JPH0499034A - Bump forming method and bump forming device - Google Patents

Abstract

PURPOSE:To cut down the process numbers for facilitating the bump formation by a method wherein a recession is provided in the end part of an elevating press part to press a wire or a sheet material against an electrode on a substrate so that a bump may be formed simultaneously to pressure-weld the bump into the electrode. CONSTITUTION:A wire 5 is pressed against an electrode 2 on a substrate 1 using a press part 6 so that a part of the wire 6 may be pressed into the recession 8 of the end part 7 simultaneously to be pressure-welded into the electrode 2. At this time, the junction of the wire 5 and the electrode 2 can be further reinforced by impressing the press part 6 with ultrasonics. Next, the presse part 6 is lifted upward while holding the wire 5 with a clamper part 3 so as to tear off the wire 5 from the bump 9. Next, after tearing off the wire 5 from the bump 9, the set up amount of the new wire 5 is fed to the part beneath the pressed part 6 by the clamper part 3. Next, the bump 9 is formed on the next electrode 2. Through these procedures, the bump 9 can be formed successively on the following electrodes 2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a bump forming method and a bump forming apparatus.

2. Description of the Related Art A conventional bump forming method and a conventional bump forming apparatus will be described below with reference to the drawings.

(1) Conventional bump forming method using a wire bonder (part 1) FIGS. 4(a) to 4(e) are process cross-sectional views of a first bump forming method using a conventional wire bonder.

As shown in FIG. 4(a), the tip of the gold (Au) wire 22 passed through the hole of the capillary 21 is heated by electric discharge or the like.
A ball 23 having a diameter 2 to 3 times the diameter of the u-wire 22 is formed. 24 is an LSI chip, and 25 is an electrode pad on the LSI chip 24. Next, as shown in the same figure (b),
A ball 23 formed at the tip of the Au wire 22 is pressed and fixed to the electrode pad 25 of the LSI chip 24 by the capillary 21 to form a bump 26. Next, as shown in FIG. 2C, the capillary 21 is vertically raised above the bump 26, and as shown in FIGS.
A laser beam 28 is irradiated perpendicularly to the Au wire 22 from a laser device 27 to cut it.

(2) Conventional bump forming method using a wire bonder (Part 2) FIGS. 5(a) to 5(e) are process cross-sectional views of a second bump forming method using a wire bonder.

As shown in FIG. 5(a), a ball 23 having a diameter two to three times the diameter of the Au wire 22 is formed at the tip of the Au wire 22 passed through the hole of the capillary 21 by electric discharge. Next, as shown in FIG. 2B, the ball 23 formed at the tip of the Au wire 22 is pressed and fixed to the electrode pad 25 of the LSI chip 24 by the capillary 21 to form a bump 26. Next, as shown in (C) to (e) of the figure, the capillary 21 is moved in a loop-shaped trajectory above the bump 26, and then the capillary 21 is lowered to cut the Au wire 22 and move the upper part of the bump 26. A top portion 29 is formed. Note that FIG. 2D shows the locus of the tip of the capillary 21. By such a forming method, the bump 26 having a two-step protrusion structure is formed.

(3) Conventional bump formation method using plating method Figure 6 shows the shape of a bump formed by plating method. A glabellar insulating film 31 is formed on a silicon wafer 30 on which a large number of LSIs are formed. An aluminum electrode 32 is formed on the glabellar insulating film 31, and a surface protection film 33 having an opening in a part of the aluminum electrode 32 is formed over the entire surface. In connection using the normal wire bonding method, the silicon wafer 30 in this state is divided into individual LSIs and sent to an assembly process.

On the other hand, in bump formation by electrolytic plating, an under bump metal layer 34 for diffusion prevention, which also serves as an electrode during plating, is first formed on the entire surface of the surface protection film 33. Next gold bump 3
A photoresist film (
(omitted in the figure). In this state, electrolytic plating is performed using the under bump metal layer 34 as one electrode to form gold bumps 35 of a predetermined height.

After removing the photoresist film, using the gold bump 35 or the newly formed photoresist film as a mask, the underbump metal layer 35 in the area other than the lower part of the gold bump 35 is removed by etching.

Problems to be Solved by the Invention However, in the above-mentioned conventional configuration, the bump formation method using a wire bonder causes defects such as uneven height of the bump and failure of the ball to stick to the electrode of the LSI. Since the diameter of the bottom portion is approximately 100 μm, there is a problem in that it is difficult to form bumps with a narrow pitch. In addition, in the bump formation method using the electrolytic plating method, L
The problem is that the process is complicated and the cost is high, as two to three new underbump metal layers are formed on the silicon wafer on which the SI has been formed, and the process is immersed in an electrolytic plating solution and plated while applying electricity. was.

The present invention solves the above-mentioned conventional problems, and aims to provide a bump forming method and a bump forming apparatus for forming bumps directly on a silicon wafer used in an assembly process using the conventional wire bonding method.

Means for Solving the Problems To achieve this object, the bump forming method of the present invention is as follows:
The first step is to supply the workpiece directly under the pressing part that has a concave portion at the tip, and the pressing part is used to press the workpiece to form a bump, and the bump is bonded onto a predetermined electrode of the substrate. It has a configuration including a second step of performing.

Effect: With this configuration, the shape of the bump is determined by the shape of the recess provided at the tip of the pressing part, so it is possible to always form a bump with a constant height and shape, and by changing the shape of the recess, it is possible to form any shape. bumps can be easily formed.

EXAMPLE Hereinafter, a bump forming method in an example of the present invention will be described with reference to the drawings.

FIGS. 1(a) to 1(e) are process cross-sectional views showing a bump forming method in an embodiment of the present invention.

First, as shown in FIG. 1(a), a substrate 1 on which electrodes 2 are formed is placed at a predetermined position in a bump forming apparatus. Next, a set amount of wire 5 is supplied by the clamper section 3 through the guide 4 directly below the tip end 7 of the pressing section 6 . Next, as shown in FIG. 6B, by pressing the wire 5 against the electrode 2 on the substrate 1 with the pressing part 6, a part of the wire 5 is pushed into the tip part 70 and the recess 8, and at the same time, the wire 5 is pressed against the electrode 2 on the substrate 1. is glued to. At this time, by applying ultrasonic waves to the pressing part 6, the bond between the wire 5 and the electrode 2 can be further strengthened (the ultrasonic oscillator is omitted in the drawing). Next, the same figure (C)
As shown in FIG. 2, the wire 5 is torn off from the bump 9 by holding the wire 5 with the clamper 3 and pulling up the pressing part 6 upward. Note that the debris remaining after the wire rod 5 is torn off is blown away with gas from the high-pressure gas nozzle 10. The shape of the bump 9 formed at this time is the opposite shape to that of the tip portion 70 and the recessed portion 8. After the wire 5 is torn off from the bump 9, the clamper section 3 supplies a new set amount of the wire 5 directly below the pressing section 6. Next, the same figure (d
), bumps 9 are formed on the next electrode 2. In this way, bumps 9 are sequentially formed on the electrodes 2, as shown in FIG. 2(e).

Next, a bump forming apparatus according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 2(a) is a perspective view of a main part of a bump forming apparatus according to an embodiment of the present invention, and FIG. 2(2) is an enlarged partial sectional view of section A in FIG. 2(a). In these figures, the same parts as in FIG. 1 are denoted by the same reference numerals, and detailed explanation will be omitted. Note that 11 is an ultrasonic oscillator, and 12 is an ultrasonic horn that transmits ultrasonic waves from the ultrasonic oscillator 11 to the pressing part 6.

As shown in FIG. 2(a), a bump forming apparatus according to an embodiment of the present invention includes a base (not shown in the drawing) on which a substrate 1 is mounted, a pressing section 6 that presses a wire 5, and a support for the pressing section 6. At the same time, an ultrasonic horn 12 transmits ultrasonic waves from an ultrasonic oscillator 11 to the pressing part 6, and a bump 9 is placed on the electrode 2 of the substrate 1.
It is comprised of a high-pressure gas nozzle 10 that supplies high-pressure gas to blow away debris, etc. from the wire 5 after it is formed.

The details of the portion (A section) surrounded by a circle in FIG. 2(a) will be explained using FIG. 2(b).

First, the recess 8 provided at the tip 7 of the pressing part 6 is formed into a bump 9.
The cross-sectional shape of the bump 9 formed by the recess 8 is a stack of cylinders with different diameters, with the lower cylinder having a larger diameter and height than the upper cylinder. It has a low structure. Further, the tip portion 7 having concave portions 8 of various shapes is prepared in advance so that it can be replaced as necessary. A suitable material for the pressing portion 6 is ultra-strong steel or the like. Further, the guide 4 provided in a part of the pressing portion 6 is a through hole through which the wire 5 is passed.

The clamper section 3 has a function of feeding out and holding the wire rod 5 in conjunction with the pressing section 6. Since the diameter of the wire 5 is finished with high precision, the height of the bump 9 formed in the recess 8 is extremely uniform.

Note that in the embodiments described above, a bump forming method and a bump forming apparatus using the wire 5 have been described, but even if a plate material is used instead of the wire 5, the bumps 9 can be similarly formed on the electrode 2 of the substrate l. I can do it. Furthermore, Figure 3 (
As shown in a) and (b), by making the shape of the recess 8 of the tip 7 of the pressing part 6 into a rectangular parallelepiped conical shape or other shape, bumps of various shapes can be easily formed.

Effects of the Invention As described above, in the bump forming method of the present invention, a concave portion is provided at the tip of the pressing portion that moves up and down, and the pressing portion presses a wire or plate material against the electrode of the substrate, and at the same time as forming a bump, the bump is attached to the electrode. By adhering, bumps can be easily formed without requiring a vapor deposition process, a resist film forming process, and a plating process. Further, in the bump forming apparatus of the present invention, the tip of the pressing part is made replaceable, and by preparing the tip with a recess of a different shape, it is possible to easily form a bump with a shape corresponding to the shape. I can do it.

[Brief explanation of drawings]

FIGS. 1(a) to <e> are process sectional views showing a bump forming method in an embodiment of the present invention, FIG. 2(a) is a perspective view of essential parts of a bump forming apparatus in an embodiment of the present invention, FIG. 2(b) is an enlarged partial sectional view of part A in FIG. 2(a), FIGS. 3(a) and (b) are front views showing the shape of the tip of the pressing part,
FIGS. 4(a) to 4(e) are process cross-sectional views of the first bump forming method using a conventional wire bonder, and 5th rj4(a) to
(e) is a process cross-sectional view of a second bump forming method using a conventional wire bonder, and FIG. 6 is a cross-sectional view of a bump formed by a conventional plating method. 1...Substrate, 2...Electrode, 5...
...Wire rod (workpiece material), 6...Press section, 7...
...Tip, 8...Concavity, 9...
bump. Agent's name: Patent attorney Shigetaka Awano Baka 1 Famous Confectionery! Figure front Figure Z Figure Z

Claims (6)

[Claims] (1) A first step in which a workpiece is supplied directly under a pressing part having a concave portion at the tip, and the pressing part is used to press the workpiece to form a bump, and the bump is placed in a predetermined position on the substrate. A bump forming method comprising a second step of adhering onto an electrode. (2) The bump forming method according to claim 1, characterized in that when the pressing section is pressing the workpiece, ultrasonic vibration is applied to the pressing section. (3) The bump forming method according to claim 1, wherein the workpiece is supplied after being cut into a shape required for one bump in advance. (4) A pressing part that has a concave part at its tip that presses the workpiece to form a bump, and presses the bump onto the electrode of the substrate, and a supply part that supplies the workpiece directly below the pressing part. A bump forming device comprising: (5) The bump forming device according to claim 4, wherein the tip portion having a concave portion for forming a bump is detachably held by the pressing portion. (6) The bump forming apparatus according to claim 4, further comprising a clamper section that feeds or holds the workpiece in conjunction with the pressing section.