Air-Spacer Gate Structure for Lower Stray Capacitance
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Solution Overview
Problem
As semiconductor technology advances to smaller geometries, the shrinking distances between gate structures and source/drain contacts in field effect transistors lead to increased stray capacitance, negatively impacting switching speed, power consumption, and coupling noise.
Innovation Solution
The formation of air-spacers surrounding gate structures is introduced, replacing conventional solid dielectric spacers, thereby reducing the relative permittivity and stray capacitance between the gate and source/drain contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solid dielectric spacers are used, then structural integrity is maintained, but stray capacitance between gate and source/drain contacts increases
Solution Approach 1:
The patent changes the dielectric parameter (relative permittivity) of the spacer material from solid dielectric (high permittivity) to air (low permittivity). This parameter change directly reduces the stray capacitance between gate and source/drain contacts while maintaining the spacer's structural function through alternative support mechanisms.
Solution Approach 2:
The patent employs a composite structure combining air (as the low-k dielectric material) with surrounding solid dielectric layers and gate structures. This composite approach allows the air-spacer to reduce capacitance while the composite structure as a whole maintains structural integrity through the surrounding solid materials.
2Productivity
If geometry size is reduced to increase functional density, then production efficiency improves, but stray capacitance increases due to reduced distances between components
Solution Approach 1:
The patent applies local quality by introducing air-spacers specifically in the regions between gate and source/drain contacts where capacitance reduction is most critical. This localized application of low-k material (air) targets the specific problem areas without requiring changes to the overall device geometry or functional density.
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 effectively lowers stray capacitance, enhancing switching speed, reducing power consumption, and minimizing coupling noise in semiconductor devices.
Implementation Method 1
the air-gap between the seal spacer and the contact etch stop layer reducing a relative permittivity between the gate structure and the source/drain contacts
Data Source
AI summary
A semiconductor device includes a substrate; two source/drain (S/D) regions over the substrate; a gate stack over the substrate and between the two S/D regions; a spacer layer covering sidewalls of the gate stack; an S/D contact metal over one of the two S/D regions; a first dielectric layer covering sidewalls of the S/D contact metal; and an inter-layer dielectric (ILD) layer covering the first dielectric layer, the spacer layer, and the gate stack, thereby defining a gap. A material of a first sidewall of the gap is different from materials of a top surface and a bottom surface of the gap, and a material of a second sidewall of the gap is different from the materials of the top surface and the bottom surface of the gap.