JPH0399460A - Semiconductor device - Google Patents

Abstract

PURPOSE:To dispense with a conductive case and to lessen a semiconductor device of this design in cost by a method wherein a conductive film is formed on a part of an insulating film, which is formed on a board where an electric circuit has been formed, opposed to the electric circuit and grounded for high frequency. CONSTITUTION:For instance, a first insulating film 2, a first conductor film 3, a second insulating film 4, a third insulating film 5, and a second conductor film 6 are formed in this sequence on a semiconductor substrate 1 of GaAs, Si, or the like. Furthermore, a first electric circuit 7 is provided between the second insulating film 4 and the third insulating film 5, and a second electric circuit 8 is formed on the board 1. The first conductor film 3 and the second conductor film 6 are grounded or connected to a power source Vd. Therefore, the conductors 3 and 6 serve as a grounding conductor in microwave. By this constitution, the first and the second electric circuit, 7 and 8, and the first electric circuit 7 and an external electric circuit are isolated from each other in microwave, so that the influence of an external circuit on a semiconductor device of this design can fully be eliminated without using a conductive case or a conductive lid which is usually used in a conventional semiconductor device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device, and particularly to a multilayer MMIC (microwave monolithic integrated circuit) used in the microwave band.

[Prior Art] FIG. 4 is a cross-sectional view showing an example of the structure of a portion of a conventional semiconductor device related to the present invention, in which (1) is a semiconductor substrate such as GaAs or Si; Amplifier 1 on the surface
Electric circuits such as a phase circuit and a signal processing circuit are formed. (12) is a conductive casing that houses the semiconductor substrate (1), and the semiconductor substrate (1) is attached to the casing (
12) and is electrically connected to this housing. Reference numeral (13) denotes a cover plate made of a conductive material such as metal, which is connected to the housing (12) by solder or the like, and is kept at the same potential as the housing. Generally, such a configuration is called a module configuration.

By the way, in a microwave band high frequency circuit, the substrate (1)
In order to prevent the circuit formed on the top from being affected by other circuits, the substrate (1) is surrounded by a high-frequency grounded conductor and is isolated from the outside (especially in the upper direction) in terms of microwaves. There is. In the conventional device shown in Fig. 4, the conductive casing (
12) and the cover plate (13) are grounded to achieve the above separation.

In such a conventional semiconductor device, a conductive casing (12)
Assembly work such as installing the semiconductor substrate (1) inside and soldering the cover plate (13) to the housing (12) is required.
The cost was getting high. Furthermore, since the conductive casing (12) is used, there is a problem that the entire semiconductor device becomes larger and heavier.

The purpose of this invention is to solve the above-mentioned problems. By providing a means in a semiconductor device that has the same function as a conventional conductive housing, the conductive housing becomes unnecessary and the assembly process becomes easier. It is an object of the present invention to provide a semiconductor device that can reduce costs by requiring fewer steps, and can also be made smaller and lighter.

[Means for Solving the Problems] In a first embodiment of the semiconductor device of the present invention, at least one layer of an insulating film is formed on a substrate on which an electric circuit is formed, and at least one layer of the insulating film is connected to the electric circuit. A conductor film is formed on opposing portions, and the conductor film is grounded at high frequency.

In a second embodiment of the semiconductor device of the present invention, a plurality of layers of insulating films are formed on a substrate on which an electric circuit is formed, another electric circuit is formed between the insulating films, and at least one of the insulating films is formed. A conductor film is formed in a portion necessary for high-frequency isolation between the electric circuits, and the conductor film is grounded at high frequency.

In a third embodiment of the semiconductor device of the present invention, a plurality of layers of insulating films are formed on a substrate on which an electric circuit is formed, another electric circuit is formed between the insulating films, and at least one of the insulating films is formed. A conductor film is formed on a portion necessary for high-frequency isolation between the electric circuits and on the upper surface of the insulating film, and each conductor film is grounded at high frequency.

[Function] In the semiconductor device according to the present invention, the high-frequency grounded conductive film acts as a microwave grounded conductive plane, and this conductive film is connected between an electric circuit inside the device and an external electric circuit, or between an electric circuit inside the device and an external electric circuit. Since it acts as a shield to isolate the electrical circuits formed therein, there is no need for a conductive casing or a conductive lid as in the conventional device shown in FIG.

[Embodiment] FIG. 1 shows a first embodiment of a semiconductor device according to the present invention. In the figure, (1) is a semiconductor substrate such as GaAs or Si, and a first Layer insulation film (2)
, first layer conductor 11N (3), second layer insulating film (4), third layer conductor 11N (3), second layer insulating film (4),
A layer insulating film (5) and a second layer conductor film (6) are formed in this order. The second layer insulating film (4) and the third layer insulating film (
A first electric circuit (7) is formed between the substrate (1) and a second electric circuit (8). Here, the first layer conductor film (3) and the second layer conductor film (6) are connected to the ground or the power supply Vdd, and each of these conductor films (3) and (6) is a ground conductor in terms of microwaves. Acts as a surface.

By the way, generally in high frequency circuits such as microwave circuits,
In order to prevent each circuit from influencing each other, it is necessary to shield the circuits from each other at high frequencies. In the first embodiment of the invention described above, the first layer conductor! ! (:l) acts as a ground conductor plane, thereby completely separating the first electric circuit (7) and the second electric circuit (8) in terms of microwaves. Furthermore, since the second layer conductor film (6) can isolate the first electric circuit (7) from the electric circuit in the upper layer of this electric circuit or from an external electric circuit, the above-mentioned The first electrical circuit (7) is not influenced by upper or external electrical circuits. In particular, since the second M conductor film (6) which is microwave-grounded is provided on the upper surface of the third layer insulating film (5) which is the uppermost layer of the semiconductor device, it is possible to Therefore, the influence of circuits outside the semiconductor device can be completely eliminated without using a separate lid.

FIG. 2 shows a second embodiment of the semiconductor device of the present invention.

In the figure, components indicated by the same reference numbers as those in FIG. 1 represent the same or equivalent components in the semiconductor device of FIG. 1. A photodiode (10) is mounted on a substrate (1). The first layer conductor film (3
) are formed with small rectangular holes (9), (9), each side of which is shorter than the wavelength input at the frequency used. The photodiode (10) receives an optical signal modulated by microwaves, and the second electric circuit (8) amplifies the microwave modulated signal received by the photodiode (lO), The electrical circuit (7) performs the necessary processing on the amplified microwave modulated signal.

The first layer conductor 8 (3), which is grounded in terms of high frequency, has the small holes (9), (9), etc. formed as described above, so that the incident light from the upper part is transmitted through the photodiode (lO ). However, the small holes (9), (9') above...
... is a small hole with one side shorter than the wavelength of the microwave modulation signal used, so the first layer conductor M(3) acts as a shield similar to a shield mesh from a microwave perspective, and the first electrical separating the circuit (7) and the second electric circuit (8);
It is possible to prevent two electrical circuits from influencing each other. Note that in this example, a photodiode (lO
Although the small hole is formed in the upper part of ), the small hole may be formed in a portion of the conductive film on other circuit elements such as a laser diode, for example.

FIG. 3 shows a third embodiment of the semiconductor device of the present invention.
In the same figure, constituent elements designated by the same reference numbers as those in FIG. 1 represent the same or equivalent components in the semiconductor device of FIG. Additionally, an inductor H) is provided. The inductor is generally called a spiral inductor. Strong magnetic lines of force are generated in the upper part of the inductor (11), which has a particularly large influence on the first electric circuit (7) in the upper part.Therefore, in this third embodiment, only the upper part of the inductor (11) is A first layer insulation 5 (31) is provided and is grounded in terms of high frequency. In this embodiment, a conductor film was selectively formed only on the top of the inductor (11), but a similar conductor film may be provided on other electric circuit elements such as FETs and couplers. In short, it is only necessary to selectively provide the conductor film as described above only on electrical circuits that may affect other electrical circuits or are susceptible to influence from other electrical circuits.

In each of the above embodiments, the first electric circuit (7) is formed between the second layer insulation 19 (4) and the third layer insulation film (5),
A second electrical circuit (8) was formed on the substrate (1), 2
It is sufficient that the two circuits are formed on separate layers, and the circuits may be formed on any layer.Also, in each of the examples, the electric power circuit is a two-layer circuit, but it is not necessary that the circuit is formed on two or more layers. You can. Further, the substrate (1) may be a dielectric substrate such as alumina or sapphire other than a semiconductor substrate.

[Effects of the Invention] As described above, according to the present invention, the conductive film formed between the layers of the insulating film or on the top of the insulating film acts as a shield against microwaves. No housing or conductive lid is required; therefore, the assembly process for the device is reduced compared to conventional devices, reducing manufacturing costs and making it possible to make the device smaller and lighter. .

[Brief explanation of drawings]

FIG. 1 is a perspective view for explaining the structure of the main part of a first embodiment of the semiconductor device of the present invention, and FIG. 2 is a perspective view for explaining the structure of the main part of the second embodiment of the semiconductor device of the invention. 3 is a perspective view for explaining the structure of the main part of the third embodiment of the semiconductor device of the present invention, and FIG. 4 is a perspective view of the part of the conventional semiconductor device related to the present invention. FIG. 3 is a perspective view for explaining the structure. (1)...Substrate, (2)...First layer insulating film, (3)
...First layer conductor film, (4)...Second layer insulating film, (5
)...Third layer insulating film, (6)...Second layer conductor film, (
7)...First electric circuit, (8)...Second electric circuit, (31)...Conductor film. Deputy Masuo Oiwa 1st ■! A3 Diagram No. 4 Sobayashi Zui, I4 Taiji Syndrome 2゛ Hirol! Tsukiku body 3: number t4i 4L boy

Claims (3)

[Claims] (1) At least one layer of insulating film is formed on a substrate on which an electric circuit is formed, a conductive film is formed on at least a portion of the insulating film facing the electric circuit, and the conductive film is grounded at high frequency. A semiconductor device characterized by: (2) Forming a plurality of layers of insulating films on a substrate on which electric circuits are formed, forming other electric circuits between the insulating films, and connecting at least the electric circuits between the insulating films with high frequency. A semiconductor device characterized in that a conductor film is formed in a portion necessary for separation, and the conductor film is grounded at a high frequency. (3) Forming a plurality of layers of insulating films on a substrate on which an electric circuit is formed, forming another electric circuit between the insulating films, and connecting at least each of the electric circuits of the insulating film with high frequency. A semiconductor device characterized in that a conductor film is formed on a portion necessary for isolation and on the upper surface of an insulating film, and each conductor film is grounded at high frequency.