Improvement of oxynitride reliability by two-step N2O nitridation

The electrical reliability of gate oxynitride in metal-oxide-Si (MOS) capac itor can be clearly improved by the two-step N2O nitridation. The nitridati on with a low temperature and a short time could form a nitrogen pileup at the poly-Si/SiO2 interface. It is experimentally found that the charge-to-b reakdown is significantly increased and the hot-electron-induced flatband v oltage shift is clearly reduced. The boron penetration effects for the pMOS devices are also suppressed. The reliability improvement can be explained by the reduction of detrimental species diffused from the poly-Si, which is achieved by nitrogen pileup at the poly-Si/SiO2 interface. This approach w ould be useful for the improvement of electrical properties in the ultrathi n gate oxynitrides. (C) 1999 Elsevier Science Ltd. All rights reserved.