JP3429177B2 - Bump formation method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes a bump forming head for forming bumps on electrodes of a semiconductor element mounted on a circuit board, a bump forming method executed by the bump forming head, and the bump forming head. More specifically, the present invention relates to a bump forming head, a bump forming method, and a bump forming apparatus that use a fluid conductive material.

[0002]

2. Description of the Related Art In recent years, as a method for mounting a semiconductor element on a circuit board, an FCB (Flip Chip Bonding) mounting method for mounting the semiconductor element face down on an electrode on the circuit board is increasingly used. As a bump forming method in this FCB mounting method, conventionally, a wire bonder is used and an SBB (Stud Bump Bonding) method is used to form bumps using, for example, a gold wire. A conventional bump forming method using gold wire and its apparatus will be described with reference to FIGS. 8 and 9. Reference numeral 2 denotes a carry-in device that carries the tray 4a into the bump forming apparatus 20 in a state where the semiconductor element 3 for forming bumps is housed in the tray 4a. Reference numeral 1 denotes a carry-out device that stores the semiconductor element 3 on which the bumps are formed in a tray 4 and carries the tray 4 out of the bump forming apparatus 20. Reference numeral 5 denotes a semiconductor element transfer device that moves the semiconductor element 3 between the tray 4 and the bump forming stage 6 by moving in the X and Y directions that are orthogonal to each other on a plane. Reference numeral 7 denotes a bump forming head, which supplies an ultrasonic horn 9 and a gold wire 10 which is supported by the ultrasonic horn 9 and supplies a gold wire 10 with the ultrasonic horn 9 which causes vibration of the ultrasonic wave to act on the gold wire 10. With. 1
1 is a semiconductor element 3 held by the bump forming stage 6.
On the other hand, the X and Y stages move the bump forming head 7 in the X and Y directions. Reference numeral 12 denotes a recognition camera which is provided on the X, Y stage 11 and recognizes electrodes for forming bumps on the semiconductor element 3 held by the bump forming stage 6. The bump forming head 12 is provided on the X, Y stage 11. It is installed adjacent to 7.

The operation of the conventional bump forming apparatus 20 thus constructed will be described below. Semiconductor element transfer device 6
However, the semiconductor element 3 stored in the tray 4a and conveyed
Is adsorbed on the bump forming stage 6 and transferred to and placed on the bump forming stage 6 whose temperature has been raised. Here, the semiconductor element 3 is fixed to the bump forming stage 6 by vacuum suction. In order to form a bump on the electrode 13 of the semiconductor element 3, first, as shown in FIG. 9A, the tip of the gold wire 10 passed through the capillary 8 is melted by a spark means (not shown) to form a spherical shape. . Next, as shown in FIG. 9B, the capillary 8
Presses the sphere formed at the tip of the gold wire 10 held by the capillary 8 against the electrode 13 of the semiconductor element 3. Then, ultrasonic vibration is applied through the ultrasonic horn 9, and the sphere is first bonded to the electrode 13 by the temperature, the pressure, and the vibration caused by the ultrasonic wave. Next, as shown in FIG. 9C, after the capillary 8 is raised, the capillary 8 is slightly moved laterally so as to make a loop so as to form a loop, and then the capillary 8 is pushed to the side of the first-bonded position ( Second bonding), the gold wire 10 is cut, and a series of operations is completed. When this operation is repeated to form bumps on the electrodes 13 on the semiconductor element 3, the semiconductor element transfer device 5 sucks and holds the semiconductor element 3 on the bump forming stage 6 and conveys the semiconductor element 3 to the tray 4b.
Are stored in the tray 4b.

[0004]

However, in the configuration of the conventional bump forming apparatus 20, since only one bump can be formed on each electrode 13 of the semiconductor element 3 in each series of operations, the production takt time is reduced. If there are 300 or more electrodes 13 in one semiconductor element 3 for a long time, it takes a long time to form bumps, and the productivity is low. Further, since the gold wire, which is the material of the bump, has become thinner, it is difficult to supply the gold wire. The present invention has been made to solve such a problem, and provides a bump forming head capable of shortening the production takt time, a bump forming method executed by the bump forming head, and the bump forming head. It is an object of the present invention to provide a bump forming device provided with the bump forming device.

[0005]

A bump forming method according to a first aspect of the present invention is a conductive material having a plurality of conductive material discharge holes arranged corresponding to electrodes on a semiconductor element on which bumps are formed. Extruding a conductive material having fluidity to be the bumps through the conductive material discharge hole of the supply member,
The conductive material supply member is moved to the semiconductor element side, and the conductive material extruded from the conductive material discharge hole is pressed against the electrode of the semiconductor element to form the bump, and the pressing is released. After that, the conductive material supply member is moved in a direction away from the semiconductor element to cut the bump formed on the electrode and the conductive material remaining in the conductive material discharge hole portion.

[0006]

[0007]

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A bump forming head, a bump forming apparatus equipped with the bump forming head, and a bump forming method executed by the bump forming apparatus according to embodiments of the present invention will be described with reference to the drawings. This will be described below. In each figure, the same components are designated by the same reference numerals. An example of the function of the "support member" described in "Means for Solving the Problems" corresponds to the ultrasonic horn 112 in the present embodiment. The bump forming apparatus 101 shown in FIG. 7 is roughly classified into a carry-in apparatus 2, a carry-out apparatus 1, a semiconductor element transfer apparatus 5, and a bump forming head 11.
0, a first recognition device 151, and a control device 501. The carry-in device 2, the carry-out device 1, and the semiconductor element transfer device 5 have the same configurations and operations as those provided in the conventional bump forming device 20 described above. That is, the carry-in device 2 is
This is an apparatus that includes a tray 4a that accommodates the semiconductor element 3 for forming bumps and that carries the tray 4a into the bump forming apparatus 20. The carry-out device 1 is a device that is equipped with a tray 4 for accommodating the semiconductor elements 3 having bumps formed thereon and carries out the tray 4 to the outside of the bump forming device 20. The semiconductor element transfer device 5 has X, Y axes that are orthogonal to each other on a plane.
The semiconductor element 3 is moved between the tray 4 and the bump forming stage 6 by moving in the direction. First recognition device 151
Is installed adjacent to the bump forming stage 6,
In the present embodiment, the recognition camera is used to align the electrodes formed on the semiconductor element 3 with the conductive material discharge holes 1110 in the conductive material supply member 111, which will be described later, provided in the bump forming head 110. In order to obtain image information, the conductive material supply member 111 is mainly imaged. These carry-in device 2, carry-out device 1, semiconductor element transfer device 5, bump forming head 110, and first recognition device 1
Reference numeral 51 is connected to the control device 501, and the control device 501 executes operation control of these components.

The basic structure of the bump forming head 110 is as follows.
The structure is the same as that of the bump forming head 7. That is,
As shown in FIG. 2, the bump forming head 110 is an ultrasonic horn 1 attached to a frame 116 installed on an X, Y stage 115 that is movable in the X and Y directions.
12 and a conductive material supply member 111 attached to the tip portion 112a of the ultrasonic horn 112 along the vertical direction.
And the frame 11 attached to the frame 116.
The ultrasonic horn 1 with the fulcrum 117 in 6 as the center of rotation
An actuator 118, which is an example that performs the function of a “support member driving device” that swings 12 in the direction of arrow I, an ultrasonic generator 119 that generates ultrasonic waves in the ultrasonic horn 112, and the X and Y stages. And a second recognition device 114 installed on 115. The second recognition device 114
Is a recognition camera in the present embodiment, and the electrodes formed on the semiconductor element 3 and the conductive material supply member 11 are
In order to obtain image information for performing alignment with the conductive material discharge hole 1110 in 1, the semiconductor element 3 is mainly imaged. According to the imaging information from the first recognition device 151 and the second recognition device 114 described above, the control device 501 controls the electrodes formed on the semiconductor element 3 and the conductive material discharge holes 1110 in the conductive material supply member 111. The X, Y stage 115 is moved so as to perform the position alignment. In the present embodiment, the ultrasonic wave generator 119 is set to X, Y.
Although it is installed on the stage 115, it is not limited to this and may be installed outside the X, Y stage 115.

As is apparent from the above structure, the difference between the bump forming head 110 and the conventional bump forming head 7 is that the conductive material supply member 111 is provided instead of the capillary provided in the conventional bump forming head 7. The other configuration is basically the same as that of the conventional bump forming head 7. Further, the conductive material supply member 11
1 is provided, the bump forming apparatus 101 is provided with the pressure suction device 120 that pressurizes or negatively pressures the inside of the conductive material supply member 111. The pressure suction device 1
In the present embodiment, 20 corresponds to an example that functions as a "conductive material entrance / exit control device". The pressure suction device 120 may be provided on the bump forming head 110.
In addition, the above-mentioned actuator 118 and ultrasonic generator 11
9 and the pressure suction device 120 are connected to the control device 501, and the control device 501 executes respective operation control.

The conductive material supply member 111 will be described in detail. As shown in FIG. 1, the conductive material supply member 11
Reference numeral 1 denotes a hollow body supported by the tip portion 112a of the ultrasonic horn 112. By pushing out a conductive material 131 which is a bump material housed inside, a hollow body 1 is once pressed against a plurality of electrodes on the semiconductor element 3. This is a member for forming a plurality of bumps by the operation of. The planar shape of the conductive material supply member 111 is substantially equal to the planar shape of the semiconductor element 3 on which bumps are formed by the conductive material supply member 111. Further, the conductive material supply member 111 has the storage section 1111 for storing the conductive material 131 therein, as described above.
In addition, the conductive material supply member 111 facing the semiconductor element 3
A plurality of conductive material discharge holes 1110 that correspond to the respective electrodes formed on the semiconductor element 3 and that penetrate the inside and outside of the conductive material supply member 111 are arranged on the semiconductor element side wall 1114. There is. As shown in the figure, the conductive material discharge hole 1110 has a circular cross section in this embodiment and has a funnel shape in which the diameter of the semiconductor element side surface 111a is larger than the diameter of the conductive material supply member 111 on the inner side. It has a cross-sectional shape. Although the number of the conductive material discharge holes 1110 is five in the drawing, the number and the shape thereof are not limited, and various modes are possible.
In one embodiment, the conductive material supply member 111 is made of stainless steel, and the outer dimensions are 10 mm in length × 10 mm in width.
× Height is 10 mm, the volume of the storage section 1111 is about 384 mm ² , and 400 conductive material discharge holes 1110 are arranged in a matrix at a pitch of 0.3 mm. The diameter of the conductive material discharge hole 1110 on the inner side of the conductive material supply member 111 is 0.03 m.
m and the diameter on the side surface 111a of the semiconductor element is 0.0
It is 7 mm.

Further, the storage portion 1111 is provided with a piston 1112 which slides in the storage portion 1111 along its extension direction in order to push out the stored conductive material 131 from the conductive material discharge hole 1110. There is. The pressure suction device 120 is connected to the conductive material supply member 111 via the tube 113, and the mounting wall 1115 facing the semiconductor element side wall 1114 has a pressure suction device 120.
An opening 1113 serving as a gas passage is formed. Therefore, the piston 1112 slides in the direction of arrow II by the gas that enters and leaves the conductive material supply member 111 through the opening 1113 by the pressure suction device 120. In the present embodiment, the gas handled by the pressure suction device 120 is air, but the gas is not limited to this.
Pressurized air is supplied into the conductive material supply member 111 by the pressure suction device 120 and the piston 1112 is pushed down, whereby the conductive material 131 stored in the storage portion 1111.
Are discharged to the outside through the conductive material discharge hole 1110. On the other hand, the pressure suction device 120 creates a negative pressure in the conductive material supply member 111, so that the piston 1112 is pulled up and the conductive material 131 remaining in the conductive material discharge hole 1110 is returned to the storage portion 1111. In the present embodiment, the conductive material 131 is, for example, a mixed material of silver and palladium, is a thermosetting epoxy resin using butyl carbitol acetate (BCA) as a solvent, and has a viscosity of 50 Pa · s. To use.
Further, the conductive material 131 may contain a gold component. By containing gold, the conductivity and processability are improved, and the performance close to that of the gold bump shown in the above-mentioned conventional technique can be obtained. The conductive material 131 is supplied into the conductive material supply member 111 by injecting one side surface of the cover of the conductive material supply member 111. or,
The conductive material 131 is temporarily cured at 120 ° C. by heating in the bump forming stage 6.

The bump forming apparatus 10 thus configured
The operation of No. 1 will be described below. First, the semiconductor element 3 on the tray 4a carried in by the carrier device 1 is adsorbed by the semiconductor element transfer device 5 and transferred onto the heated bump forming stage 6. The semiconductor element 3 mounted on the bump formation stage 6 is fixed by, for example, suction. Next, FIG.
The pressurized air is supplied from the pressure suction device 120 through the tube 113 into the conductive material supply member 111 as shown in FIG. The piston 1112 is pushed down by the pressurized air, and as shown in FIG. 4, the conductive material 131 stored in the storage portion 1111 is discharged through the conductive material discharge hole 1110. The ejection amount at this time is one of the factors that determine the size of the bump formed on the electrode of the semiconductor element 3. Therefore, the control device 501 controls the conductive material 1
According to the viscosity information of 31 and the diameter of the conductive material discharge hole 1110, the relationship between the pressing force and the discharge amount is obtained in advance, and the pressure suction device 120 is provided so as to obtain the predetermined discharge amount.
Control the behavior of.

First recognition device 151 and second recognition device 11
Based on the imaging information obtained from No. 4, the control device 501 controls the X, Y stage 115 so that the electrodes of the semiconductor element 3 and the conductive material discharge holes 1110 of the conductive material supply member 111 are aligned and aligned. , Y direction.
After the completion of the alignment, the control device 501 drives the actuator 118 to lower the conductive material supply member 111 to the semiconductor element 3 side, and as shown in FIG. 5, is discharged from the conductive material discharge hole 1110. Conductive material 131
And the electrode 13 on the semiconductor element 3 are brought into contact with each other. At this time, the control device 501 further activates the ultrasonic oscillator 119 to generate ultrasonic waves through the ultrasonic horn 112.
The voltage is applied to the upper conductive material 131, and the actuator 118 is further driven so that the conductive material 1 on the electrode 13 is applied.
31 is pressed onto the electrode 13. By applying the above-mentioned ultrasonic waves, spherical bumps are formed into bump conductive material discharge holes 1
The conductive material 131 can be formed into a shape conforming to the shape of 110, and when the conductive material 131 is brought into contact with the electrode 13 and an ultrasonic wave is applied thereto, the oxide film on the surface of the electrode 13 is destroyed and the conductivity with respect to the electrode 13 is increased. The joining of the materials 131 can be facilitated. The conductive material 131 on the electrode 13
The pressing of the conductive material 1 between the adjacent electrodes due to excessive pressing.
31 and the conductive material 13
1 is performed at a pressure that allows molding into a shape along the shape of the bump conductive material discharge hole 1110. By such operation, the bumps 14 are formed on the electrodes 13 of the semiconductor element 3 by utilizing the heat of the bump forming stage 6 again.
To form. In this way, by applying ultrasonic waves, pressing, and utilizing the heat, the conductive material 1
The 31 and the electrode 13 are joined together with higher reliability, and the quality can be improved.

The pressing force of the conductive material 131 on the electrode 13, the ultrasonic frequency applied to the conductive material 131 on the electrode 13, the temperature at the bump forming stage 6, the conductive material supply member 111. The conductive material 13 discharged from the conductive material discharge hole 1110 according to the descending speed
1 by changing the impulse force to the electrode 13
The shape of the bump 14 formed above can be adjusted. Therefore, the control device 501 controls the bump 14 having the desired shape.
The temperature of the ultrasonic oscillator 119, the actuator 118, and the bump formation stage 115 is controlled so that the shape is shaped. Specifically, the control device 501 performs temperature control so that the temperature in the bump forming stage 115 has a fluctuation of about ± 5 ° C. Further, for the actuator 118, the conductive material 131 is above the electrode 13. The conductive material supply member 111 is set to, for example, 60 until it approaches 100 μm.
It is lowered at a speed of 0 mm / s, and thereafter, for example, 10 mm / s until the conductive material 131 comes into contact with the electrode 13.
Control to lower at the speed of. The contact between the conductive material 131 and the electrode 13 is determined by the torque load of the actuator 118.

After that, as shown in FIG. 6, the conductive material supply member 111 is raised by the operation of the actuator 118. Preferably, immediately before starting the above-mentioned ascent, the pressure suction device 120 is operated to make the inside of the conductive material supply member 111 a negative pressure and pull up the piston 1112. As a result, the conductive material 131 remaining in the conductive material discharge hole 1110 is pulled back into the storage portion 1111. Therefore, when the conductive material supply member 111 rises as described above, the conductive material 131 moves in the conductive material discharge hole 1110. There is an effect that it is easy to cut and the formed bump shape can be made uniform. Then, the control device 501 drives the semiconductor element transfer device 5 to adsorb the semiconductor element 3 on the bump formation stage 6, transfers it to the tray 4b of the ejection device 1, and stores it.
As described above, since the conductive material 131 itself has an adhesive property, it is possible to prevent the bump 14 from being displaced from the electrode 13 of the semiconductor element 3 due to vibration such as transfer of the semiconductor element 3. When a conductive material other than that used in the present embodiment is used, a curing device for curing the conductive material may be provided after forming the bump 14 on the electrode 13 of the semiconductor element 3. However, it is advantageous that the bumps themselves have fluidity when the semiconductor element 3 is mounted face down in a later step. After that, the above-described operation is repeated to form the bump 14 on each semiconductor element 3.

The first recognition device 151 described above can also capture an image of the state in which the conductive material 131 is discharged from the conductive material discharge hole 1110 as shown in FIG.
The imaging operation allows the control device 501 to determine whether the ejection of the conductive material 131 is good or bad. If an ejection failure is found, for example, a measure such as equipment stoppage can be taken for maintenance. it can. In addition, in the present embodiment, the first recognition device 151 and the second recognition device 114 are provided as described above, but only the second recognition device 114 is provided, and the semiconductor element 3, the conductive material supply member 111, and the semiconductor material 3 are provided. It is also possible to perform the alignment of.

In the above embodiment, the pressure suction device 1 is used.
Although 20 performs both the operation of sending pressurized air and the suction of air through one tube 113, separate devices and tubes may be provided.

In the above embodiment, the ultrasonic horn 1 is used.
Although the case where one conductive material supply member 111 is provided at the tip of 12 is shown, the present invention is not limited to this, and a plurality of conductive material supply members may be provided. In this case, each conductive material supply member can be arranged corresponding to the arrangement of the electrodes 13 of the semiconductor element 3. By providing a plurality of conductive material supply members for one semiconductor element 3 as described above, each conductive material supply member can be downsized even in the case of a large semiconductor element 3, and the conductive material The conductive material 131 can be discharged from the discharge hole 1110 more stably.

[0020]

As described above in detail, according to the bump forming method of the first aspect of the present invention, since the conductive material supply member having the plurality of conductive material discharge holes is provided, the bump formation is performed once. A plurality of bumps can be formed by the operation, and the tact time of production can be shortened.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a conductive material supply member included in a bump forming apparatus according to an embodiment of the present invention.

FIG. 2 is a side view of a bump forming head portion including the conductive material supply member shown in FIG.

FIG. 3 is a view for explaining the operation of the conductive material supply member shown in FIG.

FIG. 4 is a view for explaining the operation of the conductive material supply member shown in FIG.

FIG. 5 is a view for explaining the operation of the conductive material supply member shown in FIG.

FIG. 6 is a view for explaining the operation of the conductive material supply member shown in FIG.

7 is a perspective view showing a bump forming apparatus including the conductive material supply member shown in FIG.

FIG. 8 is a perspective view showing a conventional bump forming apparatus.

9A to 9D are diagrams illustrating a conventional bump forming operation.

[Explanation of symbols]

3 ... Semiconductor element, 13 ... Electrode, 14 ... Bump, 101 ...
Bump forming apparatus, 111 ... Conductive material supply member, 112
... ultrasonic horn, 113 ... tube, 118 ... actuator, 120 ... pressure suction device, 131 ... conductive material 5
01 ... Control device 1110 ... Conductive material discharge hole.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiro Yamamoto 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor ▲ Kichiichi Ta, Kozo, Osaka Prefecture Sangyo Co., Ltd. (56) Reference JP-A-8-203909 (JP, A) JP-A-7-176534 (JP, A) JP-A-60-20537 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) H01L 21/60 H01L 21/60 311

Claims (5)

(57) [Claims] 1. A collector electrode of the semiconductor element where the bumps are formed
Having a plurality of conductive material discharge holes arranged to correspond to the
Through the conductive material discharge hole of the conductive material supply member and pushed out a conductive material having fluidity as the above bump, the conductive material of the above conductive material supply member is moved to the side of the semiconductor elements The conductive material extruded from the discharge hole is pressed against the electrode of the semiconductor element to form the bump, and after the pressing is released, the conductive material supply member is moved in a direction away from the semiconductor element. cut and the conductive material remaining on the bump and the conductive material discharge hole portion formed in the electrode, the bump forming method characterized by. 2. When the conductive material is extruded from the conductive material discharge hole , the conductive material is fed into the conductive material supply member.
The bump forming method according to claim 1, wherein a compressed gas is supplied. Wherein when cutting the said conductive material of the formed bump and the conductive material discharge hole portion to the electrode, the upper
A negative pressure is applied to the inside of the conductive material supply member to supply the conductive material.
The conductive material is sucked into the feeding member to form the electrode.
Bumps and the conductive material in the conductive material supply member
The method for forming bumps according to claim 1 or 2, wherein cutting with a material is performed.
Law. 4. When pressing the conductive material extruded from the conductive material discharge hole to the electrode, ultrasonic waves
The method of forming bumps according to claim 1, wherein ultrasonic waves are applied to the conductive material on the electrodes via a horn.
Law. 5. Extruded from the conductive material discharge hole
When pressing the conductive material against the electrode,
Along with heating to temporarily cure the above conductive material, request
Item 5. The bump forming method according to any one of Items 1 to 4.