Effects of PECVD oxide process in the sandwiched SOG structure on MOSFET hot-carrier reliability

In this paper, we have systematically investigated the effect of PECVD oxide process in the sandwiched SOG structure for interlevel dielectric applications on MOSFET hot-carrier reliability. Both silane-based oxide (OX) and tetraethylorthosilicate-based oxide (TEOS) were used to form various combinations with SOG as interlevel dielectrics. The influence of N/sub 2/O (N/sub 2/O-TEOS) and O/sub 2/ (O/sub 2/-TEOS) as the source gas of oxygen during the PECVD TEOS deposition was also studied. Results indicate that O/sub 2/TEOS/SOG/O/sub 2/TEOS increases the number of electron traps in the gate oxide and deteriorate SiO/sub 2/-Si interface endurance, thus reducing device lifetime. In addition, the use of OX to replace any one of the O/sub 2/-TEOS layers improves hot-carrier immunity considerably. Finally, N/sub 2/O-TEOS/SOG/OX is shown to be a very promising process due to its conformal nature over OX/SOG/OX and improved reliability over O/sub 2/-TEOS/SOG/OX.