U.S. patent application number 09/836182 was filed with the patent office on 2001-10-11 for method of fabricating semiconductor having through hole.
This patent application is currently assigned to FUJITSU LIMITED. Invention is credited to Honna, Koji, Kumagaya, Yoshikazu, Taniguchi, Fumihiko.
Application Number | 20010028101 09/836182 |
Document ID | / |
Family ID | 12667988 |
Filed Date | 2001-10-11 |
United States Patent
Application |
20010028101 |
Kind Code |
A1 |
Taniguchi, Fumihiko ; et
al. |
October 11, 2001 |
Method of fabricating semiconductor having through hole
Abstract
The semiconductor device includes a semiconductor chip, a tape
for mounting the semiconductor chip thereto, an adhesive resin
layer interposed between the semiconductor chip and the tape, and
solder balls attached to the tape. The method of fabricating the
semiconductor chip comprises the step of forming at least one hole
in the tape, after fixing the semiconductor chip to the tape
through the adhesive resin layer. Also, the TAB tape is made of
polyimide having high water permeability.
Inventors: |
Taniguchi, Fumihiko;
(Kawasaki-shi, JP) ; Honna, Koji; (Kawasaki-shi,
JP) ; Kumagaya, Yoshikazu; (Kawasaki-shi,
JP) |
Correspondence
Address: |
ARMSTRONG,WESTERMAN, HATTORI,
MCLELAND & NAUGHTON, LLP
1725 K STREET, NW, SUITE 1000
WASHINGTON
DC
20006
US
|
Assignee: |
FUJITSU LIMITED
Kawasaki
JP
|
Family ID: |
12667988 |
Appl. No.: |
09/836182 |
Filed: |
April 18, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09836182 |
Apr 18, 2001 |
|
|
|
09335878 |
Jun 18, 1999 |
|
|
|
09335878 |
Jun 18, 1999 |
|
|
|
09123450 |
Jul 28, 1998 |
|
|
|
5953592 |
|
|
|
|
Current U.S.
Class: |
257/666 ;
257/E21.505 |
Current CPC
Class: |
H01L 2924/01027
20130101; H01L 2924/12042 20130101; H01L 2924/0665 20130101; H01L
2924/3512 20130101; H01L 2224/32225 20130101; H01L 2224/73204
20130101; H01L 2924/15311 20130101; H01L 2924/01082 20130101; H01L
2924/01033 20130101; H01L 2924/01077 20130101; H01L 2924/15311
20130101; H01L 2224/73265 20130101; H01L 2224/73204 20130101; H01L
2924/01006 20130101; H01L 2924/12042 20130101; H01L 2224/48227
20130101; H01L 2224/32225 20130101; H01L 2224/73265 20130101; H01L
2924/00012 20130101; H01L 2924/00012 20130101; H01L 2224/16225
20130101; H01L 2224/73204 20130101; H01L 2224/48227 20130101; H01L
2924/00012 20130101; H01L 2924/00 20130101; H01L 2924/00 20130101;
H01L 2224/16225 20130101; H01L 2924/00012 20130101; H01L 2924/00
20130101; H01L 2924/0665 20130101; H01L 2924/00014 20130101; H01L
2224/83194 20130101; H01L 2924/01029 20130101; H01L 2924/07802
20130101; H01L 2924/01013 20130101; H01L 2924/01023 20130101; H01L
2224/8385 20130101; H01L 24/83 20130101; H01L 24/32 20130101; H01L
2224/48227 20130101; H01L 2224/48091 20130101; H01L 2224/32225
20130101; H01L 2924/00 20130101; H01L 2224/32225 20130101; H01L
2224/32225 20130101; H01L 2924/01004 20130101; H01L 2224/2919
20130101; H01L 2924/014 20130101; H01L 2224/48225 20130101; H01L
2924/0665 20130101; H01L 2224/16225 20130101; H01L 2224/2919
20130101; H01L 2224/73265 20130101; H01L 2924/15151 20130101; H01L
2224/48091 20130101; H01L 2924/15311 20130101 |
Class at
Publication: |
257/666 |
International
Class: |
H01L 023/495 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 25, 1998 |
JP |
10-43589 |
Claims
1. A method of fabricating a semiconductor device comprising a
semiconductor chip, a tape for mounting said semiconductor chip
thereto, an adhesive resin layer interposed between said
semiconductor chip and said tape, and solder balls arranged on said
tape, said method comprising the steps of: fixing said
semiconductor chip to said tape by said adhesive resin layer; and
forming at least one hole in said tape after the step of fixing
said semiconductor chip to said tape through said adhesive resin
layer.
2. A method of fabricating a semiconductor device, further
comprising the step of attaching said solder balls to said
tape.
3. A method of fabricating a semiconductor device according to
claim 2, characterized in that said step of attaching solder balls
to said tape is executed after the step of fixing said
semiconductor chip to said tape by said adhesive resin layer and
before the step of forming at least one hole.
4. A method of fabricating a semiconductor device according to
claim 1, characterized in that said step of forming at least one
hole is executed such that said at least one hole is formed through
said tape using a laser beam and reaches said adhesive resin
layer.
5. A method of fabricating a semiconductor device according to
claim 1, further comprising the step of sealing said semiconductor
chip with a sealing resin.
6. A method of fabricating a semiconductor device according to
claim 1, characterized in that said step of fixing said
semiconductor chip to the tape by said adhesive resin layer
includes the step of applying a die bonding material to said
tape.
7. A method of fabricating a semiconductor device according to
claim 1, characterized in that said step of fixing said
semiconductor chip to the tape by the adhesive resin layer includes
the step of attaching a buffer material to said tape and the step
of applying a die bonding material to said buffer material.
8. A method of fabricating a semiconductor device according to
claim 1, characterized in that said step of fixing said
semiconductor chip to the tape by said adhesive resin layer
includes the step of connecting said semiconductor chip to said
tape by protruding electrodes and the step of filling an
under-filling material between said semiconductor chip and said
tape.
9. A semiconductor device comprising a semiconductor chip, a tape
for mounting said semiconductor chip thereto, an adhesive resin
layer interposed between said semiconductor chip and said tape, and
solder balls arranged on said tape, characterized in that said tape
and said adhesive resin layer have at least one hole extending
through said tape and reaching said adhesive resin layer.
10. A semiconductor device according to claim 9, further comprising
a sealing resin for sealing said semiconductor chip, said adhesive
resin layer comprising a die bonding material for fixing said
semiconductor chip to said tape.
11. A semiconductor device according to claim 9, further comprising
a sealing resin for sealing said semiconductor chip, said adhesive
resin layer comprising a buffer material for reducing a stress
occurring due to the difference in coefficient of thermal expansion
between said semiconductor chip and said tape, and a die bonding
material for fixing said semiconductor chip to said tape through
said buffer.
12. A semiconductor device according to claim 9, characterized in
that said semiconductor chip is connected to said tape by protruded
electrodes, and said adhesive resin layer is made of an
under-filling material filled between said semiconductor chip and
said tape.
13. A semiconductor device according to claim 9, characterized in
that said tape is a FPC tape.
14. A semiconductor device comprising a semiconductor chip, a tape
for mounting said semiconductor chip thereto, an adhesive resin
layer interposed between said semiconductor chip and said tape, and
solder balls arranged on said tape, characterized in that said tape
is made of a material having high water permeability to prevent
cracking and bulging of said semiconductor device which might occur
when the solder balls are reflowed after said semiconductor device
absorbs moisture.
15. A semiconductor device according to claim 14, characterized in
that said tape is made of a resin having water permeability of 10
g/m.sup.2.multidot.24H or more.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a semiconductor device and
to a method of fabricating the same. In particular, the present
invention relates to a semiconductor device having a package
structure of a BGA or a CSP type and to a method of fabricating
such a semiconductor device.
[0003] 2. Description of the Related Art
[0004] In recent years, with the increasing demand for small, light
and thin electronic apparatuses, smaller, lighter, and thinner
semiconductor devices are required. In order to satisfy this
demand, semiconductor devices having package structures of the BGA
and the CSP types have been developed.
[0005] A semiconductor device having a package structure of a BGA
or a CSP type comprises a semiconductor chip, an FPC tape such as a
TAB tape for mounting the semiconductor chip thereto and solder
balls arranged on the TAB tape. The semiconductor chip is fixed to
the TAB tape by a die bonding material. The TAB tape has bonding
pads and ball pads, the bonding pads and the ball pads being
interconnected in the TAB tape by a wiring pattern. The
semiconductor chip is connected to the bonding pads of the TAB tape
by wires.
[0006] The solder balls are arranged on the ball pads of the TAB
tape and thus function as external electrodes. As a result, the
semiconductor chip and the solder balls are electrically connected
to each other by the TAB tape as an interposer. In the case where a
semiconductor device of surface mount type having solder balls
functioning as external terminals, such as a semiconductor device
of BGA or CSP type, is mounted to a motherboard, the semiconductor
device is, in general, heated in a solder reflowing equipment
having an ambiente temperature of about 250.degree. C. to connect
the melted solder balls to the electrode pads of the
motherboard.
[0007] Also, it is conceivable to attach a buffer resin sheet to
the TAB tape to reduce the stress arising due to the difference in
the coefficient of thermal expansion between the semiconductor chip
and the TAB tape, and to apply the die bonding material to the
buffer resin sheet to thereby fix the semiconductor chip to the TAB
tape.
[0008] In the semiconductor device in which the semiconductor chip
is fixed on to the TAB tape by the die bonding material and sealed
by the sealing resin, moisture is contained in the polyimide
constituting the TAB tape, the sealing resin and the die bonding
material. Especially, the polyimide making up the TAB tape is a
material which is easily absorbs moisture. Therefore, when the
solder balls are reflowed to mount the semiconductor device to the
motherboard, the moisture contained in the TAB tape, the sealing
resin and the die bonding material is evaporated with the increase
in temperature and the vapor causes cracking and/or bulging of the
semiconductor device.
[0009] In order to solve this problem, a method has been proposed
in which small holes are formed through the TAB tape before the
semiconductor chip is mounted to the TAB tape, so that the moisture
contained in the semiconductor device may be released through the
small holes when the solder balls are reflowed after the
semiconductor chip is mounted to the TAB tape. The cracking and
bulging of the semiconductor device can be prevented by releasing
the moisture contained in the semiconductor device.
[0010] However, if small holes are formed in the TAB tape in
advance, the die bonding material between the semiconductor chip
and the TAB tape may flow and may fill up the holes of the TAB tape
at the time of heat treatment during the fabrication process of the
semiconductor device, with the probable result that the holes fail
to function as vapor escape holes. It is also possible that the die
bonding material flows through holes of the TAB tape and
contaminates the reverse side of the TAB tape or the jigs or tools
to be used. In the case where the buffer resin sheet is attached to
the TAB tape, on the other hand, the buffer resin sheet blocks the
flow of the die bonding material, but the buffer resin sheet is
melted and fills up the holes of the TAB tape, often leading to the
failure of the holes to function as vapor escaping holes.
SUMMARY OF THE INVENTION
[0011] The object of the present invention is to provide a
semiconductor device and a method of fabricating the same which can
prevent cracking and bulging of the semiconductor device.
[0012] According to the present invention, there is provided a
method of fabricating a semiconductor device comprising a
semiconductor chip, a tape for mounting the semiconductor chip
thereto, an adhesive resin layer interposed between the
semiconductor chip and the tape and solder balls arranged on the
tape, the method comprising the steps of fixing the semiconductor
chip to the tape by the adhesive resin layer, and forming at least
one hole in the tape after the step of fixing the semiconductor
chip to the tape by the adhesive resin layer.
[0013] In this arrangement having at least one hole formed in the
tape, the moisture contained in the semiconductor device is
released through the at least one hole when the solder balls are
reflowed, to thereby prevent cracking and bulging of the
semiconductor device. Since the hole is formed after the step of
fixing the semiconductor chip to the tape by the adhesive resin
layer, the hole is not filled up with the adhesive resin layer
which may flow at the time of heat treatment during the
semiconductor fabrication process and thus effectively functions as
a vapor escape hole.
[0014] Preferably, the method further includes the step of
attaching the solder balls to the tape. The step of attaching
solder balls to the tape is executed after the step of fixing the
semiconductor chip to the tape by the adhesive resin layer and
before the step of forming the hole.
[0015] Preferably, the hole is formed through the tape using a
laser beam to such an extent as to reach the adhesive resin
layer.
[0016] Preferably, the method further comprises the step of sealing
the semiconductor chip with a sealing resin.
[0017] Preferably, the step of fixing the semiconductor chip to the
tape by the adhesive resin layer includes the step of applying a
die bonding material to the tape. As an alternative, the step of
fixing the semiconductor chip to the tap by the adhesive resin
layer includes the step of attaching a buffer material to the tape
and the step of applying a die bonding material to the buffer
material. As another alternative, the step of fixing the
semiconductor chip to-the tape by the adhesive resin layer includes
the step of connecting the semiconductor chip to the tape by
protruding electrodes and the step of filling an under-filling
material between the semiconductor chip and the tape.
[0018] A semiconductor device according to another aspect of the
present invention comprises a semiconductor chip, a tape for
mounting the semiconductor chip thereto, an adhesive resin layer
interposed between the semiconductor chip and the tape and solder
balls arranged on the tape and is characterized in that the tape
and the adhesive resin layer have at least one hole extending
through the tape and reaching the adhesive resin layer.
[0019] In this arrangement, the tape and the adhesive resin layer
having at least one hole formed through the tape and reaching the
adhesive resin layer are produced according to the method of
fabricating the semiconductor device described above and have the
same function and effect as the corresponding ones described above.
Specifically, when the solder balls are rendered to reflow, the
moisture contained in the semiconductor device is released through
the hole to thereby prevent cracking and bulging of the
semiconductor device. At the same time, the hole is not filled up
with the adhesive resin layer which flows at the time of the heat
treatment during the semiconductor fabrication process and
therefore effectively operates as a vapor escape hole.
[0020] Preferably, the semiconductor device comprises a sealing
resin for sealing the semiconductor chip, and the adhesive resin
layer is made of a die bonding material for fixing the
semiconductor chip to the tape. As an alternative, the
semiconductor device comprises a sealing resin for sealing the
semiconductor chip, and the adhesive resin layer includes a buffer
material for reducing the stress arising due to the difference in
the coefficient of thermal expansion between the semiconductor chip
and the tape and a die bonding material for fixing the
semiconductor chip to the tape by the buffer. As another
alternative, the semiconductor chip is connected to the tape by
protruding electrodes, and the adhesive resin layer is made of an
under-filling material filled between the semiconductor chip and
the tape.
[0021] Preferably, the tape is a FPC tape such as a TAB tape.
[0022] Further, the semiconductor device according to the present
invention comprises a semiconductor chip, a tape for mounting the
semiconductor chip thereto, an adhesive resin layer interposed
between the semiconductor chip and the tape, and solder balls
arranged on the tape, characterized in that the tape is made of a
material having high water permeability to prevent package cracking
and bulging which otherwise might be caused when the solder balls
are reflowed after the semiconductor device absorbs moisture.
[0023] In this arrangement, since the tape is made of a material
having high water permeability, the moisture contained in the
semiconductor device escapes from the tape thereby to prevent the
semiconductor device from developing cracking or bulging at the
time of solder ball reflow, similar to the above-mentioned case
where the tape has at least one hole.
[0024] Preferably, the tape is made of a resin having water
permeability of 10 (g/m .sup.224H) or more.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The present invention will become more apparent from the
following description of the preferred embodiments, with reference
to the accompanying drawings, in which:
[0026] FIG. 1 is a cross-sectional view of a semiconductor device
according to the first embodiment of the present invention;
[0027] FIG. 2 is a bottom view of the TAB tape of FIG. 1;
[0028] FIG. 3 is a cross-sectional view of the semiconductor
device, illustrating the manner in which vapor escaping holes are
formed in the TAB tape after the semiconductor device is
fabricated;
[0029] FIG. 4 is a cross-sectional view of the semiconductor device
of FIG. 1 and the mother board to which the semiconductor device is
mounted;
[0030] FIG. 5 is a cross-sectional view of the semiconductor device
according to the second embodiment of the invention;
[0031] FIG. 6 is a cross-sectional view of the semiconductor device
according to the third embodiment of the invention;
[0032] FIG. 7 is a cross-sectional view of the semiconductor device
according to the fourth embodiment of the invention;
[0033] FIG. 8 is a cross-sectional view of the semiconductor device
according to the fifth embodiment of the invention; and
[0034] FIG. 9 is a cross-sectional view of the semiconductor device
according to the sixth embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0035] FIGS. 1 and 2 show a semiconductor device according to the
first embodiment of the present invention. The semiconductor device
10 comprises a semiconductor chip 12, a TAB tape for mounting the
semiconductor chip 12 thereto, and an adhesive resin layer 16
interposed between the semiconductor chip 12 and the TAB tape 14.
The adhesive resin layer 16 includes a buffer sheet 18 for reducing
the stress occurring due to the difference in the coefficient of
thermal expansion between the semiconductor chip 12 and the TAB
tape 14, and a die bonding material 20 for fixing the semiconductor
chip 12 to the TAB tape 14 through the buffer sheet 18. In the
fabrication, the buffer sheet 18 is attached to the TAB tape 14,
the die bonding material 20 is applied to the buffer sheet 18, and
the semiconductor chip 12 is fixed to the TAB tape 14.
[0036] The TAB tape 14 has bonding pads 22 of copper and ball pads
24 of copper. The bonding pads 22 and the ball pads 24 are
interconnected by a wiring pattern (not shown) in the TAB tape 14.
The electrodes of the semiconductor chip 12 are connected to the
bonding pads 22 of the TAB tape 14 by wires 26.
[0037] Solder balls 28 are attached to the ball pads 24 of the TAB
tape 14, to function as external electrodes. Accordingly, the
semiconductor chip 12 and the solder balls 28 are electrically
connected to each other with the TAB tape 14 as an interposer. The
ball pads 24 are arranged on the upper surface of the TAB tape 14,
and the TAB tape 14 has ball mounting holes 30 for mounting the
solder balls 28. The solder balls 28 pass through the ball mounting
holes 30, so that the upper ends of the solder balls 28 are secured
to the ball pads 24 and the lower ends thereof protrude downward
from the TAB tape 14.
[0038] Further, vapor escaping holes 32 are formed through the TAB
tape 14 in such a manner as to reach the buffer sheet 18 and the
die bonding material 20. Furthermore, the semiconductor device
includes a sealing resin 34 for sealing the semiconductor chip
12.
[0039] The TAB tape 14 is of a structure having a plurality of
polyimide film layers bonded to each other by an epoxy adhesive.
The ball mounting holes 30 are formed in the TAB tape 14 in advance
by laser beam, punching, drilling, etching, or other means. The
vapor escaping holes 32, on the other hand, are not formed in
advance in the TAB tape 14, but are formed, at least after the
semiconductor chip 12 is mounted to the TAB tape 14, in such a
manner as to pass through the TAB tape 14 and reach the buffer
sheet 18 and the die bonding material 20.
[0040] FIG. 3 illustrates a method of fabricating the semiconductor
device 10 of FIG. 1. The basic process for fabricating the
semiconductor device 10 is well known and will be described only
briefly. The buffer sheet 18 is attached to the TAB tape 14, the
die bonding material 20 is applied to the buffer sheet 18, and the
semiconductor chip 12 is fixed to the TAB tape 14. The electrodes
of the semiconductor chip 12 are connected to the bonding pads 22
of the TAB tape 14 the wires 26. A transfer mold is carried out to
seal the semiconductor chip 12 by the sealing resin 34. Then, the
solder balls 28 are secured to the ball pads 24 of the TAB tape
14.
[0041] After that, as shown in FIG. 3, the vapor escaping holes 32
are formed by a laser beam (LB) so as to extend through the TAB
tape 14 and to reach the buffer sheet member 18 and the die bonding
material 20. The TAB tape 14 is then cut into pieces corresponding
to individual chips. The vapor escaping holes 32 can be formed
before or after securing the solder balls 28, or after cutting the
TAB tape 14, with the result that the identical effect can be
obtained.
[0042] FIG. 4 shows an example of surface-mounting the
semiconductor device 10 to the motherboard 36. In this case, at
least the solder balls 28 are heated to reflow, so that the solder
balls 28 are fused to the electrode pads 38 of the motherboard 36.
In the case where the semiconductor device 10 of surface-mounting
type such as a BGA or CSP semiconductor device having the solder
balls 28 as external terminals is mounted to the motherboard 36, in
general, the semiconductor device 10 is heated in a reflow
equipment having the ambience temperature of about 250.degree. C.,
to thereby connect the melted solder balls 28 to the electrode pads
38 of the motherboard 36.
[0043] In the solder reflowing, the moisture contained in the TAB
tape 14, the buffer sheet 18, the die bonding material 20 and the
sealing resin 34 of the semiconductor device 10 is heated, and the
resulting vapor is released out of the semiconductor device 10
through the vapor escape holes 32. Since the vapor is released out
of the semiconductor device 10 through the vapor escaping holes 32,
the semiconductor-device 10 is prevented from cracking and
bulging.
[0044] If the vapor escaping holes 32 are preformed in the TAB tape
14, a material of one or more of the buffer sheet 18, the die
bonding material 20 and the sealing resin 34 flows and leaks
through the vapor escape holes 32 or fills up the vapor escape
holes 32 during the heat treatment or the like step during the
fabrication process of the semiconductor device 10, so that the
vapor escaping holes 32 fail to function to release the vapor. In
the present invention, since the vapor escaping holes 32 are formed
after the semiconductor device 10 is formed (or preferably, after
the step of sealing the semiconductor chip 12 by the sealing resin
34), a material of the buffer sheet 18, the die bonding material 20
and/or the sealing resin 34 does not leak through the vapor
escaping holes 32 nor fill up the vapor escaping holes 32, and the
vapor escaping holes 32 thus can perform the function of releasing
the vapor when the solder balls are reflowed. Accordingly, cracking
and/or bulging of the semiconductor device, which otherwise might
occur at the time of solder reflowing, are prevented, and it is
possible to fabricate a BGA or CSP package having superior thermal
resistance in the solder reflowing process after moisture is
absorbed.
[0045] It is possible to form a multiplicity of minute vapor
escaping holes 32 at high speed and with high accuracy using a
laser beam, as shown in FIG. 2. It is preferable to use a secondary
high harmonic component of the YAG laser beam. The secondary high
harmonic component of the YAG laser beam has a wavelength of 0.532
.mu.m. A laser beam having a wavelength longer than 1 .mu.m can
pass through the semiconductor chip 12 and may destroy the
component elements (such as a transistor) of the semiconductor chip
12, so it is not suitable for use in the present invention.
Incidentally, the wavelength of the carbon dioxide gas laser beam
is 10.6 .mu.m, the wavelength of the YAG laser beam 1.06 .mu.m, and
the wavelength of the excimer laser beam 0.248 .mu.m.
[0046] In FIG. 1, the vapor escaping holes 32 are formed in such a
depth as to extend substantially through the die bonding material
20 and reach the back surface of the semiconductor chip 12.
However, the vapor escaping holes 32 are not necessarily so deep as
to reach the back surface of the semiconductor chip 12. Actually,
the component members (the TAB tape 14, the buffer sheet 18, the
die bonding material 20 and the sealing resin 34) have different
cohesive force and different water permeabilities, and therefore
the depth of the vapor escaping holes 32 should be determined
taking such properties into account.
[0047] Table 1 below shows the result of the experiment of thermal
resistance in the solder reflowing process of products having vapor
escaping holes 32 by formed laser beam (referred to as laser
holes).
1 TABLE 1 Laser Hole Hole Spec. Number of PKG Diameter Hole Pitch
Hole Bulges (mm) (mm) Number 24 H 48 H Sample No.1 0.1 0.8 100 0/15
0/39 Sample No.2 0.1 1.2 49 0/15 0/39 Sample No.3 0.1 1.6 25 0/15
0/39 Comparative -- No hole -- 15/15 -- sample 1
[0048] The thermal resistant test is carried out with respect to
samples in the form of tape-type BGAs (package size 16.quadrature.)
having 224 pins at the pitch of 0.8 mm. Sample Nos. 1 to 3 have
laser holes which are different in number, and comparative samples
have no laser holes. Specifically, as shown in FIG. 2, samples are
prepared, with vapor escape holes 32 having a diameter of 0.1 mm
.phi. formed by the secondary high harmonic component of a YAG
laser beam in the central portion in the back surface of the
224-pin tape-type BGA. In this experiment, the samples have three
different numbers of holes, i.e. 100, 49, 25 and the hole depth set
to reach the die bonding material 20, and the holes are formed
after attaching balls to the tape and-cutting the tape.
[0049] These samples (samples Nos.1 to 3) according to the
invention and the comparative samples 1 having no holes are
maintained in an atmosphere of 85.degree. C. in temperature and 85%
in humidity for 24 hours and 48 hours, and the IR reflow is then
conducted (at the reflow temperature of 250.degree. C. for about 10
seconds). Then, the bulging of the semiconductor devices (PKGs) is
observed. As a result, as shown in Table 1, the samples of the
semiconductor device having through holes do not exhibit no bulging
even after being held for 48 hours in the test atmosphere, but all
the samples of the semiconductor devices having no holes exhibit
bulging after being held for only 24 hours in the test
atmosphere.
[0050] FIG. 5 shows a semiconductor device according to the second
embodiment of the invention. The semiconductor device 10 comprises
a semiconductor chip 12, a TAB tape 14 for mounting the
semiconductor chip 12 thereto, and an adhesive resin layer 16
interposed between the semiconductor chip 12 and the TAB tape 14.
In this embodiment, the buffer sheet 18 of the first embodiment
shown in FIG. 1 is not provided and the adhesive resin layer 16
includes a die bonding material 20 for fixing the semiconductor
chip 12 to the TAB tape 14.
[0051] In the fabrication process, the die bonding material 20 is
applied to the TAB tape 14 and the semiconductor chip 12 is secured
by the TAB tape 14. The remaining parts are substantially the same
as the corresponding parts of the embodiment shown in FIG. 1. Also,
like the embodiment shown in FIG. 1, the vapor escape holes 32 are
formed through the TAB tape 14 so as to reach the die bonding
material 20. The vapor escape holes 32, do not reach the back
surface of the semiconductor chip 12.
[0052] The semiconductor device 10 according to this embodiment is
fabricated by the same steps as in the fabrication method of the
embodiment shown in FIG. 1, except that the step of bonding the
buffer sheet 18 in the embodiment of FIG. 1 is omitted. Also, the
operation of this embodiment is similar to that of the embodiment
shown in FIG. 1.
[0053] FIG. 6 shows a semiconductor device according to the third
embodiment of the present invention. The semiconductor device 10
comprises a semiconductor chip 12, a TAB tape 14 for mounting the
semiconductor chip 12 thereto, and an adhesive resin layer 16
interposed between the semiconductor chip 12 and the TAB tape 14.
This embodiment represents in an example in which the invention is
applied to a BGA or CSP package of tape type, connected by a flip
chip method. The semiconductor chip 12 includes protruding
electrodes 40 which are connected to bonding pads 22 of the TAB
tape 14. After the protruding electrodes 40 are connected to the
bonding pads 22, an under-filling material 42 is filled between the
semiconductor chip 12 and the TAB tape 14. This under-filling
material 42 constitutes the adhesive resin layer 16. The
semiconductor chip 12 can be sealed with a sealing resin.
[0054] After the under-filling material 42 is filled and set, vapor
escape holes 32 are formed through the TAB tape 14 in such a manner
as to reach the under-filling material 42. The vapor escaping holes
32 do not reach the back surface of the semiconductor chip 12. The
vapor escape holes 32 function as escape paths of the water vapor
when the solder is reflowed and can prevent the package from
cracking and bulging which might otherwise occur at the time of
solder reflowing. The under-filling material 42 is prevented from
leaking out, through the vapor escaping holes 32, by conducting the
step of forming the vapor escape holes 32 after the under-filling
material 42 is filled and set. Since the flip-chip method involves
face-down bonding, and the front surface of the semiconductor chip
12 faces the TAB tape 14, it is necessary to control the depth of
the holes formed by a laser beam so that the holes do not reach the
front surface of the semiconductor chip 12 but terminate within the
under-filling material 42.
[0055] FIG. 7 shows a semiconductor device according to the fourth
embodiment. Like in the embodiment of FIG. 1, the semiconductor
device 10 according to this embodiment comprises a semiconductor
chip 12, a TAB tape 14 for mounting the semiconductor chip 12
thereto, and an adhesive resin layer 16 interposed between the
semiconductor chip 12 and the TAB tape 14. The adhesive resin layer
16 includes a buffer sheet 18 and a die bonding material 20.
[0056] The TAB tape 14 includes bonding pads 22 and ball pads 24,
and the electrodes of the semiconductor chip 12 are connected to
the bonding pads 22 of the TAB tape 14 by wires 26. The solder
balls 28 are attached to the ball pads 24 of the TAB tape 14, and
function as external electrodes. Further, the semiconductor device
comprises a sealing resin 34 for sealing the semiconductor chip
12.
[0057] In this embodiment, the vapor escape holes 32 are not formed
unlike the embodiment shown in FIG. 1, but instead, the TAB tape 14
is made of polyimide having high water permeability (water vapor
permeability) in order to prevent the cracking and bulging of the
semiconductor device which otherwise might occur when the solder is
reflowed after the device absorbs moisture. Preferably, the TAB
tape 14 is made of polyimide resin having water permeability of not
less than 10 g/m.sup.2.multidot.24H. In this way, it is possible to
provide the polyimide base material with a similar effect to that
of the vapor escape holes 32 of the embodiment shown in FIG. 1, by
using polyimide having high water permeability as the base film of
the TAB tape 14. It is thus possible to produce a tape-type BGA or
CSP package well resistant to the reflowing.
[0058] Table 2 below shows the result of thermal resistance test in
the solder reflowing process of the semiconductor device (package)
10, using TAB tapes 14 having various levels of water
permeability.
2 TABLE 2 Sample Spec. Water Number of PKG Thickness Permeability
Bulging (.mu.m) (g/m.sup.2.24 H) 24 H 48 H Sample No.4 40 108.0
0/10 0/10 Sample No.5 50 14.5 0/18 0/18 Comparative 50 1.5 15/15
0/18 Sample 2
[0059] The samples are FBGA having 288 pins (0.75 mm pitches and
package size 18.quadrature.). The test conditions are the same as
conditions in the case of Table 1, i.e. THS (85.degree. C./85%,
24H, 48H)+IR (250.degree. C. Max 10 sec).
[0060] Sample No.4 is a double-layered TAB tape 14 using Espanex
Type SC18-40 from Shin-Nittetsu Chemical Industrial Co., Ltd. as
the base film. The water permeability of sample No.4 is 108.0,
which is 72 times as high as that of the comparative sample 2. The
water permeability of the TAB tape 14 using Espanex having the
thickness of 50 .mu.m is 86.4 (58 times as high as that of the
comparative sample 2).
[0061] Sample No.5 is the TAB tape 14 made of Capton Type 200EN
from Toray.multidot.Dupont Corporation. The water permeability of
sample No.5 is 14.5, which is 10 times as high as that of the
comparative sample 2. Sample No.6 in Table 3 below is the TAB tape
14 using Capton Type 200V. This material has water permeability of
37.3 (25 times as high as that of the comparative sample).
[0062] The comparative sample 2 is a three-layered TAB tape 14
using Upilex Type 50S from Ube Industries, Ltd. as a base film. The
conventional TAB tape 14 is made of Upilex in many cases.
[0063] The water permeability (water vapor permeability) is tested
by the method called Mocon method, using the equipment called
PERMATRAN-WID of Mocon. The Mocon method is the water vapor
permeability testing method, using an infrared sensor, based on JIS
K7128 or ASTM F1249.
[0064] The test is conducted in a manner similar to the first
embodiment. Specifically, the samples are maintained in an ambiente
of 85.degree. C./85% for 24 hours and 48 hours and the IR reflow
was conducted at the temperature of 250.degree. C. for about 10
seconds. Then, the bulging of the package is checked. The samples
including the TAB tapes using polyimide having high in water
permeability (water vapor permeability) as a base film do not show
any package bulging even after being allowed to stand for 48 hours
in the ambiente of 85.degree. C./85%, although vapor escaping holes
are not formed.
3 TABLE 3 Number of PKG bulging Water 1st 2nd 3rd Permeability test
test test Total Sample No.5 14.5 0/47 1/47 0/46 1/47 Sample No.6
37.3 0/41 0/41 0/41 0/41 Comparative 1.5 36/39 3/3 -- 39/39 Sample
2
[0065] The samples are FBGA of 48 pins (0.8 mm pitch, package size
6.times.9). The test conditions are three sets of THS {(85.degree.
C./85%, 24H)+IR (250.degree. C. Max 10 sec)}.
[0066] The result in Tables 2 and 3 shows that the cracking and the
bulging of the semiconductor devices which otherwise might occur at
the time of solder reflow after the devices absorbs moisture can be
prevented by producing the TAB tape 14 of polyimide having high
water permeability, even if the vapor escaping holes 32 in the
first embodiment are not formed. As seen from Tables 2 and 3,
sample No.5 having water permeability of 14.5 produced a
satisfactory result. This indicates that the recommendable water
permeability of the TAB tape 14 is 10 or more.
[0067] FIG. 8 shows a semiconductor device according to the fifth
embodiment of the present invention. The semiconductor device 10
comprises a semiconductor chip 12, a TAB tape 14 for mounting the
semiconductor chip 12 thereto, and an adhesive resin layer 16
interposed between the semiconductor chip 12 and the TAB tape 14.
In this embodiment, the buffer sheet 18 in the embodiment of FIG. 7
is omitted, and the adhesive resin layer 16 comprises a die bonding
material 20 for fixing the semiconductor chip 12 to the TAB tape
14. The TAB tape 14, like the TAB tape 14 of FIG. 7, is made of
polyimide having high water permeability. Therefore, the function
of the semiconductor device of FIG. 8 is similar to that of the
embodiment shown in FIG. 7.
[0068] FIG. 9 shows a semiconductor device according to the sixth
embodiment of the invention. The semiconductor device 10 comprises
a semiconductor chip 12, a TAB tape 14 for mounting the
semiconductor chip 12 thereto, and an adhesive resin layer 16
interposed between the semiconductor chip 12 and the TAB tape 14.
This embodiment is an example in which the invention is applied to
a BGA or CSP package of tape type, connected by a flip chip method.
The semiconductor chip 12 has protruding electrodes 40 which are
connected to bonding pads 22 of the TAB tape 14. After the
protruding electrodes 40 are connected to the bonding pads 22, an
under-filling material 42 is filled between the semiconductor chip
12 and the TAB tape 14. This under-filling material 42 constitutes
the adhesive resin layer 16. The TAB tape 14 is made of polyimide
having high water permeability, like the TAB tape 14 of FIG. 7.
Consequently, the semiconductor device of FIG. 9 functions in a way
similar to the embodiment of FIG. 7.
[0069] As described above, according to the present invention,
since at least one hole is formed through the tape, the moisture
contained in the semiconductor device is released by the hole when
the solder balls are reflowed, and the semiconductor device is
prevented from cracking and bulging. Since the at least one hole is
formed after the step of fixing the semiconductor chip to the tape
by the adhesive resin layer, the hole is not filled up with the
adhesive resin layer flowing by heat treatment during the
semiconductor fabrication process and thus effectively functions as
a water vapor escape hole.
[0070] Also, in order to provide a similar effect to the through
hole, by using a TAB tape using polyimide base layer having high
water permeability, a BGA or CSP package of a tape type having
superior resistance to the reflowing procedure can be produced,
even without forming a through hole.
* * * * *