Air Spacer Ring Structure for Low-Capacitance Interconnects
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Solution Overview
Problem
Conventional methods for forming air spacers between metal lines in integrated circuit devices require removing and re-depositing dielectric materials, which is costly and involves planarization processes, increasing manufacturing costs and complexity.
Innovation Solution
A method where a sacrificial spacer is formed around conductive features, allowing for the direct creation of air spacers without the need to remove and re-fill dielectric materials, thus eliminating the need for costly planarization processes, by etching and removing the sacrificial spacer to leave air spacers surrounding the conductive features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods are used to form air spacers by removing and re-depositing dielectric materials, then air spacers can be formed between metal lines, but the manufacturing cost increases and process complexity increases due to required planarization processes
Solution Approach 1:
The patent extracts the essential function of forming air spacers by directly removing sacrificial dielectric material between conductive features, eliminating the need to re-deposit dielectric material and perform planarization processes. This extraction approach maintains the air spacer formation capability while removing unnecessary process steps.
Solution Approach 2:
Instead of the conventional approach of removing dielectric material then re-depositing it to form air spacers, the patent inverts the process by directly removing sacrificial dielectric material and leaving air spaces without re-deposition. This inversion eliminates the planarization requirement and reduces process complexity.
2Reliability
If conventional methods are used to form air spacers with dielectric material removal and re-deposition, then air spacers are formed, but manufacturing costs increase due to additional planarization processes
Solution Approach 1:
The patent extracts only the essential step of removing sacrificial dielectric material to form air spacers, eliminating the costly re-deposition and planarization steps. This extraction maintains the functional outcome while reducing manufacturing cost.
Solution Approach 2:
The patent uses sacrificial dielectric material that is intentionally deposited and then completely removed to form air spacers. This disposable approach eliminates the need for expensive re-deposition processes, as the sacrificial material serves its purpose and is discarded, leaving only the desired air spacer structure.
3Object-affected harmful factors
If low-k dielectric layers are used to reduce parasitic capacitance, then parasitic capacitance is reduced, but the dielectric material occupies space that could be used for air spacers
Solution Approach 1:
The patent changes the dielectric constant parameter by replacing solid dielectric material with air (k=1.0) in the regions between conductive features. This parameter change achieves the lowest possible parasitic capacitance while maintaining the structural integrity of the interconnect system.
Solution Approach 2:
The patent creates a porous structure by forming air spaces between conductive features, effectively using air as the dielectric material. This porous approach maximizes the reduction of parasitic capacitance by eliminating solid dielectric material from the critical regions between interconnects.
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 reduces parasitic capacitance between neighboring conductive features and lowers manufacturing costs by eliminating the need for dielectric material refilling and planarization, while maintaining uniform air spacers with minimal variation.
Implementation Method 1
The etching of the low-k dielectric layer may involve forming a patterned hard mask over the low-k dielectric material, and using the patterned hard mask as an etching mask to form trenches.
Data Source
AI summary
A method includes etching a dielectric layer to form an opening. A first conductive feature underlying the dielectric layer is exposed to the opening. A sacrificial spacer layer is deposited to extend into the opening. The sacrificial spacer layer is patterned. A bottom portion of the sacrificial spacer layer at a bottom of the opening is removed to reveal the first conductive feature, and a vertical portion of the sacrificial spacer layer in the opening and on sidewalls of the dielectric layer is left to form a ring. A second conductive feature is formed in the opening. The second conductive feature is encircled by the ring, and is over and electrically coupled to the first conductive feature. At least a portion of the ring is removed to form an air spacer.