TWI793179B - Resistance measuring device, substrate inspection device, and resistance measuring method - Google Patents

Abstract

The invention provides a resistance measuring device, a substrate inspection device and a resistance measuring method. The resistance measuring device comprises a first current probe, a second current probe, contacting the electrode on the wafer side; a first detection probe, a second detection probe, contacting an outward electrode; a voltage detection part, for the first detection probe, the second Detect the voltage between the probes; the first constant current source, the positive pole is connected to the first current probe, the negative pole is connected to the ground, and the current of the first current value is output; the second constant current source, the positive pole is connected to the first constant current source The negative electrode and the ground are connected in series with the first constant current source, the negative electrode is connected to the second current probe, and the current of the second current value that is substantially the same as the first current value is output; the ground probe makes the wiring and the ground conductive and a resistance acquisition unit that acquires the resistance of the wiring based on the voltage detected by the voltage detection unit.

Description

Resistance measuring device, substrate inspection device, and resistance measuring method

The present invention relates to a resistance measuring device for measuring resistance, a substrate inspection device using the same, and a resistance measuring method.

Conventionally, in order to inspect a wiring pattern formed on a substrate such as a printed wiring board, the resistance value of the wiring pattern is measured. As the inspection of the wiring pattern, it goes without saying whether there is a disconnection or not, and it is necessary to detect a defect that does not reach a disconnection such as a thinner width or a thinner thickness of the wiring pattern. In order to detect such defects that do not reach a disconnection, it is necessary to perform high-precision resistance measurement. As such a high-precision resistance measurement method, a resistance measurement device using a four-terminal measurement method is known.

For example, the resistance measurement device described in Japanese Laid-Open Publication No. 2004-184374 includes: a pair of contact probes (P1, P2) for flowing a current for resistance measurement to the wiring pattern of the resistance measurement object; A pair of contact probes (P3, P4) for measuring the voltage at the resistance measurement site.

According to this structure, since the electric current for resistance measurement does not flow in contact probe P3 and contact probe P4 for voltage measurement, the voltage drop due to the resistance of contact probe P3 and contact probe P4 itself is reduced, and high precision resistance determination. According to FIG. 1 of Japanese Unexamined Patent Publication No. 2004-184374, the contact probe P1 on the positive side for current output is connected to a constant current source, and the contact probe P2 on the negative side is connected to a circuit ground.

However, in the resistance measuring device described in Japanese Laid-Open Publication No. 2004-184374, a current for resistance measurement flows through the contact resistance between the contact probe P2 on the negative electrode side and the measurement object M to generate a voltage. This voltage becomes a common mode voltage (common mode noise) with respect to the contact probe P3 and contact probe P4 for voltage measurement. The contact resistance Ro of the contact probe P2 can be about 100Ω, so if the current i for resistance measurement is set to 20mA, the common mode voltage Vc becomes Ro×i=100Ω×20mA=2000mV (see FIG. 7 ).

On the other hand, for example, when the measurement object is a wiring pattern, its resistance value Rx is about 1 mΩ. Then, when the current i for resistance measurement is 20 mA, the measurement voltage Vm measured by the contact probes P3 and P4 becomes Rx×i=1 mΩ×20 mA=20 μV=0.02 mV (see FIG. 7 ).

Then, the measured voltage becomes 20log(measured voltage/common-mode voltage)=20log(0.02/2000)=-100dB with respect to the common-mode voltage. Since the contact resistance caused by the contact of the contact probe P2 is unstable, the common mode voltage also fluctuates stably. Since the measurement voltage becomes a minute voltage of about -100 dB with respect to the common mode voltage, the measurement accuracy of the measurement voltage is affected by fluctuations in the common mode voltage and decreases. As a result, there is a disadvantage in that the accuracy of the measured resistance value obtained from the measured voltage also decreases.

In addition, as a method of making the common mode voltage zero, a method is conceivable in which the common mode voltage is fed back to the inverting amplifier circuit of the operational amplifier as described in Japanese Laid-Open Publication No. 2007-333598, thereby passing output of the op amp to cancel common-mode voltages. 8 is an equivalent circuit diagram of the circuit described in FIG. 1 described in Japanese Laid-Open Publication No. 2007-333598, in which Ro represents the current supply terminal 22, the current supply terminal 23, the voltage measurement terminal 24, and the voltage measurement terminal 25. The contact resistance, etc., with Co to represent the parasitic capacitance.

However, in this method, a feedback time delay caused by Ro or parasitic capacitance Co which is the resistance component of the feedback circuit and a slow response of the operational amplifier occur, so it is difficult to eliminate the unstable common mode by high-speed operation. Voltage is not easy.

An object of the present invention is to provide a resistance measurement device, a substrate inspection device, and a resistance measurement method that can easily improve resistance measurement accuracy by a four-terminal measurement method.

[Technical means to solve the problem]

The resistance measuring device of the present invention is a resistance measuring device for measuring the resistance of a conductor, and includes: a first current probe and a second current probe for contacting the conductor and flowing a predetermined current for measurement; a probe and a second detection probe for contacting the conductor and detecting a voltage generated in the conductor by the measurement current; a voltage detection unit for detecting the first detection probe and the second detection probe The voltage between the needles; the first constant current source, the positive pole is connected to the first current probe, the negative pole is connected to the ground, and outputs the current of the first current value set in advance; the second constant current source, the positive pole is connected to the first current probe The negative electrode of the constant current source is connected to the ground and connected in series with the first constant current source, the negative electrode is connected to the second current probe, and outputs a second current value that is substantially the same as the first current value. an electric current; a grounding unit that conducts conduction between a predetermined portion of the conductor and the ground; and a resistance acquisition unit that acquires the resistance based on the voltage detected by the voltage detection unit.

In addition, the resistance measurement method of the present invention is a resistance measurement method for measuring the resistance of a conductor, including: (a) a step of bringing the first current probe and the first detection probe into contact with the conductor; (b) making the second current probe contact the conductor; A step in which the probe and the second detection probe contact the position of the conductor that is separated from the contact position of the first current probe and the first detection probe; (c) contacting the first current probe through the positive electrode pin connection, the negative pole is connected to the first constant current source connected to the ground to output the current of the first current value set in advance, and the positive pole is connected to the negative pole of the first constant current source and the ground and connected to the first constant current source The source is connected in series, and the negative electrode is connected to the second constant current source of the second current probe to output a current of a second current value substantially the same as the first current value; (d) making the conductor The process of conducting the predetermined part of the ground with the ground; (e) the process of detecting the voltage between the first detection probe and the second detection probe; voltage to obtain the resistive process.

According to these structures, resistance measurement can be performed by the four-terminal measurement method using the 1st current probe and the 2nd current probe, and the 1st detection probe and the 2nd detection probe. Furthermore, as a result of the first constant current source and the second constant current source connected in series and whose connection point is set to the ground potential to maintain the output currents of the first current value and the second current value, respectively, the ground conduction The current flowing toward the ground at a predetermined portion of the conductor becomes substantially zero. As a result, the common-mode voltage becomes substantially zero. Furthermore, resistance can be obtained from a measurement voltage measured with the common-mode voltage substantially zero, and thus it is easy to improve the measurement accuracy of resistance. Therefore, it is easy to improve the resistance measurement accuracy by the four-probe measurement method.

In addition, it is preferable that the ground portion includes a ground probe for contacting the predetermined portion, and the ground probe is connected to the ground.

In addition, the step (d) is preferably a step of bringing a ground probe connected to the ground into contact with the predetermined portion.

According to these configurations, by bringing the ground probe into contact with a predetermined portion of the conductor, conduction between the conductor and the ground can be achieved.

In addition, the ground portion may be a wiring that connects the second detection probe to the ground.

In addition, the second detection probe is connected to the ground, and the step (b) may also serve as the step (d).

According to these structures, since the 2nd detection probe can be used also as a ground probe, it is not necessary to separately provide a ground probe for contacting a conductor.

In addition, preferably, a first electrode is provided at one end of the conductor, and a second electrode having a larger area than the first electrode is provided at the other end of the conductor, and the step (a) is to make the second electrode A step of making the current probe and the first detection probe contact the first electrode, and the step (b) is to make the second current probe and the second detection probe contact the second electrode The step (d) is a step of bringing the ground probe into contact with the second electrode by using the second electrode as the predetermined portion.

According to this method, two probes are brought into contact with the first electrode with a small area, and three probes are brought into contact with the second electrode with a large area. Therefore, it is easy to bring each probe into contact with the first electrode and the second electrode.

In addition, the substrate inspection device according to the present invention includes: the resistance measuring device; and a substrate inspection unit for inspecting the wiring as the conductor formed on the substrate based on the resistance measured by the resistance measuring device.

According to this configuration, the wiring formed on the substrate can be inspected based on the resistance measured by the resistance measuring device.

The resistance measurement device, the substrate inspection device, and the resistance measurement method having such a structure can easily improve the resistance measurement accuracy by the four-terminal measurement method.

Hereinafter, embodiments of the present invention will be described based on the drawings. (first embodiment)

FIG. 1 is a block diagram showing an example of the configuration of a substrate inspection device 1 using a resistance measuring device according to a first embodiment of the present invention. In addition, the same code|symbol is attached|subjected to the structure in each drawing, and the description is abbreviate|omitted.

The substrate inspection device 1 (resistance measuring device) shown in FIG. 1 includes: a constant current source CS1 (first constant current source), a constant current source CS2 (second constant current source), a voltage detection unit 4 , and a current probe Pc1 (first current probe), current probe Pc2 (second current probe), detection probe Pv1 (first detection probe), detection probe Pv2 (second detection probe), grounding probe PG (ground Department), scanner 6, and control unit 5.

FIG. 1 shows a state where each probe of the substrate inspection apparatus 1 is in contact with a substrate A to be inspected. The substrate inspection apparatus 1 performs resistance measurement by a so-called four-terminal measurement method. A portion of the substrate inspection device 1 excluding a substrate inspection unit 52 described later corresponds to an example of a resistance measuring device.

The substrate of the inspection object can be, for example, a packaging substrate for semiconductor packaging, an interposer substrate, a film carrier, a printed wiring substrate, a glass epoxy substrate, a flexible substrate, a ceramic multilayer wiring substrate, and the like. It can be an electrode plate for a display such as a liquid crystal display or an electroluminescence (EL) display, or a transparent conductive plate for a touch panel, or it can be a semiconductor wafer, a semiconductor wafer, or a chip size package (Chip Size Package, CSP) and other semiconductor substrates and other substrates.

In addition, the substrate of the inspection object may be a component-embedded substrate (embedded substrate) in which electronic components such as semiconductor chips are embedded. In addition, the inspection object is not limited to the substrate, and may be an electronic component such as a semiconductor wafer. Inspection points such as wiring patterns, pads, lands, solder bumps, and terminals are formed on a substrate or an electronic component to be inspected.

FIG. 1 illustrates a cross-sectional view of an interposer substrate for a semiconductor package that is a substrate A to be inspected. On one surface of the substrate A, a plurality of wafer-side electrodes A1 (first electrodes) connected to the semiconductor wafer are formed. In contrast to the fine electrode pitch of the semiconductor wafer, the intervals between the plurality of wafer-side electrodes A1 are set to be narrow, and the size of the wafer-side electrodes A1 is also set to be small. On the other surface of the substrate A, a plurality of external electrodes A2 (second electrodes) for connecting the semiconductor wafer to the outside are formed.

The plurality of external electrodes A2 is, for example, a ball grid arranged in a grid and connected to the outside through solder balls. In order to facilitate external wiring, the intervals between the plurality of external electrodes A2 are wider than the intervals between the wafer-side electrodes A1, and the size of the external electrodes A2 is also larger than that of the wafer-side electrodes A1.

Each wafer-side electrode A1 and each external electrode A2 are electrically connected to each other by a wiring A3 (conductor) formed to penetrate the thickness direction of the substrate A, respectively. The substrate inspection apparatus 1 measures and inspects the resistance value Rx of each wiring A3. The wiring A3 corresponds to an example of a conductor, the wafer-side electrode A1 corresponds to one end of the wiring A3, and the external electrode A2 corresponds to the other end of the wiring A3.

The current probe Pc1 , the current probe Pc2 , the detection probe Pv1 , the detection probe Pv2 , and the ground probe PG are configured, for example, as an inspection jig detachable from the substrate inspection apparatus 1 . Hereinafter, the current probe Pc1, the current probe Pc2, the detection probe Pv1, the detection probe Pv2, and the grounding probe PG are sometimes only described as the probe Pc1, the probe Pc2, the probe Pv1, the probe Pv2, the probe Needle PG.

The probes Pc1 , Pc2 , Pv1 , Pv2 , and PG are, for example, elastic (flexible) linear contacts having a diameter of about 100 μm to 200 μm. The current probe Pc1 , the current probe Pc2 , the detection probe Pv1 , and the detection probe Pv2 are formed of, for example, metal such as tungsten, high-speed steel (SKH), beryllium copper (Be—Cu), or other conductors.

The front ends of the current probe Pc1 and the detection probe Pv1 are in contact with the wafer-side electrode A1 of the substrate A. As shown in FIG. The tips of the current probe Pc2 , the detection probe Pv2 , and the ground probe PG contact the outward electrode A2 at positions spaced from the wafer-side electrode A1 . If each probe is made to contact the wafer-side electrode A1 and the outward electrode A2 in this way, two probes are made to contact the wafer-side electrode A1 with a small and narrow pitch, and three probes are made to contact the outward-facing electrode A1 with a larger and wider pitch than the wafer-side electrode A1. Electrode A2. Therefore, it is easy to bring each probe into contact with the wafer-side electrode A1 and the external electrode A2.

In FIG. 1 , the illustration is simplified and one probe Pc1, one probe Pc2, one probe Pv1, one probe Pv2, and one probe PG are shown respectively. However, there are cases where several hundred to several thousand inspection points are set for one substrate. In some cases, hundreds to thousands of probes Pc1 , Pc2 , Pv1 , Pv2 , and PG may be provided to correspond to such a large number of inspection points.

The scanner 6 is for the connection relationship between the current probe Pc1, the current probe Pc2 and the constant current source CS1 and the constant current source CS2, the connection relationship between the detection probe Pv1, the detection probe Pv2 and the voltage detection part 4, And a switching circuit for switching the connection relationship between the ground probe PG and the ground. The scanner 6 includes, for example, a plurality of switches including a switch 61 , a switch 62 , a switch 63 , a switch 64 , and a switch 65 . The switches such as the switch 61 , the switch 62 , the switch 63 , the switch 64 , and the switch 65 are, for example, semiconductor switches such as transistors, or various switching elements such as relay switches. Each switch is turned on and off in response to, for example, a control signal from the control unit 5 .

The constant current source CS1 and the constant current source CS2 are constant current circuits that flow a constant current, and flow a constant current for measurement to the wiring A3. As the constant current source CS1 and the constant current source CS2, various circuits known as constant current circuits such as those using transistors, Zener diodes, and current mirror circuits can be used, or switching power supplies can be used. circuits etc.

The positive pole (+) of the constant current source CS1 is connected to the current probe Pc1 via the switch 61, and the negative pole (-) is connected to the ground GND. The constant current source CS1 outputs a current of a preset first current value I ₁ from its positive pole (+) to the current probe Pc1 . The first current value _I1 is set to, for example, about 20 mA.

The positive electrode (+) of the constant current source CS2 is connected to the negative electrode (−) of the constant current source CS1 and the ground GND, and is connected in series to the constant current source CS1, and the negative electrode (−) is connected to the current probe Pc2 via the switch 62 . The constant current source CS2 outputs a current of a second current value I ₂ that is substantially the same as the first current value I ₁ from its positive electrode (+) to the constant current source CS1 . Here, the term "substantially the same" means that even if there are differences to some extent due to manufacturing variation of the constant current source CS1 and the constant current source CS2, current control accuracy, etc., they are considered to be the same.

The ground GND is a circuit ground of the substrate inspection apparatus 1 . In addition, the ground GND may be a frame ground (earth ground) of the substrate inspection apparatus 1 , but is more preferably a circuit ground.

When the switch 61, the switch 62, the switch 63, the switch 64, and the switch 65 are turned on by the control unit 5, a constant current source CS1, the switch 61, the current probe Pc1, the wafer side electrode A1, and the wiring A3 are formed from the ground GND. , the outward electrode A2 , the current probe Pc2 , the switch 62 , and the constant current source CS2 to return to the current loop (current loop) of the measuring current I of the ground GND.

The voltage detection part 4 measures the voltage between the detection probe Pv1 and the detection probe Pv2. The voltage detection unit 4 is configured using, for example, an analog-to-digital converter, a voltage dividing resistor, or the like. The positive side (+) terminal of the voltage detection unit 4 is connected to the detection probe Pv1 through the switch 63 , and the negative side (−) terminal of the voltage detection unit 4 is connected to the detection probe Pv2 through the switch 64 . Thus, the voltage detection unit 4 measures the voltage between the detection probe Pv1 and the detection probe Pv2 selected by the scanner 6 as the measurement voltage Vs, and outputs data indicating the measurement voltage Vs to the control unit 5 .

The control unit 5 is, for example, a so-called microcomputer, and the microcomputer includes a central processing unit (Central Processing Unit, CPU) that executes predetermined calculation processing, a random access memory (Random Access Memory, RAM) that temporarily stores data, Non-volatile storage devices that store predetermined control programs, etc., and their peripheral circuits, etc. The control unit 5 functions as a resistance acquisition unit 51 and a substrate inspection unit 52 by executing a predetermined control program.

The resistance acquisition unit 51 calculates the resistance value Rx of the wiring A3 of the measurement object based on the measurement voltage Vs detected by the voltage detection unit 4 . Specifically, the resistance value Rx is calculated using the following formula (1) from the current value Is of the measurement current I=first current value I ₁ ≒second current value I ₂ and the measurement voltage Vs. Resistance value Rx=Vs/Is (1)

In addition, the substrate inspection device 1 (resistance measuring device) includes a current measuring unit that measures the current value Is of the current actually flowing through the wiring A3, and the resistance acquisition unit 51 may use the current value Is measured by the current measuring unit and the measured voltage. Vs to calculate the resistance value Rx. In addition, when the current value Is is a constant value, the resistance value Rx is proportional to the measurement voltage Vs. Therefore, the resistance acquisition unit 51 may acquire the measured voltage Vs directly as information indicating the resistance value Rx without using the formula (1) to calculate the resistance value Rx.

The substrate inspection unit 52 inspects the wiring A3 that is a conductor based on the resistance value Rx acquired by the resistance acquisition unit 51 . Specifically, the substrate inspection unit 52 compares the reference value Rref previously stored in the storage unit with the resistance value Rx, and when the resistance value Rx is smaller than the reference value Rref, the wiring A3 is determined to be a good product, and when the resistance value Rx is When the reference value Rref is greater than or equal to the reference value Rref, the wiring A3 is determined to be defective.

2 is an explanatory diagram showing an equivalent circuit of the substrate inspection apparatus 1 and the substrate A in a state where the switch 61 , the switch 62 , the switch 63 , the switch 64 , and the switch 65 are turned on. In FIG. 2, the resistance Rc1 represents the contact resistance between the current probe Pc1 and the wafer-side electrode A1 and the resistance of the switch 61, etc., the resistance Rc2 represents the contact resistance between the current probe Pc2 and the external electrode A2 and the resistance of the switch 62, etc., and the resistance Rv1 Represents the contact resistance between the detection probe Pv1 and the wafer-side electrode A1 and the resistance of the switch 63, etc., the resistance Rv2 represents the contact resistance between the detection probe Pv2 and the outward electrode A2 and the resistance of the switch 64, etc., and the resistance RG represents the contact resistance between the ground probe PG and the outward electrode A2. The contact resistance of the electrode A2 and the resistance of the switch 65 and the like. In addition, a parasitic capacitance generated in the equivalent circuit shown in FIG. 2 is represented by a capacitor Cp.

Hereinafter, the operation of the substrate inspection apparatus 1 will be described based on the equivalent circuit shown in FIG. 2 . First, as a result of the constant current source CS1 outputting the current of the first current value _I1 and the constant current source CS2 outputting the current of the second current value _I2 , the measurement current I of the current value Is flows through the wiring A3. At this time, the normal mode (normal mode) generated in the wiring A3 is detected by the voltage detection unit 4 through the detection probe Pv1 and the detection probe Pv2 different from the current probe Pc1 and the current probe Pc2 through which the measurement current I flows. mode) is measured as a measurement voltage Vs, and the measurement voltage Vs is sent from the voltage detection unit 4 to the resistance acquisition unit 51 .

In this case, since the current does not flow through the resistors Rv1 and Rv2, the result of obtaining the resistance value Rx from the measurement voltage Vs in which the resistors Rv1 and Rv2 are excluded is obtained by the resistance acquisition unit 51, which is similar to the so-called two-terminal measurement method. Ratio, high-precision resistance measurement can be performed.

Next, the common mode voltage will be described. Since the constant current source CS2 and the resistor Rc2 are connected in series, the current of the second current value _I2 will firstly flow in the resistor Rc2. Assuming that the resistance value of the resistor Rc2 is the resistance value Rc ₂ , a voltage of Rc ₂ ×I ₂ is generated in the resistor Rc2. In a constant current circuit, the internal resistance is generally high impedance, and the negative (-) potential of the constant current power supply CS2 is inconsistent with the ground potential, so the voltage generated in the resistor Rc2 is not directly applied to the resistor RG. However, at least a part of the voltage generated in the resistor Rc2 is applied to the resistor RG, and a current of the current value _I3 flows in the resistor RG.

Here, the relationship represented by the following equations (2) and (3) exists among the first current value I ₁ , the second current value I ₂ , and the current value I ₃ .

I ₁ =I ₂ +I ₃ (2)

I ₁ ≒ I ₂ (3)

Here, since the constant current source CS1 is a constant current source, the first current value I ₁ is a fixed value. Since the first current value I ₁ ≒ the second current value I ₂ , if the current value I ₃ is measured from When the current I is shunted toward the resistor RG, the current supplied to the negative pole (-) of the constant current source CS2 is insufficient compared to the second current value _I2 , and the constant current source CS2 cannot flow out the current of the second current value _I2 .

Here, the constant current source CS2 is also a constant current source, so it intends to forcibly flow out the second current value I ₂ . At this time, since the positive pole (+) of the constant current source CS2 is connected to the ground, the potential of the negative pole (-) of the constant current source CS2 drops until the constant current source CS2 is forced to flow out the second current value _I2 . The negative electrode (-) of the constant current source CS2 supplies a current of the second current value _I2 . The state in which the current of the second current value I ₂ (≒first current value I ₁ ) is supplied to the negative electrode (−) of the constant current source CS2 refers to a state in which the current value I ₃ ≒0 is obtained from Equation (2).

The current value I ₃ ≒0 flowing through the resistor RG means that the potentials at both ends of the resistor RG become substantially equal. Since one end of the resistor RG is connected to the ground, the potential of the other end of the resistor RG, that is, the outward electrode A2 shown in FIG. 2 becomes substantially the ground potential. Since the detection probe Pv2 is in contact with the outer electrode A2, the potential of the outer electrode A2 becomes almost the ground potential, that is, the common-mode voltage applied to the voltage detection unit 4 becomes almost zero.

As above, the constant current source CS1 and the constant current source CS2 connected in series and whose connection point is set to the ground potential respectively maintain the output current of the first current value I ₁ and the second current value I ₂ . The above operation is performed within an instant of the response time of the constant current source CS1 and the constant current source CS2, and the common mode voltage becomes substantially zero.

As described above, in the background art, the measurement accuracy of the measurement voltage is affected by the variation of the common mode voltage and deteriorates. On the other hand, since the board inspection apparatus 1 can make the common mode voltage substantially zero, compared with the background art, the measurement accuracy of the resistance value Rx used as a measurement object can be improved. Therefore, it is easy to improve the resistance measurement accuracy by the four-probe measurement method.

FIG. 3 is a flowchart showing an example of a resistance measurement method according to an embodiment of the present invention. First, the resistance acquisition unit 51 moves the current probe Pc1 and the detection probe Pv1 to contact the wafer-side electrode A1 by a drive mechanism (not shown in the drawing) (step S1 : step (a)). Next, the resistance acquisition unit 51 moves the current probe Pc2, the detection probe Pv2, and the ground probe PG to contact the outer electrode A2 by using a drive mechanism (not shown in the figure) (step S2: step (b), step (d) ).

Next, the resistance acquisition part 51 turns on the switch 61, the switch 62, the switch 63, the switch 64, and the switch 65 (step S3). Step S2 and Step S3 correspond to an example of the step (d). Next, the resistance acquisition unit 51 outputs a current of the first current value I ₁ (=Is) through the constant current source CS1, and outputs a current of the second current value I ₂ (≒I ₁ ) through the constant current source CS2 (step S4: process (c)).

Next, the voltage detection part 4 measures the voltage between detection probe Pv1 and detection probe Pv2 as measurement voltage Vs (step S5: process (e)). Next, the resistance acquisition unit 51 calculates the resistance value Rx of the measurement object based on the formula (1) (step S6 ), and displays the resistance value Rx on, for example, a display device (not shown).

As described above, the resistance value Rx can be calculated from the measurement voltage Vs measured with the common mode voltage substantially zero through the processing of steps S1 to S6, and thus it is easy to improve the calculation accuracy of the resistance value Rx. Therefore, it is easy to improve the resistance measurement accuracy by the four-probe measurement method.

Next, the resistance value Rx is compared with the reference value Rref by the board|substrate inspection part 52 (step S7). Then, if the resistance value Rx is less than the reference value Rref (YES in step S7 ), the wiring A3 is judged to be good by the board inspection unit 52 (step S8 ). On the other hand, if the resistance value Rx is equal to or greater than the reference value Rref (No (NO) in step S7), the wiring A3 is judged to be defective by the board inspection unit 52 (step S9), and is displayed by, for example, a display device (not shown in the drawing). As a result of these judgments, the processing ends.

By repeating the same process as step S1 to step S9 for the other wiring A3, the resistance value Rx of all the wiring A3 of the measuring object on the substrate A can be measured, and whether the substrate A is good or not can be checked.

In addition, since the common-mode voltage is noise, making the common-mode voltage substantially zero corresponds to raising the signal-to-noise (S/N) ratio of the measurement voltage Vs. Therefore, according to the above-described substrate inspection apparatus 1 and resistance measurement method, the S/N ratio can be improved and the measurement accuracy of the resistance value Rx by the measurement voltage Vs can be improved.

As a method of increasing the S/N ratio of the measurement voltage Vs, it is conceivable to increase the current value of the measurement current to increase the measurement voltage as a signal component. However, if the current value of the measurement current is increased in the circuit described in FIG. 1 of Japanese Laid-Open Publication No. 2004-184374, a contact resistance between the contact probe P2 on the negative electrode side and the measurement object body M occurs. The voltage increases, and as a result, the common-mode voltage increases. Therefore, it is not easy to increase the S/N ratio in the circuit described in FIG. 1 of Japanese Laid-Open Publication No. 2004-184374.

On the other hand, according to the substrate inspection apparatus 1 , since the S/N ratio of the measurement voltage Vs can be improved by making the common-mode voltage substantially zero, it is easy to increase the S/N ratio and improve the measurement accuracy of the resistance value Rx.

In addition, in the circuit described in FIG. 1 of Japanese Laid-Open Publication No. 2004-184374, when measuring the resistance of a measurement object such as a component-embedded substrate or an electronic component, if a common-mode voltage is generated during the measurement, then With respect to electronic components such as semiconductor elements incorporated in component-embedded substrates, a potential difference may be generated between the measurement object and the substrate inspection device due to the charge charge of the parasitic capacitance of the measurement object. In such a case, there is a possibility that a voltage stress or a current stress is applied to the electronic component due to the potential difference, and the electronic component may be damaged.

FIG. 4 is an explanatory diagram showing connections of the substrate inspection apparatus 1 when inspecting an IC (Integrated Circuit) 100 including signal terminals P1 to Pn, a power supply terminal Vcc, and a ground terminal GND. As described above, in the resistance measurement by the conventional two-terminal method or four-terminal method that does not use the two constant current sources (CS1, CS2) and the ground probe PG, the current probe Pc1, current probe Pc2 or A common mode voltage is applied to terminals of the ICs that the detection probe Pv1 and the detection probe Pv2 are in contact with. Since IC 100 has parasitic capacitance Co generated by IC 100 itself or external wiring, common mode voltage applied to terminals of IC winds up in parasitic capacitance Co, and stress is applied to IC 100 or breakage occurs.

In this case, it is conceivable to gradually increase the measurement current to gradually increase the common-mode voltage, thereby gradually charging the parasitic capacitance with the common-mode voltage, thereby reducing the current flowing into the parasitic capacitance. value, and remove the potential difference between the measured object and the substrate inspection device. Accordingly, it is considered that damage to electronic components can be prevented. However, in the method of gradually increasing the measurement current to gradually charge the parasitic capacitance, it is necessary to wait for the voltage measurement until the parasitic capacitance of the measurement object is charged by the common mode voltage and the potential difference disappears, and the time required for the measurement increases. big.

However, according to the substrate inspection apparatus 1 , since the common-mode voltage becomes substantially zero, there is no need to wait for voltage measurement until the parasitic capacitance of the measurement object is charged by the common-mode voltage and the potential difference disappears. As a result, it is easy to shorten the resistance measurement time and inspection time.

In addition, as a method of making the common mode voltage zero, a method of feeding back the common mode voltage to the inverting amplifier circuit of the operational amplifier as described in Japanese Laid-Open Publication No. 2007-333598 is conceivable, thereby The common-mode voltage is eliminated by the output of the op amp. However, in this method, it is not easy to eliminate the unstable common mode voltage due to the time delay of the feedback due to the resistance component of the feedback circuit or the parasitic capacitance, and the slow response of the operational amplifier.

On the other hand, according to the substrate inspection apparatus 1, the constant current source CS1 and the constant current source CS2, which are connected in series and whose connection point is set to the ground potential, respectively maintain the first current value _I1 and the second current value _I2 . As a result of the output current, the common-mode voltage becomes approximately zero, so it is easy to reduce the common-mode voltage.

In addition, the board|substrate inspection apparatus 1 may be a resistance measuring apparatus which does not include the board|substrate inspection part 52, and does not need to perform step S7 - step S9. In addition, the scanner 6 may not be provided. In addition, the ground probe PG is not necessarily limited to the example of contacting the external electrode A2 , that is, one end on the negative electrode side of the wiring A3 (conductor). The ground probe PG preferably contacts the negative end of the wiring A3, but may also contact the wafer-side electrode A1 which is the positive end of the wiring A3, or may contact the middle portion of the wiring A3.

In addition, the current probe Pc1 , the current probe Pc2 , the detection probe Pv1 , and the detection probe Pv2 are not necessarily limited to the example of contacting both ends of the wiring A3 (conductor) to be measured. Even when the current probe Pc1, the current probe Pc2, the detection probe Pv1, and the detection probe Pv2 are in contact with the middle part of the measurement object, the contact position between the current probe Pc1 and the detection probe Pv1 and the current probe can be measured. The resistance value between the contact portion of the needle Pc2 and the detection probe Pv2. (Second Embodiment)

Next, a substrate inspection device 1 a using a resistance measuring device according to a second embodiment of the present invention will be described. FIG. 5 is a block diagram showing an example of the configuration of a substrate inspection device 1 a using a resistance measuring device according to a second embodiment of the present invention. FIG. 6 is an explanatory diagram showing an equivalent circuit of the substrate inspection apparatus 1 a and the substrate A shown in FIG. 5 . The substrate inspection apparatus 1 a shown in FIGS. 5 and 6 differs from the substrate inspection apparatus 1 shown in FIG. 1 in the following points.

That is, the substrate inspection apparatus 1 a shown in FIGS. 5 and 6 differs from the substrate inspection apparatus 1 in that it does not include the ground probe PG and the switch 65 , but connects the negative (-) terminal of the voltage detection unit 4 to the ground. In this case, the wiring that connects the negative (−) terminal of the voltage detection unit 4 to the ground corresponds to an example of the ground. In addition, the ground probe PG is not brought into contact with the outward electrode A2 in step S2, and the switch 65 is not turned on in step S3.

The other structures are the same as those of the substrate inspection apparatus 1 shown in FIG. 1 , and thus descriptions thereof are omitted. Also in the substrate inspection apparatus 1a, as in the case of the substrate inspection apparatus 1, the constant current source CS1 and the constant current source CS2, which are connected in series and whose connection point is set to the ground potential, respectively maintain the first current value _I1 , The output current of the second current value _I2 . As a result, the current value _I3 flowing through the resistor Rv2 becomes substantially zero, and the common-mode voltage becomes substantially zero, so that the common-mode voltage can be easily reduced.

In addition, according to the substrate inspection apparatus 1a, since it is not necessary to separately provide the ground probe PG, it is easier to reduce the cost compared with the substrate inspection apparatus 1 . In addition, since the number of probes contacting the wiring A3 is only two, it is easier to bring the probes into contact compared with the substrate inspection apparatus 1 in which three probes must be brought into contact with the wiring A3.

However, although the first current value I ₁ and the second current value I ₂ of the constant current source CS1 and the constant current source CS2 are substantially the same (I ₁ ≒ I ₂ ), there is a difference between the constant current source CS1 and the constant current source CS2 There is a concern that there may be a slight difference in manufacturing deviation or current control accuracy. When a difference is generated between the first current value _I1 and the second current value _I2 , a current corresponding to the current value _I3 of the difference flows in the resistor Rv2 shown in FIG. 6 . In this case, assuming that the resistance value of the resistor Rv2 is the resistance value Rv ₂ , a voltage of Rv ₂ ×I ₃ is generated in the resistor Rv2. Since this voltage is included in the measurement voltage Vs measured by the voltage detection unit 4 , a measurement error of the measurement voltage Vs occurs.

On the other hand, in the substrate inspection apparatus 1 shown in FIG. 2, when a difference occurs between the first current value _I1 and the second current value _I2 , the current value _I3 corresponding to the difference flows in resistor RG. In the substrate inspection apparatus 1 , the voltage generated by the current flowing through the resistor RG is not included in the measurement voltage Vs. Therefore, the substrate inspection apparatus 1 is more preferable than the substrate inspection apparatus 1a in that measurement accuracy errors due to the difference between the first current value _I1 and the second current value _I2 hardly occur.

1. 1a‧‧‧substrate inspection device (resistance measuring device) 4‧‧‧voltage detection part 5‧‧‧control part 6‧‧‧scanner 22, 23‧‧‧current supply terminal 24, 25‧‧‧voltage measurement Terminal 51‧‧‧resistance acquisition part 52‧‧‧substrate inspection part 61, 62, 63, 64, 65‧‧‧switch 100‧‧‧ICA‧‧‧substrate A1‧‧‧chip side electrode (first electrode) A2 ‧‧‧Outward electrode (second electrode) A3‧‧‧Wiring (conductor) Co‧‧‧Parasitic capacitance Cp‧‧‧Capacitor CS1‧‧‧Constant current source (first constant current source) CS2‧‧‧Constant current source (Second constant current source) D‧‧‧diode GND‧‧‧ground/earth terminal I‧‧‧measurement current I ₁ ‧‧‧first current value I ₂ ‧‧‧second current value Is, I ₃ ‧‧‧current value P1～Pn‧‧‧signal terminals Pc1, Pc2, Pv1, Pv2, PG‧‧‧probes _Rc1 , Rc2, Rv1, _Rv2 , RG ‧Resistance value Rref‧‧‧Reference value Ro‧‧‧Contact resistance Vc‧‧‧Common mode voltage Vm, Vs‧‧‧Measuring voltage Vcc‧‧‧Power terminals S1～S9‧‧‧Steps

FIG. 1 is a block diagram showing an example of the configuration of a substrate inspection device using a resistance measuring device according to a first embodiment of the present invention. FIG. 2 is an explanatory diagram showing an equivalent circuit of the substrate inspection device shown in FIG. 1 and the substrate. FIG. 3 is a flowchart showing an example of a resistance measurement method according to an embodiment of the present invention. FIG. 4 is an explanatory diagram showing connections of a substrate inspection device when inspecting an integrated circuit (Integrated Circuit, IC). 5 is a block diagram showing an example of the configuration of a substrate inspection device using a resistance measuring device according to a second embodiment of the present invention. FIG. 6 is an explanatory diagram showing an equivalent circuit of the substrate inspection device shown in FIG. 5 and the substrate. FIG. 7 is an explanatory diagram for explaining a common mode voltage of the background art. FIG. 8 is an equivalent circuit diagram of the circuit described in FIG. 1 of Japanese Laid-Open Patent Publication No. 2007-333598.

1‧‧‧Substrate inspection device (resistance measurement device)

4‧‧‧Voltage detection part

5‧‧‧Control Department

6‧‧‧Scanner

51‧‧‧Resistor Acquisition Department

52‧‧‧PCB inspection department

61, 62, 63, 64, 65‧‧‧switch

A‧‧‧substrate

A1‧‧‧chip side electrode (first electrode)

A2‧‧‧outward electrode (second electrode)

A3‧‧‧Wiring (conductor)

CS1‧‧‧Constant current source (the first constant current source)

CS2‧‧‧Constant Current Source (Second Constant Current Source)

GND‧‧‧Ground/Ground Terminal

Pc1, Pc2, Pv1, Pv2, PG‧‧‧probe

Rx‧‧‧resistance value

Vs‧‧‧measurement voltage

Claims (6)

A resistance measuring device, which is used to measure the resistance of a conductor, the resistance measuring device includes: a first current probe and a second current probe, which are used to contact the conductor and flow out a prescribed current for measurement; the first detection a probe and a second detection probe for contacting the conductor and detecting a voltage generated in the conductor by the measurement current; a voltage detection unit for detecting the first detection probe and the second detection probe. Detecting the voltage between the probes; the first constant current source, the positive pole of the first constant current source is connected to the first current probe, the negative pole of the first constant current source is connected to the ground, and the preset first constant current source is output A current of a current value; a second constant current source, the positive pole of the second constant current source is connected to the negative pole of the first constant current source and the ground and connected in series with the first constant current source, the The negative pole of the second constant current source is connected to the second current probe, and outputs a current of a second current value substantially the same as the first current value; the grounding part is used to connect a predetermined part of the conductor to the second current probe. a ground conduction; and a resistance acquisition unit that acquires the resistance based on the voltage detected by the voltage detection unit, wherein the ground unit includes a ground probe for contacting the predetermined portion, and the ground probe connected to the ground. A resistance measuring device, which is used to measure the resistance of a conductor, the resistance measuring device includes: a first current probe and a second current probe, which are used to contact the conductor and flow out a prescribed current for measurement; the first detection a probe and a second detection probe for contacting the conductor and detecting a voltage generated in the conductor by the measurement current; a voltage detection unit for detecting the first detection probe and the second detection probe. Detecting the voltage between the probes; the first constant current source, the positive pole of the first constant current source is connected to the first current probe, the negative pole of the first constant current source is connected to the ground, and the preset first constant current source is output A current of a current value; a second constant current source, the positive pole of the second constant current source is connected to the negative pole of the first constant current source and the ground and connected in series with the first constant current source, the The negative pole of the second constant current source is connected to the second current probe, and outputs a current of a second current value substantially the same as the first current value; the grounding part is used to connect a predetermined part of the conductor to the second current probe. ground conduction; and a resistance acquisition unit that acquires the resistance based on the voltage detected by the voltage detection unit, wherein the ground unit is a wiring that connects the second detection probe to the ground. A substrate inspection device, comprising: the resistance measuring device according to item 1 or 2 of the patent application; and The substrate inspection unit inspects the wiring as the conductor formed on the substrate based on the resistance measured by the resistance measuring device. A resistance measurement method, which is a resistance measurement method for measuring the resistance of a conductor, the resistance measurement method comprising: (a) a step of bringing a first current probe and a first detection probe into contact with the conductor; (b) making the first current probe and the first detection probe contact the conductor; The process that the second current probe and the second detection probe contact the position of the conductor that is separated from the contact position of the first current probe and the first detection probe; (c) contacting the first current probe through the positive electrode The current probe is connected, the negative pole is connected to the first constant current source connected to the ground to output the current of the first current value set in advance, and the positive pole is connected to the negative pole of the first constant current source and the ground and connected to the first The constant current source is connected in series, and the negative electrode is connected to the second constant current source of the second current probe to output a current of a second current value substantially the same as the first current value; (d) making the A step of conducting conduction between a predetermined portion of the conductor and the ground; (e) a step of detecting the voltage between the first detection probe and the second detection probe; and (f) The step of obtaining the resistance from the voltage detected in the step, wherein the step (d) is a step of bringing a ground probe connected to the ground into contact with the predetermined portion. The method for measuring resistance as described in item 4 of the scope of patent application, wherein A first electrode is provided at one end of the conductor, and a second electrode having an area larger than the first electrode is provided at the other end of the conductor, and the step (a) is to make the first current The step of contacting the probe with the first detection probe to the first electrode, the step (b) is to make the second current probe and the second detection probe contact the second electrode In the step (d), the step of (d) is a step of bringing the ground probe into contact with the second electrode, using the second electrode as the predetermined portion. A resistance measurement method, which is a resistance measurement method for measuring the resistance of a conductor, the resistance measurement method comprising: (a) a step of bringing a first current probe and a first detection probe into contact with the conductor; (b) making the first current probe and the first detection probe contact the conductor; The process that the second current probe and the second detection probe contact the position of the conductor that is separated from the contact position of the first current probe and the first detection probe; (c) contacting the first current probe through the positive electrode The current probe is connected, the negative pole is connected to the first constant current source connected to the ground to output the current of the first current value set in advance, and the positive pole is connected to the negative pole of the first constant current source and the ground and connected to the first The constant current source is connected in series, and the negative electrode is connected to the second constant current source of the second current probe to output a current of a second current value substantially the same as the first current value; (d) making the A process in which a specified part of the conductor is connected to the ground; (e) a step of detecting a voltage between the first detection probe and the second detection probe; and (f) a step of obtaining the resistance based on the voltage detected in the step (e) , wherein the second detection probe is connected to the ground, and the process of (b) also serves as the process of (d).

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