Electrical characteristics and thermal stability of MOS devices with MoN/TiN metal stacks and various gate dielectrics were studied in this work. High work function (5.0 eV) gate is achieved by integrating MoN/TiN stack with HfAlO dielectric. The gate stack structures can enhance the thermal stability and reduce the interaction between the metal gate and the dielectric. The Ti diffusion in the dielectric can be suppressed by AlN in HfAlO. Reliability characteristics, in terms of stress-induced leakage current and stress-induced V-fb shift, are improved for metal gate stack on HfAlO high-k dielectric in comparison with that on SiO2. The work function of metal gate also can be turned by different Al contents in high-k dielectrics and metal gate stacks (4.88-5.0 eV). (C) 2010 Elsevier Ltd. All rights reserved.