Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
1999-10-27
2001-09-04
Niebling, John F. (Department: 2812)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
Reexamination Certificate
active
06284640
ABSTRACT:
FIELD OF THE INVENTION
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
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.
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.
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).
FIG. 8
is a schematic cross-sectional view of a bonding structure of a semiconductor device of the above-mentioned mounting technique. An SiO
2
film
116
is formed on a substrate
118
and an Al terminal electrode
117
is formed on the SiO
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
.
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.
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.
Moreover, the bump is not limited to the solder bump alone. An Au plating bump may be formed after the barrier metal is formed.
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.
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.
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
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.
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.
It is preferable in the above-mentioned manufacturing method of a semiconductor device that the metal ball is used for forming a bump.
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.
Furthermore, it is preferable that the terminal electrode is formed on an element or wiring provided inside the semiconductor device.
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.
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.
Furthermore, it is preferable that the difference between the impact load per metal ball and the static load is 0.736 N or less.
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.
Next, according to the mounting method for a semiconductor device of he 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.
It is preferable in the above-mentioned mounting method that the tip of the bump has a needle shape.
Furthermore, it is preferable that the needle-shaped portion comprises a flat portion having a diameter of 40 &mgr;m or less.
Furthermore, it is preferable that the tip of the bump has a spherical shape.
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.
Furthermore, it is preferable th
Bessho Yoshihiro
Eda Kazuo
Ono Masahiro
Shiraishi Tsukasa
Gurley Lynne A.
Matsushita Electric - Industrial Co., Ltd.
Merchant & Gould P,C,
Niebling John F.
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