Role of hydrogen at poly-Si/SiO/sub 2/ interface in trap generation by substrate hot-electron injection

Abstract

The authors investigated trap generation by substrate hot-electron injection for MOS devices in which hydrogen was intentionally incorporated by forming gas anneal. It was found that the high-temperature forming gas anneal significantly enhances both interface and oxide trap generation at oxide fields during injection above 4 MV/cm, while no enhancement has been observed below 3 MV/cm. It was also found from secondary ion mass spectroscopy (SIMS) measurements that the forming gas anneal increases the hydrogen concentration at the poly-Si/SiO/sub 2/ interface but not in the gate oxide nor at the SiO/sub 2//Si interface. Based on these experimental results, a novel trap generation model, in which hydrogen released from Si-H at the poly-Si/SiO/sub 2/ interface by hot electrons causes the enhanced trap generation, is proposed.<>