JPH10135340A - Redundant circuit of semiconductor integrated circuit and method of testing blowing of redundant circuit fuse - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a redundant circuit of a semiconductor integrated circuit and method of testing blowing of a redundant circuit fuse whereby all redundant circuit fuses can be tested about their blow conditions, without increasing the test time and labor. SOLUTION: A redundant circuit has a fuse wiring 1 to be blown by a laser and wiring 2 for detecting the abnormal blow, running parallel to the fuse wiring 1 which is about 1μm width while a laser beam spot diameter is about 6μm and the space between the fuse wiring 1 and detecting wiring is about 40-5μm. When the fuse wiring is blown with a blow deviation, the laser beam spot is wide beyond necessity, or laser energy is high beyond necessity, the detecting wiring 2 is also broken to be electrically open between terminals 2a, 2b of the detecting wiring 2. Thus, the electrical connection of the detecting wiring 2 is measured to detect an abnormal blow of the fuse wiring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a redundant circuit of a semiconductor integrated circuit and a method for inspecting a fuse of a redundant circuit.

[0002]

2. Description of the Related Art Conventionally, a semiconductor integrated circuit is provided with a redundant circuit that is electrically replaced with a defective bit, and the redundant circuit is activated by cutting a redundant circuit fuse with a laser. In addition, when inspecting the cutting state of the redundant circuit fuse, the inspector visually judges a cutting abnormality such as a cutting deviation using a microscope or the like.

[0003]

However, when all of the redundant circuit fuses are visually inspected for disconnection status as in the prior art, the inspection time becomes long and a large number of personnel are required. On the other hand, if all the cut states of the redundant fuses are not inspected, the redundant circuit fuses may not be cut in a normal state, which may adversely affect the yield and reliability. Therefore, the present invention
It is an object of the present invention to provide a redundant circuit of a semiconductor integrated circuit and a method of inspecting the disconnection of the redundant circuit fuse, which can easily inspect all the disconnection states of the redundant circuit fuses without increasing the inspection time and personnel.

[0004]

According to a first aspect of the present invention, there is provided a redundant circuit for a semiconductor integrated circuit, which operates when a redundant circuit fuse is cut by a laser. In the circuit, a detection wiring for measuring electrical continuity is formed near a cut region of the redundant circuit fuse. In a redundant circuit of a semiconductor integrated circuit according to a second aspect, in the redundant circuit of the semiconductor integrated circuit according to the first aspect, the detection wiring is formed at least on one side in parallel with the redundant circuit fuse. .

According to a third aspect of the present invention, in the redundant circuit of the semiconductor integrated circuit according to the first aspect, the detection wiring is formed on at least one side of the cut region so as to be orthogonal to the redundant circuit fuse. It is characterized by having been done. According to a fourth aspect of the present invention, in the redundant circuit of the semiconductor integrated circuit according to the first aspect, the detection wiring is formed around the cutting region. A redundant circuit fuse disconnection inspection method according to claim 5, wherein the redundant circuit fuse disconnection inspection method for inspecting a disconnected state of a redundant circuit fuse cut by a laser in order to operate a redundant circuit of a semiconductor integrated circuit. A detection wiring is formed in the vicinity of the cut region of the circuit fuse, and electrical continuity between the terminals of the formed detection wiring is measured after the redundant circuit fuse is cut,
If the terminals are electrically open, it is determined that a disconnection abnormality has occurred in the redundant circuit fuse.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a redundant circuit of a semiconductor integrated circuit and a method for inspecting the disconnection of a redundant circuit fuse according to the present invention will be described. FIG. 1 is a diagram showing a detection wiring formed in parallel with a fuse wiring of a redundant circuit according to the embodiment. In the redundant circuit, a fuse wiring 1 cut by a laser (not shown) and a detection wiring 2 used to detect a cutting abnormality are formed in parallel with the fuse wiring 1. In the present embodiment, the line width of the fuse wiring 1 is about 1 μm, and the diameter of the laser beam spot is about 6 μm.
μm, and the distance between the fuse wiring 1 and the detection wiring 2 is about 4 to 5 μm. Therefore, fuse wiring 1
Is normally performed within the range of the cutting region 8 by the laser, only the fuse wiring 1 can be cut without involving the detection wiring 2.

FIG. 2 is a diagram showing a case where a disconnection occurs when the fuse wiring shown in FIG. 1 is cut by a laser.
When a cutting shift occurs on the right side of the drawing, the detection wiring 2 is also cut at the same time and the terminals 2a and 2b of the detection wiring 2 are electrically opened, so that the electrical continuity of the detection wiring 2 is measured. Thus, the disconnection abnormality of the fuse wiring 1 is detected. FIG. 3 is a view showing a case where the detection wiring is cut without causing a cutting shift when the fuse wiring shown in FIG. 1 is cut by a laser. If the laser beam spot is wider than necessary, or if the laser energy is stronger than necessary, the detection wiring 2 will be cut even if there is no deviation in the cutting center position. Also in this case, the detection wiring 2
Between the terminals 2a and 2b is electrically opened, and the disconnection of the fuse wiring 1 is detected by measuring the electrical continuity of the detection wiring 2.

On the other hand, when the fuse wiring 1 is normally cut by the laser, the detection wiring 2 is not cut, and the terminals 2a and 2b of the detection wiring 2 remain electrically short-circuited. By measuring the electrical continuity of the detection wiring 2, it is detected that the fuse wiring 1 has been cut normally. In this way, by measuring the electrical continuity between the terminals 2a and 2b of the detection wiring 2 formed in parallel with the fuse wiring 1, the cut state of the fuse wiring 1 can be easily inspected. Therefore, it is not necessary to visually inspect the cut state of the fuse wiring using a microscope as in the conventional case, and the work efficiency can be improved. In particular, it is possible to construct a system for automatically measuring the continuity between the terminals of the detection wiring and inspecting the disconnection state of the fuse wiring, thereby easily adding a redundant circuit fuse without increasing the inspection time and personnel. The entire cutting state can be inspected.

Incidentally, the detection wiring 2 can be formed in the same step as that of the fuse wiring 1. In this case, the detection wiring 2 can be easily formed. [Other Embodiments] FIG. 4 is a diagram showing a detection wiring formed in parallel with the fuse wiring on the side opposite to FIG.
If the detection wiring 12 is formed on the left side of the fuse wiring 11 in the figure, the disconnection of the detection wiring 12 is measured by measuring the electrical continuity of the detection wiring 12 after the fuse wiring 11 is cut by the laser. Can be detected. FIG. 5 is a diagram showing detection wires formed in parallel on both sides with respect to the fuse wires. In this case, by measuring the electrical continuity between the terminals 22a and 22b of the detection wiring 22 and measuring the electrical continuity between the terminals 23a and 23b of the detection wiring 23, the disconnection of the fuse wiring 21 can be prevented. In particular, left and right cutting deviations can be reliably detected.

FIG. 6 is a diagram showing a detection wiring formed above the cutting region so as to be orthogonal to the fuse wiring. By measuring the electrical continuity between the terminals 62 a and 62 b of the detection wiring 62, it is possible to detect a disconnection abnormality of the fuse wiring, particularly, a disconnection of the fuse wiring above the cutting region 68. FIG. 7 is a diagram showing a detection wiring formed below the cutting region so as to be orthogonal to the fuse wiring. Terminal 72 of detection wiring 72
By measuring the electrical continuity between a and 72b, it is possible to detect a disconnection abnormality of the fuse wiring, particularly a disconnection of the disconnection to the lower side of the disconnection region 78.

FIG. 8 is a diagram showing detection wirings formed above and below the cutting region so as to be orthogonal to the fuse wirings. Measuring the electrical continuity between the terminals 82a and 82b of the detection wiring 82;
By measuring the electrical continuity between 3a and 83b, it is possible to detect a disconnection abnormality of the fuse wiring 81, particularly a disconnection of the disconnection to the upper side and the lower side of the cut region 88. 6 and 7,
The detection wiring shown in FIG. 8 can be formed integrally with the fuse wiring. In this case, the detection wiring can be easily formed. FIG. 9 is a diagram showing the detection wiring formed around the inside of the cutting area. Terminals 92 of the detection wiring 92 continuously formed in a substantially rectangular shape along the inside of the cutting region 98
By measuring the electrical continuity between a and 92b, the disconnection abnormality 91 of the fuse wiring can be detected. In particular, a cutting abnormality can be reliably detected regardless of the direction in which the cutting deviation occurs.

FIG. 10 is a diagram showing a plurality of detection wirings formed around the inside of the cutting area. Detection wiring 102,
103, 104, and 105 are formed at the upper, lower, left, and right portions of the cutting region 108, and by measuring the electrical continuity between the terminals, it is possible to detect the cutting abnormality of the fuse wiring 101 and to detect the cutting displacement. It is possible to specify the direction when the error occurs. In each of the embodiments described with reference to the drawings, the normal cutting region is not covered with the passivation film (the insulating film 3 in FIG. 1).
The detection wiring and the fuse wiring are insulated from each other by an insulating film.

[0013]

According to the redundant circuit of the semiconductor integrated circuit according to the first aspect of the present invention, in the redundant circuit of the semiconductor integrated circuit which operates when the redundant circuit fuse is cut by the laser, the cut region of the redundant circuit fuse is provided. The detection wiring for measuring the electrical continuity was formed in the vicinity, so after cutting the redundant circuit fuse with the laser, the disconnection of the redundant circuit fuse could be easily detected by measuring the electrical continuity of the detection wiring. Can be detected. Therefore, it is not necessary to visually detect an abnormal disconnection of the redundant circuit fuse using a microscope as in the related art, and the work efficiency can be improved. In particular, it is possible to construct a system for automatically measuring the electrical continuity of the detection wiring and inspecting the disconnection state of the redundant circuit fuse, without increasing the inspection time and personnel.
It is possible to easily inspect all cuts of the redundant circuit fuses.

According to the redundant circuit of the semiconductor integrated circuit according to the second aspect, since the detection wiring is formed at least on one side in parallel with the redundant circuit fuse, it is generated in parallel with the redundant circuit fuse. Cutting displacement can be reliably detected. Further, the detection wiring can be formed in the same step as the redundant circuit fuse. According to the redundant circuit of the semiconductor integrated circuit according to claim 3, since the detection wiring is formed on at least one side of the cutting region so as to be orthogonal to the redundant circuit fuse, the side orthogonal to the redundant circuit fuse is provided. Can be detected reliably.
Further, the detection wiring can be formed integrally with the redundant circuit fuse, and the detection wiring can be easily formed.

According to the redundant circuit of the semiconductor integrated circuit according to the fourth aspect, since the detection wiring is formed around the cutting region, the cutting abnormality can be reliably detected regardless of the cutting displacement in any direction. it can. According to the method for inspecting the disconnection of a redundant circuit fuse according to claim 5, in the method of inspecting the disconnection of a redundant circuit fuse cut by a laser for operating a redundant circuit of a semiconductor integrated circuit, A detection wiring is formed in the vicinity of the cut region of the redundant circuit fuse, and electrical continuity between terminals of the formed detection wiring is measured after the redundant circuit fuse is cut. If it is opened to, since it is determined that a disconnection abnormality has occurred in the redundant circuit fuse, after cutting the redundant circuit fuse by laser,
By measuring the electrical continuity of the detection wiring, the disconnection abnormality of the redundant circuit fuse can be easily detected.

[Brief description of the drawings]

FIG. 1 is a diagram showing a detection wiring formed in parallel with a fuse wiring of a redundant circuit in an embodiment.

FIG. 2 is a diagram showing a case where a disconnection occurs when the fuse wiring shown in FIG. 1 is cut by a laser.

FIG. 3 is a diagram showing a case where the detection wiring is cut without causing a cutting shift when the fuse wiring shown in FIG. 1 is cut by a laser.

FIG. 4 is a diagram showing a detection wiring formed in parallel with the fuse wiring on the opposite side of FIG. 1;

FIG. 5 is a diagram showing detection wires formed in parallel on both sides with respect to the fuse wires.

FIG. 6 is a diagram showing a detection wiring formed above a cutting region so as to be orthogonal to a fuse wiring.

FIG. 7 is a diagram showing a detection wiring formed below a cutting region so as to be orthogonal to the fuse wiring.

FIG. 8 is a diagram showing detection wirings formed above and below a cutting region so as to be orthogonal to fuse wirings.

FIG. 9 is a diagram showing a detection wiring formed around the inside of a cutting area.

FIG. 10 is a diagram showing a plurality of detection wires formed around the inside of a cutting region.

[Explanation of symbols]

1, 11, 21, 61, 71, 81, 91, 101 Fuse wiring 2, 12, 22, 23, 62, 72, 82, 83, 9
2,102,103,104,105 Wiring for detection 8,68,78,88,98,108 Cutting area

Claims (5)

[Claims] 1. A redundant circuit of a semiconductor integrated circuit which operates when a redundant circuit fuse is cut by a laser, wherein a detection wiring for measuring electrical continuity is formed near a cut region of the redundant circuit fuse. A redundant circuit for a semiconductor integrated circuit, comprising: 2. The redundant circuit of a semiconductor integrated circuit according to claim 1, wherein said detection wiring is formed at least on one side in parallel with said redundant circuit fuse. 3. The redundant circuit of a semiconductor integrated circuit according to claim 1, wherein said detection wiring is formed on at least one side of said cut region so as to be orthogonal to said redundant circuit fuse. 4. The redundant circuit of a semiconductor integrated circuit according to claim 1, wherein said detection wiring is formed around said cutting region. 5. A redundant circuit fuse disconnection inspection method for inspecting a disconnected state of a redundant circuit fuse cut by a laser for operating a redundant circuit of a semiconductor integrated circuit, comprising: Wiring is formed, and electrical continuity between terminals of the formed detection wiring is measured after cutting the redundant circuit fuse. If the terminals are electrically open, the redundant circuit fuse is For inspecting the disconnection of a redundant circuit fuse for determining that a disconnection abnormality has occurred in a fuse.