Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package
Reexamination Certificate
1999-11-03
2001-11-06
Clark, Jhihan B (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
C257S659000, C257S723000, C257S790000, C257S787000
Reexamination Certificate
active
06313521
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a semiconductor device in which one or more semiconductor chips and chip components are mounted on a substrate and a method of manufacturing the semiconductor device. More particularly, the present invention relates to a semiconductor device in which one or more semiconductor chips and chip components are mounted on a substrate and in which electrical short and coming away of the chip components from the substrate are avoided, and a method of manufacturing such semiconductor device.
BACKGROUND OF THE INVENTION
FIG. 11
is a conceptual cross sectional view illustrating an example of a conventional semiconductor device. As shown in
FIG. 11
, a semiconductor chip
32
is flip chip bonded on a substrate
31
which has conductor patterns formed thereon not shown in the drawing. The semiconductor chip
32
is electrically coupled with the conductor patterns on the substrate
31
not shown in the drawing via eutectic solder portions
33
. In the proximity of the semiconductor chip
32
, chip components
34
such as chip capacitors, and the like are attached to the substrate
31
via the eutectic solder portions
35
. The chip components
34
are electrically coupled with the conductor patterns on the substrate not shown in the drawing via the eutectic solder portions
35
. Underfill resin
36
is injected between a first surface of the semiconductor chip
32
, that is, a surface on which circuit elements are formed and which is a surface on the bottom side of the drawing sheet, and the substrate
31
. The underfill resin
36
fills a space between the first surface of the semiconductor chip
32
and the substrate
31
except the eutectic solder portions
33
and is cured to strongly fix the semiconductor chip
32
to the substrate
31
.
Usually, on the first surface of the semiconductor chip
32
, there are provided high temperature solder bumps not shown in the drawing, and eutectic solder portions which have lower melting point than that of the high temperature solder bumps are disposed on the substrate
31
at locations corresponding to those of the solder bumps of the semiconductor chips
32
. The high temperature solder bumps of the semiconductor chip
32
and the eutectic solder portions of the substrate
31
are aligned, and heated at a temperature in which the eutectic solder melts but the high temperature solder does not melt. Thereby, only the eutectic solder portions melt, and, thereafter, the eutectic solder portions are cured. By this process, the eutectic solder potions cure such that the eutectic solder portions swallow up the solder bumps. Also, on the surface of the substrate
31
opposite to the surface on which the semiconductor chip
32
and the chip components
34
are mounted, a plurality of solder balls
37
made of the eutectic solder are disposed. The semiconductor device
50
of
FIG. 11
thereby constitutes a BGA (Ball Grid Array) package structure.
When the completed semiconductor device
50
is mounted on another substrate and the like, the solder balls
37
are once melted by heating and thereafter cured, thereby the semiconductor device
50
and another substrate and the like are electrically and mechanically coupled. However, when the solder balls
37
are melted by heating, the eutectic solder portions
33
coupling the semiconductor chip
32
and the substrate
31
are also melted once similarly to the solder balls
37
, by the heat conducted via the substrate
31
. Therefore, there is a possibility that mutual positional relation between the substrate
31
and the semiconductor chip
32
deviates from correct positional relation and that electrical and mechanical coupling between the substrate
31
and the semiconductor chip
32
becomes unstable. Thus, when the substrate
31
and the semiconductor chip
32
are coupled only by the eutectic solder
33
, electrical and mechanical coupling become unreliable. In order to avoid such disadvantage, as shown in
FIG. 11
, the underfill resin
36
was injected and cured between the substrate
31
and the semiconductor chip
32
, thereby securing the substrate
31
and the semiconductor chip
32
by the underfill resin
36
. In this structure, the heating temperature for melting the solder ball
37
made of eutectic solder is determined to be a low temperature such that the eutectic solder melts but the underfill resin
36
does not deteriorate. Thereby, high reliability of electrical and mechanical coupling between the substrate
31
and the semiconductor chip
32
can be realized.
On a second surface of the semiconductor chip
32
, that is a surface on the upper side of
FIG. 11
, an adhesive resin
38
which is electrically conductive is applied. By the adhesive resin
38
, a lid member
39
is attached to the second surface of the semiconductor chip
32
, wherein the lid member
39
is made of a metal and has good heat conductivity. The lid member
39
dissipates heat produced by the semiconductor chip
32
and functions to couple the semiconductor chip
32
to the ground potential, that is, functions to ground the semiconductor chip
32
. Also, there is provided an electrically conductive auxiliary board
40
which surrounds a space containing the semiconductor chip
32
and the chip components
34
. The auxiliary board
40
is also bonded to the substrate
31
and to the lid member
39
by using electrically conductive adhesive resin
41
. Therefore, a space
42
including the semiconductor chip
32
and the chip components
34
is electromagnetically shielded by the lid member
39
and the auxiliary board
40
.
In the fabrication of the above-mentioned conventional semiconductor device
50
, when the lid member
39
is bonded to the second surface of the semiconductor chip
32
and the auxiliary board
40
by the conductive adhesive resin
38
, if the quantity of the conductive adhesive resin
38
applied to the second surface of the semiconductor chip
32
is too large, there is a possibility that the conductive adhesive resin
38
also reach and contact the chip components
34
.
FIG. 12
is a cross sectional view illustrating a situation caused when the quantity of the conductive adhesive resin
38
is too large. In such situation, there is a possibility that electrical short occurs between terminals of one chip component, between terminals of a plurality of chip components, between a chip component
34
and the semiconductor chip
32
, and so on, via the conductive adhesive resin
38
. Therefore, it becomes impossible for the semiconductor device
50
to perform its inherent function. On the other hand, if the quantity of the adhesive resin
38
is too small, the lid member
39
and the semiconductor
32
are not secured strongly and stably. Therefore, in the manufacturing process of the conventional semiconductor device, it is necessary to apply the conductive adhesive resin
38
on the semiconductor chip
32
, very carefully.
In the above-mentioned conventional semiconductor device
50
, the chip components
34
are fixed on the substrate
31
only by the eutectic solder portions
35
. Therefore, securing force between each of the chip components
34
and the substrate
31
is not sufficiently large and there is a possibility that the chip components
34
come away from the substrate
31
. Especially, when the semiconductor device
50
is fixed to another substrate or another component by using the solder balls
37
disposed on the surface of the substrate
31
opposite to the surface on which the semiconductor chip
32
and the chip components
34
are coupled, there occurs a problem. That is, when the solder balls
37
are heated by solder reflow process to melt the solder balls
37
, the eutectic solder portions
35
coupling the chip components
34
to the substrate
31
also melt, and the chip components
34
are apt to come away from the substrate
31
. Therefore, in the conventional semiconductor device
50
, the eutectic solder portions
35
for fixing the chip components
34
to the substrate
31
and the solder balls
Clark Jhihan B
Hutchins, Wheeler & Dittmar
NEC Corporation
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