Ruthenium Oxide Liner for Low-Resistance BEOL Copper Interconnects
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Solution Overview
Problem
Copper used in back end of line (BEOL) metallization layers and vias in electronic devices exhibits high diffusion rates, leading to increased resistivity and semiconductor device failures, which decrease electrical performance and manufacturing yield.
Innovation Solution
The use of ruthenium (Ru) or a combination of ruthenium and ruthenium oxide (RuOx) in BEOL metallization layers and vias, either as part of a single or dual damascene process, to reduce contact resistance, promote adhesion between layers, and minimize defects such as voids and discontinuities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper is used in BEOL metallization layers and vias, then electrical conductivity is improved, but diffusion rate increases leading to increased resistivity and device failures
Solution Approach 1:
A ruthenium oxide film is introduced as an intermediary layer between the copper interconnect and the surrounding dielectric material. This mediator allows copper to maintain its low resistivity while preventing copper atoms from diffusing into the dielectric, thus resolving the contradiction between electrical conductivity and diffusion control
Solution Approach 2:
The patent employs a composite structure combining copper interconnects with a ruthenium oxide film. This composite material system leverages the high electrical conductivity of copper while the ruthenium oxide component provides diffusion barrier properties, achieving both low resistivity and prevention of harmful diffusion
2Reliability
If copper is used in BEOL structures, then contact resistance decreases, but adhesion between layers deteriorates
Solution Approach 1:
The ruthenium oxide film serves as an adhesion promoter and intermediary layer between copper and dielectric materials. It maintains low contact resistance for electrical performance while providing strong bonding interfaces that prevent delamination, thus resolving the adhesion problem associated with copper interconnects
3Ease of manufacture
If copper is used in BEOL metallization, then manufacturing cost is reduced, but defect formation increases
Solution Approach 1:
The ruthenium oxide film is deposited on the dielectric surface before copper filling in a preliminary step. This pre-treatment prevents defect formation during subsequent copper electroplating by providing a controlled interface that eliminates voids and discontinuities, thereby maintaining manufacturing precision while using cost-effective copper
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 decreases the overall resistivity of BEOL structures, enhances electrical performance, and increases manufacturing yield by acting as a diffusion barrier and improving layer adhesion.
Implementation Method 1
ruthenium oxide film 320...acts as a diffusion barrier
Implementation Method 2
promote adhesion between layers
Data Source
AI summary
Selective ruthenium and selective ruthenium oxide may be used in single damascene processes and/or dual damascene processes to form BEOL metallization layers and vias of an electronic device. A selective ruthenium liner may be formed to achieve a low contact resistance and a low sheet resistance for the BEOL metallization layers and vias, to promote adhesion between the various layers and materials in the BEOL metallization layers and vias, and/or to reduce or eliminate defects (such as voids and discontinuities) in the BEOL metallization layers and vias.