High Frequency Piezo-Composite Micromachined Ultrasound Transducer Array Technology for Biomedical Imaging
4. Micromachined Piezo-Composite
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Main fabrication methods for high frequency piezo-composites include dice-and-fill, tape casting and sol-gel molding, as shown in Figure 4-1. However, those techniques not only exhibit difficulties in achieving small kerf size and fine grain features, but also are labor and cost consuming in large scale production. Recent progress on the deep reactive ion etching (DRIE) processes of the lead based piezoelectric materials encouraged micromachining techniques for the fabrication of high frequency single crystal piezocomposite ultrasound transducers (PCMUT). This technique employs the DRIE to form the piezo pillars with the resin epoxy as the filler. Those fine featured 1-3 composites have shown unprecedented performance for high frequency applications. In this chapter, the practical fabrication guidelines of PC-MUT for high frequency 1-3 piezo-composites were introduced.