Low-energy mass-selected ion beam production of fragments from tetraethylorthosilicate for the formation of silicon dioxide film

Abstract

Fragment ions produced from tetraethylorthosilicate (TEOS) in a Freeman-type ion source were investigated using a low-energy mass-selected ion beam system and then, their mass numbers were identified. Although the chemical formulae of these fragments were not completely identified yet, the possible candidates of dominant fragment ions were C2+, C+, CH2+, O+, H2O+, Si+, SiC+, SiO+, SiH(OH)2+, Si(OH)3+, SiH(OH)(OC2H5)+, SiH(OCH3)2+, Si(OH)2(OC2H5)+, SiH(OC2H5)2+, Si(OH)(OC2H5)2+, Si(OCH3)2(OC2H5)+, Si(OCH3)(OC2H5)2+, and Si(OC2H5)3+. Among these fragment ions, Si(OH)3+ ions were mass-selected. The ion energy was approximately 50 eV. Then, the Si(OH)3+ ions were irradiated to a Si substrate and resulting deposited films were analyzed. Following the completion of the ion irradiation experiment, X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy assays of the films demonstrated the occurrence of silicon dioxide deposition. We conclude that the irradiation of the mass-selected Si(OH)3+ ions, obtained from TEOS, to substrates is useful for the secure growth of silicon dioxide films.