Charge trapping properties of alternative high-kappa dielectrics in MOS devices |
Posted on:2007-09-19 | Degree:Ph.D | Type:Dissertation |
University:Vanderbilt University | Candidate:Zhou, Xing | Full Text:PDF |
GTID:1448390005974547 | Subject:Engineering |
Abstract/Summary: | |
High-kappa dielectrics are promising candidates to replace SiO 2 in advanced integrated circuits in future space systems. Studies of the effects of ionizing radiation and bias-temperature stress (BTS) on high-kappa dielectrics were performed. Trapped charge densities are evaluated as functions of temperature and stress time. Prior radiation exposure enhances BTS-induced degradation in these devices. Worst-case responses in combined effects are positive (or zero) bias irradiation followed by NBTS for HfO2-based devices. Degradation due to oxide or interface trap-charge changes in magnitude with the bias polarity during switched-bias annealing either after irradiation or constant voltage stress (CVS). This demonstrates that metastable electron trapping (dominant during post-rad annealing) and hydrogen transport and reactions (dominant during post-CVS annealing) in the near-interfacial dielectric layers play significant roles in the defect formation process. Additional defect growth with time was observed as a result of additional charge injection through the gate stacks during the annealing process. These results provide insights into fundamental trapping properties of high-kappa dielectrics and can be used to help predict long-term reliability of these devices. |
Keywords/Search Tags: | High-kappa dielectrics, Trapping, Devices, Charge |
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