Journal of Vacuum Science & Technology B, Vol.23, No.2, 389-394, 2005
Reduction of plasma-induced damage in SiO2 films during pulse-time-modulated plasma irradiation
Use of a pulse-time-modulated (TM) plasma is an effective way to reduce vacuum ultra-violet (VUV) radiation damage in Si0(2) films because such a plasma can reduce the quantity of high-energy electrons while maintaining the electron density during the off time of the TM plasma. To understand the effects of VUV radiation, we measured the VUV-induced current in Si0(2) films using a simple on-wafer monitoring technique. We found that the plasma-induced-current in the Si0(2) films strongly depended on the VUV photon energy. Under the same conditions, the density of E' centers in Si0(2) films also depended on the photon energy. That is, the plasma-induced currents in the Si0(2) films detected by on-wafer monitoring corresponded to the density of E' centers (dangling bonds) in the films. By'using a TM plasma, the plasma-induced current and the E' center density in Si0(2) films can be reduced during the plasma-off time. Consequently, use of a TM plasma can eliminate VUV radiation damage. These results also confirm that our developed on-wafer monitor can predict plasma-induced damage. (c) 2005.