Doped Connecting Structure to Block Anneal Metal Diffusion
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Solution Overview
Problem
As semiconductor devices shrink in size, the challenge of forming reliable connecting structures becomes more complex due to metal diffusion issues during the anneal process, leading to bottom metal-loss problems in the fabrication of ICs.
Innovation Solution
A method involving ion implantation to form a doped dielectric layer as a diffusion barrier within the conductive material, which obstructs metal diffusion and reduces the bottom metal-loss issue by creating a compressive stress layer, thereby enhancing the reliability of connecting structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feature sizes continue to decrease to increase functional density, then production efficiency and cost are improved, but fabrication process complexity and difficulty increase
Solution Approach 1:
A doped dielectric layer is formed within the metal layer before the metal diffusion process occurs. This preliminary action creates a diffusion barrier that prevents metal atoms from migrating to the substrate during subsequent annealing processes, thereby solving the bottom metal-loss problem that becomes more severe at smaller feature sizes
Solution Approach 2:
The doped dielectric layer acts as an intermediary barrier between the metal layer and the substrate. This intermediate layer with different chemical composition and crystal structure physically blocks the diffusion path of metal atoms, preventing direct interaction between the metal and substrate while allowing the fabrication process to continue at reduced feature sizes
2Ease of manufacture
If conventional metal layers are used without diffusion barriers, then manufacturing process is simpler, but bottom metal-loss occurs during anneal process
Solution Approach 1:
The dielectric layer is doped with specific materials to alter its chemical composition and physical properties. This parameter change creates a layer with reduced metal solubility and different crystal structure, transforming it into an effective diffusion barrier that prevents metal loss while maintaining compatibility with existing manufacturing processes
Solution Approach 2:
The connecting structure employs a composite material system consisting of the metal layer, the doped dielectric layer, and the substrate. This composite structure combines materials with different properties to achieve both ease of manufacture and high reliability, as the doped dielectric layer provides diffusion barrier functionality while the metal layer maintains its conductive properties
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 method effectively mitigates the bottom metal-loss issue by reducing metal diffusion, improving the integrity and reliability of connecting structures in semiconductor devices, even as feature sizes decrease.
Implementation Method 1
a doped dielectric layer disposed over the first dielectric layer and including a compressive stress to the metal portion, wherein the doped dielectric layer obstructs metal diffusion from the conductive feature
Implementation Method 2
the doped dielectric layer includes a compressive stress to the metal portion
Data Source
AI summary
A connecting structure includes a first dielectric layer disposed over a substrate and a conductive feature, a doped dielectric layer disposed over the first dielectric layer, a first metal portion disposed in the first dielectric layer and in contact with the conductive feature, and a doped metal portion disposed over the first metal portion. The first metal portion and the doped metal portion include a same noble metal material. The doped dielectric layer and the doped metal portion include same dopants.