Reliability of Submicron Mosfet's with Deposited Gate Oxides under F-N Injection and Hot-Carrier Stress

Abstract

In this paper, submicron nMOSFET's with thin LPCVD gate oxides deposited using chemical reaction of dichlorosilane and nitrous oxide at 800 °C were evaluated. Fowler-Nordheim injection was performed to compare the resistance to electron trapping and interface-state generation of these LPCVD oxides to that of the thermally grown oxides at 850 °C. It was found that with an 850 °C 20-minute post-deposition nitrogen anneal, the LPCVD oxides exhibit comparable immunity to electron trapping as the thermal oxides. Transistor characteristics such as Δg m /g m , ΔI D /I D revealed to be similar for both oxides, but there was an order of magnitude higher ΔV t detected for the LPCVD oxide films (with/without anneal) than the thermal oxides. The mechanism responsible for the hot-carrier induced device degradation was also characterized in this study. It was found that the major source of hot-carrier damage was electron trapping for the thermal oxides and the N 2 - annealed LPCVD oxides; while for the as-deposited LPCVD oxides, both electron trapping and interface-state generation contributed to device degradation.