JP7032644B2 - Prober cooling system - Google Patents

Description

The present invention relates to a prober for electrically inspecting a plurality of chips formed on a semiconductor wafer, and particularly to a cooling system for cooling a wafer chuck.

In the semiconductor manufacturing process, various processes are applied to a semiconductor wafer to form a plurality of chips having a device. Each chip is inspected for electrical characteristics, then separated by a dicer, and then fixed to a lead frame or the like for assembly. Inspection of electrical properties is carried out by a prober equipped with a tester. The prober holds the wafer in the wafer chuck and brings the probe into contact with the electrode pads of each chip. The tester supplies power and various test signals to the chip from the terminal connected to the probe, and analyzes the signals output to the electrodes of the chip to confirm whether it operates normally.

Commercialized devices are used in a wide range of applications, for example, in a low temperature environment of −55 ° C. or lower, or in a high temperature environment of 200 ° C. or higher. Therefore, the prober is required to be able to perform inspections in such a high and low temperature environment. Therefore, a cooling system such as a chiller mechanism or a heating system such as a heater mechanism is mounted on the prober, and the wafer chuck is cooled or heated to a set temperature by these cooling systems or heating systems under the above-mentioned high and low temperature environment. (See, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2008-311483

In recent years, in wafer inspection by a prober, the number of chips to be measured at the same time is increasing in order to shorten the measurement time and reduce the test cost. At that time, even a device such as a DRAM (Dynamic Random Access Memory) or a flash memory having a small calorific value with one chip has a large calorific value due to an increase in the number of simultaneous measurements. In this case, the wafer chuck is heated by the heat generated by the device generated during the wafer inspection to raise the temperature.

For a cooling system that requires, for example, −40 ° C. as the inspection temperature in the low temperature range of the device (the temperature set by the cooling system for the wafer chuck), a refrigerator designed for low temperature is used. However, if the coolant heated to, for example, 45 ° C. or higher by the wafer chuck is returned to the refrigerator, the refrigerator oil may be adversely affected (for example, deteriorated), or the refrigerator may be affected by a heat cycle having a large temperature difference from high temperature to low temperature. It will be damaged. Therefore, in the conventional cooling system, the cooling liquid cannot be used in a high temperature region where the cooling liquid is heated to, for example, 45 ° C. or higher by the wafer chuck.

Due to such circumstances, in the conventional cooling system, the cooling capacity of the wafer chuck is lowered in the high temperature region where the coolant cannot be used. Therefore, especially when inspecting a device having a large calorific value, there is a problem that the temperature of the wafer chuck exceeds the inspection temperature required for the inspection.

On the other hand, it is conceivable to control the temperature of the wafer chuck in a wide temperature range by using air instead of the coolant. However, since air has a small heat capacity, it has a drawback that the cooling capacity in a low temperature range is inferior to that of a cooling system using a coolant.

That is, none of the conventional probers have an effective cooling capacity in a wide temperature range from a low temperature range to a high temperature range.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a prober cooling system having an effective cooling capacity in a wide temperature range from a low temperature range to a high temperature range.

In order to achieve the object of the present invention, the prober of the present invention includes a wafer chuck for holding a wafer on which a chip is formed, a refrigerator for cooling the coolant, a coolant tank connected to the refrigerator, and refrigeration. The first flow path connecting the machine and the wafer chuck, the second flow path communicating with the first flow path via the wafer chuck and connecting the wafer chuck and the coolant tank, the first flow path and the second flow path. A heat exchanger attached to the flow path and exchanging heat between the coolant flowing through the first flow path and the coolant flowing through the second flow path, and a heat exchanger and a refrigerator provided in the first flow path. A heater arranged between the two, a flow rate adjusting valve provided between the heat exchanger and the refrigerator provided in the first flow path, a temperature detector for detecting the temperature of the wafer chuck, and temperature detection. It is provided with a control unit that adjusts the opening degree of the flow rate adjusting valve based on the temperature detected by the unit and controls the flow rate of the coolant supplied from the refrigerator to the wafer chuck.

In one embodiment of the present invention, the flow rate adjusting valve is arranged on the refrigerator side of the heater in the first flow path, and the flow rate adjusting valve is a three-way valve that branches the coolant to the coolant tank on the first flow path. Is preferable.

In one embodiment of the present invention, the wafer chuck is provided with a chuck heater, and the control unit adjusts the opening degree of the flow rate adjusting valve based on the heater output of the chuck heater and the temperature detected by the temperature detection unit. It is preferable to control the flow rate of the coolant supplied from the refrigerator to the wafer chuck.

According to the present invention, it has an effective cooling capacity in a wide temperature range from a low temperature range to a high temperature range.

Block diagram showing the configuration of the prober to which the cooling system of the embodiment is applied. Functional block diagram showing the configuration of the chuck heater control system of the embodiment Functional block diagram showing the configuration of the chiller control system of the embodiment Block diagram showing the configuration of the cooling system of another embodiment

Hereinafter, preferred embodiments of the prober cooling system according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a configuration of a prober 10 to which a cooling system of an embodiment is applied.

First, the prober 10 will be described. The prober 10 includes a probe card 14 having a probe 12 contacted with an electrode of a chip to be inspected, and a tester 16. The tester 16 has a tester main body 18 and an interface 20 for electrically connecting the terminals of the tester main body 18 and the terminals of the probe card 14. The tester 16 supplies power and various test signals to the chip from the terminal connected to the probe 12, and analyzes the signals output to the electrodes of the chip to confirm whether the chip operates normally.

Next, the cooling system of the prober 10 will be described. The cooling system of the embodiment includes a wafer chuck 22 for holding the wafer W, a refrigerator 24 for cooling the coolant, and a coolant tank 28 connected to the refrigerator 24 via a pump 26. .. Further, the cooling system has a first flow path 30 and a second flow path 32. The first flow path 30 is a flow path connecting the refrigerator 24 and the wafer chuck 22, and the second flow path 32 is a flow path connecting the wafer chuck 22 and the coolant tank 28. The first flow path 30 and the second flow path 32 communicate with each other via the refrigerant flow path 23 provided in the wafer chuck 22. According to the cooling system of the embodiment configured as described above, the cooling liquid from the refrigerator 24 is passed through the first flow path 30, the refrigerant flow path 23, the second flow path 32, and the cooling liquid tank 28 to the refrigerator 24. It has a circulation flow path that circulates in the air. Further, a temperature detection unit 48 composed of a temperature sensor is attached to the wafer chuck 22. Further, the wafer chuck 22 has a built-in chuck heater 50.

Further, the cooling system of the embodiment has a heat exchanger 34. The heat exchanger 34 is attached to the first flow path 30 and the second flow path 32, and exchanges heat between the cooling liquid flowing through the first flow path 30 and the cooling liquid flowing through the second flow path 32. .. As the heat exchanger 34, a structure in which the first flow path 30 and the second flow path 32 are brought into contact with each other at a predetermined length and the contact portion is held by a casing via a heat insulating material can be exemplified. According to the heat exchanger 34 configured as described above, for example, the low-temperature coolant flowing through the first flow path 30 is heated by the high-temperature coolant flowing through the second flow path and supplied to the wafer chuck 22. At the same time, the high-temperature coolant flowing through the second flow path 32 can be cooled by the low-temperature coolant flowing through the first flow path and returned to the coolant tank 28.

Further, the cooling system of the embodiment includes a three-way valve 36 and a heater 38. The three-way valve 36 is provided in the first flow path 30 and is arranged between the refrigerator 24 and the heat exchanger 34. Similarly, the heater 38 is provided in the first flow path 30, and is also arranged between the refrigerator 24 and the heat exchanger 34.

In the cooling system shown in FIG. 1, the three-way valve 36 is arranged on the refrigerator 24 side of the heater 38. That is, the first port 36A of the three-way valve 36 is connected to the refrigerator 24 side, and the second port 36B of the three-way valve 36 is connected to the heater 38 side. Further, the third port 36C of the three-way valve 36 is connected to the coolant tank 28 via the third flow path 40. The three-way valve 36 is a preferable example of the flow rate adjusting valve of the present invention, and the three-way valve 36 can branch the coolant to the coolant tank 28 on the first flow path 30.

FIG. 2 is a functional block diagram of a chuck heater control system 42 that heats the wafer chuck 22.

The chuck heater control system 42 shown in FIG. 2 is composed of each arithmetic processing circuit including a CPU (central processing unit) (not shown) and a memory such as a ROM (Read Only Memory) or a RAM (Random Access Memory). By executing the program stored in the memory by the CPU, the functions of each part of the chuck heater control system 42 are realized. As shown in FIG. 2, the chuck heater control system 42 functions as a temperature setting unit 44, a heater control unit 46, and a memory unit 52.

The temperature setting unit 44 sets the set temperature T (° C.) of the wafer chuck 22 according to the information input via the input device such as a keyboard. This set temperature T (° C.) is output from the temperature setting unit 44 to the heater control unit 46.

The heater control unit 46 controls the temperature (° C.) of the wafer chuck 22 based on the set temperature T (° C.) of the wafer chuck 22. Specifically, the heater output H (W) of the chuck heater 50 is controlled so that the temperature (° C.) of the wafer chuck 22 detected by the temperature detection unit 48 becomes the set temperature T (° C.) of the wafer chuck 22. ..

The memory unit 52 stores a control constant map for feedback-controlling the heater output H (W) according to the set temperature T (° C.) of the wafer chuck 22. This control constant map is created, for example, by obtaining a control constant for each set temperature T (° C.) by an experiment or the like in advance.

According to the chuck heater control system 42 configured in this way, when the set temperature T (° C.) of the wafer chuck 22 is given to the heater control unit 46 from the temperature setting unit 44, the heater control unit 46 of the memory unit 52 The corresponding control constant is read from the control constant map, and the value thereof is used for feedback control of the chuck heater 50. Then, the heater control unit 46 feedback-controls the heater output H (W) of the chuck heater 50 so that the temperature (° C.) of the wafer chuck 22 detected by the temperature detection unit 48 becomes the set temperature T (° C.). do. Thereby, according to the chuck heater control system 42 of the embodiment, the temperature (° C.) of the wafer chuck 22 can be controlled to the set temperature T (° C.).

FIG. 3 is a functional block diagram of the chiller control system 54.

The chiller control system 54 shown in FIG. 3 is composed of each arithmetic processing circuit including a CPU (central processing unit) (not shown) and a memory such as a ROM (Read Only Memory) or a RAM (Random Access Memory). When the program stored in the CPU is executed by the CPU, it functions as a three-way valve control unit 56 and a memory unit 58.

The three-way valve control unit 56 adjusts the opening degree V (%) of the three-way valve 36 based on the temperature (° C.) of the wafer chuck 22 and the heater output H (W) given from the heater control unit 46 of the chuck heater control system 42. Then, the supply amount of the coolant to the wafer chuck 22 is controlled.

In the memory unit 58, data of the opening degree V (%) of the three-way valve 36 corresponding to the temperature (° C.) of the wafer chuck 22 and the heater output H (W) is stored for each temperature (° C.) and the heater output H (W). It is stored in advance in. That is, the memory unit 58 has a conversion map in which the relationship between the temperature (° C.), the heater output H (W), and the opening degree V (%) is associated with each other. This conversion map is created, for example, by obtaining the relationship between the temperature (° C.), the heater output H (W), and the opening degree V (%) by an experiment or the like in advance.

According to the chiller control system 54 configured in this way, the temperature (° C.) of the wafer chuck 22 and the heater output H (W) at that time are transmitted from the heater control unit 46 of the chuck heater control system 42 to the three-way valve control unit 56. ) Is given, the three-way valve control unit 56 reads the corresponding opening V (%) from the conversion map of the memory unit 58, and adjusts the opening V (%) of the three-way valve 36. Thereby, according to the cooling system of the embodiment, the flow rate of the coolant supplied to the wafer chuck 22 can be controlled to the flow rate according to the temperature (° C.) of the wafer chuck 22 and the heater output H (W). ..

Therefore, according to the cooling system of the embodiment, the chiller control system 54 is a three-way valve based on the temperature (° C.) of the wafer chuck 22 that controls the wafer chuck 22 to the set temperature T (° C.) and the heater output H (W). Since the opening degree V (%) of 36 is adjusted, it is possible to supply the wafer chuck 22 with the coolant having a flow rate corresponding to the set temperature T (° C.) of the wafer chuck 22.

By the way, in the cooling system of the embodiment, during operation in a high temperature region, the high temperature cooling liquid flowing from the wafer chuck 22 to the second flow path 32 flows into the first flow path 30 while passing through the heat exchanger 34. Heat exchange is performed with the flowing low-temperature coolant to cool it, and then it is returned to the coolant tank 28 via the second flow path 32. As a result, the coolant returned to the coolant tank 28 has a lower temperature than the coolant returned to the coolant tank 28 without going through the heat exchanger 34, so that the coolant is cooled from the wafer chuck 22. The coolant returned to the tank 28 can be stably supplied to the refrigerator 24.

Therefore, according to the cooling system of the embodiment, by providing the above heat exchanger 34, the coolant can be used even during operation in a high temperature region, so that a cooling capacity in a high temperature region can be obtained. can.

Further, according to the cooling system of the embodiment, by providing the above heat exchanger 34, the low temperature coolant flowing through the first flow path 30 can be brought to near the temperature required for the wafer chuck 22 by the heat exchanger 34. Since the temperature can be raised, the heater output of the heater 38 can be reduced.

As described above, according to the cooling system of the embodiment, the circulation flow path (first flow path 30 and second flow path 32) for circulating the coolant between the wafer chuck 22, the refrigerator 24, and the coolant tank 28 is provided. A heat exchanger 34, a heater 38, and a flow rate adjusting valve (three-way valve 36) are provided, and the opening degree of the flow rate adjusting valve (three-way valve 36) is set according to the temperature of the wafer chuck 22 detected by the temperature detection unit 48. To control the flow rate of the coolant supplied from the refrigerator 24 to the wafer chuck 22 by adjusting the above, even if the set temperature is in the low temperature range where it is difficult to obtain sufficient cooling capacity with air. Further, the wafer chuck 22 can be satisfactorily cooled even at a set temperature in a high temperature range where it is difficult to use the refrigerator.

Further, according to the cooling system of the embodiment configured as described above, it is possible to apply a cooling liquid having fluidity at, for example, about −50 ° C. and having a boiling point of 160 ° C. or higher, and the wafer chuck 22 can be applied. Even in a wide temperature range of −40 ° C. or higher and 150 ° C. or lower, sufficient cooling capacity can be exhibited.

Therefore, according to the cooling system of the embodiment, it has an effective cooling capacity in a wide temperature range from a low temperature range to a high temperature range.

Further, according to the cooling system of the embodiment, at least a part of the cooling liquid cooled by the refrigerator 24 by the three-way valve 36 provided in the middle of the first flow path 30 during operation in a high temperature region. It is possible to return to the coolant tank 28 via the third flow path 40 without heating with the heater 38. As a result, the coolant returned from the heat exchanger 34 to the coolant tank 28 via the second flow path 32 can be further cooled by some of the above-mentioned coolants, which is more effective. It is possible to circulate the coolant.

FIG. 4 is a block diagram showing a configuration in which the cooling system of the present invention is applied to a two-system cooling system including two wafer chucks 22A and 22B. In FIG. 4, the components common to those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.

The cooling system shown in FIG. 4 can circulate the coolant to the two wafer chucks 22A and 22B by using the refrigerator 24, the pump 26, the coolant tank 28, and the heater 38. It is a two-system cooling system.

According to the cooling system shown in FIG. 4, the first flow path 30 is branched into two branch flow paths 30A and 30B with the branch portion P as a branch point. The heater 38 is arranged on the refrigerator 24 side of the branch portion P in the first flow path 30.

One branch flow path 30A is a flow path connecting the branch portion P and the wafer chuck 22A, and a second flow path 32A is connected to the branch flow path 30A via the refrigerant flow path 23A of the wafer chuck 22A. Has been done. The second flow path 32A is a flow path connecting the wafer chuck 22A and the coolant tank 28. Further, a heat exchanger 34A is attached to the branch flow path 30A and the second flow path 32A, and the heat exchanger 34A includes a cooling liquid flowing through the branch flow path 30A and a cooling liquid flowing through the second flow path 32A. Heat exchange between. Further, in the branch flow path 30A, a three-way valve 36A is attached between the heat exchanger 34A and the branch portion P. The three-way valve 36A can branch the coolant on the branch flow path 30A to the coolant tank 28 via the third flow path 40A.

The other branch flow path 30B is a flow path connecting the branch portion P and the wafer chuck 22B, and the second flow path 32B is connected to the branch flow path 30B via the refrigerant flow path 23B of the wafer chuck 22B. Has been done. The second flow path 32B is a flow path connecting the wafer chuck 22B and the coolant tank 28. Further, a heat exchanger 34B is attached to the branch flow path 30B and the second flow path 32B, and the heat exchanger 34B includes a cooling liquid flowing through the branch flow path 30B and a cooling liquid flowing through the second flow path 32B. Heat exchange between. Further, in the branch flow path 30B, a three-way valve 36B is attached between the heat exchanger 34B and the branch portion P. The three-way valve 36B can branch the coolant on the branch flow path 30B to the coolant tank 28 via the third flow path 40B.

The adjustment of the opening V (%) of the three-way valves 36A and 36B is executed based on the chuck heater control system 42 (see FIG. 2) and the chiller control system 54 (FIG. 3). Since it is the same as the adjustment of%), the description is omitted here. Therefore, even in such a two-system cooling system, the wafer chucks 22A and 22B have a good cooling capacity in a wide temperature range from a low temperature range to a high temperature range.

In FIG. 4, two systems of cooling systems are illustrated, but the system is not limited to this, and three or more systems using a refrigerator 24, a pump 26, a coolant tank 28, and a heater 38 are used. The cooling system of the present invention can be applied even if it is a cooling system.

In the cooling system of the embodiment described above, the three-way valve control unit 56 adjusts the opening degree V (%) of the three-way valve 36 based on the temperature (° C.) of the wafer chuck 22 and the heater output H (W). However, it is not limited to this. For example, the three-way valve control unit 56 may adjust the opening degree V (%) of the three-way valve 36 based on the temperature (° C.) of the wafer chuck 22.

Further, in the cooling system of the embodiment, the three-way valve 36 is exemplified as the flow rate adjusting valve of the present invention, but the valve is not limited to this, and any valve capable of adjusting the flow rate of the coolant supplied to the wafer chuck 22 is applicable. can do.

10 ... prober, 12 ... probe, 14 ... probe card, 16 ... tester, 18 ... tester body, 20 ... interface, 22 ... wafer chuck, 23 ... refrigerant flow path, 24 ... refrigerator, 26 ... pump, 28 ... coolant Tank, 30 ... 1st flow path, 30A, 30B ... Branch flow path, 32, 32A, 32B ... 2nd flow path, 34, 34A, 34B ... Heat exchanger, 36, 36A, 36B ... Three-way valve, 36 ... Heater , 40, 40A, 40B ... Third flow path, 42 ... Chuck heater control system, 44 ... Temperature setting unit, 46 ... Heater control unit, 48 ... Temperature detection unit, 50 ... Chuck heater, 52 ... Memory unit, 54 ... Chiller Control system, 56 ... Three-way valve control unit, 58 ... Memory unit

Claims (3)

A wafer chuck that holds the wafer and
A refrigerator that cools the coolant,
The coolant tank connected to the refrigerator and
A first flow path connecting the refrigerator and the wafer chuck,
A second flow path that communicates with the first flow path via the wafer chuck and connects the wafer chuck and the coolant tank.
A heat exchanger attached to the first flow path and the second flow path and exchanging heat between the cooling liquid flowing through the first flow path and the cooling liquid flowing through the second flow path.
A heater provided in the first flow path and arranged between the heat exchanger and the refrigerator, and
A flow rate adjusting valve provided in the first flow path and arranged between the heat exchanger and the refrigerator,
A temperature detection unit that detects the temperature of the wafer chuck and
A control unit that adjusts the opening degree of the flow rate adjusting valve based on the temperature detected by the temperature detection unit to control the flow rate of the coolant supplied from the refrigerator to the wafer chuck.
Prober cooling system. The flow rate adjusting valve is arranged on the refrigerator side of the heater in the first flow path.
The cooling system for a prober according to claim 1, wherein the flow rate adjusting valve is a three-way valve that branches a coolant to the coolant tank on the first flow path. The wafer chuck is provided with a chuck heater.
The prober cooling system according to claim 1 or 2, wherein the control unit adjusts the opening degree of the flow rate adjusting valve based on the heater output of the chuck heater and the temperature detected by the temperature detection unit.

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