The paper describes a technique for manufacturing of sub-micron metal membranes based on magnetron deposition of multilayer structures. Tensile stress, biaxial elastic modulus and mechanical strength of 25–50nm thick multilayer Mo/ZrSi2 membranes were measured, and the behavior of these parameters before and after vacuum heating of samples at the level of heat loads up to 1W/cm2 was studied. The elastic properties were obtained from measurements of deformation dependence of the round membranes on the applied pressure differential. A rapid increase in tensile stress of a 25nm thick Mo/ZrSi2 film was observed at a uniform heat load of 0.25W/cm2 which was probably caused by desorption of water molecules from the membrane surface.