Measurements of residual stresses in the Parylene C film/silicon substrate using a microcantilever beam

A series of Parylene C film/silicon substrate bilayer microcantilever beams were fabricated by microelectromechanical processes for the study of residual stresses. The Parylene C films of 2 £gm thickness were deposited on the Si substrates with various thicknesses. After deposition at room temperature, deflection of the beam was observed with deposited Parylene C on the concave side. While Parylene C has a higher coefficient of thermal expansion than Si, this deflection is believed to result from the thermal mismatch between Parylene C and Si, and the temperature of monomer gas (which is formed at 690 ¢XC) flowing across the sample could be higher than 25 ¢XC. It is estimated to be 73 ¢XC based on the fitting of the curvature versus substrate thickness relation between the measurements and analytical solutions. In this case, Parylene C films are subjected to tension. In addition, the residual stress in the Parlyene C film decreases with decreasing substrate thickness. ? 2013 IOP Publishing Ltd.