Si3N4 and SiO2 layers can be deposited by reactive sputtering in a stable manner by using MF twin magnetron systems, The increasing demand for these materials for industrial applications makes it necessary to find new solutions for the target material. The up to now mostly used boron-doped poly-crystalline silicon suffers from serious drawbacks. In this paper, properties of Si3N4, and SiO2 layers deposited by using casted Si/Al alloy targets as well as conventional Si targets are compared. The advantages of using casted alloy targets are presented,