Self-Forming Barrier in Cobalt Interconnects
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
At smaller technology nodes, such as the 10 nm class, the barrier and liner layers in semiconductor manufacturing occupy a significant volume within patterned openings, reducing conductivity and performance, and the step of depositing a barrier layer adds complexity and cost.
Innovation Solution
A method of forming self-forming barrier layers by selectively removing a portion of the semiconductor dielectric layer, disposing a metal liner layer, and applying diffusion ions within the metal filling or liner layer, which diffuse into the dielectric upon heating to form a barrier layer without occupying additional volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a barrier layer and seed liner layer are deposited prior to cobalt filling, then the dielectric is protected from cobalt diffusion and the filling process can proceed, but the barrier layer occupies up to one third of the trench or via volume, significantly reducing conductivity and performance
Solution Approach 1:
Diffusion ions (such as manganese ions) are incorporated into the cobalt filling solution before the filling process begins. These ions are preliminarily positioned within the cobalt filling structure, ready to diffuse into the dielectric during subsequent thermal processing, eliminating the need for a separate barrier layer deposition step
Solution Approach 2:
The invention changes the chemical composition parameters of the cobalt filling by incorporating diffusion ions (e.g., manganese ions) into the filling solution. This compositional modification enables the cobalt filling to self-form a barrier layer during thermal processing, transforming the filling material from a simple conductor into a multi-functional material that provides both conductivity and barrier protection
2Volume of moving object
If the barrier layer and seed liner layer are made only a few nanometers thick to accommodate smaller trench and via sizes, then the volume occupation is reduced, but it becomes difficult to control the uniformity of such thin layers within the trench or via, especially when aspect ratios approach 10
Solution Approach 1:
The cobalt filling process automatically incorporates diffusion ions into the filling structure during the plating process itself. The thermal processing step that follows causes these ions to self-diffuse into the dielectric, automatically forming a barrier layer without requiring separate deposition steps. This self-service mechanism eliminates the manual control difficulties associated with depositing ultra-thin uniform layers
Solution Approach 2:
The invention merges the barrier layer formation function with the cobalt filling process. Instead of separately depositing a barrier layer and then filling, the diffusion ions are incorporated into the filling solution, and the thermal processing simultaneously completes the filling and forms the barrier layer in one integrated process step
3Reliability
If a separate barrier layer deposition step is performed prior to filling, then the dielectric is protected from damage, but the fabrication process complexity and cost increase
Solution Approach 1:
The cobalt filling solution is designed to serve multiple functions: it provides the conductive cobalt filling material and simultaneously introduces diffusion ions that will form the barrier layer. This multi-functional filling solution eliminates the need for a separate barrier layer deposition step, reducing fabrication process complexity while maintaining dielectric protection
Solution Approach 2:
The invention converts the potential harm of cobalt diffusion into a beneficial self-forming barrier layer. By incorporating diffusion ions into the filling process, the thermal processing that would normally cause unwanted diffusion instead creates a controlled, beneficial barrier layer that protects the dielectric
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 eliminates the need for a separate barrier deposition step, maintains the size of patterned openings, and enhances conductivity by allowing more volume for metal filling without reducing the dimensions of the trench or via, thus improving semiconductor performance.
Implementation Method 1
Heat is applied to the metal filling and metal liner layer to diffuse the diffusion ions from one of the metal filling and the metal liner layer into the dielectric layer
Implementation Method 2
Heat is applied to the metal filling and metal liner layer to diffuse the diffusion ions
Data Source
AI summary
A method of forming a self-forming barrier includes selectively removing a portion of a semiconductor dielectric layer to form a three-dimensional pattern within a remaining portion of the dielectric layer. A metal liner layer is disposed on a surface of the pattern to provide a metal lined pattern. A metal filling is disposed over the metal lined pattern, the metal filling being at least partially composed of a metal used in the metal liner layer. Diffusion ions are disposed in one of the metal filling and the metal liner layer. Heat is applied to the metal filling and metal liner layer to diffuse the diffusion ions from one of the metal filling and the metal liner layer into the dielectric layer to form a barrier layer between the metal liner layer and the dielectric layer.