JP2008311492A - Prober and method of controlling temperature of wafer chuck of prober - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a prober which can be adapted to various inspection conditions and the consumption power of which is reduced, and a method of controlling the temperature of a wafer chuck of the prober. <P>SOLUTION: A prober comprising a wafer chuck and a control unit comprises a cooling means for cooling the surface of the wafer chuck and a heating means for heating the surface of the wafer chuck. When the temperature of the surface of the wafer chuck is lowered, a chiller mechanism is operated so that the temperature is set to a chiller target temperature C lower than a target temperature T and the heating means is operated so as to control the temperature to the target temperature T. When the temperature of the surface of the wafer chuck is controlled to be the target temperature, the control unit detects the change of the surface temperature of the wafer chuck, calculates a variation width, compares the calculated variation width with a difference between the target temperature T and the chiller target temperature C, and changes the chiller target temperature C based on comparison results. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a prober for connecting a die electrode to a tester for electrical inspection of a plurality of semiconductor chips (dies) formed on a semiconductor wafer, and a method for controlling the temperature of the wafer chuck, and more particularly to holding a wafer. The present invention relates to a prober capable of performing inspection with a high temperature and a low temperature ring pole by heating and cooling the surface of the wafer chuck and a temperature control method for the wafer chuck.

  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 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.

  Semiconductor devices are used in a wide range of applications, and there are also semiconductor devices (devices) that are used in low temperature environments such as -60 ° C and high temperature environments such as 200 ° C. It is required that the inspection can be performed. Therefore, a wafer temperature adjusting mechanism for changing the surface temperature of the wafer chuck, such as a heating mechanism (heater) and a cooling mechanism (chiller mechanism), is provided below the wafer placement surface of the wafer chuck that holds the wafer in the prober. The wafer held on the wafer chuck 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 mechanism including a heater and a chiller mechanism. The prober includes a wafer chuck 11 for holding the wafer W, a probe card 17 having a probe 18 made in accordance with the electrode arrangement of a semiconductor chip to be inspected, and a control unit 16. A coolant path 12 and a heater 13 are provided in the wafer chuck 11. A cooling liquid flows from the cooling liquid source 14 to the cooling liquid path 12 via the path 15 to cool the surface of the wafer chuck 11 that holds the wafer W. The heater 13 generates heat to heat the surface of the wafer chuck 11 that holds the wafer W. The controller 16 controls the coolant source 14 and the heater 13 based on the temperature detected by the temperature sensor 19 provided near the surface of the wafer chuck 11, so that the surface of the wafer chuck 11 reaches a desired temperature. Like that. In this example, the heater 13 is provided on the side close to the surface of the wafer chuck 11 and the coolant path 12 is provided below the heater 13. However, the heater 13 may be provided below the coolant path 12. is there. In addition to this, the prober detects a position of the probe, and a triaxial movement / rotation mechanism of the wafer chuck 11 in the X, Y, and Z directions, an alignment camera that detects the arrangement direction of the dies formed on the wafer, and the probe. A needle position detection camera and a housing for housing them are provided, and the probe card 17 is attached to a card holder provided in the housing. Since such components are not directly related to the present invention, illustration is omitted here.

  The tester includes a tester body 21 and a connection portion 22 that electrically connects the terminals of the tester body 21 and the terminals of the probe card 17. The connection part 22 has a connection terminal mechanism using a spring, a so-called spring pin structure. A prober performs measurement in cooperation with a tester in a wafer test, and its power supply system and mechanism are independent from the tester body and the test head.

  In addition, a vacuum path or the like for vacuum-sucking the wafer W is provided in the wafer chuck 11, and there are various modified examples of the arrangement of the coolant path 12, the heater 13, and the vacuum path in the wafer chuck 11. .

  When the wafer is inspected at a predetermined temperature, the controller 16 controls the wafer chuck heater and the chiller mechanism based on the temperature detected by the temperature sensor 19 while holding the wafer W on the wafer chuck 11. The chuck 11 is set to a predetermined temperature. The wafer chuck 11 is made of a material such as a metal such as aluminum or copper or a ceramic having good thermal conductivity.

  The configuration of the prober and wafer test system described above is described in, for example, Patent Document 1 and the like, and the structure of a wafer chuck having a heater and a coolant path is described in Patent Document 2 and the like, and is widely known. Here, further explanation is omitted. Patent Document 3 describes a chiller mechanism of a wafer chuck.

  FIG. 2 is a diagram illustrating a configuration of the chiller mechanism. As shown in FIG. 2, the pump 32 circulates the low-temperature coolant held in the tank 31 in order of the path 33, the coolant path in the wafer chuck 11, the path 34, and the tank 31. Cooling. Here, a line in which the coolant circulates in the order of the pump 32, the path 33, the coolant path in the wafer chuck 11, the path 34, and the tank 31 is referred to as a wafer chuck cooling path. The tank 31 has a substantially hermetically sealed heat insulating structure and is provided with an air path 35 that connects the upper portion of the tank 31 and the outside, so that the space above the tank 31 is open to the atmosphere. Accordingly, the path 34 is connected to the air release portion of the tank 31, and the circulated coolant is output to the air release portion of the tank 31 and collected in the tank 31. The wafer chuck 11 is also provided with a heater, but the illustration is omitted here, and this is the same in the following drawings.

  The coolant in the tank 31 is circulated in the order of the path 43, the cooler 45, the flow rate adjusting valve 42, the path 44, and the tank 31 by the pump 41, cooled by the cooler 45, and returned to the tank 31. By adjusting the amount of the coolant circulated by the flow rate adjustment valve 42, the temperature of the coolant held in the tank 31 is adjusted. Here, the line through which the coolant circulates in the order of the pump 41, the path 43, the cooler 45, the flow rate adjustment valve 42, the path 44, and the tank 31 is referred to as a coolant cooling path.

  The refrigerant 45 is supplied with a substitute CFC through a circulation line in which the CFC circulates in the order of the compressor (compressor) 51, the path 53, the condenser 55, the path 54, the expansion valve 52, and the cooler 45, and is evaporated. The cooler 45 is cooled. The alternative chlorofluorocarbon vaporized by the cooler 45 is compressed by the compressor 51, cooled by the condenser 55 and liquefied, and evaporates by the cooler 45 through the expansion valve 52. The expansion valve 52 may be a capillary (capillary) tube. The condenser 55 is air-cooled by the fan 56, but may be water-cooled.

  When the wafer chuck 11 is cooled, the lower the temperature, the larger the temperature difference from the surroundings, and the temperature of the coolant rises, so that the energy consumed by the chiller mechanism increases accordingly.

  When the wafer is inspected at a predetermined temperature, the control unit 16 controls the cooling and heating mechanism of the wafer based on the temperature detected by the temperature sensor 19 while holding the wafer W on the wafer chuck 11, and the wafer chuck 11 is set to a predetermined temperature. The wafer chuck 11 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.

  When the inspection is performed at a high temperature or a low temperature, only the portion of the wafer chuck 11 is held at a high temperature or a low temperature, so that the temperature of the wafer chuck 11 changes due to a temperature difference from the surroundings. Further, as described above, the temperature of the wafer chuck 11 changes due to the heat generated by the chips accompanying the inspection. Therefore, the control unit 16 controls a heating mechanism such as a chiller mechanism or a heater according to the temperature detected by the temperature sensor 19, but in order to perform accurate temperature control, their response performance (response) becomes a problem. For example, even if the chiller mechanism or the heating mechanism is controlled so that the temperature sensor 19 detects the deviation from the target temperature and immediately corrects the temperature deviation, if the response is slow, it takes a long time to be corrected. In addition, the temperature deviation becomes large during that time, and there is a problem that the target temperature cannot be accurately controlled.

  In general, the heater generates heat immediately when the current is increased, so that the response is relatively fast. However, the chiller mechanism requires time to change the temperature of the cooling liquid in the cooling liquid source 14 and the cooling liquid whose temperature has been changed. Circulates in the coolant path 12 through the path 15 to cool the wafer chuck 11, so the response is very slow.

  Therefore, when inspection is performed under a low temperature condition, the chiller mechanism is operated under a certain condition so that the wafer chuck 11 has a chiller target temperature lower than the target temperature, and then the heater is heated so as to generate the target temperature. is doing. For the temperature change of the wafer chuck, the amount of heat generated by the heater is changed so as to reach the target temperature. The difference between the target temperature and the chiller target temperature is the lower adjustment range. When the inspection is performed under a high temperature condition, the chiller mechanism is not operated, and only the heater is operated to adjust the target temperature.

  FIG. 3 shows a case where the wafer chuck 11 is operated so that the chiller mechanism is operated so that the chiller target temperature C is lower than the target temperature T, and then the heater is heated so as to reach the target temperature. It is a figure which shows the example of a temperature change. When the target temperature T is lower than the room temperature, the chiller target temperature C lower than the target temperature T is determined. When only the chiller mechanism is operated, the chiller mechanism is controlled so that the wafer chuck becomes the chiller target temperature C. To do. Then, the heater is turned on / off so that the temperature of the wafer chuck 11 becomes the target temperature T. As described above, the control of the heating operation by the heater on / off operation has a relatively short response time but still has a certain time delay, so the temperature of the wafer chuck varies as shown in FIG.

JP 2001-210683 A (Overall) JP 2002-124558 A (Overall) JP 2003-148852 A (Overall)

  As described above, when the inspection is performed under a low temperature condition, the temperature control is performed by using the chiller mechanism and the heater together. However, such control is inefficient from the viewpoint of energy consumption. That is, the amount of temperature that is further lowered by the difference between the target temperature and the target temperature of the chiller by the chiller mechanism and the amount that the heater increases the temperature from the chiller target temperature to the target temperature are essentially unnecessary energy consumption.

  Conventionally, a semiconductor manufacturing apparatus such as a prober has been given priority to performance. However, in recent years, a prober is also required to reduce power consumption.

  SUMMARY OF THE INVENTION An object of the present invention is to realize a prober and a prober wafer chuck temperature control method that can cope with various inspection conditions and reduce power consumption.

  In order to achieve the above object, the prober and prober wafer chuck temperature control method according to the present invention determines the chiller target temperature in the same manner as in the prior art at the time of starting the control to lower the wafer chuck temperature, and actually controls the temperature. It is characterized in that a change in the temperature of the wafer chuck during the process is detected and the chiller target temperature is changed in accordance with the fluctuation range. Specifically, when the fluctuation range of the temperature change of the wafer chuck is sufficiently smaller than the difference between the target temperature and the chiller target temperature, the chiller target temperature is increased.

  That is, the prober of the present invention includes a wafer chuck that holds a wafer and a control unit that controls each part, and in order to inspect a plurality of semiconductor devices formed on the wafer with a tester, A prober for connecting a terminal to an electrode of the semiconductor device, a cooling means for cooling the surface of the wafer chuck holding the wafer, and a heating means for heating the surface of the wafer chuck holding the wafer. And when the surface of the wafer chuck holding the wafer is cooled, the control unit operates the cooling means to bring the surface of the wafer chuck to a chiller target temperature lower than a target temperature, and In a prober for controlling the wafer chuck to operate at a target temperature by operating a heating means, the control unit controls the wafer chuck to the target temperature. When the control is performed, a change in the surface temperature of the wafer chuck is detected to calculate a fluctuation range, and the calculated fluctuation range is compared with a difference between the target temperature and the chiller target temperature. The chiller target temperature is changed based on the comparison result.

  According to the prober temperature control method of the prober of the present invention, when the surface of the wafer chuck is lowered, the cooling means controls the surface of the wafer chuck to a chiller target temperature lower than the target temperature. In the prober wafer chuck temperature control method for controlling the wafer chuck to reach the target temperature by the heating means, the surface temperature of the wafer chuck is controlled when the wafer chuck is controlled to reach the target temperature. Change is detected, a fluctuation range is calculated from the detected change in the surface temperature, the calculated fluctuation range is compared with a difference between the target temperature and the chiller target temperature, and the chiller target temperature is changed based on the comparison result. It is characterized by that.

  The comparison is performed by calculating a ratio of the fluctuation range to the difference between the target temperature and the chiller target temperature, and determining whether the calculated ratio is smaller than a predetermined value. When the fluctuation range is small, the chiller target temperature is increased by a predetermined temperature.

  When the temperature control of the wafer chuck as described above is performed, the fluctuation range is not constant because the temperature of the wafer chuck is affected by various factors such as the target temperature, room temperature, wafer type, and characteristics of the mounted device. The prober is required to be able to inspect at the target temperature in any case. If the difference between the chiller target temperature and the target temperature is smaller than the fluctuation range, it may be impossible to bring the wafer chuck to the target temperature, but the prober is required to avoid such a situation. Is done. Therefore, the difference between the chiller target temperature and the target temperature cannot be made sufficiently small.

  As described above, there are various factors that affect the fluctuation range, but the fluctuation range when the temperature is actually controlled is a comprehensive result of these factors. Focusing on this point, the present invention obtains the fluctuation range when the temperature is actually controlled, compares the fluctuation range with the difference between the target temperature and the chiller target temperature, and sets the chiller target temperature to the optimum value based on the comparison result. Change to be. As a result, even when the fluctuation range of the temperature change is large, it is possible to cope with it, and when the chiller target temperature can be brought close to the target temperature, the power is reduced because the size is reduced.

  In probe inspection in a semiconductor manufacturing process, the same type of wafer may be continuously measured under the same temperature condition. In such a case, even if the wafer to be inspected is replaced, it is predicted that a similar fluctuation range will be obtained. Therefore, it is possible to use the chiller target temperature when the previous wafer is inspected.

  According to the present invention, it is possible to realize a prober and a prober wafer chuck temperature control method that can cope with various inspection conditions and reduce power consumption by simply changing the control sequence.

  The prober of the embodiment of the present invention will be described below. The hardware configuration of the prober of the embodiment is the same as that of the conventional prober described with reference to FIGS. 1 and 2, and only the control sequence of the control unit 16 under low temperature conditions. Is different.

  FIG. 4 is a view for explaining temperature control of the wafer chuck at a low temperature according to the present invention. When the wafer chuck 11 is set to the low target temperature T, the chiller target temperature C1 is determined in the same manner as in the prior art, and control for setting the wafer chuck 11 to the target temperature T is executed in the same manner as in the prior art. As a matter of course, the inspection is started when the wafer chuck 11 is within a predetermined range with respect to the target temperature T. In parallel with the inspection, the control unit 16 reads the output of the temperature sensor 19 and detects the temperature near the surface of the wafer chuck 11.

  As shown in FIG. 4A, when the temperature near the surface of the wafer chuck 11 changes with a relatively small fluctuation range, the chiller target temperature is increased from C1 to C2 close to the target temperature T. When the temperature near the surface of the wafer chuck 11 has a large fluctuation range as shown in FIG. 4B, the chiller target temperature is maintained at C1.

  FIG. 5 is a flowchart showing a temperature control sequence of the wafer chuck at a low temperature in the prober of the embodiment.

  In step 101, the chiller target temperature C1 is determined according to the target temperature T as in the conventional case.

  In step 102, the heater 13 and the chiller mechanism are controlled so as to bring the wafer chuck 11 to the target temperature T as in the conventional case. If the wafer chuck 11 is within a predetermined range with respect to the target temperature T, the inspection is started.

  In step 103, the temperature of the wafer chuck 11 output from the temperature sensor 19 is detected, and the fluctuation range is calculated.

  In step 104, the ratio R of the calculated fluctuation range to the difference TC between the target temperature T and the chiller target temperature C is calculated.

  In step 105, it is determined whether the ratio R is smaller than TR. T is a value of about 0.7, for example. If R is smaller than TR, the process proceeds to step 106; otherwise, the process returns to step 102.

  In step 106, the chiller target temperature C is increased by Δ (TC). Here, Δ is a value of 0.1 to 0.2, for example. After step 106, the process returns to step 102.

  By repeating the operation shown in FIG. 5, the chiller target temperature becomes close to the target temperature when the fluctuation range of the temperature of the wafer chuck is small. Thereby, power consumption (energy consumption) is reduced.

  Although the embodiments of the present invention have been described above, it goes without saying that various modifications are possible. For example, control methods other than those shown in the flowchart of FIG. 5 are possible. In addition, the present invention can be applied to any configuration as long as it has a heating mechanism for heating the wafer chuck and a chiller mechanism for cooling the wafer chuck.

  The present invention can be applied to any prober having a wafer chuck heating mechanism and a chiller mechanism.

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 a chiller mechanism. It is a figure explaining the conventional control which makes low temperature using both the heating mechanism and chiller mechanism of a wafer chuck. It is a figure explaining the temperature control of the Example of this invention. It is a flowchart which shows the temperature control operation | movement of the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Wafer chuck 12 Coolant liquid path | route 13, 13A, 13B Heater 14 Coolant source 16 Control part 19, 19A, 19B Temperature sensor W Wafer

Claims (4)

A wafer chuck for holding the wafer;
A prober for connecting each terminal of the tester to an electrode of the semiconductor device in order to inspect the plurality of semiconductor devices formed on the wafer with a tester.
Cooling means for cooling the surface of the wafer chuck for holding the wafer;
Heating means for heating the surface of the wafer chuck for holding the wafer,
The control unit operates the cooling unit to lower the surface of the wafer chuck holding the wafer to a chiller target temperature lower than a target temperature, and to operate the heating unit. In a prober that controls the target temperature to operate by operating
When the control is performed so that the wafer chuck reaches the target temperature, the control unit detects a change in the surface temperature of the wafer chuck and calculates a fluctuation range. A prober characterized by comparing a target temperature and a difference between the chiller target temperature and changing the chiller target temperature based on a comparison result.   The control unit calculates a ratio of the fluctuation range to a difference between the target temperature and the chiller target temperature, and increases the chiller target temperature by a predetermined temperature when the calculated ratio is smaller than a predetermined value. Prober. When the surface of the wafer chuck is lowered, the prober is controlled so that the surface of the wafer chuck is set to a chiller target temperature lower than the target temperature by the cooling means, and the target temperature is controlled by the heating means. In the wafer chuck temperature control method,
When control is performed to bring the wafer chuck to the target temperature, a change in the surface temperature of the wafer chuck is detected,
Calculate the fluctuation range from the detected surface temperature change,
Compare the calculated fluctuation range with the difference between the target temperature and the chiller target temperature,
A prober wafer chuck temperature control method, wherein the chiller target temperature is changed based on a comparison result. In the comparison, a ratio of the fluctuation range to a difference between the target temperature and the chiller target temperature is calculated, and it is determined whether the calculated ratio is smaller than a predetermined value.
4. The prober wafer chuck temperature control method according to claim 3, wherein when the temperature is small, the chiller target temperature is increased by a predetermined temperature.

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