Cu-Mn Alloy Self-Forming Barrier for Semiconductor Interconnects
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Solution Overview
Problem
Conventional methods for forming thin barrier metal films in miniaturized semiconductor devices face challenges with adhesion issues between barrier metal films and low-dielectric interlayer insulation films, leading to poor film quality and increased specific resistance in Cu interconnection patterns.
Innovation Solution
A method involving the formation of a Cu—Mn alloy layer on the inner walls of interconnection trenches and via-holes, followed by a self-forming reaction with the interlayer insulation film to create a thin, uniform MnSixOy diffusion barrier film, which reduces the specific resistance of the Cu layer by preventing Mn oxide formation and promoting Mn diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional barrier metal films (Ta, W, TaN) are used to cover interconnection trenches and via-holes, then adhesion between barrier film and interlayer insulation film is improved, but film thickness cannot be reduced sufficiently to maintain low specific resistance in miniaturized devices
Solution Approach 1:
The invention changes the material composition parameters by using a Cu-Mn alloy layer instead of conventional barrier metals. The Mn content is controlled at 1-20 at%, and through thermal processing, the material transforms in-situ to form a Cu-Mn-Si-O barrier layer with optimized thickness and adhesion properties suitable for miniaturized interconnections
Solution Approach 2:
The Cu-Mn alloy layer performs multiple functions: it serves as the interconnection material, provides the barrier function through in-situ reaction with Si and O from the interlayer insulation film to form Cu-Mn-Si-O layer, and reduces specific resistance through Mn diffusion into the Cu layer during thermal processing
2Manufacturing precision
If MOCVD or ALD processes are used to form extremely thin barrier metal films, then film uniformity is improved, but film quality deteriorates due to poor adhesion with low-dielectric interlayer insulation films
Solution Approach 1:
The invention introduces Mn as an intermediary element that reacts with Si and O from the interlayer insulation film to form a Cu-Mn-Si-O barrier layer. This intermediary reaction creates strong chemical bonding between the Cu-based interconnection layer and the interlayer insulation film, resolving the adhesion problem
Solution Approach 2:
The invention creates a composite barrier layer (Cu-Mn-Si-O) through in-situ reaction, combining elements from the interconnection layer (Cu, Mn) and the interlayer insulation film (Si, O). This composite structure provides both adhesion and barrier functionality
3Manufacturing precision
If barrier metal film thickness is reduced to maintain low specific resistance, then interconnection resistance is improved, but adhesion between barrier film and interlayer insulation film deteriorates
Solution Approach 1:
The Cu-Mn alloy layer serves multiple functions simultaneously: it provides the interconnection conductivity, forms the barrier layer through in-situ reaction with the interlayer insulation film, and reduces specific resistance through Mn diffusion during thermal processing, eliminating the need for separate thin barrier metal layers
Solution Approach 2:
The in-situ formed Cu-Mn-Si-O barrier layer creates a composite structure that naturally adheres to both the Cu interconnection layer and the interlayer insulation film, providing adequate adhesion without requiring increased thickness
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 results in a semiconductor device with significantly reduced specific resistance of the Cu interconnection pattern, achieving a specific resistance of 1.9 μΩcm, which is about half that of previous methods, while maintaining a thin and uniform diffusion barrier film.
Implementation Method 1
a self-forming reaction with the interlayer insulation film to create a thin, uniform MnSixOy diffusion barrier film
Implementation Method 2
promoting Mn diffusion
Data Source
AI summary
A method for fabricating a semiconductor device has forming an opening defined by an inner wall surface in an insulation film, covering said inner wall surface with a Cu—Mn alloy layer, depositing a first Cu layer over said Cu—Mn alloy layer without exposing said Cu—Mn alloy layer to the air, depositing a second Cu layer over said first Cu layer and filling said opening with said second Cu layer, and forming a barrier layer over said inner wall surface as a result of a reaction between Mn in said Cu—Mn alloy layer and said insulation film.