U.S. patent application number 12/869461 was filed with the patent office on 2010-12-23 for circuit device and method of manufacturing thereof.
This patent application is currently assigned to Sanyo Electric Co., Ltd.. Invention is credited to Yasunori Inoue, Hideki Mizuhara, Ryosuke Usui.
Application Number | 20100323498 12/869461 |
Document ID | / |
Family ID | 37394531 |
Filed Date | 2010-12-23 |
United States Patent
Application |
20100323498 |
Kind Code |
A1 |
Usui; Ryosuke ; et
al. |
December 23, 2010 |
Circuit Device and Method of Manufacturing Thereof
Abstract
A circuit device of preferred embodiments of the present
invention includes: a circuit element with electrodes formed in a
peripheral part thereof; connecting portions connected to surfaces
of the electrodes; and redistribution lines which are continuous to
the respective connecting portions and extended in parallel to the
main surface of the circuit element. In preferred embodiments of
the present invention, the connecting portions and the
redistribution lines are integrally formed of one piece of metal.
Accordingly, there is no place where different materials are
connected in a portion between the connecting portions and the
redistribution lines, thus improving a joint reliability of the
entire device against a thermal stress or the like.
Inventors: |
Usui; Ryosuke; (Aichi,
JP) ; Inoue; Yasunori; (Gifu, JP) ; Mizuhara;
Hideki; (Aichi, JP) |
Correspondence
Address: |
FISH & RICHARDSON P.C. (NY)
P.O. BOX 1022
MINNEAPOLIS
MN
55440-1022
US
|
Assignee: |
Sanyo Electric Co., Ltd.
Osaka
JP
|
Family ID: |
37394531 |
Appl. No.: |
12/869461 |
Filed: |
August 26, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11410476 |
Apr 24, 2006 |
7808114 |
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12869461 |
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Current U.S.
Class: |
438/460 ;
257/E21.214 |
Current CPC
Class: |
H01L 2224/274 20130101;
H01L 2924/01073 20130101; H01L 2224/05 20130101; H01L 21/561
20130101; H01L 2224/13022 20130101; H01L 2924/014 20130101; H01L
2924/01033 20130101; H01L 2924/01013 20130101; H01L 2224/0239
20130101; H01L 24/03 20130101; H01L 2224/0401 20130101; H01L 24/13
20130101; H01L 2924/0002 20130101; H01L 2924/01078 20130101; H01L
2924/01005 20130101; H01L 2224/131 20130101; H01L 2924/0002
20130101; H01L 2924/351 20130101; H01L 2224/05548 20130101; H01L
2224/13147 20130101; H01L 2924/351 20130101; H01L 2924/14 20130101;
H01L 23/4951 20130101; H01L 2221/68377 20130101; H01L 2224/13144
20130101; H01L 2924/01019 20130101; H01L 2924/01029 20130101; H01L
2924/01079 20130101; H01L 2224/0231 20130101; H01L 2924/14
20130101; H01L 2924/0105 20130101; H01L 2224/02319 20130101; H01L
24/05 20130101; H01L 2224/131 20130101; H01L 2224/02313 20130101;
H01L 2224/0233 20130101; H01L 2224/05567 20130101; H01L 2924/01004
20130101; H01L 2924/01014 20130101; H01L 21/4828 20130101; H01L
2924/01022 20130101; H01L 2924/00 20130101; H01L 2924/01006
20130101; H01L 2224/05552 20130101; H01L 2924/014 20130101; H01L
2924/00014 20130101; H01L 23/3114 20130101; H01L 2924/00 20130101;
H01L 24/11 20130101 |
Class at
Publication: |
438/460 ;
257/E21.214 |
International
Class: |
H01L 21/302 20060101
H01L021/302 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 28, 2005 |
JP |
P2005-131130 |
Claims
1-6. (canceled)
7. A method of manufacturing a circuit device, comprising:
preparing a semiconductor wafer having an electrode connected to
each of integrated circuits on a surface thereof; etching a
conductive foil to form a connecting portion in a position
corresponding to a position of the electrode, wherein the
connecting portion is protruding; connecting the semiconductor
wafer and the conductive foil to connect the connecting portion and
the electrode; etching the conductive foil to form a redistribution
line, wherein the etching is performed from a surface opposite to a
surface on which the connecting portion is formed.
8. The method of manufacturing a circuit device according to claim
1, further comprising: coating a region other than a region having
an external electrode connecting the redistribution line by a
resist.
9. The method of manufacturing a circuit device according to claim
2, wherein the semiconductor wafer and the conductive foil are
connected with a first soldering material, wherein a melting point
of the first soldering material is higher than that of a second
soldering material constituting the external electrode.
10. The method of manufacturing a circuit device according to claim
2, further comprising: separating the semiconductor wafer into
individual circuit devices by dicing the semiconductor wafer.
11. The method of manufacturing a circuit device according to claim
1 further comprising: roughening a top surface of the connecting
portion.
12. The method of manufacturing a circuit device according to claim
1, wherein a side surface of the connecting portion has a shape
broadening to surroundings.
Description
[0001] Priority is claimed to Japanese Patent Application Number
JP2005-131130 filed on Apr. 28, 2005, the disclosure of which is
incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a circuit device and a
method of manufacturing thereof, and specifically, relates to a
circuit device of a size equal to a size of a circuit element and a
method of manufacturing thereof.
[0004] 2. Description of the Related Art
[0005] When electronic equipment such as mobile phones are
miniaturized and sophisticated, circuit devices used in such
equipment are also required to be further miniaturized.
[0006] A structure to package a highly-integrated circuit element
has changed from a conventional QFP (Quad Flat Package) to a CSP
(Chip Size Package). The CSP packages are formed by dicing a wafer
which has external connection electrodes formed on a main surface
thereof. Accordingly, each of the CSP packages is capable of being
bonded to a mounting substrate with a size equal to that of the
circuit element, and a side of the mounting substrate on which the
CSP packages are mounted is capable of being miniaturized.
Employing the CSP, therefore, enables an entire set of a mobile
phone or the like to be miniaturized.
[0007] In the CSP, redistribution lines are formed on a main
surface of the circuit element to redistribute electrodes of the
circuit element. The electrodes of the circuit element are usually
formed in a peripheral part of the circuit element which is not an
area where integrated circuits are formed. A pitch between these
electrodes is, for example, 70 .mu.m and is very small, which makes
solder connection difficult. The redistribution lines are therefore
formed on the main surface of the circuit element in order to
arrange external electrodes connected to the electrodes in a
matrix. A pitch between the external electrodes is, for example,
about 500 .mu.m, which facilitates the solder connection.
[0008] With reference to FIG. 7, a description is given of a
circuit device 100 of the conventional CSP type. The circuit device
100 includes an integrated circuit formed on a surface of a circuit
element 101, and electrodes 104 which are connected to this
integrated circuit are arranged in a peripheral part of the circuit
device 100. The surface of the circuit element 101 is coated with a
protection film 102 except in places where the electrodes 104 are
exposed. The protection film 102 is a PSG (phospho-silicate-glass)
film, a Si.sub.3N.sub.4 (silicon nitride) film, or the like.
[0009] Bumps 108 are formed on the respective electrodes 104 by a
wire bonding technique and have a shape with an upper part
constricted. Each of the bumps 108 is coated with a resin layer 103
except in an upper surface.
[0010] On an upper surface of the resin layer 103, redistribution
lines 106 electrically connected to the respective bumps 108 are
extended. Each redistribution line 106 is extended inward from the
respective electrodes 104 located in the peripheral part of the
circuit element 101. The redistribution lines 106 are coated with a
resist 109 except in places where external electrodes 107 made of
solder or the like are formed. This technology is described for
instance in the Japanese Patent Application Publication No. Hei
9-64049.
[0011] However, in the aforementioned circuit device 100 of the
conventional type, each path from the electrodes 104 to the
respective redistribution lines 106 is made of different materials,
thus causing a problem of poor joint reliability. Specifically, the
bumps 108 were made of gold, copper, solder, or the like, and the
redistribution lines 106 are generally made of copper. Therefore,
the bumps 108 and the redistribution lines 106 are made of
different materials in some cases, and thermal stress occurs in an
interface therebetween following a change in temperature.
Accordingly, disconnection may occur where the bumps 108 are joined
with the respective redistribution lines 106. Furthermore, a shape
of the bumps 108 is not a shape which is deformed following a
thermal stress, which added to the problem.
[0012] Furthermore, because of the bumps 108, this conventional
type is not capable of being applied to a miniaturized circuit
element. A diameter of the bumps 108 formed by the wire bonding
technique is about 30 to 60 .mu.m, and the electrode 104 needed to
be larger than that. Accordingly, there is a problem that the bumps
108 cannot be formed in a circuit element having minute electrodes
with a side length of not more than 30 .mu.m.
[0013] Still furthermore, there is a problem that forming the bumps
108 by the wire bonding technique increases manufacturing costs of
the CSP.
SUMMARY OF THE INVENTION
[0014] The present invention is made in the light of the
aforementioned problems, and a primary object of the present
invention is to provide an improved circuit device with an improved
joint reliability and a method of manufacturing thereof.
[0015] The present invention provides a circuit device that
includes a circuit element, a connecting portion connected to an
electrode of the circuit element, and a redistribution line which
is continuous to the connecting portion and extended in parallel to
a main surface of the circuit element substantively, wherein the
connecting portion and the redistribution line are integrally
formed of one piece of metal.
[0016] Furthermore, in the circuit device of the present invention,
the redistribution line and the connecting portion are made of
rolled metal.
[0017] Furthermore, in the circuit device of the present invention,
the redistribution line is coated with a resist and that a post
continuous to the redistribution line is exposed to an outside of
the circuit device by penetrating the resist.
[0018] Furthermore, in the circuit device of the present invention,
the post is formed of a metal integrated with the connecting
portion and the redistribution line.
[0019] The present invention provides a method of manufacturing a
circuit device. The method includes preparing a semiconductor wafer
having an electrode connected to each of integrated circuits on a
surface thereof, providing an isolation trench on a surface of a
conductive foil to form a connecting portion protruded in a
position corresponding to a position of the electrode,
superimposing the semiconductor wafer on the conductive foil to
connect the connecting portion and the electrode, filling a space
between the semiconductor wafer and the conductive foil with a
filling resin, patterning the conductive foil to form a
redistribution line for each of the integrated circuits, and dicing
the semiconductor wafer to separate the semiconductor wafer into
individual circuit elements.
[0020] Furthermore, in the method of manufacturing a circuit device
of the present invention, the isolation trench is filled with a
first filling resin to cause an upper surface of the connecting
portion to be exposed, before the semiconductor wafer is
superimposed on the conductive foil, and in that a space between
the first filling resin and the semiconductor wafer is filled with
a second filling resin after the semiconductor wafer is
superimposed on the conductive foil.
BRIEF DESCRIPTION OF THE INVENTION
[0021] FIGS. 1A and 1B are a cross-sectional view and a plan view
showing a circuit device of preferred embodiments of the present
invention, respectively.
[0022] FIGS. 2A and 2B are cross-sectional views showing circuit
devices of preferred embodiments of the present invention.
[0023] FIGS. 3A to 3C are perspective views and a cross sectional
view showing a method of manufacturing a circuit device of
preferred embodiments of the present invention, respectively.
[0024] FIGS. 4A to 4E are cross-sectional views showing a method of
manufacturing a circuit device of preferred embodiments of the
present invention.
[0025] FIGS. 5A to 5D are cross-sectional views showing a method of
manufacturing a circuit device of preferred embodiments of the
present invention.
[0026] FIGS. 6A to 6D are cross-sectional views showing a method of
manufacturing a circuit device of preferred embodiments of the
present invention.
[0027] FIG. 7 is a cross-sectional view showing a conventional
circuit device.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] Hereinafter, a description is given of embodiments of the
present invention with reference to drawings.
[0029] First, a description is given of a configuration of a
circuit device 10A of an embodiment with reference to FIGS. 1A and
1B. FIG. 1A is a representative cross-sectional view of the circuit
device 10A, and FIG. 1B is a plan view of a surface of the circuit
device 10A in which external electrodes 17 and the like are
formed.
[0030] Referring to FIG. 1A, the circuit device 10A includes a
circuit element 11, connecting portions 15, redistribution lines
16, and pads 20. On a surface of the circuit element 11, electrodes
14 are formed. The connecting portions 15 are connected to exposed
surfaces of the electrodes 14. The redistribution lines 16 are
formed integrally with the respective connecting portions 15 and
extended in parallel to the surface of the circuit element 11. The
pads 20 are connected to the respective redistribution lines 16 and
arranged in a matrix. On surfaces of the pads 20, the external
electrodes 17 are individually formed.
[0031] The circuit element (semiconductor element) 11 includes a
predetermined electrical circuit which is formed in a known
diffusion process on a surface of a semiconductor substrate with a
thickness of about 100 .mu.m. Moreover, the surface of the circuit
element 11 is coated with a protection film 12 which has a
thickness of about several micrometers, in order to protect the
electrical circuit 11 formed on the surface. The protection film 12
is a PSG (Phospho-Silicate-Glass) film, a Si.sub.3N.sub.4 (silicon
nitride) film, or the like. The surfaces of the electrodes 14 are
exposed from this protection film 12.
[0032] The electrodes 14 are connected to the electrical circuit
formed on the surface of the circuit element 11, and a number of
the electrodes 14 are located in a peripheral part of the circuit
element 11. Generally, a material of the electrodes 14 is aluminum.
Each electrode 14 is very minutely formed with a size of, for
example, about 30 square .mu.m to 50 square .mu.m. A pitch of the
electrodes 14 is also very small.
[0033] On the surface of each electrode 14, a barrier film may be
formed. This barrier film can be made of Ti, Ta, TiN, TaN, TiW,
TaW, WN, or the like. Moreover, these metals may be layered to form
the barrier film. Forming the barrier film on the surfaces of the
electrodes 14 is capable of preventing Cu, which is a material of
the connecting portions 15, from being diffused to the electrodes
14, even when the connecting portion 15 abut on the electrodes
14.
[0034] The connecting portions 15 are made of rolled metal such as
copper, and lower surfaces of the connecting portions 15 abut on
the surfaces of the respective electrodes 14. A height of the
connecting portions 15 is, for example, about 90 .mu.m. Moreover,
the connecting portions 15 are cylindrical or rectangular cylinder,
and a width thereof is about 30 to 50 .mu.m. The connecting
portions 15 are elongated as described above, and thus the
connecting portions 15 themselves are capable of being deformed to
reduce a thermal stress. The connecting portions 15 are continuous
to and integrated with the respective redistribution lines 16 and
extend to the surfaces of the respective electrodes 14 by
penetrating a filling resin 13.
[0035] Preferably, lower surfaces of the connecting portions 15
abutting on the surfaces of the electrodes 14 are roughened. This
is capable of increasing a connection strength between the
electrodes 14 and the connecting portions 15 which are joined to
each other by pressure bonding. Furthermore, a surface of the
connecting portion 15 abutting on each electrode 14 is partially
buried in the electrode 14, and a joint reliability thereof is
capable of being improved.
[0036] The electrodes 14 and the connecting portions 15 are joined
to each other by pressure bonding, but can be connected with a
conductive joint material such as solder or conductive paste. When
the electrodes 14 and connecting portions 15 are joined using
solder, solder with a melting point higher than that of solder
constituting the external electrodes 17 is employed. The
redistribution lines 16 are made of a metal integrated with the
respective connecting portions 15 and extend in parallel to the
surface of the circuit element 11. The redistribution lines 16
include a function to connect the electrodes 14 arranged in the
peripheral part of the circuit element 11 at a small pitch with the
pads 20 arranged in inner part of the circuit element 11 at a large
pitch. The pitch of the electrodes 14 is, for example, about 50 to
70 .mu.m, and the pitch of the pads 20 is, for example, about 500
.mu.m. Connecting the pads 20 at the large pitch and the electrodes
14 at the small pitch using the redistribution lines 16 in such a
manner is capable of facilitating mounting of the circuit device
10A. In other words, electrical conductive paths of a mounting
substrate on which the circuit device 10A is to be mounted are not
needed to be arranged at a fine pitch.
[0037] In this embodiment, each of the connecting portion 15 and
the redistribution line 16 are integrally formed of one piece of
metal. In other words, the path from each electrode 14 of the
circuit element 11 to the external electrode 17 does not include a
place where different materials are connected to each other.
Accordingly, even when a thermal stress acts on the connecting
portions 15 or the redistribution lines 16 due to a change in
temperature or the like when the circuit device 10A is in use, a
disconnection and the like are less likely to occur.
[0038] Furthermore, the connecting portions 15, the redistribution
lines 16, and the pads 20 are made of rolled metal such as rolled
copper and the like. Long axes of crystal grains constituting the
rolled metal extend in parallel to a direction in which the
redistribution lines 16 extend. Compared to metal formed by plating
and the like, the rolled metal is superior in mechanical strength.
Furthermore, the rolled metal is superior to the plated metal also
in terms of flexibility. Based on the above description, the rolled
metal is suitable as a metal integrally constituting each
connecting portion 15 and the redistribution line 16 connected
thereto.
[0039] Furthermore, the redistribution lines 16 are formed on an
upper surface of the filling resin 13, which is provided to coat
the protection film 12. Herein, a thickness of the filling resin 13
is about 90 .mu.m, which is equal to a height of the connecting
portions 15 In other words, the redistribution lines 16 extend so
as to be distanced from the protection film 12, which protects the
surface of the circuit element 11. Accordingly, even if a change in
temperature produces different expansions in the redistribution
lines 16 and the circuit element 11, the thermal stress is reduced
by the filling resin 13, which is located between the
redistribution lines 16 and the circuit element 11. It is therefore
possible to prevent a reduction in the joint reliability caused by
the thermal stress.
[0040] The filling resin 13 can be either a thermoplastic resin or
a thermosetting resin. Alternatively, the filling resin 13 can be
resin such as epoxy resin mixed with filler. The filling resin 13
mixed with the filler can improve heat radiation and furthermore
bring a thermal expansion coefficient of the filling resin 13 close
to that of the circuit element 11. The filler can be fibers or
particles of SiO.sub.2, SiN, Al.sub.2O.sub.3, or the like.
[0041] The pads 20 are formed in a matrix within an area surrounded
by the electrodes 14 in the circuit element 11. The pitch between
the pads 20 is, for example, about 500 .mu.m. As described above,
the pads 20 are made of a metal integrated with the respective
connecting portions 15 and the redistribution lines 16. On the
surfaces of the pads 20, the external electrodes 17 are
individually formed.
[0042] The external electrodes 17 are made of solder, conductive
paste, or the like and bonded to exposed surfaces of the pads 20
each being partially exposed from a resist 19. As described above,
the pitch of the external electrodes 17 is as large as, for
example, about 500 .mu.m.
[0043] The surfaces of the redistribution lines 16 and the filling
resin 13 are coated with the resist 19 except areas where the
external electrodes 17 are formed.
[0044] Referring to FIG. 1B, the connecting portions 15 connected
to the electrodes 14 of the circuit element 11 are located in the
peripheral part of the circuit device 10A. The pads 20 and the
external electrodes 17 are arranged in a matrix within an area
surrounded by the connecting portions 15. The redistribution lines
16 extend between the connecting portions 15 and the pads 20.
[0045] With reference to FIGS. 2A and 2B, a description is given of
configurations of circuit devices 10B and 10C of other embodiments.
FIGS. 2A and 2B are cross-sectional views of the circuit devices
10B and 10C, respectively.
[0046] Referring to FIG. 2A, in the circuit device 10B, a filling
resin 13 is composed of a first filling resin 13A and a second
filling resin 13B. The other configuration of the circuit device
10B is the same as that of the circuit device 10A.
[0047] The first filling resin 13A is resin formed on the
redistribution lines 16 side and composed of resin mixed with
filler. The first filling resin 13A is formed before the connecting
portions 15 are caused to abut on electrodes 14. Accordingly, a
large amount of filler (for example, 50 wt % or more) can be mixed.
A method of forming the first filling resin 13A and the like are
described later.
[0048] The second filling resin 13B is a resin provided on the
circuit device 11 side and composed of epoxy resin or the like
which is basically not mixed with filler. If the second filling
resin 13B is mixed with filler, an amount of the filler is less
than that of the first filling resin 13A. Space between the first
filling resin 13A and a protection resin 12 is filled with the
second filling resin 13B after the connecting portions 15 are
caused to abut on the electrodes 14.
[0049] Referring to FIG. 2B, in the circuit device 10C, posts 18
extending upward and protruding from respective redistribution
lines 16 are formed. A thickness of the posts 18 is, for example,
about 100 to 200 .mu.m. Upper surfaces of the posts 18 are exposed
from a resist 19, and external electrodes 17 are bonded thereto.
The posts 18 are deformable according to a stress laterally acting
thereon. It is therefore possible to reduce a thermal stress acting
on the external electrodes 17 and thus improve a joint reliability
of the external electrodes 17. Furthermore, the posts 18 are formed
of a rolled metal integrated with the respective redistribution
lines 16 and connecting portions 15 and have a high joint
reliability against a thermal stress. The other configuration of
the circuit device 10C is the same as that of the circuit device
10A.
[0050] Next, a description is given of a method of manufacturing
the above circuit devices with reference to the drawings from FIGS.
3A.
[0051] Referring to FIGS. 3A to 3C, first, a semiconductor wafer 30
and a conductive foil 40 are prepared. FIGS. 3A to 3C are a
perspective view of the semiconductor wafer 30, a perspective view
of the conductive foil 40, and a cross-sectional view of the
conductive foil 40, respectively.
[0052] Referring to FIG. 3A, on a surface of the semiconductor
wafer 30 subjected to a diffusion process and the like, integrated
circuits are formed in a matrix. Electrodes 14 connected to each
integrated circuit are formed in a peripheral part of the
semiconductor wafer 30. In the following description, the
integrated circuit and the electrodes 14 which serve as one circuit
device are referred to as a unit 31. Between each unit 31, a dicing
line 32 is located.
[0053] Referring to FIGS. 3B and 3C, next, connecting portions 15
which are protruded are formed on a surface of the conductive foil
40. A plane size of the conductive foil 40 is substantially equal
to that of the semiconductor wafer 30. Specifically, when the
semiconductor wafer 30 has a diameter of 8 inches (200 mm), the
conductive foil 40 whose size is substantially equal to this size
of the semiconductor wafer 30 is prepared. A thickness of the
conductive foil 40 is, for example, about 120.mu.m.
[0054] The connecting portions 15 are formed by selectively etching
a surface of the conductive foil 40. Specifically, sections in the
surface of the conductive foil 40 in which the connecting portions
15 are to be formed are coated with an etching resist 41, and then
the surface of the conductive film 40 is etched. On the surface of
the conductive foil 40, an isolation trench 42 is thus formed, and
the connecting portions 15 which are not etched are convexly
protruded. A height of the connecting portions 15 is, for example,
about 90 .mu.m. Two dimensional positions of the connecting
portions 15 accurately correspond to those of respective electrodes
14 formed on the surface of the semiconductor wafer 30. Herein, a
pitch of the connecting portions 15 formed in an etching process is
capable of being formed to be very minute, which is, for example,
about 10 .mu.m.
[0055] Preferably, upper surfaces of the connecting portions 15 are
subjected to a roughening process. The roughening process is
capable of increasing, in a subsequent process, a joint reliability
between the electrodes 14 of the semiconductor wafer and the
connecting portions 15. The roughening process of the upper
surfaces of the connecting portions 15 can be performed by etching,
a CZ process, a plasma treatment, or the like. Herein, the CZ
process is a roughening process performed using a liquid mixture of
formic acid and hydrochloric acid.
[0056] Next, a description is given of subsequent processes with
reference to cross-sectional views of FIGS. 4A to 4E. In FIGS. 4A
to 4E, a method of manufacturing the circuit device 10A shown in
FIGS. 1A and 1B is described.
[0057] Referring to FIGS. 4A and 4B, next, the semiconductor wafer
30 and the conductive foil 40 are superimposed on each other so
that the upper surfaces of the connecting portions 15 are
pressure-bonded to the respective electrodes 14 of each unit 31.
Herein, the conductive foil 40 is placed on a horizontal table, and
the semiconductor wafer 30 is placed on an upper side of the
conductive foil 40. The semiconductor wafer 30 is superimposed on
the conductive foil 40 so that positions of the electrodes 14
correspond to positions of the connecting portions 15 while the
positions of the electrodes 14 and the connecting portions 15 are
being checked with a camera. The connecting portions 15 and the
electrodes 14 are connected by pressure bonding but may be
connected using a conductive joint material such as solder or
conductive paste. The connecting portions 15 and the electrodes 14
which are pressure-bonded are shown in FIG. 4B. Since a thickness
of the semiconductor wafer 30 is as large as, for example, about
600 .mu.m, a warpage or cracks are less likely to occur in moving
the semiconductor wafer 30 in this process.
[0058] Referring to FIG. 4C, next, space between the conductive
foil 40 and the semiconductor wafer 30 is filled with a filling
resin 13. The filling resin 13 can be either thermoplastic resin or
thermosetting resin. When the thermosetting resin such as epoxy
resin is employed as the filling resin 13, the liquid filling resin
13 which is filled is heat hardened. In this embodiment, the
connecting portions 15 are formed by etching, and a side face of
each connecting portion 15 therefore has a shape broadening toward
a bottom the connecting portion 15. Accordingly, a connecting
portion between the connecting portions 15 and the conductive foil
40 is easily filled with the filling resin 13.
[0059] Referring to FIG. 4D, next, the conductive foil 40 is etched
from a rear surface to form redistribution lines 16 and pads 20.
Specifically, etching is performed, after sections of the
conductive foil corresponding to sections in which the
redistribution lines 16 and pads 20 are to be formed, are coated
with the etching resist 41. In this process, a thickness of the
conductive foil 40 in an area in which etching is performed is
about 30 .mu.m, and the redistribution lines 16 and the pads 20 are
capable of being formed to be minute. Furthermore, in this process,
the conductive foil 40 is removed from between each unit 31 by
etching.
[0060] Referring to FIG. 4E, next, resist 19 is formed so that the
redistribution lines 16 and the pads 20 are coated with the resist
19. The resist 19 is partially removed so that a rear surface of
each pad 20 is partially exposed. Furthermore, external electrodes
17 made of solder or the like are bonded to surfaces of the
respective pads 20 exposed from the resist 19. After the end of
this process, the semiconductor wafer 30 is diced at places
indicated by dashed lines to separate each unit 31.
[0061] With the aforementioned processes, the circuit device 10A
shown in FIGS. 1A and 1B is manufactured.
[0062] Next, a description is given of a method of manufacturing
the circuit device 10B shown in FIG. 2A. This manufacturing method
is different from the aforementioned manufacturing method in that a
filling resin 13 is composed of a first filling resin 13A and a
second filling resin 13B.
[0063] Referring to FIG. 5A, first, a semiconductor wafer 30 and a
conductive foil 40 are superimposed on each other so that upper
surfaces of connecting portions 15 abut on respective electrodes
14. This method is the same as the aforementioned method. Herein,
before the semiconductor wafer 30 and the conductive foil 40 are
superimposed on each other, the first filling resin 13A is applied
to an isolation trench 42 formed in the surface of the conductive
foil 40. The first filling resin 13A is composed of resin mixed
with filler.
[0064] A method of applying the first filling resin 13A to fill the
isolation trench 42 with the first filling resin 13A is as follows.
First, the first filling resin 13A is applied to an entire surface
of the conductive foil 40. Next, the first filling resin 13A is
scratched away using a squeegee so as to be thinned in sections in
which the connecting portions 15 are coated with the first filling
resin 13A. Furthermore, when the first filling resin 13A is
thermosetting resin, heat hardening is performed. Next, the
conductive foil 40 is immersed in a solution of potassium
permanganate. The first filling resin 13A is therefore thinned
overall, and upper surfaces of the connecting portions 15 are
exposed from the first filling resin 13A.
[0065] The first filling resin 13A is mixed with a large amount of
filler and has a low fluidity in some cases. Accordingly, it is
difficult to fill a space between the semiconductor wafer 30 and
the conductive foil 40 with the first filling resin 13A after the
semiconductor wafer 30 and the conductive foil 40 are superimposed
on each other. In this embodiment, therefore, the first filling
resin 13A is previously formed on the surface of the conductive
foil 40.
[0066] Referring to FIG. 5B, next, a space between the conductive
foil 40 and the semiconductor wafer 30 is filled with the second
filling resin 13B. The space between the conductive foil 40 and the
semiconductor wafer 30 is narrowed since the first filling resin
13A is formed on the surface of the conductive foil 40. For
example, when a thickness of the first filling resin 13A is about
50 .mu.m, a space between the first filling resin 13A and the
semiconductor wafer 30 is about 40 .mu.m thick. Accordingly, the
space between the first filling resin 13A and the semiconductor
wafer 30 is capable of being easily filled with the second filling
resin 13B by a capillary action to prevent a formation of
voids.
[0067] The second filling resin 13B is composed of resin such as
epoxy resin and the like not mixed with filler. Alternatively, if
the second filling resin 13B is mixed with filler, an amount of the
filler is less than that of the first filling resin 13A.
Accordingly, the second filling resin 13B is excellent in a
fluidity, and is capable of filling a narrow space as described
above.
[0068] Referring to FIG. 5C, next, the conductive foil 40 is
selectively etched to form redistribution lines 16 and pads 20.
[0069] Referring to FIG. 5D, next, resist 19 is formed so that the
redistribution lines 16 and the pads 20 are coated with the resist
19. Furthermore, external electrodes 17 are formed on the
respective pads 20 exposed from the resist 19. Finally, the
semiconductor wafer 30 is diced at places indicated by dashed lines
so as to separate each unit 31, thus obtaining individual circuit
devices. The circuit device 10B shown in FIG. 2A is manufactured in
the aforementioned process.
[0070] Next, with reference to FIGS. 6A to 6D, a description is
given of a method of manufacturing a circuit device 10C whose
configuration is shown in FIG. 2B. This manufacturing method is
different from the aforementioned manufacturing method in
manufacturing posts 18.
[0071] Referring to FIG. 6A, first, a conductive foil 40 and a
semiconductor wafer 30 are superimposed on each other, and a space
formed between the conductive foil 40 and the semiconductor wafer
30 is filled with a filling resin 13. Herein, as described above,
the filling resin 13 may be composed of a first filling resin 13A
and a second filling resins 13B.
[0072] Referring to FIG. 6B, next, a rear surface of the conductive
foil 40 where the posts 18 are to be formed are coated with an
etching resist 41A, and then the conductive foil 40 is etched from
the rear surface. The posts 18 convexly protruding downward of the
paper are formed in this process.
[0073] Referring to FIG. 6C, next, the rear surface of the
conductive foil 40 is coated with a different etching resist 41B,
and then etching is performed to form redistribution lines 16.
[0074] Referring to FIG. 6D, next, the redistribution lines 16 are
coated with a resist 19 in a way that an upper portion of the posts
18 are exposed from the resist 19. On the posts 18 exposed from the
resist 19, the external electrodes 17 made of solder or the like
are bonded.
[0075] In the aforementioned processes, the circuit device 10C
whose structure is shown in FIG. 2B is formed.
[0076] With the circuit device of the embodiments of the present
invention, the connecting portion connected to the electrode of the
circuit element and the retribution line is capable of being
integrally formed of one piece of metal. It is therefore possible
to improve the joint reliability against thermal stress in a path
from the electrode of the circuit element to the external
electrode.
[0077] Moreover, the connecting portion and redistribution line are
formed of rolled metal. Accordingly, the joint reliability against
the thermal stress is capable of being further improved.
[0078] Furthermore, the redistribution line is formed to be
distanced from a protection film protecting the surface of the
circuit element. In other words, a height of the connecting portion
is designed to be higher than a thickness of the protection film.
Accordingly, the connecting portion which is formed to be high is
deformed following a change in temperature, and is capable of
reducing the thermal stress, thus improving the joint
reliability.
[0079] Still furthermore, mixing a filler in the filling resin
located between the circuit element and the redistribution line is
capable of improving a heat radiation of the entire circuit
device.
[0080] Still furthermore, according to the method of manufacturing
the circuit device of the embodiments of the present invention, the
connecting portion and the redistribution line are minutely formed
by etching. Accordingly, the embodiments of the present invention
can be applied to a circuit element having minute electrodes formed
at a small pitch. It is therefore possible to configure the circuit
device adopting the sophisticated circuit element.
[0081] Still furthermore, the path from the electrode of the
circuit element to the external electrode is capable of being
formed of one conductive foil by etching. Therefore a manufacturing
process of the CSP-type circuit device is capable of being
simplified, and furthermore, manufacturing costs are capable of
being reduced.
[0082] Still furthermore, an upper surface of the connecting
portion is caused to abut on the electrode of the circuit element
after the upper surface of the connecting portion is roughened.
Accordingly, the joint reliability between the connecting portion
and the electrode is capable of being improved.
* * * * *