Hydrogen Bond Configuration Changes in PECVD Silicon Nitride Films During RTA

Abstract

ABSTRACTPECVD silicon rich (x<4/3) and nitrogen rich (x>4/3) silicon nitride films have been deposited using a silane, ammonia, and nitrogen mixture at 400°C in a dual frequency parallel plate reactor. From FTIR measurements, most of the bonded hydrogen was observed to be present as N-H in the nitrogen rich films and as Si-H in the silicon rich films. In this study, the movement of hydrogen in the various nitride films as a result of Rapid Thermal Annealing (RTA) in N2 for 30 seconds has been investigated. While the intensity of the N-H stretching band was always found to decrease from that measured for the as-deposited film, the intensity of the Si-H stretching band was observed to increase for anneal temperatures up to 650°C. During the anneal process some hydrogen effusion takes place and some of hydrogen changes its bonding to silicon atoms from previous nitrogen atoms in the film. Consistent with the FTIR results, Hydrogen Forward Scattering (HFS), shows that only a small amount of hydrogen effuses from the silicon nitride film as a result of the RTA process below 650°C.