A method for forming a layer on a surface in making a device, including providing a distribution member for receiving vaporized material, the distribution member having one or more walls defining a polygonal two-dimensional pattern of apertures is formed in a wall, which deliver vaporized material in a molecular flow onto the surface; providing the polygonal two-dimensional pattern of apertures to have at least four vertices, with a first set of apertures disposed at the vertices, a second set of edge apertures disposed between the apertures of the first set and defining the edges of the polygonal two-dimensional pattern, and a third set of interior apertures disposed within the periphery of the polygonal two-dimensional pattern defined by the first and second sets of apertures; and dimensioning the apertures to obtain a desired flow rate.