JPH0817876A - Wire bonder - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] To improve the contact detection accuracy by devising the structure of the detection means, or to improve the contact detection accuracy by optimizing the position of the contact detection point. [Structure] Arm 10 with built-in or attached ultrasonic transducer 11
In the wire bonder for contacting the tip of the bonding pad with the bonding pad on the semiconductor chip 15 and joining the bonding pad and the wire by thermal friction due to the vibration energy of the ultrasonic vibrator, the vibration during the period when the vibration energy is not generated is exceeded. The monitoring means 20 monitors the electrical output of the acoustic wave transducer, and the determining means 16 determines the contact between the tip of the arm and the bonding pad when the magnitude of the electrical output exceeds a predetermined value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire bonder used in an LSI assembling process, and more specifically, a fine metal wire (hereinafter referred to as "wire") between a bonding pad on a semiconductor chip and an external lead wire terminal. The present invention relates to a wire bonder that is connected with a wire, and more particularly, to improvement of a technique for detecting contact between a bonding pad and a bonding tool.

[0002]

2. Description of the Related Art FIG. 10 is a schematic view of a main part of a conventional wire bonder. 1 is a table, and this table 1
Is assembled from an XY table section with a slide shaft 1a standing upright, a rotary table having a chip mounting surface 1b, etc., but is shown as an integrated unit for convenience.

The slide block 2 attached to the slide shaft 1a is movable in the axial direction (vertical direction) of the slide shaft 1a.
An arm 3 is attached which allows a slight swing around a as a fulcrum. A transducer 4 incorporating an ultrasonic transducer is fixed to the tip of the arm 3, and a bonding tool (hereinafter sometimes simply referred to as “tool”) 5 is attached to the tip of the transducer 4.

In such a structure, the chip mounting surface 1
After placing a semiconductor chip (not shown) in b and aligning it in the XY directions by a separate control system, when the slide block 2 is lowered in the direction of arrow A, at some point the tip of the tool 5 is above the semiconductor chip. Contact the bonding pad of. The wire bonder detects this contact (detection means will be described later), stops the downward movement of the slide block 2, vibrates the ultrasonic vibrator of the transducer 4, and transmits the vibration energy to the tool 5. Since a wire (not shown) is sandwiched between the tool 5 and the bonding pad, the wire and the bonding pad are firmly bonded by the frictional heat generated by the vibration energy.

Here, in the case of the conventional wire bonder shown in FIG. 10, the detection means is realized by a mechanical on / off switch 6 provided on the slide block 2.
According to this, since the arm 3 before contact is tilted slightly downward by its own weight, as shown by a virtual line in FIG. 10, the switch 6 is in one state (for example, an ON state).
However, when it contacts the bonding pad, the arm 3
Swings upward (in the direction of arrow B) about the support shaft 2a as a fulcrum, so that the switch 6 is pushed by the body of the arm 3 and, as a result, the state of the switch 6 changes from one state (ON state) to the other state. It is switched to the (OFF state), and the ultrasonic transducer is activated at the time of this switching. The switch 6 may be a proximity sensor such as an eddy current detection type sensor.

[0006]

However, the above-mentioned conventional wire bonder has the following two problems in terms of the accuracy of contact detection by the detecting means (hereinafter referred to as "contact detection accuracy"). . The first problem is that when the switch 6 is mechanical (mechanical), contact wear due to repeated on / off cannot be avoided, and contact detection accuracy cannot be stabilized for a long period of time. Also, maintenance is required to check the condition of the contacts,
It means that the number of man-hours for that is increased. Furthermore, chattering associated with mechanical on / off is unavoidable. In particular, as wear progresses, chattering increases and detection delay increases, which is a disadvantage.

The second problem is that the detection position is far from the actual contact point. That is, no matter what type of switch is used, in order to detect the actual contact point (the tip of the tool 5), the dimensional error of the arm 3 and the transducer 4 and the like interposed between the switch position and the actual contact point and The attachment error cannot be ignored, and the influence of these errors makes it difficult to set the contact detection accuracy with high accuracy and the position correlation. Therefore, it is necessary to allow a certain amount of margin, but the margin setting causes a delay in detection time, which eventually leads to a decrease in bonding speed. [Purpose] A first object of the present invention is to improve the contact detection accuracy by devising the structure of the detection means.

A second object of the present invention is to improve the contact detection accuracy by optimizing the position of the contact detection point.

[0009]

According to the first aspect of the present invention,
In order to achieve the first object, the tip of an arm having an ultrasonic oscillator incorporated therein or attached thereto is brought into contact with a bonding pad on a semiconductor chip, and the bonding is performed by thermal friction caused by the vibration energy of the ultrasonic oscillator. In the wire bonder that joins between the pad and the wire,
Monitoring means for monitoring the electrical output of the ultrasonic transducer during the period when the vibration energy is not generated, and between the tip of the arm and the bonding pad when the magnitude of the electrical output exceeds a predetermined value. And a determination means for determining the contact.

According to a second aspect of the invention, the first and second aspects are provided.
In order to achieve the purpose of, the tip of the arm is brought into contact with the bonding pad on the semiconductor chip, by thermal friction or direct heating by vibration energy, in the wire bonder to bond between the bonding pad and the wire, First potential applying means for applying a first potential to the bonding pad, and second wire or arm having a weak potential difference with respect to the first potential that does not adversely affect the semiconductor chip. Second to give the electric potential of
Potential applying means, monitor means for monitoring a current flowing between the first potential and the second potential, and the tip of the arm and the bonding pad when the magnitude of the current exceeds a predetermined value. And a determination means for determining contact with

According to a third aspect of the present invention, the first and second aspects are provided.
In order to achieve the purpose of, the tip of the arm is brought into contact with the bonding pad on the semiconductor chip, by thermal friction or direct heating by vibration energy, in the wire bonder to bond between the bonding pad and the wire, Magnetizing means for magnetizing the tip of the arm, magnetism detecting means for detecting magnetism provided in the vicinity of the bonding pad, monitor means for monitoring the output of the magnetism detecting means for detecting the magnetism, and change of the output It is characterized by further comprising: a determination unit that determines a contact between the tip of the arm and the bonding pad when the amount exceeds a predetermined value.

The invention according to claim 4 is the above-mentioned first and second aspects.
In order to achieve the purpose of, the tip of the arm is brought into contact with the bonding pad on the semiconductor chip, by thermal friction or direct heating by vibration energy, in the wire bonder to bond between the bonding pad and the wire, Electric field generating means for generating an electric field provided near the tip of the arm, electric field detecting means for detecting an electric field provided near the bonding pad, and output of the electric field detecting means for detecting the electric field are monitored. It is characterized by comprising a monitoring means and a judging means for judging the contact between the tip of the arm and the bonding pad when the change amount of the output exceeds a predetermined value.

According to a fifth aspect of the invention, the first and second aspects are provided.
In order to achieve the purpose of, the tip of the arm is brought into contact with the bonding pad on the semiconductor chip, by thermal friction or direct heating by vibration energy, in the wire bonder to bond between the bonding pad and the wire, A pair of electrodes, each of which is provided near the tip of the arm and the bonding pad, or both of which are provided near the bonding pad, and a monitor unit that monitors the capacitance between the pair of electrodes. It is characterized by further comprising: a determination unit that determines contact between the tip of the arm and the bonding pad when the amount of change in the capacitance exceeds a predetermined value.

The invention according to claim 6 is characterized in that, in the invention according to claim 5, the tip of the arm is magnetized. In order to achieve the first and second objects, the invention according to claim 7 brings the tip of the arm into contact with a bonding pad on the semiconductor chip, and heat-friction by vibration energy or direct heating In a wire bonder for joining between a bonding pad and a wire, a light emitting element and a light receiving element provided in the vicinity of the bonding pad, and monitor means for monitoring the output of the light receiving element,
It is characterized by further comprising: a determination unit that determines contact between the tip of the arm and the bonding pad when the output exceeds a predetermined value.

The invention according to claim 8 is characterized in that, in the invention according to claim 8, the tip of the arm is mirror-finished or a member for reflecting light is attached to the tip. In order to achieve the first and second objects, the invention according to claim 9 brings the tip of the arm into contact with a bonding pad on a semiconductor chip, and heat-friction by vibration energy or direct heating, In a wire bonder for joining a bonding pad and a wire, a piezoelectric element that constitutes the tip of the arm itself or a part of the tip, a monitoring unit that monitors the voltage across the piezoelectric element, and the voltage between both ends is predetermined. It is characterized by further comprising a determination means for determining contact between the tip of the arm and the bonding pad when the value exceeds the value.

The invention as defined in claim 10 is based on claim 3, 4,
In the invention described in 5 or 7, two magnetic detecting means for detecting magnetism, an electric field detecting means for detecting an electric field, a pair of electrodes or a light receiving element are arranged along the moving direction of the arm, and each of the array elements is arranged. Part of the detection sensitivity range of is polymerized.

[0017]

According to the first aspect of the invention, the principle of generating a voltage when the ultrasonic vibrator is vibrated in the opposite direction is applied, and the ultrasonic vibrator is diverted to the contact detection means. Therefore, a non-mechanical detection means is realized, contact wear is avoided, and good contact detection accuracy is maintained for a long period of time.

According to the second aspect of the invention, the weak current flowing into the bonding pad through the wire is monitored. Therefore, since the contact between the wire and the bonding pad is directly detected, good contact detection accuracy with less error can be obtained. In the invention according to claims 3 to 8, contact detection is performed based on a change in magnetism, a change in electric field, a change in capacitance, or a change in light amount. Therefore, in any case, non-mechanical non-contact contact detection means is realized, contact wear is avoided, and good contact detection accuracy is maintained for a long period of time. Since the inventions according to claims 3 to 8 indirectly detect the contact position, it is possible to obtain a higher level by not only looking at the change in the output signal but also looking at the derivative of the output signal. It is preferable because contact detection can be performed with high accuracy.

According to the ninth aspect of the invention, contact detection is performed based on the voltage across the piezoelectric element. Therefore, non-mechanical non-contact contact detection means is realized, contact wear is avoided, and good contact detection accuracy can be maintained for a long period of time. According to a tenth aspect of the present invention, two outputs taken out from the two sensors (magnetic detection means for detecting magnetism, electric field detection means for detecting an electric field, a pair of electrodes or a light receiving element) are added, or an AND logic is used. As a result, a sharp detection characteristic with a narrower detection width can be obtained as compared with the case where only one sensor is used. Therefore, the contact detection accuracy can be further improved.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. (1) FIG. 1 is a diagram showing an embodiment of the wire bonder according to the invention described in claim 1, which is an application example to a wire bonder adopting an ultrasonic bonding method.

In FIG. 1, reference numeral 10 is an arm corresponding to the arm 3 and the transducer 4 of the conventional example (see FIG. 10), and an ultrasonic transducer 11 is built in this arm 10. The ultrasonic transducer 11 is not limited to the built-in one, but may be attached to the arm 10, for example. The point is that it should be integrated with the arm 10. Arm 10
It can be moved up and down along the slide shaft 12, and can be slightly swung about a support shaft 13 as a fulcrum, and a tool 14 is integrally attached to the tip thereof.

Reference numeral 15 denotes a semiconductor chip to be bonded, and a bonding pad (not shown) is formed on the surface of the semiconductor chip 15. When the arm 10 is lowered along the slide shaft 12, the contact between the tool 14 and the bonding pad is detected, and the ultrasonic vibrator 11 is activated, the vibration energy of the ultrasonic vibrator 11 is transmitted from the arm 10 via the tool 14. Are transmitted to a wire (not shown) sandwiched between the tool 14 and the bonding pad.
As a result, frictional heat is generated between the wire and the bonding pad, and the wire and the bonding pad are firmly bonded.

Here, the ultrasonic transducer 11 is started by applying a predetermined AC voltage, and the predetermined AC voltage responds to the instruction signal Sa from the control circuit 16,
It is made by the ultrasonic oscillator circuit 17. As the ultrasonic oscillator 11, for example, a crystal, a Langevin oscillator using a piezoelectric ceramic, a concave piezoelectric ceramic sound source, or the like is used, but any of them is a ferroelectric crystal or a piezoelectric ceramic (hereinafter referred to as “piezoelectric body”). When a voltage is applied to the outside of the body, it causes a mechanical deformation, the so-called piezoelectric effect.
s) is applied.

The piezoelectric effect is also known as a phenomenon that when a piezoelectric body is mechanically deformed, a potential difference is generated across the piezoelectric body. In the present embodiment, this second phenomenon (from mechanical deformation to voltage) is used. Is used to detect the contact between the tool 14 and the bonding pad with high accuracy. That is, the wiring 19 branched from the wiring 18 connecting the ultrasonic oscillation circuit 17 and the ultrasonic transducer 11
Is connected to a voltage detection circuit 20 including a noise cut circuit and the like. The voltage detection circuit 20 responds to an instruction signal Sb from the control circuit 16 for a predetermined period (specifically, an ultrasonic transducer). During a period in which vibration energy is not generated by 11), the voltage across the ultrasonic transducer 11 as an electrical output is monitored, and the monitoring result M is converted to a digital value and transferred to the control circuit 16. In addition, the control circuit 16
When the size of the transferred monitor value M (the value corresponding to the voltage across the ultrasonic transducer 11) exceeds a predetermined value, the contact between the tool 14 and the bonding pad is determined and the arm 1
The falling of 0 is stopped, and an instruction signal Sa for instructing the generation of a predetermined AC voltage is output to the ultrasonic oscillator circuit 17.

The voltage detection circuit 20 corresponds to the monitor means for monitoring the electrical output of the ultrasonic transducer 11 in the period in which the vibration energy is not generated, and the control circuit 16 is also included in the items described in claim 1. Corresponds to a determination unit that determines contact between the tip of the arm 10 and the bonding pad when the electrical output exceeds a predetermined value. In such a configuration, when the tool 14 comes into contact with the bonding pad on the semiconductor chip 15, the ultrasonic transducer 1 is passed through the arm 10.
Although the mechanical stress is transmitted to No. 1, as described above, since the ultrasonic transducer 11 utilizes the piezoelectric effect, the second phenomenon of the piezoelectric effect, that is, the phenomenon of conversion from mechanical deformation to voltage is caused. , A potential difference is generated at both ends.

Therefore, this potential difference is detected by the voltage detection circuit 2
The monitoring result M is monitored at 0 and the monitoring result M is controlled by the control circuit 1.
When compared with the predetermined value in 6, it is possible to detect the contact between the tool 14 and the bonding pad without using a mechanical switch as in the conventional example. here,
Considering the contact detection accuracy of the present embodiment, in the present embodiment, mechanical stress is applied to the ultrasonic transducer 11 at a timing that completely coincides with the contact between the tool 14 and the bonding pad. This perfect matching is always constant and does not collapse without being affected by the length, shape, dimensional error, etc. of the arm 10. For example, even if the arm 10 has some dimensional error, the electrical output is taken out from the ultrasonic transducer 11 at exactly the same timing as the contact between the tool 14 and the bonding pad.

On the other hand, when the conventional switch is attached to the base of the arm 10, the on / off state of the switch does not always switch at the same timing as the contact between the tool 14 and the bonding pad. Not exclusively.
This is because the switching timing of the on / off state is determined by the length, shape, dimensions, etc. of the arm 10, and when these parameters deviate from the design values, the on / off timing depends on the degree of deviation (degree of error). Is faster or slower.

Therefore, from the comparison of these two, the arm 1
The electrical output can be taken out from the ultrasonic transducer 11 at exactly the same timing as the actual contact without being affected by the length, shape, size, etc. of 0, and the actual contact can be accurately performed based on the electrical output. The present embodiment is clearly superior to the prior art in that the detection can be performed well and stably, and it is possible to exert a special effect that the high detection accuracy can be stably maintained. Is. (2) FIG. 2 is a view showing an embodiment of the wire bonder according to the invention described in claim 2. In the present embodiment, elements common to FIG. 1 are assigned the same reference numerals as those in FIG.
Duplication of the explanation shall be avoided.

In FIG. 2, reference numeral 30 is a wire fed from a wire supply device (not shown).
The tip of 0 is currently in contact with a bonding pad (not shown) on the semiconductor chip 15. The bonding pad is, for example, a ground pad, and this pad is connected to one electrode 31a (negative electrode in FIG. 2) of the DC power supply 31 through the substrate of the semiconductor chip 15 and the ground. The other electrode 31b (the positive electrode in FIG. 2) of the DC power supply 31 is a contact 32a in the switch circuit 32,
The wire 30 is passed through the current detection circuit 33 and the wiring 34.
It is connected to the. The connection destination of the wiring 34 is not limited to the wire 30, and may be an arbitrary portion of the arm 10 including the tool 14. However, the arm 10 including the tool 14
To connect to any part of the tool 14 or arm 10
Must be made of a conductive material.

The interelectrode potential E of the DC power supply 31 is set to a weak value that does not adversely affect the elements formed on the semiconductor chip 15 such as damage. This DC power supply 31
Of the matters described in claim 2, it corresponds to a first potential applying means for applying a first potential (ground potential in FIG. 2) to the bonding pad, and also corresponds to the wire 30 or the arm 1.
0 corresponds to a second potential applying means for applying a second potential (potential difference E in FIG. 2) having a weak potential difference that does not adversely affect the semiconductor chip 15 with respect to the first potential. is there.

The current detection circuit 33 is a closed circuit formed when the wire 30 and the bonding pad are in contact with each other, that is, the positive electrode 31b of the DC power supply 31 and the contact 32.
a, the current detection circuit 33, the wiring 34, the wire 30, the semiconductor chip 15 and the negative electrode 31a of the DC power supply 31 are used to monitor the current i flowing through the closed circuit, and the monitoring result Mb is transferred to the control circuit 36. It Control circuit 36
Compares the monitoring result Mb with a predetermined value, and judges contact between the tip of the wire 30 and the bonding pad when the result exceeds the predetermined value.
Of the matters described, it corresponds to a monitor means for monitoring the current i flowing between the first potential and the second potential, and the control circuit 36 controls the magnitude of the current i to exceed a predetermined value. It corresponds to a determination means for determining contact between the tip of the arm 10 (more precisely, the tip of the wire 30) and the bonding pad when the arm 10 is exposed.

In this structure, when the arm 10 is lowered, the tip of the wire 30 and the bonding pad come into contact with each other at a certain point, and the DC power source 31 is used as the power source. A closed circuit is formed. Then, the contact is determined when the magnitude of the current i in the closed circuit exceeds a predetermined value. Here, the predetermined value is a value that is as low as possible to secure a noise margin, and in reality, the contact determination is performed at the same time when the closed circuit is formed.

Therefore, according to the present embodiment, the closed circuit is formed at the actual contact timing, and the closed circuit is not affected by the length, shape or size of the arm 10 at all, so that the accuracy of contact detection can be improved. Moreover, this can be stably maintained for a long period of time. In this embodiment, the wire bonder by the ultrasonic bonding method is taken as an example, but since the ultrasonic vibrator 11 is not an essential requirement in this embodiment, it can be applied to the wire bonder by the heating method. (3) FIG. 3 is a view showing an embodiment of the wire bonder according to the invention of claim 3. In the present embodiment, elements common to those of FIG. 1 or 2 are designated by the same reference numerals as those of FIG. 1 or 2, and their description will not be repeated.

In FIG. 3, reference numeral 40 is a tool. The tool 40 is similar to the above-described embodiments in terms of its shape, but differs greatly in that it is magnetized. That is, the tool 40 is magnetized by itself or by other means such as an electromagnet, and corresponds to the magnetizing means for magnetizing the tip of the arm 10 among the matters described in claim 3.

A magnetic sensor 41 using a small coil or a Hall element is arranged near the bonding pad (not shown) on the semiconductor chip 15. The output of the magnetic sensor 41 includes a noise cut circuit. It is monitored by the signal processing circuit 42, and the monitoring result Mc is the control circuit 4
3 is transferred. The control circuit 43 calculates the amount of change in the output of the magnetic sensor 41 based on the monitor result Mc, and when the amount of change exceeds a predetermined value, it is between the tip of the arm 10 (that is, the tool 40) and the bonding pad. Determine the contact.

The magnetic sensor 41 corresponds to a magnetic detecting means for detecting magnetism provided in the vicinity of the bonding pad, among the matters described in claim 3, and the signal processing circuit 42.
Corresponds to monitoring means for monitoring the output of the magnetic sensor 41, and the control circuit 43 causes the tip of the arm 10 (that is, the tool 40) and the bonding pad when the amount of change in the output of the magnetic sensor 41 exceeds a predetermined value. It corresponds to the determination means for determining the contact between the two.

In such a configuration, before the arm 10 is lowered, the distance between the tool 40 and the magnetic sensor 41 is large, so the output of the magnetic sensor 41 is almost zero or a small value. As 10 is lowered, the output of the magnetic sensor 41 gradually increases, and reaches a peak when the tool 40 and the magnetic sensor 41 are closest to each other. Therefore, if the control circuit 43 detects this peak, it can be accurately determined that the tool 40 has reached the position of the magnetic sensor 41.

As described above, the technique of this embodiment is a technique for determining whether or not the tool has reached the position of the magnetic sensor 41, and as in each of the above-described embodiments, the tool 40 and the bonding pad are combined. It does not directly determine contact. However, if the magnetic sensor 41 is arranged as close as possible to the bonding pad, the magnetic sensor 41
Since the position of (1) corresponds to the position of the bonding pad, the contact between the tool 40 and the bonding pad can be determined in the same manner as in the above embodiments. Moreover, since the position of the magnetic sensor 41 is not affected by the length, shape or size of the arm 10 at all, the accuracy of contact detection can be improved, and this can be stably maintained for a long period of time.

In this embodiment, the wire bonder by the ultrasonic bonding method is taken as an example, but since the ultrasonic vibrator 11 is not an essential requirement in this embodiment, it can be applied to the wire bonder by the heating method. Is. Further, in this embodiment, the magnetic sensor 4 is provided near the bonding pad.
However, the magnetic sensor 41 may be replaced with an eddy current detection sensor. The eddy current sensor also outputs an electric signal according to a change in magnetism (correctly, a change in magnetic flux), and thus corresponds to a magnetism detecting means. (4) FIG. 4 is a view showing an embodiment of the wire bonder according to the invention of claim 4. In the present embodiment, elements common to those of FIG. 1 or 2 are designated by the same reference numerals as those of FIG. 1 or 2, and their description will not be repeated.

In FIG. 4, reference numeral 50 is an electrode provided in the vicinity of the tool (at a position for shielding the electric field) 14.
A predetermined voltage from the voltage application circuit 51 is applied to the electrode 50, and an electric field having a strength corresponding to the magnitude of the applied voltage is generated around the electrode 50. Therefore,
The electrode 50 corresponds to the arm 1 of the items described in claim 4.
It corresponds to an electric field generating means for generating an electric field provided near the tip of 0 (correctly, the tool 14).

On the other hand, an electric field sensor 52 is provided near the bonding pad (not shown) on the semiconductor chip 15 so as to face the electrode 50. The electric field sensor 52 is defined in claim 4. Of each matter,
It corresponds to an electric field detecting means for detecting an electric field provided in the vicinity of the bonding pad. The output of the electric field sensor 52, that is, the signal that increases or decreases according to the distance from the electrode 50 is converted into a voltage value, for example, by the electric field detection circuit 53,
It is transferred to the control circuit 55 via the signal processing circuit 54 including a noise cut circuit.

Electric field detection circuit 53 and signal processing circuit 54
Is for monitoring the output of the electric field sensor 52 and corresponds to the monitoring means in each item of claim 4. The control circuit 55 determines contact between the tip of the arm 10 (correctly, the tool 14) and the bonding pad when the output of the electric field sensor 52 exceeds a predetermined value. It corresponds to the determination means of each item.

According to such a configuration, the output of the electric field sensor 52 changes to the increasing side as the tool 14 descends. Therefore, by optimizing the judgment reference value (predetermined value) in the control means 55, The contact between the tool 14 and the bonding pad can be determined with high accuracy. Moreover, the output of the electric field sensor 52 is affected only by the distance between the electrode 50 and the electric field sensor 52, and is not affected by the length, shape, size, or the like of the arm 10 at all, so that high contact detection accuracy is maintained for a long time. It can be maintained stable.

In this embodiment, the wire bonder by the ultrasonic bonding method is taken as an example, but since the ultrasonic vibrator 11 is not an essential requirement in this embodiment, it can be applied to the wire bonder by the heating method. Is. (5) FIG. 5 is a view showing an embodiment of the wire bonder according to the invention described in claims 5 and 6. In the present embodiment, elements common to those of FIG. 1 or 2 are designated by the same reference numerals as those of FIG. 1 or 2, and their description will not be repeated.

In FIG. 5, reference numeral 60 denotes a first electrode provided near the tool (at a position where the capacitance is changed) 14 and 61 is provided near a bonding pad (not shown) on the semiconductor chip 15. The two electrodes 60 and 61 correspond to a pair of electrodes in the matters described in claim 5. First and second electrodes 6
An electrostatic capacitance detection circuit 62 is connected to 0 and 61, and the electrostatic capacitance detection circuit 62 detects the electrostatic capacitance between the counter electrodes from the impedance change between the counter electrodes with respect to a high frequency signal, for example. Applying the principle of
The capacitance between the first and second electrodes 60 and 61 is detected, and the detected value is transferred to the control circuit 64 via the signal processing circuit 63 including a noise cut circuit.

Capacitance detection circuit 62 and signal processing circuit 6
3 corresponds to a monitor means for monitoring the electrostatic capacitance between the pair of electrodes, among the matters described in claim 5, and the control circuit 64 causes the change amount of the electrostatic capacitance to exceed a predetermined value. Sometimes the tip of the arm 10 (to be exact, the tool 14) and the semiconductor chip 1
5 corresponds to a determination means for determining contact with the bonding pad (not shown).

According to this structure, as the tool 14 descends, the distance between the first electrode 60 and the second electrode 61 becomes shorter, and the output of the electrostatic capacitance detection circuit 62 changes to the increasing side. Therefore, by optimizing the determination reference value (predetermined value) in the control means 64, the contact between the tool 14 and the bonding pad can be determined with high accuracy. Moreover, the output of the capacitance detection circuit 62 is affected only by the distance between the first electrode 60 and the second electrode 61, and is not affected by the length, shape or size of the arm 10 at all. Therefore, high contact detection accuracy can be stably maintained for a long period of time.

In this embodiment, the wire bonder by the ultrasonic bonding method is taken as an example, but since the ultrasonic vibrator 11 is not an essential requirement in this embodiment, it can be applied to the wire bonder by the heating method. Is. In addition, in this embodiment, the first electrode 60 is arranged on the arm 10 side, and the second electrode 61 is arranged on the semiconductor chip 15 side.
Although the change in the distance between the two electrodes 60 and 61 due to the lowering of the arm 10 is taken out as the change in electrostatic capacitance, the present invention is not limited to this. For example, both the first and second electrodes 60 and 61 are arranged in the vicinity of the chip on the side of the semiconductor chip 15 and the first and second electrodes are moved when the tool 14 approaches.
Alternatively, the capacitance change between the electrodes 60 and 61 may be extracted. (6) FIG. 6 is a view showing an embodiment of the wire bonder according to the invention described in claims 7 and 8. In the present embodiment, elements common to those of FIG. 1 or 2 are designated by the same reference numerals as those of FIG. 1 or 2, and their description will not be repeated.

In FIG. 6, reference numeral 70 is a light emitting element, 71 is a light receiving element, and these light emitting element 70 and light receiving element 71 are provided.
Is arranged in the vicinity of a bonding pad (not shown) on the semiconductor chip 15. The light emitting element 70 is, for example, a laser diode, a light emitting diode, a lamp, or the like, and its optical axis 70a is oriented in a predetermined direction. The light receiving element 71 is, for example, a photodiode or the like, and its optical axis 71a is directed in a predetermined direction.

Optical axis 70a of light emitting element 70 and light receiving element 71
The point substantially intersecting with the optical axis 71a of the tool substantially coincides with a part of the surface of the tool 14 when the arm 10 is lowered, and an optical reflecting mirror 72 is attached to the surface of the tool 14. . Although the reflecting mirror 72 is shown as a separate member (for example, a small mirror) in the drawing, the present invention is not limited to this. For example, the surface of the tool 14 may be plated to be mirror-finished, or if the surface of the tool 14 is originally glossy, it may be used as it is without any special treatment.

Reference numeral 73 is a drive circuit for driving the light emitting element 70, and 74 is a light amount change detecting circuit for synchronizing the drive circuit 73 and detecting a change in the received light amount from the output of the light receiving element 71. The output of the circuit 74 is transferred to the control circuit 76 via the signal processing circuit 75 including a noise cut circuit. The light quantity change detection circuit 74 and the signal processing circuit 75 correspond to the monitor means for monitoring the output of the light receiving element 71, and the control circuit 76 has a predetermined output of the monitor means. It corresponds to a determining means for determining contact between the tip of the arm 10 (correctly, the tool 14) and a bonding pad (not shown) on the semiconductor chip 15 when the value exceeds the value.

According to this structure, the optical axis 70a of the light emitting element 70 and the light receiving element 71 are moved as the tool 14 descends.
When the reflecting mirror 72 is located at a point where it intersects with the optical axis 71a, the light from the light emitting element 70 is reflected by the reflecting mirror 72, and most of the reflected light is received by the light receiving element 71. Therefore, since the output of the light amount change detection circuit 74 changes to the increasing side, the contact between the tool 14 and the bonding pad can be determined with high accuracy by optimizing the determination reference value (predetermined value) in the control means 76. can do. Moreover,
The output of the light amount change detection circuit 74 is exclusively the light emitting element 70.
And the light receiving element 71 and the reflecting mirror 72 (in other words, the tool 1
Since it is only affected by the positional relationship with 4) and is not affected by the length, shape or size of the arm 10 at all, high contact detection accuracy can be stably maintained for a long period of time.

In this embodiment, the wire bonder by the ultrasonic bonding method is taken as an example, but since the ultrasonic vibrator 11 is not an essential requirement in this embodiment, it can be applied to the wire bonder by the heating method. Is. Further, it is desirable that the light emitting element 70 is driven by modulation at a high frequency by the drive circuit 74. Since the modulated light from the light emitting element 70 undergoes the second modulation at a low frequency according to the descending speed of the reflecting mirror 72, the light quantity detection circuit 74 may detect the turbulence of the light due to the second modulation. Because.

It is also preferable to form micro-cut fine grooves on the surface of the reflecting mirror 72 or the tool 14. This is because the second modulation becomes deeper, the way the light is disturbed becomes stronger, and the detection performance is improved. (7) FIG. 7 is a view showing an embodiment of the wire bonder according to the invention of claim 9. In the present embodiment, elements common to those of FIG. 1 or 2 are designated by the same reference numerals as those of FIG. 1 or 2, and their description will not be repeated.

In FIG. 7, reference numeral 80 is a piezoelectric element attached to the tip of the tool 81. The piezoelectric element 80 has a so-called piezoelectric effect that a potential difference is generated at both ends when a mechanical stress is applied to a piezoelectric body such as a ferroelectric crystal or a piezoelectric ceramic.
The voltage extracted from the piezoelectric element 80 is subjected to processing such as amplification by the voltage change detection circuit 82, and then passes through a signal processing circuit 83 including a noise cut circuit and then a control circuit 84. Transferred to.

The control circuit 84 controls the tip of the arm 10 (correctly, the piezoelectric element 80 attached to the tip of the tool 81) when the voltage taken out from the piezoelectric element 80 exceeds a predetermined value.
The contact between the contact pad and the bonding pad on the semiconductor chip 15 is determined. The voltage change detection circuit 82 and the signal processing circuit 83 correspond to the monitoring means for monitoring the voltage across the piezoelectric element 80, and the control circuit 84 controls the voltage across the piezoelectric element 80. Corresponds to a determining means for determining contact between the tip of the arm 10 and the bonding pad when exceeds a predetermined value.

According to such a structure, when the piezoelectric element 80 and the bonding pad come into contact with each other as the tool 81 descends, the contact force of the piezoelectric element 80 causes the voltage across the piezoelectric element 80 to increase. Therefore, when this change exceeds the predetermined value, the control circuit 84 determines the contact between the tip of the arm 10 and the bonding pad, so that the determination reference value (predetermined value) in the control means 84 is optimized. As a result, the contact between the tool 81 and the bonding pad can be determined with high accuracy. Moreover, the output voltage of the piezoelectric element 80 changes depending only on the actual contact operation, and is not affected by the length, shape, size, or the like of the arm 10 at all, so that high contact detection accuracy is stably maintained for a long period of time. can do.

In this embodiment, the wire bonder by the ultrasonic bonding method is taken as an example, but since the ultrasonic vibrator 11 is not an essential requirement in this embodiment, it can be applied to the wire bonder by the heating method. Is. Further, in this embodiment, the piezoelectric element 80 is attached to the tip of the tool 81, but the invention is not limited to this. For example, the tool itself may be formed of a piezoelectric element. (8) FIGS. 8 and 9 are views showing an embodiment of the wire bonder according to the invention described in claim 10. Of the above-mentioned embodiments, particularly, those using a magnetic sensor (see FIG. 3), electric field This is a preferable example when applied to a device utilizing a sensor (see FIG. 4), a device utilizing an electrostatic sensor (see FIG. 5) or a device utilizing an optical sensor (see FIG. 6).

The feature of this embodiment is that, in each of the above-described embodiments using each of the above sensors, the number of the sensors is two, and the arrangement direction of the two sensors is the arm 1
Matching with the movement direction of 0 is to partially overlap the detection sensitivity range of one of the two sensors and the detection sensitivity range of the other. The combined detection sensitivity characteristics of the two sensors that satisfy such characteristics are shown in FIG.

In FIG. 8, the vertical axis represents the sensor array direction (in other words, the moving direction of the arm 10), and the horizontal axis represents the detection sensitivity. The graph on the left end shows the raw detection sensitivities of the two sensors, the sensitivity of one sensor is shown by the characteristic line 90, and the sensitivity of the other sensor is shown by the characteristic line 91. By adjusting the sensor interval, the two characteristic lines 90 and 91 partially overlap each other.

Here, when two sensor outputs are added (for example, by analog AND logic), the added output is shown as the graph in the center. The synthetic characteristic line 92 has a high peak corresponding to the center of polymerization of the two characteristic lines 90 and 91, and its width W (half-value width) is larger than either width Wa or Wb of the two characteristic lines 90 and 91. Is also narrow.

Therefore, the detection resolution in the moving direction of the arm 10 can be increased as compared with the case of only one sensor, and the contact between the tip of the arm 10 and the bonding pad can be detected more finely. In particular, the above-described embodiment using a magnetic sensor (see FIG. 3), the above-described embodiment using an electric field sensor (see FIG. 4),
When applied to the above-described embodiment utilizing an electrostatic sensor (see FIG. 5) or the above-described embodiment utilizing an optical sensor (see FIG. 6),
The detection performance can be improved, which is preferable.

The graph at the right end of FIG. 8 is a graph in which the synthetic characteristic line 92 and the threshold value 93 are compared and converted into a binary signal 94. According to this, by optimizing the size of the threshold value 93, only the apex portion of the combined characteristic line 92 can be taken out, and a detection signal having a width Wc narrower than the width W of the combined characteristic line 92 can be generated. Therefore, the resolution can be further improved.

The present embodiment is not limited to the one mainly based on such analog processing. For example, as shown in FIG. 9, after comparing two characteristic lines 90 and 91 with a predetermined threshold value 95 and converting them into two binary signals 96 and 97, AND of these two binary signals 96 and 97 is performed. You may take logic. Reference numeral 98 denotes an AND logic output signal, which can generate a high-resolution detection signal with a narrow width, as in FIG.

[0065]

According to the first aspect of the invention, the principle of generating a voltage when the ultrasonic vibrator is vibrated in the opposite direction is applied, and the ultrasonic vibrator is diverted to the contact detection means. Therefore, a non-mechanical detection means can be realized, contact wear and the like can be avoided, and good contact detection accuracy can be maintained for a long period of time.

According to the invention of claim 2, from the weak current flowing into the bonding pad through the wire,
The contact between the wire and the bonding pad can be directly detected. Therefore, it is possible to obtain good contact detection accuracy with little error. According to the inventions of claims 3 to 8, contact detection is performed based on a change in magnetism, a change in electric field, a change in capacitance, or a change in light quantity. Therefore, in any case, non-mechanical non-contact contact detection means can be realized, contact wear and the like can be avoided, and good contact detection accuracy can be maintained for a long period of time.

According to the invention of claim 9, contact detection is performed based on the voltage across the piezoelectric element. Therefore,
It is possible to realize a non-contact contact detection means that is not mechanical,
It is possible to avoid contact wear and the like and maintain good contact detection accuracy for a long period of time. According to the invention described in claim 10, two sensors (magnetic detection means for detecting magnetism, electric field detection means for detecting electric field, pair of electrodes or light receiving element)
The two outputs taken from are added or ANDed
By taking the logic, it is possible to obtain a sharp detection characteristic with a narrower detection width than in the case where only one sensor is used. Therefore, it is possible to reduce the detection delay and further improve the contact detection accuracy.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of an embodiment of the invention described in claim 1.

FIG. 2 is a conceptual diagram of an embodiment of the invention described in claim 2;

FIG. 3 is a conceptual diagram of an embodiment of the invention according to claim 3;

FIG. 4 is a conceptual diagram of an embodiment of the invention described in claim 4;

FIG. 5 is a conceptual diagram of an embodiment of the invention described in claims 5 and 6.

FIG. 6 is a conceptual diagram of an embodiment of the invention described in claims 7 and 8.

FIG. 7 is a conceptual diagram of an embodiment of the invention described in claim 9;

FIG. 8 is a characteristic diagram of an embodiment of the invention set forth in claim 10;

FIG. 9 is another characteristic diagram of the embodiment of the invention as set forth in claim 10;

FIG. 10 is a configuration diagram of a main part of a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10: Arm 11: Ultrasonic transducer 15: Semiconductor chip 16: Control circuit (judgment means) 20: Voltage detection circuit (monitor means) 30: Wire 31: DC power supply (first potential application means, second potential application) Means) 33: Current detection circuit (monitoring means) 36: Control circuit (determination means) 40: Tool (magnetization means) 41: Magnetic sensor (magnetism detection means) 42: Signal processing circuit (monitoring means) 43: Control circuit (determination) Means) 50: Electrode (electric field generating means) 52: Electric field sensor (electric field detecting means) 53: Electric field detecting circuit (monitoring means) 54: Signal processing circuit (monitoring means) 55: Control circuit (judging means) 60, 61: Electrodes (Pair of electrodes) 62: Capacitance detection circuit (monitoring means) 63: Signal processing circuit (monitoring means) 64: Control circuit (judging means) 70: Light emitting element 71: Light receiving element 74: Quantity change detection circuit (monitoring means) 75: Signal processing circuit (monitoring means) 76: Control circuit (determination means) 80: Piezoelectric element 82: Voltage change detection circuit (monitoring means) 83: Signal processing circuit (monitoring means) 84: Control circuit (determination means)

Claims (10)

[Claims] 1. A bonding pad on a semiconductor chip is brought into contact with a tip of an arm having an ultrasonic vibrator built-in or attached thereto, and thermal friction caused by vibration energy of the ultrasonic vibrator causes a gap between the bonding pad and the wire. In a wire bonder for joining, a monitoring means for monitoring the electrical output of the ultrasonic transducer during the period in which the vibration energy is not generated, and the tip of the arm when the magnitude of the electrical output exceeds a predetermined value. A wire bonder, comprising: a determination unit that determines contact between the bonding pad and the bonding pad. 2. A wire bonder in which the tip of an arm is brought into contact with a bonding pad on a semiconductor chip, and the bonding pad and the wire are bonded to each other by thermal friction by vibration energy or direct heating. And a second potential having a weak potential difference with respect to the first potential that does not adversely affect the semiconductor chip, to the wire or arm. Second electric potential applying means for giving, monitor means for monitoring a current flowing between the first electric potential and the second electric potential, and a tip of the arm when the magnitude of the electric current exceeds a predetermined value. A wire bonder, comprising: a determination unit that determines contact with the bonding pad. 3. A wire bonder in which a tip of an arm is brought into contact with a bonding pad on a semiconductor chip, and the bonding pad and the wire are joined by thermal friction or direct heating by vibration energy. A magnetizing means for magnetizing the tip, a magnetism detecting means for detecting magnetism provided in the vicinity of the bonding pad, a monitor means for monitoring the output of the magnetism detecting means for detecting the magnetism, and a change amount of the output is predetermined. A wire bonder comprising: a determining unit that determines contact between the tip of the arm and the bonding pad when the value exceeds a value. 4. A wire bonder in which the tip of an arm is brought into contact with a bonding pad on a semiconductor chip, and the bonding pad and the wire are joined by thermal friction or direct heating by vibration energy. Electric field generating means for generating an electric field provided near the tip, electric field detecting means for detecting the electric field provided near the bonding pad, and monitor means for monitoring the output of the electric field detecting means for detecting the electric field. A wire bonder comprising: a determination unit that determines contact between the tip of the arm and the bonding pad when the amount of change in the output exceeds a predetermined value. 5. A wire bonder in which a tip of an arm is brought into contact with a bonding pad on a semiconductor chip, and the bonding pad and the wire are bonded by thermal friction or direct heating by vibration energy, A pair of electrodes provided near the tip of the arm and the bonding pad, or both of which are provided near the bonding pad; monitoring means for monitoring the capacitance between the pair of electrodes; A wire bonder comprising: a determination unit that determines contact between the tip of the arm and the bonding pad when the amount of change in capacitance exceeds a predetermined value. 6. The wire bonder according to claim 5, wherein the tip of the arm is magnetized. 7. A wire bonder in which the tip of an arm is brought into contact with a bonding pad on a semiconductor chip, and the bonding pad and the wire are bonded to each other by thermal friction by vibration energy or direct heating. A light-emitting element and a light-receiving element, monitor means for monitoring the output of the light-receiving element, and contact between the tip of the arm and the bonding pad when the output exceeds a predetermined value. A wire bonder having a determining means for 8. The wire bonder according to claim 8, wherein the tip of the arm is mirror-finished or a member for reflecting light is attached to the tip. 9. A wire bonder in which the tip of the arm is brought into contact with a bonding pad on a semiconductor chip, and the bonding pad and the wire are joined by thermal friction or direct heating by vibration energy. A piezoelectric element forming the tip itself or a part of the tip, a monitor means for monitoring the voltage across the piezoelectric element, and a portion between the tip of the arm and the bonding pad when the voltage across the piezoelectric element exceeds a predetermined value. A wire bonder, which is provided with a determining means for determining the contact of the wire bonder. 10. A magnetic detection means for detecting magnetism, an electric field detection means for detecting an electric field, a pair of electrodes or a light-receiving element are arranged in two along the movement direction of the arm, and the detection sensitivity of each of the array elements. The wire bonder according to claim 3, 4, 5 or 7, wherein a part of the area is polymerized.