AVS 49th International Symposium
    Plasma Science Friday Sessions
       Session PS-FrM

Paper PS-FrM7
Electron-Stimulated Atomic Scale Recovery of Ion-Induced Damage on Si(100)

Friday, November 8, 2002, 10:20 am, Room C-103

Session: Plasma Surface Interactions II
Presenter: T. Narushima, NRI-AIST, Japan
Authors: T. Narushima, NRI-AIST, Japan
M. Kitajima, NIMS, Japan
K. Miki, NRI-AIST and NIMS, Japan
Correspondent: Click to Email
Recently, an importance of process under plasma irradiation is getting higher, because of its high reactivity and reducing process temperature. Surface damages induced by the plasma can be troubles for subsequent processes. But, effects of the plasma irradiation on the damage with atomic level have not been well studied. Previously, we reported that low energy (<40eV) electrons may be used to athermally release the compressive stress in the Si(001) surface layer induced by Ar@super +@ ions (<100eV) with using the ion and electron accelerated from Ar plasma [Narushima et al., Appl. Phys. Lett. 79, 605 (2001)]. In particular, we have strong evidence that the stress relaxation was found to depend only on the number of irradiated electrons and was independent of the total energy deposition. This indicates that complete relaxation is not promoted by a thermal activation mechanism, but by a non-thermal mechanism. In this paper, we show using scanning tunneling microscope (STM) that the underlying cause of the surface stress relaxation is athermal recrystallization of the surface atoms. Our finding is opposite to the previous report by Nakayama et al. [Phys. Rev. Lett. 82, 980 (1999)] that energetic electrons (>90eV) induce atomic scale damage. This discrepancy may be explained if we delineate 40-90 eV (in the case of Si) as the threshold between thermal and athermal processes for electron-surface atoms interactions. Our STM observation shows chracteristic features to support our hypothesis. The ion-bombarded surface does not have the thermally-generated 2x1 surface reconstruction, but instead a 1x1 reconstruction, which is slightly closer to positions of a 'bulk terminated' surface.