On the determination of poisson’s ratio of stressed monolayer and bilayer submicron thick films

In this paper, the bulge test is used to determine the mechanical properties of very thin dielectric membranes. Commonly, this experimental method permits to determine the residual stress (sigma
₀
) and biaxial Youngpsilas modulus (E/(1- upsi)). Associating square and rectangular membranes with different length to width ratios, the Poissonpsilas ratio (upsi) can also be determined. LPCVD Si
₃
N
₄
monolayer and Si
₃
N
₄
/SiO
₂
bilayer membranes, with thicknesses down to 104 nm, have been characterized giving results in agreement with literature for Si
₃
N
₄
, E = 212 plusmn 114 GPa, sigma
₀
= 420 plusmn 8 and upsi = 0.29.