JPS60165752A - Semiconductor integrated circuit - Google Patents

Abstract

PURPOSE:To stabilize the operation of a circuit in an IC which includes a differential amplifier by adjacently forming two differential signal lines of the amplifier in parallel, and providing two wirings shortcircuted by a low resistor at both outsides, thereby reducing a noise generated at the signal lines. CONSTITUTION:A thick field SiO2 film 5 is formed on the periphery of an Si substrate 7, a low resistance diffused region 3 is formed on the surface layer of the substrate 7 surrounded by the film 5, an insulating film is coated on the region 3, and two differential signal lines 8R, 8L are adjacently coated in parallel on the film. Then, contacting holes 4 are opened at both ends of the region 3, metal wiring layers 2R, 2L for connecting a constant-voltage source are buried in the holes, and the lines 8R, 8L are surrounded. Then, signal lines 1R, 1L are mounted on the film 5, and the entire surface including them is coated with a protective film 6. Thus, even if the potentials of the lines 1R, 1L are abruptly varied, the variations are shielded by the layers 2R, 2L, and the differential value of the lines 8R, 8L does not alter.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a semiconductor integrated circuit, and particularly to a semiconductor integrated circuit including a differential amplifier.

(Prior Art) As the scale of semiconductor integrated circuits increases, patterns become finer, multilayered, and circuits become more dynamic, and more and more semiconductor integrated circuits include differential amplifier circuits.

FIGS. 1A and 1B are a plan view and a sectional view of an example of a conventional MO8 type integrated circuit.

In FIG. 1 (al, (b)), 1 is a metal wiring layer forming a signal line, 2 is a metal wiring layer forming a ground or power source, 3 is an N-type diffusion layer, and 4 is a metal wiring layer and a diffusion layer. 5 is a silicon oxide film that forms the transistor gate and interlayer insulating film, 6 is a protective film called passivation, and silicon oxide film, nitride film, glass, etc. are usually used. 7 is a silicon oxide film. It's on the board.

FIG. 2 is a circuit diagram of an example of a conventional differential amplifier circuit.

In Fig. 2, Q1 to Q6 are MOSFETs D.

D is a differential signal line, P is a precharge signal line of the differential amplifier, and S is a start signal line of the differential amplifier.

As the scale of such integrated circuits increases, the patterns become finer, but changes in the thickness direction of each layer hardly change in order to ensure the reliability of the electromigrain layer 7 of the metal wiring layer.

Therefore, unlike a normal printed circuit board, the capacitance between adjacent wirings increases due to the influence of electric lines of force. For example, in a pattern for a 256 kilobit memory, the capacitance between adjacent wires is about 20 inches of the total wire capacitance. Therefore, if the potential of one signal line in adjacent wirings changes, noise will occur in the other signal line. If this noise occurs on one side of the differential signal line, for example, it may cause malfunction of the differential amplifier. As a countermeasure to this problem, shielding is usually considered in which layers to which a ground potential is applied are formed above and below, but multi-layering is disadvantageous in integrated circuits. As described above, semiconductor integrated circuits including differential amplifiers have the disadvantage that they tend to generate noise or that attempts to prevent noise are disadvantageous in manufacturing.

(Object of the Invention) An object of the present invention is to provide a semiconductor integrated circuit including a differential amplifier circuit that eliminates the above drawbacks, reduces noise caused in differential signal lines, and operates stably.

(Structure of the Invention) A semiconductor integrated circuit of the present invention is a semiconductor integrated circuit including a differential amplifier circuit, in which two differential signal lines of the differential amplifier circuit are formed adjacent to each other in parallel, and It is constructed by arranging two wires that are short-circuited to each other using a low-resistance material.

(Example) Next, embodiments of the present invention will be described using the drawings.

FIG. 3 (al and bl are a plan view and a sectional view of an embodiment of the present invention.

In this embodiment, in a semiconductor integrated circuit including a differential amplifier circuit, two differential signal lines 8R and 8L of the differential amplifier circuit are formed adjacent to each other in parallel, and a low resistance material is placed on both outer sides of the two differential signal lines 8R and 8L. Two shorted wires 2R.

It is constructed by arranging 2L respectively.

To explain in more detail, the wiring 2R22L is formed of a conductor such as metal, for example, as shown in the figure.

All of the contacts 4 are short-circuited to each other by the low-resistance diffusion layer 3 and kept at the same potential. In this embodiment, the short circuit is made by the diffusion layer 3, but the short circuit may be made by other means. In short, it is important to maintain the same potential.

Note that IR and IL are signal lines, and 5 is a silicon oxide film.

6 is a protective film, and 7 is a silicon substrate.

In this embodiment, when the potential of the signal line IR is suddenly changed, noise is generated on the signal line 2R due to the capacitance formed between the signal line IR and 2R, but the signal line 2L is also at the same potential. Therefore, similar noise occurs in the differential signal lines 8R and 8L. Therefore, the differential value of the differential signal lines 8R and 8L does not change. The wirings 2R and 2T are not only arranged for shielding, but can also be used as normal signal lines, power supply lines, etc.

The wirings 2J to 2L do not significantly affect the increase in chip area as the pattern becomes finer, and can be added without adding any new process.

(Effects of the Invention) As described in detail above, according to the present invention, it is possible to obtain a semiconductor integrated circuit including a differential amplifier circuit that reduces noise caused in differential signal lines and operates stably.

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[Brief explanation of drawings]

Figures 1 (a) and (b) are a plan view and a cross-sectional view of an example of a conventional MO8 integrated circuit, Figure 2 is a circuit diagram of an example of a conventional differential amplifier circuit, and Figure 3 (a) and Φ). 1 is a plan view and a sectional view of an embodiment of the present invention. 1, IR, IL...signal line, 2...
Metal wiring layer (for constant potential source connection), 2R, ZL...
・Wiring, 3... diffusion layer, 4... contact, 5... silicon oxide film, 6... protective film, 7... silicon substrate , 8R18L...
...Differential signal line, D, D...Differential signal line, P...
...Precharge signal line, S...Start signal line. 6- (Kufu (17) Koto 2 Koku 255-

Claims (1)

[Claims] In a semiconductor integrated circuit including a differential amplifier circuit, two differential signal lines of the differential amplifier circuit are formed adjacent to each other in parallel, and two wirings are short-circuited to each other with a low resistance material on both outsides thereof. A semiconductor integrated circuit characterized in that each of these is arranged.