The stresses in periodic Mo/Si, W/Si, and Mo/C multilayer films were determ
ined from wafer-curvature measurements. The layer thickness of each materia
l was varied systematically, and parametric stress contours were generated,
showing contours of constant stress in the two-dimensional layer thickness
parameter space. These results illustrate that the net stress in a periodi
c multilayer is not an intrinsic property of the film (for specific deposit
ion conditions) but, rather, depends strongly on the individual layer thick
nesses. X-ray diffraction measurements show (a) how the lattice spacing in
the W and Mo crystallites varies with layer thickness, and (b) in the case
of the W/Si films, how the phase composition of the polycrystalline W layer
s vary with W layer thickness. In the case of the W/Si and Mo/Si multilayer
s, irreversible stress changes were observed after the samples were stored
in air at room temperature for a period of several months. Stress-temperatu
re measurements made on the as-deposited W/Si and Mo/Si samples also reveal
irreversible stress changes (both positive and negative, depending on the
layer thicknesses) after thermal cycling to 300 degrees C; x-ray diffractio
n measurements were used to identify any associated changes in the W and Mo
microstructure. We describe mechanisms that can explain the observed stres
s behavior, and also discuss the significance of these results, particularl
y with regard to the use of these films for high-performance multilayer x-r
ay optics. (C) 2000 American Vacuum Society. [S0734-2101(00)01703-6].