Technology development and study of rapid thermal CVD high-K gate dielectrics and CVD metal gate electrode for future ULSI MOSFET device integration : zirconium oxide, and hafnium oxide
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CMOS technology has been so successful in improving device performance, shrinking device size and achieving good reliability. Based on the ITRS (International Technology Roadmap for Semiconductors), a premise of the Roadmap has been that continued scaling of microelectronics. The 2001 ITRS map showed highlights several challenges such as limitation of lithography, integration of complicate structures, introducing new material into the manufacturing, and shrinking of gate oxide thickness. The most challenging issue is the replacing silicon dioxide as a gate dielectric of MOSFET because it affects important transistor characteristics as well as device reliabilities. And the other issues for the device scaled less than 65nm are polysilicon gate depletion and quantum mechanical effect. CVD oxynitride or plasma nitridation of silicon dioxide will be used 90nm generation even though high dielectric gate materials have been investigated intensively. Because there are immense task still remained to integrate high–k material into manufacturing. This dissertation will present research on advanced gate dielectrics (zirconium oxide, and hafnium oxide) processed by MOCVD (Metal Organic Chemical Vapor Deposition) method that have been developed for ULSI MOSFET devices. Also CVD TaN as well as PVD TaN metal gate electrodes were studied for hafnium oxide gate electrode MOSFET application. And it is found that zirconium oxide is compatible with metal gate process and hafnium oxide is stable for both poly silicon and metal gate electrode. And furthermore refractive metal gate electrodes (TiN, TaN) were also demonstrated with both PVD and CVD method and found CVD metal gate electrode is more preferred for future generation MOSFET device.