Copper Silicide Interconnects with Nitrogen Gradient
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Solution Overview
Problem
Existing interconnection elements in integrated circuit interconnection structures face challenges such as inefficient electrical coupling and complex manufacturing processes, particularly in forming reliable copper silicide layers with nitrogen gradients.
Innovation Solution
A method involving etching a cavity in an insulating layer, depositing silicon nitride with a nitrogen concentration gradient, followed by copper deposition and heat treatment to form copper silicide, and then filling the cavity with copper, which enhances the nitrogen concentration gradient in the silicide layers, improving electrical coupling and reducing manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional refractory materials are used to form interconnection elements, then mechanical stability is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent changes the material composition parameters by forming copper silicide layers with controlled nitrogen concentrations (5-20 at%) through selective deposition and heat treatment, replacing traditional refractory materials while achieving comparable mechanical stability with simpler manufacturing
Solution Approach 2:
The patent uses copper, an abundant and inexpensive material, to form interconnection elements instead of rare and costly refractory materials, reducing both material cost and manufacturing complexity while maintaining mechanical stability through controlled silicide formation
2Reliability
If copper is used as interconnection material, then cost is reduced and electrical conductivity is improved, but copper migration becomes a problem
Solution Approach 1:
The patent performs preliminary heat treatment to form copper silicide layers with nitrogen incorporation before final interconnection formation, creating a stable structure that prevents copper migration during subsequent processing and operation
Solution Approach 2:
The patent introduces nitrogen-containing silicon nitride layers as intermediary layers between copper regions, where nitrogen atoms (at 5-20 at% concentration) act as barriers to copper diffusion while maintaining electrical conductivity, thus preventing copper migration without sacrificing electrical coupling
3Object-generated harmful factors
If nitrogen concentration in silicide layer is increased, then copper migration prevention is improved, but electrical conductivity may deteriorate
Solution Approach 1:
The patent applies local quality by creating nitrogen concentration gradients in the silicide layers, with higher nitrogen content (up to 20 at%) at interfaces where copper migration prevention is critical, and lower nitrogen content (5 at% or less) in bulk regions where electrical conductivity is prioritized
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 approach results in interconnection elements with improved mechanical stability, reduced resistivity, and effective prevention of copper migration, while being less expensive and simpler to produce than traditional methods using refractory materials, with better bonding and reduced risk of contamination.
Implementation Method 1
the nitrogen atom concentration in the silicide layer increases as the distance away from the copper increases
Implementation Method 2
heating to form a fourth layer of copper silicide from the second and third layers
Data Source
AI summary
An interconnection element of an interconnection structure of an integrated circuit is manufactures by a method where a cavity is etched in an insulating layer. A silicon nitride layer is then deposited on walls and a bottom of the cavity. The nitrogen atom concentration in the silicon nitride layer increasing as a distance from an exposed surface of the silicon nitride layer increases. A copper layer is deposited on the silicon nitride layer. The cavity is further filled with copper. A heating process is performed after the deposition of the copper layer, to convert the copper layer and the silicon nitride layer to form a copper silicide layer which has a nitrogen atom concentration gradient corresponding to the gradient of the silicon nitride layer.