Air-Gap Interconnect Structure for Lower Parasitic Capacitance
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Solution Overview
Problem
As integrated circuit transistor densities increase, capacitive coupling between adjacent interconnects leads to higher parasitic capacitance, slowing circuit speeds and negatively impacting device performance, while current low K dielectric materials introduce manufacturing complexity and cost due to incompatibility with conventional processes.
Innovation Solution
A semiconductor structure with air gaps between conductive lines and dielectric pillars, sealed by sealing caps, utilizing conventional materials for dielectric pillars to reduce parasitic capacitance without requiring new manufacturing techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional low K dielectric materials (HSQ, SiLK, Black Diamond, Coral) are used to reduce parasitic capacitance, then capacitive coupling between adjacent interconnects is reduced, but manufacturing complexity and costs increase due to incompatibility with conventional semiconductor manufacturing processes
Solution Approach 1:
The patent changes the dielectric constant parameter by introducing air gaps (κ≈1) between conductive interconnects through selective removal of mandrels, rather than changing the material composition. This achieves lower parasitic capacitance while using conventional semiconductor manufacturing processes like deposition, etching, and CMP, avoiding the need for exotic materials like HSQ or SiLK
Solution Approach 2:
The patent creates a porous structure by forming air gaps between interconnects through selective removal of mandrels. The air-filled voids act as low-K dielectric regions, reducing capacitive coupling while maintaining compatibility with standard manufacturing processes. The porous structure is achieved through conventional etching and deposition techniques rather than requiring special low-K materials
2Productivity
If feature sizes are shrunk to increase transistor density, then integrated circuit transistor density increases, but capacitive coupling between adjacent interconnects increases, slowing circuit speeds
Solution Approach 1:
The patent segments the dielectric medium by introducing air gaps between adjacent interconnects, dividing the continuous dielectric into isolated regions. This segmentation reduces the capacitive coupling area between neighboring conductors, allowing higher transistor density without proportionally increasing parasitic capacitance, thereby maintaining circuit speed
Solution Approach 2:
The patent introduces air gaps as intermediary regions between conductive interconnects. These air-filled spaces act as mediators that reduce the electric field coupling between adjacent lines, lowering parasitic capacitance effects even as feature sizes shrink and transistor density increases
3Object-affected harmful factors
If air gaps are introduced between conductive lines to reduce parasitic capacitance, then dielectric constant is reduced, but manufacturing process complexity increases without using conventional materials
Solution Approach 1:
The patent performs preliminary action by forming mandrels in the desired gap locations before depositing the dielectric material. These mandrels are subsequently selectively removed to create air gaps, ensuring precise gap formation and alignment with conventional deposition and etching processes, thereby maintaining manufacturing ease
Solution Approach 2:
The patent uses self-service by forming air gaps through selective removal of sacrificial mandrels rather than requiring direct deposition of low-K materials. The conventional dielectric materials and processing techniques serve themselves to create the low-K air-filled regions, eliminating the need for special materials like HSQ or SiLK while achieving the same capacitive reduction effect
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
The structure achieves lower dielectric constant and reduced parasitic capacitance, enhancing device performance and maintaining compatibility with conventional manufacturing processes, thus reducing costs and improving reliability.
Implementation Method 1
capacitive coupling between adjacent interconnects, metal lines or other elements also increases. The increased capacitive coupling in turn results in higher parasitic capacitance
Data Source
AI summary
The present disclosure provides a semiconductor structure including a base layer, a first conductive line disposed on the base layer, a first dielectric pillar disposed on the base layer, a second dielectric pillar disposed on the base layer, a first liner, and a second liner. The first conductive line is disposed between the first dielectric pillar and the second dielectric pillar. The first liner encloses a first air gap, and is disposed between the first dielectric pillar and the first conductive line. The second liner encloses a second air gap, and is disposed between the second dielectric pillar and the first conductive line.