Selectively Nitrogen Doped ALD-IGZO TFTs with Extremely High Mobility and Reliability
Dong-Gyu Kim, Hyuk Choi, Yoon-Seo Kim, Donghyeon Lee, Hye‐Jin Oh, Ju Hyeok Lee, Junghwan Kim, Seung Hee Lee, Bongjin Kuh, Tae‐Won Kim, Hyun You Kim, Jin‐Seong Park
Abstract
Achieving high mobility and reliability in atomic layer deposition (ALD)-based IGZO thin-film transistors (TFTs) with an amorphous phase is vital for practical applications in relevant fields. Here, we suggest a method to effectively increase stability while maintaining high mobility by employing the selective application of nitrous oxide plasma reactant during plasma-enhanced ALD (PEALD) at 200 °C process temperature. The nitrogen-doping mechanism is highly dependent on the intrinsic carbon impurities or nature of each cation, as demonstrated by a combination of theoretical and experimental research. The Ga 2 O 3 subgap states are especially dependent on plasma reactants. Based on these insights, we can obtain high-performance indium-rich PEALD-IGZO TFTs (threshold voltage: −0.47 V; field-effect mobility: 106.5 cm 2 /(V s); subthreshold swing: 113.5 mV/decade; hysteresis: 0.05 V). In addition, the device shows minimal threshold voltage shifts of +0.45 and −0.10 V under harsh positive/negative bias temperature stress environments (field stress: ±2 MV/cm; temperature stress: 95 °C) after 10000 s.