Semiconductor device manufacturing: process – Packaging or treatment of packaged semiconductor – Encapsulating
Reexamination Certificate
2000-06-14
2002-09-03
Talbott, David L. (Department: 2827)
Semiconductor device manufacturing: process
Packaging or treatment of packaged semiconductor
Encapsulating
C438S113000, C438S124000, C438S126000
Reexamination Certificate
active
06444500
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to methods for manufacturing semiconductor devices and split-molds used therein, and more particularly to a method for manufacturing Chip Size Package (CSP) type semiconductor devices and a split-mold used therein.
In recent years, with increasing demand for miniaturized electric equipment, a semiconductor device installed therein has also been required to have a smaller size (high density). In order to support this situation, the semiconductor device is made to have a size approximately the same as that of a semiconductor chip contained therein. Such a semiconductor device is referred to as the CSP type semiconductor device. The CSP type semiconductor device has a chip thereof encapsulated in resin so as to improve reliability while maintaining miniaturization.
The CSP type semiconductor device, on the other hand, needs to be manufactured with high productivity. Therefore it is very useful to improve productivity of a process for encapsulating the chip with the resin.
2. Description of the Related Art
FIGS. 1 through 4
show a conventional method for manufacturing such a CSP type semiconductor device and a conventional split-mold used in the method. The method includes a step for forming a resin layer serving to encapsulate a substrate on which a plurality of semiconductor chips are formed.
Specifically,
FIG. 1
is a diagram schematically showing a split-mold
20
used for manufacturing the CSP type semiconductor device. As shown in this diagram, the split-mold
20
mainly includes a male mold
21
and a female mold
22
both of which are provided with heaters (not shown) serving to heat and melt encapsulating resin
35
that will be described later.
The male mold
21
is configured to be able to be moved up and down as shown by arrows Z
1
and Z
2
in FIG.
1
. Further, the male mold
21
has a pressing surface
21
a
formed at the bottom thereof serving to apply a pressure to the encapsulating resin
35
. The pressing surface
21
a
is a flatted surface.
The female mold
22
, on the other hand, is configured to have a first female mold
23
that is shaped like a cylinder and a second female mold
24
that has an annular shape. The first female mold
23
is formed corresponding to and slightly larger than a substrate
16
in dimension. The substrate
16
is mounted on a pressing surface
25
of the first female mold
23
. The second female mold
24
has a cavity surface
26
formed on an inner wall thereof, serving to provide space to accommodate the remainder of the encapsulating resin
35
.
The second female mold
24
is configured to be approximately annular so as to surround the first female mold
23
. Further, the second female mold
24
is able to be moved up and down with respect to the first female mold
23
along the arrows Z
1
and Z
2
, that is, to approach to or separate from the pressing surface
21
a
of the male mold
21
.
FIG. 1
also shows a state immediately prior to the beginning of a process for forming a resin layer. As shown in this diagram, in this state, the second female mold
24
is moved up with respect to the first female mold
23
in the direction Z
2
. By this movement, a space is formed between the first and second female molds
23
,
24
, serving to accommodate the substrate
16
on which a plurality of bumps (protruding electrodes)
12
are formed. In addition, in this state, the bumps
12
formed on the substrate
16
face toward the male mold
21
.
Further, a mold release sheet
30
is attached to the pressing surface
21
a,
and the encapsulating resin
35
is placed on the bumps
12
of the substrate
16
.
FIG. 2
is a top view, as seen from the male mold
21
, showing a state of the encapsulating resin
35
being placed on the bumps
12
. In this diagram, reference numeral
11
denotes a plurality of semiconductor chips before the substrate
16
is diced.
As previously described, when the process of mounting the substrate
16
and the process of providing the encapsulating resin
35
are completed, a process of forming a resin layer is performed. In the resin-layer forming process, the male mold
21
including the heater is moved down in the direction Z
1
while heating the encapsulating resin
35
, until the encapsulating resin
35
begins to melt.
The male mold
21
is thus moved down in the direction Z
1
to contact the second female mold
24
. Since the male mold
21
is provided with the mold release sheet
30
on the bottom thereof as previously described, when the male mold
21
contacts the second female mold
24
, as shown in
FIG. 3
, the mold release sheet
30
is clamped therebetween. Further, the male mold
21
is provided with a sucking groove
29
, which is connected to a vacuum source (not shown) and serves to suck a peripheral portion of the mold release sheet
30
so as to apply tension thereto. Such a configuration aims to prevent the mold release sheet
30
from generating wrinkles thereon. At this time, a cavity
28
, which is surrounded by the pressing surfaces
21
a,
25
and the cavity surface
26
, is formed within the split-mold
20
.
The male mold
21
is moved down while applying the pressure to the encapsulating resin
35
via the mold release sheet
30
. Further, while applying the pressure to the encapsulating resin
35
, the male mold
21
heats the encapsulating resin
35
so as to increase the temperature thereof to a value that can cause it to melt. Consequently, as shown in
FIG. 3
, the encapsulating resin
35
spreads out on the substrate
16
.
When the male mold
21
contacts the second female mold
24
, the mold release sheet
30
is clamped therebetween and is moved down together with them in the direction Z
1
. That is, the male mold
21
and the second female mold
24
are both moved down in the direction Z
1
.
The first female mold
23
, on the other hand, is kept in a fixed state as shown in
FIG. 4
, and therefore a capacity of the cavity
28
is decreased while the male mold
21
and the second female mold
24
are both moved down. Thus, the encapsulating resin
35
within the cavity
28
is further pressed and thereby a resin layer is formed on the substrate
16
.
With respect to the previously described manufacturing process, however, the pressing surface
21
a
of the male mold
21
is merely moved down and kept parallel with respect to the pressing surface
25
of the female mold
22
. In other words, the male mold
21
is moved down toward the female mold
22
until a distance therebewteen approximately becomes equal to the height of a CSP type semiconductor to be manufactured. This downward movement applies a high molding pressure to the encapsulating resin
35
and causes it to spread out.
With respect to the process of forming the resin layer on the substrate
16
, the molding pressure applied to a place (usually an approximately central portion of the substrate
16
) where the encapsulating resin is placed is liable to become excessively high compared to that applied to a peripheral portion of the substrate. For this reason, the semiconductor chips formed on the central portion of the substrate
16
may be encapsulated in a higher molding pressure with the encapsulating resin
35
. On the other hand, the semiconductor chips formed on the peripheral portion of the substrate
16
may be encapsulated in a lower molding pressure with encapsulating resin
35
.
As a result, the conventional method for manufacturing the semiconductor device and the conventional split-mold used therein suffer from the following disadvantages.
One disadvantage in the conventional method is that the thus-formed resin layer may have no uniformity and for this reason the semiconductor chips after the substrate
16
is diced may vary in performance.
Another disadvantage in the conventional method is that, with the development of miniaturization and thinness of the semiconductor device, the semiconductor chips formed on the central portion may be damaged by an excessively high molding pressure, whereas the semiconducto
Fujitsu Limited
Staas & Halsey , LLP
Talbott David L.
Zarneke David A.
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