Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – With contact or lead
Reexamination Certificate
1998-10-13
2003-04-01
Zarabian, Amir (Department: 2822)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
With contact or lead
C257S738000, C257S778000, C257S781000
Reexamination Certificate
active
06541848
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a semiconductor device, a method of manufacturing a semiconductor device and a method of manufacturing a lead frame, and particularly relates to a semiconductor device having high-density external-connection electrodes, a method of manufacturing such a semiconductor device and a method of manufacturing a lead frame.
Recently, there is a need for semiconductor devices having smaller mounting areas on supporting boards so as to realize miniaturization of electronic devices. Also, there is a need for fine-pitched semiconductor devices in respect to the pitches of electrodes and of external connection terminals.
2. Description of the Related Art
FIGS. 1A
to
1
C and
FIG. 2
are diagrams showing resin-seal type semiconductor devices of the related art.
Referring to
FIGS. 1A
to
1
C, a first resin-seal type semiconductor device includes a resin
1
, a semiconductor chip
2
, outer leads
3
, bonding wires
4
and a die pad
5
. This semiconductor device has a package structure called SSOP (Shrink Small Outline Package) and is mounted on a supporting board with the outer leads
3
bent in a gull-wing shape.
Referring to
FIG. 2
, a second resin-seal type semiconductor device is provided with the resin
1
, the semiconductor chip
2
, the bonding wires
4
, solder balls
6
and a semiconductor chip mounting board
7
whereon the semiconductor chip
2
is mounted. This semiconductor device has a package structure called BGA (Ball Grid Array), and terminal parts mounted on the mounting board are formed of solder balls
6
.
With the semiconductor device of the SSOP type as shown in
FIGS. 1A
to
1
C, there is a problem that the mounting area becomes large. This is because a connection part
9
between inner leads
8
in the resin
1
and the outer leads
3
, and the outer leads
3
both occupy comparatively large areas. Also, with the semiconductor device of the BGA type shown in
FIG. 2
, there is a problem of additional cost since the device requires the mounting board
7
.
In order to provide a semiconductor device which can solve the above-described problems, the applicant has proposed Japanese Laid-Open Patent Application 9-162348.
FIG. 3
shows a semiconductor device
110
related to the cited application.
The semiconductor device
110
shown in
FIG. 3
has a package structure called BCC (Bump Chip Carrier) and has an extremely simple structure including a semiconductor chip
111
, a resin package
112
and metal layers
113
. The metal layers
113
are deposited on resin protrusions
117
integrally formed on a mounting surface
116
of the resin package
12
. The semiconductor chip
111
is connected to the metal layers
113
by wires
118
. Also, stud bumps
119
are provided so as to improve connectivity between the wires
118
and the metal layers
113
.
The semiconductor device
110
having the above structure no longer requires inner leads and outer leads as those of the SSOP type of the related art. Therefore, no area is required for the connection part between the inner leads and the outer leads and for the outer leads. Thus, the semiconductor device
110
can be miniaturized.
Also, a mounting board as used in the BGA type of the related art is no longer required since there is no need for supporting the solder balls thereon. Therefore, the cost of manufacturing the semiconductor device
110
can be lowered. Further, the resin protrusions
117
and the metal layers
113
cooperate so as to provide a function equivalent to that of the solder bumps of the semiconductor device of the BGA type. Thus, a mounting ability can be improved.
However, problems may arise when attempting to provide fine-pitched external connection terminals having a terminal pitch size of, for example, less than 0.5 mm so as to meet the recent trend of ever miniaturized and fine-pitched semiconductor devices. With the semiconductor device
110
of the BCC structure shown in
FIG. 3
, the external connection terminals are formed of the resin protrusions
117
and the metal layers
113
. Thus, it is difficult to achieve a fine-pitched structure in regards to creating half-etched recesses of the lead frame during manufacturing processes of the semiconductor device and to creating the metal layers
113
. In other words, there is a limit in reducing the mounting area. Therefore, there is still a need for further reduction in the mounting area.
Also, with the semiconductor device of the BGA structure shown in
FIG. 2
, a fine-pitched structure of the semiconductor device implies finer solder balls
6
. It is then difficult to mount such fine solder balls
6
on the semiconductor mounting board
7
with high accuracy.
Accordingly, there is a need for a resin-seal type semiconductor device having fine-pitched mounting terminals and a small mounting area, while achieving reduction in its cost and size. Also, there is a need for a method of manufacturing such a semiconductor device. Further, there is a need for manufacturing a lead frame.
SUMMARY OF THE INVENTION
Accordingly, it is a general object of the present invention to provide a semiconductor device, a method of manufacturing a semiconductor device and a method of manufacturing a lead frame which can satisfy the needs described above.
It is another and more specific object of the present invention to provide a semiconductor device which can achieve a fine-pitched structure of external connection terminals.
In order to achieve the above objects according to the present invention, a semiconductor device includes a semiconductor chip sealed in a resin and connecting members for electrically connecting the semiconductor chip and external connection terminals, wherein the external connection terminals are stud bumps.
In the semiconductor device described above, when wires are used as the connecting members, stud bumps can be formed with the same equipment as used in a wire bonding process, since a wire bonder is used for forming the stud bumps. Therefore, an equipment cost can be reduced.
It is still another object of the present invention to provide a semiconductor device which can achieve a fine-pitched structure of external connection terminals and also a low-back structure of the semiconductor device.
In order to achieve the above object, a semiconductor device includes a semiconductor chip, a resin package for sealing the semiconductor chip, metal layers provided on a mounting-side surface of the resin package in an exposed manner and connecting members for electrically connecting electrode pads provided on the semiconductor chip and the metal layers. The metal layers are provided with stud bumps on the mounting side, the stud bumps serving as external connection terminals.
It is yet another object of the present invention to provide a semiconductor device which can achieve good electrical connectivity between the semiconductor chip and metal layers, and between the metal layers and the mounting board.
In order to achieve the above object, each of the metal layers has a single-layered structure and is made of one of gold (Au), palladium (Pd) and aluminum (Al). Other embodiments are also possible. Each of the metal layers may have a double-layered structure having two layers each made of respective one of gold (Au), palladium (Pd) and aluminum (Al). Each of the metal layers may have a double-layered structure having an outer layer made of palladium (Pd) and an inner layer made of nickel (Ni). Also, each of the metal layers may have a triple-layered structure having three layers made of either a combination of an outer layer made of palladium (Pd), an intermediate layer made of nickel (Ni) and an inner layer made of palladium (Pd), or a combination of an outer layer made of gold (Au), an intermediate layer made of nickel (Ni) and an inner layer made of palladium (Pd). Further, each of the metal layers may have a quadruple-layered structure having four layers made of a combination of an outer layer made of palladium (Pd), a first intermediate layer made o
Hozumi Takashi
Kawahara Toshimi
Monma Syuichi
Nakaseko Shinya
Onodera Masanori
Armstrong Westerman & Hattori, LLP
Brophy Jamie L.
Fujitsu Limited
Zarabian Amir
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