Probing Equipment

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The probing device achieves reliable semiconductor wafer inspections by using a divided temperature adjustment mechanism and synchronized AC voltage control to maintain uniform temperatures and reduce noise, ensuring precise imaging and measurement accuracy.

JP7616877B2Active Publication Date: 2025-01-17SONY SEMICON SOLUTIONS CORP

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Patent Information

Application Number: JP2020206878
Authority / Receiving Office: JP · JP
Patent Type: Patents
Current Assignee / Owner
Filing Date: 2020-12-14
Publication Date: 2025-01-17
Estimated Expiration: 2040-12-14

AI Technical Summary

Technical Problem

Existing probing devices face challenges in maintaining uniform temperature distribution and reliability during semiconductor wafer inspections due to uneven temperature changes and electromagnetic noise, leading to imaging and distance measurement errors.

Method used

A probing device with a temperature adjustment mechanism divided into multiple regions, controlled by a temperature controller, allows for local temperature adjustment and minimizes electromagnetic noise by synchronizing heater activation with AC voltage zero-crossing points.

Benefits of technology

Enhances inspection reliability by maintaining consistent surface temperatures and reducing noise interference, improving positional accuracy to 7.5 μm and enabling accurate imaging and distance measurement at high and low temperatures.

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Abstract

To make it possible to improve the reliability at the time of inspection.SOLUTION: A probing device according to the present invention includes a probe card having a substrate, a probe provided on the lower surface of the substrate, and an optical system provided in the center of the substrate, a temperature control mechanism that is attached to the probe card and has a structure divided into a plurality of divided regions in the plane such that the temperature can be adjusted locally, and a temperature controller that controls the temperature of each of the plurality of divided regions in the temperature control mechanism.SELECTED DRAWING: Figure 4

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Description

[Technical field]

[0001] The present disclosure relates to a probing device used in testing semiconductor wafers. [Background technology]

[0002] There is a probing device used for inspecting semiconductor wafers (hereinafter simply referred to as wafers). The probing device is equipped with a probe card provided with a probe for electrically inspecting semiconductor chips (hereinafter simply referred to as chips) on the wafer. The probe card is also equipped with an optical system, and is capable of acquiring an image of the semiconductor chip by an image sensor. To inspect the wafer with high accuracy, it is desirable to set the probe card to a predetermined temperature, and for this purpose, a technology has been proposed that makes it possible to adjust the temperature of the probe card (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 4-359445 Summary of the Invention [Problem to be solved by the invention]

[0004] With the above temperature adjustment techniques, it is difficult to adjust the temperature locally, and for example, as the probe card moves, the temperature distribution within the surface becomes uneven, which reduces reliability during testing.

[0005] It is desirable to provide a probing device that can improve reliability during testing. [Means for solving the problem]

[0006] The probing device according to an embodiment of the present disclosure includes a substrate and a probe provided on a lower surface of the substrate. Used for electrical testing of semiconductor wafers The probe and the board are located in the center. , which is used to capture images of semiconductor wafers.The device includes a probe card having an optical system, a temperature adjustment mechanism attached to the probe card and having a structure divided into a plurality of divided areas within its surface so as to enable localized temperature adjustment, and a temperature controller that controls the temperature of each of the plurality of divided areas in the temperature adjustment mechanism. The temperature controller controls the temperature of each of the divided regions to a predetermined set temperature so as to suppress temperature changes between the divided regions and achieve a desired positional accuracy in the height direction between the semiconductor wafer and the optical system.

[0007] In a probing device according to an embodiment of the present disclosure, local temperature adjustment is possible by a temperature adjustment mechanism having a structure divided into a plurality of divided regions. [Brief description of the drawings]

[0008] [Figure 1] FIG. 11 is an explanatory diagram showing an example of a measurement sequence by a prober according to a comparative example. [Diagram 2] 11 is a flowchart showing an example of a measurement sequence by a prober according to a comparative example. [Diagram 3] 11 is an explanatory diagram showing an example of the relationship between the preheat time at the center of the wafer by a prober according to a comparative example and the imaging performance at the outer periphery of the wafer. FIG. [Figure 4] 1 is a cross-sectional view showing a configuration example of a probing device according to a first embodiment. [Diagram 5] 2 is a plan view showing an example of an in-plane structure of a temperature adjustment mechanism in the probing device according to the first embodiment. FIG. [Figure 6] 2 is a circuit diagram showing an example of a circuit configuration of a control system of the probing device according to the first embodiment. FIG. [Figure 7] 10 is an explanatory diagram showing an example of a temperature state of a probe card caused by a positional relationship with a wafer; FIG. [Figure 8] FIG. 4 is an explanatory diagram showing an example of division of a temperature adjustment mechanism. [Figure 9] 11 is an explanatory diagram showing an example of an in-plane temperature difference of a probe card when the temperature adjustment mechanism is not divided. FIG. [Figure 10] 11 is an explanatory diagram showing an example of an in-plane temperature difference of a probe card when a temperature adjustment mechanism is divided. FIG. [Figure 11]1A and 1B are explanatory diagrams showing examples of in-plane distribution of MTF of images obtained by image sensors in a non-division method and a division method, respectively. [Figure 12] 5 is a flowchart showing an example of a flow of a control operation for temperature adjustment in the probing device according to the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be made in the following order. 0. Comparative Example (Figs. 1 to 3) 1. First embodiment (FIGS. 4 to 12) 1.1 Configuration 1.2 Operation 1.3 Effects 2. Other embodiments

[0010] <0. Comparative Examples> (Outline and Problems of the Probing Device According to the Comparative Example) One of the semiconductor inspection devices is a prober that uses a probing device to perform wafer inspection. The probe card of the probing device is equipped with an optical system. In the prober, an image of the wafer is captured by an image sensor using an optical system such as a light source and a lens, and wafer-level evaluation is performed. Here, the wafer becomes a heat source and moves at high and low temperatures, so the in-plane temperature of the probe card changes depending on the positional relationship between the wafer and the probe card, and distortion occurs. In addition, the amount of distortion changes from moment to moment because the wafer, which is a heat source, moves. As a result, the positional accuracy of the optical system mounted on the probe card and the wafer changes from moment to moment, for example, within 15 μm, causing focus deviation of the acquired image and distance measurement errors. For the above reasons, it has been considered difficult to perform imaging evaluation and distance measurement evaluation at the wafer level at high and low temperatures.

[0011] On the other hand, Patent Document 1 (JP Patent Publication 4-359445A) proposes a technology that allows the temperature of a probe card to be adjusted in order to set the probe card to a predetermined temperature. In the technology described in Patent Document 1, the temperature of a certain point on the probe card is detected by a temperature sensor, and the temperature of the probe card is controlled by a temperature variable part that is uniformly (without division) arranged on the surface of the probe card based on the detection result. In the technology described in Patent Document 1, when the probe card is always on the wafer surface, it is possible to stabilize the temperature in the surface. However, when a part of the probe card is removed from the wafer surface, it is difficult to suppress the temperature change of the removed part. In contrast, in the technology disclosed herein, as described later, a temperature adjustment mechanism capable of local temperature adjustment is provided, so that even if a part of the probe card is removed from the wafer surface, it is possible to suppress the temperature change of the removed part.

[0012] Furthermore, the technology described in Patent Document 1 does not take measures against electromagnetic noise that occurs when the heater of the temperature adjustment mechanism is turned on and off, and is therefore insufficient when performing inspections using, for example, an ultra-low noise image sensor.

[0013] As a method for making the focus deviation uniform across the wafer, it is possible to use a function of the prober that measures the height of the needle tip of the probe of the probe card and tries to make the amount of needle pressing into the chip constant. In this case, the temperature of the probe card changes when the height of the needle tip of the probe is measured, which is not effective. Therefore, it is considered that it is sufficient if the probe card can maintain the state where the focus is adjusted at the center of the wafer when measuring any chip. For example, as shown in FIG. 1, a method is conceivable in which the probe card is returned to the center of the wafer 100 for each chip 101A to be measured, warmed up (contact preheat), and then moved to the chip 101A to be measured. FIG. 2 is a flowchart showing an example of a measurement sequence by the prober in this case.

[0014] First, the prober moves the probe card to the center of the wafer 100 and performs contact preheating on the central chip 101C (step S11). Next, the prober adjusts the focus on the central chip 101C (step S12). Next, the prober performs contact preheating on the central chip 101C (step S13). Next, the prober moves the probe card and measures the specified chip 101A (step S14).

[0015] Next, the prober judges whether the measurement of the designated number of chips is completed (step S15). If it judges that the measurement of the designated number of chips is not completed (step S15; N), the prober returns to the process of step S13. If it judges that the measurement of the designated number of chips is completed (step S15; Y), the prober moves the probe card to the central chip 101C (step S16).

[0016] Fig. 3 shows an example of the relationship between the preheat time at the center of the wafer and the imaging performance at the periphery of the wafer when using a prober according to a comparative example that performs the measurement sequence described above. The longer the preheat time is, the more the imaging performance tends to improve in terms of focus deviation. If the preheat time is set to 10 minutes, the time required to evaluate one wafer containing, for example, 1000 chips is 10 minutes x 1000 chips = about 7 days, which is not within a realistic evaluation time. The evaluation is required to be completed within 8 hours at the longest.

[0017] In contrast, the technology disclosed herein provides a temperature adjustment mechanism capable of local temperature adjustment, as described below, making it possible to improve reliability during wafer inspection while avoiding any impact on measurement time.

[0018] <1. First embodiment> [1.1 Configuration] Fig. 4 shows a configuration example of the probing device according to the first embodiment. Fig. 5 shows an example of an in-plane structure of the temperature adjustment mechanism 2 in the probing device according to the first embodiment. Fig. 6 shows a circuit configuration example of the control system of the probing device according to the first embodiment.

[0019] The probing device according to the first embodiment includes a probe card 1, a temperature adjustment mechanism 2, and a temperature controller 3.

[0020] The probe card 1 includes a substrate 10 having, for example, a multi-layer wiring structure, a probe 11 provided on the lower surface of the substrate 10 and connected to the wiring of the substrate 10, and an optical system 12 provided in the center of the substrate 10.

[0021] The temperature adjustment mechanism 2 is a thermostat, and is attached to the probe card 1. To enable local temperature adjustment, the temperature adjustment mechanism 2 has a structure divided into a plurality of divided regions 2A, 2B, 2C, and 2D within a plane as shown in Fig. 5. Note that, although Fig. 5 shows a structure divided into four divided regions 2A, 2B, 2C, and 2D as the plurality of divided regions, the structure may be divided into two, three, five or more divided regions.

[0022] The temperature adjustment mechanism 2 has a heater 20 (20A, 20B, 20C, 20D) having a structure divided into a plurality of divided regions 2A, 2B, 2C, 2D within its surface.

[0023] The temperature adjustment mechanism 2 is attached to the lower surface of the substrate 10 of the probe card 1, for example, by an adhesive and an extremely low head screw 13. The temperature adjustment mechanism 2 is attached to an area of the probe card 1 other than the area where the probe 11 and the optical system 12 are provided. The temperature adjustment mechanism 2 may be structured to be provided inside the substrate 10.

[0024] The heaters 20 (20A, 20B, 20C, 20D) are, for example, silicon rubber heaters. The heaters 20 (20A, 20B, 20C, 20D) are attached to the lower surface of the substrate 10 of the probe card 1 via a highly thermally conductive sheet 22 serving as a highly thermally conductive material. The highly thermally conductive sheet 22 is, for example, an electrically insulating type highly thermally conductive material. This reduces the thermal resistance in the plane between the heaters 20 (20A, 20B, 20C, 20D) and the probe card 1.

[0025] In addition, the surface of the heater 20 (20A, 20B, 20C, 20D) opposite to the surface where the heater 20 is attached to the probe card 1 is covered with a heat insulating material 23. This increases the thermal resistance between the heater 20 (20A, 20B, 20C, 20D) and the surrounding atmosphere.

[0026] The temperature adjustment mechanism 2 has thermocouples 21 (21A, 21B, 21C, 21D). The thermocouples 21 (21A, 21B, 21C, 21D) are temperature sensors that detect the temperature in each of the divided regions 2A, 2B, 2C, 2D of the heater 20 (20A, 20B, 20C, 20D). The thermocouples 21 (21A, 21B, 21C, 21D) feed back the surface temperature of the probe card 1 to the temperature controllers 3 (3A, 3B, 3C, 3D), so that the temperature can be controlled by the temperature controllers 3 (3A, 3B, 3C, 3D).

[0027] The temperature of each of the divided regions 2A, 2B, 2C, and 2D in the temperature adjustment mechanism 2 can be adjusted by being driven by an AC voltage from an AC power source 30 (FIG. 6), for example.

[0028] The temperature controllers 3 (3A, 3B, 3C, 3D) control the temperatures of the respective divided regions 2A, 2B, 2C, 2D in the temperature adjustment mechanism 2. As shown in FIG. 6, the control circuit of the temperature adjustment mechanism 2 has an AC power supply 30, a fuse 31, and a switch SW.

[0029] The temperature controller 3 (3A, 3B, 3C, 3D) controls the temperature by driving each of the multiple divided regions 2A, 2B, 2C, 2D in the temperature adjustment mechanism 2 on / off with an AC voltage. As will be described later, the temperature controller 3 (3A, 3B, 3C, 3D) controls the on / off driving timing of each of the multiple divided regions 2A, 2B, 2C, 2D at the timing when the AC voltage reaches a zero cross point.

[0030] With the above-described structure, even if the distance from the lower surface of the probe card 1 to the wafer 100 is, for example, about 4 mm, it is possible to achieve maximum temperature characteristics within a limited space.

[0031] (Example of temperature characteristics) FIG. 7 shows an example of the temperature state of the probe card 1 caused by the positional relationship with the wafer 100. In FIG.

[0032] 7, when a part of the probe card 1 is out of the plane of the wafer 100, the part of the probe card 1 that is on the plane of the wafer 100 is heated by heat from the wafer 100, while the part that is out of the plane of the wafer 100 is cooled by convection and radiation. The temperature adjustment mechanism 2 has a divided structure so as to be able to suppress temperature changes in the part that is out of the plane of the wafer 100.

[0033] Fig. 8 shows an example of division of the temperature adjustment mechanism 2. Fig. 8 shows the difference in structure between a case where the temperature adjustment mechanism 2 is not divided (non-divided type) and a case where it is divided (divided type). The sense points refer to the points where the temperature is detected by the thermocouples 21 (21A, 21B, 21C, 21D).

[0034] Fig. 9 shows an example of the temperature difference within the surface of the probe card 1 when the temperature adjustment mechanism 2 is not divided. Fig. 10 shows an example of the temperature difference within the surface of the probe card 1 when the temperature adjustment mechanism 2 is divided.

[0035] 9, if the temperature adjustment mechanism 2 has a non-divided structure, the temperature of the probe card 1 is, for example, 60° C. in the portion outside the upper surface of the wafer 100, and the temperature of the probe card 1 is 70° C. in the upper surface of the wafer 100, resulting in an in-plane temperature difference in the probe card 1. In contrast, as shown in FIG. 10, if the temperature adjustment mechanism 2 has a divided structure, it is possible to adjust the temperatures of the portion outside the upper surface of the wafer 100 and the portion above the surface of the wafer 100 to, for example, 60° C.

[0036] FIG. 11 shows an example of the in-plane distribution (defocus) of the MTF of an image obtained by an image sensor in each of the non-division method (FIGS. 8 and 9) and the division method (FIGS. 8 and 10) described above.

[0037] As shown in Fig. 11, the in-plane tendency of focus deviation is significantly improved by stabilizing the in-plane temperature of the probe card 1 using the split method. When the MTF is converted to physical length, the positional relationship in the height direction between the optical system 12 and the wafer 100 has an accuracy of, for example, 15 µm in the case of the non-split method and an accuracy of, for example, 7.5 µm in the case of the split method. In this way, in the probing device according to the first embodiment, by adopting the split method as the structure of the temperature adjustment mechanism 2, it is possible to perform imaging evaluation and distance measurement evaluation at the wafer level at high and low temperatures.

[0038] On the other hand, a side effect of temperature adjustment by the temperature adjustment mechanism 2 is that, because the temperature adjustment mechanism 2 and the wafer 100 are located close to each other at a distance of several mm, electromagnetic noise generated from the temperature adjustment mechanism 2 is released into space and reaches the wafer 100, possibly affecting measurements by the image sensor. For example, switching noise caused by the switch SW (FIG. 6) for controlling the on / off of the heaters 20 (20A, 20B, 20C, 20D) may be released into space as electromagnetic noise.

[0039] Therefore, as a noise countermeasure, the temperature controller 3 (3A, 3B, 3C, 3D) monitors the AC voltage of the AC power supply 30, and controls the heaters 20 (20A, 20B, 20C, 20D) to turn on / off when the AC voltage crosses 0V (zero cross point), that is, when the voltage sign is reversed from positive to negative. This makes it possible to suppress the generation of electromagnetic noise, and to reduce the voltage noise level in an image captured by an image sensor from several tens of μV to several μV, for example.

[0040] [1.2 Operation] FIG. 12 is a flowchart showing an example of the flow of a control operation for temperature adjustment in the probing device according to the first embodiment.

[0041] First, the temperature controller 3 judges whether or not the temperature detected by the thermocouple 21 is lower than the set temperature (step S21). If it is judged that the detected temperature is not lower than the set temperature (step S21; N), the temperature controller 3 repeats the process of step S21. If it is judged that the detected temperature is the set temperature (step S21; Y), then the temperature controller 3 judges whether or not the AC voltage is at a zero cross point (step S22). If it is judged that the AC voltage is not at a zero cross point (step S22; N), then the temperature controller 3 repeats the process of step S22. If it is judged that the AC voltage is at a zero cross point (step S22; Y), then the temperature controller 3 turns on the heater 20 (step S23).

[0042] Next, the temperature controller 3 judges whether the temperature detected by the thermocouple 21 is equal to or higher than the set temperature (step S24). If it is judged that the detected temperature is not equal to or higher than the set temperature (step S24; N), the temperature controller 3 repeats the process of step S24. If it is judged that the detected temperature is equal to or higher than the set temperature (step S24; Y), the temperature controller 3 then judges whether the AC voltage is at a zero cross point (step S25). If it is judged that the AC voltage is not at a zero cross point (step S25; N), the temperature controller 3 repeats the process of step S25. If it is judged that the AC voltage is at a zero cross point (step S25; Y), the temperature controller 3 then turns off the heater 20 (step S26).

[0043] Next, the temperature controller 3 judges whether or not there is a control stop command from, for example, a higher-level system (step S27). If it is judged that there is no control stop command (step S27; N), the temperature controller 3 returns to the process of step S21. If it is judged that there is a control stop command (step S27; Y), the temperature controller 3 ends the control process.

[0044] [1.3 Effects] As described above, according to the probing device of the first embodiment, local temperature adjustment is made possible by the temperature adjustment mechanism 2 having a structure divided into a plurality of divided regions 2A, 2B, 2C, and 2D, thereby making it possible to improve reliability during inspection.

[0045] According to the probing device of the first embodiment, the surface temperature of the probe card 1 is kept constant by the temperature adjustment mechanism 2 having a split structure, thereby suppressing distortion of the probe card 1 when the temperature changes, and the positional accuracy in the height direction between the optical system 12 mounted on the probe card 1 and the wafer 100 can be improved from 15 μm to 7.5 μm, for example. This enables imaging evaluation and distance measurement evaluation at the wafer level at high and low temperatures.

[0046] Furthermore, according to the probing device of the first embodiment, the timing of turning on / off the heater 20 of the temperature adjustment mechanism 2 is synchronized with the zero-crossing point of the AC voltage, thereby suppressing the generation of switching noise when turning the heater 20 on / off, and making it possible to reduce the voltage noise level in the image acquired by the image sensor from, for example, several tens of μV to several μV.

[0047] The effects described in this specification are merely examples and are not limiting, and other effects may be achieved. The same applies to the effects of other embodiments described below.

[0048] <2. Other embodiments> The technology according to the present disclosure is not limited to the above-described embodiment, and various modifications are possible.

[0049] For example, the present technology can be configured as follows. According to the present technology having the following configuration, local temperature adjustment is made possible by a temperature adjustment mechanism having a structure divided into a plurality of divided regions, thereby making it possible to improve reliability during inspection.

[0050] (1) a probe card including a substrate, a probe provided on a lower surface of the substrate, and an optical system provided in the center of the substrate; a temperature adjustment mechanism attached to the probe card and having a structure divided into a plurality of divided regions in a plane so as to enable local temperature adjustment; a temperature controller for controlling the temperature of each of the plurality of divided regions in the temperature adjustment mechanism; Equipped Probing equipment. (2) The temperature adjustment mechanism includes: a heater having a structure divided into the plurality of divided regions within a plane; a plurality of temperature sensors for detecting temperatures in the plurality of divided regions of the heater; have A probing device as described in (1) above. (3) the temperature of each of the divided regions of the temperature adjustment mechanism can be adjusted by being driven by an AC voltage; The temperature controller controls the temperature by driving each of the plurality of divided regions in the temperature adjustment mechanism on / off with the AC voltage, and the timing of driving each of the plurality of divided regions on / off is set to coincide with a timing at which the AC voltage reaches a zero cross point. A probing device according to (1) or (2) above. (4) The temperature adjustment mechanism is attached to the lower surface of the substrate of the probe card. A probing device according to any one of (1) to (3) above. (5) The heater is attached to the lower surface of the substrate of the probe card via a highly thermally conductive material. The probing device according to (2) above. (6) The surface of the heater opposite to the surface to which the probe card is attached is covered with a heat insulating material. A probing device as described in (5) above. (7) The temperature adjustment mechanism has four divided regions as the plurality of divided regions. A probing device according to any one of (1) to (6) above. (8) The temperature adjustment mechanism is attached to an area of the probe card other than an area where the probe and the optical system are provided. A probing device according to any one of (1) to (7) above. [Explanation of symbols]

[0051] 1...probe card, 2...temperature control mechanism (thermostat), 2A, 2B, 2C, 2D...division areas, 3 (3A, 3B, 3C, 3D)...temperature controller, 10...substrate, 11...probe, 12...optical system, 13...ultra-low head screw, 20 (20A, 20B, 20C, 20D)...heater (silicon rubber heater), 21 (21A, 21B, 21C, 21D)...thermocouple (temperature sensor), 22...high thermal conductive sheet (high thermal conductive material), 23...insulation material, 30...AC power supply, 31...fuse, 100...wafer (semiconductor wafer), 101A...chip (semiconductor chip), 101C...central chip (semiconductor chip), SW...switch.

Claims

1. a probe card including a substrate, a probe provided on a lower surface of the substrate and used for electrical inspection of the semiconductor wafer, and an optical system provided in the center of the substrate and used for acquiring an image of the semiconductor wafer; a temperature adjustment mechanism attached to the probe card and having a structure divided into a plurality of divided regions in a plane so as to enable local temperature adjustment; a temperature controller for controlling the temperature of each of the plurality of divided regions in the temperature adjustment mechanism; Equipped with The temperature controller controls the temperature of each of the plurality of divided regions to a predetermined set temperature so as to suppress a temperature change between the plurality of divided regions and to obtain a desired positional accuracy in the height direction between the semiconductor wafer and the optical system. Probing equipment.

2. The temperature adjustment mechanism includes: a heater having a structure divided into the plurality of divided regions within a plane; a plurality of temperature sensors for detecting temperatures in the plurality of divided regions of the heater; having The temperature controller controls the temperature of each of the plurality of divided regions to the predetermined set temperature by turning on the heater of the divided region where the temperature detected by the temperature sensor is lower than the predetermined set temperature and by turning off the heater of the divided region where the temperature detected by the temperature sensor is equal to or higher than the predetermined set temperature.