与CMOS工艺和电压兼容的CMOS-MEMS数字微镜阵列

Micro-mirror array is the most vital component in the image projection display systems, which have wide applications in industrial area including 3D scanning image and machine vision. In commercial area, they can be used for entertainment applications such as surround visions, movie-theater and projection mapping. In recent years, they also have found emerging applications in consumer electronic products such as interactive display and augmented reality devices. Nonetheless, the micro-mirror device market has been almost monopolized by a US company, Texas instruments, due to the powerful protection of patents, due to which the exploration to new applications of micro-mirrors has been constrained..To overcome this situation, an innovative contribution should be made to create a new type of micro-mirror array that surpasses the performance of the conventional devices. From this point of view, lowering the drive voltage (called pull-in voltage) would be a key point, where a novel MEMS actuation mechanisms are to be developed. In this proposal, we use hidden vertical comb-drive mechanism beneath the micro-mirror element crated by the CMOS back-end-of-line metal layers based on our previous study. The high-density electrode structures have effective change in the electrostatic capacitance, and hence effectively exerts large electrostatic force per footprint, thereby lowering necessary operation voltages. This proposal also plans to develop a new numerical-analytical hybrid model for the micro-mirror that is integrated with the hidden vertical-comb drive mechanism, which is helpful to swiftly predict the operation voltage. Owing to the Spice-based architecture, the simulation model is co-solved with integrated circuits at high precision, at high computational efficiency, and clear reasoning to physical pictures. For practical implementation of the micro-mirror device, we use the reliable CMOS-MEMS processes within the typical design rules of CMOS PDK (process design kit), and its electro-mechanical properties will be investigated to verify the feasibility of the developed simulation model..In summary, this proposal intends to explore the new technical approaches for highly integrated and low-cost CMOS-MEMS micro-mirror arrays, thereby delivering a new optical engine for the projection display systems that could be used in wide range of the next generation consumer electronics.

微镜阵列是广泛应用于投影显示系统中的关键器件。美国德州仪器公司的数字微镜几乎垄断市场，需要创造一种新型微镜阵列打破局面。降低微镜工作电压是关键突破口。本申请拟采用CMOS金属互连层制备一种隐藏式垂直梳齿驱动的微镜，并通过Post-CMOS工艺降低扭臂弹性，将吸合电压降至CMOS工作电压范围，实现微镜与电路单片集成，降低芯片面积和成本。通过数值仿真-理论分析相结合的方法，建立包含三维复杂电极静电驱动器的解析模型，指导微镜结构设计。基于该模型，通过力学特性和电学元件的数学映射，建立微镜电路模型，与驱动电路协同仿真，研究驱动电路和时序。在CMOS设计规则和工艺约束下，研究高可靠性的Post-CMOS工艺完成器件制备。测试微镜的电学-力学特性，验证解析模型和联合仿真的有效性。预期完成一种与CMOS工艺和工作电压全面兼容的高集成度投影显示用数字微镜阵列芯片，为下一代消费电子产品提供一种新的光学引擎。

微镜阵列芯片是广泛应用于投影显示系统的关键图像产生器。传统上在商业电影放映、会议投影等场合有广泛的应用，近年来在虚拟现实智能眼镜、车载智能灯、抬头显示系统、车载前挡风玻璃显示等新兴应用中极具竞争力。新兴应用对于投影显示系统的尺寸、重量和成本要求较高，产生了对高集成度高分辨的微镜阵列芯片的需求，来降低控制系统的复杂程度、光学系统尺寸和整机的重量。降低微镜的吸合电压是关键突破口之一。..本项目建立了两个吸合电压模型：（1）不同形状平行板静电驱动的微镜的吸合电压的快速计算的解析模型。（2）通过数值仿真-理论分析相结合的方法，建立包含三维复杂电极静电驱动器的吸合电压的有限元和解析混合模型。采用上述模型对我们的器件和第三方器件计算吸合电压，计算结果与测试结果基本吻合。..项目执行期间，采用CMOS工艺设计了四种微镜结构：（1）隐藏式垂直梳齿驱动的微镜；（2）活动转轴支撑的微镜结构；（3）V型悬臂梁支撑微镜结构；（4）单端固支悬臂梁支撑的微镜结构。通过增加静电驱动器的有效面积，降低静电驱动器电极之间的间距，降低支撑结构的弹性，将吸合电压降至接近CMOS工作电压范围。仿真计算结果表明，吸合电压为7.6-56V。..本项目开发了两种CMOS-MEMS工艺，（1）Post-CMOS-MEMS工艺，采用标准CMOS工艺制备电路和微镜，然后在实验室中完成Post CMOS工艺来释放微镜，实现了1×8规模单片集成微镜阵列芯片。（2）与CMOS代工厂合作开发量产工艺，实现了120×200规模微镜阵列。..测试微镜的电学-力学特性，验证解析模型和仿真的有效性。隐藏式垂直梳齿驱动器的微镜的吸合电压测试结果典型值为：50 V和33 V。因为实验室工艺一致性不足的问题，导致测试结果较为分散。..本项目在基于器件模型的快速设计工具、器件结构和工艺三个方面研究了与CMOS工艺和工作电压全面兼容的微镜结构，验证了高集成度投影显示用数字微镜阵列芯片的可行性并奠定了技术基础。