Using Phosphorus-Doped α-Si Gettering Layers to Improve NILC Poly-Si TFT Performance

Abstract

Ni-metal-induced lateral crystallization (NILC) has been utilized to fabricate polycrystalline silicon (poly-Si) thin-film transistors (TFTs). However, the current crystallization technology often leads to trapped Ni and NiSi 2 precipitates, thus degrading device performance. In this study, phosphorus-doped amorphous silicon (p-a-Si) and chemical oxide (chem-SiO 2 ) films were used as Ni-gettering layers. After a gettering process, the Ni impurity within the NILC poly-Si film and the leakage current were both reduced, while the on/off current ratio was increased. This gettering process is compatible with NILC TFT processes and suitable for large-area NILC poly-Si films.

Crystallization of amorphous silicon beyond the crystallized polycrystalline silicon region induced by metal nickel

“…By using plasma-enhanced chemical vapor deposition (PECVD) at a substrate temperature of 200 • C, 500-nm a-Si:H was deposited on Type-I samples and 50-nm a-Si:H was deposited on Type-II samples. Before the deposition of 300-nm PECVD SiO 2 and subsequent MIC windows definition, phosphorus implantation at a dosage of 1 × 10 16 cm −2 was performed selectively to 36 µm wide regions on the Type II sample to form metal-gettering regions, [17][18][19] which locates equally from two neighboring MIC windows. The 50-nm thick Ni was then deposited by electron-beam evaporation and 10 h pre-annealing at 400 • C was performed for the outdiffusion of hydrogen from the a-Si:H layer.…”

Effect of dopant on metal induced lateral crystallization rate

“…To address these problems, the metal-induced lateral crystallization (MILC) technique has been developed [9][10][11][12][13][14][15][16]. The MILC technique has several advantages, such as low-batch cost, simple processing method, low-temperature (under 570 °C) process, and high electrical performance of the device [17,18,19,20].…”