JP4947949B2 - Prober - Google Patents

Description

  The present invention relates to a prober for connecting a tester terminal to an electrode pad of a semiconductor chip in order to perform electrical inspection of a plurality of semiconductor chips (dies) formed on a semiconductor wafer.

  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 that combines a prober and a tester. The prober fixes the wafer to 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.

  FIG. 1 is a diagram showing a schematic configuration of a wafer test system. The wafer test system includes a prober 10 and a tester 30. 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 stage 18, needle position detection camera 19 for detecting the position of the probe, support columns 20 and 21, head stage 22, wafer alignment camera 23 provided on the support column 21, It has the card holder 24 provided in the head stage 22, the probe card 25 attached to the card holder 24, and the covers 27 and 28 which cover the circumference | surroundings of a prober. 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 stage 18 in the three-axis direction and the Z-axis direction. It constitutes a moving / rotating mechanism that rotates around. In some cases, the Z-axis moving unit 15 and the θ-rotating unit 17 are shared to form a Zθ-moving unit, the Zθ-moving unit supports the wafer stage 18, and the needle position detection camera 19 is provided on the X-axis moving table 14. At this time, the hand position detection camera 19 has an autofocus function. Since the moving / rotating mechanism is widely known, the description thereof is omitted here. The probe card 25 has a probe 26 arranged according to the electrode arrangement of the device to be inspected, and is exchanged according to the device to be inspected. The needle position detection camera 19 detects the arrangement and height position of the probe, and the wafer alignment camera 23 detects the position of the electrode pad of the semiconductor chip (die) on the wafer.

  The tester 30 includes a tester body 31 and a contact ring 32 provided on the tester body 31. The probe card 25 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).

  When performing the inspection, the Z-axis moving table 16 is moved so that the needle position detection camera 19 is positioned below the probe 26, and the tip position of the probe 26 is detected by the needle position detection camera 19. The position (X and Y coordinates) of the tip of the probe 26 in the horizontal plane is detected by the coordinates of the camera, and the position in the vertical direction is detected by the focal position of the camera. The detection of the tip position of the probe 26 must be performed whenever the probe card is replaced, and is appropriately performed every time a predetermined number of chips are measured even when the probe card is not replaced. The probe card 25 is usually provided with 700 or more probes 26, and usually the tip positions of specific probes are detected without detecting the tip positions of all the probes 26.

  Next, with the wafer W to be inspected held on the wafer stage 18, the Z-axis moving table 16 is moved so that the wafer W is positioned under the wafer alignment camera 23, 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.

  The prober is described in Patent Documents 1 and 2 and is well known, and thus further explanation is omitted.

  Since a semiconductor device is used under various environmental conditions, it is necessary to perform an electrical inspection under conditions corresponding to the environmental conditions. Therefore, a heater and a chiller mechanism are provided under the wafer W mounting surface of the wafer stage 18 of the prober so that the inspection can be performed in a state where the wafer W is at a high temperature or a low temperature. The temperature range is, for example, a range from −50 ° C. to + 150 ° C. A heat insulating member is provided between a portion of the wafer stage 18 where the heater and chiller mechanism are provided and a portion below the portion so that the temperature can be set efficiently.

  When the temperature of the wafer stage 18 is lowered, condensation occurs on the wafer W and the wafer stage 18. Therefore, Patent Document 1 describes a configuration in which dry air is introduced into a prober to prevent the occurrence of condensation when the wafer stage 18 is cooled. In addition to this, the prober 10 is generally covered with covers 27 and 28 to further prevent dust.

  When changing the temperature of the wafer stage 18, as described above, a heat insulating member is provided between the portion of the wafer stage 18 where the heater and chiller mechanism are provided and the lower portion thereof, so that the wafer W is relatively short. However, the temperature of the portion of the wafer stage 18 is transmitted to the surroundings, and the temperatures of the probe card 25 and the moving / rotating mechanism that supports the wafer stage 18 gradually change.

  FIG. 2 is a graph showing a change in ambient temperature when the heater is controlled to maintain 100 ° C. after the wafer stage 18 is heated to 100 ° C., and the wafer stage 18 is brought to 100 ° C. A shows a change in temperature of the X-axis moving table 14, and B shows a change in temperature of the moving base 12.

  When the temperature of the moving / rotating mechanism changes, the moving and rotating accuracy deteriorates, and when the temperature of the probe card 25 changes, the probe arrangement pitch changes due to expansion or contraction, and the positioning accuracy of the electrode pad and the probe decreases and is accurate. A situation occurs in which an unsuccessful contact cannot be made. In order to prevent such a situation from occurring during the inspection, after the wafer stage 18 and the wafer W reach the inspection temperature, the inspection is started after waiting until the surroundings reach a certain temperature equilibrium state.

  In Patent Document 2, a cover is provided with a shutter and a temperature sensor is provided in the prober. When the temperature is low, the shutter is closed. The structure which prevents that becomes high temperature is described.

JP 2000-294606 A (Overall) JP 2004-172552 A (Overall)

  As described above, in the conventional prober, in order to prevent a decrease in positioning accuracy due to a temperature change during the inspection, after the wafer stage 18 and the wafer W reach the inspection temperature, they wait until the surroundings reach a certain temperature equilibrium state. After that, the inspection was started. However, since it takes a long time to reach the temperature equilibrium state, there is a problem that the throughput of the wafer test system is lowered.

  Further, during the inspection, a plurality of motors provided in the moving / rotating mechanism operate to generate heat and raise the ambient temperature. The degree of heat generation varies depending on the inspection content and is not constant. Therefore, even if the inspection is started after the surroundings are in a certain temperature equilibrium state, there is a problem that the temperature inside the prober changes and the positioning accuracy is lowered.

  The present invention solves such a problem, and an object of the present invention is to realize a prober capable of maintaining high positioning accuracy without lowering throughput even when inspection is performed at high temperature or low temperature.

  In order to achieve the above object, the prober according to the present invention enables the introduction of a temperature-adjusted gas into the prober, and controls the temperature of the introduced gas so that the temperature of the portion other than the wafer stage in the prober does not change.

  That is, the prober of the present invention is a prober for connecting each terminal of a tester to the electrode of the semiconductor device in order to electrically inspect the operation of the semiconductor device formed on the wafer. A stage mechanism that moves and rotates a wafer stage that is housed in the body and holds the wafer, a cover that covers a space formed by the housing, a gas supply source that can adjust the temperature of the gas to be supplied, and the cover A temperature sensor that detects a temperature of at least one location other than the wafer stage among the blower that blows the gas from the gas supply source into the space covered with the housing and the member housed in the housing And a control unit that adjusts the temperature of the gas supplied from the gas supply source and controls the gas supply source so that the temperature detected by the temperature sensor does not change. That.

  According to the present invention, since the temperature of the portion other than the wafer stage that holds the wafer does not change, a decrease in positioning accuracy is reduced.

  In an actual prober experiment, a part other than the wafer stage in the prober shows a change in the same direction although the change is large or small. In general, the Z-axis moving table close to the wafer stage shows a great change, and the Z moving unit 15, the X-axis moving table 14, the probe card and the card holder show the next changes, but the Y-axis moving table, moving base and base The temperature change of the table 11 is small. Further, the portion where the temperature change is large is a portion near the wafer stage, which is close to the space for moving the wafer stage, and is a portion where the temperature is easily changed by introducing a temperature-controlled gas into the probe. The present inventor pays attention to this point, and a portion where the temperature change is large undergoes a large change due to the temperature-controlled gas introduced into the probe, and a portion where the temperature change is small undergoes a small change. It has been found that when the temperature of the X-axis moving table is detected and a temperature-controlled gas is introduced so as to reduce this portion, the temperature change is suppressed in most parts other than the wafer stage.

  For example, when the heater in the wafer stage is heated to raise the temperature of the wafer, and the temperature of the mounting surface of the wafer stage reaches the inspection temperature, the probe position is detected by the needle alignment camera and the electrode by the wafer alignment camera is detected. The position of the pad is detected, and the temperature of the X-axis moving table at that time is detected. And while starting a test | inspection, when the detected temperature rises, the temperature of the gas introduced is reduced. Further, when the temperature rises, the temperature of the gas is further gradually lowered, and when the temperature falls, the temperature of the gas is slightly raised. Such feedback control is performed so that the temperature of the X-axis moving table does not change.

  Of course, the gas introduced into the prober is a dry gas, so that condensation does not occur, and a clean gas is introduced through a filter in order to prevent dust from adhering to the wafer.

  Furthermore, it is desirable to provide an exhaust path for returning the gas discharged from the space covered with the cover to the gas supply source.

  When the electrical operation of the wafer is inspected using the prober of the present invention, even when the wafer is inspected at a high temperature or a low temperature, the throughput is not lowered, and the inspection can be performed with high positioning accuracy.

  FIG. 3 is a diagram showing the overall configuration of the wafer test system according to the embodiment of the present invention. As shown in the figure, the prober 10 of this embodiment is different from the conventional prober of FIG. 1 in that a temperature-controlled gas supply source 41, a blower 42, a gas supply duct 43 into the prober, an exhaust duct 44, The temperature sensor 45 that detects the temperature of the axis moving table 14, the temperature sensor 46 that detects the temperature of the moving base 12, and the temperature of the temperature control gas supply source 41 are controlled based on the temperatures detected by the temperature sensors 45 and 46. And a control unit 47. The gas supplied from the temperature control gas supply source 41 is dry air, but other gases can also be used.

  The temperature control gas supply source 41 includes a heater and a cooler, and can supply a gas having an arbitrary set temperature. The blower 42 blows the temperature-adjusted gas from the temperature control gas supply source 41 into the prober through the supply duct 43. The gas blown into the prober 10 passes through the space inside the prober 10 and returns from the exhaust duct 44 to the temperature control gas supply source 41 again. As shown in the figure, the gas is introduced into a space for moving the Z-axis moving unit 15, the Z-axis moving table 16, the θ rotating unit 17, the needle alignment camera 19, and the wafer stage 18 that support the wafer stage 18. Therefore, it greatly affects the temperatures of the Z-axis moving unit 15, the Z-axis moving table 16, the θ rotating unit 17, the needle positioning camera 19, the probe card 25, the card holder 24, and the like that are directly close to the space.

  For example, a heater (not shown) in the wafer stage 18 is heated to raise the temperature of the wafer, and when the temperature of the mounting surface of the wafer stage reaches the inspection temperature, the probe 26 is moved by the needle alignment camera 19. The position is detected and the position of the electrode pad is detected by the wafer alignment camera 23, and the temperatures of the X-axis moving table 14 and the moving base 12 at that time are detected by the temperature sensors 45 and 46. When the temperature detected by the temperature sensors 45 and 46 rises simultaneously with the start of the inspection, the temperature of the introduced gas is lowered. Further, when the temperature rises, the temperature of the gas is further gradually lowered, and when the temperature falls, the temperature of the gas is slightly raised. Such feedback control is performed so that the temperature of the X-axis moving table does not change. If the temperatures of the X-axis moving base 14 and the moving base 12 show opposite changes, the temperature of the temperature control gas supply source 41 at that time is maintained.

  FIG. 4 shows that in this embodiment, as in the case of FIG. 2, the heater built in the wafer stage 18 is heated so that the wafer stage 18 becomes 100 ° C., and then the heater is maintained so as to maintain 100 ° C. 6 is a graph showing a change in the ambient temperature when the angle is controlled. A shows a change in temperature of the X-axis moving table, and B shows a change in temperature of the moving base 12. As is clear from FIG. 2, it can be seen that the temperature change is greatly reduced. Thereby, for example, when the temperature change as shown in FIG. 2 occurs, the position error is increased by 20 μm at the maximum, but in this embodiment, it is increased by 2 μm at the maximum.

  In the embodiment, the temperatures of the X-axis moving base 14 and the moving base 12 are detected. However, the temperature may be one place, and the temperature of other places such as a card holder and a Z-axis moving base can also be detected.

  The present invention can be applied to any prober that can perform inspection at various inspection temperatures from low temperature to high temperature.

It is a figure which shows the basic composition of the wafer test system which test | inspects the chip | tip on a wafer with a prober and a tester. It is a graph which shows the temperature change of parts other than a wafer stage after heating a wafer stage high temperature in the conventional prober. It is a figure which shows the structure of the wafer test system of the Example of this invention. 6 is a graph showing a temperature change in a portion other than the wafer stage after the wafer stage is heated in the prober of the example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 12 Movement base 14 X-axis movement stand 16 Z-axis movement stand 18 Wafer stage 19 Needle position detection camera 23 Wafer alignment camera 25 Probe card 26 Probe

Claims (2)

In order to electrically inspect the operation of the semiconductor device formed on the wafer, a prober for connecting each terminal of the tester to the electrode of the semiconductor device,
A housing,
A stage mechanism that moves and rotates a wafer stage that is housed in the housing and holds the wafer;
A cover covering a space formed by the housing;
A gas supply source capable of adjusting the temperature of the gas to be supplied;
A blower that blows gas from the gas supply source into the space covered with the cover;
A temperature sensor for detecting the temperature of at least one location of the stage mechanism ;
A prober comprising: a controller that adjusts the temperature of a gas supplied from the gas supply source and controls the gas supply source so that the temperature detected by the temperature sensor does not change.   The prober according to claim 1, further comprising an exhaust path for returning the gas discharged from the space covered with the cover to the gas supply source.

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