This paper describes a new design of piezoelectric micromachined ultrasonic transducer (pMUT) with a monocrystalline Pb(Zr,Ti)O₃-based thin film (Mono-PZT) for enhancing the mechanical robustness. In this study, we investigated two design concepts to suppress crack generation in Mono-PZT. First, the area of Mono-PZT is limited by leaving an island Mono-PZT pattern only on the membrane of the pMUT. Second, the edge of Mono-PZT is covered with a polyimide (PI) thin film as a protection layer to prevent the peeling. We prepared three different designs, a new design with both concepts, another design with the first concept, and the conventional one with neither of them for comparison. The robust mechanical analyses of these devices were performed by driving resonantly and increasing the displacement of the membranes. As these results, the proposed structure with both concepts still stands well at the highest displacement, 1600 nm, while the undesired cracks occur on other structures with approximately 800 nm of displacement. The robustness could improve 50% in comparison to the other designs thanks to this unique design. Finite element method simulation results showed that this PI layer contributed to decrease the stress concentrated at the edge both in the static condition and in the dyanamic vibarion of the membrane. This layer also probably played a role in prevention of the peeling of the edge of the island-shaped Mono-PZT. In conclusion, the new design is useful for the Mono-PZT pMUT in terms of excellent mechanical robustness.

本文介绍了一种具有单晶Pb（Zr，Ti）O ₃的压电微机械超声换能器（pMUT）的新设计。基薄膜（Mono-PZT）用于增强机械强度。在这项研究中，我们研究了两种设计概念来抑制Mono-PZT中的裂纹产生。首先，通过仅在pMUT膜上留下岛型Mono-PZT图案来限制Mono-PZT的面积。其次，Mono-PZT的边缘覆盖有聚酰亚胺（PI）薄膜作为保护层，以防止剥离。我们准备了三种不同的设计，一个具有两个概念的新设计，另一个具有第一个概念的设计，以及没有一个用于比较的常规设计。这些设备的鲁棒性机械分析是通过共振驱动并增加膜的位移来进行的。根据这些结果，提出的具有两种概念的结构在最高位移1600 nm，而其他位移约800 nm的结构上会出现不希望的裂纹。得益于这种独特的设计，与其他设计相比，其耐用性可以提高50％。有限元方法模拟结果表明，该PI层有助于降低膜在静态和动态振动时集中在边缘的应力。该层也可能在防止岛状Mono-PZT边缘剥落方面发挥了作用。总之，就卓越的机械强度而言，新设计对Mono-PZT pMUT很有用。有限元方法模拟结果表明，该PI层有助于降低膜在静态和动态振动时集中在边缘的应力。该层也可能在防止岛状Mono-PZT边缘剥落方面发挥了作用。总之，就卓越的机械强度而言，新设计对Mono-PZT pMUT很有用。有限元方法模拟结果表明，该PI层有助于降低膜在静态和动态振动时集中在边缘的应力。该层也可能在防止岛状Mono-PZT边缘剥落方面发挥了作用。总之，就卓越的机械强度而言，新设计对Mono-PZT pMUT很有用。