(Invited) Novel Integration Process for IGZO MO-TFT Fabrication on Gen 8.5 PECVD and PVD Systems - A Quest to Improve TFT Stability and Mobility

Abstract

IGZO is one of the promising materials being used to make high-mobility TFTs for high-quality displays. However, a-IGZO TFTs have stability issues in addition to limited mobility (<10 cm2/V·s). AKT has made a stable a-IGZO TFT through ESL optimization and plasma treatment of the IGZO interface. AKT a-IGZO ES-TFT shows SS 0.4 ±0.1 V/dec, mobility 10 ±1.0 cm2/V·s, Von 0.25 ± 1.5V over 2200 x 2500 mm2 substrate. BTS stability range under 80oC, ±50V conditions is ~1.5V. Furthermore, another AKT MO ES-TFT shows >30 cm2/V·s mobility using multi-layer structure.

Hydrogen Barriers Based on Chemical Trapping Using Chemically Modulated Al2O3 Grown by Atomic Layer Deposition for InGaZnO Thin-Film Transistors

“…As aforementioned, hydrogen can be incorporated into a-IGZO channels via various processes, commonly used during the deposition of passivation layers or diffusion from adjacent layers during post-annealing processes. − A commonly employed process for depositing passivation layers is the plasma-enhanced chemical vapor deposition of SiN x using the SiH 4 precursor. − During this process, a large number of hydrogen atoms are incorporated into the a-IGZO layer since dissociated hydrogen atoms can easily penetrate the channel layers. − Unlike moisture or oxygen that can be blocked by high density barrier films, , hydrogen can penetrate in the atomic form via substitutional and interstitial mechanisms; , thus, it cannot be completely blocked by dense barriers. On the contrary, hydrogen can be chemically trapped in thin films by forming hydrogenated species with various high electronegative atoms, such as nitrogen, oxygen, and fluorine, having various binding energies .…”