Thermal Dependency Assessment of Silicon Wafer Behaviour Oriented at Different Angles

In considering the critical role of crystal orientation and working temperature in shaping overall performance of piezoresistive pressure microsensors, this study investigates the effect of wafer orientation (i.e., crystal orientation) and working temperature on thermomechanical and fracture behaviour of a P-type silicon wafer used in pressure sensors. The study was carried out using analytical analysis, based on Kirchhoff–Love plate theory, and numerical analyses side by side with experimental investigations for validation and comparison purposes. The study addresses the following objectives: (1) to investigate the effects of working temperature, wafer positioning and crystal orientation on deflection and fracture behaviour of a silicon membrane; (2) to compare wafer deflections obtained experimentally to those obtained from simulations and numerical approaches; and (3) to determine the effect of maximum wafer deflection on crack initiation and fracture mode through the application of an experimental thermomechanical technique. An agreement between experimental and simulated deflection values of the Si wafer within a temperature range of 25–80 °C was concluded. Moreover, when working temperatures are below 100 °C, the fracture mode is highly brittle when a wafer is oriented at 0° and 45° with respect to [110] directions, whereas the wafer tends to render some ductility at temperatures above 120 °C. It was also found that at room temperature fracture occurs at a deflection of about 389 µm and 463 µm when the crystal is oriented at 45° and 0°, respectively.