Layout structure of efuse fuse

Abstract

The present invention discloses a layout structure of an efuse fuse, which includes a second pad, a second fuse, and a second protective layer. The second protective layer adopts a double nested structure composed of multiple groups of bent metal wires, each group of bent metal wires is symmetrically arranged on both sides of the fuse, one end of the bent metal wire is connected to the second fuse, and the other end of the bent metal wire points to another symmetrical L-shaped metal wire. The present invention not only forms a protective layer to prevent the burst metal spray from affecting other circuits, but also can assist in heat dissipation on the fuse, which helps to form a temperature gradient with a high middle and low sides, so that the fusing phenomenon is not too severe, and is controlled to occur in the middle part of the fuse, so as to improve the reliability of programming.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, and in particular to a layout structure of an efuse fuse. Background Art

[0002] Based on the principle of electromigration (EM), efuse realizes the fusing of fuses through programming operations and converts them into logic outputs to realize on-chip programming functions. Efuse is a one-time programming device (OTP), and the reliability of its programming operation is one of the most important evaluation indicators. There are many ways to improve the reliability of efuse units. Among them, setting a protective layer on the efuse unit layout is a common method. This method can prevent the fuse from spraying metal to other circuits when it explodes, causing the efuse function to fail. However, the current conventional protective layer layout method may cause the sprayed metal to hit the protective layer and then reflect back to the fuse, causing the disconnected fuse to be reconnected, thereby causing the programming operation to fail.

[0003] The fuse layout structures of two conventional efuse units are as follows: Figure 1 and Figure 2 As shown, its characteristic is that the entire fuse includes a first Pad (solder pad) 101 and a first fuse (link) 102, and a first protective layer 103, wherein the first protective layer is composed of a single or multiple metal wires of the same layer parallel to the fuse, and is used to prevent the material on the metal wire that has exploded from affecting other modules and causing functional failure. At both ends of the first fuse are the first Pads, and the first Pads use the same metal layer as the first fuse body. The first Pad has an effective heat dissipation area, and its purpose is to make the efuse blow at the middle part of the first fuse, rather than at both ends of the first fuse, because the larger first pad area is easy to dissipate heat, and the first fuse will accumulate heat when electromigration occurs, and form a temperature gradient from high temperature to low temperature on the first fuse, resulting in the blowing process occurring at the high temperature in the middle of the first fuse. This phenomenon can be seen from Figure 3 As shown in the thermal distribution diagram of a conventional efuse fuse. In addition, during actual programming, if the current passing through the first fuse is too large or there is an uneven resistance distribution on the first fuse, it may cause the local heat of the first fuse to be too large and too fast, which will cause the first fuse to burst or even the first fuse metal to spray. Therefore, the conventional layout of the efuse fuse is often designed with a first protective layer to block the metal that is sprayed by the burst to prevent it from affecting other circuits. The metal wires of the protective layer are arranged in a direction parallel to the fuse. Although the protective layer of this layout method can achieve a blocking effect, sometimes the sprayed metal passes through the metal wires of the protective layer parallel to the fuse and reconnects to the disconnected fuse, so that the resistance of the fuse disconnected after programming returns from a larger resistance value to a smaller value, causing an error in the logic output, that is, the programming operation fails. Summary of the invention

[0004] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides a layout structure of an efuse fuse.

[0005] The present invention solves the above technical problems through the following technical solutions: a layout structure of an efuse fuse, characterized in that it includes a second Pad, a second fuse, and a second protective layer, the second protective layer adopts a double overlapping structure composed of multiple groups of bent metal wires, each group of bent metal wires is symmetrically arranged on both sides of the fuse, one end of the bent metal wire is connected to the second fuse, and the other end of the bent metal wire points to another symmetrical L-shaped metal wire.

[0006] Preferably, the width of the meandering metal line is the same as the width of the second fuse.

[0007] Preferably, each group of the bent metal wires are disconnected from each other.

[0008] Preferably, the meandering metal line and the second fuse are located in the same metal layer.

[0009] Preferably, the two groups of meandering metal wires between the two second Pads are symmetrically distributed.

[0010] Preferably, the horizontal spacing between the meandering metal line and the second PAD and between two meandering metal lines is L / 8, and the vertical spacing between the meandering metal line and the second fuse and between two meandering metal lines is H / 3, where H is the height of the second PAD and L is the length of the second fuse.

[0011] Preferably, the distance between the endpoints of the outer symmetrical meandering metal wires is twice the width of the second fuse, and the distance between the endpoints of the inner symmetrical meandering metal wires is three times the width of the second fuse.

[0012] The positive and progressive effect of the present invention is that the present invention improves the layout of the protective layer in the efuse unit, which not only forms a protective layer to prevent the explosion of metal spray from affecting other circuits, but also can assist in heat dissipation on the fuse, helping to form a temperature gradient with high in the middle and low on both sides, so that the melting phenomenon is not too severe, and is controlled to occur in the middle part of the fuse, so as to improve the reliability of programming. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of the fuse layout structure of the first existing efuse unit.

[0014] Figure 2 It is a structural schematic diagram of the fuse layout structure of the second existing efuse unit.

[0015] Figure 3 This is a simulation diagram of the heat distribution of an existing efuse when it blows.

[0016] Figure 4 It is a structural schematic diagram of the layout structure of the efuse fuse of the present invention. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0018] like Figure 4 As shown, the layout structure of the efuse fuse of the present invention includes a second Pad (soldering pad) 201, a second fuse (link) 202, and a second protective layer 203. The second protective layer adopts a double overlapping structure composed of multiple groups of bent metal wires. Each group of bent metal wires is symmetrically arranged on both sides of the fuse. One end of the bent metal wire is connected to the second fuse, and the other end of the bent metal wire points to another symmetrical L-shaped metal wire.

[0019] The width of the meandering metal line is the same as that of the second fuse, and the consistency is maintained.

[0020] Each group of bent metal wires is disconnected from each other, that is, the ends of the two bent metal wires are not connected to prevent short circuit. The short-circuited metal wires will increase the current flow capacity of the fuse, making the fuse less likely to be blown, that is, unable to work normally.

[0021] The bent metal wire and the second fuse are located in the same metal layer. The bent metal wire can dissipate heat for the second fuse, so that the second fuse will form a temperature drop gradient from the middle to both sides, thereby ensuring that the heat in the middle of the second fuse is the maximum and the melting point will also be located here.

[0022] The two groups of bent metal wires between the two second pads are symmetrically distributed, so that the temperature gradient from the middle to both ends of the second fuse is symmetrical, that is, the highest temperature occurs at the midpoint of the second fuse, which is beneficial to the reliability of the fuse.

[0023] Figure 4 Where H is the height of the second PAD, L is the length of the second fuse, the horizontal spacing between the meandering metal line and the second PAD and between the two meandering metal lines is L / 8, the vertical spacing between the meandering metal line and the second fuse and between the two meandering metal lines is H / 3, forming a suitable temperature gradient on the second fuse to blow the fuse.

[0024] Figure 4The w in the figure is the width of the second fuse, the distance between the endpoints of the outer symmetrically bent metal wires is twice the width of the second fuse, and the distance between the endpoints of the inner symmetrically bent metal wires is three times the width w of the second fuse, forming a suitable temperature gradient.

[0025] In summary, the layout structure of the efuse fuse of the present invention not only forms a protective layer to prevent the explosion of metal spray from affecting other circuits, but also can assist in heat dissipation on the fuse, helping to form a temperature gradient with high in the middle and low on both sides, so that the melting phenomenon is not too severe, and is controlled to occur in the middle part of the fuse, so as to improve the reliability of programming.

[0026] The above specific implementation modes are preferred embodiments of the present invention and cannot be used to limit the present invention. Any other changes or other equivalent replacement methods that do not deviate from the technical solution of the present invention are included in the protection scope of the present invention.

Claims

1. A layout structure of an efuse fuse, characterized in that: It includes a second pad, a second fuse, and a second protective layer. The second protective layer adopts a double stacking structure composed of multiple groups of meandering metal wires. Each group of meandering metal wires is symmetrically arranged on both sides of the fuse. One end of the meandering metal wire is connected to the second fuse, and the other end of one meandering metal wire points to the other end of another symmetrical meandering metal wire along the length direction of the second fuse. The meandering metal wire and the second fuse are located in the same metal layer; Each group of the bent metal wires are disconnected from each other; The two groups of meandering metal wires between the two second Pads are symmetrically distributed.

2. The layout structure of the efuse fuse according to claim 1, characterized in that: The width of the meandering metal line is the same as that of the second fuse.

3. The layout structure of the efuse fuse according to claim 1, characterized in that: The distance between the endpoints of the outer symmetrical meandering metal line along the length direction of the second fuse is twice the width of the second fuse, and the distance between the endpoints of the inner symmetrical meandering metal line along the length direction of the second fuse is three times the width of the second fuse.

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