Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – For plural devices
Reexamination Certificate
2001-01-30
2002-10-29
Nelms, David (Department: 2818)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
For plural devices
C257S724000, C257S777000, C257S778000
Reexamination Certificate
active
06472746
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to semiconductor devices and, more particularly, to a semiconductor device having external connection terminals on a side surface thereof.
2. Description of the Related Art
In recent years, miniaturization of electronic equipment has progressed, and semiconductor devices used in the electronic equipment has been also miniaturized. As a structure of such a miniaturized semiconductor device, a chip size package (CSP) structure has become popular. In a semiconductor device having the CSP structure, a semiconductor element is fixed on an interposer, and electrodes of the semiconductor element are connected to terminals of the interposer by wire bonding. Protruding electrodes such as solder balls are provided to a lower surface of the interposer as external connection terminals. Accordingly, the package size of the semiconductor device having the CSP structure is much smaller than a conventional lead frame type semiconductor device.
Additionally, a CSP structure, which does not use an interposer, has been suggested. In such a CSP structure, a semiconductor element is not mounted on an interposer, and all wirings and external connection terminals are formed on the semiconductor element. Since such a CSP structure has been achieved, a two-dimensional size of semiconductor devices having the CSP structure has reached their critical limit.
As mentioned above, the two-dimensional miniaturization of the semiconductor devices has reached their limit since they have reached their real chip size. Accordingly, in order to mount the semiconductor elements with further increased density, miniaturization of their mounting area is not needed but miniaturization of their volume is needed. Accordingly, it is desired to develop a stacking structure having a simple structure in which a plurality of semiconductor elements or a plurality of semiconductor devices can be stacked in a three-dimensional state.
When a plurality of semiconductor elements, each of which has a surface on which a plurality of electrodes are formed, are stacked, the surface of each of the semiconductor elements must be covered by an insulating layer so as to stack another semiconductor element thereon. Accordingly, it is an important issue on how to draw out and make a connection with the electrodes of each semiconductor elements.
SUMMARY OF THE INVENTION
It is a general object of the present invention to provide an improved and useful semiconductor device in which the above-mentioned problems are eliminated.
A more specific object of the present invention is to provide a semiconductor element stacking structure in which each electrode of each of stacked semiconductor elements can be drawn out with a simple structure.
In order to achieve the above-mentioned objects, there is provided according to one aspect of the present invention a semiconductor element stacking structure comprising:
a plurality of semiconductor elements arranged in a stacked state, each of the semiconductor elements having a circuit forming surface on which electrodes are formed;
a resin layer formed on the circuit forming surface of each of the semiconductor elements, the resin layer having an outer configuration the same as that of each of the semiconductor elements; and
a plurality of bonding wires embedded in the resin layer, one end of each of the bonding wires being connected to respective one of the electrodes and the other end of each of the bonding wires being exposed on a side surface of the resin layer.
According to the above-mentioned invention, electrical connection with each of the semiconductor elements can be achieved by using the bonding wires exposed on the side surface of the resin layer as external connection electrodes. That is, each of the bonding wires having the exposed end is connected to a corresponding one of the electrodes of each of the semiconductor elements. Accordingly, the external connection electrode can be formed on the exposed end of each of the bonding wires. Thereby, the electrical connection with each of the semiconductor elements can be achieved by the external connection terminal formed on the side surface of the semiconductor element stacking structure even if the semiconductor elements are stacked.
In the semiconductor element stacking structure according to the above-mentioned invention, the exposed ends of the bonding wires may be aligned along a line separated from the circuit forming surface of corresponding one of the semiconductor elements by a predetermined distance.
Accordingly, when the external connection terminals are formed on the exposed ends of the bonding wires, the external connection terminals and the circuit forming surface are prevented from short-circuiting since each of the exposed ends of the bonding wires is separated by a predetermined distance from the circuit forming surface of the corresponding semiconductor element.
The exposed ends of the bonding wires may be aligned along a plurality of lines separated from the circuit forming surface of corresponding one of the semiconductor elements by different distances, respectively. Accordingly, even if the pitch of the electrodes of the semiconductor element is small and a distance between the adjacent bonding wires in a vertical direction is small, the distance of the adjacent bonding wires can be increased by a distance in a vertical direction. More specifically, the exposed ends of the bonding wires may be aligned along a first line and a second line, the first line being separated from the circuit forming surface of the corresponding one of the semiconductor elements by a first predetermined distance, the second line being separated from the circuit forming surface of the corresponding one of the semiconductor elements by a second predetermined distance, the exposed ends of the bonding wires being alternately arranged so that one of the exposed ends is positioned on the first line and another exposed ends adjacent to the one of the exposed ends is positioned the second line.
Additionally, a protruding electrode may be provided on each of the exposed ends of the bonding wires. For example, the protruding electrodes can be easily formed by stud bumps. Additionally, the corresponding electrodes of the semiconductor elements can be connected by connecting the protruding electrodes aligned in a stacking direction by bonding wires.
Additionally, protruding electrodes may be provided on a surface of a resin layer covering the circuit forming surface of a lowermost semiconductor element from among the stacked semiconductor elements, the protruding electrodes being connected to electrodes of the semiconductor elements. Accordingly, in a case in which the stacked semiconductor elements are the same kind and the electrode arrangement is the same, the protruding electrodes formed on the side surface of the semiconductor element stacking structure can be used as electrode for connecting the corresponding electrodes of the semiconductor elements, and the protruding electrodes provided on the surface of the resin layer covering the circuit forming surface of the lowermost semiconductor elements can be used as external connection terminals.
Additionally, a wiring board may be mounted on a side surface on which the protruding electrodes provided to the exposed ends are formed so that the protruding electrodes are connected to each other by wirings of the wiring board. Accordingly, the corresponding electrodes of the semiconductor elements can be connected to each other by easily connecting the protruding electrodes by the wiring board.
Additionally, another semiconductor element may be mounted on a side surface on which the protruding electrodes provided to the exposed ends are formed. That is, another semiconductor element can be easily mounted by using the protruding electrodes provided on the exposed ends of the bonding wires. Thus, the number of semiconductor elements can be increased. Additionally, a different kind of semiconductor element can be added to the
Takashima Akira
Taniguchi Fumihiko
Armstrong Westerman & Hattori, LLP
Fujitsu Limited
Nelms David
Nguyen Dao H.
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