Self-Aligned Bottom-Gate In—Ga—Zn—O Thin-Film Transistor With Source/Drain Regions Formed by Direct Deposition of Fluorinated Silicon Nitride

Abstract

We developed a bottom-gate and self-aligned In-Ga-Zn-O thin-film transistor (IGZO TFT) with source and drain (S/D) regions that were formed by a direct deposition of fluorinated silicon nitride (SiNx:F) on top of the IGZO film (IGZO/SiNx:F). The resistivity of IGZO/SiN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> :F stack for the S/D regions of the TFT (ρS/D) was highly stable after annealing, and it obtained 4.1 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> Qcm after N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> annealing at 350°C. As a result of thermally stable ρ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S/D</sub> , the TFT properties with the IGZO/SiN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> :F S/D regions improved drastically compared with those of IGZO/SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> S/D regions. The field effect mobility of 10.6 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ·V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> ·s-1 and an ON/OFF current ratio of over 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sup> were obtained after 300°C annealing. The proposed method is essential for making thermally stable S/D regions for self-aligned oxide TFTs.