Cross-Like Air Gap Layout for Lower RF Switch Parasitic Capacitance
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Solution Overview
Problem
Conventional semiconductor structures for radio-frequency switches fail to adequately reduce the product of on-resistance and off-capacitance, limiting low loss performance in RF switches.
Innovation Solution
A semiconductor structure with a cross-like-shaped air gap is introduced, featuring a widened middle portion, tapered upper and lower portions, and an extension portion of the third dielectric layer that conforms to the sidewalls of the first and second dielectric layers, reducing parasitic capacitance between conductive layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional air gap is formed in the dielectric layer above the gate, then the parasitic capacitance between the gate and adjacent contact plugs and wires is reduced, but the off-capacitance improvement is still limited
Solution Approach 1:
The air gap is segmented into multiple portions: a first air gap portion extending from the gate top surface to the first dielectric layer, and a second air gap portion extending from the first dielectric layer to the second dielectric layer. This segmentation allows the air gap to be distributed across multiple regions, effectively reducing parasitic capacitance between the gate and adjacent conductive structures while improving off-capacitance reduction effectiveness
Solution Approach 2:
The air gap structure transitions from a conventional single-layer approach to a multi-layer dielectric structure with air gaps at different vertical levels. The first and second air gap portions are positioned at different heights above the gate, creating a three-dimensional air gap configuration that enhances capacitance reduction beyond what a single planar air gap can achieve
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 effectively decreases the off-capacitance of RF switches, enhancing the low loss characteristic of radio-frequency switches by minimizing parasitic capacitance, thereby improving the performance of RF switches.
Implementation Method 1
reduce the parasitic capacitance between the gate and adjacent contact plugs and wires
Data Source
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AI summary
A semiconductor structure with an air gap includes a dielectric stack having a first dielectric layer on a substrate, a second dielectric layer on the first dielectric layer, and a third dielectric layer on the second dielectric layer. A first conductive layer and a second conductive layer are disposed in the dielectric stack. The first conductive layer and the second conductive layer are coplanar. A cross-like-shaped air gap is disposed in the dielectric stack between the first and second conductive layers. An oxide layer is disposed on a sidewall of the second dielectric layer within the cross-like-shaped air gap.