JP2019035653A - Disconnection detector, disconnection detection method, and probe tip detector - Google Patents

Abstract

To provide a disconnection detector, a disconnection detection method, and a probe tip detector capable of precisely determining presence or absence of a signal line outputted from a linear variable differential transformer.SOLUTION: A disconnection detector includes: a signal acquisition part for acquiring two kinds of signals outputted from a linear variable differential transformer via individual signal lines for each secondary coil; and a determination part that previously acquires correspondence between presence or absence of disconnection for each signal line and both voltage values of two kinds of signals changing according to the presence or absence of disconnection, and performs first determination processing for determining presence or absence of disconnection for each signal line by referring the correspondence, based on both voltage values of two kinds of signals acquired by the signal acquisition part.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a disconnection detection device, a disconnection detection method, and a probe tip detection device that detect a disconnection of a signal line of a linear variable differential transformer.

  A plurality of semiconductor chips having the same electric element circuit are formed on the surface of a wafer (also referred to as a semiconductor wafer). Before the wafer is cut into individual semiconductor chips with a dicer, the electrical characteristics of the individual semiconductor chips are inspected by a wafer test system. This wafer test system includes a prober and a tester (see Patent Document 1).

  A prober electrically moves a probe to an electrode (also referred to as an electrode pad) of a semiconductor chip by moving the wafer chuck and a probe card having a probe (also referred to as a probe needle) while the wafer is fixed on the wafer chuck. Make contact. The tester supplies various test signals to the electrodes of the semiconductor chip via the terminals connected to the probe, and receives and analyzes the signals output from the electrodes in response to the supply of the test signals. Inspect whether the chip operates normally.

  In the inspection of a wafer by such a wafer test system, it is necessary to accurately contact the tip of the probe of the probe card installed in the prober with the wafer. For this reason, detection of the tip position of the probe is performed as a pre-stage of the wafer inspection by the prober.

  Patent Literature 2 and Patent Literature 3 disclose a prober (referred to as a probe device) that detects the tip position of a probe using a contact-type probe tip detection device provided at a position facing the probe. By using this contact-type probe tip detection device, the tip position of the probe can be detected with high accuracy.

JP 2004-079733 A JP 2009-204492 A JP 2013-179329 A

  For example, a linear variable differential transformer (LVDT) may be used as the probe tip detection device described in Patent Document 2 and Patent Document 3. Specifically, the contact surface held so as to be movable in the Z-axis direction (vertical direction) is raised from the lower side of the probe and brought into contact with the tip of the probe. By detecting LVDT with LVDT, the tip position of the probe can be detected with high accuracy.

  By the way, the minute movement of the contact surface in the Z-axis direction is detected based on signals output from the two types of secondary coils provided in the LVDT through the signal lines. For this reason, if the signal line is disconnected, the minute movement in the Z-axis direction of the contact surface accompanying the contact with the tip of the probe cannot be detected. As a result, if the contact surface is raised too much, the probe and the contact surface may collide and the probe may be damaged.

  Therefore, the voltage values of the signals output from the two types of secondary coils of the LVDT are monitored, and based on whether or not the voltage values of the two types of signals are smaller than the individual threshold values individually determined, A method for determining whether or not a signal line is disconnected is conceivable. At this time, even if the signal line is disconnected, the voltage value detected via the signal line does not become zero but a low voltage is detected due to the capacitance of the signal line itself.

  The maximum value of the voltage detected at such disconnection may be larger than or close to the minimum value of the voltage detected when the signal line is in a normal state. As a result, it becomes difficult to set an individual threshold value for determining whether or not the signal line is disconnected. For this reason, there is a possibility that the signal line is disconnected even when the detected voltage value is larger than the individual threshold value, or there is a possibility that the signal line is normal even when the voltage value is smaller than the individual threshold value. Therefore, it is difficult to determine with high accuracy whether or not the signal line output from the LVDT is disconnected.

  The present invention has been made in view of such circumstances, and a disconnection detecting device and a disconnection detection capable of accurately determining whether or not a signal line output from a linear variable differential transformer (LVDT) is disconnected. It is an object to provide a method and a probe tip detection device.

  A disconnection detecting device for achieving the object of the present invention is to receive two types of signals respectively output from two secondary coils provided in a linear variable differential transformer via individual signal lines. Two types acquired by the signal acquisition unit by acquiring in advance the correspondence relationship between the signal acquisition unit to be acquired, the presence or absence of disconnection for each signal line, and the voltage values of both of the two types of signals that change according to the presence or absence of the disconnection And a determination unit that performs a first determination process for determining the presence or absence of disconnection for each signal line with reference to the correspondence relationship based on the voltage values of both of the signals.

  According to this disconnection detection device, even when the voltage value of the signal output from the disconnected signal line does not become zero due to the capacitance of the signal line itself, the presence or absence of disconnection of the signal line can be determined with high accuracy. Can do.

  In the disconnection detection device according to another aspect of the present invention, the determination unit individually determines whether or not there is a disconnection for each signal line based on whether or not both voltage values are smaller than a predetermined individual threshold value. A second determination process is performed. Thereby, the presence or absence of the disconnection of the signal line can be determined with high accuracy.

  In the disconnection detection apparatus according to another aspect of the present invention, a signal that is disconnected, with the smaller individual threshold of the two types of signals acquired by the signal acquisition unit as the first signal and the higher individual threshold as the second signal. When the voltage value of the first signal output from the line is the first disconnection voltage value, the individual threshold value of the first signal is the first within a range where the voltage value of the second signal is smaller than a predetermined determination threshold value. The disconnection voltage value is set to be smaller than the maximum value, the individual threshold value of the second signal is set to be larger than the maximum value of the first disconnection voltage value, and the correspondence relationship includes the disconnection of the signal line corresponding to the first signal. A first voltage range corresponding to the voltage value of the first signal is greater than the individual threshold value of the first signal and greater than the individual threshold value of the second signal. Is set to a small range and corresponds to the voltage value of the second signal. The first voltage range is set to a range smaller than the determination threshold value. Thereby, the presence or absence of disconnection of the signal line corresponding to the first signal can be determined with high accuracy.

  In the disconnection detection device according to another aspect of the present invention, when the voltage value of the first signal and the voltage value of the second signal are each outside the range of the first voltage range, the determination unit is a signal corresponding to the first signal. The presence or absence of a broken wire is determined by the second determination process. By performing the first determination process and the second determination process, it is possible to determine with high accuracy whether or not the signal line corresponding to the first signal is disconnected.

  In the disconnection detection device according to another aspect of the present invention, when the voltage value of the second signal output from the disconnected signal line is the second disconnection voltage value, the individual threshold of the first signal is the voltage of the first signal. In a range where the value is larger than the determination threshold, the voltage is set to be larger than the second disconnection voltage value, and the correspondence relationship includes the second values of both voltage values indicating that the signal line corresponding to the second signal is normal. 2 voltage ranges are included, the second voltage range corresponding to the voltage value of the first signal is set to a range larger than the determination threshold, and the second voltage range corresponding to the voltage value of the second signal is It is set in a range larger than the individual threshold value of one signal and smaller than the individual threshold value of the second signal. Thereby, the presence or absence of disconnection of the signal line corresponding to the second signal can be determined with high accuracy.

  In the disconnection detection device according to another aspect of the present invention, when the voltage value of the first signal and the voltage value of the second signal are outside the range of the second voltage range, the determination unit is a signal corresponding to the second signal. The presence or absence of a broken wire is determined by the second determination process. By performing the first determination process and the second determination process, it is possible to determine with high accuracy whether or not the signal line corresponding to the second signal is disconnected.

  In the disconnection detection device according to another aspect of the present invention, the determination threshold value is set to a value larger than the individual threshold value of the second signal.

  A probe tip detection device for achieving the object of the present invention is provided in a prober for inspecting a wafer by bringing the probe into contact with an electrode of the wafer, and in the probe tip detection device for detecting the tip of the probe, a contact surface; A moving part that moves the contact surface relative to the probe from a position facing the probe, and two secondary coils according to the position of the core that moves together with the contact surface, respectively, via individual signal lines. A linear variable differential transformer that outputs two types of signals and the above-described disconnection detection device.

  According to this probe tip detection device, the presence or absence of a signal line breakage can be determined with high accuracy, so that the contact of the probe with the contact surface can be reliably detected, and the collision between the contact surface and the prober. Can prevent the prober from being damaged.

  The probe tip detection device according to another aspect of the present invention includes a contact detection unit that detects contact of the tip of the probe with the contact surface based on two types of signals output for each secondary coil.

  In order to achieve the object of the present invention, a disconnection detection method includes two types of signals respectively output from two secondary coils provided in a linear variable differential transformer via individual signal lines. The two types acquired in the signal acquisition step by acquiring in advance the correspondence relationship between the signal acquisition step to be acquired, the presence or absence of disconnection for each signal line, and the voltage values of both of the two types of signals that change according to the presence or absence of disconnection And a first determination processing step of determining the presence or absence of disconnection for each signal line with reference to the correspondence relationship based on the voltage values of both signals.

  In the disconnection detection method according to another aspect of the present invention, a second determination for individually determining the presence or absence of disconnection for each signal line based on whether or not both voltage values are smaller than a predetermined individual threshold value. It has processing steps.

  The present invention can determine the presence or absence of disconnection of a signal line output from a linear variable differential transformer with high accuracy.

It is the schematic of the wafer test system which functions as a disconnection detection apparatus and probe tip detection apparatus of this invention. It is sectional drawing of a probe height detector. It is the block diagram which showed a part of electrical structure of the prober. It is the graph which showed the voltage value of the 1st signal and the voltage value of the 2nd signal which change according to the presence or absence of each disconnection of the 1st signal line and the 2nd signal line. It is the flowchart which showed the flow of the disconnection detection of the 1st signal line and the 2nd signal line by a prober. It is the graph which showed the voltage value of both of two types of both signals which change according to the presence or absence of each disconnection of a 1st signal line and a 2nd signal line, Comprising: Both voltage values in the normal position range were shown. It is a graph. It is the flowchart which showed the flow in the case of performing disconnection detection (1st determination process and 2nd determination process) of the 1st signal line and the 2nd signal line limited within the range of a normal position range.

[Configuration of wafer test system]
FIG. 1 is a schematic diagram of a wafer test system 9 that functions as a disconnection detection device and a probe tip detection device according to the present invention. Hereinafter, the upper and upper surfaces in the Z-axis direction, which is the vertical direction in the drawing, are appropriately referred to as “upper” and “upper surface”, and the lower and lower surfaces in the Z-axis direction are appropriately referred to as “lower” and “lower surface”.

  The wafer test system 9 inspects the electrical characteristics of each of a plurality of semiconductor chips (not shown) formed on the wafer W. The wafer test system 9 includes a prober 10 and a tester 30.

  The prober 10 brings the probe 25 into contact with the electrode of each semiconductor chip (not shown) on the wafer W. The tester 30 is electrically connected to the probe 25, and inspects the characteristics of each semiconductor chip by applying a voltage to each semiconductor chip for electrical inspection of each semiconductor chip. The prober 10 functions as the probe tip detection device of the present invention.

  The prober 10 includes a base 11, a base 12, a Y stage 13, an X stage 14, a Zθ stage 15, a wafer chuck 16, a probe position detection camera 18, a probe height detector 20, and a height. Adjustment mechanisms 21 and 27, a wafer alignment camera 19, a head stage 22, a card holder 23, a probe card 24, and a probe 25 are provided.

  A substantially flat base 12 is fixed to the upper surface of the base 11. Note that a leg member may be used instead of the base 11, or the base 11 may be omitted.

  A substantially flat Y stage 13 is supported on the upper surface of the base 12 so as to be movable in the Y-axis direction via a Y moving portion (not shown). The Y moving part is provided on the upper surface of the base 12 and is parallel to the Y axis, a slider provided on the lower surface of the Y stage 13 and engaged with the guide rail, and moves the Y stage 13 in the Y axis direction. A drive mechanism such as a motor. By driving the Y moving unit, the Y stage 13 and the later-described X stage 14 and Zθ stage 15 are moved integrally on the base 12 in the Y-axis direction.

  A substantially flat plate-like X stage 14 is supported on the upper surface of the Y stage 13 through an X moving unit (not shown) so as to be movable in the X axis direction. The X moving unit is provided on the upper surface of the Y stage 13 and parallel to the X axis, the slider provided on the lower surface of the X stage 14 and engaged with the guide rail, and moves the X stage 14 in the X axis direction. And a drive mechanism such as a motor to be driven. By driving the X moving unit, the X stage 14 and a later-described Zθ stage 15 are moved integrally on the Y stage 13 in the X-axis direction.

  A Zθ stage 15 and height adjusting mechanisms 21 and 27 are provided on the upper surface of the X stage 14. A Zθ moving unit (not shown) is provided inside the Zθ stage 15. A wafer chuck 16 is held on the upper surface of the Zθ stage 15 via a Zθ moving unit (not shown). The Zθ moving unit includes, for example, an elevating mechanism that can move the upper surface of the Zθ stage 15 in the Z-axis direction, and a rotating mechanism that rotates the upper surface around the Z-axis. Therefore, the Zθ moving unit moves the wafer chuck 16 held on the upper surface of the Zθ stage 15 in the Z-axis direction and rotates it around the Z-axis axis.

  The wafer W is held on the chuck upper surface 16a which is the upper surface of the wafer chuck 16 by various holding methods such as vacuum suction. Further, the wafer chuck 16 is provided with a temperature adjusting unit (not shown) for adjusting the temperature of the wafer W held on the chuck upper surface 16a.

  The wafer chuck 16 is supported by the Y stage 13, the X stage 14, and the Zθ stage 15 so as to be movable with respect to the base 12 in the XYZ axis direction, and is also supported so as to be rotatable about the Z axis. Has been. Thereby, the wafer W held by the wafer chuck 16 and a probe 25 described later can be relatively moved.

  The height adjustment mechanism 21 moves the probe position detection camera 18 described later up and down in the Z-axis direction. Further, the height adjustment mechanism 27 moves up and down in the Z-axis direction of a probe height detector 20 described later. The height adjusting mechanisms 21 and 27 may be any known linear moving mechanism, and for example, a linear guide mechanism and a ball screw mechanism are used.

  The head stage 22 forms, for example, a top plate of a housing (not shown) of the prober 10, and is supported above the wafer chuck 16 (wafer W) by a support (not shown). The head stage 22 is formed in a substantially annular shape, and a substantially annular card holder 23 for holding the probe card 24 is provided at the center thereof. Therefore, the head stage 22 holds the outer periphery of the card holder 23, and the card holder 23 holds the outer periphery of the probe card 24. That is, the head stage 22 holds the probe card 24 via the card holder 23.

  The probe card 24 has a plurality of probes 25. These probes 25 are arranged on the probe card 24 in a pattern corresponding to the arrangement pattern of the electrodes of each semiconductor chip (not shown) of the wafer W to be inspected. The card holder 23 and the probe card 24 are exchanged according to the type of semiconductor chip.

  The probe position detection camera 18 is attached to a height adjustment mechanism 21 on the X stage 14. The probe position detection camera 18 is, for example, a camera equipped with a needle alignment microscope, and photographs the probe 25 of the probe card 24 from below. Based on the image of the probe 25 photographed by the probe position detection camera 18, the position of the probe 25 can be detected. Specifically, the XY coordinates of the tip position of the probe 25 are detected from the position coordinates of the probe position detection camera 18, and the Z coordinate of the tip position of the probe 25 is detected from the focal position of the probe position detection camera 18.

  The probe position detection camera 18 can be moved in the XY axis direction integrally with the wafer chuck 16 by the Y stage 13 and the X stage 14. The probe position detection camera 18 is moved up and down in the Z-axis direction by the height adjusting mechanism 21 as described above.

  The wafer alignment camera 19 is supported by a post (not shown) provided on the base 12 at a position lateral to the probe card 24 and above the wafer chuck 16. The wafer alignment camera 19 can be moved in the Z-axis direction by a camera lifting mechanism (not shown) such as a linear guide mechanism and a ball screw mechanism.

  The wafer alignment camera 19 images the semiconductor chip (not shown) of the wafer W held on the wafer chuck 16 from above. Based on the image of the semiconductor chip taken by the wafer alignment camera 19, the position of the electrode of the semiconductor chip can be detected. Thereby, based on the information obtained by the wafer alignment camera 19 and the position information of the tip of the probe 25 obtained by the probe position detection camera 18, the two in the XY plane between the probe 25 and the electrode of the semiconductor chip of the wafer W are obtained. Dimensional alignment (alignment) can be performed.

  The probe height detector 20 functions as a probe tip detection device of the present invention together with the LVDT control unit 51 and the overall control unit 60 shown in FIG. The probe height detector 20 is attached to the above-described height adjustment mechanism 27 on the X stage 14. In FIG. 1, the probe height detector 20 is illustrated in a simplified manner, and the detailed structure thereof will be described later with reference to FIG.

  The probe height detector 20 detects the height of the tip of the probe 25 from the reference plane that serves as a reference for the height of the probe position detection camera 18. The probe height detector 20 is a so-called contact-type detector, and detects the height of the tip of the probe 25 by physically contacting the tip of the probe 25. Here, the reference plane is a plane that serves as a reference for the height of the prober 10 as a whole, and is arbitrarily set. For example, the reference plane is set on the upper surface of the X stage 14.

  The probe height detector 20 includes a contact surface 20a and an LVDT 106 (see FIG. 2) that is a linear variable differential transformer. The probe height detector 20 raises the contact surface 20a toward the probe 25 from a position opposite to the probe 25, that is, from below the probe 25, and accompanies this contact when the contact surface 20a contacts the probe 25. The LVDT 106 detects minute movement of the contact surface 20a in the Z-axis direction (downward). Thereby, information on the height of the tip of the probe 25 is obtained based on the signal output from the LVDT 106 and the signal related to the height output from the height adjustment mechanism 27. That is, the height of the contact surface 20a from the reference surface when the tip of the probe 25 comes into contact with the contact surface 20a can be detected as the height of the tip of the probe 25.

  The above-described height adjustment mechanism 21 changes the height of the probe position detection camera 18 from the reference plane based on the detection result of the height of the tip of the probe 25. That is, the height adjustment mechanism 21 adjusts the probe position detection camera 18 to a height away from the tip of the probe 25 by a working distance based on the detection result of the height of the tip of the probe 25. In this way, by adjusting the height of the probe position detection camera using the height of the probe tip once detected by the probe height detector 20 or the like, the probe position detection camera 18 is prevented from being raised too much. Is done. As a result, the probe position detection camera 18 is prevented from colliding with the tip of the probe 25 when the probe position detection camera 18 is raised.

  The tester 30 includes a tester body 31 and a contact ring 32 provided on the tester body 31. The probe card 24 is provided with a terminal connected to each probe 25. The contact ring 32 includes spring probes arranged in an arrangement pattern that can contact each terminal of the probe card 24. The tester body 31 is held with respect to the prober 10 by a support mechanism (not shown).

[Configuration of probe height detector]
FIG. 2 is a cross-sectional view of the probe height detector 20. The probe height detector 20 is used to detect the height of the tip of the probe 25 from the reference plane described above, and detects contact between the contact surface 20 a and the probe 25 using the LVDT 106. The probe height detector 20 includes a base 102, an air bearing 103, a vertically movable portion 104, a coil spring 105, and an LVDT 106.

  The base 102 is attached on the height adjustment mechanism 27. The base 102 is formed in a substantially annular shape, and a through hole 102a parallel to the Z-axis direction is formed at the center thereof. An air bearing 103 is provided on the upper surface of the base 102. The base 102 does not need to be mounted on the height adjusting mechanism 27, and may be mounted on the side of the height adjusting mechanism 27, for example, and can be adjusted in height by the height adjusting mechanism 27. Any one is acceptable.

  The air bearing 103 is formed in a substantially cylindrical shape and has a holding hole 103a parallel to the Z-axis direction. The position of the center of the holding hole 103a in the XY axis direction and the position of the center of the through hole 102a described above in the XY axis direction coincide with each other. Reference symbol C is a central axis passing through the centers of both the holding hole 103a and the through hole 102a. The air bearing 103 holds an up-and-down moving shaft 110 of an up-and-down movable unit 104 (described later) inserted through the holding hole 103a so as to be movable in the Z-axis direction.

  Further, the air bearing 103 is formed with an air supply hole (not shown) penetrating from the outer peripheral surface to the inner surface of the holding hole 103a, and air is supplied from the air supply source 107 into the holding hole 103a through the air supply hole. Is supplied. As a result, an air layer (not shown) is formed between the inner surface of the holding hole 103a and the outer surface of the vertical movement shaft 110, so that the vertical movement shaft 110 is guided in a non-contact manner by the air bearing 103 (holding hole 103a). .

  Further, an annular flange 103b is formed on the outer peripheral surface of the lower end portion of the air bearing 103 along the circumferential direction.

  The vertically movable portion 104 is held by the air bearing 103 so as to be movable in the Z-axis direction without contact. The vertically movable portion 104 includes a vertically moving shaft 110, a stopper ring 111, a spring receiving portion 112, a stage base 113, and a stage 114.

  As described above, the vertical movement shaft 110 is inserted into the holding hole 103a of the air bearing 103 and is held by the air bearing 103 so as to be movable in the Z-axis direction without contact. A substantially annular stopper ring 111 is fitted on the lower end of the outer peripheral surface of the vertical movement shaft 110. A spring receiving portion 112 is fixed to the upper surface of the vertical movement shaft 110.

  The outer diameter of the stopper ring 111 is formed larger than the diameter of the holding hole 103a. The spring receiving portion 112 includes a disc portion 112a and a fitting portion 112b provided on the lower surface of the disc portion 112a. The outer diameter of the disc part 112 a is formed larger than the outer diameter of the coil spring 105. The fitting portion 112 b is fitted into the opening on the upper side of the coil spring 105.

  The stage pedestal 113 is fixed to the upper surface of the spring receiving portion 112. A stage 114 is fixed to the upper surface of the stage base 113. The upper surface of the stage 114 becomes the contact surface 20a described above.

  The coil spring 105 is attached between the flange portion 103b and the spring receiving portion 112 in a state compressed in the Z-axis direction. The upper end of the air bearing 103 described above is inserted into the lower opening of the coil spring 105. Thereby, the lower end of the coil spring 105 contacts the upper surface of the flange 103b. On the other hand, the above-described fitting portion 112 b is fitted into the upper opening of the coil spring 105. For this reason, the coil spring 105 urges each part (the stage 114 and the like) of the up and down movable part 104 upward in the Z-axis direction via the spring receiving part 112. As a result, the stopper ring 111 contacts the lower opening edge of the holding hole 103a, and the height position of the stage 114 in the Z-axis direction is kept constant.

  The LVDT 106 is provided on the lower surface of the base 102. The LVDT 106 includes a core 106a such as an iron core and a coil 106b. The core 106a is fixed to the lower surface of the vertical movement shaft 110 and extends downward in the Z-axis direction. The central axis of the core 106a coincides with the above-described central axis C. Accordingly, the core 106a moves in the Z-axis direction integrally with the vertical movement shaft 110, the stage 114 (contact surface 20a), and the like.

  The coil 106b has a substantially cylindrical shape parallel to the Z-axis direction. The core 106a is inserted in the coil 106b in a non-contact manner. The coil 106b includes a primary coil 108 and two types of secondary coils 109A and 109B. The primary coil 108 is excited by an excitation signal Sig0 (also referred to as an oscillation signal) that is an AC signal input from a LVDT control unit 51 (see FIG. 3) described later via a drive signal line L0. Thereby, the magnetic flux generated from the primary coil 108 is coupled to the secondary coils 109A and 109B adjacent to the primary coil 108, respectively.

  The secondary coils 109A and 109B generate an induced voltage (also referred to as an induced voltage) due to the displacement of the core 106a in the Z-axis direction when the primary coil 108 is excited. When the core 106a moves to the secondary coil 109A side, the magnetic flux coupled to the secondary coil 109A becomes larger than the magnetic flux coupled to the secondary coil 109B. For this reason, since the induced voltage output from the secondary coil 109A increases and the induced voltage output from the secondary coil 109B decreases conversely, the differential voltage (the voltage difference between the induced voltages of the secondary coils 109A and 109B). ) Occurs.

  Further, when the core 106a moves to the secondary coil 109B side, the magnetic flux coupled to the secondary coil 109B becomes larger than the magnetic flux coupled to the secondary coil 109A. For this reason, the induced voltage output from the secondary coil 109B increases, and conversely, the induced voltage output from the secondary coil 109A decreases, so that a differential voltage is generated. Further, when the core 106a is in the initial position, that is, the position where the equal magnetic flux is coupled to the secondary coils 109A and 109B, the induced voltages output from the secondary coils 109A and 109B are equal, and the differential voltage Becomes zero.

  Therefore, when the core 106a is displaced in the Z-axis direction, for example, vibrates in the Z-axis direction, sinusoidal signals having different phases are output from the secondary coils 109A and 109B (see FIG. 4).

  A first signal line L1 is connected to the secondary coil 109A. Therefore, the first signal Sig1 based on the induced voltage output from the secondary coil 109A is input from the first signal line L1 to the LVDT controller 51 via the amplifier 50 (see FIG. 3). Further, the second signal line L2 is connected to the secondary coil 109B. Therefore, the second signal Sig2 based on the induced voltage output from the secondary coil 109B is input from the second signal line L2 to the LVDT controller 51 via the amplifier 50 (see FIG. 3). The first signal line L1 and the second signal line L2 correspond to the signal lines of the present invention. The first signal Sig1 and the second signal Sig2 are signals indicating the position (displacement) of the core 106a in the Z-axis direction.

  Based on the first signal Sig1 output from the secondary coil 109A and the second signal Sig2 output from the secondary coil 109B, the overall control unit 60 (see FIG. 3) described later in the Z-axis direction of the core 106a. Detect position. Thereby, the minute movement of the core 106a in the Z-axis direction due to the contact between the contact surface 20a and the probe 25 can be detected. Note that the position of the core 106a in the Z-axis direction means that the position of the core 106a in which the induced voltages output from the secondary coils 109A and 109B are equal (the differential voltage becomes zero) is the reference position. The amount of displacement of the core 106a from the reference position is indicated.

  Thus, since the probe height detector 20 detects the contact of the tip of the probe 25 with the contact surface 20a using the LVDT 106, the detection accuracy [contact responsiveness (sensitivity)] of the contact can be improved. . As a result, it is possible to improve the measurement accuracy of the height of the tip of the probe 25 from the above-described reference plane. Further, the amount of movement (pushing amount) in the Z-axis direction of the stage 114 and the like accompanying the contact of the tip of the probe 25 with the contact surface 20a and the pressing force in the Z-axis direction accompanying the contact can be detected with high accuracy.

[Electrical configuration of the main part of the prober 10]
FIG. 3 is a block diagram showing a part of the electrical configuration of the prober 10. FIG. 3 illustrates only the configuration related to the detection of the tip height of the probe 25 and the configuration related to the detection (determination) of the presence or absence of each disconnection of the first signal line L1 and the second signal line L2. Since the configuration related to the other control of the prober 10 such as the inspection of W is a known technique, the illustration is omitted.

  As shown in FIG. 3, the secondary coil 109A is connected to the amplifier 50 via the first signal line L1, and the secondary coil 109B is connected to the amplifier 50 via the second signal line L2.

  The amplifier 50 amplifies the first signal Sig1 input from the secondary coil 109A via the first signal line L1, and the second signal Sig2 input from the secondary coil 109B via the second signal line L2, respectively. Then, the amplified first signal Sig 1 and second signal Sig 2 (hereinafter, both signals Sig 1 and Sig 2) are output to the LVDT controller 51. The amplifier 50 may be integrated with an LVDT control unit 51 to be described later, and may be omitted if the signal levels (voltages) of both signals Sig1 and Sig2 are sufficiently high.

  The LVDT control unit 51 controls the operation of the LVDT 106 under the control of the overall control unit 60 described later. The LVDT control unit 51 includes an oscillator 51A and a signal acquisition unit 51B configured by a known signal input interface or the like. The LVDT control unit 51 may be provided in the overall control unit 60 described later. Further, by causing a CPU (Central Processing Unit) or FPGA (field-programmable gate array) to execute a predetermined control program, the CPU or FPGA is caused to function as the LVDT control unit 51 (the oscillator 51A and the signal acquisition unit 51B). May be.

  The oscillator 51A outputs the excitation signal Sig0 to the primary coil 108 via the drive signal line L0 described above under the control of the overall control unit 60 described later. Thereby, since the primary coil 108 is excited, the first signal Sig1 is output from the secondary coil 109A and the second signal Sig2 is output from the secondary coil 109B according to the displacement in the Z-axis direction of the core 106a. The That is, the LVDT 106 operates.

  The signal acquisition unit 51B acquires both signals Sig1 and Sig2 amplified from the amplifier 50, and outputs both signals Sig1 and Sig2 to the probe height detection unit 62 and the determination unit 63 of the overall control unit 60, respectively. .

  The overall control unit 60 includes, for example, various arithmetic units including a CPU or FPGA, a processing unit, a memory, and the like, and performs overall control of operations of each unit of the prober 10. The overall control includes height control of the probe height detector 20 by the height adjustment mechanism 27, control of the LVDT 106 (control of the amplitude and frequency of the excitation signal Sig0 output from the oscillator 51A), and the like.

[Functions of general control section]
The overall control unit 60 functions as a probe height detection unit 62, a determination unit 63, and a storage unit 65 by executing a predetermined control program. As described above, among the various functions of the overall control unit 60, the function related to the detection of the tip height of the probe 25 and the detection of the presence or absence of each of the first signal line L1 and the second signal line L2 ( Since functions other than the function related to (determination) are well-known techniques, they are not shown.

  The probe height detection unit 62 functions as the contact detection unit of the present invention together with the probe height detector 20 described above. In addition to the signal acquisition unit 51B, a height adjustment mechanism 27 is connected to the probe height detection unit 62.

  The probe height detector 62 detects a minute movement in the Z-axis direction of the core 106a accompanying the contact of the tip of the probe 25 with the contact surface 20a based on both signals Sig1 and Sig2 input from the signal acquisition unit 51B. Thereby, the contact of the tip of the probe 25 to the contact surface 20a is detected. Then, when the contact of the tip of the probe 25 with the contact surface 20a is detected, the probe height detection unit 62 detects the probe 25 from the reference surface based on a signal related to the height input from the height adjustment mechanism 27. Detect the height of the tip.

  The determination unit 63 constitutes the disconnection detection device of the present invention together with the signal acquisition unit 51B described above. That is, the LVDT control unit 51 and the overall control unit 60 constitute the disconnection detection device of the present invention. The determination unit 63 sets the voltage value V1 of the first signal Sig1 and the voltage value V2 of the second signal Sig2 input from the signal acquisition unit 51B, that is, the voltage values V1 and V2 of both of the two types of signals Sig1 and Sig2. Based on this, it is determined whether or not each of the first signal line L1 and the second signal line L2 (for each signal line) is disconnected.

  Specifically, the determination unit 63 performs a first determination process and a second determination process. Although the details of the first determination process will be described later, the determination unit 63 determines whether or not the first signal line L1 is disconnected based on both voltage values V1 and V2, and based on both voltage values V1 and V2. Determination processing for determining whether or not the second signal line L2 is disconnected.

<Second determination process>
In the second determination process, the voltage values V1 and V2 of the two types of both signals Sig1 and Sig2 input from the signal acquisition unit 51B to the determination unit 63 are determined as individual thresholds determined in advance for both signals Sig1 and Sig2. This is a determination process in which the determination unit 63 individually determines whether or not the first signal line L1 and the second signal line L2 are disconnected based on whether or not the output signal is smaller than the second signal line L2. In the present specification, “smaller than the individual threshold” means less than the individual threshold, and “greater than the individual threshold” means more than the individual threshold.

  Specifically, the determination unit 63 determines whether or not the first signal line L1 is disconnected based on whether or not the voltage value V1 of the first signal Sig1 is lower than a predetermined first individual threshold Th1. Further, the determination unit 63 determines whether or not the second signal line L2 is disconnected based on whether or not the voltage value V2 of the second signal Sig2 is lower than a predetermined second individual threshold Th2. Since the first individual threshold Th1 and the second individual threshold Th2 are stored in advance in the storage unit 65, the determination unit 63 refers to the first individual threshold Th1 and the second individual threshold Th2 in the storage unit 65, A second determination process is performed.

  In addition to the control program, the first individual threshold Th1, and the second individual threshold Th2, the storage unit 65 includes a determination threshold Th3, a first voltage range R1, and a second voltage range R2, which will be described in detail later. Stored in advance.

  FIG. 4 is a graph showing the voltage value V1 of the first signal Sig1 and the voltage value V2 of the second signal Sig2 that change depending on whether or not each of the first signal line L1 and the second signal line L2 is disconnected. . The horizontal axis of the graph indicates the position (mm) of the core 106a in the Z-axis direction, that is, the displacement amount (mm) of the core 106a from the reference position described above. The amount of displacement in the Z-axis direction includes the amount by which the vertical movement shaft 110 or the like is pushed downward, and the amount by which the vertical movement shaft 110 or the like is drawn upward. The vertical axis of the graph is voltage (mV).

  In the graph, “V1 (L1 normal)” indicates the voltage value V1 of the first signal Sig1 output from the normal first signal line L1, and “V1 (L1 disconnection)” indicates the disconnected first signal line L1. Shows the voltage value V1 of the first signal Sig1 output from. In the graph, “V2 (L2 normal)” indicates the voltage value V2 of the second signal Sig2 output from the normal second signal line L2, and “V2 (L2 disconnection)” indicates the disconnected second signal. The voltage value V2 of the second signal Sig2 output from the line L2 is shown.

  In the graph of FIG. 4, the movable range of the position of the core 106a in the Z-axis direction is set to a predetermined range (−5 mm to +5 mm), and the first quadrant (0 mm to +5 mm) depends on the position of the core 106a in the Z-axis direction. ) And the second quadrant (-5 mm to 0 mm). Here, in the LVDT 106 of this embodiment incorporated in the probe height detector 20, the position of the core 106a in the Z-axis direction is in a specific range (−2 mm to +5 mm) [hereinafter simply referred to as a normal position range NR]. The description will be made assuming that it basically fits. The normal position range NR varies depending on the type of the prober 10 (probe height detector 20).

  As shown in FIG. 4, in the normal position range NR, the minimum value of the voltage value V1 of the normal first signal Sig1 is about 180 mV, and does not become smaller than 150 mV. Further, in the normal position range NR, the minimum value of the voltage value V2 of the normal second signal Sig2 is about 230 mV, and does not become smaller than 200 mV.

  Therefore, in the present embodiment, the first individual threshold Th1 is set to 150 mV, the second individual threshold Th2 is set to 200 mV, and the signal lines of the first signal line L1 and the second signal line L2 by the determination unit 63 are determined. The presence or absence of disconnection (hereinafter abbreviated as “both signal lines L1 and L2”) is individually determined.

  At this time, the first disconnection voltage value V1, which is the voltage value V1 of the first signal Sig1 output from the disconnected first signal line L1, and the second output from the disconnected second signal line L2. The second disconnection voltage value V2 that is the voltage value V2 of the signal Sig2 does not become zero due to the capacitance of the signal line itself as described above. The maximum value of both the disconnection voltage values V1 and V2 over the entire range (−5 mm to +5 mm) of the position in the Z-axis direction of the core 106a is about 170 mV. Therefore, the above-described second individual threshold Th2 (200 mV) is set to be larger than the maximum value of both the disconnection voltage values V1 and V2, whereas the above-described first individual threshold Th1 (150 mV) is The disconnection voltage values V1 and V2 are set smaller than the maximum value.

  Therefore, when the position of the core 106a in the Z-axis direction is in the position range W1 (−5 mm to about −1 mm) in the second quadrant, even if the first signal line L1 is disconnected, the first signal Sig1 There is a possibility that the voltage value V1 becomes larger than the first individual threshold Th1 (150 mV). For this reason, when the position of the core 106a in the Z-axis direction is a part (−2 mm to about −1 mm) in the normal position range NR, or is outside the normal position range NR (−5 mm to −2 mm), Even if the voltage value V1 of the 1 signal Sig1 becomes larger than the first individual threshold Th1, the first signal line L1 may be disconnected.

  Further, in the position range W2 (−5 mm to about −3 mm) of the core 106a in the Z-axis direction, even if the second signal line L2 is normal, the voltage value of the second signal Sig2 V2 becomes smaller than the second individual threshold Th2 (200 mV). For this reason, even if the voltage value V2 of the second signal Sig2 becomes smaller than the second individual threshold Th2 when the position of the core 106a in the Z-axis direction is outside the normal position range NR (−5 mm to about −3 mm). There is a possibility that the second signal line L2 is not disconnected and is normal.

  In the entire movable range (−5 mm to +5 mm) of the core 106a, the minimum value of the voltage value V2 of the second signal Sig2 output from the normal second signal line L2 is the voltage of the first signal Sig1 described above. Like the value V1, it is about 180 mV, and never becomes smaller than 150 mV. Therefore, if the voltage values V1 and V2 are smaller than the first individual threshold Th1 (150 mV), respectively, it can be determined that both the signal lines L1 and L2 are surely disconnected, but the voltage values V1 and V2 are If it is greater than one individual threshold Th1 (150 mV), it cannot be reliably determined whether there is a break.

  As described above, only the second determination process described above cannot accurately determine whether or not the signal lines L1 and L2 are disconnected depending on the position of the core 106a in the Z-axis direction. Further, the minimum values of the voltage values V1 and V2 of both signals Sig1 and Sig2 when both signal lines L1 and L2 are normal are about 180 mV, and conversely both signals Sig1 and Sig1 when they are disconnected. The maximum value of both disconnection voltage values V1, V2 of Sig2 is about 170 mV, and both are close to each other. For this reason, the first individual threshold Th1 and the second individual threshold Th2 are set so as to fall between these minimum and maximum values, and the first signal line L1 and the second signal line L2 are set by the second determination process. It is difficult to individually determine the presence or absence of disconnection.

  Therefore, the determination unit 63 of the present embodiment performs the first determination process in addition to the second determination process, and determines whether or not each of the signal lines L1 and L2 is disconnected.

[First determination process]
As shown in FIGS. 3 and 4, when the determination unit 63 performs the first determination process, the presence / absence of disconnection for both signal lines L1 and L2 and the two signals Sig1 and Sig2 that change according to the presence / absence of the disconnection described above. The first voltage range R1 and the second voltage range R2 indicating the correspondence relationship between the two voltage values V1 and V2 are acquired from the storage unit 65. Then, the determination unit 63 determines whether or not the first signal line L1 is disconnected based on the voltage values V1 and V2 of both signals Sig1 and Sig2 acquired from the signal acquisition unit 51B with reference to the first voltage range R1. At the same time, based on both voltage values V1 and V2, whether or not the second signal line L2 is disconnected is determined by referring to the second voltage range R2.

<About the first voltage range R1>
The first voltage range R1 is a predetermined range of both voltage values V1 and V2 indicating the disconnection of the first signal line L1 in the above-described second quadrant position range W1. The first disconnection voltage value V1 is larger than the first individual threshold value Th1 in the position range W1. On the other hand, since the second individual threshold value Th2 is set to be larger than the maximum value of the first disconnection voltage value V1, the maximum value of the first disconnection voltage value V1 is greater than the second individual threshold value Th2 regardless of the position range W1. Will not grow.

  Therefore, when the voltage value V1 of the first signal Sig1 input from the signal acquisition unit 51B is larger than the first individual threshold Th1 and smaller than the second individual threshold Th2 within the position range W1 of the second quadrant, the first signal It can be determined that the line L1 is disconnected. Conversely, when the voltage value V1 becomes larger than the second individual threshold Th2, it can be determined that the first signal line L1 is normal regardless of the position range W1.

  Here, even when the first signal line L1 is normal, if the position of the core 106a in the Z-axis direction is a partial range (+3 mm to +5 mm) within the first quadrant, the first signal input from the signal acquisition unit 51B. The voltage value V1 of Sig1 is larger than the first individual threshold Th1 and smaller than the second individual threshold Th2. Therefore, when the voltage value V1 is larger than the first individual threshold value Th1 and smaller than the second individual threshold value Th2, the first signal line L1 if the position of the core 106a in the Z-axis direction is within the second quadrant position range W1. If the position of the core 106a in the Z-axis direction is within the first quadrant, it can be determined that the first signal line L1 is normal. Whether or not the position of the core 106a in the Z-axis direction is within the position range W1 of the second quadrant can be determined based on the voltage value V2 of the second signal Sig2 input from the signal acquisition unit 51B.

  Specifically, in the present embodiment, when the voltage value V2 is smaller than about 300 mV, it can be determined that the position of the core 106a in the Z-axis direction is within the position range W1 of the second quadrant. Therefore, in this embodiment, 300 mV is set as the determination threshold Th3, and the position of the core 106a is within the position range W1 of the second quadrant based on whether or not the voltage value V2 is smaller than the determination threshold Th3, or It is determined whether it is in the first quadrant.

  As described above, the first voltage range R1 corresponding to the voltage value V1 is set to a range larger than the first individual threshold Th1 (150 mV) and smaller than the second individual threshold Th2 (200 mV). In addition, the first voltage range R1 corresponding to the voltage value V2 is set to a range smaller than the determination threshold Th3 (300 mV). When the second signal line L2 is normal, the voltage value V2 does not become 150 mV, that is, the first individual threshold value Th1, so the first voltage range R1 corresponding to the voltage value V2 described above. Is a range that is larger than the first individual threshold Th1 and smaller than the determination threshold Th3.

  Information on the first voltage range R1 for each of the voltage values V1 and V2 is stored in the storage unit 65 together with the information on the determination threshold Th3 described above. Thereby, even when the presence or absence of the disconnection of the first signal line L1 is not accurately determined in the second determination process, the determination unit 63 determines that the voltage values V1 and V2 of both the signals Sig1 and Sig2 are both in the first voltage range R1. It is possible to determine whether or not the first signal line L1 is disconnected by the first determination process for determining whether or not the above is satisfied.

  Here, since the information regarding the determination threshold Th3 can be included in the information regarding the first voltage range R1 (and the second voltage range R2 described later), the information regarding the determination threshold Th3 is not necessarily stored as shown in FIG. There is no need to store the information in the unit 65 separately.

<About the second voltage range R2>
The second voltage range R2 is a range in which both voltage values V1 and V2 indicating that the second signal line L2 is normal in the position range W2 in the second quadrant described above are predetermined and stored in the storage unit 65. It is. As described above, the voltage value V2 of the first signal Sig2 output from the normal second signal line L2 is smaller than the second individual threshold value Th2 within the position range W2 of the second quadrant. It becomes larger than the threshold value Th1.

  Here, even when the second signal line L2 is disconnected, when the position of the core 106a in the Z-axis direction is in a partial range within the first quadrant (about +2 mm to +5 mm), the first input from the signal acquisition unit 51B is performed. The second disconnection voltage value V2 of the two signals Sig2 is larger than the first individual threshold Th1 and smaller than the second individual threshold Th2.

  At this time, the second disconnection voltage value V2 is within a range in which the voltage value V1 of the first signal Sig1 output from the normal first signal line L1 is greater than the above-described determination threshold Th3 (300 mV) (particularly the first In the second quadrant), it is smaller than the first individual threshold Th1 (150 mV). In other words, the first individual threshold value Th1 is set to be larger than the second disconnection voltage value V2 within a range where the voltage value V1 is larger than the above-described determination threshold value Th3 (particularly within the second quadrant). Yes.

  Therefore, when the voltage value V1 of the first signal Sig1 is larger than the determination threshold value Th3, the voltage value V2 of the second signal Sig2 is smaller than the first individual threshold value Th1 if the second signal line L2 is normal. There is no. Therefore, when the voltage value V2 is larger than the first individual threshold value Th1 and smaller than the second individual threshold value Th2, the second signal line L2 is normal if the voltage value V1 of the first signal Sig1 is larger than the determination threshold value Th3. Conversely, if the voltage value V1 of the first signal Sig1 becomes smaller than the determination threshold Th3, it can be determined that the second signal line L2 is disconnected.

  As described above, the second voltage range R2 corresponding to the voltage value V1 is set to a range larger than the determination threshold Th3 (300 mV). The second voltage range R2 corresponding to the voltage value V2 is set to a range that is larger than the first individual threshold value Th1 (150 mV) and smaller than the second individual threshold value Th2 (200 mV).

  And the information regarding 2nd voltage range R2 for each voltage value V1, V2 is memorize | stored in the memory | storage part 65 similarly to the information regarding 1st voltage range R1 mentioned above. As a result, even if the determination unit 63 does not accurately determine whether or not the second signal line L2 is disconnected (whether the second signal line L2 is normal) in the second determination process, the both signals Sig1 , Sig2 can determine whether or not the second signal line L2 is disconnected by the first determination process for determining whether or not both of the voltage values V1 and V2 satisfy the second voltage range R2.

<Operation of determination unit>
When the voltage values V1 and V2 of both signals Sig1 and Sig2 input from the signal acquisition unit 51B satisfy the first voltage range R1, the determination unit 63 performs the first signal line L1 by the first determination process described above. Determine if there is a break. Conversely, when at least one of the voltage values V1 and V2 does not satisfy the first voltage range R1, the determination unit 63 determines whether or not the first signal line L1 is disconnected by the above-described second determination process.

  In addition, when the voltage values V1 and V2 of both signals Sig1 and Sig2 input from the signal acquisition unit 51B satisfy the second voltage range R2, the determination unit 63 performs the second signal line by the first determination process described above. The presence or absence of the disconnection of L2 is determined. Conversely, when at least one of the voltage values V1 and V2 does not satisfy the second voltage range R2, the determination unit 63 determines whether or not the second signal line L2 is disconnected by the second determination process described above.

  Note that the first determination process and the second determination process by the determination unit 63 may be performed in parallel. In this case, when the determination unit 63 determines that the first signal line L1 is disconnected in the first determination process and determines that the first signal line L1 is normal in the second determination process, the first determination process The determination result is prioritized. The first determination is also performed when the determination unit 63 determines that the second signal line L2 is normal in the first determination process and determines that the second signal line L2 is disconnected in the second determination process. The determination result of the process has priority. Thereby, it is possible to accurately determine whether or not each of the first signal line L1 and the second signal line L2 is disconnected.

<Prober action: disconnection detection>
Next, the operation of the prober 10 configured as described above, particularly the disconnection detection method for the first signal line L1 and the second signal line L2, will be described with reference to FIG. FIG. 5 is a flowchart showing a flow of detection of disconnection of the first signal line L1 and the second signal line L2 by the prober 10. Since other operations of the prober 10 (detection of the tip and height of the probe 25, inspection of the wafer W, etc.) are known techniques, a specific description thereof is omitted here.

  As shown in FIG. 5, when the prober 10 is operated, the excitation signal Sig0 is input to the primary coil 108 from the oscillator 51A of the LVDT controller 51 via the drive signal line L0, and the primary coil 108 is excited. Thus, the first signal Sig1 is output from the secondary coil 109A via the first signal line L1 according to the displacement in the Z-axis direction of the core 106a, and the secondary coil 109B via the second signal line L2 is output. The second signal Sig2 is output. As a result, the first signal Sig1 and the second signal Sig2 are respectively acquired by the signal acquisition unit 51B of the LVDT control unit 51 (step S1, corresponding to the signal acquisition step of the present invention).

  Then, the signal acquisition unit 51B outputs the acquired both signals Sig1 and Sig2 to the probe height detection unit 62 and the determination unit 63, respectively. Thereby, the height detection of the tip of the probe 25 by the probe height detection unit 62 is executed. On the other hand, the determination unit 63 that has received both signals Sig1 and Sig2 from the signal acquisition unit 51B receives the first individual threshold Th1, the second individual threshold Th2, the determination threshold Th3, the first voltage range R1, and the like in the storage unit 65. Information regarding the second voltage range R2 is referred to.

  Then, the determination unit 63 determines whether or not the voltage value V2 is smaller than the first individual threshold Th1 (150 mV) among the voltage values V1 and V2 of both the signals Sig1 and Sig2 that are first input from the signal acquisition unit 51B. That is, it is determined whether or not the voltage value V2 is out of the second voltage range R2 (step S2). When the voltage value V2 is smaller than the first individual threshold Th1 (150 mV), the determination unit 63 is outside the second voltage range R2 when the voltage value V2 is smaller than the first individual threshold Th1 (150 mV). It is determined whether or not there is a disconnection (YES in step S2). In this case, since the voltage value V2 is naturally smaller than the second individual threshold Th2 (200 mV), the determination unit 63 determines that the second signal line L2 is disconnected (step S3, the first of the present invention). Equivalent to 2 determination processing steps).

  On the other hand, when the voltage value V2 becomes larger than the first individual threshold value Th1 (150 mV), the determination unit 63 determines whether or not the voltage value V2 becomes smaller than the second individual threshold value Th2 (200 mV), that is, the voltage value V2. Is in the second voltage range R2 (step S4). When the voltage value V2 is smaller than the second individual threshold Th2 (200 mV) (YES in step S4), that is, when the voltage value V2 is within the second voltage range R2, the determination unit 63 determines that the voltage value V1 is It is determined whether the threshold value Th3 (300 mV) is greater, that is, whether the voltage value V1 is also within the second voltage range R2 (step S5).

  When the voltage value V1 is larger than the determination threshold Th3 (300 mV) (YES in Step S5), that is, when the voltage value V1 is also within the second voltage range R2, the determination unit 63 performs the second signal by the first determination process. It is determined that the line L2 is normal (YES in step S5, step S6, corresponding to the first determination processing step of the present invention).

  Further, the determination unit 63 performs the second determination process when the voltage value V1 is smaller than the determination threshold Th3 (300 mV) (NO in step S5), that is, when the voltage value V1 is out of the second voltage range R2. Thus, it is determined whether or not the second signal line L2 is disconnected. In this case, since the voltage value V2 is smaller than the second individual threshold Th2 (200 mV) as determined NO in step S4 described above, the determination unit 63 determines that the second signal line L2 is disconnected. (Step S7, corresponding to the second determination processing step of the present invention).

  On the other hand, when the voltage value V2 is larger than the second individual threshold Th2 (200 mV) in the above-described step S4 (NO in step S4), the determination unit 63 determines whether the second signal line L2 is disconnected by the second determination process. Judgment is made. Although illustration is omitted, in this case, since the voltage value V2 is larger than the second individual threshold Th2 (200 mV), the determination unit 63 determines that the second signal line L2 is normal (corresponding to a second determination processing step). ).

  Next, the determination unit 63 starts determining whether or not the first signal line L1 is disconnected. First, the determination unit 63 determines whether or not the voltage value V2 is smaller than the determination threshold Th3 (300 mV), that is, whether or not the voltage value V2 is within the first voltage range R1 (step S8). When the voltage value V2 is smaller than the determination threshold Th3 (300 mV), that is, when the voltage value V2 is within the first voltage range R1 (YES in step S8), the determination unit 63 determines that the voltage value V1 is the second value. It is determined whether or not the threshold value is smaller than the individual threshold value Th2 (200 mV) and larger than the first individual threshold value Th1 (150 mV), that is, whether or not the voltage value V1 is within the first voltage range R1 (step). S9).

  Note that “V1 <200 mV” in step S9 is when the voltage value V1 is larger than the first individual threshold Th1 (150 mV) and smaller than the second individual threshold Th2 (200 mV) (first determination process). The description includes both the case where the voltage value V1 is smaller than the first individual threshold Th1 (150 mV) (second determination process).

  The determination unit 63 determines that the voltage value V1 is larger than the first individual threshold Th1 (150 mV) and smaller than the second individual threshold Th2 (200 mV) (YES in Step S9), that is, the voltage value V1 is also the first voltage. When it falls within the range R1, it is determined that the first signal line L1 is disconnected by the first determination process (step S10, corresponding to the first determination process step of the present invention).

  Note that when the voltage value V1 is smaller than the first individual threshold value Th1 (150 mV), the determination unit 63 causes the voltage value V1 to be outside the first voltage range R1, and therefore in step S10, the second determination process is performed. Therefore, it is determined that the first signal line L1 is disconnected (corresponding to a second determination processing step). That is, in step S9 described above, regardless of the first determination process and the second determination process, if the voltage value V1 is smaller than the second individual threshold Th2 (200 mV), it is determined that the first signal line L1 is disconnected. Is done.

  Further, when the voltage value V1 becomes larger than the second individual threshold Th2 (200 mV) (NO in Step S9), that is, when the voltage value V1 is out of the first voltage range R1, the determination unit 63 determines the second Whether or not the first signal line L1 is disconnected is determined by the determination process. In this case, since the voltage value V1 is naturally larger than the first individual threshold Th1 (150 mV), the determination unit 63 determines that the first signal line L1 is normal (step S11, the second of the present invention). Equivalent to a determination processing step).

  On the other hand, when the voltage value V2 is larger than the determination threshold Th3 (300 mV) in the above-described step S8 (No in step S8), that is, when the voltage value V2 is out of the first voltage range R1, the determination unit 63 determines whether or not the first signal line L1 is disconnected by the second determination process (step S12).

  In this case, when the voltage value V1 is smaller than the first individual threshold Th1 (150 mV), the determination unit 63 determines that the first signal line L1 is disconnected (YES in step S12, step S13, and the present invention). Equivalent to a second determination processing step). Conversely, when the voltage value V1 is larger than the first individual threshold Th1 (150 mV), the determination unit 63 determines that the first signal line L1 is normal (NO in step S12, step S14, the second of the present invention). Equivalent to a determination processing step).

  Hereinafter, while the probe height detector 20 and the height adjustment mechanism 27 of the prober 10 are operating, the processing from step S1 to step S14 is repeatedly executed. When the determination unit 63 determines that either the first signal line L1 or the second signal line L2 is disconnected, the overall control unit 60 operates the probe height detector 20 and the height adjustment mechanism 27. And the determination result of the determination unit 63 is displayed (warning display) on a display unit (not shown).

[Effect of this embodiment]
As described above, in the prober 10 (wafer test system 9) of the present embodiment, the first voltage range R1 is referred to based on the voltage values V1 and V2 of both signals Sig1 and Sig2 acquired from the signal acquisition unit 51B. First determination processing is performed to determine whether the first signal line L1 is disconnected and to determine whether the second signal line L2 is disconnected with reference to the second voltage range R2 based on both voltage values V1, V2. be able to. Thereby, even when it is difficult to determine the presence or absence of the disconnection of each of the first signal line L1 and the second signal line L2 only by the second determination process, this determination can be performed. As a result, the presence / absence of disconnection of each of the first signal line L1 and the second signal line L2 can be determined with high accuracy.

  Further, since the first determination process and the second determination process of the determination unit 63 are simple voltage determinations, the determination unit 63 can be configured with an analog logic circuit (comparator), which increases the manufacturing cost of the prober 10. It can be suppressed.

[Other Embodiments]
FIG. 6 is a graph showing the voltage values V1 and V2 of both of the two types of signals Sig1 and Sig2 that change depending on whether or not each of the first signal line L1 and the second signal line L2 is disconnected. It is the graph which showed both voltage value V1, V2 in the normal position range NR. In the above embodiment, as shown in FIG. 4 described above, the presence / absence of disconnection of the first signal line L1 and the second signal line L2 is determined in the entire range (−5 mm to +5 mm) of the position of the core 106a. However, in the LVDT 106 of the present embodiment, as described above, the position of the core 106a in the Z-axis direction is basically within the normal position range NR (−2 mm to +5 mm). For this reason, as shown in FIG. 6, the first determination process and the second determination process by the determination unit 63 may be performed only within the normal position range NR.

  FIG. 7 is a flowchart showing a flow when the disconnection detection (first determination process and second determination process) of the first signal line L1 and the second signal line L2 is performed within the normal position range NR. is there. As shown in FIG. 7, in this case, Steps S4 to S7 in the flowchart shown in FIG. 5 can be omitted.

  Specifically, in this other embodiment, the second determination process is basically the same as in the above embodiment, but the first determination process determines only whether or not the first signal line L1 is disconnected, that is, both signals Sig1, It is only necessary to determine whether or not both voltage values V1 and V2 of Sig2 satisfy the first voltage range R1. As a result, it is possible to determine whether or not the signal lines L1 and L2 are disconnected with a simpler logic than the above embodiment.

[Others]
In the above embodiment, the first individual threshold Th1 is set to 150 mV, the second individual threshold Th2 is set to 200 mV, and the determination threshold Th3 is set to 300 mV. The values of these thresholds are the type of the LVDT 106, and the probe It changes suitably according to the kind etc. of the height detector 20.

  In the above embodiment, the LVDT control unit 51 and the overall control unit 60 (determination unit 63 and storage unit 65) constituting the disconnection detection device of the present invention are incorporated in the prober 10, but are provided separately from the prober 10. In this case, for example, an arithmetic unit such as a personal computer is used as the disconnection detecting device of the present invention.

  In the above-described embodiment, the determination unit 63 acquires information related to the first individual threshold Th1, the second individual threshold Th2, the determination threshold Th3, the first voltage range R1, and the second voltage range R2 from the storage unit 65. For example, the information may be input by an operator or acquired from a server on the Internet.

  In the above embodiment, the first determination process and the second determination process are selectively performed by the determination unit 63, but the presence or absence of disconnection of both signal lines L1 and L2 as shown in FIG. Based on the correspondence relationship with V2, the first determination process described above for determining whether or not there is a disconnection based on the voltage values V1 and V2 of the ranges other than the position ranges W1 and W2 may be performed.

  In the above embodiment, the disconnection detection device and the disconnection detection method of the present invention are applied to the disconnection detection of the first signal line L1 and the second signal line L2 of the LDVT 106 used in the probe height detector 20 of the prober 10. The present invention can be applied to various detectors or various apparatuses (such as measuring apparatuses) provided with the LDVT 106.

9 ... Wafer test system,
10 ... Prober,
20: Probe height detector,
20a ... contact surface,
21, 27 ... Height adjustment mechanism,
25 ... probe,
51 ... LVDT controller,
51A ... oscillator,
51B ... Signal acquisition unit,
60 ... Overall control unit,
62... Probe height detector,
63 ... determination part,
65 ... storage part,
106 ... LVDT,
106a ... core,
106b ... Coil,
108 ... primary coil,
109A, 109B ... secondary coil,
L1 ... first signal line,
L2 ... second signal line,
Sig1 ... first signal,
Sig2 ... second signal,
V1, V2 ... Voltage value,
Th1 ... 1st individual threshold value,
Th2 ... second individual threshold value,
Th3: Determination threshold

Claims (11)

A signal acquisition unit for acquiring two types of signals respectively output from two secondary coils provided in the linear variable differential transformer via individual signal lines;
The two types of signals acquired by the signal acquisition unit by acquiring in advance the correspondence between the presence / absence of the disconnection for each signal line and the voltage values of both of the two types of signals that change according to the presence / absence of the disconnection. A determination unit that performs a first determination process for determining the presence or absence of disconnection for each of the signal lines with reference to the correspondence relationship based on both the voltage values of
A disconnection detecting device.   The determination unit performs a second determination process for individually determining the presence / absence of a disconnection for each signal line based on whether or not the voltage values of the both are smaller than a predetermined individual threshold value. The disconnection detection apparatus as described in. Of the two types of signals acquired by the signal acquisition unit, the first signal output from the disconnected signal line is defined as a first signal having a smaller individual threshold and a second signal having a larger individual threshold. When the voltage value of the signal is the first disconnection voltage value, the individual threshold value of the first signal is the first disconnection voltage value within a range where the voltage value of the second signal is smaller than a predetermined determination threshold value. Is set smaller than the maximum value of
The individual threshold value of the second signal is set larger than the maximum value of the first disconnection voltage value,
The correspondence relationship includes a first voltage range of each of the two voltage values indicating a disconnection of the signal line corresponding to the first signal,
The first voltage range corresponding to the voltage value of the first signal is set to a range larger than the individual threshold value of the first signal and smaller than the individual threshold value of the second signal,
The disconnection detection device according to claim 2, wherein the first voltage range corresponding to the voltage value of the second signal is set to a range smaller than the determination threshold.   When the voltage value of the first signal and the voltage value of the second signal are outside the range of the first voltage range, the determination unit determines whether the signal line corresponding to the first signal is disconnected or not. The disconnection detection device according to claim 3, which is determined by two determination processing. When the voltage value of the second signal output from the disconnected signal line is the second disconnection voltage value, the individual threshold value of the first signal is greater than the determination threshold value. Is set to be greater than the second disconnection voltage value within a range,
The correspondence includes a second voltage range of each of the voltage values indicating that the signal line corresponding to the second signal is normal,
The second voltage range corresponding to the voltage value of the first signal is set to a range larger than the determination threshold,
The second voltage range corresponding to the voltage value of the second signal is set to a range larger than the individual threshold value of the first signal and smaller than the individual threshold value of the second signal. 4. The disconnection detection device according to 4.   When the voltage value of the first signal and the voltage value of the second signal are outside the range of the second voltage range, the determination unit determines whether or not the signal line corresponding to the second signal is disconnected. The disconnection detection device according to claim 5, wherein the disconnection detection device is determined by two determination processing.   The disconnection detection device according to any one of claims 3 to 6, wherein the determination threshold is set to a value larger than the individual threshold of the second signal. Provided in a prober that inspects the wafer by bringing a probe into contact with the electrode of the wafer, in a probe tip detection device that detects the tip of the probe,
A contact surface;
A moving unit for moving the contact surface relative to the probe from a position facing the probe;
A linear variable differential transformer that outputs two types of signals from two secondary coils via respective individual signal lines according to the position of the core that moves integrally with the contact surface;
A disconnection detecting device according to any one of claims 1 to 7,
A probe tip detection device comprising:   The probe tip detection device according to claim 8, further comprising a contact detection unit that detects contact of the tip of the probe with the contact surface based on the two types of signals output for each of the secondary coils. A signal acquisition step of acquiring two types of signals respectively output from two secondary coils provided in the linear variable differential transformer via individual signal lines;
The two types of signals acquired in the signal acquisition step by acquiring in advance a correspondence relationship between the presence or absence of disconnection for each signal line and the voltage values of both of the two types of signals that change according to the presence or absence of the disconnection. A first determination processing step of determining the presence or absence of disconnection for each of the signal lines with reference to the correspondence relationship based on both the voltage values of
A disconnection detecting method.   11. The disconnection according to claim 10, further comprising a second determination processing step of individually determining whether or not there is a disconnection for each signal line based on whether or not the voltage values of both are smaller than a predetermined individual threshold value. Detection method.

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