Highly Stable, High Mobility Al:SnZnInO Back-Channel Etch Thin-Film Transistor Fabricated Using PAN-Based Wet Etchant for Source and Drain Patterning

We report the electrical characteristics of backchannel etch (BCE) metal-oxide-semiconductor thin-film transistor (TFT) comprised of aluminum-doped tin-zinc-indium oxide (ATZIO). It has high etch selectivity in wet chemical etchants, which consist of H 3 PO 4 , CH 3 COOH, and HNO 3 . This is contrar...

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Bibliographic Details
Published in:IEEE transactions on electron devices 2015-11, Vol.62 (11), p.3653-3657
Main Authors: Cho, Sung Haeng, Ko, Jong Beom, Ryu, Min Ki, Yang, Jong-Heon, Yeom, Hye-In, Lim, Sun Kwon, Hwang, Chi-Sun, Park, Sang-Hee Ko
Format: Article
Language:English
Subjects:
acetic acid
Aluminum-doped tin-zinc-indium oxide (ATZIO)
and nitric acid (PAN) etchant for source/drain (SD)
backchannel etch thin-film transistor (BCE-TFT)
Bias
Chemicals
Drains
Etching (metallography)
high mobility
high stability
Logic gates
Metals
Oxides
Patterning
phosphoric acid
Semiconductor devices
Stress
Thermal stability
Thin film transistors
Threshold voltage
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Summary:We report the electrical characteristics of backchannel etch (BCE) metal-oxide-semiconductor thin-film transistor (TFT) comprised of aluminum-doped tin-zinc-indium oxide (ATZIO). It has high etch selectivity in wet chemical etchants, which consist of H 3 PO 4 , CH 3 COOH, and HNO 3 . This is contrary to the conventional metal-oxide-semiconductors of indium-gallium-zinc oxides, which are highly soluble in the acidic chemicals. As a result, no etch stop layer is needed to protect the backchannel from the wet etchant damage during the source and drain patterning in the bottom-gate-staggered TFT structure. This provides the possibility of oxide TFT fabrication process made as simple as that of the current amorphous silicon TFT using three or four photomasks with short channel length and less parasitic capacitance. The electrical characteristics of our ATZIO BCE-TFTs have the mobility of 21.4 cm 2 /V · s, subthreshold swing (S.S) of 0.11 V/decade, and threshold voltage of 0.8 V. In spite of the BCE structure, they have excellent stability against bias temperature stress, which shows the threshold voltage shifts of +0.75 V and -0.51 V under the prolonged positive (+20 V) and negative (-20 V) gate bias stresses for 10 000 s at 60 °C, respectively.
ISSN:0018-9383
1557-9646
DOI:10.1109/TED.2015.2479592