Air Gap Regions in RF Semiconductor Devices
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Solution Overview
Problem
RF semiconductor devices, particularly those operating in the millimeter-wave band, face significant challenges due to high parasitic components such as parasitic inductance, capacitance, and resistance, which degrade performance and are exacerbated by the extremely high operating frequencies, necessitating effective reduction methods.
Innovation Solution
The introduction of air gap regions in semiconductor devices, formed by creating trenches and sealing them with dielectric layers to position contact structures further away from gate structures, thereby reducing parasitic capacitance and resistance, is proposed. This involves a method where a dielectric layer is deposited over the semiconductor structure, trenches are formed between the contact and gate structures, and a second dielectric layer seals these trenches to create air gap regions adjacent to the contact structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If contact structures are positioned close to gate structures to reduce device area, then device area is reduced, but parasitic capacitance increases
Solution Approach 1:
An air gap region is introduced as an intermediary space between the contact structure and gate structure. This air gap acts as a mediator that electrically isolates the two structures while allowing them to remain in close physical proximity, thereby reducing parasitic capacitance without significantly increasing device area.
Solution Approach 2:
The air gap region is selectively positioned only in specific locations between contact structures and gate structures, rather than uniformly throughout the device. This localized approach reduces parasitic capacitance where it is most critical while minimizing the impact on overall device area.
2Object-generated harmful factors
If contact structures are positioned away from gate structures to reduce parasitic capacitance, then parasitic capacitance is reduced, but device area increases
Solution Approach 1:
The air gap serves as a compact intermediary that provides electrical isolation without requiring large physical separation distances. This allows contact structures to be positioned closer to gate structures than would be possible without the air gap, thereby reducing device area while maintaining low parasitic capacitance.
3Object-generated harmful factors
If air gap regions are introduced to reduce parasitic capacitance, then parasitic capacitance is reduced, but device complexity increases
Solution Approach 1:
The air gap formation process is merged with existing fabrication steps. The air gap region is created by selectively removing dielectric material that would otherwise be deposited as part of the standard interlayer dielectric process, thereby incorporating the parasitic reduction feature without adding significant process complexity.
4Object-generated harmful factors
If air gap regions are introduced to reduce parasitic components, then parasitic capacitance and resistance are reduced, but manufacturing complexity increases
Solution Approach 1:
The air gap formation is combined with the existing dielectric deposition and patterning processes. By using the same lithography and etching tools already required for other device features, the air gap regions are created without requiring additional manufacturing steps or specialized equipment.
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 incorporation of air gap regions significantly reduces parasitic capacitance and electrical resistance, enhancing the performance of RF semiconductor devices, especially at high frequencies, by minimizing signal losses and increasing switching speed, thereby improving reliability and data transmission rates.
Implementation Method 1
A first dielectric layer is deposited over the semiconductor structure between the first and second gate structures
Implementation Method 2
A second dielectric layer is deposited over the first and second trenches such that the second dielectric layer seals the first trench to form a first air gap region
Data Source
AI summary
A semiconductor device is provided, which includes an active region, a first structure, a second gate structure, a first gate dielectric sidewall, a second gate dielectric sidewall, a first air gap region, a second air gap region and a contact structure. The active region is formed over a substrate. The first and second gate structures are formed over the active region and between the first gate structure and the second gate structure are the first gate dielectric sidewall, the first air gap region, the contact structure, the second air gap region and a second gate dielectric sidewall.