Wafer-Level Packaging Structure for Reference Device EMI Shielding
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Solution Overview
Problem
MEMS sensors are susceptible to external environmental factors, leading to deviations in electrical signal output and affecting performance, and their packaging cost constitutes a significant portion of the total cost, necessitating an improved packaging structure.
Innovation Solution
A wafer-level packaging structure is designed with a device wafer, reference device regions, and a thickened intermediate layer wafer, incorporating features like inclined and stepped surfaces, via holes, blocking layers, and getters to shield electromagnetic interference and enhance signal accuracy while reducing packaging costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional packaging structures are used for MEMS sensors, then manufacturing simplicity is maintained, but signal accuracy deteriorates due to electromagnetic interference affecting reference devices
Solution Approach 1:
The packaging structure is segmented into distinct functional regions: a first region containing the MEMS sensor, a second region containing the reference device, and a third region serving as an electromagnetic shielding region. This spatial segmentation isolates the reference device from electromagnetic interference while maintaining manufacturing efficiency through wafer-level processing.
Solution Approach 2:
An electromagnetic shielding layer is introduced as an intermediary element between the MEMS sensor region and the reference device region. This shielding layer, positioned in the third region, blocks electromagnetic waves from reaching the reference device, thereby protecting signal accuracy without complicating the overall manufacturing process.
2Ease of manufacture
If packaging cost is reduced, then manufacturing efficiency improves, but signal accuracy may deteriorate due to insufficient shielding
Solution Approach 1:
The electromagnetic shielding function is merged into the packaging structure itself rather than being a separate added component. The shielding layer is integrated during wafer-level packaging processing, combining structural support and electromagnetic protection functions into a unified design that reduces overall packaging cost while maintaining shielding effectiveness.
Solution Approach 2:
The shielding effectiveness is optimized by adjusting parameters such as the thickness and material composition of the electromagnetic shielding layer. By carefully selecting these parameters, adequate protection against electromagnetic interference is achieved at minimal cost, balancing manufacturing efficiency with signal accuracy requirements.
3Reliability
If reference devices are exposed to electromagnetic waves, then manufacturing simplicity is maintained, but electrical signal output deviates from actual situation
Solution Approach 1:
Electromagnetic shielding is applied locally only in the third region where it is most needed to protect the reference device, rather than enclosing the entire wafer. This localized shielding approach ensures signal output accuracy for reference devices while maintaining manufacturing simplicity and avoiding unnecessary complexity in regions where shielding is not required.
Solution Approach 2:
The shielding strategy extends into the vertical dimension by positioning the electromagnetic shielding layer between different wafer layers. This three-dimensional arrangement provides effective electromagnetic protection for the reference device while maintaining a compact packaging structure that does not significantly increase overall device complexity.
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 structure improves signal accuracy by shielding reference devices from electromagnetic interference and reduces packaging costs through efficient manufacturing processes, enhancing the performance and cost-effectiveness of MEMS sensors.
Implementation Method 1
a thickened intermediate layer wafer... to shield electromagnetic interference and enhance signal accuracy
Data Source
AI summary
A wafer-level packaging structure, comprising a device wafer, a plurality of reference device regions, and a thickened intermediate layer wafer. The reference device regions are arranged on the device wafer and are configured to provide reference devices; the thickened intermediate layer wafer is arranged on the device wafer and comprises first sub-portions and second sub-portions which are connected to each other, each first sub-portion being arranged around a reference device; one reference device region is arranged in the area enclosed by a first sub-portion, and the orthographic projection of each second sub-portion on the device wafer covers a reference device region. Further provided are a sensor and a manufacturing method for the wafer-level packaging structure.