the temperature of the prober chuck over a wide temperature range using a single system. Conventionally, in order to accurately control the temperature of the chuck over a wide temperature range, multiple systems have been prepared, one for low-temperature testing and one for high-temperature testing, but this has the problem of making the systems complex and large.

[0006] SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a prober capable of accurate temperature control over a wide temperature range and a control method thereof.

[0007] A prober according to one aspect of the present invention is a prober for inspecting the electrical characteristics of an object to be inspected, and includes a chuck portion for adsorbing the object to be inspected, and a cooling liquid flow path configured to be able to control the temperature of the surface of the chuck portion and to circulate and supply a cooling liquid in a boiled state on at least the heat transfer surface of the chuck portion.

[0008] Furthermore, a method for controlling a prober according to one aspect of the present invention is a method for controlling a prober that inspects electrical characteristics of an object to be inspected, and includes the steps of: adsorbing the object to be inspected to a chuck portion; absorbing heat generated in the chuck portion by circulating and supplying a coolant in a boiling state at least on the heat transfer surface of the chuck portion in a coolant flow path of the chuck portion; and heating the chuck portion by a heater provided inside the chuck portion.

[0009] According to the present invention, it is possible to provide a prober capable of accurate temperature control over a wide temperature range and a control method thereof.

[0010] FIG. 1 is a schematic diagram illustrating the configuration of a prober 1 according to a first embodiment. FIG. 2 is a schematic diagram illustrating the effects of the prober 1 according to the first embodiment. FIG. 3 is a schematic diagram illustrating the configuration of a prober 1 according to a second embodiment. FIG. 4 is a schematic diagram illustrating the operation of the prober 1 according to the second embodiment. FIG. 5 is a schematic diagram illustrating the configuration of a prober 1 according to a third embodiment. FIG. 6 is a schematic diagram illustrating the configuration of a prober 1 according to a fourth embodiment. FIG. 7 is a schematic diagram illustrating the configuration of a prober 1 according to a fifth embodiment. FIG. 8 is an example of a boiling curve.

[0011] The present embodiment will be described below with reference to the accompanying drawings. The accompanying drawings illustrate embodiments according to the principles of the present disclosure. However, these drawings are intended to aid in understanding the present disclosure and are not intended to limit the present disclosure in any way. The description in this specification is merely exemplary and does not limit the scope or application of the present disclosure. The present embodiment has been described in sufficient detail to enable those skilled in the art to implement the present disclosure. However, it should be understood that other implementations and forms are possible, and that changes in configuration and structure and substitutions of various elements are possible without departing from the scope and spirit of the technical concept of the present disclosure. Therefore, the following description should not be interpreted as being limited thereto.

[0012] In the following description, a prober that inspects a substantially disk-shaped semiconductor wafer as an object to be inspected will be described as an example, but this is not intended to limit the invention.

[0013] First Embodiment A prober 1 according to a first embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic diagram showing the configuration of the prober 1 according to the first embodiment.

[0014] As shown in FIG. 1, the prober 1 includes a chuck 10 for holding a wafer W as an object to be inspected, a probe card 20 that contacts the wafer W to inspect the electrical characteristics of the wafer W, a tester 30, a coolant supply unit 40, and a control unit 50.

[0015] The chuck 10 has a chuck body 11 and a holding surface (surface) 12 formed on the surface of the chuck body 11 and capable of holding a wafer W. The chuck body 11 is made of a metal such as aluminum or copper, or a material such as ceramic having good thermal conductivity.

[0016] The prober 1 also includes a probe card 20 having probes that are brought into contact with electrodes of the wafer W to be inspected, and a tester (test head) 30. The tester 30 includes a tester main body 31 and an interface 32 that electrically connects terminals of the tester main body 31 with terminals of the probe card 20. The tester 30 supplies power and various test signals from the terminals of the probe card 20 to the chips on the wafer W, and analyzes the signals output to the electrodes of the chips to check whether the chips are operating normally.

[0017] The chuck 10 also includes a heater 13 (temperature adjustment unit) and a coolant flow path 14 within the chuck body 11. The heater 13 heats the holding surface 12 of the chuck body 11. The coolant flow path 14 is configured to receive a coolant supply from a coolant supply unit 40 via a supply path 41 and to discharge the coolant to a discharge path 42. The coolant discharged from the discharge path 42 is returned to the coolant supply unit 40.

[0018] As will be described later, the coolant supply unit 40 is controlled so that the coolant in this embodiment can be circulated and supplied to the coolant flow path 14 in a boiling state at least near the holding surface 12. It is possible to select a state in which the coolant is circulated without boiling by keeping the coolant below its saturation temperature, or to circulate the coolant with the coolant temperature above its saturation temperature while boiling at least near the holding surface 12. By appropriately controlling the boiling state, it is possible to control the temperature of the holding surface 12 while obtaining a high heat absorption capacity even in the boiling state. For this reason, the coolant supply unit 40 in this embodiment includes a heating unit for supplying the coolant in a boiling state at least near the holding surface 12 (the heat transfer surface of the chuck portion) and a pump (not shown) for circulation. Furthermore, if the heat absorption by the coolant 40 becomes excessive, the heater 13 can be used to heat the coolant and maintain the temperature of the holding surface 12.

[0019] Temperature sensors for measuring the temperature of the coolant are also provided within the chuck body 11. In FIG. 1 , as an example, a temperature sensor TS1 is provided near the holding surface 12 (the heat transfer surface of the chuck portion), and temperature sensors TSi and TSo are provided near the inlet and outlet of the coolant flow path 14, respectively. By providing the temperature sensor TS1 near the holding surface 12, the temperature of the holding surface 12 of the chuck body 11 can be directly measured. Furthermore, by providing the two temperature sensors TSi and TSo at the inlet and outlet of the coolant flow path 14, the temperature difference between the inlet and outlet of the coolant can be determined, and the amount of heat absorption by the coolant can be calculated. The amount of heat absorption can be calculated not only from the difference in the detection values ​​of the temperature sensors TSi and TSo, but also by factoring in the detection value of the temperature sensor TS1, which measures the temperature of the heat transfer surface, and the detection values ​​of the pressure sensors PS1 and PS2, which will be described later. It goes without saying that the number and arrangement of the temperature sensors shown in FIG. 1 are merely an example and are not limited thereto.

[0020] Pressure sensors PS1 and PS2 for measuring the pressure of the coolant are provided within the chuck body 11. In FIG. 1, the pressure sensors PS1 and PS2 are provided at the inlet and outlet of the coolant flow path 14, respectively, but this is not limiting. It is preferable to provide pressure sensors at a plurality of spaced positions to detect the difference in coolant pressure. Note that instead of a temperature sensor, a heat flux sensor for measuring the heat flow rate may be provided in the coolant flow path 14.

[0021] In this embodiment, the pressure sensors PS1 and PS2 are provided to detect the boiling state of the coolant. By measuring the pressure of the coolant, it is possible to determine whether the coolant is boiling. It is also possible to employ a configuration in which the boiling state of the coolant is determined taking into account the measurement results of the temperature sensors TSi and TSo.

[0022] The control unit 50 controls the coolant supply unit 40 and the heater 13 based on the temperature and pressure detected by the temperature sensors TS1, TSi, TSo and the pressure sensors PS1, PS2, so that the surface of the wafer W reaches the desired temperature.

[0023] Next, the function of the prober 1 of this embodiment will be described together with the performance of the coolant, with reference to Fig. 2. Fig. 2 shows a number of coolants with different boiling and melting points that can be used in the prober 1. As mentioned above, the prober is required to be able to set a wide range of temperatures, from low temperatures of -50°C or less to high temperatures of around 150°C to 200°C. However, it is difficult to cover such a wide temperature range with a single type of coolant.

[0024] For example, coolant A can maintain a liquid state even in high-temperature regions and provide cooling, but its viscosity increases in low-temperature regions, making circulation difficult. Meanwhile, coolant B maintains high fluidity without increasing viscosity in low-temperature regions, but boils in high-temperature regions. When the coolant boils and evaporates, its heat absorption ability decreases, making it difficult to regulate the chuck temperature. While it is possible to maintain the coolant in a liquid state even in high-temperature regions by providing a mechanism for adjusting the coolant pressure, providing a pressure adjustment mechanism increases the size and cost of the device.

[0025] As described above, in conventional probers, when measurements were to be made over a wide temperature range, it was not possible to use a single type of coolant under normal pressure, and it was necessary to use multiple types of coolant or to adopt a complex configuration such as incorporating a pressure adjustment mechanism.

[0026] In contrast, in the first embodiment, a low-boiling-point coolant, such as coolant B, can be used even in the boiling region. As shown in Figure 3, when the coolant reaches its saturation temperature (boiling point) at least near the holding surface 12 and enters a boiling state, it transitions to a phase change state before completely evaporating. In this phase change state, heat transfer is easier, i.e., the heat absorption capacity is high, and a greater heat absorption state can be achieved than in the liquid phase. Once the coolant passes through the phase change state and completely evaporates, the heat absorption capacity drops sharply as shown in the graph (arrow A) in Figure 3. Therefore, it is preferable to maintain the phase change state by controlling the boiling state.

[0027] Whether the coolant has passed the phase change state and vaporized can be determined based on the temperatures of the temperature sensors TSi, TSo, and TS1, the temperature difference between them, etc. Also, the measurement signals of the pressure sensors PS1 and PS2 can be used to detect the transition from the liquid phase state to the phase change state, or the transition from the phase change state to the vaporization state.

[0028] As an example, in the prober 1 of this embodiment, the target temperature is set to a temperature Ttgt at which a phase change state is achieved, and the temperature of the chuck body 11 is raised by the heater 13 until the target temperature Ttgt is reached, while the temperature of the holding surface 12 is monitored by the temperature sensor TS1. When the temperature detected by the temperature sensor TS1 reaches the target temperature Ttgt, the heater 13 (and / or the flow rate, pressure, etc. of the coolant) is controlled so that the amount of heat absorbed by the coolant and the amount of heat generated by the heater 13 and the tester 30 are approximately equal, taking into account the amount of heat generated by the test signal from the tester 30. By controlling the heater 13, etc. in this way to approximately equalize the amount of heat absorbed and the amount of heat generated, overshooting and hunting can be suppressed, enabling rapid and stable temperature control. It is also possible to control the heater 13, etc. by acquiring data on either the amount of heat absorbed or the amount of heat generated. In addition, the heater 13 can be controlled taking into consideration the temperatures detected by the temperature sensors TSi and TSo in the coolant flow path 14 and the pressures detected by the pressure sensors PS1 and PS2. If a heat flux sensor is provided, the heat flux sensor can be configured to measure at least one of the amount of heat generated by the wafer W and the amount of heat absorbed by the coolant. The amount of heat generated by the test signal from the tester 30 can also be calculated based on the power of the applied test signal.

[0029] As described above, the prober 1 of the first embodiment is configured to circulate and supply the coolant at a boiling state at least on the holding surface 12 of the chuck body 11. At low temperatures below the saturation temperature, a sufficient temperature difference between the coolant and the holding surface 12 and maintaining the fluidity of the coolant can provide high heat absorption capacity. At high temperatures above the saturation temperature, a high heat absorption capacity can be provided by the phase change of the coolant in the boiling state. If the boiling of the coolant is controlled so that the coolant is maintained in a phase change state, accurate temperature control over a wide temperature range is possible even when using only one type of coolant, compared to using only liquid-phase coolants. The coolant used in this embodiment may be a fluorocarbon-based antifreeze or a liquid primarily composed of water. Water has a higher phase change energy at boiling than other liquids, making it suitable as the coolant in this embodiment.

[0030] [Second Embodiment] A prober 1 according to a second embodiment will be described with reference to Figure 4. The same components as those in the prober 1 according to the first embodiment are designated by the same reference numerals in Figure 4, and therefore, redundant description will be omitted below. This prober 1 differs from the first embodiment in that the heaters 13' are configured as a heater array in which the heaters 13' are divided into multiple regions. Each divided region may have a size that is approximately the same as or corresponds to the size of the region that is in contact with the probe card 20 and is the target of testing, but is not limited to this.

[0031] The divided heater 13' is configured so that the amount of heat generated can be varied for each region. For example, as shown in Fig. 5, the amount of heat generated by the heater 13' is small immediately below the heating region Ah of the wafer W that is in contact with the probe card 20 and heated, and the amounts of heat generated H1 to H4 are large immediately below the regions other than the heating region Ah (HAh

[0032] ​In the prober 1 of this embodiment, the heat absorption capacity of the coolant in the heating region Ah is increased by boiling the coolant at least on the surface of the holding surface 12, but there may be areas where the boiling state is not achieved, and the coolant in those areas does not have sufficient heat absorption capacity. According to this embodiment, the divided heaters can locally change the heat generation amount in accordance with the boiling state of the coolant in that area, and as a result, the heat absorption capacity of the coolant can be made uniform over the entire holding surface 12.

[0033] [Third Embodiment] A prober 1 according to a third embodiment will be described with reference to Fig. 6. The same components as those in the prober 1 according to the previous embodiment are given the same reference numerals in Fig. 6, and therefore, redundant description will be omitted below. This prober 1 includes a Peltier element 15 instead of the heater 13'. The Peltier element 15 is configured as a Peltier element array divided into multiple elements, as in the second embodiment.

[0034] Each of the multiple divided Peltier elements 15 can have one surface as a heat dissipation surface and the other surface as a heat absorption surface depending on the direction of the current flowing through it. By placing the heat dissipation surface on the holding surface 12 side of the chuck body 11, the holding surface 12 can be heated appropriately. When the direction of the current is reversed, heat is absorbed from the holding surface 12, while heat is also dissipated toward the coolant in the coolant flow path 14. Note that although only a Peltier element is provided in the example of FIG. 6, a heater 13 can also be provided.

[0035] For example, the heat dissipation surface of the Peltier element 15 can be positioned on the holding surface 12 side, and the heat absorption surface can be positioned on the coolant flow path 14 side. By placing the Peltier element 15 between the coolant flow path 14 and the holding surface 12 and applying an appropriate current while ensuring a heat absorption amount greater than the heat generation amount of the heating region Ah through liquid-phase cooling or boiling cooling of the coolant, the temperature of the wafer W can be brought closer to a target temperature. Furthermore, by boiling the coolant on the heat dissipation surface of the Peltier element 15, the coolant can be maintained in a phase change state, thereby maximizing the cooling efficiency of the coolant. [Fourth Embodiment] A prober 1 according to a fourth embodiment will be described with reference to FIG. 7 . Components identical to those of the prober 1 according to the first embodiment are designated by the same reference numerals in FIG. 7 , and therefore, redundant description will be omitted below. This prober 1 does not include the heater 13. Instead, a heater 43 for heating the coolant is provided outside the chuck 10, for example, in the supply path 41.

[0036] In the above-described embodiment, the heater 43 is provided outside the chuck 10, but as in the above-described embodiment, boiling cooling is performed by boiling the cooling liquid near the holding surface 12, and the heater 43 can heat the cooling liquid, for example, if excessive cooling occurs.

[0037] Fifth Embodiment A prober 1 according to a fifth embodiment will be described with reference to FIG. 8. The same components as those in the prober 1 according to the first embodiment are designated by the same reference numerals in FIG. 8, and therefore, redundant description will be omitted below. This prober 1 differs from the previous embodiments in that it further includes a pressure adjustment mechanism 60 for adjusting the pressure of the coolant. Changing the pressure of the coolant changes the saturation temperature of the coolant, thereby enabling control of the boiling of the coolant.

[0038] For example, before starting a test using the tester 30, the pressure is adjusted by the pressure adjustment mechanism 60 so that the saturated temperature of the coolant is approximately equal to the test temperature (set value) T. If the test heat generation amount (actual measurement value) is Qt and the total thermal resistance (design value) between the wafer W and the holding surface 12 (heat transfer surface) is R, the temperature of the holding surface 12 (heat transfer surface) is T-Q ｔ It becomes R. Before the test starts, it is Q.ｔ = 0, the pressure adjustment mechanism 60 is adjusted so that the saturation temperature of the coolant is approximately equal to the test temperature T. At this time, the temperature of the coolant is T-Q ｔ R-ΔT ｓａｔ The test temperature T is maintained by the heater 13. ｓａｔ can be determined from a boiling curve (see FIG. 9) previously obtained according to the test heat release amount Qt.

[0039] On the other hand, after the test starts, the pressure in the coolant flow path 14 is reduced by adjusting the pressure adjustment mechanism 60, and the saturation temperature of the coolant is set to T′=T−Q, which is smaller than T. ｔ R-ΔT ｓａｔ This allows the coolant to begin boiling. When the test begins, the wafer W begins to generate heat based on the test signal. However, as the coolant begins to boil, its heat absorption capacity increases, allowing it to absorb the temperature increase corresponding to the test signal. As the saturation temperature of the coolant drops, the coolant begins to boil on the heat transfer surface (holding surface 12), absorbing heat in accordance with the amount of heat generated by the wafer W. Accurate control of pressure by the pressure adjustment mechanism 60 and the associated change in saturation temperature are not required. Excessive heat absorption can be compensated for by increasing the heat generated by the heater 13. The operation of the pressure adjustment mechanism 60 can also be varied based on the pressure detected by the pressure sensors PS1 and PS2 or the amount of power applied to the wafer W by the tester 30. Feedback of the actual pressure value of the coolant in the coolant flow path 14 and the amount of heat generated by the wafer W allows for more precise pressure adjustment by the pressure adjustment mechanism 60.

[0040] The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0041] REFERENCE SIGNS LIST 1...prober 10...chuck 11...chuck body 12...holding surface 13, 13', 43...heater 14...coolant flow path 15...peltier element 20...probe card 30...tester 31...tester body 32...interface 40...coolant supply unit 41...supply path 42...discharge path 50...control unit 60...pressure adjustment mechanism Ah...heating area PS1, PS2...pressure sensor PSi, PSo, PS1...temperature sensor W...wafer

Claims

1. A prober for inspecting the electrical characteristics of an object to be inspected, comprising: a chuck portion for adsorbing the object to be inspected; and a cooling liquid flow path configured to be able to control the temperature of the surface of the chuck portion and capable of supplying a cooling liquid by circulating it in a boiling state on at least the heat transfer surface of the chuck portion.

2. The prober according to claim 1, further comprising a temperature adjusting section for adjusting the temperature of said chuck section.

3. The prober according to claim 2, further comprising: a temperature measuring unit that measures the temperature of the surface of said chuck unit; and a temperature control unit that controls said temperature adjusting unit in accordance with the measurement result of said temperature measuring unit.

4. The prober according to claim 3, wherein said temperature control section controls said temperature adjustment section based on at least one of the amount of heat generated by said test object during testing and the amount of heat absorbed by said cooling liquid.

5. The prober according to claim 4, wherein at least one of the amount of heat generated and the amount of heat absorbed is measured by a heat flux sensor.

6. The prober according to claim 4, wherein the amount of heat generated is calculated from the power applied to the object under test.

7. The prober according to claim 4, wherein the temperature measurement unit includes a coolant temperature measurement unit that measures the temperature of the coolant flow path and a heat transfer surface temperature measurement unit that measures the temperature of the heat transfer surface, and further comprises a pressure measurement unit installed in the coolant flow path, and the amount of heat absorption is calculated using a value measured by the coolant temperature measurement unit, the heat transfer surface temperature measurement unit, or the pressure measurement unit.

8. The prober according to any one of claims 2 to 7, wherein the temperature adjustment section is divided into a plurality of sections and provided on the surface of the chuck section.

9. The prober according to any one of claims 1 to 7, wherein the cooling liquid is a liquid whose main component is water.

10. The prober according to claim 1, further comprising a pressure adjusting mechanism for adjusting the pressure in the cooling liquid flow path to control the boiling state of the cooling liquid.

11. The prober according to claim 10, further comprising: a pressure measuring unit that measures the pressure in the cooling liquid flow path; and a pressure adjusting mechanism control unit that controls the pressure adjusting mechanism in accordance with the measurement result of the pressure measuring unit.

12. The prober according to claim 10, further comprising a temperature adjusting section for adjusting the temperature of said chuck section.

13. The prober according to claim 12, further comprising: a temperature measuring unit that measures the temperature of the surface of said chuck unit; and a temperature control unit that controls said temperature adjusting unit in accordance with the measurement result of said temperature measuring unit.

14. The prober according to claim 13, further comprising a pressure measuring unit that measures the pressure of the cooling liquid flow path, wherein the temperature control unit controls the temperature adjustment unit in accordance with the measurement results of the temperature measuring unit and the pressure measuring unit.

15. The prober according to claim 14, wherein the pressure adjustment mechanism is controlled in accordance with the measurement result of the pressure measurement unit and the amount of heat generated during testing of the test object.

16. A method for controlling a prober that inspects the electrical characteristics of an object to be inspected, comprising the steps of: adsorbing the object to be inspected to a chuck portion; absorbing heat generated in the chuck portion by circulating and supplying a coolant in a boiling state on at least the heat transfer surface of the chuck portion in a coolant flow path of the chuck portion; and heating the chuck portion with a heater provided inside the chuck portion.

17. The control method according to claim 16, further comprising the step of measuring the pressure in the cooling liquid flow path, and controlling the heater in accordance with the measurement results of the temperature of the surface of the chuck portion and the pressure.

18. The method of claim 16, further comprising the step of controlling the boiling state of the coolant by adjusting the pressure in the coolant flow path.

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