A batch of wafer substrates is provided with each wafer substrate having a surface. Each surface is coated with a layer of material applied simultaneously to the surface of each of the batch of wafer substrates. The layer of material is applied to a thickness that varies less than four thickness percent across the surface and exclusive of an edge boundary and having a wafer-to-wafer thickness variation of less than three percent. The layer of material so applied is a silicon oxide, silicon nitride or silicon oxynitride with the layer of material being devoid of carbon and chlorine. Formation of silicon oxide or a silicon oxynitride requires the inclusion of a co-reactant. Silicon nitride is also formed with the inclusion of a nitrification co-reactant. A process for forming such a batch of wafer substrates involves feeding the precursor into a reactor containing a batch of wafer substrates and reacting the precursor at a wafer substrate temperature, total pressure, and precursor flow rate sufficient to create such a layer of material. The delivery of a precursor and co-reactant as needed through vertical tube injectors having multiple orifices with at least one orifice in registry with each of the batch of wafer substrates and exit slits within the reactor to create flow across the surface of each of the wafer substrates in the batch provides the within- wafer and wafer-to-wafer uniformity.