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

Paper PS2-TuM4
Etching Ruthenium with O2- and Cl2-Containing Inductively Coupled Plasma

Tuesday, November 16, 2004, 9:20 am, Room 213B

Session: New Gate Conductor Etching
Presenter: C.-C. Hsu, University of California, Berkeley
Authors: C.-C. Hsu, University of California, Berkeley
D.B. Graves, University of California, Berkeley
J.W. Coburn, University of California, Berkeley
Correspondent: Click to Email
Ruthenium (Ru) plasma etching has been studied using inductively coupled plasma (ICP) with O2- and Cl2-containing plasma, with the objective of understanding the relationship between plasma characteristics and the competition between wall deposition of etch by-products and the creation of volatile etch by-products that flow into the downstream. The ICP was characterized by in-situ ion and neutral mass spectrometers, a chamber wall-mounted quartz crystal microbalance, optical emission spectroscopy, a wall-mounted ion flux probe, and an FTIR spectrometer in the turbomolecular pump foreline. Ru films were etched from 150 mm diameter wafers placed on a rf-biased substrate. Ru can be etched readily by Ar and O2-containing plasma. Cl2 addition results in significant changes in etch rate, wall deposition behavior, and downstream etch product composition. With 10 sccm Ar and 10 sccm O2 at 10mT pressure and 100V bias voltage, a 60 angstroms/min etching rate was observed. In addition, without Cl2 addition, no RuO4 was observed in the foreline, and almost all etch by-products were deposited on the chamber wall. With Cl2 addition (Ar/O2/Cl2 plasma), the etching rate increased by a factor of 5, RuO4 was observed downstream by FTIR, and virtually zero wall deposition rate was observed. One interpretation of the observations is that chlorine addition to the Ar/O2 plasma results in a more volatile Ru-oxychloride etch product, increasing both film etch rate and chamber wall re-etch rate.