JP2007134545A - Prober - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a prober shortening a time required for a change at a time when a set temperature is changed from a high temperature to a low temperature. <P>SOLUTION: The prober connects each terminal for a tester to electrodes for semiconductor devices for inspecting a plurality of the semiconductor devices formed on a wafer W by a tester. The prober has a wafer chuck 18 holding the wafer, and a chiller system cooling the wafer chuck 18 to lower the temperature of the held wafer. In the prober; the chiller system has a cooling-liquid source 28 supplying a cooling liquid, and a chuck cooling-liquid path 27 fitted to cool the wafer chuck. In the prober; the chiller system further has a bypass 41 for the chuck cooling-liquid path, and a circulating path 29 circulating the cooling liquid in the chuck cooling-liquid path and the bypass from the cooling-liquid source. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a prober for connecting a die electrode to a tester in order to electrically inspect a plurality of semiconductor chips (dies) formed on a semiconductor wafer, and in particular, to cool the wafer chuck holding the wafer at a low temperature. It relates to probers that can be tested in the environment.

  In the semiconductor manufacturing process, various processes are performed on a thin disk-shaped semiconductor wafer to form a plurality of chips (dies) each having a semiconductor device (device). Each chip is inspected for electrical characteristics, then separated by a dicer, and then fixed to a lead frame and assembled. The inspection of the electrical characteristics is performed by a wafer test system composed of a prober and a tester. The prober holds the wafer on the stage and brings the probe into contact with the electrode pad of each chip. The tester supplies power and various test signals from the terminals connected to the probe, and analyzes the signals output to the electrodes of the chip with the tester to check whether it operates normally.

  Semiconductor devices are used in a wide range of applications, and there are semiconductor devices (devices) that can be used in low-temperature environments such as -55 ° C and high-temperature environments such as 200 ° C. It is required that the inspection can be performed. Therefore, a wafer temperature adjusting means for changing the surface temperature of the wafer chuck, such as a heater mechanism and a chiller mechanism, is provided below the wafer mounting surface of the wafer chuck that holds the wafer in the prober, and is held on the wafer chuck. The heated wafer is heated or cooled.

  FIG. 1 is a diagram showing a schematic configuration of a wafer test system including a prober having a wafer temperature adjusting means. As shown, the prober 10 includes a base 11, a moving base 12, a Y-axis moving table 13, an X-axis moving table 14, a Z-axis moving unit 15, and a Z-axis moving table provided thereon. 16, θ rotation unit 17, wafer chuck 18, wafer alignment camera 19, support columns 20 and 21, head stage 22, card holder 23 provided on the head stage 22, and probe attached to the card holder 23. Card 24. The probe card 24 is provided with a cantilever type probe 25. The movement base 12, the Y-axis movement table 13, the X-axis movement table 14, the Z-axis movement unit 15, the Z-axis movement table 16, and the θ rotation unit 17 move the wafer chuck 18 in the three-axis direction and the Z-axis direction. A moving / rotating mechanism that rotates around the center is configured. Since the moving / rotating mechanism is widely known, the description thereof is omitted here. The probe card 24 has a probe 25 arranged according to the electrode arrangement of the device to be inspected, and is exchanged according to the device to be inspected. A needle alignment camera 19 for detecting the position of the probe and a cleaning mechanism for cleaning the probe are provided, but are omitted here.

  The tester 30 includes a tester body 31 and a contact ring 32 provided on the tester body 31. The probe card 24 is provided with a terminal connected to each probe, and the contact ring 32 has a spring probe arranged so as to contact the terminal. The tester body 31 is held with respect to the prober 10 by a support mechanism (not shown). The prober 10 performs measurement in cooperation with the tester 30 in the wafer test, but its power supply system and mechanism are independent from the tester body and the test head.

  When performing the inspection, the tip position of the probe 25 is detected by a needle alignment camera (not shown). Next, with the wafer W to be inspected held by the wafer chuck 18, the Z-axis moving table 16 is moved so that the wafer W is positioned under the wafer alignment camera 19, and the electrode pads of the semiconductor chips on the wafer W are moved. The position of is detected. It is not necessary to detect the positions of all the electrode pads of one chip, and the positions of several electrode pads may be detected. Further, it is not necessary to detect the electrode pads of all the chips on the wafer W, and the positions of the electrode pads of several chips are detected.

  After detecting the position of the probe 25 and the position of the electrode on the wafer W, the wafer chuck 18 is rotated by the θ rotating unit 17 so that the arrangement direction of the electrode pads of the chip matches the arrangement direction of the probe 25. Then, after moving so that the electrode pad of the chip to be inspected on the wafer W is positioned below the probe 25, the wafer chuck 18 is raised and the electrode pad is brought into contact with the probe 25. Then, a power source and a test signal are supplied from the tester main body 31 to the electrode via the contact ring 32, and a signal output to the electrode is detected to check whether it operates normally.

  The above is the schematic configuration of the wafer test system. In a prober capable of heating or cooling the wafer chuck and inspecting the held wafer W at a high temperature or a low temperature, a heater 26 and a chuck coolant path 27 are provided in the wafer chuck 18. Is provided. Cooling liquid flows from the cooling liquid source 28 to the chuck cooling liquid path 27 via the circulation path 29, and cools the surface of the wafer chuck 18 that holds the wafer W. Here, a portion constituted by the chuck coolant path 27, the coolant source 28, and the circulation path 29 is referred to as a chiller system. The heater 26 generates heat to heat the surface of the wafer chuck 18 that holds the wafer W.

  In addition, a vacuum path or the like for vacuum-sucking the wafer W is provided in the wafer chuck 18, and various modifications can be made to the arrangement of the heater 26, chuck coolant path 27, and vacuum path in the wafer chuck 18. is there.

  When the inspection is performed with the wafer set at a predetermined set temperature, the heater 26 or the chiller system is operated so that the wafer chuck 18 reaches a predetermined set temperature while the wafer W is held on the wafer chuck 18. The wafer chuck 18 is made of a material such as a metal such as aluminum or copper or a ceramic having good thermal conductivity.

  Since the configuration of the prober and wafer test system described above is widely known, further description is omitted here.

  Further, Patent Document 1 divides the surface of the wafer chuck 11 into a plurality of regions, and provides a temperature adjustment mechanism (heating mechanism and chiller system) and a temperature sensor that can be controlled independently for each region, and detects each temperature sensor. It describes that the temperature adjustment mechanism in each region is controlled based on the measured temperature.

  As described above, the chiller system includes the chuck cooling liquid path 27, the cooling liquid source 28, and the circulation path 29. The cooling liquid source 28 is a part that cools the cooling liquid to a predetermined temperature, and is a heat exchanger. It is a large and heavy part. Such a cooling liquid source 28 cannot be moved and rotated by the moving / rotating mechanism by being disposed close to the wafer chuck 18. Therefore, as shown in FIG. 1, the cooling liquid source 28 is arranged at a distant position and connected by a flexible circulation path 29, but the cooling liquid source 28 is arranged in the moving range of the wafer chuck 18. Since this is not possible, the coolant source 28 needs to be located far away and the circulation path 29 will have a considerable length. Note that the coolant source 28 may be disposed within the housing of the prober 10 or may be disposed outside the housing.

  If the set temperature at the time of inspection is higher than room temperature, it can be adjusted to the set temperature even if only the heater 26 is operated, and if the coolant is circulated through the chuck coolant channel 27, the efficiency is adversely affected. Therefore, when the set temperature is higher than room temperature, the supply of the cooling liquid from the cooling liquid source 28 to the circulation path 29 and the recovery of the cooling liquid from the circulation path 29 to the cooling liquid source 28 are not performed. In this case, even when the operation of the coolant source 28 itself is stopped, the coolant source 28 operates, but the coolant may not be supplied to or recovered from the circulation path 29 in some cases. In any case, since the cooling liquid in the circulation path 29 does not circulate, the temperature of the circulation path 29 and the cooling liquid in the circulation path 29 becomes a temperature close to or higher than the room temperature.

JP 2001-210683 A (Overall)

  When the set temperature at the time of inspection is switched from a temperature higher than the room temperature to a temperature lower than the room temperature, the cooling liquid source 28 starts operation so that the cooling liquid is set to a lower set temperature, and the cooling with the circulation path 29 is performed. Begin supplying and collecting liquid. In this case, as described above, the temperature of the circulation path 29 and the coolant inside thereof is a temperature close to or higher than the room temperature, and further, the temperature of the chuck coolant path 27, the coolant inside thereof, and the temperature of the wafer chuck 18. Is the temperature of the previous test. Therefore, when changing to a low set temperature, it is necessary to set all of the wafer chuck 18, the chuck coolant path 27 and the circulation path 29, and the coolant inside them to a low set temperature. It is necessary to take at least the total heat quantity obtained by multiplying the difference between the temperature before the change and the set temperature by the heat capacity of each part, and the cooling liquid source 28 takes these heat quantities from the cooling liquid. The amount of heat that the coolant source 28 can take per unit time is determined as a cooling capacity. The time until the inspection can be performed after changing the set temperature is obtained by dividing the amount of heat that needs to be taken by the cooling capacity. It will be at least longer than the time obtained.

  The wafer test system is required to improve the throughput, and various improvements such as inspecting a large number of chips (devices) at the same time have been made. Therefore, it is required to reduce the time required for changing the inspection set temperature.

  The present invention solves the above-described problems, and an object thereof is to shorten the time required for changing a preset temperature in a prober.

  In order to achieve the above object, the prober of the present invention provides a bypass path for the chuck coolant path.

  That is, the prober of the present invention is a prober for connecting each terminal of the tester to an electrode of the semiconductor device in order to inspect a plurality of semiconductor devices formed on the wafer with a tester, and holds the wafer. A wafer chuck and a chiller system that cools the wafer chuck and holds the wafer, and the chiller system is provided to cool the wafer chuck. A chuck cooling liquid path, a bypass path of the chuck cooling liquid path, and a circulation path for circulating the cooling liquid from the cooling liquid source to the chuck cooling liquid path and the bypass path.

  The prober of the present invention has a bypass path, and when the wafer chuck is not cooled, that is, when the coolant is not supplied to the chuck coolant path, the wafer can be circulated through the circulation path and the bypass path. The chuck, the chuck coolant path, and the coolant inside thereof are the set temperatures of the previous inspection, but the temperatures of the other circulation paths 29 and the coolant inside thereof can be cooled. Therefore, the amount of heat that must be taken when switching the set temperature for inspection from a temperature higher than room temperature to a temperature lower than room temperature is multiplied by the heat capacity of each part of the wafer chuck, chuck coolant path and the coolant inside. Therefore, it is not necessary to take the circulation path having a longer path length than the conventional example and the amount obtained by multiplying the heat capacity of each part by the cooling liquid in the circulation path, so that the time required for switching the set temperature can be shortened.

  It is desirable that the length from one branch point to the bypass path to the other branch point through the chuck coolant path is as short as possible. This is to reduce the heat capacity of the portion where the temperature is changed as much as possible.

  When the time at which the inspection at a temperature higher than room temperature is completed is known in advance, the cooling liquid from the time before the time required to bring the circulating path, the bypass path and the cooling liquid in the interior to a lower set temperature. Circulation of the cooling liquid from the source to the circulation path and the bypass path may be started. Further, the operation start time of the coolant source may be set in consideration of the operation time of the coolant source. As a result, unnecessary chiller system operations are reduced, and power saving can be achieved.

  According to the present invention, it is possible to shorten the time required for changing the set temperature in the prober from a high temperature above room temperature to a low temperature that requires the chiller system to operate, and to improve the prober throughput. Can do.

  FIG. 2 is a diagram showing a schematic configuration of a chiller system for a prober according to an embodiment of the present invention. The prober of the embodiment has the same configuration as the conventional prober shown in FIG. 1 except for the chiller system. The configuration of the coolant source 28 and the like is the same as that of the conventional example.

  As shown in FIG. 2, in the embodiment, the circulation path 29 is branched at two locations on both sides near the wafer chuck 18, and the branched path forms a bypass path 41. One of the two branched paths passes through the chuck coolant path 27, and valves 42 and 43 are provided on both sides. Valves 44 and 45 are also provided on both sides of the other branched path including the bypass path 41.

  When the set temperature at the time of inspection is higher than room temperature, the valves 42 and 43 are closed, the valves 44 and 45 are opened, and the coolant source 28 circulates the coolant through the circulation path 29 and the bypass path 41. At this time, since the coolant does not circulate through the chuck coolant channel 27, the wafer chuck 18 is not cooled.

  When the set temperature at the time of inspection is lower than room temperature, the valves 42 and 43 are opened, the valves 44 and 45 are closed, and the cooling liquid source 28 circulates the cooling liquid through the circulation path 29 and the chuck cooling liquid path 27. Thereby, the wafer chuck 18 is cooled.

  For example, before the inspection at the low set temperature is performed, when the inspection at the set temperature higher than room temperature is performed for a long time and the time at which the inspection is completed is known in advance, the circulation path from the coolant source 28 29, the circulation of the coolant to the bypass path 41 is stopped, and the circulation path 29 and the bypass path 41 are set to a low set temperature before the predetermined time before the inspection at the high set temperature ends. Let it begin. This predetermined time is calculated from the time required to bring the circulation path 29, the bypass path 41, and the coolant inside thereof to a low set temperature.

  Further, in the above case, the cooling liquid source 28 also stops its operation, and the time required for the cooling liquid source 28 to reach a low set temperature including the internal cooling liquid is cooled by the time added to the above predetermined time. The liquid source 28 may be activated. By performing such control, unnecessary operation of the chiller system is reduced, so that power saving can be achieved.

  In the description of the embodiment, the heater was not mentioned, but it is needless to say that it is desirable to provide a heater in order to perform inspection at a high temperature.

  The present invention can be applied to any prober having a chiller system.

It is a figure which shows schematic structure of a wafer test system provided with the prober which has a wafer temperature adjustment mechanism. It is a figure which shows the structure of the chiller system of the prober of the Example of this invention.

Explanation of symbols

18 Wafer chuck 26 Heater 27 Chuck coolant path 28 Coolant source 29 Circulation path 41 Bypass path 42, 43, 44, 45 Valve W Wafer

Claims (1)

A prober for connecting each terminal of the tester to an electrode of the semiconductor device in order to inspect a plurality of semiconductor devices formed on the wafer with a tester,
A wafer chuck for holding the wafer;
A chiller system that cools the wafer chuck and holds the wafer held at a low temperature, and
The chiller system includes a coolant source for supplying a coolant,
A chuck coolant path provided to cool the wafer chuck;
A bypass path of the chuck coolant path;
A prober comprising: a circulation path for circulating a coolant from the coolant source to the chuck coolant path and the bypass path.

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