Modification of the Mechanical Properties of SiO₂ Thin Film Using Plasma Treatments for Micro-Electro-Mechanical Systems Applications

Abstract

In this study, we developed a novel method of modifying thin-film mechanical properties by plasma surface modification. In order to demonstrate the feasibility of this approach, various plasma treatments, including exposure to O 2 , H 2 , and NH 3 atmospheres, were implemented to modify the mechanical properties, including Young's modulus, residual stress, and hardness, of SiO 2 films. The experimental results show that the mechanical properties have been changed following the formation of SiN and Si-H bonds. These characteristics can be employed to change the shape and resonant frequencies of micromachined beams for micro-electro-mechanical systems (MEMS) applications. Since plasma treatment is simple and easy to integrate with existing processes, it has the potential to be an efficient way to finely modify the mechanical characteristics of MEMS structures.

Patterning and growth of carbon nanotubes on a highly structured 3D substrate surface

“…This work extends the planar-based CNT structures to 3D profiles; meanwhile, the integration of 3D-patterned CNTs into suspended MEMS devices is also achieved. This study exploits three key processes-plasma treatment [27][28][29], self-assembled coating of octadecyltrichlorosilane (OTS) monolayer and contact displacement electroless (CDE) plating [30,31]-to prevent the limitation of complicated surface topology imposed by photolithography and film deposition processes. Thus, as shown in figure 1, the present processes can implement (1) conformal formation of 3D CNT patterns on a highly structured Si surface, as shown in figures 1(a) and (b), (2) further integration of these 3D patterns of CNTs with suspended MEMS devices, as shown in figure 1(c), and (3) transfer of the 3D patterns of CNTs onto flexible polymer substrates, as shown in figure 1(d).…”