| Summary: | 碩士 === 逢甲大學 === 電子工程學系 === 107 === This thesis studies the effects of different metal gate (stack) materials on ferroelectric negative capacitance HfZrO2 film of junctionless field effect transistor (JL-FET). This thesis is divided into two items. The first item is to study the experimental results of the HfZrO2 using the capacitor structure (metal-insulator-substrate, MIS). The second item is to study the characteristics of different gate metals on the negative capacitance HfZrO2 gate dielectric of the junctionless FET (NC-JLFET).
For the studies of different metal materials or structures, different nitrogen gas ratios of sputtered TaN metal, TiTaN metal, double-stacked metal (TiN/TaN) on the HfZrO2 films are also investigated. The polarization, capacitance and leakage current of the MIS structure with different metals will be discussed and compared. Different single-layer metal materials (TaN, TiN and TiTaN metals) are studied and compared on the ferroelectric HfZrO2 film treated at different microwave annealing (MWA) time. The TaN metal presents the maximum remanent polarization value, the second is the TiTaN metal, and the smallest is the TiN metal. Presumably, the TaN metal has a larger compressive strain on HfZrO2 than that of the TiN metal, resulting in the larger crystal phase and the ferroelectric/negative capacitance formation in the HfZrO2 film.
For the effect of the TaN metal with 5% nitrogen gas ratio as the gate metal on the negative-capacitance junctionless FET (NC-JLFET), the P-type device with a channel width/length of 40 nm/80 nm shows the better characteristics than that of the N-type device. The DIBL, S.S. Ion/Ioff and Vth of P-type JL-FET are 177.81 mV/V, 78.2 mV/dec, 2.21×108 and -0.85 V, respectively. The NC-JLFET with a dimension of W/L= 40 nm/60 nm reveals the better subthreshold swing S.S.= 61.95 mV/dec, indicating that the TaN metal with a nitrogen gas ratio of 5% is beneficial for the technology development of HfZrO2 NC-JLFET. In addition, the better subthreshold swing (S.S.) of the N-type device is 88 mV/dec at a channel W/L of 40 nm/80 nm.
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