Redistribution Inductor Structure With Air Gaps for RF Isolation
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Solution Overview
Problem
Current semiconductor packaging technologies face challenges in achieving high integration density and performance for radio frequency switch devices due to parasitic coupling effects and limited Q factor of inductors, which result in higher power loss and lower isolation.
Innovation Solution
Integration of inductors and transformers into redistribution structures with a protection layer and air gaps to enhance the Q factor and reduce parasitic capacitance, allowing for improved performance in radio frequency switch devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inductors are integrated into redistribution structures, then the Q factor is enhanced and parasitic capacitance is reduced, but the device complexity increases due to additional protection layers and air gap structures
Solution Approach 1:
The inductor structure is merged with the redistribution structure by forming the inductor within the redistribution structure's conductive layers and dielectric materials. This integration allows the inductor to share the same physical and structural framework as the redistribution network, thereby enhancing the Q factor while avoiding the need for completely separate inductor structures that would increase overall device complexity.
Solution Approach 2:
Air gaps are introduced locally at specific positions around the inductor structure, rather than throughout the entire device. These localized air gaps reduce parasitic capacitance precisely where needed near the inductor, while the rest of the device maintains its normal structure. This selective application of air gaps minimizes the increase in device complexity while achieving the desired electrical performance improvement.
2Reliability
If air gaps are introduced to reduce parasitic capacitance, then the isolation is improved, but the manufacturing precision requirements increase due to the need for precise air gap formation
Solution Approach 1:
The air gaps are formed as part of the preliminary structuring process during the redistribution structure fabrication, rather than as a separate post-processing step. By incorporating air gap formation into the existing manufacturing flow using standard lithography and etching techniques, the precision requirements are managed within the context of already-established process capabilities, avoiding the need for additional high-precision equipment or techniques.
3Reliability
If protection layers are added to cover conductive connectors, then the reliability is enhanced, but the manufacturing steps increase
Solution Approach 1:
The protection layer formation is merged with the existing encapsulant application process. The encapsulant is applied to cover both the semiconductor die and the conductive connectors simultaneously in a single step, providing protection to both elements without requiring separate protection layer deposition steps. This integration maintains reliability enhancement while minimizing increases in manufacturing complexity.
Data Source
AI summary
An embodiment is a device including an integrated circuit die having an active side and a back side, the back side being opposite the active side, a molding compound encapsulating the integrated circuit die, and a first redistribution structure overlying the integrated circuit die and the molding compound, the first redistribution structure including a first metallization pattern and a first dielectric layer, the first metallization pattern being electrically coupled to the active side of the integrated circuit die, at least a portion of the first metallization pattern forming an inductor.