Cross-Shaped Air Gap Layout for Low-Loss RF Switches
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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 the low loss of radio frequency transmission.
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 dielectric layer that covers the sidewalls, along with copper damascened conductive layers and specific dielectric and capping layers, to reduce parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
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 improvement effect is limited and the product of on-resistance and off-capacitance cannot be adequately reduced
Solution Approach 1:
The air gap is segmented into multiple distinct portions: a first air gap portion extending from the gate upward, a second air gap portion between contact plugs, and a third air gap portion between the gate and contact plugs. This segmentation allows each air gap to independently reduce specific parasitic capacitance components, achieving greater overall reduction in the product of on-resistance and off-capacitance compared to a single conventional air gap
Solution Approach 2:
The air gap structure extends in multiple spatial dimensions: vertically from the gate through the dielectric layer, horizontally between contact plugs, and diagonally between the gate and contact plugs. This multi-dimensional air gap configuration comprehensively reduces parasitic capacitance from various spatial directions, effectively lowering the product of on-resistance and off-capacitance
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 design effectively minimizes the product of on-resistance and off-capacitance, enhancing the low loss characteristic of radio-frequency switches.
Implementation Method 1
form an air gap in the dielectric layer above the gate to reduce the parasitic capacitance between the gate and adjacent contact plugs and wires
Data Source
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.