BAW Resonator Backside Interconnects 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 leads and high fluidic channel height, making it difficult to integrate electrical and fluidic connections on the same side of the BAW die.
Innovation Solution
The method involves forming bulk acoustic wave resonators on a substrate, using flip chip mounting, and removing a portion of the substrate to expose the electrode, while incorporating an acoustic energy management structure such as an air cavity or reflector to facilitate short electrical leads and low 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
Solution Approach 1:
The patent transitions from planar connections to three-dimensional vertical connections by moving electrical connections to the backside of the BAW die. This dimensional change allows electrical leads to extend perpendicular to the fluidic pathway plane, enabling high-density sensor arrays without increasing lead length in the fluidic direction.
Solution Approach 2:
The patent separates electrical connections and fluidic interfaces onto opposite sides of the BAW die. This segmentation allows independent optimization of electrical and fluidic pathways, enabling dense sensor arrays in the fluidic plane while keeping electrical leads short through vertical backside connections.
2Length of stationary object
If the fluidic channel height is reduced to improve device integration, then the device integration is improved, but the electrical and fluidic connection complexity increases
Solution Approach 1:
By moving electrical connections to the backside of the die, the patent creates separate planes for electrical and fluidic connections. This dimensional separation simplifies the connection architecture, allowing low fluidic channel height without increasing overall complexity.
3Ease of manufacture
If electrical and fluidic connections are placed on the same side of the BAW die to simplify integration, then the integration is simplified, but the sensor array density is reduced
Solution Approach 1:
The patent divides the BAW die into two functional faces: front side for fluidic connections and backside for electrical connections. This segmentation resolves the contradiction by allowing high sensor array density in the fluidic plane while maintaining simplified integration through dedicated connection zones on each side.
4Quantity of substance
If long electrical leads are used to connect center resonators in high-density arrays, then the sensor array density is improved, but the signal integrity deteriorates
Solution Approach 1:
The patent uses vertical backside connections to create short electrical leads perpendicular to the sensor array plane. This dimensional approach maintains signal integrity by minimizing lead length while enabling high-density arrays through planar expansion in the fluidic direction.
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 reliable electrical and fluidic connections, reducing lead lengths and channel height, thus improving sensor performance and integration efficiency.
Implementation Method 1
a piezoelectric material over the first electrode, the second conductive material over the piezoelectric material
Implementation Method 2
incorporating an acoustic energy management structure such as an air cavity or reflector
Implementation Method 3
bulk acoustic wave resonators on a first surface of a substrate
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.