Self-Forming Copper Barrier via Manganese Diffusion
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Solution Overview
Problem
In semiconductor devices, the advancement of technology nodes is hindered by RC delay, and copper diffusion into low-k dielectric substrates is a challenge due to the lack of an efficient barrier layer in integrated circuits.
Innovation Solution
A self-forming liner or barrier layer is formed by diffusing manganese from a manganese-containing seed layer into the interface between copper lines and dielectric fill during annealing, creating a continuous and uniform barrier layer that prevents copper diffusion and enhances electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a barrier layer is formed to prevent copper diffusion into low-k dielectric, then copper diffusion is prevented, but the process complexity increases due to additional barrier layer formation steps
Solution Approach 1:
The manganese element in the copper-containing layer automatically diffuses to the interface between copper lines and dielectric fill during annealing treatment, self-forming a barrier layer without requiring separate barrier layer deposition steps. This self-organizing behavior resolves the contradiction by achieving reliable copper diffusion prevention while maintaining simple processing.
Solution Approach 2:
The manganese element acts as an intermediary substance that mediates between the copper-containing layer and the low-k dielectric. During annealing, manganese diffuses to the interface and forms a barrier layer that prevents copper diffusion, thus resolving the contradiction through the introduction of a mediating element that enables barrier formation without complex processing.
2Reliability
If annealing is applied to increase grain size of copper, then electrical conductivity is improved, but manganese diffusion to form barrier layer requires additional process control
Solution Approach 1:
The patent combines two functions into a single annealing process: (1) increasing copper grain size to improve electrical conductivity, and (2) diffusing manganese to the interface to form a barrier layer. By merging these two previously separate requirements into one integrated annealing step, the patent achieves improved conductivity while avoiding additional process control complexity.
Solution Approach 2:
The annealing process continuously performs dual useful actions simultaneously: copper grains grow to enhance conductivity while manganese continuously diffuses to the interface to form the barrier layer. This continuous dual-action approach resolves the contradiction by making the process more efficient rather than more complex.
3Ease of manufacture
If subtractive copper method is used to form copper lines, then manufacturing is simplified, but barrier layer formation becomes challenging
Solution Approach 1:
The manganese element is pre-included in the copper-containing layer before the subtractive patterning process. This preliminary incorporation of the barrier-forming element allows the barrier layer to self-form after etching, resolving the contradiction by preparing the necessary components in advance that will automatically assemble into the final structure without complicating the subtractive manufacturing approach.
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 increases grain size, improves electrical conductivity, and extends electromigration lifetimes while maintaining a high integrity liner-copper interface, reducing the need for complex etch schemes and enhancing reliability.
Implementation Method 1
During the second anneal, the barrier forming elements diffuse to an interface between sidewalls of the plurality of the copper containing lines and the dielectric fill to form a barrier layer along the sidewalls of the copper containing lines
Implementation Method 2
A first anneal is applied to the copper containing layer. The first anneal process increases the grain size of the copper in the copper containing layer
Data Source
AI summary
A method of forming electrically conductive structures that includes forming a copper containing layer including a barrier forming element, and applying a first anneal to the copper containing layer. The first anneal increases grain size of the copper in the copper containing layer. The copper containing layer is etched to provide a plurality of copper containing lines. A dielectric fill is deposited in the space between adjacent copper containing lines. A second anneal is applied to the plurality of copper containing lines. During the second anneal the barrier forming element diffuse to an interface between sidewalls of the copper containing lines and the dielectric fill to form a barrier layer along the sidewalls of the copper containing lines.