Molybdenum Nitride Diffusion Barrier Stack for Semiconductor Interconnects
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Solution Overview
Problem
Existing diffusion barriers in semiconductor devices face mechanical instability and interdiffusion issues due to grain boundaries in crystalline structures, particularly with molybdenum nitride being brittle and prone to cracking, which complicates the reproduction of consistent diffusion barrier characteristics.
Innovation Solution
A mechanically stable diffusion barrier stack is created by depositing a molybdenum layer followed by a molybdenum nitride layer, using techniques like sputtering in a deposition chamber, which enhances mechanical stability and reduces interdiffusion by preventing cracking and delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a molybdenum nitride layer is used as a diffusion barrier, then diffusion prevention is improved, but mechanical stability deteriorates due to brittleness and cracking
Solution Approach 1:
The patent applies composite materials by creating a barrier stack structure that combines molybdenum nitride layer with molybdenum layer and titanium nitride layer. This composite structure leverages the excellent diffusion barrier properties of molybdenum nitride while the molybdenum and titanium nitride layers provide mechanical stability and crack resistance, thereby resolving the contradiction between diffusion prevention and mechanical stability.
Solution Approach 2:
The patent segments the single molybdenum nitride barrier layer into a multi-layer stack structure. By dividing the barrier function across multiple layers with different material properties, the system achieves both effective diffusion prevention (through molybdenum nitride) and mechanical stability (through molybdenum and titanium nitride layers), eliminating the brittleness issue of pure molybdenum nitride.
2Ease of manufacture
If a crystalline structure with grain boundaries is used, then material deposition is simplified, but interdiffusion increases due to grain boundary pathways
Solution Approach 1:
The patent uses composite materials in the barrier stack where the combination of molybdenum nitride, molybdenum, and titanium nitride layers creates a structure that blocks grain boundary diffusion pathways. The multiple layers with different crystallographic structures work together to prevent interdiffusion while maintaining ease of deposition through standard sputtering processes.
3Reliability
If multiple layers are deposited to improve barrier performance, then diffusion prevention is enhanced, but device complexity increases
Solution Approach 1:
The patent segments the diffusion barrier function into three specialized layers: molybdenum nitride for primary diffusion blocking, molybdenum for mechanical stability, and titanium nitride for additional barrier performance. This segmentation enhances diffusion prevention while the systematic layering approach keeps the manufacturing process manageable and not excessively complex.
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 barrier stack structure effectively prevents interdiffusion and reaction between semiconductor layers and metal interconnects, maintaining device integrity and reducing defects, as demonstrated by improved microscope images showing no cracking or delamination.
Implementation Method 1
depositing a molybdenum layer outwardly from the semiconductor layer in a deposition chamber, and depositing a molybdenum nitride layer outwardly from the molybdenum layer in the deposition chamber
Data Source
AI summary
A mechanically stable diffusion barrier stack structure and method of fabricating the same is disclosed. The diffusion barrier stack structure having a molybdenum nitride layer deposited on a molybdenum layer and operates to prevent diffusion between a semiconductor layer and a metal interconnect. The method for fabricating includes depositing a molybdenum layer outwardly from the semiconductor layer in a deposition chamber, and depositing a molybdenum nitride layer outwardly from the molybdenum layer in the deposition chamber.