Active solid-state devices (e.g. – transistors – solid-state diode – Integrated circuit structure with electrically isolated... – Passive components in ics
Reexamination Certificate
2002-12-06
2004-11-09
Prenty, Mark V. (Department: 2822)
Active solid-state devices (e.g., transistors, solid-state diode
Integrated circuit structure with electrically isolated...
Passive components in ics
C257S531000, C257S532000
Reexamination Certificate
active
06815796
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a composite module such as a high frequency module and its production process, and more particularly to a composite module which can be made multifunctional and compact without requiring any external chip part and to its production process.
2. Description of the Related Art
Recently, the radio communication technology for portable telephones and the like has become indispensable to our life.
Under such circumstances, mobile communication portable terminals are demanded to be multifunctional, compact and low in power consumption, and a main component high-frequency module is also demanded to have a higher frequency, a reduced size with lower height, lower power consumption and a lower cost.
A conventional high-frequency module of this kind has active and passive components mounted on an alumina or resin substrate.
Meanwhile, approaches using an LTCC (Low Temperature Co-fired Ceramic) which can incorporate passive elements into a substrate itself, an MMIC (Microwave Monolithic Integrated Circuit) which incorporates passive parts onto an active element substrate, and an SOC (System On Chip) which has analog and digital circuits including a high-frequency circuit configured on a single chip without discriminating between them have been tried in recent years.
But, the LTCC has problems in wiring and precision of a built-in passive element, and the MMIC and the SOC have problems of a drop in yield, a cost rise, and a difficulty in production of a high-quality compact passive element due to a complex production process.
They all have to depend on a chip part for a passive element with a large element value.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a composite module, which is multifunctional, compact, low in power consumption, and low in cost, and a production process thereof.
It is also an object of the present invention to provide a composite module, which has an inductor and a capacitor formed on the same substrate and can be used for a high-frequency module such as a power amplifier, and a production process thereof In order to achieve the above objects, a composite module of the present invention comprises a substrate; a capacitor which is formed by stacking thin films of different types of materials on the substrate; a first wiring layer which is formed on the capacitor; a first interlayer insulation film which is formed on the first wiring layer; a magnetic film which is formed on the first interlayer insulation film; a second interlayer insulation film which is formed on the magnetic film; a first inductor pattern which is formed on the second interlayer insulation film; a third interlayer insulation film which is formed on the second interlayer insulation film; a second inductor pattern which is formed on the third interlayer insulation film to partly overlap with the first inductor pattern; a second wiring layer which is formed on the third interlayer insulation film; and a high-frequency integrated circuit which is connected to the first wiring layer and to the second wiring layer and mounted on the substrate.
The capacitor is formed of an MIM capacitor having a Pt/SrTiO
3
/Pt structure and functions as a high-frequency high-capacity bypass capacitor.
And, the capacitor is formed of an MIM capacitor having SiO
2
as a dielectric substance and functions as a matching low-capacity capacitor.
The first inductor pattern and the second inductor pattern are formed to partly overlap with the magnetic film to configure a two-layered magnetic thin film loaded inductor which confines magnetic flux by the magnetic film and functions as a high-frequency choke coil.
A distance between the first inductor pattern and the magnetic film is determined by a thickness of the second interlayer insulation film, and a distance between the second inductor pattern and the first inductor pattern is determined by a thickness of the third interlayer insulation film.
In the above configuration, the magnetic film is made of a nanogranular magnetic thin film.
The magnetic thin film loaded inductor is formed at a position different from the capacitor, and the first wiring layer is removed at the position where the magnetic thin film loaded inductor is formed.
The magnetic thin film loaded inductor is stacked on the capacitor.
And, the capacitor includes a high-frequency high-capacity bypass capacitor configuring a bias section and a matching capacitor configuring a high frequency section; the magnetic film, the first inductor pattern and the second inductor pattern function as a magnetic thin film loaded inductor which configures the bias section; a matching inductor which configures a high frequency section is further formed on the substrate; and the bias section including the high frequency high-capacity bypass capacitor and the magnetic thin film loaded inductor and the high-frequency section including the matching capacitor and the matching inductor are disposed on the substrate with their positions displaced from each other.
The substrate is made of a high-resistance silicon substrate.
The first to third interlayer insulation films are made of polyimide and have a total thickness of 15 &mgr;m or more.
The high-frequency integrated circuit is made of a GaAs MMIC (Microwave Monolithic Integrated Circuit), and the GaAs MMIC configures an active element of a power amplifier.
The substrate has a counter sunk portion, and the high-frequency integrated circuit is mounted in the counter sunk portion.
The high-frequency integrated circuit is connected to the second wiring layer via a bonding wire.
The high-frequency integrated circuit is connected to the second wiring layer via through holes formed in the first to third interlayer insulation films.
The high-frequency integrated circuit is connected as a flip chip type to the second wiring layer.
A process of producing a composite module of the present invention comprises a first step of forming a capacitor by stacking different types of materials on a substrate; a second step of forming a first wiring layer on the capacitor; a third step of forming a first interlayer insulation film on the first wiring layer; a fourth step of forming a magnetic thin film loaded inductor on the first interlayer insulation film; a fifth step of forming a second wiring layer on the magnetic thin film loaded inductor; and a sixth step of mounting a high-frequency integrated circuit, which is connected to the first wiring layer and to the second wiring layer, on the substrate.
Here, the first step includes a step of forming an MIM capacitor having a Pt/SrTiO
3
/Pt structure which functions as a high-frequency high-capacity bypass capacitor.
The first step includes a step of forming an MIM capacitor having SiO
2
, which functions as a matching low-capacity capacitor, as a dielectric substance.
The fourth step includes a step of forming a magnetic film on the first interlayer insulation film; a step of forming a second interlayer insulation film on the first interlayer insulation film including the magnetic film; a step of forming a first inductor pattern on the second interlayer insulation film to partly overlap with the magnetic film; a step of forming a third interlayer insulation film on the second interlayer insulation film including the first inductor pattern; and a step of forming a second inductor pattern on the third interlayer insulation film to partly overlap with the first inductor pattern.
The magnetic thin film loaded inductor functions as a high-frequency choke coil.
A distance between the first inductor pattern and the magnetic film is determined by a thickness of the second interlayer insulation film, and a distance between the second inductor pattern and the first inductor pattern is determined by a thickness of the third interlayer insulation film.
The magnetic film is formed of a nanogranular magnetic thin film.
The magnetic thin film loaded inductor is formed at a position different from the capacitor, and the first wiring lay
Fujimoto Masayuki
Ota Kenichi
Satomi Manabu
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