a method for forming a self - aligned hole through a substrate to form a fluid feed passage is provided by initially forming an insulating layer on a first side of a substrate having two opposing sides ; and forming a feature on the insulating layer . next , etch an opening through the insulating layer , such that the opening is physically aligned with the feature on the insulating layer ; and coat the feature with a layer of protective material . patterning the layer of protective material will expose the opening through the insulating layer . dry etching from the first side of the substrate forms a blind feed hole in the substrate corresponding to the location of the opening in the insulating layer , the blind feed hole including a bottom . subsequently , grind a second side of the substrate and blanket etch it to form a hole through the entire substrate .