The investigation of Ti-doped high-k dielectrics deposited on polycrysalline silicon

• Main Authors: Yu Tsung Pan, 潘煜琮
• Other Authors: C. H. Kao
• Format: Others
• Online Access: http://ndltd.ncl.edu.tw/handle/91667581654783432951

碩士 === 長庚大學 === 電子工程學研究所 === 98 === In this thesis, we studied the Ti-doped high-k materials such as Er2TiO3, Gd2TiO5 to replace traditional SiO2 insulator in thin film transistors and DRAM technology applications. The RF sputtering was used to deposit these high-k materials combined with post-RTA treatment to remove and passivate the defects between the high-κ materials and the polysilicon in order to improve the characteristics of the poly-oxide dielectrics. Besides, the comparison of characteristics between Ti-doped and without Ti-doped high-k materials was also investigated. The polycrystalline silicon replacing Si was used as substrate, there are existed some drawbacks such as rough interface, more interface traps, and grain boundary trap states in polycrystalline silicon. Therefore, using Ti-doped high-k materials combined with RTA treatment can improve dielectric quality and reduce defects and traps. The Ti-doped high-k dielectric can exhibit excellent properties such as higher breakdown field, lower charge trapping, and lager charge to breakdown better than the dielectric without Ti-doped. This is due to that TiO2 has high dielectric constant K (~80), smaller band gap, better thermal stability, larger breakdown electric fields. Besides, combining with the post rapid thermal annealing treatment, those defects and trap states existed in the high-k and polysilicon grain boundary can be passivated to form stronger bondings for the improvements of electrical and physical characteristics of the high-k dielectrics.