Park Jingyu, Go Seungwon, Chae Woojun, Ryoo Chang Il, Kim Changwook, Noh Hyungju, Kim Seonggeun, Du Ahn Byung, Cho In-Tak, Yun Pil Sang, Bae Jong Uk, Park Yoo Seok, Kim Sangwan, Kim Dae Hwan
School of Electrical Engineering, Kookmin University, Seoul, 02707, Republic of Korea.
Department of Electronic Engineering, Sogang University, Seoul, 04107, Republic of Korea.
Sci Rep. 2024 May 2;14(1):10067. doi: 10.1038/s41598-024-60288-z.
In this paper, the floating body effect (FBE) in indium-gallium-zinc-oxide (IGZO) thin-film transistor (TFT) and the mechanism of device failure caused by that are reported for the first time. If the toggle AC pulses are applied to the gate and drain simultaneously for the switching operation, the drain current of IGZO TFT increases dramatically and cannot show the on/off switching characteristics. This phenomenon was not reported before, and our study reveals that the main cause is the formation of a conductive path between the source and drain: short failure. It is attributed in part to the donor creation at the drain region during the high voltage (V) condition and in part to the donor creation at the source region during the falling edge and low voltage (V) conditions. Donor creation is attributed to the peroxide formation in the IGZO layer induced by the electrons under the high lateral field. Because the donor creation features positive charges, it lowers the threshold voltage of IGZO TFT. In detail, during the V condition, the donor creation is generated by accumulated electrons with a high lateral field at the drain region. On the other hand, the floating electrons remaining at the short falling edge (i.e., FBE of the IGZO TFT) are affected by the high lateral field at the source region during the V condition. As a result, the donor creation is generated at the source region. Therefore, the short failure occurs because the donor creations are generated and expanded to channel from the drain and source region as the AC stress accumulates. In summary, the FBE in IGZO TFT is reported, and its effect on the electrical characteristics of IGZO TFT (i.e., the short failure) is rigorously analyzed for the first time.
本文首次报道了铟镓锌氧化物（IGZO）薄膜晶体管（TFT）中的浮体效应（FBE）及其导致器件失效的机制。如果在开关操作时同时向栅极和漏极施加触发交流脉冲，IGZO TFT的漏极电流会急剧增加，无法呈现开/关切换特性。此前未报道过这种现象，我们的研究表明主要原因是源极和漏极之间形成了导电路径：短路失效。这部分归因于在高电压（V）条件下漏极区域产生施主，部分归因于在下降沿和低电压（V）条件下源极区域产生施主。施主的产生归因于在高横向场下电子在IGZO层中诱导形成过氧化物。由于施主的产生具有正电荷，它会降低IGZO TFT的阈值电压。具体而言，在V条件下，施主的产生是由漏极区域具有高横向场的累积电子引起的。另一方面，在V条件下，残留在短下降沿的浮动电子（即IGZO TFT的FBE）受到源极区域高横向场的影响。结果，在源极区域产生施主。因此，随着交流应力的累积，由于施主在漏极和源极区域产生并扩展到沟道，从而发生短路失效。总之，报道了IGZO TFT中的FBE，并首次对其对IGZO TFT电学特性的影响（即短路失效）进行了严格分析。
