Anchored Damascene Interconnects for Low-K Dielectric Reliability
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Solution Overview
Problem
Low-K dielectric materials used in semiconductor manufacturing exhibit reduced mechanical strength and adhesion, leading to issues like delamination during CMP and thermal mismatch stresses, which affect the reliability and yield of semiconductor devices.
Innovation Solution
A method is developed to form anchored conductive damascene interconnects within a multi-density dielectric layer, where a lower density portion with enlarged lateral dimensions forms anchoring steps, enhancing the structural stability and adhesion of metal fillings, and a refractory metal barrier layer is used to improve adhesive properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If low-K dielectric materials are used to reduce signal delay and power loss, then electrical performance is improved, but mechanical strength and adhesion are reduced
Solution Approach 1:
The dielectric layer is structured with different density regions: a first dielectric layer with higher density providing mechanical strength and adhesion, and a second dielectric layer with lower density providing electrical performance. This local differentiation allows each region to optimize for its specific function.
Solution Approach 2:
The patent uses a composite dielectric structure combining two different dielectric materials with different densities. The higher density dielectric provides mechanical support while the lower density dielectric provides electrical optimization, creating a composite system that achieves both mechanical strength and electrical performance.
2Speed
If low-K dielectric materials are used, then signal delay is reduced, but adhesion of overlying layers and metal filling is reduced
Solution Approach 1:
The adhesion-critical regions (interfaces with metal fillings and overlying layers) are positioned within or adjacent to the higher density dielectric layer, which provides superior adhesion properties. The lower density dielectric is used in regions where electrical performance is critical but adhesion requirements are lower.
Solution Approach 2:
The higher density dielectric layer is formed first, establishing a strong adhesion foundation before depositing the lower density dielectric layer. This preliminary action ensures that the structural and adhesive foundation is in place before adding the electrical optimization layer.
3Ease of manufacture
If conventional damascene structures are used in low-K dielectrics, then manufacturing is simplified, but resistance to stress migration and delamination is reduced
Solution Approach 1:
The anchoring features are localized at specific positions within the dielectric structure where stress concentration occurs. Rather than modifying the entire dielectric layer, the higher density material is strategically placed at interfaces and regions requiring enhanced stress resistance, while maintaining low-K properties in other regions.
Data Source
AI summary
An anchored conductive damascene buried in a multi-density dielectric layer and method for forming the same, the anchored conductive damascene including a dielectric layer with an opening extending through a thickness of the dielectric layer; wherein the dielectric layer comprises at least one relatively higher density portion and a relatively lower density portion, the relatively lower density portion forming a contiguous major portion of the dielectric layer; and, wherein the opening in the relatively lower density portion has a lateral dimension relatively larger compared to the relatively higher density portion to form anchoring steps.