JPH05129307A - Method and apparatus for formation of bump - Google Patents

Abstract

PURPOSE:To form, easily and in a short time, a bump for a semiconductor integrated circuit device using a flip-chip system. CONSTITUTION:The following are installed: a molten-solder tank 18 which melts a solder for bump formation use and which stores the molten solder; and a molten-solder discharge plate 12 in which discharge holes 14 guiding the discharge position of the molten solder 13 flowing through a molten-solder passage pipe 17 from the molten-solder tank 18 have been made. In order to form bumps, the discharge holes 14 in the molten-solder discharge plate 12 are first aligned with substratum metal patterns 8 on a semiconductor wafer 7. In succession, the molten solder 13 from the discharge holes 14 is exposed to an extent that its surface swells due to surface tension; after that, a mounting stand 6 on which the semiconductor wafer 7 is mounted is lowered; the substratum metal patterns 8 are brought into direct contact with the exposed molten solder 13; the molten solder in prescribed quantities is applied to the substratum metal patterns 8; the bumps are formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bump forming method and a device technique, and more particularly to a technique effective when applied to a bump forming technique of a semiconductor integrated circuit device for face down bonding.

[0002]

2. Description of the Related Art As one of the bonding methods representing the face-down bonding technology, there is a flip chip method, for example.

The flip chip method is a method in which a semiconductor chip is mounted on a package substrate or a wiring substrate via a plurality of bumps formed on its main surface.

In this method, for example, since bumps can be formed on the entire area of the main surface of the semiconductor chip, the number of electrodes can be increased without increasing the chip size and the bonding area can be reduced. Therefore, the packaging density of the semiconductor chips can be easily improved.

Typical examples of the bump forming method in such a conventional flip-chip type semiconductor integrated circuit device include a metal mask vapor deposition method and a lift-off method.

The metal mask vapor deposition method is a method of forming bumps using a metal mask as a vapor deposition mask, and has been, for example, as follows.

First, a metal mask is aligned and placed on the main surface of a semiconductor wafer on which an underlying metal pattern is formed. Holes are formed in the metal mask at positions facing the underlying metal pattern on the semiconductor wafer.

Then, using the metal mask as a vapor deposition mask, a first metal film made of, for example, lead (Pb) and a second metal film made of tin (Sn) are sequentially vapor-deposited on the semiconductor wafer.

At this time, by adjusting the thickness of each of the first metal film and the second metal film, Pb and Sn of the bump are adjusted.
The composition ratio of and is set to a predetermined value.

Since the composition ratio of the bump is an important factor for determining the melting temperature and hardness of the bump, high accuracy is required for its setting.

Then, after removing the metal mask, the semiconductor wafer is heated to melt the first metal film and the second metal film deposited on the underlying metal pattern, and are formed into a hemispherical shape by surface tension. A bump made of Pb-5% Sn is formed.

In the lift-off method, a photoresist (hereinafter simply referred to as resist) is used instead of the metal mask.
This is a method of forming bumps by using a pattern as a vapor deposition mask, and is, for example, as follows.

First, after coating a resist film on a semiconductor wafer, the exposed resist pattern of the underlying metal pattern on the semiconductor wafer is transferred to the resist film by an exposure process.

Subsequently, the first metal film and the second metal film are formed on the semiconductor wafer using the resist pattern as a vapor deposition mask.
A metal film is sequentially deposited. At this time, the composition ratio of the bump is set in the same manner as above.

After that, the resist film is removed, and at the same time,
Removing the first metal film and the second metal film on the resist film,
The first metal film and the second metal film are left only on the underlying metal pattern.

Finally, the semiconductor wafer is heated, the first metal film and the second metal film deposited on the underlying metal pattern are melted, and formed into a hemispherical shape by surface tension.
A bump made of b-5% Sn is formed.

Regarding the flip chip method, for example, Ohmsha Co., Ltd., issued November 30, 1984,
It is described in "LSI Handbook" P409 to P410, and the flip-chip bonding method and features are described.

[0018]

However, the present inventor has found that the above conventional bump forming technique has the following problems.

In the metal mask vapor deposition method, since the vapor deposition process and the heat treatment for spheroidizing the solder are required, the bump forming process is complicated and the bump forming takes time.

Further, in the metal mask vapor deposition method, the processing accuracy of the metal mask is an important factor for forming good bumps, but the processing accuracy of the metal mask is maintained as the diameter of the semiconductor wafer increases. There is a problem that processing in the state becomes difficult and the metal mask becomes expensive.

In the lift-off method, the exposure process for forming the resist pattern, the vapor deposition process, the heat treatment for spheroidizing the solder, etc. are required, so that the bump forming process is complicated and the bump forming takes time. There was a problem.

Further, in the metal mask vapor deposition method and the lift-off method, since the composition ratio of the bumps is set by the thickness of the metal film during the vapor deposition process, for example, fluctuations in the thickness of the vapor deposited metal film or the thickness of the metal film. There is a problem that it is difficult to set the composition ratio with high accuracy due to a calculation error when converting the composition ratio into the composition ratio.

The present invention has been made in view of the above problems, and an object thereof is to provide a technique capable of forming bumps easily and in a short time.

Another object of the present invention is to provide a technique capable of reducing the cost for forming bumps.

Another object of the present invention is to provide a technique capable of setting the composition ratio of the constituent elements of the bump with high accuracy and easily.

The above and other objects and novel features of the present invention will be apparent from the description of the specification and the accompanying drawings.

[0027]

Among the inventions disclosed in the present application, a brief description will be given to the outline of typical ones.
It is as follows.

That is, the first invention is a bump forming apparatus for forming a bump on a base metal pattern for external electrode connection formed on a predetermined substrate, wherein the bump forming metal is melted. A molten metal tank for storing, a molten metal injecting molten metal that has flowed from the molten metal tank to the position of the base metal pattern, and a molten metal discharge member having fine holes for discharging, and molten metal in the molten metal tank. A bump forming apparatus structure having an inflow mechanism section that flows into the molten metal discharge member side, a flow rate adjustment mechanism section that adjusts the flow rate of the molten metal, and a temperature control section that controls the temperature of each component. is there.

A second aspect of the present invention has a bump forming apparatus structure in which the molten metal discharging member is detachable.

[0030]

According to the above-mentioned first invention, the molten metal ejected from the ejection hole of the molten metal ejection member is brought into direct contact with the underlying metal pattern on the predetermined substrate to form bumps on the underlying metal pattern. Therefore, when forming bumps,
It is possible to eliminate the conventional metal vapor deposition step, the hemisphericalization step of the vapor deposition metal, or the step of forming a metal mask or a resist pattern to be a vapor deposition mask.

When melting the bump forming metal,
By setting the composition ratio of the constituent elements of the molten metal to the composition ratio of the constituent elements required for the bump, the composition ratio of the constituent elements of the bump can be set with high accuracy and easily. ..

According to the above-mentioned second invention, when the arrangement of the underlying metal pattern on the predetermined substrate is changed, it is possible to change to a molten metal discharging member which can cope with the change.

[0033]

Embodiment 1 FIG. 1 is an explanatory view for explaining a main part of a bump forming apparatus according to an embodiment of the present invention, FIG. 2 is an explanatory view for explaining the entire structure of the bump forming apparatus, and FIG. FIG. 4 is a cross-sectional view of a main part of a semiconductor wafer on which bumps are formed, FIG. 4 is a cross-sectional view of a main part of a molten metal discharge member, FIG. FIG. 4 is an explanatory diagram for explaining the bump forming method of the first embodiment.

Hereinafter, the bump forming apparatus of the first embodiment will be described with reference to FIG.
~ It demonstrates by FIG. The bump forming apparatus 1 according to the first embodiment shown in FIG. 2 includes a loader / unloader unit 2 and a transfer unit 3.
And a wafer pretreatment unit 4 and a bump formation treatment unit 5.

The loader / unloader unit 2 carries a semiconductor wafer before bump formation, which will be described later, into the bump forming apparatus 1 and carries out a semiconductor wafer after bump formation, which will be described later, to the outside of the bump forming apparatus 1. It is a department.

The transfer section 3 is a mechanism section for transferring semiconductor wafers one by one to a predetermined position by a transfer arm 3b installed in the transfer chamber 3a.

The wafer pretreatment unit 4 is a treatment unit for cleaning the surface of the semiconductor wafer, in particular, the surface of a base metal pattern, which will be described later, formed on the semiconductor wafer.

The bump formation processing unit 5 is a processing unit for forming bumps, which will be described later, and is a molten solder attachment processing chamber 5a.
And a molten solder bath chamber 5b.

The molten solder attachment processing chamber 5a is a processing chamber in which the processing for depositing molten solder, which will be described later, onto the underlying metal pattern on the semiconductor wafer is performed. Also, the molten solder bath chamber 5b
Is a bath installation chamber in which a molten solder bath described below is installed.

Both the molten solder adhesion processing chamber 5a and the molten solder bath chamber 5b are filled with an inert gas such as nitrogen (N ₂ ) gas or argon (Ar) gas.
This makes it possible to prevent the molten solder from being oxidized.

FIG. 1 shows the bump formation processing section 5 of the first embodiment. The mounting table 6 is a table on which the semiconductor wafer 7 is mounted. The mounting table 6 can move vertically and horizontally, and has a structure capable of adjusting the parallelism with a molten solder discharge plate described later. ing.

The mounting table 6 is also provided with a cooling mechanism (not shown), and has a structure capable of rapidly cooling the semiconductor wafer 7.

The semiconductor wafer (predetermined substrate) 7 is made of, for example, silicon (Si) single crystal, and is fixed to the lower surface of the mounting table 6 with its main surface facing downward.

A plurality of semiconductor chips 7a are formed on the semiconductor wafer 7, and a predetermined semiconductor integrated circuit is formed on the main surface of each semiconductor chip 7a.

On the main surface of each semiconductor chip 7a,
Base metal pattern 8 for connecting external electrodes of a semiconductor integrated circuit
Are formed in plural.

As shown in FIG. 3, the base metal pattern 8 is formed by stacking metal layers 8a to 8c in order from the lower layer. The lowermost metal layer 8a is made of, for example, chromium (C
r). The intermediate metal layer 8b is made of, for example, copper (Cu) or nickel (Ni). Further, the uppermost metal layer 8c is made of, for example, gold (Au).

The base metal pattern 8 is electrically connected to the wiring 11 forming the semiconductor integrated circuit through the through hole 10 formed in the surface protective film 9. The surface protection film 9 is made of, for example, silicon dioxide (SiO ₂ ), and the wiring 11 is made of, for example, aluminum (Al) or A.
It consists of 1 alloy.

A molten solder discharge plate (molten metal discharge member) 12 is arranged below the mounting table 6 which constitutes the bump formation processing section 5 of FIG.

The molten solder ejection plate 12 is a component having perforations of ejection holes (fine holes) 14 for guiding the ejection position of the molten solder 13, and is made of, for example, Si or SiO ₂ .

In the bump forming apparatus 1 (see FIG. 1) of the first embodiment, as will be described later, the molten solder ejection plate 12
Molten solder (molten metal) 13 discharged from the discharge hole 14 of
Are directly attached to the underlying metal pattern 8 on the semiconductor wafer 7 to form bumps.

Therefore, the ejection holes 14 are arranged so as to be the same as the arrangement of the plurality of base metal patterns 8 on the semiconductor chip 7a. The diameter of the discharge hole 14 is, for example, about 200 to 300 μm in the large diameter portion, and is about 10 to 20 μm in the small diameter portion.

The thickness of the molten solder discharge plate 12 is, for example, 10
It is about 0 to 200 μm. In addition, the molten solder discharge plate 12
The plane size of is substantially the same as the chip size of the semiconductor chip 7a, for example. That is, in the first embodiment,
The bumps are collectively formed with the semiconductor chip 7a as one unit.

Discharge holes 14 in the molten solder discharge plate 12
In the vicinity of the boundary between the large diameter portion and the small diameter portion, as shown in FIG. 4, a flow hole 15 for flowing the cooling fluid is formed.

The reason why the flow holes 15 are formed is that a cooling fluid is caused to flow in the holes 15 to cool the molten solder 13 (see FIG. 1) in the vicinity of the holes 15 to increase its viscosity, and thus the molten solder at that portion. This is because it is easy to divide 13.

Further, in the first embodiment, the molten solder discharge plate 12 is removable.

That is, the molten solder discharge plate 12 can be changed.

This is because the arrangement of the base metal pattern 8 on the semiconductor chip 7a also changes depending on the type of semiconductor product. Therefore, in the case of the first embodiment in which bumps are collectively formed for each semiconductor chip 7a, the semiconductor product can be changed. This is because it is necessary to change the molten solder discharge plate 12 accordingly.

Below the molten solder discharge plate 12 of FIG. 1, a molten solder pool chamber 16 for temporarily storing the molten solder 13 is formed.

The molten solder pool chamber 16 is provided with the molten solder flow pipe 1
It is connected to the molten solder bath 18 through 7. However, although not shown, for example, the molten solder reservoir 16 may not be provided, and the molten solder flow pipe 17 and the discharge hole 14 may be directly connected.

The mounting table 6 and the molten solder discharge plate 12 described above are installed in the molten solder adhesion processing chamber 5a shown in FIG.

The molten solder tank 18 is a tank for heating and melting a bump forming metal, for example, solder such as Pb and Sn, and storing the molten solder 13. The temperature in the molten solder bath 18 is, for example, about 350 ° C.

Pb- of the molten solder 13 in the molten solder tank 18
The Sn composition ratio has already been set to a value required for the bump described later.

In this case, the composition ratio of Pb-Sn does not fluctuate due to the thickness variation of the vapor-deposited Pb film and Sn film as in the prior art, and the thickness of the vapor-deposited Pb film and Sn film does not affect the Pb-Sn of the bump. There is no problem of error in calculating the composition ratio of.

Therefore, as compared with the prior art in which the Pb-Sn composition ratio of the bump is set by the thickness of the vapor deposition film, Pb-Sn
It is possible to set the composition ratio of Sn, that is, the composition ratio of the constituent elements of the bump with high accuracy and easily.

A vertical movement mechanism section (inflow mechanism section) 19 is installed below the molten solder bath 18. Vertical movement mechanism 1
Reference numeral 9 denotes a mechanism portion that moves the molten solder bath 18 up and down to adjust the height of the molten solder bath 18 so that the molten solder 13 in the bath 18 flows into the molten solder pool chamber 16.

On the other hand, at a predetermined position of the molten solder flow pipe 17, for adjusting the flow rate of the molten solder 13, for example, FIG.
A flow rate adjusting valve (flow rate adjusting mechanism) 20 including a needle valve as shown in FIG.

A valve rod 20a constituting the flow rate adjusting valve 20.
Is inserted into a hole 17a formed in the molten solder flow pipe 17 in a vertically movable state.

The insertion end of the valve rod 20a is connected to the molten solder flow pipe 1
It is formed in a needle shape so that it can be fitted into a V-shaped groove 17b formed on the inner wall surface of 7. That is, when a pressing force is applied to the valve rod 20a to lower it and the insertion end thereof is fitted into the groove 17b, the flow of the molten solder 13 is blocked.

The coil spring 20b is a member for returning the valve rod 20a to its original position when the pressing force applied to the valve rod 20a is released. The pressing force applied to the valve rod 20a and the restoration of the coil spring 20b. The force causes the valve to open and close.

In addition, between the valve rod 20a and the hole 17a,
The sealing member 20c is interposed to prevent the molten solder 13 from leaking.

Further, in the bump formation processing unit 5 of FIG. 1, each component, for example, the molten solder pool chamber 16 and the molten solder flow pipe 1 is provided.
In order to control the temperature of the molten solder bath 7 and the molten solder bath 18, a temperature controller 21 such as a heater is installed. However, the temperature control unit 21 is not limited to the heater, and an oil bath or the like may be used, for example.

Further, the bump formation processing section 5 has a mounting table 6
And the parallelism between the molten solder discharge plate 12 and the optical system (not shown)
A parallelism measuring unit (not shown) is installed to measure the parallelism of the mounting table 6 mechanically based on the measured value measured by the parallelism measuring unit, and the mounting table 6 and the melting point are melted. The parallelism with the solder discharge plate 12 is ensured.

However, the method for ensuring the parallelism between the mounting table 6 and the molten solder discharge plate 12 is not limited to the case of using the optical system, but various modifications can be made.

For example, a parallelism measuring sensor or the like is brought into direct contact with the main surface of the mounting table 6 to measure the parallel flatness of the mounting table 6,
It is also possible to secure the parallelism between the mounting table 6 and the molten solder discharge plate 12 by mechanically correcting the parallelism of the mounting table 6 based on the measured value.

Next, the bump forming method of the first embodiment will be described with reference to FIG.
~ It demonstrates by FIG.

First, as shown in FIG. 1, the semiconductor wafer 7
Is fixed to the lower surface of the mounting table 6 with its main surface facing downward. At this time, the semiconductor chip 7a on the semiconductor wafer 7
Have already completed inspections such as electrical characteristic inspection.

Subsequently, the mounting table 6 is horizontally moved to align the predetermined positions of the semiconductor chip 7a of the semiconductor wafer 7 and the molten solder discharge plate 12. At this time, the semiconductor chips 7a to be aligned are only the semiconductor chips 7a determined to be non-defective as a result of the above-mentioned electrical characteristic inspection.

After that, the vertical movement mechanism section 19 and the flow rate adjusting valve 20 are adjusted to eject the molten solder 13 from the ejection holes 14 of the molten solder ejection plate 12 as shown in FIG.

At this time, the height of the molten solder tank 18 and the flow rate of the molten solder 13 are adjusted so that the upper surface of the molten solder 13 discharged from the discharge holes 14 rises due to surface tension.

Then, as shown in FIG. 7, the mounting table 6 is lowered to form the underlying metal pattern 8 on the semiconductor chip 7a.
Is directly contacted with the molten solder 13 exposed from the discharge hole 14.

At this time, in the first embodiment, the molten solder 13 is collectively brought into contact with all the underlying metal patterns 8 on the semiconductor chip 7a as one unit.

Then, the through hole 1 in the molten solder discharge plate 12
A cooling fluid is caused to flow into the molten solder 5, and the molten solder 13 near the flow holes 15
Cool to increase viscosity.

Then, while raising the mounting table 6,
The molten solder bath 18 is lowered to divide the molten solder 13,
A predetermined amount of molten solder 13 is attached on the underlying metal pattern 8.

At this time, the molten solder 13 deposited on the underlying metal pattern 8 becomes hemispherical due to the surface tension.

Then, for example, in a short time of about 5 minutes,
The semiconductor wafer 7 is rapidly cooled by the cooling mechanism portion installed on the mounting table 6 to form the bumps 22 as shown in FIG. 8 on the underlying metal pattern 8. The diameter of the bump 22 is, for example, about 100 to 300 μm.

The above steps are repeated for each non-defective semiconductor chip 7a on the semiconductor wafer 7 to form bumps 22 on the underlying metal pattern 8 on the semiconductor wafer 7.

As described above, according to the first embodiment, the following effects can be obtained.

(1). The molten solder 13 exposed from the ejection holes 14 of the molten solder ejection plate 12 is brought into direct contact with the underlying metal pattern 8 on the semiconductor wafer 7 to form bumps 22 on the underlying metal pattern 8. By forming the bumps, the conventional solder vapor deposition step, the hemispherical step of vapor deposition solder, the metal mask serving as a vapor deposition mask, and the step of forming a resist pattern, which are required in the related art, are unnecessary.
And it becomes possible to form in a short time.

(2). Due to the above (1), the cost for forming the bumps 22 can be reduced.

(3). When melting solder such as Pb-Sn for forming bumps, set the Pb-Sn composition ratio of the molten solder 13 to the Pb-Sn composition ratio required for the bump 22. By doing so, the composition ratio of the constituent elements of the bump 22 can be set with high accuracy and easily.

(4) Since the molten solder discharge plate 12 is detachable, the molten solder discharge plate 12 can be changed according to the arrangement change of the base metal pattern 8 accompanying the change of the type of semiconductor product. Therefore, it becomes possible to flexibly deal with the change of the semiconductor product for which the bump forming process is performed.

(5) By forming the bumps in a batch with the semiconductor chip 7a as one unit, the accuracy of the formation position of the ejection holes 14 is not significantly tightened, and the bump formation processing speed is significantly reduced. The bumps 22 can be formed without inviting them.

(6). The bumps are collectively formed for each semiconductor chip 7a to inspect the quality of all the semiconductor chips 7a on the semiconductor wafer 7, and then the good semiconductor chips 7a are obtained based on the inspection result. Since the bumps 22 can be formed only on the bumps 22 and the bumps 22 need not be formed on the defective semiconductor chip 7a, the constituent material of the bumps 22 can be effectively used.

[0094]

[Embodiment 2] FIG. 9 is an explanatory view for explaining a main part of a bump forming apparatus according to another embodiment of the present invention.

In the second embodiment, as shown in FIG. 9, the semiconductor wafer 7 is mounted on the mounting table 6 with its main surface facing upward.

Above the mounting table 6, the molten solder discharge plate 12 is provided.
Is installed. That is, in the second embodiment,
The structure is such that the molten solder 13 can be attached from above the semiconductor wafer 7.

The method of flowing the molten solder 13 in the molten solder tank 18 into the molten solder pool chamber 16 is the same as in the first embodiment.
The height of the molten solder bath 18 is adjusted by a vertical movement mechanism 19 (see FIG. 1) not shown in FIG. Molten solder 13
The flow rate adjustment valve 20 is the same as in the first embodiment.
Done by.

In the second embodiment, the molten solder flow pipe 1
A suction mechanism portion 23 for sucking the molten solder 13 is installed at a predetermined position of 7.

In the second embodiment, after the molten solder 13 discharged from the discharge holes 14 is brought into contact with the underlying metal pattern 8, the rear portion 23 of the suction device is lowered to move the molten solder 13 to the molten solder tank 18 side. As a result, the molten solder 13 can be divided.

Therefore, in the second embodiment, it is not necessary to provide the flow holes 15 in the molten solder discharge plate 12, so that the structure and manufacture of the molten solder discharge plate 12 can be simplified. Further, since the step of cooling the molten solder 13 is not required when the molten solder 13 is divided, the bump forming processing time can be shortened.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above-mentioned Embodiments 1 and 2, and various modifications can be made without departing from the scope of the invention. It goes without saying that it is possible.

For example, in the first and second embodiments, the case where the bump is formed by using the semiconductor chip as one unit has been described, but the present invention is not limited to this, and various modifications can be made. It is also possible to form the bumps all at once.

FIG. 10 shows the semiconductor wafer and the molten solder discharge plate in this case. The plane size of the molten solder discharge plate 12 is
The size is slightly smaller than the plane size of the semiconductor wafer 7.

When such a method is adopted, all the bumps on the semiconductor wafer 7 can be formed by a single bump forming process, so that the processing speed of bump forming can be improved.

It is also possible to form one bump or a predetermined number of bumps. In this case, it becomes possible to perform good alignment between the individual underlying metal patterns and the ejection holes. Further, when forming the bumps one by one, it is not necessary to change the molten solder discharge plate even if the arrangement of the underlying metal pattern is changed.

In the above description, the case where the invention made by the present inventor is mainly applied to the case where bumps are formed on the underlying metal pattern on the semiconductor chip which is the background field of application has been described. The present invention can be applied to various bumps without limitation, and can be applied to other bump forming techniques, for example, when bumps are formed on a base metal pattern of a ceramic substrate (fixed substrate) or resin substrate (predetermined substrate).

[0107]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.
It is as follows.

(1). That is, according to the above-mentioned first invention, the molten metal discharged from the discharge holes of the molten metal discharge plate is brought into direct contact with the underlying metal pattern on the predetermined substrate,
By forming bumps on the underlying metal pattern, it is possible to eliminate the conventional metal vapor deposition step, hemisphericalization step of vapor deposition metal, or metal mask or resist pattern forming step used as a vapor deposition mask, which is required in the past. Becomes

Therefore, the bumps can be formed easily and in a short time, and the cost for forming the bumps can be reduced.

When melting the bump forming metal,
By setting the composition ratio of the constituent elements of the molten metal to the composition ratio of the constituent elements required for the bump, the composition ratio of the constituent elements of the bump can be set with high accuracy and easily. ..

(2) According to the second aspect of the present invention, when the arrangement of the underlying metal pattern on the predetermined substrate is changed, it is possible to change the molten metal discharging member to the corresponding one.

That is, it is possible to flexibly deal with the change in the layout of the underlying metal pattern of the bump-formed product.

[Brief description of drawings]

FIG. 1 is an explanatory diagram for explaining a main part of a bump forming apparatus that is an embodiment of the present invention.

FIG. 2 is an explanatory diagram for explaining an overall configuration of a bump forming apparatus.

FIG. 3 is a cross-sectional view of essential parts of a semiconductor wafer on which bumps are formed.

FIG. 4 is a cross-sectional view of a main part of a molten metal discharge member.

FIG. 5 is a cross-sectional view of a flow rate adjusting mechanism section for adjusting the flow rate of molten metal.

FIG. 6 is an explanatory diagram for explaining the bump forming method according to the first embodiment.

FIG. 7 is an explanatory diagram for explaining the bump forming method according to the first embodiment.

FIG. 8 is an explanatory diagram for explaining the bump forming method according to the first embodiment.

FIG. 9 is an explanatory diagram illustrating a main part of a bump forming apparatus according to another embodiment of the present invention.

FIG. 10 is an explanatory diagram illustrating a main part of a bump forming apparatus according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bump forming apparatus 2 Loader / unloader section 3 Transfer section 3a Transfer chamber 3b Transfer arm 4 Wafer pre-processing section 5 Bump formation processing section 5a Melt solder adhesion processing chamber 5b Melt solder bath room 6 Mounting table 7 Semiconductor wafer (predetermined substrate) 7a Semiconductor chip 8 Base metal pattern 8a Metal layer 8b Metal layer 8c Metal layer 9 Surface protective film 10 Through hole 11 Wiring 12 Molten solder discharge plate (molten metal discharge member) 13 Molten solder (molten metal) 14 Discharge hole (fine hole) 15 Flow hole 16 Molten solder reservoir 17 Molten solder flow pipe 17a Hole 17b Groove 18 Molten solder tank 19 Vertical movement mechanism part (inflow mechanism part) 20 Flow rate adjusting valve (flow rate adjusting mechanism part) 20a Valve rod 20b Coil spring 20c Sealing member 21 Temperature Control Section 22 Bump 23 Suction Mechanism Section

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toyomoge Noridome 2326 Imai, Ome City, Tokyo, Hitachi Device Development Center (72) Inventor Hiroaki Miyamoto 2326 Imai, Ome City, Tokyo Hitachi, Ltd. Device Development Center (72) Inventor Yoshiyuki Sano 3-3, Fujibashi, Ome-shi, Tokyo 2 Hitachi Hitachi Electronics Co., Ltd.

Claims (7)

[Claims] 1. A bump forming method, comprising: forming a bump by directly contacting a molten metal with a base metal pattern for connecting an external electrode formed on a predetermined substrate. 2. The bump forming method according to claim 1, wherein the melting treatment of the metal and the contact treatment with the underlying metal pattern are performed in an inert gas atmosphere. 3. The bump forming method, wherein the metal is lead, tin or an alloy thereof. 4. The bump forming method according to claim 1, 2 or 3, wherein the predetermined substrate is a semiconductor wafer. 5. When bumps are formed by directly contacting a molten metal with a base metal pattern for connecting external electrodes formed on the semiconductor wafer, the bumps are formed for each semiconductor wafer or on the semiconductor wafer. The bump forming method according to claim 4, wherein the bumps are collectively formed for each of the formed semiconductor chips. 6. A bump forming apparatus for forming a bump on a base metal pattern for connecting an external electrode formed on a predetermined substrate, comprising a molten metal tank for storing the bump forming metal in a molten state. The molten metal inflowing from the molten metal tank is guided to the position of the base metal pattern, and the molten metal discharge member having fine holes for discharging and the molten metal in the molten metal tank is connected to the molten metal discharge member side. A bump forming apparatus comprising: an inflow mechanism section for inflowing into the chamber, a flow rate adjusting mechanism section for adjusting the flow rate of the molten metal, and a temperature control section for controlling the temperature of each component. 7. The bump forming apparatus according to claim 6, wherein the molten metal discharge member is detachable.