CAREER: High-Temperature Thermal Transport in LPCVD Polysilicon for MEMS

本研究计划研究低压化学气相沉积(LPCVD)多晶硅中高温微结构变化对微电子机械系统(MEMS)中微尺度热传输现象的影响。应用热传导物理、材料科学和硅微机械加工技术，为多晶硅热敏传感器和驱动器的设计及其可靠性预测提供了新的科学知识。为了实现高温下的研究，利用MEMS技术开发了一种新型的片上仪器。该仪器用于测量多晶硅薄膜的热输运特性，并允许原位观察晶粒度的演变。基于所获得的实验数据，通过考虑颗粒尺寸、颗粒构型、杂质浓度和微观结构动力学，对热输运进行了理论模拟。所开发的模型用于理解多晶硅MEMS器件和CMOS型晶体管的定标规律和设计规则。该教育计划针对MEMS工程师在传热学方面的重大需求，目的是为学生“优化产品设计”做好准备。该项目利用校内信息技术资源，以MEMS热设计竞赛为基础，开发了一门新的传热学课程。热设计项目要求学生团队提出一种MEMS设计，该设计应该为受热传递现象影响很大的特定设备产生更好的品质因数。这门课程是为各种工程专业的大四学生和研究生设计的。为了促进学员之间的有效沟通，本课程实施了基于网页的教学。

This research program investigates the impact of high-temperature microstructural changes in Low Pressure Chemical Vapor Deposited (LPCVD) polysilicon on microscale thermal transport phenomena in microelectromechanical systems (MEMS). An application of thermal conduction physics, materials science, and silicon micromachining is made for generating new scientific knowledge needed for the design of polysilicon-based thermal sensors and actuators, and for their reliability predictions. To achieve studies at high-temperatures, a novel on-chip instrument is developed using MEMS techniques. The instrument is to measure thermal transport property of polysilicon films and allows for in situ observation of grain size evolution. Based on the acquired experimental data, theoretical work is performed to model thermal transport by accounting for grain size, grain configuration, impurity concentrations, and microstructural kinetics. The developed model is to serve for understanding scaling laws and design rules for polysilicon-based MEMS devices and CMOS transistors. The education program addresses the significant demands on heat transfer education for MEMS engineers with the purpose of preparing students for "optimizing a product design." Using on-campus information technology resources, this program develops a new heat transfer course based on a MEMS thermal design competition. The thermal design project asks student teams to propose a MEMS design that should yield a better figure of merit for a particular device, which is strongly influenced by heat transfer phenomena. The course is designed for senior and graduate students from various engineering programs. A web-page-based instruction is implemented for this course to promote effective communications among the participants.