Laser processing of defects induced in silicon by RF plasma hydrogenation. Contribution to the development of the SOI technology.


Project Director: Dr. Corneliu Ghica

Abstract

Researches regarding hydrogenated silicon performed along the ’80s had as objective to characterize the interaction between the hydrogen atoms/ions and the defects existing in single crystal silicon aiming at controlling the dopant activity, passivating the defects, suppressing the charge carrier traps. Studies regarding silicon hydrogenation have been relaunched in a new context, aiming at developing a new technology in the silicon industry named silicon-on-insulator (SOI). The SOI technology is based on a procedure known as smart cut as unique method to create multilayered electronic devices with an architecture of the kind single crystal / amorphous / single crystal. The main objective of this project is to investigate the laser processing of the defects associated to the hydrogen presence in the silicon matrix in the smart cut procedure, to understand the physical phenomena controlling the effectiveness of this procedure in order to transfer thin layers and to create electronic nanodevices. Silicon samples will be hydrogenated in RF plasma using various experimental parameters in order to find a correlation with the kind and spatial distribution of the induced defects. The morpho-structural characterization of the hydrogenated wafers surfaces and of the induced structural defects will be performed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron paramagnetic resonance (EPR). The evolution of the induced defects with the temperature will be studied by in-situ thermal treatments, during their observation in the electron microscope. For the shallow processing of a thin superficial layer (< 100 nm) rich in structural defects induced by hydrogenation, surface laser treatment will be applied during the project. The effect of the laser treatment over the density and spatial distribution of the structural defects will be examined by TEM.

Objectives
• Morphological and microstructural study of specific defects induced in single crystal Si wafers by treatment in hydrogen RF plasma.
• Evolution of the structural defects induced by plasma hydrogenation revealed by in situ thermal treatments during observation in the electron microscope.
• Study of the morphological and microstructural transformations induced by laser treatment in hydrogenated Si wafers
No.NameFunction
1Ghica CorneliuScientific Researcher II, Project director
2Nistor Leona CristinaScientific Researcher I
3Teodorescu Valentin SerbanScientific Researcher I
4Stefan MarianaScientific Researcher II
5Ghica DanielaScientific Researcher III
6Maraloiu Valentin AdrianPhD Student
7Mironov BrindusaMSc Student
  1. Characterization and structural modeling of {111} planar defects decorated with hydrogen.
  2. Identification and characterization of metastable {100} planar defects in hydrogenated Si.
  3. Identification and characterization of bubbles in hydrogenated Si facilitating the smart-cut process.
  4. Optimization of the hydrogen RF-plasma treatment conditions leading to the limitation to 50 nm below the surface of the material thickness affected (high density of defects) by the plasma treatment.
  5. Optimization of the classical thermal treatment applied to the hydrogenated Si wafers in view of partial healing of the induced defects.
  6. In-situ TEM observation of the defects evolution during heating (results under publication).
  7. Identification of the laser surface treatment leading to healing of the surface defects and formation of bubbles lined-up in a plane at ca. 20 nm below the surface.
  8. Combined surface treatments using H-plasma and laser facilitates exfoliation of ca. 20 nm thick layers by smart-cut compared to 150-200 nm achievable by ion implantation at the present moment

Patent applications

  1. Hydrogen RF-plasma and laser processing of structural defects in silicon facilitating the lift-off of single-crystal layers thinner than 50 nm, C. Ghica, L. C. Nistor, V. S. Teodorescu, S. Vizireanu, N. D. Scarisoreanu, OSIM no. A00706
  1. Characterization of {111} planar defects induced in silicon by hydrogen plasma treatments, C. Ghica, L. C. Nistor, H. Bender, O. Richard, G. Van Tendeloo, A. Ulyashin, Philosophical Magazine 86, 5137-5151 (2006).
  2. TEM characterization of extended defects induced in Si wafers by H plasma treatment, C. Ghica, L. C. Nistor, H. Bender, O. Richard, G. Van Tendeloo, A. Ulyashin, Journal of Physics D: Applied Physics 40, 395-400 (2007).
  3. Specificity of defects induced in silicon by RF-plasma hydrogenation, C. Ghica, L. C. Nistor, M. Stefan, D. Ghica, B. Mironov, S. Vizireanu, A. Moldovan, M. Dinescu, Applied Physics A 98, 777-785 (2010)
  4. Hydrogen-plasma induced platelets and voids in silicon wafers, Ghica, L. C. Nistor, B. Mironov, S. Vizireanu, Romanian Reports in Physics 62, 329-340 (2010).
  5. Skin layer defects in Si by optimized treatment in hydrogen RF-plasma, C. Ghica, L. C. Nistor, S. Vizireanu, G. Dinescu, A. Moldovan, M. Dinescu, Plasma Processes and Polymers 7, 986-991 (2010)

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