Silicon exfoliation by hydrogen implantation: Actual nature of precursor defects

Pauline Sylvia Pokam Kuisseu (1, 2) , Timothee Pingault (1, 2) , Esidor Ntsoenzok (1, 2) , Gabrielle Regula (3) , Frederic Mazen (4) , Audrey Sauldubois (2) , Caroline Andreazza (5, 2)

1 CEMHTI - Conditions Extrêmes et Matériaux : Haute Température et Irradiation
2 UO - Université d'Orléans
3 IM2NP - Institut des Matériaux, de Microélectronique et des Nanosciences de Provence
4 CEA-LETI - Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information
5 ICMN - Interfaces, Confinement, Matériaux et Nanostructures

MeV energy hydrogen implantation in silicon followed by a thermal annealing is a very smart way to produce high crystalline quality silicon substrates, much thinner than what can be obtained by diamond disk or wire sawing. Using this kerf-less approach, ultra-thin substrates with thicknesses between 15 pm and 100 pm, compatible with microelectronic and photovoltaic applications are reported. But, despite the benefits of this approach, there is still a lack of fundamental studies at this implantation energy range. However, if very few papers have addressed the MeV energy range, a lot of works have been carried out in the keV implantation energy range, which is the one used in the smart-cut (R) technology. In order to check if the nature and the growth mechanism of extended defects reported in the widely studied keV implantation energy range could be extrapolated in the MeV range, the thermal evolution of extended defects formed after MeV hydrogen implantation in (100) Si was investigated in this study. Samples were implanted at 1 MeV with different fluences ranging from 6 x 10(16) H/cm(2) to 2 x 10(17) H/cm(2) and annealed at temperatures up to 873 K. By cross-section transmission electron microscopy, we found that the nature of extended defects in the MeV range is quite different of what is observed in the keV range. In fact, in our implantation conditions, the generated extended defects are some kinds of planar clusters of gas filled lenses, instead of platelets as commonly reported in the keV energy range. This result underlines that hydrogen behaves differently when it is introduced in silicon at high or low implantation energy. The activation energy of the growth of these extended defects is independent of the chosen fluence and is between (0.5-0.6) eV, which is very close to the activation energy reported for atomic hydrogen diffusion in a perfect silicon crystal. (C) 2017 Elsevier B.V. All rights reserved.

Domaines: Micro et nanotechnologies/Microélectronique

Pauline Sylvia Pokam Kuisseu, Timothee Pingault, Esidor Ntsoenzok, Gabrielle Regula, Frederic Mazen, et al.. Silicon exfoliation by hydrogen implantation: Actual nature of precursor defects. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2017, 401, pp.38-44. ⟨10.1016/j.nimb.2017.04.033⟩. ⟨hal-01694220⟩