With the increasing requirements for microelectromechanical systems (MEMS) regarding stability, miniaturization and integration, novel materials such as wide band gap semiconductors are attracting more attention. Polycrystalline SiC has first been implemented into Si micromachining techniques, mainly as etch stop and protective layers. However, the outstanding properties of wide band gap semiconductors offer many more possibilities for the implementation of new functionalities. Now, a variety of technologies for SiC and group III nitrides exist to fabricate fully wide band gap semiconductor based MEMS. In this paper we first review the basic technology (deposition and etching) for group III nitrides and SiC with a special focus on the fabrication of three-dimensional microstructures relevant for MEMS. The basic operation principle for MEMS with wide band gap semiconductors is described. Finally, the first applications of SiC based MEMS are demonstrated, and innovative MEMS and NEMS devices are reviewed.

http://iopscience.iop.org/article/10.1088/0022-3727/40/20/S19/pdf

Group III nitride and SiC based MEMS and NEMS: materials properties, technology and applications

Silicon carbide (SiC) is recognized as the leading semiconductor for high power and high temperature electronics owing to its outstanding electrical properties combined with mature processing technologies for monolithic structures. SiC has long been known for its outstanding mechanical and chemical properties making it equally attractive for mechanical structures in micro- and nanoelectromechanical systems (MEMS and NEMS). Recent advancements in bulk and surface micromachining have led to the development of SiC analogues to common Si-based devices (i.e., resonators, pressure sensors). This paper presents an overview of MEMS and NEMS technologies that incorporate SiC as a key component in their mechanical structure, providing both a historical perspective as well as recent developments. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Micro‐ and nanomechanical structures for silicon carbide MEMS and NEMS

not available for EP1633673Abstract of corresponding document: US2004245586There are many inventions described and illustrated herein. In one aspect, the present invention is directed to a MEMS device, and technique of fabricating or manufacturing a MEMS device, having mechanical structures encapsulated in a chamber prior to final packaging and a contact area disposed at least partially outside the chamber. The contact area is electrically isolated from nearby electrically conducting regions by way of dielectric isolation trench that is disposed around the contact area. The material that encapsulates the mechanical structures, when deposited, includes one or more of the following attributes: low tensile stress, good step coverage, maintains its integrity when subjected to subsequent processing, does not significantly and/or adversely impact the performance characteristics of the mechanical structures in the chamber (if coated with the material during deposition), and/or facilitates integration with high-performance integrated circuits. In one embodiment, the material that encapsulates the mechanical structures is, for example, silicon (polycrystalline, amorphous or porous, whether doped or undoped), silicon carbide, silicon-germanium, germanium, or gallium-arsenide.

Microelectromechanical systems having trench isolated contacts, and methods for fabricating same

This review article through light on a highly promising & demanding technology, which is set to revolutionize nearly every product category in present era, while discussing the Concept, Design & Development, Fabrication techniques and applications of micro electro-mechanical systems (MEMS) based Devices or systems. Microelectromechanical system discloses outstanding flexibility and adaptability in miniaturization devices followed by their compact dimension, low power consumption, and fine performance. The MEMS devices have numerous and very high potentials of creating a new field of applications for mobile equipment’s with increased flexibility & more reliability. This work deals with research carried out for the development of MEMS based sensors & Actuators and appropriate uses of MEMS. This work carries information’s regarding subsequent commercial and real life applications of MEMS and discusses various recent technological innovations carried out with their advantages & disadvantages. This work also describes the historical development of micro-electromechanical system (MEMS) sensor technology.

/pdf/mems-technology-a-review-3ce419hf6o.pdf

MEMS Technology: A Review

As demand for lower power and higher performance nano-electronic products increases, the semiconductor industry must adopt insulating materials with progressively lower dielectric constants (ie low-k) in order to minimize capacitive related power losses in integrated circuits However in addition to a lower dielectric constant, low-k materials typically exhibit many other reduced material properties that have limited the ability of the semiconductor industry to implement them In this article, we demonstrate that the reduced material properties exhibited by low-k materials can be understood based on bond constraint and percolation theory Using a-SiC:H as a case study material, we utilize nuclear reaction analysis, Rutherford backscattering, nuclear magnetic resonance and transmission Fourier transform infra-red spectroscopy measurements to determine the average coordination (〈r〉) for these materials Correlations of 〈r〉 to Young's modulus, hardness, thermal conductivity, resistivity, refractive index, intrinsic stress, mass density and porosity show that an extremely wide range in material properties (in some cases several orders of magnitude) can be achieved through reducing 〈r〉 via the controlled incorporation of terminal Si Hx and C Hx groups We also demonstrate that the critical point at 〈r〉 ≤ 24 predicted by constraint theory exists in this material system and places limitations on the range of properties that can be achieved for future low-k a-SiC:H materials

https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=914260

Influence of network bond percolation on the thermal, mechanical, electrical and optical properties of high and low-k a-SiC:H thin films

There is a need for chemically resistant coatings that protect the exposed surface of microfluidics components. Pinhole free films with low stress and a good uniformity on flat and inclined surfaces are required. In this study, amorphous silicon carbide (SiC) thin films have been deposited by RF magnetron sputtering on hat surfaces and into micromachined cavities of Si (100). The variation of RF power, deposition pressure and substrate bias voltage have been studied. Depending on the deposition conditions, the film stress can be adjusted from - 1400 MPa to + 100 MPa. Modifications of the deposition rate and the morphology between normal and inclined (54.7 degrees) planes have been observed. Optimal chemical stability was found with slightly compressive (-100 MPa) SiC thin films. No degradation of the protective layer has been observed after 3 h in KOH at 80 degrees C. (C) 2000 Elsevier Science S.A. All rights reserved.

N. Xantopoulos

Papers

Sputtered silicon carbide thin films as protective coating for MEMS applications