scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Mechanical and structural properties of RF magnetron sputter-deposited silicon carbide films for MEMS applications

TL;DR: In this paper, the authors reported preparation and characterization of silicon carbide (SiC) films obtained by RF magnetron sputtering using a SiC ceramic target, and the residual stress of the films was measured as a function of sputtering parameters.
Abstract: In the present work, we report preparation and characterization of silicon carbide (SiC) films obtained by RF magnetron sputtering using a SiC ceramic target. The films were deposited in Ar ambient without external substrate heating. The residual stress of the films was measured as a function of sputtering parameters. The stress of the as-deposited films was observed to be compressive for the entire range of sputtering parameters used in the present work. Postdeposition annealing at 400 ?C in N2?ambient was useful in reducing the stress in the films. On sequentially annealing the films at higher temperatures (600 and 800 ?C), the nature of the stress changed from low compressive to high tensile. A superhard SiC film with low residual compressive stress (58.7 MPa) was obtained with hardness and Young's modulus values of 49.86 GPa and 363.75 GPa respectively. The x-ray diffraction pattern revealed that the films were either amorphous or nano-crystalline, depending on the deposition parameters and postdeposition annealing temperature. Atomic force microscopy roughness results confirmed good chemical stability of the films in potassium hydroxide and buffered hydrofluoric acid solutions. Several types of micro-structures were fabricated to demonstrate the feasibility and compatibility of these films in MEMS fabrication.
Citations
More filters
Journal ArticleDOI
TL;DR: In this paper, the physical, mechanical and tribological properties of various surface coatings and their impact on the replication efficiency and lifetime of micro/nano-molds that are used in micro-nano hot-embossing and injection molding processes are discussed.
Abstract: Micro/nano hot-embossing and injection molding are two promising manufacturing processes for the mass production of workpieces bearing micro/nanoscale features. However, both the workpiece and micro/nano-mold are susceptive to structural damage due to high thermal stress, adhesion and friction, which occur at the interface between the workpiece and the mold during these processes. Hence, major constraints of micro/nano-molds are mainly attributed to improper replication and their inability to withstand a prolonged sliding surface contact because of high sidewall friction and/or high adhesion. Consequently, there is a need for proper surface coating as it can improve the surface properties of micro/nano-molds such as having a low friction coefficient, low adhesion and low wear rate. This review deals with the physical, mechanical and tribological properties of various surface coatings and their impact on the replication efficiency and lifetime of micro/nano-molds that are used in micro/nano hot-embossing and injection molding processes.

65 citations

Journal ArticleDOI
TL;DR: An outstanding electrochemical performance of Si@SiC-0.5 is attributed to the SiC phase, which acts as a buffer layer that stabilizes the nanostructure of the Si active phase and enhances the electrical conductivity of the electrode.
Abstract: Here, we propose a simple method for direct synthesis of a Si@SiC composite derived from a SiO2@C precursor via a Mg thermal reduction method as an anode material for Li-ion batteries. Owing to the extremely high exothermic reaction between SiO2 and Mg, along with the presence of carbon, SiC can be spontaneously produced with the formation of Si. The synthesized Si@SiC was composed of well-mixed SiC and Si nanocrystallites. The SiC content of the Si@SiC was adjusted by tuning the carbon content of the precursor. Among the resultant Si@SiC materials, the Si@SiC-0.5 sample, which was produced from a precursor containing 4.37 wt % of carbon, exhibits excellent electrochemical characteristics, such as a high first discharge capacity of 1642 mAh g–1 and 53.9% capacity retention following 200 cycles at a rate of 0.1C. Even at a high rate of 10C, a high reversible capacity of 454 mAh g–1 was obtained. Surprisingly, at a fixed discharge rate of C/20, the Si@SiC-0.5 electrode delivered a high capacity of 989 mAh g...

51 citations

Journal ArticleDOI
TL;DR: In this article, the impact of various deposition parameters such as the reactive gas flow ratio, plasma power, substrate temperature and chamber back pressure of ICP-CVD deposited a-SiC:H thin films is investigated and the influence on important MEMS-related properties like residual stress, Young's modulus, hardness, mass density and refractive index is evaluated.
Abstract: In this study, the impact of various deposition parameters such as the reactive gas flow ratio, plasma power, substrate temperature and chamber back pressure of ICP-CVD deposited a-SiC:H thin films is investigated and the influence on important MEMS-related properties like residual stress, Young’s modulus, hardness, mass density and refractive index is evaluated. Basically, tailoring of the as-deposited a-SiC:H characteristics is possible to a great extent with residual stress values ranging from −16 up to −808 MPa, Young’s modulus values between 36 and 209 GPa or deposition of layers with hardness values ranging from 5.3 to 27.2 GPa is feasible. Especially the mechanical parameters are strongly linked to both the Si C bond density and the amount of incorporated hydrogen obtained from Fourier transform infrared spectroscopy analyses.

22 citations

Journal ArticleDOI
01 May 2017-Silicon
TL;DR: In this paper, the formation of 3C-SiC films has been confirmed from low angle XRD analysis, Raman spectroscopy, Fourier transform infrared (FTIR), XPS and dark and photoconductivity measurements.
Abstract: Cubic nanocrystalline silicon carbide (3C-SiC) films have been deposited by using the hot wire chemical vapor deposition (HW-CVD) method at a low substrate temperature and at high deposition rate. Structural, optical and electrical properties of these films have been investigated as a function of H2 dilution ratio. The formation of 3C-SiC films has been confirmed from low angle XRD analysis, Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, x-ray photoelectron spectroscopy (XPS) and dark and photoconductivity measurements. The FTIR spectroscopy analysis revealed that the bond densities of Si-H and C-H decrease while that of Si-C increases with increase in the H2 dilution ratio. The total hydrogen content decreases with increase in H2 dilution ratio and was found < 15 at. % over the entire range of H2 dilution ratio studied whereas the band gap show an increasing trend with increase in the H2 dilution ratio.

13 citations

Journal ArticleDOI
TL;DR: In this article, an intrinsic and doped, hydrogen-less amorphous silicon films are RF magnetron sputter deposited and post-hydrogenated in a remote hydrogen plasma reactor at a temperature of 370°C.

9 citations

References
More filters
Journal ArticleDOI
TL;DR: In this paper, the current status of SiC technology for a wide range of sensor applications is reviewed, and it is shown that SiC MEMs devices are well-established with operational devices demonstrated at high temperatures (up to 500 °C) for the sensing of motion, acceleration and gas flow.
Abstract: Silicon carbide has attracted considerable attention in recent years as a potential material for sensor devices. This paper reviews the current status of SiC technology for a wide range of sensor applications. It is shown that SiC MEMs devices are well-established with operational devices demonstrated at high temperatures (up to 500 °C) for the sensing of motion, acceleration and gas flow. SiC sensors devices using electrical properties as the sensing mechanism have also been demonstrated principally for gas composition and radiation detection and have wide potential use in scientific, medical and combustion monitoring applications.

225 citations

Journal ArticleDOI
TL;DR: In this paper, simple equations are proposed for determining elastic modulus and hardness properties of thin films on substrates from nanoindentation experiments, and the formulation may be inverted to enable deconvolution of film properties from data on the film/substrate bilayers.
Abstract: Simple equations are proposed for determining elastic modulus and hardness properties of thin films on substrates from nanoindentation experiments. An empirical formulation relates the modulus E and hardness H of the film/substrate bilayer to corresponding material properties of the constituent materials via a power-law relation. Geometrical dependence of E and H is wholly contained in the power-law exponents, expressed here as sigmoidal functions of indenter penetration relative to film thickness. The formulation may be inverted to enable deconvolution of film properties from data on the film/substrate bilayers. Berkovich nanoindentation data for dense oxide and nitride films on silicon substrates are used to validate the equations and to demonstrate the film property deconvolution. Additional data for less dense nitride films are used to illustrate the extent to which film properties may depend on the method of fabrication.

215 citations

Journal ArticleDOI
TL;DR: In this article, a review of reactive ion etching of SiC polytypes (3C and 6H) is presented, with the primary emphasis on the 3C and the 6H polytypes, but some results on the 4H polytype are included.
Abstract: Research and development in semiconducting silicon carbide (SiC) technology has produced significant progress in the past five years in many areas: material (bulk and thin film) growth, device fabrication, and applications. A major factor in this rapid growth has been the development of SiC bulk crystals and the availability of crystalline substrates. Current leading applications for SiC devices include high power and high temperature devices and light emitting diodes. Due to the strong bonding between Si and C (Si-C = 1.34 x Si-Si), wet chemical etching can only be performed at high temperature. Therefore, plasma-based (dry) etching plays the crucial role of patterning SiC for the fabrication of various electronic devices. In the past several years, reactive ion etching (RIE) of SiC polytypes (3C and 6H) has been investigated in fluorinated gases (primarily CHF3, CBrF3, CF4, SF 6 , and NF 3 ), usually mixed with oxygen and occasionally with other additives or in a mixture of fluorinated gases. In this paper, a review of SiC RIE is presented. The primary emphasis is on etching of the 3C and 6H polytypes, but some results on RIE of the 4H polytype are included. The paper covers the basic etching mechanisms, provides typical etching properties in selected plasma conditions, discusses the effects of changes in various etching parameters, such as plasma pressure, density and power, etching time, etc. The etching of features of sizes varying from sub-μm to tens of μm's is addressed. Finally, optimum etching conditions and trade-offs are considered for various device configurations.

147 citations

Journal ArticleDOI
TL;DR: In this article, the properties of amorphous hydrogenated or hydrogen-free silicon carbide thin films were determined by using nanoindentation and bulge techniques, respectively, and it was shown that both hardness and Young's modulus are dependent on the film composition.
Abstract: Due to its interesting mechanical properties, silicon carbide is an excellent material for many applications. In this paper, we report on the mechanical properties of amorphous hydrogenated or hydrogen-free silicon carbide thin films deposited by using different deposition techniques, namely plasma enhanced chemical vapor deposition (PECVD), laser ablation deposition (LAD), and triode sputtering deposition (TSD). a-SixC1−x: H PECVD, a-SiC LAD, and a-SiC TSD thin films and corresponding free-standing membranes were mechanically investigated by using nanoindentation and bulge techniques, respectively. Hardness (H), Young’s modulus (E), and Poisson’s ratio (v) of the studied silicon carbide thin films were determined. It is shown that for hydrogenated a-SixC1−x: H PECVD films, both hardness and Young’s modulus are dependent on the film composition. The nearly stoichiometric a-SiC: H films present higher H and E values than the Si-rich a-SixC1−x: H films. For hydrogen-free a-SiC films, the hardness and Young’s modulus were as high as about 30 GPa and 240 GPa, respectively. Hydrogen-free a-SiC films present both hardness and Young’s modulus values higher by about 50% than those of hydrogenated a-SiC: H PECVD films. By using the FTIR absorption spectroscopy, we estimated the Si-C bond densities (NSiC) from the Si-C stretching absorption band (centered around 780 cm−1), and were thus able to correlate the observed mechanical behavior of a-SiC films to their microstructure. We indeed point out a constant-plus-linear variation of the hardness and Young’s modulus upon the Si-C bond density, over the NSiC investigated range [(4–18) × 1022 bond · cm−3], regardless of the film composition or the deposition technique.

139 citations

Journal ArticleDOI
TL;DR: In this article, the formation of superhard materials in the ternary system boron-carbon-nitrogen (T-BN) was investigated, and it was shown that knock-on subplantation and ion-plating-induced increase of surface mobility and substrate-temperature-induced crystallisation are the three main parameters affecting the creation of strong covalent bonding.
Abstract: Superhard materials such as nanocrystalline cubic boron nitride (c-BN) and β -silicon carbide ( β -SiC) as well as amorphous boron carbide (B 4 C) and highly tetrahedral amorphous carbon (ta-C) are produced by radio frequency (RF) unbalanced magnetron sputtering in combination with intense ion plating in a pure argon discharge. As a result of energy and mass analysis the film-forming fluxes Φ n consist of sputtered atomic target components and the plating flux Φ Ar + of argon ions. Subplantation, ion-plating-induced increase of surface mobility and substrate-temperature-induced crystallisation are the three main parameters affecting the formation of superhard phases with strong covalent bonding. Knock-on subplantation allows the formation of B 4 C with hardness up to 72 GPa at a flux ratio Φ Ar + / Φ n of 3 for a plating energy of 75 eV. Also c-BN and ta-C can be produced with similar parameters. In the case of SiC, densification is diminished by preferential sputtering of Si and consequently stochiometry and hardness are adversely affected. However, intense ion plating with a low ion energy of 25 eV and small film-forming fluxes shift the temperature of the phase transition from amorphous to nanocrystalline β -SiC from the usual value of >900 °C to about 420 °C. Furthermore, investigations of the formation of superhard materials in the ternary system boron–carbon–nitrogen are reported.

101 citations