Ultrasonic Transducer Electrode Step Moderation
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Solution Overview
Problem
Conventional ultrasonic transducers using piezoelectric materials face challenges with increased resistance, membrane damage, and decreased dielectric strength due to the thickness of lower electrodes and interconnections, particularly when forming arrays, which affects the reliability and stability of the device.
Innovation Solution
The ultrasonic transducer design includes a first electrode, insulation films, and interconnections where the width of interconnections overlapping the edge of the electrode is thicker than those not overlapping, and the step of the electrode is moderated by tapering or forming sidewalls, reducing the resistance increase and maintaining dielectric strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lower electrode thickness is increased to reduce resistance, then the resistance decreases, but the step of the electrode increases causing interconnection coverage problems and membrane damage
Solution Approach 1:
The patent applies local quality by making the interconnection width variable along its length. Specifically, the interconnection has a first width when overlapping the lower electrode edge and a second width (greater than the first width) when not overlapping the edge. This localized width increase compensates for the reduced coverage at the electrode step, ensuring adequate electrical connection without increasing the electrode thickness.
Solution Approach 2:
The patent changes the geometric parameter of the interconnection (its width) to resolve the contradiction. By increasing the interconnection width in specific regions, the patent compensates for the step effect caused by thick lower electrodes, thereby maintaining both low resistance and adequate coverage without modifying the electrode thickness itself.
2Reliability
If the interconnection width is increased to reduce resistance, then the resistance decreases, but the device complexity increases
Solution Approach 1:
Instead of uniformly increasing the interconnection width throughout, the patent applies local quality by making the width increase only in specific regions where needed (where the interconnection does not overlap the lower electrode edge). This localized approach reduces resistance effectively while minimizing the overall increase in device complexity and material usage.
3Manufacturing precision
If the lower electrode step is moderated to reduce interconnection issues, then the manufacturing precision improves, but the electrode thickness must be reduced increasing resistance
Solution Approach 1:
The patent changes the parameter of the interconnection (its width) to compensate for the fixed electrode step. Rather than reducing the electrode thickness to improve manufacturing precision, the patent maintains the thick electrode for low resistance and instead adjusts the interconnection width parameter to ensure proper coverage and alignment, thereby resolving both issues simultaneously.
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 design suppresses resistance increase, reduces membrane damage, and enhances the reliability of the ultrasonic transducer by maintaining dielectric strength and stability, even when emitting strong ultrasonic waves.
Implementation Method 1
ultrasonic transducers using piezoelectric vibration
Implementation Method 2
wet etching holes for forming the hollow parts
Data Source
AI summary
An ultrasonic transducer includes a first electrode, a first insulation film covering the first electrode, a hollow part overlapping the first electrode on the first insulation film, a second insulation film covering the hollow part, a second electrode overlapping the hollow part on the second insulation film, and an interconnection joined to the second electrode. An edge of the first electrode is formed so as to moderate a step of the first electrode.