Active solid-state devices (e.g. – transistors – solid-state diode – Encapsulated
Reexamination Certificate
2000-07-25
2001-11-13
Clark, Sheila V. (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Encapsulated
C257S777000
Reexamination Certificate
active
06316840
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly to a semiconductor device which works as a semiconductor sensor.
2. Description of the Background Art
FIG. 27
is a cross section showing a structure of a semiconductor device
90
, as an example of the background-art semiconductor sensor, comprising moving electrodes such as an acceleration sensor, a pressure sensor and an angular velocity sensor. In general, the semiconductor sensor with the moving electrodes has a structure in which the moving electrode is contained in a hollow cavity. In
FIG. 27
, a moving part MV provided on a main surface of a sensor substrate SC is covered with a hollow cavity CV (hereinafter, referred to as a cap).
The sensor substrate SC has at least a semiconductor substrate (not shown), the moving part MV and a semiconductor element (not shown) for generating an electrical signal according to the displacement of the moving part MV, and the electrical signal generated by the semiconductor element is transmitted to a signal processing substrate AS for performing a predetermined signal processing through a wiring interconnection WR. The signal processing substrate AS has a structure of application specific IC (ASIC) to perform a function of calculating acceleration, pressure and the like on the basis of the electrical signal given from the sensor substrate SC.
The sensor substrate SC and the signal processing substrate As are mounted on a die pad DP of a lead frame and the signal processing substrate AS is electrically connected to an inner lead IL through the wiring interconnection WR. The sensor substrate SC and the signal processing substrate AS are sealed by a mold resin MR together with the die pad DP and the inner lead IL, whereby a resin-sealed package is achieved.
FIG. 28
is a perspective view showing a state before the semiconductor device
90
is sealed by the resin. As shown in
FIGS. 27 and 28
, the die pad DP in the semiconductor device
90
has such a depressed die pad structure as to be lower in position than the inner lead IL. This structure makes the inner lead IL and the surface of the semiconductor substrate such as the signal processing substrate As on the die pad DP almost flush in height, thereby facilitating wire bonding.
The cross section taken along the line A—A of
FIG. 28
corresponds to the structure view shown in FIG.
27
.
Further,
FIG. 29
is a conceptional view showing a structure of the moving part MV in the sensor substrate SC. As shown in
FIG. 29
, the moving part MV has a moving electrode MVP which is movably supported by a beam BM and a fixed electrode FXP which is so provided as to have a clearance between the moving electrode MVP and itself and form static capacitance therebetween.
The fixed electrode FXP is an electrode of semiconductor element having a structure to detect variation of static capacitance generated by the displacement of the moving electrode MVP. The cross section taken along the line B—B of
FIG. 29
is shown in FIG.
30
.
Thus, the sensor substrate SC needs to ensure the movement of the moving electrode MVP and therefore the moving part MV is covered with a cap CV made of silicon or glass to prevent the mold resin MR from entering.
Providing the cap, however, causes problems of an increase in manufacturing cost due to not only an increase in the number of parts but also necessity of a process to bond the cap CV on the sensor substrate SC.
SUMMARY OF THE INVENTION
The present invention is directed to a semiconductor device. According to a first aspect of the present invention, the semiconductor device comprises: a sensor substrate comprising a moving part on a first main surface thereof, for converting the displacement of the moving part into an electrical signal and outputting the electrical signal; an opposed substrate opposed to the first main surface of the sensor substrate, for transmitting the electrical signal with the sensor substrate through a bump provided around the moving part; and a sealing member provided at least in an edge portion of a gap defined by the sensor substrate and the opposed substrate, and in the semiconductor device of the first aspect, a sealed space is defined by the sensor substrate, the opposed substrate and the sealing member.
According to a second aspect of the present invention, in the semiconductor device according to the first aspect, the opposed substrate is a signal processing substrate for performing a predetermined processing on the electrical signal from the sensor substrate, and the sensor substrate is provided on the signal processing substrate.
According to a third aspect of the present invention, the semiconductor device according to the first aspect further comprises a signal processing substrate for performing a predetermined processing on the electrical signal from the sensor substrate, and in the semiconductor device of the third aspect, the opposed substrate is a wiring board having a wiring pattern to transmit the electrical signal from the sensor substrate to the signal processing substrate, and the sensor substrate is provided on the wiring board.
According to a fourth aspect of the present invention, in the semiconductor device according to the second aspect, the sealing member is made of resin and so provided as to cover only the edge portion of the gap defined by the sensor substrate and the opposed substrate.
According to a fifth aspect of the present invention, in the semiconductor device according to the second aspect, the sealing member is made of resin and so provided as to entirely cover the sensor substrate.
According to a sixth aspect of the present invention, in the semiconductor device according to the fifth aspect, the resin is silicone gel.
According to a seventh aspect of the present invention, the semiconductor device according to the fifth aspect further comprises: a barrier provided so as to surround at least the sensor substrate, having such a height as to reach a second main surface opposite to the first main surface of the sensor substrate, and in the semiconductor device of the seventh aspect, the resin is so provided as to fill the inside of the barrier.
According to an eighth aspect of the present invention, in the semiconductor device according to the second aspect, the sealing member is made of glass and provided between an edge portion of the first main surface of the sensor substrate and a main surface of the opposed substrate.
According to a ninth aspect of the present invention, in the semiconductor device according to the eighth aspect, the glass includes at least PbO.
According to a tenth aspect of the present invention, in the semiconductor device according to the second aspect, the sealing member is made of eutectic alloy including at least silicon and provided between an edge portion of the first main surface of the sensor substrate and a main surface of the opposed substrate.
According to an eleventh aspect of the present invention, in the semiconductor device according to the tenth aspect, the opposed substrate comprises a concave portion provided in the main surface of the opposed substrate correspondingly to a region in which the moving part and the bump of the sensor substrate are provided, and the moving part and the bump are partially contained in the concave portion.
According to a twelfth aspect of the present invention, in the semiconductor device according to the tenth aspect, the eutectic alloy further includes nickel and titanium.
According to a thirteenth aspect of the present invention, the semiconductor device comprises: a sensor substrate comprising a moving part on a first main surface thereof, for converting the displacement of the moving part into an electrical signal and outputting the electrical signal; and an opposed substrate opposed to the first main surface of the sensor substrate, for transmitting the electrical signal with the sensor substrate through a bump provided around the moving part, and in the semiconductor device of the thirteenth aspe
Clark Sheila V.
Mitsubishi Denki & Kabushiki Kaisha
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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