Processing and characterization of ultra-thin poly-crystalline silicon for memory and logic applications

In this work, processing and characterization of ultra-thin poly-Si are performed for memory and logic applications. Ultra-thin poly-Si layers with different thicknesses were prepared on the deposited oxide by low-pressure chemical vapor deposition (LPCVD). Deposited poly-Si were doped through POCl₃ gas-phase doping at 900 °C, in which 10-nm thickness was reduced. Afterward, post-deposition annealing (PDA) under different conditions were performed. Thicknesses of deposited poly-Si films were 20, 30, and 50 nm. The following PDA improves the crystallinity, which has been confirmed by high-resolution transmission electron microscopy (HR-TEM) with fast Fourier transform (FFT) imaging and sheet resistivity lowering. Also, superior crystalline film is observed in the thinner film and the bi-directionally arranged domains are obtained from the 40-nm poly-Si film.