JP3936620B2 - High frequency module - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-frequency module, and more particularly to a high-frequency module that can be miniaturized.
[0002]
[Prior art]
Various mobile portable communication terminals such as mobile phones and PDAs (Personal Digital Assistants) are indispensable for our daily life.
[0003]
Such terminals are required to have multiple functions, downsizing, low power consumption, and the like, and in order to meet such demands, high frequency components such as power amplifiers which are the main components of these terminals Modules are also required to have higher frequencies, smaller sizes, lower power consumption, and lower prices.
[0004]
By the way, such a high-frequency module has been conventionally configured by mounting various components on alumina or a resin substrate.
[0005]
On the other hand, in recent years, an approach has been attempted in which a component mounted on a substrate is incorporated into a semiconductor substrate to constitute a high-frequency module.
[0006]
[Problems to be solved by the invention]
However, in the method of incorporating each component mounted on the substrate into the semiconductor substrate as an element or circuit, the size can be reduced compared to the high frequency module mounted with each component, but the bias circuit, the wiring of the high frequency circuit, the element, etc. Since the semiconductor substrate is arranged in parallel, there is a limit in reducing the area of the semiconductor substrate.
[0007]
In addition, a configuration that suppresses the area of the semiconductor substrate by stacking high-frequency circuit wirings and elements on the bias circuit is also considered. In this configuration, the electric field generated from the inductor and capacitor of the bias circuit is also considered. In addition, there is a problem that the magnetic field affects the wiring of the high frequency circuit and the characteristics are deteriorated.
[0008]
For this reason, it is necessary to provide a sufficient distance between the bias circuit and the wiring layer to prevent such an influence, which hinders the miniaturization of the high-frequency module.
[0009]
Therefore, an object of the present invention is to provide a high-frequency module that can reduce the size and size of the high-frequency circuit.
[0010]
[Means for Solving the Problems]
The high-frequency module according to the present invention is a high-frequency module including a high-frequency circuit having a bias circuit. The bias circuit is sandwiched between a lower capacitor formed on a semiconductor substrate, an upper capacitor, and a lower capacitor and an upper capacitor. The wiring layer of the high frequency circuit is formed on the bias circuit through an interlayer insulating film.
[0011]
For this reason, the wiring of the high-frequency circuit is electromagnetically separated from the bias circuit, preventing deterioration of the characteristics of the high-frequency circuit, increasing the degree of freedom in designing the wiring and elements, and reducing the size of the high-frequency module.
[0012]
Each of the upper capacitor and the lower capacitor has a structure in which a lower electrode, a dielectric, and an upper electrode are laminated. The upper capacitor uses the upper electrode as a ground electrode, and the lower capacitor uses the lower electrode as a ground electrode. Thus, a π-type filter circuit is configured, and the filter characteristics of the bias circuit can be improved.
[0013]
The upper capacitor and the lower capacitor are formed by laminating thin films of different materials, so that the high-frequency circuit can be thinly formed.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a high-frequency module according to the present invention will be described in detail with reference to the accompanying drawings.
[0015]
FIG. 1 is a diagram conceptually showing the configuration of an embodiment of a high-frequency module according to the present invention.
[0016]
In FIG. 1, a high frequency module 1 has a bias circuit 3 using a thin film of a different material on a semiconductor substrate (Si substrate) 2 as a platform, and a wiring layer 4 of the high frequency circuit on the bias circuit 3. Are stacked.
[0017]
The bias circuit 3 is provided with a high frequency choke coil 5, an upper capacitor 6 formed on the high frequency choke coil, and a lower capacitor 7 formed below the high frequency choke coil.
[0018]
The wiring layer 4 is provided with a GND electrode 8 and a high-frequency circuit wiring 9.
[0019]
Here, the upper capacitor 6 and the lower capacitor 7 are high-frequency and large-capacity capacitors, and as will be described in detail later, a lower electrode, a capacitive insulating film, an upper electrode, for example, a MIM having a multilayer structure of Pt / SrTiO ₃ / Pt. The capacitor is formed as a capacitor, and the high frequency choke coil 5 is an inductor wiring.
[0020]
As shown in the circuit diagram of FIG. 2, the lower capacitor constituting the bias circuit has a lower electrode as a ground electrode, and the upper capacitor has a π-type filter circuit with the upper electrode as a ground electrode. This improves the filter characteristics of the bias circuit.
[0021]
In addition, since the top and bottom of the choke inductor are grounded at high frequency, the electric field and magnetic field of the bias circuit can be cut off, increasing the design flexibility of the wiring and elements of the high frequency circuit, improving the circuit characteristics and improving the high frequency module. Miniaturization can be achieved.
[0022]
Next, an example of the manufacturing method of the high frequency module which concerns on this invention is demonstrated with reference to FIG.
[0023]
First, a SiO ₂ film (not shown) is formed on a semiconductor substrate 2 made of a semiconductor such as Si.
[0024]
Then, a Pt electrode film to be the lower electrode 10 is formed on the SiO ₂ film, and a SrTiO ₃ film 11 that is a ferroelectric material is formed on the Pt electrode film by a sol-gel method, a sputtering method, a CVD method, or the like. Then, a Pt electrode film to be the upper electrode 12 is formed thereon, and as shown in FIG. 3A, a large-capacity MIM capacitor having a multilayer structure of Pt electrode film / SrTiO ₃ film / Pt electrode film is formed as a lower capacitor. 7 is formed.
[0025]
Also, polyimide as an insulating material is applied on the SiO ₂ film and the lower capacitor 7 to form a first interlayer insulating film 13, and as shown in FIG. Next, the choke coil 5 is patterned.
[0026]
Here, a polyimide, which is an insulating material, is applied on the first interlayer insulating film 10 and the choke coil 5 to form a second interlayer insulating film 14, and the lower electrode 15 is formed as shown in FIG. A Pt electrode film as SrTiO ₃ film 16 and a Pt electrode film as a lower electrode 17 are laminated, and a large-capacity MIM capacitor having a multilayer structure is formed as an upper capacitor 6 at a position corresponding to the choke coil 5. A bias circuit 3 in which a choke coil 7 is disposed between the upper capacitor 6 and the lower capacitor 7 is formed.
[0027]
Then, a third interlayer insulating film 18 is formed by applying polyimide on the upper capacitor 6, and a high-frequency circuit made of Al is formed on the third interlayer insulating film 18 as shown in FIG. A GND wiring 9 is formed.
[0028]
Here, polyimide is applied on the GND wiring 9 to form a fourth interlayer insulating layer 19, and the high-frequency circuit wiring 9 and a high-frequency circuit element (not shown) are formed on the fourth interlayer insulating film 19. As shown in FIG. 3E, the wiring layer 4 of the high-frequency circuit including the GND wiring 9 and the wiring 9 is formed.
[0029]
The upper capacitor is formed with the upper electrode as a ground electrode, and the lower capacitor is formed with the lower electrode as a ground electrode.
[0030]
【The invention's effect】
In the present invention, a high-frequency module in which the area and thickness of a high-frequency circuit to be mounted can be suppressed can be created.
[Brief description of the drawings]
FIG. 1 is a sectional view conceptually showing the configuration of a high-frequency module according to the present invention. FIG. 2 is a circuit diagram showing a bias circuit of the high-frequency module according to the present invention. Sectional view shown [Explanation of symbols]
1 ... RF module 2 ... semiconductor substrate 3 ... bias circuit 4 ... wiring layer 5 ... choke coil 6 ... upper capacitor 7 ... lower capacitor 8 ... GND electrode 9 ... wire 10, 15 ... lower electrode 11, 16 ... SrTiO ₃ film 12, 17 ... Upper electrode 13 ... First interlayer insulating film 14 ... Second interlayer insulating film 18 ... Third interlayer insulating film 19 ... Fourth interlayer insulating layer

Claims (2)

In a high frequency module equipped with a high frequency circuit having a bias circuit,
The bias circuit includes:
A lower capacitor formed on a semiconductor substrate;
An upper capacitor;
An inductor formed by being sandwiched between the lower capacitor and the upper capacitor;
The upper capacitor and the lower capacitor are:
Each has a configuration in which a lower electrode, a dielectric, and an upper electrode are laminated,
The upper capacitor has the upper electrode as a ground electrode,
The lower capacitor uses the lower electrode as a ground electrode,
The wiring layer of high-frequency circuits, high-frequency module, wherein the Ru Tei is formed via an interlayer insulating film on the bias circuit. Wherein the upper capacitor and the lower capacitor, the high-frequency module according to claim 1, wherein Tei Rukoto is formed by laminating thin films of different materials, respectively.

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