Planar Laminated Magnetic Core Inductor for BEOL IC Integration
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Solution Overview
Problem
Inductors for very large scale integration (VLSI) semiconductor ICs are too bulky for direct integration into the IC chip, limiting their ability to efficiently deliver power supply voltages and manage energy storage within multilevel wiring networks.
Innovation Solution
A planar laminated magnetic core inductor with a conductive winding spiraling around a magnetic core, featuring an alternating sequence of magnetic and non-magnetic layers, including insulating and interface layers to reduce roughness and inhibit diffusion, integrated into the multilevel wiring network of semiconductor ICs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional inductors are used for power supply in VLSI ICs, then energy storage and power delivery function is achieved, but the inductor size becomes too bulky for direct integration into the IC chip
Solution Approach 1:
The patent transitions from traditional three-dimensional inductor structures to a planar two-dimensional configuration. The magnetic core is formed as a flat structure with alternating magnetic and non-magnetic layers deposited on a substrate, allowing the inductor to be integrated into the BEOL (back-end-of-line) processing stages of IC manufacturing. This dimensional reduction enables direct integration into IC chips while maintaining energy storage functionality.
Solution Approach 2:
The patent employs composite material structures with alternating magnetic layers (e.g., CoFeB, CoFe) and non-magnetic insulating layers (e.g., RuOx, Ta2O5). This laminated composite structure achieves both magnetic functionality for energy storage and electrical insulation to prevent short circuits, all within a thin planar profile suitable for IC integration.
2Reliability
If planar laminated magnetic core structure is used, then integration into IC chip is enabled, but manufacturing complexity increases due to multiple layer deposition processes
Solution Approach 1:
The magnetic core is segmented into multiple thin alternating layers of magnetic and non-magnetic materials. Each layer is deposited separately through PVD processes, allowing precise control over thickness and composition. This segmentation enables the complex functionality to be built through repeated simple deposition cycles rather than attempting to create the entire structure in one step.
Solution Approach 2:
The patent utilizes parameter changes in the PVD deposition process, including controlling deposition temperature, gas flow ratios (oxygen to nitrogen), and deposition rate, to precisely control the oxidation state and composition of each layer. By changing parameters like oxygen partial pressure during deposition, the patent achieves controlled formation of insulating oxide layers without requiring separate processing steps.
3Manufacturing precision
If interface layers are added to reduce roughness and inhibit diffusion, then magnetic layer quality is improved, but the number of layers and manufacturing steps increases
Solution Approach 1:
The patent merges the interface layer formation with the main deposition process by controlling oxidation conditions during the PVD deposition of the non-magnetic layers. The interface layers are not deposited as separate additional steps but are formed in-situ through controlled oxidation during the deposition of Ru or Ta layers, reducing the total number of process steps while achieving the desired interface quality.
Solution Approach 2:
The patent uses thin interface layers of RuOx or Ta2O5 as intermediary layers between the magnetic layers and the surrounding environment. These interface layers serve dual purposes: they provide diffusion barriers to prevent oxygen and nitrogen from the insulating layers from diffusing into the magnetic layers, and they reduce interface roughness. The interface layers are formed as part of the non-magnetic layer deposition sequence rather than as completely separate steps.
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
Enables the integration of inductors into VLSI ICs, providing efficient energy storage and power delivery while maintaining a compact size suitable for BEOL integration, enhancing current density and performance.
Implementation Method 1
In a physical vapor deposition (PVD) chamber, depositing a non-magnetic layer on the magnetic layer
Implementation Method 2
the insulating layer and the first and second interface layers inhibit a diffusion of oxygen, nitrogen, or a combination thereof from the insulating layer into a neighboring magnetic layer
Data Source
AI summary
An inductor includes a planar laminated magnetic core and a conductive winding. The planar magnetic core includes an alternating sequence of a magnetic layer and a non-magnetic layer. The non-magnetic layer includes an insulating layer that is disposed between first and second interface layers. The conductive winding turns around in a generally spiral manner on the outside of the planar laminated magnetic core. The inductor can be integrated into a multilevel wiring network in a semiconductor integrated circuit to form a microelectronic device, such as a transformer, a power converter, or a microprocessor.