A H2O vapor based dry plasma process for pre-treating and strip-cleaning a reticle, a three layer gas distribution plate assembly to control the heat load to the reticle during the plasma process, and a modified hole pattern for the GDP that further enhances stripping of resist from the edges of the reticle are disclosed. In accordance with the method of the invention, oligonucleotide tag precursors are provided in an amplicon, wherein the tag precursors each consists of one or more oligonucleotide words selected from the same minimally cross-hybridizing set of words. The structure also includes a funneled light pipe on top of the photo collection region. , such as MOS or LED, are formed in the substrate. In order to ensure that the fan impeller is securely held on the drive shaft, the screw nut exerts a pressing force on the fan impeller in a radial direction.