Application Of ZnMgO On The High-κ MOSFET And TTFT

The fast development of information technology requires integrated circuit to be greater integrated, faster functioned and lower power-consumed, which lead to continuous shrinkage of MOS and DRAM feature size and the thickness of MOS gate dielectrics (SiO₂) would soon scale down to its physical limit. Under this trend the high-K dielectrics is a promising solution for the future development of CMOS technology. Another trend is the new material systems application in TFT for next generation panel display technology. We have made a serics of investigation on fabrication and characteristics of high-K ZnMgO thin film on MOSFET and ZnMgO stacks on TFT. Main innovation results are listed as below:Highly (002) oriented Cubic ZnMgO (C-ZnMgO) films were grown in a physical evaporation low-temperature deposition system (PELD). As-grown thin films show clear interface on the silicon. The thin films have good thermal stability and good crystal quality with smaller than 0.4° FWHM observed by XRD spectra after annealing at 400-700 ℃ in O₂ atmosphere. After fabrication into MIS structure, good dielectrics property with dielectrics constant 10.5 was attained. Permittivity is de-gradated when frequency more than 1MHz. C-ZnMgO thin film after 400℃ annealing was found to greatly reduce leakage current down to 3 orders. Of 550℃ annealing leads to high quality thin film. The reason is that at 550℃ annealing the mobile ions defect in the film were annihilated. Of 900℃ annealing shows reverse characteristics. The mobile ions defect in the film is noticeable which are attributed to Zn migrating toward surface and oxygen loss due to evaporation from the surface. But the film shows high quality interface characteristics, which could be attributed to the formation of Mg silicate layer in the interface. Those structural and electrical characteristics are helpful to MOSFET processing.Great efforts have been made for the high-K C-ZnMgO MOSFET process. The current-voltage (I-V) characteristics of MOSFET were systematically studied. The output characteristic value is lower than our Medici tool simulation result and the output curve shows insufficient in the saturation region. Those are attributed to...