Joint quality determination system and joint quality determination method

Abstract

A tool (22) holds a semiconductor chip (5). A vibrator (25) applies ultrasonic energy to the tool (22). During ultrasonic bonding, a sensor (30) acquires a signal waveform of vibration generated between the tool (22) and the semiconductor chip (5). A calculation unit (15) determines a quality of a joint state between the semiconductor chip (5) and a substrate (8) on the basis of the signal waveform.

Description

Joint quality determination system and joint quality determination method

[0001] The present invention relates to a bonding quality determination system and a bonding quality determination method.

[0002] Patent Document 1 discloses an ultrasonic bonding control device that includes a first vibration sensor that is brought into contact with the workpieces to be bonded, a second vibration sensor that is provided on the contactor side, and an abnormality detection unit that monitors the output signal of the first vibration sensor or the second vibration sensor.

[0003] In the invention of Patent Document 1, the signal amplitude of the output signal of the first vibration sensor or the second vibration sensor is compared with a first judgment threshold or a second judgment threshold to determine that a poor joint, crack breakage, or joint peeling abnormality has occurred.

[0004] Patent No. 514873

[0005] However, for example, when multiple bumps provided on a semiconductor chip as a first component are ultrasonically bonded to electrode pads on a substrate as a second component, there is a risk of poor bump bonding occurring at certain positions within the surface of the semiconductor chip.

[0006] Possible causes of poor bump bonding include particles at the bonding interface, variations in bump height, tilt of the stage on which the bonded members are mounted or the semiconductor chip, and the like.

[0007] However, the invention of Patent Document 1 can only determine whether the bonding is good or bad, such as whether there is a bonding separation abnormality or crack or breakage, and cannot determine whether the bonding state is good or bad within the surface of the semiconductor chip.

[0008] The present invention has been made in view of the above points, and an object of the present invention is to make it possible to determine whether the joining state between a first member and a second member is good or bad.

[0009] A first invention is a bonding quality determination system that ultrasonically bonds a first member and a second member and determines the quality of the bonded state, and includes a tool that holds the first member, a vibrator that applies ultrasonic energy to the tool, a sensor that acquires a signal waveform of vibrations that occur between the tool and the first member during ultrasonic bonding, and a calculation unit that determines the quality of the bonded state between the first member and the second member based on the signal waveform.

[0010] In the first invention, the quality of the joining state between the first member and the second member can be determined by acquiring the signal waveform of the vibration generated between the tool and the first member during ultrasonic joining.

[0011] Specifically, when the first member and the second member are ultrasonically joined while the first member is held in an inclined position by the tool, the load applied to the joining surface of the first member varies, which causes variations in the joining strength within the plane of the joining surface of the first member, and there is a risk of poor joining.

[0012] In contrast to this, in the present embodiment, the quality of the joining condition between the first member and the second member can be determined by monitoring and analyzing the signal waveform of the vibrations that occur between the tool and the first member, specifically, the frictional vibrations that occur due to sliding between the tool and the first member.

[0013] A second invention is a bonding quality determination system according to the first invention, wherein the calculation unit determines that the bonding condition between the first member and the second member is good when the amplitude of the signal waveform is greater than a predetermined reference value.

[0014] In the second aspect of the present invention, if the amplitude of the signal waveform is greater than a predetermined reference value, it can be assumed that the first and second members have been ultrasonically joined normally by metal diffusion, and that a large amount of frictional vibration is occurring between the tool and the first member, thereby making it possible to determine that the joining condition is good.

[0015] Here, the reference value may be calculated from a signal waveform acquired by the sensor when the first member and the second member are uniformly joined at the joining surface.

[0016] In a third aspect of the present invention, in the bonding quality determination system according to the second aspect of the present invention, the calculation unit acquires frequency characteristics of peak components and valley components of the signal waveform.

[0017] In the third aspect of the present invention, the signal waveform acquired by the sensor is divided into peak components and valley components and analyzed, thereby making it possible to determine whether the joining state between the first member and the second member is good or bad.

[0018] A fourth invention is a system for determining the quality of a bond of the third invention, wherein, during ultrasonic bonding, the tool alternately performs a first action of moving toward one end of the vibration direction and a second action of moving toward the other end of the vibration direction, and the calculation unit determines whether the tool is performing the first action or the second action based on a change in the current value of the vibrator, and synchronizes the first action with one of the peak or valley components of the signal waveform, and synchronizes the second action with the other component.

[0019] In the fourth invention, by synchronizing the first operation of the tool with one of the peak or valley components of the signal waveform and synchronizing the second operation of the tool with the other component, it is possible to determine whether a poor joint has occurred on one end or the other end of the vibration direction on the joining surface of the first member.

[0020] A fifth invention is a joining quality determination system according to any one of the first to fourth inventions, in which a plurality of sensors are provided, and the plurality of sensors are arranged in positions that are symmetrical with respect to a center line extending along the vibration direction of the tool.

[0021] In the fifth aspect of the present invention, by using a plurality of sensors to monitor and analyze a plurality of signal waveforms, it is possible to improve the accuracy of determining whether the joining state of the first member and the second member is good or bad.

[0022] A sixth invention is a method for determining whether a first member is ultrasonically joined to a second member and whether the joined state is good or bad, comprising the steps of: holding the first member by suction with a tool and ultrasonically joining the first member to the second member; acquiring a signal waveform of vibrations generated between the tool and the first member during ultrasonic joining; and determining whether the joined state between the first member and the second member is good or bad based on the signal waveform.

[0023] In the sixth invention, the quality of the joining state between the first member and the second member can be determined by acquiring the signal waveform of the vibration generated between the tool and the first member during ultrasonic joining.

[0024] According to the present invention, it is possible to determine whether the joining state between the first member and the second member is good or bad.

[0025] 1 is a side view showing a schematic configuration of a bond quality determination system according to a first embodiment; FIG. 2 is a plan view showing a schematic configuration of an ultrasonic bonding device; FIG. 3 is a side view showing a configuration of bumps and electrode pads when the bonding state between a semiconductor chip and a substrate is good; FIG. 4 is a side view showing a state in which a bond defect has occurred on the left side of the surface of a semiconductor chip; FIG. 5 is a side view showing a state in which a bond defect has occurred on the right side of the surface of a semiconductor chip; FIG. 6 is a graph showing a signal waveform acquired by a sensor; FIG. 7 is a graph showing a signal waveform of a peak component; FIG. 8 is a graph showing a signal waveform of a valley component; and FIG. 9 is a flowchart showing a procedure for determining whether a bond is good or bad; FIG. 10 is a plan view showing a schematic configuration of an ultrasonic bonding device according to a second embodiment; FIG. 11 is a side view showing a state in which a bond defect has occurred on the front side of the surface of a semiconductor chip; FIG. 12 is a side view showing a state in which a bond defect has occurred on the rear side of the surface of a semiconductor chip; FIG. 13 is a graph showing a signal waveform acquired by a sensor; FIG. 14 is a graph showing a signal waveform of a peak component; FIG. 15 is a graph showing a signal waveform of a valley component; and FIG. 16 is a flowchart showing a procedure for determining whether a bond is good or bad; and FIG. 17 is a plan view illustrating an arrangement of sensors according to another embodiment.

[0026] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present invention is not limited to the following embodiments. Furthermore, appropriate modifications are possible within the scope of the effects of the present disclosure. In each drawing, arrows indicate up / down and front / rear / left / right directions. Unless otherwise specified, directions such as up / down will be described according to the directions indicated by these arrows.

[0027] 1 and 2, an ultrasonic bonding apparatus 10 ultrasonically bonds a semiconductor chip 5 as a first member to a substrate 8 as a second member. A plurality of bumps 6 are provided on the bonding surface (the lower surface in FIG. 1) of the semiconductor chip 5. A plurality of electrode pads 9 are provided on the bonding surface (the upper surface in FIG. 1) of the substrate 8.

[0028] The ultrasonic bonding device 10 includes a stage 11 , a mounting head driving mechanism 12 , a control unit 13 , and an ultrasonic head 20 .

[0029] The substrate 8 is placed on the stage 11. Above the stage 11, an ultrasonic head 20 is disposed.

[0030] The ultrasonic head 20 is configured to be movable in the vertical direction relative to the stage 11. The ultrasonic head 20 includes a head body 21, a tool 22, and a vibrator 25.

[0031] The head body 21 is provided with a tool 22 and a vibrator 25. The tool 22 is provided at a position on the head body 21 facing the substrate 8 on the stage 11.

[0032] The vibrator 25 applies ultrasonic energy to the tool 22 via the head body 21. In the example shown in Fig. 1, the vibrator 25 is provided at the right end of the head body 21. The head body 21 vibrates ultrasonically in the left-right direction. The head body 21 functions as a horn that amplifies and transmits the ultrasonic energy.

[0033] The tool 22 ultrasonically vibrates in the left-right direction together with the head body 21. The tool 22 has a suction hole 23 formed therein. The suction hole 23 opens downwardly of the tool 22. The tool 22 sucks air through the suction hole 23, thereby suctioning and holding the semiconductor chip 5 at the lower end of the tool 22.

[0034] The mounting head driving mechanism 12 moves the ultrasonic head 20 between a bonding position and a retracted position. The bonding position is a position where the bumps 6 of the semiconductor chip 5 are pressed against the electrode pads 9 of the substrate 8 for ultrasonic bonding. The retracted position is a position where the semiconductor chip 5 is separated from the substrate 8.

[0035] The control unit 13 controls the operation of the mounting head driving mechanism 12 , the operation of the vibrator 25 , and the suction operation of the tool 22 .

[0036] The ultrasonic bonding device 10 applies ultrasonic energy to the tool 22 using the vibrator 25 while pressing the bumps 6 of the semiconductor chip 5, which is held by suction on the tool 22, against the electrode pads 9 of the substrate 8 placed on the stage 11 using the mounting head drive mechanism 12.

[0037] As a result, pressure load, heat, and ultrasonic energy are applied between the semiconductor chip 5 and the substrate 8, which promotes plastic deformation of the bumps 6 and the electrode pads 9, and the newly formed surfaces of the bumps 6 and the electrode pads 9 come into contact with each other, causing diffusion of the metals between the bumps 6 and the electrode pads 9. As a result, the bumps 6 of the semiconductor chip 5 and the electrode pads 9 of the substrate 8 are bonded together.

[0038] <Bonding quality determination system> However, for example, when multiple bumps 6 provided on a semiconductor chip 5 are ultrasonically bonded to electrode pads 9 on a substrate 8, the bonding strength may vary at certain positions on the surface of the semiconductor chip 5, which may result in poor bump bonding.

[0039] Specifically, if the load applied within the surface of the semiconductor chip 5 varies during ultrasonic bonding, the way the bumps 6 are crushed may differ within the chip surface, resulting in a difference in the bump bonding strength.

[0040] Possible causes of poor bump bonding include, for example, particles adhering to the bonding interface between the semiconductor chip 5 and the substrate 8, variations in the height of the bumps 6 on the semiconductor chip 5, and tilt of the stage 11 on which the substrate 8 is mounted or the semiconductor chip 5.

[0041] Therefore, in this embodiment, it is possible to determine whether the bonding state between the semiconductor chip 5 and the substrate 8 is good or bad.

[0042] Specifically, the bond quality determination system 1 includes an ultrasonic bonding apparatus 10, a sensor 30, and a calculation unit 15. The sensor 30 is, for example, an acoustic emission sensor. The sensor 30 is a semiconductor sensor using a piezoelectric element that responds in the frequency range from several kHz to several hundred MHz. The sensor 30 acquires a signal waveform of vibrations occurring between the tool 22 and the semiconductor chip 5 during ultrasonic bonding.

[0043] In this embodiment, the ultrasonic energy applied by the vibrator 25 is, for example, 60 kHz. However, the ultrasonic energy to be applied is not limited to this form and may be set appropriately depending on the members to be joined.

[0044] The sensor 30 is provided on the ultrasonic head 20. In the example shown in Fig. 1, the sensor 30 is provided on the mounting head driving mechanism 12 side of the ultrasonic head 20. By installing the sensor 30 in this manner at a position where the ultrasonic head 20 is least likely to vibrate when ultrasonic energy is applied, monitoring data of the vibration signal waveform can be acquired with high sensitivity.

[0045] The sensor 30 may be provided on the stage 11. In this case, the sensor 30 is positioned closer to the joint between the semiconductor chip 5 and the substrate 8, so that it picks up less noise in the vibration signal waveform, enabling monitoring data to be acquired with high sensitivity.

[0046] The calculation unit 15 determines whether the bonding state between the semiconductor chip 5 and the substrate 8 is good or bad based on the signal waveform acquired by the sensor 30 .

[0047] As shown in FIG. 3, a state in which the bumps 6 within the surface of the semiconductor chip 5 are uniformly bonded to the electrode pads 9 of the substrate 8 is determined to be a good bond.

[0048] Here, the uniformity of the bumps 6 means that when a shear test (JIS C 60068-2-21) is carried out, each bump 6 is bonded with a bonding strength equal to or greater than the standard.

[0049] During ultrasonic bonding, the tool 22 alternately performs a first operation of moving toward one end side of the vibration direction (the right side in FIG. 1 ) and a second operation of moving toward the other end side of the vibration direction (the left side in FIG. 1 ).

[0050] 4, if the semiconductor chip 5 is tilted diagonally downward to the left during ultrasonic bonding, the load and ultrasonic energy applied to the bumps 6 will be uneven across the chip surface, causing variations in bonding strength across the surface of the semiconductor chip 5 and resulting in bonding defects. In the example shown in Fig. 4, the pressing force on the left side of the surface of the semiconductor chip 5 is strong and the bonding strength on the right side is insufficient, resulting in bonding defects on the right side of the surface of the semiconductor chip 5.

[0051] As shown in Figure 5, if the semiconductor chip 5 is tilted diagonally downward to the right during ultrasonic bonding, the pressing force on the right side of the surface of the semiconductor chip 5 becomes stronger, and the bonding strength on the left side becomes insufficient, resulting in poor bonding on the left side of the surface of the semiconductor chip 5.

[0052] 6 is a graph showing a signal waveform acquired by the sensor 30. The sensor 30 monitors and acquires a signal waveform indicating frictional vibrations occurring between the semiconductor chip 5 and the tool 22 during ultrasonic bonding.

[0053] Here, frictional vibration refers to friction that occurs due to sliding between the tool 22, which is holding the semiconductor chip 5 by suction, and the semiconductor chip 5 as the bonding between the bumps 6 of the semiconductor chip 5 and the electrode pads 9 of the substrate 8 is completed after ultrasonic energy is applied to the tool 22 by the vibrator 25.

[0054] Before ultrasonic bonding, the vibration wave (ultrasonic energy) emitted from the vibrator 25 is observed as signal waveform data acquired by the sensor 30 .

[0055] As the ultrasonic bonding nears completion, the friction vibration wave described above is added, causing the sine wave of the transmitted vibration wave to change into a sawtooth wave-like shape.

[0056] 7 and 8, the amplitude of the signal waveform data acquired by the sensor 30 is divided into peak components and valley components for waveform processing. The divided waveform data of the peak components and valley components are each processed to form a single waveform.

[0057] 7 shows an output waveform obtained by performing Fourier analysis on a signal waveform containing only peak components, and FIG. 8 shows an output waveform obtained by performing Fourier analysis on a signal waveform containing only valley components.

[0058] Here, the reference value of the output voltage of the sensor 30 obtained from a non-defective joint that is uniformly joined within the surface of the semiconductor chip 5 is set to H11.

[0059] The calculation unit 15 acquires the frequency characteristics of the peak and valley components of the signal waveform, and determines that the bonding state between the semiconductor chip 5 and the substrate 8 is good if the amplitude of the signal waveform is greater than a predetermined reference value.

[0060] Specifically, if the sensor 30 acquires a signal amplitude H12 higher than the reference value H11 during ultrasonic bonding, it is estimated that a large amount of frictional vibration is generated when the bump 6 and the electrode pad 9 are ultrasonically bonded by metal diffusion, and it is determined that the bonding is good.

[0061] On the other hand, if the sensor 30 acquires a signal amplitude H13 that is lower than the reference value H11, it is estimated that the bump 6 and the electrode pad 9 have not been ultrasonically bonded due to metal diffusion, and there is little frictional vibration, and it is determined that the bond is poor.

[0062] Here, a first operation in which the tool 22 moves toward one end of the vibration direction (the right side in FIG. 1 ) is synchronized with one of the peak and valley components of the signal waveform, and a second operation in which the tool 22 moves toward the other end of the vibration direction (the left side in FIG. 1 ) is synchronized with the other of the peak and valley components of the signal waveform.

[0063] The calculation unit 15 determines whether the tool 22 is performing the first operation or the second operation based on a change in the waveform data of the current value of the transducer 25. In this embodiment, the first operation is synchronized with the peak component of the signal waveform, and the second operation is synchronized with the valley component of the signal waveform.

[0064] In this way, by synchronizing the increase and decrease in the current value of the vibrator 25 with the peak and valley components of the sensor 30, the waveform of the peak component is identified as the waveform when the tool 22 is moved to the right by the vibrator 25. Also, the waveform of the valley component is identified as the waveform when the tool 22 is moved to the left by the vibrator 25.

[0065] 7 and 8, when the tool 22 moves to the right, the bonding is good, but when the tool 22 moves to the left, the bonding is poor. Therefore, it is determined that the left side of the plane of the semiconductor chip 5 is poorly bonded.

[0066] It is also possible to synchronize the actual left-right swing direction of the ultrasonic head 20 with the peak and valley components of the monitoring data of the sensor 30 using laser Doppler measurement or the like.

[0067] Furthermore, in order to synchronize the left and right vibration direction of the ultrasonic head 20 with the peak and valley components of the signal waveform data acquired by the sensor 30, multiple sensors 30 may be arranged, and the location of the poor bonding may be predicted based on the time difference between the acquired waveform data.

[0068] <Determining Bond Quality> As shown in FIG. 9, in step S11, application of ultrasonic waves by the vibrator 25 is started, and the process proceeds to step S12.

[0069] In step S12, a change in the current value of the vibrator 25 is acquired, and signal waveform data associated with frictional vibration is acquired by the sensor 30, and the process proceeds to step S13.

[0070] In this embodiment, the timing for detecting the change in the current value of the vibrator 25 and acquiring the signal waveform data by the sensor 30 is set to 200 ms immediately after the start of application of ultrasonic waves. The acquisition timing may be appropriately set depending on the chip area, material, number of bumps, bump diameter, bump height, pin arrangement, etc. of the members to be joined.

[0071] In step S13, the left-right vibration of the tool 22 is synchronized with the peak and valley components of the waveform data of the sensor 30 based on the data indicating the change in the current value of the vibrator 25, and the process proceeds to step S14. In this embodiment, the peak component is synchronized with the direction in which the tool 22 moves to the right in the vibration direction, and the valley component is synchronized with the direction in which the tool 22 moves to the left in the vibration direction.

[0072] In step S14, waveform processing is performed to divide the signal waveform data into peak components and valley components. Furthermore, Fourier analysis is performed on the processed waveform data to check for harmonic components higher than the ultrasonic applied frequency. Note that, due to the nature of sawtooth waves, peaks appear near multiples of the applied frequency, so in this case, frequencies near 120 kHz and 180 kHz are checked.

[0073] If a value higher than the reference value H11 is obtained, it is determined that the bonding state is normal in the region of this component. If a value lower than the reference value H11 is obtained, it is determined that the bonding state is abnormal in the region of this component.

[0074] If no abnormality is detected in the waveform processed data (a) of the peak component and the waveform processed data (b) of the valley component, it is determined in step S15 that the joint is a good product.

[0075] If an abnormality is detected in the waveform processed data (a) of the peak component but not in the waveform processed data (b) of the valley component, it is determined in step S16 that a poor connection has occurred in the right region of the inner surface of the chip.

[0076] If no abnormality is detected in the waveform processed data (a) of the peak component, but an abnormality is detected in the waveform processed data (b) of the valley component, in step S17, it is determined that a poor connection has occurred in the left region of the inner surface of the chip.

[0077] If an abnormality is detected in the waveform processed data (a) of the peak component and the waveform processed data (b) of the valley component, it is determined in step S18 that the entire inner surface of the chip has a poor connection.

[0078] -Effects of embodiment 1- As described above, according to the bonding quality determination system 1 of this embodiment, the quality of the bonding state between the semiconductor chip 5 and the substrate 8 can be determined by monitoring and analyzing the signal waveform of the vibrations that occur between the tool 22 and the semiconductor chip 5 during ultrasonic bonding, specifically, the frictional vibrations that occur due to sliding between the tool 22 and the semiconductor chip 5.

[0079] Furthermore, if the amplitude of the signal waveform is greater than a predetermined reference value, it can be assumed that the semiconductor chip 5 and the substrate 8 have been ultrasonically bonded normally by metal diffusion, and that a large amount of frictional vibration is occurring between the tool 22 and the semiconductor chip 5. This allows the bonding state to be determined to be good.

[0080] Furthermore, by dividing the signal waveform acquired by the sensor 30 into peak components and valley components and analyzing them, it is possible to determine whether the bonding state between the semiconductor chip 5 and the substrate 8 is good or bad.

[0081] In addition, by synchronizing the first operation of the tool 22 with one of the peak or valley components of the signal waveform, and synchronizing the second operation of the tool 22 with the other component, it is possible to determine whether a poor bond has occurred on one end or the other end of the vibration direction on the bonding surface of the semiconductor chip 5.

[0082] Second Embodiment Hereinafter, the same parts as those in the first embodiment will be denoted by the same reference numerals, and only the differences will be described.

[0083] 10 , a plurality of sensors 30 are provided. The sensors 30 include a first sensor 31 and a second sensor 32.

[0084] The first sensor 31 is provided on the ultrasonic head 20. The first sensor 31 is disposed behind the semiconductor chip 5 in a plan view.

[0085] The second sensor 32 is provided on the ultrasonic head 20. In plan view, the second sensor 32 is disposed in front of the semiconductor chip 5. The second sensor 32 is disposed so as to be symmetrical to the first sensor 31 with respect to a center line extending in the left-right direction, which is the vibration direction of the tool 22.

[0086] 11, if the semiconductor chip 5 is tilted downward and rearward during ultrasonic bonding, the load and ultrasonic energy applied to the bumps 6 will be uneven across the chip surface, causing variations in bonding strength across the surface of the semiconductor chip 5 and resulting in bonding defects. In the example shown in Fig. 11, the pressing force on the rear side within the surface of the semiconductor chip 5 becomes strong and the bonding strength on the front side is insufficient, resulting in bonding defects on the front side within the surface of the semiconductor chip 5.

[0087] As shown in Figure 12, if the semiconductor chip 5 assumes a position tilted diagonally downward toward the front during ultrasonic bonding, the pressing force on the front side of the surface of the semiconductor chip 5 becomes stronger, and the bonding strength on the rear side becomes insufficient, resulting in poor bonding on the rear side of the surface of the semiconductor chip 5.

[0088] 13 is a graph showing a signal waveform acquired by the sensor 30. The sensor 30 monitors and acquires a signal waveform indicating frictional vibrations occurring between the semiconductor chip 5 and the tool 22 during ultrasonic bonding.

[0089] Before ultrasonic bonding, the vibration wave (ultrasonic energy) emitted from the vibrator 25 is observed as signal waveform data acquired by the sensor 30 .

[0090] As the ultrasonic bonding nears completion, the friction vibration wave described above is added, causing the sine wave of the transmitted vibration wave to change into a sawtooth wave-like shape.

[0091] 14 and 15, the amplitude of the signal waveform data acquired by the sensor 30 is divided into peak components and valley components for waveform processing. The divided waveform data of the peak components and valley components are each processed to form a single waveform.

[0092] 14 shows an output waveform obtained by performing Fourier analysis on a signal waveform containing only peak components, and FIG. 15 shows an output waveform obtained by performing Fourier analysis on a signal waveform containing only valley components.

[0093] Here, the reference value of the output voltage of the sensor 30 obtained from a non-defective joint that is uniformly joined within the surface of the semiconductor chip 5 is set to H21.

[0094] If the sensor 30 acquires a signal amplitude H22 higher than the reference value H21 during ultrasonic bonding, it is assumed that the bump 6 and the electrode pad 9 are ultrasonically bonded by metal diffusion, causing a large amount of frictional vibration, and it is determined that the bonding is good.

[0095] On the other hand, if the sensor 30 acquires a signal amplitude H23 that is lower than the reference value H21, it is estimated that the bump 6 and the electrode pad 9 have not been ultrasonically bonded due to metal diffusion, and there is little frictional vibration, and it is determined that the bond is poor.

[0096] Here, a first operation in which the tool 22 moves toward one end of the vibration direction (the right side in FIG. 10) is synchronized with one of the peak and valley components of the signal waveform, and a second operation in which the tool 22 moves toward the other end of the vibration direction (the left side in FIG. 10) is synchronized with the other of the peak and valley components of the signal waveform.

[0097] The calculation unit 15 determines whether the tool 22 is performing the first operation or the second operation based on a change in the waveform data of the current value of the transducer 25. In this embodiment, the first operation is synchronized with the peak component of the signal waveform, and the second operation is synchronized with the valley component of the signal waveform.

[0098] In this way, by synchronizing the increase and decrease in the current value of the vibrator 25 with the peak and valley components of the sensor 30, the waveform of the peak component is identified as the waveform when the tool 22 is moved to the right by the vibrator 25. Also, the waveform of the valley component is identified as the waveform when the tool 22 is moved to the left by the vibrator 25.

[0099] <Determining Bond Quality> As shown in FIG. 16, in step S21, application of ultrasonic waves by the vibrator 25 is started, and the process proceeds to step S22.

[0100] In step S22, the change in the current value of the vibrator 25 is acquired, and signal waveform data associated with frictional vibration is acquired by the rear first sensor 31 and the front second sensor 32, and the process proceeds to step S23.

[0101] In step S23, the left-right vibration of the tool 22 is synchronized with the peak and valley components of the waveform data of the sensor 30 based on the data indicating the change in the current value of the vibrator 25, and the process proceeds to step S24. In this embodiment, the peak component is synchronized with the direction in which the tool 22 moves to the right in the vibration direction, and the valley component is synchronized with the direction in which the tool 22 moves to the left in the vibration direction.

[0102] In step S24, waveform processing is performed to divide the signal waveform data of the first sensor 31 into peak components and valley components. Furthermore, Fourier analysis is performed on the processed waveform data to confirm harmonic components higher than the ultrasonic application frequency, and the process proceeds to step S25.

[0103] In step S25, waveform processing is performed to divide the signal waveform data of the second sensor 32 into peak components and valley components. Furthermore, Fourier analysis is performed on the processed waveform data to check for harmonic components higher than the applied ultrasonic frequency.

[0104] If a value higher than the reference value H21 is obtained, it is determined that the bonding state is normal in the region of this component. If a value lower than the reference value H21 is obtained, it is determined that the bonding state is abnormal in the region of this component.

[0105] If no abnormality is detected in the waveform processed data (a-1) of the peak component and the waveform processed data (b-1) of the valley component of the first sensor 31, and the waveform processed data (a-2) of the peak component and the waveform processed data (b-2) of the valley component of the second sensor 32, it is determined in step S26 that the joint is of good quality.

[0106] If an abnormality is detected in the waveform processing data (a-1) of the peak component of the first sensor 31, and no abnormality is detected in the waveform processing data (b-1) of the valley component of the first sensor 31, or the waveform processing data (a-2) of the peak component and the waveform processing data (b-2) of the valley component of the second sensor 32, then in step S27 it is determined that a poor connection has occurred in the rear right region within the chip surface.

[0107] If an abnormality is detected in the waveform processing data (b-1) of the valley component of the first sensor 31, and no abnormality is detected in the waveform processing data (a-1) of the peak component of the first sensor 31, or the waveform processing data (a-2) of the peak component and the waveform processing data (b-2) of the valley component of the second sensor 32, then in step S28 it is determined that a poor connection has occurred in the rear left region within the chip surface.

[0108] If an abnormality is detected in the waveform processing data (a-2) of the peak component of the second sensor 32, and no abnormality is detected in the waveform processing data (a-1) of the peak component and the waveform processing data (b-1) of the valley component of the first sensor 31, and the waveform processing data (b-2) of the valley component of the second sensor 32, then in step S29 it is determined that a poor connection has occurred in the front right region within the chip surface.

[0109] If an abnormality is detected in the waveform processing data (b-2) of the valley component of the second sensor 32, and no abnormality is detected in the waveform processing data (a-1) of the peak component and the waveform processing data (b-1) of the valley component of the first sensor 31, and the waveform processing data (a-2) of the peak component of the second sensor 32, then in step S30 it is determined that a poor connection has occurred in the region on the front left side of the chip surface.

[0110] If an abnormality is detected in the waveform processed data (a-1) of the peak component and the waveform processed data (b-1) of the valley component of the first sensor 31, and in the waveform processed data (a-2) of the peak component and the waveform processed data (b-2) of the valley component of the second sensor 32, in step S31, it is determined that the entire inner surface of the chip has a poor bond.

[0111] This makes it possible to determine the location of any bonding defects occurring within the surface of the semiconductor chip 5. In this embodiment, the data from the first sensor 31 is analyzed first, and then the data from the second sensor 32 is analyzed, but the order of the analyses may be reversed, or the analyses may be performed simultaneously.

[0112] Furthermore, the peak components of the first sensor 31 and the second sensor 32 may be analyzed first, and then the valley components of the first sensor 31 and the second sensor 32 may be analyzed, or vice versa.

[0113] -Effects of embodiment 2- As described above, according to the bonding quality determination system 1 of this embodiment, by using multiple sensors 30 to monitor and analyze multiple signal waveforms, it is possible to improve the accuracy of determining whether the bonding condition between the semiconductor chip 5 and the substrate 8 is good or bad.

[0114] Other Embodiments The above-described embodiment may be configured as follows.

[0115] In the second embodiment, the first sensor 31 and the second sensor 32 are provided on the ultrasonic head 20, but the present invention is not limited to this. For example, as shown in Fig. 17, the first sensor 31 and the second sensor 32 may be provided on the stage 11.

[0116] In this case, the sensors 30 are installed diagonally in the forward and backward directions relative to the direction of application of ultrasonic vibrations from the vibrator. One or more sensors 30 are installed in each direction. The closer the sensors 30 are to the semiconductor chip 5 to be bonded, the more preferable the location.

[0117] As described above, the present invention has the highly practical effect of being able to determine whether the joining state between the first member and the second member is good or bad, and is therefore extremely useful and has high industrial applicability.

[0118] REFERENCE SIGNS LIST 1 Bond quality determination system 5 Semiconductor chip (first member) 8 Substrate (second member) 15 Calculation unit 22 Tool 25 Oscillator 30 Sensor 31 First sensor 32 Second sensor

Claims

1. A bonding quality determination system that ultrasonically bonds a first member and a second member and determines the quality of the bond, comprising: a tool that holds the first member; a vibrator that applies ultrasonic energy to the tool; a sensor that acquires a signal waveform of vibrations generated between the tool and the first member during ultrasonic bonding; and a calculation unit that determines the quality of the bond between the first member and the second member based on the signal waveform.

2. A system for determining the quality of a joint according to claim 1, wherein the calculation unit determines that the joint between the first member and the second member is good when the amplitude of the signal waveform is greater than a predetermined reference value.

3. A joint quality determination system according to claim 2, wherein the calculation unit acquires frequency characteristics of peak and valley components of the signal waveform.

4. A bonding quality determination system according to claim 3, wherein the tool alternately performs a first action of moving towards one end in the vibration direction and a second action of moving towards the other end in the vibration direction during ultrasonic bonding, and the calculation unit determines whether the tool is performing the first action or the second action based on changes in the current value of the vibrator, and synchronizes the first action with one of the peak and valley components of the signal waveform, and synchronizes the second action with the other component.

5. A welding quality determination system according to any one of claims 1 to 4, wherein a plurality of sensors are provided, and the plurality of sensors are arranged at positions that are line-symmetrical with respect to a center line that extends in the vibration direction of the tool.

6. A method for determining the quality of a bond that ultrasonically bonds a first member to a second member and determines the quality of the bond, comprising the steps of: sucking and holding the first member with a tool, and ultrasonically bonding the first member to the second member; acquiring a signal waveform of vibrations generated between the tool and the first member during ultrasonic bonding; and determining the quality of the bond between the first member and the second member based on the signal waveform.

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