| Summary: | 碩士 === 逢甲大學 === 電子工程學系 === 107 === This work investigates the characteristics of different gate spacers on negative capacitance of ferroelectric HfZrO2 film of junctionless FET (JL-FET). This thesis is divided into two parts, the first part is to study the characteristics of ferroelectric HfZrO2 film of the metal-insulator-substrate (MIS) structures with different gate spacers. Three kinds of spacers of Al2O3, HfO2 and Si3N4 are studied in this work. Two annealing processes of rapid thermal annealing (RTA) and microwave annealing (MWA) are used to anneal and transfer the ferroelectric HfZrO2 film to the crystal phase of negative capacitance. The RTA process for the all spacers reveals the better characteristic of HfZrO2 film polarization value than that of the MWA process. In addition, the Al2O3 spacer reveals the best characteristic than that of the others. The values of saturation polarization, remanent polarization and the ratio of remanent polarization/coercive voltage are 19.40 μC/cm2, 31.89 μC/cm2 and 10.39 μC/cm2·V. For the results of the MWA process on different spacers of MIS structures, the Si3N4 spacer at 2400 W/300 s condition reveals the best characteristics than that of the others. The values of saturation polarization, remanent polarization and the ratio of remanent polarization/coercive voltage are 16.11 μC/cm2, 22.06 μC/cm2 and 7.71 μC/cm2·V. Thus, the negative capacitance of HfZrO2 film can be fabricated by the low temperature of MWA process.
The second part of this thesis is to study the characteristics of the negative capacitance HfZrO2 JL-FET with and without HfO2 gate spacer. According to the experimental results, the device with HfO2 gate spacer at a dimension of W/L=80 nm /80 nm reveals the better characteristic than that of the device without gate spacer. The superior characteristics of drain induced barrier lowering (DIBL) and the subthreshold swing (S.S.) for the device with HfO2 gate spacer were 55.56 mV/V and 79.46 mV/dec, respectively. In addition, the ratio of ION/IOFF ratio is also large.
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