Inductor in Silicon Interposer for RF IC
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Solution Overview
Problem
The formation of high-quality passive circuit elements, such as inductors, within multi-die integrated circuits (ICs) has been problematic, particularly in the radio frequency (RF) range.
Innovation Solution
Implementing an inductor within the conductive layers of an interposer in a multi-die IC structure, where the interposer has a higher substrate resistivity and thicker conductive layers than the dies, allowing for a higher quality factor and improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive circuit elements such as inductors are implemented within the IC structure, then the IC can operate in the RF range, but the formation of high quality passive circuit elements has been problematic
Solution Approach 1:
The inductor is extracted from the traditional die structure and placed within the interposer structure. This allows the inductor to be formed in a separate location with optimized properties (higher substrate resistivity, thicker conductive layers) while still being electrically connected to the die through the internal interconnect structure, thereby achieving high quality inductors without compromising the ease of manufacture of the overall IC structure
Solution Approach 2:
The interposer serves as an intermediary structure between the die and the external environment. By implementing the inductor within the interposer rather than directly in the die, the system achieves better inductor performance through the interposer's favorable electrical properties while maintaining the simplicity of the manufacturing process through the modular interposer design
2Reliability
If the inductor is implemented within the conductive layers of the interposer with higher substrate resistivity and thicker conductive layers, then the quality factor of the inductor is improved, but the structural complexity of the interposer increases
Solution Approach 1:
The interposer is designed with local quality variations: specific regions have higher substrate resistivity and thicker conductive layers specifically where the inductor is implemented, while other regions maintain standard interposer properties. This allows the inductor to achieve high quality factor through localized optimization without requiring the entire interposer structure to be complex
3Reliability
If multiple conductive layers are used in the interposer to implement the inductor, then the inductor performance is enhanced, but the manufacturing process becomes more complex
Solution Approach 1:
The multiple conductive layers in the interposer serve dual purposes: they provide the necessary structure for forming high-performance inductors with optimized electrical properties, and they simultaneously function as interconnect layers for routing signals between the die and external contacts. This multi-functionality allows the same structural features to enhance inductor performance without adding separate manufacturing steps
Data Source
AI summary
An integrated circuit structure can include an interposer having a plurality of conductive layers and a die coupled to the interposer through an internal interconnect structure. The integrated circuit structure can include an inductor implemented within at least one of the conductive layers of the interposer. The inductor can include a first terminal and a second terminal. The first terminal and the second terminal can be coupled to the internal interconnect structure.