Process controllability of inductively coupled plasma-enhanced reactive sputter deposition for the fabrication of amorphous InGaZnOx channel thin-film transistors

Abstract

The process controllability of inductively coupled plasma-enhanced reactive sputter deposition for the fabrication of amorphous InGaZnOx (a-IGZO) channel thin-film transistors (TFTs) was investigated. a-IGZO film deposition with the addition of H2 gas was performed using a plasma-assisted reactive sputtering system to control the oxidation process during a-IGZO film formation by balancing the oxidation and reduction reactions. Optical emission spectroscopy measurements indicate the possibility for the oxidation reaction to be inhibited by a decrease in the density of oxygen atoms and the reduction effect of hydrogen during a-IGZO film deposition due to the addition of H2 gas. The characteristics of TFTs fabricated using a-IGZO films deposited with a plasma-enhanced magnetron sputtering deposition system were investigated. The results indicate the possibility of expanding the process window by controlling the balance between oxidation and reduction with the addition of H2 gas. TFTs with a-IGZO films that were deposited with the addition of H2 gas exhibited good performance with a field-effect mobility (μFE) of 15.3 cm2 V−1 s−1 and a subthreshold gate voltage swing (S) of 0.48 V decade−1.