Hydrogen Behavior in Top Gate Amorphous In–Ga–Zn–O Device Fabrication Process During Gate Insulator Deposition and Gate Insulator Etching

Abstract

The hydrogen behavior in the amorphous In-Ga-Zn-O (a-IGZO) thin-film layer according to the device process with top gate structure was quantitatively investigated. The hydrogen quantities in the a-IGZO thin-film layer with gate insulator (w/GI) and after GI dry-etching were increased by 3.40×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">20</sup> and 2.50×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">20</sup> /cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , respectively, in comparison with without GI (w/o GI). In addition, the calculated carrier concentration of the a-IGZO thin-film layer by band alignment increased by 1.60×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">18</sup> and 7.38×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">17</sup> /cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , respectively, compared with w/o GI. Due to the plasma effect, the hydrogen quantity and the calculated carrier concentration in the a-IGZO thin-film layer after GI dry-etching slightly decreased from w/GI by 0.90 ×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">20</sup> and 8.62 ×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">17</sup> /cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , respectively. The increased hydrogen quantity in the a-IGZO thin-film layer can contribute to increase in carrier concentration by providing free electrons through the hydrogen reaction with oxygen ions or transition of hydrogen state. Here, we attempted to correlate the hydrogen effect to the increase of the carrier concentration through various physical analysis.