| AVS 55th International Symposium & Exhibition | |
| Plasma Science and Technology | Wednesday Sessions |
| Session PS1-WeM |
| Session: | Plasma-Surface Interactions in Materials Processing I |
| Presenter: | P.M. Gevers, Eindhoven University of Technology, the Netherlands |
| Authors: | P.M. Gevers, Eindhoven University of Technology, the Netherlands J.J.H. Gielis, Eindhoven University of Technology, the Netherlands H.C.W. Beijerinck, Eindhoven University of Technology, the Netherlands M.C.M. van de Sanden, Eindhoven University of Technology, the Netherlands W.M.M. Kessels, Eindhoven University of Technology, the Netherlands |
| Correspondent: | Click to Email |
Increasing demands due to miniaturization in the semiconductor industry continuously lead to new challenges for plasma-based dry etching. Fundamental studies help to address these challenges, e.g., by clarifying the etching dynamics on the microscopic level. Circumventing the complexity of etching plasmas by using a multiple-beam experiment, we have investigated etching of the archetypical model system of Si(100) with Ar+ ions and F radicals using XeF2. The surface and interface-sensitive nonlinear optical technique of second-harmonic generation (SHG) was applied to gain insight into surface related processes such as the creation of a damaged layer as well as surface defect states involving strained Si-Si bonds and Si dangling bonds. The fundamental radiation for the SHG experiments was created by an optical parametric amplifier (80 MHz, 90 fs, 0.8-1.1 eV) pumped by the regenerative amplified radiation of a Ti:sapphire oscillator. Clean H terminated Si(100) samples were exposed to well characterized beams of low energy Ar+ ions (70-1000 eV) and/or XeF2 radicals. During exposure to Ar+ ions the near surface region of the c-Si was essentially converted to an amorphous layer creating a two-layer structure. The studies were performed both spectroscopically during steady state conditions and in real time under transient conditions. Previous experiments,1,2 in the 1.3-1.8 eV energy range yielded two spatially separated contributions with a 2ω resonance around 3.4 eV associated with modified Si-Si bonds, one at the a-Si surface and one at the a-Si/c-Si interface. The present interpretation for the 0.8-1.1 eV range indicates that the main part of the SHG signal arises from the tail of those resonances, which are assigned to E’0/E1-like transitions. A simple exponential model for the real-time data shows that a third contribution is necessary to describe the data well. This third contribution appears to be temporary, i.e., it is only present during the build-up of the a-Si layer. It will be discussed that this temporary contribution might be associated to the creation of dangling bonds and it will be addressed how it yields insight into the development of the a-Si layer over time.
1 J.J.H. Gielis et al., Phys. Stat. Sol. (C) 2, 3968 (2005)
2 J.J.H. Gielis et al., Phys. Rev. B 74, 165311 (2006).