An apparatus for measuring stress in thin films

Abstract

The average stress in thin films can be obtained by measuring the bending produced in a thin substrate by the action of the film. If the substrate is cantilevered, the deflection of the free end of the substrate is proportional to the average stress in the film. In the device described here, an electronic microbalance is used to measure the deflection of the free end of the cantilevered substrate. Continuous measurement of the film stress, in situ, during film deposition is readily accomplished with this apparatus. The sensitivity is such that continuous measurements of the film stress are possible up to film thicknesses of about 2000 Å. Furthermore, the substrate temperature can be varied from -195 to 350°C. Several examples of film stress in different materials at various substrate temperatures are shown. The limitations and experimental accuracy of this device are discussed. © 1969 The American Institute of Physics.