JP2012178599A - Prober and temperature control method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a prober which maintains position accuracy during high temperature inspection without deteriorating through-put.SOLUTION: A prober has: housings 11, 12; a wafer chuck 16 holding a wafer W in which a chip is formed; a card holder 17 holding a probe card 19 having a probe 20; a head stage 13 fixed to the housing and holding the card holder; and a thermal insulation part 18 thermally insulating a connecting part between the head stage 13 and the card holder 17. The prober controls the temperature so that the head stage 13 becomes an atmospheric temperature.

Description

  The present invention relates to a prober used for inspecting a plurality of semiconductor devices (chips) formed on a wafer by a tester and a prober temperature control method, and more particularly to a prober prober temperature control method capable of setting a temperature condition to be inspected. About.

  The semiconductor manufacturing process has a large number of processes, and various inspections are performed in various manufacturing processes in order to guarantee quality and improve yield. For example, when a plurality of chips of a semiconductor device are formed on a semiconductor wafer, electrode pads of the semiconductor device of each chip are connected to a tester, a power source and a test signal are supplied from the tester, and a signal output from the semiconductor device is Wafer level inspection is performed in which a tester is used to electrically inspect whether the device operates normally.

  After wafer level inspection, the wafer is affixed to the frame and cut into individual chips with a dicer. For each chip that has been cut, only chips that have been confirmed to operate normally are packaged in the next assembly process, and defective chips are excluded from the assembly process. Further, the packaged final product is subjected to shipping inspection.

  The wafer level inspection is performed using a prober in which a probe is brought into contact with an electrode pad of each chip on the wafer. The probe is electrically connected to the terminal of the tester, and power and test signals are supplied from the tester to each chip via the probe, and the output signal from each chip is detected by the tester to measure whether it operates normally. .

  The prober includes a housing, a wafer chuck that holds a wafer on which chips are formed, a card holder that holds a probe card having an array of probes, a head stage that is fixed to the housing and holds the card holder, A moving mechanism that is fixed to the housing and moves the wafer chuck. The wafer to be inspected is fixed to the wafer chuck, the position of the electrode pad is detected by an alignment camera, the positional relationship between the probe and the electrode pad is calculated, and the electrode pad moves so as to contact the probe. The positional relationship between the probe and the electrode pad is calibrated by contacting the probe with the electrode pad of the test wafer and measuring the contact trace.

  In recent years, the size of electrode pads has been reduced along with the high integration of semiconductor devices (chips). Further, in order to improve the inspection throughput, multi-probing is performed in which a plurality of sets of probes are provided so that a plurality of chips can be inspected at the same time, and the number of chips to be inspected simultaneously is also increasing. For this reason, the tolerance of alignment for bringing the electrode pad and the probe into contact with each other is small, and it is required to improve the positional accuracy of the movement in the prober.

  In addition, semiconductor devices are required to operate normally under various environmental conditions. Along with this, it is demanded that the wafer level inspection can inspect the temperature conditions according to the specifications of the semiconductor device, that is, the operation at high and low temperatures. In order to perform inspection at a high temperature, a heater is provided in the wafer chuck, and the wafer chuck and the wafer held thereon are heated to a high temperature. In order to perform inspection at a low temperature, a chiller mechanism for cooling the wafer chuck is provided, and the wafer chuck and the wafer held by the chiller mechanism are cooled.

  The prober that enables inspection at a high temperature or low temperature is described in Patent Documents 1 and 2 and is well known, and thus detailed description thereof is omitted.

  As described above, the tolerance for alignment between the electrode pad and the probe is reduced. On the other hand, when the inspection is performed with the wafer at a high temperature or low temperature, the electrode pad and the probe are displaced as the temperature changes. For example, when changing the wafer temperature from a steady temperature to a high temperature, even if the contact is made correctly by measuring the positional relationship between the electrode pad and the probe at the steady temperature and the contact is made correctly when the temperature becomes high That is, there is a problem that the probe cannot contact the outside part of the electrode pad to perform correct inspection.

  In order to prevent the occurrence of such a problem, when measuring at a high temperature, the wafer chuck is heated while the wafer is held on the wafer chuck, and the wafer chuck and the wafer are at a high inspection temperature and are opposed to each other. Wait until the temperature of the probe card, card holder, head stage, etc. is stable and no further displacement occurs, then measure the positional relationship between the electrode pad on the wafer and the probe, and bring the probe into contact with the electrode pad. Perform an inspection. Further, when the inspection is started before the temperature becomes stable, the positional relationship between the electrode pad and the probe is frequently measured after the start to correct the change in the positional relationship. In this way, the change in the positional relationship between the probe and the electrode pad accompanying the temperature change does not affect the inspection.

JP 2001-319953 A JP 2007-101345 A

  However, it takes a very long time for the temperature of the surrounding probe card, card holder, head stage, and the like to stabilize after the wafer chuck and the wafer are heated to high temperatures, resulting in a decrease in throughput. Since an expensive tester is connected to the prober for inspection, a decrease in throughput causes a problem of increased inspection cost.

  Further, the method of frequently measuring the positional relationship between the electrode pad and the probe to correct the positional relationship also measures the positional relationship, so that the throughput is lowered and the same problem as described above is caused.

  An object of the present invention is to realize a prober and a prober temperature control method capable of maintaining positional accuracy during high-temperature inspection without reducing throughput.

  In order to achieve the above object, the prober of the present invention insulates the space between the head stage and the card holder and controls the temperature so that the head stage becomes the ambient temperature.

  That is, the prober of the present invention includes a housing, a wafer chuck that holds a wafer on which a chip is formed, a card holder that holds a probe card that is connected to a terminal of a tester and has a probe that contacts a wafer electrode, A head stage that is fixed to the housing and holds the card holder, and a heat insulating part that insulates the connecting portion between the head stage and the card holder, and the head stage is temperature controlled so as to be at ambient temperature. Features.

  A prober temperature control method according to the present invention includes a housing, a wafer chuck that holds a wafer on which a chip is formed, and a card holder that holds a probe card that is connected to a tester terminal and has a probe that contacts a wafer electrode. A prober temperature control method comprising: a head stage that is fixed to the housing and that holds the card holder; and a heat insulating part that insulates a connection portion between the head stage and the card holder. The temperature is controlled so that

  According to the present invention, the head stage and the card holder are insulated, and the head stage is maintained at the ambient temperature. Therefore, even if the card holder reaches the same high temperature as the inspection temperature, the temperature of the head stage does not change and the position shifts. Is suppressed.

  Since the card holder is heated by the holder heating mechanism, it becomes the same temperature as the wafer inspection temperature in a short time. The same applies to the wafer chuck and the wafer, and the inspection temperature is reached in a short time. Since the probe card has a small heat capacity, it similarly reaches the inspection temperature in a short time. When the wafer chuck, the wafer, the card holder, and the probe card reach the inspection temperature, the head stage is maintained at the ambient temperature, so that the head stage is in a stable state, and there is no displacement due to the temperature change. In this way, a stable state is achieved in a short time, and inspection can be started, so that throughput is improved.

  In the case of a prober that does not perform wafer inspection at a low temperature, it is necessary to newly provide a cooling mechanism. However, a prober that performs wafer inspection at a low temperature has a wafer chuck cooling mechanism in advance and inspects the wafer at a high temperature. In this case, the wafer chuck cooling mechanism is not used. Therefore, it is desirable to use it as a head stage cooling mechanism when inspecting a wafer at a high temperature. Therefore, the cooling mechanism can be switched to cool the wafer chuck, and the temperature control unit switches the cooling mechanism to cool the wafer chuck when the wafer chuck is cooled, and heats the wafer chuck to a predetermined high temperature. Sometimes the cooling mechanism is switched to cool the head stage.

  According to the present invention, it becomes possible to perform wafer level inspection at high temperature with high positional accuracy without reducing the throughput, and the inspection cost can be reduced.

1 is a diagram illustrating an overall configuration of a wafer level inspection system according to an embodiment of the present invention. It is a figure which shows arrangement | positioning of the cooling jacket in a head stage. It is a figure which shows the change of the probe tip position accompanying the temperature change in a prior art example. It is a figure which shows the change of the probe tip position accompanying the temperature change in embodiment.

  FIG. 1 is a diagram showing a schematic configuration of a system for performing wafer level inspection according to an embodiment of the present invention. A system for performing wafer level inspection includes a prober 10 for contacting a probe to an electrode pad of each chip on a wafer, and a power supply and a test signal to each chip for electrical inspection, while being electrically connected to the probe. It comprises a tester 20 that detects output signals from each chip and measures whether they operate normally.

  In FIG. 1, a base 11, a side plate 12, and a head stage 13 constitute a housing of the prober 10. In some cases, an upper plate supported by the side plate 12 is provided, and the head stage 13 is provided on the upper plate. An XY moving mechanism 14 for moving the Z-axis moving / rotating mechanism 15 in a two-dimensional plane is provided on the base 11, and the Z-axis moving / rotating mechanism 15 supports the wafer chuck 16 and moves in the Z-axis direction and also moves in the Z-axis direction. Scoring around the axis. The wafer chuck 16 sucks and fixes the wafer W by vacuum suction or the like. Provided inside the wafer chuck 16 are a heater 31 that heats the wafer chuck 16 to a high temperature, and a cooling jacket 33 that cools the wafer chuck 16 to a low temperature.

  A card holder 17 is fixed to the head stage 13 via a heat insulating portion 18. A probe card 19 having a probe 20 that contacts the electrode pad is replaceably attached to the card holder 17. The probe card 19 is manufactured according to the semiconductor device (chip) to be inspected. The terminals of the tester body 22 constituting the tester 20 are connected to the terminals of the probe card 19 through a large number of connection pins of the card unit 21. As a result, the terminals of the tester main body 22 are electrically connected to the probe 20.

  The head stage 13 is provided with a cooling jacket 34 for cooling the head stage 13. FIG. 2 is a view showing the arrangement of the cooling jacket 34 in the head stage 13. The inside of the circular heat insulating portion 18 is a circular hole, and the card holder 17 is attached and fixed by a fixing member (not shown). The cooling jacket 34 is disposed at four locations around the hole. Reference numeral 35 is a pipe that forms a flow path of the coolant supplied from the chiller device 43 via the valve 44 and is configured to circulate through the two cooling jackets 34.

  Returning to FIG. 1, the card holder 17 is provided with a heater 32 that heats the card holder 17 to raise the temperature. Further, a temperature sensor 51 is provided on the wafer chuck 16, a temperature sensor 52 is provided on the card holder 17, and a temperature sensor 53 is provided on the head stage 13, and detects the temperature at each location.

  A temperature adjustment unit 41, a heater power source 42, a chiller device 43, a valve 44 for switching whether or not the coolant is supplied from the chiller device 43 to the cooling jacket 34, and a chiller attached to the prober 10 inside or outside. And a valve 45 for switching whether or not to supply the coolant from the apparatus 43 to the cooling jacket 33. The temperature adjustment unit 41 takes in the temperature detected by the temperature sensors 51 to 53 and controls the heater power source 42 and the chiller device 43 based on a predetermined sequence and the detected temperature.

  Although not shown, the head stage 13 (or the side plate 12) is provided with a wafer alignment camera that detects the position of the electrode pad of the wafer W, and the wafer chuck 16 has a probe position camera that detects the position of the probe 20. Provided. The relative position between the wafer alignment camera and the probe position camera is calibrated by detecting the trace of the needle attached by bringing the electrode pad that has detected the position into contact with the probe 20 that has detected the position.

  Since the operation of the prober is widely known, further detailed explanation is omitted.

  Hereinafter, the control operation of the temperature adjustment unit 41 in the case of inspection at a high temperature in the prober of the embodiment will be described. The inspection at a low temperature is performed by opening the valve 45 and supplying a cooling liquid to the cooling jacket 33 of the wafer chuck 16 to lower the temperature of the wafer chuck 16 as in the conventional example. At this time, the valve 44 is closed and the cooling liquid is not supplied to the cooling jacket 34. No power is supplied to the heaters 31 and 32, and the heaters 31 and 32 do not operate. Therefore, at the time of low-temperature inspection, it is necessary to wait until the temperatures of the respective parts reach an equilibrium state before starting inspection, or to frequently detect misalignment and perform position correction (calibration operation).

  During the inspection at a high temperature, the valve 45 is closed so that the cooling liquid is not supplied to the cooling jacket 33 of the wafer chuck 16. The heater power supply 42 supplies power to the heaters 31 and 32 to heat them, and based on the temperatures detected by the temperature sensors 51 and 52, the temperature of the wafer chuck 16 and the card holder 17 is set to the inspection temperature (for example, 150 ° C.). Feedback control is performed to change the power to be supplied. At the same time, the coolant is supplied to the cooling jacket 33 of the head stage 13 by opening the valve 44 so as not to change the temperature of the head stage 13 based on the temperature detected by the temperature sensor 53, that is, the atmosphere at the start. Feedback control is performed to maintain the temperature. This control is performed by changing the temperature of the coolant supplied from the chiller device 43 and changing the amount of coolant supplied.

  In the embodiment, the head stage 13 and the card holder 17 are thermally insulated by the heat insulating portion 18 and the head stage 13 is maintained at the ambient temperature. Therefore, even if the card holder 17 becomes high temperature, the temperature of the head stage 13 does not change. In addition, the displacement due to the temperature change of the head stage 13 is suppressed. Since the card holder 17 is heated by the heater 32, the temperature becomes the same as the inspection temperature of the wafer W in a short time. The same applies to the wafer chuck 16 and the wafer W, and since the heating is performed by the heater 31, the inspection temperature is reached in a short time. Since the probe card 19 has a small heat capacity, it similarly reaches the inspection temperature in a short time. When the wafer chuck 16, the wafer W, the card holder 17, and the probe card 19 reach the inspection temperature, the head stage 13 is maintained at the atmospheric temperature, so that the head stage 13 is in a stable state, and there is no displacement due to temperature changes. In this way, it becomes stable in a short time, and inspection can be started. This improves the inspection throughput.

  Here, the case of the conventional example in which the heat insulation part 18, the heater 32, and the cooling jacket 34 are not provided is demonstrated. The wafer chuck 16 is heated by the heater 31 to the inspection temperature, and the wafer W is also brought to the inspection temperature. At this time, the temperature of the probe card 19, the card holder 17, and the head stage 13 also gradually rises due to radiation from the wafer chuck 16 and the wafer W. The temperature rise of the probe card 19 near the wafer chuck 16 and the wafer W is larger than that of the card holder 17, and the temperature rise of the head stage 13 is the slowest. The relative positions of the probe 20 and the electrode pad of the wafer W change as the temperature of each part rises. For example, the head stage 13 supports the card holder 17, and when the head stage 13 expands due to thermal expansion, the positions of the card holder 17 and the probe card 19 change accordingly. Therefore, the position of the probe 20 changes while the temperature changes without the head stage 13 being thermally stabilized. As described above, the temperature rise of the head stage 13 is moderate, and it takes a long time to stabilize.

  FIG. 3 shows a result of measuring a change in the tip position of the probe 20 when the wafer W is set to 200 ° C. in the conventional example. A rhombus indicates a change in position in the X direction, a square indicates a change in position in the Y direction, and a triangle indicates a change in position in the Z direction. From this figure, the position in the X direction changes for about 2 hours and stabilizes at a position shifted by about 20 μm, the position in the Y direction takes 7 hours or more to stabilize at a position shifted by about −60 μm, and the position in the Z direction is It turns out that it changes to a positive direction gradually, after changing to about -70 micrometers for about 1 hour. The change in the Z direction appears as a change in the contact pressure of the probe 20 with the electrode pad, which can be adjusted by detecting the pressure applied to the wafer chuck and changing the position of the wafer chuck in the Z direction. It is not a problem in practical use. The problem is the positional change in the X and Y directions. At present, the size of the electrode pad is about 50 μm on one side, the allowable range of positional deviation is about 20 μm, and in FIG. I needed to do more than that. Therefore, the inspection of the positional relationship between the probe 20 and the electrode pad is frequently performed.

  FIG. 4 shows the result of measuring the change in the tip position of the probe 20 when the wafer W is set to 200 ° C. in the prober of this embodiment. As shown in the figure, the position in the Z direction becomes stable after changing to about −70 μm for about 1 hour, and the change in the position in the X and Y directions is very gradual, and is 20 μm or less at the maximum. Compared to FIG. 3, it can be seen that the change in position in the X and Y directions is very small. Therefore, the inspection can be started as soon as the wafer W reaches the inspection temperature, and the throughput is improved. Even when the allowable range of positional deviation is small, the position change is slow, so the frequency of calibration can be reduced and the throughput is improved.

  As mentioned above, although embodiment of this invention was described, it cannot be overemphasized that various modifications are possible. For example, in the above-described embodiment, a prober capable of performing inspection at a low temperature has been described as an example, and an example in which a chiller device that cools a wafer chuck is also used for cooling a head stage has been described. In the case of a prober dedicated to room temperature and high temperature that does not perform inspection at low temperature, it is necessary to newly install a chiller device.

  The present invention can be applied to any prober that is used when a wafer is inspected and is a prober that inspects a wafer at a high temperature.

DESCRIPTION OF SYMBOLS 13 Head stage 16 Wafer chuck 17 Card holder 18 Heat insulation part 19 Probe card 20 Probe 31 Heater 32 Heater 33 Cooling jacket 34 Cooling jacket 41 Temperature adjustment part 42 Heater power supply 43 Chiller device

Claims (8)

A housing,
A wafer chuck for holding a wafer on which chips are formed;
A card holder for holding a probe card having a probe connected to a terminal of a tester and contacting an electrode of the wafer;
A head stage fixed to the housing and holding the card holder;
A heat insulating part that insulates the connection part between the head stage and the card holder;
A prober characterized in that the head stage is temperature controlled so as to be at ambient temperature. A chuck heating mechanism for heating the wafer chuck;
A holder heating mechanism for heating the card holder;
A cooling mechanism for cooling the head stage,
2. The prober according to claim 1, wherein the chuck heating mechanism, the holder heating mechanism, and the cooling mechanism are temperature controlled.   In the temperature control, when the wafer chuck is heated to a predetermined high temperature by the chuck heating mechanism, the head stage is set to an ambient temperature by the cooling mechanism, and the card holder is set to the predetermined high temperature by the holder heating mechanism. The prober according to claim 2, wherein the prober is controlled to be heated. The cooling mechanism is switchable to cool the wafer chuck;
The temperature control switches the cooling mechanism to cool the wafer chuck when the wafer chuck is cooled, and switches the cooling mechanism to cool the head stage when the wafer chuck is heated to a predetermined high temperature. The prober according to claim 2 or 3, wherein A housing, a wafer chuck for holding a wafer on which a chip is formed, a card holder for holding a probe card connected to a terminal of a tester and contacting a probe of the wafer, and fixed to the housing, A prober temperature control method comprising: a head stage that holds the card holder; and a heat insulating part that insulates a connection portion between the head stage and the card holder,
A prober temperature control method, wherein the head stage controls the temperature so as to reach an ambient temperature.   The prober further includes a chuck heating mechanism that heats the wafer chuck, a holder heating mechanism that heats the card holder, and a cooling mechanism that cools the head stage, and the chuck heating mechanism, the holder heating mechanism, and 6. The prober temperature control method according to claim 5, wherein the temperature of the cooling mechanism is controlled.   When the wafer chuck is heated to a predetermined high temperature by the chuck heating mechanism, the head stage is controlled to the ambient temperature by the cooling mechanism, and the card holder is controlled to be heated to the predetermined high temperature by the holder heating mechanism. 7. The prober temperature control method according to claim 6, wherein: The cooling mechanism is switchable to cool the wafer chuck;
The cooling mechanism is switched to cool the wafer chuck when the wafer chuck is cooled, and the cooling mechanism is switched to cool the head stage when the wafer chuck is heated to a predetermined high temperature. The prober temperature control method according to claim 6 or 7.

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