Investigation of the initial deposition steps and the interfacial layer of Atomic Layer Deposited (ALD) Al2O3 on Si

Abstract

During the first stages of Atomic Layer Deposition (ALD) of Al2O3 on silicon (Si), the substrate nature affects the surface chemistry, leading to an initial island growth mode. Furthermore, an interfacial zone develops between the Si surface and the dielectric, thus damaging the physical properties of the deposited structure. In this work, these two main shortcomings are investigated for the ALD of Al2O3 films on Si from TMA and H2O. The film and the interfacial zone are characterized by a complete range of techniques, including XRR, TEM, XPS, EDX and ToF-SIMS. In parallel, a computational model is developed to study the initial nucleation and growth steps of the film. An induction period is experimentally evidenced and numerically reproduced, together with the island growth and coalescence phenomena. The chemical composition of the (Al, O, Si) interfacial layer is precisely analyzed to get insight in the mechanisms of its formation. We show that Si oxidation occurs during the island growth, catalyzed by the presence of Al, while it is also fed by species interdiffusion through the ALD film.

Investigating the Nucleation of AlOx and HfOx ALD on Polyimide: Influence of Plasma Activation

“…At the last stages of the nucleation, the growth mechanisms were dominated by the second mechanism of lateral growth on the already deposited Al 2 O 3 and HfO 2 , as the likelihood of reactive sites on the polyimide to be vacant or even physically available was rather low. These observations clearly pointed to a nucleating mechanism based on the adsorption of precursors at reactive sites of the polyimide and further lateral growth, commonly referred to as island-coalescence nucleation or growth [34,65,70,71,102,103]. Island growth of Al 2 O 3 on H-terminated Si was already observed by selective etching of SiOx through the "defects" of the nucleating Al 2 O 3 layer [104].…”

“…The nucleation of ALD processes has been commonly studied by characterization techniques such as Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), ellipsometry, quartz microbalance (QCM), both in and ex situ, but has also been investigated using other techniques such as atomic force microscopy (AFM), scanning tunneling microscopy (STM), X-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), Auger electron spectroscopy (AES), or low energy ion scattering (LEIS) [57][58][59][60][61][62][63][64][65][66][67][68][69][70][71]. Each technique has its own advantages and disadvantages.…”

Integration of feedback control and run-to-run control for plasma enhanced atomic layer deposition of hafnium oxide thin films

“…Despite the apparent advantages of high-κ materials such as TiO 2 [1], HfO 2 [2], Al2O 3 [3,4] and ZrO 2 [5], it is challenging to deposit high-κ materials through the ALD process due to the associated issues including the halogen atom residue in films, high impurity contamination, and slow deposition rate.…”

Simulation of a Charged Al2O3 Film As An Assisting Passivation Layer For a-Si Passivated Contact p-Type Silicon Solar Cells

“…Negative charges in Al rear passivated cell [12][13][14] . This rear side passivated structure leads to a lower surface recombination loss, better light re ection inside the cell, and less suffered wafer bow for thinner wafers [15][16][17] . A passivated rear side is believed necessary for higher conversion e ciency and the possibility of thinner Si wafers application.…”