Composite Substrate Grooves and Charge Traps for RF Loss Reduction
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Solution Overview
Problem
Substrates with insulating buried layers in radio frequency applications experience significant radio frequency losses due to stringent electrical property requirements not being met, leading to crosstalk and high-frequency signal attenuation.
Innovation Solution
A composite substrate is designed with a supporting substrate layer, a buried layer featuring grooves that penetrate partially, and a growth substrate layer, where a charge trapping region beneath the grooves enhances resistivity by depleting charges and a metal silicide layer reduces interface states, while the grooves in the buried layer attenuate stress for improved mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a substrate with an insulating buried layer is used in radio frequency applications, then the substrate provides structural support and electrical isolation, but radio frequency losses occur due to insufficient electrical properties
Solution Approach 1:
The patent introduces charge trapping regions with specific doping concentrations at particular locations beneath the grooves in the buried layer. This creates local variations in electrical properties, forming depletion regions that selectively block charge carriers in critical areas while maintaining overall substrate functionality, thereby reducing radio frequency losses without compromising electrical isolation
Solution Approach 2:
The patent creates a composite structure combining the supporting substrate layer, the buried layer with grooves, and the growth substrate layer. This multi-layer composite design integrates mechanical support from the substrate with enhanced electrical isolation from the buried layer and charge trapping regions, achieving both structural integrity and reduced radio frequency losses
2Reliability
If the buried layer is made thicker to improve electrical isolation, then charge blocking capability increases, but mechanical strength decreases and deformation occurs during epitaxial processes
Solution Approach 1:
The patent segments the buried layer by introducing grooves that partially penetrate it, dividing the continuous layer into regions separated by these grooves. This segmentation allows the buried layer to maintain adequate thickness for charge blocking while the grooves provide stress relief, preventing deformation during epitaxial growth
Solution Approach 2:
The grooves in the buried layer create a porous or hollow structure within the layer. This porous design reduces the overall material volume in the buried layer, decreasing mechanical stress and preventing deformation during epitaxial processes while still maintaining sufficient charge blocking capability through the remaining material and associated charge trapping regions
3Stress or pressure
If the supporting substrate layer is made thinner to reduce stress, then mechanical stress on the growth substrate decreases, but electrical isolation and charge trapping capability are reduced
Solution Approach 1:
The patent concentrates charge trapping regions with high doping concentrations in specific locations beneath the grooves rather than uniformly throughout the substrate. This localized approach enhances electrical isolation and charge blocking capability at critical interfaces while keeping the overall substrate thickness reduced to minimize mechanical stress
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 solution effectively reduces radio frequency losses and enhances the mechanical strength of the composite substrate, enabling high-frequency and low-loss semiconductor devices by increasing resistivity and preventing deformation during epitaxial processes.
Implementation Method 1
the supporting substrate layer includes a charge trapping region beneath the plurality of grooves
Implementation Method 2
an ion is doped in a material of the charge trapping region
Data Source
AI summary
A composite substrate includes a supporting substrate layer, a buried layer and a growth substrate layer stacked in sequence. The buried layer is provided with a plurality of grooves at least partially penetrating the buried layer, the supporting substrate layer includes a charge trapping region beneath the plurality of grooves, and on a plane where the supporting substrate layer is located, shapes of projections of the charge trapping region and a corresponding groove overlap. The charge trapping region is arranged on the supporting substrate layer, and the charge trapping region is used to deplete charges of the supporting substrate layer, so as to increase resistivity of the composite substrate, reducing an impact of crosstalk; and the buried layer is provided with grooves, which may attenuate a stress transmitted from the growth substrate layer to the supporting substrate layer, so as to enhance a mechanical strength of the composite substrate.