Next-generation high performance MEMS ultrasonics

下一代高性能 MEMS 超声波

• 批准号: 567531-2021
• 负责人: Zemp, RogerRJ
• 金额: $ 6.95万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Alliance Grants
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=753098
• 关键词: Next; generation; performance; MEMS; ultrasonics

It has long been hypothesized that capacitive micromachined ultrasound transducers (CMUTs) could potentially outperform piezoelectric technologies. However, challenges with dielectric charging, operational hysteresis, and transmit sensitivity have stood as obstacles to these performance outcomes. Typically, a CMUT element is designed with an ensemble of smaller membranes oscillating together to transmit or detect ultrasound waves. However, this approach can lead to unreliable behavior and suboptimal transmit performance if these smaller membranes oscillate out of phase, or collapse at different voltages. After nearly 15 years of work, we recently designed reliable CMUT elements composed of a single long rectangular membrane, that can outperform piezoelectrics. We explored various architectural modifications to the CMUT cavity in order to improve robustness to charging and minimize hysteresis without compromising performance. In order to fabricate CMUTs with these architectural modifications, we developed a double-SOI wafer bonded process with near-100% bonding yield, without the need for aligned bonding. The fabricated single-membrane CMUTs achieved electromechanical efficiency values as high as 0.95, higher than values reported with either piezoelectric transducers or CMUT elements. Moreover, these single-membrane CMUTs exhibited transmit efficiency 2-5 times greater than published CMUT or piezoelectric transducer elements in the 1.5-2.0 MHz range. Our devices demonstrated considerable charging robustness, demonstrating minimal charging over millions of collapse-snapback actuation cycles, while also mitigating hysteresis. In this proposal, we aim to further improve these devices for next-generation high-performance MEMS ultrasonics. Improvements will include high-K dielectrics enabling higher combined transmit and biasing voltages. We also propose an inverted CMUT architecture for piston-like motion, development of high-density through-silicon via technology, and development of prototype linear and 2D arrays. We aim to demonstrate the advantages of our technology using head-on comparisons against state-of-the art commercial probes.

长期以来，人们已经假设电容性微机械超声传感器（CMUTS）可能会超过压电技术。然而，介电充电，操作磁滞和传输敏感性的挑战已经成为这些性能结果的障碍。通常，CMUT元件的设计是由较小的膜的合奏一起振荡，以传输或检测超声波。但是，如果这些较小的膜偏置振荡或在不同电压下倒塌，则这种方法可能导致不可靠的行为和次优的发射性能。经过将近15年的工作，我们最近设计了由单个长矩形膜组成的可靠CMUT元素，该元素的表现可以超越压电。我们探索了对CMUT腔的各种体系结构修饰，以提高稳健性，以最大程度地减少磁滞，而不会损害性能。为了通过这些架构修改来构建CMUT，我们开发了一个双SOI晶圆键合工艺，其键合收益率接近100％，而无需对齐键合。制造的单膜cmuts实现了高达0.95的机电效率值，高于用压电传感器或CMUT元素报告的值。此外，这些单膜CMUTs在1.5-2.0 MHz范围内发表的CMUT或压电传感器元件的发射效率比发表的CMUT或压电传感器元件高2-5倍。我们的设备表现出相当大的充电性鲁棒性，显示出数百万种倒塌的驱动循环的最小充电性，同时也减轻了滞后。在此提案中，我们旨在进一步改善这些设备，以实现下一代高性能MEMS超声波。改进将包括高K电介质，可实现较高的组合发射和偏置电压。我们还提出了一种倒置的CMUT架构，用于活塞样运动，通过技术开发高密度通过Silicon以及线性和2D阵列的原型开发。我们的目标是使用与最先进的商业探针进行正面比较来证明我们技术的优势。