Wafer-Level Integrated Inductor for High-Frequency Power Supplies
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Solution Overview
Problem
Conventional on-chip inductors face limitations in achieving high frequency operation due to eddy currents, which restrict their use in RF and high-frequency voltage conversion applications, and integrating voltage converters on-chip is hindered by physical size constraints and increased power consumption in processors.
Innovation Solution
The integration of a laminated magnetic material structure with alternating magnetic and insulating layers, surrounded by metal lines, reduces eddy currents and enables high frequency operation, along with a wafer-level process that includes electroplating and sputtering techniques to form magnetic layers adjacent to insulator layers, allowing for efficient high-frequency inductor design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional on-chip inductors are used, then integration is achieved, but eddy currents limit high frequency operation
Solution Approach 1:
The magnetic core is segmented into multiple thin laminated layers with insulating material between them. This segmentation breaks the continuous magnetic path into discrete layers, interrupting eddy current loops and reducing their magnitude, thereby enabling high frequency operation while maintaining on-chip integration
Solution Approach 2:
The inductor uses a composite structure combining magnetic material layers with insulating material layers. This composite laminated construction provides both the magnetic properties needed for inductance and the electrical isolation needed to suppress eddy currents, resolving the contradiction between integration and high frequency performance
2Speed
If inductance value is increased for lower frequency operation, then frequency requirement is met, but physical size increases beyond chip constraints
Solution Approach 1:
The invention changes the magnetic path length parameter by creating a closed-loop magnetic core structure with a short magnetic path. This allows achieving the required inductance value at higher frequencies with a compact footprint, satisfying both frequency requirements and chip area constraints
3Power
If off-die voltage converter is used, then voltage conversion is achieved, but current per pin increases beyond maximum capability
Solution Approach 1:
The voltage converter and processor are merged into a single integrated on-chip system. The inductor, switching elements, and control circuitry are all fabricated on the same die using compatible processes, eliminating the need for off-die converters and reducing current per pin while maintaining voltage conversion functionality
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
This approach enables high-frequency operation with low RDSON values and high efficiency, mitigating the challenges of eddy currents and power consumption issues, thereby facilitating the integration of voltage converters on-chip and reducing the need for off-die voltage converters.
Implementation Method 1
By increasing the resistance of the magnetic material layers, the eddy currents within the inductor may be reduced
Implementation Method 2
A second layer of metal lines may be deposited over the third layer of polymer
Implementation Method 3
A layer of titanium may be sputtered onto the second layer of polymer
Data Source
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AI summary
In described examples of an inductor (100) on a wafer level process, high conductive layers (107, 114), polymer layers (105, 109, 112, 116), and a magnetic core (111) allow high frequency operation, low RDSON values and high efficiency.