JPH0714928A - Monolithic integrated circuit - Google Patents

Abstract

PURPOSE:To provide a monolithic integrated circuit that allows improved noise radiation characteristics by suppressing magnetic field occurring when differential signal is transmitted. CONSTITUTION:On an integrated circuit board 8 consisting of a semiconductor substrate, an insulation film is formed, and on top of that, a pair of signal transmission lines 1 and 2 for conveying differential signal is formed, being wired between bonding pads 3 and 4 and resistor electrodes 5 and 6. In the middle of the transmission line 2, a silicon oxide film 7 is formed, and over it, the other signal transmission line 1 is formed, so that the middle parts of lines 1 and 2 overlap each other with the silicon oxide film 7 in-between.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monolithic integrated circuit in which all elements are formed on a semiconductor substrate to form a circuit.

[0002]

2. Description of the Related Art Conventionally, in a monolithic integrated circuit,
A signal transmission line connecting between a bonding pad for inputting / outputting an electric signal to / from the outside and a circuit element such as a resistor or a transistor is arranged so as to have a shortest wiring length. FIG. 5 shows an example thereof. In the figure,
The signal transmission lines 1 and 2 are wired in parallel with each other in order to connect the bonding pads 3 and 4 and the resistance electrodes 5 and 6 to the shortest distance.

[0003]

Since the two bonding pads for inputting / outputting the differential signal from the outside are generally arranged close to each other, the two signal transmission lines are also arranged close to each other. . Also, due to the nature of differential signals,
One and the other have opposite currents. Therefore, when a differential signal is transmitted to the signal transmission lines 1 and 2,
Magnetic field M ₁ and the current I current I ₁ is generated as shown in FIG. 5
_The magnetic field M ₂ generated by ₂ is generated in the direction in which the magnetic fields are mutually strengthened, and the synthetic magnetic field M is generated in the downward direction. For this reason, a magnetic field is generated from the monolithic integrated circuit to the outside, causing electromagnetic noise.

Therefore, the present invention has been made to solve the above problems, and provides a monolithic integrated circuit capable of suppressing the magnetic field generated outside the integrated circuit when transmitting a differential signal. The purpose is to

[0005]

In a monolithic integrated circuit of the present invention, an insulating film is formed on a semiconductor substrate on which elements constituting the circuit are formed, and at least one pair of differential signals transmitting differential signals is formed on the insulating film. A signal transmission line is formed, and a pair of signal transmission lines are crossed or overlapped at least once with an insulating means.

Here, one of the pair of signal transmission lines is formed on the first insulating film on the semiconductor substrate, and the second insulating film is formed on one of the signal transmission lines to form the insulating means. , The other of the pair of signal transmission lines may be formed on the second insulating film so that the pair of signal transmission lines intersect or overlap each other. Alternatively, one of the pair of signal transmission lines is formed on the first and second insulating films which are stacked and deposited on the semiconductor substrate, and the second insulating film is formed so as to sandwich the one signal transmission line. A contact hole is formed, and the other of the pair of signal transmission lines is the contact hole and the first
And a wiring formed on the second insulating film and connected to the wiring formed between the second insulating film.

[0007]

In the monolithic integrated circuit of the present invention, since the pair of signal transmission lines for transmitting differential signals intersect or overlap each other at least once through the insulating means, the pair of signal transmission lines intersect or overlap each other. On one side, the magnetic fields generated by the differential currents flowing through the signal transmission line are generated in mutually reinforcing directions, and the combined magnetic field is generated in a certain direction. Then, on the other side of the intersecting or overlapping portions, the combined magnetic field of the magnetic fields generated by the differential current is generated in the direction opposite to the combined magnetic field generated on the one side. In other words, the magnetic fields are generated in directions canceling each other on both sides of the portion where the pair of signal transmission lines cross or overlap each other. Therefore, the magnetic field is canceled out as a whole, and the magnetic field generated outside the integrated circuit can be suppressed. Further, the pair of signal transmission lines are electrically insulated because they intersect or overlap each other through the insulating means.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

FIG. 1 is a perspective view showing the structure of the monolithic integrated circuit of the first embodiment. A pair of signal transmission lines 1 and 2 are provided on an integrated circuit board 8 made of a semiconductor substrate on which circuit elements such as transistors are formed inside and on the surface, and an insulating film, a passivation film and the like (not shown) are formed on the surface. Formed and the bonding pads 3, 4
And the resistance electrodes 5 and 6 are connected. A silicon oxide film 7 serving as an insulating film is formed on an intermediate portion of one signal transmission line 1, and the other signal transmission line 2 is formed on the intermediate film, so that the signal transmission lines 1 and 2 are mutually formed. They are wired so that they overlap with each other.

The operation of this embodiment will be described with reference to FIG. As shown in the figure, the current I of the differential signal is applied to the signal transmission lines 1 and 2 which are overlapped with each other through the silicon oxide film 7.
₁ and I ₂ are flowing in opposite directions. On one side of the portion where the signal transmission line 1 and 2 overlap (the left side in the figure), a direction in which mutually reinforce the magnetic field M _1b of the magnetic field M _1a and current I ₂ current I ₁ is generated occurs, the synthesized magnetic field M ₁ Is generated downward. At the other side of the portion where the signal transmission line 1 and 2 overlap (right side in the figure), the magnetic field M _2b the field M _2a and the current I ₂ which the current I ₁ is generated occurs mutually reinforce each other, the combined magnetic field M ₂ is It is generated in the upward direction opposite to the above-mentioned synthetic magnetic field M ₁ . That is, the magnetic field M ₁ and the magnetic field M ₂ are generated in directions canceling each other. Therefore, when the integrated circuit is viewed as a whole, the magnetic field is canceled and the magnetic field generated outside the integrated circuit can be suppressed, so that the electromagnetic noise emission characteristic can be improved.

Next, a second embodiment will be described with reference to FIG. FIG. 3 is a perspective view showing the configuration of the monolithic integrated circuit of the second embodiment. Integrated circuit board 8 in which first layer and second layer insulating films (not shown) are formed on a semiconductor substrate
Two signal transmission lines 1 and 2 are formed on the top.
One of the signal transmission lines 2 is wired on the integrated circuit board 8 over the entire length, while the other signal transmission line 1 is formed on the integrated circuit board 8 in the middle of reaching the overlapping portion. In this overlapping portion, the conductive material in the contact holes 9 and 10 formed in the second-layer insulating film 12 and the signal transmission line 11 wired on the first-layer insulating film are connected.

Also in this embodiment, the current I of the differential signal is
₁ and I ₂ flow in mutually opposite directions as shown in FIG.
Therefore, the combined magnetic fields generated on the one side and the other side of the overlapping portions are in opposite directions, so that the magnetic fields cancel each other out as a whole. Therefore, since the magnetic field generated outside the integrated circuit can be suppressed, the electromagnetic noise radiation characteristic can be improved.

The present invention is not limited to the above embodiment, but various modifications can be made.

For example, although the silicon oxide film is used as the insulating film in the first embodiment, another insulating film such as a silicon nitride film may be used. Further, in the embodiment, the two signal transmission lines are superposed once, but the directions in which the magnetic fields are generated may be directions that cancel each other, and thus may be superposed two or more times. Further, in the embodiment, the two signal transmission lines are superposed, but they may be crossed via the insulating means. FIG. 4 shows an example thereof. In the pair of signal lines 1 and 2 formed on the integrated circuit substrate 8, the silicon oxide film 7 is formed in the intermediate portion of one signal transmission line 1.
The other signal transmission line 2 is formed thereon, and the signal transmission lines 1 and 2 intersect each other with the silicon oxide film 7 interposed therebetween. Similar to the other embodiments, when transmitting a differential signal, the magnetic fields are generated in the directions canceling each other on both sides of the intersection of the signal transmission lines 1 and 2, so that the magnetic fields are canceled as a whole, and the integrated circuit external It is possible to suppress the magnetic field generated in the field and improve the noise emission characteristics.

[0015]

As described in detail above, according to the monolithic integrated circuit of the present invention, a pair of signal transmission lines for transmitting a differential signal are crossed or overlapped with each other through insulating means, so that a differential current is generated. The magnetic fields can be generated so as to cancel each other on both sides sandwiching the intersecting or overlapping portions. Therefore, the magnetic field is canceled out as a whole, the magnetic field generated outside the monolithic integrated circuit can be suppressed, and the electromagnetic noise radiation characteristic can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of a monolithic integrated circuit according to a first embodiment.

FIG. 2 is a diagram showing a signal transmission line and a magnetic field direction of the first embodiment.

FIG. 3 is a perspective view showing a configuration of a monolithic integrated circuit according to a second embodiment.

FIG. 4 is a perspective view showing a configuration of a monolithic integrated circuit of a modified example of the embodiment.

FIG. 5 is a diagram showing a conventional signal transmission line and a magnetic field direction.

[Explanation of symbols]

1, 2, 11 ... Signal transmission line, 3, 4 ... Bonding pad, 5, 6 ... Electrode, 7 ... Silicon oxide film, 8 ... Integrated circuit substrate, 9, 10 ... Contact hole, 12 ... Insulating film

Claims (3)

[Claims] 1. A monolithic integrated circuit in which an insulating film is formed on a semiconductor substrate on which elements constituting a circuit are formed, and at least a pair of signal transmission lines for transmitting differential signals are formed on the insulating film, A monolithic integrated circuit, wherein the pair of signal transmission lines cross or overlap each other at least once via an insulating means. 2. One of the pair of signal transmission lines is formed on a first insulating film on the semiconductor substrate, and a second insulating film is formed on the one signal transmission line to provide the insulating means. 2. The monolithic structure according to claim 1, wherein the signal transmission lines of the pair are formed on the second insulating film, and the signal transmission lines of the pair intersect or overlap each other. Integrated circuit. 3. One of the pair of signal transmission lines is formed on first and second insulating films that are stacked and deposited on the semiconductor substrate, and the one signal transmission line is sandwiched so as to sandwich the one signal transmission line. A contact hole is formed in the second insulating film, and the other of the pair of signal transmission lines has the contact hole and the first hole.
2. The monolithic integrated circuit according to claim 1, wherein the monolithic integrated circuit is composed of a wiring on the second insulating film connected to the wiring formed by being interposed between the second insulating film and the second insulating film.