Wave transmission lines and networks – Long line elements and components – Strip type
Reexamination Certificate
1999-02-19
2002-05-07
Lee, Benny (Department: 2817)
Wave transmission lines and networks
Long line elements and components
Strip type
C257S728000, C257S664000, C257S778000
Reexamination Certificate
active
06384701
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a small, light-weight microwave and millimeter wave device which is suitable for mass production and has good high frequency characteristics.
2. Description of the Related Art
In recent years, as the processing speed of a data processing device and the resolution of an image processing device have increased, a high-speed, large-capacity personal communication apparatus using a high frequency wave such as a microwave or a millimeter wave has attracted public attention. As a microwave and millimeter wave device in such a communication apparatus, a module has been actively developed in which a high frequency semiconductor chip is mounted directly on a dielectric substrate having transmission lines thereon. As higher frequencies have been used, a flip-chip mounting method has attracted particular public attention, by which the semiconductor chip is connected onto the dielectric substrate via metal bumps.
FIG. 21
is a schematic diagram illustrating an HMIC
5100
Hybrid Microwave Integrated Circuit) as an exemplary microwave and millimeter wave device.
FIG. 21B
is a cross-sectional view of the HMIC 5100 taken along line
21
A-
21
B in FIG.
21
A.
The HMIC
5100
includes a single transistor chip
211
, a dielectric substrate
212
on which passive circuits
5150
in
FIG. 21A
have been formed by transmission lines, and metal bumps
213
in FIG.
21
B. The single transistor chip
211
and the dielectric substrate
212
are attached together, with the respective surface sides facing each other, so that electrodes on the single transistor chip
211
are physically and electrically connected to signal lines
214
and grounding conductor portions
215
on the dielectric substrate
212
via the metal bumps
213
. The grounding conductor portions
215
on the surface side of the dielectric substrate
212
are connected to a rounding conductor surface
217
in FIG. B on the reeves side of the dielectric substrate
212
via through holes
216
. A DC out capacitor
218
, a radial stub
219
, a chip resistor
220
, a chip capacitor
221
, and the like, are formed on the surface side of the dielectric substrate
212
as the passive circuits
5150
.
An example of such an HMIC technique is described in 1997 IEEE MTT-S digest, pp. 447-450.
Another such technique is a flip-chip mounting technique of an MMIC (Monolithic Microwave Integrated Circuit) onto the dielectric substrate
212
. The MMIC includes an active element such as a transistor and passive elements such as a transmission line, a spiral inductor and a thin film capacitor provided on the same semiconductor chip, thereby implementing functional blocks, such as an amplifier, a mixer and an oscillator, on the semiconductor chip.
FIG. 22A
illustrates an exemplary MMIC
222
being flip-chip mounted on the dielectric substrate
212
, and
FIG. 22B
is a cross-sectional view taken along line
22
A-
22
B in FIG.
22
A.
The illustrated flip-chip structure includes the MMIC
222
, the dielectric substrate
212
including transmission lines provided thereon, and the meal bumps
213
. The dielectric substrate
212
including transmission lines provided thereon, and the metal bumps
213
. The dielectric substrate
212
and the MMIC
222
are attached together, with the respective surface sides acing each other, so that electrodes provided along the periphery of the MMIC
222
are physically and electrically connected to signal lines
224
and the grounding conductor portions
215
on the dielectric substrate
212
via the metal bumps
213
. The grounding conductor portions
215
on the surface side of the dielectric substrate
212
are connected to the grounding conductor surface
217
in
FIGS. 21B
on the reverse side of the dielectric substrate
212
via the through holes
216
.
An exemplary MMIC flip=chip technique is described in 1994 IEEE MTT-S digest, pp. 1707-1710.
However, the conventional techniques have the following problems.
For HMIC, the first problem is that the semiconductor chips as the single active elements have to be mounted one by one, thus resulting in a high production cost. The second problem is that the semiconductor chip as the single active element is very small in size, and thus is difficult to handle. As a result, variation in the high frequency characteristics is likely to occur due to misalignment between the individual active elements and the substrate. The third problem is that the number of metal bumps which can be mounted on one semiconductor chip is limited, thereby resulting in an insufficient mounting strength and poor heat radiation characteristics. The fourth problem is that relatively large spacing has to be provided between the individual semiconductor chips for the mounting process, whereby the dielectric substrate requires a large area. Moreover, since such large spacing is provided between the semiconductor chips, the inductance between grounding terminals of each active element increases, whereby the operation of the element becomes unstable.
For MMIC, the first problem is that since the active element and the passive elements are designed and produced on the same semiconductor chip, any design change requires reproduction of the whole device, thereby requiring a long time for the device development. The second problem is that the specific resistance of the semiconductor substrate is smaller than that of the dielectric substrate, and a high Q value cannot be obtained, whereby it is difficult to produce a high-performance passive element. In particular, since the semiconductor substrate has a smaller resistance than that of the dielectric substrate, a passive circuit produced on the semiconductor substrate may suffer from characteristic deterioration due to factors such as leakage of a signal to the substrate. The third problem is that the passive elements occupy a major area of the semiconductor chip, thereby increasing the material cost The fourth problem is that the active element and the passive elements are integrated on the same semiconductor chip with a high density, thereby resulting in a poor electrical isolation characteristic between the respective elements.
Thus, while the HMIC technique and the MMIC technique have some advantages, they also have shortcomings to be overcome.
SUMMARY OF THE INVENTION
A microwave and millimeter wave device of the present invention includes: a dielectric substrate including at least one signal line, a passive circuit and a first grounding conductor portion which are formed on a surface side of the dielectric substrate; and a semiconductor substrate including a plurality of active elements. The signal line is physically and electrically connected to an input/output terminal of the active element via a metal bump; and the first grounding conductor portion is physically and electrically connected to a grounding terminal of the active element via another metal bump.
In one embodiment, the microwave and millimeter wave device further includes a second grounding portion on a surface side of the semiconductor substrate, wherein the second grounding portion is formed by connecting respective grounding terminals of the plurality of active elements to one another via a first conductor.
In one embodiment, a second conductor is provided on a reverse side of the semiconductor substrate; and the grounding conductor portion on the surface side of the semiconductor substrate is connected to the second conductor via a through hole.
In one embodiment, a grounding conductor surface is provided on a reverse side of the dielectric substrate; and the grounding conductor surface is connected to the grounding conductor portion on the surface side of the dielectric substrate via a through hole.
In one embodiment, the dielectric substrate includes a first dielectric layer, an intermediate conductor layer and a second dielectric layer; a grounding conductor surface is provided on a reverse side of the second dielectric layer; a ground conductor portion is provided on the surface side of the dielec
Kakimoto Noriko
Suematsu Eiji
Yamada Atsushi
Lee Benny
Sharp Kabushiki Kaisha
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