Amorphous Etch Stop Layers for Copper Diffusion Barriers
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Solution Overview
Problem
The diffusion of copper atoms between metal interconnects in high-density integrated circuits, such as VLSI circuits, leads to parasitic capacitance and cross-talk, which is exacerbated by the use of low-k dielectric materials, causing etching difficulties and potential circuit failures.
Innovation Solution
Forming amorphous metal caps and etch stop layers to prevent copper diffusion by converting polycrystalline structures into amorphous layers using nitrogen-containing plasma treatments, thereby improving etching processes and reducing under-etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If low-k dielectric materials are employed to reduce parasitic capacitance, then conduction speed between metal interconnections is improved, but copper diffusion increases causing etching difficulties and potential circuit failures
Solution Approach 1:
An amorphous aluminum nitride layer is introduced as an intermediary between the copper-containing conductive features and the low-k dielectric material. This intermediate layer acts as a diffusion barrier that prevents copper atoms from migrating into the low-k dielectric, thereby eliminating etching difficulties while allowing the low-k material to maintain its low parasitic capacitance and high conduction speed benefits.
Solution Approach 2:
The patent changes the physical and chemical parameters of the barrier layer by forming an amorphous aluminum nitride layer with specific properties (amorphous structure, nitrogen-containing composition) rather than using conventional crystalline barrier materials. This parameter change creates a more effective diffusion barrier that is compatible with low-k dielectric materials, preventing copper diffusion without compromising etching precision.
2Ease of manufacture
If conventional polycrystalline barrier layers are used, then manufacturing process is simpler, but copper diffusion occurs leading to under-etching and reduced manufacturing yield
Solution Approach 1:
The patent changes the structural parameter of the barrier layer from polycrystalline to amorphous phase. The amorphous aluminum nitride layer provides superior copper diffusion barrier properties compared to conventional polycrystalline materials, preventing under-etching and improving manufacturing yield while maintaining process compatibility through atomic layer deposition techniques.
Solution Approach 2:
The patent uses a composite structure consisting of amorphous aluminum nitride combined with specific deposition processes (atomic layer deposition) to create a barrier layer that combines the benefits of simple manufacturing with high etching precision. The amorphous nature of the aluminum nitride provides uniform properties that enhance diffusion blocking capability.
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 formation of amorphous layers effectively blocks copper diffusion, enhancing etching precision and manufacturing yield by eliminating under-etching and ensuring proper electrical connections.
Implementation Method 1
converting polycrystalline structures into amorphous layers using nitrogen-containing plasma treatments
Implementation Method 2
performing a first treatment to amorphize the metal cap; performing a second treatment to amorphize the etch stop layer
Implementation Method 3
Amorphous Layers for Reducing Copper Diffusion; the amorphous metal cap and the amorphous etch stop layer, it is more difficult for the metal such as copper in the first conductive feature to diffuse upwardly
Data Source
AI summary
A method includes depositing an etch stop layer over a first conductive feature, performing a first treatment to amorphize the etch stop layer, depositing a dielectric layer over the etch stop layer, etching the dielectric layer to form an opening, etching-through the etch stop layer to extend the opening into the etch stop layer, and filling the opening with a conductive material to form a second conductive feature.