BAW Resonator Layout for Dense Fluidic Sensor Arrays
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Solution Overview
Problem
Existing methods for manufacturing bulk acoustic wave (BAW) sensor arrays face challenges in achieving high density due to long electrical lead lengths and high fluidic channel heights, making it difficult to fabricate reliable and efficient high-density resonator sensor arrays.
Innovation Solution
The method involves forming bulk acoustic wave resonators on a substrate with conductive materials and piezoelectric materials, followed by the creation of an acoustic energy management structure and interconnects, and then removing a portion of the substrate to expose the electrodes, allowing for flip chip mounting and reduced fluidic channel height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple rows of resonators are placed in the fluidic pathway to increase sensor array density, then the sensor array density is improved, but the electrical lead lengths increase making it difficult to address high density resonator sensor arrays
Solution Approach 1:
The patent moves electrical connections from the same plane as the resonators to the backside of the substrate through via holes. This dimensional transition allows electrical leads to connect to resonators without extending across the fluidic pathway, thus increasing sensor array density while keeping lead lengths short.
Solution Approach 2:
The substrate is functionally segmented into a front side for fluidic pathways and resonators, and a back side for electrical connections. This segmentation isolates electrical lead routing from the fluidic pathway, allowing high-density resonator arrays without proportionally increasing lead lengths.
2Length of stationary object
If the laminate board thickness is increased to accommodate fluidic channel height requirements, then the fluidic channel height is improved, but the overall device size and complexity increase
Solution Approach 1:
The patent creates fluidic channels by removing substrate material from the front side rather than relying on laminate board thickness. This allows fluidic channel height to be defined by etch depth rather than board construction, simplifying the overall device structure.
Solution Approach 2:
The patent extracts fluidic channels from the laminate board structure by selectively removing substrate material. This separation allows the fluidic channel dimensions to be independently controlled without being constrained by laminate board thickness, reducing device complexity.
3Device complexity
If electrical connections and fluidic interfaces are placed on the same side of the substrate, then the device structure is simplified, but the electrical lead lengths increase and reliability decreases
Solution Approach 1:
The patent segments the substrate into distinct functional zones: the front side hosts fluidic interfaces and resonators, while the back side hosts electrical connections. This spatial separation improves reliability by isolating electrical connections from the fluidic environment and reducing lead lengths, while the overall structure remains integrated through the substrate.
Solution Approach 2:
The substrate itself acts as an intermediary, with via holes serving as conduits to connect electrical connections on the back side to resonators on the front side. This intermediary structure allows electrical and fluidic interfaces to be separated while maintaining functional connectivity, improving reliability without requiring complex external routing.
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 enables the fabrication of high-density BAW sensor arrays with short electrical leads and low fluidic channel height, improving reliability and facilitating easier electrical connections to printed circuit boards.
Implementation Method 1
a piezoelectric material located between the two electrodes
Implementation Method 2
An acoustic energy management structure that functions to reduce or avoid dissipation of the acoustic waves into the substrate
Implementation Method 3
Changes in velocity can be monitored by measuring the frequency, amplitude-magnitude, and/or phase characteristics of the acoustic wave device
Data Source
AI summary
Methods of fabricating a bulk acoustic wave resonator structure for a fluidic device. The methods can include a first step of disposing a first conductive material over a portion of a first surface of a substrate to form at least a portion of a first electrode, the substrate having a second surface opposite the first surface. Then, a piezoelectric material may be disposed over the first electrode. Next, a second conductive material can be disposed over the piezoelectric material to form at least a portion of a second electrode. The second conductive material extends substantially parallel to the first surface of the substrate and the second conductive material at least partially extends over the first conductive material. The overlapping region of the first conductive material, the piezoelectric material, and the second conductive material form a bulk acoustic wave resonator, the bulk acoustic wave resonator having a first side and an opposing second side. An acoustic energy management structure is then disposed over a first side of the bulk acoustic wave resonator. Next a third conductive material is disposed over a portion of the second conductive material that extends beyond the bulk acoustic wave resonator, wherein the third conductive material forms an interconnect extending above the acoustic energy management structure in a direction substantially perpendicular to the first surface of the substrate. Finally a portion of the second surface of the substrate is removed to expose a chemical mechanical connection at the first electrode at a second side of the bulk wave acoustic resonator. Devices formed thereby are also included.