ScholarWorks@중앙대학교

초록

As oxide semiconductors are emerging as key materials for next-generation semiconductor devices, aggressive scaling requirements in technologies such as monolithic 3D integration necessitate a reduction in channel thickness. However, the electrical performance of oxide field-effect transistors (FETs) generally deteriorates markedly as the channel thickness decreases. To systematically investigate the effects of thickness scaling and the underlying mechanisms, indium-gallium-zinc-oxide (IGZO) and zinc-tin-oxide (ZTO) FETs were fabricated and their electrical characteristics were analyzed as a function of channel thickness. ZTO FETs exhibited a mobility of 37.8 cm2/V & sdot;s at a channel thickness of 5.1 nm, which decreased to 1.43 cm2/V & sdot;s at 2.7 nm, while consistently outperforming their IGZO counterparts across all thicknesses (cf. 5.3 nm: 10.19 cm2/V & sdot;s; 2.5 nm: 0.06 cm2/V & sdot;s). To further elucidate the degradation mechanism, activation energies associated with trap barrier heights were extracted from temperature-dependent mobility measurements. In addition, interface trap density (Dit) was quantified through capacitance-voltage and capacitance-frequency analyses using the conductance method. The results revealed a clear increase in Dit with decreasing channel thickness, with ZTO FETs exhibiting lower Dit values than IGZO FETs at comparable thicknesses, in strong correlation with their higher electrical performance.

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