JP7132484B2 - Prober cooling system - Google Patents

Description

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

In a semiconductor manufacturing process, a semiconductor wafer is subjected to various processes to form a plurality of chips having devices. Each chip is inspected for electrical characteristics, then cut by a dicer, fixed to a lead frame or the like, and assembled. The inspection of electrical characteristics is performed by a prober equipped with a tester. The prober holds the wafer on a wafer chuck and contacts the electrode pads of each chip with the probes. The tester supplies power and various test signals to the chip from terminals connected to probes, and analyzes the signals output to the electrodes of the chip to confirm normal operation.

The commercialized devices are used in a wide range of applications, and may be used in a low temperature environment of -55°C or below, or in a high temperature environment of 200°C or above. Therefore, the prober is required to be capable of testing in such high and low temperature environments. 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 the cooling system or the heating system, so that the wafer chuck can be operated under the above high-low temperature environment. can be inspected (see Patent Document 1, for example).

JP 2008-311483 A

In recent wafer inspection using a prober, the number of chips to be measured simultaneously 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, which generates a small amount of heat on a single chip, generates a large amount of heat as the number of simultaneous measurements increases. In this case, the wafer chuck is heated by the heat generated by the device during wafer inspection.

For the cooling system, for example, -55°C is required as the inspection temperature in the low temperature range of the device (set temperature of the wafer chuck by the cooling system). of coolant is used. However, if the temperature of the wafer chuck exceeds the boiling point of the cooling liquid, the cooling liquid evaporates and cannot be used. Also, even if the temperature of the wafer chuck is below the boiling point of the cooling liquid, cavitation occurs in the cooling liquid at a temperature near the boiling point, so the cooling liquid cannot be used. In other words, in the conventional cooling system, the cooling liquid cannot be used in a high temperature range where the temperature of the wafer chuck is raised to a temperature near or above the boiling point of the cooling liquid. Such a problem can be solved by replacing the liquid with a liquid having a different boiling point corresponding to the temperature of the wafer chuck.

Due to these circumstances, the conventional cooling system has a lower ability to cool the wafer chuck in a high temperature range where the cooling liquid cannot be used. Therefore, when inspecting a device that generates a large amount of heat, the temperature of the wafer chuck exceeds the inspection temperature required for inspection.

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

In other words, conventional prober cooling systems do not have an effective cooling capacity in a wide temperature range from low temperature to high temperature.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cooling system for a prober which has effective cooling capability in a wide temperature range from low temperature to high temperature.

In order to achieve the object of the present invention, the prober cooling system of the present invention comprises: a wafer chuck for holding a wafer; a supply unit, a high-temperature air supply unit connected to the wafer chuck via a second flow path and supplying air having a temperature higher than normal temperature to the wafer chuck, a temperature setting unit for setting the temperature of the wafer chuck, and a first flow a valve member that opens one of the channel and the second channel and closes the other channel; When the set temperature is lower than the temperature, cooling liquid is supplied to the wafer chuck through the first flow path, and when the set temperature is equal to or higher than the reference temperature, high-temperature air is supplied to the wafer chuck through the second flow path. and a switching unit for switching the valve member.

According to one aspect of the present invention, the high-temperature air supply unit is connected to an air compression unit for compressing room temperature air, to the air compression unit through a third flow path, and to the wafer chuck through a second flow path. a vortex tube connected to separate the compressed air from the air compression section into hot air and cold air and supply the hot air to the wafer chuck.

In one aspect of the present invention, it is preferable that the high-temperature air supply unit includes a temperature adjustment unit that adjusts the temperature of the high-temperature air to a temperature according to the set temperature.

In one aspect of the present invention, the temperature adjustment unit is provided in a fourth flow path connected to the second flow path and the third flow path, and in the fourth flow path, and is connected to the vortex tube via the third flow path. a proportional control valve for proportionally adjusting the amount of compressed air flowing and the amount of compressed air flowing from the third flow path to the second flow path through the fourth flow path; and the fourth flow path to the second flow path. Detects the temperature of the mixed air in which the high-temperature air from the vortex tube and the compressed air flowing to the second flow path through the fourth flow path are mixed. and a controller for controlling the proportional control valve so that the temperature detected by the air temperature detector becomes a temperature corresponding to the set temperature.

In one aspect of the present invention, the high-temperature air supply unit includes a first exhaust passage connected to the wafer chuck to exhaust high-temperature air supplied to the wafer chuck, and a vortex tube to exhaust low-temperature air. It is preferable to include a second exhaust flow path and an exhaust section to which ends of the first exhaust flow path and the second exhaust flow path are connected.

ADVANTAGE OF THE INVENTION According to this invention, it has an effective cooling capability in the wide temperature range from a low temperature range to a high temperature range.

FIG. 2 is a block diagram showing the configuration of a prober to which the cooling system of the embodiment is applied; Block diagram showing an example of the configuration of the coolant supply unit Block diagram showing an example of the configuration of the hot air supply section Flowchart showing the operation when switching from the cooling liquid supply unit to the hot air supply unit Flowchart showing the operation when switching from the high-temperature air supply to the coolant supply

Preferred embodiments of a cooling system for a prober according to the present invention will be described in detail below with reference to the accompanying drawings.

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

First, the prober 10 will be described. The prober 10 comprises a probe card 16 having probes 14 to be brought into contact with electrodes of a chip to be tested, and a tester 30 . The tester 30 has a tester body 32 and an interface 34 that electrically connects the terminals of the tester body 32 and the terminals of the probe card 16 . The tester 30 supplies power and various test signals to the chip from terminals connected to the probes 14 and analyzes the signals output to the electrodes of the chip to confirm whether the chip operates normally.

Next, a cooling system for the prober 10 will be described. The cooling system of the embodiment includes a wafer chuck 12 that holds a wafer W, a cooling liquid supply unit 20 that is connected to the wafer chuck 12 through a first flow path 18 and supplies cooling liquid to the wafer chuck 12, and a wafer chuck. 12 through a second flow path 22 to supply air having a temperature higher than room temperature to the wafer chuck 12; and a switching unit 26 for switching to supply high temperature air to the wafer chuck 12 . The cooling system of the prober 10 also has a temperature setting section 36 for setting the temperature of the wafer chuck 12 .

The wafer chuck 12 is made of a metal such as aluminum or copper, or a material such as ceramic with good thermal conductivity. A coolant channel 28 is provided inside the wafer chuck 12 . When the electromagnetic valve 27 shown in FIG. 3 is switched to the closed side and the electromagnetic valve 49 is switched to the open side by the switching unit 26 described above, the cooling liquid from the cooling liquid supply unit 20 is supplied to the cooling medium flow path 28 first. It becomes possible to supply via 1 channel 18 . As a result, the surface of the wafer chuck 12 is cooled by the cooling liquid in a low temperature range (for example, -55° C. or more and less than 40° C.). When the switching unit 26 switches the solenoid valve 27 shown in FIG. The coolant can be supplied to the coolant channel 28 via the second channel 22 . Thereby, the surface of the wafer chuck 12 is cooled in a high temperature range (for example, 40° C. or more and less than 150° C.) by high temperature air. The solenoid valve 27 and the solenoid valve 49 constitute the valve member of the present invention.

The high-temperature air supply section 24 of the embodiment is a device that cools the wafer chuck 12 whose temperature has risen to a higher temperature than the high-temperature air generated by the high-temperature air supply section 24 in a high-temperature range. A specific configuration of the hot air supply unit 24 (see FIG. 3) will be described later.

FIG. 2 is a block diagram showing an example of the configuration of the coolant supply section 20. As shown in FIG.

As shown in FIG. 2, the coolant supply unit 20 has a pump 40, a tank 42, a cooler 44, and the like. The pump 40 circulates the low-temperature cooling liquid 46 stored in the tank 42 through the first flow path 18 , the coolant flow path 28 of the wafer chuck 12 , the flow path 48 , and the tank 42 in this order, thereby cooling the wafer chuck 12 . Cool in the low temperature range mentioned above. A check valve 41 is attached to the first flow path 18 and an electromagnetic valve 49 is attached to the flow path 48 .

On the other hand, the coolant 46 in the tank 42 is circulated through the flow path 52 , the cooler 44 , the flow path 56 and the tank 42 in this order by the pump 50 , cooled by the cooler 44 and returned to the tank 42 . A flow control valve 54 is attached to the flow path 56, and the temperature of the cooling liquid 46 stored in the tank 42 is adjusted by adjusting the amount of the circulating cooling liquid 46 with the flow control valve 54. .

The cooler 44 is provided with a circulating line 58 for CFC substitute (for example, hydrofluorocarbon). According to this circulation line 58, the alternative Freon is circulated through the compressor (compressor) 60, the flow path 62, the condenser 64, the flow path 66 and the cooler 44 in this order. An expansion valve 68 is attached to the flow path 66 . The CFC substitute supplied to the cooler 44 is heated by the coolant 46 supplied to the cooler 44 and vaporized. At this time, the coolant 46 is cooled by the CFC substitute. The CFC alternative vaporized in the cooler 44 is compressed by the compressor 60 , cooled by the condenser 64 to be liquefied, and then supplied to the cooler 44 via the expansion valve 68 . Although the condenser 64 shown in FIG. 2 is air-cooled by the fan 70, it may be water-cooled.

By the way, when the wafer chuck 12 is heated by the chip during chip inspection by the tester 30 shown in FIG. . That is, if a fluorine-based antifreeze liquid that is fluid even at a low temperature of -55°C is used as the cooling liquid 46, the cooling liquid 46 becomes gaseous at, for example, 76°C (boiling point) and thermally decomposes at 100°C or higher. Therefore, such a low boiling point cooling liquid 46 cannot be used as a refrigerant in a high temperature range.

Therefore, the cooling system of the prober 10 of the embodiment includes a high-temperature air supply section 24 that exhibits cooling capacity in a high temperature range, in addition to the coolant supply section 20 that exhibits cooling capacity in a low temperature range. By configuring the cooling system in this way, the cooling system of the embodiment has effective cooling capacity in a wide temperature range from low temperature to high temperature. The hot air supply unit 24 will be described below.

FIG. 3 is a block diagram showing an example of the configuration of the hot air supply section 24. As shown in FIG. Note that FIG. 3 also shows the check valve 41 and the solenoid valve 49 that constitute the coolant supply unit 20 .

As shown in FIG. 3, the high-temperature air supply unit 24 is connected to an air compression unit (for example, a compressor) 72 for compressing normal temperature air, and is connected to the air compression unit 72 via a third flow path 74. and a vortex tube 76 connected to the chuck 12 via the second flow path 22 . The vortex tube 76 separates the compressed air from the air compression section 72 into high-temperature air and low-temperature air, and supplies the high-temperature air to the wafer chuck 12 side. A check valve 23 is attached to the second flow path 22 .

The vortex tube 76 is a well-known device that separates the compressed air supplied to the main body 80 from the nozzle 78 into cold air and warm air. The compressed air supplied from the nozzle 78 to the main body 80 adiabatically expands inside the main body 80 to become a supersonic or subsonic swirling flow. The enthalpy in the outer periphery of the swirling flow increases, while the enthalpy in the center decreases, so that the air is separated into cold air and warm air. The separated hot air is discharged from the tip of the tube 82 to the second flow path 22 , and the separated cool air is discharged from the exhaust port 84 . The temperature of the warm air discharged from tube 82 can be set between 40° C. and 150° C., depending on operating conditions. Also, the temperature of the cool air can be set to 0° C. or lower. In addition, the third flow path 74 is provided with a regulator 86 for reducing the pressure of the compressed air from the air compression section 72 to a constant pressure, and an electromagnetic valve 88 for blocking the flow path.

The hot air supply section 24 also includes a temperature adjustment section 90 . This temperature adjustment unit 90 has a function of adjusting the temperature of the high-temperature air supplied to the wafer chuck 12 to a temperature corresponding to the set temperature of the wafer chuck 12 . The aforementioned set temperature is the temperature set by the temperature setting unit 36, and is the temperature of the wafer chuck 12 controlled by the cooling system of the embodiment.

The temperature adjustment section 90 includes a fourth flow path 92 , a proportional control valve 94 , an air temperature detection section (eg temperature sensor) 96 and a control section 98 .

The fourth channel 92 is connected to the second channel 22 and the third channel 74 . More specifically, the fourth flow path 92 is connected to the third flow path 74 downstream of the electromagnetic valve 88 and the second flow path 22 between the vortex tube 76 and the check valve 23. there is The fourth flow path 92 is a flow path for allowing part of the compressed air from the air compression section 72 to bypass the vortex tube 76 and flow directly to the second flow path 22 .

A proportional control valve 94 is provided in the fourth flow path. This proportional control valve 94 is a known valve member whose opening degree can be controlled in proportion to the value of the control signal that operates the proportional control valve. The opening of the proportional control valve 94 is controlled by a control signal from the control unit 98 to control the amount of compressed air flowing through the third flow path 74 to the vortex tube 76 and the amount of compressed air flowing from the third flow path 74 to the third flow path. The amount of compressed air flowing to the second flow path 22 via the fourth flow path 92 is proportionally adjusted.

The air temperature detector 96 is provided in the second flow path 22 . More specifically, the air temperature detector 96 is located in the second flow path 22 downstream of the confluence 93 of the fourth flow path 92 with respect to the second flow path 22 and upstream of the check valve 23 . is provided. The air temperature detector 96 detects the temperature of mixed air in which the high-temperature air discharged from the vortex tube 76 and the normal-temperature compressed air flowing through the second flow path 22 through the fourth flow path 92 are mixed. To detect.

The control unit 98 includes an arithmetic processing circuit 100 including a CPU (central processing unit) and a storage medium 102 such as a memory. In the storage medium 102, data of high-temperature air temperature (eg, 97° C.) corresponding to the set temperature (eg, 100° C.) of the wafer chuck 12 is stored in advance for each set temperature. That is, the storage medium 102 has a conversion map in which the relationship between the set temperature of the wafer chuck 12 and the temperature of the high-temperature air is associated.

When the set temperature (for example, 100° C.) of the wafer chuck 12 is set by the temperature setting unit 36, the arithmetic processing circuit 100 stores the high-temperature air temperature (for example, 97° C.) corresponding to the set temperature to the storage medium. 102. Then, the arithmetic processing circuit 100 controls the proportional control valve 94 so that the temperature of the high-temperature air (mixed air) detected by the air temperature detection unit 96 becomes the read high-temperature air temperature (for example, 97° C.). to control the opening of the proportional control valve 94 . That is, the control unit 98 controls the proportional control valve 94 so that the temperature detected by the air temperature detection unit 96 becomes the temperature according to the set temperature. Thereby, according to the temperature adjustment unit 90 of the embodiment, the temperature of the high-temperature air supplied from the vortex tube 76 to the wafer chuck 12 can be adjusted to the temperature according to the set temperature of the wafer chuck 12 .

Additionally, the hot air supply 24 includes a first exhaust passage 104 , a second exhaust passage 106 , and an exhaust chamber 108 . This exhaust chamber 108 is an example of the exhaust section of the present invention.

The first exhaust flow path 104 is a flow path that is connected to the wafer chuck 12 and exhausts high-temperature air supplied to the wafer chuck 12 . The second exhaust flow path 106 is a flow path that is connected to the exhaust port 84 of the vortex tube 76 and exhausts low-temperature air. Each end of the first exhaust channel 104 and the second exhaust channel 106 is connected to the exhaust chamber 108 . Therefore, according to the exhaust system of the high-temperature air supply unit 24 configured in this way, the high-temperature air discharged from the first exhaust passage 104, the low-temperature air discharged from the second exhaust passage 106, can be mixed in the exhaust chamber 108 and exhausted to the outside. By heating the low-temperature air with the high-temperature air and exhausting it to the outside in this way, it is possible to prevent dew condensation on the prober 10 and devices existing in the vicinity of the prober 10 .

Next, an example of the operation of the cooling system configured as described above will be described. In the following description, 40° C. is exemplified as a switching temperature set for switching between the operation of the coolant supply section 20 and the high-temperature air supply section 24 . This switching temperature corresponds to the reference temperature of the present invention. Note that the reference temperature is not limited to 40°C.

FIG. 4 is a flow chart showing an example of the operation when the operation of the cooling system is switched from the coolant supply section 20 to the high-temperature air supply section 24 . According to FIG. 4, when the set temperature of the wafer chuck 12 is set to 100.degree. be. Specifically, dry air is supplied to the first flow path 18, and the coolant 46 accumulated in the first flow path 18, the refrigerant flow path 28, and the flow path 48 is collected in the tank 42 (S20).

3 is switched to the open side and the solenoid valve 49 is switched to the closed side by the switching unit 26 of FIG. is activated (S40). After that, the temperature adjustment unit 90 controls the temperature of the high-temperature air discharged from the vortex tube 76 to a temperature (97° C.) corresponding to the set temperature (100° C.) of the wafer chuck 12 and supplies it to the wafer chuck 12 . (S50), and the wafer chuck 12 is cooled.

Thus, according to the cooling system of the embodiment, the wafer chuck 12 can be well cooled even at a set temperature in the high temperature range of 100° C. where it is difficult to use the cooling liquid 46 with a low boiling point. In addition, since the vortex tube 76 can generate high-temperature air of about 150° C., even if the set temperature of the wafer chuck 12 is about 150° C., the high-temperature air supply unit 24 of the embodiment can handle the set temperature. can do. Furthermore, since air having a temperature higher than normal temperature is used as the cooling medium in the high temperature range, the temperature distribution on the surface of the wafer chuck 12 can be made substantially uniform. As a result, the temperature distribution of the wafer W held by the wafer chuck 12 is also substantially uniform on the surface, so that the chips can be inspected satisfactorily.

FIG. 5 is a flow chart showing an example of the operation when the operation of the cooling system is switched from the hot air supply section 24 to the cooling liquid supply section 20 . According to FIG. 5, when the temperature setting unit 36 sets the temperature of the wafer chuck 12 to, for example, −30° C. (below the reference temperature) (S60), first, the hot air supply unit 24 is stopped (S70). 3 is switched to the closed side and the solenoid valve 49 is switched to the open side by the switching portion 26 of FIG. 1, after which the coolant supply portion 20 is started. (S80). After that, the temperature of the cooling liquid 46 is controlled by the cooling liquid supply unit 20 to a temperature corresponding to the set temperature (less than −30° C.) of the wafer chuck 12, and the cooling liquid 46 is supplied to the wafer chuck 12 (S90). , cools the wafer chuck 12 . The cooling temperature of the coolant 48 can be controlled, for example, by controlling the motor speed of the compressor 60 (see FIG. 2) with an inverter.

As a result, according to the cooling system of the embodiment, the wafer chuck 12 can be well cooled even at a set temperature in the low temperature range of −30° C., at which it is difficult to obtain a sufficient cooling capacity with air. In addition, if a fluorine-based antifreeze liquid that has fluidity even at about -55°C is used as the cooling liquid 46, even if the set temperature of the wafer chuck 12 is -55°C, the high-temperature air supply unit 24 of the embodiment can be used. can correspond to the set temperature.

As described above, according to the cooling system of the prober 10 of the embodiment, it has an effective cooling capacity in a wide temperature range from low temperature range to high temperature range.

In the embodiment, the vortex tube 76 is exemplified as a high-temperature air supply device, but the present invention is not limited to this. For example, a supply device including an electric heater and a blower may be configured so that high-temperature air heated by the electric heater is supplied to the wafer chuck 12 by the blower.

DESCRIPTION OF SYMBOLS 10... Prober, 12... Wafer chuck, 14... Probe, 16... Probe card, 18... First channel, 20... Coolant supply part, 22... Second channel, 23... Check valve, 24... Hot air supply Part 26... Switching part 27... Solenoid valve 28... Refrigerant flow path 30... Tester 32... Tester body 34... Interface 36... Temperature setting part 40... Pump 41... Check valve 42... Tank , 44... Cooler, 46... Coolant, 48... Flow path, 49... Solenoid valve, 50... Pump, 52... Flow path, 54... Flow control valve, 56... Flow path, 58... Circulation line, 60... Compressor, 62... Flow path, 64... Condenser, 66... Flow path, 68... Expansion valve, 70... Fan, 72... Air compressor, 74... Third flow path, 76... Vortex tube, 78... Nozzle, 80... Body, DESCRIPTION OF SYMBOLS 82... Tube, 84... Exhaust port, 86... Regulator, 88... Electromagnetic valve, 90... Temperature control part, 92... Fourth flow path, 94... Proportional control valve, 96... Air temperature detection part, 98... Control part, 100 Arithmetic processing circuit 102 Storage medium 104 First exhaust channel 106 Second exhaust channel 108 Exhaust chamber

Claims (4)

a wafer chuck that holds the wafer;
a cooling liquid supply unit connected to the wafer chuck through a first flow path and supplying cooling liquid to the wafer chuck;
a high-temperature air supply unit connected to the wafer chuck through a second flow path and supplying air having a temperature higher than room temperature to the wafer chuck;
a temperature setting unit for setting the temperature of the wafer chuck;
a valve member that opens one of the first flow path and the second flow path and closes the other flow path;
When the set temperature of the wafer chuck set by the temperature setting unit is lower than a preset reference temperature, the cooling liquid is supplied to the wafer chuck through the first flow path, and the set temperature is set to the a switching unit for switching the valve member so as to supply the high-temperature air to the wafer chuck through the second flow path when the temperature is equal to or higher than a reference temperature;
with
A cooling system for a prober , wherein the high-temperature air supply unit has a temperature adjustment unit that adjusts the temperature of the high-temperature air to a temperature corresponding to the set temperature . The high-temperature air supply section
an air compression unit that compresses normal temperature air;
connected to the air compression part through the third flow path and connected to the wafer chuck through the second flow path, and converts the compressed air from the air compression part into high-temperature air and low-temperature air; a vortex tube that separates and supplies the hot air to the wafer chuck;
2. The prober cooling system of claim 1, comprising: The temperature adjustment unit
a fourth flow path connected to the second flow path and the third flow path;
The amount of the compressed air provided in the fourth flow path and flowing into the vortex tube via the third flow path, and the amount of the compressed air flowing from the third flow path to the second flow path via the fourth flow path a proportional control valve that proportionally regulates the amount of compressed air;
provided in the second flow path on the downstream side of the junction of the fourth flow path with the second flow path, and passing the high-temperature air from the vortex tube through the fourth flow path to the second flow path an air temperature detection unit that detects the temperature of the mixed air mixed with the compressed air flowing through;
a control unit for controlling the proportional control valve so that the temperature detected by the air temperature detection unit becomes a temperature corresponding to the set temperature;
3. The prober cooling system of claim 2 , comprising: The high-temperature air supply section
a first exhaust passage connected to the wafer chuck for exhausting the high-temperature air supplied to the wafer chuck;
a second exhaust passage connected to the vortex tube for exhausting the low-temperature air;
an exhaust section to which respective ends of the first exhaust channel and the second exhaust channel are connected;
4. The prober cooling system according to claim 2 or 3 , comprising:

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