Transferred RF Die Structure for Low-Distortion Thermal Dissipation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional silicon substrates used in RF device fabrication suffer from harmonic distortion and low resistivity, leading to limitations in achieving high linearity and heat dissipation, particularly with increased transistor density and operation speed.
Innovation Solution
A radio frequency (RF) device with a transfer substrate having high thermal conductivity and electrical resistivity, formed from materials like sapphire, thermally conductive quartz, or aluminum nitride, and a multilayer redistribution structure with bump structures, which includes a strained silicon epitaxial active layer and isolation sections to enhance thermal and electrical performance without increasing device size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional silicon substrates are used for RF device fabrication, then manufacturing cost is reduced and manufacturing process is simplified, but harmonic distortion increases and electrical resistivity decreases
Solution Approach 1:
The patent extracts the active layer from the conventional silicon substrate and transfers it to a new substrate with superior electrical properties. The active layer is separated from the harmful silicon substrate environment and placed on a substrate that provides high resistivity and low harmonic distortion, thereby eliminating the harmful effects while preserving the manufactured device structure.
Solution Approach 2:
The patent changes the substrate material parameters from conventional silicon to specialized high-resistivity substrates. This parameter change in substrate resistivity and material composition directly addresses the harmonic distortion and electrical resistivity issues while maintaining compatibility with existing manufacturing processes for the active layer itself.
2Productivity
If transistor density and operation speed are increased in RF devices, then device performance is improved, but heat generation increases significantly
Solution Approach 1:
The patent introduces a specialized substrate as an intermediary between the active layer and the heat dissipation path. This substrate acts as a thermal mediator that efficiently conducts heat away from the high-density transistors while maintaining the electrical performance required for high-speed operation, thus decoupling performance improvement from heat generation problems.
3Ease of manufacture
If RF devices are packaged in conventional configurations, then manufacturing is simplified, but heat dissipation capability is insufficient
Solution Approach 1:
The patent designs the substrate to serve multiple functions simultaneously: it provides mechanical support, electrical isolation, and thermal management. This multi-functional substrate eliminates the need for separate heat dissipation structures in the packaging, maintaining manufacturing simplicity while dramatically improving heat dissipation capability through the substrate's inherent thermal conductivity.
4Temperature
If device size is increased to improve heat dissipation, then thermal management is enhanced, but device integration density decreases
Solution Approach 1:
The patent implements local quality enhancement by optimizing the substrate's thermal conductivity specifically in the regions where heat dissipation is most critical. The substrate provides enhanced thermal properties locally at the active layer interface without requiring overall device size increase, allowing high integration density to be maintained while achieving superior heat dissipation where it is most needed.
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 harmonic distortion, enhances thermal management, and improves electrical performance by using a high thermal conductivity substrate and strained silicon epitaxial layers, enabling faster switching speeds and denser integration without size increase.
Implementation Method 1
the active layer which is surrounded by the isolation sections and does not extend vertically beyond the isolation sections. The device region has a planarized top surface
Implementation Method 2
The transfer substrate resides over the top surface of the device region. Silicon crystal, which has no germanium, nitrogen, or oxygen content, does not exist within the transfer substrate or between the transfer substrate and the active layer within the device region
Data Source
AI summary
The present disclosure relates to a radio frequency device that includes a transfer device die and a multilayer redistribution structure underneath the transfer device die. The transfer device die includes a device region with a back-end-of-line (BEOL) portion and a front-end-of-line (FEOL) portion over the BEOL portion and a transfer substrate. The FEOL portion includes isolation sections and an active layer surrounded by the isolation sections. A top surface of the device region is planarized. The transfer substrate resides over the top surface of the device region. Herein, silicon crystal does not exist within the transfer substrate or between the transfer substrate and the active layer. The multilayer redistribution structure includes a number of bump structures, which are at a bottom of the multilayer redistribution structure and electrically coupled to the FEOL portion of the transfer device die.