Planar Laminated Core Inductor for BEOL VLSI Integration
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Solution Overview
Problem
Inductors for switched-inductor converters in very large scale integration (VLSI) semiconductor ICs have been too bulky for direct integration into the IC chip, limiting their ability to efficiently deliver power supply voltages and manage energy storage within the multilevel wiring network.
Innovation Solution
A planar magnetic core inductor with a conductive winding spiraling around the outside, featuring an alternating sequence of magnetic and non-magnetic layers, and a laminated configuration that allows for integration into the multilevel wiring network, utilizing materials like Co/Zr/Ta and silicon, tantalum, aluminum, chromium, or titanium, with interface layers to inhibit diffusion and reduce roughness, enabling efficient energy storage and distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional inductor structures are used, then energy storage capability is achieved, but the inductor becomes too bulky for integration into VLSI IC chips
Solution Approach 1:
The patent transitions from traditional three-dimensional inductor structures to a planar two-dimensional configuration that can be integrated into the BEOL multilevel wiring network of VLSI ICs. The inductor is formed as a planar structure with conductive traces arranged in spiral or interdigitated patterns on insulating layers, enabling integration without occupying excessive vertical space.
Solution Approach 2:
The inductor structure is nested within the existing multilevel wiring network architecture of the VLSI IC. The planar inductor is formed between different wiring layers, utilizing the available space within the BEOL structure. The inductor components are embedded within the interconnect stack, allowing co-integration with other circuit elements in a compact footprint.
2Ease of manufacture
If planar magnetic core structure is used, then integration into multilevel wiring network is enabled, but manufacturing complexity increases due to multiple layer deposition
Solution Approach 1:
The inductor is segmented into multiple functional layers including bottom electrodes, insulating layers with openings, conductive traces, and top electrodes. Each layer is formed through separate deposition and patterning steps, allowing independent optimization of each component while maintaining overall integration within the BEOL process flow.
3Manufacturing precision
If interface layers are added to reduce roughness and inhibit diffusion, then magnetic layer quality improves, but manufacturing steps increase
Solution Approach 1:
Interface layers are inserted between the magnetic layers and adjacent insulating or conductive layers to serve as intermediary structures. These interface layers have intermediate properties that facilitate smooth transitions and prevent unwanted interactions between adjacent layers, including diffusion barrier functionality and surface roughness control.
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 enables the integration of inductors into the BEOL of VLSI ICs, providing the necessary energy storage and current density for modern DC to DC voltage converters, enhancing performance-per-watt and allowing for dynamic voltage and frequency scaling.
Implementation Method 1
interface layers to inhibit diffusion
Implementation Method 2
Electrical conductors coupled to interconnects are magnetically coupled to magnetic film layers to engender an inductor
Data Source
Figure 1
Figure 2A
Figure 2B
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.