CMUT First Electrode Surface Roughness Control
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Solution Overview
Problem
The variation in frequency characteristics among cells or elements in capacitive micromachined ultrasonic transducers (CMUTs) is significant due to differences in layer thickness, affecting their performance.
Innovation Solution
The surface roughness of the first electrode is optimized to 6 nm RMS or less, which reduces the variation in frequency characteristics by controlling the surface conditions during the production process, specifically by forming a first electrode with a surface roughness value of 6 nm RMS or less and using materials like titanium or titanium alloys for high smoothness and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If layers are sequentially stacked to form a CMUT, then the device structure is completed, but the thicknesses of layers vary causing frequency characteristics to vary among cells or elements
Solution Approach 1:
The patent applies preliminary action by optimizing the surface roughness of the first electrode before subsequent layers are deposited. By controlling the first electrode's surface roughness to 6 nm RMS or less in advance, the patent prevents thickness variation in subsequent layers, thereby resolving the frequency characteristic variation issue while maintaining the sequential stacking manufacturing process
2Productivity
If the surface roughness of the first electrode is not controlled, then the manufacturing process is simpler, but the frequency characteristics vary significantly among cells or elements
Solution Approach 1:
The patent applies parameter changes by specifically controlling the surface roughness parameter of the first electrode to 6 nm RMS or less. This parameter optimization ensures uniform thickness in subsequent deposited layers, which directly improves the consistency of frequency characteristics among cells or elements without significantly complicating the manufacturing process
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 leads to uniform frequency characteristics among cells or elements, enhancing the performance and reducing variations in sensitivity and bandwidth of the ultrasonic transducers.
Implementation Method 1
a first electrode disposed on the substrate; a vibration film including a membrane disposed on the first electrode with a space therebetween
Data Source
AI summary
An electromechanical transducer includes a substrate, a first electrode disposed on the substrate, and a vibration film including a membrane disposed on the first electrode with a space therebetween and a second electrode disposed on the membrane so as to oppose the first electrode. The first electrode has a surface roughness value of 6 nm RMS or less.