JPH11312700A - Bump forming method and electronic device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable small bumps to be surely formed by a method, wherein a solder ball is made to project more as compared with its size in a bump forming method, and an electronic device. SOLUTION: A metal paste 16 is filled into recesses 14 provided to a first plate 10, the metal paste 16 filled into the recesses 14 is formed into solder balls 19, the metal paste 16 is filled into recesses 24 provided to a second plate 20, the plates 10 and 20 are made to face opposite each other and heated, solder balls 26 equivalent in volume to the total amount of solder paste filled into the recesses 14 and 24 formed in the recesses 14 of the plate 10 located under the plate 20, the plate 20 is removed, and solder balls 26 located in the recesses 14 of the plate 10 are transferred onto a device on which solder bumps are to be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a metal bump such as a solder bump and an electronic device having such a bump.

[0002]

2. Description of the Related Art In information processing apparatuses for processing a large amount of information at high speed, LSIs and VLSIs in which electronic circuits and electronic components are integrated on a semiconductor chip are often used. In order to attach a semiconductor chip on which an electronic circuit is integrated to, for example, a ceramic substrate, metal bumps such as solder bumps are provided on the semiconductor chip or the ceramic substrate, and the semiconductor chip is fixed to the ceramic substrate by welding the solder bumps. Connection can be made. For this purpose, it is necessary to form solder bumps on a semiconductor chip or a ceramic substrate.

Japanese Patent Application Laid-Open Nos. 7-249631 and 9-36118 disclose a method of providing solder bumps on an electronic component such as a semiconductor chip using a bump-forming plate having a plurality of concave portions. in this way,
A concave portion is formed on the surface of a flat bump forming plate, a solder paste is filled into the concave portion of the bump forming plate by squeezing, and the bump forming plate is heated to convert the solder paste in the concave portion into a solder ball. The solder balls are transferred from the plate to the semiconductor chip by bringing the semiconductor chip close to the plate.

[0004] By filling the recesses of the bump forming plate with solder paste by squeezing, the surface of the solder paste becomes flush with the surface of the bump forming plate, and a certain amount of solder paste is filled in each recess. You. The solder component of the solder paste in the concave portion of the bump forming plate is heated and melted, rounded by surface tension, and becomes a solder ball. The top of the solder ball protrudes upward from the surface of the bump forming plate while being held in the concave portion of the bump forming plate. Therefore, when the semiconductor chip is brought closer to the bump forming plate, the electrode pad on the surface of the semiconductor chip contacts the top of the solder ball with a small gap between the surface of the semiconductor chip and the surface of the bump forming plate. . Thus, the solder balls can be transferred from the bump forming plate to the semiconductor chip.

According to this method, the solder bumps are accurately arranged corresponding to the positions of the recesses of the bump forming plate, and the size of the solder balls is reduced by the amount of the solder paste filled in the recesses of the plate (ie, the recesses). ), The bumps can be formed accurately at low cost. In particular, when a silicon plate is used as a bump formation plate and concave portions are formed by performing anisotropic etching on the silicon plate, many minute concave portions can be accurately formed at a small pitch. It is suitable for forming bumps on a semiconductor chip having high-density wiring.

[0006]

However, as the wiring of the semiconductor chip becomes narrower and denser, the solder bump to be formed becomes smaller, and the top of the solder ball projects upward from the surface of the bump forming plate. The amount of protrusion is reduced. Therefore, if the surface of the bump forming plate or the surface of the semiconductor chip has a small distortion, a very small portion of the solder balls may not be transferred from the bump forming plate to the semiconductor chip and may be defective.

In addition, when the gap between the surface of the semiconductor chip and the surface of the plate becomes smaller at the time of transferring the solder balls, the foreign matter may enter the semiconductor when the foreign matter enters between the bump forming plate and the semiconductor chip. There is a possibility that the semiconductor chip is pressed against the chip and the surface of the semiconductor chip is damaged, or a foreign substance adheres to the wiring of the semiconductor chip. Accordingly, it is desired that the amount of protrusion of the top of the solder ball from the surface of the bump forming plate to be relatively large even if the size of the solder ball becomes small.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of forming a bump and a method of forming a bump in such a manner that the amount of protrusion of the solder ball can be increased relative to the size of the solder ball to be formed, so that a small bump can be reliably formed. To provide an electronic device including a device having a bump.

[0009]

According to a method of forming a bump according to the present invention, a plurality of recesses in a first plate are filled with a metal paste by squeezing, and the plurality of metal pastes are arranged mirror-symmetrically to the recesses in the first plate. Filling the metal paste by squeezing into the concave portion of the second plate having the concave portion,
The concave portion of the first plate and the concave portion of the second plate are aligned to face the first plate and the second plate, and the first and second plates are heated to A metal ball is formed in one of the concave portions of the first and second plates, and the other of the first and second plates is moved from one of the first and second plates to form the first and second plates. The method is characterized in that a metal ball located in one concave portion of a plate is transferred to a device on which a bump is to be formed.

[0010] The metal paste is composed of, for example, metal particles such as solder particles and flux and the like, and is filled into the recesses of the first and second plates by squeezing, respectively. The surface of the solder paste is flush with the surfaces of the first and second plates, and a certain amount of solder paste is filled in each recess. Then, the first plate and the second plate are overlapped, and the first and second plates are overlapped.
Is heated, the metal particles in the metal paste are melted and rounded to form metal balls.

Since the concave portion of the first plate and the concave portion of the second plate are aligned, the molten metal component of the metal paste in one concave portion of the first plate and one concave portion of the second plate And the molten metal component of the metal paste therein are combined into one metal ball. The metal ball is located in one of the recesses of the first and second plates with its top protruding. Then, the other plate is moved from the one plate. Then, the metal ball located in one of the concave portions of the first and second plates is transferred to a device where a bump is to be formed.

In the present invention, the sum of the amount of the metal paste filled in one concave portion of the first plate and the amount of the metal paste filled in one concave portion of the second plate is determined by one metal ball. It is the amount of metal paste required to form. That is, the sum of the volume of one recess of the first plate and the volume of one recess of the second plate is 1
It is the volume required to form one metal ball. The metal ball is finally held in one of the recesses of the first and second plates, and the formed metal ball is large in volume of the recess. Thus, the top of the metal ball protrudes considerably from the surface of the plate while being held in the recess.

When a metal ball is transferred from one plate to an apparatus on which bumps are to be formed, the gap between the plate and the apparatus on which bumps are to be formed is relatively large.
The metal ball contacts the electrode pad of the device where the bump is to be formed. That is, the transfer of the metal ball can be performed in a state where the gap between the plate and the device on which the bump is to be formed is larger than the same gap in the related art.

Therefore, even if the wiring of the device on which the bump is to be formed has a narrow pitch and a high density, the metal balls are reliably transferred from the plate to the device, and the surface of the semiconductor chip is damaged or foreign matter is removed. It is prevented from adhering to the wiring of the chip. Preferably, in the step of overlapping the first and second plates, the first and second plates are overlapped such that one of the first and second plates is below the other. This way,
The metal ball will be formed in the recess of the plate located below.

Preferably, before the first plate and the second plate are overlapped with each other, a step of heating one of the first and second plates to form a metal ball in a concave portion thereof is included. By doing so, the plate on which the metal ball is not formed is placed above the plate on which the metal ball is formed, and the two are overlapped, and the first and second plates are heated to form the metal ball.

Preferably, the first and second plates are made of silicon, and the concave portions are formed in the silicon plate by anisotropic etching. Alternatively, the first and second plates are made of photosensitive glass, and the concave portions are formed by etching the photosensitive glass. Alternatively, the first and second plates are formed by forming a replica mold having a convex portion on an existing plate by plating deposition method, and molding based on the replica mold.

Preferably, the melting point of the metal particles of the metal paste filling one of the recesses of the first and second plates is higher than the melting point of the metal particles of the metal paste filling the recess of the other plate. Thus, a metal ball having a composite structure in which the core portion is made of a metal having a high melting point and the outer peripheral portion is made of a metal having a low melting point is obtained. Further, the present invention provides an electronic device including a device having a bump formed by the above-described bump forming method.

[0018]

1 and 2 are views showing a method for forming a bump according to a first embodiment of the present invention. FIG. 1 shows steps up to the formation of a metal ball, and FIG. 2 shows steps of transferring and forming the metal ball. In FIG. 1A,
A first (for bump formation) plate 10 having a concave portion 14 on the surface 12 is prepared, and the concave portion 14 is filled with a metal paste 16. The filling of the metal paste 16 is performed by squeezing performed while moving the squeegee 18 in the direction of arrow A. The metal paste 16 is made of, for example, metal particles such as solder particles and a flux, and the surface of the solder paste 16 becomes the first by squeezing.
And a predetermined amount of solder paste 16 is filled in each recess 14. The concave portion 14 is formed corresponding to the position of the electrode pad of the semiconductor chip or the circuit board on which the bump is to be formed.

In FIG. 1B, a first plate 10
Is heated, the metal particles in the metal paste 16 are melted and rounded by the surface tension to form the metal balls 19. The components in the flux of the metal paste 16 partially evaporate and remain in the recesses 14 in a non-volatile manner. The non-volatile components hold the metal ball 19 in the recess 14. In FIG. 1 (C), a second (bump forming) plate 20 having a concave portion 24 on the surface 22 is prepared, and the metal paste 1
Fill 6. The recess 24 of the second plate 20 is
And the concave portion 14 of the plate 10 are arranged mirror-symmetrically. In the embodiment, the volume of the concave portion 24 is the same as the volume of the concave portion 14. The filling of the metal paste 16 is performed by squeegeeing using a squeegee 18. Due to the squeezing, the surface of the solder paste 16 becomes flush with the surface of the second plate 20, and a certain amount of the solder paste 16 is filled in each recess 24. The metal paste 16 of FIG. 1C may be the same as the metal paste 16 of FIG. 1A, or may be different from the metal paste 16 of FIG.

Note that the step of FIG. 1C can be performed before the step of FIG. 1A and FIG. 1B, or the step of FIG. 1A and FIG. It can be done at the same time. In FIG. 1 (D), the first plate 10 and the second plate 20 face each other by aligning the recess 14 of the first plate 10 with the recess 24 of the second plate 20. In this case, there is a slight gap between the surface 12 of the first plate 10 and the surface 22 of the second plate 20.

In FIG. 1E, the first and second plates 10 and 20 are heated to form metal balls 26 in the recesses 12 of one of the first and second plates 10. In the case of high-temperature solder, it is heated to about 350 ° C. In the embodiment, the first plate 10 on which the metal balls 19 have been formed in advance is located below the second plate 20. Therefore, the metal component of the metal paste 16 filled in the concave portion 24 of the second plate 20 melts and flows down onto the metal ball 19 of the lower first plate 10, and a part of the metal ball 19 of the first plate 10. Into the concave portion 14 of FIG. First plate 1
The 0 metal ball 19 melts, but maintains a substantially round shape. Thus, the molten metal flowing from the concave portion 24 of the second plate 20 is transferred to the metal ball 1 of the first plate 10.
9 and becomes a larger metal ball 26.

As described above, the concave portion 1 of the first plate 10
4 and the recess 24 of the second plate 20 are aligned, so that the metal ball to be formed in one recess 14 of the first plate 10 and one recess 24 facing that of the second plate 20. Are combined with each other to form one metal ball 26. The metal ball 26 is located in the recess 14 of one of the first and second plates 10 with its top protruding.

Then, the upper second plate 20 is moved from the lower first plate 10. Metal ball 2
6 is held in the concave portion 14 of the lower plate 10 with little positional variation. In FIG. 2A, an apparatus 30 on which a bump is to be formed is pressed against the first plate 10 under heating, and a metal ball 26 located in the concave portion 14 of the first plate 10 is transferred to the apparatus 30 on which a bump is to be formed. I do. In this case, the heating temperature is about 280 ° C., and the metal balls 26 are not completely melted, but the flux is melted to facilitate the transfer of the metal balls 26. The device 30 on which the bump is to be formed has an electrode pad 32 at a position corresponding to the concave portion 14.
And the metal ball 26 adheres to the electrode pad 32.
After that, the electrode pad 32 and the metal ball 26 are more reliably fused by heating to about 350 ° C. in a nitrogen atmosphere. Then, the first plate 10 is moved from the device 30 on which the bump is to be formed.

FIG. 2B shows the metal bump 34 thus formed, and FIG. 2C shows the metal bump 34 after reheating.
It is a figure which shows the place where it shape | molded. The device 30 on which the bump is to be formed is, for example, a semiconductor chip, and the metal bump 34
The device 30 molded with can be further attached to a circuit board by metal bumps 34. The device 30 on which the bump is to be formed is not limited to a semiconductor chip.
For example, any device that requires a bump such as a BGA or a circuit board can be used.

In FIG. 2A, when the metal ball 26 is transferred from the first plate 10 to the device 30 where a bump is to be formed, a gap D is formed between the first plate 10 and the device 30.
And the pressing pressure is set so as to be present between. The appropriate gap D depends on the amount of protrusion of the metal ball 26 from the surface 12 of the first plate 10. In the present invention, the sum of the amount of the metal paste 16 filled in one recess 14 of the first plate 10 and the amount of metal paste 16 filled in one recess 24 of the second plate 20 is:
This is the amount of the metal paste required to form one metal ball 26. That is, one of the first plates 10
The sum of the volume of one recess 14 and the volume of one recess 24 of the second plate 20 is the volume required to form one metal ball 26. Therefore, finally the first
Ball 26 held in the recess 14 of the plate 10
Project greatly from the surface 12 of the first plate 10.

Therefore, when transferring the metal balls 26 from the second plate 10 to the device 30 for forming bumps, the first plate 10 and the device 30 for forming bumps are transferred.
In a state where the gap D is relatively large, the metal ball 26 contacts the electrode pad 32 of the device 30 on which the bump is to be formed. That is, the transfer of the metal balls 26 can be performed in a state where the gap D between the first plate 10 and the device 30 on which the bump is to be formed is larger than the same gap in the related art.

Therefore, even if the wiring of the device 30 on which bumps are to be formed has a narrow pitch and a high density, the metal balls 26 are reliably transferred from the first plate 10 to the device 30, and the surface of the semiconductor chip is not damaged. And adhesion of foreign matter to the wiring of the semiconductor chip is prevented. The device 30 on which the metal bumps 34 are formed in this manner is further mounted on another device such as a circuit board using the metal bumps 34, and constitutes an electronic device including the device 30 having the bumps.

FIG. 3 is a view showing a method of forming a bump according to a second embodiment of the present invention. In FIG. 3A, the surface 1
First, a first (bump forming) plate 10 having a concave portion 14 is prepared, and the concave portion 14 is filled with a metal paste 16. The filling of the metal paste 16 is performed by squeegeeing using a squeegee 18. In this embodiment, FIG.
There is no formation of the metal ball 19 in the first plate 10 of (B). However, it is better to form the metal balls 19 in advance, since the first plate 10 and the second plate 2
In some cases, it is easy to perform positioning when facing 0.

In FIG. 3B, a concave portion 24 is formed on the surface 22.
Is prepared, and the recess 24 is filled with the metal paste 16. The recess 24 of the second plate 20 is connected to the recess 1 of the first plate 10.
Reference numeral 4 denotes a mirror-symmetric arrangement. Metal paste 1
The filling of 6 is performed by squeegeeing using a squeegee 18. By squeezing, the solder paste 16
Is flush with the surface of the second plate 20, and a certain amount of solder paste 16 is filled in each recess 24. The step in FIG. 3B can be performed before, after, or simultaneously with the step in FIG.

In FIG. 3C, the first plate 10
The concave portion 14 of the second plate 20 is aligned with the concave portion 14 of the second plate 20 so that the first plate 10 and the second plate 20 face each other. In this state, the first and second plates 1
The metal balls 26 are formed in the recesses 12 of the lower first plate 10 by heating 0 and 20. In this case, FIG.
Although there is no metal ball 19 as shown in FIG.
Paste 16 in one recess 14 of plate 10
Molten metal component and one recess 24 of the second plate 20
And the molten metal component of the metal paste 16 in the
Metal balls 26.

In FIG. 3D, when the upper second plate 20 is moved from the lower first plate 10,
The metal ball 26 is located in the recess 14 of the first plate 10.
It is located with its top protruding. Then Figure 2
As shown in (A), the metal balls 26 are transferred from the first plate 10 to the device 30 where bumps are to be formed. Apparatus 3 having metal bumps 34 formed in this way
Reference numeral 0 denotes an electronic device including the device 30 having a bump, which is further mounted on another device such as a circuit board using the metal bump 34.

FIG. 4 shows the first plate 10 of FIGS.
FIG. 5 is a plan view showing an example (and the second plate 20), and FIG. 5 is a sectional view taken along line VV in FIG. In this example, the first plate 10 (the second plate 2
0) is made of a silicon plate whose surface 12 has a <100> crystal plane, and the concave portion 14 is formed by forming a mask having a square opening on the surface 12 and performing anisotropic etching. . The recess 14 has the shape of a regular square pyramid.

FIG. 6 shows the first plate 10 of FIGS.
FIG. 7 is a perspective view showing another example of the plate (and the second plate 20), and FIG. 7 is a view for explaining a concave portion of the plate of FIG.
In this example, the first plate 10 (the second plate 20) is made of a silicon plate whose surface 12 is a <110> crystal plane, and the recess 14 forms a mask having a diamond-shaped opening in the surface 12. It is formed by performing anisotropic etching. The recess 14 has a diamond-shaped opening, and has a bottom surface 14 a inclined with respect to the surface 12 and four side surfaces 14 b substantially perpendicular to the surface 12.

When the first plate 10 (second plate 20) is formed of a silicon plate and the recesses 14 are formed by performing anisotropic etching, a large number of minute recesses 14 (24) are formed. It can be formed accurately.
For example, the diameter of the metal ball 26 to be formed is 70 to 100.
μm, and the pitch between the concave portions 14 (24) is 150 to 2
The first plate 10 (second plate 20) having a thickness of 00 μm can be formed with good reproducibility. A concave portion 14 (24) formed by performing anisotropic etching on a silicon plate whose surface 12 becomes a <110> crystal plane.
If the area of the opening is the same as that of the recess 14 (24) formed by performing anisotropic etching on the silicon plate whose surface 12 is a <100> crystal plane,
The volume increases.

FIG. 8 shows the first plate 10 of FIGS.
FIG. 14 is a cross-sectional view illustrating another example (and the second plate 20). The first plate 10 (and the second plate 20) are made of photosensitive glass, and the concave portions 14 are formed by etching the photosensitive glass. In the present invention, FIG.
5 and the plates of FIGS. 6 and 7, and the plate of FIG.
And the second plate 20.

Further, in the present invention, the plates of FIGS. 4 and 5, the plates of FIGS. 6 and 7, and the plate of FIG. 8 are used for replica production, and the first plate 10 and the second plate 20 are used. It can be molded based on the replica. For example, in FIG.
Reference numeral 100 denotes a plate corresponding to the plate 10 in FIGS. 4, 5, 6, 7, 8, and the like. In FIG. 9B,
A metal film 102 of Ni or the like is formed on the plate 100 by a plating deposition method or the like. In FIG. 9C, the plate 100 is released from the metal film 102, and a replica mold 102A symmetrical to the plate 100 and having a convex portion 104 is formed. In FIG. 9D, N is again formed on the replica mold 102A manufactured in FIGS.
A metal 106 such as i is formed to a required thickness. FIG. 9 (E)
Then, after releasing the replica mold 102A from the metal film 106,
The metal film 106 is subjected to post-processing and the like, and the plate 10
Replica plate 1 with same pattern and same shape as 0
06A is completed. This plate C106A can be used as the first plate 10 and the second plate 20.

Table 1 below shows Example 1 and Comparative Example 1 when forming a metal ball 26 having a diameter of 100 μm.
In the first embodiment, the concave portion 14 of the first plate 10 and the concave portion 24 of the second plate 20 are both shown in FIGS.
The size of the concave portion 24 is the same as the size of the concave portion 14. Comparative Example 1 is a case where a single metal plate having a diameter of 100 μm is formed by using a single plate having a concave portion having a rhombic opening. The unit is μm, and the side length of the concave portion is the length of one side of the diamond-shaped opening.

Table 1 Concave Side Length Concave Depth Ball Protrusion Amount Gap D Comparative Example 1 165 97 37 15 Example 1 131 77 57 35 According to Example 1, the ball protrusion amount is 20 compared to the comparative example.
μm, gap D during transfer load is also 15 μm to 35 μm
Increased to

Table 2 below shows Example 2 and Comparative Example 2 similar to Table 1 when the recesses 14 and 24 have a structure having the square openings shown in FIGS. FIG. Table 2 Recess side length Recess depth Depth of ball protrusion Gap D Comparative example 2 194 137 297 Example 2 154 109 57 35 FIG. 10 is a diagram showing a bump forming method according to a third example of the present invention. This embodiment is basically the same as the embodiment of FIG. 1, and will be described briefly. However, the concave portion 14 of the first plate 10 has a structure having a square opening shown in FIGS.
Has a diamond-shaped opening shown in FIGS. 6 and 7. The recess 24 having the diamond-shaped opening shown in FIGS. 6 and 7 is smaller in depth than the recess 14 having the square opening shown in FIGS. Because of its good shape, it is better to be on the upper side when facing.

Referring to FIG. 10A, the metal paste 16 is filled in the recess 14 of the first (bump forming) plate 10 by squeezing. In FIG. 10B,
The first plate 10 is heated to form a metal ball 19 in the recess 14. Next, in FIG. 10C, the metal paste 16 is filled in the recess 24 of the second (for bump formation) plate 20 by squeezing. FIG. 10 (D)
In the above, the concave portion 14 of the first plate 10 and the concave portion 24 of the second plate 20 are aligned, and the first plate 10 and the second plate 20 are opposed to each other. Then, in FIG. 10 (E), the first and second plates 1
The metal balls 26 are formed in the concave portions 12 of the first plate 10 by heating 0 and 20.

Then, the upper second plate 20 is moved from the lower first plate 10 and, as shown in FIG. The metal ball 26 located in the concave portion 14 of the first plate 10 is transferred to the device 30 where a bump is to be formed. Thereafter, the device 30 such as a semiconductor chip on which the metal bumps are formed in this way is further mounted on another device such as a circuit board using the metal bumps,
An electronic device including the device 30 having a bump is configured.

FIG. 11 is a view showing a method of forming a bump according to a fourth embodiment of the present invention. This embodiment is basically the same as the embodiment of FIG. 1, and will be described briefly. However, the metal paste 16a filled in the concave portion 14 of the first plate 10 contains high-temperature solder, and the second plate 20
The metal paste 16b filled in the concave portion 24 contains low-temperature solder.

In FIG. 11A, the metal paste 16a is filled in the concave portion 14 of the first (bump forming) plate 10 by squeezing. In FIG. 11B, the first plate 10 is heated to form a metal ball 19 in the recess 14. Next, in FIG. 11C, the metal paste 16b is filled in the recess 24 of the second (for bump formation) plate 20 by squeezing. FIG.
(D), the concave portion 14 of the first plate 10 and the second
The first plate 10 and the second plate 20 face each other by aligning the concave portions 24 of the plate 20 with each other. Then, in FIG. 11E, the first and second plates 10 and 20 are heated so that the concave portions 12 of the first plate 10 are heated.
A metal ball 26 is formed on the substrate.

The metal paste 16a filled in the concave portion 14 of the first plate 10 is made of a high melting point solder (for example, Sn).
5 / Pb95), and the melting temperature of this solder is 270 ° C. of solidus and 315 ° C. of liquidus. Second plate 20
The metal paste 16b filled in the concave portion 24 contains a low melting point solder (for example, Sn63 / Pb37), and the eutectic temperature of this solder is 183 ° C. Therefore, FIG.
In the case of forming the metal ball 19 in FIG.
It is heated to about 0 ° C., but when forming the metal ball 26 in FIG.
It is good to heat to about 0 ° C. In this case, the metal ball 2
The core 26a has a high-temperature solder, and the outer periphery 26b has a composite structure in which the low-temperature solder covers the core 26a.

Then, the upper second plate 20 is moved from the lower first plate 10, and as shown in FIG. 2A, the apparatus 30 on which the bumps are to be formed is heated to the first position. The metal ball 26 located in the concave portion 14 of the first plate 10 is transferred to the device 30 where a bump is to be formed. Thereafter, the device 30 such as a semiconductor chip on which the metal bumps are formed in this way is further mounted on another device such as a circuit board using the metal bumps,
An electronic device including the device 30 having a bump is configured. By using the solder ball 26 as a bump electrode, it is possible to form a mounted body having good mountability and being resistant to stress.

[0046]

As described above, according to the present invention,
By increasing the amount of ball protrusion from the surface of the plate, the variation in the position of the metal balls (bumps) is small,
The number of untransferred (defective) bumps is reduced, the gap between the plate and the device such as a semiconductor chip at the time of transfer is increased, and the damage to the device surface due to foreign matter being caught is reduced.

[Brief description of the drawings]

FIG. 1 is a view illustrating a method of forming a bump according to a first embodiment of the present invention.

FIG. 2 is a view showing a step that follows the step of FIG. 1;

FIG. 3 is a view illustrating a method of forming a bump according to a second embodiment of the present invention.

FIG. 4 is a plan view showing an example of the plate of FIGS. 1 to 3;

FIG. 5 is a sectional view taken along line VV in FIG. 4;

FIG. 6 is a perspective view showing another example of the plate shown in FIGS. 1 to 3;

FIG. 7 is a view showing a concave portion of the plate of FIG. 6;

FIG. 8 is a sectional view showing another example of the plate of FIGS. 1 to 3;

FIG. 9 is a view showing another example of the plate of FIGS. 1 to 3;

FIG. 10 illustrates a method of forming a bump according to a third embodiment of the present invention.

FIG. 11 is a view illustrating a method of forming a bump according to a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... 1st plate 14 ... recess 16 ... metal paste 18 ... squeegee 19 ... metal ball 20 ... 2nd plate 24 ... recess 26 ... metal ball 30 ... device to form a bump 34 ... metal bump

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[Procedure amendment]

[Submission date] March 31, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

Claims (8)

[Claims] 1. A concave portion of a first plate is filled with metal paste by squeezing, and a concave portion of a second plate having a plurality of concave portions arranged mirror-symmetrically to the concave portion of the first plate. And filling the metal paste with the first plate and the second plate by aligning the concave portion of the first plate with the concave portion of the second plate, and facing the first plate and the second plate. Heating the plate to form a metal ball in one of the recesses of the first and second plates, and moving the other of the first and second plates from one of the first and second plates; A method of forming a bump, comprising: transferring a metal ball located in one of the concave portions of the first and second plates to an apparatus on which a bump is to be formed. 2. The bump according to claim 1, wherein, in the step of overlapping the first and second plates, the first and second plates are overlapped so that one of the first and second plates is below the other. Formation method. 3. A step of heating one of the first and second plates to form a metal ball in a recess thereof before the first plate and the second plate are overlapped. The method for forming a bump according to claim 1, wherein: 4. The bump formation according to claim 1, wherein said first and second plates are made of silicon, and said recesses are formed by anisotropic etching on a silicon plate. Method. 5. The method according to claim 1, wherein the first and second plates are made of photosensitive glass, and the concave portions are formed by etching the photosensitive glass. . 6. A method according to claim 1, wherein the first and second plates are formed by forming a replica mold having a convex portion on the plate by a plating deposition method and molding the replica mold based on the replica mold. A method for forming a bump according to claim 1. 7. The method according to claim 1, wherein the melting point of the metal particles of the metal paste filling one of the recesses of the first and second plates is higher than the melting point of the metal particles of the metal paste filling the recess of the other plate. The method of forming a bump according to claim 1. 8. An electronic device including a device having a bump formed by the bump forming method according to claim 1.