Ultrasonic vibration type defect detection device and wire defect detection system

Abstract

Provided is an ultrasonic vibration type defect detection device and a wire defect detection system that can perform defect detection of an inspection object with high precision and in a short time. An ultrasonic vibration type defect detection device (100) that detects defects of a semiconductor device (10) includes an ultrasonic vibrator (42), a high-frequency power source (40), a camera (45), and a control unit (50) that adjusts the frequency of high-frequency power supplied from the high-frequency power source (40) to the ultrasonic vibrator (42) and performs detection of defects of the semiconductor device (10). The control unit (50) changes the frequency of high-frequency power supplied from the high-frequency power source (40) to the ultrasonic vibrator (42) on one hand and captures an image of the semiconductor device (10) using the camera (45) on the other hand, and performs detection of defects of the semiconductor device (10) based on the captured image.

Description

Technical Field

[0001] This invention relates to the structure of an ultrasonic vibration-type defect detection device, which uses ultrasonic vibration to detect defects in the object being inspected, and particularly to a wire defect detection system. Background Technology

[0002] Wire bonding apparatuses that connect the electrodes of a substrate to the electrodes of a semiconductor chip using wires are widely used. In wire bonding apparatuses, methods can be used to detect poor connections between the electrodes of the semiconductor chip and the wires by means of electrical means such as the flow of current between the wire and the semiconductor chip (see, for example, Patent Document 1).

[0003] In addition, in the wire bonding apparatus, the following method can be used: by mechanical means such as detecting the displacement in the Z direction from the time the ceramic tip falls to the end of the bonding process, the connection between the electrode of the semiconductor chip and the wire can be poor (for example, see Patent Document 2).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 9-213752

[0007] Patent Document 2: Japanese Patent Application Publication No. 2010-56106 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] Furthermore, in recent years there has been a demand for higher precision in defect detection of inspected items such as wires. However, defect detection methods using electrical or mechanical means, as described in Patent Documents 1 and 2, sometimes result in false detections.

[0010] Furthermore, it is required to perform defect detection on all wires connecting the electrodes of the semiconductor chip to the electrodes of the substrate. However, the defect detection methods described in Patent Documents 1 and 2 perform defect detection on each wire individually, which leads to problems such as long inspection times for semiconductor chips, for example, where there are hundreds or more wires connecting a semiconductor chip to the substrate.

[0011] Therefore, the purpose of this invention is to perform defect detection on the object to be inspected with high precision and in a short time.

[0012] Technical means to solve the problem

[0013] The ultrasonic vibration type defect detection device of the present invention detects defects in an inspection object, characterized by comprising: an ultrasonic vibrator for causing ultrasonic vibration in the inspection object; a power supply for supplying high-frequency power to the ultrasonic vibrator; a camera device for capturing images of the inspection object subjected to ultrasonic vibration; and a control unit for adjusting the frequency of the high-frequency power supplied from the power supply to the ultrasonic vibrator and performing defect detection on the inspection object. The control unit, on the one hand, changes the frequency of the high-frequency power supplied from the power supply to the ultrasonic vibrator, and on the other hand, uses the camera device to capture images of the inspection object, and performs defect detection on the inspection object based on the captured images.

[0014] In this way, the frequency of the high-frequency power supplied by the self-powered source to the ultrasonic vibrator changes, thus enabling the object to be inspected to vibrate ultrasonically at various frequencies, allowing for high-precision detection of defects in the object.

[0015] In the ultrasonic vibration type defect detection device of the present invention, the object to be inspected may include an object part that is the object to be detected as defective and a non-object part that is not the object to be detected as defective. When the frequency of the high-frequency power supplied by the self-powered device to the ultrasonic vibrator changes, the control unit adjusts the voltage of the high-frequency power supplied by the self-powered device to the ultrasonic vibrator in such a way that the ratio of the amplitude of the object part detected according to the image captured by the camera device to the amplitude of the non-object part detected according to the image captured by the camera device is a predetermined value or higher.

[0016] Therefore, when the object to be inspected is subjected to ultrasonic vibration, the amplitude of the object portion becomes larger than that of the non-object portion, enabling high-precision detection of defects in the object portion of the object to be inspected.

[0017] The ultrasonic vibration-type defect detection device of the present invention may also include: a current sensor that detects the current of the high-frequency power supplied by the self-powered source to the ultrasonic vibrator, and a control unit that adjusts the voltage of the high-frequency power supplied by the self-powered source to the ultrasonic vibrator in such a way that the current detected by the current sensor is within a predetermined range when the frequency of the high-frequency power supplied by the self-powered source to the ultrasonic vibrator changes.

[0018] Ultrasonic vibrators possess their own resonant frequency. Therefore, if high-frequency power at the resonant frequency is input to the ultrasonic vibrator during ultrasonic vibration, the resonance causes a decrease in the vibrator's impedance, resulting in a larger amplitude and significant overall vibration of the object being inspected. Consequently, the amplitude of the object's vibration may sometimes be masked by the amplitude of non-objective parts, making it undetectable. Since the amplitude of the ultrasonic vibrator is proportional to the current of the high-frequency power input, by using a current sensor to detect the current and adjusting the voltage of the high-frequency power within a predetermined range, the current and amplitude of the ultrasonic vibrator can be set within a predetermined range. This prevents situations where the entire object vibrates significantly during ultrasonic vibration, and the amplitude of the object's vibration is masked by the amplitude of non-objective parts, thus enabling high-precision detection of defects in the object's parts.

[0019] In the ultrasonic vibration-type defect detection device of the present invention, the control unit may also include a map, which predefines the change of the voltage of the high-frequency power supplied by the self-power source to the ultrasonic vibrator relative to the frequency of the high-frequency power supplied by the self-power source to the ultrasonic vibrator in such a way that the current of the high-frequency power supplied by the self-power source to the ultrasonic vibrator is within a predetermined range. When the frequency of the high-frequency power supplied by the self-power source to the ultrasonic vibrator is changed, the voltage of the high-frequency power supplied by the self-power source to the ultrasonic vibrator is adjusted based on the map.

[0020] Therefore, without adjusting the voltage of the high-frequency power based on the feedback of the current detected by the current sensor, a simple structure can be used to suppress the situation where the overall vibration of the object being inspected is large when the object is subjected to ultrasonic vibration, and the amplitude of the object part is blocked by the amplitude of the non-object part, making it undetectable. Defects in the object part of the object being inspected can be detected with high precision.

[0021] In the ultrasonic vibration-type defect detection device of the present invention, the object to be inspected may also be a semiconductor device, the semiconductor device comprising: a substrate; a semiconductor element mounted on the substrate; and a wire connecting the electrode of the semiconductor element to the electrode of the substrate, or connecting one electrode of the semiconductor element to another electrode of the semiconductor element. When the frequency of the high-frequency power supplied by the self-powered source to the ultrasonic vibrator changes, the control unit adjusts the voltage of the high-frequency power supplied by the self-powered source to the ultrasonic vibrator in such a way that the ratio of the amplitude of the wire detected according to the image captured by the camera device to the amplitude of the substrate and the semiconductor element detected according to the image captured by the camera device is a predetermined value or higher.

[0022] Therefore, when the substrate and semiconductor element are subjected to ultrasonic vibration, the amplitude of the wire becomes larger than the amplitude of the substrate or semiconductor element, which can detect defects in the object part of the object with high precision.

[0023] In the ultrasonic vibration type defect detection device of the present invention, the control unit can also adjust the voltage of the high-frequency power supplied from the power source to the ultrasonic vibrator in such a way that the amplitude of the detected wire exceeds a predetermined upper limit amplitude.

[0024] This can suppress excessive vibration of the wire when the semiconductor device is subjected to ultrasonic vibration.

[0025] In the ultrasonic vibration type defect detection device of the present invention, the control unit may, on the one hand, change the frequency of the high-frequency power supplied by the power source to the ultrasonic vibrator, and on the other hand, use a camera device to capture an animation of the semiconductor device, calculate the difference between a frame of the captured animation and the image of the wire in the previous frame, and output a defect detection signal of the wire when the difference exceeds a predetermined threshold.

[0026] Therefore, defects in the wire can be detected based on the amplitude of the wire's vibration.

[0027] In the ultrasonic vibration type defect detection device of the present invention, the control unit can also calculate the difference by changing the number of frames between the frame that calculates the difference and the previous frame, or by changing the frame rate of the animation.

[0028] Therefore, even when the frequency of the wire changes, the difference in the wire image can be detected, which can improve the detection accuracy of defects.

[0029] In the ultrasonic vibration type defect detection device of the present invention, the ultrasonic vibrator may also be an ultrasonic transducer connected to the object to be inspected and causing the object to be inspected to vibrate ultrasonically, or an ultrasonic horn disposed around the object to be inspected.

[0030] Therefore, a simple structure can be used to detect defects in the object being inspected.

[0031] The present invention discloses a wire defect detection system for detecting defects in the wires of a semiconductor device. The semiconductor device includes: a substrate; a semiconductor element mounted on the substrate; and a wire connecting an electrode of the semiconductor element to an electrode of the substrate, or connecting one electrode of the semiconductor element to another electrode of the semiconductor element. The wire defect detection system is characterized by including: an ultrasonic vibrator for ultrasonically vibrating the semiconductor device; a power supply for supplying high-frequency power to the ultrasonic vibrator; a camera for capturing images of the ultrasonically vibrated semiconductor device; a display for displaying images captured by the camera; and a control unit that, while adjusting the frequency of the high-frequency power supplied from the power supply to the ultrasonic vibrator, performs wire defect detection. The control unit, while varying the frequency of the high-frequency power supplied from the power supply to the ultrasonic vibrator, captures an animation of the semiconductor device using the camera, calculates the difference between a frame of the captured animation and a previous frame, and, when the difference exceeds a predetermined threshold, displays a different image of the wire compared to other wires on the display.

[0032] Thus, when the difference exceeds a predetermined threshold, the displayed image of the cable is different from that of other cables, making it easy to detect cable defects through the display.

[0033] The effects of the invention

[0034] This invention can perform defect detection on the object to be inspected with high precision and in a short time. Attached Figure Description

[0035] Figure 1 This is a system diagram illustrating the structure of the ultrasonic vibration-type defect detection device according to an embodiment.

[0036] Figure 2 To indicate Figure 1 The image shown is of a semiconductor device taken from above by a camera in an ultrasonic vibration-type defect detection device.

[0037] Figure 3 This is a graph illustrating the impedance changes of the ultrasonic transducer and the current changes of the high-frequency power relative to the frequency of the high-frequency power when the voltage of the high-frequency power supplied to the ultrasonic transducer is set to a certain value in the prior art.

[0038] Figure 4 This is a graph illustrating the changes in voltage and current of the high-frequency power supplied to the ultrasonic transducer when the voltage detected by the current sensor changes in a certain manner in the ultrasonic vibration type defect detection device of the embodiment.

[0039] Figure 5 To indicate Figure 1The flowchart shows the operation of the ultrasonic vibration-type defect detection device.

[0040] Figure 6 To make the substrate vibrate ultrasonically Figure 2 Enlarged plan view of part A and Figure 6 An enlarged top view of section B shown.

[0041] Figure 7 To illustrate the mapping of the voltage of the high-frequency power relative to the frequency of the high-frequency power in the ultrasonic vibration type defect detection device of the embodiment, in a manner where the current of the high-frequency power supplied to the ultrasonic transducer is constant.

[0042] Figure 8 To illustrate another mapping of the change in voltage of high-frequency power relative to the frequency of high-frequency power in the ultrasonic vibration type defect detection device of the embodiment, such that the current of the high-frequency power supplied to the ultrasonic transducer is within a predetermined range.

[0043] Figure 9 This is a system diagram illustrating the structure of the wire defect detection system according to the implementation method.

[0044] Figure 10 To indicate Figure 9 The flowchart shown illustrates the operation of the wire defect detection system.

[0045] Figure 11 A top view showing the area beyond which the substrate is subjected to ultrasonic vibration.

[0046] [Explanation of Symbols]

[0047] 10: Semiconductor devices

[0048] 11: Substrate

[0049] 12, 25-28: Electrodes

[0050] 20: Semiconductor components

[0051] 21-24: Semiconductor chips

[0052] 30, 31-34: Wire

[0053] 35, 36: Beyond the area

[0054] 39a, 39b: Center line

[0055] 40: High-frequency power supply

[0056] 42: Ultrasonic transducer

[0057] 43: Ultrasonic speaker

[0058] 45: Camera

[0059] 48: Monitor

[0060] 50: Control Department

[0061] 51: CPU

[0062] 52: Memory

[0063] 53: Voltage sensor

[0064] 54: Current sensor

[0065] 55, 56: Mapping

[0066] 100: Ultrasonic vibration type defect detection device

[0067] 200: Wire Defect Detection System Detailed Implementation

[0068] The following refers to the appendix. Figure 1 The ultrasonic vibration type defect detection device 100 of the embodiment will be described below. In the following description, the ultrasonic vibration type defect detection device 100 will be used to detect defects in the wire 30 of the semiconductor device 10, which is the object of inspection, but it can also be used to detect defects in other objects of inspection.

[0069] like Figure 1 As shown, the ultrasonic vibration type defect detection device 100 includes an ultrasonic transducer 42 as an ultrasonic transducer, a high-frequency power supply 40, a camera 45 as an imaging device, and a control unit 50.

[0070] like Figure 1 As shown, the semiconductor device 10, which is the inspection target of the ultrasonic vibration type defect detection device 100, has semiconductor chips 21 to 24 stacked in four layers on a substrate 11. A wire 30 continuously connects the electrodes 25 to 28 of each semiconductor chip 21 to 24 to the electrode 12 of the substrate 11. Here, semiconductor chips 21 to 24 constitute a semiconductor element 20. The wire 30 includes: a first-order wire 31, connecting the electrode 25 of the first-order semiconductor chip 21 to the electrode 12 of the substrate 11; and second-order wires 32 to fourth-order wires 34, respectively connecting the electrodes 26 to 28 of the second to fourth-order semiconductor chips 22 to 24 to the electrodes 25 to 27 of the first to third-order semiconductor chips 21 to 23. The substrate 11 and semiconductor chips 21 to 24 of the semiconductor device 10 constitute a non-target portion that is not subject to defect detection, while the wire 30 constitutes the target portion for defect detection.

[0071] The high-frequency power supply 40 outputs alternating current at the frequency of the ultrasonic wave region, causing the ultrasonic transducer 42 to vibrate ultrasonically. The ultrasonic transducer 42 is a component that vibrates ultrasonically by being driven by high-frequency power in the frequency range of the ultrasonic wave region input from the high-frequency power supply 40. For example, it may include a piezoelectric element. The ultrasonic transducer 42 is connected to the substrate 11 of the semiconductor device 10, causing the substrate 11 to vibrate ultrasonically.

[0072] Between the high-frequency power supply 40 and the ultrasonic transducer 42, a voltage sensor 53 for detecting the voltage of the high-frequency power supplied from the high-frequency power supply 40 to the ultrasonic transducer 42 and a current sensor 54 for detecting the current of the high-frequency power are installed.

[0073] The camera 45 is positioned on the upper side of the semiconductor device 10, such as... Figure 2 As shown, the image shows a substrate 11, semiconductor chips 21 to 24 mounted on the substrate 11, electrodes 25 to 28 disposed on the outer periphery of semiconductor chips 21 to 24, electrodes 12 of the substrate 11 disposed around the first-order semiconductor chip 21, and wires 30 that continuously connect the electrodes 12, 25 to 28.

[0074] The control unit 50 is a component that internally includes a central processing unit (CPU) 51 and a memory 52. ​​A high-frequency power supply 40 is connected to the control unit 50 and operates according to the instructions of the control unit 50. A camera 45 is connected to the control unit 50 and operates according to the instructions of the control unit 50. The video captured by the camera 45 is input to the control unit 50. A voltage sensor 53 and a current sensor 54 are connected to the control unit 50, and the voltage and current data of the high-frequency power detected by the voltage sensor 53 and the current sensor 54 are input to the control unit 50. The control unit 50, on the one hand, changes the frequency of the high-frequency power supplied from the high-frequency power supply 40 to the ultrasonic transducer 42, and on the other hand, captures images of the semiconductor device 10 captured by the camera 45, and performs defect checks on the semiconductor device 10 based on the captured images.

[0075] Subsequently, on the one hand, referring to Figure 3 On the one hand, it explains the changes in impedance and current A0 relative to frequency f when the voltage V0 of the high-frequency power supplied from the high-frequency power source 40 to the ultrasonic transducer 42 is set to a certain value, as in the prior art.

[0076] like Figure 3 As shown by the dashed line c0, if the voltage V0 of the high-frequency power supplied from the high-frequency power source 40 to the ultrasonic transducer 42 is set to a constant, and the frequency f of the high-frequency power is varied, then the ultrasonic transducer 42 will resonate at a frequency f1. Therefore, the impedance of the ultrasonic transducer 42 is as follows: Figure 3 As shown by the dashed line a, the impedance decreases significantly at frequency f1. On the other hand, at frequency f2, which is between frequency f1 and the maximum frequency f3, the impedance of the ultrasonic transducer 42 increases significantly.

[0077] If so Figure 3 As shown by the dashed line a, the impedance of the ultrasonic transducer 42 decreases significantly near the frequency f1, then as... Figure 3 As shown by the solid line b0, the current A0 supplied to the ultrasonic transducer 42 increases significantly. Conversely, if the impedance of the ultrasonic transducer 42 increases significantly near the frequency f2, the current A0 supplied to the ultrasonic transducer 42 decreases significantly. The magnitude of the current A0 supplied to the ultrasonic transducer 42 is proportional to the amplitude of the ultrasonic transducer 42. Therefore, near the resonant frequency f1 of the ultrasonic transducer 42, the amplitude of the ultrasonic transducer 42 increases significantly while the amplitude of the substrate 11 increases significantly; near the frequency f2, the amplitude of the ultrasonic transducer 42 decreases significantly while the amplitude of the substrate 11 decreases significantly.

[0078] Therefore, at the resonant frequency f1 of the ultrasonic transducer 42, the substrate 11, semiconductor chips 21 to 24 and wire 30 all vibrate significantly. As a result, the amplitude of the wire 30 is sometimes obscured by the amplitude of the substrate 11 and semiconductor chips 21 to 24 and is difficult to detect.

[0079] Conversely, at frequency f2, the amplitudes of substrate 11, semiconductor chips 21 to 24 and wire 30 become very small, and sometimes the amplitude of wire 30 cannot be detected.

[0080] As explained above, when the voltage V0 supplied by the high-frequency power supply 40 to the ultrasonic transducer 42 is set to a constant and the frequency is varied, as in the prior art, it is sometimes difficult to detect the amplitude of the wire 30 near the resonant frequency f1 of the ultrasonic transducer 42.

[0081] Therefore, in the ultrasonic vibration type defect detection device 100 of the embodiment, considering that the amplitude of the ultrasonic transducer 42 is proportional to the current of the high-frequency power input to the ultrasonic transducer, the current A1 of the high-frequency power input to the ultrasonic transducer 42 is detected by the current sensor 54, and the voltage V1 of the high-frequency power is adjusted so that the detected current A1 is within a predetermined range. Thus, the current A1 of the high-frequency power can be set within a predetermined range, and the amplitude of the ultrasonic transducer 42 can be set within a predetermined range. Furthermore, when the frequency of the high-frequency power is changed to cause the semiconductor device 10 to vibrate ultrasonically, the following situation can be suppressed: the amplitude of the substrate 11 or semiconductor element 20, which is not the target part of the detection, vibrates significantly at a specific frequency, and the amplitude of the wire 30, which is the target part of the detection, is blocked by the amplitude of the substrate 11 or semiconductor element 20 and cannot be detected.

[0082] The following refers to, on the one hand, Figure 4 On the one hand, in the ultrasonic vibration type defect detection device 100 of the embodiment, when the voltage V1 of the high-frequency power supplied to the ultrasonic transducer 42 changes in a certain way due to the current A1 detected by the current sensor 54, the operation of the change of voltage V1 and current A1 of the high-frequency power will be explained.

[0083] In the ultrasonic vibration type defect detection device 100 of the embodiment, the current A1 detected by the current sensor 54 is fed back to the control unit 50. Near the frequency f1 where the high-frequency current A1 increases, such as... Figure 4 As shown by the dashed line c1, the voltage V1 of the high-frequency power supplied to the ultrasonic transducer 42 is reduced. On the other hand, near the frequency f2 where the current A1 detected by the current sensor 54 decreases, such as Figure 4 As shown by the dashed line c1, the voltage V1 of the high-frequency power supplied to the ultrasonic transducer 42 is increased. Thus, it can be done as follows: Figure 4 As shown by the solid line d1 in the figure, the magnitude of the current A1 detected by the current sensor 54 is approximately constant and independent of the frequency f.

[0084] In this way, by feedback control in a manner that the current A1 of the high-frequency power supplied to the ultrasonic transducer 42 from the high-frequency power source 40 is kept approximately constant, the amplitude of the ultrasonic transducer 42 can be kept approximately constant even when the frequency f of the high-frequency power is changed, and the amplitudes of the substrate 11 and the semiconductor element 20 can be kept approximately constant.

[0085] Furthermore, the voltage can be adjusted so that the ratio of the amplitude of the wire 30 detected based on the image captured by the camera 45 to the amplitude of the substrate 11 and semiconductor element 20 detected based on the image captured by the camera 45 is at least a predetermined value. This suppresses the reduction in detection accuracy caused by interference from the amplitude of the substrate 11 or semiconductor element 20 at each frequency f, reliably detecting the amplitude of the wire 30 and enabling high-precision detection of defects in the wire 30. Additionally, by checking the image of the wire 30 captured by the camera 45 while adjusting the high-frequency power voltage to ensure that the amplitude of the wire 30 does not exceed the upper limit, damage to the wire 30 due to excessive vibration during defect detection can be suppressed.

[0086] Subsequently, on the one hand, referring to Figure 5 , Figure 6 On the one hand, the detection operation of the ultrasonic vibration type defect detection device 100 for defects in wire 30 will be explained.

[0087] like Figure 5 As shown in step S101, the CPU 51 of the control unit 50 adjusts the voltage V1 of the high-frequency power in such a way that the current A1 detected by the current sensor 54 is approximately constant, and changes the frequency f of the high-frequency power and causes the semiconductor device 10 to vibrate ultrasonically.

[0088] Control unit 50 Figure 5 As shown in step S102, an animation of the positively vibrating semiconductor device 10 is captured, as follows. Figure 5 As shown in step S103, the captured image data is saved in memory 52.

[0089] The CPU 51 of the control unit 50 causes the frequency of the high-frequency power to vary within a predetermined range of ultrasonic frequencies, captures the animation of the semiconductor device 10 and saves it to the memory 52, and then enters... Figure 5 In step S104, the image of a frame is compared with the image of the wire 30 of the previous frame, and the position difference Δd is calculated.

[0090] Figure 6 The wire 30a shown in detail in section A is normally connected to each of the electrodes 12, 25-28. If the wire 30a is subjected to ultrasonic vibration, the first-order wires 31a to the fourth-order wires 34a vibrate laterally at the natural frequency g0 between each of the electrodes 12, 25-27 connected to the lower end of the first-order wires 31a to the fourth-order wires 34a and each of the electrodes 25-28 connected to the upper end. The natural frequency g0 varies depending on the diameter of the wire 30a and the spacing L of the electrodes 25, 26 and 27, but in typical semiconductor devices 10, it is mostly in the tens of hertz (Hz) range.

[0091] On the other hand, regarding the defective wire 30b, it is not connected to the electrode 26 of the second-order semiconductor chip 22. Therefore, if the defective wire 30b is subjected to ultrasonic vibration, the second-order wire 32b and the third-order wire 33b vibrate laterally at the natural frequency g1 between the electrode 25 of the first-order semiconductor chip 21 and the electrode 27 of the third-order semiconductor chip 23. In this example, as Figure 6 As shown in detail in Part B, the distance L between electrodes 25 and 27 is twice the distance L between electrodes 25, 26 and electrodes 26, 27, i.e., 2L. Therefore, the natural frequency g1 of the second-order wire 32b and the third-order wire 33b of the defective wire 30b is about half of g0. In a typical semiconductor device 10, this is mostly in the 20Hz to 30Hz range.

[0092] The first-order wires 31a to 34a of the normally connected cable 30a vibrate laterally at a natural frequency g0 of tens of Hz. The frame rate of the animation is 24 to 60 frames per second. Therefore, for example, the image of the first-order wires 31a to 34a of one frame is displayed in... Figure 6 In the detailed section of part A, the center line 39a of wire 30a is a dotted line to the left of it, as shown in the image of the previous front frame. Figure 6 In the detailed section of part A, it becomes a dotted line to the right of the center line 39a of wire 30a.

[0093] The CPU 51 of the control unit 50 is in Figure 5 In step S104, Figure 6 The image of the first-order wires 31a to 34a of a frame shown in detail in Part A is compared with the image of the first-order wires 31a to 34a of the previous frame, and the difference Δda is calculated. Figure 6 As detailed in Part A, the difference Δda is small under normal wire 30a conditions. Furthermore, the difference Δda is a quantity proportional to the amplitude of the first-order wire 31a to the fourth-order wire 34a.

[0094] On the other hand, the second-order wires 32b and 33b, which are in a non-connected state between the defective wires 30b and the electrodes 26 of the second-order semiconductor chip 22, vibrate laterally at a large amplitude of 20Hz to 30Hz. As mentioned above, the frame rate of the animation is 24 to 60 frames per second. For example, the image of the second-order wires 32b and 33b in one frame... Figure 6 In the detailed sections A and B, the image of the previous frame is shown as a dotted line to the left of the center line 39b of the defective wire 30b. Figure 6 In the detailed sections A and B, a dotted line appears to the right of the center line 39b of the defective wire 30b.

[0095] The situation is similar for the CPU 51 of the control unit 50 and the wire 30a, as follows: Figure 6 As detailed in Part B, the difference Δdb between the images of the second-order wires 32b and 33b of a current frame and the images of the second-order wires 32b and 33b of the previous frame is calculated. Figure 6 As detailed in Part B, for the second-order wire 32b and the third-order wire 33b of the defective wire 30b, the difference Δdb is very large, exceeding the predetermined threshold ΔS. Furthermore, the difference Δdb becomes a quantity proportional to the amplitude of the second-order wire 32b and the third-order wire 33b.

[0096] The CPU 51 of the control unit 50, such as Figure 6 As detailed in Part B, when the difference Δdb between the image of the second-order wire 32b and the third-order wire 33b of a frame and the image of the second-order wire 32b and the third-order wire 33b of the previous frame exceeds a predetermined threshold ΔS, in Figure 5 If the condition in step S105 is "yes" (YES), proceed to... Figure 5 In step S106, a wire defect detection signal indicating that the wire 30 of the semiconductor device 10 is defective is output to the outside.

[0097] On the other hand, when the difference Δd of any wire 30 does not exceed a predetermined threshold ΔS, the CPU 51 of the control unit 50, Figure 5 If the result in step S105 is negative (NO), proceed to... Figure 5 In step S107, a good signal indicating that the wire 30 of the semiconductor device 10 is good is output to the outside.

[0098] As explained above, the ultrasonic vibration-type defect detection device 100 of the embodiment performs feedback control to keep the current A1 of the high-frequency power supplied from the high-frequency power source 40 to the ultrasonic transducer 42 approximately constant. Therefore, even when the frequency f of the high-frequency power changes, the amplitude of the ultrasonic transducer 42 can be kept approximately constant, as can the amplitudes of the substrate 11 and the semiconductor element 20. Furthermore, by adjusting the voltage so that the ratio of the amplitude of the wire 30 detected based on the image captured by the camera 45 to the amplitudes of the substrate 11 and the semiconductor element 20 detected based on the image captured by the camera 45 is at least a predetermined value, the amplitude of the wire 30 being buried within the amplitudes of the substrate 11 and the semiconductor element 20 can be suppressed. Thus, the amplitude of the wire 30 being buried within the amplitudes of the substrate 11 and the semiconductor element 20 can be suppressed at various frequencies, and the amplitude of the wire 30 can be reliably detected at various frequencies.

[0099] Furthermore, the frequency at which the wire 30 vibrates significantly due to its disconnection varies depending on the location of the disconnection, the distance L between electrodes 12 and electrodes 25-28, and the diameter of the wire 30. The ultrasonic vibration-type defect detection device 100 of this embodiment can reliably detect the amplitude of the wire 30 at various frequencies. Therefore, it can detect the amplitude of the wire 30 at frequencies where its amplitude is large due to the disconnection, enabling high-precision and short-time defect detection of the wire 30.

[0100] The above explanation assumes that the current A1 of the high-frequency power supplied to the ultrasonic transducer 42 by the high-frequency power source 40 is kept approximately constant through feedback control. Thus, even when the frequency f of the high-frequency power source changes, the amplitude of the ultrasonic transducer 42 remains approximately constant, but this is not the only possibility.

[0101] For example, as referenced Figure 3 As explained, the change in the current A0 of the high-frequency power is obtained in advance through experiments, etc., while keeping the voltage V0 of the high-frequency power constant and changing the frequency, and then generated as follows. Figure 7 The dashed line c2 shows the voltage waveform that corresponds to the increase and decrease of current A0. This voltage waveform is pre-stored in memory 52 as a mapping 55 representing the change of voltage V2 relative to frequency f. Figure 7 As shown by the dashed line c2, mapping 55 produces a waveform where the voltage decreases near frequency f1 and increases at frequency f2. Furthermore, during ultrasonic vibration, the voltage relative to frequency f can be adjusted by referring to mapping 55 stored in memory 52. ​​At this time, as... Figure 7 As shown by the solid line d2, even if the frequency changes, the current A2 supplied to the ultrasonic transducer 42 remains approximately constant.

[0102] Therefore, a simple structure can be used to suppress the following situation: when the semiconductor device 10 is subjected to ultrasonic vibration in various frequency bands, the semiconductor device 10 vibrates significantly as a whole, and the amplitude of the wire 30, which is the target part, is blocked by the amplitude of the substrate 11 or the semiconductor element 20 and cannot be detected, so that defects in the target part of the object can be detected with high precision.

[0103] In addition, it can simplify the experiment, for example... Figure 8 As shown by the dashed line c3, the voltage waveform that causes the voltage V3 to vary in a stepwise manner with respect to the frequency f is stored as a mapping 56 in the memory 52. ​​In the case described, as... Figure 8 As shown by the solid line d3, although the current A3 supplied to the ultrasonic transducer 42 is not approximately constant, it is within a given range ΔA. Therefore, a simpler method can be used to perform high-precision and short-time defect detection of the wire 30.

[0104] Furthermore, the CPU 51 of the control unit 50 can also calculate the image difference Δd of the wire 30 by adjusting the number of frames between a frame that calculates the image difference Δd and the previous frame, or by adjusting the frame rate of the animation, when the semiconductor device 10 is subjected to ultrasonic vibration. Therefore, even when the frequency of the wire 30 changes, the image difference Δd of the wire 30 can be detected, improving the accuracy of defect detection.

[0105] Then, referring to Figure 9 The wire defect detection system 200 of the implementation method will be described. Figure 9 The wire defect detection system 200 shown detects defects in the wires 30 of a semiconductor device 10. The semiconductor device 10 includes: a substrate 11; semiconductor chips 21 to 24 mounted on the substrate 11; and wires 31 to 34, connecting electrodes 25 to 28 of the semiconductor chips 21 to electrodes 12 of the substrate 11, or connecting one electrode 25 to 28 of the semiconductor chips 21 to the other electrode 25 to 28 of the semiconductor chips 21 to the other electrode 25 to 28 of the semiconductor chips 24. The wire defect detection system 200 may also use an ultrasonic transducer 42, which is the ultrasonic vibrator of the ultrasonic vibration type defect detection device 100 described above, as an ultrasonic speaker 43, and add a display 48 to the control unit 50 to display images captured by a camera 45. Furthermore, the wire defect detection system 200 does not include a voltage sensor 53 or a current sensor 54 mounted on the ultrasonic vibration type defect detection device 100; reference data is stored in the memory 52 of the control unit 50. Figure 7 , Figure 8 The mapping 55 or mapping 56 is described above. Furthermore, when the frequency f of the high-frequency power supplied from the high-frequency power source 40 to the ultrasonic horn 43 changes, the CPU 51 of the control unit 50 adjusts the voltage of the high-frequency power supplied from the high-frequency power source 40 to the ultrasonic horn 43 based on mapping 55 or mapping 56. The structure other than this is the same as the ultrasonic vibration type defect detection device 100 described above.

[0106] An ultrasonic horn 43 is disposed around the semiconductor device 10 to cause the semiconductor device 10 to vibrate ultrasonically.

[0107] On the one hand, refer to Figure 10 , Figure 11 The operation of the wire defect detection system 200 is explained. This is in accordance with the above description. Figure 5 , Figure 6 The ultrasonic vibration type defect detection device 100 described herein operates the same way, and the same step numbers are marked but the description is omitted.

[0108] like Figure 10As shown in steps S201 and S102 to S104, the CPU 51 of the control unit 50 adjusts the voltage V1 of the high-frequency power supply in a manner that keeps the current A1 detected by the current sensor 54 approximately constant, while simultaneously changing the frequency f of the high-frequency power supply to cause the semiconductor device 10 to vibrate ultrasonically. Then, the CPU 51 of the control unit 50 captures an animation of the vibrating semiconductor device 10's wire 30 and saves the captured image data to the memory 52. ​​Next, the control unit 50 changes the frequency of the high-frequency power supply within a predetermined ultrasonic frequency range, captures an animation of the semiconductor device 10, saves it to the memory 52, and, similarly as described above, compares the image of one frame with the image of the previous frame to calculate the difference Δd between the images of the wire 30.

[0109] The CPU 51 of the control unit 50, such as Figure 6 As detailed in Part B, when the difference Δdb between the image of the second-order wire 32b and the third-order wire 33b of a frame and the image of the second-order wire 32b and the third-order wire 33b of the previous frame exceeds a predetermined threshold ΔS, in Figure 10 If the condition in step S105 is "yes" (YES), proceed to... Figure 10 In step S202, the images displayed on the display 48 of the second-order wire 32b and the third-order wire 33b are different from the images displayed on the first-order wire 31a to the fourth-order wire 34a of the normally connected wire 30a.

[0110] Regarding different displays, there are various displays. For example, the images of the second-order wires 32b and third-order wires 33b of the defective wire 30b can be displayed in red. Alternatively, a high-brightness white display can be used to distinguish it from the images of the substrate 11 and each semiconductor chip 21-24, or the images of the first-order wires 31a to fourth-order wires 34a of the normally connected wires 30a.

[0111] If the inspector views the image on the monitor 48, for example, since the defective cable 30b is displayed in red, the presence and location of the defective cable 30b can be detected at a glance.

[0112] The CPU 51 of the control unit 50 is in Figure 10 In step S105, if the result is negative (NO), the processing ends without making the image different.

[0113] In addition, the CPU 51 of the control unit 50 can also be like Figure 11 As shown, when the difference Δdb between the image of the second-order wire 32b and the third-order wire 33b of a frame and the image of the second-order wire 32b and the third-order wire 33b of the previous frame exceeds a predetermined threshold ΔS, then... Figure 11The images of the areas 35 and 36 where the difference Δdb between the vibration regions of the second-order wire 32b and the third-order wire 33b shown in the mid-shadow line exceeds a predetermined threshold ΔS, are displayed on the monitor 48 differently from the images of other areas. For example, when areas 35 and 36 are displayed in red, a wider area than the images of the second-order wire 32b and the third-order wire 33b of the defective wire 30b is displayed in red, thus making it easier for the inspector to detect the defective wire 30b.

[0114] As explained above, the wire defect detection system 200 of this embodiment, in addition to having the same effect as the ultrasonic vibration type defect detection device 100 described above, can also distinguish the display image of the defective wire 30b from other display images and display it on the display 48. Therefore, the inspector can detect the defective wire 30b through the image on the display 48. The amplitude of the defective wire 30b differs significantly from the amplitude of the normally connected wire 30a, thus enabling high-precision detection of the defective wire 30b. Furthermore, the camera 45 can acquire images of all the wires 30 contained in the semiconductor device 10, analyze them simultaneously, and display them on the display 48; therefore, even if the number of wires 30 increases, defect inspection of all wires 30 can be performed in a short time.

Claims

1. An ultrasonic vibration-type defect detection device for detecting defects in an object under inspection, characterized in that... include: An ultrasonic vibrator is used to cause the object being inspected to vibrate ultrasonically. A power source supplies high-frequency power to the ultrasonic vibrator. A camera device is used to capture images of the object being inspected, which is subjected to ultrasonic vibrations; and The control unit adjusts the frequency of the high-frequency power supplied from the power source to the ultrasonic vibrator and performs defect detection on the object under inspection. The control unit, on the one hand, changes the frequency of the high-frequency power supplied from the power source to the ultrasonic vibrator, and on the other hand, uses the camera device to capture images of the object under inspection, and detects defects in the object under inspection based on the captured images. The object to be inspected includes the object portion that becomes a defective inspection object and the non-object portion that does not become a defective inspection object. When the frequency of the high-frequency power supplied from the power source to the ultrasonic vibrator changes, the control unit adjusts the voltage of the high-frequency power supplied from the power source to the ultrasonic vibrator in such a way that the ratio of the amplitude of the target portion detected according to the image captured by the camera device to the amplitude of the non-target portion detected according to the image captured by the camera device is a predetermined value or higher.

2. The ultrasonic vibration type defect detection device according to claim 1, characterized in that... include: A current sensor detects the current from the high-frequency power supplied by the power source to the ultrasonic vibrator. When the frequency of the high-frequency power supplied from the power source to the ultrasonic vibrator is varied, the control unit adjusts the voltage of the high-frequency power supplied from the power source to the ultrasonic vibrator in such a way that the current detected by the current sensor is within a predetermined range.

3. The ultrasonic vibration type defect detection device according to claim 1, characterized in that... The control unit includes a mapping that predefines the variation of the voltage of the high-frequency power supplied from the power source to the ultrasonic vibrator relative to the frequency of the high-frequency power supplied from the power source to the ultrasonic vibrator, such that the current of the high-frequency power supplied from the power source to the ultrasonic vibrator is within a predetermined range. When the frequency of the high-frequency power supplied from the power source to the ultrasonic vibrator is varied, the voltage of the high-frequency power supplied from the power source to the ultrasonic vibrator is adjusted based on the mapping.

4. The ultrasonic vibration type defect detection device according to any one of claims 1 to 3, characterized in that... The object to be inspected is a semiconductor device, comprising: a substrate; a semiconductor element mounted on the substrate; and wires connecting the electrodes of the semiconductor element to the electrodes of the substrate, or connecting one electrode of the semiconductor element to another electrode of the semiconductor element. When the frequency of the high-frequency power supplied from the power source to the ultrasonic vibrator changes, the control unit adjusts the voltage of the high-frequency power supplied from the power source to the ultrasonic vibrator in such a way that the ratio of the amplitude of the wire detected according to the image captured by the camera device to the amplitude of the substrate and the semiconductor element detected according to the image captured by the camera device is a predetermined value or higher.

5. The ultrasonic vibration type defect detection device according to claim 4, characterized in that... The control unit adjusts the voltage of the high-frequency power supplied from the power source to the ultrasonic vibrator in such a way that the amplitude of the detected wire does not exceed a predetermined upper limit amplitude.

6. The ultrasonic vibration type defect detection device according to claim 4, characterized in that... The control unit, on the one hand, changes the frequency of the high-frequency power supplied from the power source to the ultrasonic vibrator, and on the other hand, uses the camera device to capture animation of the semiconductor device. Calculate the difference between the image of a frame in the captured animation and the image of the line drawing from the previous frame. When the difference exceeds a predetermined threshold, a defect detection signal for the wire is output.

7. The ultrasonic vibration type defect detection device according to claim 6, characterized in that... The control unit calculates the difference by calculating the number of frames between a frame and the previous frame, or by calculating the frame rate change of the animation.

8. The ultrasonic vibration type defect detection device according to claims 1 to 3, characterized in that... The ultrasonic vibrator is an ultrasonic transducer connected to the object being inspected and causing the object to vibrate ultrasonically, or an ultrasonic horn disposed around the object being inspected.

9. A wire defect detection system for detecting defects in the wires of a semiconductor device, the semiconductor device comprising: substrate; Semiconductor components are mounted on the substrate; The system also includes wires for connecting the electrodes of the semiconductor element to the electrodes of the substrate, or connecting one electrode of the semiconductor element to another electrode of the semiconductor element, and the wire defect detection system is characterized by comprising: An ultrasonic vibrator causes the semiconductor device to vibrate ultrasonically. A power source supplies high-frequency power to the ultrasonic vibrator. A camera device for capturing images of the semiconductor device subjected to ultrasonic vibrations; A display screen showing images captured by the camera device; and The control unit adjusts the frequency of the high-frequency power supplied from the power source to the ultrasonic vibrator and performs defect detection on the wire. The control unit, on the one hand, changes the frequency of the high-frequency power supplied from the power source to the ultrasonic vibrator, and on the other hand, uses the camera device to capture animation of the semiconductor device. Calculate the difference between a frame of the captured animation and the previous frame. When the difference exceeds a predetermined threshold, the display image of the cable is made different from the display images of the other cables and displayed on the monitor. The semiconductor device includes an object section that becomes a defective detection object and a non-object section that does not become a defective detection object. When the frequency of the high-frequency power supplied from the power source to the ultrasonic vibrator changes, the control unit adjusts the voltage of the high-frequency power supplied from the power source to the ultrasonic vibrator in such a way that the ratio of the amplitude of the target portion detected according to the image captured by the camera device to the amplitude of the non-target portion detected according to the image captured by the camera device is a predetermined value or higher.

Images