Active solid-state devices (e.g. – transistors – solid-state diode – Integrated circuit structure with electrically isolated... – Passive components in ics
Reexamination Certificate
1997-12-03
2001-03-20
Saadat, Mahshid (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Integrated circuit structure with electrically isolated...
Passive components in ics
C257S209000, C257S211000
Reexamination Certificate
active
06204548
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains to a fuse installed in a wiring pattern on a semiconductor substrate and in particular, pertains to a semiconductor device fuse used in circuit installation such as that cut by irradiation of an appropriate laser in accordance with the results of an operation check in a manufacturing process, cut-off of an inferior circuit, and operation of an auxiliary circuit.
BACKGROUND OF THE INVENTION
A semiconductor device fuse is installed in a wiring pattern to check the operation, etc., of a circuit at the wafer stage during the manufacture of a semiconductor device and to appropriately set and correct the circuit in accordance with the results, and operation of the circuit is prevented or a redundant circuit is operated by cutting part of the fuse.
Such a semiconductor device fuse is formed in a strip shape with a prescribed width, and in order to electrically cut the fuse, in general, it is partially thermally melted and evaporated by irradiating a laser beam at a prescribed position.
Such a laser beam irradiates the surface of the semiconductor substrate, however it is known that if a pulsed laser beam irradiates many fuses of a semiconductor device, the lower layer of the semiconductor device fuses is damaged at a prescribed rate. In such a case, if a semiconductor electric element is formed at the position directly under the semiconductor device fuses, the entire product is deteriorated.
According to the conventional technique, when many semiconductor device fuses installed in the semiconductor device, they are arranged together in one fuse region, and no semiconductor electric element is formed under each semiconductor device fuse, which is an ineffective region. Thus, even in case damage occurs, the generation of an inferior product is prevented, and the cutting workability of the semiconductor device fuses is improved.
However, recently, along with improvements in the degree of integration of semiconductor devices, the internal circuit has been made larger in scale and complicated, and the number of semiconductor device fuses required to set and correct the circuit has also increased. On the other hand, since the size of semiconductor device fuses is determined by the spot diameter of a laser beam and the precision of an irradiated position, the circuit cannot be reduced to smaller scale, and the ineffective region generated in the above-mentioned conventional technique increases to the degree that it cannot be ignored.
The present invention considers the above-mentioned problems, and its objective is to provide a semiconductor device fuse, which can form an electrical element and an interlayer wiring film without damaging its lower layer when it is cut by irradiation with a laser beam.
SUMMARY OF THE INVENTION
The inventor of the present invention researched the shape of fuses, and as a result, it was discovered that a semiconductor fuse could be reliably melted and evaporated by irradiation with a laser beam without damaging its lower layer.
The present invention is created based on the above-mentioned knowledge, and is characterized by the fact that a semiconductor fuse characterized by having a narrow-width part and a cut part formed by patterning an electronconductive thin film installed on a semiconductor substrate and in which the above-mentioned cut part is connected via the above-mentioned narrow-width part to an electrical element formed on the semiconductor substrate, the above-mentioned cut part is formed in a shape wherein part of the laser beam, which cannot be blocked by the above-mentioned narrow-width part, can also be blocked, when the above-mentioned laser beam irradiates the above-mentioned narrow-width part; that when the above-mentioned laser beam irradiates, the electrical connection is opened.
With such a constitution, the part of the laser beam with a strong intensity, which damages the lower layer, reliably irradiates the semiconductor device fuse, so that it does not irradiate the thin film of its lower layer. As a result, damaging the semiconductor substrate and the thin layer of the lower layer is prevented.
In order for the laser beam not to be overshot, a detailed planar shape of the cut part of the semiconductor device fuse, as shown in the invention, may have an expanding part.
In the semiconductor device fuse described it is effective for the envelope shape of the above-mentioned expanding part to have a shape that fits the cross section shape of the above-mentioned laser beam.
In general, the cross section shape of the laser beam is circular. Therefore, in the semiconductor device fuse described, the envelope shape of the above-mentioned expanding part is preferably circular.
Since the invention described is equipped with the semiconductor device fuse described, a semiconductor electrical element can be installed at the position directly under it, and the ineffective region disappears, so that the size of the chips can be reduced.
Also, as for the semiconductor device equipped with several semiconductor device fuses, as in the invention described, when the above-mentioned cut parts of the mutually adjacent semiconductor device fuses are arranged, if they are controlled not to be arranged in one horizontal column, the cut parts do not cause problem when the semiconductor device fuses become closer to each other, which is favorable for the reduction of the size of chips.
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patent: 4630355 (1986-12-01), Johnson
patent: 5025300 (1991-06-01), Billig et al.
patent: 5420455 (1995-05-01), Gilmour et al.
patent: 5608257 (1997-03-01), Lee et al.
patent: 5872389 (1999-02-01), Nishimura et al.
patent: 5986319 (1999-11-01), Huggins
patent: 5986321 (1999-11-01), Froehner
Eckert II George C.
Petersen Bret J.
Saadat Mahshid
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
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