SBIR Phase II: Investigation of Charge Trapping in Plasma Enhanced Chemical Vapor Deposition (PECVD) Dielectrics Using Electrostatically Actuated Mechanical Resonators

这个小型企业创新研究（SBIR）二期项目建议为一系列用于医学成像的超声波换能器开发高质量的介电薄膜和结构。第一阶段开发的表征介电体电荷捕获行为的技术和方法是将微制造超声换能器从当前状态转变为商业可行状态所需的关键创新。器件中高电场产生的电荷捕获对换能器的性能是有害的。电荷捕获依赖于磁场极性，并引起机电转换效率随时间的变化。换能器阵列中电荷捕获的变化更具破坏性。将开发一种消除电荷捕获的极性依赖性的工艺，从而使新型双极超声成像阵列能够提高图像质量。由于性能和可靠性对这些超声探头的成功商业化至关重要，因此将研究介电充电如何导致性能的时间依赖性损失和可能限制使用寿命的材料退化问题。微制造超声换能器（MUT）的开发和商业化是针对医疗应用市场。这项工作还将使超声探头的发展能够为医生提供更准确的非侵入性诊断信息，例如提高区分癌组织和良性组织的能力。图像质量与价格之比推动了全球30亿美元超声诊断市场的市场份额。这些新型超声换能器将显著提高图像质量/价格比，从而在产品发布时实际创造5%的市场份额波动。具体来说，在与拟议研究最相关的10亿美元的放射学市场中，MUT探头的引入将产生5000万美元的年度系统销售额，其中约三分之一是直接探头销售。

This Small Business Innovation Research (SBIR) Phase II project proposes to develop high quality dielectric films and structures for a family of ultrasonic transducers for medical imaging applications. The technology and methods developed in Phase I to characterize charge-trapping behavior of dielectrics are the critical innovations required to take micro-fabricated ultrasonic transducers from their current state to a commercially viable state. Charge trapping created by the high electric fields in the device is detrimental to transducer performance. Charge trapping is dependent on field polarity and causes shifts in electromechanical conversion efficiency in time. Variations in charge trapping within a transducer array are even more disruptive. A process that removes the polarity dependence of charge trapping and thereby enables a new type of bipolar ultrasound imaging array that improves image quality will be developed. Since performance and reliability are critical to successful commercialization of these ultrasound probes, the issues of how dielectric charging causes time-dependent loss in performance and material degradation that could limit lifetime will be researched. The development and commercialization of micro-fabricated ultrasound transducers (MUT) is targeted at the medical applications market. This work will also enable the development of ultrasound probes that can non-invasively provide more accurate diagnostic information for doctors, such as improved ability to distinguish between cancerous and benign tissue. The image quality to price ratio drives market share in the global $3Billion diagnostic ultrasound market. These novel ultrasonic transducers will significantly improve the image quality/price ratio, and thus realistically create market share swings of 5% upon product release. Specifically, in the $1Billion mid-to-premium segment of the radiology market most relevant to the proposed research, $50M of annual system sales would be generated by the introduction of MUT probes, of which approximately one third are direct probe sales.