Several fabricating processes for ink jet printheads are disclosed, each printhead being composed of two parts aligned and bonded together. One part is a substantially flat substrate which contains on the surface thereof a lineal array of heating elements and addressing electrodes, and the second part is a substrate having at least one recess anisotropically etched therein to serve as an ink supply manifold when the two parts are bonded together. A lineal array of parallel grooves are formed in the second part, so that one end of the grooves communicate with the manifold recess an the other ends are open for use as an ink droplet expelling nozzles. Many printheads can be made simultaneously by producing a plurality of sets of heating elements array with their addressing electrodes on a silicon wafer and by placing alignment marks thereon at predetermined locations. A corresponding plurality of sets of channels and associated manifolds are produced in a second silicon wafer and, in one embodiment, alignment openings are etched thereon at predetermined locations. The two wafers are aligned via the alignment openings and alignment marks, then bonded together and diced into many separate printheads. A number of printheads can be fixedly mounted in a pagewidth configuration which confronts a moving recording medium for pagewidth printing or individual printheads may be adapted for carriage type ink jet printing.