CMUT (Capacitive Micromachined Ultrasonic Transducer)-based biochemical transducer and manufacturing method thereof

Abstract

The invention provides a CMUT (Capacitive Micromachined Ultrasonic Transducer)-based biochemical transducer and a manufacturing method thereof. The CMUT-based biochemical transducer comprises a sensitivity identification material layer, an upper electrode, a silicon dioxide film, a silicon strut, a lower electrode, a silicon dioxide insulating layer and a silicon substrate in sequence from top to bottom. According to the biochemical transducer, the metal lower electrode is completely isolated from the silicon substrate, the method which takes the substrate as the lower electrode in the conventional CMUT based biochemical transducer is replaced, the power consumption is reduced, the electric field strength between the upper electrode and the lower electrode is greatly improved, and the electromechanical coupling capability is strengthened; the lower electrode is only positioned inside a cavity formed by the silicon dioxide film, the silicon strut and the silicon dioxide insulating layer, so that the lower side of the film is effectively vibrated rather than covering the whole silicon substrate, the parasitic capacitance is effectively reduced, the electromechanical conversion ratio is further increased, and the effective utilization rate of electric energy is improved.

Description

technical field [0001] The invention belongs to the technical field of MEMS and biochemistry, in particular to a CMUT-based biochemical sensor and a preparation method thereof. Background technique [0002] Biological and chemical sensors are mostly composed of mass sensors and polymer functional layers, and the detection of biochemical quantities is achieved by shifting the resonance frequency caused by mass changes. Common biochemical sensor microstructures based on MEMS (Micro Electro-Mechanical Systems, micro-mechanical electronic systems) technology mainly include micro-cantilever beams, piezoelectric quartz crystals, thin-film bulk acoustic resonators, and surface acoustic wave resonators. Although these measurement structures have been It is very mature, but due to its own structural characteristics, the improvement of the resonance frequency and quality factor is limited. For example, the resonance frequency of the commonly used cantilever beam structure in air is te...

AI Technical Summary

Problems solved by technology

However, these biochemical sensors are mostly based on some common CMUT structures. Due to the influence of factors such as large parasitic capacitance, large film quality, high impedance of the silicon substrate, and charging phenomenon of the insulating layer during work, the further improvement of the detection sensitivity and quality limit is limited. Therefore, These conventional CMUT structures are not suitable for use as biochemical sensors or cannot give full play to the many advantages of CMUTs when used as biochemical sensors.

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