Microstructure and interfacial states of silicon dioxide film grown by low temperature remote plasma enhanced chemical vapor deposition

Abstract

The properties of SiO2 film and the Si/SiO2 interface formed by remote plasma enhanced chemical vapor deposition with the addition of chlorine into SiH4-N2O have been investigated. With the chlorine addition, the deposition rate increased at low deposition temperatures but at temperatures above 150 degrees C, it decreased because of the desorption of surface halide species. Chlorine at the Si/SiO2 interface prevented further subcutaneous oxidation and formed strong, terminal site Si-Cl bonds which reduced the interface state density. The substitution reaction of O and H with Cl in the bulk oxide film leads to a disordered film structure and decreased hydrogen concentration. The surface roughness increased and the refractive index decreased with increased Cl-2 addition. With chlorine addition of less than 6 vol %, the interface trap density (located at similar to E-upsilon + 0.3-0.4 eV) significantly decreased down to the 1-3 X 10(11) eV cm(2) level at the Si midgap. At high chlorine partial pressure and temperature, the local interface trap density (located at similar to E-upsilon + 0.7-0.8 eV) increased due to increased structural disorder resulting from breakage of the Si-O bond. (C) 1999 American Institute of Physics. [S0021-8979(99)07714-2].