JP3186744B2 - Semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device having a fuse element forming a part of a redundant circuit, and more particularly, to a fuse element even when an energy beam for blowing the fuse element is misaligned. The present invention relates to a semiconductor device capable of reliably fusing.

[0002]

2. Description of the Related Art A semiconductor device is known which includes a main circuit such as a memory circuit and a redundant circuit for protecting the main circuit. This redundant circuit is composed of 1
When a defective element is generated in a chip, the fuse element at an address corresponding to the defective element is blown by a laser beam, thereby switching the defective element to a normal element.

FIG. 13 shows a fuse element of a conventional semiconductor device.
A description will be given with reference to FIGS.

In each of the drawings, a silicon oxide film 102 is formed on a silicon substrate 100, and a fuse element 104 made of a polycrystalline silicon film is formed thereon by utilizing a part of the pattern of a wiring layer. . Both ends of the fuse element 104 covered with the silicon oxide film 106 are connected to an aluminum wiring 110 via a contact hole 108. Then, the fuse element 104
Is performed by irradiating the fuse element 104 with a laser beam 112 as shown in FIG. 13A, thereby causing the fuse element 104 to generate heat.

[0005]

The misalignment of the laser irradiating device is caused as a cause of the erroneous blow of the fuse element 104. In general, it is said that an alignment device used for a laser irradiation device is not as accurate as a stepper in an exposure device, and has an alignment accuracy of about 1 μm for a fuse element 104 having a width of 2 μm.

[0006] The fuse element 1 is
04 is required to be blown by the fuse element 10
4 means that the entire wiring width is within the beam diameter. However, if even a part of the wiring width of the fuse element 104 deviates from within the beam diameter due to misalignment, the fuse element 104 cannot be opened any more, resulting in a fusing mistake.

[0007] Even when the entire wiring width of the fuse element 104 is within the beam diameter, a fusing mistake occurs. this is,
This is due to the energy distribution of the laser beam. This energy distribution is as shown in FIG. 11, and as the distance x from the beam center increases, the energy density of the laser beam decreases. Therefore, as the center of the laser beam deviates from the center of the fuse element 104 due to misalignment, the amount of energy contributing to fusing decreases, and a fusing mistake occurs.

A first problem to which the present inventor has paid attention is to reliably eliminate a fusing error of a fuse element caused by misalignment.

It is considered that such fusing mistakes increase more and more as the miniaturization of semiconductor devices advances rapidly. This is because the thickness of the fuse element 104 must be reduced with the miniaturization of the semiconductor device, and the absorbed energy decreases as the thickness decreases.

If the laser beam 112 is misaligned with respect to the thin film fuse element 104, factors that hinder the fuse element 104 from being blown will overlap, and the number of blowout errors will further increase. The second that the inventor focused on
An object of the present invention is to surely blow a fuse element which tends to become thinner.

The following publications disclose techniques relating to the fusing of the fuse element, but do not take any measures against the fusing error caused by the misalignment and the thinning of the fuse element.

Japanese Patent Application Laid-Open No. 61-51966 discloses a technique in which a shock absorbing layer made of a polycrystalline silicon film is provided below a fuse element. In this way, even if the fuse element 104, which tends to be thinned by increasing the output of the laser beam, is blown, an adverse effect on the silicon substrate can be prevented. However, if the laser irradiation device is misaligned, it is impossible to reliably blow the fuse element. The shock absorbing layer made of the polycrystalline silicon film only absorbs the beam transmitted through the fuse element.

Japanese Patent Application Laid-Open No. Sho 58-640610 discloses a technique in which a coating having high light absorption is provided above a fuse element. Also, JP-A-60-17625 discloses that
A technique is disclosed in which a window for exposing the fuse element is provided above the fuse element.

[0014] In these two techniques, only when the fuse element exists within the beam diameter, it is only possible to secure a relatively high incident energy, and there is no measure against alignment misalignment.

JP-A-58-207665 describes that V
A technique for forming a fuse element along a letter-shaped groove is disclosed. According to this technique, the fuse element is melted and flows along the V-shaped groove at the time of laser beam irradiation, so that it is possible to blow the fuse with relatively low power. However, no measure is taken when the laser beam is misaligned in the width direction of the fuse element.

It is an object of the present invention to provide a semiconductor device which can reliably blow a fuse element even when a laser irradiation device is misaligned.

Another object of the present invention is to provide a semiconductor device capable of reliably blowing a fuse element without significantly increasing the output of a laser beam, even if the thickness of the fuse element is reduced by miniaturization of the element. It is to provide a device.

Another object of the present invention is to reliably blow the fuse element even when the double bad conditions of thinning the fuse element and misalignment of the laser irradiation device overlap. It is to provide a semiconductor device.

[0019]

According to the present invention, there is provided a semiconductor device comprising:
A semiconductor device having a fuse element that can be blown by a laser beam, wherein the fuse element includes a first fuse element formed above a substrate, and an interlayer insulating film formed above the first fuse element. And a second fuse element formed above the interlayer insulating film,
The first fuse element is formed by serially connecting fuse wiring layers provided in a plurality of columns at intervals in a wiring width direction, and the second fuse element is formed by connecting the fuse wiring layers adjacent to each other. It is formed above the space formed between the layers and opposite to the space between the layers, and is connected to the first fuse wiring layer via a contact hole.

[0020]

[0021]

[0022]

[0023]

The misalignment of the laser irradiation device occurs in all directions, but particularly when the laser beam deviates from the wiring width of the fuse element, the fuse element can no longer be blown. In the first invention, since the fuse wiring layers are provided in a plurality of rows at intervals in the wiring width direction (that is, folded in a plurality of times in parallel), even if the laser beam is shifted particularly in the wiring width direction, Any one of the fuse wiring layers can always be positioned within the beam diameter of the laser beam, and reliable fusing can be achieved. Since the fuse wiring layers in each column are connected in series, it is possible to always open the fuse element only by blowing out one of the fuse wiring layers.

A plurality of fuse wiring layer patterns connected in series can be easily formed by a mask pattern used in a photolithography process, and the number of manufacturing processes does not increase.

In general, the area for arranging fuse elements can be relatively widened even if the main circuit area of the semiconductor device is miniaturized. Therefore, the miniaturization of the semiconductor device is not hindered by a plurality of column patterns.

In the second invention, when a high melting point metal film is used as a wiring layer on a semiconductor substrate, the high melting point metal film is formed at a lower layer position facing the fuse element, so that the fuse element is formed. The laser beam that has passed through is reflected and can be used as the fusing energy of the fuse element. In particular, if the fuse element is a thin film having a thickness of 1000 angstroms or less, the energy absorption is small, and the transmitted energy is high. Becomes possible. Further, even if the beam center is shifted from the center of the fuse element due to the misalignment and the energy directly incident on the fuse element is reduced, the fuse element can be reliably blown by the reflected energy. Such a high melting point metal film is, for example, S
RAM (static random access memory)
Are used as a gate electrode or a wiring layer of a Vss power supply. Therefore, the refractory metal film formed in the lower layer position facing the fuse element can be realized only by changing the mask pattern in the photolithography process. For this reason, even if the thickness of the fuse element is reduced, the number of manufacturing steps does not increase only for manufacturing the redundant circuit, and the reliable melting of the thinned fuse element can be realized without increasing the product cost.

The third invention is a combination of the first invention and the second invention. Even when a large misalignment of the laser irradiation apparatus occurs, at least one of the plurality of rows is required.
One fuse wiring layer can be reliably blown. In addition, since a refractory metal film capable of reflecting an energy beam transmitted through the thinned fuse wiring layer is always formed in a lower layer position facing the fuse wiring layer, the amount of energy absorbed by the fuse wiring layer is increased. As a result, reliable fusing can be realized.

The energy absorption of the thinned second fuse element deteriorates due to the miniaturization of the semiconductor device. In particular, when a beam having a low energy density is irradiated due to misalignment, the second fuse element may not be blown. Therefore, in the fourth invention, a first fuse element thicker than the second fuse element is arranged in the lower layer,
The beam energy transmitted through the second fuse element blows the first fuse element having high energy absorption. Since the first and second fuse elements are connected in series, it is possible to reliably open the fuse element by blowing one of them.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 The structure of a redundant circuit portion of a semiconductor device according to Embodiment 1 will be described in the order of manufacturing steps with reference to FIG.

First, a P-type or N-type silicon substrate 10
Is oxidized in a wet atmosphere at 1100 ° C. to form a silicon oxide film 16 of about 8000 angstroms. Next, a polycrystalline silicon film serving as a wiring layer is formed to a thickness of about 1000 angstroms by the CVD method. Next, after forming a pattern for etching by photolithography,
Unnecessary portions of the polycrystalline silicon film are removed by plasma etching. Then, a fuse element 30 of a polycrystalline silicon film is formed. Note that the fuse element 30 may be formed of a single crystal silicon film or an amorphous silicon film instead of the polycrystalline silicon film.

Here, the fuse element 30 is formed by meandering a one-line wiring layer. As a result, the fuse elements 30 are provided in a plurality of rows at intervals in the wiring width direction (that is, folded in a plurality of times in parallel).
The fuse wiring layers 32 are formed, and the fuse wiring layers 32 in each column are connected in series. In this way, the pattern of the fuse element 30 is formed such that two or more fuse wiring layers 32 exist within the beam diameter of the laser beam 40 as shown in FIG.

Next, the silicon oxide film 18 is formed by CVD.
5000 angstrom. Thereafter, an etching pattern of the contact hole 20 is formed by a photolithography process, and dry etching is performed to form the contact hole 20. Next, about 1 μm of aluminum containing 5% of silicon is formed by a sputtering method,
After forming an etching pattern by a photolithography process, dry etching is performed to form an aluminum wiring 22.

Here, when a defect, for example, due to the adhesion of dust occurs in a chip constituting a memory circuit as a main circuit, the fuse element 30 corresponding to the address is blown off by the laser beam 40 to perform repair.

At this time, even if the fuse element 30 and the laser beam 40 are displaced in any direction due to misalignment, the fuse element 20 can be reliably blown. That is, the fuse element 30 is composed of a plurality of rows of fuse wiring layers 32 (that is, folded a plurality of times in parallel) formed in a meandering manner as shown in FIG. 1A and arranged at intervals in the wiring width direction. , Any one row of the fuse wiring layer 32 within the effective beam diameter (D) of the laser beam 40.
Can always exist. Therefore, even if there is a large misalignment that deviates from the wiring width of one row of fuse wiring layers 32, any one of the plurality of serially connected rows of fuse wiring layers 32 is surely blown, and the fuse element 30 is securely connected. Can be opened.

Here, as an arrangement condition of the fuse wiring layer 32, as shown in FIG. 2, the effective beam diameter that contributes to the fusing of the fuse wiring layer 30 by the laser beam 40 is (D), and the fuse wiring layer 32 The width of each (W)
When the center pitch between two adjacent fuse wiring layers 32 is (P), D> P + W. In this way, even if the misalignment occurs parallel to the width direction of the fuse wiring layer 32, one fuse wiring layer 32 can always be blown by the laser beam 40. The energy distribution of the laser beam 40 is shown in FIG.
The effective beam diameter (D) is a beam diameter having energy (E ′) sufficient to blow the fuse wiring layer 32, for example, energy (E ′) of about 1 μJ.

It is more preferable to set the condition of D ≧ 2P + W. By doing so, one line of the fuse wiring layer 32 is located at the beam center position of the effective beam (D).
Is more likely to be present. Accordingly, since the beam center area having the highest energy can be used for fusing, the thinned fuse wiring layer 32 can always be blown.

(Embodiment 2) In a semiconductor device according to Embodiment 2, two wiring layers are formed at different positions in the thickness direction via an interlayer insulating layer, and one fuse element is connected to two wirings having different layers. It is formed using a layer.

In FIG. 3, an element isolation insulating layer 12 and a gate oxide film 14 are sequentially formed on a silicon substrate 10, and a silicon oxide film 16 is formed thereon. On the silicon oxide film 16, a polycrystalline silicon film as a first wiring layer is formed to about 1000 angstroms,
After forming an etching pattern by photolithography,
By plasma etching, for example, two lower fuse wiring layers 52, 52 are formed in parallel. On the lower fuse wiring layers 52, 52, a silicon oxide film 18 of a second layer as an interlayer insulating layer is formed at various positions in the contact holes 2.
0, 26, and a second layer
A polycrystalline silicon film as a wiring layer is formed to about 1000 Å. Then, an upper fuse wiring layer 54 is formed by a photolithography step and an etching step in a manner parallel to the two lower fuse wiring layers 52 and at an intermediate position therebetween. The upper fuse layer 54 is connected to the lower fuse wiring layer 52 using the contact hole 26. Thereafter, a silicon oxide film 24 is further formed thereon, and finally an aluminum wiring 22 is formed. Aluminum interconnection 22 is connected to lower fuse layer 52 using contact hole 20.

Here, two lower fuse wiring layers 52,
52 and the upper fuse wiring layer 54 formed therebetween are connected in series to the aluminum wiring 22 using the contact hole 26. In this way, the fuse element 50 forms a plurality of rows of fuse wiring layers 52, 52, 54 formed of different layers at intervals in the width direction of the fuse wiring layer, and connects each row in series. Connected.

As a result, the fuse element 50 according to the second embodiment also has the same laser beam 4 as in the first embodiment.
Within the effective beam diameter D of 0, two or more fuse wiring layers can exist.

Embodiment 3 The structure of a semiconductor device according to Embodiment 3 will be described with reference to FIG.

In the semiconductor device according to the third embodiment, a high melting point metal film is used for the first wiring layer, and a second wiring layer is formed on the high melting point metal layer via an interlayer insulating layer. This is a semiconductor device including crystalline silicon.

In this embodiment, a second layer of polycrystalline silicon is used, and a single line of the fuse element 60 is formed by photolithography and etching. Then, a refractory metal film, for example, a tungsten film 62 as a first wiring layer is formed on the fuse element 6.
A pattern is formed in a photolithography process and a subsequent etching process is performed so as to form a lower layer position opposite to 0. In this embodiment, the thickness of the tungsten film 62 is 2000 angstroms, and the thickness of the fuse element 60 is 800 angstroms.
Further, the tungsten film 62 is formed over an area larger than a lower layer position facing the fuse element 60.
This is to ensure that the tungsten film 62 always exists under the fuse element 60 even if the wiring pattern is formed shifted in the width direction when the fuse element 60 is formed.

4A and 4B, when a laser beam 40 is irradiated from above, a part of the fuse element 60 made of a polycrystalline silicon film is absorbed. According to the experiment of the inventor, the fuse 60 made of a polycrystalline silicon film was used.
It has been found that when the film thickness is less than 1000 angstroms, the absorptance of the laser light becomes poor, and most of the laser light is transmitted. As a result, the heat generation of the fuse 60 may be insufficient and the fuse may not be blown.

Here, the energy E absorbed by the fuse element 60 is as follows.

E = Φ [1-exp (−α × t)] Φ: Incident power α: Absorption coefficient of fuse element t: Film thickness of fuse element Absorption coefficient α of polycrystalline silicon constituting fuse element
Is a YLF laser (wavelength = 1047 nm) as a laser light source
Alternatively, in the case of a YAG laser (wavelength = 1056 nm), the absorption coefficient at that wavelength is approximately α = 3 x 10 (1 / cm).

Therefore, the absorption energy E when the thickness of the fuse element is 2000 angstrom as in the prior art.
₁ is E ₁ = 0.006Φ, whereas when the film thickness t becomes 1000 Å, the absorbed energy E ₂ becomes E ₂ = 0.003Φ, indicating that the absorption rate is considerably reduced.

Therefore, as in this embodiment, the fuse element 6
When a tungsten film 62 is provided below 0, the laser beam 40 transmitted through the fuse element 60 is reflected on the tungsten film 62 and is absorbed again by the fuse element 60 made of a polycrystalline silicon film. Therefore, the high melting point metal film 6
If most of the light incident on the fuse element 2 is reflected, the fuse element 60 has about 2.
Double (direct incidence + reflection) laser beam absorption will occur. For this reason, the amount of heat generated by the fuse element 60 is also approximately doubled, so that even if the thickness of the fuse element 60 is reduced, there is no defect that the fuse cannot be blown.

Considering that the incident energy distribution of the laser beam is as shown in FIG. 11, even if a fuse element having no refractory metal film in the lower layer as in the prior art could be blown out using the beam center area, Due to misalignment of the irradiation device, the fuse may not be blown. In this embodiment, the width of the fuse element 60 made of a polycrystalline silicon film is (W), the beam diameter of laser light is (φ), the width of the refractory metal film is L, and W <φ.
<L is set. Therefore, even if the laser beam 40 is slightly shifted due to the alignment shift, the energy absorption of the fuse element 60 is approximately doubled.
This prevents the fuse element 60 from being blown.

The above operation will be described by comparing FIG. 12 and FIG. FIG. 12 is a diagram of the incident + reflected energy density of the laser beam incident on the fuse element 60 in this embodiment.

11 and 12, x is the distance from the center of the laser beam, φ is the laser beam diameter, and E _F
Is the incident energy density of the laser beam, E _FR is the incident and reflected energy density of the laser light assuming that the absorption rate of the laser light is 10%, E 'is the energy density required to blow the fuse, and W is the polycrystal. The fuse width and MG of the silicon film are an alignment margin of a beam and a fuse element that can be allowed to blow the fuse.

11 and 12, the fuse width (W) is 1 μm, and the beam diameter (φ) of the laser beam.
Is 5 μm. In the conventional example of FIG. 13, the alignment margin (MG) for cutting the fuse is small as shown in FIG. 11, and is only 0.6 μm on one side. On the other hand, in the embodiment of FIG. 4, the alignment margin (MG) is
And 1.6 μm can be secured.

In this embodiment shown in FIG. 4, the tungsten film 62 is formed directly on the silicon substrate 10, but the silicon oxide film is formed on the silicon substrate 10 by a thermal oxidation method or a CVD method, and then the tungsten film 62 is formed. May be.

In this embodiment, the tungsten film 62 is used as the high melting point metal film functioning as the reflection layer. However, any metal having a melting point sufficiently higher than that of the fuse element 60 above it may be used. Molybdenum, titanium, platinum, nickel, cobalt, tantalum film or the like may be used as the metal at 1400 ° C. or higher. Alternatively, a refractory metal silicide film, which is a silicon compound of a single refractory metal, may be used as the refractory metal film. The above-mentioned single metal film or silicide film may be preferably formed as a reflective layer to have a thickness of 500 to 3000 Å. Further, as a high melting point metal film, the above-mentioned single high melting point metal film is formed on polycrystalline silicon having a thickness of 500 to 2,000 angstroms.
A refractory metal polycide film formed with a thickness of Å may be used. These materials can be similarly applied to the high melting point metal films of the following embodiments.

(Fourth Embodiment) A semiconductor device according to a fourth embodiment has a fuse element 7 having a planar arrangement as shown in FIG.
It consists of 0. The fuse element 70 includes an upper fuse wiring layer 72 made of a polycrystalline silicon film,
A refractory metal film, for example, a tungsten film 74 is formed at a lower layer position opposite to this, and both of them are connected in series via a contact hole 26 at one end. The other ends of the fuse wiring layer 72 and the tungsten film 74 are connected to the aluminum wirings 22 and 22 via the contact holes 20, respectively, in areas that are drawn right and left from the two-layer overlapping area. That is, the wiring positions of the aluminum wirings 22 and 22 with respect to both ends of the fuse element 70 are patterns arranged in parallel on the same side of the fuse element 70. In this manner, the fuse element 7 having a two-layer structure having a substantially T-shaped pattern is provided.
0.

The sectional structure of the fuse element 70 is shown in FIG.
(A) to (C).

In this embodiment, the fuse wiring layer is formed by utilizing a part of the uppermost third wiring layer among the first to third wiring layers constituting the memory circuit as the main circuit. 7
2 and a tungsten film 74 is formed using a part of the pattern of the second wiring layer.

According to such a structure, even if the energy absorption of the laser beam 40 directly incident on the relatively thin fuse wiring layer 72 is small as in the case of the third embodiment, the fuse wiring layer 72 can be removed. Most of the transmitted laser beam 40 is transmitted to the underlying tungsten film 74.
The fuse wiring layer 72 can be blown by utilizing this energy.

(Embodiment 5) The semiconductor device according to Embodiment 5 has a planar arrangement as shown in FIG.
The cross-sectional structure is as shown in FIGS.
That is, the device of the fifth embodiment is similar to the device of the fourth embodiment,
It is the same in that a tungsten film 74 is provided in a lower layer facing a fuse wiring layer 72 using a third wiring layer, but the tungsten film 74 serves as a first wiring layer of a memory circuit forming a main circuit. Utilizing this, a part of the pattern is formed to extend to a position below the fuse wiring layer 72.

In the case of the fifth embodiment, as in the third and fourth embodiments, the energy of the laser beam 40 transmitted through the relatively thin fuse wiring layer 72 is reflected by the tungsten film 74 so that the fuse wiring is formed. It can contribute to the fusing of the layer 72.

However, since two silicon oxide films 16 and 18 exist as an interlayer insulating layer between the fuse wiring layer 72 and the tungsten film 74, the fusing energy is consumed by the energy absorption there. become.

(Sixth Embodiment) Similarly, the semiconductor device according to the sixth embodiment has a planar arrangement as shown in FIG. 5 and a sectional structure as shown in FIGS. 8 (A) to 8 (C). It was done. That is, the fuse wiring layer 72 is formed using a part of the pattern of the second wiring layer of the memory circuit forming the main circuit. On the other hand, the tungsten film 74
It is formed using a pattern of a part of the first wiring layer of the memory circuit. The point that the energy reflected by the tungsten film 74 can be used as the fusing energy of the fuse wiring layer 72 is the same as in the above-described embodiments.

(Embodiment 7) The semiconductor device according to the embodiment 7 has a fuse element 80
Are composed of an upper fuse element 82 made of polycrystalline silicon and a lower fuse element 86 made of a refractory metal film formed in a region facing the fuse element 82. And furthermore,
The fuse elements 82 and 86 in the upper layer and the lower layer are divided into fuse wiring layers 84 and 88 provided in a plurality of columns at intervals in the wiring width direction (that is, folded in a plurality of times).
It consists of. One ends of the upper and lower fuse elements 82 and 86 are connected in phase using the contact holes 26, and the other ends are connected to the aluminum wirings 22 and 22 using the contact holes 20, respectively.

According to the seventh embodiment, the upper fuse element 82 has a plurality of rows of fuse wiring layers 8 in the wiring width direction.
4, the fuse can always be blown out with one fuse wiring layer 84 within the effective beam diameter D of the laser beam 40 even if an alignment error occurs.

Further, since a fuse wiring layer 88 formed of a high melting point metal film always exists at a lower layer position facing each of the fuse wiring layers 84 in a plurality of rows constituting the upper fuse element 82, a relatively thin film is formed. Even if the laser beam 40 passes through the upper fuse wiring layer 84, the energy that contributes to the fusing of the upper fuse wiring layer 84 can be increased by reflecting the laser beam 40 on the lower fuse wiring layer 88. As a result, the fuse element 80 can be reliably blown.

As a modification of the seventh embodiment, the semiconductor substrate 1
In the case where three wiring layers are formed at 0, three combinations can be applied as in the fourth to sixth embodiments.

In the fourth to seventh embodiments described above, the upper fuse wiring layers 72 and 84 and the lower fuse wiring layers 74 and 88 made of a refractory metal film are connected in series, and both of them are connected in series. Although the fuse elements 70 and 80 are formed, both ends of the upper fuse wiring layers 72 and 84 are connected to the aluminum wirings 22 and 22, and the lower refractory metal film 7 is formed.
It is also possible to use 4,88 only as a reflection layer of the laser beam 40.

When the lower refractory metal film is formed wider than the upper fuse wiring layer, the surface of the refractory metal film may be formed in a concave lens shape. With this configuration, the laser beam transmitted through the upper fuse wiring layer and incident on the refractory metal film can be focused on the fuse wiring layer and reflected, thereby further increasing the fusing energy of the fuse wiring layer. Becomes possible.

(Embodiment 8) In this embodiment 8, as shown in FIG. 10, first and second fuse elements 92 and 94 both made of polycrystalline silicon are interposed via a silicon oxide film 18 which is an interlayer insulating layer. The fuse element 90 is formed by forming one end of the fuse element 90 and the other end of the fuse element 90 in series. The upper second fuse element 92 is a thin film of, for example, 1000 Å or less, and the first fuse element 94 is formed thicker than the second fuse element 92.

When the laser beam is applied to the fuse element 90, the energy is absorbed by the second fuse element 92 in the upper layer. If the laser beam misalignment is small, the second fuse element 92 can be blown using the high energy density region shown in FIG. However, when the misalignment increases, a region having a low energy density is irradiated to the second fuse element 92.
At this time, since the thin film second fuse element 92 has low energy absorption, it may be difficult to reliably blow it. The laser beam transmitted through the thin film second fuse element 92 is applied to the first fuse element 94 having good energy absorption by forming a relatively thick film. Although the energy density of the laser beam incident on the first fuse element 94 is lower than that of the laser beam incident on the first fuse element 94, the melting due to heat generation is ensured due to the good energy absorption.

As described above, according to the eighth embodiment, the fuse element 90 can be reliably opened by blowing one of the first and second fuse elements 94 and 92 connected in series.

[0073]

According to the first aspect of the present invention, a plurality of columns (that is, a plurality of parallel folded portions) are arranged at intervals in the wiring width direction.
And one of the fuse wiring layers connected in series, even if the laser beam is largely shifted in the width direction of the wiring, one of the fuse wiring layers must be positioned within the beam diameter of the laser beam. Can be
The fuse element can be reliably blown.

According to the second aspect of the present invention, by forming the high melting point metal film in a lower layer position facing the fuse element, the laser beam transmitted through the fuse element is reflected and used as the fusing energy of the fuse element. In particular, the thinned fuse element can be reliably blown.

According to the third aspect of the present invention, the fuse element is reliably blown by the action of both the first and second aspects of the present invention, even when a beam misalignment occurs with respect to the thin-film fuse element. There is an effect that can be done.

According to the fourth aspect of the present invention, when the misalignment is small, the second fuse element having a thinner upper layer can be blown by a beam having a high energy density. The first fuse element having a relatively thick film and high energy absorption can be blown by the beam transmitted through the second fuse element having a small number of fuse elements, and one of the fuse elements connected in series in the upper and lower layers is reliably blown. it can.

[Brief description of the drawings]

FIGS. 1A and 1B show a semiconductor device according to a first embodiment of the present invention. FIG. 1A is a plan view of a fuse element seen from above, and FIG. It is II sectional drawing of A).

FIG. 2 shows an effective beam diameter of a laser beam and two adjacent beams.
FIG. 3 is a schematic explanatory diagram showing an arrangement relationship with a fuse wiring layer of the present invention.

3A and 3B show a semiconductor device according to a second embodiment of the present invention. FIG. 3A is a plan view of the fuse element seen from above, and FIG. (A) is a sectional view taken along the line II-II, and (C) is a sectional view taken along the line III-III in FIG.

4A and 4B show a semiconductor device according to a third embodiment of the present invention. FIG. 4A is a plan view of the fuse element seen from above, and FIG. It is IV-IV sectional drawing of A).

FIG. 5 is a plan view of a semiconductor device according to a fourth embodiment to a sixth embodiment of the present invention as seen through from above.

6A and 6B show a sectional structure of a semiconductor device according to a fourth embodiment of the present invention. FIG. 6A is a sectional view taken along line VV of FIG. 5, and FIG. 6B is a sectional view taken along line VI-VI of FIG. FIG. 5 (C) is the same as FIG.
It is VII-VII sectional drawing.

FIGS. 7A and 7B show a cross-sectional structure of a semiconductor device according to a fifth embodiment of the present invention. FIG. 7A is a cross-sectional view taken along line VI-VI of FIG. 5, and FIG. It is sectional drawing.

8A and 8B show a sectional structure of a semiconductor device according to a sixth embodiment of the present invention. FIG. 8A is a sectional view taken along line VI-VI of FIG. 5, and FIG. 8B is a sectional view taken along line VII-VII of FIG. It is sectional drawing.

9A and 9B show a semiconductor device according to a seventh embodiment of the present invention. FIG. 9A is a plan view of the fuse element seen from above, and FIG. 9B is a view of FIG. VIII-VIII sectional drawing of FIG.

10A and 10B show a semiconductor device according to an eighth embodiment of the present invention. FIG. 10A is a plan view of the semiconductor device seen from above, and FIG. ) Is a sectional view taken along the line IX-IX, (C) is a sectional view taken along the line XX in (A), and (D) is a sectional view taken along the line XI-XI in (A).

FIG. 11 is a characteristic diagram showing an energy distribution of a laser beam.

FIG. 12 is a characteristic diagram showing an energy distribution of energy directly incident on the fuse wiring layer and energy reflected and incident on the fuse wiring layer when a refractory metal film is provided below the fuse wiring layer.

FIG. 13 shows a conventional semiconductor device, wherein FIG. 13A is a plan view of the fuse element seen from above, and FIG. 13B is a sectional view taken along line XII-XII of FIG. It is.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Silicon substrate 16, 18, 24 Silicon oxide film 20, 26 Contact hole 22 Aluminum wiring 30 Fuse element 32 Fuse wiring layer 40 Laser beam 50 Fuse element 52 Lower fuse wiring layer 54 Upper fuse wiring layer 60 Fuse element 62 High melting point metal film Reference Signs List 70 fuse element 72 fuse wiring layer 74 refractory metal film 80 fuse element 82 upper fuse element 84 fuse wiring layer 86 lower fuse element 88 fuse wiring layer 90 fuse element 92 second fuse element 94 first fuse element

Claims (1)

(57) [Claims] 1. A semiconductor device having a fuse element that can be blown by a laser beam, wherein the fuse element is formed above a first fuse element formed above a substrate, and above the first fuse element. And a second fuse element formed above the interlayer insulating film, wherein the first fuse elements are provided in a plurality of columns at intervals in the wiring width direction. A fuse wiring layer formed in series, wherein the second fuse element is formed above and opposed to a space formed between the adjacent fuse wiring layers; A semiconductor device which is connected to a fuse wiring layer via a contact hole.