Investigation of the cut location in hydrogen implantation induced silicon surface layer exfoliation

Abstract

The physical mechanisms of hydrogen induced silicon surface layer exfoliation were investigated using the combination of ion beam analysis, secondary ion mass spectroscopy (SIMS), scanning electron microscopy (SEM), and cross section transmission electron microscopy (XTEM). A 〈100〉 oriented silicon wafer was implanted with 175 keV protons to a dose of 5×1016 cm−2. The implanted wafer was bonded to a silicon oxide capped 〈100〉 silicon wafer and then heated to an elevated temperature of 600 °C to produce exfoliation. The hydrogen-implanted sample was analyzed in the as-implanted state as well as after the cleavage of the silicon wafer. The depth distribution of the implantation damage was monitored by Rutherford backscattering spectrometry (RBS) in channeling condition and XTEM imaging. Elastic recoil detection analysis and SIMS was performed to examine the hydrogen depth distribution. Cross section SEM and RBS channeling was used to measure the thickness of the exfoliated layer after cleavage. A comparison of the results deduced from the methods listed shows conclusively that the cleavage of the silicon wafer takes place above the hydrogen concentration peak near the implantation damage peak, revealing the crucial role of the implantation damage in the crystal in terms of hydrogen induced cleavage of the silicon crystal. The stress and strain field in the proton-implantation induced damage region of the silicon crystal is proposed to explain the observed results.