Fuse structure window

Details Fuse structure window Fuse structure window

2003-03-10

2004-06-15

Vortman, Anatoly (Department: 2835)

Electricity: electrothermally or thermally actuated switches

Electrothermally actuated switches

Fusible element actuated

C337S160000, C337S290000, C337S296000, C337S405000, C257S209000, C257S529000, C365S225700

Reexamination Certificate

active

06750753

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fuse structure, and in particular fuse structure that can avoid damage from the laser blow process in its laser spot.
2. Description of the Related Art
Fuses are routinely used in the design of monolithic integrated circuits (IC). Fuses are programming elements for the product after monolithic integrated circuit manufacture programming.
It is well known that random access memories (RAM) are designed with redundancies which include spare columns, rows, or even fully functional arrays, wherein when any element fails, the defective row, column and the like are replaced by a corresponding element. Disabling and enabling of spare elements is accomplished by fuses which are blown when required, preferably, by a laser beam.
Additionally, the technique of laser fuse deleting (trimming) has been widely used both in the memory and logic IC fabrication industries, as an effective way to improve functional yields and to reduce development cycle time. Yet, fuse blow yield and fuse reliability have been problematic in most conventional fuse designs.
FIG. 1
is a sectional view of a traditional fuse structure,
FIG. 2
is a top view of a traditional fuse structure, and
FIG. 1
shows a cross section C-C′ of FIG.
2
.
Referring to
FIG. 1
, symbol
100
shows a substrate having a laser spot
110
. A metal layer M
0
is formed on part of the substrate
100
. A metal layer M
1
is formed on part of the oxide layer, between the metal layer M
0
and metal layer M
1
having a oxide layer
120
. A conductive plug
130
penetrating the oxide layer
120
electrically connects the metal M0 layer and M1 layer. A laser spot
110
on part of the metal M1 layer and the top of a part of the oxide layer
120
forms a fuse window
140
. The symbol
150
is a passivation layer.
Referring to
FIG. 2
is a top view of FIG.
1
. There are plural fuse structures
210
,
220
,
230
,
240
in fuse window
140
. Each fuse structure comprises the M0 layer, the conductive plug
130
and the M1 layer. The solid line area shows the M1 layer, the dashed line area shows M0 layer, and each fuse structure comprises its own optimal laser spot
11
. To give an example, a laser beam
290
blows the position
110
of the fuse structure
220
. Because of misalignment of the laser beam
290
or thermal scattering of the laser beam
290
, thermal shock from the laser blow process can damage the M0 layer. This can cause the fuse structures to crack, seriously affecting device reliability and yield.
SUMMARY OF THE INVENTION
Accordingly, an object of the invention provides a fuse structure comprising a substrate, a plurality of conductive layers, a dielectric layer and a plurality of conductive plugs in a new arrangement, increasing the distance between different fuse units.
Another object of the invention provides a fuse window having a plurality of fuse structures, each of the fuse structures comprising a substrate, a plurality of conductive layers, a dielectric layer and a plurality of conductive plugs. The fuse units do not electrically connect to each other.


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