面向MEMS封装的多孔纳米支架基吸气剂的构效关系及能控吸气行为研究

The getter is an important compositing factor to maintain the vacuum level and improve the performance, life time and stability of MEMS devices packaged in vacuum. Due to the low capacity, the uncontrollable gettering performance and the pre-activated with long time before packaging of current film getters, the bulk manufacturing of MEMS under the miniaturization trend is restricted. Therefore it is proposed in this project a principle method utilizing 3D porous nanostructure combined with activation by micro-area-induction-heating to realize the fabrication and application of getters with high performance. Focusing on some key behavioral problems of controlling depositing behavior, strengthening heat transfer and enhancing diffusion related to 3D surface, it is studied the mechanism of equilibrium gettering and the dynamic response mechanism of efficiency improving gettering of typical getters under the collaborative control of electrical-magnetic-thermal-interface. It is revealed the functioning mechanism how 3D geometric structure affects the dynamic behaviors like nucleation, growing and adsorption of getter material, and the structure-property relationship as well as the controlling principle of getter efficiency enhanced by porous structure is acquired. Then it is established the theoretical model of enhancement of heat transferring, adsorption and diffusion by porous frame under the cooperation of strongly coupled electrical-magnetic-thermal-interface. The controllable adsorption behavior and control principle of activation to re-adsorption are clarified, and it is obtained controlling method to primarily control the vacuum activated after packaging. Hopefully, this project will provide theoretical and technical foundations to the design and optimization of novel functional getters with high efficiency and controllability suitable for MEMS vacuum packaging.

吸气剂是维持真空封装型MEMS器件真空度水平以提升其性能和长期稳定性的重要组成单元，现有薄膜吸气剂低容量、不可调控的吸气性能及长时间先激活的封装方式制约了MEMS器件批量化制备，项目针对高效能吸气剂性能优化和使用调控的应用需求，提出了利用3D多孔纳米支架基和微区感应加热激活相结合的原理方案。围绕多孔3D界面对沉积行为的调控、传热强化、增强激活等关键行为问题，研究纳米多孔衬底3D几何学构型对吸气材料成核、生长、吸附等行为的界面作用机制，掌握多孔结构强化吸气效能的构效关系与调控规律；研究在电-磁-热-界面强耦合协同作用下典型吸气剂增效吸附动力学响应机制，建立多孔支架基传热、吸附、扩散行为的多场耦合理论模型；研究能控吸气及激活/再吸气行为的演化规律，掌握器件封装后激活的真空度调控方法，以期为新型适用于MEMS真空封装用高效、能控、功能型吸气剂的设计与优化提供理论和技术基础。

项目执行按计划顺利进行，完成了原定项目计划内容。针对面向MEMS封装纳米支架基吸气剂的构效关系及吸气行为研究，分别从新型非蒸散型吸气剂测试系统开发、微区电磁感应加热、镍基多级塔状结构制备、复合多孔纳米支架基吸气剂的开发与测试、非蒸散型吸气剂吸附动力学进行研究。通过新型非蒸散型吸气剂测试系统的开发，有效解决了传统吸气剂测试系统漏率误差大、操作复杂、无法完成吸气剂瞬时速率实时检测等弊端，为后续吸气剂性能检测提供一种新的结构与性能测试技术；通过微区电磁感应加热的仿真与测试，分析了磁感线分布情况与感应加热机理，结合电磁感应加热的趋肤效应，选择高磁通量镍作为MEMS局部加热层材料，为后续实验探究提供材料基础；通过塔状多级镍结构制备工艺参数的探究，成功制备大比表面积、可感应加热快速激活吸气剂，测试得到其感应加热温度可达到500℃，满足大部分吸气剂的激活温度，在此支架沉积钛基吸气剂，其吸气容量可达2.57%，相比于平面吸气剂，其吸气容量提升了3倍左右。通过复合多孔纳米支架基吸气剂的开发与测试，制备了硅-镍-多孔氧化铝多层复合结构支架，通过调控孔径大小与薄膜沉积参数，掌握了孔径与沉积吸气剂构效关系，通过复合支架上沉积吸气剂的TGA测试，明确孔洞结构预处理工艺对吸气性能提升，最终获得复合支架最大吸气容量可达到6.01%，较多级镍基吸气剂性能有明显的提升；通过非蒸散型吸气剂吸附动力学研究，成功构建多孔吸附仿真模型与新型吸附算法，从吸附-扩散、分子体系能量角度对吸气剂吸附做出原理性解释与仿真，得到吸附-扩散厚度与速率的相互作用关系。本项目提出的可感应加热型吸气剂支架，可有效解决MEMS封装过程中封装尺寸小与要求吸气容量高的矛盾、吸气剂激活温度与MEMS结构层不可长时间高温保持的矛盾，为、高性能MEMS传感器提供有效的真空封装补偿方法。