Abstract This work presents a novel method of local contact openings formation in an aluminum oxide (Al₂O₃) rear surface passivation layer by the selenization of the lithium fluoride (LiF) salt on top of the Al₂O₃ for ultra-thin copper indium gallium (di)selenide (CIGS) solar cells (SCs). This study introduces the potentially cost-effective, fast, industrially viable, and environmentally friendly way to create the nano-sized contact openings with the homogeneous distribution in the thick, i.e. up to 30 nm, Al₂O₃ passivation layer. The passivation layer is deposited by atomic layer deposition, while the LiF layer is spin-coated. Selenization is done in the H₂Se atmosphere and the optimal process parameters are deduced to obtain nano-sized and uniformly allocated openings as confirmed by scanning electron microscopy images. The contact openings were produced in the different thicknesses of the alumina layer from 6 nm to 30 nm. Furthermore, the Al₂O₃ rear surface passivation layer with the contact openings was implemented into ultra-thin CIGS SC design, and one trial set was produced. We demonstrated that the created openings facilitate the effective current collection through the dielectric Al₂O₃ layer up to 30 nm thick. However, the upper limit of Al₂O₃ thickness in which the contact openings can be created by the described method is not established yet. The produced passivated CIGS SCs show increased external quantum efficiency response due to the optical enhancement of the passivated cells. However, the production of SCs on the Al₂O₃ passivation layer with the openings created by selenization of LiF is not optimized yet.