Ab initio simulations of ultrashort laser pulse interaction with Cl–Si(100): implications for atomic layer etching

Abstract

Due to the remarkable resistance of SiCl against photo-induced desorption, achieving atomic layer etching (ALE) of Cl-Si(100) through a laser-based method has remained a formidable challenge. In this study, we...

Defect-Mediated Atomic Layer Etching Processes on Cl–Si(100): An Atomistic Insight

“…Specifically, at an electric field strength of E 0 = 2.3 V/Å, the Si–Si bond lengths of the defective structure at positions 2–4 extend to 4.21, 3.90, and 3.84 Å, respectively, while those for the pristine structure reach only 2.61 Å. In the case of pristine structures, the Si–Si bond does not directly dissociate but instead oscillates along the bond direction when the electric field strength is below 2.6 V/Å . However, the introduction of a point defect lowers the intensity threshold for desorption from 2.6 to 2.1 V/Å.…”

“…It should be noted that only four Si layers were used in the rt-TDDFT calculations since these calculations are significantly time-consuming. The size of cluster was examined in our previous work to mitigate its effects on calculation results Figure a,b depicts the pristine and defective structures used for calculations, respectively.…”

“…The Hartwigsen–Goedecker–Hutter (HGH) pseudopotentials with the local density approximation functional (LDA) method were employed . The selected pseudopotentials and cluster size have been tested in our previous research . The simulation box had dimensions of 20 × 20 × 20 Å 3 with a mesh size of 0.2 Å.…”

“…It was found that electron loss between Si−Si bonds leads to the desorption of SiCl from the surface. 31,32 However, the studies above primarily focused on the removal process from pristine surfaces while neglecting defects generated during synthesis and manufacturing processes. 33−35 Particularly in the context of the laser-induced ALE process, scanning tunneling microscopy (STM) images have revealed that defects are initially generated and subsequently propagate horizontally, resulting in the atomic layer removal of GaAs under laser pulses.…”

“…Besides, the etching mechanisms of thermal ALE have been categorized into fluorination, ligand exchange, conversion, oxidation, and halogenation mechanisms, among others, as summarized in reviews. , Concerning laser-induced ALE, real-time time-dependent DFT calculations have been employed to investigate the interaction between chlorinated Si layers and pulsed lasers. It was found that electron loss between Si–Si bonds leads to the desorption of SiCl from the surface. , …”