Structural, Compositional and Electrical Characterization of buried silicon oxide insulating layers synthesized by SIMOX process

Abstract

Silicon oxide (SiO2) buried insulating layers were synthesized by SIMOX (separation by implanted oxygen) process using 140 keV 16O+ ion implantation at fluence levels ranging from 1.0×1017 to 1.0×1018 cm−2 into <111> single crystal silicon substrates at room temperature and at elevated temperature (325 °C). The post‐implantation annealing was performed in order to recover the implantation‐induced structural damage. The structural, compositional and electrical characterization of the ion‐beam synthesized buried silicon oxide insulating layers were characterized by Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS) measurements and Current‐voltage (I–V) characteristics. The FTIR spectra of implanted samples reveal absorption band in the wavenumber range 1200–800 cm−1 associated with the stretching vibration of Si‐O bonds indicating the formation of silicon oxide. The FTIR spectra of annealed samples revealed absorption band associated with one bending vibration in addition to the asymmetric stretching vibration of Si‐O bonds. The FTIR studies show that the structures of ion‐beam synthesized buried oxide layers are strongly dependent on total ion fluence. The XRD data show the formation of silicon oxide (SiO2) structure at all ion fluences. The concentration of the formed phases is found to increase with increase in the ion fluence as well as the annealing temperature. The RBS measurements show that the thickness of the buried oxide layer increases with increase in the oxygen fluence. However, the thickness of the top silicon layer was found to decrease with increase in the ion fluence. The I‐V characteristics show that the currents flowing in buried oxide layers are ohmic in the low voltage region and space charge limited in the higher voltage range.