Integrated Inductor Shield Layout for Packaging Field Isolation
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Solution Overview
Problem
Integrated circuit inductors and transformers are sensitive to environmental factors such as humidity, temperature, and stress due to dielectric losses and permittivity changes in packaging materials, leading to performance variations.
Innovation Solution
A patterned floating metal shield is placed above the inductor or transformer to terminate electric fields and reduce penetration into the packaging material, along with the use of dummy silicon dies, caps, or glob materials to suppress electric fields, and figure-8 transformer designs to minimize magnetic field sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If inductors are fabricated in metal layers of integrated circuits, then integration density is improved, but sensitivity to environmental factors (humidity, temperature, stress) increases due to dielectric losses and permittivity changes in packaging materials
Solution Approach 1:
A shield layer is introduced as an intermediary component between the inductor and the packaging material. This shield acts as a mediator that blocks the harmful interaction between environmental factors (humidity, temperature, stress) transmitted through the packaging and the inductor, thereby reducing dielectric losses and permittivity changes while maintaining integration density
Solution Approach 2:
The packaging material, which originally causes harmful dielectric losses and permittivity changes, is converted into a beneficial structure by adding the shield layer. The shield transforms the harmful environmental transmission path into a blocked path, where the packaging material's presence is neutralized and even becomes part of the protective structure
2Reliability
If shielding is added above inductors to block environmental factors, then performance stability is improved, but device complexity and manufacturing steps increase
Solution Approach 1:
The shield layer is merged with the existing metal interconnect layers of the integrated circuit. By using the same fabrication processes and material layers already present in the IC structure, the shield is integrated without adding separate manufacturing steps or significant structural complexity, thus improving performance stability while minimizing device complexity increase
3Reliability
If shielding is added above inductors to block environmental factors, then performance stability is improved, but manufacturing process steps increase
Solution Approach 1:
The shield fabrication is merged with the standard metal interconnect formation processes already used in integrated circuit manufacturing. The shield pattern is created using the same etching and deposition steps as the existing metal layers, eliminating the need for separate manufacturing processes and maintaining ease of manufacture while achieving performance stability
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 effectively reduces the impact of environmental changes on inductor performance by minimizing electric field penetration and electromagnetic interference, enhancing stability and reducing frequency shifts in oscillator circuits.
Implementation Method 1
A patterned floating metal shield is placed above the inductor or transformer to terminate electric fields and reduce penetration into the packaging material
Implementation Method 2
figure-8 transformer designs to minimize magnetic field sensitivity
Data Source
AI summary
An integrated circuit includes a semiconductor substrate, a metal layer, an inductor in the metal layer, and a shield above the inductor. The metal layer is a first metal layer; and the shield may be is in a second metal layer above the first metal layer. The shield may include a plurality of metal strips substantially perpendicular to metal lines of the inductor.