AVS 51st International Symposium
    Plasma Science and Technology Tuesday Sessions
       Session PS2-TuM

Paper PS2-TuM7
X-ray Photoelectron Spectroscopy Study on Walls Coatings and Passivation Layers Generated on Sidewalls Trenches during Shallow Trench Isolation Processes.

Tuesday, November 16, 2004, 10:20 am, Room 213B

Session: New Gate Conductor Etching
Presenter: C. Maurice, LTM-CNRS, France
Authors: C. Maurice, LTM-CNRS, France
B. Pelissier, LTM-CNRS, France
G. Cunge, LTM-CNRS, France
O. Joubert, LTM-CNRS, France
Correspondent: Click to Email
For IC technology where delineating ever-finer structures is critical, wafer-to-wafer reproducibility is essential. Inherent to plasma processes, the coatings deposited on the reactor walls can disturb reproducibility by influencing the plasma chemistry. Simultaneously to walls coatings formation, passivation layers issued from etch products are deposited on the sidewalls of the etched patterns. These passivation layers, mandatory in obtaining controlled profiles are dependent on reactor walls conditions. This study proposes an XPS analysis of both walls coatings and of the passivation layers deposited during Shallow Trench Isolation (STI) processes. First, using a simple piece of Al@sub2@O@sub3@ floating on top of a 200 mm diameter wafer, walls conditions have been simulated and the chemical composition of the walls coatings analyzed quasi in-situ after each etching steps of the process. Secondly, using the combined effects of geometrical shadowing (allowing the screening of photoelectrons coming from the bottoms of the patterns) and of electrostatic charging, the chemical composition of the passivation layers formed on feature sidewalls has been determined. Results validate the technique even in the case of STI etching where the passivation layers are very thick. Comparison between the results obtained on the final walls coatings and passivation layers reveals in both cases the formation of SiOCl layers and thus the important correlation between the two deposits. Comparison between SiO@sub2@ and Si@sub3@N@sub4@ hard masks is performed. The impact of CF@sub4@ addition in typical Cl@sub2@/O@sub2@ chemistries is also investigated.