JP2001148462A - Semiconductor integrated circuit device and fuse-cutting device for cutting off fuse thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor integrated circuit, which is equipped with a metal fuse structure which is restrained from causing failure to it due to the fact that moisture penetrates through molding resin, when the defective bits of memory cells which form an LSI are substituted by redundant bits and a fuse-cutting device which cuts off the fuses of the same. SOLUTION: A redundant circuit is previously connected to another circuit via a fuse 3 formed of Al wiring, and when a normal circuit becomes partially defective, a defective circuit is replaced by a redundant circuit isolated by cutting off the fuse 3, to ensure a semiconductor integrated circuit device of normal operations, where the cut edge face of the cut fuse 3 is formed of an inactive compound 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor integrated circuit device and a fuse blow device for cutting a fuse of the semiconductor integrated circuit device. And a semiconductor integrated circuit device for ensuring normal operation by replacing a redundant circuit separated by cutting a metal fuse with a defective circuit when a normal circuit partially becomes defective. The present invention relates to a fuse cutting device for cutting a fuse of such a semiconductor integrated circuit device.

[0002]

2. Description of the Related Art In an LSI (Large Scale Integrated Circuit) in which a memory and a logic of multilayer wiring are integrated on one chip, a partial circuit failure may occur due to a defect in a manufacturing process. ) Often has a defective circuit (defective bit). Therefore, in order to replace this defective circuit, a redundant circuit (redundant bit) is provided in advance in the LSI. If a defective circuit is found by a test during the manufacturing process, the defective circuit is completely disconnected from the normal circuit by cutting a fuse connected to the defective circuit, and a redundant circuit is newly connected. Substitute.

In such a case, an Al (aluminum) wiring may be used as a fuse of a redundant circuit in a memory section. The reason for using the Al wiring is that it is necessary to completely sublimate the fuse with a laser and to perform stable cutting. For this purpose, an insulating film is present on the fuse and the thickness of the insulating film is reduced to 1000 nm or less. This is because it needs to be formed.

[0004] The cutting of the fuse is performed in the following process.
The fuse irradiated with the laser is heated to reach the boiling point of Al. As heating continues, the vapor pressure of Al increases,
Following the physical blow-off of the insulation on the fuse, the components of the fuse, including Al, evaporate. In this state, if packaging is performed while exposing the blown fuse, the remaining portion of the Al fuse is exposed to moisture penetrating the mold resin to form AlOH.

However, since AlOH containing water is gel-like and has electrical conductivity, the blown fuse is recombined, the defective circuit is restored, and the LSI may malfunction. Note that a fuse other than a metal fuse (for example, a fuse made of polysilicon) is stable against moisture and does not cause such a malfunction.

Therefore, in order to prevent such a malfunction, after the fuse is cut, an insulating film (SiN or SiO ₂ ) for preventing the penetration of moisture is subjected to CVD (Chemical Vapor D).
There is a means for depositing by eposition (chemical vapor deposition) method. In the process according to the prior art, as shown in FIG. 8, after patterning the uppermost Al wiring layer (Step S
101), an SiO ₂ film is deposited as an insulating film by a CVD method (Step S102), and a pad opening (Step S102) is formed.
The lot subjected to 103) is moved from the wafer process line to the wafer measurement line (step S10).
4).

On the wafer measurement line, after identifying the defective bit in the memory section (step S105), the fuse of the redundant circuit is cut to replace the defective bit with the redundant bit (step S106). At this time, gold that covers the stage surface of the tester or metal that falls from the prober adheres to the front and back surfaces of the wafer, and a large amount of Al dust generated when the probe rubs the pad is generated. Then, after the end of step S106, the wafer is transferred to the wafer process line (step S107), and these deposits and the like are removed (step S108).

Next, a passivation film (insulating protection film) is deposited by a CVD method so that the blown fuse does not come into contact with moisture penetrating from the outside (step S109).
After opening the pad again (step S110), the back surface of the wafer is ground (step S111), and the process moves to the next step (step S112). These steps S1
Steps 08 to S111 are performed in a wafer process line.

[0009]

However, in order to prevent the metal adhering to the wafer on the wafer measurement line from being brought into the wafer process line (step S108), it is necessary to completely remove the adhering matter. It is necessary to prepare a cleaning device or a dedicated device for processing a wafer returned from the measurement line.
Each of these cleaning equipment and dedicated wafer processing equipment requires a high cost for installation, and thus measures have been desired.

It is an object of the present invention to prevent a malfunction caused by a metal fuse from being caused by moisture permeating a molding resin when a defective bit of a memory cell constituting an LSI is replaced by a redundant bit. It is an object of the present invention to provide a semiconductor integrated circuit device having a fuse structure described above and a fuse cutting device for cutting a fuse of such a semiconductor integrated circuit device.

[0011]

In order to solve the above-mentioned problems, according to the present invention, a redundant circuit is connected in advance to another circuit via a metal fuse, and a normal circuit is partially defective. In the case of a circuit, a semiconductor integrated circuit device that secures normal operation by replacing the redundant circuit that is cut and separated by cutting the metal fuse with the defective circuit, wherein the cut end face of the metal fuse is It is characterized by being composed of an inert compound.

According to a second aspect of the present invention, the redundant circuit is connected in advance to another circuit via a metal fuse, and when the normal circuit partially becomes defective, the metal fuse is replaced. A semiconductor integrated circuit device which secures normal operation by replacing the redundant circuit cut and separated with the defective circuit, wherein a cut end face of the metal fuse and its periphery are covered with an insulating film. Features.

According to the first or second aspect of the present invention, the cut end face of the metal fuse is made of an inert compound, or the cut end face of the metal fuse and its periphery are covered with an insulating film. This prevents moisture from penetrating into the metal fuse and prevents the semiconductor integrated circuit device from malfunctioning.

According to a third aspect of the present invention, the redundant circuit is connected in advance to another circuit via a metal fuse, and when the normal circuit partially becomes defective, the metal fuse is replaced. A fuse cutting device for cutting a metal fuse of a semiconductor integrated circuit device which ensures normal operation by replacing the cut and separated redundant circuit with the defective circuit, wherein a portion of the metal fuse to be cut is cut by a laser. Laser light heating means for irradiating and heating with light, and passivation means for passivating the cut end surface of the metal fuse after being cut by heating with the laser light heating means are provided. Here, "passive" refers to a state in which the surface of the metal changes to a hydrated oxide to form a film and no corrosion occurs.

In the invention according to claim 3, it is preferable that the passivation means is a gas supply means for supplying a passivation gas to the cut end face of the metal fuse.

Further, in the invention according to claim 3, it is preferable that the passivating means is a film forming gas supplying means for supplying an insulating film forming gas to the cut end face of the metal fuse and the periphery thereof. It is.

According to the third aspect of the present invention, by providing the passivation means, the cut end face of the metal fuse is passivated. For example, the cut end face of the metal fuse is made of an inert compound. And it is possible to cover the cut end surface of the metal fuse and its periphery with an insulating film, so that moisture does not penetrate the metal fuse and prevent the semiconductor integrated circuit device from malfunctioning. Is done.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. FIG. 1 is a plan view showing the structure of the fuse according to the present embodiment, FIG. 2 is a sectional view of the fuse, FIG. 3 is a sectional view of the fuse after being cut by a fuse cutting device, and FIG. After that,
FIG. 5 is a cross-sectional view when the exposed portion of the fuse is passivated, and FIG. 5 is a cross-sectional view when the exposed portion of the fuse is covered with an insulating film after being cut by the fuse cutting device.

In this embodiment, a description will be given of a case where a defective portion of a memory is replaced with a normal circuit by a redundant circuit in an LSl in which a memory and a logic formed on a semiconductor wafer are integrated.

FIG. 1 is a plan view of a fuse according to the present embodiment. As shown in FIG. 1, a fuse 3 having a width of 1 μm
Are arranged in parallel at a pitch of 10 μm. A fuse window (opening portion) 4 having a width of 10 μm, which will be described below, overlaps a central portion in the longitudinal direction of the fuse 3.

One end of the fuse 3 is connected to a power supply line 5,
The other end is connected to a wiring 1 connected to a circuit for detecting a voltage via a plug 2, and an address to be replaced with a redundant fuse is selected according to a code written in a series of fuses 3. The thickness of the insulating film on the fuse 3 is 400 n.
Fuse window 4 for m to 1000 nm
Is located at the center of the fuse (described below).

FIG. 2 is a sectional view taken along the line II-II of FIG. 1 and shows a structure before the fuse is cut.

This embodiment relates to an LSI composed of four layers of Al wiring. As shown in FIG.
Is used for the third wiring layer 13. The fuse 3 to be cut by the laser needs to have the following structure. The structure is such that the fuse 3 has a thickness of 400 nm or more and 1
This structure is coated with SiO ₂ of 000 nm or less. In order to adjust the film thickness, the uppermost insulating film 15 in the fuse window 4 and a part of the fourth interlayer film 14 are etched.

FIG. 3 is a sectional view showing a state where the fuse shown in FIG. 2 has been cut by laser irradiation. The laser is focused to a spot size of 1 to 5 μm and illuminates fuse 3 via fuse window 4.
The temperature of the fuse (laminated film composed of Al and Ti) irradiated with the laser rises and Al reaches the boiling point. A reached boiling point
l, the SiO 2 existing above the fuse 3
₂ is blown off to form an opening 20. Al and Ti forming the fuse 3 evaporate into the atmosphere from the opening 20 and continue to be irradiated with the laser until the complete disconnection. At this time, the laser irradiation time is 1 to 20 ns, and the laser energy is 0.1 to 10 μJ.

The end face of the fuse 3 cut by the laser is in an exposed state. If the fuse 3 is simply covered with the mold resin as it is, it reacts with the permeated moisture as described in the conventional example, so that Al becomes gel-like AlOH. Changes to
This gel-like AlOH returns the blown fuse to its original bonded state.

FIG. 4 is a cross-sectional view showing the fuse after cutting shown in FIG. 3 in which the cut end face is changed to an inactive compound 21 such as an oxide film or a nitride film.

FIG. 5 is a cross-sectional view of the fuse after cutting shown in FIG. 3 in which the cut end and its periphery are covered with an insulating film 22 described below.

A main method for changing the end face of the blown fuse into an inert compound as shown in FIG. 4, or
The main method for covering with an insulating film as shown in FIG. 5 is as follows.

First Method The first method is a method of oxidizing or nitriding the end face of a fuse by heating by laser irradiation and oxygen and nitrogen in the atmosphere.

In this method, in the same pulse as that for cutting the fuse (pulse width is set to 5 ns or more), a method for inactivating the end face and a method for cutting the fuse in succession to the cutting process. Different low energy pulses (1μ
J or less) to deactivate the end face. In these methods, the fuse cutting device is provided with a power supply for controlling the pulse width and energy of the laser or an output control circuit for periodically varying the pulse width and energy of the laser.

Second Method A second method is a method of oxidizing an end face of a fuse by heating by laser irradiation and oxygen introduced by a nozzle (described below). In this method, the same pulse as that used to cut the fuse is used, following the cutting process.
There are a method of oxidizing the end face and a method of oxidizing the end face by using a pulse different from that for cutting the fuse.

Third Method A third method is to cover the end face of the fuse with an insulating film 22 by heating by laser irradiation and an insulating film-forming gas introduced by a nozzle. C for material of fuse 3
When u (copper) is used, since the compound of Cu does not have an appropriate passivation, it is inappropriate to use the first method and the second method, and use the third method. There is a need.

Although a CVD raw material is used as an insulator film forming gas, an inorganic material such as silane is not suitable for the structure of the apparatus because it has self-combustibility and corrosiveness. From the viewpoints described above and ease of handling (liquid at normal temperature), Si (OCH ₃ ) ₄ and Si (OC ₂ H ₅ ) ₄ are suitable among alkoxysilanes.

In this method, it is difficult to control the process of cutting the fuse and the process of forming the insulating film with the same pulse. Therefore, it is preferable to use a method using different pulses in each process.

FIG. 6 illustrates the second and third methods.
FIG. 3 is a diagram illustrating a configuration of a fuse cutting device. This fuse cutting device mainly includes a laser light source 32 for emitting a laser beam 30, a laser power supply 33 connected to the laser light source 32, and a laser beam 30 emitted from the laser light source 32.
An optical system comprising a mirror 31 for guiding the wafer 37 to the wafer 37, a gas supply device 34 for supplying a predetermined gas (an inactive gas or an insulator film forming gas) from the nozzle 34a to the surface of the wafer 37, and the wafer 37 being moved. The laser power supply 33, the gas supply device 34, and the stage 35 constituting these stages are controlled by a central control device 36, respectively.

FIG. 7 is a flowchart showing the operation of this embodiment. In FIG. 7, steps S1 to S3 are the same as steps S101 to S103 of the conventional example (FIG. 8), and then the back surface of the wafer is ground (step S4) and transferred to the wafer measurement line (step S5). . Then, step S7, step S
7 is the same as Steps S105 and S106 of the conventional example, and selects one of the first to third methods (Steps S8a to 8c) in Step S8. According to any of these methods, step S107 of the conventional example is used.
Step S1110 is unnecessary, and after step S8, it is possible to move to the next step (step S11).
9).

Therefore, as is apparent from a comparison between FIG. 8 and FIG. 7, according to the present invention, the above-described countermeasure against moisture permeation can be taken only one time between the wafer process line and the wafer measurement line. In addition, cleaning equipment and dedicated equipment are not required.

[0038]

As described above, according to the first aspect of the present invention, since the cut end surface of the metal fuse is made of an inactive compound, moisture permeates the metal fuse. As a result, a malfunction of the semiconductor integrated circuit device can be prevented, so that the reliability of the semiconductor integrated circuit device can be improved.

According to the second aspect of the present invention, since the cut end surface of the metal fuse and the periphery thereof are covered with the insulating film, moisture does not penetrate into the metal fuse, so that the semiconductor integrated circuit can be prevented. Since malfunction of the device can be prevented, reliability of the semiconductor integrated circuit device can be improved.

According to the third aspect of the present invention, since the fuse cutting device is provided with the passivation means, the cut end face of the metal fuse can be passivated. Moisture does not penetrate, and malfunction of the semiconductor integrated circuit device can be prevented. Therefore, reliability of the semiconductor integrated circuit device can be improved. Further, after the wafer is moved from the wafer process line to the measurement process line for circuit correction, it is not necessary to return the wafer to the wafer process line again, so that the process can be simplified. Furthermore, there is no need to prepare a facility for removing the deposits or a dedicated device that satisfies the pollution standard, so that capital investment can be reduced.

[Brief description of the drawings]

FIG. 1 is a plan view of a fuse according to an embodiment of the present invention.

FIG. 2 is a sectional view of the fuse according to the first embodiment before cutting;

FIG. 3 is a cross-sectional view after the fuse is cut by the fuse cutting device according to the first embodiment;

FIG. 4 is a cross-sectional view when the exposed portion of the fuse is passivated after being cut by the fuse cutting device according to the first embodiment;

FIG. 5 is a cross-sectional view when the exposed portion of the fuse is passivated after being cut by the fuse cutting device of the fuse according to the embodiment;

FIG. 6 is a diagram showing a configuration of a fuse cutting device according to the embodiment of the present invention.

FIG. 7 is a flowchart of a process according to the embodiment of the present invention.

FIG. 8 is a flowchart of a process of a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... wiring to a voltage detection circuit, 2 ... plug, 3 ... fuse, 4 ... fuse window, 5 ... power supply line, 10 ... S
i-substrate, 11 ... first interlayer film, 12 ... second interlayer film, 13 ...
Third interlayer film, 14 ... fourth interlayer film, 15 ... uppermost insulating film,
16: Fuse connection wire, 17: Fuse connection plug, 20: Opening, 21: Inactive compound, 22: Insulating film, 30: Laser beam, 31: Mirror, 32: Laser light source, 33: Laser power source, 34 ... gas supply device, 35 ...
Stage, 36: Central control unit, 37: Wafer.

Claims (5)

[Claims] 1. A redundant circuit in which a redundant circuit is connected in advance to another circuit via a metal fuse, and when the normal circuit partially becomes defective, the redundant circuit is cut and separated. A semiconductor integrated circuit device which secures normal operation by substituting the defective circuit with the defective circuit, wherein a cut end face of the metal fuse is made of an inactive compound. 2. The redundant circuit according to claim 1, wherein the redundant circuit is connected in advance to another circuit via a metal fuse, and when the normal circuit becomes partially defective, the metal fuse is cut and separated. A semiconductor integrated circuit device which secures normal operation by substituting the defective circuit with the defective circuit, wherein a cut end surface of the metal fuse and its periphery are covered with an insulating film. 3. The redundant circuit according to claim 1, wherein the redundant circuit is connected in advance to another circuit via a metal fuse, and when the normal circuit becomes partially defective, the metal fuse is cut and separated. A fuse cutting device that cuts the metal fuse of the semiconductor integrated circuit device that ensures normal operation by substituting the defective circuit with the defective circuit, and irradiates and heats a portion of the metal fuse to be cut with laser light. Means, and a passivation means for passivating a cut end face of the metal fuse after being cut by heating with the laser light heating means. 4. The fuse cutting device according to claim 3, wherein said passivation means is gas supply means for supplying a passivating gas to a cut end face of said metal fuse. 5. The method according to claim 3, wherein the passivating means is a film forming gas supplying means for supplying an insulating film forming gas to the cut end face of the metal fuse and the periphery thereof.
The fuse cutting device according to the above.