A convenient method

low-angle X-ray reflectivity measurement method

is presented to characterize the parameters of low-Z material layers in bilayer structures using X-ray diffractometer (XRD). Because the low-Z material optical constant is similar to the silicon (Si) substrate

the change of the low-Z material layer profiles is difficult to determine.Therefore

an ultra-thin metal layer is deposited as the Base Layer (BL) onto the substrate prior to the low-Z material layer. By choosing chromium (Cr) as the BL material

three Cr/C bilayer films with different C deposition times are fabricated and measured. After the simulation of the reflectivity curves

the density of C is approximately 2.25 g/cm

3

while the deposition rate of C layer is 0.058 nm/s under our laboratory conditions.