Water-enhanced negative bias temperature instability in p-type low temperature polycrystalline silicon thin film transistors

Water-enhanced degradation of p-type low temperature polycrystalline silicon thin film transistors under negative bias temperature (NBT) condition is studied. H₂O penetration into gate oxide network and the role of H₂O during NBT stress are confirmed and clarified respectively. To prevent H₂O diffusion, a combination of a layer of PECVD SiO₂ and a layer of PECVD Si₃N₄ as passivation layers are investigated, revealing that 100 nm SiO₂ and 300 nm Si₃N₄ can effectively block H₂O diffusion and improve device NBT reliability.