JP2000077480A - Device and method for gang bonding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To import an effective ultrasonic vibrations to a bonding portion, regardless of the size of bonding load. SOLUTION: A plurality of inner leads provided on a wiring tape 16 is bonded in batch to a plurality of bonding pads provided on a semiconductor chip 8 one to one by exciting the pads and leads in a state, where the pads and leads are held between a bonding stage 9 and a bonding tool 10, by means of a bonding device provided with the bonding stage 9 on which the semiconductor chip 8 is placed, the bonding tool 10 which is faced opposite to the stage 9, a loading base 14 for applying a bonding load, an ultrasonic vibrator 11, and a horn 12. The upper end section of the bonding tool 10, which is the contacting point of the bonding tool 10 with the loading base 14 is constituted, so that the section becomes a node section for ultrasonic standing wave.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD OF THE INVENTION

The present invention relates to a gang bonding apparatus and a gang bonding method used in a semiconductor assembly technique, and more particularly, to a plurality of bonding pads on a semiconductor chip and a plurality of inner leads corresponding to each of these bonding pads. The present invention relates to an ultrasonic gang bonding apparatus and a gang bonding method capable of jointly bonding gangs.

[0002]

2. Description of the Related Art Conventionally, as a technique for bonding an inner lead to a bonding pad (surface electrode) on a semiconductor chip, ultrasonic vibration is transmitted to the inner lead to bond the bonding pad on the semiconductor chip to the inner pad. Ultrasonic inner lead bonding technology is known, in which the oxide film on the metal surface is removed by friction between the leads and both are brought into contact with each other, and the frictional heat generated between the bonding pad and the inner leads further strengthens the bonding. Have been.

Japanese Patent Laid-Open No. 5-136205 discloses that a plurality of bonding pads on a semiconductor chip and a plurality of inner leads corresponding to each of these bonding pads can be collectively bonded. A so-called carrier tape type ultrasonic gang bonding apparatus is disclosed. In this carrier tape type ultrasonic gang bonding technology, as shown in FIG.
First, a semiconductor chip 2 is fixed on a bonding stage 1 having a built-in heater by a method such as vacuum suction, and is heated to a predetermined temperature. Next, a plurality of bonding pads 3, 3,... On the semiconductor chip 2 and a TCP (Tape Carrier) corresponding to each of these bonding pads 3, 3,.
The plurality of inner leads 5, 5,... Provided on the package tape 4 are sandwiched between the bonding tool 6 and the bonding stage 1 in a state where the inner leads 5, 5,. In this state, the bonding tool 6 is vibrated by the ultrasonic vibrator 7, whereby the plurality of bonding pads 3, 3,... And the plurality of inner leads 5, 5,. .

In this bonding method, as described above, since ultrasonic waves are used together with thermal pressure welding, bonding can be performed at a lower temperature than in the case of only thermocompression bonding. There is an advantage that the degree can be increased.

[0005]

However, in the conventional device described in the above publication, the number of bonding pins has increased in recent years due to the increase in the number of bonding pins due to the increase in the density of semiconductor devices. Since an excessive bonding load is applied to the inner lead 24, the ultrasonic vibration is hindered, and a sufficient bonding effect cannot be obtained, or the ultrasonic vibrator cannot withstand the load and breaks. The inconvenience has arisen.

In addition, in the above-described conventional apparatus, the horn (acoustic tube) 28 is held in a cantilever manner. Therefore, when the bonding load on the multi-pin semiconductor chip is increased, the horn 28 is bent, and In addition, the parallelism of the press contact surface between the bonding tool 25 and the bonding stage 21 is deviated, and as a result, there is a problem that uniform bonding is impaired.

[0007] The present invention has been made in view of the above circumstances, and regardless of the magnitude of a bonding load applied to a bonding site via a bonding tool.
It is an object of the present invention to provide a gang bonding apparatus and a gang bonding method which can always provide an effective ultrasonic vibration to a bonding site.

[0008]

According to a first aspect of the present invention, there is provided a semiconductor device comprising: a bonding stage for mounting a semiconductor chip; and a bar disposed opposite to the bonding stage. A bonding tool, a pressing means for applying a bonding load to the bonding tool, and an ultrasonic vibrating means for vibrating the bonding tool, wherein a plurality of bonding tools are provided on the semiconductor chip. The ultrasonic vibrating means is driven while the pad and a plurality of inner leads prepared corresponding to each of the bonding pads are sandwiched between the bonding stage and the bonding tool. By vibrating the tool, the above-mentioned plural bonding pads and plural inner leads are collectively joined one to one. That relates to gang bonding apparatus, an ultrasonic pressure Futoki, at the site of the bonding tool comprising a node portion of the ultrasonic standing wave is characterized by being configured to the pressure means it is in contact.

According to a second aspect of the present invention, there is provided the gang bonding apparatus according to the first aspect, wherein an upper end portion of the bonding tool becomes a node of the ultrasonic standing wave when ultrasonic vibration is applied. The above-mentioned pressurizing means is configured to be in contact with the node from above at the node.

According to a third aspect of the present invention, there is provided the gang bonding apparatus according to the second aspect, wherein an upper end portion of the bonding tool has a tapered shape.

According to a fourth aspect of the present invention, there is provided the gang bonding apparatus according to the first aspect, wherein the ultrasonic vibrating means includes an ultrasonic vibrator and an ultrasonic vibrator radiated from the ultrasonic vibrator. And a horn that is added to the above bonding tool with an appropriate degree of adjustment.

According to a fifth aspect of the present invention, there is provided the gang bonding apparatus according to the fourth aspect, wherein the horn comprises:
At one end where the joint portion with the ultrasonic transducer is located, it is attached and fixed to the pressurizing means, and at the other end, it is attached and fixed to the bonding tool.

According to a sixth aspect of the present invention, there is provided a bonding stage on which a semiconductor chip is mounted, a bonding tool made of a bar disposed to face the bonding stage, and a bonding load applied to the bonding tool. A plurality of bonding pads disposed on the semiconductor chip by using a bonding apparatus including a pressing unit for applying the pressure and an ultrasonic vibrating unit for vibrating the bonding tool; A plurality of inner leads prepared corresponding to each of the above, in the state of being pressed between the bonding stage and the bonding tool, by driving the ultrasonic vibration means,
The present invention relates to a gang bonding method in which the bonding tool is vibrated and the plurality of bonding pads and the plurality of inner leads are collectively bonded in a one-to-one manner, and serves as a node of an ultrasonic standing wave during ultrasonic vibration. The pressure means is brought into contact with the bonding tool at a site thereof.

According to a seventh aspect of the present invention, there is provided the gang bonding method according to the sixth aspect, wherein an upper end of the bonding tool is a node of the ultrasonic standing wave when ultrasonic vibration is applied. The pressure means is brought into contact with the node from above at the node.

Further, the invention according to claim 8 relates to the gang bonding method according to claim 7, wherein an upper end portion of the bonding tool is tapered.

[0016]

The structure of the present invention focuses on the distribution of ultrasonic waves that vibrate the bonding tool (standing wave mode), and pressurizes by contacting the portion where the nodes of the ultrasonic waves are formed. Therefore, with the increase in the number of bonding pins of the semiconductor device, even if a large bonding load is applied by the pressing means, the ultrasonic vibrator is not damaged and the vibration of the bonding tool is not hindered. . In such a configuration, it is common that the pressing unit presses the upper end of the bonding tool from above, so that a node of the ultrasonic standing wave is generated at the upper end of the bonding tool. It is preferable to determine the length, shape, horn mounting position, ultrasonic frequency, and the like. Also, if the upper end of the bonding tool has a tapered shape such as a hemisphere, a cone, a pyramid, a truncated cone, or a truncated pyramid, the consumption of ultrasonic energy at the nodes can be reduced, which is more effective. is there.

In the above-mentioned conventional apparatus, the horn is held in a cantilever manner. According to the fifth aspect of the present invention, one end of the horn is fixed to the pressing means, and the other end is bonded to the bonding means. Since it is a so-called two-sided holding structure that is attached and fixed to the tool, the horn does not bend even if the bonding load increases, and therefore, the parallelism of the press-contact surface between the bonding tool and the bonding stage is reduced. Since no displacement occurs, uniform joining can be maintained.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. The description will be specifically made using an embodiment. FIG. 1 is a schematic sectional view showing a main part of a gang bonding apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic sectional view showing an operation state thereof. The gang bonding apparatus of this example is a CSP (Chip Sca
1 relates to an ultrasonic gang bonding apparatus for collectively joining a plurality of inner leads provided on a tape for semiconductor package and a plurality of bonding pads on a semiconductor chip, as shown in FIG. Stage 9 for bonding, and a bonding tool 1 disposed above and opposed to the bonding stage 9.
0, an ultrasonic vibrator 11 such as a ceramic piezoelectric element, a horn (acoustic tube) 12 integrated with the ultrasonic vibrator 11 and applying ultrasonic vibration to the bonding tool 10 at an appropriate level; And a pressing mechanism 13 for applying a pressing force from above vertically.

The bonding stage 9 has a vacuum suction device (not shown) for mounting and holding the semiconductor chip 8, and also has a built-in heater for heating the semiconductor chip 8 to a predetermined temperature. The pressing mechanism 13 includes a load base 14 on a flat plate, Z-axis linear shaft mechanisms 15 and 15 that support the load base 14 from above and make the load base 14 freely movable in the vertical direction. (Not shown). The bonding tool 10 is made of a titanium alloy rod having a length of 70 to 80 mm and a circular cross section (diameter: 8 mm). The lower end face opposed to the bonding stage 9 is a flat face, but the upper end is a hemisphere. It is configured such that the top contacts the lower surface of the load base 14 of the pressing mechanism 13. The horn 12 is attached and fixed to the lower surface of the load base 14 of the pressurizing mechanism 13 with a screw or the like on the left end side (root portion) in the drawing where the joining portion with the ultrasonic transducer 11 is located, while the right end side in the drawing. At this point, a two-sided holding structure is provided by attaching and fixing to the bonding tool 9 with screws or the like.

Here, during the ultrasonic vibration, the length and shape of the bonding tool 10, the mounting position of the horn 12, The ultrasonic frequency and the like have been determined. A wiring tape (CSP tape) 16 wound around a pay-out reel and a take-up reel (not shown) is interposed between the bonding stage 9 and the bonding tool 10.

Next, the operation of the gang bonding apparatus having the above configuration will be described with reference to FIG. First, the semiconductor chip 8 is placed on the bonding stage 9,
The semiconductor chip 8 is heated to a predetermined temperature while being fixed by vacuum suction and energizing a heater built in the bonding stage 9. Next, a take-up reel (not shown) is turned to convey the wiring tape 16 onto the semiconductor chip 8,
The plurality of bonding pads provided on the semiconductor chip 8 and the plurality of inner leads provided on the wiring tape 16 corresponding to each of these bonding pads are one in one.
Position so that they overlap one to one.

Next, the pressurizing mechanism 13 is driven to lower the bonding tool 10, and the overlapped portion (site to be bonded) between the wiring tape 16 and the semiconductor chip 8 is pressed between the bonding stage 9 and the bonding tool 10. . When the pressure applied to the overlapping portion (planned joining portion) between the wiring tape 16 and the semiconductor chip 8 reaches a desired bonding load, the overlapping portion (planned joining portion) is maintained in this pressurized state. The operation of the pressure mechanism 13 is stopped. In this state, desired high-frequency power is applied to the ultrasonic transducer 11, and the emitted ultrasonic vibration is transmitted to the bonding tool 10 via the horn 4. Thus, bonding tool 1
After 0 is excited for a predetermined time, the ultrasonic vibration is stopped, the load base 14 is raised, and the joining is completed.

As described above, according to the configuration of this example, the bonding load is applied from the upper portion of the bonding tool 10, but the upper end portion of the bonding tool 10 (that is, the contact point between the bonding tool 10 and the load base 14). However, since it is designed to be at the position of the node of the ultrasonic vibration, even when the bonding load is large, the vibration of the bonding tool 10 is not hindered, and the overlapping portion (the semiconductor chip 8 and the wiring tape 16) is formed. (Joining site). Also, the upper end of the bonding tool 10 is
The hemispherical tapered shape can reduce the consumption of ultrasonic energy at the ultrasonic node. In addition, since the horn 12 is held at both ends, even if the bonding load becomes large, the horn 12 does not bend, so that the bonding tool 10 and the bonding stage 9 are not bent.
There is no deviation in the degree of parallelism of the press contact surface between the two, and uniform joining can be maintained.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and there are design changes that do not depart from the gist of the present invention. Is also included in the present invention. For example, in the above-described embodiment, a titanium alloy rod having a circular cross section is used as the bonding tool 10, but the cross sectional shape is not limited to a circle, but may be a square, a polygon, or another shape. Further, the material is not limited to the titanium alloy. Further, in the above-described embodiment, the upper end portion of the bonding tool 10 has a hemispherical shape. However, the present invention is not limited to this. Almost the same effects as described in the example can be obtained. Further, the contact point between the bonding tool 10 and the pressing mechanism 13 does not necessarily have to be at the upper end of the bonding tool 10, but even in that case, the bonding becomes a node of the ultrasonic standing wave during the ultrasonic vibration. At the position of the tool 10, the pressing mechanism 1
By making contact with 3, it is possible to obtain substantially the same effects as described in the above embodiment.

As described above, according to the structure of the present invention, since the pressing means comes into contact with the portion where the node of the ultrasonic wave is formed and pressurizes, the joining of the semiconductor device is achieved. As the number of pins increases, even if a large bonding load is applied by the pressurizing means, the ultrasonic vibrator is not damaged and the vibration of the bonding tool is not hindered. In such a configuration, it is common that the pressing unit presses the upper end of the bonding tool from above, so that a node of the ultrasonic standing wave is generated at the upper end of the bonding tool. It is preferable to determine the length, shape, horn mounting position, ultrasonic frequency, and the like. Also, if the upper end of the bonding tool has a tapered shape such as a hemisphere, a cone, a pyramid, a truncated cone, or a truncated pyramid, the consumption of ultrasonic energy at the nodes can be reduced, which is more effective. is there.

Further, in the above-mentioned conventional apparatus, the horn is held in a cantilever manner. In the invention according to the fifth aspect, one end is attached and fixed to the pressing means, and the other end is bonded to the pressing means. Since it is a so-called two-sided holding structure that is attached and fixed to the tool, the horn does not bend even if the bonding load increases, and therefore, the parallelism of the press-contact surface between the bonding tool and the bonding stage is reduced. Since no displacement occurs, uniform joining can be maintained.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a main configuration of a gang bonding apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view showing an operation state of the embodiment.

FIG. 3 is a schematic view of a main part of a conventional gang bonding apparatus.

[Explanation of symbols]

 Reference Signs List 8 semiconductor chip 9 bonding stage 10 bonding tool 11 ultrasonic vibrator (ultrasonic vibrating means) 12 horn (part of ultrasonic vibrating means) 13 pressurizing mechanism (pressurizing means) 14 load base

Claims (8)

[Claims] 1. A bonding stage on which a semiconductor chip is mounted, a bonding tool made of a bar disposed to face the bonding stage, and pressing means for applying a bonding load to the bonding tool. Ultrasonic vibration means for vibrating the bonding tool; a plurality of bonding pads disposed on the semiconductor chip; and a plurality of inner leads prepared corresponding to each of the bonding pads. The ultrasonic vibrating means is driven while the pressure is held between the bonding stage and the bonding tool, and the bonding tool is vibrated so that the plurality of bonding pads and the plurality of inner leads are brought into contact with each other. This is a gang bonding machine that joins together one to one. At the site of the bonding tool to be knuckles, gang bonding apparatus, wherein said pressurizing means is configured in contact. 2. An apparatus according to claim 1, wherein an upper end portion of said bonding tool is a node of said ultrasonic standing wave during ultrasonic vibration, and said pressing means is in contact with said node from above. The gang bonding apparatus according to claim 1, wherein: 3. The gang bonding apparatus according to claim 2, wherein an upper end of the bonding tool has a tapered shape. 4. The ultrasonic vibrating means is formed by integrally joining an ultrasonic vibrator and a horn for applying ultrasonic vibration radiated from the ultrasonic vibrator to the bonding tool at an appropriate level. The gang bonding apparatus according to claim 1, wherein 5. The horn is attached and fixed to the pressurizing means at one end where a joining portion with the ultrasonic vibrator is located, and is attached and fixed to the bonding tool at the other end. The gang bonding apparatus according to claim 4, wherein: 6. A bonding stage for mounting a semiconductor chip, a bonding tool made of a bar disposed opposite to the bonding stage, and pressing means for applying a bonding load to the bonding tool. A plurality of bonding pads disposed on the semiconductor chip and a plurality of bonding pads provided on each of the bonding pads are prepared by using a bonding apparatus including an ultrasonic vibration unit for vibrating the bonding tool. With the plurality of inner leads held between the bonding stage and the bonding tool, the ultrasonic vibrating means is driven to vibrate the bonding tool, and the plurality of bonding pads and the plurality of bonding pads. A gang bonding method for joining the inner leads to each other in a one-to-one manner, A gang bonding method, wherein the pressurizing means is brought into contact with a portion of the bonding tool that becomes a node of an ultrasonic standing wave during ultrasonic vibration. 7. An upper end of the bonding tool is a node of the ultrasonic standing wave during ultrasonic vibration,
7. The gang bonding method according to claim 6, wherein said pressurizing means is brought into contact with said node from above. 8. The gang bonding method according to claim 7, wherein an upper end of the bonding tool has a tapered shape.