Prova

Abstract

To provide a prober that can reliably prevent condensation from occurring during probing. [Solution] In one embodiment, the probe 1 comprises a sealing member 37 interposed between a holding member 62 and a chuck 34 to form a sealed space S in which a probe 65 is positioned; a suction passage 84 connected to a vacuum source 100 via an external pipe 92 for reducing the pressure in the sealed space S; a regulator 104 that adjusts the fluid flow in the external pipe 92 so that the negative pressure acting on the sealed space S approaches a set pressure; a gas supply unit 110 that supplies dry gas to the sealed space S; and a pressure control unit 20 that controls the regulator 104. The gas supply unit 110 supplies dry gas when the regulator 104 is operating. The pressure control unit 20 corrects the set pressure according to the flow rate of dry gas so that no backflow of fluid occurs from the external pipe 92 to the sealed space S while the regulator 104 and the gas supply unit 110 are operating.

Description

[Technical Field]

[0001] The present invention relates to a prober for inspecting devices formed on a wafer. [Background Art]

[0002] In a wafer on which a large number of devices are formed in the pre-process of semiconductor manufacturing, the wafer is divided into a plurality of chips for each device in a dicing process. Prior to the dicing process, probing is performed to remove defective products from among the devices on the wafer. Probing is a wafer-level inspection that identifies defective products by inspecting the electrical characteristics of devices formed on a wafer. The apparatus that performs this probing is a prober.

[0003] A prober includes a probe card having a plurality of probes. The probes are electrically connected to a test head. By bringing the wafer into contact with the probe card, each probe is brought into contact with an electrode pad of each device. An electrical signal is sent from the test head to each device via the probe, and the electrical characteristics thereof are inspected to determine whether the device is defective.

[0004] In recent years, along with the demand for larger wafers and higher integration, the number of devices formed per wafer has also increased. For this reason, improvement of inspection efficiency is required to improve throughput and reduce cost in semiconductor manufacturing. Accordingly, a so-called multi-stage multi-stage prober (also referred to as a "multi-prober") in which a plurality of stages of stages having a plurality of test heads arranged in the horizontal direction are provided vertically has also been developed (see Patent Document 1). According to such a prober, since a plurality of test beds can perform inspection simultaneously and continuously, inspection efficiency can be improved.

[0005] Each stage of the multi-prober is equipped with a chuck for placing wafers corresponding to each test head, while a shared alignment device is positioned for multiple test heads. The alignment device detachably supports the chuck on which the wafer is placed. During probing, the alignment device is driven to bring the chuck closer to the test head and bring the wafer into contact with the probe card. A sealing member is provided between the test head and the chuck, and by reducing the pressure in the sealed space formed inside the sealing member to create a negative pressure state, the wafer, along with the chuck, is pulled towards the head stage and held in place. This allows the chuck to be temporarily detached from the alignment device, and probing can continue in that state. During this time, the alignment device can be moved to another head stage. Therefore, the number of alignment devices can be reduced relative to the number of test heads, and the manufacturing cost of the prober can be reduced. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2018-49989 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Incidentally, probing is performed considering the actual usage environment in order to ensure the functionality of the device, and depending on the device specifications, it may be performed in a low-temperature environment. In that case, it is necessary to prevent damage to the device due to condensation. Therefore, the prober in Patent Document 1 incorporates measures such as lowering the dew point by appropriately supplying dry gas to the aforementioned sealed space.

[0008] This prober switches between depressurizing a sealed space and supplying dry gas, either one or the other. Therefore, it is difficult to stably fill the sealed space with dry gas while maintaining a stable negative pressure state. Furthermore, even with sealing components, it is difficult to completely eliminate pressure leakage from the sealed space to adjacent spaces (areas with higher vacuum). If the negative pressure in the sealed space increases due to this pressure leakage, there is a possibility that air will enter the sealed space and cause condensation.

[0009] This invention has been made in view of these circumstances, and one of its objectives is to provide a prober that can reliably prevent the occurrence of condensation during probing. [Means for solving the problem]

[0010] A prober according to one aspect of the present invention comprises a holding member for holding a probe card, a chuck having an adsorption surface for vacuum adsorption of a wafer on a surface facing the probe card, a sealing member interposed between the holding member and the chuck and forming a sealed space in which a probe connected to the probe card is arranged, a suction passage connected to a vacuum source via an external pipe for reducing the pressure in the sealed space, a regulator connected to the external pipe and adjusting the fluid flow in the external pipe so that the negative pressure acting on the sealed space approaches a set pressure, a gas supply unit for supplying dry gas to the sealed space, and a pressure control unit for controlling the regulator. By creating a negative pressure state in the sealed space, the sealing member achieves a sealed state of the sealed space, and the holding member holds the chuck. The gas supply unit supplies dry gas when the regulator is operating. The pressure control unit corrects the set pressure according to the flow rate of dry gas so that no backflow of fluid from the external pipe to the sealed space occurs while the regulator and gas supply unit are operating. [Effects of the Invention]

[0011] According to the present invention, a prober can be provided that can reliably prevent the occurrence of condensation during probing. [Brief explanation of the drawing]

[0012] [Figure 1] It is a diagram illustrating the schematic configuration of a prober according to an embodiment. [Figure 2] It is a horizontal cross-sectional view schematically illustrating the internal structure of the prober. [Figure 3] It is a cross-sectional view taken along line A-A in Figure 2. [Figure 4] It is an enlarged view of portion B in Figure 3. [Figure 5] It is a diagram illustrating the configuration and operation of a measurement unit. [Figure 6] It is a diagram illustrating the configuration and operation of a measurement unit. [Figure 7] It is a diagram illustrating an outline of a negative pressure control method during probing. [Figure 8] It is a diagram illustrating results of an experiment performed for setting a differential pressure correction value. [Figure 9] It is a flowchart illustrating an outline of probing processing. [Figure 10] It is a flowchart illustrating an outline of probing processing. [Figure 11] It is a diagram illustrating the operation of the prober during a probing step. [Figure 12] It is a diagram illustrating the operation of the prober during a probing step. [Figure 13] It is a diagram illustrating an effect obtained when differential pressure correction according to the embodiment is performed. DETAILED DESCRIPTION OF EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following embodiment and modifications thereof, substantially identical components are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

[0014] The prober of the present embodiment inspects the electrical characteristics of semiconductor devices formed on a wafer (also simply referred to as "devices"). When performing probing (wafer level inspection) under a low-temperature environment, dry air is supplied to each area of the prober to prevent dew condensation in each area. During probing, a sealed space is formed between the chuck that holds the wafer and the test head. By setting the sealed space to a negative pressure state, the chuck is stably supported by the test head, and the contact state between the device and the probe is maintained. The negative pressure is maintained at a set pressure by a regulator provided outside the apparatus. In the present embodiment, dry air for dew condensation prevention is also supplied to the sealed space. In order to stably prevent the occurrence of dew condensation in this sealed space, the set pressure is corrected according to the flow rate of dry gas into the sealed space. The details thereof will be described below.

[0015] FIG. 1 is a diagram illustrating a schematic configuration of a prober according to an embodiment. For convenience of description below, when viewed from the front of the apparatus, the left-right direction, the front-rear direction, and the up-down direction are described as the X direction, the Y direction, and the Z direction, respectively. The prober 1 has a housing 2 that is rectangular in front view and plan view. Inside the housing 2, there are provided a measurement area 10 where wafer inspection is performed, and a loader area 12 where wafers and the like are conveyed into and carried out of the measurement area 10. The loader area 12 includes a storage area 14 that stores wafers and probe cards.

[0016] In the storage area 14, there are provided a wafer storage portion 16 that stores wafers, and a card storage portion 18 that stores probe cards. The wafer storage portion 16 receives wafer cassettes such as FOUPs and FOSBs that store a plurality of wafers. When an operator or a robot recovers a wafer or a probe card, access can be made from the front side of each storage portion. A loader door 4 for an operator to enter and exit the loader area is provided on a side surface of the housing 2.

[0017] The prober 1 is also equipped with a control unit 20 and an operation panel 22. The control unit 20 consists of a general-purpose computer and includes a CPU for executing various calculation processes, memory or storage for storing control programs, memory used as a work area for data storage and program execution, an input / output interface, a user interface, etc. The user interface accepts operator input via the operation panel 22. The control unit 20 controls each functional part (mechanism and device) of the prober 1 according to the control program.

[0018] Figure 2 is a schematic horizontal cross-sectional view showing the internal structure of prober 1. Prober 1 has a measurement area 10 and a loader area 12. The measurement area 10 includes an inspection area, which will be described later. The measurement area 10 and the loader area 12 are separated by a partition wall provided inside the housing 2. The loader area 12 includes a storage area 14 and a transport area 15. A transport unit 24 for transporting wafers W and probe cards (described later) is movably arranged in the transport area 15.

[0019] The measurement area 10 is provided with multiple measurement units 30 for probing the wafer W. In this embodiment, a multi-stage prober is employed, in which a stage with four measurement units 30 arranged horizontally is arranged in three vertical rows, but the number of arrangements and rows can be set as appropriate.

[0020] In the measurement area 10, a shared alignment device 32 is positioned for each measurement section 30. The alignment device 32 detachably supports a chuck 34 (wafer chuck). The chuck 34 holds and fixes the wafer W by means of vacuum suction, for example, and is attached to and detached from the test head of the measurement section 30 during the probing process (details will be described later). The alignment device 32 can move between multiple measurement sections 30 arranged horizontally. The chuck 34 can move in the X, Y, and Z directions within the measurement area 10 by the operation of the alignment device 32, and can also rotate around the Z axis (θ direction).

[0021] The transport unit 24 transports wafers W between the wafer housing 16 and each measurement unit 30, and transports probe cards between the card housing 18 and each measurement unit 30. The transport unit 24 is equipped with an arm 26 for receiving and transferring wafers W. A suction pad (not shown) is provided on the upper surface of the arm 26. The arm 26 holds the wafer W by vacuum adsorption of the back surface of the wafer W using this suction pad. The transport unit 24 is a transport device shared by all measurement units 30, and is movable in the X and Z directions by the operation of a drive mechanism (not shown), and can also rotate around the Z axis (θ direction).

[0022] The transport unit 24 moves its arm 26 back and forth (extends and retracts) by the operation of an arm drive mechanism (not shown). The wafers W in the wafer housing section 16 are removed by the arm 26 and transported to each measurement section 30 by the transport unit 24. After inspection is complete, the wafers W are returned to the wafer housing section 16 by following the reverse path from each measurement section 30.

[0023] Figure 3 is a cross-sectional view taken along the line AA in Figure 2. Figure 4 is an enlarged view of section B in Figure 3. As shown in Figure 3, the measurement area 10 is provided with three upper and lower level measurement sections 30. Each measurement section 30 is partitioned by a partition wall 36 into an inspection area 40 and an equipment housing area 42. The inspection area 40 is the area where the wafer W to be inspected is placed and is located relatively lower down. The equipment housing area 42 is the area where the test head 44 and other electrical equipment are housed and is located relatively higher up. The inspection area 40 is partitioned from the transport area 15 by a partition wall 38, and the equipment housing area 42 is partitioned from the transport area 15 by a partition wall 39. The equipment housing area 42 and the transport area 15 correspond to an "outer area" partitioned separately from the inspection area 40.

[0024] More specifically, as shown in Figure 4, the alignment device 32 is positioned in the inspection area 40. The partition wall 38 is provided with an opening 46 that connects the inspection area 40 and the transport area 15, and a shutter 48 that opens and closes the opening 46. By opening the shutter 48, the arm 26 of the transport unit 24 can be extended into the inspection area 40. In other words, wafers W can be transferred between the transport unit 24 and the alignment device 32.

[0025] Furthermore, the inspection area 40 is equipped with a heat exchanger 50 for cooling the chuck 34. Pipes 52 for circulating coolant are connected to the heat exchanger 50. When probing is performed in a low-temperature environment, coolant is supplied to the chuck 34 via pipes 52. This allows the wafer W (i.e., the device formed on the wafer W) placed on the chuck 34 to be cooled.

[0026] A heating and cooling structure (not shown) is provided inside the chuck 34. This allows the wafer W to be heated to a high temperature (e.g., 150°C) or a low temperature (e.g., -40°C) to test the electrical characteristics of the device. In this embodiment, a double-layer structure is used for the heating and cooling mechanism, consisting of a heating layer with a surface heater and a cooling layer with a passage for a cooling liquid. In a modified example, a single-layer heating / cooling device may be used as the heating and cooling mechanism, in which a cooling tube with a heating heater wrapped around it is embedded in a heat conductor.

[0027] Meanwhile, the equipment housing area 42 contains the test head 44 and electrical equipment (not shown). A pogo frame 54 is positioned at the boundary between the inspection area 40 and the equipment housing area 42. The pogo frame 54 functions as an interface connecting the test head 44 and the probe card (described later).

[0028] Each area is equipped with a discharge port for releasing dry air to prevent condensation. The inspection area 40 is equipped with a discharge port 56, and the equipment housing area 42 is equipped with a discharge port 58. The transport area 15 is also equipped with a discharge port 60.

[0029] Figures 5 and 6 illustrate the configuration and operation of the measuring unit 30, corresponding to the cross-sectional view taken along the CC arrow in Figure 4. Figure 5 shows the state before inspection, and Figure 6 shows the state during inspection. As shown in Figure 5, the measurement unit 30 comprises a chuck 34, a test head 44, a pogo frame 54, a head stage 62, and a probe card 64. The probe card 64 has a number of probes 65 for supplying power to the wafer W.

[0030] The pogo frame 54 and the head stage 62 constitute part of the partition wall 36 and function as "holding members" that hold the probe card 64. A complementary (circular) mounting hole 66 for attaching the pogo frame 54 is provided in the center of the head stage 62. The mounting hole 66 is closed when the pogo frame 54 is assembled to fit into the mounting hole 66. The head stage 62 has a suction surface capable of adsorbing the pogo frame 54, and the pogo frame 54 is adsorbed and fixed by operating a vacuum source (e.g., a vacuum pump) described later. A seal ring 63 (sealing member) is interposed between the head stage 62 and the pogo frame 54 to maintain airtightness. In modified versions, the head stage 62 and the pogo frame 54 may be fixed together by a fixing structure such as screws.

[0031] The test head 44 is supported above the head stage 62. The test head 44 is electrically connected to the probes 65 of the probe card 64 and supplies test signals (electrical signals) to each device on the wafer W during testing, and detects the output signals from each device to obtain their electrical characteristics. This allows testing whether each device is functioning correctly.

[0032] The pogo frame 54 is equipped with numerous pogo pins 68 that electrically connect each terminal formed on the lower surface of the test head 44 (the surface facing the pogo frame 54) to each terminal formed on the upper surface of the probe card 64 (the surface facing the pogo frame 54). In addition, seal rings 70 and 72 (sealing members) are provided on the peripheral edges of the upper surface (the surface facing the test head 44) ​​and the lower surface (the surface facing the probe card 64), respectively. The seal ring 72 is interposed between the pogo frame 54 and the probe card 64 and functions as a "second sealing member".

[0033] This configuration creates a space S1 surrounded by the test head 44, pogo frame 54, and seal ring 70, and a space S2 surrounded by the probe card 64, pogo frame 54, and seal ring 72. As described later, by reducing the pressure in these spaces S1 and S2 to create a negative pressure state, the test head 44, pogo frame 54, and probe card 64 are integrated. Spaces S1 and S2 correspond to the "second sealed space," and the pogo pins 68 are placed inside it.

[0034] Furthermore, the inner space (i.e., the inspection area 40) and the outer space (i.e., the equipment housing area 42) are separated by a partition wall 36 that includes the head stage 62 and the pogo frame 54. In this embodiment, the probe card 64 may be removed from the pogo frame 54 when the probe card 64 is replaced, but the seal ring 70 still functions at that time, so airtightness between the inspection area 40 and the equipment housing area 42 is maintained.

[0035] The probe card 64 has multiple probes 65 corresponding to the electrodes of each device on the wafer W to be inspected. When the test head 44, pogo frame 54, and probe card 64 are integrated as described above, each probe 65 is electrically connected to each terminal of the test head 44 via the pogo frame 54. The probe card 64 has a large number of probes 65 corresponding to the electrodes of all devices on the wafer W to be inspected, and the measurement unit 30 inspects all devices on the wafer W simultaneously.

[0036] The chuck 34 has an adsorption surface 31 on the surface facing the probe card 64 that vacuum-adsorbs the wafer W. More specifically, the chuck 34 includes a disc-shaped chuck body 33 and a disc-shaped holding plate 35 assembled on the upper surface of the chuck body 33. The holding plate 35 is a porous material made of ceramics or the like, and its upper surface is the adsorption surface 31 that sucks and holds the wafer W. A chuck seal rubber 37 (seal ring) is provided on the upper surface of the chuck body 33 so as to surround the wafer W. The chuck seal rubber 37 functions as a "first sealing member".

[0037] The chuck 34 is detachably supported by the alignment device 32. The alignment device 32 comprises an X table 76, a Y table 78, and a Z table 80. A guide rail extending in the X direction is provided in the measurement area 10 of the housing 2 (see Figure 3), and the X table 76 is horizontally mounted so that it can move in the X direction along the guide rail. The X table 76 is driven by a moving mechanism (not shown). A guide rail extending in the Y direction is provided on the upper surface of the X table 76. The Y table 78 is horizontally mounted so that it can move in the Y direction along the guide rail. The Y table 78 is driven by a moving mechanism (not shown). Each moving mechanism is implemented by a screw feed mechanism and a servo motor to drive it, but may also be implemented by a linear motor.

[0038] The Z-table 80 is supported by the Y-table 78 so as to be able to move up and down in the Z-direction and rotate in the θ-direction. The Z-table 80 is provided with a lifting mechanism for raising and lowering the chuck 34 and a rotation mechanism for rotating the chuck 34 (not shown). The rotation mechanism is implemented, for example, by a spindle motor. The chuck 34 is detachably supported on the upper surface of the Z-table 80. With this configuration, the chuck 34 can move in the X-direction, Y-direction, Z-direction, and θ-direction. By moving the chuck 34, the relative position of the wafer W and the probe card 64 can be adjusted.

[0039] As shown in Figure 6, during the probing process, the Z-table 80 is moved, and the chuck 34 is moved (raised) toward the probe card 64. At this time, the chuck seal rubber 37 comes into contact with the lower surface of the head stage 62, forming a sealed space S surrounded by the chuck 34, probe card 64, head stage 62, and chuck seal rubber 37. The chuck seal rubber 37 is interposed between the head stage 62 and the chuck 34. The sealed space S corresponds to the "first sealed space" and is contained within the inspection area 40, with the probe 65 positioned inside.

[0040] The chuck body 33 is provided with a suction passage 82 for evacuating the wafer W attached to the suction surface 31. The suction passage 82 is connected to a vacuum source 100 via a pipe 90. By driving the vacuum source 100, vacuuming is performed, and the resulting suction force is applied to the wafer W through the porous structure of the holding plate 35. The wafer W is then attracted to the suction surface 31 by the negative pressure generated at this time. A control valve 102 is provided in the pipe 90. The control valve 102 adjusts the suction force (negative pressure) applied to the suction surface 31 of the chuck 34. In this embodiment, the control valve 102 consists of a solenoid-driven electromagnetic valve, but it may also be a motor-driven electric valve. The control unit 20 controls the operation of the control valve 102.

[0041] The headstage 62 (holding member) is provided with a suction passage 84 that communicates with the sealed space S. The suction passage 84 is connected to the vacuum source 100 via piping 92 (external piping). A regulator 104 and a pressure sensor 106 are provided in piping 92. The regulator 104 is an electro-pneumatic regulator that adjusts the fluid flow in piping 92 so that the negative pressure acting on the sealed space S (first sealed space) approaches the set pressure. The regulator 104 is installed outside the housing 2 (i.e., in a normal temperature environment) so as not to be affected by temperature changes inside the prober 1 in order to maintain normal operation.

[0042] The pressure sensor 106 detects the internal pressure of the regulator 104, that is, the pressure being adjusted by the regulator 104. The control unit 20 functions as a "pressure control unit" and calculates the set value of the negative pressure acting on the sealed space S (set pressure), and outputs a pressure control command to the regulator 104. Upon receiving the control command, the regulator 104 autonomously operates to bring its internal pressure, and thus the negative pressure in the sealed space S, closer to the set pressure. Specifically, the set pressure is called the "target pressure," and the pressure detected by the pressure sensor 106 is called the "actual pressure," and feedback control is performed to bring the deviation between the target pressure and the actual pressure closer to zero.

[0043] The pogo frame 54 is provided with a suction passage 86 that communicates with spaces S1 and S2. The suction passage 86 is connected to the vacuum source 100 via piping 94. A control valve 108 is provided in piping 94. The control valve 108 adjusts the suction force (negative pressure) acting on spaces S1 and S2 (second sealed spaces). In this embodiment, the control valve 108 is a solenoid valve, but it may also be an electric valve. The control unit 20 controls the operation of the control valve 108.

[0044] The prober 1 further includes a gas supply unit 110 that supplies dry air to the sealed space S (first sealed space). The gas supply unit 110 includes a gas supply source 112 and a flow control valve 114. The chuck 34 is provided with a gas supply passage 83 that communicates with the sealed space S. The gas supply passage 83 is connected to the gas supply source 112 via piping 96. The dry air supplied from the gas supply source 112 is discharged into the sealed space S from the open end of the gas supply passage 83 (i.e., the surface of the chuck 34).

[0045] A flow control valve 114 is provided in the piping 96. In this embodiment, the flow control valve 114 is a solenoid valve, but it may also be an electric valve. The gas supply source 112 has a tank for storing pressurized dry air. The flow control valve 114 adjusts the flow rate of dry air supplied from the gas supply source 112 to the sealed space S. The control unit 20 controls the opening degree of the flow control valve 114 during probing to control the flow rate of dry air.

[0046] The vacuum source 100 and regulator 104 operate, reducing the pressure in the sealed space S, and the chuck 34 is pulled towards the probe card 64. By creating a negative pressure state in the sealed space S, the chuck seal rubber 37 ensures that the sealed space S is sealed, and the head stage 62 holds the chuck 34 in place. In addition, each probe 65 of the probe card 64 can come into contact with each device on the wafer W, allowing for inspection.

[0047] At this time, by detaching the Z-table 80 from the chuck 34 as shown in the figure, the alignment device 32 can be used for other measuring units 30. As described above, since the alignment device 32 is shared by each stage of the measuring units 30, wafer W can be transferred between other measuring units 30 while inspection is being performed in one measuring unit 30.

[0048] Furthermore, the head stage 62 (holding member) is provided with a passage 88 that connects the sealed space S with the external space (inspection area 40). An opening / closing mechanism 120 is provided to open and close the passage 88. The opening / closing mechanism 120 includes an air cylinder 122 and a cylinder drive unit 124. The cylinder drive unit 124 drives the air cylinder 122, which operates the shutter 126 and opens and closes the passage 88. The control unit 20 controls the cylinder drive unit 124.

[0049] When probing begins, the communication passage 88 is closed to allow for vacuuming of the sealed space S. When probing ends, the communication passage 88 is opened to release the negative pressure in the sealed space S. This allows the chuck 34 to be quickly detached from the head stage 62.

[0050] Next, the condensation prevention method in this embodiment will be described in detail. Figure 7 is a diagram illustrating the general method for controlling negative pressure during probing. Figure 7(A) shows an unstable negative pressure state in the sealed space S, and Figure 7(B) shows a stable negative pressure state in the sealed space S.

[0051] As shown in Figure 7(A), a value appropriate for holding the chuck 34 (set pressure P) is set as the negative pressure Pa of the sealed space S during probing. The regulator 104 operates autonomously to ensure that the negative pressure Pa becomes the set pressure P. However, the set pressure P is set to be smaller than either the negative pressure Pb acting on the space S2 (second sealed space) adjacent to the sealed space S, or the negative pressure Pc acting on the suction surface 31 of the chuck 34.

[0052] In this embodiment, the negative pressure Pa is set to -5kPa, the negative pressure Pb to -60kPa, and the negative pressure Pc to -90kPa. This is based on considerations such as the possibility that if the negative pressure Pa is greater than the negative pressure Pb, the probe card 64 may detach from the pogo frame 54, and if the negative pressure Pa is greater than the negative pressure Pc, the wafer W may detach from the adsorption surface 31.

[0053] In this embodiment, the set pressure P is calculated using the following formula (1).

number

[0054] k, N, Z included in the terms preceding the differential pressure correction value P1 in equation (1) above OD M and A are all parameters related to the holding force of the chuck 34 and are included in the conventional method for calculating the set pressure. In this embodiment, in order to stably maintain the negative pressure in the sealed space S, this conventional set pressure is corrected by a differential pressure correction value P1. Specifically, when setting the differential pressure correction value P1, the following influences are considered as factors causing pressure fluctuations in the sealed space S.

[0055] 1) Effects of dry air supply As described above, dry air is supplied from the gas supply passage 83 at a positive pressure Pd to prevent condensation. This positive pressure Pd is a factor that reduces the negative pressure Pa in the sealed space S. In other words, a loss of negative pressure occurs due to the discharge pressure (positive pressure) of the dry gas into the sealed space S.

[0056] 2) Effects of pressure difference with adjacent areas As described above, since the negative pressures Pb and Pc in the regions adjacent to the sealed space S are considerably larger than the negative pressure Pa, the pressure in the sealed space S may escape to the space S2 or the adsorption surface 31 side where the negative pressure is greater, potentially causing the negative pressure Pa in the sealed space S to exceed the set pressure. As a result, this may not be in sync with the adjustment of the regulator 104, and air may flow back into the sealed space S from the regulator 104 side.

[0057] Furthermore, although the seal ring 63 and chuck seal rubber 37 ensure a seal between the components forming the sealed space S, if the negative pressure in the sealed space S increases, the pressure difference with the outside may increase, potentially allowing outside air to enter.

[0058] 3) Effects of pressure loss As described above, since the pipe 92 connecting the sealed space S and the regulator 104 has a certain length, there is a considerable distance between the sealed space S and the pressure sensor 106. Therefore, there is a certain delay before the pressure change in the sealed space S is transmitted to the regulator 104. In addition, there is pressure loss in the pipe 92 (more specifically, fluid pressure loss between the regulator 104 and the sealed space S). As a result, there is a delay or insufficient adjustment of the pressure by the regulator 104, and there is a possibility that air will flow back from the regulator 104 into the sealed space S.

[0059] In this embodiment, taking the above effects into consideration, the differential pressure correction value P1 is set as shown in Figure 7(B) so that no backflow of fluid occurs from the piping 92 to the sealed space S during probing (while the regulator 104 and gas supply unit 110 are operating). That is, the differential pressure correction value P1 is set to correct the set pressure P as described later, in order to suppress the instability of the negative pressure in the sealed space S due to the above-mentioned effects and to stably prevent the occurrence of condensation.

[0060] The differential pressure correction value P1 is set as a fixed value corresponding to the flow rate of dry air supplied to the sealed space S and is determined experimentally in advance. As described above, due to the above influence, a difference (differential pressure) occurs between the pressure detected by the pressure sensor 106 and the actual pressure in the sealed space S. As a result, there is a possibility that the control of the regulator 104 may be affected by this differential pressure. This differential pressure changes according to the flow rate of dry air (the discharge pressure of dry air into the sealed space S).

[0061] In this embodiment, a differential pressure correction value P1 based on this differential pressure is set and reflected in the setting of the set pressure P so as not to be affected by the above. In addition, the flow rate of the dry air is set in order to ensure the supply of dry air itself despite the differential pressure. Specifically, the gas supply unit 110 is adjusted so that the flow rate of the dry air is a predetermined flow rate of 1 L / min or more. This predetermined flow rate is set within a range in which the absolute value of the discharge pressure of the dry air is smaller than the absolute value of the set pressure P. That is, the flow rate is set within a range that does not affect the adsorption (vacuum contact) between the chuck 34 and the head stage 62 due to the negative pressure in the sealed space S.

[0062] Figure 8 shows the results of experiments conducted to set the differential pressure correction value. Figure 8(A) shows the case where dry air is supplied to the sealed space S (with purging), and Figure 8(B) shows the case where dry air is not supplied to the sealed space S (without purging).

[0063] In the experiment to determine the differential pressure correction value P1, the pressure detected by the pressure sensor 106 attached to the regulator 104 and the pressure detected by a pressure sensor experimentally installed in the chamber (sealed space S) were measured, and the differential pressure was plotted. In addition, two measurement conditions were set: with a dry air purge of 1100 mL / min (Figure 8(A)) and without a purge (Figure 8(B)). This purge amount was set with a slight margin relative to 1 L / min. It should be noted that the actual operating pressure (negative pressure) in the sealed space S is assumed to be on the atmospheric pressure side of -10 kPa.

[0064] Since a multi-probe was used in the experiment, similar tests were performed on multiple chucks (stages: stg). The maximum variation in differential pressure measured for each chuck was 40 Pa. In the case of a specification that applies a 100 μm overdrive at 4 kPa, this pressure difference corresponds to 2 μm, which was found to be negligible. However, compared to the differential pressure without purging, a pressure difference of 125 Pa occurred. This corresponds to 6 μm in the same specification as above, which is insufficient for the accuracy of the overdrive amount. Therefore, when calculating the set pressure P, a differential pressure correction value of 125 Pa was added as P1 to correct the value and bring it closer to the theoretical overdrive amount.

[0065] Figures 9 and 10 are flowcharts illustrating the overview of the probing process. Figures 11 and 12 are diagrams illustrating the operation of prober 1 during the probing process. Figures 11(A) to (F) show the processing steps from the start of the probing process to the actual probing, and Figures 12(A) to (C) show the processing steps after the inspection is completed. The flow of the probing process will be explained below based on Figures 9 and 10, with appropriate reference to Figures 11 and 12.

[0066] As shown in Figure 9, the control unit 20 first loads the wafer W onto the chuck 34 supported by the alignment device 32 (S10), and simultaneously performs positive pressure control of the regulator 104 and supplies dry air (S12: Figure 11(A)). At this time, the vacuum source 100 is driven to attract the wafer W to the chuck 34. The chuck 34 is separated from the head stage 62, and an open space S0 is formed between the chuck 34 and the head stage 62. The communication passage 88 is opened.

[0067] The control unit 20 drives the gas supply unit 110 to supply dry air to the open space S0 for a predetermined time (for example, about 3 seconds) to dry the atmosphere around the chuck 34. At this time, the regulator 104 is made to positive pressure so that the removed moisture is not led to the vacuum source 100. In other words, the gas in the piping 92 is blown out towards the open space S0.

[0068] After a predetermined time has elapsed (Y in S14), the control unit 20 temporarily stops controlling the regulator 104 and driving the gas supply unit 110 (S16), and drives the alignment device 32 to perform the alignment process (S18). That is, it adjusts the horizontal (XY direction) and rotational (θ direction) positions of the wafer W so that each of the multiple devices and multiple probes 65 on the wafer W faces the other.

[0069] Next, the control unit 20 drives the alignment device 32 to determine the contact position and height with the device, taking into account the amount of overdrive of the probe 65 (S20). Then, after moving the chuck 34 to a standby position directly below the probe card 64 (S22: Figure 11(B)), it is moved to the contact position (S24: Figure 11(C)).

[0070] Next, the control unit 20 drives the opening / closing mechanism 120 to close the shutter 126 and close the communication passage 88, and drives the gas supply unit 110 to start supplying dry air to the sealed space S (S26: Figure 11(C)). It also starts depressurizing the sealed space S using the regulator 104 (S28). In other words, the communication passage 88 is closed and the supply of dry gas is started prior to the supply of negative pressure to the sealed space S. Then, the control unit 20 separates the chuck 34 from the Z table 80 of the alignment device 32 (S30), and depressurizes the sealed space S while correcting the set pressure P using the differential pressure correction value P1 (differential pressure correction) until the wafer W reaches the contact height (i.e., until it reaches the set override amount) (S32: Figure 11(D)).

[0071] The alignment device 32, with the chuck 34 separated, moves to another measurement unit 30 (Figure 11(E)). The control unit 20 performs inspection (wafer test) using the test head 44 (S34: Figure 11(F)). At this time, as described above, the set pressure P is corrected (differential pressure correction) using the differential pressure correction value P1. The control unit 20 continues to control the regulator 104 based on the corrected set pressure P and performs the wafer test.

[0072] As shown in Figure 10, when the wafer test is completed (Y in S36), the control unit 20 moves the Z-table 80 of the alignment device 32 to the receiving position of the chuck 34 (S38: Figure 12(A)). The control unit 20 drives the opening / closing mechanism 120 to open the shutter 126 and open the communication passage 88 (S40), and fixes the chuck 34 to the Z-table 80 (S42: Figure 12(B)). Subsequently, the supply of dry air is stopped (S44).

[0073] In other words, when the sealed state of the sealed space S is released, the communication passage 88 is opened, and after the communication passage 88 is opened, the supply of dry gas is stopped. Subsequently, the chuck 34 is retracted from the head stage 62, and the wafer W is unloaded from the chuck 34 (S46: Figure 12(C)).

[0074] Figure 13 shows the effect of differential pressure correction in the embodiment. Figure 13(A) shows a magnified photograph of a specific location on the wafer surface when differential pressure correction is performed. Figure 13(B) shows a magnified photograph of the same location on the wafer surface when differential pressure correction is not performed, as a comparative example.

[0075] As is clear from comparing Figure 13(A) and Figure 13(B), in the comparative example, numerous scattered ice formations due to condensation can be observed on the surface of wafer W (Figure 13(B)). In contrast, no such ice formations occurred in this embodiment (Figure 13(A)). In other words, the effect of differential pressure correction in this embodiment was confirmed.

[0076] As described above, in this embodiment, when probing is performed in a low-temperature environment, dry air is supplied to the sealed space S where the wafer W and probe 65 are placed. This prevents or suppresses condensation on the electrodes of the wafer W and probe 65. In particular, since a space S2 with a larger negative pressure and a suction passage 82 are located adjacent to the sealed space S, the negative pressure in the sealed space S tends to become larger than the set value due to their influence. On the other hand, positive pressure is supplied by dry air. As a result, the negative pressure in the sealed space S tends to change, and the set pressure P is corrected by a differential pressure correction value P1 that takes these factors into account. This prevents backflow of fluid from the external piping to the sealed space S and also prevents condensation from occurring due to pressure fluctuations in the sealed space S. In other words, the occurrence of condensation during probing can be stably prevented.

[0077] Although preferred embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to these specific embodiments, and various modifications are possible within the scope of the technical concept of the present invention.

[0078] [Differentiation] In the above embodiment, an example was shown in which a pressure sensor 106 is provided on the regulator 104. The pressure sensor 106 may be installed externally on the regulator 104, or it may be built into the regulator 104. Alternatively, the pressure sensor 106 may be separated from the regulator 104 and installed near the regulator 104 in the piping 92.

[0079] In the above embodiment, an example was shown in which dry air was used as the dry gas, but a dry inert gas or other dry gas may also be used.

[0080] In the above embodiment, a multi-stage prober with multiple measuring units 30 was exemplified, but a single-stage prober having a single measuring unit 30 may also be used. In that case as in the above embodiment, the control unit controls the flow rate of the dry gas to achieve the set dew point in each area.

[0081] In the above embodiment, the probe card 64 is equipped with a number of probes 65 corresponding to all devices on wafer W, and an example was shown in which all devices on wafer W are inspected simultaneously. In a modified example, the probe card may be equipped with a number of probes corresponding to some of the devices on the wafer, and a configuration may be adopted in which the devices on the wafer are inspected sequentially.

[0082] Although not described in the above embodiment, the pipes 90, 92, and 94 shown in Figure 6 may each be individually connected to the vacuum source 100.

[0083] In the above embodiment, we mainly described measures to prevent condensation on the wafer W, but the same condensation prevention effect can be obtained for the probe card 64 as well.

[0084] In the above embodiment, probing in a low-temperature environment was mainly described, but it goes without saying that testing at multiple temperature ranges from low to high is also possible.

[0085] It should be noted that the present invention is not limited to the embodiments and modifications described above, and the components can be modified and implemented without departing from the spirit of the invention. Various inventions may be formed by appropriately combining the multiple components disclosed in the embodiments and modifications described above. In addition, some components may be deleted from all the components shown in the embodiments and modifications described above. [Explanation of Symbols]

[0086] 1 Probe, 10 Measurement area, 12 Loader area, 14 Storage area, 15 Transport area, 20 Control unit, 22 Operation panel, 24 Transport unit, 26 Arm, 30 Measurement section, 31 Suction surface, 32 Alignment device, 34 Chuck, 35 Holding plate, 36 Partition wall, 37 Chuck seal rubber, 40 Inspection area, 42 Equipment storage area, 44 Test head, 50 Heat exchanger, 54 Pogo frame, 62 Head stage, 63 Seal ring, 64 Probe card, 65 Probe, 68 Pogo pin, 70 Seal ring, 72 Seal ring, 82 Suction passage, 83 Gas supply passage, 84 Suction passage, 86 Suction passage, 88 Connecting passage, 90 Piping, 92 Piping, 94 Piping, 96 Piping, 100 Vacuum source, 102 Control valve, 104 Regulator, 106 Pressure sensor, 108 control valve, 110 gas supply unit, 112 gas supply source, 114 flow control valve, 120 opening / closing mechanism, 122 air cylinder, 124 cylinder drive unit, 126 shutter, S sealed space, S2 space, W wafer.

Claims

1. A retaining member for holding the probe card, A chuck having a suction surface for vacuum adsorption of a wafer on the surface facing the probe card, A sealing member interposed between the holding member and the chuck, forming a sealed space on the inside where the probe connected to the probe card is positioned, A suction passage connected to a vacuum source via external piping for reducing the pressure in the sealed space, A regulator connected to the external piping adjusts the fluid flow in the external piping so that the negative pressure acting on the sealed space approaches a set pressure, A gas supply unit that supplies dry gas to the aforementioned sealed space, The system comprises a pressure control unit that controls the regulator, By creating a negative pressure state in the sealed space, the sealing state of the sealed space by the sealing member is achieved, and the chuck is held by the holding member. The gas supply unit supplies dry gas when the regulator is operating. The pressure control unit is a prober that corrects the set pressure according to the flow rate of the dry gas so that backflow of fluid from the external piping to the sealed space does not occur during the operation of the regulator and the gas supply unit.

2. The sealing member includes a first sealing member that forms the first sealed space which is the sealed space, The system further comprises a second sealing member interposed between the holding member and the probe card inside the first sealed space, forming a second sealed space on which pogo pins connected to the probe card are arranged, The prober according to claim 1, wherein the set pressure is set as a negative pressure smaller than either the negative pressure acting on the second sealed space or the negative pressure acting on the adsorption surface.

3. The prober according to claim 1 or 2, wherein the gas supply unit adjusts the flow rate of dry gas to a predetermined flow rate of 1 L / min or more.

4. The prober according to claim 3, wherein the predetermined flow rate is set within a range in which the absolute value of the discharge pressure of the dry gas is smaller than the absolute value of the set pressure.

5. The prober according to claim 1 or 2, wherein the pressure control unit corrects the set pressure based on the discharge pressure of dry gas from the gas supply unit.

6. The prober according to claim 5, wherein the pressure control unit corrects the set pressure based on the fluid pressure loss between the regulator and the sealed space in the external piping.

7. A passage connecting the inspection area containing the sealed space and the sealed space, The system includes an opening and closing mechanism for opening and closing the aforementioned connecting passage, The opening and closing mechanism closes the communication passage prior to supplying negative pressure to the sealed space. The prober according to claim 1 or 2, wherein the gas supply unit starts supplying dry gas prior to supplying negative pressure to the sealed space.

8. The opening and closing mechanism opens the communication passage when releasing the sealed state of the sealed space. The prober according to claim 7, wherein the gas supply unit stops supplying dry gas after the communication passage is opened.

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