Fabrication And Investigation Of High K Gate Dielectric Materials For Next Generation MOSFET Applications

With the quick development of microelectronics, the size of semiconductor devices is becoming smaller and smaller according to the'Moore law'. SiO2, as the present gate dielectric, can't satisfy this trend in the coming several years. Thus the research of high k gate dielectric materials for next generation metal-oxide-semiconductor field effect transistors (MOSFET) applications has become a focus in the field of present microelectronic materials. According to the analysis of physical properties, we select LaAlO3 as the candidate material for its medium dielectric constant and good chemical stability. Pulsed laser deposition (PLD) is a novel film deposition technique, which proves to be very advantageous in preparation of multicompent oxides, especially those with high melting point. In our research work, LaAlO3 (LAO), LaAlOxNy (LAON) films and ultra thin LAO, LAON films were deposited by PLD. Their microstructures, chemical stability, electrical properties and the interfacial reactions with Si substrates were studied systematically. The film growth parameters were also optimized. It is found for the first time that LAO especially LAON is very promising in the future application for next generation MOSFET. At the same time, Zr-Sn-Ti-O and Zr-Sn-Ti-O-N oxide films were deposited by PLD and their microstructures and electrical properties were studied. These research results indicate that they may be used in DRAM. The following are our main research results:1,The most stable amorphous high k gate dielectric material up to now has been obtained.Using a single crystal LaAlO3 target, LAO, LAON films and ultra thin LAO, LAON films were deposited on clean single crystal Si substrate and Pt coated silicon substrates in oxygen ambient (or low vacuum) and nitrogen ambient by PLD, respectively. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results indicate that films are amorphous. Differential thermal analysis (DTA) measurements showed that their crystallization temperatures are as high as 850℃,...