RFIC Device with Thin Semiconductor Layer and Sheet Heat Sink
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Solution Overview
Problem
RF CMOS switches on silicon-on-insulator substrates suffer from overheating due to electrical coupling with the silicon substrate, leading to reliability issues when handling high signal power, as the existing methods to eliminate this coupling, such as removing the silicon substrate, result in lower heat dissipation capabilities.
Innovation Solution
A novel RFIC device is designed with a semiconductor layer thinner than 3 μm, vertically isolated by dielectric layers, and equipped with a sheet-like heat sink made of high thermal conductivity materials, such as boron nitride or metals like aluminum, to efficiently dissipate heat from the transistor without introducing additional electrical interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the silicon substrate is removed to eliminate electrical coupling, then parasitic capacitance is reduced, but heat dissipation capability deteriorates
Solution Approach 1:
The device structure is segmented into distinct functional layers: a thin silicon layer for active components, insulating layers for electrical isolation, and a separate heat sink layer for thermal management. This segmentation allows each layer to optimize its specific function without compromising others.
Solution Approach 2:
Insulating layers are introduced as intermediary elements between the silicon active layer and the substrate/heat sink. These intermediary layers eliminate harmful electrical coupling (parasitic capacitance) while allowing thermal energy to pass through to the heat sink.
2Temperature
If the silicon substrate is kept for heat dissipation, then heat dissipation capability is maintained, but electrical coupling causes additional parasitic capacitance
Solution Approach 1:
Insulating layers serve as mediators that block electrical coupling between the silicon active components and the substrate, eliminating parasitic capacitance while permitting thermal conduction to the heat sink for effective heat dissipation.
Solution Approach 2:
The insulating layers are strategically positioned only where electrical isolation is needed, while maintaining thermal contact between the silicon layer and the heat sink. This local application of insulation preserves heat dissipation pathways while blocking harmful electrical coupling.
3Power
If high signal power is applied to overcome coupling losses, then signal strength is maintained, but overheating occurs reducing reliability
Solution Approach 1:
The insulating layers eliminate the need for high signal power compensation by removing the source of coupling losses. This allows operation at lower power levels while maintaining signal integrity, thereby preventing overheating and improving reliability.
Solution Approach 2:
The structure converts the potentially harmful effect of direct substrate contact into a benefit by using the substrate as a heat sink while electrically isolating the active components. The same substrate that could cause parasitic capacitance becomes an effective thermal management solution.
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 minimizes parasitic effects and maintains heat dissipation capabilities comparable to the removed silicon substrate, preventing overheating and enhancing the reliability of RFIC devices.
Implementation Method 1
a sheet-like heat sink that is formed on a surface of the second dielectric layer opposite to the first semiconductor layer for dissipating heat from the semiconductor component
Data Source
AI summary
A radio frequency integrated circuit (RFIC) device and methods for fabricating same are disclosed. The RFIC device includes: a first semiconductor layer having a first surface, a second surface parallel to the first surface and a thickness of smaller than 3 μm; a first dielectric layer on the first surface of the first semiconductor layer; a semiconductor component within the first semiconductor layer and the first dielectric layer; a second dielectric layer on the second surface of the first semiconductor layer, the second dielectric layer having a thickness of smaller than 1 μm; and a sheet-like heat sink formed on a surface of the first dielectric layer opposite to the first semiconductor layer for dissipating heat from the semiconductor component. Efficient dissipation of heat from an RF transistor to a certain extent can be achieved by the RFIC device.