Embodiments relate to a structure for securing a shadow mask and a susceptor where the top surface of the shadow mask mounted with the susceptor is flush with the top surface of the susceptor. When the susceptor is mounted with the shadow mask, the entire top surface of the susceptor and the shadow mask is substantially coplanar. A substrate onto which material is deposited is placed below the shadow mask. The susceptor moves below reactors for injecting materials or radicals. Since the entire top surface of the susceptor is substantially flat, the vertical distance between the reactors and the susceptor can be reduced, contributing to the overall quality of the layer formed on the substrate and reducing the materials wasted by leaking outside the gap between the susceptor and the reactors.