AVS 51st International Symposium
    Plasma Science and Technology Friday Sessions
       Session PS1+DI-FrM

Paper PS1+DI-FrM4
Ion-Enhanced Plasma Etching of Metal Oxides in Chlorine Based Plasmas

Friday, November 19, 2004, 9:20 am, Room 213A

Session: High K and Difficult Materials Etch
Presenter: D. Ramirez, University of California, Los Angeles
Authors: D. Ramirez, University of California, Los Angeles
Y. Ta, University of California, Los Angeles
J.P. Chang, University of California, Los Angeles
Correspondent: Click to Email
The development of plasma etching chemistries is necessary to pattern new gate dielectric materials, such as hafnium based oxides, for sub-90nm complementary metal oxide semiconductor (CMOS) devices. An electron cyclotron resonance high density plasma reactor is used in this work to study the etching of metal oxides and their corresponding metals in chlorine based chemistries. The plasma density, electron temperature and gas phase species are characterized by a Langmuir probe, an optical emission spectrometer, and a quadrupole mass spectrometer. The etching of Al@sub 2@O@sub 3@ and HfO@sub 2@ was first studied in Cl@sub 2@ and BCl@sub 3@ plasmas, to allow for studies of the etching of hafnium aluminate, Hf@sub 1-x@Al@sub x@O@sub y@. The dominant etch products of Al and Hf metals in Cl@sub 2@ and BCl@sub 3@ plasmas were metal chlorides. However, the dominant etch products of Al@sub 2@O@sub 3@ and HfO@sub 2@ in Cl@sub 2@ and BCl@sub 3@ plasmas were metal chlorides and metal boron-oxy-chlorides, respectively. These results allowed us to assess the effect of metal-oxygen bond strength on the surface etching reactions, as well as the oxygen removal mechanism in the etching of metal oxides. Enhanced surface chlorination of the metal oxide surfaces was observed with increasing ion energy, which demonstrates that the etching reaction is limited by the momentum transfer from the ions to the film surface. The etch rates of Al@sub 2@O@sub 3@ and HfO@sub 2@ and their selectivities to Si were found to increase in BCl@sub 3@ plasmas due to the increased oxygen removal rate. Etching of Hf@sub 1-x@Al@sub x@O@sub y@ will also be presented, with a focus on predicting its etch rate based on the etching of Al@sub 2@O@sub 3@ and HfO@sub 2@ individually. Finally, the application of a generalized model, developed for the etching of ZrO@sub 2@ and HfO@sub 2@, to the etching of Al@sub 2@O@sub 3@ and Hf@sub 1-x@Al@sub x@O@sub y@ in chlorine based plasmas will be discussed.