AVS 46th International Symposium
    Nanometer-scale Science and Technology Division Friday Sessions
       Session MS+PS-FrM

Paper MS+PS-FrM2
Plasma Cleaning of Via Bottoms Following Dielectric Etching

Friday, October 29, 1999, 8:40 am, Room 611

Session: Diagnostics and Processes in Etching
Presenter: P.J. Matsuo, State University of New York at Albany
Authors: P.J. Matsuo, State University of New York at Albany
M. Schaepkens, State University of New York at Albany
G.S. Oehrlein, State University of New York at Albany
Correspondent: Click to Email
In plasma etching, aspect ratio effects have been well documented. However,the dependence of the necessary cleaning steps following the etch on feature geometry have not. Cleaning via bottoms following the dielectric etch step can be critical to achieving low resistance contacts in multi-layer metallization schemes. Reducing this resistance is a prerequisite for the proper electrical function of Cu/low-k dielectric wiring architecture. We have examined in-situ surface modifications of post-etch blanket surfaces of several materials (Si, Cu, TiN, Al), resulting from Ar and O@sub 2@ cleaning treatments, using ellipsometry and XPS. We also investigated the removal efficiency of fluorocarbon and oxide residues at via bottoms for realistic aspect ratio structures by measuring the removal rate of fluorocarbon films or oxide films during O@sub 2@ plasma and Ar sputter cleaning, respectively. Ion driven cleaning procedures such as oxide removal, do not show a significant dependence on feature aspect ratio. On blanket films, to vias with an aspect ratio of 3, Ar sputter rates of BPSG remain constant. The removal of fluorocarbon residues under high density O@sub 2@ plasma exposure is heavily dependent on the neutral flux and is reduced in accordance with geometrical shadowing offset by the constant ion component. We have also investigated the surface chemistry of the residues as a function of feature geometry and cleaning process parameters.