AVS 53rd International Symposium
    Plasma Science and Technology Tuesday Sessions
       Session PS2-TuM

Paper PS2-TuM13
Enhancement of NF3 Etching Rates in PECVD Chamber Cleaning

Tuesday, November 14, 2006, 12:00 pm, Room 2011

Session: Plasma Surface Interactions I: Joint AVS-AIChE Session
Presenter: J.J. An, MIT
Authors: J.J. An, MIT
B. Bai, MIT
H.H. Sawin, MIT
Correspondent: Click to Email
In the optimization of PECVD chamber cleaning, it is important to maximize the cleaning rate and minimize the use of gases that are costly and must be treated. In conventional processes, much of the feed gases are not consumed in cleaning, but are lost by surface recombination and other processes. Using an Aston torroidal remote plasma source, we have shown the etching rate of silicon nitride using NF3 can be significantly enhanced by the addition of other gases in small amounts. The additives are composed of simple compounds providing selected amounts of C, S, and/or O to the mixture, with the performance depending on the choice and amounts of the additives. The nature of the enhancement will also be discussed. This enhancement is approximately a factor of four larger at lower silicon nitride temperatures. This lower temperature cleaning is particularly important since the chamber walls and pump exhaust tubing often require the longest time to clean. While the kinetics of this effect are not yet well understood, we will present mass spectrometer results sample by line-of-sight from the plasma source, FTIR measurements of the pump exhaust, as well as etching rate variation with gas compositions, flow rates, and sample temperature.