Barrier-Free Metal Via Interface for Low Resistance
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Solution Overview
Problem
The challenge in forming vias for interconnects in integrated circuits is the increased resistance due to barrier layers at the via interfaces, which affects device performance, especially as technology scales down, and prior methods to remove these layers compromise device reliability by exposing copper to dielectrics.
Innovation Solution
A method of forming vias without barrier layers at the interface of the via and the metal line, using a metallic etch stop layer to protect the dielectric and prevent metal diffusion, allowing direct contact between the via fill and the metal line, thereby reducing resistance and maintaining device reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If barrier layers are present at the via interface with metal lines, then device reliability is maintained by preventing copper diffusion into dielectrics, but via resistance increases affecting device performance
Solution Approach 1:
The patent removes the barrier layer from the via interface with the metal line, extracting only the necessary barrier function at the trench interface while eliminating the resistive barrier at the via interface. This allows direct copper-to-copper contact in the via, reducing resistance while maintaining reliability through the etch stop layer's diffusion barrier function at the appropriate location.
Solution Approach 2:
The patent introduces a metallic etch stop layer as an intermediary element that performs the diffusion barrier function. This etch stop layer is positioned at the trench interface with the dielectric, mediating between the copper metal line and the dielectric material, thereby preventing copper diffusion without requiring a barrier layer at the via interface.
2Object-affected harmful factors
If barrier layers are removed from via interfaces to reduce resistance, then via resistance decreases improving device performance, but copper diffusion into dielectrics is enabled compromising device reliability
Solution Approach 1:
The metallic etch stop layer serves as a mediator that provides the necessary diffusion barrier function. It is positioned between the copper metal line and the dielectric material at the trench interface, enabling direct copper contact in the via (reducing resistance) while simultaneously preventing copper diffusion into the dielectric (maintaining reliability).
Solution Approach 2:
The patent extracts the barrier function from the via interface and relocates it to the trench interface through the metallic etch stop layer. This separation allows the via interface to be barrier-free (low resistance) while the trench interface maintains the diffusion barrier function (reliability).
Data Source
AI summary
An electrical communication structure that includes a plurality of metal line levels, a first metal line in a first metal line level of the plurality of line levels, and a second metal line in an upper metal line level of the plurality of line levels. A base of the second metal line is atop a metal etch stop layer that is aligned with edges of the second metal line. The electrical communication structure further includes a via that extends from the first metal line to the second metal line through the plurality of line levels. the via is not in electrical communication with at least one an intermediate metal line within the plurality of line levels between the first metal line level and the upper metal line level. The via has a metal fill that is in direct contact with a metal fill of the first metal line.