A certified reference material of GaAs/AlAs superlattice has been developed for surface chemical analysis. Thin films as well as multilayered films are artifical materials fabricated that achive or modify some specific physical properties and can be applied to various advanced materials such as semiconductor devices, magnetic multilayers, otical mirros, X-ray mirrors, etc. Depth profiling by ion sputtering in surface chemical analysis is one of the most popular techniques to reveal layered materials. Excellent depth resolution on the nm level requires the use of a high quality reference material such as a superlattice which is suitable for the optimization of sputter depth profiling. The certified reference material consists of 4 layers whose thicknesses (~ 23nm) are certified with an accuracy of about 0.3nm and, in addition, whose interface roughness and surface oxide thickness are given as reference data.