AVS 50th International Symposium
    Plasma Science and Technology Wednesday Sessions
       Session PS2-WeM

Paper PS2-WeM1
Ion-enhanced Etching of High-k Dielectric Films with Mass-analyzed Ion Beam Irradiation

Wednesday, November 5, 2003, 8:20 am, Room 315

Session: Etching Difficult Materials
Presenter: K. Karahashi, MIRAI-ASET, Japan
Authors: K. Karahashi, MIRAI-ASET, Japan
N. Yamagishi, MIRAI-ASET, Japan
T. Horikawa, MIRAI-ASRC/AIST, Japan
A. Toriumi, MIRAI-ASRC/AIST and University of Tokyo, Japan
Correspondent: Click to Email
As advanced high-k gate dielectrics are being developed to replace SiO@sub2@ in future generations of microelectronics devices, understanding their etch characteristics becomes vital for introducing the materials into the manufacturing process. We report on the interactions of high-k dielectrics, such as HfO@sub2@, Al@sub2@O@sub3@, with ionic species contained in plasma etching environments. To clarify the ion induced reactions in the fluorocarbon plasma, we employed the mass-analyzed ion beam apparatus that can irradiate a single ionic species to sample surfaces under an ultra-high vacuum condition. CF@sub3@@super+@, ion is found to chemically etch HfO@sub2@ and Al@sub2@O@sub3@ films, and the etch yield scaled linearly with the square root of ion energy with a threshold energy between 20 - 40 eV. This indicates that the etching reaction is limited by the momentum transfer to the etched film. Etching yields decreased monotonically with decreasing fluorine atoms contained in incident fluorocarbon ions (CF@subX@@super+@, X=1-3). In the case of CF@super+@, ion irradiation, the etching stopped after slightly etching HfO@sub2@ films. Then an amorphous fluorinated carbon (a-C:F) film was continuously deposited on the HfO@sub2@ surface. Using x-ray photoelectron spectroscopy analysis, it was confirmed that carbon accumulates on the surface at the early stage as CF@super+@ ion dose increases, so that the transition to the a-C:F deposition is caused by surface modification with CF@super+@ ion irradiation. This work was supported by NEDO.