Bulk Acoustic Resonator Interconnect Layout for Dense Fluidic 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 length increases making it difficult to address high density resonator sensor arrays
Solution Approach 1:
The patent applies dimensionality change by moving electrical connections from the same plane as the resonators to the opposite side of the substrate. This spatial reconfiguration allows electrical leads to extend perpendicular to the resonator array plane, effectively reducing lead length interference with fluidic pathways while maintaining high sensor array density. The electrical connections are routed through the substrate thickness dimension rather than along the surface plane.
2Length of stationary object
If the fluidic height of the flow channel is reduced to improve device compactness, then the device compactness is improved, but the height of the laminate board must be reduced which complicates manufacturing
Solution Approach 1:
The patent applies segmentation by separating the electrical connection functions from the fluidic channel structure. The electrical connections are isolated on the opposite side of the substrate from the fluidic pathways, allowing independent optimization of each subsystem. This segmentation enables reduced fluidic channel height without compromising electrical lead routing, as the two systems no longer share the same spatial constraints.
3Ease of operation
If electrical connections and fluidic interfaces are placed on the same side of the BAW die to simplify assembly, then the assembly process is simplified, but the electrical lead length increases and reliability decreases
Solution Approach 1:
The patent applies inversion by placing electrical connections on the opposite side of the substrate from the fluidic interfaces, rather than on the same side. This inverted spatial arrangement reduces electrical lead length and improves signal integrity while maintaining assembly simplicity through standardized flip-chip mounting techniques. The opposite-side configuration eliminates lead length issues associated with same-side connections.
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 efficient electrical and fluidic connections.
Implementation Method 1
a piezoelectric material... forming a bulk acoustic wave resonator
Implementation Method 2
An acoustic wave device employs an acoustic wave that propagates through or on the surface of a specific binding material, whereby any changes to the characteristics of the propagation path affect the velocity and/or amplitude of the wave
Implementation Method 3
forming a bulk acoustic wave resonator... An acoustic energy management structure is formed over at least a portion of the active region
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.