JPH07273199A - Semiconductor device - Google Patents

Abstract

PURPOSE:To blow out a fuse easily with a laser beam even if no redundancy window is provided by forming a fuse blow material layer constituting a redundancy fuse at a relatively upper layer. CONSTITUTION:A fuse blow material layer 11 is formed of a wiring metal on a layer insulating film 100 covering a silicon substrate 101. The fuse blow material layer 11 is covered with a layer insulating film 14. A laser absorbing material layer 12 is formed on the layer insulating film 14 while covering the metal layer 11. The laser absorbing material layer 12 employs TiN or polysilicon which absorbs laser light efficiently. Since the fuse blow material layer 11 is formed at a relatively upper layer, the fuse can be blown out easily without requiring any blow-out window and the step for making a window can be eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a structure suitable for blowing a fuse by using laser blow in a redundant circuit of an LSI.

[0002]

2. Description of the Related Art Generally, in an LSI, a redundant circuit is often provided in order to compensate for defects and improve yield. For this reason, a method of providing a redundancy and replacing the circuit by melting the redundancy fuse is used.

Laser blowing by a laser is often used to blow such a redundancy fuse, but for this purpose, an element structure suitable for laser blowing is required.

FIG. 4 is a cross-sectional view of such a conventional semiconductor device, and particularly illustrates an LSI having a multilayer structure.

As shown in the figure, the fuse polysilicon 5 for functioning the redundancy is formed on the interlayer insulating film 8 on the silicon substrate. The polysilicon 5 is covered with an interlayer insulating film 6. The polysilicon 5 is manufactured in the same process as the gate forming a transistor (not shown). An interlayer insulating film 7 is arranged on the interlayer insulating film 6.

The first metal layer 4 for wiring is an interlayer insulating film 7.
And is disposed in the interlayer insulating film 2. On the other hand, the second metal layer 3 for wiring is arranged on the interlayer insulating film 2. A passivation film 1 for protecting the device is arranged on the second metal layer 3.

A redundancy window 8 and a pad window 9 are provided in portions of the interlayer insulating film 2 and the passivation film 1 corresponding to the fuse polysilicon 5.

In the structure described above, the fuse polysilicon 5 for redundancy is arranged on the lower layer 8, and the first metal layer 4 for wiring is arranged on the layer 7 above it. The second metal layer 3 for wiring is arranged on the layer 2 thereabove.

Here, polysilicon is used as the material of the fuse polysilicon 5 because the gate material forming the semiconductor element (transistor) is polysilicon and is arranged in the first or second layer, and Is low and stable, and can be easily fused when irradiated with laser light. In addition to polysilicon, a polycide structure with a refractory metal such as W or Mo can be used. Incidentally, the interlayer insulating film 6 on the fuse polysilicon 5,
Reference numerals 7 and 2 are, for example, 2000 to 8000 angstroms, and the optimum thickness is determined from the focus and power of the laser beam.

[0010]

The conventional semiconductor device is
As described above, in the multilayer structure, since the lower layer is polysilicon and the second layer above it is a metal layer, the structure becomes complicated. Therefore, the fuse polysilicon 5 and the first metal layer 4 are formed. The interlayer insulating films 6, 7, and 2 in between have a large film thickness, and a special etching step is required to obtain an appropriate film thickness.

Further, since the fuse polysilicon 5 is formed below in the same process as the gate of the transistor, the film thicknesses of the interlayer insulating films 6, 7 and 2 are properly adjusted in order to facilitate the fuse blowing. It requires a special process to do so.

On the other hand, since redundancy is performed after the diffusion process, a redundancy window 8 is provided above the fuse polysilicon 5 and no passivation is applied, so that water and impurities do not soak into the redundancy window 8. Need to do so. In order to improve the reliability of the pellet, it is necessary to increase the distance (thickness) from the side surface of the redundancy window 8 to the wiring first metal layer 4 or the second metal layer 3 in order to improve the reliability. is there. Therefore, the limitation of the chip size of the higher-order device and the addition of the number of steps cannot be avoided. Considering the step of leaving the interlayer insulating films 6, 7, and 2 on the fuse polysilicon 5, for example, 3
In the case of the layer metal layer product, since the interlayer insulating films 6, 7, and 2 are thicker by that much, the etching time becomes longer, and it is necessary to improve the resist selectivity ratio, or the etching is divided into a plurality of parts.
A problem is that the etching margin is reduced and the number of processes is increased.

The present invention is intended to solve the problems of the prior art as described above, and an object thereof is to blow a fuse without opening a window for blowing the fuse or by reducing the number of steps. To provide a semiconductor device.

[0014]

The semiconductor device of the present invention comprises:
A transistor having a gate formed of a polysilicon layer deposited on a semiconductor substrate via an insulating film, and a first wiring layer formed above the transistor via the insulating film;
A semiconductor device in which a defective circuit is replaced with a redundant circuit by fusing a redundancy fuse, wherein the second wiring layer formed in the same step as that of the first wiring layer is used as a fuse blow material layer to form the redundancy fuse. The laser absorber is formed almost directly above the redundant fuse via an insulating film.

A second semiconductor device of the present invention is the semiconductor device according to the first semiconductor device, wherein the laser absorber is one laser absorbing material layer.

According to a third semiconductor device of the present invention, in the first semiconductor device, the laser absorber is the first and second semiconductor devices.
The third wiring layer is formed in a step different from that of the third wiring layer, and the laser absorbing material layer is laminated on the third wiring layer.

[0017]

The fuse blow material layer forming the redundancy fuse is formed in a relatively upper layer. As a result, even if there is no window for redundancy, fusing with laser light is facilitated, or the number of steps for opening the window is reduced, and the manufacturing process of the semiconductor device is simplified. Moreover, the laser light absorbing material layer is formed above the fuse blow material layer,
The laser light is efficiently absorbed, and the fuse is surely blown.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

Example 1. 1 is a sectional view of a semiconductor device according to a first embodiment of the present invention. As shown in the figure, an interlayer insulating film 100 is formed on a silicon substrate 101, and a fuse blow material layer 11 is further formed thereon by a wiring metal layer (Al layer). The fuse blow material layer 11 is covered with an interlayer insulating film 14. A laser absorbing material layer 12 is arranged on the interlayer insulating film 14 and above the metal layer 11 (almost directly above the metal layer 11). The laser absorption material layer 12 is formed of a Ti-based metal material such as TiN or an arbitrary material such as polysilicon that efficiently absorbs a laser. A metal layer 13 for wiring is also arranged on the interlayer insulating film 14. Metal layer 1
A passivation film 15 is disposed on the fuse blowing material layer 3 and the fuse blowing material layer 12.

In the above-mentioned structure, when a laser is irradiated, a certain laser absorbing material layer 12 and the fuse blow material layer 12 immediately below the laser absorbing material layer 12 are instantaneously burnt out. That is, the fuse blow material layer 12 can be burned out without providing an opening window for redundancy.

Note that, in place of the fuse blow material layer 12 in FIG. 1, the multilayer laser absorber 20 shown in FIG. 2 can be formed at the same position as that. The absorber 20 is formed by laminating a laser absorption material layer 23 on an insulating film 22 on a base layer 21 formed in the same step as the wiring metal layer 13 in order to prevent reflection of laser light. .
The absorption material layer 23 is made of the same material as the laser absorption material layer 12 of FIG. Alternatively, the insulating film 22 may be omitted and the absorbing material layer 23 may be directly formed on the base layer 21.

Incidentally, the insulating film 2 is formed on the base layer 21.
2. When disposing the absorbing material layer 23, first, the base layer 21 is formed of a metal layer material, the insulating film 22 of a single layer or a plurality of layers is formed thereon, and then, at a low temperature of 600 ° C. or lower. Then, it is effective to deposit a laser absorption material layer 23 made of an insulating material or a conductive material above the fuse blow material layer 12 so as to cover all or a part of the layer, and perform patterning.

Example 2. Third Embodiment FIG. 3 is a sectional view of a semiconductor device according to a second embodiment of the present invention. As shown in the figure, the fuse blow material layer 11 is arranged in the interlayer insulating film 14 on the interlayer insulating film 100. A metal layer 13 for wiring is arranged on the layer of the interlayer insulating film 14. On the upper portion of the passivation film 15 corresponding to the fuse blow material 11, a laser absorption material layer 12 for redundancy is arranged.

Note that, instead of the laser absorbing material layer 12, the laser absorbing body 20 of FIG. 2 can be used at the same position as in the first embodiment.

[0025]

According to the present invention, the fuse blow material layer is formed not by the polysilicon formed at the same step as the transistor gate but by the wiring material layer. Since it is formed, the fusing can be easily performed without providing the window for fusing or by reducing the number of steps for providing the window.

[Brief description of drawings]

FIG. 1 is a sectional view of a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing a laser absorber.

FIG. 3 is a sectional view of a semiconductor device according to a second embodiment of the present invention.

FIG. 4 is a sectional view of a conventional semiconductor device.

[Explanation of symbols]

 11 Fuse Blow Material Layer 12 Laser Absorption Material Layer 13 Metal Layer 14 Interlayer Insulation Film 15 Passivation Film 20 Laser Absorber 21 Base Layer 22 Insulation Film 23 Laser Absorption Material Layer 100 Interlayer Insulation Film 101 Silicon Substrate

Claims (3)

[Claims] 1. A transistor having a gate, which is a layer having polysilicon deposited on an semiconductor substrate via an insulating film, and a first wiring layer formed above the transistor via the insulating film. In the semiconductor device, a defective circuit is replaced with a redundant circuit by blowing a redundancy fuse, and a second wiring layer formed in the same step as the first wiring layer is used as a fuse blow material layer. A redundant fuse is configured, and just above this redundant fuse,
A semiconductor device characterized in that a laser absorber is formed via an insulating film. 2. The semiconductor device according to claim 1, wherein the laser absorber is one layer of laser absorbing material. 3. The laser absorber has a multi-layer structure in which a laser absorbing material layer is laminated on a third wiring layer formed in a step different from that of the first and second wiring layers. The semiconductor operation according to claim 1.