Fracture Properties of Silicon Carbide Thin Films by Bulge Test of Long Rectangular Membrane

Abstract

This paper reports the mechanical properties and fracture behavior of silicon carbide (3C-SiC) thin films grown on silicon substrates. Using bulge testing combined with a refined load-deflection model of long rectangular membranes, which takes into account the bending stiffness and prestress of the membrane material, the Young's modulus, prestress, and fracture strength for the 3C-SiC thin films with thicknesses of 0.40 and 1.42 µm were extracted. The stress distribution in the membranes under a load was calculated analytically. The prestresses for the two films were 322 ± 47 and 201 ± 34 MPa, respectively. The thinner 3C-SiC film with a strong (111) orientation has a plane-gstrain moduli of 415 ± 61 GPa, whereas the thicker film with a mixture of both (111) and (110) orientations exhibited a plane-strain moduli of 329 ± 49 GPa. The corresponding fracture strengths for the two kinds of SiC films were 6.49 ± 0.88 and 3.16 ± 0.38 GPa, respectively. The reference stresses were computed by integrating the local stress of the membrane at the fracture over edge, surface, and volume of the specimens and were fitted with Weibull distribution function. For the 0.40-µm-thick membranes, the surface integration has a better agreement between the data and the model, implying that the surface flaws are the dominant fracture origin. For the 1.42-µm-thick membranes, the surface integration presented only a slightly better fitting quality than the other two, and therefore, it is difficult to rule out unambiguously the effects of the volume and edge flaws.[ 2007-0191]Index Terms-Bulge test, fracture property, microelectromechanical systems (MEMS), silicon carbide (SiC) thin films, Weibull distribution function.

Stiction-Induced Sealing of Surface Micromachined Channels

“…This corresponds with an analysis of similar microchannels made of SiN x [38]. Thin membranes of polycrystalline 3C-SiC characterized by bulge testing show fracture strengths between 3.2 GPa and 6.5 GPa [45]. The stress at the pillar junctions largely exceeds these values, thus explaining the rupture of the membrane.…”

Measurement of Young’s modulus and residual stress of thin SiC layers for MEMS high temperature applications

“…Table 1 gives an overview of some published results. Bulge testing is widely employed for determining Young's modulus and residual stress of polycrystalline 3C-SiC (Fu 2005); (Roy et al 2006);(von Berg et al 1996) as well as single crystal 3C-SiC (Mehregany et al 1997);(von Berg et al 1996); (Zhou et al 2008); (Mitchell et al 2003). In this method, pressure-dependent membrane deflection is measured.…”

“…However, the method is sensitive to inaccuracies in deflection measurement and sample preparation (Mitchell et al 2003). Zhou et al (2008) has performed bulge testing of long rectangular membranes. Using a simplified model that assumes plane-strain deformation in the membrane middle section, a plane-strain modulus E ps can be measured.…”

Fabrication Technique of Deformation Carriers (Gratings and Speckle Patterns) with FIB for Microscale/Nanoscale Deformation Measurement

“…As mechanics researchers, we focus on the characterization of their mechanical properties, which are important factors affecting not only their performance but also the basis to analyze their reliabilities. Estimation of fundamental mechanical property requires that displacements and strains be measured at micron and submicron length scale [1][2][3][4][5], which means traditional macroscopic experimental testing methods like moiré method and digital image correlation (DIC) method are no longer applicable and it is urgent to develop novel microscopic testing methods.…”