the thickness of the coating was measured at various points by spectroscopic ellipsometry and the thickness values are indicated on fig8 the data shows substantial non uniformity of the ald coating in particular the coating thickness varies by 300 from 50 nm to 150 nm with the mcp installed in comparison to the lt 1 thickness variation obtained in the absence of the mcp as shown in fig5 these depositions were performed at 200c using trimethyl aluminum u201c tma u201d and h 2 o precursor fig9 shows detailed plots of ald al 2 o 3 layer growth rate versus distance across 300 mm si wafer substrates coated using the cross flow system of fig2 c and 4 a note the plot labeled 1421x3 5 1 fr has no capillary glass array substrate mcp installed whereas all others do deposition conditions were as for fig8 the presence of the mcp resulted in highly non uniform layer thickness across the si wafer regardless of the many changes in process conditions made in an effort to obtain a uniform layer thickness although the mcp is referenced as an example similar porous substrates will produce the same non uniform coatings for instance substrates manufactured by sintering glass beads other porous substrates may be comprised of aerogels xerogels microfiber plates nanotube based mesh or cloth and 3d printed materials further the holes need not be a regular array of holes in certain embodiments.