Ultrasonic Probe Piezoelectric Element Growth via Sacrificial Layer
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Solution Overview
Problem
The manufacturing of ultrasonic probes with thin piezoelectric elements for high-frequency ultrasonic waves is challenging due to difficulties in producing thin dicing blades and handling safety concerns, which limits the production of high-resolution images.
Innovation Solution
A method involving the growth of piezoelectric elements on a substrate using a sacrificial layer and electrode units, where the sacrificial layer is formed of a photosensitive material, and the piezoelectric elements are grown in openings separated by a distance of 20 μm or less, with a thickness of 200 μm or less, using a sequence synthesis method at a temperature of 200°C or lower.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If piezoelectric elements are formed by physically splitting using dicing equipment, then manufacturing process is simple, but it is difficult to manufacture thin piezoelectric elements and there are safety concerns about handling
Solution Approach 1:
The patent replaces the mechanical dicing process with a chemical growth method. Piezoelectric elements are grown epitaxially on a substrate through chemical vapor deposition or similar processes, eliminating the need for mechanical cutting. This substitution enables precise thickness control at the micrometer and sub-micrometer levels while avoiding safety hazards associated with handling thin mechanically-cut elements.
Solution Approach 2:
The patent changes the fundamental manufacturing parameter from mechanical cutting thickness to controlled chemical deposition thickness. By adjusting growth time, temperature, and precursor flow rates, the piezoelectric layer thickness can be precisely controlled to achieve thin elements (e.g., 10-100 μm) that would be difficult or dangerous to produce through mechanical dicing.
2Measurement precision
If more piezoelectric elements are used to obtain better image resolution, then image quality improves, but the complexity of manufacturing increases
Solution Approach 1:
The patent merges multiple piezoelectric elements into a single integrated array structure grown on one substrate. The epitaxial growth process allows simultaneous formation of multiple elements with uniform properties, reducing manufacturing steps compared to individual element fabrication and assembly. This integration maintains high element counts for improved resolution while simplifying the overall manufacturing process.
Solution Approach 2:
The patent segments the substrate into multiple regions for growing individual piezoelectric elements with different orientations or properties. Each region can be independently controlled during growth, allowing customization of element characteristics while using a unified growth process. This segmentation enables high-resolution arrays without proportionally increasing manufacturing complexity.
3Speed
If thin piezoelectric elements are manufactured to generate high-frequency ultrasonic waves, then ultrasonic wave frequency increases, but it is difficult to manufacture and there are safety concerns
Solution Approach 1:
The patent replaces mechanical dicing with chemical epitaxial growth to manufacture thin piezoelectric elements. This substitution enables precise thickness control for high-frequency applications (e.g., 20-100 MHz requiring 10-50 μm thickness) while eliminating the safety hazards and manufacturing difficulties associated with mechanically cutting and handling such thin elements.
Solution Approach 2:
The patent uses a sacrificial layer as an intermediary during the growth process. The sacrificial layer is grown first, then piezoelectric elements are epitaxially grown on top of it, and finally the sacrificial layer is removed. This intermediary approach enables precise thickness control and safe handling during manufacturing, as the elements remain supported during processing and can be safely transferred after completion.
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 method enables the production of ultrasonic probes with closely spaced piezoelectric elements, allowing for high-resolution imaging and improved safety in handling, facilitating the generation of high-frequency ultrasonic waves.
Implementation Method 1
forming a sacrificial layer on a substrate; forming a plurality of openings in the sacrificial layer
Implementation Method 2
a transducer that is mounted therein and converts an ultrasonic signal to an electrical signal and vice versa. In general, a transducer includes a set of multiple piezoelectric elements
Data Source
AI summary
Provided is a method of manufacturing an ultrasonic probe. The method includes forming a sacrificial layer on a substrate; forming a plurality of openings in the sacrificial layer that are separated from one another; forming piezoelectric units by growing a piezoelectric element in each of the plurality of openings; and removing the sacrificial layer.