Shielded MEMS Devices in Integrated Circuits
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Solution Overview
Problem
Current methods for mitigating electromagnetic, thermal, and acoustic coupling in RF MEMS devices, such as complex wafer bonding processes, result in increased device size and cost, compromising signal integrity in compact cellular phone designs.
Innovation Solution
The development of integrated circuits with shielded MEMS devices that incorporate electromagnetic and acoustic shielding structures, formed using a single substrate without the need for cap wafer bonding, featuring conductive pillars, metallic thin films, and dielectric layers to create monolithic shielding structures around MEMS devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex wafer bonding processes with cap wafer are used to mitigate electromagnetic and acoustic coupling, then signal integrity is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts the shielding function from a separate cap wafer bonding process and integrates it directly into the substrate structure. Ground planes and shielding layers are formed within the substrate itself through deposition and patterning processes, eliminating the need for complex wafer bonding while maintaining electromagnetic and acoustic isolation.
Solution Approach 2:
The patent merges the shielding structure with the substrate by forming ground planes and metallic layers directly within the substrate. This integration combines the substrate's mechanical support function with the electromagnetic shielding function, simplifying the overall device structure and manufacturing process.
2Reliability
If complex wafer bonding processes with cap wafer are used to mitigate electromagnetic and acoustic coupling, then signal integrity is improved, but device footprint increases
Solution Approach 1:
The patent implements nested shielding structures where ground planes and metallic shielding layers are embedded within the substrate layers. The shielding structure is nested within the substrate thickness rather than adding lateral footprint, allowing electromagnetic and acoustic isolation without increasing device area.
3Object-affected harmful factors
If complex wafer bonding processes with cap wafer are used to mitigate electromagnetic and acoustic coupling, then electromagnetic isolation is improved, but manufacturing time and cost increase
Solution Approach 1:
The patent performs preliminary actions by forming ground planes and shielding layers directly during substrate fabrication before device assembly. The shielding structure is prepared in advance within the substrate through deposition and patterning, eliminating the need for time-consuming post-fabrication wafer bonding processes.
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
This approach enhances signal integrity by reducing electromagnetic and acoustic interference while maintaining a small form factor and reducing manufacturing costs, achieving improved isolation without the need for complex bonding processes.
Implementation Method 1
a metallic thin film over the MEMS device and in contact with the conductive pillar, wherein the metallic thin film, the conductive pillar and the ground plane form an electromagnetic shielding structure surrounding the MEMS device
Implementation Method 2
an acoustic shielding structure over the substrate and adjacent the electromagnetic shielding structure
Data Source
AI summary
Integrated circuits having shielded micro-electromechanical system (MEMS) devices and method for fabricating shielded MEMS devices are provided. In an example, an integrated circuit having a shielded MEMS device includes a substrate, a ground plane including conductive material over the substrate, and a dielectric layer over the ground plane. The integrated circuit further includes a MEMS device over the ground plane. Also, the integrated circuit includes a conductive pillar through the dielectric layer and in contact with the ground plane. The integrated circuit includes a metallic thin film over the MEMS device and in contact with the conductive pillar, wherein the metallic thin film, the conductive pillar and the ground plane form an electromagnetic shielding structure surrounding the MEMS device. Further, the integrated circuit includes an acoustic shielding structure over the substrate and adjacent the electromagnetic shielding structure.