Local Interconnect Air Gap Structure for Capacitance Reduction
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Solution Overview
Problem
Integrated circuits face challenges with high capacitance due to the close spacing of conductive lines, which affects performance, even when using low-k materials for isolation.
Innovation Solution
The introduction of voids or airgaps between adjacent conductive lines in interconnect structures, which are closed at the upper end by insulating material, reduces capacitance and is particularly effective for tight pitch interconnects in logic structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conductive lines are spaced closely together to increase density, then productivity is improved, but capacitance increases causing performance degradation
Solution Approach 1:
The patent introduces air gaps (void spaces) between adjacent conductive lines in the interconnect structure. These air gaps act as porous regions with extremely low dielectric constant (k≈1), replacing the traditional solid dielectric material. This reduces the capacitance between closely spaced conductive lines while maintaining high interconnect density, directly resolving the technical contradiction between productivity and harmful capacitive effects.
Solution Approach 2:
The patent creates a composite interconnect structure combining conductive lines, air gaps (void spaces), and dielectric materials. The air gaps serve as a low-k dielectric component within the composite structure, providing electrical isolation with minimal capacitance. This composite approach enables close spacing of conductors while maintaining performance by leveraging the unique properties of air as a dielectric medium.
2Object-generated harmful factors
If low-k materials are used for isolation, then capacitance is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent removes the dielectric material from specific regions between conductive lines to create air gaps. This extraction approach replaces complex low-k material deposition and processing with a simpler sequence: deposit dielectric, pattern openings, etch through to expose conductors, then fill with conductive material. The air gaps are formed by the absence of material rather than by introducing a special low-k material, significantly simplifying the manufacturing process while achieving the same capacitance reduction effect.
Data Source
AI summary
An integrated circuit includes a base comprising an insulating dielectric. A plurality of conductive lines extends vertically above the base in a spaced-apart arrangement, the plurality including a first conductive line and a second conductive line adjacent to the first conductive line. A void is between the first and second conductive lines. A cap of insulating material is located above the void and defines an upper boundary of the void such that the void is further located between the base and the cap of insulating material. In some embodiments, one or more vias contacts an upper end of one or more of the conductive lines.