Copper-Based Nitride Liner for Low-Resistance Interconnects
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Solution Overview
Problem
The miniaturization of transistors in integrated circuits leads to increased electrical resistance in conductive structures due to the limitations of traditional barrier layer materials and copper seed layers, which are difficult to etch and prone to oxidation, affecting the density and performance of copper-based conductive lines and vias.
Innovation Solution
Forming a copper-based nitride liner/passivation layer by converting a copper seed layer into a copper-based nitride layer, which acts as a barrier to copper and oxygen, reducing electrical resistance and allowing for more efficient filling of trenches/vias during copper deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional barrier layer materials and copper seed layers are used in miniaturized transistors, then device density is improved, but electrical resistance increases due to etching difficulties and oxidation
Solution Approach 1:
The patent changes the chemical composition of the seed layer from pure copper to copper-based nitride (Cu3N or Cu4N), which fundamentally alters the material properties. This compositional change enables the seed layer to function as both a copper source and an oxidation barrier, resolving the contradiction between maintaining low electrical resistance and preventing oxidation in miniaturized structures
Solution Approach 2:
The invention uses copper-based nitride as a composite material that combines the beneficial properties of copper (high conductivity) with nitrogen (oxidation resistance). This composite approach allows the single layer to perform multiple functions: providing copper atoms for conductive structure formation while simultaneously acting as a diffusion barrier against oxygen, thereby reducing electrical resistance and improving reliability
2Ease of manufacture
If copper seed layer is used, then copper deposition is enabled, but oxidation occurs affecting performance
Solution Approach 1:
The copper-based nitride seed layer is self-passivating, meaning it automatically protects itself from oxidation without requiring external protective layers. The nitrogen atoms in the copper nitride structure create a stable compound that resists oxidation, allowing the seed layer to serve its copper deposition function while inherently protecting against the harmful oxidation effect
Solution Approach 2:
The nitrogen atoms in copper-based nitride act as an intermediary barrier between copper and oxygen. This intermediate layer prevents direct contact between copper and oxygen, blocking the oxidation reaction while still allowing the copper nitride to serve as a source of copper atoms for the conductive structure formation
3Productivity
If feature size is reduced to increase transistor density, then device functionality is improved, but conductive structure resistance increases
Solution Approach 1:
By changing the seed layer composition to copper-based nitride, the patent achieves lower electrical resistance in miniaturized conductive structures. The copper nitride provides a more efficient copper source with better atomic layer control, enabling lower resistance even as feature sizes decrease to increase transistor density
Solution Approach 2:
The copper-based nitride seed layer is formed in advance with controlled thickness and composition before the main copper deposition process. This preliminary preparation ensures optimal copper atom availability and distribution, which is critical for maintaining low resistance in the final conductive structures as device features are scaled down
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 copper-based nitride layer reduces electrical resistance and minimizes oxygen migration, enabling the formation of conductive structures with improved performance and density in integrated circuits.
Implementation Method 1
converting at least a portion of the copper-based seed layer into a copper-based nitride layer
Implementation Method 2
a copper-based nitride layer positioned between the copper-based conductive structure and the layer of insulating material
Data Source
AI summary
One illustrative method disclosed herein includes forming a trench/via in a layer of insulating material, forming a barrier layer in the trench/via, forming a copper-based seed layer on the barrier layer, converting at least a portion of the copper-based seed layer into a copper-based nitride layer, depositing a bulk copper-based material on the copper-based nitride layer so as to overfill the trench/via and performing at least one chemical mechanical polishing process to remove excess materials positioned outside of the trench/via to thereby define a copper-based conductive structure. A device disclosed herein includes a layer of insulating material, a copper-based conductive structure positioned in a trench/via within the layer of insulating material and a copper-based silicon or germanium nitride layer positioned between the copper-based conductive structure and the layer of insulating material.