JPH07120707B2 - Microwave integrated circuit - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a wiring line for a semiconductor integrated circuit, and more particularly to reducing an external leakage electromagnetic field.

[Conventional technology]

As a conventional line of this type, a microstrip line composed of a conductor formed on the back surface of a semiconductor substrate and a conductor formed on a semiconductor substrate is used. Since the electromagnetic field leaks around this line, there is a drawback that the lines are coupled and the signal leaks when the distance between the lines is narrowed by integrating the circuits or when the lines cross each other. It was In particular, this is a big problem in microwave integrated circuits that use high frequencies in the microwave band.

The above points will be described by taking an m × n matrix switch circuit as an example. This type of conventional m × n (1 ≤ m, 1 ≤
n) The matrix switch circuit is shown in FIG.

In FIG. 5, input terminals IT1 to ITm are respectively connected to one ends of input signal lines IL1 to ILm, and output terminals OT1 to OTn are respectively connected to one ends of output signal lines OL1 to OLn. Further, the input signal lines IL1 to ILm and the output signal lines OL1 to OLn intersect with each other at intersections Cij (i = 1,2, ..., m, j = 1,2, ..., n).
, And one-input one-output switch Sij is provided at each of these intersections, and a signal synthesizer Mij is inserted in each output signal line OLj at that point. In addition, input signal line IL1
~ ILm and the other end of each of the output signal lines OL1 to OLn are connected to a terminating resistor I
Connected to R1-IRm and OR1-ORn. In FIG. 5, the structure of the input signal lines IL1 to ILm and the output signal lines OL1 to OLn is a microstrip line structure.

An example of the intersection Cij is shown in FIG. In the figure, the input signal line IL and the output signal line as the microstrip line
The OL is crossed by Air Bridge 1. At the intersection of these microstrip lines, input signal line IL
Signal coupling occurs between the output signal line OL and the output signal line OL. In this regard, for example, "The Institute of Electronics and Communication Engineers 1984 General National Convention
S9-1 ”, it is reported that it is difficult to reduce the coupling by about 40 dB at the frequency of 1 CHz.

In FIG. 5, one-input one-output switch Skl (1≤k≤
When m, 1 ≦ l ≦ n) is turned on, the signal input to the input terminal ITk is input signal line ILk, 1 input 1 output switch SK
l, signal synthesizer Mkl, output signal line OLl and signal synthesizer Mpl
It is output to OTl of the output terminal through (p = k + 1, k + 2, ..., M). Similarly, an arbitrary input terminal and output terminal can be connected. 1 input 1 output switch Sij
The on / off ratio of is, for example, 50 at a frequency of 1 GHz.
It is possible to manufacture products with dB or higher.

[Problems to be solved by the invention]

However, no matter how high the ON / OFF ratio of the 1-input 1-output switch Sij is set, it is difficult to increase the ON / OFF ratio at the output terminal OTj because an unnecessary signal leaks from the intersection Cij. For example, 1-input 1-output switch S11, S2
1, ..., When Sm1 is in the off state, the output terminal OT1 has, in addition to the leakage signal from the 1-input 1-output switch S11, S21, ..., Sm1, the intersection C11, C21 ,.・, Leakage signal from Cm1 is added and output.

Therefore, a matrix switch circuit having a high on / off ratio cannot be realized by a monolithic IC.
Also in other microwave integrated circuits, it is difficult to fabricate an amplifier circuit having high gain due to leakage between lines, and layout is restricted because lines cannot approach or intersect each other, resulting in high integration. However, there are some drawbacks such as not being able to do it and sometimes not being able to configure the IC.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a line with little signal leakage even when the lines approach or intersect each other.

[Means for solving problems]

The present invention relates to a microwave integrated circuit which constitutes a matrix switch circuit and in which an input line is connected to an output line via a 1-input 1-output switch, and a central conductor is surrounded by a conductive wall via a dielectric. A metal-covered line is formed on a semiconductor substrate, and a signal line or a DC bias line consisting of an input line and an output line is wholly or partially composed of the metal-covered line, and the signal line or the DC bias line crosses. Then, only one of them is surrounded by a conductive wall.

[Action]

In the line according to the present invention, there is little signal leakage due to the approach and intersection of the lines.

〔Example〕

FIG. 1 is a circuit diagram showing an embodiment of an integrated circuit according to the present invention. In FIG. 1, A1 to Am are conductive walls forming a metallized line, and in FIG. 1, the same or corresponding portions as those in FIG. 5 are designated by the same reference numerals.

As shown in FIG. 1, the input signal lines IL1 to ILm are surrounded by conductive walls A1 to Am, and both ends of the conductive walls A1 to Am are grounded.

FIG. 2 shows a configuration example of the input signal line ILi (i = 1, 2, ..., M) and the conductive wall Ai. FIG. 2 is a sectional view, and the input signal line ILi extends perpendicularly to the paper surface.

Next, a procedure for manufacturing the metal-covered line shown in FIG. 2 will be described. First, the bottom conductive wall Ai1 that is the first conductor wiring layer is formed on the silicon substrate 2, then the dielectric layer 3a such as polyimide that is the first dielectric layer is formed, and the second dielectric layer 3a is formed on the dielectric layer 3a.
The input signal line ILi which is the conductor wiring layer of is manufactured. next,
The second dielectric layer 3b is produced, and the dielectric layers 3a and 3b are surrounded by the conductive walls Ai2 for the side surface and the upper surface which are the third conductor wiring layer. At this time, the conductive walls Ai1 and Ai2 are electrically coupled.

The intersection Cij shown in FIG. 1 (i = 1,2, ..., m, j = 1,
An example of 2, ..., N) is shown in FIG. FIG. 3 is a sectional view. In the figure, the input signal line ILi extends perpendicularly to the paper surface, and the output signal line OLj extends parallel to the paper surface. The manufacturing procedure is
An insulating dielectric layer 3c and an output signal line OLj are formed on the silicon substrate 2, and an insulating dielectric layer is formed on the output signal line OLj.
The conductive wall Ai, the dielectric layer 3e, and the input signal line ILi are manufactured with the 3d in between. Due to this structure, the input signal line
Most of the energy of the signal flowing through ILi is confined and transmitted in the region surrounded by the conductive wall Ai. Therefore, the electromagnetic field coupling between the input signal line ILi and the output signal line OLj can be significantly reduced as compared with the case where the conventional microstrip lines cross each other, and the 1-input 1-output switch having a high on / off ratio is provided. Is used, the on / off ratio of the monolithic matrix switch circuit can be increased.

In the above embodiment, the output signal line may be a metal covered line instead of the input signal line. Further, both the input signal line and the output signal line may be metal-coated lines.

FIG. 4 shows an example of the structure of the intersection where both the input signal line and the output signal line are metal-coated lines. FIG. 4 is a cross-sectional view of the intersection, in which the input signal line ILi extends perpendicular to the paper surface and the output signal line OLj extends parallel to the paper surface. On the silicon substrate 2, the insulating dielectric layer 3 is sandwiched between the output signal line OLj, the output signal line conductive wall 4j, and the input signal line ILi.
And the conductive wall Ai for the input signal line is produced.

In the above-mentioned embodiment, the silicon substrate is used as an example of the substrate, but a semiconductor substrate such as GaAs may have the same structure. Also, the matrix switch circuit has been described as an example,
A great effect can be expected even when it is necessary to take isolation between lines in a circuit such as an amplifier circuit.

〔The invention's effect〕

INDUSTRIAL APPLICABILITY As described above, the present invention forms a metal-coated line whose central conductor is surrounded by an electrically conductive wall via a dielectric on a semiconductor substrate, and uses a signal line or a DC bias line composed of an input line and an output line. All or part of the line is covered with metal, and at the part where the signal line or the DC bias line crosses, only one of them is surrounded by the conductive wall, so that Since it is possible to reduce the signal leakage of lines that approach or intersect without forming a step, it is possible to realize a highly integrated circuit such as a matrix switch circuit having a high on / off ratio or an amplifier circuit having a high gain. Especially, the effect is great in the microwave circuit.

[Brief description of drawings]

1 is a circuit diagram showing an embodiment of an integrated circuit according to the present invention, FIG. 2 is a sectional view showing a metal-coated line which constitutes the integrated circuit of FIG. 1, and FIG. 3 is an integrated circuit of FIG. FIG. 4 is a cross-sectional view showing an embodiment of the intersection of FIG. 4, FIG. 4 is a cross-sectional view showing the second embodiment thereof, FIG. 5 is a circuit diagram showing a conventional integrated circuit, and FIG. 6 is a perspective view showing the intersection. It is a figure. IT1 to ITm …… input terminal, IL1 to ILM …… input signal line, OT1
~ OTn …… Output terminal, OL1 ～ OLn …… Output signal line, Cij ……
Intersection, Sij ... 1 input 1 output switch, Mij ... Signal combiner, IR1 to IRm, OR1 to ORn ... Termination resistance, A1 to Am ... Conductive wall.

Claims (1)

[Claims] 1. A microwave integrated circuit, which constitutes a matrix switch circuit and has an input line connected to an output line through a 1-input 1-output switch, wherein a central conductor is surrounded by a conductive wall through a dielectric. A metal-coated line on a semiconductor substrate, and the signal line or the DC bias line consisting of the input line and the output line is wholly or partly composed of the metal-coated line, and the signal line or the DC bias line is The microwave integrated circuit, wherein only one of the intersecting portions is surrounded by the conductive wall.