AVS 50th International Symposium
    Plasma Science and Technology Wednesday Sessions
       Session PS1-WeA

Paper PS1-WeA5
Reduction Mechanism of VUV Radiation Damages in Pulse-Time-Modulated Plasma Processes

Wednesday, November 5, 2003, 3:20 pm, Room 314

Session: Mechanisms in Plasma-Surface Interactions
Presenter: Y. Ishikawa, Tohoku University, Japan
Authors: Y. Ishikawa, Tohoku University, Japan
M. Okigawa, Tohoku University, Japan
S. Yamasaki, National institute of Advanced Industrial Science and Technology, Japan
S. Samukawa, Tohoku University, Japan
Correspondent: Click to Email
In plasma processing using high-density plasma, vacuum-ultraviolet (VUV) radiation damage is one of the most serious problems. The electrical characteristics of dielectrics directly exposed to plasma are affected by plasma-emitted VUV radiation. VUV radiation with a higher photon energy than the SiO@sub 2@ band gap energy (8.8 eV) can generate electron-hole pairs in the irradiated dielectric films. The generation of electron-hole pair increases the charge densities trapped in the SiO@sub 2@ bulk and SiO@sub 2@/Si interface, affecting the conductivity of the SiO@sub 2@ layer. This results in dielectric breakdown, shorter lifetime of minority carriers, and a flat band voltage shift in transistors. Thus, reducing the VUV radiation damage is important for improving the reliability of semiconductor devices. To realize these requirements, we proposed a pulse-time-modulated plasma (pulsed plasma). In this paper, to understand the reduction mechanism of VUV radiation damages using pulsed plasma, we investigated the time dependence of defects (E' center) generation in the SiO@sub 2@ film by altering the pulse-on and off time. We found that the E' center was increased during the pulse-on-time and was also reduced during the pulse-off time. It is speculated that the generation and loss of E' center was progressed at the time constant of µmseconds. As a result, the pulsed plasma could drastically reduce the generation of E' center in the SiO@sub 2@ film and could eliminate VUV radiation damages in comparison with the continuous plasma.