TW201521127A - Wire bonding apparatus and wire bonding method - Google Patents

Abstract

A wire bonding apparatus 10 includes a capillary 28 for inserting a wire 30, a non-arrival decision circuit 36 and a controller 80. The non-arrival decision circuit 36 applies a predetermined AC electrical signal between the wire held in the capillary and a bonding object and obtains a capacitance value between the wire held in the capillary and the bonding object. When the capacitance value decreases after a first bonding process, the non-arrival decision circuit 36 decides that the wire is cut from the bonding object. Then, when the capacitance value recovers before arriving at a second bonding point, the non-arrival decision circuit 36 decides that the cut wire hangs and contacts the bonding object.

Description

Wire drawing device and wire bonding method

The present invention relates to an apparatus and method for wire bonding using a capillary.

The wire bonding device is used, for example, to connect a lead of a substrate to a pad of a semiconductor chip with a thin wire. The line is made as follows. That is, the metal wire is lowered toward the wire together with the wire tool. It initially drops at high speed and becomes low when it is close to the wire. This low speed drop is called the first search. Then, the metal wire is pressed against the wire by the tip end of the tool, and the ultrasonic vibration is applied while the two are joined to form a first bond. After the first bonding, the tool is pulled and the metal wire is extended to form an appropriate loop to move over the pad. Lower the tool when it reaches the top of the pad. It initially drops at a high speed and becomes low when it is close to the pad. The low speed drop is a second search. Then, the metal wire is pressed against the pad by the tip end of the tool, and the second bond is performed while the ultrasonic vibration is applied while the both are applied. After the second bonding, the wire clamper is used to stop the movement of the metal wire while pulling the tool to connect the metal wire to the second bonding. Cut off at the point. This operation is repeated to perform a connection between a plurality of wires of the substrate and a plurality of pads of the semiconductor wafer. Further, appropriate heating may be performed at the time of the first joining and the second joining. In addition, the first bonding of the bonding pads may be performed to perform the second bonding of the wires.

As described above, the first bonding and the second bonding are performed at the time of wire bonding, but the first bonding or the second bonding is not normally performed. Further, there is a case where the metal wire is peeled off from the wire in a stage in which the first arc is not sufficiently transferred to the second arc, and the metal wire is formed in the middle of the line arc even if the first bonding is normal. The situation that was cut off. These phenomena are collectively referred to as unjoined, and it is necessary to detect unjoined early. When the unbonding detection is performed, a voltage is applied between the substrate side and the metal wire side of the tool, or a current flows therebetween, and the resistance component, the diode component, and the capacitance component between the two are determined. Normal (for example, Patent Document 1 and Patent Document 2).

However, as a wire bonding method, a ball bonding method and a wedge bonding method are known.

The ball joint method uses a gold wire or the like which can form a free air ball (FAB) by a high voltage spark or the like, and uses a chamfer having a front end having a rotational symmetry about a longitudinal axis. The capillary of the part serves as a tool.

In the wedge bonding method, an aluminum wire or the like is used, and the FAB is not formed, and a wedge bonding tool having a wire guide and a pressing surface at the tip end is used as a bonding tool without using a capillary. At the time of the wedge-shaped joining, the metal wire is obliquely extended to the pressing surface side along the wire guide at the tip end of the tool, and the metal wire side surface is pressed against the bonding object by the pressing surface to be joined. Therefore, it becomes a form in which the metal wire protrudes laterally from the pressing surface at the front end of the tool, and the front end of the tool is not long around it. The axis of the direction is rotationally symmetrical (for example, Patent Document 3).

Since the tip end of the wedge-shaped joining tool is not rotationally symmetrical, the direction in which the wire guide is connected to the wire does not coincide with the arrangement of the pads and the wires. Therefore, the bonding head of the holding tool is set to a rotary type (for example, Patent Document 4), or the bonding stage holding the bonding object is rotated. Then, there has been proposed a method in which a capillary having a rotationally symmetrical shape at the distal end is used and the side surface of the metal wire is pressed by the distal end of the capillary to be joined (for example, Patent Document 5).

Prior technical literature

Patent literature

Patent Document 1: Japanese Patent No. 3335043

Patent Document 2: Japanese Patent Laid-Open Publication No. 2000-306940

Patent Document 3: Japanese Patent Laid-Open Publication No. SHO 58-9332

Patent Document 4: Japanese Patent Laid-Open No. 55-7415

Patent Document 5: US Patent Application Publication No. 2005/0167473

In the wedge bonding method, an aluminum wire having an elongation less than a gold wire is used. Therefore, there is a case where the metal wire which extends the metal wire toward the second joint is cut after the wire bonding of the first joint is normally performed. The unbonding or cutting of the metal wire can be judged based on the response of the electrical signal by imparting an electrical signal between the bonding object and the metal wire.

The judgment of the unjoining or cutting is for judging whether or not the joining is normally formed after the joining forming process is performed by imparting ultrasonic energy, and therefore it is usually performed at the first joint or the second joint. As described above, if the wire is cut between the first joint and the second joint, as long as the joining process of the second joint is advanced The line is unjoined and judged. However, when the capillary is lowered to perform the bonding process at the second bonding point, the metal wire protruding from the capillary is also lowered due to the cutting in the middle, and the object to be bonded is contacted, and the metal wire and the bonding object may be erroneously determined. The case of joining.

If the wire is not cut at the second joint in the case where the wire is not cut in the middle due to the erroneous determination, the defective product is caused.

An object of the present invention is to provide a wire bonding device and a wire bonding method capable of accurately determining whether or not a wire is cut between a first joint point and a second joint point.

A wire bonding apparatus according to the present invention includes: a first bonding processing unit that bonds a bonding object and a metal line at a first bonding point of the wire bonding; and a non-joining monitoring portion that is specified after the first bonding process During the continuous monitoring period, a predetermined electrical signal is continuously applied between the metal wire held by the capillary and the object to be bonded, and based on the continuous response of the electrical signal, it is monitored and determined whether or not the connection between the metal wire and the object to be joined is changed.

Further, in the wire bonding device of the present invention, it is preferable that the predetermined continuous monitoring period is a period in which the wire is extended from the first joint to the second joint of the wire after the first joining process.

Further, in the wire bonding device of the present invention, it is preferable that the unbonding monitoring unit applies a predetermined electrical signal between the metal wire held by the capillary and the object to be bonded, and obtains the metal wire and the bonding object held by the capillary. When the capacitance value decreases after the first bonding process, it is determined that the metal wire is cut from the bonding target, and when the capacitance value is restored before reaching the second bonding point, it is determined that the capacitance value is cut off. The metal wire hangs down to contact the object to be joined.

Further, in the wire bonding device of the present invention, it is preferable that the predetermined electrical signal is any one of an alternating current electrical signal and a direct current pulse signal.

Further, in the wire bonding device of the present invention, it is preferable that the unjoining monitoring unit determines the decrease and recovery of the capacitance value based on the differential value obtained by differentiating the obtained capacitance value with time.

Further, in the wire bonding device of the present invention, it is preferable that the wire bonding of the first bonding point and the second bonding point is performed by a wedge bonding method.

Further, the wire bonding method of the present invention is characterized by comprising: a first bonding processing step of bonding a bonding object and a metal line at a first bonding point of the bonding; a continuous monitoring step of causing a metal wire after the first bonding process A predetermined electric signal is continuously applied between the metal wire held by the capillary and the object to be bonded, and the wire and the wire held by the capillary are joined during the period from the first joint to the second joint of the wire. a change in the capacitance value between the objects; and a midway cutting determination step, when the capacitance value decreases after the first bonding process, it is determined that the metal wire is cut off halfway, and when the capacitance value is restored before reaching the second bonding point, It is determined that the metal wire cut by the middle is suspended and comes into contact with the object to be joined.

In addition, in the wire bonding method of the present invention, it is preferable that the predetermined electrical signal is any one of an AC electrical signal and a DC pulse signal.

The wire bonding device of the present invention includes: a first bonding processing portion that bonds the first bonding object and the metal wire at the first bonding point of the wire bonding; and a wire arc forming processing portion that extends the metal wire from the first bonding point Moving to a second joint to form a predetermined line arc; the second joint processing portion joining the second joint object and the metal wire at the second joint; and the unjoining monitoring portion from the first joint The predetermined electrical signal is continuously applied between the metal wire held by the capillary and the bonding platform holding the first bonding object and the second bonding object, in the entire period from the pre-treatment to the second bonding, based on the continuity of the electrical signal. In response, it monitors and judges whether the connection state of the metal wire changes.

Further, in the wire bonding device of the present invention, it is preferable that the unbonding monitoring portion monitors and determines whether or not the connection state of the metal wire is based on a change in the capacitance value between the metal wire and the bonding platform or a change in the electrical short circuit. Variety.

Further, in the wire bonding device of the present invention, it is preferable that the unjoining monitoring unit sets the stable value of the continuous response in the period before the first joining process to the first reference value, and determines the first joining based on the first reference value. Whether or not the connection state between the metal wire of the point and the first bonding object changes, the stable value of the continuous response when the first bonding process is completed is set to the second reference value, and the line arc forming process is judged based on the second reference value. Whether or not the connection state of the metal wire is changed, the stable value of the continuous response during the line arc forming process is set to a third reference value, and the wire between the second bonding point and the second bonding object is determined based on the third reference value. Whether or not the connection state is changed, the stable value of the continuous response when the second joining process is completed is set to the fourth reference value, and the period from the second joining point to the completion of the cutting process of the wire is determined based on the fourth reference value. There is no change in the connection state of the metal wires.

Further, in the wire bonding device of the present invention, it is preferable that the unbonding monitoring unit sets the potential of the bonding platform to a ground voltage value, and specifies a DC voltage signal having a voltage different from the ground voltage value by a predetermined voltage value. The electric signal is applied to the metal wire, and the first reference value is set to a predetermined voltage value, and the second reference value to the fourth reference value are set to the ground voltage value, and it is determined whether or not the connection state of the metal wire is changed.

In addition, in the wire bonding device of the present invention, the first bonding point is also preferably The wire bonding of the second joint is performed by a wedge bonding method or a ball bonding method.

The wire bonding method of the present invention includes: a first bonding process step of bonding a first bonding object and a metal line; and a wire arc forming processing step of extending a wire side from the first bonding point to the second bonding point Forming a predetermined line arc to move while moving; a second bonding process step of bonding the second bonding object to the metal line at the second bonding point; and an unjoining monitoring step from before the first bonding process to after the second bonding During the entire period, a predetermined electrical signal is continuously applied between the metal wire held by the capillary and the bonding platform holding the first bonding object and the second object, and the metal wire is monitored and judged based on the continuous response of the electrical signal. There is no change in the connection status.

According to at least one of the above configurations, it is possible to accurately determine whether or not the wire is cut between the first joint and the second joint.

According to at least one of the above configurations, it is possible to accurately determine the change in the connection state of the metal wires during the entire period from the first bonding process to the second bonding.

6‧‧‧Semiconductor wafer

8‧‧‧ circuit board

10‧‧‧Wireing device

12‧‧‧ pedestal

14‧‧‧Joining platform

16‧‧‧XY platform

18‧‧‧ Bonding head

20‧‧‧Z-direction motor

22‧‧‧Z-direction drive arm

24‧‧‧Ultrasonic Converter

26‧‧‧Ultrasonic vibrator

28‧‧‧ Capillary

30, 31‧‧‧ metal wire

32‧‧‧Clamps

33‧‧‧ spool

34‧‧‧Clamp opening and closing department

36‧‧‧Unjoined decision circuit

50‧‧‧window fixture

60‧‧‧ computer

62‧‧‧XY platform I/F

64‧‧‧Z-direction motor I/F

66‧‧‧Ultrasonic Vibrator I/F

68‧‧‧Clamp opening and closing I/F

70‧‧‧Unjoined decision circuit I/F

80‧‧‧Control Department

82‧‧‧ memory

84‧‧‧First joint program

86‧‧‧Line arc forming program

88‧‧‧Second joint program

90‧‧‧Unjoined continuous monitoring program

92‧‧‧cut judgment handler

94‧‧‧Exception output processing program

96‧‧‧Control program

98‧‧‧Control data

100‧‧‧ first joint

102‧‧‧second junction

104‧‧‧ cut off

105‧‧‧ front end

106‧‧‧Power supply

108‧‧‧Determination Department

C _M , C _L , C _P ‧‧‧ Capacitance

F1‧‧‧Unjoined wire of the first joint

F2‧‧‧cutting of the metal wire during the formation of the arc

F3‧‧‧ Unbonded metal wire at the second joint

F4‧‧‧After the second joining process and the cutting of the wire before the wire cutting process

C ₀ ~ C ₂ , T ₁ ~ T ₃ , t ₀ ~ t ₁₅ ‧ ‧ hours

J1‧‧‧ first reference value

J2‧‧‧ second reference value

J3‧‧‧ third reference value

J4‧‧‧ fourth reference value

S10~S22‧‧‧Steps

The voltage value V ₀ ‧‧‧

X ₁ ~X ₃ ‧‧‧Distance

X, Y, Z‧‧ Direction

Z ₁ ~Z ₃ ‧‧‧ Height

Fig. 1 is a configuration diagram of a wire bonding device according to an embodiment of the present invention.

2 is a view showing a non-joining determination circuit of the wire bonding device according to the embodiment of the present invention.

3 is a timing chart showing the operation of each member of the wire bonding device according to the embodiment of the present invention.

4 is a flow chart showing the sequence of a wire bonding method according to an embodiment of the present invention.

Fig. 5 is a view showing continuous monitoring of wire cutting between a first joint point and a second joint point in the wire bonding apparatus according to the embodiment of the present invention.

FIG. 6 is a view showing the first joining process of FIG. 4. FIG.

Fig. 7 is a view showing a state in which a metal wire is extended in a line arc forming process subsequent to Fig. 6;

Fig. 8 is a view showing a state in which the wire is cut after Fig. 7;

Fig. 9 is a view showing a state in which the capillary is lowered after Fig. 8 and the cut metal wire is in contact with the object to be joined.

FIG. 10 is a view showing the wire which is likely to be generated during the entire period from the first joint to the second joint in the wire bonding apparatus according to the embodiment of the present invention.

11(a) to 11(f) are diagrams showing the use of an alternating current electrical signal as a predetermined electrical signal in the wire bonding apparatus according to the embodiment of the present invention, in which the metal wire is unjoined, and the capillary and the joint are cut in the middle. A diagram of the change in capacitance between platforms.

12(a) to 12(f) are diagrams showing the use of a DC voltage signal as a predetermined electrical signal in the wire bonding apparatus according to the embodiment of the present invention, in which the metal wire is unjoined, and the capillary and the joint are cut in the middle. A graph of changes in voltage values between platforms.

Hereinafter, embodiments of the present invention will be described in detail using the drawings. Hereinafter, the object to be wired is described as a wire of the circuit board at the first joint and a pad of the semiconductor wafer at the second joint. However, this case is an example for explanation, and the A bonding point is set as a solder pad of the semiconductor wafer, and the second bonding is performed The point is set to the wire of the circuit substrate. The first bonding point and the second bonding point may both be used as pads of the semiconductor wafer, and the first bonding point and the second bonding point may also be used as the wires of the circuit substrate. The pad or the wire is an example of an object to which the wire is bonded, and may be other than the above. In addition to the semiconductor wafer, a general electronic component such as a resistor chip or a capacitor chip may be used as the substrate to be bonded, and a lead frame may be used as a circuit board in addition to the epoxy resin substrate or the like. Frame) and so on.

The dimensions, materials, and the like described below are exemplified for explanation, and can be appropriately changed according to the specifications of the wire bonding device.

In the following, in the drawings, the same reference numerals are given to the one or the corresponding component members, and the repeated description is omitted.

FIG. 1 is a configuration diagram of the wire bonding device 10. The wire bonding device 10 is a device that uses a capillary tube 28 as a wire bonding tool, uses an aluminum wire as the wire 30, and connects the two bonding objects by the wire bonding method by a wedge bonding method. In FIG. 1, the semiconductor wafer 6 and the circuit board 8 which are bonding objects are not shown as constituent members of the wire bonding device 10. Further, in the embodiment of the present invention, the wedge bonding method refers to a bonding method in which the FAB is not formed at the tip end of the metal wire and ultrasonic waves and pressure are used.

The wire bonding device 10 is configured to include a bonding platform 14 held by the pedestal 12, an XY stage 16, and a computer 60.

The bonding stage 14 is a bonding object holding stage on which the semiconductor wafer 6 and the circuit board 8 as two bonding objects are mounted. The bonding stage 14 is movable relative to the pedestal 12 when the circuit board 8 or the like is mounted or discharged, but is fixed to the pedestal 12 during the bonding process. As the joint platform 14, metal can be used Make a mobile table. The bonding platform 14 is connected to a reference potential such as a ground potential of the wire bonding device 10. The bonding platform 14 is connected to a ground-side terminal of the unjoined determination circuit 36 to be described later. In the case where it is necessary to insulate between the semiconductor wafer 6 or the circuit substrate 8, the necessary portion of the bonding stage 14 is insulated.

The semiconductor wafer 6 is formed by integrating a transistor or the like into an electronic circuit on a germanium substrate, and is input as an input terminal, an output terminal, or the like of the electronic circuit to the semiconductor wafer 6 as a plurality of pads (not shown). Upper surface. The lower surface of the semiconductor wafer 6 is the back surface of the germanium substrate, and is set as the ground electrode of the electronic circuit.

The circuit board 8 is formed by patterning a desired wiring on the epoxy substrate, and includes: a wafer pad (not shown) electrically and mechanically connecting and fixing the lower surface of the semiconductor wafer 6; and a plurality of wires (not The display terminal is disposed around the wafer pad; and the input terminal and the output terminal of the circuit substrate are drawn from the die pad or the plurality of wires. The wire bonding is performed by connecting the pads of the semiconductor wafer 6 and the wires of the circuit substrate 8 with the wires 30.

The window clamper 50 provided on the joining platform 14 is a flat member having an opening at the center portion, and is a member that holds the circuit board 8. The window clamp 50 is configured such that the lead wire of the circuit board 8 to be wired is placed in the opening of the center portion and the semiconductor wafer 6 is placed, and the circuit board 8 is pressed by the peripheral portion of the opening to fix the circuit board 8 Engaged in the platform 14.

The XY stage 16 is a moving stage on which the bonding head 18 is mounted and the bonding head 18 is moved to a desired position in the XY plane with respect to the pedestal 12 and the bonding stage 14. The XY plane is a plane parallel to the upper surface of the pedestal 12. The Y direction is a direction parallel to the longitudinal direction of the ultrasonic transducer 24 attached to a bonding arm (not shown) to be described later. Figure 1 shows the X direction, the Y direction, and The direction perpendicular to the XY plane is the Z direction.

The bonding head 18 is fixed and mounted on the XY stage 16, and has a Z-direction motor 20, and by the rotation control of the Z-direction motor, the capillary 28 is moved along the Z-direction driving arm 22 and the ultrasonic transducer 24. A moving mechanism that moves in the Z direction. As the z-direction motor 20, a linear motor can be used.

The Z-direction drive arm 22 is a member to which the ultrasonic transducer 24 and the clamp 32 are attached and which is rotatable about the rotation center of the joint head 18 by the rotation control of the Z-direction motor 20. The center of rotation of the joint head 18 is not necessarily the output shaft of the Z-direction motor 20, and the entire center of gravity position including the Z-direction drive arm 22, the ultrasonic transducer 24, and the clamp 32 can be considered, and the rotation is set to be reduced. The location of the load.

The ultrasonic transducer 24 is an elongated rod member in which a root portion is attached to the Z-direction driving arm 22, and a capillary tube 28 into which the metal wire 30 is inserted is attached to the distal end portion. The ultrasonic transducer 26 is mounted on the ultrasonic transducer 24, and the ultrasonic energy generated by driving the ultrasonic vibrator 26 is transmitted to the capillary 28. Therefore, the ultrasonic transducer 24 is formed in such a manner that the ultrasonic energy from the ultrasonic vibrator 26 can be efficiently transmitted to the capillary 28, and is formed into a horn shape that becomes thinner toward the distal end side. As the ultrasonic vibrator 26, a piezoelectric element is used.

The capillary tube 28 is a cone having a flat front end surface and a through hole having a through hole in the center portion into which the metal wire 30 can be inserted in the longitudinal direction. As the capillary tube 28, a ceramic capillary tube used in the spherical bonding can be used as it is. The capillary used in the spherical joint is provided with a suitable corner shape called chamfering on the distal end surface side of the through hole so that the FAB can be easily held, and in the wedge bonding method of the present embodiment, the spherical joint is used. The capillary has a flat surface called a face on the lower surface of the front end side of the through hole of the capillary. The working face The pressing surface is used for the wedge bonding in the wire bonding device 10.

The wedge bonding tool includes a wire guide that is disposed at an inclination of the front end portion with respect to the longitudinal direction, and a pressing surface for pressing the side surface of the wire. Therefore, the tool is not rotationally symmetrical about the longitudinal direction of the tool, but is The metal wire has a directivity in the direction of the wire guide and protrudes in the lateral direction. When such a wedge bonding tool is used, the direction of the wire guide and the direction in which the wires are connected may not coincide with each other due to the arrangement of the wires and the pads.

For example, the semiconductor wafer 6 is mounted on the central portion of the circuit board 8, and a plurality of pads are arranged around the peripheral portion of the semiconductor wafer 6, and the circuit board 8 is also wound around the outside of the semiconductor wafer 6. A plurality of wires are provided. In the above case, the connection direction of the wires connecting the wires to the pads varies according to each of the plurality of wires. In order to make the direction of the wire guide coincide with the direction in which the wires are connected, it is necessary to rotate the wedge bonding tool about the longitudinal axis or to rotate the circuit board 8.

On the other hand, since the working surface on the distal end surface side of the capillary tube 28 has a rotationally symmetrical shape about the longitudinal direction of the capillary tube 28, the connection direction of the metal wire connecting the bonding pad and the lead wire varies depending on each type of wire. It is also only necessary to perform a shaping process in which the direction of the metal wire 30 protruding from the tip end of the capillary 28 is slightly changed. Therefore, the capillary 28 is used for wedge engagement.

The metal wire 30 inserted into the capillary 28 is a thin wire of aluminum. The wire 30 is wound around a wire spool 33 provided at the front end of a wire holder extending from the bonding head 18, and is inserted from the bobbin 33 to the center portion of the capillary 28 via the wire clamp 32. The through hole protrudes from the front end of the capillary 28. As the material of the metal wire 30, in addition to the pure aluminum thin wire, it may be appropriately mixed. Fine lines such as bismuth and magnesium. The diameter of the wire 30 can be selected in accordance with the object to be joined. An example of the diameter of the metal wire 30 is 30 μm.

The clip 32 is mounted on the Z-direction drive arm 22, and the metal wire 30 is freely moved by opening a pair of splints disposed on opposite sides of the metal wire 30 by using a pair of splints disposed on opposite sides of the metal wire 30. A wire holding device that closes the opposing plates to stop the movement of the wire 30. Since the clip 32 is attached to the Z-direction drive arm 22, the metal wire 30 can be appropriately held even if the capillary 28 is moved in the XYZ direction. The opening and closing of the clip 32 is performed by the operation of the jig opening and closing portion 34 using the piezoelectric element.

The unjoining determination circuit 36 is a circuit that determines whether or not the connection between the bonding target and the metal wire 30 is appropriate at each stage of the wire bonding. The unjoining determination circuit 36 applies a predetermined electrical signal between the bonding object and the metal wire 30, and determines whether or not the connection between the bonding object and the metal wire 30 is appropriate based on the response of the electrical signal.

FIG. 2 is a configuration diagram of the unjoined determination circuit 36. Here, FIG. 2 is a view showing a case where it is confirmed that the first bonding point 100 has been properly wired, and then passes through the line arc forming processing step, and shifts to the second wire bonding processing step, and the second wire bonding process is confirmed. In the step, the second bonding point 102 is appropriately wired, and then the metal wire cutting process is appropriately performed, so that the metal wire 30 is turned off at the second bonding point 102. As described above, the case where the respective processing steps of the wire bonding are normally performed is shown.

The unjoined determination circuit 36 includes an application power source 106 and a measuring portion 108, and one of the terminals is connected to the bonding platform 14, and the other terminal is connected to the wire holder 32 or the bobbin 33. The power source 106 is applied as an AC voltage source, and is internally provided in the measuring unit 108. The impedance value is measured by an impedance measuring circuit not shown, whereby the capacitance component between the metal wire 30 and the bonding stage 14 is known. Alternatively, a DC pulse power source may be used instead of the AC voltage source as the application power source 106. Hereinafter, the description will be continued by using the applied power source 106 as an AC voltage source.

When the metal wire 30 is in a state of being connected to the lead of the circuit board 8 or the pad of the semiconductor wafer 6, the value of the capacitance component between the clip 32 and the bonding stage 14 becomes the capacitance value of the member of the wire bonding device 10, that is, the device capacitance value. The total value of the capacitance value of the circuit board 8 or the semiconductor wafer 6, that is, the device capacitance value. On the other hand, when the metal wire 30 is in the cut-off state 104, the metal wire 30 and the circuit board 8 or the semiconductor wafer 6 are electrically opened, and therefore the capacitance component between the wire clip 32 and the bonding stage 14 is only Is the device capacitance value. The unjoining determination circuit 36 determines whether the metal wire 30 is connected to the circuit board 8 or the semiconductor wafer 6 as the bonding target or is in an open state based on the change in the capacitance component in the measuring unit 108.

As shown in FIG. 2, in the respective processing steps of the wire bonding, the unjoining determination circuit 36 performs the determination in the following manner in each processing step. After the first wire bonding process of the first bonding point 100, the capacitance value between the wire clamp 32 or the bobbin 33 and the bonding platform 14 becomes the total value of the device capacitance value and the device capacitance value, and the metal wire 30 and the circuit substrate 8 are determined. The connection state is between. When the capillary 28 is lowered toward the second junction 102, and the metal line 30 is in contact with the second junction 102, the capacitance value between the clamp 32 and the bonding platform 14 is also the total value of the device capacitance value and the device capacitance value. Further, it is determined that the metal line 30 and the circuit board 8 are in a connected state.

After the second wire bonding process of the second bonding point 102, the connection state between the metal wire 30 and the semiconductor wafer 6 is determined based on the total value of the device capacitance value and the device capacitance value between the wire clamp 32 and the bonding platform 14. Wire cutting treatment Thereafter, the capacitance value between the wire clamp 32 and the bonding stage 14 becomes a value of the device capacitance value, and it is determined that the metal wire 30 and the semiconductor wafer 6 are in a disconnected state.

Returning again to Fig. 1, the computer 60 controls the operations of the respective members of the wire bonding device 10 as a whole. The computer 60 is configured to include a control unit 80 as a central processing unit (CPU), various interface circuits, and a memory 82. The parts are connected to each other by an internal bus.

Each of the interface circuits is a drive circuit or a buffer circuit provided between the control unit 80 of the CPU and each member of the wire bonding device 10. In Figure 1, the interface circuit is shown only as I/F. The various interface circuits are an XY stage I/F 62 connected to the XY stage 16, a Z-direction motor I/F 64 connected to the Z-direction motor 20, an ultrasonic vibrator I/F 66 connected to the ultrasonic vibrator 26, and connected to the clamp opening and closing. The jig opening/closing I/F 68 of the portion 34 and the unjoining determination circuit I/F 70 connected to the unjoined determination circuit 36.

The memory 82 is a memory device that stores various programs and various control data. The various programs are the first bonding program 84 for the first wire bonding process, the wire arc forming program 86 for the line arc forming process, the second bonding program 88 for the second wire bonding process, and the continuous monitoring with the unjoining determination circuit 36. The disconnected continuous monitoring program 90 for processing, the disconnection determination processing program 92 for determining the middle of the disconnection of the metal wire 30, and the abnormality output processing program 94 for outputting the abnormal signal output for the middle of the disconnection of the metal wire 30, Other control programs that control processing 96. The control data 98 is necessary for executing various programs or controlling programs.

The function of the above configuration, in particular, the functions of the computer 60 will be described in detail with reference to FIG. 3 and subsequent figures. FIG. 3 is a timing chart showing the operation of each member in the wire bonding process. Fig. 4 is a flow chart showing the procedure of the wire bonding method. Figure 5 is A timing chart is shown in association with the respective signals of the unjoined monitoring between the first joint point and the second joint point in association with the action of the capillary tube 28. 6 to 9 are views each showing a state of a metal wire between the first joint point and the second joint point.

3 is a time chart showing an operation state of each member until the second wire bonding process and the wire wire cutting of the second bonding point 102 are performed by the first wire bonding process from the first bonding point 100. The horizontal axis of Fig. 3 is time. The vertical axis of FIG. 3 sequentially indicates the height state of the capillary 28 from the upper stage side toward the lower stage side, the Z-direction motor 20 is in an operating state or a stopped state, the XY stage 16 is in an operating state or a stopped state, and the ultrasonic vibrator 26 is in an operating state or The stop state, the magnitude of the pressing force that presses the capillary 28 downward, and the clamp 32 are in a closed state or an open state.

The height state of the capillary 28 changes when the Z-direction motor 20 is in the operating state, and does not change when the Z-direction motor 20 is in the stopped state. The control of the operation and the stop of the Z-direction motor 20 is performed by driving the Z-direction motor 20 via the Z-direction motor I/F 64 when the control unit 80 executes various programs. If there is a stop command, stop the action. In addition to the change in the height state, the capillary tube 28 also changes the positional state in the XY plane by moving in the XY plane. The control of the movement of the capillary 28 in the XY plane is performed by the control unit 80 executing the various programs, and if there is a movement command of the XY stage 16, the XY stage 16 is moved and driven via the XY stage I/F 62. If there is a stop command, the mobile drive is stopped.

When the capillary 28 is located at the first joint 100 and the second joint 102, ultrasonic energy is supplied from the ultrasonic vibrator 26 to the capillary 28. The control of the ultrasonic energy supply from the ultrasonic vibrator 26 is performed by the control unit 80 executing various programs, and if there is an operation command of the ultrasonic vibrator 26, The ultrasonic vibrator I/F 66 operates the ultrasonic vibrator 26, and if there is a stop command, the operation is stopped.

When the capillary 28 is positioned at the first joint 100 and the second joint 102, the capillary 28 is given a predetermined pressing force via the ultrasonic transducer 24. The control of the magnitude of the pressing force can be performed as part of the drive control of the Z-direction motor 20. In other words, when the control unit 80 executes various programs, if there is a pressing force change command, the Z-direction motor I/F 64 is controlled by the Z-direction motor 20 to control the pressing force.

In the wire arc forming process or the wire cutting process, the wire clamp 32 is opened when the wire 30 is extended from the capillary 28, and the wire clamp 32 is closed when the wire 30 is stopped and the clamping is performed. When the control unit 80 executes various programs, when the control unit 80 executes various programs, when the wire clamp 32 is opened, the I/F 68 is opened and closed by the clamp, and the clamp opening/closing unit 34 is opened to open the clamp 32. With the closing action command, the clamp opening and closing portion 34 closes the clamp 32.

In FIG. 3, the time t ₀ to the time t ₄ are the first wire bonding processing steps, during which the control unit 80 executes the first bonding program 84. 3, at time t ₀ to time t just above the ₁ period, for driving the XY stage 16 is moved, the capillary 28 is moved to the first point of engagement. From time t ₀ to time t ₃ , the Z is driven to the motor 20, whereby the capillary 28 continues to descend. About decreases from time t ₀ to time directly above the capillary 28 is moved to the point of 100 t ₁ of the first high-speed engagement fall at times t ₁ to time in the capillary tube 28 contacts the circuit substrate 8 wire ₃ is disposed between t For low speed. This low speed drop is called the first search.

At time t between time _{t. 3} to _4, XY stage 16 and the Z-direction motor 20 are stopped, in this period, the operation of the ultrasonic vibrator 26 to impart ultrasonic energy to the capillary tube 28. The pressing force changes stepwise between the time t ₁ and the time before and after the start of the operation of the ultrasonic vibrator 26 . Thus, at time t between time _{t. 3} to _4, the first joint 100, between the wire and the tip of the capillary 28 of the circuit board 8 interposed therebetween protrudes from the distal end 30 of the capillary 28 of the metal wire, and by ultra The bonding between the wire 30 and the wire is performed by the sonic energy and the pressing force. During the bonding process, the bonding platform 14 is preferably heated to maintain the appropriate processing temperature.

In FIG. 3, time t ₄ to time t ₁₀ are periods during which the line arc forming processing step. At this time, the pressing force is restored. During this period, the control unit 80 executes the line arc forming program 86. 3, at time t between time t _{5. 4} only to the Z-direction motor 20 is driven, whereby the capillary tube 28 is slightly increased. Between time t ₅ and time t ₆ , only the XY stage 16 is mobile driven. The movement drive is performed in the form of a reverse movement in which the capillary 28 is temporarily returned from the first joint 100 to the opposite side of the second joint 102 in the XY plane. Only the Z-direction motor 20 is driven between time t ₆ and time t ₇ so that the capillary 28 rises at the position after the reverse movement. Then, at time t between time t _{8. 7} to maintain the state. In this state, the line arc of the wire 30 becomes the highest point. Between time t ₈ and time t ₉ , the XY stage 16 is slightly driven in a state where the wire clip 32 is closed. This movement drive is performed in such a manner that the position of the capillary 28 from the reverse movement in the XY plane is moved in the direction of the second joint 102. Thereby, the line arc is stretched toward the second joint point 102 side, and the highest point of the line arc is adjusted to the desired height.

At time t ₉ open clip 32, wire 30 may be in a state of extending from the distal end of the capillary 28 out. Then, at time t ₉ to ₁₀ between time t, and for driving the XY stage 16 is moved, and the Z drive motor 20. Thereby, the capillary wire 28 is lowered while the metal wire 30 is extended toward the second joint 102, and the wire arc is lowered downward.

At time t ₁₀ , the capillary 28 reaches directly above the second junction 102. The time t ₁₀ to the time t ₁₃ is the period of the second wire bonding processing step of the second bonding point 102. During this period, the control unit 80 executes the second engagement program 88. About 28 drops of the capillary, from time t ₉ to the capillary 28 is moved to a second time just above the engaging point 102 t ₁₀ high speed decrease, at time t ₁₀ to the capillary contact with the semiconductor wafer 28 time pad 6 t ₁₂ The setting is set to low speed. This low speed drop is referred to as a second search.

At time t to time t _{12 is} between _13, XY stage 16 and the Z-direction motor 20 are stopped, in this period, the operation of the ultrasonic vibrator 26 to impart ultrasonic energy to the capillary tube 28. The pressing force changes stepwise between the time t ₁₀ and the time before and after the start of the operation of the ultrasonic vibrator 26. As a result, between the time t ₁₂ and the time t ₁₃ , at the second joint 102, a metal wire 30 protruding from the front end of the capillary 28 is sandwiched between the tip end of the capillary 28 and the pad of the semiconductor wafer 6, and The bonding between the metal wire 30 and the wire is performed by ultrasonic energy and pressure. During the bonding process, the bonding platform 14 is preferably heated to maintain the appropriate processing temperature.

In Fig. 3, time t ₁₃ to time t ₁₅ are periods during which the wire cutting process is performed. The wire cutting process step can be distinguished from the second wire bonding process by a step of executing a dedicated wire cutting process program by the control unit 80. Alternatively, the period may be included in the second wire bonding process, and the second bonding program 88 may include a wire cutting process.

In the wire cutting process step, the pressing force is restored. 3, at time t to time t _{13 is} the Z-direction only between the motor 20 is driven _14, whereby the capillary tube 28 is slightly increased. Between time t ₁₄ and time t ₁₅ , the clamp 32 is closed, the XY stage 16 is moved and driven, and the Z-direction motor 20 is driven. This movement drive is performed such that the capillary 28 moves in the XY plane while rising. Thereby, the wire 30 is cut at the second joint 102.

In this manner, after the first wire bonding process from the first bonding point 100 is subjected to the wire arc forming process, the second wire bonding process and the wire wire cutting of the second bonding pad 102 are performed.

The functions of the above-described configuration, and in particular, the functions of the continuous monitoring of the unconnected control unit 80 and the midway cutting determination of the wire 30 will be described in detail with reference to FIGS. 4 to 9 . 4 is a flowchart showing the order from the first wire bonding process to the second wire bonding process in the order of the wire bonding method, and the order corresponds to the processing order of each program stored in the memory 82 of the computer 60. When the wire bonding device 10 is turned on or the like, initialization of each component of the wire bonding device 10 including the computer 60 is performed.

Then, the bonding stage 14 is temporarily pulled out, and the circuit board 8 on which the semiconductor wafer 6 is mounted as the bonding target is positioned and placed on the bonding stage 14, and is fixed by being pressed by the window clamp 50. The joining platform 14 is returned to the position of the initial state again. Further, the joining platform 14 is heated to a predetermined temperature determined in the joining condition. This bonding target setting step is automatically performed using the automatic transfer device of the circuit board 8.

Next, the first joining program 84 is executed by the control unit 80, and the first joining process is performed at the first joining point 100 (S10). The first bonding point 100 is set on one of the wires of the circuit board 8. The setting of the first joint 100 is performed using a positioning camera or the like not shown in FIG. The operation of each member in the first wire bonding process has been described in FIG. 3, and thus detailed description thereof will be omitted.

At the first joint 100, at the front end portion of the capillary 28 and the circuit substrate 8 The wire 30 is sandwiched between the wires and pressed, by the ultrasonic vibration energy of the ultrasonic vibrator 26, the pressing force of the capillary 28 generated by the driving control of the Z-direction motor 20, and optionally from the bonding platform. The heating temperature of 14 is to bond the metal wire 30 to the wire. In this way, the first wire bonding process at the first joint 100 is performed.

When the first wire bonding process is completed, the line arc forming process is performed (S12). This processing sequence is performed by the control unit 80 executing the line arc forming program 86. That is, after the completion of the first wire bonding process, the capillary 28 is raised upward while the wire clamp 32 is opened, and then moved to the immediately above the second bonding point 102. The second junction 102 is disposed on one of the pads of the semiconductor wafer 6. While the capillary 28 is moving, the wire 30 is successively fed from the bobbin 33, and the necessary line length is extended from the front end of the capillary 28. The operation of each member in the line arc forming process has been described in FIG. 3, and thus detailed description thereof will be omitted.

During the line arc forming process, continuous monitoring without engagement is performed (S14). This processing sequence is performed by the control unit 80 executing the unjoined continuous monitoring program 90. The unjoined continuous monitoring is performed in such a manner that the unjoining determination circuit 36 is continuously operated via the unjoining determination circuit I/F 70 in accordance with an instruction from the control unit 80, and the control unit 80 continuously receives the obtained result.

The continuous operation of the unjoined determination circuit 36 is such that the AC voltage source as the application power source 106 illustrated in Fig. 2 operates continuously for a predetermined continuous monitoring period. Thereby, an alternating voltage signal is continuously applied between the metal wire 30 held by the capillary 28 and the bonding platform 14. The measuring unit 108 described in FIG. 2 acquires the capacitance value between the wire 30 held by the capillary 28 and the bonding stage 14, and transmits the value to the control unit 80 sequentially via the unjoining determination circuit I/F 70.

It is determined whether or not the metal wire is cut in the middle by continuous monitoring without joint (S16). This processing sequence is performed by the control unit 80 executing the cut determination processing program 92.

In FIG. 5, the time change of each signal when the continuous monitoring is not engaged is shown in association with the operating state of the capillary 28. The horizontal axis of Fig. 5 is time. The vertical axis is the operation state of the capillary 28 from the upper stage side toward the lower stage side of the paper surface, the output of the measurement unit 108 of the unjoined determination circuit 36, that is, the unjoined monitoring output, and the differential output obtained by differentiating the unjoined monitoring output. The timing of unjoined monitoring in the prior art.

The time t ₄ , time t ₇ , time t ₉ , and time t _{12 on the} horizontal axis are the same as those described in FIG. That is, the time t ₄ is the timing at which the line arc forming process is started after the bonding process of the first bonding point 100 is completed, and the period from the time t ₇ to the time t ₉ is the period in which the line arc which is the highest position is formed, and t ₁₂ is the capillary 28 The timing at which the metal line 30 contacts the second junction 102 is lowered. As shown in the lowermost section of Fig. 5, the time T ₁ , the time T ₂ , and the time T ₃ are the timings of the unjoined monitoring in the prior art. Here, the timing is just before the time t ₄ , just after the time t _{7 , and} after t ₁₂ . This case is an example, and there is a case where the unsynchronized monitoring is performed by an appropriate sampling timing other than this.

As shown by the unjoined monitor output of the second stage from the top of FIG. 5, this is not the sampling timing of the prior art, but the unjoined determination circuit 36 is continuously operated during the predetermined continuous monitoring period. The continuous monitoring period is set to be suitable for monitoring whether or not the wire 30 is cut from the first joint to the second joint after the first joining process. Here, the entire period from the first joint point to the second joint point is set as the continuous monitoring period. Alternatively, for example, a period between T ₁ and T ₃ used in the prior art is set as a continuous monitoring period. Alternatively, T ₁ and T _{3 of the} uncombined monitoring sampling timing of the prior art may be directly retained, and the time t _{7 when the} capillary 28 is at the highest position and the time t ₁₂ when the capillary 28 is the lowest position are set as the continuous monitoring period. .

The unjoined monitor output is a time change indicating the capacitance value by the output of the measuring unit 108 of the unjoined determination circuit 36. In FIG. 5, for example to increase the capillary 28 C ₀ time to time a capacitance value C ₁ is maintained substantially constant value, to decrease abruptly at the time a capacitance value C _1. When the wire 30 is cut off, the capacitance value detected from the measurement section 108 "total value of the capacitance value of the capacitance value of the device apparatus" to "means the capacitance value" can be determined and therefore the metal wire ₃₀₁ is cut at time C Broken. Time to reduce the capacitance value C is maintained after the time C between ₂ to _1, but at the time a capacitance value C ₂ abruptly restored to the original high value. In this case, it is considered that the "device capacitance value" is restored to "the total value of the device capacitance value and the device capacitance value", and it can be determined that the metal wire 30 extending from the tip end of the capillary 28 due to the middle cut of the metal wire 30 is in contact with The circuit substrate 8 or the semiconductor wafer 6.

In this manner, the capacitance value between the metal wire 30 held by the capillary 28 and the bonding stage 14 is obtained, and when the capacitance value is lowered after the first bonding process, it can be determined that the metal wire 30 is cut in the middle of the line arc. In addition, when the capacitance value is restored before reaching the second bonding point, it can be determined that the cut metal wire 30 hangs down and comes into contact with the circuit substrate 8 or the semiconductor wafer 6 as the bonding target.

In the sampling timing of the unjoined monitoring of the prior art, at any one of the time T1, the time T2, and the time T3, the capacitance values are the same value without change, and therefore, the middle of the wire 30 cannot be detected. .

In the above, it is determined whether or not the metal wire 30 is halfway due to a change in the capacitance value. Cut off. The detection of the change in the capacitance value can be performed using a comparison of the threshold capacitance values using a threshold capacitance value. Instead, it is determined whether or not the metal wire 30 is cut off halfway based on the differential value obtained by differentiating the electric signal representing the capacitance value with respect to time. The differential output of FIG. 5 is an output obtained by differentiating the unjoined monitor output from time. When the capacitance value is drastically lowered, the pulse wave in the negative direction is output, and if the capacitance value rises and falls sharply, the pulse wave in the positive direction is output. Whether or not the wire 30 is cut off halfway can be determined based on the presence or absence of the pulse wave output.

6 to 9 are diagrams showing states of the metal wires 30 at times t ₄ , time C ₀ , time C ₁ , and time C ₂ .

At the time shown in FIG. 6 t _4, the first joint 100, between the wire and the tip of the capillary 28 of the circuit board 8 interposed therebetween protrudes from the distal end 30 of the capillary 28 is a metal wire. Therefore, the capacitance value detected by the measurement unit 108 becomes "the total value of the device capacitance value and the device capacitance value".

At time C ₀ shown in FIG. 7, the capillary 28 is in a state in which X1 is moved from the first joint 100 in the XY plane, and the height in the Z direction is raised to Z1 based on the upper surface of the circuit board 8. The metal wire 30 is extended from the capillary 28 in a state where the metal wire 30 is bonded to the circuit board 8 at the first joint 100. At this time, the capacitance value detected by the measurement unit 108 is also "the total value of the device capacitance value and the device capacitance value".

The time C ₁ shown in FIG. 8 is the time when the height of the capillary 28 in the Z direction becomes the highest value Z2, the clip 32 is closed, and the XY stage 16 has moved by the distance X2 from the first joint 100 in the XY plane (refer to the figure). 3). Here, it is shown that the metal wire 30 is in the cut-off state 104 between the first joint 100 and the tip end of the capillary 28. The portion of the wire 30 that extends from the capillary 28 in the direction of the first joint 100 and is cut is the tip end portion 105. In addition, the above-described state in which the cutting time C ₁ is generated is exemplified, and the cutting may be performed in other states as long as it is in the middle of the second joining point 102 from the first joining point 100.

At this time, the capacitance value detected by the measurement unit 108 becomes the "device capacitance value", and the capacitance value is drastically lowered from the "total value of the device capacitance value and the device capacitance value". According to the unjoined continuous monitoring, it is determined that the wire 30 is cut off in the middle of the line arc by detecting a sudden decrease in the capacitance value.

The time C ₂ shown in Fig. 9 is the time when the capillary 28 is lowered in the Z direction to the height of Z3, and one side is moved in the XY plane, and the distance X3 is moved from the first joint 100, and the front end of the capillary 28 reaches the second joint. Just above point 102. Z ₃ is a value smaller than Z ₂ of Fig. 8, and X ₃ is a value larger than X ₂ of Fig. 8 . At this time, the tip end portion 105 of the wire 30 extending from the capillary 28 is in contact with the circuit board 8 due to the decrease of the capillary 28. At this time, the capacitance value detected by the measurement unit 108 rises sharply and returns to the "total value of the device capacitance value and the device capacitance value". According to the unjoined continuous monitoring, when the sudden rise recovery of the capacitance value is detected, the sudden decrease detection of the capacitance value of the previous time C ₁ is combined, and it can be determined that the case does not indicate between the metal wire 30 and the first bonding point 100. The connection is normal, and the metal wire 30 is cut in the middle of the line arc, and the front end portion 105 is suspended to contact the object to be joined.

Returning to FIG. 4 again, if it is determined in S14 whether or not the metal wire is cut in the middle, it is determined that the wire is not cut in the middle, and then the second wire bonding process is performed at the second joint 102 (S18). This processing sequence is performed by the control unit 80 executing the second joining program 88. The second junction 102 is disposed on one of the pads of the semiconductor wafer 6. The setting of the second joint 102 is performed using a positioning camera or the like not shown in FIG. The operation of each member in the second wire bonding process has been performed in FIG. The description is omitted, so detailed description is omitted.

If it is determined in S16 that the metal wire is cut in the middle, it is determined that the metal wire is cut off in the middle, and an abnormal signal is output (S20), and the operation of the wire bonding device 10 is stopped (S22). This processing sequence is performed by the control unit 80 executing the abnormality output processing program 94.

By continuously performing the unjoined monitoring by continuously operating the unjoined determination circuit 36, even when the aluminum wire having a smaller stretch than the gold wire is used for the wedge bonding of the capillary 28, the first joint 100 can be accurately judged to The presence or absence of the wire break between the second joints 102.

In the above, the predetermined continuous monitoring period is a period in which the metal wire is extended from the first bonding point to the second bonding point after the first bonding process, but may be performed from the first bonding process to the above. The continuous monitoring period is set for the entire period after the second joining.

During the continuous monitoring period, the unjoined monitoring unit continuously applies a predetermined electrical signal to the wire 30 held between the capillary 28 and the bonding platform 14. Then, with respect to the continuous response of the electric signal, an appropriate judgment threshold is used to monitor and judge whether or not the connection state of the wire 30 is changed.

When the unbonded metal wire of the first joint is F1, the middle of the wire during the arc formation is cut into F2, and the unbonded wire of the second joint is F3, and the second is After the joining process and the middle cut of the wire before the wire cutting process is F4, an appropriate determination threshold value is used for each of F1 to F4. In this way, F1 to F4 can be distinguished and monitored.

Hereinafter, continuous monitoring is performed for the entire period from the first bonding process to the second bonding process, and will be about F1 to F4, using FIGS. 10 to 12 . The contents of the difference are described in detail.

Fig. 10 is a view corresponding to Figs. 6 to 9, and further expanded in a state shown in Figs. 6 to 9, showing the joining of the wires 30 from the first bonding process to the second bonding after the second bonding. Figure. Here, the metal wire 31 which has been subjected to the following treatment without any problem is shown: a first bonding process performed on the first bonding point of the circuit board 8, a line arc forming process after the first bonding process, and a line arc forming process Thereafter, the second bonding process is performed on the second bonding point of the semiconductor wafer 6, and the cutting process of the metal wire 30 is cut after the second bonding process.

In FIG. 10, the metal wire of the first joint is not joined, that is, F1, and the middle of the wire during the formation of the arc is F2, and the wire of the second joint is not joined, that is, F3, and the second. The portion where F4 is generated is cut in the middle of the metal wire before the bonding process and before the wire cutting process.

The unjoining determination circuit 36 shown in FIG. 10 is the same as that described in FIG. 2, and includes an application power source 106 that outputs a predetermined electric signal, and a measurement unit 108 that measures a response to a predetermined electric signal. Here, as a predetermined electrical signal, an AC voltage signal or a DC voltage signal is used.

The use of the electric signal can be determined depending on whether or not the semiconductor wafer 6 and the circuit board 8 are connected to the bonding platform 14 only with a resistance component. When the semiconductor wafer 6 and the circuit board 8 are both connected to the bonding platform 14 only with a resistance component, a DC voltage signal can be used as a predetermined electrical signal. The semiconductor wafer 6 and the circuit board 8 are not considered to be connected to the bonding platform 14 only by a resistance component, and when a capacitor component is included, an AC voltage signal is used as a predetermined electrical signal.

When using an AC voltage signal as a prescribed electrical signal, the measuring unit 108 measures the change in capacitance between the wire 30 of the spacer 32 and the landing platform 14. The capacitance value can be converted into a voltage value using an appropriate conversion circuit, and the change in the capacitance value is measured by measuring the change in the converted voltage value. When the DC voltage signal is used as a predetermined electrical signal, the measuring unit 108 measures the change in the presence or absence of an electrical short between the wire 30 of the spacer 32 and the bonding stage 14.

The presence or absence of an electrical short is performed by measuring the voltage value as follows. In other words, the potential of the bonding platform is set to the ground voltage value V=0 (V), and the DC voltage signal having a voltage higher than the ground voltage value by the predetermined voltage value V ₀ is set as a predetermined electrical signal. Further, when the measured voltage value is V = 0 (V), there is an electrical short between the metal wire 30 and the bonding stage 14, and when the measured voltage value is a predetermined voltage value V ₀ , it is set to There is an electrical short circuit.

11(a) to 11(f) show the case where the AC voltage signal is used as a predetermined electrical signal, and the capacitance value between the metal wire 30 and the bonding platform 14 as a continuous response of the electrical signal is measured. A diagram that distinguishes F1 to F4. 11(a) to 11(f) are composed of the six timing charts of Figs. 11(a) to 11(f). In all of these timing diagrams, the horizontal axis is time. The vertical axis of Fig. 11(a) is the height position of the capillary, and the vertical axis of Figs. 11(b) to 11(f) is the capacitance between the metal wire 30 and the bonding stage 14.

Fig. 11(a) corresponds to the uppermost diagram of Fig. 3. The time t ₃ , the time t ₄ , the time t ₁₂ , the time t ₁₃ , and the time t _{14 on the} horizontal axis are the same as those described in FIG. That is, the period from time t ₃ to t ₄ is the first bonding processing period, the period from t ₁₂ to t ₁₃ is the second bonding processing period, and t ₁₄ is cut by the operation of the clip 32 after the second bonding processing. Timing of metal lines 30.

Fig. 11 (b) shows that before the first bonding process to the above A time chart of the temporal change of the capacitance value measured by the good products of all the processes without any problem during the entire period after the second bonding.

In in FIG. 11 (b), before the time until the metal wire ₃ t 30 is not in contact with the circuit board 8, so the capacitance value of the capacitance value becomes 30 means interposed between the metal wire 14 wire apparatus 10 and the bonding stage. The device capacitance value is represented as C _M in FIG.

When the wire 30 at time t ₃ in contact with the circuit substrate 8, plus the capacitance value of the circuit board 8 and has measured. The capacitance value of the circuit board 8 is shown as C _L in FIG. Thus, after the time t ₃ to time t during a measurement value of the capacitance value becomes ₁₂ (C _M + C _L).

When the wire 30 at time t ₁₂ in contact with the semiconductor wafer 6, plus the capacitance value of the further semiconductor wafer 6 having being measured. The capacitance value of the semiconductor wafer 6 is shown as C _P in FIG. Thus, after the time t to time t _{12 is} the capacitance value measured during ₁₄ becomes a value _{(C M + C L + C} P).

When the wire 30 at time t ₁₄ is cut by the cutting process, the state shown in FIG. 10, the metal line on a semiconductor wafer 830 away from the circuit board 6 without contact, so the measurement value of the capacitance value Again becomes the device capacitance value C _M .

Fig. 11 (c) is a timing chart showing temporal changes in the capacitance value when the first junction is not joined with F1. During the process F1 are not bonded to the first bonding i.e., the time t between time _{t. 3} and ₄ produced. When the unbonded F1 is generated, since the metal wire 30 is not firmly connected to the circuit board 8, the capacitance value becomes a smaller value than the capacitance value (C _M + C _L ) at the time t ₃ at the time of good product.

In order to distinguish between good and unjoined F1, the capacitance value measured stably before t ₃ can be used as a reference. For example, using the capacitance value C _M before t ₃ as a reference, a value obtained by adding the C _M to a predetermined measurement margin is used as the first reference value J1, and the first reference value J1 is used as the difference between the good and the F1. Judgment threshold. To simplify the explanation, it is set as J1 = C _M in Fig. 11 (c). When the measured capacitance value exceeds J1, it is judged to be good, and when it is less than J1, it is judged as F1. An example of a good product is the measured capacitance value (C _M + C _L ), and an example of F1 is that the measured capacitance value is still C _M .

Fig. 11 (d) shows that the processing of the first junction is normal, and the capacitance value measured at time t ₃ is (C _M + C _L ), but when F2 is cut in the middle of the occurrence of the wire 30 in the line arc forming process. A timing diagram of the time variation of the capacitance value. The cut F2 is generated midway between time t ₄ and time t ₁₂ . When the F2 is cut in the middle, the metal wire 30 is separated from the circuit board 8, and the measured capacitance value is a value smaller than the capacitance value (C _M + C _L ) at the time t ₄ at the time of good product.

In order to distinguish between good products and cut off F2 in the middle, the capacitance value measured stably after t ₄ can be used as a reference. For example, using the capacitance value (C _M + C _L ) at t ₄ as a reference, a value obtained by adding the (C _M + C _L ) to a predetermined measurement margin is used as the second reference value J2, and the The second reference value J2 is used as a judgment threshold for distinguishing between good products and F2. To simplify the explanation, it is assumed that J2 = (C _M + C _L ) in Fig. 11 (d). When the measured capacitance value is still J2, it is judged to be good, and when it is less than J2, it is judged as F2. An example of a good product is a measured capacitance value (C _M + C _L ), and an example of F2 is a measured capacitance value C _M .

Fig. 11(e) is a timing chart showing temporal changes in the capacitance value when the line arc forming process is normal, but when the second junction is not joined to F3. Unjoined F3 is produced between time t ₁₂ and time t ₁₃ . When the unbonded F3 is generated, since the metal wire 30 is not firmly connected to the semiconductor wafer 6, the capacitance value becomes a smaller value than the capacitance value (C _M + C _L + C _P ) at the time t ₁₂ at the time of good product.

In order to distinguish between good and unjoined F3, the capacitance value measured stably after t ₄ can be used as a reference. For example, using the capacitance value (C _M + C _L ) at t ₄ as a reference, a value obtained by adding the (C _M + C _L ) to a predetermined measurement margin is used as the third reference value J3, and the The third reference value J3 is used as a judgment threshold for distinguishing between good products and F3. To simplify the explanation, it is assumed that J3 = J2 = (C _M + C _L ) in Fig. 11(e). If the measured capacitance value exceeds J3, it is judged to be good, and when it is still J3, it is judged as F3. An example of a good product is a measured capacitance value (C _M + C _L + C _P ), and an example of F3 is a measured capacitance value (C _M + C _L ).

Fig. 11 (f) shows that the processing of the second junction is normal, and the capacitance value measured at time t ₁₂ is (C _M + C _L + C _P ), but the metal line 30 is generated before the subsequent metal wire cutting process. A timing chart showing the time change of the capacitance value when F4 is cut off. Midway cut F4 is generated between time t ₁₃ and time t ₁₄ . When the F4 is cut in the middle, since the metal wire 30 is separated from the semiconductor wafer 6, the measured capacitance value becomes a smaller value than the capacitance value (C _M + C _L + C _P ) at the time t ₁₃ of the good product. .

In order to distinguish between good products and cut F4 in the middle, the capacitance value measured stably before t ₁₃ can be used as a reference. For example, using the capacitance value (C _M + C _L + C _P ) at t ₁₃ as a reference, a value obtained by subtracting the (C _M + C _L + C _P ) from a predetermined measurement margin is used as the fourth. The reference value J4 uses the fourth reference value J4 as a determination threshold for distinguishing good products from F4. To simplify the explanation, it is assumed that J4 = (C _M + C _L + C _P ) in Fig. 11 (f). When the measured capacitance value is still J4, it is judged to be good, and when it is less than J4, it is judged as F4. An example of a good product is a measured capacitance value (C _M + C _L + C _P ), and an example of F4 is a measured capacitance value (C _M + C _L ).

In this way, the predetermined electrical signal uses the AC voltage signal, and the first reference value J1 to the fourth reference value J4 are used as the determination reference corresponding to F1 to F4, respectively, thereby distinguishing the unjoined F1 line arc of the first joint point. Midway cut in formation process F2, the unjoined F3 of the joint, and the middle of the wire cutting process before the cutting of F4.

12(a) to 12(f) show the case where the DC voltage signal is used as a predetermined electrical signal, and the voltage value between the metal wire 30 and the bonding platform 14 as a continuous response of the electrical signal is measured. A diagram that distinguishes F1 to F4. 12(a) to 12(f) are diagrams corresponding to Figs. 11(a) to 11(f), and are composed of the six timing charts of Figs. 12(a) to 12(f). Similarly to FIGS. 11(a) to 11(f), in all of the timing charts, the horizontal axis is time. Further, the vertical axis of Fig. 12(a) is the height position of the capillary, and the vertical axis of Figs. 12(b) to 12(f) is the voltage value between the metal wire 30 and the bonding stage 14.

Fig. 12(a) corresponds to the uppermost diagram of Fig. 3 in the same manner as Fig. 11(a). The time t ₃ , the time t ₄ , the time t ₁₂ , the time t ₁₃ , and the time t _{14 on the} horizontal axis are also the same as those described in FIG. 11 (a) to FIG. 11 (f), and therefore the detailed description is omitted. instruction of.

Fig. 12 (b) is a timing chart showing temporal changes in voltage values measured for good products that have undergone all processes without problems during the entire period from the first bonding process to the second bonding process.

In in FIG. 12 (b), before the time until the metal wire ₃ t 30 is not in contact with the circuit board 8, thus joining the metal wire 30 with no electrical shorting between the internet 14, the measured voltage value becomes the predetermined voltage value V _0.

When the metal wire 30 comes into contact with the circuit board 8 at time t ₃ , an electrical short circuit occurs between the bonding stage 14 and the metal wire 30 via the circuit board 8 . Thereby, the measured voltage value becomes V=0 (V).

If the metal line 30 contacts the semiconductor wafer 6 at time t ₁₂ , the junction between the bonding platform 14 and the metal line 30 is still electrically shorted via the semiconductor wafer 6 and the circuit substrate 8 , and the measured voltage value is still V=0. (V). When the metal wire 30 is cut by the cutting process at time t ₁₄ and the state shown in FIG. 10 is reached, the metal wire 30 is separated from the semiconductor wafer 6 on the circuit board 8 and is not in contact with each other. There is no electrical short circuit between the 30 and the joining platform 14, and the measured voltage value again becomes the predetermined voltage value V ₀ .

When so, to a DC voltage signal as a predetermined electrical signal, in the case where the yield, the time _{t. 3} to time t ₁₄ becomes a voltage value between V = 0 (V).

Fig. 12 (c) is a timing chart showing temporal changes in voltage values when the first junction is not joined with F1. During the process F1 are not bonded to the first bonding i.e., the time t between time _{t. 3} and ₄ produced. When the unbonded F1 is generated, since the metal wire 30 is not firmly connected to the circuit board 8, there is no electrical short between the metal wire 30 and the bonding stage 14. Therefore, the voltage value is still the voltage value at the time t ₃ when the product is good, that is, the predetermined voltage value V ₀ .

In order to distinguish between good and unjoined F1, a voltage value that is stably measured before t ₃ can be used as a reference. For example, using the predetermined voltage value V ₀ which is a voltage value before t ₃ as a reference, a value obtained by adding the predetermined voltage value V ₀ to a predetermined measurement margin is used as the first reference value J1, and the first reference is used. The value J1 is used as a judgment threshold for distinguishing between good products and F1. To simplify the explanation, it is set as J1 = V ₀ in Fig. 12 (c). When the measured voltage value is less than J1, it is judged to be good, and when J1 is judged to be F1. An example of a good product is that the measured voltage value is V = 0 (V), and an example of F1 is that the measured voltage value is still V ₀ .

Fig. 12 (d) shows that the processing of the first junction is normal, and the voltage value measured at time t ₃ is V = 0 (V), but when F2 is cut in the middle of the wire 30 in the line arc forming process. Timing diagram of the time variation of the voltage value. The cut off F2 is generated between time t ₄ and time t ₁₂ . If F2 of being interrupted is generated, since the wire 30 away from the circuit board 8, and therefore a state engaged with the platform 14 without an electrical short between the metal wire 30, the measured voltage value becomes more than the time t ₄ at yield A value at which the voltage value V = 0 (V) is large.

In order to distinguish between good products and cut off F2 in the middle, the voltage value measured stably after t ₄ can be used as a reference. For example, using the voltage value V=0 (V) at t ₄ as a reference, a value obtained by adding the V=0 (V) to a predetermined measurement margin is used as the second reference value J2, and the second is used. The reference value J2 is used as a judgment threshold for distinguishing between good products and F2. To simplify the description, J2 = 0 (V) is set in Fig. 12 (d). When the measured voltage value is still J2, it is judged to be good, and when it exceeds J2, it is judged as F2. An example of a good product is that the measured voltage value is V = 0 (V), and an example of F2 is that the measured voltage value is V ₀ .

Fig. 12(e) is a timing chart showing temporal changes in the voltage value when the line arc forming process is normal, but when the second junction is not joined to F3. Unjoined F3 is produced between time t ₁₂ and time t ₁₃ . If the unbonded F3 occurs, since the metal wire 30 is not firmly connected to the semiconductor wafer 6, there is no electrical short between the metal wire 30 and the bonding stage 14. Therefore, the voltage value becomes the predetermined voltage value V ₀ .

In order to distinguish between good and unjoined F3, the voltage value measured stably after t ₄ can be used as a reference. For example, using the voltage value V=V(V) when t ₄ is used as a reference, a value obtained by adding the V=0 (V) to a predetermined measurement margin is used as the third reference value J3, and the third is used. The reference value J3 is used as a judgment threshold for distinguishing between good products and F3. To simplify the description, it is assumed that J3 = J2 = 0 (V) in Fig. 12 (e). If the measured voltage value is still J3, it is judged to be good, and when it exceeds J3, it is judged as F3. An example of a good product is that the measured voltage value is V = 0 (V), and an example of F3 is that the measured voltage value is V ₀ .

Fig. 12 (f) shows that the processing of the second junction is normal. Although the voltage value measured at time t ₁₂ is still V = 0 (V), the middle of the metal line 30 is generated before the subsequent metal wire cutting process. A timing chart showing the time variation of the voltage value when F4 is turned off. Midway cut F4 is generated between time t ₁₃ and time t ₁₄ . When the F4 is cut in the middle, the metal wire 30 is separated from the semiconductor wafer 6, so that there is no electrical short circuit between the metal wire 30 and the bonding stage 14. The measured voltage value is a value larger than the voltage value V=0 (V) at the time t ₁₃ at the time of good product.

In order to distinguish between good products and cut off F4 in the middle, the voltage value measured stably before t ₁₃ can be used as a reference. For example, using the voltage value V=0 (V) at t ₁₃ as a reference, a value obtained by subtracting the V=0 (V) from a predetermined measurement margin is used as the fourth reference value J4, and the fourth is used. The reference value J4 is used as a judgment threshold for distinguishing between good products and F4. To simplify the explanation, it is assumed that J4 = J3 = J2 = 0 (V) in Fig. 12 (f). When the measured voltage value is still J4, it is judged to be good, and when it exceeds J4, it is judged as F4. An example of a good product is that the measured voltage value is V = 0 (V), and an example of F4 is that the measured voltage value is V ₀ .

In this way, the predetermined electrical signal uses the DC voltage signal, and the first reference value J1 to the fourth reference value J4 are set as the judgment reference corresponding to F1 to F4, respectively, thereby distinguishing the unjoined F1 line of the first joint point. In the arc forming process, the F2 is cut in the middle, the unjoined F3 at the joint is cut, and the F4 is cut in the middle before the wire cutting process. In particular, J2 = J3 = J4 = 0 (V) can be set, and measurement and determination become easy.

In the above, the wire bonding of the first joint and the second joint is described by a wedge joint using a capillary tube, but it can also be performed by a spherical joint method.

The present invention is not limited to the embodiments described above, and includes All changes and modifications of the technical scope and nature of the invention as defined by the scope of the claims.

[Industrial availability]

The present invention can be utilized in an apparatus and method for wire bonding using a capillary.

6‧‧‧Semiconductor wafer

8‧‧‧ circuit board

10‧‧‧Wireing device

12‧‧‧ pedestal

14‧‧‧Joining platform

16‧‧‧XY platform

18‧‧‧ Bonding head

20‧‧‧Z-direction motor

22‧‧‧Z-direction drive arm

24‧‧‧Ultrasonic Converter

26‧‧‧Ultrasonic vibrator

28‧‧‧ Capillary

30‧‧‧Metal wire

32‧‧‧Clamps

33‧‧‧ spool

34‧‧‧Clamp opening and closing department

36‧‧‧Unjoined decision circuit

50‧‧‧window fixture

60‧‧‧ computer

62‧‧‧XY platform I/F

64‧‧‧Z-direction motor I/F

66‧‧‧Ultrasonic Vibrator I/F

68‧‧‧Clamp opening and closing I/F

70‧‧‧Unjoined decision circuit I/F

80‧‧‧Control Department

82‧‧‧ memory

84‧‧‧First joint program

86‧‧‧Line arc forming program

88‧‧‧Second joint program

90‧‧‧Unjoined continuous monitoring program

92‧‧‧cut judgment handler

94‧‧‧Exception output processing program

96‧‧‧Control program

98‧‧‧Control data

X, Y, Z‧‧ Direction

Claims (14)

A wire bonding device includes: a first bonding processing unit that bonds a bonding object and a metal wire at a first bonding point of the wire bonding; and a non-joining monitoring portion that is in a predetermined continuous state after the first bonding process During the monitoring period, a predetermined electrical signal is continuously applied between the metal wire held by the capillary and the object to be bonded, and based on the continuous response of the electrical signal, the metal wire and the object to be bonded are monitored and determined. Whether the connection changes. The wire bonding device according to claim 1, wherein the predetermined continuous monitoring period is such that after the first bonding process, the metal wire is extended from the first bonding point to the second bonding point of the bonding wire. period. The wire bonding device according to the second aspect of the invention, wherein the non-joining monitoring unit applies a predetermined electrical signal to the metal wire held between the capillary and the bonding object, and obtains the above-mentioned capillary held by the capillary. The capacitance value between the metal wire and the bonding target is determined to be that the metal wire is cut from the bonding target after the first bonding process is lowered, and then the second bonding point is reached after the second bonding point is reached. When the capacitance value is restored, it is determined that the cut metal wire is suspended and contacts the bonding target object. The wire bonding device of claim 3, wherein the predetermined electrical signal is any one of an alternating current electrical signal and a direct current pulse signal. The wire bonding device according to claim 3 or 4, wherein the unjoined monitoring unit is The reduction and recovery with respect to the capacitance value are determined based on the differential value obtained by differentiating the capacitance value obtained as described above with respect to time. The wire bonding device according to any one of claims 1 to 5, wherein the wire bonding of the first joint and the second joint is performed by a wedge joint. A wire bonding method includes: a first bonding process step of bonding a bonding object and a metal line at a first bonding point of the wire bonding; and a continuous monitoring step, after the first bonding process, causing the metal wire from the above A predetermined electric signal is continuously applied between the metal wire held by the capillary and the object to be bonded, and the metal held by the capillary is obtained while the first joint is extended to the second joint of the wire. a change in a capacitance value between the line and the object to be bonded; and a midway cutting determination step, when the capacitance value is lowered after the first bonding process, it is determined that the metal wire is cut in the middle, and then reaches the second When the capacitance value is restored before the joint, it is determined that the metal wire cut in the middle is suspended and contacts the object to be joined. The wire bonding method according to claim 7, wherein the predetermined electrical signal is any one of an alternating current electrical signal and a direct current pulse signal. A wire bonding device includes: a first bonding processing unit that bonds a first bonding object and a metal wire at a first bonding point of the wire bonding; and a wire arc forming processing portion that causes the metal wire side to be bonded from the first bonding The point is extended to the second joint to form a predetermined line arc and moves; a second bonding processing unit that bonds the second bonding object to the metal line at the second bonding point; and the unbonded monitoring portion, from before the first bonding process to after the second bonding During the period, a predetermined electrical signal is continuously applied between the metal wire held by the capillary and the bonding platform holding the first bonding object and the second bonding object, and is monitored and judged based on the continuous response of the electrical signal. There is no change in the connection state of the above metal wires. The wire bonding device according to claim 9, wherein the unjoined monitoring unit monitors and determines the wire based on a change in a capacitance value between the metal wire and the bonding platform or a change in an electrical short circuit. There is no change in the connection status. The wire bonding device according to claim 10, wherein the unjoined monitoring unit sets a stable value of the continuous response in a period before the first joining process as a first reference value, based on the first reference value. And determining whether the connection state between the metal wire of the first joint and the first joint object is changed, and setting a stable value of the continuous response when the first joining process is completed as a second reference value, based on The second reference value is used to determine whether or not the connection state of the metal wire in the line arc forming process period is changed, and the stable value of the continuous response in the line arc forming process period is set to a third reference value, based on the third The reference value determines whether the connection state between the metal wire and the second bonding object of the second bonding point is changed, and the stable value of the continuous response when the second bonding process is completed is The four reference values determine whether or not the connection state of the metal wire in the period from the second junction to the completion of the cutting process of the metal wire is changed based on the fourth reference value. The wire bonding device according to claim 11, wherein the non-joining monitoring unit is a DC voltage signal having a potential of the bonding platform set to a ground voltage value and having a voltage different from the ground voltage value by a predetermined voltage value. The electric wire is applied to the metal wire as the predetermined electric current signal, and the first reference value is set to the predetermined voltage value, and the second reference value to the fourth reference value are used as the ground voltage value to determine the metal wire. There is no change in the above connection state. The wire bonding device according to claim 9, wherein the wire bonding of the first joint and the second joint is performed by a wedge bonding method or a ball bonding method. A wire bonding method includes: a first bonding processing step of bonding a first bonding object and a metal wire at a first bonding point of the wire bonding; and a wire arc forming processing step of causing one side of the metal wire to be bonded from the first bonding a point is extended to the second joint to form a predetermined line arc, and a second joining process is performed to bond the second object to be joined to the wire at the second joint; and the unjoining monitoring step Continuously applying between the metal wire held by the capillary and the bonding platform holding the first bonding object and the second bonding object, from before the first bonding process to after the second bonding The specified electrical signal is monitored and judged based on the continuous response of the electrical signal Whether the connection state of the metal wire changes.