Trap-Rich Layer Immobilizes Surface Conduction for RF Linearity
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Solution Overview
Problem
High resistivity Silicon substrates in RF devices can exhibit non-linear characteristics due to surface conduction layers, leading to harmonic distortion, which is difficult to mitigate without increasing complexity or signal loss using conductive shielding layers.
Innovation Solution
A trap-rich layer, such as a polycrystalline Silicon layer, is used to immobilize the surface conduction layer by trapping carriers, preventing capacitance and inductance changes at RF frequencies, thereby reducing harmonic distortion without the need for conductive shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a conductive shielding layer is incorporated to reduce non-linear characteristics, then harmonic distortion is reduced, but device complexity and signal loss increase
Solution Approach 1:
The patent extracts the harmful surface conduction layer by forming a trap-rich layer that captures and immobilizes surface carriers, removing the source of non-linear capacitance and conductance variations without requiring an additional conductive shielding layer
Solution Approach 2:
The trap-rich layer acts as an intermediary between the semiconductor substrate and the RF signal path, capturing carriers that would otherwise form a variable surface conduction layer, thereby eliminating the need for a conductive shielding layer while maintaining signal integrity
2Object-generated harmful factors
If a conductive shielding layer is incorporated to reduce non-linear characteristics, then harmonic distortion is reduced, but signal loss increases
Solution Approach 1:
The patent extracts the harmful surface conduction layer by forming a trap-rich layer that captures and immobilizes surface carriers, removing the source of non-linear capacitance and conductance variations without requiring an additional conductive shielding layer that would cause signal loss
3Reliability
If the doping level is kept very low to maintain high resistivity, then the substrate behaves as a dielectric at RF frequencies, but surface conduction layers form due to oxide charges and weak electric fields
Solution Approach 1:
The trap-rich layer is formed in advance to preemptively capture carriers before they can form a variable surface conduction layer, preventing the harmful effect of non-linear capacitance and conductance variations before it occurs
Solution Approach 2:
The patent converts the harmful surface conduction layer into a beneficial immobilized carrier layer by using the trap-rich layer to capture carriers, transforming the source of non-linearity into a stable, non-variable structure that improves RF performance
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 trap-rich layer effectively reduces or eliminates harmonic distortion in RF signals by immobilizing the surface conduction layer, improving signal integrity without increasing complexity or signal loss.
Implementation Method 1
The trap-rich layer may have a high density of traps that trap carriers from the surface conduction layer
Data Source
AI summary
The present invention relates to using a trap-rich layer, such as a polycrystalline Silicon layer, over a semiconductor substrate to substantially immobilize a surface conduction layer at the surface of the semiconductor substrate at radio frequency (RF) frequencies. The trap-rich layer may have a high density of traps that trap carriers from the surface conduction layer. The average release time from the traps may be longer than the period of any present RF signals, thereby effectively immobilizing the surface conduction layer, which may substantially prevent capacitance and inductance changes due to the RF signals. Therefore, harmonic distortion of the RF signals may be significantly reduced or eliminated. The semiconductor substrate may be a Silicon substrate, a Gallium Arsenide substrate, or another substrate.