Semiconductor Air-Spacer Structure for Gate-Contact Capacitance
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Solution Overview
Problem
As semiconductor technology advances to smaller geometries, stray capacitance between the gate structure and source/drain contacts of field effect transistors increases, posing challenges for switching speed, power consumption, and coupling noise reduction.
Innovation Solution
The formation of air-spacers surrounding gate structures instead of conventional solid dielectric spacers, which lowers the relative permittivity and thereby reduces stray capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solid dielectric spacers are used, then structural stability is maintained, but stray capacitance 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 stray capacitance between gate and source/drain contacts while maintaining the spacer's structural function through alternative design approaches.
Solution Approach 2:
The patent introduces an air gap as an intermediary medium between the gate structure and source/drain contacts. This air spacer acts as a mediator that electrically isolates the conductive elements while minimizing parasitic capacitance, replacing the traditional solid dielectric intermediary.
2Productivity
If geometry size is reduced, then production efficiency increases, but stray capacitance increases
Solution Approach 1:
The patent addresses the stray capacitance issue arising from scaled-down geometries by changing the dielectric parameter of the spacer material. Using air (εr≈1) instead of solid dielectric materials reduces the capacitance effect that becomes more pronounced at smaller feature sizes, thereby enabling continued scaling without proportionally increasing parasitic effects.
3Object-generated harmful factors
If low-k dielectric materials are used, then stray capacitance is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent extracts the dielectric material entirely from the spacer region, replacing it with air. This eliminates the need to manufacture, deposit, and pattern low-k dielectric layers, thereby reducing manufacturing complexity while achieving the desired low capacitance effect. The air spacer is formed through simpler processes such as selective removal of sacrificial layers.
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 decreases stray capacitance, enhancing switching speed, reducing power consumption, and minimizing coupling noise in semiconductor devices.
Implementation Method 1
the air-gap between the gate structure and the source/drain contacts reduces the relative permittivity and reduces stray capacitance 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.