U.S. patent application number 09/842487 was filed with the patent office on 2001-10-25 for manufacturing method for semiconductor device, mounting method of semiconductor device, semiconductor device, and inspecting method of semiconductor device.
This patent application is currently assigned to Matsushita Electric Industrial Co., Ltd.. Invention is credited to Bessho, Yoshihiro, Eda, Kazuo, Ono, Masahiro, Shiraishi, Tsukasa.
Application Number | 20010033032 09/842487 |
Document ID | / |
Family ID | 17977882 |
Filed Date | 2001-10-25 |
United States Patent
Application |
20010033032 |
Kind Code |
A1 |
Ono, Masahiro ; et
al. |
October 25, 2001 |
Manufacturing method for semiconductor device, mounting method of
semiconductor device, semiconductor device, and inspecting method
of semiconductor device
Abstract
A manufacturing method for a semiconductor device using a wire
bonding method using a metal wire. In the wire bonding method, an
impact load applied when a metal ball formed at the tip of the
metal wire by electric discharge is brought into contact with a
terminal electrode of a semiconductor device is smaller than a
static load applied after the metal ball is brought into contact
with the terminal electrode. The method makes it possible to
prevent an element or wiring from being damaged while securing the
pressure necessary for bonding the metal ball to the terminal
electrode even when the terminal electrode is placed on the element
or the wiring.
Inventors: |
Ono, Masahiro; (Osaka,
JP) ; Shiraishi, Tsukasa; (Osaka, JP) ;
Bessho, Yoshihiro; (Osaka, JP) ; Eda, Kazuo;
(Nara, JP) |
Correspondence
Address: |
Douglas P. Mueller
MERCHANT & GOULD P.C.
P.O. Box 2903
Minneapolis
MN
55402-0903
US
|
Assignee: |
Matsushita Electric Industrial Co.,
Ltd.
Osaka
JP
|
Family ID: |
17977882 |
Appl. No.: |
09/842487 |
Filed: |
April 25, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09842487 |
Apr 25, 2001 |
|
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09427807 |
Oct 27, 1999 |
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Current U.S.
Class: |
257/782 ;
257/E21.508 |
Current CPC
Class: |
H01L 2224/05022
20130101; H01L 2224/05572 20130101; H01L 2224/05001 20130101; H01L
24/85 20130101; H01L 2924/01082 20130101; H01L 24/11 20130101; H01L
2924/01024 20130101; H01L 2924/01005 20130101; H01L 2224/85205
20130101; H01L 2224/48465 20130101; H01L 2924/01033 20130101; H01L
2924/01028 20130101; H01L 2224/48091 20130101; H01L 2924/01047
20130101; H01L 2224/85181 20130101; H01L 2924/14 20130101; H01L
2924/01079 20130101; H01L 2924/01013 20130101; H01L 2924/01039
20130101; H01L 2924/01078 20130101; H01L 2924/13091 20130101; H01L
2224/1134 20130101; H01L 2224/16 20130101; H01L 2224/78301
20130101; H01L 2224/81191 20130101; H01L 2924/0105 20130101; H01L
2924/01327 20130101; H01L 2924/01029 20130101; H01L 24/78 20130101;
H01L 2224/13099 20130101; H01L 24/13 20130101; H01L 2924/01006
20130101; H01L 24/16 20130101; H01L 24/48 20130101; H01L 24/05
20130101; H01L 2924/014 20130101; H01L 2924/01022 20130101; H01L
2924/01046 20130101; H01L 2224/451 20130101; H01L 2924/01015
20130101; H01L 2224/0508 20130101; H01L 24/45 20130101; H01L
2224/05027 20130101; H01L 2224/48091 20130101; H01L 2924/00014
20130101; H01L 2224/85181 20130101; H01L 2224/48465 20130101; H01L
2224/48465 20130101; H01L 2224/48091 20130101; H01L 2924/00
20130101; H01L 2924/13091 20130101; H01L 2924/00 20130101; H01L
2224/451 20130101; H01L 2924/00 20130101; H01L 2224/451 20130101;
H01L 2924/00014 20130101; H01L 2224/85205 20130101; H01L 2924/00
20130101; H01L 2224/1134 20130101; H01L 2924/00014 20130101 |
Class at
Publication: |
257/782 |
International
Class: |
H01L 023/52 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 29, 1998 |
JP |
10-308180 |
Claims
What is claimed is:
1. A manufacturing method for a semiconductor device using a wire
bonding method using a metal wire, wherein in said wire bonding
method, an impact load applied when a metal ball formed at the tip
of said metal wire by electric discharge is brought into contact
with a terminal electrode of a semiconductor device is smaller than
a static load applied after said metal ball is brought into contact
with said terminal electrode.
2. The method for manufacturing a semiconductor device according to
claim 1, wherein said metal ball is used for forming a bump.
3. The method for manufacturing a semiconductor device according to
claim 1, wherein said metal wire is used for bonding the terminal
electrode of the semiconductor device to an input/output terminal
electrode of a circuit board.
4. The method for manufacturing a semiconductor device according to
claim 1, wherein said terminal electrode is formed on an element or
wiring provided inside said semiconductor device.
5. The method for manufacturing a semiconductor device according to
claim 1, wherein an ultrasonic wave is applied at least after said
static load is applied.
6. The method for manufacturing a semiconductor device according to
claim 1, wherein the impact load per said metal ball is 0.441 N or
less, the static load is 0.981 N or less and the pressure applied
to said terminal electrode after said static load is applied is 140
MPa or less.
7. The method for manufacturing a semiconductor device according to
claim 1, wherein the difference between the impact load per said
metal ball and said static load is 0.736 N or less.
8. The method for manufacturing a semiconductor device according to
claim 1, wherein said metal ball is formed of at least one metallic
material selected from the group consisting of Au, Al, Pd, Pb, Sn,
Cu, In, Bi, Ti and Ni.
9. A method for mounting a semiconductor device, comprising
mounting a circuit board provided with a bump on an input/output
terminal electrode to a semiconductor device by bonding the tip of
said bump to said terminal electrode of said semiconductor device,
wherein an impact load applied when said bump is brought into
contact with said semiconductor device is smaller than a static
load applied after said bump is brought into contact with said
terminal electrode.
10. The method for mounting a semiconductor device according to
claim 9, wherein the tip of said bump has a needle shape.
11. The method for mounting a semiconductor device according to
claim 10, wherein said needle-shaped portion comprises a flat
portion having a diameter of 40 .mu.m or less.
12. The method for mounting a semiconductor device according to
claim 9, wherein the tip of said bump has a spherical shape.
13. The method for mounting a semiconductor device according to
claim 9, wherein the terminal electrode of said semiconductor
device is formed on the element or the wiring provided inside said
semiconductor device.
14. The method for mounting a semiconductor device according to
claim 9, wherein an ultrasonic wave is applied at least after said
static load is applied.
15. The method for mounting a semiconductor device according to
claim 9, wherein the impact load per said bump is 0.441 N or less,
the static load is 0.981 N or less, the pressure applied to said
terminal electrode after said static load is applied is 140 MPa or
less.
16. The method for mounting a semiconductor device according to
claim 9, wherein the difference between the impact load per said
bump and said static load is 0.736 N or less.
17. The method for mounting a semiconductor device according to
claim 9, wherein said bump is formed by a wire bonding method and
formed of at least one metallic material selected from the group
consisting of Au, Al, Pd, Pb, Sn, Cu, In, Bi, Ti and Ni.
18. The method for mounting a semiconductor device according to
claim 9, wherein said bump is formed by plating and formed of at
least one metallic material selected from the group consisting of
Au, Al, Pd, Cu, Ni, Ti, Cr and Ag.
19. The method for mounting semiconductor electrode according to
claim 9, wherein said bump is formed by a printing method and
formed of at least one metallic material selected from the group
consisting of Ag, Pd, Pt, Cu, Ni, Pb, Sn and Bi.
20. A method for inspecting a semiconductor device used for a
method for manufacturing a semiconductor device by a wire bonding
method using metal wire, wherein a probe needle for inspection is
brought into contact with a region on said terminal electrode other
than a region in which the metal ball formed at the tip of said
metal wire by electric discharge is bonded to said terminal
electrode among regions on the terminal electrode of the
semiconductor device.
21. The method for inspecting a semiconductor device according to
claim 20, wherein said terminal electrode is formed on the element
or the wiring provided inside said semiconductor device.
22. A semiconductor device manufactured by a wire bonding method
using a metal wire, comprising a region with which a probe needle
for inspection is brought into contact in addition to a region in
which the metal ball formed at the tip of said metal wire by
electric discharge is bonded to said terminal electrode formed on
the semiconductor device.
23. The semiconductor device according to claim 22, wherein said
terminal electrode is formed on the element or the wiring inside
said semiconductor device.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a manufacturing method and
a mounting method for a semiconductor device, which are capable of
being performed even in a case where a terminal electrode (pad) for
bonding is placed on an element or wiring.
BACKGROUND OF THE INVENTION
[0002] Recently, as portable type electronic equipment has become
smaller and has had a higher performance, a semiconductor device,
etc. has been required to have a small size and high performance.
In order to meet these requirements, it is necessary to increase
the number of terminal pins, to reduce the pitch or to make an area
arrangement. In this case, however, there is a limit for reducing
the pitch. In order to further reduce the pitch, it is important to
mount a terminal electrode on an element or wiring as well.
[0003] According to such a mounting, when a bump is formed or
mounted on the terminal electrode provided at the semiconductor
side, if extremely high pressure is applied, the element inside the
semiconductor device may be destroyed or cracks may occur in an
insulating layer. Thus, an electric current leak occurs between the
insulating layer and the wiring. For example, in a technique using
a wire boding method, the impact load may damage the element or the
wiring. Therefore, a technique where a terminal electrode is
provided on the element or the wiring as well has not been
established. Therefore, when the wire bonding method is used, it is
necessary to form a terminal electrode outside the element or the
wiring. Moreover, the wiring had to be drawn out of the
semiconductor device.
[0004] Therefore, in the prior art in which the area bonding can be
performed, the mounting technique is mainly based on a plating
bump. Examples of such techniques include a mounting technique
using a solder bump. The technique is developed by IBM Ltd. and
generally called C4 (Controlled Collapse Chip Connection).
[0005] FIG. 8 is a schematic cross-sectional view of a bonding
structure of a semiconductor device of the above-mentioned mounting
technique. An SiO.sub.2 film 116 is formed on a substrate 118 and
an Al terminal electrode 117 is formed on the SiO.sub.2 film 116.
On the terminal electrode 117, a solder bump 111 is formed via a
glass protective film 115 and metal films 112, 113 and 114.
[0006] According to a literature "Mounting Technique of
Electronics" (August (1996), pages 78-83), an aluminum oxide film
is formed on the surface of aluminum that is a material of the
terminal electrode 117 of an IC chip. After removing this oxide
film, the metal films, called barrier metals, 112, 113 and 114 are
formed by vacuum evaporation, and then the solder bump 111 is
formed. As a material for each film, for example, a Cu--Sn
intermetallic compound for the metal film 112, a Cr--Cu alloy for
the metal film 113 and Cr for the metal film 114 are used,
respectively.
[0007] This solder bump 111 is brought into contact with an
input/output terminal electrode of a circuit board and then reflow
is performed. As a result, the solder bump 111 is melted and the
bonding between the solder bump 111 and the input-output terminal
of the circuit board is completed.
[0008] Moreover, the bump is not limited to the solder bump alone.
An Au plating bump may be formed after the barrier metal is
formed.
[0009] In these techniques, it is not necessary to apply load when
the bump is formed. Therefore, in a case where the terminal
electrode is formed on an active element of the IC chip, even if
the bump is formed on the terminal electrode, the active element of
the IC chip can be prevented from being damaged.
[0010] However, in these techniques, plating or treatments
accompanying the plating are carried out. Therefore, a device for
plating, a waste liquid treatment and a washing treatment, etc. are
required, thus raising the manufacturing cost. In addition, it is
necessary to cope with environmental problems, separately.
Consequently, it has been difficult to put these techniques of the
prior art into practical use as a consumer product.
[0011] As mentioned above, circuits of the semiconductor device
have become finer. There was a problem in terms of securing an
electrode for electric current to flow in such finer circuits.
Furthermore, in a case where the electroless plating is performed,
it is very difficult to unify the height of the bump, so that the
reliability of the mounted body remains a problem.
SUMMARY OF THE INVENTION
[0012] It is therefore an object of the present invention to
provide a manufacturing method and a mounting method for a
semiconductor device, which are capable of preventing an element or
wiring from being destroyed even if a wire bonding method is used,
to provide a semiconductor device used for the above-mentioned
methods, and to an inspecting method of a semiconductor device.
[0013] In order to achieve the above-mentioned object, the
manufacturing method for a semiconductor device uses a wire bonding
method using a metal wire, in the wire bonding method, an impact
load applied when a metal ball formed at the tip of the metal wire
by electric discharge is brought into contact with a terminal
electrode of a semiconductor device is smaller than a static load
applied after the metal ball is brought into contact with the
terminal electrode. With such a manufacturing method for the
semiconductor device, by making the impact load smaller than the
static load, even when the terminal electrode is placed on an
element or wiring, the element or the wiring can be prevented from
being damaged while securing the pressure necessary for bonding the
metal ball to the terminal electrode.
[0014] It is preferable in the above-mentioned manufacturing method
of a semiconductor device that the metal ball is used for forming a
bump.
[0015] Furthermore, it is preferable that the metal wire is used
for bonding the terminal electrode of the semiconductor device to
an input/output terminal electrode of a circuit board.
[0016] Furthermore, it is preferable that the terminal electrode is
formed on an element or wiring provided inside the semiconductor
device.
[0017] Furthermore, it is preferable that an ultrasonic wave is
applied at least after the static load is applied. By applying an
ultrasonic wave, the bonding between the metal ball and the
terminal electrode can be stabilized.
[0018] Furthermore, it is preferable that the impact load per metal
ball is 0.441 N or less, the static load is 0.981 N or less and the
pressure applied to the terminal electrode after the static load is
applied is 140 MPa or less.
[0019] Furthermore, it is preferable that the difference between
the impact load per metal ball and the static load is 0.736 N or
less.
[0020] Furthermore, it is preferable that the metal ball is formed
of at least one metallic material selected from the group
consisting of Au, Al, Pd, Pb, Sn, Cu, In, Bi, Ti and Ni.
[0021] Next, according to the mounting method for a semiconductor
device of the present invention mounts a circuit board provided
with a bump on an input/output terminal electrode to a
semiconductor device by bonding the tip of the bump to the terminal
electrode of the semiconductor device, wherein an impact load
applied when the bump is brought into contact with the
semiconductor device is smaller than a static load applied after
the bump is brought into contact with the terminal electrode. With
such a mounting method of the semiconductor device, by making the
impact load smaller than the static load, even when the terminal
electrode is placed on an element or the wiring, the element or
wiring can be prevented from being damaged while securing the
pressure necessary for bonding the metal ball to the terminal
electrode.
[0022] It is preferable in the above-mentioned mounting method that
the tip of the bump has a needle shape.
[0023] Furthermore, it is preferable that the needle-shaped portion
comprises a flat portion having a diameter of 40 .mu.m or less.
[0024] Furthermore, it is preferable that the tip of the bump has a
spherical shape.
[0025] Furthermore, it is preferable that the terminal electrode of
the semiconductor device is formed on the element or the wiring
provided inside the semiconductor device.
[0026] Furthermore, it is preferable that an ultrasonic wave is
applied at least after the static load is applied. By applying an
ultrasonic wave, the bonding between the metal ball and the
terminal electrode can be stabilized.
[0027] Furthermore, it is preferable that the impact load per metal
ball is 0.441 N or less, the static load is 0.981 N or less, and
the pressure applied to the terminal electrode after the static
load is applied is 140 MPa or less.
[0028] Furthermore, it is preferable that the difference between
the impact load per bump and the static load is 0.736 N or
less.
[0029] Furthermore, it is preferable that the bump is formed by a
wire bonding method and formed of at least one metallic material
selected from the group consisting of Au, Al, Pd, Pb, Sn, Cu, In,
Bi, Ti and Ni.
[0030] Furthermore, it is preferable that the bump is formed by
plating and formed of at least one metallic material selected from
the group consisting of Au, Al, Pd, Cu, Ni, Ti, Cr and Ag.
[0031] Furthermore, it is preferable that the bump is formed by a
printing method and formed of at least one metallic material
selected from the group consisting of Ag, Pd, Pt, Cu, Ni, Pb, Sn
and Bi.
[0032] Next, according to the inspecting method for a semiconductor
of the present invention, the method is used for a method for
manufacturing a semiconductor device by the wire bonding method
using metal wire, wherein a probe needle for inspection is brought
into contact with a region on the terminal electrode other than a
region in which the metal ball formed at the tip of the metal wire
by electric discharge is bonded to the terminal electrode. With
such an inspecting method of a semiconductor device, even if the
probe needle is brought into contact with the terminal electrode
and causes the loss of the terminal electrode made of e.g.
aluminum, etc., the loss is not related to the region in which the
bump is formed. Therefore, the stable bonding can be realized.
[0033] It is preferable in the above-mentioned inspecting method of
a semiconductor device that the terminal electrode is formed on the
element or the wiring inside the semiconductor device.
[0034] Next, the semiconductor device of the present invention is
manufactured by the wire bonding method using a metal wire,
comprising a region with which a probe needle for inspection is
brought into contact, other than the region in which the metal ball
formed at the tip of the metal wire by electric discharge is bonded
to the terminal electrode formed on the semiconductor device. With
such an inspecting method for a semiconductor device, even if the
probe needle is brought into contact with the terminal electrode
and causes the loss of the terminal electrode made of, e.g.
aluminum, etc., the loss is not related to the region in which the
bump is formed. Therefore, the stable bonding can be realized.
[0035] It is preferable in the above-mentioned semiconductor device
that the terminal electrode is formed on the element or the wiring
provided inside the semiconductor device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] FIG. 1A is a schematic view showing a part of a method for
forming a bump of a semiconductor device in a first embodiment
according to the present invention.
[0037] FIG. 1B is a graph showing one example of a bonding process
according to the present invention.
[0038] FIG. 2A is a graph showing a relationship between the static
load f, the diameter R of a seating and the height H of a seating
according to the present invention.
[0039] FIG. 2B is a graph showing a relationship between a static
load f and pressure P applied to a terminal electrode according to
the present invention.
[0040] FIG. 2C shows a diameter of a seating according to the
present invention.
[0041] FIG. 3A is a cross-sectional view showing a state right
before an impact load is applied to a terminal electrode by wire
bonding according to the present invention.
[0042] FIG. 3B is a cross-sectional view showing a state when a
terminal electrode is bonded to an input/output terminal electrode
by a metal wire according to the present invention.
[0043] FIG. 3C is a graph showing one example of a bonding process
according to the present invention.
[0044] FIG. 4A is a schematic cross-sectional view showing a method
for inspecting a semiconductor device in a third embodiment
according to the present invention.
[0045] FIG. 4B is a view showing one example of a square-shaped
terminal electrode seen from above in the third embodiment
according to the present invention.
[0046] FIG. 5A is a cross-sectional view of a semiconductor device
in a fourth embodiment according to the present invention.
[0047] FIG. 5B is a view of a semiconductor seen from above in the
fourth embodiment according to the present invention.
[0048] FIG. 6A is a schematic cross-sectional view showing a
mounting process for a semiconductor in a fifth embodiment
according to the present invention.
[0049] FIG. 6B is a graph showing one example of a bonding process
according to the present invention.
[0050] FIG. 7A is a schematic cross-sectional view showing a
mounting process of a semiconductor device in a sixth embodiment
according to the present invention.
[0051] FIG. 7B is a graph showing one example of a bonding process
according to the present invention.
[0052] FIG. 8 is a schematic cross-sectional view of a bonding
structure of a semiconductor device of a prior art.
DETAILED DESCRIPTION OF THE INVENTION
[0053] Hereinafter, the present invention will be described by way
of embodiments with reference to drawings.
[0054] First Embodiment
[0055] FIG. 1A is a schematic view showing a part of a method for
forming a bump of a semiconductor device in a first embodiment of
the present invention. In a semiconductor device 5 shown in FIG.
1A, three insulating layers 4a, 4b and 4c are formed on a substrate
provided with an element 3b. In the insulating layers, wiring 3a is
formed. On the insulating layer 4a, a terminal electrode 1 is
formed. More specifically, in the semiconductor device 5 shown in
FIG. 1, the terminal electrode 1 is formed on the element 3b and
the wiring 3a provided inside the semiconductor device 5. The
terminal electrode 1 is formed primarily of, for example, aluminum.
Moreover, the element 3b is an active element such as a transistor,
etc. or a passive element such as resistance, etc.
[0056] In this embodiment, a bump is formed on the terminal
electrode 1 by the wire bonding method. As shown in FIG. 1A, at the
tip of a metal wire 2, a metal ball 2a is formed by electric
discharge. The metal ball 2a is formed primarily of, for example,
Au. However, it may be formed of at least one metallic material
selected from the group consisting of Au, Al, Pd, Pb, Sn, Cu, In,
Bi, Ti and Ni.
[0057] The metal ball 2a is pressed against the terminal electrode
1 by a pressure tool 6. With this embodiment, the impact load is
applied to the terminal electrode 1 when the metal ball 2a is
pressed against. After the impact load is applied, sequentially the
static load is applied. FIG. 1B shows one example of the bonding
process. T of the abscissa shows time, F of the ordinate shows the
magnitude of the load and t1 in FIG. 1B shows a time in which an
ultrasonic wave is applied (the same is true in the following FIGS.
2C, 5B and 6B). In the example of this figure, the load per metal
ball is 0.245 N (25 gram weight) for the impact load as shown by
the remark 5 and 0.392 N (40 gram weight) for the static load as
shown by the remark 6.
[0058] Main constituent factors related to the impact load include
the speed when the metal ball is brought into contact with the
terminal electrode, a detection load that is a reference with which
the device detects that the metal ball is brought into contact with
the terminal electrode, the size of the metal ball, and the like.
In order to reduce the impact load, the speed is preferably small.
Furthermore, the detection load is preferably small because load is
applied until the load reaches to the reference load. In addition,
as to the metal ball, especially for an Au ball that is soft, the
larger the Au ball is, the greater the effect of relaxing the
impact is. Therefore, it is preferable that the Au ball is large.
After the impact load is applied, the static load is applied so as
to stabilize the bonding property of the metal ball. In general, it
is preferable that an ultrasonic wave is used together in order to
secure the stability.
[0059] Herein, a state right after the metal ball 2a made of Au,
etc. is brought into contact with the terminal electrode 1 is
described. Until the metal ball 2a is sufficiently crushed, the
contact area between the metal ball 2a and the terminal electrode 1
is small. Therefore, stress is tends to be concentrated on the
contact portion, and thus a high pressure is applied thereto.
Therefore, by reducing the impact load, the element 3b or the
wiring 3a placed below the terminal electrode 1 can be prevented
from being damaged. The load for bonding can be secured by making
the static load applied after the impact load is applied larger
than the impact load. When the impact load is applied, the metal
ball 2a is sufficiently crushed. Therefore, even if the static load
is increased, the pressure applied to the terminal electrode 1 can
be reduced such that damage to the element 3b or the wiring 3a
placed below the terminal electrode 1 can be prevented. Moreover,
the damage herein denotes the deterioration of the property, the
electric current leak due to the occurrence of cracks, or the
like.
[0060] In other words, according to this embodiment, by making the
impact load smaller than the static load, even if the terminal
electrode is placed on the element or the wiring, the element or
the wiring can be prevented from being damaged while securing the
pressure necessary for bonding. Furthermore, since the technique of
this embodiment does not require a washing process, the cost can be
reduced. Further, it is not necessary to cope especially with
environmental problems. Furthermore, since bonding to the terminal
electrode on the element or the wiring is possible, the terminal
electrode is not required to be formed outside the element or the
wiring to thus enable a miniaturization of the device. Furthermore,
since the wiring is not required to be drawn out of the device, the
cost can be reduced and higher performance can be realized.
[0061] Hereinafter, this embodiment will be explained more
specifically by way of the experiment results. Table 1 shows the
conditions for bonding the Au ball to the terminal electrode. These
conditions can be used for forming the bump and for performing the
wire bonding method.
1TABLE 1 Time for Stage Detec- Output of applying Ball tem- Search
tion Static ultrasonic ultrasonic size pera- Con- speed load load
wave wave (.mu.m ture dition (mm/s) (N) (N) (mW) (msec) .phi.)
(.degree. C.) (A) 5 0.441 0.294 100 20 50 230 (B) 15 0.588 0.392
100 20 50 230 (C) 30 0.981 0.981 100 20 50 230 (D) 5 0.441 0.294
200 20 50 230
[0062] The impact load depends upon the speed when the Au ball is
brought into contact with the terminal electrode (hereinafter,
"search speed" will be referred to) and the detection load. When
the search speed is large, even if the device detects the detection
load, the control for inhibiting the load does not follow.
Therefore, actually, load greater than the detection load is
applied to the terminal electrode. In this case, the load greater
than the detection load is an impact load. When the impact load is
actually measured under the conditions (A), (B) and (C) of Table 1,
the measurement results shown in Table 2 were obtained.
2 TABLE 2 Condition (A) (B) (C) Impact load 0.441 N 0.735 N 1.961
N
[0063] The impact load shown in Table 2 was measured by using a
pressure sensor. As shown in Table 2, as in the conditions (A)
where the search speed is as relatively low as 5 mm/s, the impact
load is equal to the detection load. On the contrary, as in the
condition (C) where the search speed is as high as 30 mm/s, the
detection load is 0.981 N (100 gram weight) while the actual impact
load is 1.961 N (200 gram weight) that is much larger than the
detection load.
[0064] Table 3 shows the results of qualities evaluated under the
conditions (A) to (D) of Table 1.
3 TABLE 3 Condition (A) (B) (C) (D) Al wiring leak 0/192 0/192 1/64
0/128 Nch MOS Tr 0/54 3/54 -- 2/54 property deterioration
[0065] The "Al wiring leak" of the measurement item of Table 3
shows results of whether or not the electric current leak occurs
due to the occurrence of cracks by bonding between the Al wiring 3a
and the terminal electrode 1 (the distance between them: 1 .mu.m).
The insulating layer is an SiO.sub.2 layer.
[0066] Another measurement item, "Nch MOS Tr property
deterioration" shows results of whether or not the deterioration of
the threshold value or electric current leak occurs due to the
bonding when the terminal electrode is placed on the Nch MOS
transistor. The insulating layer is an SiO.sub.2 layer. Moreover,
the distance between the terminal electrode and the Nch MOS
transistor is 4.97 .mu.m. Among the written numerical values in
Table 3, the numerical values of the right side show the number of
samples and those of the left side show the number of
defectives.
[0067] The results in Table 3 show that even if the static load is
small, if the impact load per bump is 0.735 N (75 gram weight) or
more, the property deterioration is easily caused by the stress
concentration (conditions (B) and (C)). Furthermore, Table 3 also
shows that in the range where the impact load is up to 0.441 N (45
gram weight), there is no problem (condition (A)).
[0068] Furthermore, the comparison between the condition (A) and
the condition (B) shows that the effect by the energy propagation
by the ultrasonic wave is not negligible. Therefore, it is
preferable that ultrasonic wave is used at the energy of 100 mW or
less and for about 20 msec.
[0069] Next, other experiment results are shown. They are obtained
when experiments were carried out while changing conditions. Table
4 shows the bonding conditions.
4TABLE 4 Output Time for Stage Detec- of ultra- applying Ball tem-
Search tion Static sonic ultrasonic size pera- Con- speed load load
wave wave (.mu.m ture dition (mm/s) (N) (N) (mW) (msec) .phi.)
(.degree. C.) (E) 5 0.196 0.294 60 20 52.about.55 260 (F) 15 0.490
0.392 85 20 52.about.55 260 (G) 20 0.588 0.392 85 20 52.about.55
260 (H) 50 0.981 0.981 85 20 52.about.55 260
[0070] Table 5 shows the results of qualities evaluated under the
conditions (H) of Table 4.
5 TABLE 5 Condition (E) (F) (G) (H) Al wiring leak 0/320 0/320
0/320 3/30
[0071] As shown in the results of Table 5, defectives occurred only
under the condition (H). Herein, the condition (G) is similar to
the condition (B). Consequently, it is shown that when the impact
load is reduced to some extent, the occurrence of defectives can be
inhibited.
[0072] Next, the experiment results are shown with respect to the
various of devices. Table 6 shows the results when the bonding was
performed in a case where the terminal electrode is formed on the
Nch MOS transistor.
6TABLE 6 [The terminal electrode is formed on an Nch MOS
transistor.] Search Stage Output of Change of speed temperature
Static load ultrasonic threshold (mm/s) (.degree. C.) (N/bump) wave
(mW) voltage 1 5 330 0.049.about.0.981 40 1.0% or less 2 10 330
0.196.about.0.392 40 1.2% or less 3 20 330 0.196.about.0.392 40
1.0% or less 4 20 200 0.196.about.0.392 40 1.2% or less 5 20 150
0.196.about.0.981 40.about.100 0.6% or less
[0073] Table 7 shows the results when the bonding was performed in
a case where the terminal electrode is provided on a Pch MOS
transistor.
7TABLE 7 [The terminal electrode is formed on the Pch MOS
transistor.] Search Stage Output of Change of speed temperature
Static load ultrasonic threshold (mm/s) (.degree. C.) (N/bump) wave
(mW) voltage 6 5 330 0.049.about.0.588 40 0.3% or less
[0074] Table 8 shows the results when the bonding was performed in
a case where the terminal electrode is provided on a SRAM
transistor.
8TABLE 8 [The terminal electrode is provided on a SRAM transistor.]
Search Stage Output of speed temperature Static load ultrasonic
(mm/s) (.degree. C.) (N/bump) wave (mW) Bit error 7 5 330
0.049.about.0.588 40 0/228
[0075] Table 9 shows the results when the bonding was performed in
a case where the terminal electrode is provided on the Al
wiring.
9TABLE 9 [The terminal electrode is provided on Al wiring.] Search
Stage Output of Electric speed temperature Static load ultrasonic
current (mm/s) (.degree. C.) (N/bump) wave (mW) leak 8 5 330
0.049.about.0.392 40 Each 0/82 9 10 330 0.196.about.0.392 40 Each
0/16 10 20 330 0.196.about.0.392 40 Each 0/16 11 20 200
0.196.about.0.392 40 Each 0/16 12 20 150 0.196.about.0.981
40.about.100 Each 0/16
[0076] When the terminal electrode is formed on the element, the
distance between the terminal electrode and the element is 4.97
.mu.m. When the terminal electrode is formed on the Al wiring, the
distance between the terminal electrode and the Al wiring is 1
.mu.m.
[0077] The conditions common to the experiments shown in Tables 6
to 9 include: the detection load per bump of 0.245 N (25 gram
weight); the time of applying ultrasonic wave of 15 msec; and the
diameter of the Au ball of about 69 .mu.m. In all cases, an
ultrasonic wave is applied at the same time the static load is
applied. Moreover, there is no problem as long as the ultrasonic
wave is applied at least after the static load is applied.
[0078] As is apparent from the results of Tables 6 to 9, all
samples have no property deterioration or no electric current leak,
showing the excellent results. More specifically, if the static
load is inhibited to some extent, there arises no problems even if
the static load per bump that is applied after the impact load is
applied is 0.981 N (100 gram weight) and the ultrasonic wave is 100
mW.
[0079] Next, the shape of the bump and pressure applied to the
terminal electrode were measured while changing the static load.
The measurement results are described as follows. The measurement
conditions are shown in Table 10.
10TABLE 10 Output Stage Detec- of ultra- Time of Ball tem- Search
tion Static sonic applying size pera- Con- speed load load wave
wave (.mu.m ture dition (mm/s) (N) (N) (mW) (msec) .phi.) (.degree.
C.) 5 0.245 0.245.about. 40 20 about 330 1.373 69
[0080] The lower part of the bump, which was obtained after the Au
ball was deformed and the static load was applied thereto, is
referred to as a seating. FIG. 2A is a graph showing a relationship
between the static load f, the diameter R of the seating and the
height H of the seating. FIG. 2B is a graph showing a relationship
between the static load f and the pressure P applied to the
terminal electrode. The pressure applied to the terminal electrode
can be calculated from the area of the seating and the static load.
More specifically, as shown in FIG. 2C, the average diameter R of
the seating is expressed by the following equation (1) and the
average radius r of the seating is expressed by the following
equation (2). In the equations (1) and (2), .phi.x and .phi.y
denote diameters of the seating, respectively.
R=(.phi.x+.phi.y)/2 equation (1)
r=R/2 equation (2)
[0081] When the pressure P is expressed by the following equation
(3):
P=f/.pi.r.sup.2 equation (3)
[0082] wherein f denotes the static load and P denotes the pressure
applied to the terminal electrode.
[0083] It is preferable that the pressure applied to the terminal
electrode after the static load is applied is up to 140 MPa
corresponding to the pressure when the static load per bump is
0.981 N (100 gram weight).
[0084] As mentioned in the experiment results, it is preferable
that the device is used under the conditions of: the impact load
per bump of 0.441 N (45 gram weight) or less, the static load of
0.981 N (100 gram weight) or less; the ultrasonic wave of 100 mW or
less; and the pressure applied to the terminal electrode after the
static load is applied of up to 140 MPa corresponding to the
pressure when the static load per bump is 0.981 N (100 gram
weight). Furthermore, there is no problem as long as the impact
load is secured to be 0.245 N (25 gram weight). As mentioned above,
it is preferable that the impact load is 0.981 N or less.
Therefore, it is preferable that the difference between the impact
load per metal ball and the static load is 0.736 N (75 gram
weight).
[0085] Second Embodiment
[0086] FIGS. 3A and B are schematic views showing a bonding process
when wire bonding is performed on a terminal electrode of a
semiconductor device. In a semiconductor device 25 shown in FIG.
3A, three insulating layers 24a, 24b and 24c are formed on a
substrate provided with an element 23b. In the insulating layers,
wiring 23a is formed. On the insulating layer 24a, a terminal
electrode 21 is formed. More specifically, in the semiconductor
device 25 shown in FIG. 3, the terminal electrode 21 is formed on
the element 23b and the wiring 23a provided inside the
semiconductor device 25. The terminal electrode 21 is formed
primarily by, for example, aluminum. Furthermore, the element 23b
is an active element such as a transistor, etc. or a passive
element such as resistance, etc.
[0087] As shown in FIG. 3A, at the tip of a metal wire 22, a metal
ball 22a is formed by electric discharge. The metal ball 22a is
formed primarily of, for example, Au. However, it may be formed of
at least one metallic material selected from the group consisting
of Au, Al, Pd, Pb, Sn, Cu, In, Bi, Ti and Ni.
[0088] The metal ball 22a is pressed against the terminal electrode
21 by a pressure tool 6. With this embodiment, the impact load is
applied to the terminal electrode 21 when the metal ball 22a is
pressed against, and sequentially the static electrode is applied.
FIG. 3C shows one example of the bonding process. In the example of
this figure, the load per metal ball is 0.245 N (25 gram weight)
for the impact load as shown by the remark 25 and 0.392 N (40 gram
weight) for the static load as shown by the remark 26.
[0089] Also in this embodiment, for the same reason as in the first
embodiment, the impact load is set to be smaller than the static
load, whereby the element 23b or the wiring 23a placed below the
terminal electrode 21 can be prevented from being damaged.
Furthermore, it is generally preferable that an ultrasonic wave is
used together in order to secure the stability. Herein, the damage
denotes the deterioration of property, the electric current leak
due to the occurrence of cracks, or the like.
[0090] Furthermore, as shown in FIG. 3B, the tip opposed to the
metal ball 22a of the metal wire 22 is bonded to an input/output
terminal electrode 28 of the circuit board 27.
[0091] Similar to the first embodiment, also in the second
embodiment, it is preferable that the device is used under the
conditions of: the impact load per bump of 0.441 N (45 gram weight)
or less; the static load of 0.981 N (100 gram weight) or less;
ultrasonic wave of 100 mW or less; and the pressure applied to the
terminal electrode after the static load is applied of up to 140
MPa corresponding to the pressure when the static load per bump is
0.981 N (100 gram weight). Furthermore, there is no problem as long
as the impact load is secured to be 0.245 N (25 gram weight). As
mentioned above, it is preferable that the impact load is 0.981 N
or less. Therefore, it is preferable that the difference between
the impact load per metal ball and the static load is 0.736 N (75
gram weight).
[0092] Third Embodiment
[0093] The third embodiment of the present invention relates to a
method for inspecting a semiconductor device. FIG. 4 is a schematic
view showing a method for inspecting a semiconductor device of this
embodiment. FIG. 4A is a cross-sectional view of a semiconductor
device, and FIG. 4B is a view of a semiconductor device seen from
above.
[0094] In a semiconductor device 37 shown in FIG. 4A, three
insulating layers 34a, 34b and 34c are formed on a substrate
provided with an element 33b. In the insulating layers, wiring 33a
is formed. On the insulating layer 34a, a terminal electrode 31 is
formed. More specifically, in the semiconductor device 37, the
terminal electrode 31 is formed on the element 33b and the wiring
33a provided inside the semiconductor device 37.
[0095] FIG. 4A shows a state before the wire bonding is carried out
on the terminal electrode 31 or before the bump is formed by the
wire bonding method.
[0096] FIG. 4B shows an example of the terminal electrode 31 having
a square shape that is a general shape of the terminal electrode.
However, the shape of the terminal electrode is not limited to a
square shape alone. The terminal electrode 31 is formed primarily
of aluminum. The hatched part of the terminal electrode 31 shows
the region in which the metal ball is bonded.
[0097] Since a bonding region 35 of the metal ball is thought to be
similar to a circular shape, the corner region 36 of the terminal
electrode 31 is a region that is not related to the bonding. If the
bonding region 35 of the metal ball is inspected by bringing a
probe needle 32 into contact with the bonding region 35 in advance,
the loss of aluminum occurs because of the contact. When the
bonding is performed later, an intermetallic compound of the metal
ball and the terminal electrode (primarily aluminum) is generated,
thus inhibiting the stability of the bonding.
[0098] In this embodiment, the region in which the probe needle 32
for inspection is in contact with a corner region 36 of the
terminal electrode 31, which is not related to the bonding region
35 of the metal ball. Therefore, in the bonding region 35, there is
no loss of aluminum caused by the contact of the prove needle 32,
thus enabling the stable bonding connection.
[0099] Fourth Embodiment
[0100] The fourth embodiment of the present invention relates to a
semiconductor device suitable for the inspection when the wire
bonding is carried out or the bump is formed by the wire bonding
method. FIG. 5A is a cross-sectional view of a semiconductor device
according to this embodiment; and FIG. 5B is a view of a
semiconductor seen from above.
[0101] In a semiconductor device 47 shown in FIG. 5A, three
insulating layers 44a, 44b and 44c are formed on a substrate
provided with an element 43b. In the insulating layers, the wiring
43a is formed. On the insulating layer 44a, a terminal electrode 41
is formed. More specifically, in the semiconductor device 47, the
terminal electrode 41 is formed on the element 43b and the wiring
43a provided inside the semiconductor device 47.
[0102] FIG. 5A shows a state before the wire bonding is carried out
on the terminal electrode 41 or before the bump is formed by the
wire bonding method. FIG. 5B shows an example of the terminal
electrode 41 having a rectangular shape. The terminal electrode 41
is formed primarily of aluminum. The bonding region 45 shown by a
hatched part of the terminal electrode 41 shows the region in which
the metal ball is bonded. A bonding region of the metal ball is
thought to be similar to a circular shape.
[0103] In this embodiment, an inspection region 46 is provided on
the terminal electrode 41. When the probe needle 42 is brought into
contact with the bonding region 45 of the metal ball in advance,
the loss of aluminum occurs due to the contact. When the bonding is
performed later, an intermetallic compound is generated between the
metal ball and the terminal electrode (primarily aluminum), thus
inhibiting the stability of the bonding.
[0104] In this embodiment, the contact region of the probe needle
42 is provided separately from the bonding region 45 of the metal
ball. Therefore, the stable bonding connection is possible.
[0105] Fifth Embodiment
[0106] FIG. 6A is a schematic view showing a mounting process for a
semiconductor according to a fifth embodiment of the present
invention. In a semiconductor device 59 shown in FIG. 6A, three
insulating layers 54a, 54b and 54c are formed on a substrate
provided with an element 53b. In the insulating layers, wiring 53a
is formed. On the insulating layer 54a, a terminal electrode 51 is
formed. More specifically, in the semiconductor device 59, the
terminal electrode 51 is formed on the element 53b and the wiring
53a provided inside the semiconductor device 59. The element 53b is
an active element such as a transistor, etc. or a passive element
such as resistance, etc.
[0107] On an input/output terminal electrode 58 of a circuit board
57 shown in FIG. 6A, a bump 52 having a needle-shaped tip is
formed. The bump 52 is bonded to the terminal electrode 51 of the
semiconductor electrode 59. The bump 52 can be formed in a shape of
a needle having a diameter of a tip flat portion of 40 .mu.m or
less on the input/output terminal electrode 58 of the circuit board
57 by, for example, the wire bonding method.
[0108] It is preferable that when the bump 52 is formed by the wire
bonding method, it is formed of at least one metallic material
selected from the group consisting of Au, Al, Pd, Pb, Sn, Cu, In,
Bi, Ti and Ni. It is further preferable that when the bump 52 is
formed by plating, it is formed of at least one metallic material
selected from the group consisting of Au, Al, Pd, Cu, Ni, Ti, Cr
and Ag. It is still further preferable that when the bump 52 is
formed by a printing method, it is formed of at least one metallic
material selected from the group consisting of Ag, Pd, Pt, Cu, Ni,
Pb, Sn and Bi.
[0109] The circuit board 57 moves in the direction shown by the
arrow in FIG. 6A, and then the bump 52 is pressed against the
terminal electrode 51. Consequently, the impact load is applied to
the terminal electrode 51 when the bump 52 is pressed. After the
impact load is applied, sequentially the static load is applied.
FIG. 6B shows one example of the bonding process. In the example of
this figure, the load per metal ball is 0.245 N (25 gram weight)
for the impact load as shown by the remark 55 and 0.392 N (40 gram
weight) for the static load as shown by the remark 56.
[0110] Main constituents factors related to the impact load include
the speed when the metal ball is brought into contact with the
terminal electrode, the detection load that is a reference with
which the device detects that the metal ball is brought into
contact with the terminal electrode, the size of the metal ball,
and the like. In order to reduce the impact load, the speed is
preferably small. Furthermore, the detection load is preferably
small because the load is applied until the load reaches to a
target load.
[0111] Furthermore, as to the flat portion at the tip of the bump,
the larger the flat portion is, the smaller the stress is.
Therefore, the flat portion at the tip is preferably large. More
specifically, it is preferable that the diameter of the flat
portion is as large as possible in the range of 40 .mu.m or
less.
[0112] After the impact load is applied, the static load is applied
so as to stabilize the bonding property of the bump. In general, it
is preferable that the ultrasonic wave is used together in order to
secure the stability.
[0113] This mounting process can be employed in any mounting
methods that require pressure. For example, it may be employed in
the case where the ultrasonic wave is used together to perform a
pressure welding the bump. Furthermore, it may be employed in the
mounting via a connecting layer such as conductive paste, an
anisotropic conductive film, etc.
[0114] Herein, the state right after the bump 52 is brought into
contact with the terminal electrode 51 is described. Until the bump
52 is sufficiently crushed, the contact area between the bump 52
and the terminal electrode 51 is small. Therefore, stress tends to
be concentrated on the contact portion, and thus a high pressure is
applied thereto. Therefore, by reducing the impact load, the
element 53b or the wiring 53a placed below the terminal electrode
51 can be prevented from being damaged. The load for bonding can be
secured by making the static load applied after the impact load is
applied larger than the impact load. When the impact load is
applied, the bump 52 is sufficiently crushed, even if the static
load is increased, the pressure applied to the terminal electrode
51 can be reduced such that damage to the element 53b or the wiring
53a placed below the terminal electrode 51 can be prevented.
Herein, the damage denotes the deterioration of the property, the
electric current leak due to the occurrence of cracks, or the
like.
[0115] Furthermore, in the mounting process according to this
embodiment, the experiment results described in the first
embodiment can be employed. Therefore, it is preferable that the
impact load per bump is 0.441 N (45 gram weight) or less, the
static load is 0.981 N (100 gram weight) or less; the ultrasonic
wave is 100 mW or less; and the pressure applied to the terminal
electrode after the static load is applied is up to 140 MPa
corresponding to the pressure when the static load per bump is
0.981 N (100 gram weight). Furthermore, there is no problem as long
as the impact load is secured to be 0.245 N (25 gram weight). As
mentioned above, it is preferable that the impact load is 0.981 N
or less. Therefore, it is preferable that the difference between
the impact load per metal ball and the static load is 0.736 N (75
gram weight).
[0116] Sixth Embodiment
[0117] FIG. 7A is a schematic view showing a mounting process for a
semiconductor device according to a sixth embodiment of the present
invention. In a semiconductor device 69 shown in FIG. 7A, three
insulating layers 64a, 64b and 64c are formed on a substrate
provided with an element 63b. In the insulating layers, wiring 63a
is formed. On the insulating layer 64a, a terminal electrode 61 is
formed. More specifically, in the semiconductor device 69, the
terminal electrode 61 is formed on the element 63b and the wiring
63a provided inside the semiconductor device 69. The element 63b is
an active element such as a transistor, etc. or a passive element
such as resistance, etc.
[0118] The sixth embodiment is different from the fifth embodiment
in that the bump 62 has a spherical-shaped tip. Such a bump 62
having a spherical-shaped tip can be formed by, for example,
plating. The material of the bump 62 is the same as that in the
fifth embodiment.
[0119] The method for mounting the semiconductor device 69 to the
circuit board 67 in this embodiment is the same as that of the
fifth embodiment. In other words, also in this embodiment, by
making the impact load smaller than the static load, damage to the
element 63b or the wiring 63a placed below the terminal electrode
61 can be prevented.
[0120] FIG. 7B shows one example of the bonding process. In the
example of this figure, the load per bump is 0.245 N (25 gram
weight) for the impact load as shown by the remark 65 and 0.392 N
(40 gram weight) for the static load as shown by the remark 66.
[0121] Furthermore, also in the mounting process according to this
embodiment, the experiment results described in the first
embodiment can similarly be employed. Therefore, as mentioned in
the experiment results, it is preferable that the device is used
under the conditions of: the impact load per bump of 0.441 N (45
gram weight) or less, the static load of 0.981 N (100 gram weight)
or less; ultrasonic wave of 100 mW or less; and the pressure
applied to the terminal electrode after the static load is applied
of up to 140 MPa corresponding to the pressure when the static load
per bump is 0.981 N (100 gram weight). Furthermore, there is no
problem as long as the impact load is secured to be 0.245 N (25
gram weight). As mentioned above, it is preferable that the impact
load is 0.981 N or less. Therefore, it is preferable that the
difference between the impact load per metal ball and the static
load is 0.736 N (75 gram weight).
[0122] The invention may be embodied in other specific forms
without departing from the spirit or essential characteristics
thereof. The embodiments disclosed in this application are to be
considered in all respects as illustrative and not restrictive, the
scope of the invention is indicated by the appended claims rather
than by the foregoing description, and all changes which come
within the meaning and range of equivalency of the claims are
intended to be embraced therein.
* * * * *