Mudar Ahmed Abdulsattar, Saad Mahdi Salih, Ahmed Abdulsattar Almaroof, Adeebah Muhammedsaeed Alhilaly, Maad Ahmed Almaroof

Abstract

The oxide layer on the Si surface needs to be removed in addition to the removal of Si upper layers before many industrial manufacturing processes. Thermodynamics of removal of these layers by KOH solution is described using density functional theory including Gibbs free energy, enthalpy, and entropy. Results show that the degree of oxidation is the most effective factor in determining the possibility and speed of removal. Small SiO₂ spots on the Si substrate can be removed with mild speed. Thick SiO₂ layers are the most difficult and time-consuming layers to remove using a KOH solution. The removal of thin oxide layers on the Si surface is performed by the direct reaction of KOH molecules. Thick oxide layers are removed by the reaction of K⁺ and OH^- ions in slower reaction rates due to the hydration of these ions. The calculated thermodynamic quantities of oxidation and removal are in good agreement with experimental findings‎.