Electrical and reliability properties of thin silicon oxinitride dielectrics formed by low pressure rapid thermal chemical vapor deposition

Abstract

The electrical properties and reliability issues of MOSFETs with an ultra thin silicon oxinitride gate film (5 nm up to 8.5 nm), prepared by low pressure rapid thermal chemical vapor deposition are studied with the goal to evaluate the impact of the nitridation on the electrical properties of MOSFETs. More specifically, the wear-out and breakdown features of oxinitride dielectrics are investigated as a function of the nitrogen concentration in the film. The charge building up in the insulator bulk was evaluated while the interface reliability parameters were extracted from charge pumping and transfer characteristics measurements after constant current gate stress (1 mA cm −2). The optimum nitridation rate for minimizing the charge building up is shown to be 2–3%. However the charge-to-breakdown was found to decrease continuously after nitridation.