A multilayered gate stack having improved reliability (i.e., low charge trapping and gate leakage degradation) is provided. The inventive multilayered gate stack includes, from bottom to top, a metal nitrogen-containing layer located on a surface of a high-k gate dielectric and Si-containing conductor located directly on a surface of the metal nitrogen-containing layer. The improved reliability is achieved by utilizing a metal nitrogen-containing layer having a compositional ratio of metal to nitrogen of less than 1.1. The inventive gate stack can be useful as an element of a complementary metal oxide semiconductor (CMOS). The present invention also provides a method of fabricating such a gate stack in which the process conditions of a sputtering process are varied to control the ratio of metal and nitrogen within the sputter deposited layer.