Micro Scale Experiments and Modeling of MEMS RF-Switches

MEMS 射频开关的微尺度实验和建模

• 批准号: 0120866
• 负责人: Horacio Espinosa
• 金额: $ 29.97万
• 依托单位: Northwestern University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-10-01 至 2005-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0120866&HistoricalAwards=false
• 关键词: Micro; Scale; Experiments; Modeling; MEMS

0120866EspinosaA GOALI award supports study of materials properties and problems relevant to the integration of micro-electro-mechanical systems (MEMS) with IC components for wireless applications. These systems offer unique advantages over other technologies because of their low power consumption, high sensitivity, physical size, and low cost. The technology is ideal for next generation of cell phones, base stations for wireless systems, and highly-efficient software-controlled digital radio for military communications. In these applications the MEMS devices are typically used as filters or switches. Filters with Q-factors of 94,000 can be employed to pre-select a communication band and a specific channel within that band. Switches with insertion losses bellow 0.1 dB per switch can be used for electromagnetic beam steering in radar antennas, accomplished through phase shifting. This feature enables antennas to transmit and receive signals without the need for physical reorientation. However, despite the large industrial interest, the technology is not yet commercially viable because a number of technical obstacles have to be overcome first. Key among these are packaging and mechanical modeling of MEMS materials at the micron scale. For instance, in the case of RF-switches, the effect of the environment can result in stiction of the membranes due to humidity or other sources. This requires the development of a cheap hermetic package. From a reliability standpoint, it is necessary to consider the plasticity limit and its temperature dependence with the materials involved. Temperatures as low as minus 50 degrees Celcius can be reached in satellite and airplane wireless applications while temperatures of a few hundred degrees can be present during device packaging. Another important failure mechanism is fatigue caused by excessive actuation cycles. Most of these devices are actuated trillions cycles pushing the design envelope and our current knowledge of material behavior beyond known parameters.In this project the reliability of capacitive RF-MEMS switch materials and components will be investigated. The effect of temperature and number of cycles on material degradation as a result of defects generation and evolution will be examined for aluminum alloy and doped nanocrystalline diamond films. Likewise, the evolution of the built-in stresses will be identified with a nanoindentation technique for use in the SEM, recently developed in the PI's laboratory. Experiments will consist of the deflection of freestanding films, to assess the elastic and inelastic properties of the films, and fatigue analysis by means of successive electrostatic actuation. Evolution of built-in stresses and material microstructure will be assessed as a function of the number of actuation cycles. Modeling of the experiments will be performed at several length scales, from ab initio calculations and molecular dynamics to discrete dislocation and continuously distributed dislocation networks; extensive simulations will link modeling and experiment.***

0120866 EspinosaA GOALI奖支持材料特性和与微机电系统（MEMS）集成无线应用IC元件相关问题的研究。 这些系统因其低功耗、高灵敏度、物理尺寸和低成本而具有比其他技术独特的优势。 该技术是下一代手机、无线系统基站和用于军事通信的高效软件控制数字无线电的理想选择。在这些应用中，MEMS器件通常用作滤波器或开关。 可以采用Q因子为94，000的滤波器来预先选择通信频带和该频带内的特定信道。 每个开关的插入损耗低于0.1 dB的开关可用于雷达天线中的电磁波束转向，通过相移实现。 这一特性使天线能够发射和接收信号，而不需要物理重新定向。然而，尽管有很大的工业兴趣，但该技术在商业上还不可行，因为首先必须克服一些技术障碍。 其中的关键是微米级MEMS材料的封装和机械建模。例如，在RF开关的情况下，由于湿度或其他来源，环境的影响可能导致膜的静摩擦。这就需要开发一种廉价的密封封装。从可靠性的角度来看，有必要考虑塑性极限及其与所涉及材料的温度相关性。在卫星和飞机无线应用中可以达到低至零下50摄氏度的温度，而在设备包装期间可以存在几百度的温度。另一个重要的失效机制是由过度的致动循环引起的疲劳。这些器件中的大多数都经过了数万亿次的驱动循环，这使得设计范围和我们目前对材料行为的了解超出了已知的参数。温度和循环次数对材料退化的影响，作为缺陷的产生和演变的结果，将检查铝合金和掺杂的纳米金刚石薄膜。同样，内置应力的演变将被确定与纳米压痕技术用于扫描电镜，最近在PI的实验室开发。实验将包括独立膜的偏转，以评估膜的弹性和非弹性特性，以及通过连续静电致动的疲劳分析。内置应力和材料微观结构的演变将作为驱动周期数的函数进行评估。实验的建模将在几个长度尺度上进行，从从头计算和分子动力学到离散位错和连续分布的位错网络;广泛的模拟将连接建模和实验。