Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
2000-11-21
2003-09-23
Chaudhuri, Olik (Department: 2823)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C436S118000
Reexamination Certificate
active
06624058
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a resin seal type semiconductor device, and a method for producing the same.
2. Description of the Related Art
Recently, in keeping with the tendency toward high density packaging of electrical appliances, there has been increased demand for thin and small-sized semiconductor devices, and the production quantity of resin seal type packages such as Ball Grid Array/Chip Size Package (BGA/CSP) has increased. In these circumstances, in order to improve BGA/CSP production or the like, a production method using package molding/saw cutting techniques has been widely used where a plurality of integrated circuit (IC) chips are fixed to one wiring substrate and sealed all together by mold resin. Thereafter, the wiring substrate is cut into separate semiconductor devices.
FIG. 2
is a cross sectional view showing an example of a conventional semiconductor device.
The semiconductor device shown in this drawing is that of BGA/CSP type produced by using package molding/saw cutting technique. An IC chip
3
is fixed onto a wiring substrate
1
by an adhesive agent
2
. The wiring substrate
1
is, for example, formed of a glass/epoxy substrate having a thickness of 0.2 mm or thereabouts. Wiring patterns
1
a
and
1
b
are respectively formed on face and reverse surfaces of the wiring substrate
1
in the periphery thereof and are electrically connected to each other via a through hole
1
c.
The wiring pattern
1
a
formed on the face surface of the wiring substrate
1
and an electrode
3
a
on the surface of the IC chip
3
are connected by a wire
4
such as gold wire. The surface of the wiring substrate
1
is sealed by a mold resin
5
having a predetermined thickness so as to protect the IC chip
3
and the wire
4
. A soldering ball
6
having a diameter of 0.5 mm or thereabouts is attached to the wiring pattern
1
b
formed on the reverse surface of the wiring substrate
1
so as to make connection with a printed circuit board or the like.
Such semiconductor devices as above are produced by the following process.
First, a wiring substrate is produced in which plural sets of wiring patterns
1
a
and
1
b
, and through holes
1
c
are arranged, corresponding to each of the plural IC chips
3
, in transverse and vertical directions in a region around a corresponding IC chip
3
. Subsequently, the plural IC chips
3
are each fixed by the adhesive agent
2
to a predetermined position on the wiring substrate, and an electrode
3
a
on the surface of the IC chip
3
and the wiring pattern
1
a
corresponding thereto are connected by the wire
4
for wire bonding.
Further, the wiring substrate on which the plural IC chips
3
are mounted is placed on a lower metallic mold heated to 170° C. or thereabouts, and a corresponding upper metallic mold is placed thereon. The mold resin
5
is injected from an injection hole formed in the upper metallic mold into an interior of the molds and a cavity formed by an inner surface of the upper metallic mold, and the wiring substrate is sealed by the mold resin
5
.
After the mold resin
5
has been cured, the wiring substrate of which surface is sealed by the mold resin
5
, is taken out by releasing the upper and lower metallic molds therefrom. The resin-sealed wiring substrate is cut into separate semiconductor devices corresponding to the IC chips
3
by using a cutting saw. The soldering ball
6
is attached to the wiring pattern
1
b
on the reverse side of each of the separate wiring substrates
1
, to thereby form a complete semiconductor device. Thus, productivity markedly improves as compared with a method in which wiring semiconductor devices are separately molded one by one.
However, the above-described structure of semiconductor devices and method for producing the same, which have been conventionally known, have the following problems.
When the wiring substrate having dimensions of, for example 60 mm×180 mm, is placed on a lower metallic mold heated to 170° C. or thereabouts, the wiring substrate is warped due to heat from the lower metallic mold and a portion of the wiring substrate may be raised from the lower metallic mold. When the upper metallic mold is placed on the wiring substrate in the above-described state, there exists a problem in which the bonded wire
4
contacts the inner surface of the upper metallic mold and thereby deforms. In this regard, there is a risk of causing short-circuits due to deformed wires
4
contacting each other.
SUMMARY OF THE INVENTION
The present invention has been devised to solve the above-described problems existing in the conventional method, and an object of the present invention is to provide a semiconductor having a structure in which reduced deformation of a bonded wire occurs, and a method for producing the semiconductor device.
In order to solve the above-described problem, in accordance with a first aspect of the present invention, there is provided a method for producing a semiconductor device, comprising the steps of: (a) bonding a plurality of semiconductor elements onto a wiring substrate, the wiring substrate having a wiring pattern formed thereon for external connection, and each semiconductor having a surface with an electrode thereon; (b) connecting the electrode on the surface of each of the semiconductor elements to the wiring pattern on the wiring substrate with a metal wire; (c) fixing a contact prevention resin having a predetermined height to the surface of at least one of the plurality of semiconductor elements; (d) placing the wiring substrate, with the surface of each of the semiconductor elements facing upward, in a lower metallic mold for mold processing; (e) putting an upper metallic mold for mold processing on the wiring substrate placed in the lower metallic mold; (f) injecting mold resin into a space formed between the wiring substrate and the upper metallic mold for sealing the semiconductor element and the metal wire on the wiring substrate; and (g) cutting the wiring substrate sealed by the mold resin into portions corresponding to the plurality of semiconductor elements to thereby form a plurality of semiconductor devices.
In the first aspect of the present invention, since the above-described method for producing a semiconductor device is provided, the following operation is performed.
A plurality of semiconductor elements are bonded onto a wiring substrate on which wiring patterns are formed corresponding to the plurality of semiconductor elements. Further, an electrode on the surface of each of the semiconductor elements and a wiring pattern corresponding thereto are connected by a metal wire and contact prevention resin having a predetermined height is fixed to the surface of each of the semiconductor elements. The wiring substrate on which the plurality of semiconductor elements are mounted, is placed on the lower metallic mold for mold processing, and an upper metallic mold is placed on the wiring substrate. The mold resin is injected into the space formed between the upper metallic mold and the wiring substrate, thereby sealing the wiring substrate. The wiring substrate sealed by the mold resin is cut into portions corresponding to the semiconductor elements, thereby forming a plurality of semiconductor devices.
In accordance with a second aspect of the present invention, there is provided a method for producing a semiconductor device, comprising the steps of: (a) bonding a plurality of semiconductor elements onto a wiring substrate, the wiring substrate having a wiring pattern for external connection formed thereon, and each semiconductor having a surface with an electrode thereon; (b) connecting the electrode on the surface of each semiconductor element to the wiring pattern on the wiring substrate with a metal wire; (c) placing, in a lower metallic mold for mold processing, the wiring substrate with the surfaces of the semiconductor elements facing upward; (d) placing an upper metallic mold for mold processing on the wiring substrate placed in the lower metalli
Chaudhuri Olik
Kebede Brook
Oki Electric Industry Co. Ltd.
Rabin & Berdo P.C.
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