Molybdenum Capping for Copper Interconnect Diffusion Control
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Solution Overview
Problem
Existing metallization processes for semiconductor devices face challenges in preventing copper interconnect oxidation and copper diffusion into dielectric structures, which affects the electromigration reliability of copper-containing layers.
Innovation Solution
A method involving plasma-enhanced chemical vapor deposition (PECVD) is used to selectively deposit a molybdenum capping layer on copper interconnects, while exposing the dielectric surface to a molybdenum-containing precursor gas, thereby preventing copper diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional metallization processes are used to deposit copper interconnects, then copper can be deposited with relatively low cost and good processing properties, but copper diffusion into dielectric structures and copper oxidation occur, reducing electromigration reliability
Solution Approach 1:
A molybdenum capping layer is deposited as an intermediary barrier between the copper interconnect and the dielectric structure. This intermediate layer prevents direct contact and interaction between copper and dielectric materials, thereby stopping copper diffusion and oxidation while maintaining electrical functionality.
Solution Approach 2:
The patent uses a composite structure combining copper interconnects with a molybdenum capping layer. This composite material system leverages the high electrical conductivity of copper while using molybdenum's diffusion barrier properties to prevent harmful copper migration, achieving both electrical performance and structural stability.
2Object-generated harmful factors
If barrier and capping layers are deposited to contain copper, then copper diffusion is prevented, but the process complexity and number of deposition steps increase
Solution Approach 1:
The molybdenum capping layer serves multiple functions simultaneously: it acts as a diffusion barrier to prevent copper migration, provides oxidation protection, and maintains adhesion between layers. This multi-functionality reduces the need for separate barrier and capping layers, simplifying the overall process.
Solution Approach 2:
The patent employs plasma-enhanced chemical vapor deposition (PECVD) to deposit the molybdenum layer at controlled temperatures and pressures. By optimizing deposition parameters such as plasma power, gas flow rates, and substrate temperature, the process achieves high-quality capping layers with improved adhesion and reduced processing complexity.
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 molybdenum capping layer effectively prevents copper diffusion into dielectric structures, improves adhesion, and enhances the electromigration reliability of copper interconnects.
Implementation Method 1
performing a plasma-enhanced chemical vapor deposition (PECVD) deposition process
Implementation Method 2
delivering a molybdenum-containing precursor gas to a substrate comprising a copper interconnect surface and a dielectric surface in a plasma processing chamber
Implementation Method 3
The molybdenum capping layer effectively prevents copper diffusion into dielectric structures
Data Source
AI summary
Embodiments of the invention provide a method of forming a molybdenum (Mo) capping layer that is used to prevent copper diffusion in interconnect boundary regions of a formed semiconductor device. The molybdenum capping will improve copper boundary region properties to promote adhesion, decrease diffusion and copper agglomeration. Embodiments provide that a molybdenum capping layer may be selectively deposited on a surface of a copper interconnect structures formed in a dielectric layer formed on a substrate.