Comparison of thermal stability of Mo/Si multilayers with different crystallinities of Mo layers

To investigate the thermal stability of Mo/Si multilayers with different initial crystallinities of Mo layers, two kinds of Mo/Si multilayers were deposited by DC magnetron sputtering and annealed at 300 degrees C and 400 degrees C. The period thickness compactions of multilayers with crystalized and quasi-amorphous Mo layers were 0.15 nm and 0.30 nm at 300 degrees C, respectively, and the stronger the crystallinity, the lower the extreme ultraviolet reflectivity loss. At 400 degrees C, the period thickness compactions of multilayers with crystalized and quasi-amorphous Mo layers were 1.25 nm and 1.04 nm, respectively. It was shown that multilayers with a crystalized Mo layer had better thermal stability at 300 degrees C but were less stable at 400 degrees C than multilayers with a quasi-amorphous Mo layer. These changes in stability at 300 degrees C and 400 degrees C were due to the significant transition of the crystalline structure. The transition of the crystal structure leads to increased surface roughness, more interdiffusion, and compound formation. (c) 2023 Optica Publishing Group