Cu Interconnection Barrier Formation via Metal Diffusion
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Solution Overview
Problem
Conventional Cu interconnection structures in semiconductor devices require thick barrier films to prevent diffusion, which increase resistance and are difficult to deposit uniformly, while barrier-less structures with alloy elements like Al, Mg, and Sn are unreliable and increase electric resistance.
Innovation Solution
A semiconductor device manufacturing method that forms a barrier film by diffusing a predetermined metal element, such as Mn, into the interface between the Cu interconnection layer and the insulating film, creating a stable compound like MnO to prevent Cu diffusion, reducing the need for a conventional barrier film and minimizing resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick barrier film is used to prevent Cu diffusion, then diffusion protection is improved, but interconnection resistance increases and manufacturing difficulty increases
Solution Approach 1:
The Cu interconnection layer itself serves as the source of the barrier film material. Through heat treatment, Cu atoms diffuse outward to form a Cu-rich interfacial layer at the boundary with the insulating film, eliminating the need for separate barrier film deposition processes while maintaining uniform thickness.
Solution Approach 2:
The barrier function is extracted from a separate barrier film layer and integrated into the Cu interconnection layer itself. The Cu layer performs dual functions: providing electrical conduction and forming a diffusion barrier at its interface with the insulating film.
2Reliability
If a conventional barrier film is formed to prevent Cu diffusion, then diffusion protection is improved, but interconnection resistance increases
Solution Approach 1:
The barrier function is merged with the Cu interconnection layer by forming a Cu-rich interfacial layer through heat treatment. This eliminates the need for separate barrier materials (such as Ta or TaN) and their associated deposition processes, thereby reducing interconnection resistance.
Solution Approach 2:
The Cu layer serves its own barrier function by generating a Cu-rich interfacial layer through controlled diffusion during heat treatment, eliminating dependence on external barrier materials.
3Device complexity
If alloy elements like Al, Mg, or Sn are added to Cu layer to form barrier-less structure, then barrier film deposition is eliminated, but electric resistance increases and reliability decreases
Solution Approach 1:
The Cu layer forms its own barrier through controlled self-diffusion during heat treatment, creating a Cu-rich interfacial layer without requiring alloying elements or external barrier materials, thereby maintaining both process simplicity and reliability.
Solution Approach 2:
The barrier formation mechanism is changed from chemical alloying to physical diffusion-controlled segregation. By controlling heat treatment parameters, Cu atoms segregate to the interface to form a protective layer, avoiding the resistance increase associated with alloy elements.
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 method achieves a reliable Cu interconnection structure with reduced resistance and improved reliability by forming a thin, stable oxide layer at the interface, eliminating the need for thick barrier films and avoiding the increased resistance associated with alloy elements.
Implementation Method 1
diffusing a predetermined metal element, such as Mn, into the interface between the Cu interconnection layer and the insulating film
Implementation Method 2
creating a stable compound like MnO to prevent Cu diffusion
Data Source
AI summary
A method of manufacturing a semiconductor device, including forming an opening in an interlevel insulating film disposed on a semiconductor substrate, forming an auxiliary film containing a predetermined metal element, to cover an inner surface of the opening, forming a main film to fill the opening after forming the auxiliary film, the main film containing, as a main component, Cu used as a material of an interconnection main layer, and performing a heat treatment before or after forming the main film, thereby diffusing the predetermined metal element of the auxiliary film onto a surface of the interlevel insulating film facing the auxiliary film, so as to form a barrier film on the interlevel insulating film within the opening, the barrier film containing, as a main component, a compound of the predetermined metal element with a component element of the interlevel insulating film.