Shielded Transcapacitive Sensor Routing Traces
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Solution Overview
Problem
Capacitive sensor devices face noise and energy interference issues due to the proximity of active circuits to receiver electrodes, which affects signal quality, particularly in compact silicon sensor devices used for fingerprint sensing.
Innovation Solution
The implementation of a silicon sensor device with multiple metal and dielectric layers, where each metal layer is separated by a dielectric layer, and includes transmitter electrodes, receiver electrodes, routing traces, and circuit layers. Routing traces and shielding blocks are configured to shield receiver electrodes from noise and energy originating from the circuit layers, improving signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If active circuits are located proximate to receiver electrodes to reduce device size, then device compactness is improved, but noise and energy interference on receiver electrodes increases
Solution Approach 1:
A shielding layer is introduced as an intermediary component between the active circuits and receiver electrodes. This shielding layer acts as a mediator that blocks electromagnetic noise and energy from the active circuits from reaching the receiver electrodes, while allowing the circuits to remain in close proximity for compact device design.
Solution Approach 2:
The device is segmented into distinct functional layers: a first metal layer containing receiver electrodes, a shielding layer with routing traces for transmitter electrodes, and circuit layers beneath. This segmentation separates the noise-sensitive receiver electrodes from noise-generating active circuits while maintaining compact overall device size through vertical stacking.
2Object-affected harmful factors
If multiple metal and dielectric layers are added for shielding, then noise shielding effectiveness is improved, but device complexity increases
Solution Approach 1:
The second metal layer is designed to serve multiple functions simultaneously: it provides electromagnetic shielding for the receiver electrodes from active circuits, and it contains routing traces for transmitter electrodes. This multi-functionality reduces the need for additional dedicated shielding layers, thereby limiting the increase in 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
This design enhances signal-to-noise ratio, reduces sensor size, and lowers costs while maintaining high resolution, achieving smaller sensor pitch and easier design with lower complexity compared to conventional sensors.
Implementation Method 1
A respective routing trace for a respective transmitter electrode is configured to shield respective portions of the plurality of receiver electrodes which correspond to a width of the respective transmitter electrode from energy and/or noise originating from the one or more circuit layers
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A silicon sensor device includes: a plurality of metal layers; and a plurality of dielectric layers. Each of the plurality of metal layers is disposed on a respective dielectric layer, and wherein each of the plurality of metal layers is separated from an adjacent metal layer by a respective dielectric layer. The plurality of metal layers include: a first metal layer comprising a plurality of transmitter electrodes and a plurality of receiver electrodes; a second metal layer disposed beneath the first metal layer, wherein the second metal layer comprises a plurality of routing traces for the plurality of transmitter electrodes and a plurality of shielding blocks; and one or more circuit layers disposed beneath the second metal layer. A respective shielding block of the plurality of shielding blocks is configured to shield a respective portion of a respective receiver electrode of the plurality of receiver electrodes.