Active solid-state devices (e.g. – transistors – solid-state diode – Combined with electrical contact or lead – Chip mounted on chip
Reexamination Certificate
2002-10-17
2004-08-24
Thai, Luan (Department: 2827)
Active solid-state devices (e.g., transistors, solid-state diode
Combined with electrical contact or lead
Chip mounted on chip
C257S686000, C257S723000
Reexamination Certificate
active
06781241
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 a three-dimensional structure in which a plurality of semiconductor devices and semiconductor elements are stacked, and a manufacturing method of such a semiconductor device.
With the development of electric equipments in recent years, a demand for miniaturization in dimensions and thickness, multifunction, high-performance and high-density in the semiconductor devices has been increasing. In order to cope with such a demand, the structure of the semiconductor devices has been shifting to a three-dimensional structure in which a plurality of semiconductor devices or a plurality of semiconductor elements are stacked.
2. Description of the Related Art
Japanese Laid-Open Patent Application No. 2001-223297 discloses an example of a semiconductor device, which has a three-dimensional structure formed by stacking a plurality of semiconductor devices.
FIG. 1
is a cross-sectional view of the semiconductor device disclosed in the above-mentioned patent document.
In
FIG. 1
, semiconductor chips
3
are mounted on both sides of each of interposers
1
, and are encapsulated by a seal resin
2
, respectively. The two interposers
1
are stacked with the seal resin
2
, which encapsulates the semiconductor chip
3
, interposed therebetween. The interposers
1
are connected to each other by bonding solder balls
7
to ball pads
5
which are exposed in through holes
6
formed in a solder resist
4
. That is, the upper and lower interposers
1
are electrically connected to each other by the solder balls
7
, and are also connect mechanically to each other.
In the semiconductor device shown in
FIG. 1
, since each semiconductor chip mounted on the stacked interposers is encapsulated by the seal resin, it is necessary to provide a distance between two interposers, which distance is greater than the thickness of the seal resin layer interposed between two interposers. Therefore, if the distance between the interposers can be reduced, the overall height of the semiconductor device can also be reduced.
Additionally, since the interposers are connected and fixed to each other by the solder balls provided in the peripheral portion of the interposers, if a warp occurs in the interposers in a stacking process of an assembling process of the semiconductor package, a defect may occur in the connecting part between the interposers. Moreover, when mounting the complete semiconductor package onto a substrate, a defect may occur in the connecting part between the interposers due to a thermal deformation of the interposers and remelting of the solder balls.
Furthermore, since the complete semiconductor package is mechanically connected by a small area with only the solder balls, a stress tends to be concentrated into the connecting part between the interposers, which may deteriorate mechanical reliability of the package.
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 device having a three-dimensional structure in which a plurality of semiconductor devices or a plurality of semiconductor elements are stacked, the semiconductor device having a reduced overall height and an improved reliability in the mechanical strength of the stacked structure.
Another object of the present invention is to provide a semiconductor device having a three-dimensional structure in which a plurality of semiconductor devices or a plurality of semiconductor elements are stacked, the semiconductor device having an improved heat release characteristic.
In order to achieve the above-mentioned objects, there is provided according to one aspect of the present invention a semiconductor device comprising: a first semiconductor element having a circuit forming surface and a back surface opposite to the circuit forming surface; a first interposer having a surface on which first electrode pads are formed and the first semiconductor element is mounted with the circuit forming surface facing the first interposer; a second semiconductor element having a circuit forming surface and a back surface opposite to the circuit forming surface; a second interposer having a surface on which second electrode pads are formed and the second semiconductor element is mounted with the circuit forming surface facing the second interposer, the second electrode pads for connection with the first interposer; and external connection terminals provided on a surface of the second interposer opposite to the surface on which the second semiconductor element is mounted, wherein the first interposer and the second interposer are electrically connected to each other by conductive members between the first and second electrode pads, and the back surface of the first semiconductor element and the back surface of the second semiconductor element are fixed to each other by an adhesive.
According to the above-mentioned invention, there is no need to encapsulate the first and second semiconductor elements provided between the first and second interposers. Thus, a distance between the first and second interposers can be reduced, which results in a reduction in an overall thickness of the semiconductor device. Additionally, since the first and second semiconductor elements are bonded to each other by the adhesive, a mechanical strength of the connection between the interposers is improved, which prevents warp of the interposers. Further, since the first and second semiconductor elements are bonded to each other by the adhesive, a heat generated in the first semiconductor element can be efficiently released outside through the second semiconductor element and the second interposer.
The semiconductor device according to the present invention may further comprise at least one third semiconductor element which is mounted on a surface of the first interposer opposite to the surface on which the first semiconductor element is mounted. Accordingly, the number of semiconductor elements stacked in the semiconductor device can be increased, which improves a packaging density. Additionally, a plurality of the third semiconductor elements may be mounted and encapsulated on the surface of the first interposer in a stacked and fixed state. Accordingly, semiconductor elements of different kinds or sizes can be efficiently arranged within the semiconductor device. Further, a metal layer for heat release may be provided on a surface of the first interposer opposite to the surface on which the first semiconductor element is mounted. Accordingly, the metal layer serves as a heat spreader, which can efficiently release a heat of the semiconductor elements to outside of the semiconductor device.
Additionally, there is provided according to another aspect of the present invention a semiconductor device comprising: a first semiconductor element having a circuit forming surface and a back surface opposite to the circuit forming surface; a first interposer having a surface on which first electrode pads are formed and the first semiconductor element is mounted with the circuit forming surface facing the first interposer; a second semiconductor element having a circuit forming surface and a back surface opposite to the circuit forming surface; a second interposer having a surface on which second electrode pads are formed and the second semiconductor element is mounted with the circuit forming surface facing the second interposer, the second electrode pads for connection with the first interposer; and external connection terminals provided on a surface of the second interposer opposite to the surface on which the second semiconductor element is mounted, wherein the first interposer and the second interposer are electrically connected to each other by conductive members between the first and second electrode pads, and the
Nishimura Takao
Onodera Hiroshi
Takashima Akira
Uno Tadashi
Thai Luan
Westerman Hattori Daniels & Adrian LLP
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