P‐20: Effects of N₂O Plasma Treatment Time on the Performance of Self‐Aligned Top‐Gate amorphous oxide Thin Film Transistors

Abstract

We report on the effects of N 2 O plasma treatment time on the performance of self-aligned top-gate amorphous oxide thin-film transistors (TFTs). N 2 O plasma is treated on the surface of the active layer. It is shown that the treatment effect is timedependent. With the increase of treatment time, the electrical characteristics and bias stress stability are improved significantly. However, adverse effects appear with the time prolonging due to the damage of excess plasma. The optimum performance of a-IGZO and a-IZO TFTs is obtained with the N 2 O plasma treatment time at 90s and 240s, respectively.

Near-Ideal Top-Gate Controllability of InGaZnO Thin-Film Transistors by Suppressing Interface Defects with an Ultrathin Atomic Layer Deposited Gate Insulator

“…As shown in Figure 8b, the |ΔV th | continuously increases with NBS and PBS times for ALD AlO x -gated TFTs without N 2 O pretreatment, originating from the TMA-induced Vo and −OH defects near the GI/channel interface, while the N 2 Otreated a-IGZO TFTs exhibit superior bias stabilities even with the stress time prolonged to 7200 s, benefiting from the stronger resistance of N 2 O-oxidized AOS against ALD-induced Vo generation and −OH doping. 66,68 Even when the PBS or NBS was performed at a high temperature of 80 °C, the modified SATG a-IGZO TFT with ALD-AlO x GI still exhibits no observable degradations under such severe positive or negative bias temperature stress (PBTS/NBTS), as shown in Figure 8c,d. This further confirms the ultralow defect concentrations in ALD-AlO x GI and at the N 2 O-treated IGZO/AlO x interface.…”

“…Such an increase of binding energy might imply the elevation of the Fermi level 67 or the enhanced bonding between metal and oxygen, while the latter is more consistent with the resistivity results (Figure 7a) and previous reports. 33,51,66 For the AlO xcovered a-IGZO film, both In 3d and Ga 3d peaks were positively shifted by the N 2 O pretreatment (Figure 7b,c), indicating the noticeable effect of N 2 O plasma on eliminating the impact of ALD on the a-IGZO channel. The XPS signal intensity of Zn 2p is still weak on AlO x -covered a-IGZO films.…”

Effects of Mechanical Stress on Flexible Dual‐Gate a‐InGaZnO Thin‐Film Transistors

“…Besides, to avoid the damage to IGZO, the ESL uses a lower preparation temperature which results in a deteriorated layer density and a worse interface. Although the appropriate N 2 O plasma treatment which occurs in the ESL process can improve TFT performance owing to weakly bonded oxygen, an excess treatment may generate charge trapping center in IGZO resulting in larger SS with reduced mobility . In addition, the amount of hydrogen in the ESL increases, which can act as a dopant in IGZO leading to a higher carrier concentration in back channel.…”

“…Although the appropriate N 2 O plasma treatment which occurs in the ESL process can improve TFT performance owing to weakly bonded oxygen, [27][28][29] an excess treatment may generate charge trapping center in IGZO resulting in larger SS with reduced mobility. [30] In addition, the amount of hydrogen in the ESL increases, which can act as a dopant in IGZO [26,31] leading to a higher carrier concentration in back channel. Correspondingly, there is a more negative V th in the TG-controlled performance.…”

Improvement of contact resistance in flexible a-IGZO thin-film transistors by CF4/O2 plasma treatment

“…Several groups have shown, that various plasma treatments (i.e. NH3 [17], Ar [18,19,20,21,22,23], N2 [20], NF3 [24], He [18,25], O2 [20], N2O [26], H2 [22] and recently F [27]) can change the electrical characteristics and e.g., form heavily doped n + a-IGZO. So far, there is no report on the effects of CF4/O2 plasma and, to the best of our knowledge, we apply for the first time a CF4 based plasma treatment on the contact areas of a-IGZO TFTs to investigate the contact resistance.…”