Semiconductor Fuse Copper Migration Prevention
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Solution Overview
Problem
Copper (Cu) migration in semiconductor fuses during the blowing process can lead to incomplete cutting and reconnection of fuse ends, especially under high temperature and humidity conditions, affecting the reliability of semiconductor devices.
Innovation Solution
A semiconductor fuse design featuring copper (Cu) and aluminum (Al) fuse metals with a TiN conductive layer, where the aluminum fuse metal is formed in a recess wider than the laser spot to prevent copper migration, ensuring complete cutting and maintaining electrical isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper (Cu) is used as fuse metal, then electrical conductivity is improved, but copper migration occurs under high temperature and humidity conditions causing reconnection of fuse ends
Solution Approach 1:
A barrier layer is introduced between the copper fuse metal and the surrounding environment. This intermediary layer prevents copper atoms from migrating while allowing the fuse to maintain its electrical conductivity function. The barrier layer acts as a mediator that blocks the harmful migration path without interfering with the electrical properties of the copper fuse.
Solution Approach 2:
The fuse structure is transformed from pure copper to a composite structure consisting of copper fuse metal combined with a barrier layer. This composite material approach allows the system to benefit from both the high electrical conductivity of copper and the migration-blocking properties of the barrier layer, resolving the contradiction between conductivity and migration resistance.
2Manufacturing precision
If laser energy is increased to ensure complete fuse cutting, then cutting effectiveness is improved, but copper migration is exacerbated due to higher temperature
Solution Approach 1:
The barrier layer serves as a protective intermediary that allows the system to tolerate higher laser energies during the blowing process. By preventing copper migration even at elevated temperatures, the barrier layer enables complete fuse cutting to be achieved without risking reconnection, thus resolving the contradiction between cutting completeness and temperature control.
3Reliability
If fuse metal is completely evaporated during blowing, then clean cutting is achieved, but residue remains when evaporation is incomplete causing reconnection
Solution Approach 1:
The barrier layer acts as a protective intermediary that prevents residue formation and blocks migration paths. Even when copper evaporation is incomplete, the barrier layer prevents the residual copper from migrating and reconnecting the fuse ends, thus ensuring cutting reliability without requiring complete evaporation of the fuse metal.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design effectively prevents copper migration, ensuring reliable fuse cutting and improving the yield of semiconductor devices by maintaining electrical isolation and preventing reconnection of fuse ends.
Implementation Method 1
the fuse of a failed cell is then cut by irradiating with a laser. In this case, the laser energy passes through the insulating layer without being absorbed because the insulating layer has the same properties as glass. Thus, most of the laser energy is absorbed by the fuse. The fuse is thermally expanded by the laser energy, and so the fuse is blown and cut.
Implementation Method 2
The fuse is thermally expanded by the laser energy, and so the fuse is blown and cut.
Data Source
AI summary
A fuse of a semiconductor device includes first fuse metals formed over an underlying structure and a second fuse metal formed between the first fuse metals. Accordingly, upon blowing, the fuse metals are not migrated under conditions, such as specific temperature and specific humidity. Thus, reliability of a semiconductor device can be improved.