One-to-one correspondence between nm-resolution channel crystallinity and electrical property of poly-Si TFT revealed by NBD two-dimensional imaging

We successfully established the direct correspondence between the whole channel crystallinity at nm-scale and electrical property in one and the same poly-Si thin-film transistors (TFTs). A low-damage focused ion beam (FIB) technique was newly developed for preparing site-specific nanobeam diffraction (NBD) specimen of bare channel of the TFT that was electrically evaluated in advance. We applied NBD two-dimensional imaging (2D1) to the whole channel area for acquiring massive diffraction patterns over 30,000 so that both high spatial resolution (3 nm) and large-area measurement (0.5×0.5 μm 2 ) are achieved. Our NBD-2D1 analysis definitely revealed that drain current in individual TFTs is determined by whether the electrons can travel from the source to the drain without passing through the grain boundaries inside the channel, which cannot be clearly judged by using conventional scanning/ transmission electron microscopy (S/TEM) techniques.