AVS 49th International Symposium
    Plasma Science Monday Sessions
       Session PS1-MoA

Paper PS1-MoA9
Measuring Vacuum Ultraviolet Radiation-Induced Damage

Monday, November 4, 2002, 4:40 pm, Room C-103

Session: Dielectric Etch I
Presenter: J.L. Lauer, University of Wisconsin-Madison
Authors: J.L. Lauer, University of Wisconsin-Madison
J.L. Shohet, University of Wisconsin-Madison
R.W.C. Hansen, University of Wisconsin-Madison
Correspondent: Click to Email
During plasma processing, UV(ultraviolet) and VUV (ultraviolet) radiation is present, but its effects are difficult to separate from those due to charge particles incident on the wafer. To isolate the radiation effects, unpatterned oxide-coated wafers and Charm-2 wafers were exposed to UV/VUV radiation at the University of Wisconsin-Madison synchrotron. The contribution of UV/VUV photon irradiation to gate-oxide damage, and damage to dielectric materials in general, were examined using two measurement techniques that may predict the possibility of damage. They are (1) surface potential measurements and (2) electrically erasable read-only memory transistors (Charm-2 Wafers). In addition to these measurements, the current flowing to the wafer and the voltage on the substrate, were monitored during photon irradiation. Two processes, photoemission and photoconductivity, can create currents flowing across the dielectric layer, while only photoemission occurs in conductors. Positive charge appearance on the surface of dielectrics and conductors by VUV photoemission results in extraneous charge measurements with both techniques. As a result, it can become difficult to interpret the net amount charge on surfaces. In addition, it was determined that the UV monitors on Charm-2 wafers do not respond to VUV radiation.@footnote 1@ Thus, the results from both damage measurement techniques must be analyzed carefully, especially in situations where VUV generation is important, such as in processing plasmas. @FootnoteText@ @footnote 1@The authors are grateful to W. A. Lukaszek of Wafer Charging Monitors and John Hu of LSI for loaning us the Charm-2 wafers and providing the analysis of the UV/VUV exposures. This work was supported in part by the National Science Foundation under grant DMR-0084402