IMPROVEMENT OF THE CANTILEVER BEAM TECHNIQUE FOR STRESS MEASUREMENT DURING THE PHYSICAL VAPOR-DEPOSITION PROCESS

An improvement of an optical method for in situ measurement of the int rinsic stress in thin films is described. The method presented is base d on the well-known beam bending technique using the deflection of a l aser beam that reflects itself on a sample. The first new development lies in the evaluation of the bending plate equation. The second uses image processing to determine the deformation of the sample. The metho d has been applied to pure chromium films on glass substrates to valid ate the stress measurements. The reproducibility of stress measurement is of about 8%. Results show the great adaptability of the technique to any kind of stress evolution during the physical vapor deposition p rocess and give additional information about the evolution of stress v ersus film thickness, in comparison with ex situ techniques, Finally, a correlation between stress measurement and microstructure has been c arried out. (C) 1998 American Vacuum Society.