JPH1197493A - Bonding method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To widen an applicable range of bonding conditions, lessen a deformation amount of a bump, and bond at a narrow pitch by a method wherein a plurality of directions of ultrasonic vibrations are set and a deformation of a bump at a time of bonding is controlled. SOLUTION: If positioning of a SAW device D absorbed to a bonding tool 3 and a ceramic substrate B fixed onto a work stage 12 is ended, a vertical drive mechanism 11 is activated, and an ultrasonic horn 5 is moved downward together with the bonding tool 3 to start a pressure to a bump 2, and the ultrasonic horn 5 is applied to the bonding tool 3. If applying is ended and the ultrasonic horn 5 is elevated up to a specified position, a support arm 6 is rotated at 90 degrees together with the ultrasonic horn 5 and the bonding tool 3, and the bonding tool 3 is dropped and brought into contact with a back surface of a SAW device D to press and apply ultrasonic waves. Accordingly, the ultrasonic waves are applied in a different direction of the bump 2 to bond. It is possible to cope with a case where an electrode pad is fine-pitched.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonding method and a bonding apparatus for performing flip chip bonding in which thermocompression bonding is performed with a bonding tool while applying ultrasonic waves, in a technology for mounting devices such as semiconductors.

[0002]

2. Description of the Related Art Flip-chip bonding, in which a device electrode and a substrate electrode are bonded via bumps, has the advantages of a small mounting area and a short circuit wiring length, and is capable of high-density mounting and high-speed device mounting. Suitable for. In particular, those using gold ball bumps, whose formation process is relatively easy, have been widely put to practical use.

[0003] The outline of these processes will be described. Gold bumps are formed on electrodes of a device such as a SAW (Surface Acoustic Wave) device in advance by a ball bump method or the like. The device on which the gold bump is formed is sucked by a bonding tool attached to an ultrasonic horn with the bump forming surface facing down. On the other hand, a gold-plated ceramic substrate is placed on a bonding stage heated to about 200 ° C. After the device and the ceramic substrate are aligned by a camera or the like, the bonding tool descends and presses the device to the ceramic substrate to join the device. This pressurization is usually performed in two stages. That is, the burrs remaining on the bumps are removed in the first stage, and then the bumps are joined in the second stage. Therefore, the ultrasonic vibration is initially performed for 800 ms with a low output of about 0.5 W.
And then oscillate the ultrasonic vibration at a power of 2.0 W for 800 m.
s is applied. At this time, since the bonding tools operate in the same state, the ultrasonic vibrations are in the same direction.

[0006] Referring to FIG. 6, the vertical drive mechanism 23 is constituted by one side surface of the base 21 and a corresponding portion of the support arm 22. The support arm 22 supports the ultrasonic horn 24 at one end.

The ultrasonic horn 24 holds a bonding tool 25 at the tip. The bonding tool 25 has a pipe-like shape, and a suction hole 26 is provided at the center thereof so as to penetrate therethrough. A tip 27 forms a head 27 adapted to the shape of the suction chip. The SAW device D on which the bumps 28 are formed is attracted to the head 27. The other end of the bonding tool 25 is connected to a vacuum hose 29, and the other end of the vacuum hose 29 is connected to a pump (not shown).

On the other hand, a bonding stage 30 is disposed below the bonding tool 25. On the bonding stage 30, a ceramic substrate B on which an electrode 31 is formed is mounted.

[0007]

In flip-chip bonding, in which thermocompression bonding is performed in combination with ultrasonic waves, ultrasonic waves are applied to the bumps at a high output for a long time in order to secure bonding strength as compared with wire bonding or the like. There is a need. This not only lowers the manufacturing efficiency, but also when the ultrasonic wave is applied from the same direction (b), the bump deforms long and oval in the direction of the ultrasonic vibration before and after bonding as shown in FIG. I do. That is, since the allowable deformation amount of the bump with respect to the electrode size requires the major axis of the ellipse where the bump is deformed, the appropriate range of the bonding condition is extremely restricted. For this reason, it is difficult to cope with the case where the electrode pads have a fine pitch.

The present invention has been made under such circumstances, and by controlling the deformation of the bumps during bonding, it is possible to secure an appropriate range of bonding conditions in a wide range and reduce the amount of deformation of the bumps. The present invention provides a method and an apparatus capable of performing narrow-pitch bonding on a substrate.

[0009]

According to the present invention, a device having a substrate on which an electrode is formed and having a bump disposed on the electrode and an envelope on which the electrode is formed are connected to each other by the electrode over the bump. In a bonding method in which ultrasonic waves are applied and thermocompression-bonded to each other, there is a bonding method in which the directions of the ultrasonic waves are plural.

According to the present invention, the bonding is performed by applying an ultrasonic wave to a bonding tool.
A bonding method is performed each time the bonding tool is rotated by a predetermined angle by a rotating unit.

Further, according to the present invention, in the bonding method, the application of the ultrasonic wave to the bonding tool is performed every time the work stage is rotated by a predetermined angle.

According to the present invention, a work stage and a bonding tool provided to face the work stage and to which ultrasonic vibration is applied are formed on electrodes of a device adsorbed by the bonding tool. In a bonding apparatus in which ultrasonic waves are applied to a bonding tool by applying ultrasonic waves to electrodes of an envelope placed on a work stage and thermocompression bonding is performed, the application of ultrasonic waves to the bonding tool changes the vibration direction to change the vibration direction. Means for bonding.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a schematic diagram of a first embodiment of the present invention. A case where the present invention is applied to a SAW device D as in the prior art will be described. The external dimensions of the SAW device D are 2.0 × 2.0 × 0.4 (mm), and the electrode 1 is provided on the surface. Electrodes 1 are formed by sputtering 16 pieces of aluminum, and the size of each electrode 1 is 120 μm.
m and the thickness is 0.7 μm. Each of the electrodes 1 is formed with a gold ball bump 2 having a diameter of 70 μm and a height of 30 μm. As an envelope for mounting this device, a tungsten / nickel / gold electrode 4 was formed on a ceramic substrate B having an outer diameter of 3.0 × 3.0 × 0.5 (mm). The surface of the electrode was 0.4 μm by electroless plating.
Formed by gold plating.

An apparatus for flip-chip bonding these devices will be described. The ultrasonic horn 5 is supported by a support arm 6 and holds a bonding tool 3 at its tip. The bonding tool 3 is provided with a through hole 7 for sucking a device. A telescopic vacuum hose 14 is connected to the other end of the bonding tool, and the vacuum hose 14 is connected to a pump (not shown). The other end of the ultrasonic horn 5 is connected to an ultrasonic source (not shown). The other end of the support arm 6 is connected to a Θ-axis rotation motor 10, which is mounted on a bonding apparatus main body 18 via a vertical drive mechanism 11.

On the other hand, a work stage 12 is provided below the bonding tool 3, and a plate 13 for fixing the ceramic substrate B is provided on the work stage 12.

The operation of these structures will be described.
The AW device D and the ceramic substrate B fixed on the work stage 12 are aligned, and when the alignment is completed within a predetermined range, the vertical drive mechanism 11 operates to move the ultrasonic horn 5 downward. Accordingly, the bonding tool 3 also moves downward and starts pressing the bumps 2 of the device. When the pressing load reaches 1 kgf, the ultrasonic vibration source operates and the ultrasonic horn 5 applies a 1.5 W output to the bonding tool 3 for 200 ms. When the application is completed, the bonding tool 3 releases the suction of the device, and the vertical drive mechanism 11 operates to move up to a predetermined position. When the bonding tool 3 rises to a predetermined position.
Since the shaft rotation motor 10 operates and the support arm 6 rotates 90 degrees, the ultrasonic horn 5 and the bonding tool 3
Rotate 0 degrees. In this state, the vertical drive mechanism 11 operates again to lower the bonding tool 3 to lower the SAW device D.
And pressurized. When the pressing load reaches 1 kgf, ultrasonic vibration is applied for 200 ms at an output of 2.0 W, and when the application is completed, the vertical drive mechanism 11 operates to raise the bonding tool 3 and complete the bonding. Therefore,
As shown in FIG. 2, bonding could be performed in directions in which the directions (a, b) of the ultrasonic waves applied to the bumps 2 were different.

After bonding, the diameter of the pressure bonding bump 2 was measured, and the bonding strength (shear strength) was measured using the shear tool 14 as shown in FIG. The bump 2 is deformed while maintaining a substantially circular shape, and the crimping diameter of the bump 2 is 100 μm, and it can sufficiently cope with a □ 120 μm size pad.
A sufficient strength of 0 gf was obtained.

In the conventional method (the vibration direction of the applied ultrasonic wave is one direction), it is necessary to apply an ultrasonic output of 2.0 W for 500 ms in order to obtain the same bonding strength. And the major axis reached 120 μm, making it difficult to apply to a pad having a size of 120 μm.

FIG. 4 shows another embodiment, and the same reference numerals are given to the same components or components having the same functions as those of the previous embodiment. The ultrasonic horn 5 is fixed to the main body of the apparatus by a support arm 6, and holds the bonding tool 3 at the tip thereof. A telescopic vacuum hose 14 is connected to the other end of the bonding tool 3, and the vacuum hose 14 is connected to a pump (not shown). The other end of the ultrasonic horn 5 is connected to an ultrasonic source (not shown).

On the other hand, a work stage 12 is provided below the bonding tool 3, and a plate 13 for fixing a substrate is provided on the work stage 12. A rotation mechanism 15 using a motor as a power source is connected to a lower portion of the work stage 12.

The operation of these structures will be described.
The AW device D and the ceramic substrate B fixed on the work stage 12 are aligned, and when the alignment is completed within a predetermined range, the vertical drive mechanism 11 operates to move the ultrasonic horn 5 downward. Similarly, the bonding tool 3 also moves downward and starts pressing the bumps 2 of the device. When the pressing load reaches 1 kgf, the ultrasonic vibration source is activated and the ultrasonic horn 5 applies a 1.5 W output to the bonding tool 3 for 200 ms. When the application is completed, the bonding tool 3 releases the suction of the device, and the vertical drive mechanism 11 operates to move up to a predetermined position. When the bonding tool 3 is raised to a predetermined position, the motor rotates and the rotating mechanism 15 operates to move the work stage 12 to 90 degrees.
Rotate degrees. In this state, the vertical drive mechanism 11 operates again to lower the bonding tool 3 to contact the back surface of the SAW device D to apply pressure. When the pressing load reaches 1 kgf, ultrasonic vibration is applied for 200 ms at an output of 2.0 W, and when the application is completed, the vertical drive mechanism 11 operates to raise the bonding tool 3 and complete the bonding.

FIG. 5 is a plan view showing still another embodiment, in which a first bonding tool 3a is fixedly supported by a first ultrasonic horn 5a and a second bonding tool 3b.
Are supported by the second ultrasonic horn 5b. The first ultrasonic horn 5a and the second ultrasonic horn 5b are fixed to the apparatus main body 18 via the support arms 6a and 6b and the vertical drive mechanisms 11a and 11b in a state where the angle is shifted by 90 degrees. Other configurations are the same as those of the above-described embodiment.

On the other hand, a work stage 12 for mounting and fixing the substrate 2 is provided below the bonding tools 3a and 3b. The work stage 12 has an XY table structure and is set so as to be movable within the operation range of each of the bonding tools 3a and 3b.

The operation of these structures will be described. The position of the SAW device D sucked by the first bonding tool 3a and the position of the ceramic substrate B fixed on the work stage 12 are adjusted by a camera (not shown). When the positioning is completed within the range, the first ultrasonic horn 5
The ultrasonic horn 5a moves downward by operating the vertical drive mechanism a, so that the first bonding tool 3a also moves downward to start pressing the bumps 2 of the device.
When the pressing load reaches 1 kgf, the ultrasonic vibration source is activated, and the first ultrasonic horn 5a is connected to the first bonding tool 3.
a is applied for 200 ms with an output of 1.5 W. When the application is completed, the first bonding tool 3a releases the suction of the device, and the vertical drive mechanism operates to move up to a predetermined position. When the first bonding tool 3a rises to a predetermined position, the work stage 12 operates and moves to a predetermined position below the second bonding tool 3b. In this state, the vertical drive mechanism of the second ultrasonic horn 5b operates to lower the second bonding tool 3b to contact the back surface of the SAW device D and apply pressure. When the pressing load reaches 1 kgf, ultrasonic vibration is applied for 200 ms at an output of 2.0 W,
When the application is completed, the up-down drive mechanism operates to raise the bonding tool 3b, and the bonding is completed.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the application to the SAW device D has been described as an electronic component, but the invention is similarly applied to a semiconductor device. I can do it. A plated bump may be used for the bump. It goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0027]

As described above, in the present invention, in the bonding using ultrasonic waves, the application of ultrasonic waves to the bonding tool is performed a plurality of times while changing the vibration direction. Bonding without deformation. As a result, the suitable range of the bonding conditions can be widened, and it is possible to cope with the case where the electrode pads are finely pitched.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a model of an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing directions of ultrasonic vibration in the present invention.

FIG. 3 is an explanatory diagram of a measurement of a shear strength of a formed bump.

FIG. 4 is a configuration diagram showing another embodiment of the present invention.

FIG. 5 is a configuration diagram showing still another embodiment of the present invention.

FIG. 6 is a configuration diagram showing a conventional embodiment.

FIG. 7 is an explanatory view showing a shape of a bump in a conventional embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electrode (device) 2 ... Bump 3 ... Bonding tool 4 ... Electrode (substrate) 5 ... Ultrasonic horn 7 ... Capillary 8 ... Head 10 ... Shaft rotation motor 11 ... Vertical drive mechanism 12 ... Work stage 15 ... Rotation mechanism

Claims (5)

[Claims] 1. A device having a substrate on which electrodes are formed, and a device in which bumps are provided on the electrodes and an envelope on which electrodes are formed, are thermocompressed to each other by applying ultrasonic vibration to the electrodes via the bumps. Bonding method in which the direction of the ultrasonic vibration is plural. 2. The bonding method according to claim 1, wherein said bonding uses a bonding tool, and the application of ultrasonic waves to said tool is performed each time said bonding tool is rotated by a predetermined angle by a rotating means. . 3. The bonding method according to claim 1, wherein the bonding is performed using a bonding tool, and the application of the ultrasonic wave to the tool is performed every time the work stage is rotated by a predetermined angle. 4. The bonding method according to claim 1, wherein the bonding is performed using a bonding tool, and the application of the ultrasonic wave to the tool is performed by a plurality of bonding heads having different ultrasonic vibration directions. 5. A work stage and a bonding tool provided opposite to the work stage and to which ultrasonic vibration is applied, wherein a bump formed on an electrode of a device adsorbed by the bonding tool is placed on the work stage. In a bonding apparatus for applying ultrasonic waves to a bonding tool by applying ultrasonic waves to electrodes of a mounted envelope and applying thermosonic pressure to the bonding tools, the application of the ultrasonic waves to the bonding tool has a vibration direction changing means for changing a vibration direction. Bonding equipment.