A thermal inkjet printhead with a monolithically fabricated nozzle plate and self-aligned ink feed hole

A monolithic thermal inkjet printhead has been developed and demonstrated to operate successfully by combining monolithic growing of a nozzle plate on the silicon substrate and electrochemical etching of silicon for an ink feed hole. For the monolithic fabrication, a multiexposure and single development (MESD) technique and Ni electroplating are used to form cavities, orifices, and the nozzle plate. Electrochemical etching, as a backend process, is applied to form an ink feed hole through the substrate, which is accurately aligned with the frontside pattern without any backside mask. The etch rate is nearly proportional to the current density up to 50 mu m/min. Experiments with a 50-mu m-diameter nozzle show ink ejection up to the operating frequency of 11 kHz with an average ink dot diameter of about 110 mu m for 0.3-A, 5-mu s current pulses.