Air Bridge Segmentation for Semiconductor Mechanical Strength
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Solution Overview
Problem
Existing semiconductor devices with multi-finger structures, such as FETs, face mechanical weakness in air bridges due to external forces, leading to a high likelihood of air bridges being crushed, which affects the device's reliability and performance.
Innovation Solution
The semiconductor device incorporates first air bridges extending over bus lines and second air bridges that connect the first air bridges, both formed using a liftoff process with a resist, to distribute external forces effectively and enhance mechanical strength by providing additional support and spacing to prevent contact with gate bus lines and fingers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air bridges are provided to avoid contact between drain fingers and source bus line, then contact is prevented, but mechanical strength is insufficient and air bridges may be crushed due to external force
Solution Approach 1:
The air bridge structure is divided into multiple segments: first air bridges extending from source fingers over the source bus line, and second air bridges extending from drain fingers over the drain bus line. This segmentation allows each air bridge segment to be independently optimized for mechanical strength while maintaining the electrical isolation function.
Solution Approach 2:
Multiple air bridges are combined to form a composite support structure. The first air bridges and second air bridges work together to provide distributed mechanical support across the bus lines, preventing any single air bridge from bearing excessive external force that would cause crushing.
2Power
If multi-finger structure is used for RF amplification, then amplification performance is improved, but complexity of interconnection increases
Solution Approach 1:
The interconnection structure utilizes vertical air bridges to create three-dimensional routing, allowing bus lines to cross under air bridges without electrical contact. This vertical dimension resolves the complexity of interconnecting multiple fingers while maintaining clear signal paths and reducing parasitic effects.
Data Source
AI summary
A semiconductor device includes a semiconductor layer, an active region defined in the semiconductor layer, first fingers provided on the active region and arranged in parallel with respect to a first direction, second fingers provided on the active region and interleaved with the first fingers, a bus line that is provided on an outside of the active region and interconnects the first fingers, first air bridges that are provided on the outside of the active region and are extended over the bus line, and that are connected to the second fingers, and second air bridges that are provided on the outside of the active region and are arranged in a second direction which crosses to the first direction, and that interconnect the first air bridges.