Semiconductor Airgap Formation via Selective High-k Etching
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Solution Overview
Problem
Current etch processes struggle to maintain selectivity across various materials in semiconductor fabrication, especially as device sizes shrink, leading to increased parasitic capacitance and performance issues due to the use of high-k materials with high dielectric constants.
Innovation Solution
The formation of an airgap between the gate structure and spacer material, combined with selective deposition of high-k materials, reduces parasitic capacitance by utilizing a sacrificial material that is sensitive to gentle etching, allowing for consistent airgap creation and minimizing the presence of high-k materials in critical areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If high-k materials are used to reduce device size, then device miniaturization is improved, but parasitic capacitance increases leading to performance degradation
Solution Approach 1:
The patent extracts and removes the harmful high-k material from the region between the gate and source/drain contacts. By selectively etching away the high-k material in this specific area while preserving it elsewhere, the invention eliminates the parasitic capacitance source without sacrificing the overall device miniaturization benefits.
Solution Approach 2:
The patent applies different material properties to different regions: high-k material is retained in areas where it provides benefit (such as under the gate for capacitance enhancement) but removed from areas where it creates harm (between gate and source/drain). This localized differentiation resolves the contradiction by optimizing material presence based on spatial function.
2Object-generated harmful factors
If selective etching is used to remove high-k material, then parasitic capacitance is reduced, but etch selectivity across multiple materials becomes difficult to maintain
Solution Approach 1:
The patent introduces an intermediary sacrificial material layer that facilitates selective removal of high-k material. This sacrificial layer is specifically designed to be etched away first, creating access to the high-k material beneath while protecting other structures. The intermediary enables the complex selective etching to proceed in a controlled, stepwise manner.
Solution Approach 2:
The patent performs preliminary actions by first depositing the sacrificial material layer and performing initial etching steps to create access pathways before removing the high-k material. This preliminary preparation simplifies the subsequent high-k material removal by establishing controlled access points and protecting vulnerable areas.
3Object-generated harmful factors
If airgap formation is implemented, then parasitic capacitance is reduced by up to 50%, but additional process steps are required
Solution Approach 1:
The patent merges the airgap formation process with the existing high-k material removal sequence. By integrating the sacrificial material deposition and etching steps into the overall gate-last process flow, the invention creates the airgap structure without requiring completely separate process modules. The steps are combined in a way that achieves parasitic capacitance reduction while minimizing additional process complexity.
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 by up to 50% compared to conventional gate-last processes, improving device performance and reducing power consumption by minimizing the dielectric constant between the gate and source/drain materials.
Implementation Method 1
The methods may include etching the first material. The etching may form an airgap adjacent the gate structure.
Implementation Method 2
forming a high-k material on a floor of a trench
Implementation Method 3
reduces parasitic capacitance by up to 50% compared to conventional gate-last processes, improving device performance and reducing power consumption by minimizing the dielectric constant between the gate and source/drain materials
Data Source
AI summary
Processing methods may be performed to form an airgap in a semiconductor structure. The methods may include forming a high-k material on a floor of a trench. The trench may be defined on a semiconductor substrate between sidewalls of a first material and a spacer material. The methods may include forming a gate structure on the high-k material. The gate structure may contact the first material along each sidewall of the trench. The methods may also include etching the first material. The etching may form an airgap adjacent the gate structure.