IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Engineering Monday Sessions
       Session SE-MoP

Paper SE-MoP14
Microscopic Polishing of Cu Thin Films using Atomic Force Microscopy

Monday, October 29, 2001, 5:30 pm, Room 134/135

Session: Poster Session
Presenter: H.C. Galloway, Southwest Texas State University
Authors: K.M. Fishbeck, Southwest Texas State University
M.D. Arthur, Southwest Texas State University
J.S. McDonald, Southwest Texas State University
K.L. Muessig, Southwest Texas State University
D.C. Koeck, Southwest Texas State University
H.C. Galloway, Southwest Texas State University
M.-S. Lim, University of Houston
S.S. Perry, University of Houston
Correspondent: Click to Email
Chemical Mechanical Planarization of microelectronic wafers in multiple stages of fabrication is an important process in creating efficient multilayer devices in the modern semiconductor industry. The CMP process uses a rotating pad to apply pressure to a wafer surface exposed to a polishing slurry composed of both a corrosive solution and suspended abrasive particles. In order to study the fundamental mechanisms of CMP, an Atomic Force Microscope is used in conjunction with a liquid cell to simulate the CMP process. Copper thin films grown on Si wafers are exposed to chemicals of variable composition in the liquid cell, with the force of the AFM tip itself providing the mechanical component of the CMP process. A sputtering process is used to coat the AFM cantilever tips with a thin film of alumina to more closely model a single abrasive particle in a CMP slurry. The solutions used in the liquid cell are of varied concentrations and consist of both a corrosive agent(HNO@sub 3@ or NH@sub 4@OH) and a suitable corrosion inhibitor. The materials used for both the samples and the tip coating were chosen for their relevance to current microelectronic fabrication applications, as were the solution components used in the liquid cell. In this way it is possible to study the localized effects of CMP on the exposed samples as a functions of force, solution chemistry, and exposure time. In situ AFM imaging at varying time intervals allows analysis of both material removal processes and surface topography changes.