Objective: This project focuses on designing, building and commissioning work the atomic layer deposition (ALD) reactor for Al2O3 ultrathin film, which it will be contain specific components and a system's own control unit. Methodology: The ALD reactor was designed under a system to minimize components, flow lines and connections; to reduce manufacturing costs, volume of precursors, among others. Currently, ALD reactors are expensive to sell, maintain and replace parts. The design and manufacture of the ALD reactor manufactured at the University of Sonora (UNISON) is based on the state art with sequential binary reactions of the precursors, for the proposal for the manufacture of solar cells. Contribution: It was possible to build and commission the ALD reactor for the deposition of ultra-thin films, with the characteristics of being reproducible and scalable, which makes it attractive for commercialization. The homemade ALD reactor at UNISON is considered a very interesting equipment for the semiconductor research area, since it is possible to combine different types of materials in the form of films such as oxides and nitrides in the order of Angstroms (Ǻ).