Wire bonding method and wire bonding apparatus

Abstract

To improve an accuracy of a bonding position.SOLUTION: After acquisition of an image of a first lead 41, a first pad 51, a second pad 52, and a second lead 42 while moving a bonding head from an imaging position to a first direction, the bonding head is moved in a second direction that is opposite to the first direction, the bonding head is returned to an imaging position, and the image of the first lead 41 is acquired again. On the basis of the acquired image, a position deviation amount of an actual bonding position of a semiconductor chip 50 against the bonding position 48 of a substrate 40 is calculated. On the basis of the image that is acquired again, the position deviation amount is corrected, and a corrected position deviation amount is calculated. On the basis of the corrected position deviation amount, a position of a plurality of pads 55 is corrected. A wire is bonded to the corrected position of the plurality of pads 55.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a wire bonding apparatus and a wire bonding method for connecting a lead of a substrate and a pad of a semiconductor chip with a wire.

Background Art

[0002] The position of a semiconductor chip bonded to a substrate often deviates from an accurate position, and correction of this deviation amount may be required. Therefore, prior to bonding, a correction value for the bonding position is obtained based on the coordinates of pads and leads stored in advance, position detection points, and coordinates and position detection points on the lead side, and the offset amount of the camera is added to the corrected bonding position for bonding (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, an XY table that drives a bonding head to which a bonding tool and an imaging device are attached in the XY direction may have hysteresis depending on the moving direction. In this case, when the bonding head is reciprocated along a predetermined path, a slight positional deviation may occur when returning to the imaging position. Then, the positional accuracy of bonding may be reduced due to this positional deviation.

[0005] On the other hand, in recent years, the pad size has become smaller, and the gap between the outer periphery of the bonding ball and the pad periphery has become very small, and higher bonding position accuracy is required.

[0006] Therefore, the present invention aims to improve the accuracy of bonding positions. [Means for solving the problem]

[0007] The wire bonding method of the present invention is a wire bonding method that uses a bonding apparatus comprising a bonding head to which a bonding tool and an imaging device are attached, and an XY table for moving the bonding head in the XY direction, to connect a plurality of leads of a substrate and a plurality of pads of a semiconductor chip bonded on the substrate with wires, wherein the semiconductor chip comprises a first pad located on one side and a second pad located on the other side, and the substrate comprises a first lead connected to the first pad by a wire and a second lead connected to the second pad by a wire, an image acquisition step of moving the bonding head to an imaging position and acquiring an image of the first lead with the imaging device, and then sequentially acquiring an image of the first pad, an image of the second pad and an image of the second lead while moving the bonding head in a first direction, and the position of the first lead and the position of the first pad based on each image acquired in the image acquisition step The method is characterized by including: a position detection step for detecting the position of a second pad and the position of a second lead; a position misalignment calculation step for calculating the amount of position misalignment of the actual bonding position of the semiconductor chip relative to the bonding position of the substrate based on the positions detected in the position detection step; an image reacquisition step for acquiring an image of the second lead, then moving the bonding head in a second direction opposite to the first direction to return to the imaging position, and acquiring an image of the first lead again; a corrected position misalignment calculation step for re-detecting the position of the first lead based on the image reacquisition step, correcting the position misalignment amount based on the detected position difference between the previously detected position of the first lead and the re-detected position of the first lead, and calculating a corrected position misalignment amount; a position correction step for correcting the positions of multiple pads based on the corrected position misalignment amount calculated in the corrected position misalignment calculation step; and a bonding step for bonding wires to the positions of the multiple pads corrected in the position correction step using a bonding tool.

[0008] In this way, the position of the pads is corrected based on the amount of misalignment between the actual bonding position of the semiconductor chip and the bonding position of the substrate, and the amount of misalignment caused by hysteresis in the XY table, thereby improving the bonding position accuracy.

[0009] In the wire bonding method of the present invention, the bonding step may involve moving the bonding head from the imaging position in a first direction to move the bonding tool onto one of the starting pads among the plurality of pads, and initiating the bonding of wires from the starting pad to each position of the plurality of pads.

[0010] In this way, since the bonding head is moved from the imaging position toward the first direction onto the start pad, positional shifts caused by hysteresis in the XY table are less likely to occur. This improves the accuracy of the bonding position.

[0011] The wire bonding method of the present invention is a wire bonding method that uses a bonding apparatus comprising a bonding head to which a bonding tool and an imaging device are attached, and an XY table for moving the bonding head in the XY direction, to connect a plurality of leads of a substrate and a plurality of pads of a semiconductor chip bonded on the substrate with wires, wherein the semiconductor chip comprises a first pad located on one side and a second pad located on the other side, and the substrate comprises a first lead connected to the first pad by a wire and a second lead connected to the second pad by a wire, and an image acquisition step of moving the bonding head to an imaging position and acquiring an image of the first lead with the imaging device, and then sequentially acquiring an image of the first pad, an image of the second pad and an image of the second lead while moving the bonding head in a first direction, and the position of the first lead and A wire bonding method comprising: a position detection step of detecting the position of a first pad, the position of a second pad, and the position of a second lead; a position misalignment amount calculation step of calculating the amount of position misalignment of the actual bonding position of the semiconductor chip relative to the bonding position of the substrate based on each position detected in the position detection step; a position correction step of correcting the positions of the multiple pads based on the position misalignment amount calculated in the position misalignment amount calculation step; and a bonding step of bonding wires to the corrected positions of the multiple pads with a bonding tool, wherein the bonding step is characterized in that, after acquiring an image of the second lead, the bonding head is moved in a second direction opposite to the first direction to return to the imaging position, and then the bonding head is moved again in the first direction to move the bonding tool onto one of the starting pads among the multiple pads, and the bonding of wires from the starting pad to each position of the multiple pads is started.

[0012] In this way, since the bonding head is moved from the imaging position toward the first direction onto the start pad, positional shifts caused by hysteresis in the XY table are less likely to occur. As a result, bonding position accuracy can be improved even without reacquiring the image of the first read and calculating the amount of corrected positional shift.

[0013] In the wire bonding method of the present invention, the starting pad may be a single pad located adjacent to the movement path of the bonding tool parallel to the first direction.

[0014] This reduces the travel distance from the imaging position to the starting pad, making positional shifts caused by hysteresis in the XY table less likely. As a result, bonding position accuracy can be improved.

[0015] In the wire bonding method of the present invention, the first pad is positioned at the first corner of the semiconductor chip, and the second pad is positioned at the second corner diagonally opposite the first corner. The first direction may be a direction that moves diagonally from the first corner toward the second corner.

[0016] This allows the amount of positional displacement of the semiconductor chip relative to the substrate in the X, Y, and θ directions to be detected by moving the bonding head from the first lead to the second lead.

[0017] The wire bonding apparatus of the present invention comprises a bonding head to which a bonding tool and an imaging device are attached, an XY table for moving the bonding head in the XY direction, an imaging device, a bonding tool, a bonding head, and a control unit for adjusting the operation of the XY table, and connects a plurality of leads of a substrate and a plurality of pads of a semiconductor chip bonded on the substrate with wires, the control unit includes a processor for performing information processing, the semiconductor chip comprises a first pad located on one side and a second pad located on the other side, the substrate comprises a first lead connected to the first pad by a wire and a second lead connected to the second pad by a wire, and the processor moves the bonding head to the imaging position, acquires an image of the first lead with the imaging device, and then moves the bonding head in the first direction The bonding head is moved in a second direction opposite to the first direction to return to the imaging position, and the image of the first lead is acquired sequentially. Based on the acquired images, the position of the first lead, the position of the first pad, the position of the second pad, and the position of the second lead are detected. Based on the detected positions, the amount of misalignment of the actual bonding position of the semiconductor chip relative to the bonding position of the substrate is calculated. After acquiring the image of the second lead, the bonding head is moved in a second direction opposite to the first direction to return to the imaging position, and the image of the first lead is acquired again. Based on the newly acquired image, the position of the first lead is re-detected. Based on the detected position difference between the previously detected position of the first lead and the newly detected position of the first lead, the amount of misalignment is corrected to calculate the corrected amount of misalignment. Based on the calculated corrected amount of misalignment, the positions of the multiple pads are corrected, and wires are bonded to the corrected positions of the multiple pads using a bonding tool.

[0018] In the wire bonding apparatus of the present invention, the processor may move the bonding head from the imaging position in a first direction to move the bonding tool onto one of the starting pads among the plurality of pads, and start bonding the wire from the starting pad to each position of the plurality of pads.

[0019] The wire bonding apparatus of the present invention comprises a bonding head to which a bonding tool and an imaging device are attached, an XY table for moving the bonding head in the XY direction, an imaging device, a bonding tool, a bonding head, and a control unit for adjusting the operation of the XY table, and connects a plurality of leads of a substrate and a plurality of pads of a semiconductor chip bonded on the substrate with wires, the control unit includes a processor for performing information processing, the semiconductor chip comprises a first pad located on one side and a second pad located on the other side, the substrate comprises a first lead connected to the first pad by a wire and a second lead connected to the second pad by a wire, and the processor moves the bonding head to an imaging position, acquires an image of the first lead with the imaging device, and then moves the bonding head in a first direction. The bonding process involves sequentially acquiring images of the first pad, the second pad, and the second lead, detecting the position of the first lead, the first pad, the second pad, and the second lead based on the acquired images, calculating the amount of misalignment of the actual bonding position of the semiconductor chip relative to the bonding position of the substrate based on the detected positions, correcting the positions of the multiple pads based on the calculated misalignment, bonding wires to the corrected positions of the multiple pads with a bonding tool, and, after acquiring the image of the second lead, moving the bonding head in a second direction opposite to the first direction to return to the imaging position, then moving the bonding head again in the first direction to move the bonding tool over one of the starting pads among the multiple pads, and starting the bonding of wires from the starting pad to each position of the multiple pads. [Effects of the Invention]

[0020] This invention can suppress the decrease in bonding position accuracy caused by hysteresis in the XY table and improve bonding position accuracy. [Brief explanation of the drawing]

[0021] [Figure 1]It is a system diagram showing the configuration of the wire bonding apparatus of the embodiment. [Figure 2] It is a perspective view showing the lens barrel of the camera shown in FIG. 1 and the bonding tool attached to the ultrasonic horn. [Figure 3] It is a plan view showing a substrate and a semiconductor chip bonded to the substrate. [Figure 4] It is a flowchart showing the operation of the wire bonding apparatus of the embodiment. [Figure 5] It is an explanatory diagram of the image acquisition step and the position detection step of the wire bonding apparatus of the embodiment. [Figure 6] It is an explanatory diagram of the correction position deviation amount calculation step of the wire bonding apparatus of the embodiment. [Figure 7] It is an explanatory diagram of the bonding operation of the wire bonding apparatus of the embodiment. [Figure 8] It is a flowchart showing other operations of the wire bonding apparatus of the embodiment. [Figure 9] It is an explanatory diagram of the step of moving the bonding tool to the start pad in other operations.

Mode for Carrying Out the Invention

[0022] The following describes the wire bonding apparatus 100 and wire bonding method of an embodiment with reference to the drawings. As shown in Figure 1, the wire bonding apparatus 100 includes an XY table 11, a bonding head 12, a bonding stage 13, a bonding arm 14, an ultrasonic horn 15, an ultrasonic transducer 16, a bonding tool called a capillary 17, a wire clamper 18, an imaging device called a camera 19, a spool 22, and a control unit 30. The wire bonding apparatus 100 connects multiple leads 45 (see Figure 4) of a substrate 40 adsorbed and fixed on the bonding stage 13 and multiple pads 55 (see Figure 4) of a semiconductor chip 50 bonded on the substrate 40 with wires 23. In the following description, the transport direction of the substrate 40 will be referred to as the X direction, the direction perpendicular to the X direction from the bonding stage 13 toward the bonding head 12 will be referred to as the Y direction, and the upward direction will be referred to as the Z direction.

[0023] The XY table 11 moves the bonding head 12 mounted on top of it to any position in the plane (XY plane) along the surface of the bonding stage 13. The bonding head 12 is fitted with a bonding arm 14 and a Z-direction motor 25. The base portion 14A of the bonding arm 14 is attached to the bonding head 12 so as to be rotatable around a rotation axis 28. The Z-direction motor 25 consists of a stator 25S mounted inside the bonding head 12 and a rotor 25D provided on the base portion 14A of the bonding arm 14. The rotor 25D is attached to the base portion 14A so as to be opposite to the stator 25S and rotates the base portion 14A around the rotation axis 28. An ultrasonic horn 15 is attached to the tip of the bonding arm 14. A capillary 17 is attached to the tip of the ultrasonic horn 15. As described above, the bonding arm 14 is attached to the bonding head 12, the ultrasonic horn 15 is attached to the bonding arm 14, and the capillary 17 is attached to the ultrasonic horn 15. Therefore, when the bonding head 12 moves in the XY direction by the XY table 11, the ultrasonic horn 15 and the capillary 17 move together with the bonding head 12 in the XY direction. In addition, the Z-direction motor 25 drives the tip of the ultrasonic horn 15 and the tip of the capillary 17 in the Z direction so that they move toward and away from the bonding stage 13.

[0024] An ultrasonic transducer 16 is attached to the base of the ultrasonic horn 15. The ultrasonic transducer 16 ultrasonically vibrates the capillary 17 attached to the tip of the ultrasonic horn 15. A wire clamper 18 is attached to the upper side of the bonding arm 14. The wire clamper 18 grips and releases the wire 23. A spool 22 for feeding out the wire 23 is attached to the upper end of the bonding head 12.

[0025] A camera 19 is mounted on the top of the bonding head 12. A lens barrel 19A, which houses optical components such as lenses, is positioned at the tip of the camera 19. As shown in Figure 2, the optical axis 19Z of the lens barrel 19A is mounted offset by SX in the X direction from the central axis 17Z in the Z direction of the capillary 17. In the wire bonding apparatus 100, the optical axis 19Z of the lens barrel 19A is not offset in the Y direction. Since the camera 19 is mounted on the bonding head 12 in this way, when the bonding head 12 moves in the XY direction by the XY table 11, the camera 19 moves with the bonding head 12 in the XY direction.

[0026] Returning to Figure 1, the control unit 30 detects the position of each part of the wire bonding apparatus 100 and controls its operation. The control unit 30 is a computer equipped with a CPU 31, which is a processor that performs information processing, and a memory 32 that stores operation programs and operation data. The XY table 11, the Z-direction motor 25, the ultrasonic transducer 16, and the wire clamper 18 are each connected to the control unit 30 and operate according to commands from the control unit 30. The camera 19 is also connected to the control unit 30 and operates according to commands from the control unit 30, and the image data captured by the camera 19 is input to the control unit 30.

[0027] The XY table 11 incorporates an XY position detection device that detects the XY position of the bonding head 12. The output of the XY position detection device is input to the control unit 30. The bonding head 12 is also equipped with a capillary height detector 24 that detects the Z-direction height of the tip of the capillary 17 by detecting the rotation angle around the rotation axis 28 of the bonding arm 14. The detection signal from the capillary height detector 24 is input to the control unit 30.

[0028] Next, the substrate 40 and semiconductor chip 50 will be described with reference to Figure 3. A bonding position 48 to which the semiconductor chip 50 is bonded is set in the center of the substrate 40. The center of the bonding position 48 is the bonding position center 48C. In addition, multiple leads 45 are formed radially around the bonding position 48. The semiconductor chip 50, on which multiple pads 55 are formed, is bonded to the bonding position 48 on the substrate 40. In the following description, the pad 55 formed on the upper right first corner 50A of the semiconductor chip 50 will be called the first pad 51. The pad 55 formed on the lower left second corner 50B, diagonally opposite the first corner 50A, will be called the second pad 52. The upper right lead 45 connected to the first pad 51 by wire 23 will be called the first lead 41, and the lower left lead 45 connected to the second pad 52 by wire 23 will be called the second lead 42. Note that when multiple leads 45 on the substrate 40 are not distinguished, they will be referred to as leads 45. Furthermore, when referring to multiple pads 55 of a semiconductor chip 50 without distinguishing between them, they are simply called pads 55.

[0029] As shown in Figure 3, the semiconductor chip 50 is bonded to the substrate 40 with its center 50C offset around the X, Y, and Z axes relative to the bonding position center 48C. The amount of offset in the X direction is ΔX, and the amount of offset in the Y direction is ΔY. The amount of angular offset around the Z axis is Δθ.

[0030] Next, the operations performed by the control unit 30 of the wire bonding apparatus 100 will be described with reference to Figures 4 to 7. Note that the operations of the control unit 30 described below are those performed by the CPU 31 of the control unit 30.

[0031] The control unit 30 of the wire bonding apparatus 100 performs an image acquisition process as shown in step S101 of Figure 4. The control unit 30 first moves the bonding head 12 to the imaging position. As shown in Figure 5, the imaging position is a position where the camera 19 can acquire an image of the upper right first lead 41. When the bonding head 12 is moved to the imaging position, the edge 41E and center 41C of the first lead 41 are included in the field of view 20 of the camera 19, which is indicated by a dashed rectangle in Figure 5. After moving the bonding head 12 to the imaging position, the control unit 30 acquires an image of the first lead 41 with the camera 19 and stores the acquired image data in the memory 32.

[0032] Next, the control unit 30 moves the bonding head 12 diagonally downward and to the left from the imaging position toward the second lead 42 to the lower left, as indicated by arrow 91 in Figure 5. The direction of arrow 91 is the first direction. Then, the control unit 30 moves the bonding head 12 to a position where the edge 51E and the center 51C of the first pad 51 are included within the field of view 20 of the camera 19. Then, the control unit 30 acquires an image of the first pad 51 with the camera 19 and stores the acquired image data in the memory 32.

[0033] Similarly, the control unit 30 moves the bonding head 12 to a position where the edge 52E and center 52C of the second pad 52 are included in the field of view 20 of the camera 19, acquires an image of the second pad 52 with the camera 19, and stores the acquired image data in the memory 32. Subsequently, the control unit 30 moves the bonding head 12 to a position where the edge 42E and center 42C of the second lead 42 are included in the field of view 20 of the camera 19, acquires an image of the second lead 42 with the camera 19, and stores the acquired image data in the memory 32.

[0034] In this manner, the control unit 30 moves the bonding head 12 in the first direction while sequentially acquiring images of the first lead 41, the first pad 51, the second pad 52, and the second lead 42. Once the image of the second lead 42 has been acquired, the control unit 30 terminates the image acquisition process.

[0035] The control unit 30 proceeds to step S102 in Figure 4 and executes the position detection process. First, the position detection of the center 41C of the first lead 41 will be described. The control unit 30 reads the image data of the first lead 41 stored in the memory 32 and detects the edge 41E of the first lead 41. For example, the control unit 30 detects the edge 41E of the lower right corner of the first lead 41, as shown by the thick line in Figure 5, by image binarization processing, etc. Once the edge 41E is detected, the position of the long side, short side and corner of the first lead 41 can be determined. Since the outer diameter of the first lead 41 is known, once the edge 41E is detected, the XY coordinates (41X, 41Y) of the center 41C of the first lead 41 can be calculated.

[0036] Similarly, the control unit 30 detects the edge 42E of the second lead 42 and calculates the XY coordinates (42X, 42Y) of the center 42C of the second lead 42.

[0037] Next, the control unit 30 reads the image data of the first pad 51 stored in the memory 32, detects the edge 51E of the first pad 51, and calculates the XY coordinates (51X, 51Y) of the center 51C of the first pad 51, similar to the case of the first read 41. Similarly, the control unit 30 reads the image data of the second pad 52 stored in the memory 32, detects the edge 52E of the second pad 52, and calculates the XY coordinates (52X, 52Y) of the center 52C of the second pad 52.

[0038] Thus, the control unit 30 calculates the position of the center 41C of the first lead 41, the position of the center 51C of the first pad 51, the position of the center 52C of the second pad 52, and the position of the center 42C of the second lead 42 based on each image acquired in the image acquisition step, and then terminates the position detection step.

[0039] The control unit 30 proceeds to step S103 in Figure 4 to perform the positional displacement calculation process. Based on the calculated XY coordinates (41X, 41Y) of the center 41C of the first lead 41 and the XY coordinates (42X, 42Y) of the center 42C of the second lead 42, the control unit 30 calculates the XY coordinates (48X, 48Y) of the bonding position center 48C of the substrate 40. Similarly, based on the XY coordinates (51X, 51Y) of the center 51C of the first pad 51 and the XY coordinates (52X, 52Y) of the center 52C of the second pad 52, the control unit 30 calculates the XY coordinates (50X, 50Y) of the center 50C of the semiconductor chip 50. Then, the control unit 30 calculates the XY positional displacement amounts ΔX and ΔY of the center 50C of the actual bonding position of the semiconductor chip 50 relative to the bonding position center 48C of the substrate 40, based on the calculated XY coordinates (48X, 48Y) of the bonding position center 48C and the XY coordinates (50X, 50Y) of the center 50C.

[0040] Furthermore, the control unit 30 identifies the diagonal 81 of the semiconductor chip 50 based on the XY coordinates (51X, 51Y) of the center 51C of the first pad 51 and the XY coordinates (52X, 52Y) of the center 52C of the second pad 52. Similarly, the control unit 30 identifies the diagonal 82 of the bonding position 48 based on the XY coordinates (41X, 41Y) of the center 41C of the first lead 41 and the XY coordinates (42X, 42Y) of the center 42C of the second lead 42. Then, it calculates the angle difference between the diagonal 81 and the diagonal 82 and defines this as the amount of angular displacement Δθ of the semiconductor chip 50 around the Z axis. Once the control unit 30 has calculated the positional displacement amounts ΔX, ΔY, and Δθ, it terminates the positional displacement amount calculation process.

[0041] As described above, by moving the bonding head 12 in the first direction from the first lead 41 to the second lead 42, the positional displacement amounts ΔX, ΔY, and Δθ of the semiconductor chip 50 relative to the substrate 40 in the X, Y, and θ directions can be detected.

[0042] The control unit 30 proceeds to step S104 in Figure 4 to execute the image reacquisition process. As shown in Figure 6, the control unit 30 moves the bonding head 12 in the upper right direction in a second direction opposite to the first direction, returning the bonding head 12 to the imaging position. Arrow 92 in Figure 6 indicates the second direction. When the bonding head 12 returns to the imaging position, the field of view 20A of the camera 19 should capture the same image of the first read 41 as the field of view 20 shown in Figure 5. However, as shown in Figure 6, the position of the field of view 20A when it returns to the imaging position is shifted by ΔXS and ΔYS from the position of the field of view 20 at the initial imaging position shown in Figure 5. This shift is due to hysteresis between the movement of the XY table 11 in the first direction and the movement in the second direction. Therefore, after returning the bonding head 12 to the imaging position, the control unit 30 reacquires the image of the first read 41 in the field of view 20A in Figure 6 and stores it in the memory 32.

[0043] After the control unit 30 reacquires an image of the first lead 41, it proceeds to step S105 in Figure 4 to perform the correction position shift amount calculation process. The control unit 30 reads the reacquired image from the memory 32, re-detects the position of the center 41C of the first lead 41, and calculates the detected position difference between the previously detected position of the center 41C of the first lead 41 and the re-detected position of the center 41C of the first lead 41. As shown in Figure 6, the re-detected position of the center 41C of the first lead 41 is shifted by the displacement amounts ΔXS and ΔYS of the field of view 20A. Therefore, the detected position differences in the XY directions of the re-detected center 41C of the first lead 41 are ΔXS and ΔYS, respectively.

[0044] Next, the control unit 30 adds or subtracts the detected position difference ΔXS and ΔYS to the previously calculated positional deviation amounts ΔX and ΔY of the center 50C of the actual bonding position of the semiconductor chip 50 relative to the bonding position center 48C of the substrate 40, and calculates the corrected positional deviation amounts ΔXA and ΔYA of the center 50C of the actual bonding position of the semiconductor chip 50 relative to the bonding position center 48C of the substrate 40, as ΔXA=(ΔX+ΔXS) and ΔYA=(ΔY+ΔYS), or ΔXA=(ΔX-ΔXS) and ΔYA=(ΔY-ΔYS). After calculating the corrected positional deviation amounts ΔXA and ΔYA, the control unit 30 terminates the corrected positional deviation amount calculation process.

[0045] The control unit 30 proceeds to step S106 in Figure 4 and performs the position correction process. Based on the corrected positional deviations ΔXA and ΔYA of the center 50C of the actual bonding position of the semiconductor chip 50 relative to the bonding position center 48C of the substrate 40, and the angular deviation Δθ of the semiconductor chip 50 around the Z axis, the control unit 30 corrects the position of each pad 55 as if the semiconductor chip 50 had been accurately bonded to the bonding position 48, and calculates the actual position of each pad 55. Once the actual position of each pad 55 has been calculated, the control unit 30 terminates the position correction process.

[0046] Once the position correction process is complete, the control unit 30 proceeds to step S107 in Figure 4 to execute the bonding process. As shown by arrow 93 in Figure 7, the control unit 30 moves the bonding head 12 on the XY table 11 so that the center of the capillary 17 is positioned at the center of the actual position of each pad 55. The control unit 30 then drives the capillary 17 vertically with the Z-direction motor 25 and vibrates the capillary 17 ultrasonically with the ultrasonic transducer 16 while bonding the wire 23 to each pad 55. After that, the control unit 30 moves the capillary 17 onto the corresponding lead 45 and bonds the wire 23 onto the lead 45. In this way, the control unit 30 drives the XY table 11 and the Z-direction motor 25 to sequentially connect each pad 55 and each lead 45 with the wire 23. Once each pad 55 and each lead 45 is connected with the wire 23, the control unit 30 terminates the bonding process.

[0047] As described above, the wire bonding apparatus 100 corrects the positions of multiple pads 55 based on the positional deviations ΔX, ΔY, and Δθ of the actual bonding position of the semiconductor chip 50 relative to the bonding position 48 of the substrate 40, and the detected positional differences ΔXS and ΔYS caused by hysteresis of the XY table 11, thereby improving the bonding position accuracy.

[0048] Furthermore, the operation of the control unit 30 of the wire bonding apparatus 100 described above also performs the bonding method.

[0049] In the above description, the control unit 30 was described as moving the bonding head 12 diagonally downward to the left as shown by arrow 91 in Figure 5, but it is not limited to this. For example, it may be moved diagonally downward to the right from the upper left to the lower right. In this case, the upper left lead 45 and pad 55 become the first lead 41 and the first pad 51, respectively, and the lower right pad 55 and lead 45 become the second pad 52 and the second lead 42.

[0050] Furthermore, the first pad 51 and the second pad 52 are not limited to being located at opposite corners of the semiconductor chip 50. The first pad 51 may be located on one side, for example, the upper side, and the second pad 52 on the other side, for example, the lower side, or they may be located on the right and left sides.

[0051] Furthermore, in the above description, the control unit 30 was described as executing each step in the order of image acquisition, position detection, position misalignment amount calculation, image reacquisition, corrected position misalignment amount calculation, position correction, and bonding. However, the image reacquisition step may be executed after the image acquisition step, and then the steps may be executed in the order of position detection, position misalignment amount calculation, corrected position misalignment amount calculation, position correction, and bonding.

[0052] Next, other operations of the wire bonding apparatus 100 will be described with reference to Figures 8 to 9. Processes similar to those described earlier with reference to Figures 4 to 7 are denoted by the same reference numerals and their explanations are omitted. The other operations involve returning the bonding head 12 to the imaging position, moving the bonding head 12 from the imaging position in a first direction, and then moving the capillary 17 onto the start pad 53 to perform bonding, without reacquiring the image of the first lead 41 or calculating the corrected positional displacement amounts ΔXA and ΔYA. These operations will be explained below.

[0053] As shown in step S201 of Figure 8, after the control unit 30 has performed the position misalignment amount calculation step, it performs the position correction step without performing the corrected position misalignment amount calculation step of step S105 of Figure 4. The position correction step shown in step S201 of Figure 8 performs position correction based on the position misalignment amounts ΔX, ΔY, and Δθ of the actual bonding position of the semiconductor chip 50 relative to the bonding position 48 of the substrate 40, without using the detected position differences ΔXS and ΔYS.

[0054] The control unit 30 calculates the actual position of each pad 55 by correcting the position of each pad 55 based on the positional displacement amounts ΔX, ΔY, and Δθ, assuming that the semiconductor chip 50 was accurately bonded to the bonding position 48. Once the control unit 30 has calculated the actual position of each pad 55, it terminates the position correction process.

[0055] The control unit 30 proceeds to step S202 in Figure 8, returning the bonding head 12 to the imaging position, as described with reference to Figure 6.

[0056] Next, as shown in Figure 9, the control unit 30 moves the bonding head 12 again in the first direction as indicated by arrow 91 in Figure 9. When the bonding head 12 is moved in the first direction in this way, the center of the capillary 17 moves in a direction parallel to the first direction, as indicated by arrow 94 in Figure 9. Arrow 94 indicates the movement path of the center of the capillary 17. Then, in step S203 in Figure 9, when the center of the capillary 17 approaches the actual position of one pad 55, the control unit 30 designates that pad 55 as the starting pad 53 and moves the center of the capillary 17 to the center of the starting pad 53. Then, in step S204 in Figure 9, the control unit 30 connects the starting pad 53 and the corresponding lead 45 with a wire 23, and then connects the other pads 55 and their corresponding leads 45s with wires 23.

[0057] The operation of the wire bonding apparatus 100 described above involves moving the bonding head 12 onto the start pad 53 in a first direction from the imaging position. Since the distance traveled from the imaging position to the start pad 53 is shortened, positional displacement caused by hysteresis in the XY table 11 is less likely to occur. As a result, bonding position accuracy can be improved even without reacquiring the image of the first read 41 and calculating the corrected positional displacement amounts ΔXA and ΔYA.

[0058] Although other operations have been described above, in the bonding process of the operation described earlier with reference to Figures 4 to 7, after performing the position correction process, the bonding head 12 may be moved from the imaging position toward the first direction, as shown in Figure 9, and the capillary 17 may be moved onto the start pad 53 to perform bonding, similar to the other operations.

[0059] This operation corrects the positions of multiple pads 55 based on the positional deviations ΔX, ΔY, and Δθ of the actual bonding position of the semiconductor chip 50 relative to the bonding position 48 of the substrate 40, and the detected positional differences ΔXS and ΔYS caused by hysteresis in the XY table 11. In addition, it makes positional deviations caused by hysteresis in the XY table 11 less likely to occur, thus further improving bonding position accuracy. [Explanation of Symbols]

[0060] 11 XY table, 12 bonding head, 13 bonding stage, 14 bonding arm, 14A root, 15 ultrasonic horn, 16 ultrasonic transducer, 17 capillary, 17Z central axis, 18 wire clamper, 19 camera, 19A lens barrel, 19Z optical axis, 20, 20A field of view, 22 spool, 23 wire, 24 capillary height detector, 25 Z direction motor, 25D rotor, 25S stator, 28 rotation axis, 30 control unit, 31 CPU, 32 memory, 40 substrate, 41 first lead, 41C, 42C, 50C, 51C, 52C center, 41E, 42E, 51E, 52E edge, 42 second lead, 45 lead, 48 bonding position, 48C bonding position center, 50 semiconductor chip, 51 First pad, 52; second pad, 53; starting pad, 55; pads, 81, 82; diagonal, 100; wire bonding apparatus.

Claims

1. A wire bonding method is provided for connecting multiple leads of a substrate and multiple pads of a semiconductor chip bonded to the substrate with wires, using a bonding apparatus comprising a bonding head to which a bonding tool and an imaging device are attached, and an XY table for moving the bonding head in the XY direction, The semiconductor chip comprises a first pad located on one side and a second pad located on the other side. The substrate comprises a first lead connected to the first pad by a wire, and a second lead connected to the second pad by a wire. The bonding head is moved to the imaging position, and an image of the first lead is acquired with the imaging device. Then, while moving the bonding head in a first direction, an image of the first pad, an image of the second pad, and an image of the second lead are acquired sequentially in this image acquisition step. A position detection step in which the position of the first lead, the position of the first pad, the position of the second pad, and the position of the second lead are detected based on each image acquired in the image acquisition step, A positional deviation amount calculation step calculates the amount of positional deviation of the actual bonding position of the semiconductor chip relative to the bonding position of the substrate based on each position detected in the position detection step, After acquiring an image of the second lead, the bonding head is moved in a second direction opposite to the first direction and returned to the imaging position, and an image of the first lead is acquired again in an image reacquisition step. A corrected positional misalignment calculation step is performed, in which the position of the first lead is re-detected based on the image re-acquired in the image re-acquisition step, and the positional misalignment amount is corrected based on the detected position difference between the previously detected position of the first lead and the re-detected position of the first lead, and the corrected positional misalignment amount is calculated. A position correction step in which the positions of the multiple pads are corrected based on the corrected position misalignment amount calculated in the corrected position misalignment amount calculation step, A wire bonding method comprising a bonding step of bonding a wire with a bonding tool to the positions of a plurality of pads corrected in the position correction step.

2. A wire bonding method according to claim 1, The bonding process involves moving the bonding head from the imaging position in the first direction to move the bonding tool onto one of the starting pads among the plurality of pads, and initiating the bonding of wires from the starting pad to each of the plurality of pads. A wire bonding method characterized by the following.

3. A wire bonding method is provided for connecting multiple leads of a substrate and multiple pads of a semiconductor chip bonded to the substrate with wires, using a bonding apparatus comprising a bonding head to which a bonding tool and an imaging device are attached, and an XY table for moving the bonding head in the XY direction, The semiconductor chip comprises a first pad located on one side and a second pad located on the other side. The substrate comprises a first lead connected to the first pad by a wire, and a second lead connected to the second pad by a wire. The bonding head is moved to the imaging position, and an image of the first lead is acquired with the imaging device. Then, while moving the bonding head in a first direction, an image of the first pad, an image of the second pad, and an image of the second lead are acquired sequentially in this image acquisition step. A position detection step in which the position of the first lead, the position of the first pad, the position of the second pad, and the position of the second lead are detected based on each image acquired in the image acquisition step, A positional deviation amount calculation step calculates the amount of positional deviation of the actual bonding position of the semiconductor chip relative to the bonding position of the substrate based on each position detected in the position detection step, A position correction step in which the positions of the multiple pads are corrected based on the position misalignment amount calculated in the position misalignment amount calculation step, A wire bonding method comprising a bonding step of bonding a wire with a bonding tool to the corrected positions of a plurality of pads, The bonding process involves, after acquiring an image of the second lead, moving the bonding head in a second direction opposite to the first direction to return it to the imaging position, then moving the bonding head again in the first direction to move the bonding tool onto one of the starting pads among the plurality of pads, and starting the bonding of wires from the starting pad to each position of the plurality of pads. A wire bonding method characterized by the following.

4. A wire bonding method according to claim 2 or 3, The starting pad is a single pad located adjacent to the movement path of the bonding tool parallel to the first direction. A wire bonding method characterized by the following.

5. A wire bonding method according to any one of claims 1 to 3, The first pad is positioned at the first corner of the semiconductor chip, and the second pad is positioned at the second corner diagonally opposite the first corner. The first direction is the direction that goes diagonally from the first corner toward the second corner. A wire bonding method characterized by the following.

6. A bonding head to which bonding tools and imaging devices are attached, An XY table for moving the bonding head in the XY direction, A wire bonding apparatus comprising the imaging device, the bonding tool, the bonding head, and a control unit for adjusting the operation of the XY table, wherein a plurality of leads on a substrate and a plurality of pads on a semiconductor chip bonded to the substrate are connected by wires, The control unit includes a processor that performs information processing. The semiconductor chip comprises a first pad located on one side and a second pad located on the other side. The substrate comprises a first lead connected to the first pad by a wire, and a second lead connected to the second pad by a wire. The aforementioned processor, The bonding head is moved to the imaging position, and an image of the first lead is acquired with the imaging device. Then, while moving the bonding head in the first direction, images of the first pad, the second pad, and the second lead are acquired sequentially. Based on each acquired image, the position of the first lead, the position of the first pad, the position of the second pad, and the position of the second lead are detected. Based on each detected position, the amount of positional deviation of the actual bonding position of the semiconductor chip relative to the bonding position of the substrate is calculated. After acquiring the image of the second lead, the bonding head is moved in the second direction opposite to the first direction and returned to the imaging position, and the image of the first lead is acquired again. Based on the newly acquired image, the position of the first lead is re-detected, and the positional displacement is corrected based on the difference in detected positions between the previously detected position of the first lead and the newly detected position of the first lead, and the corrected positional displacement is calculated. Based on the calculated amount of corrected positional deviation, the positions of the multiple pads are corrected. A wire bonding apparatus characterized by bonding a wire with the bonding tool to the corrected positions of a plurality of pads.

7. A wire bonding apparatus according to claim 6, The aforementioned processor, Moving the bonding head from the imaging position in the first direction to move the bonding tool onto one of the starting pads among the plurality of pads, and starting the bonding of wires from the starting pad to each position of the plurality of pads, A wire bonding apparatus characterized by the following features.

8. A bonding head to which bonding tools and imaging devices are attached, An XY table for moving the bonding head in the XY direction, A wire bonding apparatus comprising the imaging device, the bonding tool, the bonding head, and a control unit for adjusting the operation of the XY table, wherein a plurality of leads on a substrate and a plurality of pads on a semiconductor chip bonded to the substrate are connected by wires, The control unit includes a processor that performs information processing. The semiconductor chip comprises a first pad located on one side and a second pad located on the other side. The substrate comprises a first lead connected to the first pad by a wire, and a second lead connected to the second pad by a wire. The aforementioned processor, The bonding head is moved to the imaging position, and an image of the first lead is acquired with the imaging device. Then, while moving the bonding head in the first direction, images of the first pad, the second pad, and the second lead are acquired sequentially. Based on each acquired image, the position of the first lead, the position of the first pad, the position of the second pad, and the position of the second lead are detected. Based on each detected position, the amount of positional deviation of the actual bonding position of the semiconductor chip relative to the bonding position of the substrate is calculated. Based on the calculated positional displacement, the positions of the multiple pads are corrected. The wire is bonded to the corrected positions of the multiple pads using the bonding tool. The bonding involves, after acquiring an image of the second lead, moving the bonding head in a second direction opposite to the first direction to return it to the imaging position, and then moving the bonding head again in the first direction to move the bonding tool onto one of the starting pads among the plurality of pads, and starting the bonding of wires from the starting pad to each position of the plurality of pads. A wire bonding apparatus characterized by the following features.

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