Cu-Mn Alloy Diffusion Barrier for Semiconductor Interconnects
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Solution Overview
Problem
Current methods for forming barrier films in semiconductor devices with Cu interconnection structures, such as Physical Vapor Deposition (PVD) and Chemical Vapor Deposition (CVD, struggle to achieve uniform thin films, leading to unreliable Cu interconnections due to difficulties in uniformly forming thin barrier films, which can result in high resistance and signal delay.
Innovation Solution
A method involving the formation of a Cu—Mn alloy layer as a seed layer, followed by a copper layer with a higher concentration of oxygen, carbon, or nitrogen, which is then heated to diffuse Mn atoms into the Cu layer, creating a self-aligned diffusion barrier film and reducing Mn concentration in Cu interconnections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If PVD or CVD methods are used to form a barrier film, then the barrier film can be formed, but it is difficult to achieve uniform thin film formation, leading to unreliable Cu interconnections
Solution Approach 1:
The Cu-Mn alloy layer performs dual functions: it serves as both the interconnect material and the source of Mn for forming the diffusion barrier film. During heating, Mn atoms automatically diffuse to the interface between the Cu layer and interlayer insulating film to form the barrier film, eliminating the need for separate barrier film formation processes and achieving uniform thickness through self-alignment
Solution Approach 2:
The invention changes the composition parameters by adding Mn to Cu to form a Cu-Mn alloy layer. This compositional change enables Mn to diffuse and form the barrier film during subsequent heating processes, transforming the barrier film formation from a separate deposition process into an integrated diffusion process that achieves better uniformity
2Reliability
If a Cu-Mn alloy layer is formed and heated to create a diffusion barrier film, then the barrier film is formed effectively, but Mn concentration remains in the Cu interconnections, increasing resistance
Solution Approach 1:
The invention creates local concentration differences by introducing oxygen, carbon, or nitrogen at specific locations (in the second Cu layer). During heating, Mn atoms preferentially diffuse to these regions with high oxygen, carbon, or nitrogen content, achieving local segregation that removes Mn from the bulk Cu interconnection while concentrating it in specific zones, thus reducing overall resistance
Solution Approach 2:
Oxygen, carbon, or nitrogen act as intermediary substances that facilitate Mn diffusion and segregation. These elements serve as mediators that attract and concentrate Mn atoms in specific regions during the heating process, enabling effective separation of Mn from the Cu interconnection material
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 effectively reduces the Mn concentration in Cu interconnects, lowering resistance and enabling faster signal transmission by segregating Mn in regions with high oxygen, carbon, or nitrogen content, thereby improving the reliability and performance of Cu interconnection structures.
Implementation Method 1
the added metal is diffused by heating to form a Cu diffusion barrier film
Implementation Method 2
heating the substrate on which the second copper layer has been formed
Data Source
AI summary
A semiconductor device fabrication method including the steps of: forming an interlayer insulating film on a substrate; forming an opening in the interlayer insulating film; forming an alloy layer containing manganese and copper to cover the inner surface of the opening; forming a first copper layer of a material containing primarily copper on the alloy layer to fill the opening; forming, on the first copper layer, a second copper layer of a material containing primarily copper and a higher concentration of oxygen, carbon or nitrogen than the first copper layer; heating the substrate on which the second copper layer has been formed; and removing the second copper layer.