Active solid-state devices (e.g. – transistors – solid-state diode – Combined with electrical contact or lead – Bump leads
Reexamination Certificate
2000-08-24
2003-06-24
Potter, Roy (Department: 2822)
Active solid-state devices (e.g., transistors, solid-state diode
Combined with electrical contact or lead
Bump leads
C257S778000
Reexamination Certificate
active
06583506
ABSTRACT:
TECHNICAL FIELD
This invention relates to a semiconductor device comprising bumps that are suitable for mounting on a circuit board with an anisotropic conductive film therebetween.
BACKGROUND TECHNOLOGY
Recently, a semiconductor device for surface mounting comprising bumps (projecting terminals) capable of electrically and mechanically connecting to a circuit board has been often used.
The structure of the bump in such a conventional semiconductor device and a fabricating method thereof will be briefly described with reference to
FIG. 14A
to FIG.
14
D. Incidentally, these drawings are sectional views, but oblique lines showing sections are omitted.
FIG. 14D
shows a section of the bump and thereabout of a complete semiconductor device.
On the surface of a silicon wafer
213
which is cut into semiconductor chips, a selective oxide (LOCOS) film
204
which is a layer necessary for fabricating a semiconductor device is provided, and an aluminum layer
702
is provided on the selective oxide (LOCOS) film
204
. This aluminum layer
702
is a layer necessary to input and output a power supply or a signal to/from interconnections in the semiconductor device and an integrated circuit from/to the outside.
On top of that, a passivation film
703
which is an insulation protection film covering the entire face of the silicon wafer
213
is provided, and an opening portion
703
a
is formed in the passivation film
703
on the aluminum layer
702
. A gold bump
701
which is mushroom shaped is provided from the aluminum layer
702
within the opening portion
703
a
extending onto the passivation film
703
around the opening portion
703
a
with a noble metal film
705
therebetween.
In this drawing, only one bump is shown, but many bumps are provided in a real semiconductor chip.
FIG. 14A
to
FIG. 14C
are views showing the mid-steps of the fabrication of this semiconductor device.
As shown in
FIG. 14A
, the selective oxide film
204
is formed on the silicon wafer
213
, and the aluminum layer
702
which is connected to the internal integrated circuit is formed at a necessary position on the selective oxide film
204
. The passivation film
703
which covers the entire face of the silicon wafer
213
including the aluminum layer
702
is formed, and the opening portion
703
a
for establishing connection with the outside is formed on the aluminum layer
702
.
Then, as shown in
FIG. 14B
, the noble metal film
705
is formed on the entire faces of the passivation film
703
and the aluminum layer
702
, and further a photosensitive resist
710
is selectively (except for a bump formation region) formed on the noble metal film
705
.
The noble metal film
705
is a noble metal layer such as an alloy of titanium and tungsten, or the like and has a function as an electrode for producing the gold bump
701
, which is formed on the aluminum layer
702
in a subsequent step, by electro-plating, and another function of improving the connection between the aluminum layer
702
and the gold bump
701
.
This noble metal film
705
is formed by being laminated on the entire surface in a vacuum apparatus.
Next, as shown in
FIG. 14C
, a gold layer is produced in a portion in which the resist
710
is not formed by the electro-plating step to form the gold bump
701
which is the mushroom shaped bump electrode.
Then, after the resist
710
is removed, the noble metal layer
705
is removed with the gold bump
701
as a mask with only a portion thereof under the gold bump
701
left.
FIG. 14D
is a sectional view of this state.
Through such process steps, the bump electrodes of the gold bumps
701
are formed on the silicon wafer
213
, and the silicon wafer
213
is cut into discrete semiconductor chips to complete semiconductor devices.
However, in the semiconductor device comprising such conventional bumps, since a plating process which is hard to manage is employed for making up the bumps, the bumps are prone to be nonuniform in height, and additionally, the use of costly gold for the material of the bumps results in a high cost of production.
The present invention is made to solve such problems and its object is to make it possible to easily fabricate bump electrodes of a semiconductor device at low cost and to make the height of the bumps uniform.
Moreover, another object is to make it possible that the height of a most projecting end face of the bump is sufficiently higher than those of projecting faces of any other parts of the semiconductor device in order that the bump can be surely electrically connected to an interconnection on a circuit board when such a semiconductor device is mounted on the circuit board with an anisotropic conductive film therebetween, and that an effective area of the end face is made large to catch a plurality of conductive particles.
DISCLOSURE OF THE INVENTION
To achieve the above object of the present invention, a semiconductor device comprising a polysilicon layer used for an interconnection and a gate of a transistor, an insulation layer covering thie polysilicon layer, an interconnection conductor layer formed on the insulation layer, and a bump for inputting and outputting a power supply or a signal to an integrated circuit, on the surface of a semiconductor chip in which the integrated circuit is formed, is structured as follows.
A polysilicon film and an insulation film made of the same materials as those of said polysilicon layer and said insulation layer are provided at a region at which the bump is formed, on the surface of the semiconductor chip; a first conductor which covers the insulation film and is electrically connected to the interconnection conductor layer is made of the same material as that of the interconnection conductor layer by sputtering; a protection insulation film which covers the surfaces of the first conductor, the interconnection conductor layer, and the semiconductor chip and in which an opening portion is provided on the first conductor is formed; a second conductor which conducts to the first conductor through the opening portion is formed on the protection insulation film by sputtering.
Further, the bump is composed of the polysilicon film, the insulation film, the first conductor, and the second conductor, and is formed so that a height of a most projecting end face thereof from the surface of the semiconductor chip is higher than those of projecting faces of any other parts.
Also in this case, each of the aforesaid first conductor and the second conductor can be made of aluminum.
Moreover, it is preferable that the most projecting end face of the bump is covered with a conductive film for preventing surface oxidation, that is, a conductive oxidation film or a noble metal film.
In the case where the aforesaid bump is composed of the aforesaid first conductor and the second conductor which conducts to the first conductor through the opening portion formed in the protection insulation film covering the first conductor, the film thickness of the protection insulation film at the region under the second conductor is formed thicker than that of the other region, thereby increasing the bump's height.
Further, in the present invention, a semiconductor device comprising a bump, on the surface of a semiconductor chip in which an integrated circuit is formed, for inputting and outputting a power supply or a signal to the integrated circuit and mounted on a substrate with an anisotropic conductive film containing a large number of conductive particles therebetween is structured as follows.
On the surface of the semiconductor chip, a first conductor which is electrically connected to the integrated circuit; a protection insulation film which covers the surfaces of the first conductor and the semiconductor chip and in which a through hole is formed on the first conductor; and a second conductor which is formed on the protection insulation film by sputtering and conducts to the first conductor through the through hole, are provided, wherein the bump is composed of the first conductor and the second conductor, and is formed s
Kikuchi Masayoshi
Masuda Takashi
Morokawa Shigeru
Watanabe Makoto
Yano Takakazu
Armstrong Westerman & Hattori, LLP
Citizen Watch Co. Ltd.
Potter Roy
LandOfFree
Semiconductor device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Semiconductor device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Semiconductor device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3162650