Determination of the Generation Depth of Ultra‐Soft X‐Ray Si <i>L</i> _<i>2,3</i> Emission in a Thin SiO ₂ Film Under Electron Beam Irradiation

ABSTRACT Nanometer‐thick silicon dioxide (SiO 2 ) films are among the key materials in micro‐ and nanoelectronic device fabrication, as the film thickness directly determines the stability of the operating characteristics of semiconductor devices and integrated circuits. Accordingly, analysis of the phase composition and chemical state of nanometer‐scale SiO 2 films is an important task. One of the effective techniques for characterizing such structures is ultra‐soft X‐ray emission spectroscopy. However, the available data on the analysis depth and the size of the generation region of ultra‐soft X‐ray radiation remain insufficiently explored. Therefore, the aim of the present study is to establish the experimental dependence of the generation depth of ultra‐soft X‐ray Si L 2 , 3 emission in a thin SiO 2 /Si film on the energy of incident (primary) electrons. To this end, a thin SiO 2 film with a thickness of approximately 20 nm was produced by thermal oxidation of silicon. The film thickness was determined by X‐ray reflectometry and found to be 18.8 nm. Ultra‐soft X‐ray emission spectroscopy data analysis showed that, even when the Si L 2 , 3 spectrum is excited by a 1 keV electron beam, the SiO 2 film with a thickness of 18.8 nm exhibits an influence from the single‐crystal silicon substrate. Thus, even at a primary electron beam energy of ~ 1 keV, the generation region of ultra‐soft X‐ray emission in the SiO 2 /Si structure exceeds 20 nm. This fact must be taken into account when investigating silicon‐based structures and its compounds of comparable thickness.