利用干涉显微镜测量Ge-Sb-Te薄膜中相变图案的深度

Amorphous-to-crystalline phase-change technology is a promising candidate for high-density, low-power memory. The volume change associated with the phase-change is several percent, and understanding it is extremely important. The deformation of the phase-change region was investigated using an "optical" phase-shifting interferometric microscope (PSI), a "physical" stylus profilometer, and an atomic force microscope (AFM). The crystallized regions of the amorphous Ge 2 Sb 2 Te 5 film (thickness ~ 200 nm) irradiated with laser light became concave, and the depth depended on the light energy density. At the laser energy density of ~ 9.0 J/mm 2 , the depth was ~ 15 nm using PSI and ~ 10 nm using a stylus. The result that PSI overestimates the depth can be explained by the difference in the complex refractive index n + i k of the phase-change film. This is useful information when optically evaluating the shape of a phase-change region.