Study on the influence of residual stress on the mechanical characteristics of free-standing Si-membranes processed by DRIE process

Publication date: Available online 6 March 2019Source: Sensors and Actuators A: PhysicalAuthor(s): S. Boominathasellarajan, P. Saravanan, K.K. Pandey, V. Srihari, H.K. PoswalAbstractThe mechanical behavior of free-standing Si membranes (diaphragms) fabricated by deep reactive ion etching (DRIE) was studied in order to emphasis the magnitude of process-induced stress and/or strain distribution in both square and circular diaphragms. For this purpose, 25-μm thick circular and square diaphragms with 4-mm diameter (or side-size) were fabricated using silicon-on-insulator wafer. The thickness and surface homogeneities of the DRIE processed Si-diaphragms were analyzed by SEM and AFM, respectively. Micro-Raman spectroscopy studies revealed a non-uniform distribution of compressive stresses throughout the diaphragm surface. Using the synchrotron based Laue diffraction measurements, the residual stress values were quantitatively estimated as 19.88 and -22.83 MPa for the unloaded circular and square diaphragms, respectively. The pressure vs. displacement experiments were conducted using the bulge testing method and these studies yielded maximum mid-point deflection values of 25 and 30 µm for the circular and square diaphragms, respectively against applied pressure of 25 kPa. Based on the deflection characteristics, the average residual stress and equivalent biaxial modulus were estimated by means of standard analytical equations. Using the finite element analysis, the mid-point...

Source: Sensors and Actuators A: Physical - March 8, 2019 Category: Physics Source Type: research