μ-Raman Spectra Analysis of the Evolution of Hydrogen Related Defects and Void Formation in the Silicon Ion-Cut Process

摘要

Hydrogen implanted, boron doped (100) Czochralski silicon wafers, which were annealed after implantation up to 600℃, are investigated by μ Raman spectroscopy (μRS). We have studied the thermal evolution of hydrogen related defects, including vacancy-hydrogen (V_nH_m) complexes, H-saturated dangling bonds and trapped H_2 molecules. Applying temperatures above ～400℃, the hydrogen related defects and the formation of voids/platelets are distinctly modified. The measured intensity of the local vibration mode (LVM) of H_2 molecules trapped in multi-vacancy complexes at a frequency of ～3820 cm~(-1) decreases while the LVM of H_2 in platelets or larger voids (～4150 cm~(-1)) is increasing. This indicates that multi-vacancy complexes coalesce and form larger voids/platelets. Most of the V_nH_m complexes (～2000 - 2200 cm~(-1)) are dissolved during annealing at 600℃, where a thin silicon layer exfoliates due to the ion-cut mechanism. However, the Raman modes of the characteristic V_2H_6 complex, of Si-H_x bonds stemming from H-terminated surfaces and of H_2 located in voids/platelets still can be observed after a short time annealing (≤ 2 min) at 600℃.