Electrical Properties Of HfO₂ And HfO_xN_y Gate Dielectrics

With the continued scaling-down of MOSFET, the ultra-thin gate oxide causes some serious problems of devices. The ultra-thin SiO2 dielectrics cause significant leakage current, consequently increases standby power of device. Meanwhile, the reliability of gate dielectrics is also degraded. These problems boost the study of high-K materials as the alternatives of SiO2 gate dielectrics. Among all High-K gate dielectric materials ,hafnium oxide (HfO2) is being extensively investigated as one of the most promising candidate materials due to its superior thermal stability with poly-si , biggish constant and reasonable band alignment.Our researches focus on HfO2 dielectrics. The HfO2 layer is deposited by means of reactive sputtering. Compared to other commonly referenced high-K materials, HfO2 is known for its stability on silicon and process compatibility. The fabrication and electrical properties of HfO2 and HfOxNy gate are carefully studied.With the study on HfO2.we can receive a few significative conclusion:1. An HfO2 layer with less than 3.5nm EOT was obtained and show good electrical properties. The gate leakage current at a gate voltage bias ofIV is less than 10-7 A/cm2 . The experiments show an roomtemperature in the course of reactive sputtering conduces to restraining the surface reaction between Hf02 and Si layer;2. We studied different surface progress .comparable with conventional method ,the surface with NH4F cleaning step have superior thermal stability with HfO2 ,NH4F cleaning step is introduced can reduces leakage current and EOT;3. We researched fabrication at different asputtering and annealing atmosphere, the different process conduced different electricalproperties .We can conclude a higher annealing temperature and higher proportion of O2 during reactive sputtering favors the improvement of electrical performances of HfO2 dielectrics;4. The analysis of I-V curves of these devices displays different leakage current mechanism under different area of applied bias-voltage; As to SILC. there are different leakage current mechanism at influence of SIl.C;5. With the research on HfOxNy gate dielectrics, it can reduces leakage current and increase crystallizing point;Our research can help to realize the leakage current mechanism and SILC effect of HfO2,futher more it can offer us direction on optimize the fabrication process;...