Air-Gap Interposer Inductor Layout for High Q in Less Die Area
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Solution Overview
Problem
Existing semiconductor technologies face challenges in integrating high performance capacitors and inductors with high quality factor (Q factor), small area consumption, limited parasitic coupling, ease of layout, and manufacture, while additional metal layers increase on-die area and fabrication costs.
Innovation Solution
An improved interposer is developed, featuring a substrate with an inductor forming region, trenches, a buffer layer lining the trenches to form air gaps, and an inductor coil pattern embedded in the buffer layer. The interposer also includes a fluorosilicate glass layer and a dielectric capping layer to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional metal layers are used to improve Q factor, then Q factor is improved, but on-die area increases and fabrication costs increase
Solution Approach 1:
The inductor coil pattern is embedded within the buffer layer (typically a planar layer), utilizing the vertical dimension (z-axis) to integrate the inductor structure. This allows the inductor to occupy three-dimensional space within the existing buffer layer thickness, improving Q factor without expanding the on-die footprint area.
Solution Approach 2:
The inductor coil pattern is nested within the buffer layer structure, which itself is embedded in the substrate. This nested configuration allows the inductor to be integrated within the existing interposer architecture without requiring additional metal layers above or below the buffer layer, thus avoiding area expansion and cost increase.
2Reliability
If additional metal layers are used to improve Q factor, then Q factor is improved, but fabrication costs increase
Solution Approach 1:
The inductor fabrication process is merged with the existing buffer layer formation process. The inductor coil pattern is formed within the same buffer layer that provides mechanical support and electrical isolation, eliminating the need for separate additional metal layer deposition and associated fabrication steps, thereby reducing fabrication costs.
Solution Approach 2:
The buffer layer serves multiple functions: it provides mechanical support, electrical isolation, and houses the inductor coil pattern. This multi-functional design eliminates the need for dedicated additional metal layers solely for inductor formation, reducing fabrication complexity and costs while maintaining high Q factor performance.
3Reliability
If additional metal layers are used to improve Q factor, then Q factor is improved, but fabrication throughput decreases
Solution Approach 1:
The inductor coil pattern is formed within the buffer layer during the buffer layer formation process itself, before subsequent interposer fabrication steps. This preliminary integration means that inductor fabrication occurs concurrently with buffer layer deposition rather than as a separate subsequent step, maintaining fabrication throughput while achieving high Q factor.
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 improved interposer achieves a high quality factor, reduces on-die area consumption, minimizes parasitic coupling, and simplifies layout and manufacturing, while maintaining cost-effectiveness and fabrication throughput.
Implementation Method 1
a buffer layer lining interior surfaces of the plurality of trenches and forming air gaps within the plurality of trenches
Data Source
AI summary
An interposer includes a substrate having an inductor forming region thereon, a plurality of trenches within the inductor forming region in the substrate, a buffer layer lining interior surfaces of the plurality of trenches and forming air gaps within the plurality of trenches, and an inductor coil pattern embedded in the buffer layer within the inductor forming region.