Air Gap Interconnects via Sacrificial Layer Protection
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Solution Overview
Problem
Conventional methods for forming air gaps between neighboring conductive features in electronic devices often result in damage to conductive features, inconsistent gap formation, undesirable gap dimensions, and the presence of higher dielectric constant materials, which negatively impact device performance by increasing capacitive coupling and signal interference.
Innovation Solution
A method involving the formation of interconnect structures with a conductive and barrier material, followed by selective removal of dielectric and barrier materials to create trenches and air gaps, using a sacrificial material with slots to define the gap locations, and filling with an isolation material to maintain low dielectric constant air gaps between interconnect structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional subtractive processes (etching) are used to form air gaps, then air gaps can be created between conductive features, but the conductive features may be damaged
Solution Approach 1:
A sacrificial material is deposited over the conductive features before the air gap formation process. This sacrificial layer serves as a protective preliminary action that prevents etchant damage to the conductive features while allowing the air gaps to be formed through the dielectric material.
Solution Approach 2:
The sacrificial material acts as an intermediary layer between the etchant and the conductive features. It mediates the interaction by being selectively removed in specific regions while protecting the conductive features from direct exposure to the etchant, thus enabling air gap formation without damage.
2Productivity
If feature dimensions and spacing are reduced to increase integration density, then device integration level increases, but RC delay and cross-talk increase
Solution Approach 1:
Air gaps are selectively formed in specific local regions between conductive features rather than uniformly throughout the entire device. This local quality approach allows the dielectric constant to be reduced (k≈1) only where needed to minimize capacitive coupling and cross-talk, while maintaining other structural requirements in different regions.
Solution Approach 2:
The dielectric constant parameter is changed from typical dielectric materials (k=3-4) to air gaps (k≈1) in specific regions. This parameter change directly reduces the capacitive coupling between adjacent conductive features, thereby reducing RC delay and cross-talk effects.
3Stability of the object's composition
If higher dielectric constant materials remain between air gaps and conductive features, then material coverage is maintained, but capacitive coupling increases
Solution Approach 1:
Higher dielectric constant materials are selectively removed (taken out) from the regions between the air gaps and conductive features. The sacrificial material process enables this extraction by providing a template that guides selective removal, ensuring that only the necessary dielectric material remains to maintain structural integrity while minimizing capacitive coupling.
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 enhances the reliability and performance of electronic devices by reducing capacitive coupling and signal interference while preserving the integrity of conductive features and maintaining low dielectric constant materials within the air gaps, thereby improving feature density and reducing power dissipation.
Implementation Method 1
Conventional methods of form air gaps between the neighboring conductive features may result in one or more of undesirable damage to the conductive features (e.g., when a conductive material is subjected to a subtractive process, such as an etching process, to form the air gaps)
Data Source
AI summary
An electronic device comprises a dielectric structure, interconnect structures extending into the dielectric structure and having uppermost vertical boundaries above uppermost vertical boundaries of the dielectric structure, an additional barrier material covering surfaces of the interconnect structures above the uppermost vertical boundaries of the dielectric structure, an isolation material overlying the additional barrier material, and at least one air gap laterally intervening between at least two of the interconnect structures laterally-neighboring one another. Each of the interconnect structures comprises a conductive material, and a barrier material intervening between the conductive material and the dielectric structure. The at least one air gap vertically extends from a lower portion of the isolation material, through the additional barrier material, and into the dielectric structure. Electronic systems and method of forming an electronic device are also described.