DESIGN OF 2 DEVICES FOR BIAXIAL STRESSES AND THEIR APPLICATION TO SILICON-WAFERS

Two devices have been constructed for the development of biaxial stres ses and the study of deformation potentials on thin layers. In the fir st device hydrostatic pressure was employed to develop a two-dimension al stress environment on thin silicon wafers. The deformation of the p lates was found to be related to the third root of the pressure applie d, in good agreement with theory. The second apparatus used a central force for the bending of the wafer, and the stresses, as detected from the frequency shift of the silicon phonon line in the Raman spectra, were confined to a small area af the plate. In both devices an analyti c relation between the radius of curvature at the centre of the wafer and the stresses developed was established.