AVS 53rd International Symposium
    Plasma Science and Technology Thursday Sessions
       Session PS1-ThA

Paper PS1-ThA4
Vacuum-Ultraviolet Induced Photocurrents in Plasma-Charged, Atomic Layer Deposited, HfO2/SiO2/Si Dielectric Stacks*

Thursday, November 16, 2006, 3:00 pm, Room 2009

Session: Plasma Processing for High-K/III-V’s and Smart Materials
Presenter: G.S. Upadhyaya, University of Wisconsin-Madison
Authors: G.S. Upadhyaya, University of Wisconsin-Madison
J.L. Shohet, University of Wisconsin-Madison
Correspondent: Click to Email
Advanced MOS technologies currently utilize gate oxides so thin that any further decrease in silicon-oxide thickness results in a large increase in power consumption due to high gate-leakage current. High-K dielectric materials are being investigated in order to maintain high coupling capacitance and limiting the leakage current by using thicker gate-oxide layers. In this work, we utilize the high-K dielectric hafnium oxide because of its resistance against silicide formation. It is well known that plasma and vacuum-ultraviolet (VUV) radiation-induced damage during fabrication adversely affects device reliability by degrading the gate oxide. The VUV-radiation response of hafnium oxide is relatively unknown. To this end, we investigate the effect of VUV radiation with energies from 7 to 21 eV, which is the range of energies emitted by most processing plasmas, on uncharged as well as plasma-charged, atomic-layer deposited (ALD) HfO2/SiO2/Si dielectric stacks. The electron-storage ring at the University of Wisconsin Synchrotron Radiation Center will be used as the VUV source. By measuring the substrate and photoemission currents during irradiation and the resulting surface potential, information about the nature of traps and rate of interface state generation in dielectric layers as a function of photon energy can be obtained. Comparison of HfO2 with SiO2 dielectric layers shows that, due to the lower bandgap of HfO2, traps and interface states in HfO2 are populated at a lower VUV photon energy than for silicon oxide. This indicates that charging of HfO2 during processing may occur more easily than for SiO2. @FootnoteText@ *Worksupported by the National Science Foundation under grant No. DMR-0306582. The UW-Synchrotron is a national facility, funded by the National Science Foundation under grant No. DMR-0084402.