An on-chip micro-mechanical test structure is presented to investigate the tribological behavior of deep reactive ion etching (DRIE) sidewall surfaces of microelectromechanical systems (MEMS) devices. The proposed test structure is fabricated on silicon on insulator (SOI) wafer using a standard surface micromachine process. Test structure consists of two orthogonally placed electrostatic comb-drive actuators, one is used to align a contact with the friction surfaces under a certain normal load, and another one is used to generate the tangential motion on contacted sidewall surfaces. To assess the frictional behavior of DRIE sidewall surfaces, both static and dynamic friction coefficients were studied for different DRIE process parameters. Wear analysis was carried out to extract the performance and reliability of MEMS sidewall surfaces during their operation. From the experiment results, it is found that with the increment of normal load, the static friction coefficient exhibits a nonlinear dependence, and however, it has less effect on the dynamic friction coefficient. DRIE process parameters have a significant influence on static and dynamic friction coefficients, i.e., variation in asperity size changes the real contact area between the contact pairs during their operation. From the wear analysis, it is found that the friction coefficient was very high initial value, then it drops with each subsequent cycle for a few cycles and finally reaches steady-state value.

中文翻译：

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用于研究深 RIE MEMS 侧壁表面摩擦学行为的片上微加工测试结构

提出了一种片上微机械测试结构，以研究微机电系统 (MEMS) 设备的深反应离子蚀刻 (DRIE) 侧壁表面的摩擦学行为。建议的测试结构是使用标准表面微机械工艺在绝缘体上硅 (SOI) 晶片上制造的。测试结构由两个正交放置的静电梳状驱动执行器组成，一个用于在一定法向载荷下与摩擦表面对齐接触，另一个用于在接触的侧壁表面上产生切向运动。为了评估 DRIE 侧壁表面的摩擦行为，研究了不同 DRIE 工艺参数的静态和动态摩擦系数。进行磨损分析以提取 MEMS 侧壁表面在其运行过程中的性能和可靠性。从实验结果可以看出，随着法向载荷的增加，静摩擦系数呈现非线性相关性，而对动摩擦系数的影响较小。DRIE 工艺参数对静摩擦系数和动摩擦系数有显着影响，即，凹凸尺寸的变化会改变接触副在操作过程中的实际接触面积。从磨损分析中发现，摩擦系数初始值非常高，然后随着随后的每个循环下降几个循环，最终达到稳态值。静摩擦系数呈现非线性相关性，但对动摩擦系数的影响较小。DRIE 工艺参数对静摩擦系数和动摩擦系数有显着影响，即，凹凸尺寸的变化会改变接触副在操作过程中的实际接触面积。从磨损分析中发现，摩擦系数初始值非常高，然后随着随后的每个循环下降几个循环，最终达到稳态值。静摩擦系数呈现非线性相关性，但对动摩擦系数的影响较小。DRIE 工艺参数对静摩擦系数和动摩擦系数有显着影响，即，凹凸尺寸的变化会改变接触副在操作过程中的实际接触面积。从磨损分析中发现，摩擦系数初始值非常高，然后随着随后的每个循环下降几个循环，最终达到稳态值。