Active solid-state devices (e.g. – transistors – solid-state diode – Integrated circuit structure with electrically isolated... – Passive components in ics
Reexamination Certificate
2001-11-29
2003-09-23
Flynn, Nathan J. (Department: 2826)
Active solid-state devices (e.g., transistors, solid-state diode
Integrated circuit structure with electrically isolated...
Passive components in ics
C257S535000, C257S774000, C257S776000
Reexamination Certificate
active
06624500
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin-film electronic component and a motherboard, and more particularly to a thin-film electronic component and a motherboard, which are operated at high frequencies, suitably used for a thin-film capacitor, a thin-film inductor, a thin-film LC filter, a thin-film resistance, a thin-film RC filter, or the like.
2. Description of the Related Art
Accompanying the recent trend toward realizing electronic equipment in small sizes yet maintaining highly sophisticated functions, it has been strongly urged to provide electronic components having small size and slimness so that they can be installed in the electronic equipment to satisfy the demand for high-frequency use.
In a high-speed digital circuit of a computer that must process large quantity of data at high speeds, in particular, the clock frequency in a CPU chip is as high as from 200 MHz to 1 GHz, and the clock frequency of a bus among the chips is also as high as from 75 MHz to 133 MHz even on a level of a personal computer.
As the degree of integration of LSI increases and a larger and larger number of elements are provided in the chip, the power source voltage tends to be lowered to suppress electric power consumption. Accompanying an increase in the operation speed, an increase in the density, and a decrease in the voltage in the IC circuits, passive parts such as capacitors must also be designed in small sizes yet having large capacities to exhibit excellent characteristics for high-frequency pulses or high-speed pulses.
As the operation frequency increases, resistance and inductance possessed by the element cause an instantaneous drop in the power-source voltage on the side of the logic circuit, or new voltage noise. As a result, an error occurs on the logic circuit. In modern LSIs, in particular, the power source voltage has been lowered to suppress an increase in the consumption of electric power that results from an increase in the total number of elements, and the width of permissible change in the power source voltage has been decreased. During coming years, it is expected that there will be further increase in the number of elements and increase in the operation frequency, and consequently a reduction in resistance and inductance components on the mount portion will be of particular importance in connection with logic circuit errors.
As a natural consequence of such a trend, not only an improvement in the electrical characteristics of the passive element itself, but also mounting-related characteristics (mounting accuracy and mounting reliability) of higher level have been sought after. For example, higher mounting accuracy is required to cope with an increase in the number of the elements, and satisfactory reflow resistance is required for mounting components properly.
As a method for decreasing inductance in a connection portion of a capacitor, a thin-film capacitor is disclosed in U.S. Pat. No. 4,439,813. In this conventional thin film capacitor, to obtain electric signals fed from a lower electrode made of TiW, Ta, Al, and Cu in the shortest distance, a through hole is formed in an insulation layer, an upper electrode, and a protective layer, and, after forming a BLM layer made of Cr/Cu/Au on the inner wall of the through hole, a solder bump is formed on this BLM layer.
FIG. 6
shows the capacitor disclosed in this publication. On a supporting substrate
31
, a lower electrode
33
, an insulation layer
35
, an upper electrode
37
, and a protective layer
39
are stacked on top of one another. The lower electrode
33
is connected to an external terminal
41
via a through hole formed in the protective layer
39
. The upper electrode
37
is connected to an external terminal
43
via a through hole formed in the protective layer
39
. The external terminal
43
is formed on the insulation layer
35
.
However, the above-described thin-film capacitor has the following disadvantage. In this construction, the insulation layer
35
is formed on the lower electrode
33
by a sputtering method, an evaporation method, or a sol-gel method. Since the lower electrode
33
is subjected to a high-temperature process, the adhesion strength between the supporting substrate
31
and the lower electrode
33
tends to be deteriorated. Therefore, when the external terminals
41
and
43
, made of solder bumps, are coupled to the electrode disposed on a base, being fixed via the lower electrode
33
to the supporting substrate
31
, the external terminals
41
and
43
tend to be stripped from the supporting substrate
31
. This makes it impossible to attain adequate coupling strength between the thin-film capacitor and the base, with the result that the thin-film capacitor easily falls off due to some shock.
That is, the solder-bump external terminals
41
and
43
disposed via the lower electrode
33
on the supporting substrate
31
are put under unduly heavy load, and, when stripped off, breakage does not occur in the solder bump but occurs, for example, at the interface between the supporting substrate
31
and the lower electrode
33
. Thus, it is impossible to make the most of the strength of the external terminal, i.e. solder bump, resulting in deterioration in the mounting reliability.
To overcome such an inconvenience, an adherent layer may be provided between the supporting substrate
31
and the lower electrode
33
. In this case, however, the adherent layer is diffused or shifted due to the above-stated high-temperature process, and thus a desired function cannot be attained. As a result, the adhesion strength between the supporting substrate
31
and the lower electrode
33
is deteriorated.
SUMMARY OF THE INVENTION
An object of the invention is to provide a thin-film electronic component and a motherboard in which an external terminal is coupled to a supporting substrate with improved coupling strength.
The invention provides a thin-film electronic component comprising:
a supporting substrate;
a lower electrode formed on part of the supporting substrate;
an insulation layer formed on the lower electrode;
an upper electrode formed on the insulation layer;
a connection electrode formed on part of the supporting substrate located on a bottom surface of a through hole formed in the insulation layer, the connection electrode being electrically connected to the lower electrode; and
an external terminal disposed on the connection electrode within the through hole.
That is, the thin-film electronic component includes: a supporting substrate; a lower electrode formed on the supporting substrate; an insulation layer formed on the lower electrode; an upper electrode formed on the insulation layer; a connection electrode which is formed on a bottom surface of a through hole formed on the insulation layer and electrically connected to the lower electrode; and an external terminal disposed on the connection electrode within the through hole. In this construction, the connection electrode is disposed on the supporting substrate via a portion remaining free of the lower electrode. In other words, the inside of the through hole formed in the insulation layer serves as a region free of the insulation layer (insulation layer-free region), and the connection electrode provided within the insulation layer-free region is disposed on the supporting substrate via the portion free of the lower electrode.
Adopting such a structure confers the following advantages. Even if the insulation layer is formed by the sputtering, evaporation, or sol-gel method and the lower electrode is subjected to a high-temperature process, since the connection electrode is fabricated and disposed on the supporting substrate after completion of the formation of the insulation layer, it is possible to attain adequate coupling strength between the supporting substrate and the connection electrode disposed directly, or via an adherent layer, on the supporting substrate. This helps increase the coupling strength between the supporting substrate and the external terminal electr
Flynn Nathan J.
Hogan & Hartson LLP
Kyocera Corporation
Sefer Ahmed N.
LandOfFree
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