Diamond RF Substrate Stack for CMOS-Compatible Harmonic Control
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Solution Overview
Problem
Current high-frequency device substrates, particularly those using silicon-based materials, face limitations in achieving superior high-frequency characteristics due to interference from harmonics and require further enhancement in performance.
Innovation Solution
A substrate for high-frequency devices is developed, featuring a support substrate with surface unevenness, a diamond layer, and a silicon oxide film layer, which improves thermal conductivity and insulating properties, reducing carrier mobility and enhancing high-frequency characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a silicon substrate with SOI structure is used, then compatibility with CMOS process and mass production capability are improved, but high-frequency characteristics are limited due to harmonic interference
Solution Approach 1:
The invention uses a diamond layer formed on the silicon substrate. Diamond has superior thermal conductivity and electrical insulation properties compared to silicon, which helps reduce harmonic interference and improves high-frequency characteristics while maintaining compatibility with existing silicon-based CMOS manufacturing processes.
Solution Approach 2:
The invention changes the material parameter of the substrate from pure silicon to a composite structure with diamond layer. This parameter change (material composition) fundamentally improves the thermal and electrical properties, reducing carrier mobility and harmonic distortion, thereby enhancing high-frequency performance.
2Reliability
If the resistivity of the support substrate is increased, then harmonic characteristics are improved, but manufacturing complexity increases
Solution Approach 1:
Instead of simply increasing the resistivity of the silicon substrate through doping, the invention introduces a diamond layer that naturally provides both high resistivity and superior thermal conductivity. This composite approach achieves the desired electrical isolation without requiring complex heavily-doped silicon structures.
3Reliability
If a charge storage layer (TR layer) is introduced, then cross-talk prevention is improved, but device complexity increases
Solution Approach 1:
The diamond layer inherently provides charge storage capability due to its wide bandgap and ability to trap carriers. This eliminates the need for a separate TR layer while achieving the same cross-talk prevention function, thereby reducing device complexity.
Solution Approach 2:
The invention extracts the charge storage function from the traditional TR layer concept and integrates it into the diamond layer itself. The diamond layer simultaneously provides thermal management, electrical insulation, and charge storage, consolidating multiple functions into a single layer.
4Temperature
If diamond is used to improve thermal conductivity, then heat dissipation is improved, but manufacturing difficulty increases
Solution Approach 1:
The invention uses Chemical Vapor Deposition (CVD) to form the diamond layer, which is a well-established semiconductor manufacturing technique. By controlling parameters such as temperature, pressure, and gas composition during CVD, diamond can be formed on silicon substrates using existing fabrication equipment, making the process manufacturable.
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 substrate achieves improved high-frequency performance by leveraging diamond's thermal conductivity and the silicon oxide film's insulating properties, resulting in reduced harmonic distortion and enhanced signal integrity.
Implementation Method 1
improvement of heat-dissipating property using excellent thermal conductivity of diamond
Implementation Method 2
the substrate for a high-frequency device is made with an enhanced insulating property by providing the silicon oxide film layer on the diamond layer
Data Source
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AI summary
The present invention is a substrate for a high-frequency device including a support substrate having unevenness on a surface thereof, a diamond layer on the surface of the support substrate, and a silicon oxide film layer on the diamond layer. Thereby, the substrate for a high-frequency device using diamond having excellent high-frequency characteristics and a method for producing a substrate for a high-frequency device using diamond having excellent high-frequency characteristics are provided.