Ultrananocrystalline diamond thin films for MEMS and moving mechanical assembly devices
Ultrananocrystalline diamond thin films for MEMS and moving mechanical assembly devices
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DOI：
10.1016/s0925-9635(01)00385-5
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发表时间：
2001-11-01
影响因子：
4.1
通讯作者：
Ding, MQ
中科院分区：
文献类型：
--
作者：
Krauss, AR;Auciello, O;Ding, MQ
由于可用的表面加工技术，MEMS器件目前主要在硅中制造。基于Si的MEMS技术的主要问题是Si具有差的机械和摩擦学特性[J. J. Sniegowski，in：B. Busan（Ed.），MEMS中的摩擦学问题和机遇，Kluwer学术出版社，荷兰，1998年，第325页; A. P. Lee，A. P. Pisano，M.G.林脱线Res. Soc. Symp. 276（1992）67.]，并且实际的MEMS器件目前主要限于仅涉及弯曲和挠曲运动的应用，例如悬臂加速度计和振动传感器。然而，由于Si的弯曲强度和断裂韧性较差，以及Si粘附在亲水表面的倾向，即使这些简单的设备也具有有限的动态范围。未来涉及显著滚动或滑动接触的MEMS应用将需要使用具有显著改善的机械和摩擦学性能的新材料，以及在恶劣环境中良好表现的能力，金刚石是一种具有高机械强度，特殊化学惰性和出色热稳定性的超硬材料。其脆性断裂强度是Si的23倍，预计磨损寿命是Si的10000倍。然而，作为已知最硬的材料，金刚石是出了名的难以制造。传统的CVD薄膜沉积方法提供了一种制造超小金刚石结构的方法，但是该膜具有大的晶粒尺寸、高的内应力、差的晶间粘附力和非常粗糙的表面，因此不适合MEMS MMA应用。类金刚石薄膜也正在研究应用于MEMS器件。然而，它们主要涉及物理气相沉积方法，其不适合于在高纵横比特征上的良好保形沉积，并且通常它们不表现出金刚石的突出机械性能。我们在这里展示了一种新的微波等离子体技术的应用，使用一种独特的C-60/Ar或CH 4/Ar化学，产生相纯超纳米金刚石（UNCD）涂层的形态和机械性能，非常适合于MEMS应用一般，特别是MMA的使用。我们开发了用于制造UNCD-MEMS组件的光刻技术，包括杠杆和多级器件，作为微轴承和齿轮的前体，使UNCD成为开发高性能MEMS器件的有前途的材料。(C)2001 Elsevier Science B. V.保留所有权利。
MEMS devices are currently fabricated primarily in silicon because of the available surface machining technology. A major problem with the Si-based MEMS technology is that Si has poor mechanical and tribological properties [J.J. Sniegowski, in: B. Bushan (Ed.), Tribology Issues and Opportunities in MEMS, Kluwer Academic Publisher, The Netherlands, 1998, p. 325; A.P. Lee, A.P. Pisano, M.G. Lim, Mater. Res. Soc. Symp. Proc. 276 (1992) 67.], and practical MEMS devices are currently limited primarily to applications involving only bending and flexural motion, such as cantilever accelerometers and vibration sensors. However, because of the poor flexural strength and fracture toughness of Si, and the tendency of Si to adhere to hydrophilic surfaces, even these simple devices have limited dynamic range. Future MEMS applications that involve significant rolling or sliding contact will require the use of new materials with significantly improved mechanical and tribological properties, and the ability to perform well in harsh environments, Diamond is a superhard material of high mechanical strength, exceptional chemical inertness, and outstanding thermal stability. The brittle fracture strength is 23 times that of Si, and the projected wear life of diamond MEMS moving mechanical assemblies (MEMS MMAs) is 10 000 times greater than that of Si MMAs. However, as the hardest known material, diamond is notoriously difficult to fabricate. Conventional CVD thin film deposition methods offer an approach to the fabrication of ultra-small diamond structures, but the films have large grain size, high internal stress, poor intergranular adhesion, and very rough surfaces, and are consequently ill-suited for MEMS MMA applications. Diamond-like films are also being investigated for application to MEMS devices. However, they involve mainly physical vapor deposition methods that are not suitable for good conformal deposition on high aspect ratio features, and generally they do not exhibit the outstanding mechanical properties of diamond. We demonstrate here the application of a novel microwave plasma technique using a unique C-60/Ar or CH4/Ar chemistry that produces phase-pure ultrananocrystalline diamond (UNCD) coatings with morphological and mechanical properties that are ideally suited for MEMS applications in general, and MMA use in particular. We have developed lithographic techniques for the fabrication of UNCD-MEMS components, including cantilevers and multi-level devices, acting as precursors to microbearings and gears, making UNCD a promising material for the development of high performance MEMS devices. (C) 2001 Elsevier Science B.V. All rights reserved.