Thin Ion Beam Fuse for Semiconductor Interconnects
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Solution Overview
Problem
Conventional fuse structures in semiconductor devices face challenges such as damage to underlying layers during etch processing, difficulty in forming on non-planar surfaces, and metal corrosion issues, which affect their programming and spacing requirements.
Innovation Solution
The use of focused ion beam deposition to form thin fuse layers with predetermined thicknesses, which are absorptive to laser programming, eliminating the need for etch processing and allowing precise placement without additional protective layers, thus reducing minimum pitch spacing and avoiding corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thick metal lines are used to form fuse connection structures, then the fuse can be formed and connected, but the etch processing required to define the fuse connection structure damages the underlying layers
Solution Approach 1:
The patent changes the thickness parameter of the metal layer from thick to thin (less than 500 Angstroms). This thin metal layer is deposited using ion beam deposition, which allows the fuse to be formed without requiring aggressive etch processing that would damage underlying layers. The thinness of the metal layer enables selective removal through laser programming without the need for thick etching processes.
Solution Approach 2:
The patent replaces the mechanical/chemical etching process with a laser-based programming approach. Instead of using etch chemistry to define and program the fuse, a laser is used to selectively remove or modify the thin metal layer. This substitution eliminates the harmful effects of etch processing on underlying layers while maintaining fuse functionality.
2Ease of manufacture
If thick metal fuses are used, then the fuse connection structure can be formed, but it becomes difficult to form on non-planar surfaces and difficult to laser program due to reflectivity and metal thickness
Solution Approach 1:
The patent changes the thickness parameter of the metal layer to be very thin (less than 500 Angstroms). This thinness has two benefits: (1) it allows the metal to conform to non-planar surfaces more easily, and (2) it reduces laser reflectivity, making laser programming more effective. The thin metal layer absorbs laser energy more efficiently rather than reflecting it, enabling reliable fuse programming.
3Reliability
If interconnect barrier layers are deposited and patterned to form fuses, then the fuse connection can be made, but protective layers must be formed over metal and bond pad layers to prevent metal corrosion during etching, which increases minimum pitch spacing
Solution Approach 1:
The patent replaces the etching process with laser programming. Since no etching is performed on the thin metal fuse layer, there is no risk of metal corrosion during processing. This eliminates the need for protective layers over metal and bond pad areas, and consequently removes the overlap requirements that would increase minimum pitch spacing between features.
4Ease of manufacture
If the last metal layer is used to define the fuse connection structure, then the fuse can be formed, but the etch processes used to program or blow such coplanar last metal fuses require deposition of a uniform thin film followed by a patterned etch process that can cause metal corrosion
Solution Approach 1:
The patent changes the thickness parameter of the metal layer to be very thin (less than 500 Angstroms), which enables direct laser programming without requiring additional thin film deposition and etch processes. This thin metal layer can be selectively removed by laser energy, providing a simpler and corrosion-free programming method compared to using the full-thickness last metal layer with conventional etch processes.
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
This approach enables efficient, precise, and cost-effective formation and programming of fuse structures without damaging underlying layers, allowing for dynamic reprogramming of semiconductor circuitry while reducing spacing constraints and metal corrosion issues.
Implementation Method 1
a localized deposition process is then applied to form a programmable thin conductive fuse layer on the exposed metal layers
Implementation Method 2
the thin fuse layer may then be programmed to blow, thereby electrically disconnecting the exposed metal layers from one another
Data Source
AI summary
A back-end-of-line thin ion beam deposited fuse (204) is deposited without etching to connect first and second last metal interconnect structures (110, 120) formed with last metal layers (LM) in a planar multi-layer interconnect stack to programmably connect separate first and second circuit connected to the first and second last metal interconnect structures.