Ultrasonic Fingerprint Sensor Nanorod Flip-Chip Structure
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Solution Overview
Problem
Conventional ultrasonic fingerprint sensors face challenges in implementing a stable flip-chip structure due to difficulties in connecting upper electrodes through a thickness of 100 μm or more, and existing methods lack a reliable technology for manufacturing such a structure without wire bonding.
Innovation Solution
A method involving the fabrication of an ultrasonic fingerprint sensor using a nanorod structure, where silicon or ceramic nanorods are integrated with metal electrodes to form a flip-chip structure, allowing for the connection of upper electrodes to a lower PCB without wires, by etching conductive substrates, filling with nano-piezoelectric material, and forming side electrodes to connect the nanorods and electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flip-chip bonding method is used to connect upper electrodes to a lower PCB, then the connection reliability is improved, but the difficulty of connecting through a thickness of 100 μm or more increases
Solution Approach 1:
The patent divides the thick substrate (100 μm or more) into multiple thinner layers by introducing via holes that pass through the substrate. This segmentation allows the upper electrodes to be connected to the lower PCB through the via holes, effectively reducing the connection path complexity and enabling reliable flip-chip bonding despite the overall thickness of the device.
2Ease of manufacture
If wire bonding method is used for electrical connection, then the ease of manufacture is improved, but the device complexity increases due to additional wire components
Solution Approach 1:
The patent extracts and eliminates the need for separate wire bonding by integrating the electrical connection function directly into the substrate structure through via holes and metal electrodes. This removes the external wire components while maintaining manufacturing simplicity through standard semiconductor fabrication processes.
3Manufacturing precision
If conventional thin film process is used, then the manufacturing precision is maintained, but the ability to overcome height difference of 100 μm or more deteriorates
Solution Approach 1:
The patent transitions from a planar two-dimensional thin film process to a three-dimensional structure by creating via holes that extend vertically through the substrate. This dimensional change allows the process to handle height differences of 100 μm or more while maintaining manufacturing precision through controlled etching and filling processes.
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 creation of a stable flip-chip structure for ultrasonic fingerprint sensors, improving manufacturing efficiency, yield rate, and ensuring stable device operation while extending the device's lifespan by eliminating wire connections and optimizing signal flow through semiconductor and metal electrodes.
Implementation Method 1
it is necessary to fabricate a structure using a material called lead zirconate titanate (PZT). This material is commonly known as a piezoelectric material, and has the characteristic of functioning to convert mechanical force into an electrical signal.
Data Source
AI summary
The present invention is directed to a method for manufacturing an ultrasonic fingerprint sensor by using a nanorod structure, the method including: a conductive mold generating step of generating a plurality of rod generation holes; a nanorod generating step of generating nanorods by filling the plurality of rod generation holes with a nano-piezoelectric material; a side electrode generation portion marking step of marking side electrode generation portions; a conductive mold etching step of generating nanorods and side electrodes by performing primary etching on the conductive mold; an insulating material filling step of filling portions with an insulating material; a lower electrode forming step of performing secondary etching and forming lower electrodes; a dummy substrate bonding step of bonding a dummy substrate to a surface on which the lower electrodes are formed; and an upper electrode forming step of removing the conductive substrate base and forming upper electrodes.