High-Frequency Component Structure with Low Stray Capacitance
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Solution Overview
Problem
High-frequency electronic components face significant stray capacitance issues due to non-negligible capacitances between components, especially in solid substrate and semiconductor-on-insulator (SOI) structures, which hinder efficient operation at high frequencies.
Innovation Solution
A structure featuring heavily-doped islands of a second conductivity type in a silicon substrate, with insulating regions between components, reduces stray capacitances by creating a depleted area that acts as an insulator, utilizing a substrate with a resistivity of 1000 ohms.cm or higher to minimize inter-component capacitance at frequencies above 1 GHz.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If components are formed in a solid substrate or SOI structure, then electronic components can be manufactured with standard processes, but stray capacitances between components become non-negligible and hinder high-frequency operation
Solution Approach 1:
Heavily-doped islands of opposite conductivity type are introduced as intermediary elements between the silicon support and the components. These islands create depleted areas that act as additional insulating barriers, effectively reducing stray capacitance between neighboring components while maintaining compatibility with standard semiconductor manufacturing processes
Solution Approach 2:
The substrate is modified locally by creating heavily-doped regions only in specific areas where components are located. This local modification creates depleted areas beneath each component that reduce stray capacitance without affecting the overall substrate structure or requiring complete redesign of the manufacturing process
2Reliability
If insulating layers are used to separate components, then vertical insulation is achieved, but lateral stray capacitances between neighboring components remain significant at high frequencies
Solution Approach 1:
The insulation approach is extended from a single horizontal insulating layer to a three-dimensional structure combining the insulating layer with heavily-doped islands beneath each component. This creates depleted areas that provide additional insulation in the vertical dimension, effectively reducing lateral stray capacitance between neighboring components
3Object-affected harmful factors
If heavily-doped islands are introduced to reduce stray capacitance, then insulating properties improve, but device structure becomes more complex
Solution Approach 1:
The doping concentration parameter is dramatically increased in specific regions to create heavily-doped islands. This parameter change transforms conductive regions into insulating depleted areas, reducing stray capacitance. The islands are positioned and sized to provide effective isolation while minimizing additional structural complexity
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 values, enabling reliable high-frequency operation by making the substrate's insulating properties more pronounced, particularly at frequencies much lower than 1 GHz, thus improving performance in high-frequency circuits.
Implementation Method 1
the silicon support has, at least in the vicinity of its portion in contact with the insulating layer, heavily-doped islands of a second conductivity type, the distance between islands being smaller than twice the extent of the space charge area created by the junction with the silicon support
Implementation Method 2
the distance between islands being smaller than twice the extent of the space charge area created by the junction with the silicon support
Data Source
AI summary
A structure including at least two neighboring components, capable of operating at high frequencies, formed in a thin silicon substrate extending on a silicon support and separated therefrom by an insulating layer, the components being laterally separated by insulating regions. The silicon support has, at least in the vicinity of its portion in contact with the insulating layer, a resistivity greater than or equal to 1,000 ohms.cm.