JP2000349110A - Bump sheet, and method and device for forming bump using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transfer a lot of solder fixed on a bump sheet to a semiconductor chip in a short time b forming the bump sheet into a strip or tape while a slit is so provided as to surround solders which are to be transferred. SOLUTION: A bump sheet 1 is aligned with a semiconductor chip, and a solder 2 fixed on the bump sheet 1 is transferred to the semiconductor chip. In short, a semiconductor chip aligned to the bump sheet 1 on a fixing device is fixed and heated to a specified temperature. Solder groups 2 which are arrayed proportional to the electrode array of an LSI chip are provided with constant intervals on a bump sheet part 5, with slits 3 formed at points for avoiding heat radiation of heat conductivity. The slits 3 are linearly formed, by four, to surround the bump sheet part 5, or formed in L-shape at a corner part. Thus, a lot of solders are transferred at high reliability in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bump sheet, a bump forming apparatus and a bump forming method using the same, and more particularly, to a bump bump sheet capable of transferring a large amount of solder in a short time and a bump using the same. The present invention relates to a forming apparatus and a bump forming method.

[0002]

2. Description of the Related Art Well-known methods for forming solder bumps on a flip-chip LSI include a vapor deposition method, a plating method, a solder paste printing method, and a solder ball mounting method that can be processed individually for the LSI. ing.

In order to obtain high yield and high reliability,
It is desired that the height of the solder bumps be uniform and as high as possible. Since the vapor deposition method, the plating method, and the like are equipment investments and batch processing of wafers, there is waste in supplying solder to defective portions, and the cost cannot be justified. Although the ball mounting method can meet the demand for reliability, it is difficult to arrange and transfer minute balls, and the production capacity is poor.
Further, in the conventional bump forming method, the means for melting and shaping the bumps is often a reflow furnace. , And the flux is carbonized, and the cleaning property is lowered, so that residue becomes a problem. For these reasons, there is a need for a technique of transferring a prepared solder and heating it in a short time to form a bump.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned drawbacks of the prior art, and in particular, to provide a novel bump sheet and a bump forming apparatus using the same, which enable a large amount of solder to be transferred in a short time. And a method for forming a bump.

[0005]

SUMMARY OF THE INVENTION The present invention basically employs the following technical configuration to achieve the above object.

[0006] That is, the first of the bump sheet according to the present invention.
An aspect is a bump sheet for aligning a bump sheet and a semiconductor chip and transferring solder fixed on the bump sheet to the semiconductor chip, wherein the bump sheet is formed in a strip shape or a tape shape. In addition, a slit is provided so as to surround the solder group to be transferred, and a second aspect is characterized in that the slit is formed in a linear shape. In a third aspect, the slit is formed in an L-shape, and in a fourth aspect, a bump sheet and a semiconductor chip are aligned with each other. A bump sheet for transferring solder fixed on the bump sheet to the semiconductor chip, wherein a resin layer is provided on the bump sheet, and a copper thin film is formed on the resin layer; A solder for transfer is fixed on a copper thin film, and a fifth aspect is that a bump sheet and a semiconductor chip are aligned, and the solder fixed on the bump sheet is removed. A bump sheet for transferring to the semiconductor chip, on the bump sheet, a solder having a small diameter portion having a small diameter made of solder and a large diameter portion having a large diameter are fixed. A large part is fixed on the bump sheet via a small diameter part. In a sixth aspect, the bump sheet and the semiconductor chip are aligned and fixed on the bump sheet. A bump sheet for transferring the applied solder to the semiconductor chip, wherein a recess is formed in the bump sheet, and the solder is fixed on the recess so as to cover the recess. is there

Further, the first aspect of the bump forming apparatus according to the present invention is as follows.
An aspect is a bump forming apparatus for aligning a bump sheet and a semiconductor chip and transferring solder fixed on the bump sheet to the semiconductor chip, wherein the bump sheet mounts and fixes the bump sheet. A fixing device, a chip fixing device provided above the bump sheet fixing device and fixing the aligned semiconductor chip, a heating device for heating the semiconductor chip to a predetermined temperature, and a semiconductor chip of the chip fixing device And a movable control device for bringing the solder of the bump sheet on the bump sheet fixing device into contact with the bump sheet fixing device. And a heating device for heating the bump sheet to a temperature of The present invention is characterized in that the bumper is fixed by a spacer and the spacer is used to maintain a predetermined distance between the bump sheet fixing device and the chip fixing device. A time control device for controlling a contact time between the chip and the solder of the bump sheet on the bump sheet fixing device is provided.

Further, a first method of forming a bump according to the present invention is described.
An aspect is a bump forming method for aligning a bump sheet and a semiconductor chip and transferring solder fixed on the bump sheet to the semiconductor chip, wherein the bump sheet is positioned on a bump sheet fixing device. A first step of fixing and fixing, a second step of positioning and fixing a semiconductor chip on a chip fixing device provided above the bump sheet fixing device, and contacting the semiconductor chip with solder on the bump sheet. And heating the semiconductor chip to a predetermined temperature to make the solder on the bump sheet spherical, and to transfer the spherical solder to the semiconductor chip. In the second embodiment, the bump sheet and the semiconductor chip are aligned, and the solder fixed on the bump sheet is A method for forming a bump for transferring to a conductive chip, comprising: a first step of positioning and fixing the bump sheet on a bump sheet fixing apparatus; and a step of mounting a semiconductor on a chip fixing apparatus provided on the bump sheet fixing apparatus. While positioning and fixing the chip, a second step of heating the semiconductor chip to a predetermined temperature, contacting the semiconductor chip and solder on the bump sheet,
A third step of making the solder on the bump sheet spherical and transferring the spherical solder to the semiconductor chip.
In an aspect, in the first step, the bump sheet is heated to a temperature at which the solder does not melt.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A bump sheet, a bump forming apparatus and a bump forming method using the same according to the present invention align a bump sheet having a predetermined amount of solder formed on a substrate on which solder is not wet with an LSI chip. In the method of transferring solder, the bump sheet is preheated on the stage of the bump sheet fixing device, the LSI chip is heated by pulse heating, and the solder is melted by heat conduction from the electrode of the LSI chip. , To transfer solder.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific examples of a bump sheet, a bump forming apparatus and a bump forming method using the same according to the present invention will be described in detail with reference to the drawings.

FIGS. 1 and 2 show the structure of a bump sheet according to a first embodiment of the present invention. In these figures, a bump sheet and a semiconductor chip are shown. A bump sheet for aligning and transferring the solder fixed on the bump sheet to the semiconductor chip. The bump sheet 1 is formed in a strip shape or a tape shape, and the solder group 2 to be transferred is formed. A bump sheet provided with a slit 3 so as to surround the bump sheet is shown, and the slit 3 is a bump sheet characterized by being formed in a linear shape 3a.
A bump sheet characterized by being formed in a character shape 4 is shown.

Hereinafter, the first specific example will be described in more detail.

A bump sheet according to the present invention comprises a bump sheet having a predetermined amount of solder formed on a substrate on which solder is not wetted and an LSI.
In the method of transferring solder by aligning with the chip,
The bump sheet is preheated on the stage of the bump sheet fixing device, heats the LSI chip by pulse heating, melts the solder by heat conduction from the electrodes of the LSI chip, and solders.

In the present invention, it is not necessary to treat the bump sheet with tungsten or chromium which does not wet the solder, and even if the substrate can be soldered like stainless steel, the substrate and the solder do not sufficiently reach the bonding temperature. So it can be used.

If the bump sheet is processed into a strip or tape shape and the LSI chip is heated by using pulse heating, automation can be easily performed, and the yield and the production capacity can be improved.

FIG. 1A is a cross-sectional view of the bump sheet of the present invention viewed from the top, and FIG. 1B is a cross-sectional view of the bump sheet. FIG. 2A is a bump sheet of another specific example, and FIG.
Is a sectional view of the same.

With this configuration, the transfer margin 6 is provided on both sides of the bump sheet section 5, and automation is facilitated.

In the bump sheet section 5, solder groups 2 arranged at equal intervals to the electrode arrangement of the LSI chip are arranged at equal intervals, and slits 3 are formed at various places to avoid heat radiation due to heat conduction. The bump sheet in which four slits are linearly formed so as to surround the bump sheet portion 5 shown in FIG. 1 has high strength against deformation during conveyance, but has large heat radiation from corner portions sandwiched between the slits. Therefore, as shown in FIG. 2, an L-shaped slit 4 may be formed at a corner depending on the bump arrangement or the size of the chip.

(Second Specific Example) FIGS. 3 to 8 are views showing the structure of a bump sheet according to a second specific example according to the present invention.

Hereinafter, the third example will be described in more detail.

FIG. 3 is a sectional view showing the structure of the bump sheet. Solder arranged at the same position as the LSI electrode pattern is formed on SUS303 which does not contain Ni in which Sn in the solder reacts relatively easily. The SUS303 substrate is composed of a bump sheet part 5 to which solder is fixed and a frame part 6 used for transportation. This configuration is the simplest structure and is inexpensive.

FIG. 4 is a sectional view showing another structure of the bump sheet. The substrate 1 is made of an inexpensive material with good workability, such as Cu or 42 alloy, which is well soldered and used for a lead frame. A resin layer 11 is provided to ensure the releasability of the solder 2, and a Cu layer is further formed on the resin layer 11.
Was formed, and the solder 2 was formed on the Cu thin film 12. Here, the resin layer 11 is formed of polyimide,
The thickness of the Cu thin film 12 is adjusted so that the Cu thin film 12 is solid-dissolved in the solder, the fluctuation of the melting point is reduced, and the Cu can be separated from the polyimide 11 by dissolving into the solder 2. The solder 2 on the bump sheet 1 has a diameter of 100 μm and a height of 60 μm.
The thickness 12 of Cu is 0.1 μm to 1 μm. This sheet has characteristics that the workability of the frame and the slit is good and the molten solder 2 can be easily separated from the bump sheet 1.

FIG. 5 shows a structure devised to further improve the releasability of the bump sheet of FIG. 3. A small-diameter portion 14 made of solder and having a small diameter is formed on the bump sheet 1. The large diameter portion 15 is fixed to the solder 2, and the large diameter portion 15 is fixed on the bump sheet 1 via the small diameter portion 14. In the case of this configuration, since the contact area between the bump sheet 1 and the solder 2 is small, the releasability of the solder becomes better. Since the cost is higher than that of the structure shown in FIG. 3, a solder having a relatively large amount of Sn and a solder having a high melting point have a structure like this because it is easily compatible with stainless steel.

FIG. 6 shows that the solder on the bump sheet 1 is
This is the solder paste 2A. By printing the solder paste before the transfer, the cost can be reduced.

FIG. 7 shows a configuration in which a concave portion 18 is formed in the bump sheet 1 and a solder paste 2 A is fixed on the concave portion 18 so as to cover the concave portion 18. In this configuration, the amount of solder can be increased, so that there is a feature that the solder ball can be formed large.

FIG. 8 shows that the solder balls 2B are placed in the concave portions 18 of the bump sheet 1 in which the concave portions 18 are formed.
1 is a bump sheet fixed by 1. Peeling is easier than any of the sheets in FIGS. FIG. 7 may be temporarily melted to form the configuration shown in FIG.

(Third Specific Example) FIGS. 9 to 11 show a bump forming apparatus and a method of forming the same according to a third specific example of the present invention. FIG. 12 is a block diagram of the bump forming apparatus. In these figures, there is shown a bump forming apparatus for aligning a bump sheet 1 with a semiconductor chip 22 and transferring a solder 2 fixed on the bump sheet 1 to the semiconductor chip 22. A bump sheet fixing device 31 for placing and fixing the sheet 1 thereon, and a chip fixing device 32 provided on the bump sheet fixing device 31.
A heating device 42 for heating the semiconductor chip 22 to a predetermined temperature; and a movable control device 40 for bringing the semiconductor chip 22 of the chip fixing device 32 into contact with the solder 2 of the bump sheet 1 on the bump sheet fixing device 31. And a bump forming apparatus provided with a heating device 41 for heating the bump sheet 1 on the bump sheet fixing device 31 to a predetermined temperature. The sheet is fixed by the spacer 50, and the bump sheet fixing device 3 is fixed by the spacer 54.
A bump forming apparatus characterized in that a gap between the chip fixing device 32 and the chip fixing device 32 is maintained at a predetermined distance, and furthermore, a semiconductor chip 22 of the chip fixing device 32 and a bump sheet on the bump sheet fixing device 31 are provided. 1 solder 2
The bump forming apparatus is provided with a time control device 45 for controlling a contact time with the bump forming device.

Hereinafter, this specific example will be described in detail.

First, a method of forming a solder bump shown in FIG. 9 will be described.

The bump sheet 1 on which a predetermined amount of solder 2 has been formed is placed on the stage of the bump sheet fixing device 31 in advance, and the flux is supplied. At this time, bump sheet 1
Are heated to an appropriate temperature by a heating device 41. The chip 22 is positioned and fixed by the positioning section 55 of the chip fixing device 32, the solder 2 is brought into contact with the electrode 22 a of the LSI chip 22 by the movable control device 40, and pulse heat heating is performed by the pulse heating device 42. The solder 2 is melted by heat conduction from the electrodes 22a of the LSI chip 22, and when all the solder 2 is melted, it becomes spherical due to surface tension, and at the same time, the electrodes 22a of the LSI chip 22 and the solder 2 are joined. .

At this time, when the bump sheet 1 reaches the soldering temperature due to heat conduction from the LSI chip 22,
Since the bump sheet 1 and the solder 2 are bonded and cannot be separated, the solder 2 is melted. However, the bump sheet 1 is cooled to a temperature before the soldering temperature is reached, or the LSI chip 22 is raised. The LSI chip 22
And the bump sheet 1 are separated.

As another method, pulse heating is also used for heating the bump sheet 1. In this case, 0.001
By starting heating the bump sheet 1 at intervals of about 3.0 seconds, the solder 2 on the bump sheet 1
It is possible to perform the melt transfer to the electrode 22a of the SI chip 22.

When the solder 2 is melted only by rapid heating of the LSI chip 22, the solder 2 is radiated from the bump sheet 1, so that it takes time to reach a required temperature.
To prevent this, the bump sheet 1 is previously heated to an appropriate temperature.

There are two types of chip fixing devices used here. The first method is a flat type as shown in FIG. 9, and it is necessary to provide the device with a highly accurate position control function. Another method is a type shown in FIG. 10 in which a counterboring process for positioning is performed on a suction tool of a chip fixing device, and the gap between the chip fixing device and the bump sheet fixing device can be maintained at a predetermined interval. In this case, the bump height is maintained at a predetermined height only by abutting the tip of the positioning portion 55 of the chip fixing device 32 against the bump sheet 1, and the control system of the device performs load control.

FIG. 11 shows a spacer 5 separately from the suction tool.
4 is prepared, and when the bump sheet 1 transported by the frame by the spacer 54 comes to a predetermined position, the bump sheet 1 is pressed against the bump sheet suction tool, and the next step
The chip fixing device 32 sucking the SI chip 22 descends, stops at a predetermined position set by the spacer 54, and starts transfer at this position. With this method, the structure of the chip fixing device 32 can be simplified.

Accordingly, the bump forming apparatus includes a rail capable of transporting a bump sheet processed into a predetermined shape,
A storage device for storing chips before bump formation, a chip fixing device capable of positioning and adsorbing chips, a bump sheet fixing device capable of adsorbing and fixing the back surface of a bump sheet, and storing a bump transfer sheet, It comprises a device having a function of sequentially supplying, a pulse heat tool for heating a semiconductor chip of a chip fixing device, and a pulse heat tool for heating a bump sheet of a bump sheet fixing device.

As described above, the bump forming method according to the present invention aligns the bump sheet with the semiconductor chip,
A bump forming method for transferring solder fixed on the bump sheet to the semiconductor chip, comprising: a first step of positioning and fixing the bump sheet on a bump sheet fixing device; A second step of positioning and fixing the semiconductor chip in a chip fixing device for fixing the semiconductor chip, contacting the semiconductor chip with solder on the bump sheet, and fixing the semiconductor chip to a predetermined position. By heating to temperature,
A third step of making the solder on the bump sheet spherical, and transferring the spherical solder to the semiconductor chip.

A first step of positioning and fixing the bump sheet on the bump sheet fixing device; and positioning the semiconductor chip on a chip fixing device provided above the bump sheet fixing device and fixing the semiconductor chip. A second step of heating the semiconductor chip to a predetermined temperature, contacting the semiconductor chip with solder on the bump sheet, making the solder on the bump sheet spherical, A third step of transferring the spherical solder to the chip.

In the first step, when the bump sheet is heated to a temperature at which the solder does not melt, the transfer can be performed in a shorter time.

[0040]

As described above, the bump sheet, the bump forming apparatus and the bump forming method using the same according to the present invention can transfer a large amount of solder in a short time with high reliability.

[Brief description of the drawings]

FIG. 1 is a view showing a bump sheet according to a first specific example of the present invention.

FIG. 2 is a diagram showing another specific example of a bump sheet.

FIG. 3 is a cross-sectional view showing a second embodiment of the present invention and showing solder formed on a bump sheet.

FIG. 4 is another sectional view showing the solder formed on the bump sheet.

FIG. 5 is another sectional view showing the solder formed on the bump sheet.

FIG. 6 is another cross-sectional view showing the solder formed on the bump sheet.

FIG. 7 is another cross-sectional view showing the solder formed on the bump sheet.

FIG. 8 is another cross-sectional view showing the solder formed on the bump sheet.

FIG. 9 is a view showing a third specific example of the present invention and showing a bump forming step.

FIG. 10 is a view showing another bump forming step of the third specific example of the present invention.

FIG. 11 is a view showing another bump forming step of the third specific example of the present invention.

FIG. 12 is a block diagram showing a configuration of a bump forming apparatus according to a third specific example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bump sheet 2 Solder 2A, 2B Solder paste 3 Slit 3a Linear slit 4 L-shaped slit 5 Bump sheet part 6 Transfer margin (frame part) 11 Resin layer 12 Cu thin film 14 Small diameter part 15 Large diameter part 18 Concave part Reference Signs List 20 flux 31 bump sheet fixing device 32 chip fixing device 40 movable control device 41 first heating device 42 second heating device 45 time control device 54 spacer 55 positioning portion

Claims (13)

[Claims] 1. A bump sheet for aligning a bump sheet with a semiconductor chip and transferring solder fixed on the bump sheet to the semiconductor chip, wherein the bump sheet has a strip shape or a tape shape. A bump sheet, wherein a slit is formed so as to surround the solder group to be transferred. 2. The bump sheet according to claim 1, wherein the slit is formed linearly. 3. The bump sheet according to claim 1, wherein the slit is formed in an L shape. 4. A bump sheet for aligning a bump sheet with a semiconductor chip and transferring a solder fixed on the bump sheet to the semiconductor chip, wherein a resin layer is provided on the bump sheet. A bump sheet, wherein a copper thin film is formed on the resin layer, and solder for transfer is fixed on the copper thin film. 5. A bump sheet for aligning a bump sheet with a semiconductor chip and transferring solder fixed on the bump sheet to the semiconductor chip, wherein the bump sheet is formed of solder. A solder sheet comprising a small-diameter portion having a small diameter and a large-diameter portion having a large diameter is fixed, and the large-diameter portion is fixed on the bump sheet via the small-diameter portion. . 6. A bump sheet for aligning a bump sheet with a semiconductor chip and transferring solder fixed on the bump sheet to the semiconductor chip, wherein the bump sheet has a recess formed therein. A bump sheet wherein solder is fixed on the concave portion so as to cover the concave portion. 7. A bump forming apparatus for aligning a bump sheet with a semiconductor chip and transferring solder fixed on the bump sheet to the semiconductor chip, wherein the bump sheet is placed and fixed. A bump sheet fixing device, a chip fixing device provided on the bump sheet fixing device and fixing the aligned semiconductor chip, a heating device for heating the semiconductor chip to a predetermined temperature, and a chip fixing device. A bump forming apparatus, comprising: a movable control device for bringing a semiconductor chip into contact with solder of a bump sheet on the bump sheet fixing device. 8. The bump forming apparatus according to claim 7, further comprising a heating device for heating the bump sheet on the bump sheet fixing device to a predetermined temperature. 9. The bump according to claim 7, wherein said bump sheet is fixed by a spacer, and said spacer keeps a predetermined distance between said bump sheet fixing device and said chip fixing device. Forming equipment. 10. The bump forming apparatus according to claim X, further comprising a time control device for controlling a contact time between a semiconductor chip of the chip fixing device and solder of a bump sheet on the bump sheet fixing device. . 11. A bump forming method for aligning a bump sheet with a semiconductor chip and transferring solder fixed on the bump sheet to the semiconductor chip, wherein the bump sheet is mounted on a bump sheet fixing device. A first step of positioning and fixing the semiconductor chip; a second step of positioning and fixing a semiconductor chip on a chip fixing device provided above the bump sheet fixing device; and a step of fixing the semiconductor chip and the solder on the bump sheet. And heating the semiconductor chip to a predetermined temperature to make the solder on the bump sheet spherical and to transfer the spherical solder to the semiconductor chip. A bump forming method characterized by the above-mentioned. 12. A bump forming method for aligning a bump sheet with a semiconductor chip and transferring solder fixed on the bump sheet to the semiconductor chip, wherein the bump sheet is mounted on a bump sheet fixing device. A first step of positioning and fixing the semiconductor chip; and a second step of positioning and fixing the semiconductor chip on a chip fixing device provided on the bump sheet fixing device, and heating the semiconductor chip to a predetermined temperature. Contacting the semiconductor chip and the solder on the bump sheet to make the solder on the bump sheet spherical,
A third step of transferring the spherical solder to the semiconductor chip. 13. The bump forming method according to claim 11, wherein in the first step, the bump sheet is heated to a temperature at which the solder does not melt.