Measuring vacuum ultraviolet radiation-induced damage

During plasma processing of semiconductors, ultraviolet ~UV! and vacuum ultraviolet ~VUV! radiation are present, but their effects can be difficult to separate from those due to charged particles incident on the wafer. The contribution of VUV photon irradiation to gate-oxide damage, and damage to dielectric materials in general, was examined using two measurement techniques that can predict the possibility of damage. They are ~1! surface potential measurements and ~2! electrically erasable read-only memory transistors ~CHARM-2 wafers!. To isolate the radiation effects, unpatterned oxide-coated wafers and CHARM-2 wafers were exposed to VUV synchrotron radiation. VUV exposure of dielectrics and conductors results in an accumulation of positive charge due to photoemission. As a result, it can become difficult to distinguish the photoemitted from the plasma-deposited charge. In addition, it was determined that the UV monitors on CHARM-2 wafers did not respond to VUV radiation. © 2003 American Vacuum Society. @DOI: 10.1116/1.1565152#