Self-Aligned Top-Gate Amorphous Zinc-Tin Oxide Thin-Film Transistor With Source/Drain Regions Doped by Al Reaction

Huan Yang,Shengdong Zhang,Lei Lu,Jiye Li,Xiaoliang Zhou

doi:10.1109/jeds.2021.3094281

Huan Yang, Shengdong Zhang + Show 3 more

Open Access

https://doi.org/10.1109/jeds.2021.3094281

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Abstract

A self-aligned fabrication process for top-gate amorphous zinc-tin oxide (a-ZTO) thin-film transistors (TFTs) is developed, in which the source/drain (S/D) doping is realized through depositing a thin aluminum (Al) film on S/D regions and performing a thermal annealing. Results indicate that a chemical oxidation-reduction reaction between Al and a-ZTO films takes place during the thermal annealing process, and shallow donors of oxygen vacancies and metal tin (Sn) interstitials are thus generated. The formed S/D regions have a high carrier concentration over 1 ×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">20</sup> cm $^{-3}$ , low sheet resistance of 0.57 k Ω/sq, and high thermal stability even in oxygen ambient. The fabricated a-ZTO TFTs exhibit excellent electrical performances, including a low channel-width-normalized S/D resistance of about 7.05 Ω cm, a high field-effect mobility of 15.7 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /Vs, a high on/off current ratio of over $10 ^{8}$ , and near-zero turn-on voltage. Moreover, good electrical stability with less than 0.2-V threshold voltage shift under ±30-V gate bias stresses is also achieved.

Highlights

AMORPHOUS metal oxide semiconductors (AOS) thin-film transistors (TFTs) have been demonstrated to have relatively high carrier mobility, good performance uniformity over large-area, and low fabrication cost, and thereby regarded as one of the most promising devices applicable to advanced large area electronics and high-end integrated circuits [1,2,3,4,5,6,7,8,9]
The In-free amorphous zinc-tin oxide (a-ZTO) has been investigated as a promising non-toxic low-cost AOS, and reasonably high performance and stability of a-ZTO TFTs have been well demonstrated in recent years [12, 15,16,17,18,19,20,21,22]
A SATG a-ZTO TFT technology featuring Al reaction doping of S/D regions has been developed

Summary

INTRODUCTION

AMORPHOUS metal oxide semiconductors (AOS) thin-film transistors (TFTs) have been demonstrated to have relatively high carrier mobility, good performance uniformity over large-area, and low fabrication cost, and thereby regarded as one of the most promising devices applicable to advanced large area electronics and high-end integrated circuits [1,2,3,4,5,6,7,8,9]. The In-free amorphous zinc-tin oxide (a-ZTO) has been investigated as a promising non-toxic low-cost AOS, and reasonably high performance and stability of a-ZTO TFTs have been well demonstrated in recent years [12, 15,16,17,18,19,20,21,22]. The applicability of the Al reacted S/D doping method for fabrication of TG a-ZTO TFTs is demonstrated well

EXPERIMENTAL DETAILS

RESULTS AND DISCUSSION

CONCLUSION