Abstract
Keywords: Amorphous oxide semiconductors, Ultra-thin oxide TFTs, NBTS, PBTSRecently, amorphous oxide semiconductors have attracted much attention for BEOL-compatible electronics such as next-generation memory applications (e.g. 2T0C). For practical use of oxide TFTs in BEOL-compatible electronics, ultra-thin channel thickness is essential. However, we have recently discovered that the well-known reliability issues such as negative bias temperature stress (NBTS) and positive bias temperature stress (PBTS) become more serious in ultra-thin oxide TFTs. In this respect, we investigated on how channel thickness relates with the instabilities in this study. As seen in Fig.1, PBTS instability becomes worse with the decrease in channel thickness. It is discovered that back-channel trap states are critical to PBTS instabilities, and such a back-channel effect appears more seriously when the channel thickness decreases. More details including experimental evidence and TCAD simulation results will be discussed at the conference. Figure 1. Comparison of positive bias temperature stress (PBTS) test results of IGZO TFTs with different channel thickness (7, 15, 20, 30, 40, 60 nm).
Published Version
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