Nickel Silicide Interconnects via Metal Halide Precursors
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Solution Overview
Problem
As integrated circuit components shrink below 50 nm, conventional copper interconnects face increased resistivity due to electron scattering and are prone to electromigration, necessitating new materials and methods for forming reliable metal interconnections within the back-end-of-line (BEOL) processes, which require low thermal budgets.
Innovation Solution
A method involving the formation of a clean metal halide layer on a substrate, followed by exposure to a siliciding agent at temperatures below 400°C to create a nickel silicide layer, using chemical vapor deposition and atomic layer deposition techniques to minimize contamination and achieve reliable silicide-based interconnects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional copper interconnects are used in sub-50 nm features, then high conductivity is achieved at larger dimensions, but resistivity increases due to electron scattering at surfaces and grain boundaries
Solution Approach 1:
The patent changes the material parameter from copper to nickel silicide, fundamentally altering the electrical and thermal properties to suit sub-50 nm dimensions where copper fails due to surface scattering effects
Solution Approach 2:
The patent uses a composite approach by forming nickel silicide through reaction between nickel and silicon layers, creating a material with superior electrical properties for nanoscale interconnects
2Reliability
If copper interconnects are used to meet current density requirements, then electrical performance is maintained, but electromigration damage occurs leading to wire failure
Solution Approach 1:
The patent changes the material composition from copper to nickel silicide, which has higher melting point and better resistance to electromigration, thereby extending the operational lifespan of the interconnect
3Manufacturing precision
If high thermal budget processes are used to form silicides, then complete silicide formation is achieved, but low-k dielectric damage occurs in BEOL processes
Solution Approach 1:
The patent performs preliminary actions by depositing thin nickel and silicon layers with controlled stoichiometry before the siliciding reaction, enabling complete silicide formation at lower temperatures that protect the low-k dielectric
Solution Approach 2:
The patent changes the temperature parameter from conventional high-temperature siliciding (>650°C) to low-temperature processing (<400°C) by modifying the precursor layer composition and structure
4Productivity
If feature dimensions are reduced to increase circuit density, then greater circuit densities are achieved, but material performance deteriorates due to surface effects
Solution Approach 1:
The patent changes the material system from copper to nickel silicide, which maintains stable electrical properties at nanoscale dimensions where copper suffers from surface scattering and electromigration
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 the formation of reliable silicide-based interconnects at low thermal budgets, reducing impurity incorporation and enhancing the conductivity and durability of nanoscale interconnects, thus addressing the limitations of conventional copper interconnects.
Implementation Method 1
The metal halide layer is cleaned by exposure to a halogen gas to form a clean metal halide layer
Implementation Method 2
The clean metal halide layer is exposed to a siliciding agent to form a metal silicide
Implementation Method 3
The clean metal halide layer is exposed to a siliciding agent to form a metal silicide
Data Source
AI summary
Methods for depositing or forming a metal silicide layer are disclosed. A metal halide layer is deposited, cleaned by a halogen and subjected to a siliciding agent to form the metal silicide.