| AVS 54th International Symposium | |
| Plasma Science and Technology | Tuesday Sessions |
| Session PS-TuP |
| Session: | Plasma Science and Technology Poster Session |
| Presenter: | J.A. Kelber, University of North Texas |
| Authors: | J. Wilks, University of North Texas J.A. Kelber, University of North Texas |
| Correspondent: | Click to Email |
The continued scaling of barriers to < 4 nm thickness drives the quest for a practical single step deposition process, in contrast to the current TaN/Ta two step standard. Pure Ta deposition has been considered, but Ta deposition on OSG and related materials results in a Ta-O-C "interphase" 2-4 nm thick which inhibits Cu adhesion and prevents barrier scaling to sub-4 nm length scales. We present in-situ XPS and ex-situ AFM data indicating that 500 eV Ar ion bombardment in the presence of ammonia results in a self-limiting process involving carbon depletion and nitrogen addition to the surface region. No significant change in surface rougness is observed. The surface nitridation results in a qualitatively different response to Ta deposition: an abrupt interface with initial Ta2N formation, with subsequent Ta formation at longer deposition times. These results suggest a new direction in plasma pretreatment of OSG surfaces prior to metallization--a self-limiting surface nitridation, followed by a single step Ta PVD process resulting in a Ta2N/Ta nanoscale barrier. Further, the results observed for the ion bombardment process mimic in major respects results observed for low pressure plasma treatments--including enhanced carbon depletion due to the presence of ammonia, the self-limiting nature of the process, and nitrogen incorporation. The usefulness of such UHV-based processes as models for low-pressure plasma processing will also be discussed.