Semiconductor device manufacturing: process – Packaging or treatment of packaged semiconductor
Reexamination Certificate
2001-12-04
2003-02-11
Graybill, David E. (Department: 2827)
Semiconductor device manufacturing: process
Packaging or treatment of packaged semiconductor
C438S127000, C257S667000, C257S783000, C257S778000, C257S782000
Reexamination Certificate
active
06518090
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a semiconductor device having a package structure such as BGA (Ball Grid Array), CSP (Chip Scale Package), wherein a semiconductor chip is mounted on a circuit board through a resin layer, and a method of manufacturing the same.
BACKGROUND OF THE INVENTION
Semiconductor devices have been increasingly required to be lighter and smaller, in accordance with the recent trend that electronic devices have become lighter and smaller. Corresponding with this trend, BGA or CSP-type semiconductor devices using a sealing resin have become widely used.
FIG.
8
(
a
) shows an example of a conventional wire bonding type CSP. This semiconductor device is arranged so that a semiconductor chip
51
is fixed on a circuit board
52
by using an adhesive film or an adhesive resin paste layer
53
. The semiconductor chip
51
is connected to a metal wire
54
formed on the top surface of the circuit board
52
by a wire
55
(wire bonding) and the metal wire
54
is connected to a solder ball
56
formed on the bottom surface of the circuit board
52
, through a perforation
57
formed through the circuit board
52
. This semiconductor device is arranged so that a face of the circuit board
52
where the semiconductor chip is mounted is coated with a resin mold layer
58
to protect the semiconductor chip
51
and the wire
55
.
FIG.
8
(
b
) shows an example of a conventional flip chip type CSP. This semiconductor device is arranged so that the semiconductor chip
51
is fixed on the top surface of the circuit board
52
by using the adhesive resin layer
53
. The adhesive resin layer
53
is fabricated from an insulating or anisotropic conductive paste or sheet. Each protrusive electrode
59
formed on an electrode (not illustrated) of the semiconductor chip
51
is connected to an electrode of the circuit board
52
, and the metal wire
54
on the circuit board
52
is also connected to the solder ball
56
provided on the bottom surface of the circuit board
52
through the perforation
57
formed on the circuit board
52
.
As another method to mount the semiconductor chip
51
on the circuit board
52
by a flip chip connection, there is a method in which a liquid sealing resin is injected into an interface between the semiconductor chip
51
and the circuit board
52
, after the semiconductor chip
51
is connected to the circuit board
52
by the flip chip connection. In the cases of these flip chip connections, the resin mold layer
58
is not necessary.
When the semiconductor devices shown in FIGS.
8
(
a
) and (
b
) are used, the device is mounted on another packaging substrate by reflowing. However, the constituents of the semiconductor device such as a base material forming the circuit board
52
and a resin take up moisture in the air. The moisture is vaporized and expands as the temperature rises at the moment of mounting by reflowing, so this may bring about the so-called popcorn phenomenon that causes swelling and falling off inside the semiconductor device. In this manner, the moisture in the semiconductor device has been a problem.
Thus, as FIG.
9
(
a
) shows, a technique (first conventional technique) of Japanese Laid-Open Patent Application No. 9-121002/1997 (Tokukaihei 9-121002; published on May 6, 1997) is arranged so that a small hole, i.e. moisture drain hole
60
penetrating the circuit board
52
is formed in an area of the circuit board
52
where the adhesive resin layer
53
is exposed, and the moisture accumulated in the semiconductor device is effectively drained through the moisture drain hole
60
.
Meanwhile, as FIG.
9
(
b
) shows, a technique (second conventional technique) of Japanese Laid-Open Patent Application No. 11-243160/1999 (Tokukaihei 11-243160; published on Sep. 7, 1999) proposes such an arrangement that a small hole, i.e. moisture drain hole
61
, penetrating the circuit board
52
and the adhesive resin layer
53
from the bottom surface of the circuit board
52
, is formed to make it easy to drain the moisture through th e moisture drain hole
61
.
However, the conventional semiconductor devices have following problems. The first conventional technique is arranged so that the moisture drain hole
60
is formed before the semiconductor chip
51
is mounted on the circuit board
52
. In this kind of arrangement, fluid adhesives such as an adhesive like a paste or resins that temporarily lose solidity so as to becoming fluid when heated cannot be used as materials for the adhesive resin layer
53
for mounting the semiconductor substrate
51
on the circuit board
52
. This is because the adhesive or the resin could leak through the moisture drain hole
60
or the hole
60
could be blocked by the leaking agent. For the same reasons, in the case of the flip chip connection, an aerotropic conductive adhesive film/paste, a thermosetting adhesive, or an underfill agent cannot be used as the adhesive resin layer
53
. As a result, available materials and variety of the manufacturing process have become severely limited.
In the meantime, the second conventional technique is arranged so that the moisture drain hole
61
is formed through the circuit board
52
and the adhesive resin layer
53
after the semiconductor chip
51
is mounted on the circuit board
52
, to solve these problems.
However, in this case it is difficult to determine the endpoint in the penetrating operation, when the moisture drain hole
61
is formed from the bottom surface of the circuit board
52
by using a drill or a laser beam. That is to say, provided that the semiconductor device is the wire bonding type shown in FIG.
9
(
b
), on the one hand, it is possible to set the endpoint as the penetrating operation ends when the laser beam reaches the back of the semiconductor chip
51
, since a non-connecting surface of the semiconductor chip
51
faces the circuit board
52
. On the other hand, in the case of a flip-chip-type semiconductor device, since the laser beam reaches a connecting surface (top surface) of the semiconductor chip
51
, the laser beam does harm to characteristics of the semiconductor device, because a connecting surface of the semiconductor chip
51
faces the circuit board
52
. Moreover, moisture resistance of the semiconductor chip
51
has become reduced, because the connecting surface of the semiconductor chip
51
is exposed to the outside air through the moisture drain hole
61
.
In both of the conventional techniques, performance of draining moisture from the semiconductor device depends on the diameter of the moisture drain holes
60
and
61
, so the larger the diameter, the better moisture draining performance. Meanwhile, the diameter of the moisture drain holes
60
and
61
are determined in accordance with the diameter of the laser beam or the drill forming the holes
60
and
61
. For instance, when the laser beam which can do the operation efficiently is used, it is difficult to make a beam with large diameter and thus making the moisture drain holes
60
and
61
have large diameter is also difficult. In the meantime, when the drill is used, while making the moisture drain holes
60
and
61
with large diameter itself is easy, it is difficult to drain moisture adequately by making the diameter of the moisture drain holes
60
and
61
be adequately large, because relationships such as tradeoffs between the moisture drain hole and the wiring pattern (metal wire
54
) formed on the circuit board
52
must be considered.
Therefore, the present invention aims to provide a semiconductor device capable of efficiently draining moisture from the device through a moisture drain hole formed through a circuit board, at the moment of reflowing for mounting the semiconductor device on another mounting substrate. Furthermore, the present invention aims to provide a manufacturing method of a semiconductor device in which:
a semiconductor chip is protected from a penetrating operation to form the moisture drain hole through the circuit board; and also
materials of intermediate layers such as an adhesive
Dotta Yoshihisa
Saza Yasuyuki
Tamaki Kazuo
Graybill David E.
Mitchell James
Nixon & Vanderhye P.C.
Sharp Kabushiki Kaisha
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