JP2007129091A - Prober - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a prober in which the temperature of a device inspected can be set accurately through a simple arrangement. <P>SOLUTION: The prober comprises a probe card 17 having a probe 18, a wafer chuck 11 for holding a wafer W, and a control section 32 and connects each terminal of a tester 21 with the electrode of a semiconductor device. The prober further comprises a means 31 capable of regulating the temperature at a portion holding the wafer in the wafer chuck 11 entirely but incapable of regulating the temperature partially, and a plurality of temperature sensors 33A, 33B and 33C for detecting the temperature at a plurality of points of the portion holding the wafer in the wafer chuck. The control section 32 calculates an inspection equivalent temperature corresponding to the semiconductor device under inspection from the temperatures at the plurality of points and regulates the temperature regulation means 31 depending on the inspection equivalent temperature. <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 perform electrical inspection of a plurality of semiconductor chips (dies) formed on a semiconductor wafer, and more particularly, heating and heating a surface of a wafer chuck holding a wafer. The present invention relates to a prober that can be cooled and inspected in high and low temperature environments.

  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 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, a chiller mechanism, and a heat pump mechanism is provided under the wafer mounting surface of the wafer chuck for holding the wafer in the prober. Heating or cooling the wafer held thereon is performed.

  FIG. 1 is a diagram showing a schematic configuration of a wafer test system including a prober having a wafer temperature adjusting 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 device 14 to the cooling liquid path 12 via the path 15 to cool the surface of the wafer chuck 11 holding the wafer W. The heater 13 generates heat to heat the surface of the wafer chuck 11 that holds the wafer W. The control unit 16 controls the cooling device 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. To. 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, a connection part 22, and a connection part 23 that electrically connects the terminal of the connection part 22 and the terminal of the probe card 17. The connection part 22 has a connection terminal mechanism using a spring, a so-called spring pin structure. The prober performs measurement in cooperation with the tester in the wafer test, but 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. . In the following description, the cooling mechanism including the coolant path 12 and the cooling device 14 and the heating mechanism including the heater 13 are collectively referred to as wafer temperature adjusting means. Therefore, the wafer temperature adjusting means may have only one of a cooling mechanism and a heating mechanism.

  The wafer temperature adjusting means can set the wafer W held on the wafer chuck 11 to an arbitrary temperature from −55 ° C. to + 200 ° C., for example. The wafer temperature adjusting means can also be realized by a heat pump mechanism or the like.

  When the wafer is inspected at a predetermined temperature, the control unit 16 controls the wafer temperature adjusting means based on the temperature detected by the temperature sensor 19 while the wafer W is held on the wafer chuck 11. Set to a predetermined temperature. The wafer chuck 11 is made of a material having good thermal conductivity such as aluminum, copper, or ceramic, and the surface holding the wafer W is considered to have substantially the same temperature. Therefore, only one temperature sensor 19 is provided, and control is performed assuming that the detected temperature of the wafer chuck 11 is the same in other portions.

  Further, the wafer W has a thin plate shape, and when it is attracted to and held by the wafer chuck 11, the thermal resistance between the wafer W and the surface of the wafer chuck 11 is sufficiently small, and the entire surface of the wafer W can be quickly removed from the wafer chuck 11. 11 surface temperature is considered.

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

JP 2001-210683 A (Overall)

  When inspecting the electrical characteristics of a device, a power supply and a signal are supplied to the device to operate, and an output signal is detected. Therefore, the device generates heat during inspection. However, even if heat is generated, the heat capacity of the wafer chuck 11 is large and the thermal conductivity of the wafer chuck 11 is good. Therefore, it has been controlled that the temperature of the device under inspection can be detected by the temperature sensor 19.

  However, the wafer chuck 11 is not sufficiently small in surface thermal resistance due to the internal structure and the like, and when the held wafer device generates heat, the temperature of that portion may rise above the temperature of other portions. all right. It has been found that the difference between the actual temperature of the device being inspected and the temperature detected by the temperature sensor cannot be ignored, especially when testing a device with a large amount of heat generated and the temperature sensor is far from the device being inspected. . In other words, there is a problem that the device to be inspected cannot be set to the inspection temperature accurately.

  In order to solve such a problem, Patent Document 1 divides the surface of the wafer chuck 11 into a plurality of regions, and includes temperature adjusting means (heating mechanism and cooling mechanism) and a temperature sensor that can be controlled independently for each region. Although it is described that the temperature adjusting means in each region is controlled based on the temperature detected by each temperature sensor, there is a problem that the cost increases.

  Further, reducing the surface roughness of the wafer chuck 11 to reduce the temperature resistance between the held wafer and the surface of the wafer chuck also reduces the difference between the temperature of the device under inspection and the temperature detected by the temperature sensor. Although effective in the above, it is still expensive and the effect is not sufficient.

  The present invention solves such a problem, and an object thereof is to realize a prober capable of accurately setting the temperature of a device under inspection to a desired temperature at a low cost.

  In order to achieve the above object, the prober of the present invention is provided with a plurality of temperature sensors on the wafer chuck to detect temperatures at a plurality of locations on the wafer chuck, and corresponds to a device (die) under inspection from the temperatures at the plurality of locations. The temperature is calculated, and the temperature adjusting means is adjusted according to the temperature.

  That is, the prober of the present invention includes a probe card having a probe that contacts an electrode of a semiconductor device and connects the electrode to a terminal of a tester, a wafer chuck that holds a wafer, and a control unit that controls each unit. 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 a portion for holding the wafer of the wafer chuck A temperature adjusting unit that adjusts the temperature as a whole and cannot partially adjust the temperature; and a plurality of temperature sensors that detect temperatures of a plurality of portions of the wafer chuck holding the wafer, and the control unit includes: The temperature corresponding to the semiconductor device being inspected among the plurality of semiconductor devices is calculated from the temperatures of the plurality of locations detected by the plurality of temperature sensors, And adjusting the temperature adjusting means in accordance with the serial test corresponding temperature.

  The temperature sensor is inexpensive, and even if a plurality of temperature sensors are provided, the increase in cost is small. If a plurality of temperature sensors are provided on the wafer chuck to detect the temperatures at a plurality of locations on the wafer chuck, the inspection corresponding temperature corresponding to the device (die) being inspected can be calculated more accurately from the temperatures at the plurality of locations. The temperature adjustment means can only adjust the temperature of the part of the wafer chuck that holds the wafer as a whole, but not the temperature of the wafer chuck, but it is the device under inspection that needs to be adjusted. By adjusting the temperature adjusting means based on the inspection-corresponding temperature corresponding to the device, the device under inspection can be brought to a desired temperature. Of course, in the present invention, temperatures other than the device under inspection cannot be controlled, but there is no problem in inspecting. As described above, according to the present invention, in a conventional prober, it is possible to accurately set a device under inspection to a desired temperature only by changing the control software by increasing the number of low-cost temperature sensors. .

  There are various methods for calculating the inspection-corresponding temperature.

  For example, the highest temperature among a plurality of temperatures detected by a plurality of temperature sensors is calculated as the inspection-corresponding temperature. This is because the temperature of the wafer chuck and that portion of the wafer rises locally as the device under inspection generates heat, so the temperature sensor that detects the highest temperature is considered to be closest to the device under inspection.

  Further, since the position of the device under inspection is known, the temperature detected by the temperature sensor closest to the device under inspection may be calculated as the inspection corresponding temperature.

  In general, since the number of temperature sensors is smaller than the number of devices in the wafer, the device under inspection may be separated from any temperature sensor to some extent. Therefore, a plurality of related temperatures detected by a plurality of temperature sensors in the vicinity of the device under inspection are combined according to the distance to each temperature sensor of the device under inspection to calculate the inspection corresponding temperature. Also good. In this case, since the temperature corresponding to the device under inspection is considered to have the highest temperature, the position corresponding to the device under inspection is detected from the temperature gradient using the temperature detected by the surrounding temperature sensors. It is desirable to calculate the temperature.

  Also, when the response speed of temperature adjustment by the temperature adjustment means is not sufficiently high, when the inspection of one device is completed and the next device is inspected, the inspection-corresponding temperature of the device position is within the inspection temperature allowable range. There may be cases where it is not. In general, since the order of inspection of a plurality of devices is set in advance, the inspection-corresponding temperature corresponding to the inspection-inspected device predicted to be inspected following the device under inspection is calculated, and the inspection-corresponding temperature is calculated. Further, the temperature of the device that is predicted to be inspected subsequently may be predicted and controlled based on the temperature corresponding to the inspection schedule. For example, there is an allowable range for the inspection temperature of the device. Therefore, when the device is being inspected, the temperature corresponding to the inspection of the device is controlled to be within this allowable range, but when the inspection of this device is nearing completion, the temperature corresponding to the expected inspection of the device to be inspected next is controlled. Is below the lower limit of the allowable range, and if the inspection-corresponding temperature of the device under inspection has a margin up to the upper limit of the allowable range, the temperature is raised within a range where the inspection-corresponding temperature does not exceed the upper limit of the allowable range.

  When performing the above predictive control, a plurality of temperatures detected by a plurality of temperature sensors in the vicinity of the target device are combined according to the distance from the target device to each temperature sensor in the vicinity. It is desirable to apply a method for calculating the corresponding temperature.

  As described above, according to the present invention, a prober that can accurately set the temperature of a device under inspection to a desired temperature can be realized at low cost.

  FIG. 2 is a diagram showing a configuration of a wafer test system having a prober according to an embodiment of the present invention. FIG. 2 corresponds to FIG. 1, and corresponding portions are denoted by the same reference numerals. The difference from the configuration of FIG. 1 is that the wafer chuck 11 is provided with a plurality of temperature sensors 33A, 33B, and 33C. In practice, it is desirable to provide a larger number of temperature sensors. Detection signals from the temperature sensors 33A, 33B, and 33C are selected by the switch 34 and input to the control unit 32. The control unit 32 is realized by a computer, for example, and selects which temperature sensor output is input by controlling the switch 34. The output of the selected temperature sensor is converted into digital data by an A / D converter in the control unit 32 and processed. Note that a temperature sensor that outputs digital temperature data can also be used. The temperature adjusting means 31 is a part constituted by the cooling mechanism and / or the heater of FIG. 1 and may be anything as long as the temperature of the surface of the wafer chuck 11 holding the wafer W can be adjusted.

  The temperature sensors 33A, 33B, and 33C can be realized by, for example, a low-cost thermistor or the like, but may be any small temperature sensor.

  Hereinafter, an example of how the temperature adjusting means 31 is controlled based on a plurality of temperature data detected by a plurality of temperature sensors will be described with reference to FIG.

  FIG. 3 shows the arrangement of 13 temperature sensors A to M provided on the wafer chuck 11 and the arrangement of dies (devices) formed on the wafer W held on the wafer chuck 11. Although it is desirable to provide as many temperature sensors as possible and the maximum number of dies, a number smaller than the number of dies is provided due to cost and arrangement space. In FIG. 3, 13 temperature sensors A to M are used and arranged as shown.

  In the first control method, temperature data of a plurality of locations detected by M are read from a plurality of temperature sensors A while sequentially switching (scanning) the switch 34, and the highest temperature among them is set as the inspection-corresponding temperature. When the device under inspection generates heat, the temperature of the wafer chuck 11 and the portion of the device under inspection of the wafer W rises locally. Therefore, the temperature sensor that detects the highest temperature is considered to be closest to the device under inspection.

  For example, when the die 100 corresponding to the position of the temperature sensor B is inspected, the die 100 generates heat, so that the temperature detected by the temperature sensor B is higher than the temperatures detected by the other temperature sensors A and C to M. . Further, when the die 101 in the vicinity of the temperature sensor B is inspected, the die 101 generates heat, so that the temperature detected by the temperature sensor B closest to the die 101 is the temperature detected by the other temperature sensors A, C to M. Get higher. Accordingly, the temperature data detected by the temperature sensors A and C is ignored, and the temperature adjusting means 31 is controlled based on the temperature data detected by the temperature sensor B, so that the temperature detected by the temperature sensor B is a desired temperature. Control within the range.

  The second control method uses information regarding the position of the device under inspection. The prober moves the wafer chuck 11 in accordance with an instruction from a tester or a host computer to bring the probe electrode into contact with the probe 18. Accordingly, the prober controller 32 has information regarding the position of the die under inspection. Therefore, the temperature detected by the temperature sensor closest to the device under inspection may be calculated as the inspection-corresponding temperature by switching the switch 34. Except for this point, the description is the same as the first control method, and thus the description is omitted.

  Similar to the second control method, the third control method uses information regarding the position of the device under inspection. As described above, since the number of temperature sensors is smaller than the number of dies on the wafer W, the position of the device under inspection may not match the position of the temperature sensor. Therefore, in the second control method, the temperature detected by the temperature sensor closest to the device under inspection is set as the inspection corresponding temperature. However, this causes an error corresponding to the distance between the device under inspection and the temperature sensor. In the third control method, this error is corrected.

  In the third control method, when the device 102 is inspected, the temperature data detected by the surrounding temperature sensors C, D, G, and H is used as four related temperature data to determine the inspection-corresponding temperature of the device 102. calculate. Specifically, since the temperature at the position of the device 102 under inspection is considered to be the highest, the temperature sensors A, B, F, I, J, K, and L further around the temperature sensors C, D, G, and H The temperature gradient at the positions of the temperature sensors C, D, G, and H is calculated using the detected temperature data. Then, the temperature corresponding to the temperature gradient and the distance from the device 102 under inspection to the temperature sensors C, D, G and H are combined to calculate the inspection corresponding temperature at the position of the device 102 under inspection.

  The fourth control method not only calculates the inspection-corresponding temperature of the device under inspection, but also performs control by predicting the temperature at the position of the device to be inspected following the device under inspection. In general, the response speed of the temperature adjustment by the temperature adjusting means 31 is not sufficiently high, and a certain response time is required. Therefore, when the inspection of a certain device is completed and the next device is inspected, there may be a case where the inspection-corresponding temperature at the position of the device is not within the inspection temperature allowable range. In this case, it is necessary to wait until the inspection-corresponding temperature of the portion is within the allowable range of the inspection temperature. Generally, since the inspection order of the devices on the wafer W is set in advance, after the device under inspection The position of the device to be inspected to be subsequently inspected is known. Therefore, in the fourth control method, the temperature corresponding to the inspection schedule corresponding to the position of the inspection scheduled device is calculated, and the temperature of the device predicted to be subsequently inspected based on the inspection corresponding temperature and the inspection scheduled correspondence temperature. Predictive control.

  For example, the inspection-corresponding temperature of the device under inspection needs to be within an allowable range and is controlled so as to satisfy it. It can be calculated by the same method as the inspection-compatible temperature described in the control method. If the inspection schedule corresponding temperature is within the allowable range, there is no particular problem and the control is continued as it is. However, there is a possibility that the inspection schedule corresponding temperature is outside the allowable range, for example, below the lower limit of the allowable range. In that case, when the inspection of the device under inspection is nearing the end, the temperature is controlled so that the temperature corresponding to the inspection at the position of the device under inspection does not exceed the upper limit of the allowable range. As a result, the temperature corresponding to the inspection schedule rises, and the difference from the lower limit is reduced even if it falls within the allowable range or does not fall within the allowable range, so the standby time when starting the next device inspection can be shortened. .

  In the fourth control method, when the inspection time per device is short, it is desirable to calculate not only the next device to be inspected but also the temperature corresponding to the inspection schedule of several devices ahead and use it for the control.

  As mentioned above, although the Example of this invention was described, it cannot be overemphasized that various modifications are possible. For example, in the above-described embodiment, it is described that one die (device) is inspected at the same time. However, in recent years, a plurality of dies are also inspected at the same time. The present invention can be similarly applied to such a case.

  The present invention can be applied to any prober that inspects a wafer under a predetermined temperature condition such as high temperature or low temperature. By applying the present invention, the temperature of a device to be inspected can be accurately set with a simple configuration.

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 wafer test system of the Example of this invention. It is a figure which shows arrangement | positioning of the temperature sensor on a wafer chuck for demonstrating the control method in 2 Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Wafer chuck 17 Probe card 18 Probe 21 Tester main body 31 Temperature adjustment means 32 Control part 33A-33C Temperature sensor 34 Switch AM Temperature sensor W Wafer

Claims (6)

A probe card having a probe that contacts an electrode of a semiconductor device and connects the electrode to a terminal of a tester;
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 a plurality of semiconductor devices formed on the wafer with a tester.
Temperature adjusting means for adjusting the temperature of the portion of the wafer chuck that holds the wafer as a whole, and temperature adjustment that cannot be partially adjusted;
A plurality of temperature sensors for detecting the temperature of a plurality of locations of the portion of the wafer chuck that holds the wafer, and
The controller calculates an inspection corresponding temperature corresponding to a semiconductor device being inspected among the plurality of semiconductor devices from the temperatures at a plurality of locations detected by the plurality of temperature sensors, and the temperature according to the inspection corresponding temperature. A prober characterized by adjusting the adjusting means.   The prober according to claim 1, wherein the control unit calculates the highest temperature as the inspection-corresponding temperature among a plurality of temperatures detected by the plurality of temperature sensors.   2. The prober according to claim 1, wherein the control unit calculates a temperature detected by a temperature sensor closest to the semiconductor device under inspection being inspected as the inspection-corresponding temperature.   The controller synthesizes a plurality of related temperatures detected by a plurality of temperature sensors in the vicinity of the semiconductor device under inspection in accordance with distances to the plurality of temperature sensors in the vicinity of the semiconductor device under inspection. The prober according to claim 1, wherein the probe-corresponding temperature is calculated. The plurality of semiconductor devices on the wafer have a preset inspection order,
The controller calculates, from the temperatures at a plurality of locations detected by the plurality of temperature sensors, a test scheduled corresponding temperature corresponding to a test planned semiconductor device that is predicted to be subsequently tested after the semiconductor device under test, The prober according to claim 1, wherein the temperature adjusting unit is adjusted based on the inspection corresponding temperature and the inspection scheduled corresponding temperature.   The controller synthesizes a plurality of related temperatures detected by a plurality of temperature sensors in the vicinity of the semiconductor device under inspection according to a distance from the semiconductor device under inspection to the plurality of temperature sensors in the vicinity. Calculating the inspection-corresponding temperature and determining a plurality of schedule-related temperatures detected by a plurality of temperature sensors in the vicinity of the semiconductor device to be inspected as distances to the temperature sensors in the vicinity of the semiconductor device to be inspected. The prober according to claim 5, wherein the prober corresponding temperature is calculated according to the calculation.

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