Advanced Microsystems through alternative microfabrication processes

世界经济论坛一份关于制造业未来的报告强调了灵活、快速和低成本制造的必要性。该项目为下一代微系统提出了与这一愿景相一致的框架，并得到了三大支柱方面的进步的支持：制造技术、设备级创新和主要是数字化的系统架构，易于适应和重新配置。未来的微系统将包括在柔性或刚性衬底上的微换能器(阵列或簇)上的混合集成、薄的接口模拟层和在低功率现成硅芯片上实现的先进的数字信号处理算法。印刷天线的集成还将在复杂的物联网结构中增加无线互联，其中处理能力可以委托给云。低成本、快速制造的支柱依赖于像SU-8这样的材料的光聚合过程的健壮性，即使与改变其物理化学性质的颗粒/分子混合也是如此。功能化的SU-8薄层可以通过高分辨率无掩模光刻进行图案化，因此它们可以用于定义(电和光)互连、无源元件和微型传感器，从化学传感器到移动的MEMS结构。这项技术不仅可以在带有现成芯片的柔性基板上实现高密度混合集成，还可以实现芯片级集成(硅芯片顶部的薄聚合物传感器层)。为了实现进一步的可扩展性，现代器件级技术将利用机电耦合来提高微尺度的灵敏度：稳定边界上的操作、弱耦合谐振器中的参数放大和模式局部化效应。第三个支柱涉及系统级体系结构，其中将模拟电子接口最小化的愿望导致了基于滑模控制的主要数字闭环系统。三种目标应用将验证这一愿景：(1)用于惯性导航的先进惯性测量单元(IMU)；(2)基于聚合物CMUT阵列的超声成像换能器；(3)用于流体分析的带有嵌入式微流控通道的共振聚合物悬臂阵列。IMU将验证基于聚合物的平面可移动MEMS结构技术，并将使用高灵敏度加速度计通过数字滑模控制工作在其稳定边界上，而陀螺仪的灵敏度将通过参数放大来增强。CMUT阵列将验证离面电气驱动和密封。与常规的频移传感技术相比，具有成型微流控通道的弱耦合悬臂梁将利用模式局部化效应来提高传感器的数量级灵敏度。

A World Economic Forum report on the future of manufacturing emphasized the need for flexible, rapid and low cost manufacturing. The project proposes a framework for the next generation microsystems aligned with this vision, supported by advances in three supporting pillars: manufacturing technology, device level innovations and a mostly-digital system architecture, easy to adapt and reconfigure. The microsystems of the future will consist of the hybrid integration on flexible or rigid substrates of microtransducers (arrays or clusters), a thin interfacing analog layer and advanced digital signal processing algorithms implemented on low-power off-the shelf silicon dies. The integration of printed antenna will also add the wireless interconnectivity in complex IoT structures, where the processing power can be delegated to the cloud. The low-cost, rapid manufacturing pillar relies on the robustness of photo-polymerization process of materials like SU-8, even when mixed with particles/molecules that modifies its physico-chemical properties. Functionalized SU-8 thin layers can be patterned by high resolution maskless lithography, so that they can be used to define (electrical and optical) interconnects, passive components, and microtransducers, from chemical sensors to moving MEMS structures. The technology will allow not only a high-density hybrid integration on flexible substrates with off-the-shelf dies, but also a die level integration (thin polymer sensor layer on the top of a Si die). To enable further scalability, modern device level techniques will exploit the electromechanical coupling to enhance the sensitivity at microscale: operation on the stability border, parametric amplification and mode localization effects in weakly-coupled resonators. The third pillar addresses the system-level architecture, where the desire to minimize the analog electronic interface leads to mostly digital closed-loop systems, based on sliding mode control. Three target applications will validate the vision: (1) an advanced inertial measurement unit (IMU) for inertial navigation, (2) an ultrasound imaging transducer based on polymer CMUT arrays and (3) a resonant polymer cantilever array with embedded microfluidic channels for fluid analysis. The IMU will validate the polymer-based technology for in-plane movable MEMS structures, and will use high-sensitivity accelerometers operated on their stability border through digital sliding mode control, while the gyroscope sensitivity will be enhanced through parametric amplification. The CMUT array will validate the out-of-plane electrical actuation and hermetic sealing. The weakly-coupled cantilevers with shaped microfluidic channels for fluid analysis will exploit mode localization effects to increase the sensitivity of the sensors with orders of magnitude compared to the common frequency shift sensing technique.