Acronym: SOI

Type: CNCSIS, Contract No. 233/2007 (PCE)

Project Director: Dr. Corneliu Ghica

     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. .

  1. Morphological and microstructural study of specific defects induced in single-crystal silicon wafers by irradiation in hydrogen RF-plasma to elucidate the formation mechanism
  2. Evolution of the structural defects induced by hydrogenation during in-situ thermal treatments in the electron microscope
  3. Study of the morphological and microstructural transformations induced in hydrogenated silicon wafers by surface laser treatment

Project coordinator :

National Institute of Materials Physics (NIMP)
105bis Atomistilor str., Bucharest, Magurele, PO Box MG-7, zip code 077125, Romania
Phone: + 40-21-369 0185
Fax: + 40-21-369 0177

Project Director :

Dr. Corneliu Ghica, Senior Researcher I
Phone: + 40-21-369 0170 / int. 108
Fax: + 40-21-369 0177

Partner : INCDFM

Main equipment :

  1. The RF plasma installation of treatment was capacitively coupled to a 13.56 MHz radio-frequency generator.
  2. Pulsed laser with solid active environment YAG:Nd Surellite II with an average pulse duration of 5-7 ns and a variable repetition rate of 1-10 Hz. The laser source is provided with a frequency multiplication system, which allows to extract 4 harmonics with following pulse energies: 650 mJ for l=1064 nm, 350 mJ for l=532 nm, 160 mJ for l=355 nm si 100 mJ for l=266 nm.
  3. JEOL 200 CX Analytic Transmission Electron Microscope. The microscope can operate at 5 values of acceleration voltage between 40-200 kV in steps of 40kV in two working modes: transmission (TEM) with a maximum spatial resolution of 0.27 nm at 200 kV and scanning (SEM) at 4 nm resolution. The microscope has specialized specimen holders, e.g. one or two tilt axes, tilt-rotation, heating-up, necessary for identification and characterization of the defect types in materials and for in-situ experiments.
  4. The TEM specimen preparation techniques: wire-saw for slicing, tripod for mechanical thinning at controlled angle, grinding and polishing machines, Zeiss Stemi 2000-C stereoscopic optical microscope and Zeiss Axio Observer A1m reversed metallographic for specimen thinning monitoring, Gatan PIPS and Gatan Dual Mill 600 ion milling installations.
  5. ESR/EPR spectrometer model Varian E12 upgraded with EMX - plus (Bruker) components. Operating parameters: frequency 9.2 – 9.9 GHz; 3.8 K < T < 500 K; magnetic field 0.03 T < B < 1.8 T;sensitivity 1.6 x 109 spins/Gauss.

Scientific and Technological Achievements

  1. Characterization and structural modeling of {111} planar defects decorated with hydrogen (published results).
  2. Identification and characterization of metastable {100} planar defects in hydrogenated Si (published results).
  3. Identification and characterization of bubbles in hydrogenated Si facilitating the smart-cut process (published results).
  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 (results under publication).
  5. Optimization of the classical thermal treatment applied to the hydrogenated Si wafers in view of partial healing of the induced defects (results under publication).
  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 (patentable results under publication)
  8. It becomes possible to extract layers of ca. 20 nm by smart-cut compared to 150-200 nm achievable at the present moment.

Published Papers

  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
    C. 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 (submitted May 04, 2010)
  6. 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
    National patent (submitted September 10, 2009)

Conferences & Workshops

  1. Laser treatment of plasma hydrogenated silicon wafers
    C. Ghica, L. C. Nistor, D. Ghica, M. Stefan, B. Mironov, M. Dinescu, S. Vizireanu, G. Dinescu
    Poster presentation at E-MRS, Strasbourg, France, June 8-12, 2009.

Laboratory Networks

Under Construction

International Projects

Under Construction

Stages Activities Calendar
Stage I Activity 1. Hydrogen plasma treatments of Si wafers in different experimental conditions.< 2.5 nm.
Activity 2. Influence of the plasma parameteres on the etching of the Si wafers in function of their crystallographic orientation. SEM and AFM observations.
Activity 3. Atomic processes associated to the hydrogen diffusion in the Si lattice. RES measurements.
Activity 4. Identification of the specific defects induced by the hydrogen plasma. TEM studies on specimens prepared in plan-veiw and cross-section.
December 2008
Stage II Activity 1. Hydrogen plasma treatment of Si wafers in optimal conditions facilitating the smart-cut process.
Activity 2. Preparation of TEM specimens in cross-section and plan-view for in-situ thermal treatment experiments in the electron microscope.
Activity 3. In-situ thermal treatments inside the TEM to observe the dynamics of the extended defects during heating.
Activity 4. Participation in an international conference.
Activity 5. Elaboration of a scientific paper to be published in an ISI jurnal.
September 2009
Stage III Activity 1.Determination of the optimal conditions of laser irradiation using simulation programs, starting from the in-situ thermal treatment results.
Activity 2. Experiments of laser treatment on hydrogenated Si wafers using the irradiation conditions determined by simulation.
Activity 3. SEM and TEM examination of the hydrogenated Si wafers after the laser treatment.
Activity 4. Identification of the structural transformations occurred on the wafer surface and below the surface.
Activity 5. Participation in an international conference.
Activity 6. Elaboration of a scientific paper to be published in an ISI jurnal.
September 2010

Laboratory of Atomic Structures and Defects in Advanced Materials