Laminated film structure, multi-mode piezoelectric type miniature ultrasonic transducer and manufacturing method

Abstract

The invention discloses a laminated film structure, a multi-mode piezoelectric type miniature ultrasonic transducer and a manufacturing method. The laminated film structure comprises a substrate, a supporting film, an insulating film, a bottom electrode, a piezoelectric film and a top electrode which are sequentially laminated from bottom to top, wherein the upper surface of the substrate is sunken downwards to form a cavity structure, the horizontal cross section of the cavity structure is in a non-axis symmetrical shape, and the horizontal cross section of the piezoelectric film is consistent with the horizontal cross section of the cavity structure of the substrate in shape. The multi-mode piezoelectric miniature ultrasonic transducer comprises a laminated film structure. Through the asymmetric structural design of the piezoelectric film, the rigidity and mass distribution of the vibration film of the piezoelectric miniature ultrasonic transducer are optimized, so that net charges generated by an even-order mode originally having a symmetric vibration mode are not completely counteracted, the number of modes capable of being responded by a single piezoelectric miniature ultrasonic transducer is increased, therefore, the purpose that a single piezoelectric miniature ultrasonic transducer has a plurality of working modes and excitation modes is achieved.

Description

technical field [0001] The invention relates to the technical field of ultrasonic transducers, in particular to a laminated film structure, a multi-mode piezoelectric micro-ultrasonic transducer and a manufacturing method. Background technique [0002] Ultrasonic transducers have very important application value in the fields of medical imaging diagnosis and treatment, structural health monitoring, positioning exploration, machinery manufacturing, biological breeding, chemical catalysis, food defoaming, etc., and play an increasingly important role in national economy, social development and national defense security. increasingly important role. With the continuous expansion of the application field of ultrasonic transducers and the continuous improvement of detection performance requirements, the limitations of traditional ultrasonic transducers such as large volume, low sensitivity, easy mismatch of acoustic impedance, and narrow frequency band have become increasingly pr...

AI Technical Summary

Problems solved by technology

Therefore, the single-mode pMUT cannot take into account the ultrasonic detection depth and imaging resolution. In use, pMUT probes with different modal frequencies need to be replaced according to the detection requirements, which not only reduces work efficiency, but also increases surgical costs and risks.

In addition, single-mode ultrasonic transducers will generate standing waves in ultrasonic cleaning applications, resulting in cleaning blind spots, which seriously affect the cleaning effect and efficiency; in ultrasonic extraction, ultrasonic processing, sonochemical catalysis, and nondestructive testing applications, In order to obtain the best processing effect, ultrasonic transducers with multiple working modes are also more suitable for actual work needs

[0004] In order to solve the demand for multi-mode ultrasonic transducers in practical applications, array devices using a variety of single-mode ultrasonic transducers are favored by many researchers, mainly including a variety of single-mode ultrasonic transducers according to There are two methods of designing arrays, horizontally interleaved and vertically stacked, but these methods will inevitably increase the volume, power consumption, design complexity and manufacturing cost of the device, and affect the final ultrasound imaging effect. Special consideration must be given to the ultrasound between adjacent units. Crosstalk suppression issues, and currently there are relatively few design methods for a single pMUT capable of generating multimodal ultrasound

By matching the appropriate control circuit, the fundamental mode and high-order harmonic mode of the pMUT can be excited separately, but usually it is necessary to use ultrasound contrast agents to nonlinearly amplify the high-order harmonics, so as to obtain a medically accurate imaging. The value of multi-band ultrasound, and the control circuit used in this method is generally more complex, the flexibility of frequency band design is poor, and even the shape of the top electrode needs to be specially designed to improve the electromechanical conversion capability of high-order harmonic modes

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