AVS 47th International Symposium
    Plasma Science and Technology Wednesday Sessions
       Session PS2-WeA

Paper PS2-WeA9
Understanding the Evolution of Trench Profiles in the Via-First Dual Damascene Integration Scheme

Wednesday, October 4, 2000, 4:40 pm, Room 311

Session: Feature Evolution
Presenter: T. Kropewnicki, Applied Materials
Authors: T. Kropewnicki, Applied Materials
K. Doan, Applied Materials
B. Tang, Applied Materials
C. Björkman, Applied Materials
Correspondent: Click to Email
Many surprising shapes of via profiles and trench bottoms have been observed during trench etch of the via-first dual damascene integration scheme. The most common features are faceting of the existing via holes as the trench etch progresses and fencing around the via holes. These particular features can lead to problems during copper metallization and ultimately to device failure. Therefore, it is imperative that the evolution of these features be understood so that they can be avoided. This paper will present experimental results indicating that the evolution of these features is heavily dependent upon the existing via profile and whether bottom antireflection coating (BARC) or photoresist (PR) is in the via hole prior to starting the trench etch. The proposed mechanism for faceting of the via hole is preferential sputtering of the top edge of the via. Fencing results when BARC or PR on the via sidewall vertically mask the underlying oxide when the via wall is sloped. Our empirical model for fence and facet formation was confirmed by a simple profile simulator. Finally, several options for avoiding the evolution of fencing and faceting during the trench etch will be proposed.