Silicon-Free RF Die Packaging for Heat and Harmonic Distortion
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Solution Overview
Problem
Conventional silicon substrates used in RF device fabrication suffer from harmonic distortion and low resistivity, leading to heat dissipation issues and reduced performance, necessitating improved packaging solutions for enhanced thermal and electrical performance without increasing package size.
Innovation Solution
The RF device employs a mold device die with a multilayer redistribution structure and a mold compound without silicon crystal content, featuring a Si—SiGe—Si structure for enhanced thermal conductivity and reduced dielectric constant, along with a wafer-level packaging process that includes a passivation layer and interfacial layers to address heat dissipation and harmonic distortion.
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 thermal performance deteriorates and electrical performance deteriorates due to heat dissipation issues and harmonic distortion
Solution Approach 1:
The patent extracts and removes the silicon substrate from the RF device structure, retaining only the necessary active layers and interfacial layers. This eliminates the harmful thermal and electrical properties of bulk silicon while preserving the beneficial fabrication processes. The device is supported by a mold compound instead of a silicon substrate, achieving thermal management without the distortion issues of conventional silicon substrates.
Solution Approach 2:
The patent employs a composite structure consisting of an active layer, an interfacial layer, and a mold compound. This composite material system combines the advantages of different materials: the active layer provides RF functionality, the interfacial layer manages thermal and mechanical properties, and the mold compound provides thermal management and structural support, collectively achieving both ease of manufacture and improved thermal performance.
2Ease of manufacture
If conventional silicon substrates are used for RF device fabrication, then manufacturing cost is reduced and manufacturing process is simplified, but electrical performance deteriorates due to low resistivity values and harmonic distortion
Solution Approach 1:
The patent extracts and removes the silicon substrate from the RF device structure, retaining only the necessary active layers and interfacial layers. This eliminates the harmful thermal and electrical properties of bulk silicon while preserving the beneficial fabrication processes. The device is supported by a mold compound instead of a silicon substrate, achieving thermal management without the distortion issues of conventional silicon substrates.
Solution Approach 2:
The patent employs a composite structure consisting of an active layer, an interfacial layer, and a mold compound. This composite material system combines the advantages of different materials: the active layer provides RF functionality, the interfacial layer manages thermal and mechanical properties, and the mold compound provides thermal management and structural support, collectively achieving both ease of manufacture and improved thermal performance.
3Productivity
If high density integration of transistors is implemented to increase functionality, then device capability is improved, but heat generation increases significantly requiring better heat dissipation packaging
Solution Approach 1:
The patent introduces a mold compound as an intermediary material between the active layer and the external environment. This mold compound serves as a thermal mediator that conducts heat away from the densely integrated transistors in the active layer, enabling high-density integration while managing the resulting heat generation through its superior thermal conductivity compared to conventional silicon substrates.
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 provides RF devices with improved thermal and electrical performance by effectively managing heat and reducing harmonic distortion, enabling high-density packaging within a single wafer without increasing package size, thus overcoming the limitations of conventional silicon substrates.
Implementation Method 1
The first mold compound resides over the active layer of the FEOL portion without silicon crystal, which has no germanium content, in between
Implementation Method 2
featuring a Si—SiGe—Si structure for enhanced thermal conductivity and reduced dielectric constant
Data Source
AI summary
The present disclosure relates to a radio frequency (RF) device that includes a mold device die and a multilayer redistribution structure underneath the mold device die. The mold 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 first mold compound. The FEOL portion includes an active layer, a contact layer, and isolation sections. Herein, the active layer and the isolation sections reside over the contact layer, and the active layer is surrounded by the isolation sections. The first mold compound resides over the active layer without silicon crystal, which has no germanium content, in between. The multilayer redistribution structure includes redistribution interconnections and a number of bump structures that are at bottom of the multilayer redistribution structure and electrically coupled to the mold device die via the redistribution interconnections.