Electrical Properties And Reliability Studies Of Novel Nanodevices

The Moore's Law and the rule of scaling-down have been the guiding principles for the development of Integrated Circuits (ICs) over the last 50 years. With the geometric shrinkage, many new effects appear, such as the most important reliability issue of nano MOSFETs-Bias temperature instability (BTI). In addition, traditional Si technology is approaching its physical limit and a variety of innovative electronic devices emerge. As one among them, carbon nanotube network based thin-film transistors (CNN-TFTs) have gained enormous attentions for their superior electrical properties, improved process controllability and unique flexibility.With the development of novel materials, technology and devices, the conventional electrical characterization methods face many new challenges, such as the characterization of the recovery effect in BTI, which are still not well-dissolved yet. In addition to the characterization methods, the electrical properties of the emerging deceives, for instance, the effective gate capacitance (CG) and the carrier mobility (?) of the CNN-TFTs are still lack of complete studies.This thesis has launched some frontier researches mainly focusing on the fabrication, electrical characterization, electrical properties, and reliability of the nano-devices. It includes:(1) For the recovery effect of BTI in nano-MOSFETs, much effort was spent on building a new type of fast pulsed ID-VG measurement (FPM) system to accurately extract the stress induced threshold voltage shift (?Vt) and developing a modified charge pumping (MCP) method to quasi real-time examining the generations of interface trapped charges (?Nit). (2) By the new measurement techniques, the BTI effects of nano-MOSFETs have been systematically studied, including all four different configurations:NBTI of pMOSFETs, PBTI of pMOSFETs, NBTI of nMOSFETs and PBTI of nMOSFETs. (3) By the combination of drop-casting process and lithography technique, CNN-TFTs were fabricated. A pulsed ID-VG method with gate pulses of alternating polarities (AP) and conventional C-V measurements were innovatively employed to the CNN-TFTs. we have systematically investigated the effective gate capacitance and the transfer characteristics of the CNN-TFTs. Our main results are:(1) Combing FPM and MCP methods, we have quantitatively decomposed the contributions of interface trapped charges and oxide charges in BTI effects of nano-MOSFETs under different stress conditions. (2) We found that:in BTT effects, expect for the influence from interface traps, the contribution from the trapping/detrapping of oxide charges is also curial, which must be taken into account when modeling BTI effects. (3) With the AP pulsed ID-VG and C-V measurements on CNN-TFTs, we have obtained hysteresis-free transfer characteristics and the strong correlation between the gate capacitance and nanotube density. Based on these, a new methodology to obtain the apparent carrier mobility has been established.These studies have provided new methods, models and results for device fabrication, electrical characterization, electrical property analysis and reliability evaluation of nano-MOSFETs. It is of important scientific significance and practical value for the research and development of emerging devices.