Bonding device

Abstract

Provided is a wire bonding device (100) comprising: a frame (10); a bonding tool drive mechanism (20) that is attached to the frame (10) and that drives a capillary (31) in a Z direction relative to a wafer (45); an XY stage (40) that is attached to the frame (10), that holds the wafer (45), and that drives the wafer (45) in an XY direction; and a cutter (50) that is attached to the frame (10) and that cuts a wire (32) bonded to the wafer (45) at a predetermined XY position.

Description

Bonding apparatus

[0001] The present disclosure relates to the structure of a bonding apparatus.

[0002] Patent Document 1 discloses a bump electrode forming apparatus that forms bumps on the electrodes of semiconductor chips. The bump electrode forming apparatus disclosed in Patent Document 1 includes a transfer device that moves a wafer in the horizontal direction, a bonding head that drives a capillary in the Z direction, and a YX table that drives the bonding head in the XY direction. The bonding head and the XY table drive the capillary in the XYZ directions to form bumps on the electrodes of semiconductor chips in the wafer.

[0003] Further, Patent Document 2 discloses a bump forming method. The bump forming method disclosed in Patent Document 2 forms a ball at the tip of a wire, bonds the ball to the electrode of a semiconductor chip, then raises the capillary, and cuts the base of the ball with a cutter to form a bump.

[0004] Japanese Patent Application Laid-Open No. 7-122560, Japanese Patent Application Laid-Open No. 10-199888

[0005] By the way, in recent years, there has been a demand for forming bumps at high speed. In the bump electrode forming apparatus described in Patent Document 1, in order to form bumps at high speed, it is necessary to drive the capillary at high speed in the XYZ directions. For this purpose, it is necessary to satisfy the conflicting conditions of increasing the size of the Z-direction motor mounted on the bonding head and reducing the weight of the bonding head. Therefore, the bump electrode forming apparatus described in Patent Document 1 had room for improvement in order to form bumps at high speed.

[0006] Further, in the bump forming method described in Patent Document 2, it is necessary to mount a cutter on the bonding head. For this reason, the bonding head becomes large, and there was room for improvement in order to form bumps at high speed.

[0007] Further, in recent years, there has been a demand for forming pin wires at high speed on the electrodes of semiconductors.

[0008] Therefore, the object of this disclosure is to provide a wire bonding apparatus capable of forming pin wires or bumps at high speed.

[0009] The bonding apparatus of the present disclosure is a wire bonding apparatus for forming pin wires or bumps on a bonding target, and is characterized by comprising: a frame; a bonding tool driving mechanism attached to the frame that drives a bonding tool in the Z direction relative to the bonding target and connects wires at predetermined XY positions; an XY stage attached to the frame that holds the bonding target and drives the bonding target in the XY direction; and a cutter attached to the frame that cuts the wires bonded to the bonding target at the predetermined XY positions.

[0010] In this manner, the bonding tool drive mechanism, which drives the bonding tool in the Z direction, and the cutter are mounted on the frame so as not to move in the XY direction. Wire connection and cutting are performed at predetermined XY positions, and the bonding target is driven in the XY direction by the XY stage. Therefore, the Z-direction motor that drives the bonding tool in the Z direction and the cutter can be enlarged, allowing the bonding tool and cutter to be driven at high speed. This enables the formation of pin wires or bumps on the bonding target at high speed.

[0011] The bonding apparatus of the present disclosure comprises a bonding tool drive mechanism, an XY stage, and a control unit for adjusting the operation of the cutter, wherein the control unit aligns the XY position of the object to be bonded to a predetermined XY position using the XY stage, lowers the bonding tool using the bonding tool drive mechanism to bond the wire to the object to be bonded, raises the bonding tool using the bonding tool drive mechanism to feed out the wire from the tip of the bonding tool, and cuts the fed-out wire with the cutter to form the pin wire or the bump.

[0012] In this way, the XY stage aligns the XY position of the bonding target to a predetermined XY position, and the high-speed bonding tool drive mechanism and cutter form the pin wire or bump, allowing for high-speed formation of the pin wire or bump on the bonding target.

[0013] The bonding apparatus of this disclosure can form pin wires or bumps at high speed.

[0014] This is a diagram showing the configuration of the wire bonding apparatus of the embodiment. This is a flowchart showing the pin wire formation operation of the wire bonding apparatus of the embodiment. This is an explanatory diagram of the operation of the wire bonding apparatus of the embodiment, showing the operation of aligning the XY positions of the electrodes of the semiconductor chip with the XY positions of the capillary. This is an explanatory diagram of the operation of the wire bonding apparatus of the embodiment, showing the state in which the XY positions of the electrodes of the semiconductor chip are aligned with the XY positions of the capillary. This is an explanatory diagram of the operation of the wire bonding apparatus of the embodiment, showing the state in which the capillary is lowered and a free air ball is bonded to the electrodes of the semiconductor chip. This is an explanatory diagram of the operation of the wire bonding apparatus of the embodiment, showing the state in which the capillary is raised and the wire is fed out from the tip of the capillary. This is an explanatory diagram of the operation of the wire bonding apparatus of the embodiment, showing the operation of cutting the fed-out wire with a cutter. This is an explanatory diagram of the operation of the wire bonding apparatus of the embodiment, showing the state in which the capillary is raised after the wire is cut. This is a diagram showing the pin wire formed by the wire bonding apparatus of the embodiment.

[0015] The following description will explain a wire bonding apparatus 100, which is an embodiment of the bonding apparatus, with reference to the drawings. In the following description, as shown in Figure 1, the direction from the XY stage 40 toward the bonding tool drive mechanism 20 will be referred to as the Y direction, the direction perpendicular to the Y direction in the horizontal plane will be referred to as the X direction, and the vertical direction will be referred to as the Z direction.

[0016] As shown in Figure 1, the wire bonding apparatus 100 includes a frame 10, a bonding tool drive mechanism 20, an XY stage 40, a cutter 50, a torch 60, a position detection camera 70, and a control unit 80. The dashed line in Figure 1 indicates the signal flow.

[0017] Frame 10 includes a lower frame 12 and an upper frame 14. The lower frame 12 is fixed to the floor surface of the building. The upper frame 14 includes a plurality of columns 15, 16 erected on the lower frame 12, an upper rail 17 connecting the upper ends of the plurality of columns 15, 16, and a post 18 connected to the upper rail 17 and extending downward.

[0018] The bonding tool drive mechanism 20 includes a bonding arm 21, an ultrasonic transducer 23, an ultrasonic horn 24, a Z-direction motor 27, and a clamper 28.

[0019] The bonding arm 21 is mechanically connected to the lower frame 12 via a cross-shaped leaf spring 22. The cross-shaped leaf spring 22 is a spring that combines a horizontal leaf spring, which is approximately parallel to the horizontal direction, and a vertical leaf spring, which is approximately parallel to the vertical direction, so that they intersect in a cross shape. The upper end of the vertical leaf spring is connected to the bonding arm 21, and the lower end is connected to the lower frame 12. The front end of the horizontal leaf spring is connected to the bonding arm 21, and the rear end is connected to the lower frame 12. The bonding arm 21 is able to swing about a rotation axis 22A, which is a horizontal axis passing through the intersection of the vertical leaf spring and the vertical leaf spring. The cross-shaped leaf spring 22 also connects the bonding arm 21 to the lower frame 12 so that the bonding arm 21 does not move in the XY direction.

[0020] The ultrasonic horn 24 is attached near the tip of the bonding arm 21. The ultrasonic transducer 23 is attached to the base end of the ultrasonic horn 24. A bonding tool, a capillary 31, is attached to the tip of the ultrasonic horn 24. The ultrasonic horn 24 amplifies the ultrasonic vibrations of the ultrasonic transducer 23 to ultrasonically excite the capillary 31. A through hole extending in the Z direction is provided inside the capillary 31, and a wire 32 is inserted through this through hole. The wire 32 is fed out from a wire spool (not shown).

[0021] The clamper 28 is attached to the top of the bonding arm 21. The clamper 28 grips and releases the wire 32 inserted through the capillary 31.

[0022] The Z-direction motor 27 generates power to oscillate the bonding arm 21. The Z-direction motor 27 consists of a rotor 25 provided at the rear end of the bonding arm 21 and a stator 26 attached to the lower frame 12. By applying current to this Z-direction motor 27 and driving it, the bonding arm 21 oscillates around the rotation axis 22A of the cross-leaf spring 22. As the bonding arm 21 oscillates, the capillary 31 moves vertically to move toward and away from the wafer 45.

[0023] The XY stage 40 consists of an XY drive unit 41 and a stage 42. The XY drive unit 41 is attached to the lower frame 12 and drives the stage 42 mounted on top in the XY direction. The stage 42 adsorbs and holds the wafer 45 to be bonded on its upper surface. When the stage 42 is driven in the XY direction by the XY drive unit 41, the wafer 45 also moves in the XY direction. Therefore, the XY stage 40 is attached to the lower frame 12, holds the wafer 45, and drives the wafer 45 in the XY direction.

[0024] The cutter 50 is mounted on the post 18 of the upper frame 14 via a cutter Z-direction drive unit 53. The cutter 50 comprises a cutting blade 51 for cutting the wire 32 (see Figures 4A to 4C) and a cutting blade drive unit 52 for driving the cutting blade 51. The cutter Z-direction drive unit 53 moves the cutter 50 in the Z direction to adjust the Z-direction position of the cutting blade 51, but does not move the cutter 50 in the XY direction. Therefore, the cutter 50 is mounted on the post 18 of the upper frame 14 so as not to move in the XY direction.

[0025] The torch 60 is attached to the upper frame 14. The torch 60 discharges electricity between itself and the wire tail 34 (see Figure 4C) that is extended from the tip of the capillary 31, shaping the wire 32 into a free air ball 33.

[0026] The position detection camera 70 is mounted on the upper rail 17 and captures and outputs images of the semiconductor chip 46 and electrode 47 (see Figures 3 and 4) of the wafer 45.

[0027] The bonding arm 21 is equipped with a position sensor 29 that detects the Z-direction position of the capillary 31.

[0028] As described above, the wire bonding apparatus 100 is configured such that the bonding arm 21 is connected to the lower frame 12 by a cross-shaped spring 22 so as not to move in the XY direction, and the Z-direction motor 27 is configured to oscillate the bonding arm 21 around the rotation axis 22A of the cross-shaped spring 22, thereby moving the capillary 31 in the Z direction. As a result, the bonding arm 21 moves in the Z direction at a fixed, predetermined XY position to connect the wire 32 to the wafer 45. In addition, the cutter 50 is mounted on the post 18 of the upper frame 14 so as not to move in the XY direction, and cuts the wire 32 at a fixed, predetermined position.

[0029] The control unit 80 is a computer that includes a CPU 81, which is a processor that performs information processing, and a memory 82 that stores control programs and control data. The Z-direction motor 27, ultrasonic transducer 23, clamper 28, XY drive unit 41, cutting blade drive unit 52, cutter Z-direction drive unit 53, and torch 60 are connected to the control unit 80 via an interface circuit (not shown) and operate according to commands from the control unit 80. In addition, the position detection camera 70 and position sensor 29 are connected to the control unit 80 via an interface circuit (not shown), and captured images and detected data are input to the control unit 80.

[0030] Next, with reference to Figures 2 to 4D, the operation of forming the pin wire 35 (see Figure 4D) using the wire bonding apparatus 100 of the embodiment will be described.

[0031] As shown in step S101 of Figure 2, the CPU 81 of the control unit 80 discharges electricity between itself and the wire tail 34 (see Figure 4C) that is unfurled from the tip of the capillary 31 by the torch 60, thereby forming the wire tail 34 into a free air ball 33.

[0032] The CPU 81 of the control unit 80 proceeds to step S102 in Figure 2, operating the XY drive unit 41 to move the stage 42 in the XY direction, and moving the wafer 45 held on the stage 42 in the XY direction. Multiple semiconductor chips 46 are formed on the wafer 45, and multiple electrodes 47 are formed on the semiconductor chips 46. The CPU 81 acquires images of the semiconductor chips 46 and electrodes 47 from the position detection camera 70 and calculates the XY position of the electrodes 47. Then, as shown by arrow 91 in Figure 3A, the CPU 81 of the control unit 80 moves the wafer 45 held on the stage 42 in the XY direction by the XY drive unit 41, and aligns the XY position of the electrodes 47 with the XY position of the capillary 31 as shown in Figure 3B. The XY position of the capillary 31 is a known, predetermined XY position.

[0033] Next, the CPU 81 of the control unit 80 opens the clamp 28 as shown in Figure 3C, and as shown in step S103 in Figure 2 and arrow 92 in Figure 3C, the bonding tool drive mechanism 20 lowers the capillary 31 while detecting the Z-direction position of the capillary 31 with the position sensor 29. Then, the free air ball 33 is bonded to the electrode 47 of the semiconductor chip 46 (ball bonding). When the free air ball 33 is bonded to the electrode 47, it becomes a roughly hemispherical crimped ball 33A.

[0034] Next, the CPU 81 of the control unit 80, with the clamp 28 open as shown in Figure 4A, detects the Z-direction position of the capillary 31 using the position sensor 29 and raises the capillary 31 using the bonding tool drive mechanism 20, as shown in step S104 of Figure 2 and arrow 93 in Figure 4A. This causes the wire 32 to be fed out from the tip of the capillary 31, as shown in Figure 4A.

[0035] Next, as shown in step S105 of Figure 2, the CPU 81 of the control unit 80 adjusts the Z-direction position of the cutting blade 51 using the cutter Z-direction drive unit 53. Then, as shown in step S106 of Figure 2 and arrow 94 in Figure 4B, the CPU 81 of the control unit 80 operates the cutting blade drive unit 52 to cut the wire 32 at a predetermined Z-direction position at a predetermined XY position using the cutting blade 51, thereby forming the pin wire 35.

[0036] Next, the CPU 81 of the control unit 80 opens the cutting blade 51 and closes the clamper 28, as shown in step S107 of Figure 2 and Figure 4C, causing the bonding tool drive mechanism 20 to raise the capillary 31. This forms a pin wire 35 at a predetermined height that stands upright on the electrode 47.

[0037] The CPU 81 of the control unit 80 determines in step S108 of Figure 2 whether pin wires 35 have been formed on all predetermined electrodes 47. If it determines NO in step S108 of Figure 2, it returns to step S101 of Figure 2 and repeats steps S101 to S107 of Figure 2. On the other hand, if the CPU 81 of the control unit 80 determines YES in step S108 of Figure 2, it terminates the pin wire formation operation.

[0038] As described above, the wire bonding apparatus 100 has a bonding tool drive mechanism 20 that drives the capillary 31 in the Z direction, a cutter 50, and a cutter Z-direction drive unit 53 mounted on the frame 10 so that they do not move in the XY direction, and the wafer 45 containing the semiconductor chip 46 is driven in the XY direction by the XY stage 40. For this reason, the Z-direction motor 27, the cutting edge drive unit 52 of the cutter 50, and the cutter Z-direction drive unit 53 are made larger so that the capillary 31, cutter 50, and cutting edge 51 can be driven at high speed. As a result, pin wires 35 can be formed on the electrodes 47 of the semiconductor chip 46 at high speed.

[0039] Furthermore, since the capillary 31 does not move in the XY direction, the position detection camera 70 and torch 60 can be fixed to the frame 10. This allows for a simple configuration.

[0040] The above description explains the operation of forming the pin wire 35 using the wire bonding device 100. However, when forming a bump using the wire bonding device 100, in step S105 of Figure 2, the Z-direction position of the cutting blade 51 is adjusted by the cutter Z-direction drive unit 53 to a position just above the crimping ball 33A, and in step S106 of Figure 2, the wire 32 is cut by the cutting blade 51.

[0041] Furthermore, although the bonding arm 21 has been described as being connected to the lower frame 12 by a cross-leaf spring 22, it is not limited to this. For example, it may be connected to the upper frame 14 by the cross-leaf spring 22. In this case, the stator 26 may be attached to the upper frame 14 or to the lower frame 12. Alternatively, a rotation support member such as a ball bearing may be used instead of the cross-leaf spring 22.

[0042] 10 Frame, 12 Lower frame, 14 Upper frame, 15, 16 Column, 17 Upper rail, 18 Post, 20 Bonding tool drive mechanism, 21 Bonding arm, 22 Cross spring, 22A Rotating shaft, 23 Ultrasonic transducer, 24 Ultrasonic horn, 25 Rotor, 26 Stator, 27 Z-direction motor, 28 Clamper, 29 Position sensor, 31 Capillary, 32 Wire, 33 Free air ball, 33A Crimping ball, 34 Wire tail, 35 Pin wire, 40 XY stage, 41 XY drive unit, 42 Stage, 45 Wafer, 46 Semiconductor chip, 47 Electrode, 50 Cutter, 51 Cutting blade, 52 Cutting blade drive unit, 53 Cutter Z-direction drive unit, 60 Torch, 70 Position detection camera, 80 Control unit, 81 CPU, 82 Memory, 100 wire bonding equipment.

Claims

1. A bonding apparatus for forming pin wires or bumps on a bonding target, comprising: a frame; a bonding tool driving mechanism attached to the frame for driving a bonding tool in the Z direction relative to the bonding target and connecting wires at predetermined XY positions; an XY stage attached to the frame for holding the bonding target and driving the bonding target in the XY direction; and a cutter attached to the frame for cutting wires bonded to the bonding target at predetermined XY positions.

2. A bonding apparatus according to claim 1, comprising: a bonding tool drive mechanism; an XY stage; and a control unit for adjusting the operation of a cutter, wherein the control unit aligns the XY position of the object to be bonded to a predetermined XY position using the XY stage; lowers the bonding tool using the bonding tool drive mechanism to bond the wire to the object to be bonded; raises the bonding tool using the bonding tool drive mechanism to feed out the wire from the tip of the bonding tool; and cuts the fed-out wire with the cutter to form the pin wire or the bump.

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