JPS6216546B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor integrated circuit device, and more particularly to a structure of fuse wiring connecting redundant circuits in a semiconductor integrated circuit device having redundant circuits.

In semiconductor memories such as RAM, ROM, or PROM, redundant circuits consisting of extra cell lines, etc. are provided, and the redundant circuits are connected to the common wiring layer by fuse wiring that can be blown by energizing, and as needed. A method is often used in which redundant circuits are separated from the common wiring layer.

The fuse wiring was conventionally made of nichrome (Ni-
Cr) or conductive polysilicon, but in order to fuse these resistor films, the temperature of the resistor film must be raised to at least 1500 [℃] or higher. Therefore, the self-heating current for fusing becomes extremely large. Therefore, in the conventional fuse wiring described above, a structure is adopted in which the width of the part to be fused is formed as narrow as possible, that is, about 1 [μm], to limit the fusing current, but the fusing current is still quite large. If the width is about [μm], the width will vary greatly from the viewpoint of processing accuracy, so in order to completely blow out such fuse wiring, a voltage of 10 to 15 [V] and a current of 10 ~number
A high output transistor of about 100 [mA] must be specially provided. Since such high-output transistors require a very large dedicated area, there is a problem in that peripheral circuits such as semiconductor memories become large and the degree of integration of the semiconductor integrated circuit device is reduced.

Furthermore, the fuse wiring made of the nichrome film is very troublesome to form, and the fuse wiring made of the polysilicon film has a problem that the fused surface is not very clean and the reliability of the fused state is poor.

In view of the above-mentioned problems, the present invention is easy to form, can be easily blown by a single power supply of about 5 [V] of a semiconductor integrated circuit without providing particularly high-output transistors, and has high reliability in the blown state. Provided is a semiconductor integrated circuit device having high fuse wiring.

That is, the present invention provides a semiconductor integrated circuit device that includes:
It has a fuse wiring made of a polysilicon pattern and a metal layer directly in contact with the polysilicon pattern, and is characterized in that the fuse wiring is cut by generating an alloying effect between the polysilicon pattern and the fuse wiring. do.

The present invention will be explained in detail below with reference to illustrated embodiments.

FIG. 1 is an explanatory diagram of a redundant circuit structure, FIG. 2a is a top view of one embodiment of the fuse wiring of the present invention, and FIG. 2b is a sectional view of the same.

For example, in a semiconductor memory having a redundant circuit, a bit line 1 and a plurality of cell lines 2a, 2b, 2c, 2d, etc. are connected by fuse wiring 3a, 3b, 3c, 3d, etc., as shown in FIG. The structure is such that the cell line is provided with transistors 4a, 4b, 4c, 4d, etc. for supplying fusing current of the fuse wiring, whose source or drain is connected to the cell line and the other is grounded. There is. Then, when cutting off the bit line and cell line, the fusing current supply transistor attached to the desired cell line is activated.
A current is passed between the bit line and the ground via the fuse wire and the transistor to blow out the fuse wire.

The structure of the fuse wiring of the present invention is, for example, as shown in FIGS. 2a and 2b, an insulator such as phosphosilicate glass (PSG) formed on the surface of a semiconductor integrated circuit board 5 on which element formation has been completed. Thickness deposited on the film 6 at intervals of about 2 to 3 [μm], for example.
2000~3000 [Å], width ~3 [μm], length 10 [μm]
2 [pieces] of polysilicon patterns 7a of about [m]
and 7b, a layer having a width W of about 2 to 3 [μm] is deposited on the insulating film 6 in direct contact with these polysilicon patterns and integrally with the bit line 1 and cell line 2. It consists of an aluminum wiring layer 8.

Next, an example of a method for forming a fuse wiring having the structure of the present invention will be explained using FIGS. on the integrated circuit board 5
A polysilicon film with a thickness of about 2000 to 3000 [Å] is deposited by a method such as CVD, and after selectively removing the polysilicon film to form polysilicon patterns 7a and 7b at desired locations, Windows for wiring contacts to various functional elements formed on the substrate are formed in the film 6, and then an aluminum (Al) wiring layer with a thickness of approximately 0.5 to 1.0 [μm] is coated on the insulating film 6. Perform dressing formation. At this time, the Al wiring layer 8 of the cell line 2 is narrowed to a width of about 2 to 3 [μm], passes over the polysilicon patterns 7a and 7b, and is in direct contact with the polysilicon patterns. Patterning is performed so as to connect to the Al wiring layer of bit line 1.

In the fuse wiring having the structure of the present invention, migration of aluminum occurs at a temperature of around 420 [°C], but at temperatures around this temperature, a unique reaction between aluminum and polysilicon occurs at the interface, and the polysilicon Aluminum enters inside and alloying occurs. As the aluminum becomes thinner due to this alloying, the temperature further increases and alloying at the interface progresses. By repeating this process, the upper aluminum wiring layer is rapidly eaten into the polysilicon pattern, so that the fuse wiring can be completely blown out or made non-conductive at a temperature of 600 degrees Celsius or less. Therefore, the voltage required to blow the fuse wiring or make it non-conducting is sufficient to be around 5 [V], which is the single power supply voltage of a semiconductor integrated circuit, and the current is not more than a few [mA]. Therefore, the output of the fusing current supply transistor can be significantly reduced compared to the conventional one, and the area dedicated to the transistor can therefore be significantly reduced. In addition, the fuse wiring of the present invention can be melted or made non-conductive by alloying at the interface as described above.
Since this is done by the reaction mechanism of temperature rise due to thinning of the wire, the wire can be cut reliably in a short time and the reliability of the cutting state is extremely high.

In the above embodiment, the structure of the fuse wiring of the present invention was explained as an example in which an aluminum wiring layer is deposited on a polysilicon pattern. It's okay to use it.

When the deposited wiring layer is made of aluminum, in addition to the effect of reducing the fusing current due to alloying of the present invention, the effect of migration of aluminum is added, so fusing can be performed at a lower current than in the case of alloying alone. becomes.

Further, the fuse wiring structure of the present invention can be applied to the disconnection of redundant circuits and elements other than the above embodiments.

Furthermore, in the above embodiment, an example was explained in which a polysilicon pattern for fuse wiring is newly deposited on an insulating film formed on the surface of a semiconductor integrated circuit board on which element formation has been completed. The pattern is formed at a desired location at the same time as the gate electrode of the transistor is formed, and after the formation of the upper insulating film is completed, a window is formed in the insulating film at the position of the polysilicon pattern, and the polysilicon pattern is formed. If the metal wiring layer is formed on the exposed pattern, the number of steps can be reduced and it is more effective.

As explained above, the fuse wiring of the present invention can greatly reduce the area occupied by the transistor for supplying the blowing current for cutting the fuse, and the cutting can be done easily and reliably, so that it can be used in semiconductor integrated circuits. This is extremely effective in increasing the degree of integration and reliability of devices.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a redundant circuit structure, FIG. 2a is a top view of one embodiment of the fuse wiring of the present invention, and FIG. 2b is a sectional view of the same. In the figure, 1 is a bit line, 2a, 2b,
2c, 2d are cell lines, 3a, 3b, 3c, 3
d is a fuse wiring; 4a, 4b, 4c, and 4d are transistors for supplying blowing current; 5 is a semiconductor integrated circuit board; 6 is an insulating film; 7a and 7b are polysilicon patterns; and 8 is an aluminum wiring layer.

Claims (1)

[Scope of Claims] 1. Fuse wirings 3a to 3d made of polysilicon patterns 7a, 7b and a metal layer 8 in direct contact with the polysilicon patterns 7a, 7b, wherein the polysilicon patterns 7a, 7b and the fuse wirings By generating an alloying action between 3a and 3d,
A semiconductor integrated circuit device characterized in that the fuse wirings 3a to 3d are cut.