THESIS
2023
1 online resource (83 pages) : illustrations (some color)
Abstract
Thin-film transistor (TFT) based on metal oxides (MO) prevails over silicon-based
TFTs as the potential candidates for next-generation flat-panel display. Among which
amorphous indium-gallium-zinc oxide (IGZO) has been mostly studied accredited to its
superior electrical characteristics.
Plasma treatment in chlorine (Cl
2) and boron trichloride (BCl
3) atmosphere was
discovered responsible for the formation of low-resistivity IGZO thin film during the
fabrication of elevated-metal metal-oxide (EMMO) transistor. The application of Cl
2/BCl
3
plasma in the selective metallization of top-gate self-aligned transistor’s source/drain
region unfolded when the IGZO active layer in EMMO transistors achieved repetitive low
resistivity in the following attempts.
The activation effect of Cl
2/BCl
3 plasm...[
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Thin-film transistor (TFT) based on metal oxides (MO) prevails over silicon-based
TFTs as the potential candidates for next-generation flat-panel display. Among which
amorphous indium-gallium-zinc oxide (IGZO) has been mostly studied accredited to its
superior electrical characteristics.
Plasma treatment in chlorine (Cl
2) and boron trichloride (BCl
3) atmosphere was
discovered responsible for the formation of low-resistivity IGZO thin film during the
fabrication of elevated-metal metal-oxide (EMMO) transistor. The application of Cl
2/BCl
3
plasma in the selective metallization of top-gate self-aligned transistor’s source/drain
region unfolded when the IGZO active layer in EMMO transistors achieved repetitive low
resistivity in the following attempts.
The activation effect of Cl
2/BCl
3 plasma was investigated in a systematic approach
using Cl
2/BCl
3 plasma activated IGZO thin film subsequently. The completeness of plasma activation was evaluated in terms of resistivity, uniformity and thermal stability. The
efficiency of plasma activation was explored considering the adjustable parameters
involved in plasma system. After optimizing the plasma activation process, a fabrication
window was constructed. The lower boundary achieved a resistivity of 6.5×10
-3 Ω·cm, a
uniformity of 12% and a thermal durability of 250 ℃.
After the establishment of activation recipe, a top-gate self-aligned transistor with
Cl
2/BCl
3 plasma activated source/drain region was initially fabricated. The transistor
exhibited abnormal electrical characteristics, indicating that additional problems had
aroused during the integration of transistor and plasma treatment. The following
experiments managed to eliminate the integration problems and develop the appropriate
fabrication process in a trial-and-error approach. The top-gate self-aligned transistors
fabricated achieved a converged threshold voltage of -1.14 V and a subthreshold slope of
408 mV/decade to channel length as low as 2 μm.
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