title: Plastic Deformation of Micromachined Silicon Diaphragms with a Sealed Cavity at High Temperatures.
abstract: Single crystal silicon (SCS) diaphragms are widely used as pressure sensitive elements in micromachined pressure sensors. However, for harsh environments applications, pure silicon diaphragms are hardly used because of the deterioration of SCS in both electrical and mechanical properties. To survive at the elevated temperature, the silicon structures must work in combination with other advanced materials, such as silicon carbide (SiC) or silicon on insulator (SOI), for improved performance and reduced cost. Hence, in order to extend the operating temperatures of existing SCS microstructures, this work investigates the mechanical behavior of pressurized SCS diaphragms at high temperatures. A model was developed to predict the plastic deformation of SCS diaphragms and was verified by the experiments. The evolution of the deformation was obtained by studying the surface profiles at different anneal stages. The slow continuous deformation was considered as creep for the diaphragms with a radius of 2.5 mm at 600 °C. The occurrence of plastic deformation was successfully predicted by the model and was observed at the operating temperature of 800 °C and 900 °C, respectively.
authors: School of Mechanical Engineering, Xi'An Jiaotong University, 28 West Xianning Road, Xi'An 710049, China. juan.ren@mail.xjtu.edu.cn.
authors: Juan
authors: J
authors: Ren
authors: Birmingham City University, Birmingham B5 5JU, UK. michael.ward@bcu.ac.uk.
authors: Michael
authors: M
authors: Ward
authors: Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Loughborough LE11 3UZ, UK. p.kinnell@lboro.ac.uk.
authors: Peter
authors: P
authors: Kinnell
authors: GE Sensing &amp; Inspection Technologies, Leicestershire LE6 0FH, UK. russell.craddock@ge.com.
authors: Russell
authors: R
authors: Craddock
authors: School of Mechanical Engineering, Xi'An Jiaotong University, 28 West Xianning Road, Xi'An 710049, China. seanwei@mail.xjtu.edu.cn.
authors: Xueyong
authors: X
authors: Wei
keywords: microfabrication; plastic deformation; pressure sensor; single crystal silicon