SOI RF Device Deep Trench Isolation for Signal Distortion
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Solution Overview
Problem
Conventional SOI RF devices suffer from signal distortion due to alterations in substrate electrical characteristics caused by RF signal amplification, along with high manufacturing costs and unsuitability for mass production.
Innovation Solution
An SOI RF device is designed with a silicon substrate, a buried oxide layer, a device layer including an RF device, a first dielectric layer, a deep trench structure extending through the layers to the substrate interface, and a second dielectric layer, which helps in preventing signal distortion and reducing manufacturing complexity and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional SOI RF devices are used, then complete isolation between active layer and substrate is achieved, but signal distortion occurs due to substrate electrical characteristic alterations during RF signal amplification
Solution Approach 1:
The invention extracts the problematic substrate portion by forming a deep trench that removes a columnar region of the substrate directly beneath the RF device. This extracted substrate region eliminates the source of electrical characteristic alterations that cause signal distortion, while the buried oxide layer maintains complete isolation between the active layer and remaining substrate.
Solution Approach 2:
The invention introduces an intermediary deep trench structure filled with dielectric material between the RF device and the substrate. This intermediary structure acts as a mediator that prevents direct electrical interaction between the RF device and substrate, blocking the harmful electrical characteristic alterations from propagating to cause signal distortion.
2Reliability
If conventional SOI RF device manufacturing is used, then functional devices are produced, but manufacturing cost is high and process conditions are critical
Solution Approach 1:
The manufacturing process is segmented into distinct sequential steps: forming the deep trench, filling it with dielectric material, and planarizing the surface. This segmentation allows each step to be independently optimized and controlled, reducing overall process complexity and making the manufacturing more suitable for mass production while maintaining device functionality.
Solution Approach 2:
The deep trench structure is formed preliminarily before completing the RF device fabrication. This preliminary action prepares the substrate in advance by removing problematic regions and creating a stable foundation, which simplifies subsequent processing steps and reduces the need for critical process conditions during later device formation stages.
Data Source
AI summary
A silicon-on-insulator (SOI) radio-frequency (RF) device is disclosed, the SOI RF device includes: a silicon substrate; a buried oxide layer formed on the silicon substrate; a device layer formed on the buried oxide layer, the device layer including an RF device; a first dielectric layer covering the device layer; a deep trench structure extending through, from the top downward, the first dielectric layer, the silicon device layer and the buried oxide layer to an interface between the buried oxide layer and the silicon substrate; and a second dielectric layer covering both of the first dielectric layer and the deep trench structure. The SOI RF device is capable of improving signal transmission characteristics and preventing signal distortion, and can be easily manufactured with lower cost in less critical process conditions. A method of forming such an SOI RF device is also disclosed.