Study on Stress–Strain Characteristics of SiO2 Films for High-Temperature SiC Capacitive Pressure Sensors Using FEA and Dimensional Analysis of Nanoindentation

Abstract

Silicon dioxide (SiO2) thin film has attracted tremendous attention in recent years for high-temperature SiC capacitive pressure sensors (CPSs) due to its superior physical and electrical properties. The calculation of capacitance for CPSs is highly dependent on the intrinsic mechanical characteristics of SiO2 films. However, its plastic parameters, particularly in high temperatures, have rarely been considered in the previous calculation of capacitance by finite element simulations. In this article, nanoindentation tests were first carried out to obtain Young’s modulus of annealed SiO2 films grown by low-pressure chemical vapor deposition (LPCVD) technique and its variation after 1 h of high-temperature treatment in the air (600, 700, 800, and 900 °C), respectively, and then, the plastic parameters of each sample were calculated in combination with finite element analysis (FEA) and dimensional analysis of nanoindentation. Herein, the results demonstrated that the optimal value of representative strain <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sigma _{{\text {r}}}$ </tex-math></inline-formula> was 0.091 in dimensional analysis. Furthermore, the material parameters of each sample were imported into ANSYS Workbench for finite element simulations, and the maximum indentation depth <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${h}_{m}$ </tex-math></inline-formula> and the residual indentation depth <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${h}_{{\text {r}}}$ </tex-math></inline-formula> results were within 4% and 10% errors between simulations and nanoindentation tests, respectively. Therefore, this work provides an available reference to the parameters’ acquisition and capacitance calculation of CPSs.