Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
2000-02-17
2001-08-28
Picardat, Kevin M. (Department: 2822)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S612000, C438S614000
Reexamination Certificate
active
06281107
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device and a method for manufacturing the same, and more specifically to a semiconductor device having a semiconductor device chip mounted on a circuit substrate and encapsulated with resin, and a method for manufacturing the same.
2. Description of Related Art
In a prior art semiconductor device, a method has been performed in which a semiconductor device chip is mounted on one principal surface of a circuit substrate, and solder bump electrodes is formed on the other principal surface of the circuit substrate by locating a solder ball on electrodes formed on the other principal surface of the circuit substrate, and by reflowing the solder ball. This method is widely known as a BGA (Ball Grid Array). This package is attracting attention, since it has a construction fitted to a package required to have a number of electrodes.
In the case of forming the solder bump electrodes on the circuit substrate as an external electrodes of the package, since the solder bump electrode is required to have a height, a method of directly putting a solder ball on the electrodes of the circuit substrate has been performed in the prior art.
For example, Japanese Patent Application Pre-examination Publication No. JP-A-02-284426 discloses a method for forming a solder bump electrode on a predetermined electrode by means of a solder immersing method, although it relates to a semiconductor device chip itself.
As shown in
FIG. 1
, this prior art example is so constructed that an aluminum electrode
15
having poor solder wettability is formed on a silicon oxide film
14
formed on a silicon substrate
13
, and a whole surface of the aluminum electrode
15
exposed within an opening formed in an insulator film
16
is covered with a conductive paste
17
having a solder wettability, and an assembly thus formed is immersed into a solder bath so that a solder bump electrode
18
is obtained.
Furthermore, Japanese Patent Application Pre-examination Publication No. JP-A-05-327202 discloses a method for forming a solder bump electrode by printing a solder paste on a predetermined electrode and shaping it by a reflowing.
In the prior art semiconductor device shown in
FIG. 1
, the conductive paste is formed on the whole surface of the aluminum electrode having poor solder wettability. The reason for this is that it is necessary to cover a large area with the conductive paste, since it is difficult to obtain a sufficient bond strength between a surface of the aluminum electrode and the conductive paste because an oxide film is formed on the surface of the aluminum electrode, and since it is also difficult to obtain a sufficient bond strength between the conductive paste and the solder because of a resin component included in the conductive paste.
In addition, the height of the solder bump electrode obtained by the solder immersing method is on the order 30 &mgr;m at maximum in the case of an electrode having one side length of 100 &mgr;m. This is effective in the case that the height of the solder bump electrode is not so required as in TAB (Tape Automated Bonding), but has become difficult to apply to a packaging for mounting on a printed circuit substrate. In the method for printing and reflowing the solder paste, on the other hand, it was difficult to obtain a sufficient bump height in comparison with the area in which the solder is printed.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a semiconductor device and a method for manufacturing the same, which have overcome the above mentioned defect of the prior art.
Another object of the present invention is to provide a semiconductor device and a method for manufacturing the same, capable of increasing the height of the solder bump electrode and also capable of uniformizing the height of the obtained solder bump electrodes.
Still another object of the present invention is to provide a semiconductor device and a method for manufacturing the same, capable of having an elevated reliability of connection after being mounted.
A further object of the present invention is to provide a semiconductor device and a method for manufacturing the same, capable of forming, in bundle, and at a low cost, bump electrodes having an elevated reliability of connection after being mounted.
A feature of the present invention lies in a semiconductor device including a semiconductor device chip mounted on a substrate and a solder bump electrode formed on an electrode film of the substrate, wherein the semiconductor device includes a conductive paste formed in the form of a pillar on a first surface portion of the electrode film, and a solder bump electrode formed to cover the pillar-form conductive paste and a second surface portion of the electrode film on which the pillar-form conductive paste is not formed. Here, it is preferred that the first surface portion is positioned on a center of the electrode film, and the second surface portion is positioned on a periphery of the electrode film. Furthermore, a surface of the electrode film is preferably plated with gold. In addition, a circuit element mounted on the substrate can be one or more electronic parts including the semiconductor device chip. Moreover, the conductive paste preferably includes a Cu powder as conductive filler.
Another feature of the present invention lies in a method for manufacturing a semiconductor device, comprising the steps of forming a conductive paste in the form of a pillar on a first surface portion of a whole surface of an electrode film on a substrate, by means of a printing method, and forming a solder bump electrode to cover the pillar-form conductive paste and a second surface portion of the electrode film on which the pillar-form conductive paste is not formed. Here, it is preferred that after the conductive paste is formed in the form of the pillar by means of the printing method, the pillar-form conductive paste is cured by a heat treatment. The solder bump electrode can be formed by printing a solder paste to cover the pillar-form conductive paste and the second surface portion of the electrode film on which the pillar-form conductive paste is not formed, and then, reflow-melting the printed solder paste. Alternatively, the solder bump electrode can be formed by a solder immersing method.
REFERENCES:
patent: 5468655 (1995-11-01), Greer
patent: 5547530 (1996-08-01), Nakamura et al.
patent: 5640052 (1997-06-01), Tsukamoto
patent: 5747101 (1998-05-01), Booth et al.
patent: 2-284426 (1990-11-01), None
patent: 5-327202 (1993-12-01), None
Foley & Lardner
NEC Corporation
Picardat Kevin M.
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